The pressure sensitive
adhesives seen on the market are mostly polypropylene sealing, textured paper (crepe paper), and PVC electrical tape. Pressure sensitive adhesives are mainly solvent-based or latex-based adhesives of acrylic and rubber. The hot melt pressure sensitive adhesive has been developed due to the need for high speed operation, proper coating, and elimination of solvent pollution problems. It combines the characteristics of hot melt adhesive and pressure sensitive adhesive. It is solvent-free, non-polluting and easy to use. It is applied in a molten state, and a slight finger pressure is applied after cooling and solidification to have adhesion effect.
Pressure sensitive adhesive application
Pressure sensitive adhesives are used in a wide range of applications such as diapers, women's products, double-sided tape, labels, packaging, medical care, bookbinding, surface protection films, wood processing, wallpaper and shoemaking. Among them, the consumption of HMPSA for packaging is the largest, accounting for almost half of the total. The main component of the hot melt pressure sensitive adhesive is styrene thermoplastic elastomer. The hot melt pressure sensitive adhesive has the advantages of no solvent, no air pollution, and high productivity. However, the disadvantage is that heat resistance and cohesion are insufficient. New thermoplastic elastomers such as SEBS, SEPS, and epoxidized SBS are used to prepare higher performance hot melt pressure sensitive adhesives.
Types of pressure sensitive adhesives
The new acrylate block copolymer has heat resistance, oxidation stability, and UV stability. It is good for HDPE, stainless steel, glass, polystyrene, acrylic, polycarbonate, nylon, polypropylene and other materials. It can be used for medical tapes, transparent films, labels, etc. The acrylic polymer is combined with a water-soluble polymer to form a water-dispersible hot-melt pressure sensitive adhesive.
The acrylic polymer is dispersed in a weakly alkaline aqueous solution to a non-adhesive particle of 100 μ or less, and is easily separated, and is suitable for recycling old paper. The benzophenone-containing acrylate monomer is copolymerized to give a low Tg acrylic copolymer.
The heating and melting pressure sensitive adhesive
is easily crosslinked by UV irradiation. The advantage is that no photoinitiator needs to be added, and there is no problem of initiator residue. It can be coated at low temperature (120~140 °C). It has low VOC, low odor, no skin irritation and good thermal stability. The composition of the pressure sensitive adhesive is a special type of adhesive, that is, the glue is applied to the substrate and processed into a strip and supplied as a reel, including solvent activated adhesive tape, heated adhesive tape and pressure sensitive adhesive tape. For example, medically used adhesive plasters and electrical insulating adhesives are pressure sensitive adhesive tapes.
The composition of the pressure sensitive adhesive tape:
1. Pressure sensitive adhesive;
3. Underlayer treatment agent;
4. Back treatment agent
5. The main components of the paper pressure sensitive adhesive include rubber type and resin type.
For example, polyacrylate or polyvinyl ether substrates require uniformity, low stretchability and good solvent wetting, including:
For fabrics such as cotton, glass cloth or non-woven fabric.
Plastic film types such as PE, PP, PVC and polyester film.
For paper such as kraft paper, glass transparent paper.
The substrate has a degree of between 0.1 and 0.5. The function of the underlying treatment agent is to increase the adhesion strength between the adhesive and the substrate, so that the adhesive tape is removed without causing the adhesive to be detached from the substrate to stain the surface to be adhered, and the adhesive tape is reusable. A commonly used underlayer treatment agent is a chloroprene rubber partially modified with isocyanate, a modified chlorinated rubber. The back treatment agent is generally prepared from materials such as polyacrylate, PVC, cellulose derivatives or organosilicon compounds
. This can act as a release agent. For double-sided adhesive tape, if you need to add a layer of release paper, you can add a semi-hard PVC film, PP film or kraft paper.
Adhesive properties of pressure sensitive adhesive The pressure sensitive adhesive does not need to be warmed and can be bonded by finger pressure. It is an adhesive that resists peeling strength. Its adhesion characteristics are four major factors: the cohesive strength of the T (fast tack) adhesive layer; the K-adhesive force is the adhesion between the adhesive and the substrate.