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 compatible amorphous polymer.

Claims

1. An absorbent article comprising a liquid permeable interior layer, a liquid impervious exterior layer, and an absorbent layer therebetween; further comprising a hot melt adhesive composition consisting essentially of: (i) 90% by weight of an amorphous polyolefin composition comprising a copolymer having more than 40 mole % 1-butene; and (ii) a second amorphous polymer comprising at least one butene monomer, the polymer having a molecular weight (MW.sub.n) of at least 1000 wherein the polymer is compatible with the polyolefin; wherein the interior layer comprises a nonwoven; wherein the absorbent layer comprises a super absorbent material; wherein the exterior layer comprises a multilayer structure comprising a polymer film; and wherein the article comprises an adhesive bond between the interior layer comprising the nonwoven and the exterior layer comprising the multi-layer structure comprising the polymer film.

2. The absorbent article of claim 1, comprising another exterior layer comprising a nonwoven layer.

3. The absorbent article of claim 1, wherein the hot melt adhesive bonds the interior layer and the exterior layer.

4. The absorbent article of claim 1, wherein the adhesive may be coated, applied, or sprayed onto either a nonwoven or polymer film layer of the article.

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

6. The absorbent article of claim 1, wherein the adhesive is substantially free of a tackifier.

7. The absorbent article of claim 1, wherein the second amorphous polymer comprises a viscous liquid with molecular weight of 1000-20,000 and a Saybolt Universal seconds (SUS) viscosity at 100° C. of about 100 to 20,000.

8. The absorbent article of claim 1, wherein the amorphous polyolefin polymer comprises less than 50 wt. % of one or more alpha olefin C.sub.2 or C.sub.4-20 monomers.

9. The absorbent article of claim 1, wherein the second amorphous polymer comprises a polyisobutylene with a molecular weight of 1500 to 6000.

10. The absorbent article of claim 1, wherein the density of the adhesive is less than 0.9 g/cm.sup.3.

11. A disposable absorbent article comprising a first substrate, a second substrate, and a hot melt adhesive composition bonding the first substrate and the second substrate to one another, wherein the hot melt adhesive consists essentially of: (i) 90% by weight of an amorphous polyolefin composition comprising a copolymer having more than 40 mole % 1-butene; and (ii) a second amorphous polymer comprising at least one butene monomer, the polymer having a molecular weight (MW.sub.n) of at least 1000 wherein the polymer is compatible with the polyolefin; wherein the first substrate is a liquid permeable interior layer comprising a nonwoven and the second substrate is a liquid impervious exterior layer comprising a polymer film and a second nonwoven.

Description

EXPERIMENTAL

(1) A number of hot melt adhesive compositions were prepared by blending first amorphous copolymer, second compatible copolymer and antioxidant using mixing conditions at elevated temperatures to form a fully homogenized melt. Mixing temperatures varied from about 135 to about 200° C. preferably about 150 to about 175° C. as needed to obtain uniformity. A traditional heated stirred blade (WiseStir®) mixer was used to ensure full homogenization in a heated container into a final adhesive composition.

Examples 1-3

(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 Experimental Preparations Ex. 1 Ex. 2 Ex. 3 Component (wt. %) (wt. %) (wt. %) Rextac E-65 44.5 54.5 (1-butene copolymer) Rextax E-63 30 20 (1-butene copolymer) Rextac 2830 70 (1-butene copolymer) Indapol H-1900 24.99 24.99 29.49 Polyisobutylene (MW2500) Irganox 1010 (Stabilizer) 0.5 0.5 0.5 Benotex OB 0.01 0.01 0.01 (Optical brightener) Brookfield DV-II + pro Viscosity (cP) Rotation 10 rpm Spindle # SC4-27 250° F. 31000 23825 18200 275° F. 13650 13175 10250 300° F. 6265 6875 6050 325° F. 4090 4460 3850 350° F. 3245 3060 2595 Mettler Softening 116 115 91 Point (° C.) Density (g-cm.sup.−3) 0.87 0.87 0.87

Comparative Example 1

(4) Holt melt adhesive compositions are formulated by melt blending, as described below, wherein specific components and amounts of the components are shown in the following table 3.

(5) TABLE-US-00003 TABLE 3 Experimental Preparations CEx. 1 CEx 2 Component (wt. %) (wt. %) APAO 75 Rextac E-63 (1-butene copolymer) 75 Polyisobutylene 25 White Oil 25 Irganox 20120 (Stabilizer) 0 0 Benotex OB (Optical brightener) 0 0

(6) Comparative examples 1 and 2 forms a non-uniform composition that has insufficient cohesive/adhesive strength to be usefully measured.

(7) TABLE-US-00004 TABLE 4 Test Results Add-on Add-on method - (g-m.sup.−2) Air Average Peel Nordsen ® Over Press. Web Speed Peak Peel force Hot Melt 120 mm Temp (psi/ (inch-sec.sup.−1/ Peel (g- (N- Run applic. width (° F./° C.) Gap Pascal) m-sec.sup.−1) Ex. Ex. Ex. (g-in.sup.−1) in.sup.−1) cm.sup.−1) 1 Slot/true 0.75 320/160 2000/50.8 Ex. 2 190 93 0.37 coat die 2 Slot/true 1 310/154.4 2000/50.8 Ex. 2 202 110 0.43 coat die 3 Slot/true 1 320/160 2000/50.8 Ex. 2 217 134 0.53 coat die 4 Slot/true 1 330/165.6 2000/50.8 Ex. 2 212 131 0.52 coat die 5 Slot/true 1 315/157.2 2000/50.8 Ex. 2 205 110 0.43 coat die 6 Slot/true 0.5 320/160 2000/50.8 Ex. 2 111 58 0.23 coat die 7 Slot/true 0.75 320/160 2000/50.8 Ex. 2 161 95 0.37 coat die 8 Slot/true 0.5 320/160 2000/50.8 Ex. 1 126 70 0.28 coat die 9 Slot/true 0.75 320/160 2000/50.8 Ex. 1 181 100 0.39 coat die 10 Slot/true 0.5 320/160 2000/50.8 Ex. 3 117 62 0.24 coat die 11 Slot/true 0.75 320/160 2000/50.8 Ex. 3 152 93 0.37 coat die 12 Slot/true 1 320/160 2000/50.8 Ex. 3 192 123 0.48 coat die 13 Signature 1 360/182.2 20 mm 40/0.276 2000/50.8 Ex. 2 154 92 0.36 14 Signature 1 360/182.2 20 mm 45/0.310 2000/50.8 Ex. 2 164 96 0.38 15 Signature 1 360/182.2 25 mm 45/0.310 2000/50.8 Ex. 2 189 1025 0.4 16 Signature 1.25 360/182.2 25 mm 45/0.310 2000/50.8 Ex. 2 201 123 0.48 17 Signature 1.25 360/182.2 25 mm 45/0.310 2000/50.8 Ex. 3 187 116 0.46 18 Signature 1 360/182.2 25 mm 45/0.310 2000/50.8 Ex. 2 158 88 0.35 19 Signature 1 360/182.2 25 mm 45/0.310 2000/50.8 Ex. 1 197 122 0.48 20 Signature 1.25 360/182.2 25 mm 45/0.310 2000/50.8 Ex. 1 232 138 0.54

(8) All tests show adhesion and good bonding. The data from runs 2, 3, 4, 45, 9, 12, 15, 16, 17, 19 and 20 show values that all exceeded requirements for a successful construction manufacture.

(9) These data indicate 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.

(10) Melt viscosity is generally directly related to a polymer molecular weight and is reported in millipascal-second (mP.Math.s) or centipoises (cP) using a Brookfield DV—II+Pro (Rotation 10 rpm—Spindle # SC4-27) at the stated temperature.

(11) 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 measure the precise temperature at which a disc of polymer sample, heated at as rate of 2° C. per minute of 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 reports in degrees Centigrade or degrees Fahrenheit is important because it typically indicates the polymer's heat resistance useful application temperatures and solidification points.

(12) Peel test values were obtained by forming a laminate from a SMS non-woven (11.6 g-m.sup.−2) micro-porous polyethylene film (0.5 mil/0.127 micron) using lamination conditions as shown in Table 4. The laminate is cut into 1 inch/25.4 mm wide strips in the cross machine direction. Peel force was measured by separating the laminate at room temperature using a TMas pull tester at a rate of 20 in-sec.sup.−1/50.8 cm-sec.sup.−1 with the peek force averaged over a 15 period.

(13) 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.