Removable pressure sensitive
are gaining more and more attention in the fields of medical, automotive, household appliances, building materials, LCD liquid crystal panels, and temporary protective films on some high-gloss materials such as mirror stainless steel. Its demand and application range are expanding and showing an increasing trend.
Method for preparing removable pressure sensitive adhesive Principle of SPG membrane emulsification
The SPG film was developed and produced by a research unit in Miyazaki Prefecture, Japan. The manufacturing method is that the volcanic ash of the South Kyushu is first sintered to produce a glassy substance having a fine phase separation, and its chemical composition is CaO-Al2O3-B2O3-SiO2. Then, it is treated with an acid to remove soluble CaO and B2O, and finally a material having a uniform micro-L structure with Al2O3-SiO2 as a skeleton is formed. It is processed into a certain thickness and shape, which is called SPG film. SPG films of different pore sizes can be obtained by changes in manufacturing conditions.
The SPG membrane is used to cause the hydrophobic monomer to form minute droplets through the pores of the membrane under the action of N2 pressure. When dispersed in the aqueous phase, the droplets of the prepared emulsion are relatively uniform due to the relatively uniform pore size of the membrane. As long as the composition of the water phase is adjusted, the droplets can be stabilized to produce uniform emulsified droplets. After the polymerization, a viscous colloidal particle having a uniform particle size is obtained. Of course, the use of SPG films of different pore sizes can also produce corresponding micelles of different particle sizes.
Preparation of removable pressure sensitive adhesive
a. Preparation of membrane emulsion
The continuous phase (aqueous phase) and the dispersed phase (oil phase) are first prepared. The composition of the continuous phase was ω (deionized water) / ω (polyvinyl alcohol) / ω (sodium dodecyl sulfate) = 97.5: 2: 0.5. The composition of the dispersed phase is ω (2 - EHA) / ω (AA) / ω (BPO) = 98: 2: 0.5. The monomer was stored in the dispersed phase in the tank and extruded through a fine pore of the SP membrane into the continuous phase under the action of N2 pressure. Note that the pressure to control N2 should be moderate. An emulsified droplet of uniform size is formed, and the stability of the emulsified droplet is maintained by magnetic stirring.
The prepared emulsion was poured directly into the reaction flask to carry out polymerization. The polymerization process conditions are as follows: first, the dissolved oxygen is replaced by N2 for 1 hour under stirring. Then, the temperature was raised to 60 ° C in 0.5 h, and polymerization was carried out for 20 hours to lower the temperature to below 35 ° C.
Adding a tackifier, a thickener, a mold inhibitor, etc. to the viscous microspheres obtained after the polymerization, and stirring uniformly.
Performance and application of removable pressure sensitive adhesive The re-peelable pressure-sensitive adhesive product prepared by the SPG film emulsification method has uniform distribution of the rubber particles, and the surface of the rubber layer is flat and has good adhesive property.
The pressure-sensitive adhesive can be used for a re-peelable pressure-sensitive adhesive article which can be repeatedly used for a paste.