REACTIVE POLYURETHANE HOT-MELT ADHESIVES

Abstract

The present invention relates to a composition comprising at least one crosslinkable thermoplastic polyurethane (P) and at least one compound (N) having a conjugated, nitrogen-containing aromatic structure as nucleating agent, wherein the compound (N) is a solid and is present in the composition in an amount within a range from 0.01% to 0.5% by weight, based on the thermoplastic polyurethane. The present invention further relates to a process for producing such compositions and to the use of the compositions of the invention as sealant, coating or adhesive

Claims

1. A composition, comprising: at least one crosslinkable thermoplastic polyurethane (P) and at least one compound (N) comprising a conjugated, nitrogen-containing aromatic structure as a nucleating agent, wherein the at least one compound (N) is a solid and is present in the composition in an amount of from 0.01% by weight to 0.5% by weight, based on the at least one crosslinkable thermoplastic polyurethane (P).

2. The composition of claim 1, wherein the nucleating agent is selected from the group consisting of a quinacridone, a monoazo compound, a perylene, a diketopyrrolopyrrole, an isoindoline, a phthalocyanine and derivatives thereof.

3. The composition of claim 1, wherein the nucleating agent is selected from the group consisting of a quinacridone, a perylene and derivatives thereof.

4. The composition of claim 1, wherein a total amount of nucleating agents is in a range of from 0.03% by weight to 0.1% by weight, based on the at least one crosslinkable thermoplastic polyurethane (P).

5. The composition of claim 1, comprising a nucleating agent that has been subjected to a treatment comprising grinding, treatment with a solvent, acids, alkalis, bleaches, crystallization or extraction, and finishing operations to reduce or prevent flocculation or lump formation, finishing operations to control a particle size, or finishing operations to regulate a viscosity.

6. The composition of claim 1, wherein the nucleating agent is a solid with a specific surface area in a range of from 10 m.sup.2/g to 150 m.sup.2/g.

7. A process for producing the composition of claim 1, the process comprising: (i) providing at least one crosslinkable thermoplastic polyurethane (P) or a reaction mixture for preparation of a crosslinkable thermoplastic polyurethane (R-P); (ii) adding at least one compound (N) that comprises a conjugated, nitrogen-containing aromatic structure as a nucleating agent to the at least one crosslinkable thermoplastic polyurethane (P) or to the reaction mixture for preparation of the crosslinkable thermoplastic polyurethane (R-P), where the at least one compound (N) is a solid; and (iii) mixing the nucleating agent and the at least one crosslinkable thermoplastic polyurethane (P) or the reaction mixture for preparation of the crosslinkable thermoplastic polyurethane (R-P), wherein a total amount of nucleating agents is in a range of from 0.01% by weight to 0.5% by weight, based on the at least one crosslinkable thermoplastic polyurethane (P) or the reaction mixture for preparation of the crosslinkable thermoplastic polyurethane (R-P).

8. The process of claim 7, wherein the nucleating agent is selected from the group consisting of a quinacridone, a monoazo compound, a perylene, a diketopyrrolopyrrole, an isoindoline, a phthalocyanine and derivatives thereof.

9. The process of claim 7, wherein the nucleating agent is selected from the group consisting of a quinacridone, a perylene and derivatives thereof.

10. The process of claim 7, wherein the total amount of nucleating agents is in a range of from 0.03% by weight to 0.1% by weight, based on the at least one crosslinkable thermoplastic polyurethane (P).

11. A sealant, coating or adhesive, comprising the composition of claim 1.

12. The sealant, coating or adhesive of claim 11, which is an adhesive, wherein the adhesive is a hotmelt adhesive, an assembly adhesive for fixing of a component, a bookbinding adhesive, an adhesive for production of a composite film, a laminate, a sandwich component, or an edgebanding product.

13. A method of bonding wood, textiles, metals, ceramic or plastics, the method comprising contacting wood, a textile, a metal, ceramic or a plastic with the sealant, coating or adhesive of claim 11.

14. A method of bonding foils, fibers, films, injection-molded products, or shaped films, or of 3D printing, the method comprising contacting a foil, a fiber, a film, an injection-molded product, or a shaped film with the sealant, coating or adhesive of claim 11, or comprising 3D printing the sealant, coating or adhesive.

15. A sealant, coating or adhesive, comprising a composition obtained or obtainable by the process of claim 7.

16. The sealant, coating or adhesive of claim 15, which is a hotmelt adhesive, an assembly adhesive for fixing of a component, a bookbinding adhesive, an adhesive for production of a composite film, a laminate, a sandwich component, or an edgebanding product.

17. A method of bonding wood, textiles, metals, ceramic or plastics, the method comprising contacting wood, a textile, a metal, ceramic or a plastic with the sealant, coating or adhesive of claim 15.

18. A method of bonding foils, fibers, films, injection-molded products, or shaped films, or of 3D printing, the method comprising contacting a foil, a fiber, a film, an injection-molded product, or a shaped film with the sealant, coating or adhesive of claim 15, or the method comprising 3D printing the sealant, coating or adhesive.

Description

EXAMPLES

[0150] 1. Compounds Used/Composition of the Polyurethanes

TABLE-US-00001 TABLE 1 Composition Name Concentration (% by wt.) Isocyanate 11.7 Polyol-A 20.1 Polyol-B 21.6 Polyol-C 24.9 Polyol-D 21.7 [0151] Isocyanate: mixture of diphenylmethane diisocyanate isomers (4,4: 98.6% by weight; 2,4: 1.4% by weight) [0152] Polyol-A: polypropylene glycol having an average molecular weight of 1970 g/mol and a functionality of 1.9 [0153] Polyol-B: polypropylene glycol having an average molecular weight of 4000 g/mol and a functionality of 2.0 [0154] Polyol-C: polyester polyol based on adipic acid and hexane-1,6-diol and having an average molecular weight of 3500 g/mol, acid number of max. 2 mg [0155] KOH/g, a functionality of 2.0 and a melting point peak maximum of 55 C. (measured via DSC). [0156] Polyol-D: polyacrylate copolymer on methyl methacrylate and butyl methacrylate having an average molecular weight of 34 000 g/mol, and a glass transition of 76 C. (measured via DSC) [0157] Solvenon DPM: dipropylene glycol monomethyl ether, CAS No. 34590-94-8, from BASF [0158] Nucleating agent-A: Cinquasia K4535, 2,9-dichloroquinacridone, ground, acid extraction, C.I. Pigment Red 202, specific surface area 72.4 m.sup.2/g [0159] Nucleating agent-B: Cinquasia K4410, solid solution of gamma-quinacridone and 2,9-dimethylquinacridone (ratio 1:3), C.I. Pigment Red 122, specific surface area 58.5 m.sup.2/g [0160] Nucleating agent-C: Irgazin Yellow K2060, isoindoline, Pigment yellow 110, specific surface area 26.7 m.sup.2/g [0161] Nucleating agent-D: Irgazin Yellow K2080, isoindoline, Pigment yellow 110, specific surface area 45.6 m2/g [0162] Nucleating agent-E: Paliogen Red Violet K5411, perylene, Pigment violet 29, specific surface area 78 m.sup.2/g [0163] Nucleating agent-F: Cromophtal Yellow L1061 HD, benzimidazolone (Pigment yellow 151), specific surface area 26.7 m.sup.2/g [0164] Nucleating agent-G: Paliogen Blue L6470, indanthrone pigment, specific surface area 52 m.sup.2/g [0165] Nucleating agent-H: Pigment Red 122 [0166] Reference-A: Finntalc MO5SL, talc with particle size features D98=9 microns, d50=2.2 microns and 44% particles below 2 microns [0167] Reference-B: Irgaclear DM, bis(p-methylbenzylidene)sorbitol, CAS Number: 81541-12-0 [0168] Reference-C: Irgastab NA287, zinc glycerolate, CAS Number: 16754-68-0 [0169] Reference-D: ADK Stab NA71, 2,2-methylenebis(2,4-di-tert-butylphenyl)phosphate lithium salt, CAS Number 85209-93-4 [0170] Reference-E: Millad NX8000, bis(4-propylbenzylidene)propylsorbitol, CAS Number 882073-43-0

[0171] 2. Production of the PUR Hotmelt [0172] Polyol-A, polyol-B, polyol-C and polyol-D were introduced into a reactor. The mixture was heated to 120 C. and a reduced pressure of 70 mbar was applied for a duration of 1.5 hours. Subsequently, the isocyanate was added and the mixture was stirred for a further 3 hours. Then Solvenon DPM was added to the reaction mixture. The molar ratio of Solvenon DPM to the remaining isocyanate groups was 1:1. The reaction was stopped and the material obtained was cooled. Inverse titration confirmed the absence of NCO groups.

[0173] 3. Compounding of the PUR Hotmelt with Nucleating Agent [0174] About 1 g of the PUR hotmelt obtained was admixed with the nucleating agent in a mortar. The concentration of the nucleating agent used is stated in table 2. Once the polyurethane had melted completely, the nucleating agent was dispersed homogeneously in the melt. When the mixture was visually homogeneous, it was cooled and stored.

[0175] 4. DSC Analysis [0176] About 10 mg of a polyurethane hotmelt and the mixture of polyurethane and nucleating agent were weighed into an aluminum boat. Under a nitrogen atmosphere, the sample was heated from room temperature to 120 C. After 3 minutes at 120 C., the sample was cooled to 80 C. Finally, the sample, after 3 minutes isothermal at 80 C., was heated back up to 120 C. The heating and cooling rate was 20 K/min. The crystallization peak in the cooling step was recorded.

TABLE-US-00002 TABLE 2 Concentration of the nucleating agent and crystallization (peak) temperature ID Nucleating agent Concentration (% by wt.) Tc ( C.) 1 0 12 2 Nucleating agent-A 0.3 32 3 Nucleating agent-B 0.3 32 4 Nucleating agent-C 0.3 30 5 Nucleating agent-D 0.3 31 6 Nucleating agent-E 0.3 30 7 Nucleating agent-F 0.3 30 8 Nucleating agent-G 0.3 33 9 Nucleating agent-H 0.3 32 10 Reference-A 3 29 11 Reference-B 0.3 25 12 Reference-C 0.3 25 13 Reference-D 0.3 19 14 Reference-E 0.3 11 [0177] The measurements show that, when the nucleating agents of the invention are used, a change in the crystallization temperature of at least 5 C. is achieved. When reference-A is used, an increase in the concentration used by a factor of 10 is needed to achieve the same change in the crystallization temperature.

[0178] 5. Measurement of Bond Strength with Use of the PUR Hotmelts [0179] Tensile shear strength was measured using plywood samples. Roughly 1 mm-thick films of the PUR hotmelt or of the mixture of PUR hotmelt with the nucleating agent were sandwiched between two sheets with an overlap of about 10 mm. The sheets were pressed at 100 C. for 10 min (1 kg). Subsequently, the samples were removed and tested after different times. The results are shown in table 3. The maximum force was determined using a spring balance.

TABLE-US-00003 TABLE 3 Maximum force/time of bond strength ID Nucleating agent Time (min:sec) Force (N) 1 3:30 35 1 5:00 50 2 Nucleating agent-A 3:30 58 2 Nucleating agent-A 5:00 70 10 Reference-A 3:30 50 10 Reference-A 5:00 60 [0180] The measurements show that, when the inventive nucleating agent (I D2) is used, the adhesive achieves a higher bond strength than without nucleating agent or using a nucleating agent according to the prior art (I D10).

[0181] 6. Efficacy of the Nucleating Agent in PUR Hotmelt [0182] In order to show the efficacy of the nucleating agent in the PUR hotmelt formulations, the concentration of the nucleating agent H in the formulation was varied. The experiment was conducted according to the general description for the DSC analysis. The results are summarized in table 4. The concentration relates to the amount of the nucleating agent based on the PUR hotmelt.

TABLE-US-00004 TABLE 4 Crystallization peak as a function of the concentration of the nucleating agent in the PUR hotmelt Concentration (% by wt.) Tc ( C.) 0.3 32 0.1 31 0.06 31 0.03 29

[0183] 7. Production of a Reactive PUR Hotmelt [0184] Polyol-A, polyol-B, polyol-C and polyol-D and the nucleating agent were introduced into a reactor. The mixture was heated to 120 C. and a reduced pressure of 70 mbar was applied for a duration of 1.5 hours. Subsequently, the isocyanate was added and the mixture was stirred for a further 3 hours. The composition of the mixture is shown in table 5. The reaction was stopped and the material obtained was cooled. No agglomeration was observed during the storage. The NCO content was determined by inverse titration.

TABLE-US-00005 TABLE 5 Composition of the reactive PUR hotmelts RHM-ID 1 RHM-ID2 RHM-Ref1 Concentration Concentration Concentration Name (% by wt.) (% by wt.) (% by wt.) Isocyanate 11.7 11.7 11.7 Polyol-A 20.1 20.1 20.1 Polyol-B 21.6 21.6 21.6 Polyol-C 24.9 24.9 24.9 Polyol-D 21.7 21.7 21.7 Nucleating 0.3 agent-A Reference-A 3.0 NCO content 1.9 1.9 1.9 (% by wt.)

[0185] 8. Measurement of Initial Adhesion of Reactive PUR Hotmelts [0186] Tensile shear strength was measured using plywood samples. Roughly 1 mm-thick films of the PUR hotmelt or of the mixture of reactive PUR hotmelt with the nucleating agent were sandwiched between two sheets with an overlap of about 10 mm. The sheets were pressed at 100C for 10 min (1 kg). Subsequently, the samples were removed and, after 15 minutes, tested with a Zwick/Roell testing machine at 25 mm/min and initial load 1 N. 3 samples were tested for each system. The sample without nucleating agent (RHM-ID-1) showed an average maximum force of 55 N, while samples with nucleating agent (RHM-1D2 and RHM-Ref1) showed an average maximum force of about 90 N. RHM-ID2 showed similar characteristics to sample RHM-Ref1 with just 1/10 of the concentration of the nucleating agent.

LITERATURE CITED

[0187] EP 0 199 021 A2 [0188] DE 38 27 224 A1 [0189] WO2005/066256 [0190] WO 2008/155018 A1 [0191] Lehrbuch der Lacke und Beschichtungen by Hans Kittel, volume 5 (5. Pigmente, Fllstoffe und Farbmetrik/volume ed. Jrgen Spille), chapter 5.4, 2003, ISBN 3-7776-1015-1 [0192] Kunststoffhandbuch, volume 7, Polyurethane, Carl Hanser Verlag, 3rd edition, 1993, chapter 3.1