Low-viscosity aqueous adhesive polymer dispersions
View Patent ↗The invention relates to low-viscosity, low-monomer aqueous polymer dispersions based on polychloroprene, and a process for the preparation thereof and the use thereof as a contact adhesive.
1. An aqueous polymer dispersion comprising a concentration of polychloroprene of less than or equal to 40 weight % and a residual monomer content of less than 50 ppm, wherein said aqueous polymer dispersion has a viscosity of less than 50 mPas, a pH stability of greater than 2 hours, and the viscosity of said aqueous dispersion changes by a factor of less than or equal to 3 over the range of from 10 to 1,000 /s.
2. The aqueous polymer dispersion of claim 1 , further comprising a total emulsifier concentration of less than 1.5 weight %.
3. The aqueous polymer dispersion of claim 1 , further comprising from 0.1 to 5 parts by weight of ageing/oxidation stabilizers, based on a solids concentration of polychloroprene of 100 parts.
4. The aqueous polymer dispersion of claim 1 , wherein said aqueous polymer dispersion has a Zn concentration of less than 0.24 weight %.
5. The aqueous polymer dispersion of claim 1 , wherein said aqueous polymer dispersion has a pH of 8 to 10.
6. The aqueous polymer dispersion of claim 1 , further comprising 40 to 100 parts by weight of silica/water-glass as a suspension of discrete particles in water, wherein the solids content of the silica suspension is used to calculate the parts and the polychloroprene solids content of a polychloroprene latex is set at 100 parts.
7. The aqueous polymer dispersion of claim 6 , wherein said silicas are aqueous silicon dioxide dispersions, the SiO 2 particles of which have a primary particle size of from 1 to 400 nm.
8. A process for preparing the aqueous polymer dispersion of claim 1 , comprising
a) continuously or discontinuously (co)polymerizing chloroprene in an aqueous emulsion, optionally with a defined amount of a regulator to form an aqueous polymer dispersion;
b) removing residual monomers from said aqueous polymer dispersion down to a value of less than 50 ppm;
c) optionally diluting said aqueous polymer dispersion with water; and
d) optionally storing said aqueous polymer dispersion under temperature-controlled conditions and/or concentrating and optionally subsequently diluting said aqueous polymer dispersion with water.
9. The process of claim 8 , wherein a) is carried out with 0 to 20 parts by weight, based on 100 parts by weight of chloroprene, of copolymerizable ethylenically unsaturated monomers in the presence of 0 to 1 mmol of a regulator, based on 100 g of monomer, at temperatures of 0 to 70 ° C. in said aqueous emulsion, the resulting aqueous polymer dispersion having a content which is insoluble in organic solvents of 0.1 to 90 weight %, based on the polymer.
10. The process of claim 8 , wherein a) is performed as a batch process or as a continuous process.
11. The process of claim 10 , wherein constituents are added in succession, simultaneously by means of static mixers/dynamic mixers, or combinations thereof, wherein the mixing times are less than 1 hour.
12. An adhesive composition comprising the aqueous polymer dispersion of claim 1 .
13. The adhesive composition of claim 12 , wherein said adhesive composition is applied by brush, roller, spray, or mist.
14. A substrate coated with the adhesive composition of claim 12 .
15. A process for producing a wet-in-wet bond on foams, comprising (1) applying the adhesive composition of claim 12 to a substrate by means of spray, brush, or roller application and (2) generating a wet bond before film formation after an air-drying time of less than 5 minutes.
16. A process for producing a wet-in-wet bond on foams, comprising (1) applying the adhesive composition of claim 12 to less than 75 g/m 2 , based on polychloroprene, on a substrate surface by means of spray, brush, or roller application and (2) generating a wet bond before film formation after an air-drying time of no less than 5 minutes and prolonging the contact time to more than 5 min without a loss of function.
17. The process of claim 15 , wherein (1) is achieved by conventional medium pressure spray application in the range of from 0.5 to 6 bar.
18. A process for producing composite materials, comprising bonding joint components with an adhesive composition comprising the aqueous polymer dispersion of claim 1 .
19. A foam bond in mattress and furniture/upholstery comprising the aqueous polymer dispersion of claim 1 .
20. A bonded substrate comprising the aqueous polymer dispersion of claim 1 , wherein said bonded substrate is selected from the group consisting of wood, thermoplastics, elastomers, thermoplastic elastomers, vulcanisates, textile woven fabrics, knitted fabrics, braided fabrics, metals, and stoneware, which have been concreted with one another and/or on to porous substrates having a density of less than 1 kg/liter.