Release film for pressure-sensitive silicone adhesive and production method therefor
A release film for pressure-sensitive silicone adhesives which comprises: any of various bases; a primer layer (first layer) disposed on at least one surface of the base, the primer layer having a specific thickness and comprising as a main component an organosilicon compound having a plurality of silanol groups in the molecule; and a release layer (second layer) disposed on the outer surface of the primer layer, the release layer having a specific thickness and comprising as a main component a cured object obtained from a hydrolyzable fluorinated compound. A release coating film having excellent releasing properties can be stably and easily imparted to various bases, and the primer layer and the release layer can be formed even by room-temperature (25° C.) application.
1. A release film adapted for silicone pressure-sensitive adhesive, comprising a substrate, a primer layer disposed on at least one surface of the substrate as a first layer, and a release layer disposed on the outer surface of the primer layer as a second layer,
the substrate having a thickness of 10 to 200 μm,
the primer layer comprising an organosilicon compound having a plurality of silanol groups per molecule and having a thickness of 0.5 to 500 nm,
the release layer comprising a cured product of a hydrolyzable fluorinated compound and having a thickness of 0.5 to 30 nm.
2. The release film of claim 1 wherein the organosilicon compound having a plurality of silanol groups per molecule is a hydrolytic partial condensate of a tetraalkoxysilane.
3. The release film of claim 1 wherein the hydrolyzable fluorinated compound has at least one hydrolyzable silyl group at one or more molecular chain ends, the hydrolyzable silyl group being selected from among silyl groups having C 1-12 alkoxy, C 2-12 alkoxyalkoxy, C 1-10 acyloxy, C 2-10 alkenyloxy, halogen or amino, and silazane groups.
4. The release film of claim 1 wherein the hydrolyzable fluorinated compound is a fluorooxyalkylene group-containing organosilicon compound having per molecule a divalent linear perfluorooxyalkylene polymer residue: —(CF 2 ) d —O—(CF 2 O) p (CF 2 CF 2 O) q (CF 2 CF 2 CF 2 O) r (CF 2 CF 2 CF 2 CF 2 O) s (CF(CF 3 )CF 2 O) t —(CF 2 ) d — wherein p, q, r, s and t are each independently an integer of 0 to 200, p+q+r+s+t is 3 to 500, each repeating unit in parentheses with subscripts p, q, r, s and t may be randomly arranged, d is independently an integer of 0 to 8, the unit with d may be linear or branched, the organosilicon compound further having at least one hydrolyzable silyl group at one or more molecular chain ends.
5. The release film of claim 1 wherein the hydrolyzable fluorinated compound is at least one compound selected from hydrolyzable fluorinated organosilicon compounds having the general formulae (1) to (5):
(A-Rf) α —ZW β (1)
Rf—(ZW β ) 2 (2)
Z′—(Rf—ZW β ) γ (3)
wherein Rf is a divalent linear perfluorooxyalkylene polymer residue: (CF 2 ) d —O—(CF 2 O) p (CF 2 CF 2 O) q (CF 2 CF 2 CF 2 O) r (CF 2 CF 2 CF 2 CF 2 O) s (CF(CF 3 )CF 2 O) t —(CF 2 ) d —, p, q, r, s, and t are each independently an integer of 0 to 200, p+q+r+s+t is 3 to 500, each repeating unit in parentheses with subscripts p, q, r, s and t may be randomly arranged, d is independently an integer of 0 to 8, the unit with d may be linear or branched, A is fluorine, hydrogen or a monovalent fluorinated group terminated with —CF 3 , —CF 2 H or —CH 2 F group, Z and Z′ are each independently a single bond, or a di- to octavalent organic group which may contain nitrogen, oxygen, silicon, phosphorus or sulfur and which may be fluorinated, W is a monovalent organic group terminated with a hydrolyzable group, α and β are each independently an integer of 1 to 7, α+β is 2 to 8, and γ is an integer of 2 to 8,
A-Rf-Q-(Y) δ —B (4)
Rf-(Q-(Y) δ —B) 2 (5)
wherein Rf and A are as defined above, Q is a single bond or divalent organic group, δ is each independently an integer of 1 to 10, Y is a divalent organic group having a hydrolyzable group, and B is hydrogen, C 1-4 alkyl or halogen.
6. The release film of claim 5 wherein the hydrolyzable fluorinated organosilicon compounds are the following:
wherein Me is methyl, p1, q1, r1, s1, and t1 are each independently an integer of 1 to 200, the sum of p1, q1, r1, s1, and t1 is 3 to 500, each unit in parentheses with subscripts p1, q1, r1, s1, and t1 may be randomly arranged.
7. The release film of claim 1 wherein the release layer contains the cured product of a hydrolyzable fluorinated compound and a nonfunctional fluorinated compound.
8. The release film of claim 1 wherein the substrate is of a resin, paper or metal.
9. A method for preparing the release film of claim 1 , comprising the steps of:
wet coating a solution of an organosilicon compound having a plurality of silanol groups per molecule in a solvent onto at least one surface of a substrate,
drying the solvent to form and lay a primer layer on the at least one surface of a substrate,
wet coating a solution of a hydrolyzable fluorinated compound in a solvent onto the outer surface of the primer layer and then drying the solvent, or providing a solution of a hydrolyzable fluorinated compound in a solvent, evaporating off the solvent, and dry coating the hydrolyzable fluorinated compound to the outer surface of the primer layer, and
curing the hydrolyzable fluorinated compound to form and lay a release layer on the outer surface of the primer layer.
10. The release film of claim 1 wherein the primer layer has a thickness of 30 to 500 nm.
11. The release film of claim 1 wherein the substrate is:
a plastic film or sheet made of polyesters, polypropylene, polyethylene, polyvinyl chloride, polytetrafluoroethylene or polyimides;
a paper substrate;
a laminated paper substrate; or
a metal foil.
12. A layered structure comprising a release film adapted for silicone pressure-sensitive adhesive which comprises a substrate, a primer layer disposed on at least one surface of the substrate as a first layer, and a release layer disposed on the outer surface of the primer layer as a silicone second layer, and a pressure-sensitive adhesive disposed on the release layer of the release film,
the primer layer comprising an organosilicon compound having a plurality of silanol groups per molecule and having a thickness of 0.5 to 500 nm,
the release layer comprising a cured product of a hydrolyzable fluorinated compound and having a thickness of 0.5 to 30 nm.