ONE-COMPONENT THERMOSETTING EPOXY COMPOSITION WITH IMPROVED ADHESION

Abstract

A one-component thermosetting epoxy resin composition includes at least one epoxy resin A having on average more than one epoxide group per molecule, at least one latent hardener B for epoxy resins, at least one impact modifier D, at least one physical or chemical blowing agent E and fibrous anhydrous magnesium oxysulfate MOS. Thermally expandable epoxy resin compositions have improved adhesion, especially on metal substrates.

Claims

1. A one-component thermosetting epoxy resin composition comprising: 20-55 weight-% of at least one epoxy resin A having on average more than one epoxide group per molecule; 1-6 weight % of at least one latent hardener B for epoxy resins; 0-3 weight-% of at least one accelerator C; 10-50 weight-% of at least one impact modifier D; 0.01-5 weight-% of at least one physical or chemical blowing agent E; 2-35 weight-% of a fibrous anhydrous magnesium oxysulfate MOS; wherein the thermosetting epoxy resin composition has a needle penetration value (in 0.1 mm) of 20-80 using a total load (weight of the needle and related parts) of 100 g for 5 second with a needle thickness of 1 mm at 23° C.

2. Composition according to claim 1, wherein the latent hardener B is selected from dicyandiamide, guanamines, guanidines, aminoguanidines and derivatives thereof, substituted ureas, imidazoles and amine complexes.

3. Composition according to claim 1, wherein the at least one accelerator C is a substituted urea.

4. Composition according to claim 1, wherein the impact modifier D is selected from the group consisting of blocked polyurethane polymers D1, carboxyl-terminated acrylonitrile/butadiene copolymers D2 and liquid rubbers D4.

5. Composition according to claim 1, wherein the proportion of fibrous anhydrous magnesium oxysulfate MOS is 5-30 weight-%, 7.5-25 weight-%.

6. Composition according to claim 1, wherein the fibrous anhydrous magnesium oxysulfate MOS (MgSO.sub.4.Math.5Mg(OH).sub.2) is selected from the list consisting of MgSO.sub.4.Math.5Mg(OH).sub.2.Math.3H.sub.2O and MgSO.sub.4.Math.5Mg(OH).sub.2.Math.8H.sub.2O.

7. Composition according to claim 1, wherein the fibrous anhydrous magnesium oxysulfate MOS has a length of 3 to 1000 μm.

8. Composition according to claim 1, wherein the fibrous anhydrous magnesium oxysulfate MOS has a diameter of 0.1 to 5 μm.

9. Composition according to claim 1, wherein the thermosetting epoxy resin composition is tacky at 23° C., exerting a pressure of 5 kg for 1 second on the surface of the thermosetting epoxy resin composition, the thumb remains sticking to the surface of the thermosetting epoxy resin composition.

10. Composition according to claim 1, wherein thermosetting epoxy resin composition has a needle penetration value (in 0.1 mm) of 20-80 using a total load (weight of the needle and related parts) of 100 g for 5 second with a needle thickness of 1 mm at 23° C.

11. Article having a three-dimensional extent, comprising, the one-component thermosetting epoxy resin composition according to claim 1.

12. Article according to claim 11, wherein as strips, these articles are 20-500 mm, in length, 2-15 mm, in width and 0.5-5 mm, in thickness; and as patches, these articles are 20-500 mm in length and in width and 0.5-5 mm, in thickness.

13. Use A method for reinforcing heat-stable materials comprising: obtaining an article having a three-dimensional extent as recited in claim 11, reinforcing the heat-stable materials by applying the article to the materials.

14. Method for reinforcing a structural component comprising the steps: i) placing a one-component thermosetting epoxy resin composition according to claim 1 or an article having a three-dimensional extent, comprising, the one-component thermosetting epoxy resin composition, in a cavity of a structural component; ii) heating the one-component thermosetting epoxy resin composition or the article to a temperature from 120° C. to 220° C.

15. Article obtained by the method according to claim 14.

Description

EXAMPLES

[0142] Test methods used for the testing of the respective properties in the examples were as follows:

TABLE-US-00001 Rubber1 NBR Rubber2 SBR Liquid Epoxy Liquid epoxy resin of formula (II) Solid Epoxy Solid epoxy resin of formula (II) Carbon black Carbon black Calcium oxide Calcium oxide Stabilizer Hindered phenolic antioxidant MOS MOS-HIGE, fibrous magnesium oxysulfate [MgSO.sub.4•5Mg(OH).sub.2•3H.sub.2O], fiber length 10-20 μm, fiber diameter 0.5 μm, BET specific surface area 10 m.sup.2/g, Ube Material Industries, Ltd., Japan. Calcium Carbonate Calcium Carbonate Recycled Carbon fiber Recycled Carbon fiber Wollastnite Wollastnite BA Physical blowing agent, Expancel, Akzo Nobel, Netherlands DICY Dicyandiamide Accelerator Substituted urea Aluminium hydroxide Aluminium hydroxide D1 Terminally blocked polyurethane polymer D1 of formula (1) D2-1 Liquid CTBN D2-2 Solid CTBN Fumed Silica Fumed Silica, Wacker Raw materials used

[0143] Preparation of the Compositions

[0144] According to the information in Table 1 and 2, the reference compositions Ref.1-Ref.4 and the compositions E1-E5 according to the invention were produced. The amounts in Table 1 and 2 are in parts by weight. The raw materials used were mixed with a sigma mixer for 30 min. All the compositions Ref.1- Ref.4 and E1-5 were tacky at 23° C. according to the definition described before.

[0145] The following measurements were carried out on the test specimens obtained:

[0146] Test Methods:

[0147] Needle Penetration

[0148] Penetration depth was measured by preparing square samples of freshly mixed compositions (30 mm×30 mm×thickness 10 mm). For the measurement, a 1 mm thin needle was placed on the surface of the sample and released to penetrate the sample for 5 sec. The total load (weight of the needle and related parts) was 100 g. The penetrated depth of the needle is given in 0.1 mm. The measurements were performed at 23° C. High penetration value means low viscosity of the composition.

[0149] Determination of Foam Density/Volume Expansion (Expansion)

[0150] The expansion stability was tested in all samples by heat treatment of the individual samples at different temperatures as indicated in table 1 and table 2 in an oven. The temperatures, periods and extent of expansion (in % based on the original volume before expansion) are shown in table 1 and table 2.

[0151] Expansions were quantified for each sample by measuring the density before and after expansion. The densities were determined according to DIN EN ISO 1183 using the water immersion method (Archimedes principle) in deionized water and a precision balance to measure the mass.

[0152] Tensile Shear Strength (LSS)

[0153] The determination follows the general lines of ASTM D1002-10. The tensile shear strength was determined using the following set-up (dimensions in mm): [0154] Test temperature: 23° C. [0155] Bond area: 10 mm×20 mm [0156] Adhesive layer thickness: 0.2 mm [0157] Curing: as shown in table 1 and table 2 [0158] Test velocity: 10 mm/min

[0159] Cohesive Fracture/Adhesive Fracture (Fracture Mode)

[0160] Visual assessment of the fracture mode obtained from the tensile shear strength, divided into CF and AF. CF=cohesive fracture, AF=adhesive fracture.

TABLE-US-00002 TABLE 1 Composition Ref. 1 Ref. 2 Ref. 3 E1 E2 E3 E4 Rubber1 9 9 9 9 9 9 9 Rubber2 6 6 6 6 6 6 6 Liquid Epoxy 23.5 23.5 23.5 23.5 23.5 23.5 23.5 Solid Epoxy 23.5 23.5 23.5 23.5 23.5 23.5 23.5 Carbon black 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Calcium oxide 5 5 5 5 5 5 5 Stabilizer 0.4 0.4 0.4 0.4 0.4 0.4 0.4 MOS 27 15 5 14.8 Calcium Carbonate 27 12 22 12 Recycled Carbon fiber 27 Wollastnite 27 BA1 2.3 2.3 2.3 2.3 2.3 2.3 2.3 DICY 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Accelerator 0.2 Total 100 100 100 100 100 100 100 Volume expansion 20 min @ 180° C. 127.7 88.2 97.4 102.8 96.4 104.7 113.2 (%) Lap shear strength 10 min @ 155° C. 0.9 0.3 0.4 2.8 1.8 0.6 7.8 (MPa) 20 min @ 180° C. 3.0 3.6 5.2 9.6 8.6 4.6 7.3 Failure mode 20 min @ 180° C. 100% CF 100% AF 50% CF 50% CF 90% CF 98% CF 100% CF Penetration 83 50 62 47 64 74 63

TABLE-US-00003 TABLE 2 Composition Ref. 4 E5 D1 8.2 8.2 Liquid Epoxy 22.4 22.4 Aluminium hydroxide 14.5 14.5 D2-1 5.7 5.7 D2-2 18.5 18.5 fumed silica 6.3 6.3 Calcium oxide 2.4 2.4 Stabilizer 0.1 0.1 Calcium Carbonate 16.4 6.4 MOS 10 BA 3 3 DICY 3.1 3.1 Accelerator 0.35 0.35 Total 100 100 Volume expansion (%) 160.2 157.6 10 min @ 155° C. Volume expansion (%) 182.1 164.8 60 min @ 190° C. Lap shear strength (MPa) 3.7 9 10 min @ 155° C. Lap shear strength (MPa) 5.3 8 60 min @ 190° C. Penetration 73 44