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 exactly one NCO-reactive group per molecule, with a diisocyanate, the molar ratio of the diisocyanate molecule to the NCO-reactive groups of the NCO-reactive polymer being at least 2:1; and (b) reacting the residual NCO groups in the reaction product from step a) with an NCO-reactive silane. The invention also relates to a moisture-reactive composition containing said polymer composition, to methods for producing the polymer composition, and to moisture-reactive compositions containing said polymer 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 a molecular weight Mn of between 2000 and 25 000 g/mol and having exactly one NCO-reactive group per molecule with a diisocyanate, a molar ratio of the diisocyanate molecules to the NCO-reactive groups of the NCO-reactive polymer being at least 2:1; and subsequently b) reacting the remaining NCO groups in the reaction product from step a) with an NCO-reactive silane.

2. The polymer composition as claimed in claim 1, wherein the molar ratio of diisocyanate to NCO-reactive groups of the NCO-reactive polymer in step a) is 2:1 to 20:1.

3. The polymer composition as claimed in claim 1, wherein the NCO-reactive polymer has a number-average molecular weight of 4000 to 20 000 g/mol.

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

5. The polymer composition as claimed in claim 1, wherein the diisocyanate comprises 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, hexamethylene 1,6-diisocyanate, 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′-bi(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), where 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 the steps of: a) reacting an NCO-reactive polymer having at least two NCO-reactive groups with a diisocyanate, a molar ratio of diisocyanate to NCO-reactive groups of the NCO-reactive polymer being at least 1.25; 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 the 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 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

[0146] For the production of the polymer compositions according to the invention, the following diethylene glycol monobutyl ether-started polyoxypropylene polymers having in each case one hydroxyl group per molecule, produced analogously to the method in EP 0 654 302 A1 were used.

TABLE-US-00001 Monool I OH number: 55.1 mg KOH/g (determined according to DIN 53240—1 (2012), corresponding to a molar mass of 1018 g/mol) Viscosity at 25° C.: 80 mPas Water content: 100 ppm Monool II OH number: 12.7 mg KOH/g (determined according to DIN 53240—1 (2012), corresponding to a molar mass of 4417 g/mol) Viscosity at 25° C: 814 mPas Water content: 100 ppm Monool III OH number: 2.9 mg KOH/g (determined according to DIN 53240—1 (2012), corresponding to a molar mass of 19 345 g/mol) Viscosity at 25° C: 36 100 mPas Water content: 200 ppm

Preparation of Aspartic Ester AE1

[0147] A diethyl N-(3-trimethoxysilylpropyl)aspartate was prepared according to EP-A 0 596 360, example 5.

Production of a Silane-Functional Polymer SP

[0148] In a 21 sulfonation flask with lid, stirrer, thermometer and nitrogen flow, 880.1 g of a 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 D E) were reacted with 46.7 g of isophorone diisocyanate (IPDI, Desmodur® I, Covestro Deutschland AG, NCO content 37.8%, molar mass 222 g/mol) after addition of 0.04 g of dibutyltin dilaurate at 60° C. until the theoretical isocyanate content was reached. 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.

Production of the Polymer Compositions Pl-P3 According to the Invention

[0149] In a 21 sulfonation flask with lid, stirrer, thermometer and nitrogen flow, the amounts of the polyoxypropylene polymers indicated in table 1 under “Monool I-III” were reacted with the amount of hexamethylene diisocyanate (HDI, Desmodur® H, Covestro Deutschland AG, NCO content 50%, molar mass 168 g/mol) indicated in table 1 under “Hexamethylene diisocyanate” at 60° C. with addition of the amount of dibutyltin dilaurate indicated in table 1 under “Dibutyltin dilaurate” until complete reaction of the NCO-reactive groups of the NCO-reactive polymer (here hydroxyl groups of the polyoxypropylene polymer). After addition of the amounts of diethyl N-(3-trimethoxysilylpropyl)aspartate indicated in table 1 under “Aspartic ester AE1”, the mixture was stirred further until it was no longer possible to observe any isocyanate band in the IR spectrum. The viscosity of the polymer compositions obtained was determined 24 h after production of the polymer compositions according to the method in DIN EN ISO 3219/B3 using a Physica MCR 51 rheometer from Anton Paar Germany GmbH (D).

TABLE-US-00002 TABLE 1 Polymer composition P1 P2 P3 Monool I 509.0g Monool II 421.4g Monool III 831.9 g Hexamethylene diisocyanate 168.0 g 112.2 g 36.1 g Aspartic ester AE1 527.2 g 466.1 g 136.0 g Dibutyltin dilaurate 0.06 g 0.05 g 0.05 g Eq NCO groups 2 1.33 0.43 Eq OH groups 0.5 0.095 0.043 Index 4 14 10 Eq Silane 1.5 1.23 0.387 Viscosity [Pas], 24 h after production 1.6 3.0 56

Example MC-2

Production of Moisture-Curing Compositions Without Addition of Vinylsilanes

[0150] The polymer compositions P1-P3 are admixed with the amount of water indicated in the table, the mixture is homogenized for 10 minutes in a Speedmixer and the viscosity is determined at 23° C. after storage for 24 h in a closed vessel.

TABLE-US-00003 TABLE 2 Molar ratio Viscosity Amount of P1 [g] Amount of water [g] Water/—SiOR.sub.3 after 24 h at 23° C. 50 1.68 1:1.3 1.3 50 1.26 1:1 1.2 50 0.84 1:0.66 1.2 50 0.42 1:0.33 1.2 Molar ratio Viscosity Amount of P2 [g] Amount of water [g] Water/—SiOR.sub.3 after 24 h at 23° C. 50 1.8 1:1.3 2.6 50 1.35 1:1 2.5 50 0.9 1:0.66 2.5 50 0.45 1:0.33 2.4 Molar ratio Viscosity Amount of P3 [g] Amount of water [g] Water/—SiOR.sub.3 after 24 h at 23° C. 50 0.52 1:1.3 viscous 50 0.39 1:1 viscous 50 0.26 1:0.66 64 50 0.13 1:0.33 45

[0151] It is apparent (see table 2) that the polymer compositions P1-P3 react with stoichiometric and substoichiometric amounts of water and hence remain liquid to viscous. The viscosity-increasing effect of the increase in the molar mass is in this case at least partly compensated by the viscosity-lowering effect of the release of methanol. The polymer compositions P1-P3 thus clearly functioned as desiccants.

Example MC-1 (According to the Invention, Without VTMO Desiccant)

[0152] A moisture-curing compositions based on polymer compositions P2 was produced according to the following procedure: 516.16 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 132.2 g of plasticizer (Mesamoll®, from Lanxess, water content 0.03% by weight), 267.21 g of silane-functional polymer SP and also 56.2 g of polymer composition P2, 8.1 g of Cab-O-Sil® TS 720 (hydrophobic fumed silica, from Cabot, water content 0.11% by weight) and 2.9 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. is not exceeded. Then, 1.0 g of aminopropyltrimethoxysilane (Dynasilan® AMMO, Evonik) are added and the mixture is homogenized for 5 min under static vacuum with a butterfly stirrer (200 revolutions/min).

Example MC-2 (Comparison, MC-2, But Without Addition of the Polymer Compositions P2 According to the Invention, Without VTMO Desiccant)

[0153] A moisture-curing compositions based on silane-functional polymer SP 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 silane-functional polymer SP, 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. is not exceeded. Then, 1.0 g of aminopropyltrimethoxysilane (Dynasilan® AMMO, Evonik) are added and the mixture is homogenized for 5 min under static vacuum with a butterfly stirrer (200 revolutions/min).

Example MC-3 (Comparison, MC-1, But Without Addition of the Polymer Compositions P2 According to the Invention, With Addition of VTMO Desiccant and Aminosilane)

[0154] A moisture-curing compositions based on silane-functional polymer SP 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 silane-functional polymer SP, 8.4 g of Cab-O-Sil® TS 720 (hydrophobic fumed silica, from Cabot, water content 0.11% by weight) and 1.2 g of 1,8-diazabicyclo[5.4.0]undec-7-ene, and also 25.0 g of vinyltrimethoxysilane (Dynasilan® VTMO, Evonik) (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. is not exceeded. Then, 15.0 g of an oligomeric aminosilane (Dynasilan® 1146, Evonik) are added and the mixture is homogenized for 5 min under static vacuum with the butterfly stirrer (200 revolutions/min).

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

[0155] 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.

[0156] 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, unless indicated otherwise.

[0157] 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.

[0158] 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

[0159] Using a doctor blade (200 μm) a film of the adhesive is applied to a glass plate previously cleaned with ethyl acetate and is 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

[0160] The water content was determined according to DIN EN ISO 15512:2017-03, method B2.

Determination of the Tensile Shear Strength

[0161] The tensile shear strength was determined according to DIN EN 14293, storage sequence b).

TABLE-US-00004 TABLE 3 MC—2 MC—3 Moisture—curing composition MC—1 CE CE Silane—functional polymer SP [g] 267.2 275.5 275.5 MESAMOLL® [g] 132.2 136.2 136.2 CAB—O—SIL® TS 720 [g] 8.1 8.4 8.4 OMYALITE® 95T [g] 516.6 578.8 578.8 DBU [g] 3.0 3.0 1.2 Dynasilan® VTMO [g] — — 25.0 Polymer composition P1 [g] 56.0 — — Polymer composition P2 [g] — — — Dynasilan® 1146 [g] — — 15.0 Dynasilan® AMMO [g] 1.0 1.0 State immediately after production Paste—like Paste—like Paste—like State 1 d after production Paste—like gelled Paste—like State 7 d after production Paste—like gelled Paste—like Skin forming time after 7 d of storage at 23® C. [min] 10 gelled 60 Skin forming time after 30 d of storage at 23® C. [min] 10 gelled 60 Tensile strength [N/mm.sup.2] 1.8 n.d. 2.7 Elongation at break [%] 154 n.d. 170 Shore A hardness 57 n.d. 61 Tensile shear strength according to DIN EN 14293 1.7 n.d. 2.5 [N/mm.sup.2] CE: Comparative example?

[0162] The results show that use of the polymer composition P2 according to the invention, even without addition of drying agent and silane adhesion promoter, affords a storage-stable moisture-curing compositions MC-1 the properties of which in the fully reacted state are comparable with a comparative composition MC-3 obtained using drying agent and adhesion promoter. In contrast, dispensing with a drying agent and an adhesion promoter results in a moisture-curing composition MC-2 which is not storage-stable. The tensile shear strength according to DIN EN 14293 obtained with MC-1 is far above the profile of requirements for soft parquet adhesives in the DIN EN 14293 standard.