Activatable Adhesive, Labels, and Related Methods

Abstract

An activatable adhesive that is formulated to readily absorb energy from a given radiation source, an activatable adhesive label that incorporates such an activatable adhesive, a system for activating such labels, and related methods and uses are described. The activatable adhesive includes a plasticizer, a tackifier, and an adhesive base polymer that includes butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and acrylic acid.

What is claimed is: 
     
         1 . An aqueous adhesive composition which is activatable by exposure to IR radiation and exhibits pressure sensitive adhesive properties once activated by IR radiation or by heating, the adhesive composition comprising (i) an emulsion base copolymer exhibiting a glass transition temperature Tg above 25° C. and a weight average molecular weight within a range of from 10,000 Daltons to 150,000 Daltons, (ii) a solid plasticizer for such copolymer exhibiting a melting point above 40° C., and (iii) a high softening point tackifier. 
     
     
         2 . An adhesive comprising:
 an adhesive base polymer including at least one lower alkyl acrylate, styrene, methyl methacrylate, methacrylic acid, acrylic acid, at least one multifunctional monomer, and at least one chain transfer agent;   a plasticizer; and   atackifier.   
     
     
         3 . The adhesive according to  claim 2  wherein the adhesive comprises:
 from about 20% to about 35% of an adhesive base polymer; 
 from about 50% to about 75% of a plasticizer; and 
 from about 5% to about 20% of a tackifier. 
 
     
     
         4 . The adhesive according to  claim 2  wherein the adhesive base polymer includes:
 from about 5% to about 50% of at least one lower alkyl acrylate; 
 from about 20% to about 85% of styrene; 
 from about 1% to about 35% methyl methacrylate; 
 from about 0.5% to about 5% methacrylic acid; 
 from about 0.5% to about 5% acrylic acid; 
 from about 0% to about 5.0% of at least one multifunctional monomer; and 
 from about 0% to about 5.0% of at least one chain transfer agent. 
 
     
     
         5 . The adhesive according to  claim 2  wherein the at least one lower alkyl acrylate is selected from the group consisting of methyl acrylate, butyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, and combinations thereof. 
     
     
         6 . The adhesive according to  claim 5  wherein the at least one lower alkyl acrylate is butyl acrylate. 
     
     
         7 . The adhesive base polymer according to  claim 6  wherein:
 the butyl acrylate is from about 9% to about 14% of the adhesive base polymer; 
 the styrene is from about 68% to about 80% of the adhesive base polymer; 
 the methyl methacrylate is from about 2% to about 6% of the adhesive base polymer; 
 themethacrylic acid is about 1% to about 2% of the adhesive base polymer; 
 the acrylic acid is about 1% to about 2% of the adhesive base polymer; 
 the multifunctional monomer is from about 0.5% to about 2.5% of the adhesive base polymer; and 
 the chain transfer agent is from about 1.0% to about 4.0% of the adhesive base polymer. 
 
     
     
         8 . The adhesive according to  claim 2  wherein the adhesive is white. 
     
     
         9 . The adhesive according to  claim 2  wherein the adhesive does not include an additive selected from the group consisting of carbon black, graphite, an ink, a dye, a pigment, and a colorant. 
     
     
         10 . The adhesive according to  claim 2  wherein the adhesive further comprises at least one additive selected from the group consisting of carbon black, graphite, an ink, a dye, a pigment, and a colorant. 
     
     
         11 . The adhesive according to  claim 2  wherein the plasticizer is a material selected from dicyclohexyl phthalate, glyceryltribenzoate, diphenyl phthalate, 1,4-cyclohexane dimethanoldibenzoate, and combinations thereof. 
     
     
         12 . The adhesive according to  claim 2  wherein the tackifier is provided in the form of an aqueous resin ester dispersion. 
     
     
         13 . The adhesive according to  claim 2  wherein the plasticizer is configured to melt after exposure to energy. 
     
     
         14 . The adhesive according to  claim 2  wherein the adhesive is configured to be activated by exposure to energy for less than one second. 
     
     
         15 . The adhesive according to  claim 13  wherein the energy is selected from the group consisting of NIR energy, MWIR energy, IR energy, microwave energy, inductive heating energy, visible light energy, radiant heat energy, and UV energy. 
     
     
         16 . The adhesive according to  claim 14  wherein the energy has a peak wavelength from approximately 0.8 micrometer to approximately 3.0 micrometers. 
     
     
         17 . The adhesive according to  claim 2  wherein:
 the adhesive is activatable; 
 the adhesive has a tackiness; and 
 the adhesive's tackiness is maintained for at least approximately two minutes after the adhesive is activated. 
 
     
     
         18 . The adhesive of  claim 14  wherein the adhesive exhibits an open time of from 0.1 second to 72 hours. 
     
     
         19 . The adhesive of  claim 14  wherein the adhesive upon activation, exhibits an initial tack to a substrate of at least 1.0 Newton. 
     
     
         20 . The adhesive of  claim 19  wherein the substrate is selected from the group consisting of cardboard and steel. 
     
     
         21 . The adhesive of  claim 14  wherein the adhesive upon activation, exhibits an optical clarity having less than 10% haze. 
     
     
         22 . The adhesive of  claim 14  wherein the adhesive upon activation, is clear. 
     
     
         23 . The adhesive of  claim 22  wherein the adhesive remains clear for at least 1 year. 
     
     
         24 . The adhesive of  claim 2  wherein the adhesive base polymer has a weight average molecular weight within a range of 10,000 Daltons to 150,000 Daltons. 
     
     
         25 . The adhesive of  claim 14  wherein the adhesive is activated by exposure to electromagnetic radiation having a wavelength of from 0.1 micrometers to 10 micrometers. 
     
     
         26 . The adhesive of  claim 14  wherein the intensity of the electromagnetic radiation is from about 100 kW/m 2  to about 800 kW/m 2 . 
     
     
         27 . A system that is configured to facilitate the application of an activatable label to an item, the system comprising:
 a means for emitting energy; and   one or more actuators that are configured to:
 receive the activatable label, 
 transport the activatable label through the emitted energy, and 
 transport the activatable label to a position where the activatable label is applied to the item; 
   wherein the activatable label includes an adhesive having:
 i. an adhesive base polymer including butyl acrylate, styrene, methyl methacrylate, methacrylic acid, acrylic acid, at least one multifunctional monomer, and at least one chain transfer agent, 
 ii. a plasticizer, and 
 iii. a tackifier. 
   
     
     
         28 . The system according to  claim 27  wherein the one or more actuators is selected from the group consisting of a blower system, a conveyor belt, a paddle, a carrier sheet, a plunger, a vacuum drum, a roller, a vacuum belt, and a vacuum head. 
     
     
         29 . The system according to  claim 27  wherein the item is selected from the group consisting of a bottle, a can, a container, a vessel, a bag, a pouch, an envelope, a parcel, and a box. 
     
     
         30 . The system according to  claim 27  wherein the activatable label is one of a stack of precut activatable labels. 
     
     
         31 . A method for activating a label, the method comprising:
 providing the label wherein the label has a first surface that is coated with an activatable adhesive, the activatable adhesive including:
 i. an adhesive base polymer including butyl acrylate, styrene, methyl methacrylate, methacrylic acid, and acrylic acid, 
 ii. a plasticizer, and 
 iii. a tackifier; 
   providing a source of energy configured to output radiant energy; and   exposing the label to the radiant energy that is output from the source of energy so the first surface of the label becomes tacky.