Hot melt adhesive

Abstract

An absorbent article having a liquid permeable interior layer, a liquid impervious exterior layer, an absorbent layer therebetween, and a hot melt adhesive composition having an amorphous polyolefin composition and a heterophase polyolefin copolymer composition with a first set of comonomer units and a second set of comonomer units, wherein the first set of comonomer units are propene.

Claims

1. An absorbent article comprising a liquid permeable interior layer, a liquid impervious exterior layer, and an absorbent layer therebetween, wherein the absorbent article further comprises a hot melt adhesive composition comprising: from about 10 wt. % to about 90 wt. % of an amorphous polyolefin composition comprising a random butane-α-olefin copolymer, the random butane-α-olefin copolymer comprising at least 30 mole % of 1-butene monomer units, and from about 10 wt. % to about 90 wt. % of a heterophase polyolefin copolymer composition comprising a first set of comonomer units and a second set of comonomer units, wherein the first set of comonomer units are propene, and wherein the second set of comonomer units are selected from the group consisting of ethylene, 1-hexene, 1-octene, and amorphous blocks and crystalline blocks; wherein the hot melt adhesive composition is substantially tackifier-free; and wherein the hot melt adhesive has a density of less than 0.9 g-cm.sup.−3.

2. The absorbent article of claim 1, wherein the liquid permeable interior layer comprises a nonwoven.

3. The absorbent article of claim 1, wherein the liquid impervious exterior layer comprises a polymer film.

4. The absorbent article of claim 1, wherein the absorbent article comprises an adhesive bond between a polymer film and a nonwoven fabric.

5. The absorbent article of claim 1, wherein the hot melt adhesive composition bonds the liquid permeable interior layer and the liquid impervious exterior layer.

6. The absorbent article of claim 1, wherein the absorbent article is selected from the group consisting of infant diapers, adult diapers, and feminine care pads.

7. The absorbent article of claim 1, wherein the heterophase polyolefin copolymer composition comprises at least 5 wt. % crystalline sequences or blocks.

8. The absorbent article of claim 1, wherein the heterophase polyolefin copolymer composition comprises greater than 40 wt. % of the first set of comonomer units, wherein the heterophase polyolefin copolymer composition comprises less than 60 wt. % of the second set of comonomer units.

9. The absorbent article of claim 1, wherein the hot melt adhesive composition has a softening point from about 80° C. to 140° C. when measured using ASTM D 3461-97.

10. The absorbent article of claim 1, wherein the hot melt adhesive composition comprises from about 10 wt. % to about 40 wt. % of the heterophase polyolefin copolymer composition.

11. The absorbent article of claim 1, wherein the heterophase polyolefin copolymer composition comprises from about 70 wt. % to about 99.5 wt. % of the first set of comonomer units.

12. The absorbent article of claim 1, wherein the amorphous polyolefin composition has a viscosity from about 2000 mPa.Math.s to about 8000 mPa.Math.s when measured by ASTM D3236 at 190° C.

13. An absorbent article comprising a liquid permeable interior layer, a liquid impervious exterior layer, and an absorbent layer therebetween, wherein the absorbent article further comprises a hot melt adhesive composition comprising: from about 10 wt. % to about 90 wt. % of an amorphous polyolefin composition comprising a random butane-α-olefin copolymer, the random butane-α-olefin copolymer comprising from about 30 mole % to about 70 mole % of 1-butene monomer units, wherein the amorphous polyolefin composition has a viscosity from about 2000 mPa.Math.s to about 8000 mPa.Math.s when measured by ASTM D3236 at 190° C.; and from about 10 wt. % to about 90 wt. % of a heterophase polyolefin copolymer composition comprising a first set of comonomer units and a second set of comonomer units, wherein the first set of comonomer units are propene, and wherein the second set of comonomer units are selected from the group consisting of ethylene, 1-hexene, 1-octene, and amorphous blocks and crystalline blocks; wherein the hot melt adhesive composition is substantially tackifier-free; wherein the hot melt adhesive has a density of less than 0.9 g-cm.sup.−3; and wherein the hot melt adhesive composition has a softening point from about 80° C. to 140° C. when measured using ASTM D 3461-97.

14. The absorbent article of claim 13, wherein the liquid permeable interior layer comprises a nonwoven.

15. The absorbent article of claim 13, wherein the liquid impervious exterior layer comprises a polymer film.

16. The absorbent article of claim 13, wherein the absorbent article comprises an adhesive bond between a polymer film and a nonwoven fabric.

17. The absorbent article of claim 13, wherein the hot melt adhesive composition bonds the liquid permeable interior layer and the liquid impervious exterior layer.

18. The absorbent article of claim 13, wherein the absorbent article is selected from the group consisting of infant diapers, adult diapers, and feminine care pads.

19. An absorbent article comprising a liquid permeable interior layer, a liquid impervious exterior layer, and an absorbent layer therebetween, wherein the absorbent article further comprises a hot melt adhesive composition comprising: from about 10 wt. % to about 90 wt. % of an amorphous polyolefin composition comprising a random butane-α-olefin copolymer, the random butane-α-olefin copolymer comprising from about 30 mole % to about 70 mole % of 1-butene monomer units, wherein the amorphous polyolefin composition has a viscosity from about 2000 mPa.Math.s to about 8000 mPa.Math.s when measured by ASTM D3236 at 190° C.; from about 10 wt. % to about 90 wt. % of a heterophase polyolefin copolymer composition comprising a first set of comonomer units and a second set of comonomer units, wherein the first set of comonomer units are propene, and wherein the second set of comonomer units are selected from the group consisting of ethylene, 1-hexene, 1-octene, and amorphous blocks and crystalline blocks; and an antioxidant; wherein the hot melt adhesive composition has a softening point from about 80° C. to 140° C. when measured using ASTM D 3461-97; wherein the hot melt adhesive has a density of less than 0.9 g-cm.sup.−3; and wherein the adhesive is substantially free of a tackifier.

20. The absorbent article of claim 19, wherein the absorbent article is selected from the group consisting of infant diapers, adult diapers, and feminine care pads.

Description

EXPERIMENTAL

(1) A number of hot melt adhesive compositions were prepared by blending first amorphous copolymer, second heterophase copolymer, polymer plasticizer/diluent and antioxidant under mixing conditions at elevated temperatures to form a fully homogenized fluid melt. Mixing temperatures varied from about 135 to about 200° C. preferably about 150 to about 175° C. A WiseStir® mixer was used to ensure full homogenization of components into a final adhesive composition.

Examples 1-4 there are 8 Examples?

(2) Hot melt adhesive compositions were formulated by melt blending as described below, wherein specific components and amounts of the components are shown in the following table 2.

(3) TABLE-US-00002 TABLE 2 Exemplary Adhesive Formulations Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Source Component wt. % wt. % wt. % wt. % wt. % wt. % wt. % wt. % ExxonMobil Vistamaxx 8816 20 35 35 35 15 15 15 10 Chemical, Houston, TX Huntsman Rextac E-65 59.5 60 55 50 64.5 59.5 59.5 59.5 Chemicals Ineos Chemicals Indapol H-300 20 4.5 9.5 14.5 20 24.99 0 0 (polyisobulylene) (Polyisobutylene) Ineos Chemicals Indapol H-1900 0 0 0 0 0 0.5 24.99 29.99 (Polyisobutylene) Ciba Geigy Ltd., Irganox 1010 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Basel, Switzerland (Hindered Phenol) Mayzo, Inc. Benetex OB 0 0 0 0 0 0.01 0.01 0.01 Fluorescent Ooptical Brightener

(4) TABLE-US-00003 TABLE 3 EXEMPLARY ADHESIVE VISCOSITY DATA Brookfiled Viscosity @ Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 121.1° C. (250° F.) 26200 29750 16600 39000 135° C. (250° F.) 7710 12125 9725 7500 8425 7100 9100 8750 148.9° C. (250° F.) 4675 6350 5325 4525 5150 4200 5325 5375 162.8° C. (250° F.) 3075 4190 3500 2980 3475 2800 3550 3375 176.7° C. (250° F.) 2220 2945 2450 2080 2315 1920 2385 2275 Mettler Softening Point 121° C. 125° C. 125° C. 124° C. 120° C. 118° C. 118° C. 115° C. Density g-cm.sup.−3 0.86-0.87 0.86-0.87 0.86-0.87 0.86-0.87 0.86-0.87 0.86-0.87 0.86-0.87 0.86-0.87 ASTM 792

(5) These data indicates that the materials will provide excellent construction bonding in disposable absorbent articles. Note viscosity relates to the resistance to flow of the material under certain conditions. This distinctive property determines the flowability, degree of wetting, and penetration of the substrate by the molten polymer. It provides an indication of its processability and utility as a hot melt adhesive material. Melt viscosity is generally directly related to a polymer molecular weight and is reported in Millipascal-second's or centipoise (cP) using a Brookfield thermoset RVT viscometer using a rotor number 27 at the stated temperature.

(6) Mettler softening point in degrees Centigrade or degrees Fahrenheit is typically measured using ASTM D3104, The amorphous nature of the poly olefin materials results in a melting point, which is not sharp or definite. Rather as the temperature increases, amorphous polymers gradually change from a solid to a soft and then to a liquid material. No clearly defined glass transition or melting temperature is often noted. This temperature testament that generally measures the precise temperature at which a disc of polymer sample, heated at a rate of 2° C. per minute or 10° per minute becomes soft enough to allow the test object, a steel ball (grams) drops through the sample. The softening point of a polymer reported in degrees Centigrade or degrees Fahrenheit is important because it typically indicates the polymer's heat resistance, useful application temperatures and solidification points.

(7) The claims may suitably comprise, consist of, or consist essentially of, or be substantially free of any of the disclosed or recited elements. The invention illustratively disclosed herein can also be suitably practiced in the absence of any element which is not specifically disclosed herein. The various embodiments described above are provided by way of illustration only and should not be construed to limit the claims attached hereto. Various modifications and changes may be made without following the example embodiments and applications illustrated and described herein, and without departing from the true spirit and scope of the following claims.

(8) The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”

(9) Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

(10) While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.