High performance anti-block treatments for viscoelastic solids
Anti-blocking compositions are disclosed that include a wax or mixture of waxes effective to reduce, retard or prevent blocking of a viscoelastic solid when applied to the surface of such a solid. Also disclosed are methods of reducing, retarding or preventing blocking of a viscoelastic solid, and the products of those methods which are viscoelastic solids resistant to blocking.
1. An anti-blocking composition comprising:
at least one wax comprising a water-based emulsion formed from a mixture of a homopolymer selected from a polyethylene homopolymer and an oxidized polyethylene homopolymer; and a copolymer selected from an ethylene acrylic acid copolymer and an ethylene-vinyl acetate copolymer; wherein said at least one wax is utilized in an amount effective to reduce blocking of a viscoelastic solid when said composition is applied to the surface of said viscoelastic solid.
2. The anti-blocking composition of claim 1 , wherein said at least one wax comprises about 20 weight % to about 50 weight % of said water-based emulsion or dispersion on the total weight of the emulsion or dispersion.
3. The anti-blocking composition of claim 1 , further comprising at least one of the materials selected from:
a. a surfactant,
b. a water-soluble polymeric material, and
c. a wetting agent;
wherein the molten state of a viscoelastic solid coated with said anti-blocking composition retains the thermal and physical stability of a corresponding uncoated viscoelastic solid.
4. The anti-blocking composition of claim 3 , wherein said surfactant is present in about 0.5 to about 10.0 weight % based on the total composition.
5. The anti-blocking composition of claim 3 , wherein said water-soluble polymeric material is present in about 0.2 to about 5.0 weight % based on the total composition.
6. The anti-blocking composition of claim 3 , wherein said wetting agent is present in about 0.05 to about 0.50 weight % based on the total composition.
7. The anti-blocking composition of claim 1 , wherein said at least one wax has a weight average molecular weight of about 1000 to about 15000 Daltons.
8. The anti-blocking composition of claim 1 , wherein said water-based emulsion is formed in the presence of 2-Dimethylaminoethanol.
9. A method of reducing blocking of a viscoelastic solid, comprising the steps of:
a) treating the surface of a viscoelastic solid after manufacture with an anti-blocking composition comprising a water-based emulsion formed from a mixture of a homopolymer selected from a polyethylene homopolymer and an oxidized polyethylene homopolymer; and a copolymer selected from an ethylene acrylic acid copolymer and an ethylene-vinyl acetate copolymer; and
b) drying;
thereby providing a viscoelastic solid coated with said anti-blocking composition components.
10. The method of claim 9 , wherein said viscoelastic solid is selected from the group consisting of a hot melt adhesive, a hot melt pressure-sensitive adhesive, a hot melt paint and a thermoplastic elastomer.
11. A coated viscoelastic solid resistant to blocking which is the product of the method of claim 9 , wherein the surface of said viscoelastic solid is coated with an anti-blocking wax or mixture of waxes, and one or more of:
a. a surfactant,
b. a water-soluble polymeric material, and
c. a wetting agent;
wherein the molten state of said coated viscoelastic solid retains the thermal and physical stability of a corresponding uncoated viscoelastic solid.
12. The coated viscoelastic solid of claim 11 , wherein the surfactant is present in about 0.002 to about 0.25 weight % based on the total weight.
13. The coated viscoelastic solid of claim 11 , wherein the water-soluble polymeric material is present in about 0.001 to about 0.15 weight % based on the total weight.
14. The coated viscoelastic solid of claim 11 , wherein the wetting agent is present in about 0.0002 to about 0.01 weight % based on the total weight.