The most exercisable waste polystyrene plastic pre

Preparation of adhesive from waste polystyrene plastic (Part 2)

2.3 resin modification

rosin and phenolic resin make it a 1-ring open system. Furan resin and epoxy resin are good modifiers, and have good heat and water resistance. Compared with phenolic resin, the modification effect of both is better. For example, after dissolving PSF in the mixed solvent of toluene, ethyl acetate, acetone and chloroform, adding phenolic resin, the shear strength of the adhesive can reach 3.47mpa, and the uneven peel strength can reach 14.8kn/m[4]. The varnish can be prepared by adding rosin to the toluene or benzene solution of PSF, and then adding appropriate fillers and pigments to obtain various colored paints [7]. Because the stability of rosin molecules is not very good, the amount of rosin should not be too large, otherwise the bonding strength will decline and the adhesive layer will be brittle. Resin and other modifiers can also be used in the modification of adhesives at the same time to achieve more satisfactory results. For example, with ethyl acetate, acetone, cyclohexane and toluene as mixed solvents, phenolic resin and isocyanate as modifiers, the shear strength of the adhesive can reach 3 97mpa, uneven peel strength up to 15 8ｋＮ/ｍ[6]。

2.4 phthalate modification

phthalate is a plasticizer for plastics, which can improve the flexibility and toughness of adhesives. This modification method is often used for PS based self-adhesive, and sometimes it is used together with other modifiers, such as rosin, etc. For example, the composition and proportion are ps2 0kg, dibutyl phthalate 2 5kg, organic solvent 3 5kg, ethyl acetate 0 3kg self-adhesive can be pasted on the surface of glass, metal, walls and other objects, and can be reused [5]. For another example, with PSF, dibutyl phthalate, natural rubber, crude benzene and rosin as raw materials, self-adhesive can be prepared [7]

by adding appropriate fillers to the adhesive, the corresponding sealant or coating products can be prepared. For example, the adhesive made of PSF, polyvinyl alcohol, No. 50 solvent oil, toluene, dibutyl phthalate, water, surfactant octyl phenoxyethyl ether and filler can be used for sealing aluminum alloy doors and windows [8]. Another example is that PS is dissolved in the mixed solvent composed of ethyl acetate and No. 200 gasoline, then rosin is added, and bentonite, talcum powder, light calcium, pigment, desiccant, etc. are added to prepare the internal and external wall coating, which can be sprayed and brushed, with strong adhesion, fast drying speed, and smooth and flat coating [5]

through chemical reaction, the active group is grafted on the polystyrene molecular chain to make it a polar substance, which is the so-called chemical modification. The adhesive prepared from it has good polarity and good bonding performance with polar substrate. For example, after PS is dissolved in the mixed solvent of aromatic hydrocarbon and chlorinated hydrocarbon, adding electronic tensile testing machine is not just a simple tensile test activator cu2cl2, initiator butyl peroxide benzoate, adding acrylonitrile and propylene alcohol monomer at 100 ℃, after the reaction, that is, grafting active acrylonitrile and propylene alcohol groups in PS chain links, and then adding fillers, you can get adhesives with good water resistance and high bonding strength, which are widely used in construction Wood furniture and daily necessities, etc. [4]. For another example, polystyrene is grafted with acrylate and the classification body of the displacement sensor of the active single tensile testing machine. The existence of ester group in acrylate greatly improves the adhesion between the film and the substrate, and the addition of active monomer N-alkyl acrylamide can make the film cross-linking reaction in the film-forming process, giving the film good mechanical properties and weather resistance. This kind of paint can be used as building exterior wall paint [9]. Among the above adhesives and coatings, organic substances are used as solvents, which are highly toxic and cause pollution to producers, consumers and the environment. Therefore, it is of great significance to explore water-based coatings

3 water-based polystyrene adhesive and coating

adding water, surfactant or emulsifier to polystyrene adhesive, the corresponding emulsion can be prepared after emulsification, so as to reduce the proportion of organic solvents in the adhesive, reduce the harm of the adhesive and reduce the cost. Surfactants can be sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, alkyl phenol polyoxyethylene ether, etc. [13]. PS after chemical modification and grafting has good water solubility, and the water emulsion adhesive prepared from it has better stability. The water emulsion adhesive can also be further treated to partially or completely separate the organic components, further reducing the organic content in the adhesive. For example, after PS is dissolved in 1,2-dichloroethane, it is sulfonated through sulfonation reaction, then emulsified with water, distilled under reduced pressure to evaporate the organic solvent, then a water-based coating is obtained, which can be used for food packaging, internal coating of food cans, cartons and other waterproof layers [10,11]

4 future development

in the production of adhesives and their corresponding products from waste PS, a lot of research work has been carried out, and gratifying results have been achieved, which has made contributions to saving resources and reducing environmental pollution. Because this recycling method is simple, the process and technology are easy to master, and the investment is not large, medium and small enterprises can produce, so there are many such enterprises in China at present. At present, the inspection of adhesive products in China is still only for performance inspection, and the inspection of toxicity and pollution of products is not enough, and the supervision and management system of environmental pollution of manufacturers is not perfect. Therefore, environmental pollution problems are common in the production and use of adhesive products

as the date of China's accession to the WTO approaches, in addition to enterprises consciously complying with national laws and regulations on environmental protection or voluntarily carrying out ISO14000 environmental management system certification, China should strengthen the establishment of relevant indicators in adhesive standards. With the improvement of people's living standards and the strengthening of environmental protection awareness, people will pay more and more attention to the pollution of products while improving the reuse rate of waste plastics. Therefore, adhesive products with good bonding performance, high utilization rate of waste materials and little pollution are trusted by people. Therefore, adhesives and coatings with stable components, low toxicity or water-based are the development trend in the future, and they are also the future goal of researchers who will work hard in the two stages of our competition

source: Chinese plastic additives