Elastic attachment hot melt adhesive composition and a disposable absorbent article made with the same

Abstract

The invention features a hot melt adhesive composition based on olefin polymers that can be used for elastic attachment in the manufacture of a disposable article. The hot melt adhesive includes from about 3 to about 10% by weight of a first propylene-based copolymer having a melt index measured by ASTM D1238 (190 C., 2.16 kg) of no greater than about 5, a second propylene-based polymer with a viscosity at 190 C. of no greater than about 5000 cps, a first tackifying agent having a softening point of at least about 90 C. and from about 5% by weight to about 20% by weight of a plasticizer.

Claims

1. A hot melt adhesive composition comprising: a. from about 3 to about 10% by weight of a first propylene-based copolymer that is single-site catalyzed having a melt index measured by ASTM D1238 (190 C., 2.16 kg) of no greater than about 5, b. a second propylene-based polymer that is single-site catalyzed with a viscosity at 190 C. of no greater than about 5000 cps, c. a first tackifying agent having a softening point of at least about 90 C. and d. from about 5% by weight to about 20% by weight of a plasticizer.

2. The hot melt adhesive composition of claim 1 wherein the first tackifying agent is present at from about 20% to about 70% by weight.

3. The hot melt adhesive composition of claim 1 wherein the first tackifying agent has a softening point of at least about 110 C.

4. The hot melt adhesive composition of claim 1 wherein the first propylene-based copolymer has an ethylene content of no less than about 10.

5. The hot melt adhesive composition of claim 1 wherein the first propylene-based copolymer is present at from about 3% by weight to about 7% by weight.

6. The hot melt adhesive composition of claim 1 wherein the second propylene-based polymer has a viscosity at 190 C. of no greater than about 3,000 cps.

7. The hot melt adhesive composition of claim 1 wherein the second propylene-based polymer has a viscosity at 190 C. of no greater than about 2,000 cps.

8. The hot melt adhesive composition of claim 1 wherein the second propylene-based polymer is present at from about 7% to about 20% by weight.

9. The hot melt adhesive composition of claim 1 further comprising a third polymer.

10. The hot melt adhesive composition of claim 9 wherein the first propylene-based copolymer, second propylene-based polymer, third polymer, first tackifying agent and plasticizer makes up at least 90% of the adhesive composition.

11. The hot melt adhesive composition of claim 1 wherein the total of the first propylene-based copolymer and the second propylene based polymer is no less than about 10% by weight.

12. The hot melt adhesive composition of claim 1 having a viscosity of from about 3,000 cps to about 20,000 cps at 177 C.

13. The hot melt adhesive composition of claim 1 having a creep (37.8 C., 4 hours) of no greater than 35%.

Description

EXAMPLES

(1) Test Procedures

(2) Test procedures used in the examples and throughout the specification, unless stated otherwise, include the following. The amounts of raw materials listed in Tables 2 and 3 are in weight percent.

(3) High Temperature GPC Molecular Weight Distribution Analysis

(4) The GPC molecular weight distribution curve of each polymer in Table 1 was obtained using a high temperature HPLC system with BHT-stabilized 1,2,4-Trichlorobenzene (TCB) mobile phase. The molecular weight data, was calculated versus polystyrene standards.

(5) GPC System: Agilent PL-GPC 220

(6) Mobile Phase: TCB stabilized with 0.0125% BHT

(7) Temperature: 160C

(8) Columns: PLgel 10 um mixed-B (3)

(9) Flow rate: 1.0 ml/min

(10) Injection Volume: 200 uL

(11) Concentration: 6.0 mg/ml (0.009 g/1.5 mL)

(12) Viscosity Test Method

(13) Viscosity is determined in accordance with ASTM D-3236 entitled, Standard Test Method for Apparent viscosity of Adhesives and Coating Materials, (Oct. 31, 1988), using a Brookfield Thermosel viscometer Model RVDV 2 and a number 27 spindle. The results are reported in centipoise (cps).

(14) Creep Determination

(15) Bond Preparation

(16) The hot melt adhesive is applied in molten form to 3 LYCRA 800 dtex strands (pre-stretched to 300%) using a Nordson SURE WRAP nozzle, an application temperature of 177 C. and a coat weight of 47.3 mg/strand/meter (1.2 mg/strand/inch). The adhesive was coated on the pre-stretched elastic strands, the strands were then laminated between a nonwoven (UNIPRO 45 available from Midwest Filtration LLC) and a polyethylene back sheet (DH284 available from Clopay).

(17) Bond Testing 1. Staple one end of the multi-strand elastic attachment lamination to the edge of a sturdy piece of cardboard with the nonwoven facing up. 2. Extend the sample to 100% of full extension being careful not to overextend the back sheet. 3. Mark the sample where it reaches the 300 mm marking on the cardboard. 4. Relax the sample until the sample marking reaches the 285 mm marking on the cardboard, and staple the other end of the attachment. The sample is now secured at 95% of full extension. 5. After at least five samples have been attached in this same manner, cut through the individual strands of elastic at each end of the attachments, allowing the strands to be able to move within the lamination. Be careful not to cut the entire polyethylene sheet. 6. Condition the board with the anchored test specimens at 37.8 C. (100 F.) for four hours. 7. Remove the board and specimens from the oven and mark the polyethylene where the elastic is still bonded, represented by the gathered portion of the attachment. 8. Measure the length of the initial bond (285 mm) and the bond length at four where the elastic is still bonded; calculate percent creep per calculation below. 9. Report average of five samples

(18) Calculations

(19) $\frac{\mathrm{Percent}\mathrm{Creep}=\mathrm{initial}\mathrm{length}-\mathrm{length}\mathrm{at}X\mathrm{hours}100}{\mathrm{initial}\mathrm{length}}$

(20) TABLE-US-00001 TABLE 1 Polymer Properties Second First polymer polymer Third polymer VISTAMAXX VISTAMAXX VISTAMAXX 6102 8880 6202 Supplier Exxon Exxon Exxon Mobil Chem. Mobil Chem. Mobil Chem. Co. Co. Co. Polymer Type PP/PE PP/PE PP/PE Copolymer Copolymer Copolymer Ethylene content 16 6 15 (weight %) Melt Index 3 Not Available 9.1 ASTM D1238 (190 C./2.16 kgs) Viscosity @ 190 C. Not 1200 Not (cP) Available Available Molecular Weight 315000 42200 215000 (Mw) by GPC (grams/mole) Density .862 .879 .861

(21) TABLE-US-00002 TABLE 2 Examples Comp Control 1* 1 Example 1 Example 2 Example 3 VISTAMAXX 2 3 5 5 6102 VISTAMAXX 14 13 16.9 12.5 8880 VISTAMAXX 14 13 9.1 12.5 6202 EASTOTAC 60 59 54.5 55 H130 CALSOL 550 10 12 14.5 15 Molten Viscosity 10625 10200 8500 13100 at 177 C. (cP) Creep - 37.8 C. 25 44 31 24 20 (100 F.), 4 hour (%) *Comparative 1 is NW1002P ZP a styrene block copolymer (SBC) based adhesive commercially available from HB Fuller Company

(22) TABLE-US-00003 TABLE 3 Examples Example 4 Example 5 Example 6 Example 7 VISTAMAXX 6102 5 5 5 5 VISTAMAXX 8880 10 16 16.9 12.1 VISTAMAXX 6202 10 15 9.1 12.3 EASTOTAC H130 52 54.5 ESCOREZ 5415 55 ESCOREZ 5600 53 CALSOL 550 12 14.5 15 BENZOFLEX 352 20 Additives 2.6 Molten Viscosity at 7575 19400 8500 10450 177 C. (cP) Creep - 37.8 C. 22 28 24 31 (100 F.), 4 hour (%)

(23) The adhesive compositions were prepared by combining and mixing the components in the percentages set forth in Table 2 in a sigma blade mixer operating at 177 C.

(24) The amount in the additives row, includes the total amount of antioxidant, co-extrusion coating and packaging film present in the adhesive.

(25) Other embodiments are within the claims.