Minnesota Mining and Manufacturing Company

3m Innovative Properties Company

Rudyard M Enanoza

Mark D Weigel

Joseph P Callahan, Jr

Chung I Young

Michael S Groess

The present invention provides pressure-sensitive adhesive beads that comprise a tacky pressure-sensitive adhesive core and a non-tacky shell material that surrounds the area wherein the beads are capable of being positioned via magnetic means. The present invention also provides method(s) of preparing adhesive coated substrates using pressure-sensitive adhesive bead(s) that are magnetically responsive, electrostatically responsive, or both by using magnetic forces, electrostatic forces or both.

Method of magnetically and/or electrostatically positioning

Adhesive beads comprise a core comprising a pressure sensitive adhesive material and an essentially discontinuous organic polymer disposed about the core. The beads are free-flowing at room temperature. Upon application of heat and/or pressure the core is activated and blends with the coating to provide a pressure sensitive adhesive.

Adhesive beads

The present invention provides pressure-sensitive adhesive beads that comprise a tacky pressure-sensitive adhesive core and a non-tacky shell material that surrounds the area wherein the beads are capable of being positioned via magnetic means. The present invention also provides method(s) of preparing adhesive coated substrates using pressure-sensitive adhesive bead(s) that are magnetically responsive, electrostatically responsive or both by using magnetic forces, electrostatic forces or both.

The present invention relates to a method for suspension polymerization of a pressure-sensitive acrylatre copolymer bead having a glass transition temperature of 0.degree. C. or less. The method comprises making a monomer premix comprising an acrylic acid ester of non-tertiary alcohol, the alcohol having from 1 to 14 carbon atoms, with the average number of carbon atoms being about 4 to about 12, a polar monomer copolymerizable with the acrylic acid ester, a chain transfer agent, a free-radical initiator, and a modifier moiety selected from the group consisting of 2-polystyrylethyl methacrylate macromolecular monomers, reactive zinc salts and hydrophobic silicas. The premix is then combined with a water phase containing a sufficient amount of suspending agent to form a suspension. The suspension is concurrently agitated and polymerization of the polymer premix is permitted until polymer beads are formed. The polymer beads are then collected. The amount of the modifier moiety must be sufficient to render the copolymer bead non-agglomerating at room temperature and safely handleable and transportable.

Suspension polymerization

An improved hot melt pressure sensitive adhesive composition comprises copolymerized monomeric acrylate or methacrylate ester of a non teritary alcohol, polar monomer such as acrylic acid, 2-polystyrylethyl methacrylate macromolecular monomer and sufficient zinc carboxylate to endow the composition with improved melt flow properties and cohesive strength. The invention also provides adhesive coated sheet materials comprising the adhesive composition coated onto a flexible sheet.

Acrylate hot melt adhesive containing zinc carboxylate

The present invention relates to a method for suspension polymerization of a pressure-sensitive acrylate copolymer bead having a glass transition temperature of 0.degree. C. or less. The method comprises making a monomer premix comprising an acrylic acid ester of non-tertiary alcohol, the alcohol having from 1 to 14 carbon atoms, with the average number of carbon atoms being about 4 to about 12, a polar monomer copolymerizable with the acrylic acid ester, a chain transfer agent, a free-radical initiator, and a modifier moiety selected from the group consisting of 2-polystyrylethyl methacrylate macromolecular monomers, reactive zinc salts and hydrophobic silicas. The premix is then combined with a water phase containing a sufficient amount of suspending agent to form a suspension. The suspension is concurrently agitated and polymerization of the polymer premix is permitted until polymer beads are formed. The polymer beads are then collected. The amount of the modifier moiety must be sufficient to render the copolymer bead non-agglomerating at room temperature and safely handleable and transportable.

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Woodbury, MN, United States of America

Rudyard M Enanoza