Pressure-sensitive adhesives and process for preparing them

Abstract

The invention relates to a process for preparing a dispersion-based or hotmelt pressure-sensitive adhesive based on at least one polymer, which involves crosslinking the at least one polymer, the polymer having functional groups Y, the polymer additionally being admixed with at least one kind of functionalized particles which have at least one polymeric base unit, characterized in that the particles have a monomer as base unit, the monomer having at least one kind of functional groups Z which are not able to enter into any reaction with the functional group Y and which, by thermal energy, electromagnetic radiation, particulate radiation and/or sound energy, are converted into the group X, the crosslinking of the polymer being brought about at least in part by a reaction of the functional groups X of the particles and of the functional groups Y of the polymer, and additionally to pressure-sensitive adhesives based on at least one crosslinked polymer component, wherein the crosslinking of the polymer component is brought about at least partly through incorporation of functionalized particles, the particles having at least one polymeric base unit and also a monomer with one kind of functional groups Z, these groups Z, following conversion into the groups X by means of thermal energy, electromagnetic radiation, particulate radiation and/or sound energy, being capable of reacting with functional groups Y that are present in the polymer component, and also to the use of surface-modified functionalized particles having a polymeric base unit as crosslinking reagents for the crosslinking of polymers for preparing pressure-sensitive adhesives.

1 . A process for preparing a pressure-sensitive adhesive, the process comprising the steps of:
 providing a polymer, having reactive centers comprising functional groups Y,   preparing functionalized polymeric particles by emulsion polymerization, miniemulsion polymerization or microemulsion polymerization, or by dispersion polymerization, wherein the functionalized polymeric particles comprise a monomer composition, wherein the monomer composition comprises nonfunctionalized base monomers at a concentration of 60% to 100% by weight of the total monomer composition, wherein the functionalized polymeric particles comprise monomers having functional groups Z which themselves do not react with functional groups Y, but which are configured to be converted to functional groups X which are reactable with functional groups Y, wherein the functionalized polymeric particles have particle diameters that are less than 100 nm;   converting at least some of the functional groups Z of the functionalized polymeric particles, by supply of energy, into functional groups X which are capable of reacting with the functional groups Y of the polymer; and   reacting the functional groups X of the functionalized polymeric particles with the functional groups Y of the polymer to crosslink said polymer with said functionalized polymeric particles.   
     
     
         2 . The process according to  claim 1 , wherein the functionalized polymeric particles additionally have functional groups X a , where, in the process, optionally before the conversion of the functional groups Z into the functional groups X, a partial crosslinking step takes place which comprises reacting the functional groups X a  with some of the functional groups Y. 
     
     
         3 . The process according to  claim 1 , wherein the energy supplied is thermal energy, electromagnetic radiation, particulate radiation and/or sound energy. 
     
     
         4 . The process according  claim 1 , wherein the functionalized polymeric particles are present as a dispersion in water. 
     
     
         5 . The process according to  claim 1 , wherein the functionalized polymeric particles are present as a dispersion in a reactive system comprising monomers for preparing the pressure-sensitive adhesive or a polymeric binder. 
     
     
         6 . The process according to  claim 1 , wherein the functionalized polymeric particles are spherical. 
     
     
         7 . The process according to  claim 1 , wherein at least part of said functionalized polymeric particles are in the form of at least one of hollow particles and core-shell particles. 
     
     
         8 . The process according to  claim 1 , wherein the functionalized particles are present in a concentration range of 0.1% to 15% by weight based on the polymer. 
     
     
         9 . The process according to  claim 1 , wherein the conversion of the functional groups Z into the functional groups X and the reaction with the functional groups Y proceed simultaneously. 
     
     
         10 . The process according to  claim 1 , wherein the conversion of the groups Z into the groups X comprises removal of protective groups or deblocking. 
     
     
         11 . The process according to  claim 1 , wherein prior to converting said functional groups Z to said functional groups X, a formulation of said polymer having reactive centers comprising functional groups Y and said functionalized polymeric particles is applied to a support as a coating and dried. 
     
     
         12 . The process according to  claim 11 , wherein the glass transition temperature T g  of the functionalized polymeric particles is higher than the temperature at which said formulation is formed, the temperature at which said formulation is applied to said support and the temperature at which said formulation is dried after coating. 
     
     
         13 . A process for preparing a pressure-sensitive adhesive, the process comprising the steps of:
 providing a polymer, having reactive centers comprising functional groups Y,   preparing functionalized polymeric particles by emulsion polymerization, miniemulsion polymerization or microemulsion polymerization, or by dispersion polymerization, wherein the functionalized polymeric particles comprise a monomer composition, wherein the functionalized polymeric particles comprise monomers having functional groups Z which themselves do not react with functional groups Y, but which are configured to be converted to functional groups X which are reactable with functional groups Y, wherein the functionalized polymeric particles have particle diameters that are less than 100 nm and one or more functionalities selected from the group consisting of benzophenone derivatives, acetophenone derivatives, benzoin derivatives, benzyl derivatives, thioxanthone derivatives, hydrazines, amines, phenols, tosyl chlorides, isocyanates, carbamates, urea derivatives, aldehydes, carbonates, phosphines, carbodiimides, N-methylmorpholines, N-hydroxysuccinimide esters, imidazole groups, oxazolidine groups, oxazoline groups and sulfonic acid groups;   converting at least some of the functional groups Z of the functionalized polymeric particles, by supply of energy, into functional groups X which are capable of reacting with the functional groups Y of the polymer; and   reacting the functional groups X of the functionalized polymeric particles with the functional groups Y of the polymer to crosslink said polymer with said functionalized polymeric particles.   
     
     
         14 . A process for preparing a pressure-sensitive adhesive, the process comprising the steps of:
 providing a polymer, having reactive centers comprising functional groups Y,   preparing functionalized polymeric particles by emulsion polymerization, miniemulsion polymerization or microemulsion polymerization, or by dispersion polymerization, wherein the functionalized polymeric particles comprise a monomer composition, wherein the functionalized polymeric particles comprise monomers having functional groups Z which themselves do not react with functional groups Y, but which are configured to be converted to functional groups X which are reactable with functional groups Y, wherein the functionalized polymeric particles have particle diameters that are less than 100 nm, wherein the functional groups Z comprise blocked isocyanates;   converting at least some of the functional groups Z of the functionalized polymeric particles, by supply of energy, into functional groups X which are capable of reacting with the functional groups Y of the polymer; and   reacting the functional groups X of the functionalized polymeric particles with the functional groups Y of the polymer to crosslink said polymer with said functionalized polymeric particles.