USE OF ADHESIVE TAPES FOR BONDING OPTICAL COMPONENTS
Optical components are bondable by means of an adhesive tape that has at least one layer of a pressure-sensitive adhesive compound on basis of a polyacrylate having a weight-averaged molecular weight Mw in the range of 200000=M w =1000000 g/mol, which can be obtained by radical copolymerization of at least the following components: (a) 55 to 92% by weight of one or more acryl monomers of the general formula CH 2 ═CH—COOR 1 , where R1 is a hydrocarbon group having 4 to 14 carbon atoms, (b) 5 to 30% by weight of one or more copolymerizable monomers, wherein the glass transition temperature T G,bH of the homopolymer from the monomer of the component (b) is no less than 0° C., or wherein the glass transition temperature T G,bH of the copolymer from the monomers of the component (b) is no less than 0 DEG C., (c) 3 to 15% by weight of one or more copolymerizable monomers promoting a cross-linking reaction of the polyacrylate, wherein the polyacrylate is cross-linked. The cross-linked polyacrylate has a loss factor ranging between 0.2 and 0.4, a shear strength characterized by a maximum deflection x max in the microshear travel test of 200 to 600 μm, and an elastic portion in the polyacrylate of at least 60%.
1 . A method for the adhesive bonding of optical components by means of an adhesive tape, wherein
the adhesive tape has at least one layer of a pressure-sensitive adhesive based on a polyacrylate having a weight-average molecular weight M w in the range from 200000≦M w ≦1000000 g/mol and being obtainable by free-radical copolymerization of at least the following components:
(a) 55% to 92% by weight of one or more acrylic monomers of the general formula
CH 2 ═CH—COOR 1
where R 1 represents a hydrocarbon radical having 4 to 14 carbon atoms, where a
glass transition temperature T g,aH of the homopolymer of a monomer of component (a) [defined as glass transition temperature value T g according to DIN 53765:1994-03] is not more than −20° C.
or a where the glass transition temperature T g,aC of a copolymer of the monomers of component (a) according to the Fox equation is not more than −20° C.,
(b) 5% to 30% by weight of one or more copolymerizable monomers,
where a the glass transition temperature T g,bH of a the homopolymer of the monomer of component (b) [defined as glass transition temperature value T g according to DIN 53765:1994-03] is not less than 0° C.
or where a the glass transition temperature T g,bC of a copolymer of the monomers of component (b) according to the Fox equation is not less than 0° C.,
(c) 3% to 15% by weight of one or more copolymerizable monomers promoting a crosslinking reaction of the polyacrylate,
wherein the polyacrylate is crosslinked,
where the crosslinked polyacrylate has a loss factor (tan δ value) of between 0.2 and 0.4,
wherein the crosslinked polyacrylate has a shear strength having characterized by a maximum deflection x max in the microshear travel test of 200 to 600 μm,
and where the crosslinked polyacrylate has an elastic component in the polyacrylate of at least 60%, determined in the microshear travel test.
2 . The method of claim 1 , wherein
component (b) comprises at least partly of one or more acrylic and/or methacrylic monomers of the general formula
CH 2 ═C(R 2 )—COOR 3
where R 2 is H or R 2 is CH 3 and where R 3 represents a hydrocarbon radical having at least six carbon atoms, and for which the-conditions in relation to glass transition temperatures specified for component (b) are met.
3 . The method of claim 1 , wherein the adhesive tape is carrierless.
4 . The method of claim 3 , the adhesive tape is formed by the layer of pressure-sensitive adhesive.
5 . The method of claim 1 , wherein component (c) comprises at least partly of one or more acrylic and/or methacrylic monomers of the general formula
CH 2 ═C(R 4 )—COOR 5
where R 4 is H or R 4 is CH 3 and where R 5 is H or R 5 represents an alkyl group which has a functional group capable of and/or promoting a crosslinking reaction of the polyacrylate.
6 . The method of claim 5 , wherein
the glass transition temperature T g,cH of the homopolymer of the monomer of component (c) [defined as glass transition temperature value T g according to DIN 53765:1994-03] is not less than 0° C.
or where the glass transition temperature T g,cC of the copolymer of the monomers of component (c) according to the Fox equation is not less than 0° C.
7 . The method of claim 1 , further comprising
crosslinking the polyacrylate with at least one thermal initiation.
8 . The method of claim 7 , further comprising adding aluminum chelate as crosslinking initiator.
9 . The method of claim 7 , wherein a temperature at crosslinking does not exceed 90°.
10 . The method of claim 1 , wherein component (c) comprises at least partly of one or more copolymerizable photoinitiators.
11 . An adhesive tape with at least one layer of a pressure-sensitive adhesive based on a polyacrylate having a weight-average molecular weight M w in the range from 200000≦M w ≦1000000 g/mol, where the polyacrylate is the product of polymerization of at least the following components:
(a) 55% to 92% by weight of one or more acrylic monomers of the general formula
CH 2 ═CH—COOR 1
where R1 represents a hydrocarbon radical having 4 to 14 carbon atoms, where additionally, if component (a) comprises only one monomer, a glass transition temperature T g,aH of a homopolymer of the monomer of component (a) [defined as glass transition temperature value T g according to DIN 53765:1994-03 (cf. section 2.2.1)] is not more than −20° C.
or, if component (a) comprises more than one monomer, a the glass transition temperature T g,aC of a the-copolymer of the monomers of component (a) according to the Fox equation is not more than −20° C., the glass transition temperature value T g being used for calculation into the Fox equation being the T g according to DIN 53765:1994-03 (cf. section 2.2.1) of the homopolymers of the individual monomers of component (a);
(b) 5% to 30% by weight of one or more copolymerizable monomers,
where, if component (b) comprises only one monomer, a glass transition temperature T g,aH of a the-homopolymer of the monomer of component (b) [defined as glass transition temperature value T g according to DIN 53765:1994-03 (cf. section 2.2.1)] is not less than 0° C.
or where a the glass transition temperature T g,bC of a copolymer of the monomers of component (b) according to the Fox equation is not less than 0° C., a glass transition temperature value T g being used for calculation into the Fox equation being the T g according to DIN 53765:1994-03 (cf. section 2.2.1) of homopolymers of the individual monomers of component (b);
(c) 3% to 15% by weight of one or more copolymerizable monomers promoting a crosslinking reaction of the polyacrylate,
wherein the polyacrylate is crosslinked,
where the crosslinked polyacrylate has a loss factor (tan δ value) of between 0.2 and 0.4,
wherein the crosslinked polyacrylate has a shear strength having maximum deflection x max in the microshear travel test of 200 to 600 μm,
and where the crosslinked polyacrylate has an elastic component in the polyacrylate of at least 60%, determined in the microshear travel test.
12 . The method of claim 7 , wherein a temperature at crosslinking does not exceed 60° C.