Flame-retardant adhesive and sealant with improved mechanical properties

Abstract

A moisture-curable composition having flame retardant properties and to the use thereof as an adhesive, sealant or coating. The composition according to the invention contains at least one moisture-reactive polymer in a proportion of 10% to 50% by weight, at least one precipitated, surface-coated aluminum trihydrate in a proportion of 30% to 60% by weight and in preferred embodiments up to 25% by weight of at least one phosphorus-containing compound and up to 20% by weight of at least one carbon additive. The inventive moisture-curable composition has excellent flame retardant properties and after curing remains resistant for a long time at high heat levels.

Claims

1. A moisture-curable sealant or adhesive composition comprising: a) a moisture-reactive polymer component in a proportion of 10% to 50% by weight based on a total weight of the composition, the moisture-reactive polymer component consisting of at least one organic polymer STP containing silane groups, wherein a polymer backbone of the at least one organic polymer STP containing silane groups is a polyether, b) at least one precipitated, surface-coated aluminum trihydrate ATH in a proportion of 30% to 60% by weight based on the total weight of the composition, c) between 5% and 20% by weight based on the total weight of the composition of at least one phosphorus-containing compound PH comprising a mixture of a liquid alkyl phosphate and ammonium polyphosphate, and d) at least one carbon additive KO that comprises expandable graphite in an amount between 1% to 15% by weight based on the total weight of the composition, wherein: within a temperature range of from 5° C. to 35° C., the moisture curable composition can be applied to a substrate and is curable, and the at least one precipitated, surface-coated aluminum trihydrate ATH provides a synergistic effect that leads to higher tensile strength, higher elongation, and higher tensile shear strength compared to compositions using standard ATH when used together with the moisture-reactive polymer component.

2. The moisture-curable sealant or adhesive composition according to claim 1, wherein the at least one precipitated, surface-coated aluminum trihydrate ATH comprises a surface coating of vinyl silanes or fatty acids.

3. The moisture-curable sealant or adhesive composition according to claim 1, wherein the composition additionally comprises a latent curing agent.

4. The moisture-curable sealant or adhesive composition according to claim 3, wherein the at least one carbon additive KO further comprises at least one dried carbon black in a proportion between 1% and 15% by weight, based on the total weight of the composition.

5. The moisture-curable sealant or adhesive composition according to claim 4, wherein: the at least one dried carbon black is present in an amount in a range of from 4% to 11% by weight and the at least one phosphorus-containing compound PH is present in an amount in a range of from 7% to 15% by weight based on the total weight of the composition, and the composition is configured to achieve at least hazard level class HL2 according to DIN EN 45545-2 after curing.

6. The moisture-curable sealant or adhesive composition according to claim 1, wherein the at least one organic polymer STP containing silane groups has end groups of formula (II) ##STR00003## where: R.sup.14 is a linear or branched, monovalent hydrocarbyl radical having 1 to 5 carbon atoms; R.sup.15 is a linear or branched, monovalent hydrocarbyl radical having 1 to 8 carbon atoms; x has a value of 0 or 1 or 2; R.sup.16 is a linear or branched divalent hydrocarbyl radical having 1 to 12 carbon atoms which may have cyclic and/or aromatic moieties and optionally one or more heteroatoms; T is a divalent radical selected from —O—, —S—, —N(R.sup.17)—, —O—CO—N(R.sup.17)—, —N(R.sup.17)—CO—O— and —N(R.sup.17)—CO—N(R.sup.17)—, and R.sup.17 is a hydrogen radical or a linear or branched hydrocarbyl radical having 1 to 20 carbon atoms which may have cyclic moieties and which may have an alkoxysilane, ether or carboxylic ester group.

7. The moisture-curable sealant or adhesive composition according to claim 1, wherein: the expandable graphite is present in an amount in a range of from 3% to 10% by weight and the at least one phosphorus-containing compound PH is present in an amount in a range of from 10% to 20% by weight based on the total weight of the composition, and the composition is configured to achieve fire retardancy class B (s2, d0) according to DIN EN 13501-1 after curing.

8. An adhesive, sealant or coating comprising the moisture-curable sealant or adhesive composition according to claim 1.

9. A built structure or article of manufacture that has been bonded, sealed or coated with the adhesive, sealant or a coating according to claim 8.

10. A cured composition of the moisture-curable sealant or adhesive composition according to claim 1, cured within a temperature range of from 5° C. to 35° C.

11. The moisture-curable sealant or adhesive composition according to claim 1, wherein the expandable graphite is present as the carbon additive KO in an amount in a range of from 3% to 10% by weight and the at least one phosphorus-containing compound PH is present in an amount in a range of from 10% to 20% by weight based on the total weight of the composition.

Description

EXAMPLES

(1) Recited hereinbelow are working examples intended to more particularly elucidate the invention described. It will be appreciated that the invention is not restricted to these described working examples.

(2) “Standard climatic conditions” refer to a temperature of 23±1° C. and a relative air humidity of 50±5%.

(3) Shore A hardness was determined according to DIN 53505, measured after 7 of 14 days at standard climatic conditions (“NK”; 23° C., 50% relative humidity) using disk-shaped test specimens having a diameter (circular) of 42 mm and a thickness (height) of 6 mm. In some experiments the measurement was repeated after storage in an oven at a particular temperature. The data for temperature and residence time in the oven are reported in the respective tables.

(4) The skin time (HBZ) was determined by applying a few grams of the composition to cardboard in a film thickness of about 2 mm and measuring under standard climatic conditions the time until, upon gentle tapping of the surface of the composition using an LDPE pipette, no residue remained on the pipette for the first time.

(5) The mechanical properties of tensile strength, elongation at break and modulus of elasticity (at 0-5% elongation) were measured in accordance with DIN EN 53504 at an extension rate of 200 mm/min.

(6) The tensile shear strength was determined based on ISO 4587/DIN EN 1465 on a Zwick/Roell Z005 tensile tester, wherein in each case two identical substrates were bonded to one another (bonding area: 12×25 mm; film thickness: 4.0 mm; measuring rate: 20 mm/min; substrate: float glass, PVC and aluminum; temperature: 23° C. (unless otherwise stated)).

(7) The tear propagation resistance was determined according to DIN 53515 using films cured for 14 days at 23° C. and 50% relative humidity having a film thickness of 2 mm.

(8) Production of Polymers P

(9) Isocyanate-Comprising Polyurethane Polymer PU-1

(10) 500 g of polyoxypropylene diol (Acclaim® 4200 N, Covestro; OH number 28.1 mg KOH/g), 2000 g of polyoxypropylene polyoxyethylene triol (Caradol® MD34-02, Shell; OH number 35.0 mg KOH/g) and 245 g of tolylene diisocyanate (TDI; Desmodur® T 80 P, Covestro) were reacted at 80° C. to afford an NCO-terminated polyurethane polymer having a content of free isocyanate groups as determined by titrimetry of 1.88% by weight. The isocyanate-comprising polymer was cooled to room temperature and stored under exclusion of moisture.

(11) Silane-Functional Polymer STP-1

(12) Under exclusion of moisture 1000 g of Acclaim® 12200 polyol (from Covestro; low monol polyoxypropylenediol, OH number 11.0 mg KOH/g, water content around 0.02% by weight), 35.2 g of isophorone diisocyanate (Vestanat® IPDI from Evonik Industries), 122.5 g of diisononyl 1,2-cyclohexanedicarboxylate (Hexamoll® DINCH® from BASF) and 0.12 g of dibutyltin dilaurate were heated to 90° C. with continuous stirring and maintained at this temperature until the content of free isocyanate groups as determined by titrimetry had reached a value of 0.39% by weight. Subsequently, 36.9 g of diethyl N-(3-trimethoxysilylpropyl)aminosuccinate (adduct of 3-aminopropyltrimethoxysilane and diethyl maleate; produced as per U.S. Pat. No. 5,364,955) were mixed in and the mixture was stirred at 90° C. until it was no longer possible to detect any free isocyanate by FT-IR spectroscopy. The silane-functional polymer was cooled to room temperature and stored under exculsion of moisture.

(13) Silane-Functional Polymer STP-2

(14) Under exclusion of moisture 1000 g of Acclaim® 12200 polyol (from Covestro; low monol polyoxypropylenediol, OH number 11.0 mg KOH/g, water content around 0.02% by weight), 43.6 g of isophorone diisocyanate (Vestanat® IPDI from Evonik Industries), 126.4 g of triethylene glycol bis(2-ethylhexanoate) (Solusolv® 2075 from Eastman Chem.) and 0.12 g of dibutyltin dilaurate were heated to 90° C. with continuous stirring and maintained at this temperature until the content of free isocyanate groups as determined by titrimetry had reached a value of 0.63% by weight. Subsequently, 62.3 g of diethyl N-(3-trimethoxysilylpropyl)aminosuccinate (adduct of 3-aminopropyltrimethoxysilane and diethyl maleate; produced as per U.S. Pat. No. 5,364,955) were mixed in and the mixture was stirred at 90° C. until it was no longer possible to detect any free isocyanate by FT-IR spectroscopy. The silane-functional polymer was cooled to room temperature and stored under exclusion of moisture.

(15) Production of Latent Curing Agents

(16) Aldimine 1

(17) (N,N′-bis(2,2-dimethyl-3-lauroyloxypropylidene)-3-aminomethyl-3,5,5-trimethylcyclohexylamine)

(18) 50.00 g of 2,2-dimethyl-3-lauroyloxypropanal were initially charged in a round-bottomed flask under a nitrogen atmosphere. With stirring, 13.93 g of 3-aminomethyl-3,5,5-trimethylcyclohexylamine were added and then the volatile constituents were removed at 80° C. and a vacuum of 10 mbar.

(19) A pale yellow liquid having an amine value of 153.0 mg KOH/g was obtained.

(20) Production of Moisture-Curable Compositions

(21) In tables 2 to 4 comparative examples are labelled “(Ref.)”. The raw materials employed are described in table 1.

(22) Raw Materials Employed

(23) TABLE-US-00001 TABLE 1 Employed raw materials in example formulations Raw material Producer/description Disflamoll TOF tris(2-ethylhexyl) phosphate (Disflamoll ® TOF; Lanxess) Chalk 1 (dried) Ground calcium carbonate (Omyacarb ® 5-GU; Omya) Carbon black Carbon black (Monarch ® 570; Cabot) (dried) ATH 1 (dried) Ground, uncoated ATH (Micral ® AM500, Huber) ATH 2 (dried) Precipitated, vinylsilane-coated ATH (Martinal ® OL 104 ZO, Martinswerk) ATH 3 (dried) Ground, uncoated ATH (SB 632, Huber) ATH 4 (dried) Ground, uncoated ATH (MoldX ® P18; Huber) ATH 5 (dried) Precipitated, uncoated ATH (Martinal ® OL 104 LEO, Martinswerk) ATH 6 (dried) Precipitated, fatty-acid-coated ATH (Martinal ® OL 104 C, Martinswerk) ATH 7 (dried) Ground, uncoated ATH (MoldX ® P18; Huber) ATH 8 (dried) Precipitated, uncoated ATH (Hymod ® M6400, Huber) Titanium dioxide Kronos ® 2500; Kronos Phosphate Ammonium polyphosphate (JLS-APP; JLS) Expandable Nyagraph ® 250; Nyacol Nano Technologies graphite Rheology Thixatrol ® ST; Elementis additive Catalyst 1 4% by weight dibutyltin dilaurate in Hexamoll DINCH Catalyst 2 5% by weight salicylic acid in Disflamoll TOF Drying agent Vinyltrimethoxysilane (Silquest ® A-171; Momentive) Adhesion N-(2-aminoethyl)-3-aminopropyltrimethoxysilane promoter (Silquest ® A-1110; Momentive)
Production of Polyurethane Compositions Z-1 to Z-5

(24) In a vacuum mixer in each case the polyurethane polymer PU-1 together with the plasticizer and the Aldimine-1 were initially charged under nitrogen and the filler (chalk, carbon black and/or ATH) was added and mixed in. Subsequently the catalyst was added and mixed in under vacuum at 1000-1200 rpm over 20 min to obtain a homogeneous paste. This was then filled into airtight cartridges and used later to produce the test specimens. The precise quantities (in % by weight based on the total composition in each case) of the individual raw materials for the respective experiments are shown in table 2.

(25) TABLE-US-00002 TABLE 2 Compositions Z-1 to Z-5 in % by weight in each case based on the total composition. Z-2 Z-5 Z-1 (Ref.) Z-3 Z-4 (Ref.) Polymer PU-1 25 25 25 25 25 Disflamoll TOF 12 12 12 12 12 Aldimine-1 2 2 2 2 2 Chalk 1 (dried) 60 Carbon black (dried) 5 10 ATH 1 (dried) 60 ATH 2 (dried) 60 55 50 Catalyst 1 0.5 0.5 0.5 0.5 0.5 Catalyst 2 0.5 0.5 0.5 0.5 0.5 TOTAL 100 100 100 100 100
Production of STP Compositions Z-6 to Z-17

(26) In a vacuum mixer the silane-functional polymer STP-1 or STP-2, plasticizer and drying agent were thoroughly mixed in the weight fractions reported in tables 3 to 5 over 5 minutes. Subsequently the respective filler (and the raw materials titanium dioxide, rheology additive, expandable graphite and phosphate not used in all formulations) was incorporated by kneading at 60° C. over 15 minutes. With the heating means switched off, adhesion promoter and catalyst were then added and the mixture was processed into a homogeneous paste under vacuum over 10 minutes. Said paste was then filled into internally coated aluminum applicator gun cartridges and, after storage, further used for the test specimens. The precise quantities (in % by weight based on the total composition in each case) of the individual raw materials for the respective experiments are shown in tables 3 to 5.

(27) TABLE-US-00003 TABLE 3 Compositions Z-6 to Z-9 in % by weight in each case based on the total composition. Z-9 Z-6 Z-7 Z-8 (Ref.) Polymer STP-2 25 25 25 25 Disflamoll TOF 11.5 11.5 11.5 11.5 Drying agent 1.5 1.5 1.5 1.5 Carbon black (dried) 5 10 ATH 3 (dried) 60 ATH 2 (dried) 60 55 50 Adhesion promoter 1 1 1 1 Catalyst 1 1 1 1 1 TOTAL 100 100 100 100

(28) TABLE-US-00004 TABLE 4 Compositions Z-10 to Z-13 in % by weight in each case based on the total composition. Z-10 Z-11 (Ref.) (Ref.) Z-12 Z-13 Polymer STP-1 24 24 24 24 Disflamoll TOF 15 15 15 15 Drying agent 2 2 2 2 Titanium dioxide 2 2 2 2 Rheology additive 3 3 3 3 ATH 4 (dried) 51.7 ATH 5 (dried) 51.7 ATH 6 (dried) 51.7 ATH 2 (dried) 51.7 Adhesion promoter 1 1 1 1 Catalyst 1 1.3 1.3 1.3 1.3 TOTAL 100 100 100 100

(29) TABLE-US-00005 TABLE 5 Compositions Z-14 to Z-19 in % by weight in each case based on the total composition. Z-15 Z-16 Z-14 (Ref.) (Ref.) (Ref.) Z-17 Z-18 Z-19 Polymer STP-2 24 24 24 20 20 20 Disflamoll TOF 15 15 15 16.5 16.5 16.5 Drying agent 2 2 2 2 2 2 Titanium dioxide 2 2 2 2 2 2 Rheology additive 3 3 3 Phosphate 8 8 10 Expandable graphite 4 6 4 ATH 7 (dried) 51.7 ATH 4 (dried) 51.7 ATH 8 (dried) 51.7 ATH 2 (dried) 45 43 43 Adhesion promoter 1 1 1 1 1 1 Catalyst 1 1.3 1.3 1.3 1.5 1.5 1.5 TOTAL 100 100 100 100 100 100
Measured Results

(30) The measured results as per the above-described methods are shown in tables 6 to 9.

(31) TABLE-US-00006 TABLE 6 Test results for compositions Z-1 to Z-5. A Shore A hardness value of 0 means the sample was destroyed by the heat. Z-2 Z-5 Z-1 (Ref.) Z-3 Z-4 (Ref.) Tensile strength [MPa] 2.4 0.8 3.3 4.3 1.15 Elongation at break [%] 545 914 316 257 352 Tensile shear strength 1.82 0.81 2.96 3.48 0.87 [MPa] Elastic modulus (0-5%) 1.5 0.5 1.8 2.5 1.6 [MPa] Shore A (7 d RT) 41 23 49 45 39.1 Shore A (7 d RT) + 38.3 11.4 42.7 45.5 27.2 1 h 120° C. Shore A (7 d RT) + 31.8 0 37.9 44.7 0 4 h 120° C. Shore A (7 d RT) + 26.7 0 34.5 42 0 8 h 120° C. Shore A (7 d RT) + 25.4 0 33.6 37.6 38.8 1 h 140° C. Shore A (7 d RT) + 9.5 0 20.5 30 0 4 h 140° C. Shore A (7 d RT) + 0 0 14.7 27.5 0 8 h 140° C.

(32) TABLE-US-00007 TABLE 7 Test results for compositions Z-6 to Z-9 Z-9 Z-6 Z-7 Z-8 (Ref.) Tensile strength [MPa] 2.65 3.86 3.51 2.58 Elongation at break [%] 114 123 88 87 Tensile shear strength [MPa] 1.48 2.37 2.53 1.38 Elastic modulus (0-5%) [MPa] 2.3 4.2 7.7 2.9 Shore A (14 d RT) 52 63 72 57 Shore A (14 d RT) + 2 h 120° C. 50 60.3 69.2 54.2 Shore A (14 d RT) + 4 h 120° C. 49.7 61.5 70 54.5 Shore A (14 d RT) + 6 h 120° C. 48.7 60.7 71.3 55 Shore A (14 d RT) + 8 h 120° C. 47.3 61.3 70 53

(33) TABLE-US-00008 TABLE 8 Test results for compositions Z-10 to Z-13 Z-10 Z-11 (Ref.) (Ref.) Z-12 Z-13 Tensile strength [MPa] 1.7 2.4 1.6 1.6 Elongation at break [%] 260 350 600 560 Tear propagation resistance 4.0 5.2 12.0 9.0 [N/mm] Elastic modulus (0-5%) [MPa] 0.7 0.7 1.7 1.3 Shore A (14 d RT) 26 30 33 31 Skin time (min) 35 45 50 50

(34) TABLE-US-00009 TABLE 9 Test results for compositions Z-14 to Z-19. Z-14 Z-15 Z-16 (Ref.) (Ref.) (Ref.) Z-17 Z-18 Z-19 Tensile strength 3 2.9 3 1.8 1.5 1.5 [MPa] Elongation at break 120 140 180 101 93 93 [%] Tear propagation 3.2 3.4 4.0 3.5 3.5 3.3 resistance [N/mm] Elastic modulus 2.5 2.3 2.4 2.2 2.3 1.9 (0-5%) [MPa] Shore A (14 d RT) 50 50 50 n/m n/m n/m Skin time (min) 50 60 50 18 16 14 SBI Test (DIN EN C n/m n/m B B B 13501-1) (s2, d0) (s2, d0) (s1, d0) (s1, d0) “n/m” means that this value was not measured.

(35) The measured results in tables 6 to 9 clearly show that the inventive compositions are superior to the noninventive examples in terms of heat stability, fire properties and mechanics. This shows that irrespective of whether a silane-functional polymer STP or an isocyanate-comprising polyurethane polymer PU is used these properties are only achieved through use of a precipitated, surface-coated aluminum trihydrate ATH. Moreover, further improved properties may also be achieved through the use of carbon black or expanded clay.