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 drinks bottles are made of PET, refreshing drinks bottles, liquid food bottles are made of PVC and PE, detergent bottles, cosmetics bottles, milk bottles and lactic acid bacteria drinks are mostly made of PE.
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 is made of HDPE, and the trademark is BOPP film, which is stuck on the bottle body with EVA glue. The method of recycling polyester bottles is regeneration granulation. Alcoholysis and other methods. No matter which method is adopted, the polyester bottle should be separated from other bottles first, and the polyester bottle body should also be separated from the bottom of the bottle.
(1) separation: the mixed additional bottles enter the crusher through the conveyor belt for crushing, and then the density is separated.
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 recycled 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 to make fibers. Regenerated PET materials can be used for spinning into fibers, and can be used as pillow cores, mattresses, sleeping bags, blankets, etc.
C. Glass fiber reinforced material, 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, and its thermal deformation temperature can reach 240 degrees. The flexural modulus is 9500MPa, the flexural 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. Due to the great polarity difference between PE and PET, compatibility treatment is needed when mixing. Generally, the compatibility is improved by grafting modification of polyolefin.
(3) alcoholysis: carrying out alcoholysis on the PET waste in the presence of an alkaline catalyst, and then adding dibasic anhydride for polycondensation to obtain a product with an acid value greater than 12. Alkyd resin paint can be prepared by diluting, filtering and adding proper amount of catalyst. See the table below for 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. Waste PET bottles can also be made into adhesives and unsaturated polyester by methods similar to waste PET films.
(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. Because the compatibility between wood fiber and HDPE is poor, 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 with polystyrene beads. Foam 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 particles by melt extrusion granulation after volume reduction, but because of its huge volume, it usually needs to be reduced first and then recycled. Methods include mechanical method, solvent method and heating method.
(2) It can be used as filler after crushing, and polystyrene foam products can be used as filler to make various products after crushing. Such as (1) reforming into foam 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) Preparation of brominated polystyrene flame retardant by bromination. Using aluminum trichloride as catalyst, waste polystyrene and bromine are electrophilicly replaced to prepare brominated polystyrene with bromine content of 60% ~ 70%, which can be used as flame retardant for thermoplastics 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 can play an obvious flame retardant effect. When used together with antimony trioxide, it has a good flame retardant synergistic effect.