Bonding compositions

Abstract

There is provided a curable composition comprising one or more reactive components that cure upon exposure to suitable conditions, the curable composition comprising: (i) at least one aromatic nitroso or at least one aromatic nitroso precursor compound or combinations thereof; and (ii) a film former component comprising at least one non-halogenated hydroxy group-containing resin together with at least one crosslinking agent.

Claims

1. A curable composition comprising: (i) at least one aromatic nitroso or at least one aromatic nitroso precursor compound or combinations thereof; and (ii) a film former component comprising at least one non-halogenated hydroxy group-containing resin together with at least one crosslinking agent selected from a phenolic resin, an epoxy resin having at least two oxirane ring systems and combinations thereof.

2. The curable composition of claim 1 wherein the at least one non-halogenated hydroxyl group-containing resin includes a co-polymer which is a co-polymer of at least one of polyvinyl alcohol, polyvinyl butyral and polycellulose acetate butyrate.

3. The curable composition of claim 1, wherein the non-halogenated hydroxy group-containing resin is present in the composition in a range of from about 0.5 to 10% wt/wt of the total weight of the curable composition.

4. The curable composition of claim 1, wherein the at least one crosslinking agent is a compound having at least two reactive moieties, each of which can undergo a crosslinking reaction with a hydroxy group of the at least one non-halogenated hydroxy group-containing resin.

5. The curable composition of claim 1, wherein the crosslinking agent is a phenolic resin.

6. The curable composition of claim 1, wherein the crosslinking agent is an epoxy resin having at least two at least two oxirane ring systems.

7. The curable composition of claims 1, wherein the at least one aromatic nitroso compound or at least one aromatic nitroso precursor compound comprises at least one alkoxy silane moiety and at least one moiety selected from an aromatic nitroso or an aromatic nitroso precursor or combinations thereof.

8. The curable composition of claim 1, further comprising a compound comprising: (a) at least one phosphonate moiety; or (b) at least one phosphinate moiety, or combinations thereof.

9. The curable composition of claim 8 wherein the compound is of the general formula: ##STR00045## wherein u is from 0 to 20; A is a direct bond or O; R.sup.4 is selected from the group consisting of H, C.sub.1-C.sub.24 alkyl, and C.sub.3-C.sub.24 acyl; R.sup.5 is selected from the group consisting of C.sub.1-C.sub.24 alkyl, C.sub.1-C.sub.24 alkoxyl and C.sub.3-C.sub.24 acyl; and R.sup.6 is a moiety comprising nitrosobenzene, quinone oxime or quinone dioxime.

10. The curable composition of claim 1, wherein the aromatic nitroso precursor is a nitrosobenzene precursor or comprises an aromatic oxime or an aromatic dioxime or combinations thereof.

11. A process for bonding a material to a substrate, comprising the steps of: a) providing a curable composition as defined in claim 1; b) providing the material to be bonded in a non-cured form, and c) simultaneously curing the composition and the material to be bonded so that the material is bonded to the substrate.

12. A process for bonding a first substrate to a second substrate, comprising the steps of: a) providing a curable composition as defined in claim 1; b) applying the curable composition to at least one part of the surface of the first substrate; and c) contacting said surface of the first substrate with a surface of a second substrate, to which the curable composition is optionally applied, under conditions of heat and pressure sufficient to create a cured bond between the two substrates.

13. A process for crosslinking an elastomeric material, comprising the steps of: a) providing a curable composition as defined in claim 1 in a non-cured form; b) mixing the composition with at least one elastomeric material to form a curable mixture; and c) exposing said curable mixture to conditions of heat and pressure sufficient to crosslink the elastomeric material.

14. The cured product of a curable composition according to claim 1.

15. A curable composition comprising reactive components that cure, the curable composition comprising: (i) at least one aromatic nitroso or at least one aromatic nitroso precursor compound or combinations thereof; (ii) a film former component comprising at least one non-halogenated hydroxy group-containing resin together with at least one crosslinking agent and (iii) a sulfur impregnated particulate solid which acts as a release agent for sulfur during the cure process.

16. The curable composition of claim 15 wherein the sulfur impregnated particulate solid is selected from the group consisting of: sulfur-impregnated clays, sulfur impregnated silicates, sulfur impregnated aluminates, sulfur impregnated charcoals, sulfur impregnated carbon blacks and combinations thereof.

17. The cured product of a curable composition according to claim 15.

Description

DETAILED DESCRIPTION

(1) It should be readily apparent to one of ordinary skill in the art that the examples disclosed herein below represent generalised examples only, and that other arrangements and methods capable of reproducing the invention are possible and are embraced by the present invention.

EXAMPLES

(2) Prebaking occurs when a metal part coated with a bonding agent (for example in bonding a rubber to metal assembly) is exposed to high temperatures (>160 C.) prior to vulcanization of the rubber. When the rubber to metal bonding agent contains as part of its composition a chlorinated polyolefin and in particular a chlorinated polyethylene with high chlorine content, poor bonding strengths can be observed after this prebaking process. By the inclusion of film former component of the present invention, for example, isocyanates, either free, blocked or a combination of both, epoxy resin or a phenolic resin, prebaked bond strengths are significantly increased.

(3) When chlorinated polyolefin is removed completely from the formulation, and replaced by the film former component of the invention, a robust, tack free coating may be produced. Polymers resins containing hydroxyl groups such as polyvinyl butyral and cellulose acetate butyrate have been used herein. The addition of the film former component of the present invention, to formulations containing such polymers significantly increases bond strengths.

(4) Other methods to solve the prebaked bond issues have been to completely remove or replace the chlorinated polyolefin from the system, which may lead to decreased bond performance and so the film former component of the invention provides an excellent alternative.

(5) Rubber to Metal Bond Testing

(6) Bonded parts were pulled to destruction according to WDK (Association of German Rubber Manufacturing Industry) Guideline 2000 (Assessment of Rubber to Metal Bonding Agents for NVH Applications) outlined below. To test the performance of the bonds produced by the compositions of the invention, P-25 buffer parts are used, which are part of the ASTM-D429-Method F testing procedure.

(7) Examples of compositions comprising the film former of the present invention.

Example 1

(8) TABLE-US-00001 3699-056 Input: % Nitrososilane 8 BSU 1.5 DER 669E 1.5 Silica (Cabosil TS-720) 1.5 PVB (Butvar 72A) 2 Carbon Black (HGD4S) 2.5 Ethyl acetate 83 100 Initial Strength 8.3 MPa 5 minute Pre-bake 8.8 MPa Strength Bond Testing according to WDK Standard PVB = Poly vinyl butyral BSU = N,N-bis(3-Trimethoxysilylpropyl)urea DER-669E = High mw solid epoxy resin (Dow)

Example 2

(9) TABLE-US-00002 3699-062 Input: % Nitrososilane 8 DER-669E 1.5 BSU 1.5 Silica (Cabosil TS-720) 2 PVB (Mowital B30H) 1.5 Carbon Black (HGD4S) 2.5 CXC-1612 0.1 Ethyl acetate 82.9 100 Initial Bond Strength 9.1 Mpa 5 minute Pre-bake Strength 9.2 MPa Bond Testing according to WDK Standard PVB = Poly vinyl butyral BSU = N,N-bis(3-Trimethoxysilylpropyl)urea CXC-1612 = Ammonium hexafluoroantimonate (King Industries) DER-669E = High mw solid epoxy resin (Dow)

Example 3

(10) TABLE-US-00003 3699-072 Input: % Nitrososilane 8 BSU 1.5 DER 669-E 1.5 PVB (Mowital B60HH) 2 Silica (Cabosil TS-)720 1.5 Carbon Black (HGD4S) 2.5 CXC-1612 0.01 Ethyl acetate 82.99 100 Initial Strength 8.1 MPa 5 minute Pre-bake Strength 9.8 MPa Bond Testing according to WDK Standard PVB = Poly vinyl butyral BSU = N,N-bis(3-Trimethoxysilylpropyl)urea CXC-1612 = Ammonium hexafluoroantimonate (King Industries) DER-669E = High mw solid epoxy resin (Dow)

Example 4

(11) TABLE-US-00004 3699-101 Input: % Nitrososilane 8 BSU 1.5 DER 669-E 1.5 PVB (Mowital B30H) 2 Silica (CabosilTS-720) 1.5 Carbon Black (HGD4S) 2.5 NH.sub.4 PF.sub.6 0.1 Ethyl acetate 82.9 100 Initial Strength 10.2 MPa 5 minute Pre-bake Strength 9.3 MPa Bond Testing according to WDK Standard PVB = Poly vinyl butyral BSU = N,N-bis(3-Trimethoxysilylpropyl)urea DER-669E = High mw solid epoxy resin (Dow)

Example 5

(12) TABLE-US-00005 3640-102 Input: % Nitrososilane 8 BSU 1.5 Methylon 75-108 1.5 PVB (Mowital 60T) 1 Silica (Aerosil 200) 1.5 Carbon Black (HGD4S) 2.5 NaSbF.sub.6 0.1 Ethyl acetate 63.9 Isopranol 20 100 Initial Strength 9.9 MPa 5 minute Pre-bake Strength 10.8 MPa Bond Testing according to WDK Standard PVB = Poly vinyl butyral BSU = N,N-bis(3-Trimethoxysilylpropyl)urea Methylon 75-108 = Phenol Formaldehyde Resin

(13) All parts are % weight by weight of the composition. *All parts are parts by weight

Example 6

(14) TABLE-US-00006 3729-24 Input: % Ethyl acetate 56.7 IPA 20 DNB (30% wt. soln. in xylene) 16.7 Carbon Black (HGD4S) 2.5 Methylon 75108 1.5 Silica (Aerosil 200) 1.5 PVB (Mowital 60T) 1 NaSbF6 0.1 100 Initial Strength 5.7 MPa 5 minute Pre-bake Strength 6.1 MPa Bond Testing according to WDK Standard PVB = Poly vinyl butyral

Example 7

(15) TABLE-US-00007 3634-9 Input: % Xylene 70 HPE1305 10 Ethyl Acetate 8 Nitrososilane 8 Carbon Black (CK3) 2.5 BSU 1.5 100 Initial Strength 2.2 MPa 5 minute Pre-bake Strength 1.5 MPa HPE1305 = Chlorinated Polyethylene

Example 8

(16) With polyvinyl butyral: General improvement in bond strengths by the inclusion of an isocyanate

(17) TABLE-US-00008 3705-26 % % Input: A B Nitrososilane 8 8 BSU 1.5 1.5 Carbon Black (HGD4S) 2.5 2.5 Silica (Cabosil TS-720) 1.5 1.5 PVB (Mowital B60HH) 2 2 Desmodur XP2714 0 2 Ethyl Acetate 84.5 82.5 100 100 Initial Strength 5.1 MPa 7.2 MPa 5 minute Pre-bake Strength 7.6 MPa 9.5 MPa Bond Testing according to WDK Standard PVB = Poly vinyl butyral BSU = N,N-bis(3-Trimethoxysilylpropyl)urea

Example 9

(18) With cellulose acetate butyrate: General improvement in bond strengths by the inclusion of an isocyanate.

(19) TABLE-US-00009 3705-43 % % Input: A B Nitrososilane 8.0 8.0 BSU 1.5 1.5 Carbon Black (HGD4S) 2.5 2.5 Silica (Aerosil 200) 1.5 1.5 CAB 381-20 2.0 2.0 Desmodur XP2714 0.0 2.0 Ethyl Acetate 19.5 24.2 Xylene 65.0 58.3 100.0 100.0 Initial Strength 4.4 MPa 9.1 MPa 5 minute Pre-bake Strength 6.5 MPa 9.3 MPa Bond Testing according to WDK Standard PVB = Poly vinyl butyral BSU = N,N-bis(3-Trimethoxysilylpropyl)urea CAB = Cellulose Acetate Butyrate

(20) Addition of isocyanates (such as Desmodur XP2714 to formulations of a rubber to metal bonding agent that contains 1) a hydroxyl functional polymer such as Mowital B60HH or Eastman CAB 381-20 (PCAB) 2) the nitrososilane molecule defined herein (and see WO2009/118255) significantly increases bond performance, by crosslinking as shown in Examples 8&9
Components Used
Polyisocyanate

(21) Description: Silane functional polyisocyanate with allophanate structure based on hexamethylene diisocyanate; Form: 100% solids; NCO content: approx 16%. Desmodur XP2714:Supplied from Bayer Material Science

(22) Cellulose Acetate Butyrate Polymer

(23) Cellulose acetate butyrate polymer used in the present invention contains: Hydroxyl content0.5-5 wt %, Acetyl content1-30, Butyryl content15-65 wt %. A preferred grade, CAB381-20, is supplied by Eastman.

(24) Poly Vinyl Butyral (PVB) Polymer

(25) Average molar mass of PVB polymers: 12,000-100,000. Suitable PVB grades include:

(26) TABLE-US-00010 Content of polyvinyl Content of polyvinyl Grade alcohol .sup.1) acetate .sup.2) Mowital B 16 H 18-21 1-4 Mowital B B20 H 18-21 1-4 Mowital B 30 T 24-27 1-4 Mowital B 30 H 18-21 1-4 Mowital B 30 HH 11-14 1-4 Mowital B 45 M 21-24 1-4 Mowital B 45 H 18-21 1-4 Mowital B 60 T 24-27 1-4 Mowital B 60 H 18-21 1-4 Mowital B 60 HH 12-16 1-4 Mowital B 75 H 18-21 0-4 .sup.1) Hydroxyl groups in terms of polyvinyl alcohol .sup.2) Acetyl groups in terms of polyvinyl acetate

(27) A number of preferred grades of PVB is supplied by Kuraray. One example of a preferred grade of PVB suitable for use in the compositions of the present invention, contains as co-polymers: Polyvinyl Alcohol content: 12-16% and Polyvinyl Acetate content: 1-4%.

(28) Sulfur Impregnated Particulate Solids & Testing

(29) The sulfur impregnated particulate solid that can be used are sulfur impregnated powered activated carbons or sulfur impregnated powered charcoals.

(30) A first example of a suitable material is Desorex DY 700 S (Donau Carbon). This is a steam activated powdered carbon, based on selected grades of coal. The activated carbon is impregnated with sulfur in a special, thermal production process and has a good adsorption capacity.

(31) TABLE-US-00011 Desorex DY 700 S Impregnation (wt %) Ca. 1 Moisture content (wt %) Iodine adsorption (mg/g) >700 Total surface area (m2/g) approx. 700 (BET-method) Granulation (%) Min. 85 (<300 mesh)

(32) A second example of a suitable material is Desorex HGC 816 S, which is a granular S impregnated activated carbon which is based on coconut shells. The material can be used for the removal of mercury from flue gas, natural gas or other waste gases.

(33) TABLE-US-00012 Desorex HGC 8 16 S Specifications: Impregnation (wt %) approx. 10 Bulk density (kg/m.sup.3) 500 30 Moisture content (wt %) <10 (as packed) Granulation (mesh) 8 16 Product data before impregnation: Total surface area (m.sup.2/g) approx. 1000 (BET-method) CTC-adsorption (wt %) >60

(34) A third example of a suitable material is Desorex HGD 4S, which is a sulfur impregnated carbon based on coal. A special thermal impregnation process guarantees a high filtration efficiency and long life time of the activated carbon. Desorex HGD 4S is produced, based on a high activated carbon and has a high adsorption capacity for mercury as well as for organic impurities.

(35) TABLE-US-00013 Desorex HGD 4 S Specifications: Impregnation (wt %) min. 10 Bulk density (kg/m.sup.3) 560 30 Moisture content (wt %) <10 (as packed) pH - value approx. 3 Diameter of particles (mm) approx. 4 Product data before impregnation: Total surface area (m.sup.2/g) 1000 (BET-method) Iodine adsorption (mg/g 950 CTC-adsorption (wt %) >60

(36) CK3 (CAS RN 1333-86-4), is a carbon black for application which is used as a reinforcing filler in rubber compounds. The CK 3 used herein is an industrially produced carbon black. CK 3 is a gas black which imparts considerable scorch safety to rubber compounds by delaying the onset of cure.

(37) TABLE-US-00014 CK 3 (Carbon Black) Specifications: CTAB surface m.sup.2/g 88 ASTM area D 3765 Tint strength % 116 ASTM (IRB = 100) D 3265 OAN ml/100 g 104 ASTM D 2414 pH value 3.5 ISO 787/9 Ash content % 0.05 ASTM D 1506 Heating loss % 1.5 ASTM at packing D 1509 Sieve residue ppm 10 ASTM 325 mesh D 1514 Pour density g/dm.sup.3 350 ASTM D 1513

(38) The BET surface area of the Desorex and CK3 grades are: Desorex HGC 816S=total surface area before impregnation with sulfur approx 1000 m.sup.2/g (from TDS); Desorex HGD-4S=total surface area before impregnation with sulfur 1000 m.sup.2/g (from TDS); Desorex DY700S=approx 700 m.sup.2/g (from TDS); Carbopal MB4S(Sulfur free activated carbon for control experiments)=900 m.sup.2/g (from TDS); and CK3=88 m.sup.2/g (from TDS via the CTAB test method, which has been superseded by the BET ASTM test).

(39) Examples of the sulfur impregnated carbon compared to a standard carbon black particle (CK3).

(40) TABLE-US-00015 Different carbons A B C D Nitrososilane 8 8 8 8 Ethyl acetate 8 8 8 8 BSU 0.3 0.3 0.3 0.3 Glymo 0.9 0.9 0.9 0.9 Superchlon HE1200 10 10 10 10 CK3 2.5 0 0 0 Desorex HGC 0 2.5 0 0 Desorex HGD-4S 0 0 2.5 0 Desorex DY700S 0 0 0 2.5 Xylene 70.3 70.3 70.3 70.3 initial 8.1 8.4 9.5 10.8 steam 5 9.5 9.1 8.5

(41) Examples of different grades of chlorinated polymers with a sulfur impregnated carbon. The grades HPE1515, Superchlon HE1200 and HPE2200H all contain >65% chlorine content. The molecular weights are between 50 and 150,000 g/mol.

(42) TABLE-US-00016 Different chlorinated polymers with a Sulfur impregnated carbon F G H Nitrososilane 8 8 8 Ethyl acetate 8 8 8 BSU 0.3 0.3 0.3 Glymo 0.9 0.9 0.9 Superchlon HE1200 10 0 0 HPE1515 0 10 0 HPE2200H 0 0 10 Desorex HGC 8 16 s 2.5 2.5 2.5 Xylene 70.3 70.3 70.3 initial 8.4 8.7 6.8 steam 9.5 3.9 5.5

CONCLUSION

(43) The bond strength results indicate that use of curable compositions comprising the film former component of the present invention, that is a non-halogenated hydroxylated resin and a suitable crosslinking agent, in combination with a nitroso-containing material, shows a demonstrable increase in bond performance in both initial and 5-minute pre-bake testing. In particular the pre-bake results demonstrate superior performance of the film former system of the invention. The robustness of this film former in curable compositions means the compositions can be applied to a substrate prior to transport or storage so that they are ready to use as requires and do not display any reduced bond quality on cure.

(44) As described above, the film former of the invention has tailorable properties depending on the nature of the non-halogenated hydroxylated resin and a suitable crosslinking agent chosen for a given application, cure and operating conditions.

(45) Inclusion of a sulfur impregnated particulate solid into these compositions is advantageous from the point of view that increase bond durability and resistance is improved post cure.