Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-04-09
2002-06-25
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S221000, C524S227000, C524S230000, C524S297000, C524S313000, C524S488000, C525S064000, C525S079000, C525S167000, C525S444000
Reexamination Certificate
active
06410627
ABSTRACT:
BACKGROUND OF THE INVENTION
Hot melt adhesives are used commercially for a wide variety of applications. The major advantage of hot melt adhesive systems is the lack of a carrier fluid which eliminates the need for drying the adhesive film once it is applied to the substrate. This elimination of the drying step overcomes hazards associated with solvent usage and also allows for faster production line speeds and lower transportation costs.
For various applications, such paper bonding applications including tissue/towel lamination, roll wrap, bag ending, and moisture activated front seals for envelopes, it is also desired that some hot melt adhesives be water-dispersible.
SUMMARY OF THE INVENTION
We have now found that the use of high hydroxyl compounds, which function as tackifiers in hot melt adhesive formulations, at high levels, >10%, provide hot melts with improved water sensitivity compared to hot melts formulated with conventional tackifiers. These compounds find particular use in hot melt adhesives based on sulfonated polyesters and graft copolymers of vinyl monomers and polyalkylene oxide polymers.
Thus, in its broadest aspect, the present invention is directed to hot melt adhesive compositions comprising a sulfonated polyester or a graft copolymer of at least one vinyl monomer and at least one polyalkylene oxide polymer; and a high hydroxyl number compound.
It will be recognized that the general formulations described above can be adapted to include a wide variety of hot melt adhesive compositions, the more precise formulations of which will vary depending upon the specific end use, as known to those skilled in the particular art.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to hot melt adhesive compositions, with improved water sensitivity, comprising a sulfonated polyester or a graft copolymer of at least one vinyl monomer and at least one polyalkylene oxide polymer; and a high hydroxyl number compound.
The high hydroxyl compound aids in the water dispersibility of the hot melt adhesive formulation. Specifically, the compounds described here will provide the adhesives of the present invention with improved water sensitivity, as compared to hot melt adhesives formulated with conventional tackifiers (rosin and rosin derivatives, terpene phenolics, and &agr;-methyl styrene). Water sensitive adhesives may be used in remoistenable and repulpable applications, or in wetness indicator adhesives.
The compounds of the present invention are solid high hydroxyl materials with a hydroxyl number >100 mg KOH/g. The compounds are amorphous, with a low melt viscosity and a softening point above room temperature. Preferred compounds are styrene allyl alcohol copolymers available from ARCO Chemical under the tradename SAA-100 with an hydroxyl number of 210 mg KOH/g and orthophthalate neopentyl glycol polyester polyol available from Stepan under the tradename Stepanol PN-110 with a hydroxyl number of 110 mg KOH/g. These compounds form miscible blends with sulfonated polyester base polymers and polyethylene glycol grafted polyvinyl acetate base polymers. The compounds are present in an amount of 5 to 40%, preferably 10 to 35% by weight of the adhesive.
The polymeric component of the present adhesive formulation is any polymer suitable for use in formulating hot melt adhesives. Preferred are the sulfonated polyesters, or a graft copolymers of vinyl monomers and polyalkylene oxide polymers. The polymeric component is present in the adhesive compositions in an amount greater than 40% by weight, preferably 60% by weight.
The sulfonated polyester component of the present invention is a condensation polymer comprising the reaction product of:
(a) at least one difunctional dicarboxylic acid or corresponding methyl ester which is not a sulphomonomer;
(b) 2 to 25 mole percent of at least one sulphomonomer containing at least one metallic sulfonate group or nitrogen-containing non-metallic sulfonate group attached to an aromatic or cycloaliphatic nucleus and at least one functional group selected from the group consisting of hydroxyl, carboxyl, and amino;
(c) at least one difunctional reactant selected from a glycol or a mixture of a glycol and diamine having two —NRH groups, the glycol containing two —C(R
1
)
2
—OH groups wherein R in the reactant is hydrogen or an alkyl group of 1 to 6 carbon atoms, and R
1
in the reactant is a hydrogen atom, an alkyl of 1 to 5 carbon atoms, or an aryl group of 6 to 10 carbons atoms;
(d) 0 to 40 mole percent of a difunctional reactant selected from hydroxycarboxylic acids having one —C(R)
2
—OH group, aminocarboxylic acids having one —NRH group, amino-alcohols having one —C(R)
2
—OH group and one —NRH group, or mixtures of said difunctional reactants wherein R in the reactant is hydrogen or an alkyl group of 1 to 6 carbon atoms; and
(e) 0 to 40 mole percent of a multifunctional reactant containing at least three functional groups selected from hydroxyl, carboxyl, and mixtures thereof wherein at least a portion of the multifunctional reactant contains at least three hydroxyl groups,
wherein all stated mole percentages are based on the total of all acid, hydroxyl and amino group containing reactants being equal to 200 mole percent, and wherein the polymer contains proportions of acid-group containing reactants (100 mole percent acid) to hydroxy- and amino-group containing reactants (100 mole percent base) such that the value of (equivalents) EQ (base) divided by (equivalents) EQ (acid) is between 0.5 and 2.
The difunctional acid or ester reactant of (a) of the composition of the present invention is preferably substantially aliphatic in nature and may be an acid selected from the group consisting of oxalic; malonic; dimethylmalonic; succinic; glutaric; adipic; trimethyladipic; pimelic; pivalic; fumaric; maleic; dodecanoic; 2,2-dimethylglutaric; azelaic; sebacic; 1,3-cyclopentane-dicarboxylic; 1,2-cyclohexanedicarboxylic; 1,3-cyclohexane dicarboxylic; 1,4-cyclo-hexanedicarboxylic; phthalic; terephthalic; isophthalic; 2,5-norbornane-dicarboxylic; 1,3-naphthalic; diphenic; 4,4′-oxydibenzoic; diglycolic; thiodipropionic; 4,4′-sulfonyldibenzoic; and 2,5-naphthalenedicarboxylic acids and esters thereof and mixtures thereof. The difunctional dicarboxylic acid or ester reactant of (a) is preferably selected from the group of acids consisting of isophthalic acid, terephthalic acid, phthalic anhydride (acid), adipic acid, pivalic acid, dodecanedioic acid, sebacic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexane-dicarboxylic acid, maleic anhydride, fumaric acid, succinic anhydride (acid), 2,6-naphthalenedicarboxylic acid, and glutaric acid and esters thereof and mixtures thereof. The more preferred difunctional dicarboxylic acid reactants of (a) are selected from the group consisting of isophthalic acid, adipic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid and mixtures thereof with 1,4-cyclohexanedicarboxylic acid being most preferred.
The sulphomonomer reactant of (b) is preferably selected from the group consisting of difunctional monomers containing a —SO
3
M group attached to a nucleus selected from the group consisting of benzene, naphthalene, anthracene, diphenyl, oxydiphenyl, sulfonyldiphenyl, and methylenediphenyl, wherein M is Na+, Li+, Mg++, Ca++, Fe++, and Fe+++. The more preferred sulfomonomer reactant of (b) is selected from the group consisting of diols an diol adducts of multifunctional reactant containing at least three hydroxyl groups and a monocarboxylic acid sulfomonomer containing at least one metallic sulfonate group or nitrogen-containing non-metallic sulfonate group attached to an aromatic or cyclo-aliphatic nucleus. Alternatively, a more preferred group of sulfomonomers include 5-sodiosulfoisophthalic acid, dimethyl 5-sodiosulfoisophthalate, 5-lithiosulfoisphthalic acid, and bis(2-hydroxyethyl)-5 -sodiosulfoisophthalate; with the 5-sodiosulfoisophthalic acid or dimethyl 5-sodiosulfoisophthalate be
Blumenthal Mitchell J.
Paul Charles W.
Foulke Cynthia L.
National Starch and Chemical Investment Holding Corporation
Szekely Peter
LandOfFree
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