AU6981600A

AU6981600A - Bonding agent

Info

Publication number: AU6981600A
Application number: AU69816/00A
Authority: AU
Inventors: Marlies Hulsebusch; Jurgen Lindner
Original assignee: Atlas Elektronik GmbH
Current assignee: Atlas Elektronik GmbH
Priority date: 1999-08-03
Filing date: 2000-07-27
Publication date: 2001-02-19
Anticipated expiration: 2020-07-27
Also published as: NO20020436D0; AU774023B2; WO2001009099A2; EP1200408A2; DE19936472A1; NO321886B1; ATE248820T1; DK1200408T3; EP1200408B1; WO2001009099A3; DE50003566D1; NO20020436L; ZA200200805B

Abstract

The invention relates to 8-hydroxychinoline derivatives, methods for preparing 8-hydroxychinoline derivatives and their use as a bonding agent between metallic surfaces and organic polymer layers. The inventive 8-hydroxychinoline derivatives are capable of bonding organic polymer layers to metallic surfaces.

Description

-1 Adhesion promoters The present invention relates to 8-hydroxy-quinoline derivatives, methods of preparing 8-hydroxy-quinoline derivatives, and their use as adhesion promoters between metal surfaces and organic polymer layers. Possible metal surfaces are in particular iron alloys and ceramic surfaces coated with silver or gold, e.g. piezo ceramics. Possible organic polymer layers are in particular polyurethanes, e.g. adhesives and varnishes. When the adhesion promoter of the invention is used, the organic polymer layer can be applied from an organic solution or an aqueous dispersion of the varnish or adhesion components which only complete their polymerisation on the adhesion promoter layer. Adhesion promoters used so far, also known as primers, such as zinc chromate primers, for example, are toxic because of their content of heavy metals and are therefore harmful to the environment. The problem in the present case thus consists in providing a toxicologically acceptable and environmentally compatible adhesion promoter which can bond organic polymer layers, such as varnish and adhesive layers, firmly to metal surfaces. In the present case, there is the further problem of finding a method of preparing suitable adhesion promoters which is capable of providing a sufficiently high reaction yield with a small number of reaction steps, so that there is no need for extensive purification or isolation steps in order to recover the adhesion promoter from the reaction mixture. The solution according to the invention is provided by modifying 8-hydroxy quinoline with organic diazonium compounds. It has been found that 8-hydroxy quinoline derivatives are especially suitable as adhesion promoters when they carry a substituent which is linked via an azo-coupling and which carries a group capable of reacting with components in the organic polymer layer to be applied. As an organic product, an adhesion promoter on the basis of 8-hydroxy-quinoline derivatives is, as a matter of principle, capable of being degraded chemically or biologically into harmless products.

-2 8-hydroxy-quinoline, also known as 8 quinolinol or oxine, is known in medicine as a fungicide and antiseptic, and in analytical chemistry as an organic complexing agent for more than 40 different metals. It has not, however, been proposed before to pro vide adhesion promoters on the basis of 8-hydroxy-quinoline for layers of adhesive or varnish which are to be applied to a metal surface. Furthermore, no method has previously been provided for preparing 8-hydroxy-quinoline derivatives which gives a high reaction yield with a small number of reaction steps. Together with the polymer combination, the adhesion promoters of the invention exhibit very high moisture resistance and good corrosion protection properties. Furthermore, these adhesion promoters possess only slight toxicity. In order to apply the adhesion promoters to the surfaces to be coated, only a minor temperature influ ence is exerted on the substrate, and, moreover, high consistency and reproducibility of the application is achieved. The azo-coupling of an organic substituent carrying a polymer-specific group to the 8-hydroxy-quinoline can be achieved by means of the corresponding diazonium compound of the substituent. The diazonium compound of the organic substituent, which carries a further reactive polymer-specific group, can be obtained by reacting the corresponding amine compound with nitrite, e.g. sodium nitrite. The general reaction scheme for the azo-coupling of the substituent carrying a reactive polymer-specific group to the 8-hydroxy-quinoline takes place according to the general reaction scheme: + OH OH

N

2 N N R N R R = reactive group, especially amino, carboxy, epoxy or vinyl group.

-3 Instead of the benzene ring in the substituent, other organic radicals which act as a spacer molecule can also be used. In the general reaction scheme shown here, the benzene ring acts as a spacer at the same time. It is also possible to use alkenyl radicals with 2 to 6 carbon atoms as spacers, such as ethenyl, propenyl, butenyl, pentenyl and hexenyl. Substituents can also be linked to the 8-hydroxy-quinoline via an azo-coupling if they have more than just one reactive group. The azo-coupling of the diazonium substituent occurs almost exclusively in the 5 position of the 8-hydroxy-quinoline. The present invention will now be described in more detail with reference to the following examples, though these are not to be understood as limiting. Brief description of the drawings: Figure 1 shows the FT IR drift spectrum of an adhesion promoter on the basis of 8 hydroxy-quinoline. Figure 2 shows the FT IR spectrum of the adhesion promoter when applied to sheet silver. Figure 3 shows the FT IR drift spectrum of an adhesion promoter on the basis of 8 hydroxy-quinoline. Figure 4 shows the FT IR spectrum of the adhesion promoter after being applied to a gilded stainless steel sheet. Figures 5 and 6 show the structure of a coat on metal surfaces 1, 5, consisting of adhesion promoter 2, 4 and organic polymer 3. Figure 7 shows structural formulae of adhesion promoters of the invention.

-4 Example 1: Synthesis of 5-(p-aminobenzyl-azo)-8-hydroxy-quinoline 2.44 g (0.02 mol) of p-aminobenzylamine are added to a mixture consisting of 9 ml (0.1 mol) of 37 % strength hydrochloric acid and 35 ml water. The solution is cooled to 0-5' C. Diazotisation is initiated by adding a solution of 1.38 g (0.02 mol) NaNO 2 in 10 ml water. The mixture is then stirred at room temperature for 30 minutes. This solution of diazotised p-aminobenzylamine is dripped slowly into a cold solution (0-5* C) of 2.90 g 8-hydroxy-quinoline in an 80 % acetic acid solution so that the temperature does not rise above 5' C. After everything has been added, stirring continues at this temperature for a further 2 hours, and then the mixture is allowed to warm up slowly to room temperature. In the process, some of the product already precipitates. Complete precipitation is achieved by careful neutralisation while cooling with an aqueous ammonia solution. The precipitated product is filtered off by suction and rinsed with ice water. The decomposition temperature is 273* C. The IR spectrum exhibits the following peaks: 3005, 2865, 1630, 1605, 1550, 1505, 1400, 1375, 1350, 1300, 1235, 1080, 850 cm 4 . 'H NMR spectrum (250 MHz, DMSO, deep-field shift compared to TMS): 9.33 ppm (1 H), 8.99 ppm (1 H), 8.03 ppm (1 H), 8.02 ppm (2 H), 7.77 ppm (1 H), 7.71 ppm (2 H), 7.25 ppm (1 H), 4.14 ppm(2H). Example 2: Synthesis of 5-(p-hydroxybenzyl-azo)-8-hydroxy-quinoline 2.46 g (0.02 mol) 4-aminobenzyl alcohol are cooled to 0-5* C in a mixture of 5 ml concentrated HCl and 100 ml water and diazotised with 1.38 g (0.02 mol) NaNO 2 in 10 ml water. 2.90 g (0.02 mol) 8-hydroxy-quinoline are dissolved in 10 ml 1 M NaOH and cooled to 0-5* C. This solution is slowly added to the solution of diazotised 4-aminobenzyl alcohol. It is stirred at this temperature for a further 16 hours. After this, the mixture is neutralised with concentrated acetic acid and the resultant product is filtered off by suction. The melting point is 2210 C. The IR spectrum exhibits the following peaks: 3290, 3065, 2920, 2865, 1570, 1475, 1280, 1225, 1190, 1020, 845, 790, 710 cm 1 . 'H NMR spectrum (250 MHz, DMSO, deep-field shift compared to TMS): 9.31 ppm (1 -5 H), 9.00 ppm (1 H), 8.01 ppm (1 H), 7.97 ppm (2 H), 7.76 ppm (1 H), 7.56 ppm (2 H), 7.26 ppm (1 H). 1 3 C NMR spectrum (62.9 MHz, deep-field shift compared to TMS): 157.3 ppm, 151.5 ppm, 148.9 ppm, 145.5 ppm, 138.6 ppm, 137.9 ppm, 131.7 ppm, 127.4 ppm, 127.1 ppm, 123.0 ppm, 122.3 ppm, 114.6 ppm, 111.6 ppm, 62.5 ppm. Example 3: Synthesis of 5-(p-vinyl benzyl-azo)-8-hydroxy-quinoline 2.98 g (0.025 mol) p-vinyl aniline are dissolved in 5 ml concentrated HCl in 100 ml water. The solution is cooled to 0-5* C and diazotised with 1.73 g (0.025 mol) NaNO 2 in 12 ml water. This diazonium solution is slowly added to a cold solution of 3.7 g (0.025 mol) 8-hydroxy-quinoline in 50 ml 2-ethoxy ethanol and a solution of 1 g NaOH and 5 g Na 2

CO

3 in 50 ml water. The solution is subsequently stirred for 24 hours at 0-50 C. The precipitated solids are filtered off by suction and rinsed with ice water. The solids are recrystallised in methanol. The melting point is >300* C. IR spectrum: 3350, 3190, 3030, 2920 1740, 1690, 1600, 1580, 1410, 1340, 1270, 1165, 940, 790, 670 cm-1. H NMR spectrum (250 MHz, DMSO, deep-field shift compared to TMS): 9.33 ppm (1 H), 9.00 ppm (1 H), 8.02 ppm (2 H), 7.92 ppm (1 H), 7.75 ppm (1 H), 7.70 ppm (2 H), 7.23 ppm (1 H), 6.86 ppm (1 H), 6.00 ppm (1 H), 5.40 ppm (1 H). The adhesion promoters of the invention can be applied to a metal surface from an ethanolic solution. The complexing of the metal surface by adhesion promoters of the invention, on the basis of 8-hydroxy-quinoline, becomes clear in the following examples. Example 4: Coating a silver surface with adhesion promoters on the basis of 8 hydroxy-quinoline A comparison of the IR spectra of an adhesion promoter on the basis of 8-hydroxy quinoline, as shown in Figure 1, and the adhesion promoter applied to sheet silver, as shown in Figure 2, shows that the OH oscillation of the adhesion promoter no longer occurs when it is applied to the silver surface.

-6 Example 5: Coating a gold surface with an adhesion promoter on the basis of 8 hydroxy-quinoline A comparison between the IR spectra of an adhesion promoter according to the invention, as shown in Figure 3, and the adhesion promoter applied to gilded stainless steel sheet, as shown in Figure 4, shows that the OH oscillation of the adhesion promoter is no longer present after application to the gold surface. The absence of this OH oscillation is evidence of the formation of a complex between the adhesion promoter of the invention and the gold surface. Example 6: Tensile strength test on CrNil810 For the tensile strength test according to DIN 53281, CrNi 1810 was coated with 25 mg 5-p(aminobenzyl-azo)-8-hydroxy-quinoline, dissolved in 125 ml ethanol, by immersion for 12 hours. After that, epoxy adhesive, type 9323 ex 3M was applied, and the tensile strength was measured after curing and conditioning of the bond. At room temperature, a figure of 19 N/mm 2 was found, and after storage in water for 16 hours at more than 950 C, a figure of 19 N/mm 2 was found, again measured at room temperature. Example 7: Combined tension and shear resistance test on gilded brass sheet Gilded brass sheet was coated with 25 mg 5-(p-vinyl benzyl-azo)-8-hydroxy-quino line, dissolved in 250 ml ethanol, by immersion in a bath in the course of 24 hours. After that, silver-filled epoxy adhesive was applied, and the combined tension and shear resistance after curing and conditioning of the bond at room temperature was determined according to DIN EN 1465, and found to be 9.9 N/mm 2 . Example 8: Combined tension and shear resistance test on gilded brass sheet Gilded brass sheet was coated with 5 mg 5-(p-aminobenzyl-azo)-8-hydroxy-quino line, dissolved in 200 ml ethanol, by immersion for 24 hours. After that, silver-filled epoxy adhesive was applied, and the tensile strength after curing and conditioning of -7 the bond was determined according to DIN EN 1465 at room temperature, and found to be 9.9 N/mm 2 . Example 9: Tensile strength test on AlMgj AlMg 3 was coated with 20 mg 5-(p-vinyl benzyl-azo)-8-hydroxy-quinoline, dis solved in 250 ml ethanol, by immersion for 23 hours. Following this, polyurethane casting resin, e.g. Biresin 1305, was applied, and the tensile strength measured after curing and conditioning of the bond, by determining the tensile strength of two round samples 20 mm in diameter bonded face to face. The test at room temperature showed a tensile strength of 8 N/mm 2 ; after storage in water for 16 hours at a tem perature of more than 950 C, a figure of 4.3 N/mm 2 was found, the measurement again being performed at room temperature. Example 10: Tensile strength test on stainless steel material no. 1.4571 Stainless steel no. 1.4571 was coated with 20 mg 5-(p-vinyl benzyl-azo)-8-hydroxy quinoline, dissolved in 250 ml ethanol, by immersion for 23 hours. After that, poly urethane casting resin, e.g. Biresin U1305, was applied, and the tensile strength was measured as in Example 9 after curing and conditioning of the bond. The measure ment at room temperature showed a tensile strength of 5.1 N/mm 2 , while the tensile strength after storage in water for 16 hours at a temperature of more than 95* C showed a tensile strength of 6.1 N/mm 2 , again measured at room temperature. Example 11: Tensile strength test on silver-coated ceramic A 10 mm piece of silver-coated ceramic was coated with 5-(p-vinyl benzyl-azo)-8 hydroxy-quinoline, as described in Example 10. After curing and conditioning of the bond with polyurethane casting resin, the tensile strength was measured as in Example 9. At room temperature, a strength figure of 4 N/mm 2 was found, while after storage in water for more than 16 hours at a temperature of more than 95* C a strength figure of 1.6 N/mm 2 was found, again measured at room temperature.

-8 Example 12: Tensile strength test on silver-coated ceramic A 10 mm piece of silver-coated ceramic was coated with 5-(p-aminobenzyl-azo)-8 hydroxy-quinoline, as described in Example 10. The tensile strength of the polyurethane casting resin was measured as described in Example 9 after curing and conditioning of the bond. The tensile strength test at room temperature produced a figure of 5.2 N/mm 2 ; after storage in water for 16 hours at a temperature of more than 950 C, a figure of 2.2 N/mm 2 was found, again measured at room temperature. The adhesion promoters of the invention can be applied to the metal surface in a very small layer thickness, i.e. possibly in a monomolecular layer. When building an electronic component, the consecutive layers, namely the adhesion promoter of the invention directly onto a metal surface, and a polymer layer reacting with the reac tive polymer-specific group of the adhesion promoter, can for their part be coated with a layer of the adhesion promoter of the invention which is layered on a metal surface. All together, the structure shown in Figures 5 and 6 results. In Figure 5, layer 1 is a metal surface, layer 2 the layer of adhesion promoter, and layer 3 a layer of organic polymer. In Figure 6, layer 1 is a metal layer, layer 2 the adhesion promoter layer, layer 3 an organic polymer layer, layer 4 a further adhesion promoter layer and layer 5 a fur ther metal layer. Layers 1 in Figures 5 and 6 can also be a thin metal layer applied to a substrate, such as a gold or silver coating on a piece piezo-ceramic, for example. Figure 6 shows a structure in which two metal surfaces, which can be the same or different, layers 1 and 5 respectively, are each covered with a layer of the adhesion promoter, these layers being adjacent, on opposite sides, to a common layer of organic polymer. The adhesion promoter layers 2 and 4 can consist of the same 8 hydroxy-quinoline derivative or of different ones, provided that they only carry reactive groups which can react with monomers or oligomers in the organic polymer layer 3. The organic polymer layer 3 can in this case be a mixture of different mono- -9 mers, e.g. monomers which can form polyesters, polyurethanes, polycarbonates and/or polyamides. The features of the invention disclosed in the above description, in the drawings and in the claims may be essential for carrying out the invention in its various embodi ments both individually and in any combination.

Claims

1. 8-hydroxy-quinoline derivatives, obtainable by azo-coupling 8-hydroxy quinoline to organic diazonium compounds which carry at least one further group capable of a polymerisation reaction with organic polymers.

2. 8-hydroxy-quinoline derivatives as claimed in Claim 1, in which the azo coupled diazonium compounds are aromatic.

3. 8-hydroxy-quinoline derivatives as claimed in either of Claims 1 or 2, in which the azo-coupled diazonium compounds carry at least one further amino, carboxy, epoxy, alkenyl or alkyl group.

4. 8-hydroxy-quinoline derivatives as claimed in Claim 1, which correspond to the following general formula: O H N N it N R where R is an aliphatic or aromatic hydrocarbon with 2 to 6 C atoms which carry at least one reactive substituent.

5. 8-hydroxy-quinoline derivatives as claimed in Claim 4, in which the substitu ent is an amino, epoxy, alkenyl or hydroxy group.

6. A method of preparing 8-hydroxy-quinoline derivatives, characterised in that

8-hydroxy-quinoline is reacted with an organic diazonium compound which carries at least one further group capable of polymerisation. - 11 7. The method as claimed in Claim 6, in which the organic diazonium compound is aromatic. 8. The method as claimed in either of Claims 6 or 7, in which the group of the organic diazonium compound capable of polymerisation contains a further epoxy, carboxy, alkenyl or amino group.

9. The method as claimed in any of Claims 6 to 8, in which a mixture of organic diazonium compounds is used.

10. Use of an 8-hydroxy-quinoline derivative as claimed in any of the preceding claims as an adhesion promoter between a metal surface and an organic polymer layer.