DRYING AGENT FOR MOISTURE-CURING COMPOSITIONS

Abstract

The invention relates to a polymer composition that can be produced by (a) reacting an NCO-reactive polymer having at least two NCO-reactive groups, with a polyisocyanate, the molar ratio of polyisocyanate molecules to NCO-reactive groups of the NCO-reactive polymer being at least 1.25:1; and (b) reacting the reaction product from step a) with an NCO-reactive silane. The invention also relates to a moisture-reactive composition containing the polymer composition and to methods for producing the polymer composition and the moisture-reactive composition. Finally, the invention relates to the use of the polymer composition as a drying agent for moisture-curing adhesives, sealants and coating agents.

Claims

1. A polymer composition produced by: a) reacting an NCO-reactive polymer having at least two NCO-reactive groups per molecule with a polyisocyanate, a molar ratio of the polyisocyanate molecules to the NCO-reactive groups of the NCO-reactive polymer being at least 1.25:1; and subsequently b) reacting remaining NCO groups in a reaction product from step a) with an NCO-reactive silane.

2. The polymer composition as claimed in claim 1, wherein the molar ratio of the polyisocyanate molecules to the NCO-reactive groups of the NCO-reactive polymer in (a) is 1.25:1 to 10:1.

3. The polymer composition as claimed in claim 1, wherein the NCO-reactive polymer has a number-average molecular weight of 2000 to 100 000 g/mol.

4. The polymer composition as claimed in claim 1, wherein the NCO-reactive polymer is a polyol.

5. The polymer composition as claimed in claim 1, wherein the polyisocyanate comprises 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, hexamethylene 1,6-diisocyanate (HDI), 2-methyl-1,5-diisocyanatopentane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- and/or 2,4,4-trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3- and/or 1,4-diisocyanatocyclohexane, 1,4-diisocyanato-3,3,5-trimethylcyclohexane, 1,3-diisocyanato-2-methylcyclohexane, 1,3-diisocyanato-4-methylcyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 1-isocyanato-1-methyl-4(3)-isocyanatomethylcyclohexane, 2,4′- and/or 4,4′-diisocyanatodicyclohexylmethane, 1,3- and/or 1,4-bis(isocyanatomethyl)cyclohexane, bis(isocyanatomethyl)norbornane, 4,4′-diisocyanato-3,3′-dimethyldicyclohexylmethane, 4,4′-diisocyanato-3,3′,5,5′-tetramethyldicyclohexylmethane, 4,4′-diisocyanato-1,1′-bis(cyclohexyl), 4,4′-diisocyanato-3,3′-dimethyl-1,1′-bi(cyclohexyl), 4,4′-diisocyanato-2,2′,5,5′-tetramethyl-1,1′-bi(cyclohexyl), 1,8-diisocyanato-p-menthane, 1,3-diisocyanatoadamantane, 1,3-dimethyl-5,7-diisocyanatoadamantane, 1,3- and/or 1,4-bis(isocyanatomethyl)benzene, 1,3- and/or 1,4-bis(1-isocyanato-1-methylethyl)benzene, bis(4-(1-isocyanato-1-methylethyl)phenyl) carbonate, 2,4- and/or 2,6-diisocyanatotoluene, 2,4′- and/or 4,4′-diisocyanatodiphenylmethane, 1,5-diisocyanatonaphthalene, or a mixture thereof.

6. The polymer composition as claimed in claim 1, wherein the NCO-reactive silane is a compound of formula (I):
R.sup.1.sub.3Si(CH.sub.2).sub.nX   (I), wherein R.sup.1 each radical is in each case independently selected from C.sub.1-C.sub.8-alkyl, C.sub.6-C.sub.20-aryl, C.sub.1-C.sub.8-alkoxy, or C.sub.1-C.sub.8-acyloxy and at least one of the radicals R.sup.1 is a C.sub.1-C.sub.8-alkoxy or C.sub.1-C.sub.8-acyloxy radical, n is an integer from 1 to 4, X is selected from —OH, —SH, and —NHR.sup.2, R.sup.2 is selected from H, C.sub.1-C.sub.20-alkyl, —CH.sub.2CH.sub.2CN, and —CHR.sup.3CH.sub.2COOR.sup.4, R.sup.3 is selected from H and —COOR.sup.4, and R.sup.4 in each case is C.sub.1-C.sub.20-alkyl.

7. A process for producing the polymer composition as claimed in claim 1, comprising: a) reacting an NCO-reactive polymer having at least two NCO-reactive groups per molecule with a polyisocyanate, a molar ratio of the polyisocyanate molecules to the NCO-reactive groups of the NCO-reactive polymer being at least 1.25:1; and b) reacting a reaction product from step a) with an NCO-reactive silane.

8. A moisture-curing composition comprising a polymer composition as claimed in claim 1 and at least one additive comprising one or more fillers, one or more crosslinking catalysts, one or more adhesion promoters, one or more plasticizers, or a combination thereof.

9. The moisture-curing composition as claimed in claim 8, wherein the moisture-curing composition has a water content, determined according to DIN EN ISO 15512:2017-03, method B2, of up to 0.1% by weight, based on a total weight of the moisture-curing composition.

10. The moisture-curing composition as claimed in claim 8, containing no further drying agents.

11. The moisture-curing composition as claimed in claim 8, comprising less than 1% by weight of vinyl group-containing silanes, based on a total weight of the moisture-curing composition.

12. The moisture-curing composition as claimed in claim 8, comprising 5% to 50% by weight of the polymer composition as claimed in claim 1; 10% to 70% by weight of at least one filler; up to 5% by weight of at least one adhesion promoter; 0.001% to 5% by weight of at least one crosslinking catalyst; and up to 50% by weight of at least one plasticizer, based in each case on a total weight of the moisture-curing composition.

13. A process for producing the a moisture-curing composition, comprising mixing a polymer composition as claimed in claim 1 with at least one filler, at least one adhesion promoter, at least one crosslinking catalyst, at least one plasticizer, or a combination thereof.

14. The process as claimed in claim 13, wherein the polymer composition as claimed in claim 1 is mixed with at least one filler having a water content of up to 1% by weight, based on a total weight of the filler.

15. The process as claimed in claim 13, wherein at most 1% by weight of vinyl group-containing silanes are added to the moisture-curing composition.

16. A drying agent for moisture-curing adhesives, sealants, or coating materials, comprising the polymer composition as claimed in claim 1.

17. A parquet adhesive containing the polymer composition as claimed in claim 1.

Description

EXAMPLES

Production of Polymer Compositions

[0175] In a 21 sulfonation flask with lid, stirrer, thermometer and nitrogen flow, the amounts of a difunctional propylene glycol having an OH number of 13.4 mg KOH/g (determined according to DIN 53240-1 (2012)) (Acclaim® Polyol 8200 N from Covestro Deutschland AG; Leverkusen DE) indicated in table 1 under “Amount of NCO-reactive polymer” were reacted with the amounts of isophorone diisocyanate (IPDI, Desmodur® I, Covestro Deutschland AG, NCO content 37.8%, molar mass 222 g/mol) or tolylene diisocyanate (TDI, Desmodur® T80, Covestro Deutschland AG, molar mass 174 g/mol, NCO content 48.2%) indicated in table 1 under “Amount of polyisocyanate” at 60° C. with addition of the amounts of dibutyltin dilaurate indicated in table 1 under “Amount of catalyst” until complete reaction of the NCO-reactive groups of the NCO-reactive polymer (see reaction time, table 1). Optionally, the addition of catalyst is dispensed with and the reaction temperature is increased to 80° C. for this purpose (examples P4 and P5). After addition of the amounts of diethyl N-(3-trimethoxysilylpropyl)aspartate (prepared according to EP-A 0 596 360, example 5) indicated in table 1 under “Amount of NCO-reactive silane”, the mixture was stirred further until it was no longer possible to observe any isocyanate band in the IR spectrum.

[0176] The molar amount of NCO-reactive groups in the NCO-reactive polymer was calculated as follows: OH number in mg KOH/g of polymer determined according to DIN 53240-1 divided by 1000 (mg/g) and the molar mass of KOH (56.1 g/mol) multiplied by the mass of NCO-reactive polymer. Example P1: (13.4 mg/g)/(1000 mg/g)/(56.1 g/mol)*(1037.6 g)=0.248 mol.

[0177] The molar amount of the polyisocyanate was calculated as follows: Mass of polyisocyanate in g/mol divided by the molar mass of the polyisocyanate. Example P1: 82.6 g/222 g/mol=0.372 mol.

[0178] The ratio of the molar amounts of the polyisocyanate to the molar amount of NCO-reactive groups was calculated as follows: Molar amount of the polyisocyanate in moles divided by the molar amount of NCO-reactive groups in the NCO-reactive polymer. Example P1: 0.372 mol/0.248 mol=1.5.

[0179] The viscosity of the polymer compositions obtained was determined according to the method in DIN EN ISO 3219/B3 using a Physica MCR 51 rheometer from Anton Paar Germany GmbH (D).

TABLE-US-00001 TABLE 1 P3 P5 Polymer composition P1 P2 CE P4 CE Amount of NCO-reactive polymer [g] 1037.6 880.1 880.1 880.1 880.1 Molar amount of NCO-reactive polymer [mol] 0.124 0.105 0.105 0.105 0.105 Molar amount of NCO-reactive groups in the 0.248 0.210 0.210 0.210 0.210 NCO-reactive polymer [mol] Polyisocyanate IPDI IPDI IPDI TDI TDI Amount of polyisocyanate [g] 82.6 116.8 46.7 91.4 36.6 Molar amount of polyisocyanate [mol] 0.372 0.526 0.210 0.526 0.210 Ratio of polyisocyanate to molar amount of NCO- 1.5 2.5 1.0 2.5 1.0 reactive groups in the NCO-reactive polymer Catalyst, amount [g] 0.04 0.04 0.04 — — Reaction time [h] 5 5 5 5 32 Reaction temperature [° C.] 60 60 60 80 80 Amount of NCO-reactive silane [g] 177.1 300.5 74.81 300.5 74.81 Viscosity [Pa .Math. s] 26 21 45 22 30 CE: Comparative example

[0180] As comparative example P3 shows, the polymer composition produced using a low ratio of polyisocyanate to NCO-reactive groups exhibits a higher viscosity than the polymer compositions P1 and P2 according to the invention. The same applies to the comparative composition P5 compared to composition P4 according to the invention. In addition, comparative composition P5 shows that it is not possible to dispense with the catalyst in the case of a low ratio of polyisocyanate to NCO-reactive groups because without the use of a catalyst the reaction time until complete reaction of the NCO-reactive groups of the NCO-reactive polymer is significantly longer. In contrast, in the case of a high ratio of polyisocyanate to NCO-reactive groups, the NCO-reactive groups of the NCO-reactive polymer are reacted in a relatively short time even without addition of a catalyst.

Production of Polymer Composition P6 (Comparative Example)

[0181] Further isophorone diisocyanate (IPDI, Desmodur I, Covestro Deutschland AG, NCO content 37.8%, molar mass 222 g/mol) was added to the polymer composition P3 described above and reacted with diethyl N-(3-trimethoxysilylpropyl)aspartate in accordance with the teaching of DE 10 2005 026 085 A1 to afford a urea derivative. The amounts of IPDI and diethyl N-(3-trimethoxysilylpropyl)aspartate used were selected here such that the relative amounts of the raw materials used, including the raw materials used for the production of the polymer composition P3, corresponded exactly to those of polymer composition P2 according to the invention. In particular, the ratio of IPDI to NCO-reactive groups in the polyol therefore corresponded to that of polymer composition P2 according to the invention. The polymer composition thus obtained had a high viscosity of 45 Pa.Math.s. This example shows that the polymer composition according to the invention has a lower viscosity than a composition produced in accordance with the teaching of DE 10 2005 026 085 A1 from the same starting materials.

Production of Moisture-Curing Compositions Without Addition of Vinylsilanes

Example MC-1 (According to the Invention)

[0182] A moisture-curing composition based on polymer composition P1 was produced according to the following procedure: 578.8 g of Omyalite® 95 T (calcium carbonate, from Omya) filler, dried beforehand for 16 hours at 100° C. in an air circulation drying cabinet to a water content of 0.08% by weight, are dispersed with 136.2 g of plasticizer (Mesamoll®, from Lanxess, water content 0.03% by weight), 275.5 g of polymer composition P1 (table 3), 8.4 g of Cab-O-Sil® TS 720 (hydrophobic fumed silica, from Cabot, water content 0.11% by weight) and 3 g of 1,8-diazabicyclo[5.4.0]undec-7-ene (Sigma-Aldrich Co. LLC) in a laboratory dissolver with a butterfly stirrer (200 revolutions/min) and a dissolver disk (2500 revolutions/min) for 15 min under a static vacuum and with cooling. Static vacuum is to be understood here as meaning that the apparatus is evacuated down to a pressure of 200 mbar (dynamic vacuum) and the connection to the vacuum pump is then severed. Cooling was chosen such that during the entirety of production a temperature of 65° C. was not exceeded.

Example MC-2 (Comparative Example)

[0183] Analogously to MC-1, a moisture-curing composition was produced, with the difference that now polymer composition P3 was used instead of polymer composition P1.

Example MC-3 (Comparative Example)

[0184] Composition MC-3 was produced analogously to MC-2, with vinyltrimethoxysilane as drying agent (Dynasilan® VTMO, Evonik) and an adhesion promoter (Dynasilan® 1146, Evonik) additionally being added.

[0185] Compositions MC-1 to MC-3 were examined as described hereinbelow for their storage stability (viscosity rise) and reactivity (skin forming time). The results are shown in the following table.

Determination of Viscosity, Shore Hardness, Elongation at Break and Tensile Strength

[0186] After 7 days of storage in a cartridge the moisture-curing compositions were applied to a polyethylene film using a doctor blade to afford membranes having a uniform layer thickness of 2 mm and cured for 14 days at 23° C. and 50% atmospheric humidity, wherein after 7 days the membranes were detached from the film and turned over. The properties of these membranes were subsequently determined by the following methods.

[0187] Viscosity was determined after seven or 60 days of storage and was carried out according to the method in DIN DIN EN ISO 3219/B3 at a shear rate of 40/s.

[0188] Testing of Shore A hardness was carried out on the membranes according to the method in DIN ISO 7619-1. To determine Shore A hardness, three membranes were placed on top of one another to ensure a layer thickness of 6 mm.

[0189] Elongation at break and tensile strength were determined by means of a tensile test according to the method in DIN 53 504 on S2 dumbbells stamped from the membranes produced as described above using a shaped punch. The test speed was 200 mm/min.

Determination of the Skin Forming Time

[0190] Using a doctor blade (200 μm) a film of the adhesive was applied to a glass plate previously cleaned with ethyl acetate and was immediately placed in a drying recorder (BK 3 drying recorder, BYK-Gardner). The needle was loaded with 10 g and moved over a distance of 35 cm over a period of 24 hours. The drying recorder was situated in a climate-controlled room at 23° C. and 50% relative atmospheric humidity. The time of disappearance of the permanent trace of the needle from the film was specified as the skin forming time.

Determination of the Water Content

[0191] The water content was determined according to DIN EN ISO 15512:2017-03, method B2.

Determination of the Tensile Shear Strength

[0192] The tensile shear strength was determined according to DIN EN 14293, storage sequence b).

TABLE-US-00002 TABLE 2 MC-2 MC-3 Moisture-curing composition MC-1 CE CE Polymer composition P1 P3 P3 Amount of polymer composition [g] 275.5 275.5 275.5 MESAMOLL [g] 136.2 136.2 136.2 CAB-O-SIL TS 720 [g] 8.4 8.4 8.4 OMYALITE 95T [g] 578.8 578.8 578.8 DBU [g] 3.0 3.0 0.3 Dynasilan VTMO [g] — — 25.0 Dynasilan 1146 [g] — — 15.0 State immediately after production Paste- Paste- Paste- like like like Viscosity after 7 d storage at 23° C. 56 gelled 35 [Pa .Math. s] Viscosity after 60 d storage at 71 gelled 50 23° C. [Pa .Math. s] Skin forming time after 7 d 0.5 gelled 1 storage at 23° C. [h] Skin forming time after 30 d 0.5 gelled 1 storage at 23° C. [h] Water content according to <100 n.d. <100 formulation (DIN EN ISO ppm ppm 15512:2017-03, method B2) Adhesion to glass, bead test Cohesive n.d. Cohesive failure failure Adhesion to glass, bead test after Cohesive n.d. Cohesive immersion in water failure failure Tensile strength [N/mm.sup.2] 2.7 n.d. 2.7 Elongation at break [%] 170 n.d. 170 Shore A hardness 60 n.d. 61 CE: Comparative example

[0193] The results show that use of the polymer composition P1 according to the invention, even without addition of drying agent and silane adhesion promoter, affords a storage-stable formulation the reactivity and properties of which in the fully reacted state are comparable with a comparative composition obtained using polymer composition P3 with addition of drying agent and adhesion promoter. In contrast, the use of polymer composition P3 while dispensing with a drying agent and an adhesion promoter results in a composition which is not storage-stable.