Hot melt adhesive

Abstract

A hot melt adhesive material and articles made using the hot melt adhesive to assemble structures in an article. The adhesive material typically is manufactured by blending amorphous polymer with a heterophase polymer having crystallinity into an adhesive composition.

Claims

1. An adhesive composition comprising: (i) about 10 wt. % to about 90 wt. % of a polyolefin copolymer, wherein the polyolefin copolymer comprises propene monomer units and at least 40 wt. % of 1-butene monomer units; and (ii) about 10 wt. % to about 90 wt. % of a heterophase polyolefin propylene copolymer, wherein the heterophase polyolefin propylene copolymer comprises propene monomer units, amorphous blocks, and crystalline blocks.

2. The adhesive composition of claim 1, wherein the polyolefin copolymer comprises less than 5 wt. % crystallinity, wherein the heterophase polyolefin propylene copolymer comprises at least 5 wt. % crystallinity in at least one sequence or block.

3. The adhesive composition of claim 1, wherein the polyolefin copolymer comprises less than 50 wt. % of the propene monomer units.

4. The adhesive composition of claim 1, wherein the heterophase polyolefin propylene copolymer comprises polymer blocks or sequences that have a crystallinity of greater than 10 wt. %.

5. The adhesive composition of claim 1, wherein the adhesive composition is substantially free of a tackifier.

6. The adhesive composition of claim 1, wherein the adhesive composition comprises from about 50 wt. % to about 90 wt. % of the polyolefin copolymer, and wherein the adhesive composition comprises from about 10 wt. % to about 50 wt. % of the heterophase polyolefin propylene copolymer.

7. The adhesive composition of claim 1, wherein the polyolefin copolymer comprises two or more monomer units, and wherein the heterophase polyolefin propylene copolymer comprises two or more monomer units.

8. The adhesive composition of claim 1, wherein the adhesive composition is free of a tackifier.

9. An article comprising a substrate and a film, fiber, cellulose sheet or non-woven having an adhesive bond there between comprising the adhesive composition of claim 1, wherein the adhesive composition provides cohesive strength from the heterophase polyolefin propylene copolymer and adhesive strength from the polyolefin copolymer.

10. An article comprising a substrate and a film, fiber, cellulose sheet or non-woven having an adhesive bond there between comprising the adhesive composition of claim 5, wherein the adhesive composition provides cohesive strength from the heterophase polyolefin propylene copolymer and adhesive strength from the polyolefin copolymer.

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

(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 Amoco Indapol H-300 20 4.5 9.5 14.5 20 24.99 0 0 Chemicals (Polyisobutylene) Amoco Indapol H-1900 0 0 0 0 0 0.5 29.99 29.99 Chemicals (Polyisobutylene) Ciba Geigy Irganox 1010 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Ltd., Basel, (Hindered Switzerland Phenol) Mayzo, Inc. Benetex OB 0 0 0 0 0.01 0.01 Fluorescent Optical 0 0.01 Brightener

(4) TABLE-US-00003 TABLE 3 EXEMPLARY ADHESIVE VISCOSITY DATA Brookfield 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. (275 F.) 7710 12125 9725 7500 8425 7100 9100 8750 148.9 C. (300 F.) 4675 6350 5325 4525 5150 4200 5325 5375 162.8 C. (325 F.) 3075 4190 3500 2980 3475 2800 3550 3375 176.7 C. (350 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.

(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 thermosel 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 F. 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.