Low temperature hot melt adhesives for disposable articles with high creep resistance
View Patent ↗The present invention is directed to adhesives suitable for application using a hot melt process at a relatively low temperature in the range of about 110° C. to about 130° C. Such adhesives exhibit desirable viscoelastic properties and are suitable for bonding an elastic attachment in the manufacture of disposable articles, such as disposable diapers.
1. A method of forming an article comprising:
(a) applying a low application temperature hot melt adhesive onto a substrate at a temperature in the range of from about 110° C. to about 130° C. at an add-on-level of about 20 to about 100 mg/m/strand;
(b) cooling the adhesive to room temperature;
wherein the low application temperature hot melt adhesive comprises:
i. 5 to 20 wt % of the styrenic block copolymer that (1) has a melt flow index greater than 33, measured in accordance with ASTM D 1238, and (2) has a styrene content greater than 40%;
ii. 0.5 to 5% wt % of the wax;
iii. 30-70 wt % of a tackifier that has a ring and ball softening point less than about 105° C.;
iv. 0.1-2 wt % of an antioxidant; and
v. optionally, up to 30 wt % of an oil; and
wherein the cooled adhesive has a creep performance of less than about 15% after 300% strain is applied on the cooled adhesive at 38° C. for four hours.
2. The method of claim 1 wherein the adhesive is applied by strand coating.
3. A method of forming an article comprising:
(a) applying the low application temperature hot melt adhesive onto a substrate at a temperature in the range of from about 110° C. to about 130° C. at an add-on-level of about 3 to about 30 mg/in; and
(b) cooling the adhesive to room temperature;
i. 5 to 20 wt % of the styrenic block copolymer that (1) has a melt flow index greater than 33, measured in accordance with ASTM D 1238, and (2) has a styrene content greater than 40%;
ii. 0.5 to 5% wt % of the wax;
iii. 30-70 wt % of a tackifier that has a ring and ball softening point less than about 105° C.;
iv. 0.1-2 wt % of an antioxidant; and
v. optionally, up to 30 wt % of an oil; and
wherein the cooled adhesive has a creep performance of less than about 25% after 300% strain is applied on the cooled adhesive at 38° C. for four hours.
4. The method of claim 3 wherein the adhesive is applied by spiral coating.