Methods for forming high shrink wrap label sleeves

Abstract

Methods for forming high shrink wrap label sleeves directly from a roll are disclosed herein. A seaming agent is applied to the label, where the trailing edge will overlap the leading edge to form a seam. The seaming agent is then exposed to radiation to cure the seaming agent and form a sleeve. The label comprises a film with at least one external layer that has a Hildebrand solubility parameter, and the seaming agent includes a component having a Hildebrand solubility parameter that is within 2.2 MPa1/2 or within 4.4 calories1/2·cm−3/2 of the Hildebrand solubility parameter of the external layer of the film. The seaming agent also has a viscosity of at least 1 centipoise and less than 1000 centipoise when measured at any temperature between ambient temperature and 60° C.

1 . A method for forming a high shrink wrap label sleeve, comprising:
 applying a liquid radiation-curable seaming agent to a leading edge or to a trailing edge of a high shrink label film;   wrapping the high shrink label film until the trailing edge contacts the leading edge to create a seam that joins the trailing edge of the high shrink label film to the leading edge of the high shrink label film with the liquid radiation-curable seaming agent; and   exposing the seam to radiation to form the high shrink wrap label sleeve;   wherein the high shrink label film has an external layer with a Hildebrand solubility parameter; and   wherein the liquid radiation-curable seaming agent has an immediate welding strength of greater than 2 grams within less than 0.5 seconds on an associated high shrink label film, and has a viscosity of at least 1 centipoise and less than 250 centipoise when measured at any temperature between ambient temperature and 60° C.;   wherein the liquid radiation-curable seaming agent contains:   from 24.7 wt % to 98 wt % of monomers having a molecular weight of 300 daltons (Da) or less;   from 0 to 70 wt % of an organic solvent having a molecular weight of 300 daltons (Da) or less;   from 0 wt % to 80 wt % of oligomers or polymers having a molecular weight of 300 daltons (Da) or greater; and   from 0.5 wt % to 15 wt % of a photoinitiator;   wherein when the % VOC of the liquid radiation-curable seaming agent is measured per the modified method of Example 5, the % VOC of the liquid radiation-curable seaming agent is about 30% to about 50% of the amount of the organic solvent in the liquid radiation-curable seaming agent; and   wherein a monomer or the organic solvent has a Hildebrand solubility parameter that is within 2.2 MPa 1/2  or within 4.4 calories 1/2 ·cm −3/2  of a Hildebrand solubility parameter of the external layer of the high shrink label film.   
     
     
         2 . The method of  claim 1 , further comprising:
 placing the wrapped high shrink label film onto a shaped article prior to exposing the seam to radiation to form the high shrink wrap label sleeve.   
     
     
         3 . The method of  claim 1 , wherein the radiation has at least one peak wavelength of about 300 nm to about 500 nm. 
     
     
         4 . The method of  claim 1 , wherein the seam is exposed to radiation at an average power density of at least 0.2 W/cm 2  as measured on the surface of the sleeve, or least 0.5 W/cm 2 , or at least 1 W/cm 2 . 
     
     
         5 . The method of  claim 1 , wherein the seam is exposed to radiation for a time period of about 0.05 seconds to about 5 seconds. 
     
     
         6 . The method of  claim 1 , wherein the liquid radiation-curable seaming agent is applied by spraying, drop-on-demand jetting, ink jetting, stamping, transfer from a rotating roller or rod, stamping, brushing, injecting from nozzle or needle, or ultrasonic spraying. 
     
     
         7 . The method of  claim 1 , wherein the liquid radiation-curable seaming agent contains:
 from 40 wt % to 60 wt % of monomers having a molecular weight of 300 daltons (Da) or less;   from 10 to 30 wt % of the organic solvent having a molecular weight of 300 daltons (Da) or less;   from 0 wt % to 15 wt % of oligomers or polymers having a molecular weight of 300 daltons (Da) or greater;   from 0.5 wt % to 15 wt % of the photoinitiator; and   from 15 to 25 wt % of a tackifying agent.   
     
     
         8 . The method of  claim 1 , wherein the liquid radiation-curable seaming agent comprises:
 from 25 wt % to 98 wt % of an acrylic or methacrylic acid ester or amide or carbamate monomer having a molecular weight of 300 daltons (Da) or less;   wherein the monomer has a Hildebrand solubility parameter that is within 2.2 MPa 1/2  or within 4.4 calories 1/2 ·cm −3/2  of a Hildebrand solubility parameter of the external layer of the associated high shrink label film upon which the seaming agent is used.   
     
     
         9 . The method of  claim 1 , wherein the external layer of the high shrink label film comprises a polyolefin; and
 the seaming agent contains a monomer that comprises an acrylic or methacrylic acid ester or amide or carbamate containing a cyclic hydrocarbon group; an acrylic or methacrylic acid ester or amide or carbamate containing a hydrocarbon having a maximum of 20 carbon atoms; or an acrylic or methacrylic acid ester or amide or carbamate containing an aromatic hydrocarbon or heterocyclic group having a maximum of 20 carbon atoms.   
     
     
         10 . The method of  claim 9 , wherein the external layer of the high shrink label film comprises a cyclic olefin polymer or a cyclic olefin copolymer. 
     
     
         11 . The method of  claim 10 , wherein the seaming agent comprises a monomer having a molecular weight of less than 300 Da selected from the group consisting of isobornyl acrylate, isobornyl methacrylate, cyclohexyl acrylate, ethyl hexyl acrylate, ethyl hexyl methacrylate, tert-butyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate, alkyl acrylates, alkyl methacrylates, tricyclodecanedimethanol acrylate, styrene, vinyltoluene, benzyl acrylate, lauryl acrylate, isodecyl acrylate, phenoxy benzyl acrylate, ethoxylated aryl acrylate, alkylated phenyl acrylate, and phenyl acrylate. 
     
     
         12 . The method of  claim 10 , wherein the seaming agent comprises an oligomer or polymer having a molecular weight of more than 300 Da selected from the group consisting of urethane acrylate, urethane methacrylate, acrylic or methacrylic esters of glycols or diols or polyhydric alcohols, acrylic or methacrylic esters of alkoxylated diols or polyols or polyhydric alcohols, oligomers of acrylic or methacrylic esters, polyvinylbutyral, hydrocarbon resins, polyterpenes, rosin derivatives, polyesters, polystyrene, styrene block copolymers, epoxy acrylates, epoxy methacrylates, phenoxy resins, acrylated or methacrylated dendritic alcohols, ethoxylated diglycidyl ether of bisphenol A diacrylate; polyacrylates of hyperbranched alcohols; blends of urethane acrylate and monomer; and blends of inert resin and monomer. 
     
     
         13 . The method of  claim 1 , wherein the external layer of the high shrink label film comprises polystyrene (PS), polyethylene terephthalate glycol-modified (PETG), or polyvinyl chloride (PVC), or a blend thereof. 
     
     
         14 . The method of  claim 13 , wherein the seaming agent comprises a monomer having a molecular weight of less than 300 Da that is (a) an acrylic or methacrylic ester, amide, or carbamate having a cyclic ether containing group, such as tetrahydrofurfuryl or dioxane; or (b) an acrylic or methacrylic ester, amide, or carbamate having an ethoxylated or propoxylated aromatic or cycloaliphatic group; (c) a monoacrylate or diacrylate or triacrylate or polyacrylate or methacrylate of an alkyl diol or polyol; (d) a vinyl lactam; (e) an acrylamide or methacrylamide; (f) vinyl pyrrolidone or a nitrogen heterocyclic unsaturated monomer; (g) a vinyl morpholine; (h) a lactone or lactam having an acrylate, methacrylate, or vinyl group; (i) a phenyl or alkyl phenol acrylate or methacrylate; (j) an ethoxylated or propoxylated phenyl or alkyl phenol acrylate or methacrylate; (k) a mono-or di- or tri-hydroxyl acid acrylate or methacrylate; (I) an urethane acrylate or methacrylate; (m) an allyl ether; (n) a vinyl ester; (o) a mono-, di-, tri-, tetra-, or poly- -acrylate or -methacrylate of a polyhydric alcohol, including an ethoxylated or propoxylated polyhydric alcohol; or (p) 2-(2-ethoxyethoxy)ethyl acrylate. 
     
     
         15 . The method of  claim 13 , wherein the seaming agent comprises a monomer selected from the group consisting of tetrahydrofurfuryl acrylate (THFA) or caprolactone-modified THFA, phenyl acrylate, cyclic trimethylol propane formal acrylate (CTFA), isobornyl acrylate, isobornyl methacrylate, alkoxylated phenyl acrylate, hexanediol diacrylate, butanediol diacrylate, butanediol dimethacrylates, alkoxylated aliphatic or cycloaliphatic diol diacrylate or dimethacrylate, and tricyclodecanedimethanol diacrylate (TCDDA), ethoxylated cyclohexane dimethanol diacrylate (EO-CHMDA), hydroxy pivalic acid neopentyl glycol diacrylate or caprolactone-modified hydroxy pivalic acid neopentyl glycol diacrylate, hydroxypyvalyl pivalate diacrylate (HPPDA), and caprolactone acrylate. 
     
     
         16 . The method of  claim 13 , wherein the seaming agent comprises an oligomer or polymer selected from the group consisting of urethane acrylate, urethane methacrylate, acrylic or methacrylic esters of glycols or diols or polyhydric alcohols, acrylic or methacrylic esters of alkoxylated diols or polyols or polyhydric alcohols, oligomers of acrylic esters, polyvinylbutyral, hydrocarbon resins, polyterpenes, rosin derivatives, polyesters, epoxy resins, epoxy acrylates, epoxy methacrylates, phenoxy resins, a resin containing a diglycidyl ether of bisphenol-A, polystyrene, styrene block copolymers or terpolymers, terpene phenols, polyester acrylates or methacrylates, polyurethane, polyesteramide, oligomers of acrylic or methacrylic acids or esters or amides; homopolymers, copolymers, terpolymers, or block copolymers of an acrylic acid ester or methacrylic ester; ethoxylated diglycidyl ether of bisphenol A diacrylate; polyacrylates of hyperbranched alcohols; blends of urethane acrylate and monomer; and blends of inert resin and monomer. 
     
     
         17 . The method of  claim 13 , wherein the seaming agent comprises a solvent selected from the group consisting of ethers, cyclic ethers, esters, amides, glycol ethers, ketones, toluene, halogenated alcohols, and halogenated hydrocarbons. 
     
     
         18 . The method of  claim 13 , wherein the seaming agent comprises a monomer which is tetrahydrofurfuryl acrylate (THFA) and contains 0 wt % of the organic solvent. 
     
     
         19 . The method of  claim 1 , wherein the seaming agent has a flashpoint of about 65° C. or greater. 
     
     
         20 . A liquid radiation-curable seaming agent having an immediate welding strength of greater than 2 grams within less than 0.5 seconds on an associated label film, and having at least one component with a Hildebrand solubility parameter that is within 2.2 MPa 1/2  or within 4.4 calories 1/2 ·cm −3/2  of a Hildebrand solubility parameter of an external layer of the associated label film, and having a viscosity of at least 1 centipoise and less than 300 centipoise when measured at any temperature between ambient temperature and 60° C.; wherein when the % VOC of the seaming agent is measured per the modified method of Example 5, the % VOC of the seaming agent is less than 25%.