HOT MELT ADHESIVES AND USES THEREOF
The disclosure relates to adhesive compositions comprising a semi-crystalline olefin polymer or copolymer and a functional wax, functional olefin polymer, or mixture thereof. These compositions are useful as, for example, adhesives in disposable articles such as diapers, adult incontinence articles, underpads, personal care garments, and the like.
1 . A stretch adhesive composition comprising:
about 25 wt. % to about 75 wt. %, by weight of the stretch adhesive composition, of a semi-crystalline propylene polymer that is a homo-polymer or co-polymer characterized by
a heat of fusion (ΔHm) of between about 4 J/g and about 30 J/g;
a storage modulus (E′) at 40° C. and 1 Hz of between about 3.0×10 8 dyn/cm 2 and about 1.7×10 9 dyn/cm 2 ; and
a viscosity (η) at 200° C. of between about 2 Pa·s and about 100 Pa·s, preferably between about 2 Pa·s and about 20 Pa·s;
between about 1 wt. % and about 10 wt. %, by weight of the stretch adhesive composition, of an adhesion promoter that is a functional wax, functional polyolefin, functional tackifier, functional plasticizer, or a mixture thereof; and
between about 10 wt. % and about 55 wt. %, preferably about 20 wt. % and about 55 wt. %, by weight of the stretch adhesive composition, of a tackifier;
wherein the stretch adhesive composition exhibits an initial creep resistance of about 35% or less and an aged creep resistance, after about 28 days at about 40° C., of about 35% or less.
2 . The stretch adhesive composition of claim 1 , wherein the semi-crystalline propylene polymer is a homo-polymer.
3 . The stretch adhesive composition of claim 1 , wherein the semi-crystalline propylene polymer is a co-polymer.
4 . The stretch adhesive composition of claim 1 , wherein the heat of fusion of the semi-crystalline propylene polymer is between 4 J/g and 6 J/g.
5 . The stretch adhesive composition of claim 1 , wherein the heat of fusion of the semi-crystalline propylene polymer is between 20 J/g and 24 J/g.
6 . The stretch adhesive composition of claim 1 , wherein the storage modulus at 40° C. and 1 Hz of the semi-crystalline propylene polymer is between about 5.0×10 8 dyn/cm 2 and about 1.1×10 9 dyn/cm 2 .
7 . The stretch adhesive composition of claim 1 , wherein the viscosity of the semi-crystalline propylene polymer @ 200° C. is between 2 Pa·s and 8 Pa·s, measured in accordance with ASTM D3236.
8 . The stretch adhesive composition of claim 1 , wherein the viscosity of the semi-crystalline propylene polymer @ 200° C. is between 20 Pa·s and 24 Pa·s.
9 . The stretch adhesive composition of claim 1 , comprising between 1 wt. % and 5 wt. %, by weight of the adhesive composition, of the adhesion promoter.
10 . The stretch adhesive composition of claim 1 , wherein the adhesion promoter is a functional polyolefin.
11 . The stretch adhesive composition of claim 1 , wherein the adhesion promoter is a functional wax.
12 . The stretch adhesive composition of claim 1 , further comprising up to 8 wt. %, by weight of the adhesive composition, of a solid plasticizer or a liquid plasticizer.
13 . The stretch adhesive composition of claim 1 , further comprising up to 2 wt. % , by weight of the adhesive composition, of one or more of an antioxidant, stabilizer, crosslinking agent, filler, nucleating agent, elastomer, colorant, rheology modifier, or a mixture thereof.
14 . The stretch adhesive composition of claim 1 , further comprising up to 10 wt. % , by weight of the adhesive composition, of a non-functionalized wax.
15 . The stretch adhesive composition of claim 1 , having a viscosity @ 150° C. of between about 7,500 Pa·s and about 15,000 Pa·s.
16 . The stretch adhesive composition of claim 1 , characterized by a shear modulus (G′) at 40° C. and 10 rad/s of between about 1.5×10 6 dyn/cm 2 and about 2.5×10 7 dyn/cm 2 .
17 . An article comprising:
a nonwoven substrate;
an elastic strand or an elastic film; and
an elastic attachment hot melt adhesive comprising the stretch adhesive composition of claim 1 .
18 . The article of claim 17 that is a diaper, sanitary napkin, pet sheet, hospital gown, or surgical garment.
19 . The article of claim 18 comprising a substrate that is tissue, cotton, nonwoven fabric, or polyolefin film.
20 . A stretch adhesive composition comprising:
about 45 wt. % to about 65 wt. %, by weight of the stretch adhesive composition, of a semi-crystalline propylene polymer that is a homo-polymer or co-polymer characterized by
a heat of fusion (ΔHm) of between about 4 J/g and about 8 J/g;
a storage modulus (E′) at 40° C. and 1 Hz of between about 5.0×10 8 dyn/cm 2 and about 1.1×10 9 dyn/cm 2 ; and
a viscosity (η) at 200° C. of between about 6 Pa·s and about 8 Pa·s, measured in accordance with ASTM D3236;
between about 1 wt. % and about 10 wt. %, by weight of the stretch adhesive composition, of an adhesion promoter that is a functional wax, functional polyolefin, functional tackifier, functional plasticizer, or a mixture thereof; and
between about 20 wt. % and about 40 wt. %, by weight of the stretch adhesive composition, of a tackifier;
wherein the stretch adhesive composition exhibits an initial creep resistance of about 10% or less and an aged creep resistance of about 20% or less after about 28 days at about 40° C.