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Research progress and development trend of water-based paper plastic laminating adhesive

1 preface

in recent years, art prints, packaging paper, advertising calligraphy and painting, book covers and packaging paper bags and cartons are mostly pasted with a layer of polypropylene film to improve the appearance and service life of paper or prints. The color printing paper after coating is called plastic paper, also known as laminating paper. Its color is bright and dazzling, and has moisture-proof and antifouling properties, which is deeply loved by consumers. The adhesive that can stick PP film to paper is called paper plastic composite adhesive, which is referred to as laminating adhesive for short. There are several main varieties of commercially available laminating adhesives: Polyurethane two-component adhesive, EVA adhesive, SBS adhesive and polyacrylate adhesive

at present, there are three main types of paper plastic composite adhesives: solvent type, water-based (or lotion type) and solid type. Waterborne laminating adhesive has the characteristics of non-toxic, low taste, no pollution, easy coating and low cost, which is the development direction of paper plastic laminating adhesive. There are many varieties of this kind of laminating adhesive, and new types of adhesive with improved initial viscosity, drying speed and water resistance are constantly coming out. Water based laminating adhesive mainly includes polyvinyl alcohol (PVA) acetal, polyvinyl acetate, water-based two-component polyurethane, neoprene latex, composite lotion and acrylate water-based adhesive. Among them, acrylate aqueous laminating adhesive is the most widely studied and applied

2 polyvinyl alcohol (PVA) and its acetal aqueous laminating adhesive

pvac are saponified and hydrolyzed to form PVA. PVA used for aqueous laminating adhesive is the hydrolysate with low saponification degree. If a certain proportion of aldehydes (such as formaldehyde) are added to polyvinyl alcohol, under certain conditions, condensation with aldehydes can obtain laminating adhesive with water resistance, frost resistance, good adhesion, simple process and low cost. For example, an aqueous laminating adhesive prepared with polyvinyl formal as the base material does not gel below 0 ℃ without adding antifreeze

3 polyvinyl acetate aqueous laminating adhesive

polyvinyl acetate lotion has a long history of use, low price, good stability, and good initial adhesion strength. It can freely adjust the viscosity by adding fillers and plasticizers. It has good miscibility, no environmental pollution, and convenient application. It is a widely used paper plastic laminating adhesive. Bst-7 aqueous laminating adhesive developed by Wang Jinliang and others is made with vinyl acetate ethylene copolymer lotion (VAE) as the main body, adding an appropriate amount of several tackifying resins, and using phosphate ester as the softener. The test shows that for a long time, the treatment of eye diseases and eye health care and beauty care have been an important part of the medical field. Ophthalmic treatment and health care cannot be separated from the use of various biomedical materials: artificial substitutes need to be implanted for ocular organic injuries, and the experimental LCD screen will display the words "PC control", such as artificial eyeballs, artificial lacrimal ducts, etc; Artificial cornea should be implanted to help patients with severe keratopathy recover their brightness; Intraocular lens implantation is necessary for cataract surgery; Adhesives and hemostatics for ophthalmology are needed during ophthalmic surgery; The protection and correction of eye vision need corneal contact lens and other indicators, which are equivalent to the imported arocoat laminating adhesive. The peel strength is significantly higher than the latter, and the price is lower. Zhao Guofa [12] prepared VAE based laminating adhesive with a mass fraction of 46% VAE lotion, 5.8% butyl acrylate, 2% vinyl acetate, 6% rosin, 12% polyvinyl alcohol, 19% pure water, 0.05% copolymerization catalyst, etc. at a specific temperature, which has the characteristics of folding resistance and high strength. Although polyvinyl acetate aqueous laminating adhesive has obvious advantages, it also has shortcomings such as poor water resistance and easy creep of adhesive layer, which affect its use and development

since the 1950s, scientists at home and abroad have done a lot of work to improve the performance of polyvinyl acetate aqueous laminating adhesive, and also achieved some results]. For example, through the acetalization of polyvinyl alcohol, the copolymerization of vinyl acetate and methyl methacrylate lotion, and the addition of hydrophobic rosin modified resin to the polymerization monomer, a new water-resistant polyvinyl acetate aqueous laminating adhesive has been developed]. Zhangqiuhui et al. Added two complementary modifiers [18], the water-based laminating adhesive obtained has good water resistance, which exceeds the Japanese class II product standard, and the production process is simple, the raw materials are easy to obtain, and the cost is similar to that of ordinary vinyl acetate homopolymer lotion. They are excited about this.

4 aqueous two-component polyurethane laminating adhesive

aqueous vinyl polyurethane adhesive] is a two-component, with the mixture of aqueous vinyl resin, filler or surfactant as the main agent, and the mixture of polyisocyanate (and its prepolymer) and stabilizer as the crosslinking agent. Before use, the two components are mixed and then heated for rapid curing or cold pressed for rapid curing. A two-component aqueous vinyl polyurethane adhesive was obtained by adding a certain proportion of polymethylene polyphenyl polyisocyanate solution to the modified polyvinyl acetate lotion]. The adhesive can replace the common polyvinyl acetate laminating adhesive, and has been widely used in paper plastic composite. At the same time, it can also be used in printing, wood processing and other aspects. It has good water resistance and solvent resistance

5 neoprene latex aqueous laminating adhesive neoprene latex

crl-403 or crl-503 can be made into a variety of adhesives after mixing with different tackifiers, vulcanizers, fillers, stabilizers, antioxidants, etc., which can be used for paper plastic composite, as well as for bonding paper, fiber, PVC, leather, etc. 6 composite lotion water-based laminating adhesive

a kind of water-based paper plastic composite adhesive can be prepared with the mixture of SBS and epoxy resin [the mass ratio of the two is (1 ~ 3.5):1] as the base material, MMA as the modifying diluent, polyvinyl acetate lotion as the water-soluble carrier, rosin and dimer rosin as the tackifier. Polyvinyl acetate lotion accounts for about 60% of the total mass of adhesives. It is specially] reported that an adhesive made of styrene butadiene latex, ethylene vinyl acetate and acrylate or vinyl chloride ternary composite lotion and acrylate lotion mixed in a certain proportion with modifier can be used for the composite of polypropylene film and paper printing. Ye Xianke et al. Blended acrylate lotion and VAE lotion, and crosslinked them with the synthesized diamide curing agent nl-1. The resulting composite film had a solid content of 50% and a viscosity of 3pa#8226; s. Paper plastic composite does not need hot pressing, with low cost and no pollution. This new composite lotion type laminating adhesive has been widely used in paper plastic composite

6 acrylate aqueous laminating adhesive

there are many studies on acrylate aqueous laminating adhesive. A lotion paper plastic laminating adhesive is reported in the literature. The lotion with solid content of 50% is obtained by copolymerization of acrylate monomer with styrene and acrylonitrile. It is an ideal replacement product of solvent based laminating adhesive. The literature also reported a kind of lotion laminating adhesive, which contains polyacrylate and modifier, and has the characteristics of strong adhesion and good toughness. Xu zushun and others synthesized an acrylate based laminating adhesive by semi continuous seed lotion polymerization with acrylate, methacrylate, styrene and acrylonitrile as the main monomers and acrylic acid, hydroxyethyl acrylate and hydroxypropyl acrylate as the functional monomers. It is suitable for the lamination of various ink prints with polypropylene or polyester film, with high bonding strength and resistance to organic solvents. Acrylate systems generally use copolymers. Mix methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc. to adjust the softening point and toughness, or copolymerize with acrylonitrile, styrene, VAC, MMA, etc. to meet the needs of different applications. Acrylate copolymer has good thermal stability, optical stability, strong oxidation resistance, good film transparency, and high adhesion to many materials. It has been widely used in the field of paper plastic laminating adhesive

7.1 polyacrylate water-based laminating adhesive

homopolyacrylate water-based laminating adhesive can be easily prepared by using standard compounding equipment, with good adhesion to a variety of films, and good smoothness and light stability of the adhesive film. In the one component system, it still has a smooth appearance. All reactants exist in the same lotion, but no reaction occurs. After the film is formed, the active group in the polymer particles reacts with the active group in the aqueous phase to produce cross-linking and solidify, so it has a long storage life. Tanghongke et al. Made water-based double film adhesive with multi-component co polyacrylate lotion and emulsified rosin as tackifier, which has strong adhesion, good stability, excellent water and moisture resistance

7.2 fast compounding polyacrylate aqueous laminating adhesive

in the laminating adhesive technology, it is necessary to not only make the paper and plastic bond firmly, but also require fast bonding speed. There are also many researches on this aspect. For example, the high-speed sealing adhesive for composite plastic cartons developed by Jiao Jian, etc. is made by taking acrylate lotion as the main material and adding a certain amount of b-acrylic lotion, rosin, composite emulsifier, antioxidant and filler. It has excellent bonding properties under various climatic conditions and has high promotion and application value

7.3 modified acrylate waterborne laminating adhesive

polymer lotion with core/shell structure is a polymer lotion polymerized by more than two monomers with different properties in stages under certain conditions. The inner and outer sides of its lotion particles contain different components, giving the adhesive different properties. Polysiloxanes and acrylates, two substances with different chemical structures, large polar differences, and different reactivity and compatibility, are prepared by lotion polymerization to obtain a lotion with both advantages]. For example, a modified waterborne paper plastic laminating adhesive can be prepared by lotion polymerization with octamethylcyclotetrasiloxane (D4) and butyl acrylate as the main monomers, OP-10 and sodium dodecyl sulfate as emulsifiers, and potassium persulfate as initiator. The performance of the product can be adjusted by changing the amount of silicone and acrylate

7.4 emulsion free acrylate aqueous laminating adhesive

aqueous emulsion laminating adhesive contains small molecular emulsifiers, which migrate to the surface in products and adhesives, reducing the water resistance, adhesion and other physical properties of the products. In order to eliminate the adverse effects caused by emulsifiers, a new process of emulsion free polymerized paper plastic laminating adhesive was developed]. Using olefins containing - so4na as emulsified monomers, the waterborne acrylate copolymer paper plastic laminating adhesive prepared by emulsion free polymerization process has stable storage and strong adhesion. The preparation of waterborne acrylate copolymer paper plastic lamination adhesive by emulsion free polymerization is a new product with promising development prospects

8 conclusion

"green engineering" is the development direction of Chemical Technology in the 21st century. Safe, non-toxic, pollution-free, fast curing water-based laminating adhesive has been widely concerned. The products compounded with this glue will not turn yellow, and will be straight without curling. In addition, using water-based laminating adhesive and corresponding equipment for paper plastic lamination has the advantages of less investment, low energy consumption and low cost, which has important environmental protection value and considerable economic benefits

source: Chinese glue

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