Process for manufacturing and bonding a shoe rubber outsole

Abstract

The present invention relates to a process for manufacturing a shoe rubber outsole using a special heat and pressure stable water-based polyurethane dispersion adhesive without a pre-treatment of UV irradiation or plasma, as well as a process for manufacturing a shoe using the outsole manufactured as described herein and an PUD-based adhesive composition for the described processes.

Claims

1. A process for manufacturing a shoe rubber outsole, comprising the steps of: 1) providing an uncured rubber material; 2) applying an adhesive composition to the uncured rubber material of the step (1) and drying the rubber material, wherein said adhesive composition comprises a heat and pressure stable water-based polyurethane dispersion; and 3) curing the rubber material obtained in the step (2), wherein the adhesive composition comprises, based on the total weight of the composition: a) 85 to 99.9 wt. % of a water-based polyurethane dispersion; b) 0.1 to 1 wt. % of at least one cross-linker; c) 0.1 to 10 wt. % of at least one modified polyolefin based adhesion promoter; d) 0 to 5 wt. % of at least one filler; e) 0 to 0.1 wt. % of at least one optical brightener; and f) 0 to 1 wt. % of at least one hydrophobically modified ethylene oxide-urethane block copolymer (HEUR) thickener.

2. The process according to claim 1, wherein (i) the uncured rubber material in step (1) is a shoe rubber outsole preform; and (ii) the rubber material obtained in step (2) is cured and formed to a shoe rubber outsole in step (3); and (iii) the curing in step (3) is by heat-pressing.

3. The process according to claim 1, wherein the process does not comprise an additional step of treating the uncured rubber material by UV irradiation or plasma.

4. The process according to claim 1, wherein the water-based polyurethane dispersion is an NCO-terminated polyurethane obtained from a reaction mixture comprising a polyester polyol and a polyisocyanate wherein the polyester polyol is prepared with adipic acid and 1,4-butanediol, wherein the polyisocyanate is selected from hexamethylenediisocyanate (HDI) or isophoronediisocyanate (IPDI), and wherein the reaction mixture has a molar excess of the hydroxyl group than the isocyanate.

5. The process according to claim 1, wherein the cross-linker is selected from the group consisting of polycarbodiimides and polyaziridines.

6. The process according to claim 1, wherein the modified polyolefin based adhesion promoter comprises modifying polyolefins with unsaturated carboxylic acid modification, acid anhydride modification, acryl modification, chlorinating modification or combinations thereof.

7. The process according to claim 1, wherein the filler is fumed silica.

8. The process according to claim 1, wherein the adhesive composition is liquid and has a viscosity of less than 5,000 mPa.Math.s at 25° C. as determined by a Brookfield viscometer (Spindle No. 63, 12 rpm).

9. A process for manufacturing a shoe, comprising (1) manufacturing the shoe rubber outsole according to claim 1; (2) thermally activating the shoe rubber outsole of step 1; and (3) attaching the activated shoe rubber outsole of step 2 to shoe.

10. The process according to claim 9, wherein the process does not comprise additional steps of degreasing, cleaning, priming or applying adhesive to the shoe rubber outsole prior to the step (3).

11. An adhesive composition for an uncured rubber material, comprising based on the total weight of the composition: a) 85 to 99.9 wt. % of a water-based polyurethane dispersion; b) 0.1 to 1 wt. % of at least one cross-linker; c) 0.1 to 10 wt. % of at least one modified polyolefin based adhesion promoter comprising a modified polyolefin, a (meth)acrylate, and an emulsifier; d) 0 to 5 wt. % of at least one filler; e) 0 to 0.1 wt. % of at least one optical brightener; and f) 0 to 1 wt. % of at least one hydrophobically modified ethylene oxide-urethane block copolymer (HEUR) thickener.

12. An article comprising a substrate and the adhesive composition according to claim 11.

13. The article of claim 12, wherein the substrate is an uncured rubber material.

14. The article of claim 12, wherein the uncured rubber material is selected from the group consisting butadiene rubber, acrylonitrile-butadiene rubber or styrene-butadiene-styrene rubber.

15. The article of claim 12 is a shoe rubber outsole.

Description

EXAMPLES

Example 1: Adhesive Composition

[0064]

TABLE-US-00001 parts by No. Material weight 1 Polyester PUD 93.0 (based on NCO-terminated polyurethane prepolymer prepared from adipic acid/1,4-butanediol and HDI(base)/IPDI) solid content: 48-50% particle size: 200-240 nm (determined by DLS) 2 Modified polyolefin (about 10% aqueous solution 5.0 containing (meth)acrylate and emulsifier, commercially available from Soo Technical Corporation, South Korea under the trade name of ST-NIC-2000) 3 N,N′-dicyclohexylcarbodiimide or N,N′- 0.2 diisopropylcarbodiimide (in 2-methoxy-1-methylethyl acetate) 4 Fumed silica 1.0 (15% solution in water) 5 Optical brightener (Tinopal ® NFW 10 liquid, 0.02 commercially available from BASF) 6 HEUR type thickener 0.5

Manufacture:

[0065]

TABLE-US-00002 1. Input material no. 1 into tank and start mixing for 30 minutes. 2. Mix material no. 2 and no. 3 in sequence and mix for 1 hr at room temperature. 3. Input material no. 4 slowly and mixing for 1 hour. 4. Input material no. 5 slowly and mixing for 1 hour. 5. Input material no. 6 by dropping around for 1 hour and mixing for 3 hours.

Example 2: Shoe Manufacture

[0066] The adhesive composition according to example 1 was uniformly applied to an unvulcanized rubber outsole using a sprayer and then a rubber vulcanization process was performed at 160° C. and 150 bar for 420 seconds. The vulcanized rubber outsole was thermally activated in a heating chamber at 55° C. for about 100 seconds. Thereafter, the thermally activated rubber outsole was manually attached to a midsole and an upper and then further attached using a hydraulic walled sole attaching machine to manufacture a shoe.

[0067] After 1 day and/or 18 days, tests for measuring the bonding strength between the rubber outsole and the midsole were conducted by measuring peel strength using a peel tester (5580, Instron).

[0068] The bonding strength of a shoe manufactured according to the present invention was 7.5 and 8.1 kgf/cm.sup.2 after 1 day and 18 days respectively and the rubber materials were broken. It was also observed for a shoe that had been manufactured using the same process but Dispercoll U 2793 XP (PUD-based adhesive, commercially available from Bayer MaterialScience), that the bonding strength showed only 4.0 and 4.3 kgf/cm.sup.2 after 1 day and 18 days respectively and the adhesives were separated from the rubber material.

[0069] For comparative purposes, the average bonding strength of a shoe manufactured according to a conventional manufacturing process using UV radiation pre-treatment as described in Example 1 of WO 2017103063 A1, and of a shoe manufactured according to the process steps of the present invention but using an adhesive composition having no adhesive promoter were also determined as 5.0 kgf/cm.sup.2, and 3.5 kgf/cm.sup.2 with point failure, respectively, which were significantly lower than that achieved according to the process of the present invention.