Non-reactive hot melt adhesive, its manufacture and its use in sealing packages

Patent metadata

Field	Value
Publication number	US-9902885-B2
Application number	US-201515311811-A
Country	US
Kind code	B2
Filing date	May 28, 2015
Priority date	Jun 3, 2014
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

A non-reactive hot melt adhesive containing a copolymer being substantially composed of a reaction product of lactide (L) and caprolactone (C) in a molar ratio (L/C) of at least 1.5. The adhesive further includes a carbodiimide compound. The presence of a small but effective amount of carbodiimide causes a stabilizing effect on the sealing properties of the adhesive, especially if it is exposed to higher temperatures. A method manufactures the adhesive and a method seals a package with the adhesive.

First claim

The invention claimed is:

1. A non-reactive hot melt adhesive containing a copolymer being substantially composed of a reaction product of lactide (L) and caprolactone (C) in a molar ratio (L/C) of at least 1.5, wherein the adhesive further comprises a carbodiimide compound, and
the amount of carbodiimide ranges between 0.05 and 2.5% by weight as determined on the amounts of carbodiimide and the copolymer.

2. The non-reactive hot melt adhesive according to claim 1 , wherein the mean molecular weight Mn of the copolymer ranges between 10000 g/mole and 50000 g/mole.

3. The non-reactive hot melt adhesive according to claim 1 , wherein the adhesive further comprises a tackifier in an amount of up to 80% by weight, based on the total weight of the adhesive.

4. The non-reactive hot melt adhesive according to claim 1 , wherein the adhesive further comprises a plasticizer in an amount of up to 40% by weight, based on the total weight of the adhesive.

5. The non-reactive hot melt adhesive according to claim 1 , wherein the adhesive further comprises a stabilizer.

6. A method for the manufacture of a non-reactive hot melt adhesive containing a copolymer being substantially composed of a reaction product of lactide (L) and caprolactone (C) in a molar ratio (L/C) of at least 1.5, the method having the following steps:
polymerizing a mixture comprising lactide and caprolactone in a molar ratio of at least 1.5 in the presence of a polymerization catalyst,
adding an amount of carbodiimide to the resulting copolymer of lactide and caprolactone in liquid phase, after completion of the reaction,
wherein the amount of carbodiimide ranges between 0.05 and 2.5% by weight as determined on the amounts of carbodiimide and the copolymer.

7. The method according to claim 6 , wherein the polymerization is performed at a temperature of 160-200° C.

8. The method according to claim 6 , wherein an amount of a mono-alcohol is added to the mixture.

9. The method according to claim 6 , wherein an amount of a di-alcohol is added to the mixture.

10. The method according to claim 6 , wherein an amount of a catalyst deactivating agent is added to the mixture after completion of the reaction.

11. The method according to claim 6 , wherein a tackifier is added to the mixture in an amount of up to 80% by weight as determined on the total weight of the adhesive.

12. The method according to claim 6 , wherein a plasticizer is added to the mixture in an amount of up to 40% by weight as determined on the total weight of the adhesive.

13. A method for sealing a package made of a package material whereby an amount of a non-reactive hot melt adhesive in liquid form is applied to a first surface of the package material, after which this surface and another surface of package material are contacted, wherein the non-reactive hot melt adhesive according to claim 1 is used.

14. The method for sealing a package according to claim 13 , wherein the package material is composed of cardboard material.

15. The method for sealing a package according to claim 13 , wherein the surface of package material is coated with a layer of polyolefin.

16. The non-reactive hot melt adhesive according to claim 1 , wherein the amount of carbodiimide ranges between 0.5 and 2.5% by weight as determined on the amounts of carbodiimide and the copolymer.

17. The method according to claim 6 , wherein the amount of carbodiimide ranges between 0.5 and 2.5% by weight as determined on the amounts of carbodiimide and the copolymer.

Assignees

• Purac Biochem Bv
• Purac Biochem Bv

Inventors

• Schaekens Chris François Hubert

Classifications

• C09J7/35

  Heat-activated · CPC title

• C09J11/06

  organic · CPC title

• C09J167/04 Primary

  Polyesters derived from hydroxycarboxylic acids, e.g. lactones (C09J167/06 takes precedence) · CPC title

• B65B51/10

  Applying or generating heat or pressure or combinations thereof {(welding of plastics per se B29C65/02; closing plastic tube ends in general B29C57/10)} · CPC title

• C08K5/29

  Compounds containing {one or more} carbon-to-nitrogen double bonds · CPC title