Hot-Melt Adhesive Composition Comprising Bio-Based Polyester Polyols

Abstract

The present invention relates to a hot-melt adhesive composition comprising at least one polyester polyol based on Betulin and at least one NCO-terminated compound as well as a method for the production of a laminated article using the inventive hot-melt adhesive composition.

Claims

1. A hot-melt adhesive composition comprising: a) at least one polyester polyol based on Betulin; and b) at least one NCO-terminated compound.

2. The hot-melt adhesive composition according to claim 1 having a softening point of no more than 120° C., determined according to the method of Ring & Ball.

3. The hot-melt adhesive composition according to claim 1 having a viscosity of 1000 to 100000 mPas, determined at 130° C. according to DIN EN ISO 2555/2000-01 (Brookfield Thermosel, spindle 27, 10 rpm).

4. The hot-melt adhesive composition according to claim 1 wherein the at least one polyester polyol based on Betulin is the reaction product of Betulin and at least one compound selected from the group consisting of dicarboxylic acid, short-chain polyols, amines, triglycerides and mixtures thereof.

5. The hot-melt adhesive composition according to claim 1 wherein the at least one polyester polyol based on Betulin comprises 5 to 80 mol-% of Betulin moieties.

6. The hot-melt adhesive composition according to claim 1 wherein the at least one NCO-terminated compound is derived from methylenediphenyl diisocyanate (MDI) or its isomers.

7. The hot-melt adhesive composition according to claim 1 comprising at least one polyester polyol based on Betulin in an amount of 10 to 30 wt.-%, based on the total weight of the hot-melt adhesive composition.

8. The hot-melt adhesive composition according to claim 1 wherein the ratio of NCO/OH is 5:1 to 1:1.

9. The hot-melt adhesive composition according to claim 1 wherein the hot-melt adhesive is a 1K-polyurethane hot-melt adhesive.

10. The hot-melt adhesive composition according to claim 1 wherein the hot-melt adhesive is a 1K, moisture reactive polyurethane hot-melt adhesive.

11. The hot-melt adhesive composition according to claim 1 wherein the hot-melt adhesive composition does not contain any water or solvent.

12. The hot-melt adhesive composition according to claim 1 having an application temperature of no more than 170° C.

13. A method for the production of a laminated article comprising: i) providing a first substrate; ii) providing a second substrate; ii) applying a hot-melt adhesive composition according to claim 1 to at least part of at least one of the first or second substrates, and iii) contacting the first and second substrates with the applied adhesive to form a laminated article, wherein the hot-melt adhesive is applied at temperatures of no more than 170° C.

14. The method of claim 13 further comprising exposing the laminated article to moisture to cure the applied adhesive to an irreversible solid form.

15. An article comprising hot-melt adhesive composition according to claim 1.

16. cured reaction products of the hot-melt adhesive composition according to claim 1.

Description

EXAMPLES

[0049] The following polyester polyols were prepared; the composition being summarized in Table 1.

TABLE-US-00001 TABLE 1 Polyester polyol Composition PES 1 131.63 g Betulin (29.3 mol-%)  25.55 g butane diol (27.9 mol-%)  87.8 g sebacic acid (42.8 mol-%) PES 2 110.65 g Betulin (25 mol-%)  28.51 g butane diol (31.6 mol-%)  63.44 g adipic acid (43.4 mol-%) PES 3 338.55 g Betulin (23.98 mol-%)  87.12 g butane diol (30.31 mol-%) 274.35 g acelaic acid (45.71 mol-%) PES 4   177 g Betulin (46.6 mol-%)  7.73 g butane diol (10 mol-%) 215.27 g dimeric fatty acid (43.4 mol-%) PES 5   177 g Betulin (46.6 mol-%)  7.73 g butane diol (10 mol-%) 215.22 g dimeric fatty acid (43.4 mol-%)

[0050] The polyester polyols were found to have the following mechanical properties, summarized in Table 2.

TABLE-US-00002 TABLE 2 viscosity.sup.1) Tg.sup.2) acid OH Mn PES [mPas] [° C.] number.sup.3) number.sup.3) [g/mol].sup.4) polydispersity.sup.5) PES 1 1550 12 2.6 80 1933 2.1 PES 2 7500 29 2.8 59 2207 2.1 PES 3 630 −15 2.3 73 1725 2.2 PES 4 5500 20 2.9 28 3666 2.3 PES 5 7500 19 1.5 29 4188 2.5 .sup.1)at 130° C. determined with Brookfield Thermosel, spindle 27, 10 rpm .sup.2)glass transition temperature, determined with DSC .sup.3)[mg KOH/g], determined via titration .sup.4)determined with GPC .sup.5)determined with GPC

[0051] The obtained polyester polyols were reacted with diphenylmethylene diisocyanate (4,4′-MDI) (NCO content 33.6 wt.-%) with a ratio of NCO to OH of 2.2/1.

[0052] The obtained adhesive compositions were tested and compared to compositions employing a commonly used polyester polyol based on phthalic acid, commercially available under the trade name Dynacoll® 7130 from Evonik, Germany. The results are summarized in Table 3.

[0053] Tensile strength and e-modulus were determined according to EN ISO 527.

TABLE-US-00003 TABLE 3 Example 1 Example 2 Comp.-Ex. 1 Polyester polyol PES 2 PES 3 Dynacoll viscosity (@ 14000 8900 17000 130° C.; [mPas]) setting time [s] 65 40 60 open time [s] 80 60 100 tensile strength 8 12.2 4.1 [MPa] E-modulus [%] 3.6 4.1 44

[0054] As can be clearly seen from the provided data, the inventive hot-melt adhesive composition shows advantageous properties that even exceed those of conventionally used petrochemical-based alternatives, in particular with regard to tensile strength and e-modulus.

[0055] It was further found that the inventive hot-melt adhesive composition shows a surprisingly high hydrolysis stability. PES 1 and 5 as characterized in Table 1 above were reacted with 4,4′-MDI as described above to obtain an inventive hot-melt adhesive composition. The hydrolysis behavior of the obtained inventive hot-melt adhesive compositions was analyzed and compared with a conventional composition employing the polyester polyol sold under the trade name Dynacoll® 7130. After storing the samples for 6 days at 90° C. and 100% relative humidity, the inventive hot-melt adhesive composition did not change in the optical appearance whereas the comparative composition showed clear signs of decomposition. This was confirmed after storage under the same conditions for 21 days where the comparative composition was found to be completely decomposed. In contrast thereto, the inventive hot-melt adhesive compositions maintained their original appearance. The results are briefly summarized in Table 4.

TABLE-US-00004 TABLE 4 Storage Example 3 Example 4 Comp.-Ex. 2 time (PES 1) (PES 5) (Dynacoll ®)  6 days solid, slightly brittle, soft, elastic elastic no decomposition no decomposition decomposition 21 days solid, slightly brittle, brittle, elastic no decomposed no decomposition decomposition