Water-based adhesive consisting of dispersed polymer and emulsified silicone resin polymer

Abstract

A water-based adhesive which comprises a dispersed polymer and an emulsified silicone resin polymer. The adhesive is postcrosslinkable via reactive groups.

Claims

1. A water-based adhesive comprising: a dispersed thermoplastic polymer, and an emulsified silicone resin polymer, wherein the adhesive is postcrosslinkable via reactive groups at temperatures between 100° C. and 300° C., wherein a solids content is above 50% by weight.

2. The adhesive according to claim 1, wherein the adhesive is a one-component system.

3. The adhesive according to claim 1, wherein the thermoplastic polymer has polar groups.

4. The adhesive according to claim 1, wherein the silicone resin polymer is a polysiloxane having organic side groups.

5. The adhesive according to claim 1, wherein the adhesive has a pH of between 6 and 9.

6. The adhesive according to claim 1, wherein the adhesive has a viscosity of between 4, 190.883 to 120,954.416 lb/ft-h (1,000 to 50,000 mPa.Math.s).

7. A method for bonding at least two different substrates with an adhesive according to claim 1, comprising the steps of: providing at least two substrates, applying the adhesive to at least a part of the first substrate and/or of the second substrate, and joining and bonding the two substrates together.

8. The method according to claim 7, wherein the adhesive is applied by a roller, a stencil, a knife or spraying.

9. The method according to claim 7, wherein the first substrate is a metal and the second substrate is selected from the group consisting of glass fiber, silicate fiber, polyamide fiber, polyacrylonitrile fiber, carbon fiber, and any combination thereof.

10. An insulating material bonded with an adhesive according to claim 1.

11. The insulating material according to claim 10, wherein the insulating material comprises at least two bonded substrates, a first substrate being a metal and a second substrate being selected from the group consisting of glass fiber, silicate fiber, polyamide fiber, polyacrylonitrile fiber, carbon fiber, and any combination thereof.

12. The adhesive according to claim 1, wherein the adhesive is postcrosslinkable via a condensation reaction.

13. The adhesive according to claim 1, wherein the thermoplastic polymer is a copolymer or a combination of copolymers selected from the group consisting of acrylate copolymer, styrene-acrylate copolymer, ethylene-vinyl acetate copolymer, acrylate-urethane copolymer, polyurethane copolymer, and ethylene-acrylic acid copolymer.

14. The adhesive according to claim 4, wherein the organic side groups are selected from the group consisting of methyl, phenyl, alkoxy, and any combination thereof.

15. The adhesive according to claim 1, wherein the solids content is between 60% and 80% by weight.

16. The method according to claim 9, wherein the metal is aluminum.

17. The insulating material according to claim 11, wherein the metal is aluminum.

Description

EXAMPLES

(1) Various raw material compositions were tested for the preparation of the adhesive.

(2) Table 1 lists the starting raw materials with the chemical characterization.

(3) TABLE-US-00001 TABLE 1 Trade name Designation Chemical characterization (manufacturer) EAA (A)* Heat-sealable adhesive nolax S35.3110 based on aqueous ethylene- (nolax AG) acrylic acid copolymer dispersion (EAA) Si resin Aqueous Me/Ph—Si resin Silres P 50 E (containing emulsion (containing (Wacker Silicone) solvent) (B) solvent, <8% xylene), 50% solids content Si resin Aqueous Me/Ph—Si resin Silres MPF 52 E (aqueous) (C) emulsion, 50% solids (Wacker Silicone) content StyAc** (D) Aqueous styrene-acrylate Pliotec HDT 12 dispersion (StyAc) (OMNOVA Solutions) PUD*** (E) Aqueous polyurethane Neorez R-600 dispersion (PUD) (DSM Coating Resins) Filler (F) Calcined kaolin Kamin 70 (KaMin, LLC) Defoamer (G) Combination of liquid HCs, Agitan 701 silicones, oxalkylated (Münzing) compounds, modified solids, and nonionic emulsifiers. *Ethylene-acrylic acid **Styrene-acrylate ***Polyurethane dispersion HCs hydrocarbons

(4) Table 2 shows an experiment matrix of the different compositions of the starting materials, with figures in percent by weight.

(5) TABLE-US-00002 TABLE 2 (figures in % by weight) Formulation 1 2 3 4 5 6 7* 8 9 10* 11 12 13* 14* A 100 90.7 34.8 34.8 B 100 83.0 52.2 C 100 82.6 52.2 52.2 65.2 D 100 86.9 34.8 E 100 90.9 21.7 F 9.4 16.6 16.5 13.0 13.1 13.0 7.6 13.0 13.0 G 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 Thickener 0.4 1.5 Dispersant 0.4 0.5 *inventive

(6) Substrates

(7) To produce the test specimen, substrates used were as follows: isoGLAS filament fabric (Frenzelit) with a weight of 420 g/m.sup.2; aluminum foil with a thickness of 30 μm for T-peel, and with a thickness of 20 μm for media resistance.

(8) For comparison, specimens were used of an assembly composed of Isoglas glass fiber fabric with 20 μm aluminum foil and 100% silicone adhesive. In the results tables below, this assembly is designated the benchmark (BM).

(9) Production of the Test Specimen

(10) 2 pieces approximately 10 cm×12 cm in size were cut to size. The aluminum foil was cut to size in 2 pieces of approximately 13 cm×20 cm.

(11) Bonding:

(12) The formula under test was coated onto the matt side of the aluminum foil using a wire-wound coating bar, generally RDS 44, without pressure. The coat weight was around 70 g/m.sup.2. A piece of glass fiber fabric was placed lengthwise (with the reverse side downward) directly into the film while still wet; it should be ensured that approximately 2 cm of the upper margin are not in the adhesive—this makes it easier later to clamp the specimen into the tensile testing machine. The glass fabric was pressed on uniformly by hand. The test specimen was subsequently dried in an oven at 50° C. for around 20 minutes.

(13) Activation at 230° C.:

(14) Directly after drying, the test specimens were activated in a muffle furnace at 230° C. for 1 to 20 min. The test specimens were always placed into the oven with the aluminum side downward. Where possible, the adhesive strip marking ought to be removed prior to activation. The activation is necessary in order to bring about crosslinking of the adhesive system.

(15) Adhesive Before and after Heat Exposure at 90° C. (T-Peel)

(16) The T-peel test was carried out in a heating chamber at 90° C. The sample mount for the heating chamber had a spacing of 3 cm between the lower and upper jaws. The measurement length of the sample was 70 mm, the relative velocity of the jaws was 50 mm/min, and a maximum force was 100 N. Before being clamped in, the test specimens were conditioned at 90° C. for 15 minutes and subsequently at 90° C. for 2 minutes after having been clamped in. Thereafter the test specimens were exposed to a heat load of 400° C. over a period of 1 h.

(17) Table 3 summarizes the test results for the individual formulations from table 2.

(18) TABLE-US-00003 TABLE 3 Adhesive value before Adhesive value after heat heat exposure exposure, 1 h at 400° C. Formu- Average load Maximum load Average load Maximum load lation (N/2 cm) (N/2 cm) (N/2 cm) (N/2 cm) 1 0.75 1.29 0.52 1.15 2 0.68 1.25 0.82 1.55 3 <0.1 <0.1 <0.1 <0.1 4 <0.1 <0.1 <0.1 <0.1 5 <0.1 <0.1 <0.1 <0.1 6 <0.1 <0.1 <0.1 <0.1  7* 4.37 5.84 1.58 2.12 8 8.39 10.21 <0.1 <0.1 9 8.04 9.57 <0.1 <0.1 10* 3.19 4.13 0.52 1.03 11  6.35 9.00 <0.1 <0.1 12  6.58 9.11 <0.1 <0.1 13* 2.6 3.75 0.85 1.32 14* 2.07 3.26 1.33 2.07 BM Assembly not separable <0.1 <0.1 *inventive

(19) The pure aqueous silicone resin emulsions (formulations 3 and 5) exhibit poor filming and adhesive properties.

(20) The EAA adhesive (formulations 1 and 2) holds the two materials of the test specimen together, but loses adhesion after storage at elevated temperature.

(21) The inventive adhesive (formulation 7), based on formulation 1 and an aqueous silicone resin emulsion, exhibits higher adhesion values for the test specimen after heat exposure (1 h, 400° C.) than the individual substances (formulation 1, 3, 5).

(22) With the inventive adhesive composed of a styrene-acrylate copolymer and a silicone resin emulsion (formulation 10), as well, the assembly still holds together after heat exposure, whereas the individual substances (formulations 6, 8, 9) do not hold.

(23) An aqueous inventive polyurethane dispersion with silicone resin in accordance with formulation 13 likewise exhibits improved adhesion values relative to the individual constituents (formulations 11 and 12) and especially relative to the benchmark.

(24) While formulations 8 and 9 and also 11 and 12 exhibit good adhesion values prior to heat exposure, they do not withstand heat exposure.

(25) Heat Resistance to Infrared Heater

(26) To test the heat resistance, the test specimen was cut to a size of 25×25 cm. The test specimen was sprayed with a heat-resistant varnish (exhaust varnish) in the middle over a size of around 2.5×2.5 cm. The test specimen was placed on a rack. At a distance of 20 mm from the rack and from the piece of test specimen provided with heat-resistant varnish, an infrared source was located. The infrared heater used was a Krelus IR heater. The test specimen was irradiated at a temperature of 459° C. for 2 h.

(27) Table 4 summarizes the results of the testing of the heat resistance using an infrared heater.

(28) TABLE-US-00004 TABLE 4 Formulation Assessment 1 delaminated after just 5 min 2 no self-delamination after 2 h at 459° C.  7* no self-delamination after 2 h at 459° C. 10* no self-delamination after 2 h at 459° C. 13* no self-delamination after 2 h at 459° C. 14* no self-delamination after 2 h at 459° C. BM delaminated after 10 min *inventive

(29) Since the test specimens with an aqueous silicone resin emulsion (formulations 3 and 6) according to table 3 already failed to exhibit any adhesive strength under heat, it was not possible to test the heat resistance of the corresponding test specimen. The test specimens with formulations 8 and 9 and also the shaped articles comprising polyurethane dispersions (formulations 11 and 12, table 3) are also not heat-resistant.

(30) The test specimen with an EAA adhesive (formulation 1) delaminates after just 5 min, and therefore has only very little or no heat resistance.

(31) The test specimens with the inventive adhesive (formulations 7, 10, and 13) did not exhibit self-delamination even after 2 h at 459° C. Delamination or self-delamination here means that the individual substrates of the test specimen part from one another.

(32) A test specimen with the inventive adhesive 14 additionally comprises solvent. A test specimen of this kind likewise exhibits no self-delamination. In the dried and activated state, formulation 14 is substantially free of solvent. However, the presence of traces of the solvent in the ppm range cannot be ruled out.

(33) Heat Resistance to Thermal Oven

(34) The respective test specimen was stored freely standing on a rack in a high-temperature oven at 400° C. for 1 h.

(35) Table 5 shows the results from the heat exposure in the thermal oven.

(36) TABLE-US-00005 TABLE 5 Formulation Assessment 1 no delamination 2 no delamination  7* no delamination 8 delaminated after 5 min 9 delaminated after 5 min 10* no delamination 11  delaminated after 5 min 12  delaminated after 5 min 13* no delamination 14* no delamination BM delaminated after 10 min *inventive

(37) Test specimens with the inventive adhesives (formulations 7, 10, 13, 14) do not exhibit any delamination in the thermal oven either.

(38) Combustion Test

(39) The combustion test was carried out with a BBW kiln from Wazau, Berlin.

(40) The test specimen was cut to a size of 560 mm×160 mm and affixed to a support. The Bunsen burner was ignited and allowed to burn for at least 2 min before the start of the test. The burner was subsequently held at an angle of 30° to the test specimen, at a distance of 2 cm. The test specimen was subjected to the flame for 5 seconds horizontally (ignition test) and 15 seconds horizontally (combustibility test).

(41) The results of the combustion test for the test specimens with the individual formulations are set out in table 6.

(42) TABLE-US-00006 TABLE 6 Designation Ignition test/combustibility test 1 +/+ 2 +/+ 3 −/− (coated only on aluminum; no assembly tested) 4 −/− (coated only on aluminum; no assembly tested) 5 −/− (coated only on aluminum; no assembly tested) 6 −/− (coated only on aluminum; no assembly tested)  7* −/− 8 was not tested, since not heat-resistant 9 was not tested, since not heat-resistant 10* −/− 11  was not tested, since not heat-resistant 12  was not tested, since not heat-resistant 13* −/− 14* −/− BM +/+ *inventive − does not ignite/does not burn + ignites/forms flame

(43) The test specimen with the pure binder (formulation 1) is not fire-resistant. Conversely, the test specimens with the inventive adhesive (formulation 7, 10, and 13) are fire-resistant.

(44) Good results were also achieved with an adhesive which before drying and activation contained solvent (5.75% wet/wet, formulation 14).