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1. WO2016135341 - DEBONDABLE REACTIVE HOT MELT ADHESIVES

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[ EN ]

Claims

1. An electrically debondable reactive hot melt adhesive composition, comprising:

a) at least one isocyanate-functional polyurethane polymer; and

b) at least one organic or inorganic salt.

2. The electrically debondable reactive hot melt adhesive composition according to claim 1 , wherein the at least one isocyanate-functional polyurethane polymer is present in an amount of 20 to 90 % by weight of the adhesive composition.

3. The electrically debondable reactive hot melt adhesive composition according to claim 1 or 2, wherein the at least one organic or inorganic salt is present in an amount of 1 to 30 %, preferably in an amount of 1 to 16 % by weight of the adhesive composition.

4. The electrically debondable reactive hot melt adhesive composition according to any one of claims 1 to 3, wherein the composition comprises at least one polar compound, which is different from compounds a) and b).

5. The electrically debondable reactive hot melt adhesive composition according to claim 4, wherein the at least one polar compound is selected from the group consisting of propylene carbonate and poly(ethylene glycol)bis(2-ethylhexanoate).

6. The electrically debondable reactive hot melt adhesive composition according to any one of claims 1 to 5, wherein compound b) is a trifluoromethanesulfonate salt, preferably lithium trifluoromethanesulfonate.

7. The electrically debondable reactive hot melt adhesive composition according to any one of claims 1 to 6, wherein the free NCO content in the isocyanate-functional polyurethane polymer ranges from 0.1 to 5 %, preferably from 1 to 2.5 %.

8. The electrically debondable reactive hot melt adhesive composition according to any one of claims 1 to 7, further comprising one or more additives selected from the group consisting of plasticizers, adhesion promoters, pigments, corrosion inhibitors, leveling agents, gloss promoters, stability enhancers, anti-foaming agents, antioxidants and fillers, which are different from compounds a) to c).

9. A method for producing an electrically debondable reactive hot melt adhesive composition according to any one of claims 1 to 8, the method comprising blending of a reactive polyurethane hot melt in a molten state with the at least one organic or inorganic salt, wherein the reactive polyurethane hot melt comprises the isocyanate-functional polyurethane polymer and optionally one or more additives, wherein the blending is performed at temperatures such as to keep the hot melt in the molten state.

10. A method for forming a debondable adhesive bond between a first and a second substrate, the method comprising the steps of:

i) applying the electrically debondable reactive hot melt adhesive composition according to any one of claims 1 to 8 to the surface of the first substrate and optionally the surface of the second substrate:

ii) contacting the first and the second substrates such that the electrically debondable reactive hot melt adhesive composition is interposed between the two substrates:

iii) allowing formation of an adhesive bond between the two substrates to provide bonded substrates; and

iv) optionally applying a voltage to the bonded substrates whereby adhesion at least one interface between the electrically debondable reactive hot melt adhesive composition and a substrate surface is substantially weakened.

1 1 . The method according to claim 10, wherein

(1 ) the voltage applied ranges from 9 to 100 V, preferably from 9 to 48 V;

(2) the voltage is applied for an interval of 1 second to 20 minutes, preferably 1 second to 3 minutes; and/or

(3) the first and/or the second substrate are electrically conductive.

12. The method according to claim 10 or 1 1. wherein in step d) in addition to the voltage heating is applied to the bonded substrates, preferably heating at up to 80°C.

13. A bonded substrate obtained according to the methods of any one of claims 10 to 1 1 , wherein the bonded substrate can be debonded upon application of an electric voltage and, optionally, heat.