GB2599165A

GB2599165A - Hybrid epoxy composition

Info

Publication number: GB2599165A
Application number: GB2015388.8A
Authority: GB
Inventors: P Tully Raymond; Burns Barry; Ward Emer; Duffy Cormac; Coleman Deborah; Bergin Niamh; Kudreviciute Egle
Original assignee: Henkel IP and Holding GmbH
Current assignee: Henkel IP and Holding GmbH
Priority date: 2020-09-29
Filing date: 2020-09-29
Publication date: 2022-03-30
Anticipated expiration: 2040-09-29
Also published as: GB202015388D0; GB2599165B

Abstract

A curable composition comprises a curable epoxy component, a heat-activated curing agent, 10-15 wt.% phenol-terminated polyurethane component, and 10-15 wt.% (meth)acrylate component. When cured, the composition has an elastic modulus of 300-900 MPa and a tensile lap shear strength >20 MPa. The weight ratio of the polyurethane and (meth)acrylate components is preferably 1:1. The epoxy component may be present in an amount of 20-80 wt.%, particularly 35-65 wt.%. The curing agent may be present in an amount of 0.25-2.0 wt.% and may be activatable at 150-200ºC. Typically, the curing agent is a urea, e.g. 1,1’-(4-methyl-m-phenylene)bis(3,3’-dimethylurea). The (meth)acrylate component may be an epoxy (meth)acrylate, urethane (meth)acrylate, ester (meth)acrylate, or melamine (meth)acrylate. Preferably, the composition is free from peroxide. A method of bonding a joint between male and female mating parts using the composition is disclosed, wherein the difference between the thermal expansion coefficients of the male and female parts is preferably >5x10-6 m/m.ºC.

Description

HYBRID EPDXY COMPOSITION

BACKGROUND

Field

[0001] The present invention relates to the combination of (i) (meth)acrylate modified polyurethane with (ii) phenol based epoxy materials which act as flexibilisers. When these components are together they form a hybrid composition wherein when the composition is cured provides a cured composition with an elastic modulus in the range of 300 -900 MPa. The composition maintains the performance attributes associated with a structural epoxy while minimising issues arising from thermal expansion for example where there is a difference in thermal expansion. This may occur when there is a coefficient of thermal expansion mismatch, for example where two substrates have different coefficients of thermal expansion.

Brief Description of Related Technology

[0002] Epoxy adhesives are widely used in the automobile industry for many body-in-white applications. Adhesive joining techniques reduce cracks around spot welds, provide outstanding stress distribution and increase torsional stiffness and fatigue strength over traditional body-in-white construction methods. Bonded joints are protected against corrosion caused by environmental factors. Corrosion may weaken the car body structure and adversely affect driving safety and comfort. Adhesives also offer significant weight savings leading to lower energy consumption and reduced CO2 emissions.

[0003] Bonding is highly effective when it comes to joining dissimilar materials such as various grades of steel, aluminium, magnesium and composites. Differences in the coefficient of thermal expansion (CTE) between bonded materials can lead to failure during body in white applications where the bond is exposed to high temperatures, for example oven temperatures of about 180 °C or higher. There is a need with the ever-increasing range of materials being bonded to provide high elastic modulus 1K (1K is used to denote one part compositions) compositions. One approach is to look at decreasing the elastic modulus of the cured adhesive which may offer improved CTE. Addition of components to the curable composition can lead to a reduction in the elastic modulus of the cured composition but addition of components can lead to other issues. For example addition of a component to decrease the elastic modulus of the cured composition may reduce the strength, for example the tensile lap shear strength which can be measured according to ASTM D897 or the T-peel strength which can be measured according to ASTM D1876. The addition of a component to decrease the elastic modulus of the cured composition may also bring with it one or more of a negative impact on the corrosion resistance of the formula or decreased strength after water uptake.

[0004]W02018169609 discloses a two-component adhesive based on hybrid urethane-acrylate epoxies comprising a core/shell rubber demonstrating good T-peel strength. The adhesives are suitable for use in industry, e.g., as adhesives for transportation industry applications.

[0005] It would be beneficial to provide additional adhesives which are both strong and flexible so that an ever-increasing range of materials which may have different coefficient of expansion can be bonded.

SUMMARY

[0006] In one aspect, the present invention provides a curable composition comprising: (i)a curable epoxy component, (ii)a heat-activated curing agent, (iii)a phenol terminated polyurethane component in an amount of from about 10 wt% to about 15 wt% based on the total weight of the composition, and (iv)a (meth)acrylate component in an amount of from about 10 wtt to about 15 wt% based on the total weight of the composition, wherein when cured the cure product of the composition has an elastic modulus of from about 300 MPa to about 900 MPa as measured by ASTM 13638, and a tensile lap shear strength is above about 20 MPa as measured according to ASTM D897.

[0007] The cure product of the composition has an elastic modulus of from about 300 MPa to about 900 MPa due to the combination of the phenol terminated polyurethane component and the (meth)acrylate component. The combination of the phenol terminated polyurethane component and the (med0acrylate component provide the cure product with flexibility.

[0008] Beneficially the cure product of the invention has an elastic modulus of from about 300 MPa to about 900 MPa as measured by ASTM D638. An elastic modulus in the range of from about 300 MPa to about 900 MPa allows the cure product sufficient flexibility to retain a bond between two substrates which react differently when placed under stress, for example with differing co-efficient of expansion when placed under heat stress.

[0009] Beneficially the cure product of the composition has a tensile lap shear strength above about 20 MPa as measured according to ASTM D897. A tensile lap shear strength above about 20 MPa provides the cure product of the composition sufficient strength to form a stable bond between two materials.

[0010] For example to bond two substrates the composition of the invention may be applied to a first surface of a first substrate and the first surface may be brought into contact with a second surface (fur example of a second substrate) to form a bond assembly. The substrates may have different coefficients of expansion. The bond assembly can be heated to cure the composition. The cure product of the composition will form a bond joining the two substrates. As the bond assembly cools the substrates with different coefficients of expansion will shrink at different rates and by different amounts. A cure product of the composition of the invention has sufficient flexibility, an elastic modulus from about 300 MPa to about 900 MPa as measured by ASTM D638, to maintain the bond integrity between the two substrates when exposed to the forces created by the different coefficients of expansion of the two substrates as they cool. That is the cure product of the composition of the invention if flexible enough to maintain a bond while the bond assembly cools. Beneficially the flexible cure product of the composition of the invention also has the required strength, above about 20 MPa as measured according to ASTM D897, to provide structural integrity to the bond assembly. The cure product of the composition is both flexible and strong.

[0011] The composition of the invention comprises a phenol terminated polyurethane component in an amount of from about 10 wt, to about 15 wtc, based on the total weight of the composition. The composition of the invention may comprise the phenol terminated polyurethane in an amount of from about 10 wt% to about 12 wtc based on the total weight of the composition. When over 15 wtn of the phenol terminated polyurethane component is present the cure product of the composition may not achieve a tensile lap shear strength above about 20 MPa as measured according to ASTM 1D897.

[0012] The composition of the invention comprises a (meth)acrylate component in an amount of from about 10 wt to about 15 wtu based on the total weight of the composition. The composition of the invention may comprise the (meth)acrylate component in an amount of from about 10 wtp to about 12 wt.' of based on the total weight of the composition. When over 15 wtr of the (meth)acrylate component is present the cure product of the composition may have a T-peel strength below about 10 N/mm as measured according to ASTM D1876.

[0013] The phenol terminated polyurethane component and (meth)acrylate components of the composition of the invention may be present in about a 1:1 weight ratio. A ratio of about 1:1 provides the cure product of the composition with flexibility and strength.

[0014] The cure product of the composition has an elastic modulus of from about 300 MPa to about 900 MPa as measured by ASTM 5638. The cure product of the composition of the invention may have an elastic modulus of from about 500 MPa to about 900 MPa as measured by ASTM 5638. Beneficially the cure product of the composition having an elastic modulus below 900 MPa means the cure product is sufficiently flexible to be used to bond two substrates which have different coefficients of expansion. For example the cure product has the flexibility to bond substrates wherein the difference of the coefficient of thermal expansion between the substrates is greater than about 5 x 10-6m/m.°C.

[0015] The cure product of the composition of the invention may have a T-peel strength is above about 10 N/mm as measured according to ASTM 51876. Beneficially a T-peel strength above 10 N/ mm means that the cure product of the composition has the requisite strength to maintain a bond between two substrates. [0016] The cure product of the composition of the invention may have a corrosion resistance greater than about 60(.;. The cure product of the composition may have a corrosion resistance greater than about 60% due to the combination of the phenol terminated polyurethane component and the (me:_h)acrylate component. A corrosion resistance of greater than about 60% means that the cure product retains sufficient strength when corroded. Corrosion resistance above 60% is required as when the cure product is exposed to natural weathering, for example when the cure product is used to bond parts of an automobile, the cure product retains sufficient strength even when corroded.

[0017] The cure product of the composition of the invention may have a water uptake of greater than about 85(1,. The cure product of the composition may have a water uptake of greater than about 855 due to the combination of the phenol terminated polyurethane component and the (meth)acrylate component. A water uptake of greater than 85 means that the composition cures to sufficient strength even after the composition has aged in humid conditions. For example in the manufacture of an automobile the composition may be applied to a part and the part may be stored in relatively humid conditions before it is bonded to another part by curing the composition of the invention. A water uptake of greater than 85% means that the composition after aging in humid conditions cures to provide a cure product which has at least 85-(= the strength of a cure product which is not aged in humid conditions.

[0018] The composition of the invention may comprise the curable epoxy component in an amount of from about 20 wt to about 80 wtu, for example from about 35 wt' to about 65 wtu, based on the total weight of the composition.

[0019] The heat-activated curing agent of the composition of the invention may be a urea, for example a substituted urea. The heat-activated curing agent may cure the composition of the invention when the composition is heated to above 150 °C. The heat-activated curing agent of the composition of the invention may be activatable from a temperature of about 150 °C to about 200 °C.

[0020] The heat-activated curing agent of the composition of the invention may be present in an amount of from about 0.25 wt to about 2.0 wt', for example 0.25 wtu to about 1.5 wt %, based on the total weight of the composition.

[0021] The heat-activated curing agent of the composition of the invention may be 1,1'-(4-methyl-m-phenylene)bis(3,3T-dlmethylurea).

[0022] The (meth)acrylate component of the composition of the invention may be chosen from the group of epoxy (meth)acrylate, urethane (meth)acrylate, ester (meth)acrylate, and melamine (meth)acrylate.

[0023] The composition of the invention may be free from peroxide. Peroxide is commonly used in compositions which comprise a (meth)acrylate to aid the cure of the composition. In the present composition the inclusion of a peroxide may lead to a reduction in T-peel strength and tensile lap shear strength [0024] In another embodiment the invention relates to a cure product formed by curing the composition of the invention.

[0025] In another embodiment the invention relates to a method of bonding a joint between a male mating part and a female mating part comprising: (i)providing a curable composition according to the invention; (ii)applying the composition to at least one mating part; (iii)joining the mating parts so as to form a joint between the male and female mating parts; (iv)curing the composition so that the male and female parts are bonded by a cure product formed by curing the composition of the invention.

[0026] Curing the composition of the invention during the method of the invention may be performed at a temperature of about 150 °C or greater.

[0027] The method of bonding a joint according to the invention may be performed wherein the difference between the coefficient of thermal expansion between the male and female part is greater than about 5 x 10-m/m-°C. For example when the male and female parts are heated to cure the composition the composition of the invention is sufficiently flexible to bond these parts even though they will expand by different amounts.

[0028] In another embodiment the invention relates to the use of a composition according to the invention for bonding a joint between male and female parts, wherein the difference between the coefficient of thermal expansion between the male and female parts is greater than about 5 x 10-6m/m.°C.

[0029] In another embodiment of the invention a bonded assembly comprising a male mating part and a female mating part bonded together by a cure product formed by curing the composition of the invention.

EXAMPLES

[0030]An example of a composition that may be considered a basis for a curable composition of the invention are given below in table 1: Table 1 Component Range (wt 4 based Preferred Range (wt on total % based on total composition weight) composition weight) Curable epoxy 20 -80 35 - 62.5 component Phenol terminated 10 -15 10 - 12 polyurethane (Meth)acrylate component 10 -15 10 - 12 Heat activated 0.25 - 2.0 0.25 - 1.5 curing agent Preparation [0031] The raw materials are formulated together in the amounts as shown in tables 2 to 5. The amounts shown are as a weight % based on the total weight of the composition.

[0032] The following compositions were prepared wherein the curable epoxy component was a blend of KANE-ACE MX 154 available from KANEKA and EPON 828 available from HEXION. The heat-activated curing agent was DYHARD UR700 available from ALZCHEM. All samples were cured at 180 °C for 30 minutes.

Testing [0033] T-Peel testing was carried out according to ASTM D1876 with a bond gap of 300 microns. The substrate was grit blasted mild steel.

[0034] Tensile lap shear strength testing was carried out according to ASTM 5897 with a bond gap of 300 microns. The substrate was grit blasted mild steel.

[0035] Corrosion resistance testing was carried out by determining tensile lap shear strength according to ASTM D897 with a bond gap of 300 microns. The substrate was grit blasted mild steel. The specimen was then aged by submerging the specimen in aqueous 5% sodium chloride 3 70 °C for 1 week. The tensile lap shear strength as tested according to ASTM D897 with a bond gap of 300 microns. The corrosion resistance is the tensile lap shear strength after aging as a percentage of the tensile lap shear strength before aging.

[0036] The water uptake is the tensile lap shear strength after aging as a percentage of the tensile lap shear strength before aging. To determine the tensile lap shear strength before ageing a bead of the composition is placed on a first joint lap of grit blasted mild steel. The first lap is then mated with a second lap of grit blasted mild steel and cured. The tensile lap shear strength was tested according to ASTM 5897 with a bond gap of 300 microns to determine the tensile lap shear strength before aging. To determine the tensile lap shear strength after aging a bead of the composition on a first joint lap of grit blasted mild steel. The joint lap and composition is aged in a humidity chamber @ 23 °C and 80'3 relative humidity for 3 days. The lap is then mated with a second lap of grit blasted mild steel and cured. The tensile lap shear strength was tested according to ASTM D897 with a bond gap of 300 microns to determine the tensile lap shear strength after aging. The water uptake is the tensile lap shear strength after aging as a percentage of the tensile lap shear strength before aging.

[0037] The modulus of elasticity (elastic modulus or modulus) was measured using ASTM 5638 with a pull speed of 10 mm per minute.

Table 2a

2 3 4 5 6 7 8 Ka neka MX 154 59.5 59.5 59.5 59.5 59.5 59.5 59.5 59.5 Egon 328 12.2 12.2 12.2 12.2 12.2 12.2 12.2 12.2 DICY 4 4 4 4 4 4 4 4 Dyhard UR 700 1 1 1 1 1 1 1 1 CN 153 CN 159 CN 9276 CN 9012 CN 9631380 Flex 111 20 Photomer 6008 20 Epon 8111 SR 351 Flex IV 20 UrtiVar UVP 5187 20 CN 975 Adeka 9061 20 UVP6565 20 UVP5150 20 Silica 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3 T-peels GBMS (N/mrn) 20 20.9 21.4 18.9 23.1 21.8 19.1 21.7 Tensile GBMS 33.1 31.8 39.8 39.6 41.9 32.9 31.9 42.8 Corrosion Resistance -GBMS(MPa) 25 18.2 27.9 28.7 30 20.5 20.8 30.1 Corrossion Resistance -% Retention 75 57 7C 72 72 62 65 70 Water uptake -GBMS(MPa) 33.9 30.8 39 39.1 44.1 33.2 33.1 40.6 Water uptake -% Retention 102 97 98 99 105 101 104 95 Modulus -MPa 1368 586 1268 1288 1592 1171 1083 1518

Table 2b

9 10 11 12 13 14 15 16 Ka neka MX 154 59.5 59.5 59.5 59.5 59.5 59.5 59.5 59.5 [pen 328 12.2 12.2 12.2 12.2 12.2 12.2 12.2 12.2 DICY 4 4 4 4 4 4 4 4 Dyhard UR 700 CN 153 20 CN 159 20 04 9276 20 04 9012 20 CN 9631380 20 Flex 111 Photomer 6008 Epon 8111 20 SR 351 20 Flex IV Univar UVP 5187 CN 975 20 Adeka 9061 UVP6565 UVP6150 Silica 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3 T-peels GI3M5 (N/mm) 19.9 18.5 17.7 20.8 20.9 19.4 19.4 19.5 Tensile GBMS 41.8 34.1 38 42 39.5 42.4 40.1 41 Corrosion Resistance -GBMS(MPa) 26.5 24-7 25 27-7 285 29-7 28-3 29-6 Corrossion Resistance -% Retention 64 72 66 66 72 70 71 72 Water uptake -CMS (MPa) 39-1 38-9 33.5 42-8 40-2 445 40_S 41-S Water uptake -% Retention 93 114 101 102 102 106 102 101 Modulus -MPa 1460 1476 1392 1438 1411 1423 1534 1460 [0038] Composition 1 is a basic epoxy composition which comprises curable epoxy components and a heat activated curing agent but does not comprise a phenol terminated polyurethane component or a (meth)acrylate component to provide flexibility to the composition. While composition 1 when cured has acceptable T-Peel, tensile lap shear strength, corrosion resistance and water uptake results the modulus of composition 1 is too high which may lead to bond failure if applied to bond two materials with different coefficients of expansion. Composition 2 is a basic epoxy composition which comprises a modified polyurethane resin (ADEKA 9061) which acts to flexiblise the composition. The addition of the polyurethane to the composition reduced modulus but negatively impacted the corrosion resistance of the composition. Compositions to 16 comprise the basic epoxy composition of composition 1 in addition to various (meth)acrylate components. The addition of the various (meth)acrylate components to the system had different effects on the system but none was capable for providing a composition with a modulus below 900 MPa while maintaining the requisite T-peel and tensile lap shear strength, corrosion resistance and water uptake.

Table 3

17 18 19 20 21 22 Kaneka MX 154 59.5 59.5 59.5 59.5 59.5 59.5 Epon 328 13.2 13.2 13.2 13.2 13.2 13.2 DICY 35 3.5 3.5 3.5 3.5 3.5 Dvhard UR 700 0.5 0.5 0.5 0.5 0.5 0.5 Calcium Oxide 2.5 2.5 2.5 2.5 2.5 2.5 Casiflux G20 16 16 16 16 16 16 Sylothix 53 0.3 0.3 0.3 0.3 0.3 0.3 Scotchlite VC 5500 2 2 2 2 2 2 CN 9012 20 Flex IV 20 UnivarUVP 5187 20 CN 975 20 Adeka 9061 20 T-peels GBMS (N/mm) 18.8 22 20.9 21.7 15.4 21.2 Tensile GBMS 34.2 31.3 38.6 40.4 35.9 31.9 Corrosion Resistance -GBMS (MPa) 24.1 18.3 27.8 30.8 27.4 23.1 Corrossion Resistance -% Retention 70 58 72 76 76 72 Water uptake -GBMS(MPa) 33.5 31.3 35.4 31.5 30.1 33.4 Water uptake -% Retention 98 100 92 78 84 105 Modulus -MPa 2091 786 1354 1206 1301 1018 [0039] Compositions 17 to 22 were prepared with the formulations as per table 3 to determine the effect of various (meth)acrylate components in a typical epoxy composition comprising a range of fillers and thixotropic agents. Flexibiliser DY 965 is a phenol terminated polyurethane adduct, Univar UVP 5187 is a flexible epoxy Novolac acrylate in 20% propoxylated glycerol triacrylate, CN9012 from SARTOMER is an aliphatic urethane diacrylate, CN975 is a hexafunctional aromatic urethane acrylate oligomer, Flex IV is the reaction product of a flexible methylene ether diol reacted with a molar excess of toluene diisocyanate and then end-capped with hydroxyethylmethacrylate. Composition 17 which did not contain any (meth)acrylates to flexibilise the cure product and had a modulus of 2091 MPa. The addition of the various (meth)acrylates made the compositions 18 to 22 more flexible but none of the compositions had a modulus below 900 MPa while maintaining the requisite T-peel and tensile lap shear strength, corrosion resistance and water uptake. For example composition 18, while exhibiting a modulus of 786 MPa did not show-adequate water uptake strength retention.

Table 4a

23 24 25 26 27 Kaneka MX 154 45 45 45 45 45 Epon 328 30 10 10 DICY 3.5 3.5 3.5 3.5 3.5 Dyhard UR 700 0.5 0.5 0.5 0.5 0.5 Calcium Oxide 3 3 3 3 3 Casiflux G20 10 10 10 10 10 Nipol 1411 1.2 1.2 1.2 1.2 1.2 Sylothix 53 0.3 0.3 0.3 0.3 0.3 Scotchlite VC 5500 4 4 4 4 4 Caloosil T5720 1 1 1 1 1 Adeka EP49-10P2 1.25 1.25 1.25 1.25 1.25 Glymo 0.25 0.25 0.25 0.25 0.25 Flexibilizer DY965 20 30 Flex IV 20 30 t-Bu Peroxybenzoate T-peels GBMS (N/mm) 16.9 20.4 17 20.3 0.6 Tensile GBMS 31.6 24.9 27.5 19.7 10.4 Corrosion Resistance -GBMS(MPa) 29.7 19.8 19.6 9.8 8.9 Corrossion Resistance -% Retention 94 79 71 50 85 Water uptake -GBMS (MPa) 26.2 23.5 25.4 14.8 11.1 Water uptake -% Retention 83 95 92 75 107 Modulus -MPa 1749 975 997 936 533

Table 4b

28 29 30 31 32 Kaneka MX 154 45 45 45 45 45 Epon 328 10 DICY 3.5 3.5 3.5 3.5 3.5 Dyhard UR 700 0.5 0.5 0.5 0.5 0.5 Ca lcium Oxide 3 3 3 3 3 Casiflux G20 10 10 10 10 10 Nipol 1411 1.2 1.2 1.2 1.2 1.2 Sylothix 53 0.3 0.3 0.3 0.3 0.3 Scotchlite VC5500 4 4 4 4 4 Ca bosil 15720 1 1 1 1 1 Adeka EP49-10P2 1.25 1.25 1.25 1.25 1.25 Glymo 0.25 0.25 0.25 0.25 0.25 Flexibilizer DY 965 10 10 20 15 10 Flex IV 10 20 10 15 20 t-Bu Peroxybenzoate 0.25 1-peels GBMS (N/mm) 19.2 3.5 13.5 12.2 5.7 Tensile GEINIS 28.6 16.7 19.2 20.3 17.6 Corrosion Resistance -GBNIS (MPa) 19.3 9.1 9.4 10.1 9.3 Corrossion Resistance -% Retention 68 54 49 50 53 Water uptake -GSM'S (MPa) 24.8 14.7 15.4 18.1 15.2 Water uptake -% Retention 86 88 80 89 87 Modulus -MPa 837 410 380 762 387 [0040] Compositions 23 to 32 were prepared with the formulations as per table 4a and 4b to determine the effect of increasing the amounts of flexibilising components in the compositions. Composition 23 contains no phenol terminated polyurethane component or (meth)acrylate component to flexibilise the cure product and the cure product has a modulus of 1749 MPa. Composition 24 shows the addition of 20 wt% of phenol terminated polyurethane (Flexibliser DI 965) did not reduce the modulus to below 900 MPa. Increasing the amount of phenol terminated polyurethane to 30 wt% in composition 26 decreased the modulus to below 900 MPa but reduced the corrosion resistance retention to below an acceptable level. Composition 25 shows the addition of 20 wt?, (meth)acrylate (Flex IV) did not reduce the modulus to the below 900 MPa. Increasing the amount of (meth)acrylate to 30 wt%, in composition 27 reduced the modulus to below 900 MPa but the composition lacked sufficient strength even before corrosion resistance or water uptake testing.

[0041] Composition 28 comprises a flexibilising component comprising a phenol terminated polyurethane and a (meth)acrylate component wherein the phenol terminated polyurethane and (meth)acrylate components are present in about a 1:1 weight ratio. The cure product of composition 28 provided excellent strengths, corrosion and water uptake strength retention and modulus.

[0042] Compositions 29 to 32 wherein the flexibilising component is present at 30 wt-'_ do not provide cure products with the required strengths, corrosion and water uptake strength retention and modulus. The addition of a peroxybenzoate cure accelerator in composition 32 did not improve the characteristics of the cure product.

Table 3

33 34 35 36 37 38 39 40 Ka ne ka MX 154 47 47 47 47 47 47 47 47 Epon 328 5 5 5 5 5 5 5 5 ['ICY 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Dyhard UR 700 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.75 Calcium Oxide 2 2 2 2 2 2 2 2 CasifluxG2O 10.8 10.8 10.8 10.8 10.8 10.8 10.8 10.8 Nigel 1411 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Sylothlx 53 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Scotch lite VC 5500 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 Cabosil T5720 2 2 2 2 2 2 2 2 Adeka EP49-10P2 1 1 1 1 1 1 1 1 Glymo 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Flexibilizer DV 965 12 12 12 12 12 12 12 12 CN 153 12 CN 9276 12 CN 9012 12 CN 963880 12 CN 2560 Flex 111 12 Photomer 6008 12 Epon 8111 SR 351 12 Flex IV 12 T-peels GBMS (N/mrn) 15.3 14 11.8 12.4 14.3 11.8 11.3 22 Tensile GBMS 30.2 28.4 28 27 24.7 29 26.6 25.1 Corrosion Resistance -GBMS (MPa) 20.7 21.1 18.8 18.3 15.8 20 20.5 15.3 Corrossion Resistance -% Retention 69 74 67 68 64 69 77 61 Water uptake -GBMS (MPa) 30.7 28.3 28.3 29.2 25.5 29.2 25.2 22.6 Water uptake -% Retention 102 100 101 108 103 101 95 90 Modulus -MPa 883 772 867 944 618 889 911 668 [0043] Compositions 33 to 40 were prepared with the formulations as per table 5 to determine effect of different (meth)acrylate components on the cure product of the composition. A phenol terminated polyurethane (Flexibliser DY963) and a range of (meth)acrylate components were added to add flexibility to the cure products of the compositions. The phenol terminated polyurethane and (meth)acrylate components are present in about a 1:1 weight ratio and the composition comprises less than 30 wt% flexibilising component based on the total weight of the composition. Across the range of (meth)acrylates for all compositions 33 to 40 the cure products provided excellent strengths, corrosion and water uptake strength retention and modulus.

[0044] The words "comprises/comprising" and the words "having/including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0045] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

Claims

Claims 1. A curable composition comprising: (a) a curable epoxy component, (b) a heat-activated curing agent, (c) a phenol terminated polyurethane component in an amount of from about 10 wtu to about 15 wtu based on the total weight of the composition, and (d) a (meth)acrylate component in an amount of from about 10 wt, to about 15 wt based on the total weight of the composition, wherein when cured the cure product of the composition has a modulus of from about 300 MPa to about 900 MPa as measured by ASTM D638, and a tensile lap shear strength is above about 20 MPa as measured according to ASTM D897.
2. The composition of any preceding claim wherein composition comprises the phenol terminated polyurethane in an amount of from about 10 wt to about 12 wt_ based on the total weight of the composition.
3. The composition of any preceding claim wherein the composition comprises the (meth)acrylate component in an amount of from about 10 wtu to about 12 wtu of based on the total weight of the composition.
4. The composition of any preceding claims wherein the phenol terminated polyurethane component and (meth)acrylate components are present in about a 1:1 weight ratio.
5. The composition of any preceding claim wherein the cure product has a modulus of from about 500 MPa to about 900 MPa as measured by ASTM D638.
6. The composition of any preceding claim wherein cure product has a T-peel strength is above about 10 N/mm as measured according to ASTM D1876.
7. The composition of any preceding claim wherein the cure product has a corrosion resistance was greater than about 60%.
8. The composition of any preceding claim wherein the cure product has a water uptake of greater than about 852.
9. The composition of any preceding claim wherein the curable epoxy component is present in an amount of from about 20 wt 3 to about 80 wt,, for example from about 35 wt_ to about 65 1/2-Lc, based on the total weight of the composition.
10. The composition of any preceding claim wherein the heat-activated curing agent is a urea, for example a substituted urea.
11. The composition of any preceding claim wherein the heat-activated curing agent is present in an amount of from about 0.25 wtc to about 2.0 wt', for example 0.25 wt-to about 1.5 wt', based on the total weight of the composition.
12. The composition of any preceding claim wherein the heat-activated curing agent is activatable from a temperature of about 150 °C to about 200 °C.
13. The composition of any preceding claim wherein the heat-activated curing agent is 1,1'-(4-methyl-mphenylene)bis(3,3'-dimethylurea).
14. The composition of any preceding claim wherein the (meth)acrylate component is chosen from the group of epoxy (meth)acrylate, urethane (meth)acrylate, ester (meth)acrylate, and melamine (meth)acrylate.
15. The composition of any preceding claim wherein the composition is free from peroxide.
16. A cure product formed by curing the composition according to any of claims 1 to 15.
17. A method of bonding a joint between a male mating part and a female mating part comprising: (a) providing a curable composition according to claims 1 to 15; (b) applying the composition to at least one mating part; (c) joining the mating parts so as to form a joint between the male and female mating parts; (d) curing the composition so that the male and female parts are bonded by the cure product according to claim 16.
18. The method of bonding a joint according to claim 17 wherein the curing is performed at above about 150 °C.
19. The method of bonding a joint according to claim 17 or 18 wherein the difference between the coefficient of thermal expansion between the male and female part is greater than about 5 x 10-6m/m-°C.
20. The use of a composition according to claims 1 to 15 for bonding a joint between male and female parts, wherein the difference between the coefficient of thermal expansion between the male and female parts is greater than about 5 x 10-6m/m.°C.
21. A bonded assembly comprising a male mating part and a female mating part bonded together by the cure product according to claim 16.