HMPSA CROSSLINKABLE UNDER UV IRRADIATION
A UV-crosslinkable HMPSA composition comprises 10-24% by weight of a block copolymer comprising a styrenic block and a polybutadiene block comprising at least 25% by weight of the 1,2-vinyl unit; 43-65% by weight of a tackifying resin obtained by polymerization, then complete or partial hydrogenation of a C9 fraction, having a softening point of 80-150° C.; 10-25% by weight of a petroleum-derived hydrocarbon oil; and an appropriate amount of a photoinitiator (D). A self-adhesive article comprises a carrier layer (b) coated with a self-adhesive layer (a) comprising the HMPSA composition in the crosslinked state.
1 .- 12 . (canceled)
13 . A UV-crosslinkable hotmelt pressure sensitive adhesive (HMPSA) composition comprising, based on the total weight of said composition:
from 10% to 24% by weight of a block copolymer (A) which comprises at least:
a block A1 consisting of a repeating unit of aromatic hydrocarbon substituted by a vinyl group, and
a polybutadiene block A2 comprising at least 25% by weight of the 1,2-vinyl unit, based on the total weight of said polybutadiene block;
from 43% to 65% by weight of a tackifying resin (B) obtained by polymerization, then complete or partial hydrogenation of a petroleum-derived C9 fraction of unsaturated or aromatic hydrocarbons, said resin (B) having a softening point of from 80 to 150° C.;
from 10% to 25% by weight of a liquid plasticizer (C) comprising a petroleum-derived, completely or partially saturated hydrocarbon oil; and
an appropriate amount of a photoinitiator (D).
14 . The HMPSA composition as claimed in claim 13 , wherein the block copolymer (A) comprises 2 styrenic blocks A1 and the weight content of the 1,2-vinyl unit in the polybutadiene block A2 is within a range of from 30% to 70% by weight.
15 . The HMPSA composition as claimed in claim 13 , wherein the tackifying resin (B) has a softening temperature of between 90 and 120° C.
16 . The HMPSA composition as claimed in claim 13 , wherein the liquid plasticizer (C) comprises an oil having an average molecular mass as measured by the ASTM D 2502 method of less than or equal to 2000 g/mol.
17 . The HMPSA composition as claimed in claim 13 , further comprising up to 25% by weight of a liquid polybutadiene (E) of low molecular mass.
18 . The HMPSA composition as claimed in claim 13 , wherein it comprises:
from 12% to 19% by weight of the block copolymer (A);
from 50% to 65% by weight of the tackifying resin(s) (B); and
from 14% to 23% by weight of the liquid plasticizer (C).
19 . A self-adhesive article comprising a carrier layer (b) coated with a self-adhesive layer (a), wherein said self-adhesive layer (a) comprises the adhesive composition as defined in claim 13 , in the crosslinked state.
20 . The self-adhesive article as claimed in claim 19 , wherein the article is a single-sided or double-sided self-adhesive tape.
21 . The self-adhesive article as claimed in claim 19 , wherein the article further comprises a nonstick protective layer (c) adjacent to the adhesive layer (a).
22 . The self-adhesive article as claimed in claim 19 , wherein the thickness of the layer (a) is from 5 μm to 2000 μm.
23 . A method for manufacturing the self-adhesive article as defined in claim 19 , said process comprising the sequential steps:
i. of preheating the HMPSA composition to a temperature of between 70 and 180° C.;
ii. of applying said composition by coating to a bearing surface;
iii. of crosslinking said composition by UV irradiation to form the layer of crosslinked adhesive composition (a); then
iv. of laminating or transferring the layer (a) onto a carrier layer or onto a nonstick protective film.
24 . A bonding method employing the self-adhesive article as defined in claim 19 , comprising the following steps:
A. removing the nonstick protective layer, when such a layer is present;
B. applying the self-adhesive article to one surface of a product; and
C. applying a pressure to said article.