Compositions based on silane-terminated polymers with improved adhesion on thermoplastics

Abstract

An adhesive composition, including at least polymer containing silane groups, between 15 and 35 wt.-% of at least one polymeric plasiticzer, between 0.5 and 2.5 wt.-% of at least one monomeric or oligomeric aminofunctional alkoxysilane S1 with a nitrogen content of between 4.5 and 14.5 wt.-%, and between 0.5 and 2.5 wt.-% of at least one oligomeric aminofunctional alkoxysilane S2 with a nitrogen content of between 15 and 20 wt.-%. The adhesive composition is particularly suitable to seal or bond thermoplastic substrates, such as polyolefins or bituminous materials, and shows fast adhesion build-up and low volatile organic carbon (VOC).

Claims

1. An adhesive composition, comprising at least one polymer P containing silane groups; between 15 and 35 wt.-%, based on the total composition, of at least one polymeric plasiticzer PL; between 0.5 and 2.5 wt.-%, based on the total composition, of at least one monomeric or oligomeric aminofunctional alkoxysilane S1 with a nitrogen content of between 4.5 and 14.5 wt.-%, based on the total weight of S1; between 0.5 and 2.5 wt.-%, based on the total composition, of at least one oligomeric aminofunctional alkoxysilane S2 with a nitrogen content of between 15 and 20 wt.-%, based on the total weight of S2.

2. The adhesive composition as claimed in claim 1, wherein the polymer P containing silane groups is a polyorganosiloxane having terminal silane groups.

3. The adhesive composition as claimed in claim 1, wherein the polymer P containing silane groups is an organic polymer containing silane groups.

4. The adhesive composition as claimed in claim 2, wherein the organic polymer P containing silane groups is a a polyurethane, polyolefin, polyester, polycarbonate, polyamide, poly(meth)acrylate or polyether or a mixed form of these polymers.

5. The adhesive composition as claimed in claim 1, wherein the polymeric plasticizer PL is a polyether plasticizer.

6. The adhesive composition as claimed in claim 1, wherein the monomeric or oligomeric aminofunctional alkoxysilane S1 and/or the oligomeric aminofunctional alkoxysilane S2 comprise secondary amino groups.

7. The adhesive composition as claimed in claim 1, wherein the monomeric or oligomeric aminofunctional alkoxysilane S1 comprises N-(n-Butyl)-3-aminopropyltrimethoxysilane and/or an oligomer obtained from the condensation of N-(n-Butyl)-3-aminopropyltrimethoxysilane with alkylalkoxysilanes.

8. The adhesive composition as claimed in claim 1, wherein the monomeric or oligomeric aminofunctional alkoxysilane S1 has a viscosity of between 2 and 40 m.Math.Pas, measured at 20° C. according to DIN 53015.

9. The adhesive composition as claimed in claim 1, wherein the oligomeric aminofunctional alkoxysilane S2 comprises an oligomer obtained from the condensation of N-(n-Butyl)-3-aminopropyltrimethoxysilane.

10. The adhesive composition as claimed in claim 1, wherein the oligomeric aminofunctional alkoxysilane S2 has a viscosity of between 1500 and 3500 m.Math.Pas, measured at 20° C. according to DIN 53015.

11. The adhesive composition as claimed in claim 1, wherein the composition comprises the polymer P with an amount of between 10 and 25 wt.-%, based on the total composition.

12. The adhesive composition as claimed in claim 1, wherein the composition furthermore comprises between 0.5 and 2.5 wt.-% vinyl trimethoxysilane, based on the total composition.

13. A method of adhesively bonding or sealing a substrate, comprising applying an adhesive composition according to claim 1 to a substrate.

14. The method according to claim 13, wherein the substrates are selected from the group consisting of fluoropolymer-coated aluminum, rubber, poly(methyl methacrylate), polycarbonate, polyolefins, and polyethylene laminated with bituminous backside.

Description

EXAMPLES

(1) Adduced hereinafter are working examples which are intended to elucidate the invention described in detail. 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) Viscosities mentioned in the tables are referring to measurements done according to DIN 53015 measured at 20° C.

(4) Adhesions were tested according to the following procedure: To examine the adhesion, the respective substrate was briefly wiped with a cellulose cloth containing isopropyl alcohol and after 10 min, the adhesive to be tested was applied to the substrate as a round bead with a caulking gun and a nozzle. Then, the adhesive was cured for 7 days at 23° C. and 50% r.h. (standard climatic conditions) and subsequently the adhesion was examined. During the adhesion test, the cured beads were in each case cut slightly over the surface of the substrate (adhesive surface) on one end. The cut end of the bead was grasped and then carefully and slowly, peeling in the direction of the other end of the bead, pulled from the surface of the substrate. In this case, if the adhesion was so strong that the bead end threatened to tear when pulled, a cut was made perpendicular to the bead-pulling direction up to the smooth surface of the small plate by means of a cutter, and a part was thus detached from the bead. Such cuts were, if necessary, repeated at intervals of 2 to 3 mm as pulling continued. In this way, after each corresponding storage time, one third of the bead was pulled or cut from the small plates. The evaluation of the adhesive properties was carried out based on the cured composition, which remained after the bead on the substrate surface was removed (cohesion failure), namely by estimating the cohesive portion of the adhesive surface. The evaluation of the adhesive properties is carried out by estimating the cohesive portion of the adhesive surface:

(5) 1: >95% cohesive failure, 2: 75-95% cohesive failure, 3: 25-75% cohesive failure, 4: <25% cohesive failure, 5: 0% cohesive failure (pure adhesive failure). A lower number for the adhesion result means a better adhesion on the substrate.

(6) Compounds Used:

(7) TABLE-US-00001 TABLE 1 Compounds used for the example compositions. Name Description, trade name Polymer STP-1 Polymer having silane groups; preparation detailed (Polymer P) below MS 203H Silane-functional polyether polymer (MS Polymer ® (Polymer P) S203H, Kaneka) STP-E15 Silane-functional polyether polymer (Geniosil ® (Polymer P) STP-E15, Wacker) Polyether Polyether polyol (Acclaim ® Polyol 4200, Covestro); (Polymeric M.sub.n approx. 4000 g/mol plasticizer PL) DIDP Diisodecyl phthalate (Jayflex ® DIDP, ExxonMobil) (plasticizer) DINCH 1,2-Cyclohexane dicarboxylic acid diisononyl ester (plasticizer) (Hexamoll ® DINCH, BASF) Thixotropy Modified castor oil (Thixatrol ® ST, Elementis) additive VTMO Vinyl trimethoxysilane (Dynasylan ® VTMO, Evonik) (drying agent) AMMO 3-Aminopropyltrimethoxysilane with 7.81 wt.-% (Silane S1) nitrogen and a viscosity of 2 mPa .Math. s (Dynasylan ® AMMO, Evonik) 1189 N-(n-Butyl)-3-aminopropyltrimethoxysilane with (Silane S1) 6.8 wt.-% nitrogen and a viscosity of 2.5 mPa .Math. s (Dynasylan ® 1189, Evonik) 1146 Oligomer of diaminoalkoxysilane (comprising (Silane S1) secondary amino groups) and alkylalkoxysilane with 5-7 wt.-% nitrogen and a viscosity of 35 mPa .Math. s (Dynasylan ® 1146, Evonik) 1124 (Silane) Bis(trimethoxysilylpropyl)amine with 4.1 wt.-% nitrogen and a viscosity of 6.5 mPa .Math. s (Dynasylan ® 1124, Evonik) A-174 3-(Trimethoxysilyl)propyl methacrylate (Silquest ® (Silane) A-174, Momentive) SIVO 280 Modified oligomer of N-(n-Butyl)-3- (Silane S2) aminopropyltrimethoxysilane with 15.5-17.5 wt.-% nitrogen and a viscosity of ≤3000 mPa .Math. s (Dynasylan ® VPS SIVO 280, Evonik) 6490 (Silane) Oligomer of vinyl trimethoxysilane without amino groups and a viscosity of 2-4 mPa .Math. s (Dynasylan ® 6490, Evonik) PCC (Filler) Surface-treated, nanosized precipitated calcium carbonate (Ultra-Pflex ®, Specialty Minerals Inc.) GCC (Filler) Surface-treated ground limestone (Pfinyl ® 402, Specialty Minerals Inc.) Catalyst Dibutyltin dilaurate (Fascat ® 4202, PMC Organometallix)

(8) Preparation of a Polymer P Containing Silane Groups:

(9) Polymer STP-1:

(10) With exclusion of moisture, 1000 g of Acclaim® 12200 polyol (polyoxy-propylenediol having a low level of unsaturation, from Covestro; OH number 11.0 mg KOH/g), 43.6 g of isophorone diisocyanate (IPDI; Vestanat® IPDI, from Evonik), 126.4 g of diisodecyl phthalate (DIDP) and 0.12 g dibutyl tin dilaurate (DBTDL) were heated up to 90° C. while stirring constantly and left at this temperature until the content of free isocyanate groups determined by titrimetry had reached a stable value of 0.63% by weight. Subsequently, 63.0 g of diethyl N-(3-trimethoxysilylpropyl)-aminosuccinate (adduct formed from 3-aminopropyltrimethoxysilane and diethyl maleate; prepared according to the details in 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 means of FT-IR spectroscopy. The polyether containing trimethoxysilane groups thus obtained, having a silane equivalent weight of about 6880 g/eq (calculated from the amounts used), was cooled down to room temperature and stored with exclusion of moisture.

(11) Compositions Based on Polymers Containing Silane Groups:

(12) Comparative examples (not according to the present invention) are identified in tables 2 to 5 by “(Ref.)”.

(13) Compositions C1 to C11:

(14) A series of example compositions was prepared by mixing the ingredients shown in Tables 2 and 4 under nitrogen atmosphere in a vacuum mixer. First, the polymer P, the plasticizer, the thixotropy additive, and VTMO (where applicable) were thoroughly mixed for 5 minutes. Subsequently, the dried fillers were added with kneading during 15 minutes at 60° C. With the heater switched off, silanes S1 and S2 and other silanes (where applicable) and catalyst were added and the compostions were subsequently processed to a homogeneous paste during 10 minutes under vacuum. Said paste was subsequently filled into internally coated aluminum spreading piston cartridges which were closed air-tight and stored under standard climate conditions for at least 24 h until the testing protocol was employed.

(15) TABLE-US-00002 TABLE 2 Example compositions (all numbers in wt.-%, based on the total individual composition). C3 C4 C5 C11 Composition C1 C2 (Ref.) (Ref.) (Ref.) (Ref.) Polymer STP-1 (Polymer P) 17.5 17.5 17.5 17.5 17.5 17.5 Polyether (Polymeric 22 22 — — 22 22 plasticizer PL) DIDP (plasticizer) — — 22 22 — — Thixotropy additive 4 4 4 4 4 4 VTMO (drying agent) 2 2 2 2 2 2 A-174 (Silane) — — — — — 1 1189 (Silane S1) 1 — 1 1 1 — 1146 (Silane S1) — 1 — — — — SIVO 280 (Silane S2) 1 1 — 1 — 1 PCC (Filler) 15 15 15 15 15 15 GCC (Filler) 37 37 37 37 37 37 Catalyst 0.5 0.5 0.5 0.5 0.5 0.5

(16) TABLE-US-00003 TABLE 3 Adhesion tests on plastic substrates. The values indicate adhesion performance (details above) after 7 d curing under standard climate conditions. C3 C4 C5 C11 Substrate C1 C2 (Ref.) (Ref.) (Ref.) (Ref.) Acrylonitrile butadiene styrene 1 1 5 5 5 n/m (ABS) sheet Ethylene propylene diene (M-class) 1 2 5 5 5 5 rubber (EPDM) Styrene butadiene rubber (SBR) 1 1 5 1 1 n/m Acrylonitrile butadiene rubber 1 1 4 5 3 n/m (NBR) “n/m” means that this value was not measured.

(17) An additional test with EPDM (Ethylene propylene diene (M-class) rubber) substrate using compositions C1 and C11 was performed by comparing the adhesion after one-week immersion in water (55° C.) of the cured adhesion bead samples. The test sample with composition C1 showed fully cohesive failure (“1”) after water immersion while the sample with reference composition C11 showed fully adhesive failure (“5”).

(18) TABLE-US-00004 TABLE 4 Example compositions (all numbers in wt.-%, based on the total individual composition). Composition C6 C7 C8 C9 C10 (Ref.) (Ref.) (Ref.) (Ref.) (Ref.) Polymer STP-1 (Polymer P) — 23 23 23  — MS 203H (Polymer P) 48.7 — — — — STP-E15 (Polymer P) — — — — 39  Polyether (Polymeric — 22 — — 7 plasticizer PL) DINCH (plasticizer) — — 17  16.5 — Thixotropy additive 4  4 4 4 4 VTMO (drying agent) 2  2 — 2 — 1189 (Silane S1) 1.5 — — — — AMMO (Silane S1) 2  1 — 1 — SIVO 280 (Silane S2) — — 1 — 1 1124 (Silane) —   0.5 — — 6490 (Silane) — — 1.5   1.5 GCC (Filler) 41.3 47 53 53  47  Catalyst 0.5   0.5 0.5   0.5   0.5

(19) TABLE-US-00005 TABLE 5 Adhesion tests on plastic and polyolefinic laminated bituminous substrates. The values indicate adhesion performance (details above) after 7 d curing under standard climate conditions. C6 C7 C8 C9 C10 Substrate C1 C2 (Ref.) (Ref.) (Ref.) (Ref.) (Ref.) Henry Blueskin Thru-Wall 1 1 5 5 5 5 5 Flashing Membrane (SBS rubberized bituminous backside, laminated yellow smooth polyethylene front) Grace Perm-A-Barrier Wall 1 1 5 5 5 5 5 Flashing (rubberized bituminous backside, laminated with smooth polyethylene front) Carlisle VapAir Seal 1 1 5 5 5 5 5 725TR (rubberized bituminous backside, laminated with smooth woven polypropylene film) Henry Blueskin VP160 4 3 5 5 5 5 5 (PSA polymer layer backside, laminated with a polyethylene/ polypropylene fibre cloth, spun woven) Cetco Envirosheet (SBS 1 1 5 5 5 5 5 rubberized bituminous sheet with polyethylene laminated front) Ethylene propylene diene 1 2 5 5 5 5 5 (M-class) rubber (EPDM)