Method for applying a material containing a meltable polymer with free NCO groups

1. A method of applying a material comprising a fusible polymer, comprising the step of:

applying a filament of an at least partly molten material comprising a fusible polymer from a discharge opening of a discharge element to a first substrate;

wherein

the fusible polymer has the following properties:

a melting point (DSC, differential scanning calorimetry; 2nd heating at heating rate 5° C./min) within a range from ≥35° C. to ≤150° C.;

a glass transition temperature (DMA, dynamic-mechanical analysis to DIN EN ISO 6721-1:2011) within a range from ≥−70° C. to ≤110° C.;

wherein the filament, during the application process, has an application temperature of ≥100° C. above a melting point of the fusible polymer for ≤20 minutes, and wherein, prior to application, the material is heated from a temperature of ≤40° C. to a maximum application temperature within ≤5 minutes, and

wherein there are free NCO groups in the material including the fusible polymer, and

wherein the fusible polymer, after heating to 20° C. above its melting point and cooling to 20° C. at a cooling rate of 4° C./min, within a temperature interval from 25° C. to 40° C. for ≥1 minute, has a storage modulus G′ (determined at the respective temperature with a plate/plate oscillation viscometer to ISO 6721-10 at a frequency of 1/s) of 400 kPa to ≤10 MPa and, after cooling to 20° C. and storage at 20° C. for 120 minutes, has a storage modulus G′ (determined at 20° C. with a plate/plate oscillation viscometer to ISO 6721-10 at a frequency of 1/s) of ≥20 MPa.

2. The method according to claim 1 , wherein a content of free NCO groups in the material including the fusible polymer is within a range from ≥0.1% by weight to ≤10% by weight (titrimetric determination to DIN EN ISO 11909), based on a total weight of the material containing a fusible polymer.

3. The method according to claim 1 , wherein ≥60 mol % to ≤100 mol % of the free NCO groups in the material including the fusible polymer are in the form of terminal NCO groups.

4. The method according to claim 1 , wherein the fusible polymer also has at least one of the following properties:

A1) a storage modulus G′ (plate/plate oscillation viscometer to ISO 6721-10 at a frequency of 1/s) at 20° C. above the melting point of ≥1·10 4 Pa;

A2) a storage modulus G′ (plate/plate oscillation viscometer to ISO 6721-10 at a frequency of 1/s) at 10° C. below the melting point with prior heating to a temperature of 20° C. above the melting point and subsequent cooling at a cooling rate of 1° C./min of ≤1·10 7 Pa;

A3) the storage modulus G′ (plate/plate oscillation viscometer to ISO 6721-10 at a frequency of 1/s) of the fusible polymer at the highest application temperature attained during the application process is a factor of ≥10 less than the storage modulus G′ (plate/plate oscillation viscometer to ISO 6721-10 at a frequency of 1/s) at a temperature of 20° C. above the melting point of the fusible polymer; or

A4) at least two of properties A1) to A3).

5. The method according to claim 1 , wherein the NCO groups in the material including the fusible polymer are present in a separate component having an average molecular weight Mn (determined by means of gel permeation chromatography against polystyrene standards and N,N-dimethylacetamide as eluent) of ≥340 g/mol to ≤10 000 g/mol.

6. The method according claim 1 , wherein there are also free groups having Zerewitinoff-active hydrogen atoms in the material including the fusible polymer.

7. The method according to claim 1 , wherein the filament is applied to the first substrate at a rate of ≥20 mm/s.

8. The method according to claim 1 , wherein the fusible polymer is selected such that, after storage at a maximum application temperature attained for a duration of ≤1 hour, a storage modulus G′ (DMA, dynamic-mechanical analysis to DIN EN ISO 6721-1:2011 at a frequency of 1/s) more than doubles or the storage modulus G′ (DMA, dynamic-mechanical analysis to DIN EN ISO 6721-1:2011 at a frequency of 1/s) falls to a value of less than half the starting value.

9. The method according to claim 1 , wherein the discharge element with its discharge orifice is run over the first substrate in contact with the first substrate at a constant pressure.

10. The method according to claim 1 , wherein the material is applied to the first substrate at a pressure of ≥0.001 bar.

11. The method according to claim 1 , wherein the fusible polymer comprises a polyurethane obtained from a reaction of a polyisocyanate component and a polyol component, where the polyol component includes a polyester polyol having a no-flow point (ASTM D5985) of ≥25° C.

12. The method according to claim 1 , wherein the material applied is contacted with a second substrate.

13. The method according to claim 1 , wherein the method comprises a method of producing an article from the material comprising a fusible polymer and the method comprises the steps of:

I) applying a filament of the at least partly molten material to a carrier so as to obtain a layer of the material, corresponding to a first selected cross section of the article;

II) applying a filament of the at least partly molten material to a previously applied layer of the material so as to obtain a further layer of the material, corresponding to a further selected cross section of the article and bonded to the layer applied beforehand; and

III) repeating step II) until the article has been formed.