1, movie surcharge
Film is one of the most important plastic products, with a wide variety and short service life, and it is one of the main varieties for recycling. Let's briefly introduce an example according to the purpose and form.
(1) agricultural film, which mainly includes plastic film and shed film, plastic film mainly includes PE film, and shed film includes PE, PE/EVA and PVC film. When recycling, we should distinguish PE and PVC films. Agricultural films are generally dirty and often contain dirt, sand, grass roots, nails, wire and so on. The recovery methods mainly include removing iron impurities and cleaning.
The use of recycled granular materials from waste agricultural films is as follows.
1, PE recycled granular materials can still be used to produce agricultural films, fertilizer packaging bags, garbage bags, agricultural recycled water pipes, fences, tree supports, pots, barrels, garbage bins, geotechnical materials, etc.
2.PVC recycled pellets can be used to produce packaging films, such as heavy packaging bags, agricultural water pipes, soles and so on. Packaging film materials include cellophane, polyethylene, polyvinyl chloride, polypropylene, EVA, PVDC, PA, PET and various composite films. After sorting and cleaning, it can be directly made into plastic products similar to agricultural films, or it can be made into various products after granulation. Composite films include composite films of different plastics and films made of plastics, paper, aluminum foil and other materials. After recycling, recycling is more complicated, for example, before recycling multilayer plastic composite films, such as PE/PP, PE/EVA/PE, PE/ adhesive /PA/ adhesive /PE, PP/PVDC, etc.
Paper-plastic composite film needs to be separated before recycling, which is also a method of paper-plastic composite separation. The separation equipment is a chrome-plated hollow cylinder with electric heating, and a hollow cylinder with blades is installed in the cylinder. The cylinder and the hollow cylinder rotate reversely, and the crushed paper-plastic mixture is added into the cylinder. After the plastic on the heated mixture is melted in the cylinder, it is discharged from the lower part of the cylinder, and the air in the hollow cylinder takes away the waste gas.
Aluminum-plastic composite film, including BOPP/ aluminum, PE/ aluminum, etc. , used for all kinds of food packaging. Used aluminum-plastic composite soft packaging bag is actually a kind of mixed waste, which is difficult to recycle. The main treatment method abroad is incineration to recover heat. There is a method to make low-grade blank products by burning aluminum and adding fillers in China, and the effect is not ideal. This paper introduces an example of making antistatic functional materials by using the conductivity of aluminum. The technological process is as follows: aluminum-plastic composite waste-cleaning-crushing-screening-granulation-aluminum powder-additive-extrusion-semi-finished product-extrusion. Cleaning the aluminum-plastic composite waste, pulverizing, sieving with 10 day sieve, and granulating. The granulation process can be carried out by the granulator of Beijing Plastic Machinery Factory. The technological conditions of granulation are as follows: water spraying: 95℃ water 0.8 liter, feeding time. Pumping time is 5min, crushing time is 10min, and each treatment is 15kg. The agglomerated material is extruded by an extruder to form a semi-finished product, and then 20% additives such as aluminum powder, flame retardant and compatilizer are added to the semi-finished product, and then the product is obtained by extrusion granulation and used as a conductive material.
3.PET film, in the plastic industry, PET is mainly used as film and bottle, while film can be used as packaging, decoration, tape substrate or capacitor insulation, PET sheet is also used as photographic film substrate, and PET is also widely used as fiber. The physical viscosity of PET for film and fiber is higher than that of PET paper for bottle, so the recycling is slightly different.
Waste from polyester film and fiber factories can be used to wait for polyester/epoxy powder coatings. Generally, these chips have a relative molecular weight of about 20,000 and a melting point of over 260 degrees, forming a single linear PET. This waste is alcoholized with polyol at 250 to 260 degrees. Low melting point oligoester with relative molecular weight of about 2000-5000 can be obtained. Adding dibasic anhydride and esterifying agent, and polycondensing at 200 ~ 220℃ to obtain the product with acid value of about 3.05 mgKOH/g, softening point of about 85 ~ 65438 005℃ and glass transition temperature of ≤50℃. This product is used to prepare polyester/epoxy powder coatings.
Polyester formula for polyester/epoxy powder coatings
raw material consumption
Polyester waste 723.6g dibasic anhydride 0.98mol.
Glycol 1.7 1 mol catalyst 0. 1%
PET industrial waste can also be used as adhesive. Osaka Industrial Research Institute of Japan and Fuji Photographic Film Co., Ltd. used the waste of PET industry to react with glycerol to make adhesives for metal bonding. PET industrial waste can be modified with adipic acid or ethylene glycol, and can also be made into hot melt adhesive for bonding flexible materials such as cloth, leather, paper, plastic and aluminum. Properties of polyester/epoxy powder coatings.
Index name technical standard index name technical standard
The appearance is smooth, with a slight orange peel luster/%> 85.
Fineness/mesh >; 180 flexibility /mn 1
Curing time/(minute/degree Celsius) 20/ 180 Hardness >: 2H
Horizontal flow /[mm(oc.min)] > 25/ 180-5 Moisture resistance (40 oc+-2 oc, RH95%+_3%)/d 2 1
At room temperature, 25%H2SO4 was soaked in acid for 90 days, and the coating was intact.
Impact strength /kN/cm 50 alkali immersion resistance 25%NaOH4 coating is intact at room temperature for 90 days.
Adhesion (grade) 1-2 salt water immersion resistance 10NaCL coating is intact at room temperature for 90 days.
Unsaturated polyester can be prepared by the reaction of waste PET film, sheet or fiber with propylene glycol, styrene, glycerol, phthalic anhydride, maleic anhydride, hydroquinone and catalyst, which can be used to make artificial marble. The recycling method of waste PET film can also refer to the recycling method of PET bottles.
Bonding properties of polyester hot melt adhesive
Bonding strength of materials
Shear strength/MPa tear strength (n/25mm) Shear strength/MPa tear strength/(n/25mm)
Cotton (plain weave) 3.07 ① 2. 10 ①
Polyester 2.93 ① 2.93 ①112.0 PET film 3.05 ① tears.
Leather (frosted) 2.27 ② 100 aluminum foil 12.90 ④ 126
Tape (for raincoats) 2.83 ①-8.83 ①
Canvas (for account) 7.60 73.0 aluminum foil 20. 13 133
Kraft paper 1.93 ③ 12.2 tinplate 1 1.85 70.3
(1) the fracture value of the material, the bonding part does not crack; ② Cortical shedding; ③ Tearing of paper layer; ④ Test value of the board as a sample.
2. recycling of bottles
Bottles include cool beverage bottles, mineral water bottles, liquid food bottles, cosmetics bottles, etc. The materials used are polyethylene (PE), polyvinyl chloride (PVC) and polyethylene terephthalate (PET). Usually mineral water bottles are made of PVC or PET, carbonated beverage bottles are made of PET, refreshing beverage bottles, and liquid food bottles are made of PVC, PE, detergent bottles and cosmetic bottles.
Generally, all kinds of recycling bottles are sorted manually first, and then recycled according to different materials. At present, many technologies and equipment have been used to recycle various bottles.
(1)PET bottle recycling. PET bottles are widely used in carbonated drinks such as Coca Cola, Pepsi Cola and Sprite. At present, most of them are composed of PET bottles and HDPE bottle bottoms. The bottle cap material is high density polyethylene, and the trademark is BOPP film. EVA adhesive is used to bond bottles. The recycling methods of polyester bottles include regeneration granulation, alcoholysis and so on. No matter which method is adopted, the first thing to do is
① Separation: the mixed additional bottles are crushed by a conveyor belt and then separated according to density.
② Regenerative granulation: Regenerative granulation can be done by an extruder. The separated PET chips are extruded by an extruder and granulated to make pellets. In order to avoid physical viscosity reduction due to water absorption during extrusion, they should be dried before extrusion. The uses of PET particles are as follows:
A. remanufacture PET bottles. The recovered particles can not be used for direct contact with food, but can be used for the middle layer of a three-layer PET bottle and then made into carbonated beverage bottles.
B spinning fiber, the recycled PET material can be used for spinning fiber, used as pillow core, mattress, sleeping bag, felt, etc.
C. Glass fiber reinforced materials. The recycled PET reinforced by glass fiber has good heat resistance and mechanical strength, and can be used to manufacture automobile parts, such as heat-resistant automobile wheel covers. The thermal deformation temperature can reach 240 degrees, the bending modulus is 9500MPa, the bending strength is 2 14 MPa and the impact strength is 15kf/m2.
D.*** Mixed modification: The recycled PET material can be mixed with other polymers * * * to make various modified materials, such as mixed with PE***, to obtain a PET*** mixture with improved impact performance, and the ratio of PE to PET is (10 ~ 50): (90 ~ 50): if a small amount of polypropylene is added.
(3) alcoholysis, that is, the PET waste is alcoholized in the presence of an alkaline catalyst, and then dibasic anhydride is added for polycondensation to obtain the product with an acid value greater than 12. Alkyd resin paint can be prepared by diluting, filtering and adding proper amount of catalyst. The following table shows the formula. The reaction temperature is 80-85 DEG C and the reaction time is 4-5 hours.
Formulation of coating prepared by alcoholysis of polyester waste
Material addition/%Material addition/%
PET material 25 N- hydroxymethyl acrylamide 2
Triethylene glycol 23 nonionic emulsifier 0.9
Dibutyl phthalate 18 anionic emulsifier 1. 1
Vinyl acetate 24 persulfate initiator 1.4 ~ 1.6
α-methylstyrene 7 water 130
Methacrylic acid 1
Another example is that PET waste reacts with polyol at 220 ~ 250℃, and insulation paint with three-dimensional network structure is prepared by solvation. The quality meets the requirements of GB6 109. ③ In addition, PET bottles can also be used to make plasticizer: 2- ethylhexyl terephthalate (DOTP), which is similar to dioctyl phthalate (DOP) in terms of electrical properties and low-temperature flexibility.
(2) The charging process of PVC bottles and the recycling process of PVC are as follows.
PVC bottles are cleaned, sorted, crushed, crushed and recycled.
Firstly, the PVC bottles were cleaned with steam and alkali liquor and the trademarks were removed. Then the PVC bottles were sorted mechanically and manually, and the sorted PVC bottles were crushed for the second time. Finally, the powder recovery product with fineness of 500~ 1200μm was obtained, and the purity could reach 99.98%.
(3) extra charge for 3)PE bottles. PE used as bottle material is mainly HDPE, including dairy bottles, food bottles and cosmetic bottles. After sorting and cleaning, the recycled HDPE bottles can be crushed and selected, and their uses are as follows:
① Use colored cola bottle bottom.
(2) The intermediate core layer used for extruding pipes.
③ Filled with talcum powder or glass fiber to make flowered teacups or injection molded products.
④ It is compounded with this fiber and used as artificial wood. Due to the poor compatibility between wood fiber and HDPE, it is necessary to add appropriate coupling agent or use activated wood fiber.
⑤ Make artificial gravel, press HDPE bottles into sheets or granules, then stick the gravel made of yarn and metal on the surface, and then mix it with concrete or asphalt for civil building materials.
3. Recycling of polystyrene foam
Polystyrene foam can be molded from polystyrene beads. Used for packaging household appliances or frozen food. There are also several instant noodle bowls made of expandable polystyrene beads by injection molding. These plastic products are huge in size and the amount of tuition and miscellaneous fees is large, so their recycling has received special attention in China.
The main ways to recover polystyrene foam are: granulating after volume reduction, using it as various filling materials after crushing, cracking to make oil or recovering styrene, etc.
(1) polystyrene foam can be made into recycled pellets by melt extrusion granulation after volume reduction, but it is bulky and usually needs volume reduction before recycling. There are mechanical method, solvent method and heating method.
(2) It can be used as filler after crushing, and polystyrene foamed plastic products can be used as filler to make various products, such as ① remodeling into foamed plastic products.
② Concrete composite board products
③ Gypsum sandwich brick
④ Used as asphalt reinforcing agent.
⑤ Used as soil improver.
(3) cracking to make oil or recovering styrene. The device for cracking waste polystyrene foam to make oil is as follows.
Pretreatment and heat treatment of waste polystyrene foam from volume reduction catalytic cracking distillation of styrene
(4) Others, waste polystyrene foam can be used to make coatings and adhesives.
(1) coating, expandable polystyrene foam can be made into coating by adding appropriate solvent after crushing, and the process flow is as follows.
Fillers, colorants
PS and ethyl acetate are over-researched, over-researched.
Ethanol, dibutyl ester, grinding the products in the ring filtration reactor.
Oxidation resin, nitrile rubber kettle
(2) Adhesive, mixed solvent of esters and benzene, waste polystyrene foam, anti-precipitant, plasticizer, phenolic resin and other additives can be added to make coatings for cement, steel and wood.
(3) preparing brominated polystyrene flame retardant by bromination. Brominated polystyrene was prepared by electrophilic substitution reaction of waste polystyrene and bromine with aluminum trichloride as catalyst. Bromine content can reach 60% ~ 70%, which is used as flame retardant for thermoplastic plastics such as PET, ABS and nylon. Brominated polystyrene has low price, good flame retardant effect and thermal stability. When the dosage is 5 phr, it has obvious flame retardant effect. When used together with antimony trioxide, it has good flame retardant synergistic effect.
4. Extra charge for plastic shoes
Plastic footwear includes foam and non-foam sandals and slippers, as well as various plastic soles. The main materials are PVC, PE, PE/EVA, etc. Before recycling, it is necessary to sort, usually by hand, and the sorted waste shoes should be recycled according to the types of materials.