Encapsulated pigments
Described are encapsulated pigments having an outer water-soluble shell and a core containing organic and/or inorganic pigments and optionally solvents and/or conventional additives. The encapsulated pigments have very good dissolution rates in aqueous systems and are therefore particularly suitable for paints, coatings, printing inks, in papermaking and in cosmetic formulations.
1. An encapsulated pigment comprising an outer water-soluble shell, said shell comprising a water-soluble film former of polyvinyl alcohol (PVOH) encapsulating a core, said core comprising at least one effect pigment which is a pearlescent pigment or a multilayered pigment based on SiO 2 flakes, glass flakes, or TiO 2 flakes, and, optionally, one or more solvents and/or conventional additives.
2. An encapsulated pigment according to claim 1 , wherein the outer shell consists of the water-soluble film former.
3. An encapsulated pigment according to claim 1 , wherein the shell/core weight ratio is from 50:50 to 0.5:99.5.
4. An encapsulated pigment of claim 1 , wherein the % weight of the core is >80% based on the total weight of the encapsulated pigment.
5. An encapsulated pigment according to claim 1 , wherein the dissolution rate of the shell in de-ionized water stirred at 300 rpm and at room temperature is <60 seconds.
6. An encapsulated pigment according to claim 1 , wherein the core comprises at least one pearlescent pigment which is based on a TiO 2 - and/or Fe 2 O 3 -coated mica flake, glass flake, Al 2 O 3 flake or SiO 2 flake.
7. An encapsulated pigment according to claim 1 , wherein the core comprises at least one pearlescent pigment which has a TiO 2 —SiO 2 —TiO 2 layer sequence.
8. An encapsulated pigment according to claim 1 , wherein the core further comprises at least one additive which is an antifoam agent, surface-active substance, wetting agent, antisettling agent, preservative, UV stabilizer, flow-control agent, neutralizer, modifier, siccative or thixotropic agent.
9. A paint, coating, powder coating, printing ink, papermaking, paper coating, security printing ink, plastic or cosmetic composition comprising an encapsulated pigment of claim 1 and water.
10. An encapsulated pigment of claim 1 , wherein the shell/core weight ratio is from 10:90 to 5:95.
11. An encapsulated pigment of claim 1 , wherein the outer water-soluble shell has a thickness of 0.01-1.0 mm.
12. An encapsulated pigment according to claim 1 , wherein the water-soluble film former has an acid number of from 120 to 280 mg of KOH/g.
13. An encapsulated pigment of claim 1 , wherein the outer water-soluble shell is provided such that when 10 g of the encapsulated pigment is provided in 90 g of de-ionized water at room temperature with stirring at 300 rpm, the shell will dissolve within one minute.
14. An encapsulated pigment according to claim 1 , wherein the film former is a polyvinyl alcohol (PVOH), which has the following properties:
ester value in accordance with DIN 53401 in mg of KOH/g =1-250,
degree of hydrolysis in mol %=80-100,
viscosity in accordance with DIN 53015 in mPas=2-60,
residual acetyl content=0.1-20, and
ash content in %, calculated as Na 2 O=0.5-1.
15. An encapsulated pigment according to claim 1 , wherein the water-soluble film former has an acid number of from 90 to 350 mg of KOH/g.
16. An encapsulated pigment comprising an outer water-soluble shell, said shell comprising a water-soluble film former having an acid number of from 90 to 350 mg of KOH/g, encapsulating a core, said core comprising at least one organic and/or inorganic pigment and, optionally, one or more solvents and/or conventional additives, wherein the outer water-soluble shell has a thickness of 0.01-1.0 mm.