Biodegradable graft polymers, their production, and their use in agrochemical formulations

A graft polymer comprising:

• (A) 20 to 95% of a polymer backbone as a graft base,
• which comprises at least one sub-unit (a1) and at least one sub-unit (a2), wherein
• (a1) is a unit comprising, moieties derived from at least one alkylene oxide monomer and/or at least one polyalkylene oxide-polymer having two hydroxy-end-groups, the alkylene oxide monomer selected from the group consisting of C2- to C10-alkylene oxides,
• (a2) is a unit comprising, moieties derived from at least one lactone and/or at least one hydroxy acid, such sub-unit (a2) being a moiety derived from a single lactone and/or hydroxy-acid or being oligo-or-polymeric units consisting of at least one type of lactone and/or at least one type of hydroxy acid,
• wherein the polymer backbone is
• a) obtained
• (A1) by co-polymerization of at least one sub-unit (a1) and at least one sub-unit (a2);
• (A2) by first oligo-/polymerizing sub-unit(s) (a2) and then polymerizing the product with sub-unit(s) (a1);
• (A3) By first oligo or polymerizing sub-unit(s) (a1) and then co-polymerizing the product with sub-unit(s) (a2);
• or
• (A4) by first providing an oligo- or polymeric sub-unit (a1) which bears an end-cap on one side, which is thereafter reacted as starter-block with at least one sub-unit (a2), wherein the sub-unit (a1) may be different to that or those in the starter block or may be arranged in a different order compared to those in the starter block, to attach to the non-end capped side of the starter block a new block comprising moieties from the sub-units employed for the (co-)polymerization, thereby obtaining a di-block-structure of [end-cap]-[sub-unit(s) (a1)]-[sub-unit(s) (a2)], or [end-cap]-[sub-unit(s) (a1)]-[random-{sub-unit(s) (a2)-sub unit(s) (a1)}];
• wherein in case more than one sub-unit (a1) and/or more than one sub-unit (a2) are present already in an employed oligomer or polymer, those sub-units can be arranged in any order within such employed oligomer or polymer, and
• wherein in case more than one sub-unit (a1) and/or more than one sub-unit (a2) are present for the polymerization, those sub-units and the optional oligomer/polymers if employed) can be arranged in any order within the obtained backbone;
• and wherein in case of (A1), (A2) and (A3) the use of a starter molecule is optional;
• or b) selected from the group consisting of:
• (A1) a backbone consisting of a randomly arranged order of monomeric, oligomeric and/or polymeric (a1)-sub-units and monomeric, oligomeric and/or polymeric (a2)-sub-units, with more than one sub-unit (a1) and/or more than one sub-unit (a2) being present;
• (A2) a backbone consisting of oligo- or polymerized sub-units (a2) as an inner block and two outer blocks of oligomeric and/or polymeric (a1)-sub-units, defined as “-[block of (a1)]-[block of (a2)]-[block of (a1)]”;
• (A3) a backbone consisting of an inner block of oligomeric and/or polymeric (a1)-sub-units and two outer blocks of oligo- or polymeric sub-units (a2), in the form of at least a tri-block-polymer defined as “-[block of (a2)]-[block of (a1)]-[block of (a2)]-”;
• and
• (A4) a backbone consisting of
• a first block with
• (i) on one end an end-cap, such end-cap being a C1 to C18 attached to said first block via an ether-function;
• and
• (ii) an oligo- or polymeric sub-unit (a1);
• and
• a second block which is attached to said first block at the opposite end of said first block, which is “opposite” in relation to the end-cap on said first block) via an ether or ester-function, said second block being composed of at least one sub-unit (a2) and optionally at least one sub-unit (a1), wherein the optional sub-unit(s) (a1) in said second block may be different to that or those in the first block or may be arranged in a different order compared to those in the first block, and the order of the sub-unit(s) (A1) and (a2) may be also in any order, including random structure,
• such di-block-structure having as an idealized structure in case of using only sub-unit(s) (a2) for the second block:
• [end-cap]-[sub-unit(s) (a1)]-[sub-unit(s) (a2)]
• or in case of using sub-unit(s) (a1) and (a2) for the second block:
• [end-cap]-[sub-unit(s) (a1)]-[random-{sub-unit(s) (a2)-sub unit(s) (a1)}];
• and wherein in case of (A1), (A2) and (A3) the use of a starter molecule is optional;
• and
• (B) 5 to 80% to of polymeric sidechains (B) grafted onto the polymer backbone (A), wherein said polymeric sidechains (B) are obtained by (co-)polymerization of at least one vinyl ester monomer (B1), optionally a nitrogen-containing monomer (B2), and optionally further monomer(s) (B3), and optionally further monomers,
• with all percentages as weight percent in relation to the total weight of the graft polymer.