Polyolefin adhesive compositions and articles made therefrom
Provided are adhesive compositions composed of a polyolefin composition comprising at least about 50 wt. % polypropylene and at least one wax. The polymer compositions have a Dot T-Peel of about 1 Newton or more, a branching index (g′) of 0.95 or less measured at the Mz of the polymer, a molecular weight of 100,000 or less, and the adhesive compositions has a fast set time. The packaging industry desires adhesive compositions having a fast set time, such as those setting in less than five seconds from a molten state at conventional packaging operating temperatures to a solid or quasi solid having favorable Dot T-Peel, set time, and or fiber tear adhesion properties. Polymer based adhesives performing within this window are a favorable alternative to conventional formulated adhesives. The provided adhesive compositions exhibit a favorable balance of properties such as high adhesive strength, wide temperature operating window, and fast set time.
1. An adhesive composition comprising:
(1) a polyolefin composition comprising at least about 50 mol % of a polypropylene, and
(2) at least one wax, wherein the at least one wax comprises a linear polyethylene wax having a molecular weight equal to or greater than 3000; and
(3) wherein the adhesive composition is free of tackifier;
(A) wherein the polyolefin composition has:
(a) a Dot T-Peel of 1 Newton or more on Kraft paper,
(b) an Mw of 10,000 to 100,000,
(c) a branching index (g′) of from 0.4 to 0.98 measured at the Mz of the polyolefin when the polyolefin has an Mw of 10,000 to 60,000, or a branching index (g′) of from 0.4 to 0.95 measured at the Mz of the polyolefin when the polyolefin has an Mw of 10,000 to 100,000;
(B) wherein the at least one wax has a viscosity at 140° C. of between about 100 cp and about 10,000 cp and a wax softening point greater than 110° C. such that a set time function F is greater than 1 and less than 3, wherein F is calculated according to the following equation:
F= 5.26−6.9×10 −5 *[wax viscosity at 140° C., (cp)]−0.021*[wax softening point, (° C.)]
wherein the wax softening point is determined by at least one of:
(a) mettler drop point as determined by ASTM-D3954-94;
(b) congealing point as determined by ASTM D-938;
(c) ring and ball softening point as determined by ASTM E-28; or
(d) peak melt temperature as determined by DSC; and
(C) wherein the adhesive composition has a set time greater than about 1 second and less than about 3 seconds as measured by Dot Set Time; and
(D) wherein the adhesive composition has a fiber tear at 2° C. of about 20% or greater.
2. The adhesive composition of claim 1 , wherein the set time is from about 1.5 seconds to about 3 seconds as measured by Dot Set Time.
3. The adhesive composition of claim 1 , wherein the set time is from about 1.5 seconds to about 2.5 seconds as measured by Dot Set Time.
4. The adhesive composition of claim 1 , wherein the linear polyethylene wax has a viscosity greater than about 100 cp at 190° C.
5. The adhesive composition of claim 1 , wherein the linear polyethylene wax has a peak melt point greater than about 110° C.
6. The adhesive composition of claim 1 , wherein the linear polyethylene wax comprising polyethylene imparts a set time improvement of about 33% or more compared to a reference composition prepared with the same polymer compositions and a Fischer Tropsch wax having a congealing point per ASTM D-938 of 80° C.
7. The adhesive composition of claim 1 , wherein the adhesive composition has a fiber tear at 2° C. of about 20% or greater.
8. An adhesive composition, comprising:
(1) a polyolefin composition comprising at least about 50 mol % of a polypropylene,
(2) at least one wax, wherein the at least one wax comprises a linear polyethylene wax having a molecular weight equal to or greater than 3000, a viscosity at 140° C. of between about 100 cp and about 10,000 cp, and a viscosity greater than about 100 cp at 190° C.; and
(3) wherein the adhesive composition is free of tackifier;
(A) wherein the polyolefin composition has:
(a) a Dot T-Peel of 1 Newton or more on Kraft paper,
(b) an Mw of 10,000 to 100,000,
(c) a branching index (g′) of from 0.4 to 0.98 measured at the Mz of the polyolefin when the polyolefin has an Mw of 10,000 to 60,000, or a branching index (g′) of from 0.4 to 0.95 measured at the Mz of the polyolefin when the polyolefin has an Mw of 10,000 to 100,000;
(B) wherein the at least one wax has a wax softening point greater than 110° C. such that a set time function F is greater than 1 and less than 3, wherein F is calculated according to the following equation:
F= 5.26−6.9×10 −5 *[wax viscosity at 140° C., (cp)]−0.021*[wax softening point, (° C.)]
wherein the wax softening point is determined by at least one of:
(a) mettler drop point as determined by ASTM-D3954-94;
(b) congealing point as determined by ASTM D-938;
(c) ring and ball softening point as determined by ASTM E-28; or
(d) peak melt temperature as determined by DSC;
(C) wherein the adhesive composition has a set time greater than about 1 second and less than about 3 seconds as measured by Dot Set Time; and
(D) wherein the adhesive composition has a fiber tear at 2° C. of about 20% or greater.