Pressure sensitive adhesive composition
Provided are a pressure-sensitive adhesive composition, a pressure-sensitive adhesive optical laminate, a pressure-sensitive adhesive polarizing plate and a display device. The pressure-sensitive adhesive composition offers a pressure-sensitive adhesive that has excellent durability and processability in manufacturing due to increased hardness even when the pressure-sensitive adhesive layer is formed thinner than a typical adhesive composition, and that can prevent a pressure mark and leakage of the pressure-sensitive adhesive, as well as a bending problem generated when applied on an optical member such as a polarizing plate, etc.
1. A pressure-sensitive adhesive composition, consisting of:
a pressure-sensitive adhesive polymer including a polymerization unit of a first monomer which forms a homopolymer having a glass transition temperature of less than 0° C., a polymerization unit of a second monomer which forms a homopolymer having a glass transition temperature of 0° C. or more, and a polymerization unit of a cross-linking monomer;
a cross-linking catalyst in an amount of 1 to 40 ppm;
optionally at least one of other monomers for copolymerization;
optionally a silane coupling agent;
optionally a tackifier; and
optionally one or more additives selected from the group consisting of a curing agent, a UV light stabilizer, an antioxidant, a coloring agent, a reinforcing agent, a filler, an antifoaming agent, a surfactant and a plasticizer,
wherein the first monomer is an alkyl (meth)acrylate containing an alkyl group with 1 to 20 carbon atoms and the second monomer is an alkyl acrylate or vinyl acetate, wherein the alkyl acrylate contains a straight-chain or branched-chain alkyl group with 1 to 6 carbon atoms, and
wherein the pressure-sensitive adhesive polymer comprises the polymerization unit of the first monomer at 60 to 95 parts by weight, the polymerization unit of the second monomer at 1 to 40 parts by weight, and the polymerization unit of the cross-linking monomer at 0.1 to 10 parts by weight, and
wherein the pressure-sensitive adhesive polymer has a weight average molecular weight ranging from 100,000 to 3,000,000, and
wherein the pressure-sensitive adhesive composition has a storage modulus at 30° C. and 1 rad/sec ranging from 0.01 MPa to 0.5 MPa in a state in which a cross-linked structure is formed.
2. The pressure-sensitive adhesive composition of claim 1 , wherein the homopolymer formed of the first monomer has a glass transition temperature ranging from −100° C to −20° C.
3. The pressure-sensitive adhesive composition of claim 1 , wherein the homopolymer formed of the second monomer has a glass transition temperature ranging from 5° C. to 200° C.
4. The pressure-sensitive adhesive composition of claim 1 , wherein the cross-linking catalyst is at least one selected from the group consisting of trialkylaminoalkylethanol amine, N,N,N′,N′-tetraalkylhexanediamine, trialkylamine, imidazole, naphthenic acid cobalt, dialkyltin diacetate, dialkyltin diacetylacetonate, trialkyltin hydroxide, dialkyltin dilaurate, and a combination thereof.
5. A pressure-sensitive adhesive optical laminate comprising:
an optical film; and
a pressure-sensitive adhesive layer formed on either or both sides of the optical film, and containing the pressure-sensitive adhesive composition of claim 1 which is cross-linked.
6. A pressure-sensitive adhesive polarizing plate comprising:
a polarizer film; and
a pressure-sensitive adhesive layer formed on either or both sides of the polarizer film, and containing the pressure-sensitive adhesive composition of claim 1 which is cross-linked.
7. A display device comprising the optical laminate of claim 5 .
8. A display device comprising the polarizing plate of claim 6 .