US 12,077,693 B2
Adhesive composition for foldable display, and foldable display comprising same
Hyon Gyu Park, Daejeon (KR); Hee Song, Daejeon (KR); Hyunsup Lee, Daejeon (KR); and Yoonkyung Kwon, Daejeon (KR)
Assigned to LG CHEM, LTD., Seoul (KR)
Appl. No. 16/755,620
Filed by LG CHEM, LTD., Seoul (KR)
PCT Filed Dec. 11, 2018, PCT No. PCT/KR2018/015701
§ 371(c)(1), (2) Date Apr. 13, 2020,
PCT Pub. No. WO2019/117594, PCT Pub. Date Jun. 20, 2019.
Claims priority of application No. 10-2017-0169347 (KR), filed on Dec. 11, 2017.
Prior Publication US 2020/0332153 A1, Oct. 22, 2020
This patent is subject to a terminal disclaimer.
Int. Cl. C09J 7/38 (2018.01); B29C 65/48 (2006.01); C09J 7/10 (2018.01); H05K 1/18 (2006.01); H05K 5/00 (2006.01)
CPC C09J 7/385 (2018.01) [B29C 65/48 (2013.01); C09J 7/10 (2018.01); H05K 1/18 (2013.01); H05K 5/0017 (2013.01); H05K 2201/10128 (2013.01)] 11 Claims
OG exemplary drawing
 
1. An adhesive composition for a foldable display comprising:
a polymer comprising an alkyl (meth)acrylate and a monomer having a crosslinkable functional group; and
a crosslinking agent,
wherein a content of the alkyl (meth)acrylate is from 97.5 parts by weight to 99 parts by weight and a content of the monomer having a crosslinkable functional group is from 1 parts by weight to 2.5 parts by weight based on 100 parts by weight of the polymer
wherein the crosslinking agent has one or more functional groups selected from the group consisting of an alkoxysilane group, a carboxyl group, an acid anhydride group, a vinyl ether group, an amine group, a carbonyl group, a carbodiimide group and an oxazoline group, or wherein the crosslinking agent comprises N,N,N′,N′-tetraglycidyl-m-xylenediamine,
wherein the monomer having a crosslinkable functional group is at least one selected from the group consisting of beta-carboxyethyl acrylate, (meth)acrylic acid, 2-(meth)acryloyloxy acetic acid, 3-(meth)acryloyloxy propionic acid, 4-(meth)acryloyloxy butyric acid, an acrylic acid dimer, itaconic acid, maleic acid, and maleic anhydride,
wherein the monomer having a crosslinkable functional group does not have a hydroxyl group as the only crosslinkable functional group,
wherein an adhesive strength of the adhesive composition with a polyimide (PI) film after curing is greater than or equal to 500 gf/in and less than or equal to 5,000 gf/in at room temperature;
a storage modulus of the adhesive composition after curing measured under a condition of −20° C. and 1% strain is greater than or equal to 50,000 Pa and less than or equal to 250,000 Pa;
an initial stress upon starting strain under a condition of −20° C. and 12% strain is greater than or equal to 5,000 Pa and less than or equal to 20,000 Pa;
a final stress measured after strain for 10 minutes under a condition of −20° C. and 12% strain is greater than or equal to 1,000 Pa and less than or equal to 10,000 Pa; and
a stress drop defined by (initial stress-final stress)/(initial stress) is greater than or equal to 40% and less than or equal to 90%.