ADDITIVE COMPOSITION FOR CAUSTIC REMOVABLE HOT MELT ADHESIVES AND FORMULATIONS CONTAINING THE SAME
An additive composition for imparting caustic removability to a hot melt adhesive includes an ester functionalized polymer having a polymeric backbone and, pendent thereon, one or more dicarboxylic acid moieties in at least partial ester form. The polymeric backbone has a weight average molecular weight less than 50,000. The ester functionalized polymer may be, for example, an at least partial ester of a maleated hydrocarbon. The additive may further include a low molecular weight α,β ethylenically unsaturated anhydride-containing or acid-containing polymer. A caustic removable hot melt adhesive composition comprises a hot melt adhesive additive and a conventional hot melt adhesive resin. A caustic removable adhesive label comprises a substrate and a caustic removable hot melt adhesive composition which includes an additive composition. The caustic removable hot melt adhesives can be used on labels for articles, such as glass bottles.
1 . An additive composition for imparting caustic removability to a hot melt adhesive, said additive composition comprising:
an ester functionalized polymer comprising a polymeric backbone and, pendent thereon, one or more dicarboxylic acid moieties in at least partial ester form; and
an at least partial ester of a low molecular weight α,β ethylenically unsaturated anhydride-containing or acid-containing polymer selected from the group consisting of a partial ester of a low molecular weight maleic anhydride homopolymer, a partial ester of a low molecular weight maleic anhydride olefin copolymer, and partial ester of a low molecular weight maleic anhydride vinyl aromatic copolymer.
2 . The additive composition of claim 1 , wherein a portion of the polymeric backbone is aliphatic.
3 . The additive composition of claim 1 , wherein the polymeric backbone has a weight average molecular weight less than 50,000.
4 . The additive composition of claim 1 , wherein the polymeric backbone is a homopolymer of a C3 to C16 monomer or a copolymer of two or more C3 to C16 monomers.
5 . The additive composition of claim 1 , wherein the one or more dicarboxylic acid moieties is an at least partial ester of a dicarboxylic acid moiety derived from a functionalizing agent selected from the group consisting of maleic acid, maleic anhydride, fumaric acid, itaconic acid, tetrahydrophthalic acid, and tetrahydrophthalic anhydride.
6 . The additive composition of claim 1 , wherein the ester functionalized polymer is an at least partial ester of a maleic anhydride grafted butadiene polymer or an at least partial ester of a maleic anhydride grafted C5 hydrocarbon polymer.
7 . The additive composition of claim 1 , wherein the ester functionalized polymer is an at least partial ester of a maleic anhydride grafted hydrocarbon polymer containing a structure according to Formula I:
wherein R is a maleic anhydride or a dicarboxylic acid moiety, the dicarboylic acid moiety having a structure according to Formula II:
wherein R 1 and R 2 can be the same or different and are selected from H and any residue of an aromatic, aliphatic, linear, or branched C1-C12 monoalcohol, provided that at least a portion of the acid groups in the polymer are in ester form.
8 . The additive composition of claim 1 , wherein the at least partial ester of a low molecular weight α,β ethylenically unsaturated anhydride-containing or acid-containing polymer is a partial ester of a low molecular weight maleic anhydride vinyl aromatic copolymer.
9 . The additive composition of claim 1 , wherein the at least partial ester of a low molecular weight α,β ethylenically unsaturated anhydride-containing or acid-containing polymer is a partial ester of a low molecular weight styrene-maleic anhydride (SMA) copolymer.
10 . The additive composition of claim 9 , wherein the low molecular weight styrene-maleic anhydride (SMA) copolymer has a structure according to Formula III:
in which R is a residue of at least one monoalcohol selected from C1 to C12 monoalcohols, and their mixtures; n ranges from 7 to 72; and x, y, and z are such that a molar ratio of (x:(y+z)) is in the range from 1:1 to 3:1, and (z/(y+z)) ranges from 0.5 to 1.0.
11 . The additive composition of claim 10 , wherein the low molecular weight SMA ester has a ratio of styrene(S) : maleic anhydride(MA) of about 1:1 to about 3:1.
12 . The additive composition of claim 10 , wherein the low molecular weight SMA ester has a ratio of styrene(S) : maleic anhydride(MA) of about 1.4:1 to about 1.6:1.
13 . The additive composition of claim 8 , wherein the ester functionalized polymer is an at least partial ester of a maleic anhydride grafted hydrocarbon polymer and the at least partial ester of a low molecular weight maleic anhydride vinyl aromatic copolymer is a partial ester of a low molecular weight styrene-maleic anhydride (SMA).
14 . A caustic removable hot melt adhesive composition comprising:
a hot melt adhesive additive comprising the additive composition of claim 1 ; and
an adhesive resin selected from the group consisting of styrene-isoprene block copolymers, polyacrylate resins, poly ethylene vinyl acetate (EVA) resins, polystyrene butadiene resins, random styrene butadiene (SBR) copolymers, styrene-butadiene block copolymers, styrene-isoprene-butadiene-styrene block copolymers, styrene-ethylene-propylene-styrene block copolymers, styrene-ethylene-butylene block copolymers, amorphous poly-α olefin (APAO) resins, and mixtures thereof.
15 . A caustic removable adhesive label comprising:
a substrate, and
a caustic removable hot melt adhesive composition comprising
a hot melt adhesive additive comprising the additive composition of claim 1 ; and
an adhesive resin selected from the group consisting of styrene-isoprene block copolymers, hydrocarbon tackifying resins, polyacrylate resins, poly ethylene vinyl acetate (EVA) resins, polystyrene butadiene resins, random styrenebutadiene (SBR) copolymers, styrene-butadiene block copolymers, styrene-ethylene-butylene block copolymers, amorphous poly-α olefin (APAO) resins, and mixtures thereof.
16 . (canceled)
17 . The caustic removable adhesive label of claim 15 , wherein the adhesive additive is soluble in a caustic solution having a pH greater than 8.
18 . An article having a caustic removable adhesive label, wherein the article comprises
a container, and
a caustic removable adhesive label according to claim 15 .
19 . The article of claim 18 , wherein the container is made from a material from the group consisting of glass, metal, and plastic.
20 . The additive composition of claim 1 , wherein the one or more dicarboxylic acid moieties are 50 to 100% esterified.
21 . The additive composition of claim 1 , wherein the one or more dicarboxylic acid moieties contain one or two ester groups having a structure —C(═O)OR wherein R is a C1 to C6 alkyl group.