Two-component lamination adhesive of renewable origin

1. A two-component lamination adhesive comprising an —NCO component and an —OH component, wherein the —NCO component is obtained by reacting, according to a polyaddition reaction, a stoichiometric excess of an aromatic or aliphatic polyisocyanate (A) with a composition (B) formed of diols comprising, on the basis of the total weight of said composition:

from 60 to 100% by weight of a composition (B1) comprising one or more di(polyricinoleate) diols having a hydroxyl number N OH of between 30 and 70 mg KOH/g and formula (I):

in which:

A represents a divalent hydrocarbon radical optionally interrupted by one or more oxygen or sulfur heteroatoms;

m and n, which are identical or different, represent 0 or an integer ranging from 1 to 11 and are such that m+n varies from 0 to 11; and

from 0 to 40% by weight of a composition (B2) comprising diols having an N OH of between 72 and 360 mg KOH/g and which are:

dimerized fatty alcohols comprising from 20 to 44 carbon atoms, or

di(polyricinoleate) diols having formula (II):

in which:

B represents a radical as defined above for A which is identical to or different from the radical represented by A;

p and q, which are identical or different, represent 0 or an integer ranging from 1 to 3 and are such that p+q varies from 0 to 3.

2. The two-component lamination adhesive as claimed in claim 1 , wherein the Brookfield viscosity at 40° C. of the —NCO component after mixing (A) and (B) is within the range extending from 500 to 2000 mPa·s.

3. The two-component lamination adhesive as claimed in claim 1 , wherein the Brookfield viscosity at 40° C. of the —NCO component after mixing (A) and (B) is within the range extending from 500 to 1500 mPa·s.

4. The two-component lamination adhesive as claimed in claim 1 , wherein the divalent hydrocarbon radical A corresponds to a diol of formula:

HO-A-OH  (VI)

each of the 2 —OH functional groups of which is replaced with a single bond and the hydroxyl number N OH of which is within the range extending from 110 to 1808 mg KOH/g.

5. The two-component lamination adhesive as claimed in claim 1 , wherein the divalent radical A corresponds to a diol of formula HO-A-OH (VI) chosen from:

(a) ethylene glycol;

(b) 1,4-butanediol;

(c) diethylene glycol;

(d) 1,4-cyclohexanedimethanol;

(e) a polypropylene glycol with a molar mass ranging from 400 g/mol to 1000 g/mol; or

(f) an aliphatic dimerized fatty alcohol comprising from 20 to 44 carbon atoms.

6. The two-component lamination adhesive as claimed in claim 1 , wherein the divalent radical A corresponds to a diol of formula HO-A-OH (VI) chosen from an aliphatic dimerized fatty alcohol comprising from 35 to 37 carbon atoms or a polypropylene glycol with a molar mass of 400 g/mol.

7. The two-component lamination adhesive as claimed in claim 1 , wherein the di(polyricinoleate) diols constituting the composition (B1) have a hydroxyl number N OH of between 35 and 65 mg KOH/g.

8. The two-component lamination adhesive as claimed in claim 1 , wherein the composition formed of diols (B) comprises from 70 to 100% by weight of (B1) and from 0 to 30% weight/weight of (B2).

9. The two-component lamination adhesive as claimed in claim 1 , wherein the polyisocyanate (A) is 2,4′- or 4,4′-diphenylmethane diisocyanate (MDI).

10. The two-component lamination adhesive as claimed in claim 1 , wherein the —OH component is a composition comprising at least approximately 80% by weight of ricinoleic acid triglyceride.

11. The two-component lamination adhesive as claimed in claim 1 , wherein the —NCO and —OH components are present in an amount corresponding to an —NCO/—OH molar ratio of approximately 2.

12. The two-component lamination adhesive as claimed in claim 1 , wherein the di(polyricinoleate) diol of formula I is prepared by transesterifying a triglyceride of ricinoleic acid of formula III

with an alcohol of formula R 1 OH, in which R 1 is C 1-4 -alkyl, to produce a ricinoleic acid monoester of formula IV

transesterfying IV to obtain a polyricinoleate of formula V

and transesterfying V with a compound of formula VI

HO-A-OH  (VI).

13. A multilayer film comprising 2 thin layers bonded to one another by a continuous layer, wherein the continuous layer is composed of the two-component lamination adhesive as defined in claim 1 in the crosslinked state and in an amount of less than 10 g/m 2 .

14. A process for the continuous preparation of the multilayer film as defined in claim 13 , comprising the sequential stages of:

(i) combining the —NCO and —OH components in the form of an adhesive mixture rendered flowable by heating,

(ii) coating a first thin layer with said adhesive mixture to form a substantially continuous layer,

(iii) laminating a second thin layer over the first thin layer with the coating formed in stage (ii), then

(iv) crosslinking the adhesive mixture.

15. The process according to claim 14 , wherein heating in (i) is to a temperature of 40-80° C.

16. A flexible packaging material comprising the multilayer film as claimed in claim 13 .

17. A two-component lamination adhesive comprising an —NCO component and an —OH component, wherein the —NCO component is obtained by reacting, according to a polyaddition reaction, a stoichiometric excess of an aromatic or aliphatic polyisocyanate (A) with a composition (B) formed of diols comprising, on the basis of the total weight of said composition:

from 60 to 100% by weight of a composition (B1) comprising one or more di(polyricinoleate) diols having a hydroxyl number N OH of between 30 and 70 mg KOH/g and formula (I):

in which:

A represents a divalent hydrocarbon radical optionally interrupted by one or more oxygen or sulfur heteroatoms;

m and n, which are identical or different, represent 0 or an integer ranging from 1 to 11 and are such that m+n varies from 0 to 11; and

from 0 to 40% by weight of a composition (B2) comprising diols having an N OH of between 72 and 360 mg KOH/g and which are:

dimerized fatty alcohols comprising from 20 to 44 carbon atoms, or

di(polyricinoleate) diols having formula (II):

in which:

B represents a radical as defined above for A which is identical to or different from the radical represented by A;

p and q, which are identical or different, represent 0 or an integer ranging from 1 to 3 and are such that p+q varies from 0 to 3, wherein the —NCO component is obtained by reacting, according to a polyaddition reaction, an aromatic or aliphatic polyisocyanate (A) with a composition formed of diols (B), in an amount of (A) and (B) corresponding to a —NCO/—OH equivalent ratio of between 2 and 10.