Bleaching agent, preparation and use of the same with polymerizable compositions for optical materials

A polymerizable composition for an optical material comprising:

• (A) a polymerizable component,
• (B) a colouring component comprising particles of a blue pigment (b1);
• (C) a polymeric dispersing agent to disperse the particles of the colouring component (B) in the polymerizable component (A);
• (D) an ultraviolet absorbing agent;
• and
• (E) a radical polymerization initiator,
• wherein the particles of the colouring component (B) have a z-average size equal to or lower than 400 nm, as measured by Dynamic Light Scattering technique according to the method ISO 22412:2017,
• the polymeric dispersing agent (C) comprises a polymeric part and one or more pigment affinitive-groups selected from:
• carboxylic group, sulphate group, sulphonate group, amine salts, phosphate group, phosphonate group, carbamate group, urea group, amide group or amine group, and
• wherein said polymerizable component (A) is a mixture of compounds selected from the group consisting of the following Formulas (3), (4) and (5):
• wherein in the Formula (4), X represents a divalent group derived from a linear or branched aliphatic diol having 2 to 8 carbon atoms or a trivalent to hexavalent group derived from a linear or branched aliphatic polyol having 3 to 10 carbon atoms and having 3 to 6 hydroxyl groups, and n is an integer of 2 to 6;
• wherein in the Formula (5), X represents a divalent group derived from a linear or branched aliphatic diol having 2 to 8 carbon atoms or a trivalent to hexavalent group derived from a linear or branched aliphatic polyol having 3 to 10 carbon atoms and having 3 to 6 hydroxyl groups, m and n represent integers of 0 to 6, and the sum of m and n is an integer of 2 to 6;
• with the proviso that when no compounds of Formula (3) and (4) are present, in the Formula (5) n represents integers of 1 to 6 and the sum of m and n is an integer of 2 to 6.

A process for preparing a polymerizable composition for an optical material comprising the following steps in sequence:

• providing a bleaching agent;
• mixing the bleaching agent with (AA) a polymerizable component comprising a compound including two or more allyloxycarbonyl groups and (D) an ultraviolet absorbing agent and (E) a radical polymerization initiator,
• wherein the providing the bleaching agent comprises the following steps in sequence:
• providing a pre-mixture by mixing:
• (A) a polymerizable component comprising an aromatic ester compound including two or more allyloxycarbonyl groups,
• (B) a colouring component comprising particles of a blue pigment (b1),
• (C) a polymeric dispersing agent to disperse the particles of the colouring component (B) in the polymerizable component (A),
• homogenizing the pre-mixture to obtain a bleaching agent in which the particles of the colouring component (B) have a z-average size equal to or lower than 400 nm, as measured by Dynamic Light Scattering technique according to the method ISO 22412:2017, and
• wherein the polymeric dispersing agent (C) comprises a polymeric part and one or more pigment affinitive-groups selected from:
• carboxylic group, sulphate group, sulphonate group, amine salts, phosphate group, phosphonate group, carbamate group, urea group, amide group or amine group.