ALDIMINE CONTAINING GLASS BONDING PRIMER

Abstract

A novel primer composition contains aldimine and/or epoxy resins, a process of making such primer to be used in glass bonding adhesive kit.

Claims

1. A primer composition comprising, based on the total weight of the composition: an organic solvent, selected from acetone, methyl ethyl ketone, and a mixture thereof; an aldimine; an alkoxysilane; a non-reactive film forming resin; a polyisocyanate prepolymer; a reactive modifier, which is an oxazolidine-containing compound; a catalyst; an isocyanate stabilizer, which is diethyl malonate; and less than 10 wt % of a diglycidyl ether of bisphenol A.

2. The primer composition of claim 1 which is substantially free of carbon black.

3. The primer composition of claim 1 wherein the aldimine is a dialdimine.

4. The primer composition of claim 1 wherein the aldimine is reaction of polyetheramines and benzaldehyde.

5. The primer composition of claim 1 wherein alkoxysilane is a reaction product of gamma-mercaptopropyltrimethoxysilane and hexamethylene diisocyanate (HDI) biuret.

Description

EXAMPLES

[0017] The present invention can be further demonstrated with the following non-limiting examples.

[0018] Table 1 illustrates the various raw material components and their sources used in the making the examples to demonstrate the present invention.

TABLE-US-00001 TABLE 1 Components used in the present invention Component Component Type Description Supplier A solvents acetone and methyl ethyl ketone Sigma Aldrich (Ratio by weight = 1:1) B dialdimine Incozol BH Incorez C alkoxysilane reaction product of gamma- Silquest A189 from intermediate mercaptopropyltrimethoxysilane Momentive and (e.g., Silquest A189) and Desmodur N100 from hexamethylene diisocyanate(HDI) Covestro AG biuret (e.g., Desmodur N100) D diglycidyl ether DER. 332 Olin Corpomtion of bisphenol A E film forming VITEL 2301 BU (40 wt.% Bostik resin solution in methyl ethyl ketone) F aliphatic and Desmodur RFE, Desmodur HL, Desmodur RFE, aromatic and PAPI 20 (Ratio by weight = Desmodur HL from polyisocyanates 1:1:2.67) Covestro AG and PAPI 20 Dow Chemical Company G oxazolidine PARALOID QM-1007 Dow Chemical Company reactive modifier H catalyst KKAT 670 or FOMREZ UL28 KKAT 670 from King Industries and FOMREZ UL28 from Momentive I isocyanate diethyl malonate Sigma Aldrich stabilizer

[0019] Table 2 summarized various Examples prepared to demonstrate the present invention. Examples 1 to 6 are inventive samples that contain aldimine while Examples 7 to 10 are comparative samples that do not contain aldimine.

TABLE-US-00002 TABLE 2 Contents of Various Examples Prepared. Component Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Ex 10 A 30.84 30.86 30.87 30.87 25.87 35.87 30.86 30.87 30.87 35.87 B 3.34 6.67 5 5 5 5 0 0 0 0 C 10.01 6.67 5 5 10 5 6.68 15 15 5 D 6.68 6.67 5 5 5 0 13.33 0 0 5 E 23.23 23.23 28.23 28.23 28.23 28.23 23.23 28.23 28.23 28.23 F 23.37 23.37 23.37 23.37 23.37 23.37 23.37 23.37 23.37 23.37 G 2 2 2 2 2 2 2 2 2 2 H .sup.0.2 .sup.1 .sup.0.2 .sup.1 .sup.0.2 .sup.1 .sup.0.2 .sup.2 .sup.0.2 .sup.2 .sup.0.2 .sup.2 .sup.0.2 .sup.1 .sup.0.2 .sup.1 .sup.0.2 .sup.2 .sup.0.2 .sup.2 I 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33 .sup.1 Using Fomrez UL28 available from Momentive .sup.2 Using KKAT 670 available from King Industries

[0020] In addition, two commercial black primers were also used as comparative examples. The first primer, Example 11, is a commercial two-step glass bonding primer known as BETASEAL 43520A, commercially available from the Dow Chemical Company, which contains carbon black but does not contain aldimine or epoxy resin. The primer has to be used in conjunction with BETASEAL 43518, commercially available from the Dow Chemical Company, which is a solvent based silane blend. During glass bonding, BETASEAL 43518 is first applied on the glass side to condition the glass surface. BETASEAL 43520A is then applied on the conditioned glass surface.

[0021] Another comparative primer example, Example 12, is a commercial one-step primer known as BETAPRIME 5504G, also available from the Dow Chemical Company, which contains carbon black but does not contain aldimine or epoxy resin. The primer is directly applied on the glass surface.

All samples were prepared in the following manner:

[0022] Primer for glass bonding of the present invention was prepared using a 2-step process. In the first step, Component C was prepared by combining Desmodur N 100 (aliphatic hexamethylene diisocyanate based polyisocyanate) and SILQUEST A189 (gamma-mercaptopropyltrimethoxysilane) and methylethylketone to get a 70% solids solution. Desmodur N 100 and SILQUEST A189 were added to get 3:1 equivalents of isocyanate and the mercapto groups. FASCAT 4202 (dibutyltin dilaurate) catalyst was then added to the blend. The solution was allowed to react in a reaction vessel at 60 C. until all mercapto groups were consumed. The resulting reaction product is the organosilane intermediate (Component C of Table 1). The rest of the components given in Table 1 were then added in an aluminum container. The organosilane intermediate was added along with the catalyst (Component H). The components were then stirred using a tongue depressor.

[0023] Comparative Examples (Examples 7-10) were similarly prepared without the addition of aldimine.

[0024] Both kinds of Example primes were used to study adhesion performance of the primer on 35 glass substrates. The glass substrates were cleaned with acetone and isopropanol prior to applying the primers. The primers were applied using a 1 mil drawdown bar. The primer was allowed to cure for under ambient condition for the required amount of time.

[0025] The performances of primer of the present invention were evaluated using the following test methods:

[0026] Scratch Adhesion Test: Adhesion test was performed by coating the primer on a glass substrate using a 1 mm diameter hemispherical stainless steel scratch head. After curing the primers for 24 hours, scratches were applied on the primer surface using this scratch head. For each test, a set of 8 scratches were applied by varying the normal load from 200 to 1000 g. The minimum force required to remove the primer from the glass surface was reported as the adhesion force between the primer and glass.

[0027] Shelf Stability Test: Freshly prepared primers stored in aluminum bottles were placed in 54 C. oven for 3 days. After 3 days, bottles were removed from the oven. Primers that gelled do not pass the shelf stability test, whereas the primers that do not gel pass the shelf stability test.

[0028] Hydrolytic Stability Test: Glass coated with the primer was allowed to cure for 7 days under ambient condition. The primer coated glass was then immersed in 90 C. water bath for 10 days. After 10 days, the primer coated glass was removed from the water bath and air dried for 4 hours. Finally, the scratch adhesion test was performed on this primer and the minimum adhesion force required to remove the primer from the substrate was recorded.

[0029] Quick Knife Test (SAE J1720): a 6.3 mm (width)6.3 mm (height)100 mm (length) bead of adhesive was placed on the primer coated substrate. The adhesive was cured under the conditions of 23 C. and 50 percent relative humidity for 24 hours. The cured bead was then cut with a razor blade through to the substrate at a 45 angle while pulling back the end of the bead at 180 angle. Notches were cut every 3 mm on the substrate. The adhesion failure was noted as 1. Cohesive Failure (CF), i.e., adhesion failure occurring within the adhesive; as 2. Adhesive failure to Primer (AFP), i.e., failure at primer adhesive interface; and as 3. Primer failure to glass (PFG), i.e., failure at primer glass interface.

[0030] Lap Sheer Test: Primer samples were coated on plate glass and were allowed to dry for 1 hour. Adhesive bead of BETASEAL Express, commercially available from The Dow Chemical Company, was applied on the dried primers. An e-coat coupon was then placed on the bead in a lap assembly. The adhesive was allowed to cure for 24 hours prior to lap sheer test. Lap sheer was performed by pulling the two substrates at a rate of 5 inch/min. The peak force required to pull the two substrate apart and the adhesion failure mode was recorded.

[0031] All above performance test results are summarized in Table 3.

TABLE-US-00003 TABLE 3 Performance of Inventive Examples and Comparative Examples Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Color Clear Clear Clear Clear Clear Clear Type 1-step 1-step 1-step 1-step 1-step 1-step Shake before No No No No No No use Adhesion after 900 1000 1000 1000 1000 1000 24 hours Adhesion after 900 967 1000 967 1000 767 10 day 90 C. water soak Blistering after None Moderate None None None Severe 10 d 90 C. water soak Shelf Stable No No No Yes Yes Yes (54 C. Gel test) Quick knife test 95CF/5PFG 100CF 95CF/5PFG 90CF/10PFG 95CF/5PFG (Express on glass, 1 d RT) Quick knife test 100CF 90CF/10PFG 95CF/5PFG 95CF/5PFG 90CF/10PFG 95CF/5PFG (Express on glass, 7 d RT) Quick knife test 100 CF 100CF 95CF/5PFG 90CF/10PFG 90CF/10PFG (X2500 on glass, 1 d RT) Quick knife test 100 CF 100CF 100CF 5CF/95PFG 50CF/50PFG (X2500 on glass, 7 d RT) Lap Sheer 581 (100CF) 577 (100CF) (Express on clear glass) RT Lap Sheer 165 (100AF 179 (100AF (Express on to ecoat) to ecoat) clear glass) 10 d at 90 C. water Ex 7 Ex 8 Ex 9 Ex 10 Ex 12 Ex 13 Color Clear Clear Clear Clear Black Black Type 1-step 1-step 1-step 1-step 2-step 1-step Shake before No No No No Yes No use Adhesion after 967 967 967 1000 1000 600 24 hours Adhesion after 400 300 767 700 1000 1000 10 day 90 C. water soak Blistering after Moderate Slight Moderate Slight None None 10 d 90 C. water soak Shelf Stable No No No No Yes Yes (54 C. Gel test) Quick knife test 95CF/5PFG 95CF/5PFG (Express on glass, 1 d RT) Quick knife test 100CF 90CF/10PFG 90CF/10PFG 100 CF 100 CF (Express on glass, 7 d RT) Quick knife test 95CF/5PFG 95CF/5PFG (X2500 on glass, 1 d RT) Quick knife test 98CF/2PFG 95CF/5PFG (X2500 on glass, 7 d RT) Lap Sheer 523 (100CF) (Express on clear glass) RT Lap Sheer 100 (100AF (Express on to ecoat) clear glass) 10 d at 90 C. water

[0032] Table 3 shows the performance of the inventive primer examples and the comparative examples. All primers, with the exception of Ex 13, showed good adhesion to the glass surface after 24 hour cure. The adhesion value for these primers exceeds the maximum measurable value of the instrument (i.e., 1000 g). In comparison, Ex 13 primer has relatively low dry adhesion value (600 g), which can be attributed to the slow cure kinetics of the primer.

[0033] The Scratch Adhesion Test performed after 10 days in 90 C. water soak demonstrates the hydrolytic stability of the primers. Adhesion values after 10 days 90 C. water soak are provided in Table 3.

[0034] It is clearly evident that the inventive primers perform much better than the comparative examples. Both epoxy resin and aldimine are required to enhance hydrolytic stability of the primer. Primers of Examples 1, 2, 3, 4, and 5 contain both epoxy and aldimine and resulted in excellent hydrolytic stability, as seen by the scratch test performed after immersing the primer in 90 C. water for 10 days. In addition, the lap sheer test performed after immersing the assembly in 90 C. water for 10 days also show that presence of both aldimine and epoxy is needed to have better lap sheer performance. Primer of Example 6, which contains the aldimine but not the epoxy resin, shows excellent adhesion at room temperature as evident from the scratch test. However, the hydrolytic stability of this primer is slightly lower compared to the primers of Examples 1 through 5. In addition, this primer also shows more severe blistering relative to the primers of Examples 1 to 5. In the absence of both epoxy and the aldimine, the primers have lower hydrolytic stability (Examples 6, 7, 10, and 11).

[0035] In addition, the aldimine helps to stabilize the primer and therefore enhances the shelf stability of the primer. Shelf stability also depends on the catalyst used. In the case of a tin catalyst such as Fomrez UL28, as used in Examples 1, 2, and 3, primers do not pass the 54 C. gel test indicating a shorter shelf life. In comparison, primers containing a non-tin catalyst such as KKAT 670, as used in Examples 4 and 5, are more likely to pass the 54 C. gel test. However, even if the primer contains KKAT 670 as the catalyst, it can still fail the gel test when aldimine is absent in the composition. This is evident in Examples 9 and 10. Both of these primers do not contain aldimine and therefore fail the gel test.

[0036] Quick knife test was performed to evaluate the link up rate with moisture-cured urethane adhesives. All primer show excellent linkup time (100% cohesive failure) with BETASEAL Express as the urethane adhesive after 7 day adhesive cure. The presence of aldimine and/or epoxy does not compromise the link up rate of the primer to adhesive.

[0037] It is also observed that in the preferred embodiment of the present invention primer contains a dialdimine such as Incozel BH (commercially available from Incorez), which is a reaction product of polyetheramines (e.g., JEFFAMINE D400, commercially available from Huntsman) and benzaldehyde.