US 2003/0149166 A1 · Aqueous silicone emulsion, of use as base for preparing a water-repellent and anti-adhesive paper coating, process for preparing an emulsion of this type and anti-adhesive coatings

Abstract

The invention concerns an aqueous silicone emulsion for the preparation of anti-adherent coating on fibrous or non fibrous supports for example paper. Said emulsion comprises polyorganosiloxanes (POS) with Si-vinyl units and POS with SiH units, cross-linkable by polyaddition in the presence of a platinum catalyst. Known emulsions of this type are not stable and tend to be cross-linked prematurely and to produce a chemical foam. Said undesirable phenomena constitute a great nuisance for industrial machines used for anti-adherent paper coating. The invention solves this problem by proposing an emulsion having the following composition: POS A with the Si-Vi units, POS B with SiH units, platinum catalyst C, agent T for setting and maintaining pH between 5 and 9, preferably between 6 and 8; T being preferably a buffer solution (NaHCO3); an emulsifying agent D (polyvinyl alcohol); optionally a polyaddition inhibitor E and optionally other additives F such as filler, biocide, antifoam, anti-freeze, colouring agent, synthetic latex and the like. The invention also concerns a method for preparing said emulsions and methods for coating supports, for example paper, using said emulsion. The invention is applicable for making paper anti-adherent.

Claims10

Dependent claims

Aqueous silicone emulsion which can be used in particular as coating base for the preparation of anti-adhesive and water-repellent coatings, this emulsion being of the type of that comprising:

at least one polyorganosiloxane (A) (POS) carrying Si-EU units with EU representing a group comprising at least one ethylenic unsaturation, preferably a vinyl unsaturation, and at least one POS (B) carrying SiH units;
the latter being capable of reacting by polyaddition with the SiEU units,
a metal catalyst (C), preferably a platinum catalyst,
hydroxyl radicals capable of reacting with SiH units by dehydrogenation/condensation,
characterized in that it additionally comprises at least one agent (T) for fixing and maintaining the pH between 5 and 9, preferably between 5.5 and 8.5 and more preferably still between 6 and 8, this agent advantageously being a buffer system.

2 more elements

Process for the preparation of an aqueous silicone emulsion which can be used in particular as coating base for the preparation of anti-adhesive and water-repellent coatings,

this emulsion being of the type of that comprising:
at least one polyorganosiloxane (A) (POS) carrying Si-EU units with EU representing a group comprising at least one ethylenic unsaturation, preferably a vinyl unsaturation, and at least one POS (B) carrying Si—H units, the latter being capable of reacting by polyaddition with the Si-EU units;
a metal catalyst (C), preferably a platinum catalyst;
hydroxyl radicals capable of reacting with SiH units by dehydrogenation/condensation;
characterized in that it consists essentially in preparing a dispersion of silicone phase in water while taking care:
→to fix the pH of the final emulsion between 5 and 9, preferably between 5.5 and 8.5 and more preferably still between 6 and 8,
→and to see to it that this pH is permanently maintained.

4 more elements

Dependencies are inferred from the claim text.

Aqueous silicone emulsion, of use as base for preparing a water-repellent and anti-adhesive paper coating, process for preparing an emulsion of this type and anti-adhesive coatings

Life of this patent

Aqueous silicone emulsion, of use as base for preparing a water-repellent and anti-adhesive paper coating, process for preparing an emulsion of this type and anti-adhesive coatings

Life of this patent

Abstract

Claims10