US 11,932,786 B2
Method for structurally joining substrates having different coefficients of linear thermal expansion
Urs Rheinegger, Regensdorf (CH); Elyes Jendoubi, Suzhou (CN); Dominique Gallo, Otelfingen (CH); and Christian Krüger, Zürich (CH)
Assigned to SIKA TECHNOLOGY AG, Baar (CH)
Appl. No. 16/955,955
Filed by SIKA TECHNOLOGY AG, Baar (CH)
PCT Filed Dec. 18, 2018, PCT No. PCT/EP2018/085495
§ 371(c)(1), (2) Date Jun. 19, 2020,
PCT Pub. No. WO2019/121682, PCT Pub. Date Jun. 27, 2019.
Claims priority of application No. 17208668 (EP), filed on Dec. 19, 2017.
Prior Publication US 2020/0325368 A1, Oct. 15, 2020
Int. Cl. C09J 163/04 (2006.01); C08G 59/40 (2006.01); C09J 175/14 (2006.01); C08G 71/04 (2006.01)
CPC C09J 163/04 (2013.01) [C08G 59/40 (2013.01); C09J 175/14 (2013.01); C08G 71/04 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method of adhesive bonding of heat-stable substrates, comprising the steps of:
i) applying a one-component thermosetting epoxy resin composition to the surface of a heat-stable substrate S1;
ii) contacting the one-component thermosetting epoxy resin composition applied with a surface of a further heat-stable substrate S2, where a thickness of the one-component thermosetting epoxy resin composition applied after step ii) is ≥0.8 mm;
iii) heating the one-component thermosetting epoxy resin composition to a temperature of 100-220° C.
wherein the one-component thermosetting epoxy resin composition comprises:
a) at least one epoxy resin A having an average of more than one epoxy group per molecule;
b) at least one latent curing agent for epoxy resins B;
where a weight ratio of the at least one epoxy resin A having an average of more than one epoxy group per molecule to at least one toughness improver D is 0.3-2.2,
and wherein the at least one toughness improver D is a terminally blocked polyurethane prepolymer of the formula (I):

OG Complex Work Unit Chemistry
where R1 is a p-valent radical of a linear or branched polyurethane prepolymer terminated by isocyanate groups after removal of terminal isocyanate groups;
p has a value of 2 to 8; and
R2 is a blocking group which is detached at a temperature above 100° C., where R2 is not a substituent selected from the group consisting of

OG Complex Work Unit Chemistry
where
R12 is an alkylene group which has 2 to 5 carbon atoms and optionally has double bonds or is substituted, or is a phenylene group or a hydrogenated phenylene group; and
R19 represents bisphenols, after removal of a hydroxyl group, and
wherein the one-component thermosetting epoxy resin composition has a maximum linear expansion Max. elongation of ≥1.65 mm, determined in a lap shear test during cooling of a heated cured lap shear specimen, and
wherein the maximum linear expansion Max. elongation is measured in the lap shear test at a strain rate Vst of 0.40 mm/min, and
wherein a temperature of the heated cured lap shear specimen in the lap shear test is 180° C. at a start of the measurement and the heated cured lap shear specimen is cooled at the start of the measurement at a cooling rate of 40° C./min to a temperature of 25° C. and then left at that temperature.