CA2132201A1 - Crosslinkable silarylene-siloxane copolymers - Google Patents

Abstract

Crosslinkable copolymers suitable for use as elevated temperature pressure-sensitive adhesives comprise randomly arranged silarylene units and siloxane units. Preferably, there is present in the copolymer backbone in the range of 0.8 to 1.2 siloxane to silarylene units, and there being present in the copolymer a crosslinking functionality.

Description

C~0~8hIN~AB~_8ILARy~E~E-~ILU~ANE CoPo~Y~R8 FIE~D 9F T~E INYBNTION
~he present invention relates to thermal and ultraviolet (W) radiation curable silarylene-siloxane random copolymers and cured co~po~itions thereof, and to a proce~s for making the copolymer, The cured silarylene~iloxane copoly~ers are elevated temperature 10 resistant pressure-sensitive adhesives (PSAs).

: BAC~GRO~ND OF ~_ ~V~ION
Silicone pressure-sensitive adhesives are well known. Generally, they comprise a mixtur~ of a 15 silicone polymer, a tackifier rPsin, solvent~, viscosity ~tabilizers, and other additives and are cured ~y thermal and/or ~atalytic means. Silicone polym~r~ used in:thase mixtures are gums containing : dimathylsiloxy a~d:diphenylsilsxy groups and siloxy ::~ 20 groups having a group useful in a:crosslinking reaction such as a ~inyl or acrylic group. Such adhesive~, alk~ough useful for many applications, fail for appli ations necessitating elevated temperaturesO
~;ilicone pGlymer~ containing organic groups in 25 ~ddition~to oxygen a~om~ between ~ilicone at~R are well known. ~hese polym~rs in which the organic gr~up is an arylene gr~up~are known as silarylene po~ym~r~
: and tho~e polymers also containing diorga~osiloxy groups are known as silarylene-siloxane copolymers.
30 These copolymer~ ca~ generally be cured by exposure to!
:~ ion~zing radiation or by h~ating in the presence of well known catalysts. Silarylene-siloxane and siloxane : unit in the copolymer may have a random distribution as is disclosed in U.S. Patent Nos. 2,562,000, 3S 3,287,310, 3~332,973, and 4,340,711 or the ~nits may be block~ as is disclosed in U.S. Patent No. 3,959,403.
U.S. Patent No. 3,444,127 discloses ordered :

WO93/21278 21 322 Ql PCT/US~3/0~07~ ~

poly~arylenesiloxane) polymers, and U.S. Patent No.
4,366,323 discloses arylene-siloxanylene pol~ers.
The silarylene-siloxane copolymers described above can be useful, for example, in high temperature 5 resistant fluids, fibersl coatings, or elastomers.
U.S~ Patent No. 4,534,838 discloses photo-initiating silicones and makes reference to others.
U.S. Patent No. 4,563,514 discloses radiation curable polysilarylene-polysiloxane copolymers which 10 ~an be crosslinked in the presence of a suitable cure initiator to provide transparent, self-bonding, di-t repellent, tough, and solvent resistant compositions.
Vinyl substituted silarylene-siloxane copolymers are disclosed in Macromolecules, Vol. Z4, No. 16, pages 15 4503-4509, and 451~ to 4514 ~1991). Silarylene-siloxane compositions curable to pressure-sensitive adhesives are not disclosed.
~ : None of the~:above~art or ~ny ~other art of which :~: the inventor is~`aware~pro~ides a silarylene-siloxane 20 copolymer compoæition that i5 curable to an elevated : temperature-resistant~pressure-sensitive adhesive.

nxMAQ OF ~HE INVE~TION
Briefly, a-crosslinkable silarylene-siloxane ~: 2:5:~pressure-sensitive~adhesiv~ copolymer composition comprises a copol~mer comprising a~backbone having rand~mly arrang~ed~silarylene and siloxane units, of whi d~siloxane units: at least 55 mol percent are aryl : siloxane units, the copolymer comprising at least 0.05 :~ 30 ~molipercent crosslinking~functionality. Preferably, : there can be in the random cspolymer backbone no more : -than:six, more preferably an average of no more than two, and most~preferably no more than two, consecutive units of either silarylene or siloxane units. Because 35~ the: copolymer is curable there is present in the ~ copolymer a crosslinking functionality.
: ~ :

~ , ::

WO93/2127~ ! ?1~22ol PCT/US93/0~074 The silarylene-siloxane copolymer composition curable to a pre~sure-~nsitive adhesi~e khat i5 resistant to degradation at elevated temperatures. The silar~lene-siloxane copolymer c~mprises units of R3 R3 R4 .
-Si Ar- si-o- and -si-o- :
1~ ~3 13 14 in which Ar, R3, and R4 are defined below. In a most preferred embodiment, there are present 1:1 alternating silarylene and siloxane units. ~:
In another aspect, there is provided a process for making the silarylene-siloxane copolymer.
In a further aspect of the in~ention, there is provided an artiole co~pri~ing a subs~rate bearing on at least on@ surface thereof ~n elev~t~d temperature-20 r~s:istant pressure- ensitive adhesive layer o~ the : : ~ cur~d composition described above.
In ~hi~ application:
'silarylene" in a polymer means a ~ilarylene~iloxy u~i~ having the struc~ure : 25 ~ Si ~;Ar - Si - O - , wherein ~r i~ a~
. , ., ~ , 30 de~ined below;
; q'silox~ne" means a polymer having Si-O groups~
: i.e., the ~iloxy unit, -Si ~

~ 'acryli acid" or "acrylic acid ester" mean to include methacrylic acid or me~hacrylic acid ester;
: ~ ~ 4Q Nlower alkyl" means C1 to C4, linsar or branched;
and : , W~ 93/21278 ~ n 3~ 2 01 P~r/usg3/02074 "group" means the specified moiety or any group containing the specified moiety (as by substitution or extension~ that does not adversely affect the composition.
DE~AILE~ D~SC~IPTION 0~ PREFERRED EMBODINENT8 OF T~
INVENTION
Briefly, in a preferred embodiment, the silarylene-siloxane copolymer composition o~ the 10 invention that is curable to a pressure-sensitive adhesive, and that is resistant to degradation at elevated temperatures, comprises a copolymer having the general formula: :

R6--SRi4~ ~ r ~si~3--SltR6 I

wherein : R3 is independently a lower alkyl group having 1 to 4 carbon atoms, preferably a methyl group;
Ar is an arylene or àlkylenearylene group having 6 25 to 20 carbon atoms, that optionally can comprise 1 to 3 rings that can be fused or joined by a covalent bond or t : O O R3 ~: 30 -OC-, -OCO-, -Si- , or linear, branch~d, or cycloalXylene of up to 6 carbon atoms which can be substituted with fluoroalkyl groups having 1 to 3 35 carbon atoms and having 1 to 7 fluorine atoms;
each R4 is an organic group independently selected from aryl groups ha~ing S to 12 carbon atoms, linear and branched alkyl groups having 1 to 6 carbon atoms, and R5 groups, of which total R4 groups 5S to 95 mol 40 percent are aryl, preferably phenyl, 5 to 45 mol .

WO93/21278 ~-~ 213 2 2 01 PCT/U~93/02074 _ 5 _ perc@nt are alkyl groups, pre~erably methyl~ and 0.05 to 5 mol percent ~re R5 groups which iæ defined below;
c is a number having a value o~ 0.8 to 1.2 expressing the n~mber of ~iloxane groups per arylene or 5 alkarylene group, pref~rably c has a value o~ 0.9 to 1.1 and ~ost preferably is 1;
d is a number having an average value of 50 to 500;
e is a number having a ~alue from 1 to about 2Q0 so that the weight average molecular weight of the 10 copolymer is between about ~ x 104 and 5 x 105;
each R6 is ~ terminal group that independently may be hydroxyl, lower alkyl, phenyl, or R5; and Rs, which is required to be present in at l~ast one of R4 and R6, can be a functional crosslinking group elected from organi groups containing - a) an ~thylanically-unsaturated group sel~cted om 1) group~ cro~ kabl¢
; ~; under the in~luence of free radicals, pr~ferably an acrylic acid ester-: 20 containing group and 2) groups crosslinka~le in a hydrosilation reac~ion with copolyhydrosilane, preferably a vinyl containing group, b) :an oxirane group (generally called an 25~ epoxy ~and includes epoxy-containing gr2Up), preferably a gly~idoxyalkyl~ne group, and c) a grQup that is a photocrosslinker, such as a pendent benzophenoxy group, with t~é provisos:
l) that at least 0.05 mol psrc~nt, preferably at Ieast 0.5, ~ore .
preferably 1.0 ~ol percent of R5 is pres~nt as at least one o~ R6 ~nd 3S ~4 and

(2) that WC~ 93/~1278 ~ 2~0 1 PCI/U~93/~2074 (a) wh~n E~5 is an acrylic: acid ester group there is present in the composition a su~f icient amount of an ~:
initiator of f ree radiaals to eff~ct polymerizat~ orl and thereby crosslin}cing of the ac:rylic groups, (b) when R5 is a ~vinyl group attached direetly to a Si atom there is pres~nt in the :.
compositis)n a suf f icient amount of polyhydro~iloxane, pref erably 1 tc~ 5 weight perc~nt, and a ~;uf f ic:ient amount of cataly~;t, pref erably 1 to lOOo ppm, ~or a :: hydrosilation r~action, (c) when R5 is an oxirarle-: ~ 20 : ~ contaîning gr~up there is : ~ : pr~sent in the composition a sufficient amolmt of epoxy re~in curative, preferably 1 ~: to 5 weigh~ p~rc:ent , and s ~ (d) when R5 is ~photocro~slinkiTIg roup it i~ pr~sent in ~
composition in suf f is :i~nt amount~ preferably 0. 05 to 3 weight percent, to crosslink 30; ; :the polymers.
The weight average molecular weight of the copoly~ers pre~erably ::~n be in the range of 20,000 to 5,~00~000, ~ore preferab~y 30,000 to 1~5oo~a~o~ and ~: ~ost pre~rably 50,000 to l,oOo,Ooo.
:~: 35 Th@ ~ilarylenQ-silox~ne copolymers of the in~ention are prepared by modification of methods kn~wn in th~ art for making silarylene-siloxane copolymers. ;~

. ~1V0 93/21278 ~ 2 1 ~ 2 2 01 PCr/US93tû2074 The copolymers of the in~rention are prepared, ~or example, by the condensation of one mole of a silarylene compound s:~f the stru ::tural ~ormula s R3 R3 Y ~ Si ~ Si Y II

1~
with from about 0. 95 to 1. 0 moles o~ diorgarlic group substitllted s~ lanes of the ctruc:tural ~ormula Z -- Si -- Z III

.
20 in which R3, R4 and Ar are defined above and Y a~nd Z are ~utually reactive groups which independently ~re hydro~yl or a hydrolyzable group such as halogen, amine, or a substituted uriedo . Pref erably, Y is hydroxyl and Z is dialkylamino. The condensation 25 reaction can be carried :out at about 50 to 150~C, pre~erably at 80 to 110 in a hydroc~rbon solvent such s c:yclohexane, benzene ~ toluene, or xylene . ~en Y is yd~yl and Z is~`~substituted uriedo ~uch a~

:: ~0 ~C~N

~: ~ R
35:
wherein each R independently can be a linear or brarlched alkyl group having 1 to 4 ~--arbon ats: ms or both :: R groups together provide a cycloalkylene group having 4 to 8 carbon atoms, the condensation reaction a~n be 40 carried out at: 5û to 150C in chlorobenzene. Note:

WO 93/21278 2 1 :~ 2 2 0 1 P(~/US93J02074 the substituted ur~ido group~; ref erred to ln the following discussion i8 ~;pec:ifioally ~N--CC~N\ ¦
[~ ~H2--C~2 When eithe~ Y or Z i~ halogen, pref erably chlorine, the conden:ation can b~ arri~d out at about -lO~C to 30C
in a polar organic: solvent . uc:h a~ tetrah~dro~uran vr chl orobenzene. The condensation reactiorl carl b~
15 terminated by reaction with water. The polymer obtainéd by the condehsation reaction typically has l:he structural f ormula:

~F~3 R3 R4 4~ IV

:: 25 whereirl Ar, ~, R4, b, arld d ~re defined above.
Al~ough this c:opol~er, having terminal hydroxyl groups/ can b~ u ed in ~he elevated t~3mp~ra~ure re~ pre~ure ~ensitiYe a~e~ive co~po~itions the inveDtion~ it i~ ol~ten desir~ble . o replaGe t~e 30 t~r~inal hydroxyl group by reaction wit~h silyl cc~mpounds (R'a) 3SiZ, to obtain terminated polymers, or wi~ ~R4) 2RSSiZ to s~btain chain extended copolymers havin5~ structural Formula I. It i~ often desirable to react the copolymer ~wilth both an ~R4)2SiZ2 and an 35 63;L4~3 2R~SiZ silyl c:c~mpound so as to obtaln terminat~d ~: ~ c:hain ext~nded copolymer~;.
: ~ In the prsparation of the silarylene-si~o$ane copolymers, when eithPr Y in the silarylene of formula - II or the Z in he silane of formula III is halogen, 4 0 ~here is f ormed a prepolymer ha~ing up to 6 repeating .2l322ol ~WO93/21278 j. PCT/US93~02074 - _ g _ units of either silarylene or siloxane units, these being an zverage of 1.7 repeating units of silarylene and an average of 1.55 repeating units of siloxane.
When Y is hydroxyl and Z is dialkylamine group, there 5 i~ formed a prepolymer having up to 3 repeating units in a chain, averaging 1.7 repeating units of silarylene, and 1.02 repeating units of siloxane. When Y is hydroxyl and Z is uriedo, there are e~sentially on}y alternating units o~ silarylene and siloxane.
The present inventisn provides a method of preparing a crosslinkable polymer comprising the steps of:
1) reacting a ~ixture comprising a functional silarylene compound with a diorganic group substituted silane to provide a rea.ctive precopolymer, .2) reacting ~aid reàctive precopolymer with : a chain extending ~ilyl co~pound to : provide a high molecular weight copolymer:(i.e., above SoO,OOo weight : average molecular weight), and

3~ o*tionally curing said high molecular weight copolym~r to provide a ::
: crosslinked copolymer.
: ~ sum~ary of the:Reaction Equations that can provid~ the copolym~r~ of the invention are as follows:

~ ~ , :
' ' ~:

WO 93/2127~ 2 1 3 2 2 0 1 PCI`/U~93/0~74 la.3 Rl3 ~,4 Y--Si~ Si--Y ~ Z--Si--Z

ac~ylic e~, e~by ph~ m~ ~P) when Y ~nd Z ~e ¦ \
hyd~ \w~en Y and Z a~e muhlally hydlolyz~ble ~ eactive gtwps atlea~ ~o ~ / - R3 R3 R~
~S6~ ~d ! ~lR3 13 1~ d tl /~olym~
lV
at 1~ ~e of lR4~Si:Z2 ~d ~R3: R3 Rl 4 ~ ~ (R4 ~SIi~ . -( S~ ( lS~ )~ d Sl a- _R6 R4 L R3 R3 ~ R4 e copo ~ng .

~herein~r,~ Y~, R3, Z, R4, d, c, e, R6 are as previ~u~ly de~ined.~
:~unctional silarylene compounds uitable for u~e ; :in ~he preparation of the copolymers of the inve~tion S ~re ~hose compou~ds~o~Formula II, where Y~is hydroxyl or a hydr~lyzable group, preferably Y i5 hydroxyl or : ~chlorine, and Ar is an arylene ~roup which can cont in ~heteroatoms such as 0, e.g., as in ether or ester gr~ups, preferably, phenylene or biphenylane group~ ~ 10~ substitut d by at least one lo~er al~yl group (i.e., C
to C4, ~hich can be substituted by halogen at~m~);
pre~erably Ar has at least one of the form~lae:

: : .

W093/~278 ii 2l 3?20l PCr/US93/02074 .

~CH2T~cH2)p ~CH~ _~)p wherein each R3 group i~ a lower alkyl group of 1 to 4 carbon atoms, n is zero or an integer having a valus of 10 1 to 4 inclusive, p is zere: or one, and W i~; selected ~r~m a covalent bond and the divalent groups: ~ , --~-- ( in which R19 is hydrogen, lower alkyl :L5 R19 Rl9 o~ 1 to 4 carbon atoms l or -CF3 ~, o R3 DO-C-, ~C~, and --Si-- ~wherein R3 is as def ined above), and -CH2CH2--. ` Th~ following structural ~ormulae llustrate suitable bis (di-l~wer-alkylhydroxy~ilyl) arene~ and bis (di-l~wer-2S alkylhalosilyl) arenes which are pr~ferred silaryleneco~pounds of Formula II:
CH3 CH~ C~3 CH3 ;: : 4 ~si ~ o~ ~ Cl -- sl~si Cl ~3 C~3 ~ C~3 ~H3 : ~2~5 C2H5 ~H3 CH3 HO -- Si~Si -- OH ~ HO -- si~4i OH ~
C2Hs ~2H5 C~H3 ~ H3 : 4 0 3 CH3 ~4Hs

4 ~ ~' 4 4 ~
'~ I
C~3 CH3 C4H9 ~4Hg WO 93/21278 2 13 2 2 01 P~/US93/û2074 C~3 CF3 CH3 ~4Hg CF3 C1~4Hg Br-- Sl ~ C--~--si -- Br Cl - fi~ SiCl CH3 ~F3 s ~3 C4~Ig CF3 C4Hg c~3 CH3 CH3 ~H3 H~ f i--~ ~ si -- o~ Cl-- Si~CH2--~--Si~

C:H3 CH3 ~H3 CH3 C~H3 ~f i~f i~H H~Si CH2~CH2~CH2--si~H
CH3 ~H3 CH3 CH3 ~ H3 1 3 ~H3 ~H3 1 ~--~12- S~OHCl--Si--CH2~CH2Si~l : ~ ~I3 CH3CH3 ~ H3 ~: :
~he bis ~dilowe~alkylhalosilyl) ~r~nes can be ; ; prepared accc~rding to the method disclosed in U. S .
Pa~en~ No. 4, 709, 054 by the reaction of an zromatic:
35 acyl-halide with a haloge~ated poly ilane in the : ~ presex~ce of a transition ~etal catalyst. The;
; ~ bis (hydroxydiloweralkylsilyl) ar~nes aa~ be prepar~d by the~ method disclosed in U.S. Pa!tent No. 3,202,634 by f irst preparing a h~drosilane, by reaction of an arene 40 dihalide, with magTlesium and a silane, in a ~odified .
Grignard reaction and then converting the hydrosilane to the corresponding diol by hydrol~sis with aquec~us : NaO~ or KO~ . :
Diorg~nic group-substituted silanes of Formula III
45 . uitable for use in the preparation of copolymer~; of th~ invention are of two classes: Clacs A ~ilanes in : ~ :

WO g3/21278 ; 1`, f 2 1 3 2 2 0 1 Pcr/usg3/o2o74 NaOH or KOH. These patentc are incorporated herein by reference for these disclosed methods.
Diorganic group-sub tituted silanes of Formula III
suitable for use in the preparation of copolymers of

5 the invention are of two classes: Class A silanes in which the organic groups of the silane compound, i.~., R4 groups, are non-functional groups including alkyl groups that can be straight chain or branched and having 1 to 6 carbon atoms and aryl groups having 6 to 10 12 carbon atoms; and Class B ~ilanes, in which the organia groups, i.e., R4 groups, of the silyl compound is at least one group containing a functional group, i.e., R5, which is the crosslinking (i~e., curable) group of the copolymer. The diorganic group-15 substituted silanes are chocen so that ~5 to 95 mole : percent of the R4 groups in the resulting copolymer are :
:aromatic groups,:5~to;~5 mole percent are alkyl groups,and O.05 to 5 mole~percent are organic groups containing~a functional crosslinking group. Where less 20~than 55 ~ole:percent~of the:R4 groups are aryl, the copolymers~b~come increasingly tougher and are not pressure-sensitive.

Exa~}es o~_Çlass A silanes which are ~ommerciallv ZS a~ailable:i~clyde~
:dichlorodi~ethylsilanè ~
:bis(dimethyl~mino)dimethylsilane dichlorodiethylsilane~
dihydroxydiphenylsilane 3Q` dichloroqiphenylsilane ~ , .
dichloromethylphenylsilane dihydroxydimethy;l ilane : bis(N-pyrrolidyl)dimethylsilane s(ureido)dimethylsilane 35 ~dihydroxydiethylsilane is:(diisopropylamino)diisopropylsilane : bis(ureido~di(l,1-dimethylethyl)silane , ~ :,:: , W093/21278 ~ 2 1 3 2 2 0 1 rcl/usg3/02074 dihydroxydihexylsilane bi~(ureido)diphenylsilane dihydroxydi-l-naphthylsilane dichlorodi(4-phenylphenyl)silane 5 dihydroxymethylphenyIsilane bis(ureido)methylphenyIsilane.
~the first six are available from Petrarch Systems Silanes and Silicones, Bristol, PA) The silanes then following can be prepared by known procedures as 10 disclosed in MetalQrq~anic PolYmers, K.A. Andrianov, Interscience Publishers, NY (1965) and Organosilicon Compounds, C. Eaborn, Butterworth Scientific Publications, London ~(1960).

Additional examples of Class A silanes can prepared as disclosed in Macromolecules, Vol. 24, No. 16, page 4504~1199l~.

Class B silanes,~the ~ilanes in which an organic 20 group~oontains~a;~functiona~ group that is used in the preparation of the~oopolymer if there are no cros~slinkable~groups present in the R6 groups, are silanes of Formula~III having two groups, Z, that are reactive~in condensation~reaction with groups Y of 25 ~Fo:r ula;II~. The~Clas ~B~ sil~nes also can have one or two~functional~organic groups, Rs,~there being at léast 0.05 mol percent,~ preferably at least 0.5 mol percent, and~more preferab}y~ .O mol percent of R5 being present as at least one of R6 and R4 that in the copolymer are 30 ie~ponsible~for the crosslinking (curing) of the copolymer on exposure to activating energy (e.g., W , E-beam, thermal)~.~ There are four subclasses of Class B
silanes to provide the four choices for functional roup R5, defined ab~ve, as follows:
Clas~ B(a) si}anes are compounds having the general formula~:

W0~3/21278 ~ 21 3 2 2 o l PcT/US93/0~074 . - 15 -Z--si--z S l8 in which Z i~ hydroxyl or halogen; R7 is selected from alkyl groups having 1 to ~ c~rbon atoms, aryl group~
having 6 to 12 carbon ato~, and R8; and R8 i~ an 10 e~hylenically-un~aturat~d ~roup that is crosslinkable under the influence of ~ree radicals and includes such groups as (CH2)m-CH2-0-~O-c=cH2~ H2)s-cH2cH=~H
lS Rg --(C~2)~ ~--C~=CH2, (C~2)~--CI=C~2, --~C~2)~--C=CH~
Cl : and preferably i ~(CH2~m~CH2~0~CO-~=cH2 in which m can be an integer of 2 to 12 ~nd R9 can be H or -CH3. ~ :
: 3~ Class B(b) silanes ar~ co~pounds having the general for~uI~:

~si--z 35~

in which Z is hydro~yl or halogen; R10 is selected from : alkyl groups having 1 to S carbon atoms, aryl groups 40 ha~ing 6 ~o 12 carbon at~msp and R11; and Rll is a vinyl, propenyl, or butenyl group. Examples of Class : ~: B(b) ~ilan~s include: dihydroxymethylYinylsilane, dichloro~ethyl~5-hexenyl)silane, :~ ~ dihydroxy-2-pr~penylmethylsilane, WOg3/21278 ~ PCT/US93/02074 .. ; .

dichloromethylvinylsilane*, dichloro-2-propenylmethylsilane, dichlorophenylvinyl ilane~, dichlorodivinylsilane~, and dichlorodi(2-propenyl)silane.
5 ~ available from Petrarch Syste~s Silanes and Silicones; others can be prepared as disclosed in Oraanosilicon Compounds, su~ra.
Class B(c) silanes are epoxy group containing silanes having the ~eneral formula:
~12 Z--si--z in which Z is defined above; R12 is selected from alkyl :~ :
~: group8 having l:to 6~carbcn atoms, aryl groups having 6 ; : to 12 carbon atoms,::and R13, and R13 is an epoxy group .
: 20 having the~formula:~ ~

H2cN2 ~ -CH2CH(CH3) ~ N3 ; -CN~cH3) ~ -cH2cH2cH2ocHz ~ ~ 2CH2C~2 ~ OCH2CLHCH2 :~ 35 /~~~
~ ~ --CH2CH2~b ~ 2COOC:H2~1 HCH2~ ! ` ' Class B(d~ silanes are silanes that con~ain a ~x photoinitiator group that is responsible for a photoinitiator induced crosslinking (curing) of the polymers under;the influence of ultraviolet. Class ~ : 45 Btd) silanes have the general formula :~
~, :

WO93/21278 ~ ~ PCr/U~3/02~74 ,-~--S ~--Z

in which Z is defined above; R14 is selected from alkyl gr~ups having 1 to 6 carbon atoms, aryl groups having 6 to 12 carbon atoms and Rl5; and R15 is a polymerization 10 photoinitiating group. Included among such groups are:

--CH2CH2~H2~0~ CH2CH2CH2--N~

O o -CH2CH2-OC-CN=C~ ~ -C~2CH2~0C-CN=CH-CH=CH ~

/o\
: H2~ CH2 : --CH2~2~H2--O--~H2 I N
H2~ \ ~ 2 : ~ 0 Wh~n R4 o~ For~ula I is a crosslinking group R5 and R5 ~$ ~n ethylenically unsa~urat~d group-containing organic gr~up that is polymerizable ~y ~ree radicals there i~ pr~ent in the copolymer composition a 35 ph~toinitiator of fre~ radicals to promote the pol~merization of the ~crylic acid ester group and ffect crossl~nking (curing) of the compositionO
Suitable photoinitiators include for example, acyloin and derivative~ thereof ~uch as benzoin, benzoin methyl ~:40 :e~her, benzoin ethyl ethPr ~ benzoin isopropyl ether~
:: ~benzoin iso~utyl e her, and 2-hydroxy-2-methyl-10 2-diphenylathanone; diketones such as benzil and 2, 3-butanedione; and phenones such as acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-WO93/21278 2 i 3 2 2 0 1 PCTIUS93/02074 phenylacetophenone, benzophenone, 4,4'-bis(dimethylamino)benzophenone, and l-hydroxycyclohexyl phenyl ketone. ~hese photoinitiators are a~ailable from Aldrich Che~ical Co. Also, useful are 5 2,2,2-tribromo-l-~henylethanone and 2,2,2 tribromo-l-(2-n~trophenyl~ethanone which can be prepared by known procedures. Generally, the radiation acti~ated initiator is present in an amount of about 0.0l to l0 weight percent, preferably about 0.25 to 5 weight l0 p~rcent, and more preferably 0.5 to l.5 percent by weight of the copolymer. The independent photoinitiators of polymer crosslinking listed above can also be used as photoinitiators of free radicals for promoting the polymerization.
Other photoinitiators that can also be used in the compositi.on of the invention include, but are not limited to: aldehydes, such as benzaldehyde, acetaldehyde~ and their substituted derivatives;
ketones such as~ acetophenone, ~enzophenone and their 2 O substituted derivatives, particularly the 4-` alkylbenzophenones~wherein the alkyl group has l to 18 ~: carbon atoms such as~the methyl, ethyl, butyl, octyl, dodecyl, and octadecyl groups, and the commercially available:derivatives:such as Sandoray~ lO00 (Sandoz : 25 C~emicàls, Inc.:,.Charlotte, NC); quinones such as thebenz ~ none~ ànthraquinone and their substituted derivàtivesi thioxanthones such as 2-sopropylthioxanthone (Polys~iences, IncO ~ Warrington, PA) and 2-dodecylthioxanthone; and certain chromophore-30 substituted~halomethyl-sym-triazines such as 2,4-bis-(trichloromethyl)-6-(3',4'-dimethyoxyphenyl~-sym-: triazine:(3M, St. Paul, NN). Other pre~erredindependent (monomeric or oligomeric or po~ymeric) cro~slinking agent~ are polyfunctio~al benzophenones (that i , compound~ having an aliphatic, aromatic or 8ilicic ~ucleus to which two to four benzoylphenoxy gro~ps are attached) because: (l) they are particularly WO 93~21278 ~ j, 21 3~D ~ Pr/U93/02074 effec:tiv2 in brillging about rapid gelation of the ;Idhe~ive compo~;itis:~n (2) of their low vapor prç~sure, and ( 3 ) of their thermal stability . Examples of such compounds include:

~--CO~(CH2)2-10~--CO~ , and R16~--[~o~--C~ ] 2-4 in which :R16 is hydrogen or an ~lkyl group having 1 to 18 carbon atoms, ~C~COMH--(H2C) 1_6~Ol~( cH2 ) 1_6NHcoo~3 CO~) (CH2~1_6NHCo~--CO~

and ~: 2~ .
C:H3 (Rl7) 4_~Si--(~Si--CH2CN2CN2~:~) f i~ whic~ 7 i alkyl ~oup ha~ing 1 to ~8 aarbon atom~; :
and f~ ic t~ae int~er 2 t 3, or 4 . These a~mpounds c:~n lbs ~r~pared aec:ording to reactions disclosed in B ehler-nd~Pearson in~ L~g~2~niC Synthesis, vols. 1 and 2, John Wiley Sons, NY (1977).
::: When R4 of Formula I~is R5, and R5 is an organic !
vinyl-containing group, a mutually rea tive gr3Up in the silaryl~ne siloxane copolymer composition is 40 present, e.g., a polyhydrosiloxane crossli~ker capable o} participating i~ a hydrosilation reaction with the : : ~i~yl group. Suitable polyhydrosiloxane crosslink~rs : c~ntain at least two hydrosilyl groups such as for ~ ex~ple:

WO93/21278 ~ 213 2 2 01 PCT/US93J02074 R18 R~ ~ ~ 18 R

5 R18 R' R18 Rl wherein each Rl~ independently can be an alkyl group of 1-6 carbon at~ms or phenyl;
each R' independently can be R18 or hydrogen, provided that at least two R' groups are hydrogen;
Q can be oxygen, an arylene group ha~ing 6 to 16 ~ :-carbon atoms, an alkylene group ha~ing 2 to 16 carbon atoms, or ~CF2~z where z = an integer from 2 to 10;
each g, h, and j i~ 0 or an integer in the range of 1 to 35 da~ignating the numbers of repeat uni~.
Specific rlasses of these crossli~ker~ are polyhydrosiloxanes containing silicon-hydride groups ~: and ~aving fo~mulae (1) through (5) (1) (Rla)3Si~ 0-- Si~o5i(R18)3 H h~

wher~in h~ ~an be an integer from 2 to 35 and R
i d~*ined;abo w , ~ d~praferably R18 i~ methyl;

- ~18 l - Rls :
~ ~ ) (Rl~)3si - t - sli_ 9~ - o si_ osi (R18~3 wherein g' can ha~e a Yalue at least one and up to ~5 de~ignating the n~mber of repeat units, h' is an integer from 2 to 35, and R18 is a defined abo~e, and 40 preferably R18 is methyl;

:

WO93/21278 ~ -~; 2 i 3 2 2 0 I PCT~U~93~02~74 ~ 21 -(3) (Rl8)3S~ ti__o - - si X si~si(R18) 3 H Rl8 R18 ~, wherein j' can be an integ~r from 2 ~o 35, X and 10 R18 are defined above, and pr~ferably R~8 is methyl;

(4) HtRl8)25i ~ - Si ~ 5i(R18)~H
l18 wherein g is 0 or ~ nu~ber up to 35 and Rl~ is d@fined above, and preferably R18 is methyl; and R18 ~ R18 ~; 25 : (5) H - fi x fi ~ ~ ~ R18 Rls ::~: 30 : wherein~X and R18 ara as defined abo~e, and ~; ~ preferably R18.is methyl~ The polyhydrosiloxane Gros~;lir~er generally can be p2:e88nt in an amount in the r~ng~ o~ ~.l to~ 10, preferably 0.5 to 5, an~ most 35 pre~erably 0.5 to 2 weight percent based on vinyl co~taining silarylene loxane.
Other u~eful crssslinkers include silica particl~s ha~ing adsorbed ~nto their s~rfaaes compounds having at :~ : least two dimethylhydrosilyl groups; e.g., compound (4) : 40~ or (5~ above can ~e adsorbed onto silica particles.
The preferred concentration of polyhydrosilox~ne ~: cros~linker, having at least 2 hydrosilyl groups, is an ` amsunt ~hat provides at least one hydrosilyl group per vinyl group up to about three hydrosilyl groups per 45 vinyl group~

WO93/~1278 ,. ~i3~ PCT/USg3/0~074 Hydrosilation catalysts useful along with the polyhydrogensiloxane crosslinkers in the composition of the in~ention where R5 is a vinyl group are well known and include both thermal and photo acti~ated catalysts 5 such a~ the platinum complexes disclosed in U.S. Patent Nos. 4,288,345 and 4,510,094. Platinum complexes afford fast reaction and hence are preferred. Useful platinum containing catalysts disclosed in the aforementioned patents include, for example:
chloroplatinic acid, and , :
chloroplatinic acid-olefin complexes, (these two catalysts are available from Petrarch Systems Silanes and Silicone) platinum II-acetylacetonate (available fro~ Aldrich Chemical Co., Milwaukee, WI~
5-cyclopentadlenyl)trimethylplatinum, 5-cyclopentadienyl)t.iisopropylplatinum, and (trimethylsilyl-~5-cyclopentadienyl)trimethylplatinum (prepared as 20 dieclosea in U.S.~Patent No. 4,510,094).
: The:catalyst can be supported, anchored, or coated on a mi~ropàrticulate carrier such as alumina, sili~a or zirconia. ~The~`catalyst can be employed in an amount in the~range of from O.l to lO00 ppm (parts per 25 ~illion)~ of copoly~er compo`sition of the in~ention, preférably from:~:to 300:ppm. Catalysts not co~mercially~vailable can be prepared by methods described in ~.S. Patent No. 4,Sl0,094.
When R4 of Por~ula I is R5 and R5 is an oxirane 30 group containing organic group, there is present in the copolymer composition an epoxy resin curative. Epoxy re in curatives are well known in the art and include both catalysts and curing agents. A summary of useful curatives i8 given~in U.S. Patent No. 4,707,534.
35 Particularly useful epoxy resin curatives include amines such as ethylenediamine, diethylenetriamine, aminoethylene~hanolamine, diaminodiphenylsulfone, WO93/21278 21 3 ~ 2 ~ 1 PCT/usg3/02074 - 23 - .
dicyandiamide, organic acids such as adipic acid, and acid anhydrides such as phthalic anhydride. Generally, a mixture of the epoxy group-containing copolymer and curing agent preferably in stoichiometric amounts (i.e., one active amine hydrogen for each epoxide group) can be cured by heating at 20 to 2booc for 10 minutes tQ about 10 hours, preferably 1009 to 200C for 0~5 to 1~0 hour dependîng on the particular epoxide compound, curing agent, and the amount of material 10 being cured.
The epoxy group~containing copolymer can also be cured by catalytic agents which can be either thermally-activated or photoactivated.
Examples of the thermally activated catalytic 15 agents include BF~-amine complexes, benzyldimethylamine, and trimethylamine, which are commercially availa~le fro~ Aldrich Chemical Co.
: ~xamples of photoactivated cata}ysts include 4-::~ chlorobenzenediazonium~hexafluoxophosphate, ~` 20~diphenyliodonium~hexafluoroarsenate, and triphenyl hexa~luoroarsenate, which are commercially available from G.E. Other~photoactivated catalysts are well : known:and are taught in U.S. Patent Nos. 4,039,521, 4,069,955,:ana~4~,076,536. When a thermally activated 25 cat~lyst is e~ployed,~ from about 0.0l to 20 percent by weight, pref~rably 0.5 to 5 percent by weight, of catalyst ba~ed on the epoxy composition is used.
Within these catalyst concentrations, curing can be : made to proceed using lower temperatures ~e.g~, less 30 than 30 to -10C.~) or elevated temperatures (e.g., 3~
to 200C, preferably 50 to 100C.) to either subdue the exotherm of polymerization or to accelerate the p~lymerization. When a photoactivated catalyst is used,~ 0.0l to about 10 percent by weight of catal~st, , : 35 bafied on epoxy copolymer, is used. Curing is effected by exposing the catalyzed composition to any source of WO93/21278 , ~32Z~ PCT/US93/0~074 radiation emitting actinic radiation at a wavelength within the visible or ultraviolet spectral regions~
Silane compounds, which ~an be used to obtain terminated copoly~ers and ~hain extended copolymers are (R4)3SiZ and ~R4)2R6SiZ, wherein R4, R6 and Z are as defined above. Examples of suitable terminating (R4)3Si~ silanes include: chlorotrimethylsilane, chlorotriphenylsilane, and chlorodimethylvinylsilane, which are commercially available from Petrarch Systems lO Silanes and Silicones; ureidotrimethylsilan~, and reacti~e-gxoup containing silanes such as (3-acryloyloxy~propy1dimethyl-chlorosilane, 3-(2,3-epoxypropoxy)propylchlorodimethyl-silane, and phenyl{4-t3-(bis(dimethylamino)methylsilyl)propoxy~-15 phenyl}methanone. There is used about two moles of(R4)2R65iZ or tR4~35i~Z silanes per mole of hydroxyl terminated copolymer. ~ ~
: The:Formula~III silanes such as those described above as:6uitab1e~for use:in the preparation of the ~ 20 copolymer of Formula:IV can also be used as chain :~ extending silanes, e.:g., those having the formula (R4)2SiZ2. m ere~is then used about 0.95 to l.05 moles of (R4)2SiZ2 per~mole of hydroxyl terminated copolymer.
Following-the~chain extending reaction it is often 25 desir~ble to terminate~the polymer by reaction with terminating silanes ~(R4)2R6SiZ.
When the aopolymers of the invention are prepared by condensation of silarylene compound of Formula II
~:~ with silanes of Formula III in which either Y or Z is 30 halogen,~ the resuiting copolymer preferably has 50% of its siloxy groups present in units of one, 40% present in units o f two, and 10% present in units of three and the average n~mber of repeat units of siloxy groups (c in Formula IV) i~ 1~.7. The copolymer preferably has 35 50% of its silarylene yToups present in monads and the remaining 50% in diads or triads with the average ;::

W093/21278 ~ 213 Z 2 ~1 PCT/U593/D2074 number o~ rep~at units of the silarylene groups is 1.550 When the copolyme~s of the invention are pr~pared by condensation o~ bishydroxysilarylenes o~ Fo~mula II
5 with silanes of Fo~mula III in which Z is an amino group R
wherein each R is a linear or branched ~lX~l ~roup having ~ to 4 carbon atoms or both Rs to~ether can form an alkylene group having 4 to 8 carbon atoms, then the resulting copolymer preferably has 90% of its siloxy 15 group~ and 95% of i~s silarylene group~ present in ~onads an~ the remaining 10% of siloxy groups pres~nt in diad~ and the remaining 5% of silary}ene group in diads or .triad~.
:
When the~copoly~rs of the invention are pr~pared 20 by condensation oî a bishydroxysilarylene of Formula I~
with silanes of Formula III in which Z ic a substi~uted :~
ureido group :such as the N-phenyl~reido group~ then the :~ :resulting copolymer has alternatins silarylen~ and iIo~y~groups,'i.e., c in Formula IV is l.O. ~~
~ he cur~d~silarylen~ silox~ne copolymers o~ ~he .

~ in~ention when~pro~ided a~ a coating on a ~lex~ble :~: b~c~in~ ar~ particularly useful as elevated temperature re~istant pressure sensiti~e adhesive tapes. The cured P8A of the invention i~ ùseful as a layer bonding t~o 30 substrates together to provide a laminatedl structure.
~ .

~: The test procedures used in the examples to : ~valuate and compare the properties of the PSA
35 compo~itions and tapes made from them are industry standard tests. These tests are described in detail in :various publications of the American Society for W093m 278 ~3~0~ PcT/usg3/o2n74 - ~6 ~ -Testing ~aterials (ASTM), Philadelphia, PA and thePressure Sensitive ~ape Council (PSTC), Glenview, I~
References to these standards are also given.

5 Shear Strenath_~AST~LL~ L _8: PSTC - 7~
The shear strength is a measure of the cohe~iveness or internal strength of an adhesive. It is based upon the amount of force required to pull a~
adhe~ive strip from a standard flat surface in a 10 dir~ction parallel to the surface to which it has been affixed with a definite pressure. It is measured in units of ti~e (minutes) required to pull a standard area of PSA coated sheet material from a stainlass steel test panel under stress of a constant, standard 15 load.
The tests were conducted o~ adhesive coat~d strips ::~ applied to a ~tainle~s~ste~l panel ~uch that a 1~.7 mm y 12.7 mm portion of each strip was in firm contact with the panel with one end portion of the tape being :~ 20 fr~e. T~e panel with adhesive coated strip attached was held in a rack such that the coated surface of the panel forms ~n angle of 182 wi~h the Yertical tape ~x~e end which was then tensioned by application of a force of one kilogram applied as a hanging ~eight from 5~ the f~ee @nd o~ th~co~ted strip. The 2 qreater than 180 was used to ne~ate pe~l forces, thus ensurîng that only the shear forces were measured in order to more : accurately determin~ the holding p w er o~ the t~pe being te~ted. Time elapsed for each test specimen to 30 separate from the~ steel panel was recorded as the shear strength.
PP = ~op-off, i.~., 75-100% adhesive ~ailure from :~ steel platP - Pressure-sensitive adhesi~e compo itions derived from the inventive copolymers have shear 35 strengths exceeding 500 minutes at 22C and 50% R.H.

Peel Adhesion LASTM D 3330-78: PSTC - 1 ( 11175L!

-2~132~01 ~ 27 -The peel adhesion is the force required ~o remo~e a PSA coated test specimen fr~m a test psnel measured at a ~pe~ific angle and rate of removal. In the sxamples, this force is expressed in Newtons per 5 decimeter (N/dm) width of coated sheet. The procedure followed was: ;
1) A test specimen 25.4 mm wide was applied to a horizontally positioned clean glass test plate. A 2.2 kg rubber roller was used to press a 12.7 cm length of specimen into firm contact with the glass surfa~e.
2) The fxee end of the specimen was doubled back nearly touching itself so the angle of removal was 180~. The free end was attached to the adhesion tester scale.
3) The glass test plate was clamped in the iaws of tensile testin~ machine which was capable of moving the plate away from thè scale at a constant~:rate of 2.3 meters per minute.
4) The :scale~reading in Newtons was record~d as the tape was peeled from the glass surface.

Objects~and advantages of this invention are further illustrated~by~the following examples, but the 25 ~pà~ticular materials~and amounts thereof recited in ;these~:~exa~plesj:as~well as~other conditions and :detail~,-should~not~be~construed to unduly limit this invention.` Temperatùres are expressed in dPgrees centigrade and parts are parts by weight.
; 30: ~ ~ ~
Y~T~I8 OF ~ILAN~ CO~PO~ND8 : Bis(dimethylhydroxysilyl)benzene (Compound l) : : :
`bis~dimethylamino)diphenylsilane ~Compound 2) is(dimethylamino)dimethylsilane (Compound 3) 35 ~i~(dimethylamino)methylvinylsilane (Compound 4) methacryloxypropylmethyldichlorosilane ~Compound 5), , ~ .

`2132201 ~ 3 were obtained from Petrach Systems, Bristol, PA, and were purified and dried before use.
Preparations of bis(uriedo)methylvinylsilane tCompound 6), phenyl{4-~3-~bis(dimethylamino)methylsilyl)propoxy~-phenyl}methanone (Compound 7), and phenyl{~-~(3-methyldichlorosilyl)propoxy]phenyl}methanone (Compound 8) were prepared~according to the procedures described in Macromolecules, Vol. 12, 373, 1979.
Hydrosiloxane (DC-1107~, Compound 9) containing 35 repeat units were obtained from Dow Chemicals, Michigan.
Polymer molecular~weights were determined by gel permeation chromatographic analysis using polystyrene 15 as an internal standard.

Preparation of 1.3-bis~D-dimeth~lhydro~ysilYlphen~ 2-vinYl-1 1.2.3.3-Dentamethyltrisiloxane (Compound 10) 1,4-Bis(dimethylhydroxysilyl)benzene (Compound 1) ~19.6 g~, 0.0867 mole)~was placed in a weighed three-necked, 500 mL round-bottom flask and dried overnight in a vacuum oven~at~50-C. The flask was reweighed, fitted with a~thèrmometer, a mechanical stirrer, and a septum sealed opening.~ After the system was purged --25 ~with~nitrogen,~dry~200 m~tetrahydrofuran (THF) and 8.8 g (0.0867 ~mole);~of~p~yridine was charged to the reaction flask. A~solution of 6.069 g (0.0434 mole) dry vi~nyImethyldichoIo&iIane in toluene was added drop-wise o w r a period~of~three hours at 0-5C. The solution 30 was slowly allowed,to warm-to room temperature over a 12-hour period. The reaction mixture was filtered under reduced pressure to remove pyridine hydrochloride. ~The~product was freed from solvent and ilane and the~product was dried under vacuum to 35~ constant weight. The product was obtained in 85% yield :
~ and confirmed by spectral analysis to be 1,3-bis(p-:: :
~ ' WO93/2127~ 2 1 ~ 2 2 0 I pCT/U~93/~2074 dimethylhydroxysilylphenyl)-2-vinyl-1,1,2,3,3 pentam~thyltrisiloxane having the structural form~la CH3 IH3 fH3 l H3 IH3 HO - 5i ~ - Si - O - Si - O - Si ~ - Si - OH
C~3 CH3 CH-CH2 ~H3 CH3 8Y~E8I8 OF 8ILa~O~ AT~D gI~ARYLENE-~ILOA~
~2~Y~

1,4-Bis(dimethylhydroxysilyl)benzene (Compound 1 ~196 g, 0.867 mole) was placed in a weighed three-n~cked, 5000 mL round bottom flask and dried overnight in a vacuum oven at 50C. ~he flask was reweighed, fitt~d wi~ a thermometer, a mechanical stirrer, a~d a ~wo-outlet adapter supporting a reflux cbndenser and a 20 septum ~aled opening~ A~t~r the system ha~ been pu~ged with nitrogen, dry toluene (1000 ml) was added, a positive nitrogen pre~sure as established and th~
: reaction was: lowly heated to a gentle reflux ~g5 to 105C~. ~nder nitrogen atmosphere, about 69.6 g of 25 bis(di~ethylamino3diphenyl ilane ~Co~pound 2) ~nd : 26.7:~ o~ bi~(dime hylamino~dim~thylsilane ~Com~ound 3) ;`; wer~ ch~rged to the reaction flasX. Then, at ~ hour in~@rvals ~here ~as added 12.96 g (0.Q48 m~le~3 o~
~::Co~pound 2 and 4.67 g (0O032 moles) of Compound 3 until 30 1210 4 g ~0- 45 moles~ total of Compound 2 and 45.4 g (0.31 moles~ total of Compound 3 had been added ! ' providing 0O88 mole of aminosilanes per mole of arene, The reaction mixture was r.fluxed fQr an additional 10 houræ. The resulting polymer was slowly added to a 35 l~rge excPss methanol. After decanting the methanol, ~he product, a low viscosity tacky gum, was dried to a cons ant weight under vacuum at 80~C. The copclym~r was obtained in 80% yield (based on silanes used3. The nu~bex average molecular weight of the polymer was WO93/21278 PCT/U593/02~74 2132~01- 30 -52,000 as determined from g 1 permeation chromatographi~ analysis. Analysis o~ the copolymer by nuclear magnetic resonance, N~R, revealed that 90% of its siloxy groups and 95% of its silarylene groups were 5 present as singl~ units and the remaining 10% siloxy groups were pres~nt in units of 2 and the xemaining 5%
of silarylene groups were present in units of 2 or 3, and in some instances may be up to 6. The copolymer had the approximate formula:

CH3 CIH3 ~ CH3 H~E~Si~_ si~si~si~--H
CH3 CH3 (~ r C~3 t : in which r is 0.5, s ~s 0.4, and t is 135.
: 20 Pre~olYmer B
The procedure for the synthesis of the copolymer ~: was the same as in prepolymer A except that the ratio 25 b~tween Compound 2 and Compound 3 was 0.75 to 0.25 and the ratio between diol ~o silanes was 1.0 to 0.91. The resulting polymer was slowly added to a large excess of methanol. After~ecanting the me~hanol, ~ e product, a low vi~co~ity tacky ~um, was dried to a constant weight : 30 under ~acuum at 8UC. The copolymer was obtained in 75~ yield (based on ~ilanes used). The number average . molecular weight of the polymer was S5,000 and its . approximate formula was the same as that of Prepolymer A in which r is 0. 7, s l5 0 . 23, and t is 150.
~: PreEcly~
The procedure for the synthesis of the copolymer was the ~ame as in prepolymer A except that the ratio between Compound 2 to Compound 3 was 90:10 and the 40 ratio between diol to silanes was 1.0 to 0.95. The re ulting polymer was slowly added to a large excess of WO93/21278 PCT/U593/02074 .
. .
. - 31 -methanol. After decanting the methanol; the product which was a low visc05ity gum was ~ried to a constant weight under vacuum at 80C. The copolymer was obtained in 82% yield (based on silane~ used). The 5 number average molecular weight of the polymer was 64,000 and its approximate formula was the same as that of Prepolymer A in which r is O.85, s is O.l, and t is 165.

10 Pre~ol~mer D (comparative) The procedure for the synthesis of the copolymer was the same as in prepolymer ~ except that the ratio be~ween Compound 2 to Compound 3 w~s 50:50 and the ratio between ~iol to silanes was l~O to 0.93. The 15 resulting polymer was slowly added to a large excess of methanol. After decanting the methanol, the product, a ~: low viscosity non-taoky polymer, was dried to a :: constant weight under vacuum at 80C. The copolymer was obtained in 80% yield ~based on silanes used). The ~: 20 numb~r aYerage molecular weight of the polymer was 42fO~O and it~ a~proximate formula is ~he same as that of Prepolymer A:in which r is 0.5, s is 0~5, and t is : 120.

25~ O~C~L~R WDIG~T:S~RY~N~-8ILOXaNB F~C~IO~
~y~8 ` : ; a) Preparation~of_hiqher_molecular silaFylene ilQ~ne ~olymer fr~m hydroxy termin~ted silarylene-ilsxane prepo~vmers_w-th di~ferent dichlorosilanes Prepolymer A (20 g, 2.9 x 10-4 mole) was weighed ~: int~ a 500 ml one-necX flask containing a magnetic ~ ætirrer~ The flask was vacuum pumped at 100C
: : overnight to dry the sa~ple. The flask was septum 35 ~eal~d under nitrogen and cooled to 0-5C; 150 ml of dry tetrahydrofuran was added. The contents were all~wed to dissolve. The polymer solution was slowly .

WO93/21278 2 13 Z 2 0 1 PCT/US~3/02C74 stirred under a nitrogen blanket.
Methacryloxypropylmethyldichlorosilane ~Compound 5) (0.08 g, 3.3 x ~0~4 mol) in 10 mL of dry tetrahydrofuran was slowly titrated into polymer solution until the 5 polymer solution became very viscous. Th~ polymer mass was back titrated with bis(dimethylhydroxysilyl)benzene (0.04 g, 1.7 x 10-4 mol) in 10 ml of tetrahydrofuran over 6.0 hours to ensur~ that the polymer was terminated by silarylene units. The polymer was 10 precipitated in excess of methanol; the methanol was decanted and the product, a tacky gum, was dried in a vacuum oven at 80C~ The weight a~erage molecular weight of the copolymer was 550,000 with a dispersity of 1.$ and it had the approximate formula:

Ju~

:
: 15~in which r = 0.5, s~`= 0.4, t = 135, u = 10.5, R6 = OH, and .::

20~ ~

: : b) The above procedure was repeated with ~; prepolymér B to obtain tacky silarylene-siloxane 25 copolymer containing methacryla~e pendants having a weight average:molecular weight of 520,000 with a : dispersity o~ 1.9 and an approximate formula the same : a~ copolymer ~lA in which r = 0.7, s = 0.23 and t is :::

WO93/~1278 2 1 3 2 2 0 1 PCT/~S93/~074 - 33 - :
O :'' 150, R5 is ~CH2~30C-C=CH2, R6 is OH, and u was 9.
c) The procedure (a) was repeated with prepolymer :~
C to obtain tack~ silarylene-siloxane copoly~er containing methacrylate pendants having a weight 10 average molecular weight of 440,000 with a dispersity of ~.1 and an approximate formula the same as that of copolymer la in which r - 9.8~, s is 0.1, t is 165~ R5 ~ .
and R6 were the same as for copolymer la and u is 6.8.
d) The proc~dure ~a) was repeated with prepolymer 15 D to obtain non-tacky silarylene-siloxane copolymer containing methacrylate pendants having a weight-~verage of 590~0~0 with a dispersity.of 2.5. This was a co~parative poly~er having less than 55 mole ~ of aryl groups in R4. It had àn approximate formula the 20 ~ame as that of copolymer la but in which r = 0.5, s - :`
0.5, t = 120, and u = 14.
e) T~e procedure (a) was repeated by substituting phenyl~4-~3-methyldichlorosilyl)propoxy~phenyl}-me~hanone (Co~pound 8) for methacryloxypropylmethyl-: 25 dichlorosilane to obtain tacky high m~lecular weight ~: silar~lene-siloxane copolymers containing be~zophenone : ~ p~ndan~ unit~. Th~ weight aver~ge molecular weighk of :~ ~he copolymer was 650,000 with a dispersity of 1~8.
:The polymer obtai~ed had ~n approximate formula that .
: 30 :was the same as that of copolymer la except that r -0.5 to 0.6, s = 0.4, t - 135, and R5 is ; CH

, ~ --sio-- ' (CH2)3 ~ -C ~ , R6 was OH, and u was 12. :
: f) Methyl~inyldichlorosilane was used for methacryloxypropylmethyldichlorosilane in procedure (a) ~ 213220~ ~
WO93/2127~ ' PCT/~S93/02074 ,~ . .

to obtain a tacky high molecular weight copolymer containing vinyl pendant units.

xamPle 2 a? Preparation of hiaher molecular silarvlene-siloxanel~lYmer rom hYdrox~ rmin~a~d s larylene- ~
siloxane ~repoly~ers with d fferent bis(ureido)silanes Prepolymer A ~20 g, 3 . 9 x 10-4 mole) was weighed into 500 mL one-neck f lask containing magnetic stirrer.
10 The flask was vacuum pumped at 100C overnight to dry the sample. The flask was septum seal~d under nitrogen and cooled to -10 to ooc; 150 mI, of dry chlorobenz~ne was added. The polymer dispersion was slowly stirred under nitrogen blanket. Bis(ureido)methacryloxypropyl-15 methysilane (0.08 g, 1.45 x 10-4 mol) in 10 mL of dry chlorobenzene was slowly titrated into polymer solution `~ until the polymer solution beaame vsry viscous. The polymer mass was-back~titrated with bis(dimethyl-~hydroxysilyl)benzene (0.04 g, 1.7 x 10-4 mol) in 10 mL
20 of tetrahydrofuran over a period of 6.0 hours. The polymer was precipitated in an excess of methanol; the methanol was decanted and the product, a tacky gum, was ~:~dried in a vacuu~ oven at 80C. The weight average molecular weight~:of:the copolymer was 840,000 w~th a 25:di~persity of 2.~6. It;had an approxi~ate copolymer th sia~e as that of ~copolymer la except that u was 16.
b) ~he prooedure in Example 2a was repeated with prepolymer D to obtain a non-tacky silarylene-siloxane copolymer containing ~ethacrylate pendants having a ! 30l weight average !molecular :weight of 590,000 ~ith a : ; dispersity of 2.5. This polymer was a comparative ~xample.
c) Bis(ueido)methyl~inylsil~ne was used for bis(ueido)~ethacryloxypropylmethylsilane in procedure ~:~ 35 (a) to obtain a tacky high molecular weight copolymer ~ :containing vinyl pendant units.

:

WO93/21278 2 i 3 2 2 01 PcT/us93/o2o74 , ~

E~ ' a) Pre~aration of hiqher molecular sil~rYlene-siloxane pol~m_r from hYdroxv terminated slly~yl~D-=
siloxane pr~polymers with different 5 bis(dimeth~laminoL~ilane5 Prepolymer A (20 g, 3.9 x 10-4 mol) was..~weighed into 500 mL two-necked flasX containing a magnetic stirrer~ The flask was vacuum pumped at 100C
overnight to dry the sample. The flask was septum lO sealed to one neck and the other was fitted with a reflux condenser. Positive nitrogen pressure was maintained throughout the course of the reaction.
About 150 mL of dry toluene was added. The contents were allowed to dissoIve.
Bis(dimethylamino)methylvinylsilane (0.08 g, 5.06 x 10-4 mol) in lO mL of dry toluene was slowly added into polymer while refluxing the mixture at 95~105C until the polymer sclution became very viscous. The polymer ~: maæs was back titrated.with bis(dimethylhydroxy-20 silyl)benzene (0.04 g, 1.7 x 10-4 mol) in 10 mL of tetrahydrofuran over 6.0 hours. The polymer was precipitated in an excess of methanol; the methanol was decanted and the product, a tacky gum, was dried in a vacuum oven at &0C. The weight average molecular --25 wei~ht of the copolymer was 580,000 with a di~persity of 2.2.~ The copolymer had an approximate formula the : same as that of copolymer la except that R5 was -CH--CH~
and u was 11~5.
b) The above procedure was repeated with ~ 30 prepolymer 8 to obtain a tacky silarylene-siloxane : ~ copolymer containing vinyl pendant units having a weight average molecular weight of 750,000 with a di~persity of 2.4. The copol~mer had an approximate formula the same as that of copolymer lb except that RS
:: :
35 ~as -~HaCH2, and u was 11.
~;: c) The procedure (a) was repeated with prepolymer C to obtain a taGky silarylene-siloxane copolymer :

W093f21278 PCT/US93/02~74 containing ~inyl pendant units having a weight average molecular weight of 650,000 with a dispersity o~ 2.4.
The copolymer had an approximate formula the same a~
that of copolymer lc except that R5 was -CH-CH2, and u 5 was 10.
d) The procedure (a~ was repeated wit~ prepolymer D to obtain a non-ta~ky ilarylene-siloxane copolymer containing vinyl pendant units having a weight average molecular weight of 510, 000 with a disper~ity of 2.3, 10 which was a comparativ~ polymer. The copolymer had an approxi~ate f ormula the sa~me as that of copolymer ld ~xoept that :R5 was -CH----CH2 and u was 11.
e) ~he procedure (a3 was repeated by substituting phenyl{4~[3-((bisdimethylamino)methylsilyl~-15 propoxy]phenyl}-methanone for bis(dimethylamino)-~e~hylvinylsilane to obtain tac~y high ~olecular weight silarylene-siloxane copolymers containing benzophenone pendant units. The w~ight average molec~lar weight of t~e aopolymer was 490,000 with a dispersity of 2.6.
20 The copoly~er~had an approximate ~ormula ~ e same as i tha of copolymer le~except that R5 was 0~
: Z5 ~ O ~ ~2t3 and u was 9.

30 S~n~hesis of silarylene-siloxane random copolvmer Containi~n~L pendant~vinyl units : ~ 1,4-bis(dimethylhydroxysilyl)benzene ~Compound 1) : : (19.6 g~ O.OB67 mole)~ and silarylene condensate :~Co~pound 10) (0.4 g, 0.0008 mole) were placed in a 35 weighed thre2-necked, 500 mL round-bottom flask and dried overnight in a vacuum ovPn at 50C. The flask wa~ reweighed, fitted with a thermometer, a mechanical stirrer, and a two-outlet adapter supporting a reflux ~;

WO g3/21278 2 1 3 2 2 0 1 Pcr/usg3/02074 conden~er and a ~eptum sealed opening. After the sy~tem had been purged with nitrogen, dry toluene ~200 mL) was added, a positive nitrogen pressure was established and the reaction was slowly heated to a 5 gentle re~lux (9S to 105C). Under nitrogen atmosphere, about 14.18 g o~ Compound 2 ~0!062 mole) and 7.07 g of Compound 3 (0.040 mole) were charged to the rea~tion flask. The reaction mixture was refluxed for 10 hours, and then slowly poured into a large 10 excess of methanol. After decanting the methanol, the product, a tacky gum, was dried to a constant weight under ~acuum at 80C. The copolymer was obtained in 80% yield (based on silanes used). The weight average molecular weight of the polymer was 250,000 with a 15 dispersity of 1.5.

` PREPARATlON OF PR~8~URE-8EN8ITIV~ AD~E8IV~B
; xam~le 5 :: Into a solution of 5 g of the copolymer prepared 20 in Example la, above, in 10 mh of toluene was added 0.1 g of 2,2-dimethoxy-2-phenyl acetophenone (Irgacure~651, ~:~ Ciba-Geigy, Hawthorne, NY) and the solution was knife-~: coated onto biaxially oriented poly(ethylenetere-~: ph~halate) backing; dry coating weight was 3.8 mg/cm2.
, 25 The solvent was ~vaporated at room te~p~rat~re and the hand spread was heated at 150C for S minutes. The layer of copolymer was cured under low intensity W
lights for five minutes. After conditioning overnight ; .
at constant temperature (22C) and humidity (50% ~H);
30 the peel adhesion of the pressure-~ensitive a~hesive tape obtained was determined according to the procedure ~: de~cribed above. The tape had a peel adhesion from :: : glass of 35 N/dm with a shear of 1000+ minutes.

35 Exam~l~ 6 A ~olution of 5 g of the copolymer pr~pared in Example lf) in 10 mL of toluene was knife-coated onto 213~201 W093/21278 , PCT/US93/0 074 .

polyester film~ The layer of copolymer obtained was cured in an RPC processor ~odel #QCl202 ANIR (available from ~PG Industries, Chicago, IL) at 30 cm/sec with ~wo standard medium pressure mercury vapor lamps operating 5 at 80 watts per centimeter. The lamps were located approximately 9.5 cm from the adhesive surfa~e. ~ ;, Multiple passes through the proceæsor were used to increase the degree of cure with no delay between ::
subsequent passes. The total dose was 600 mJ/cm2.
lO Aft~r conditioning overnight at constant temperature (22C) and humidity (50~ R~), the peel adhesion of the tapes obtained was measured. The tape had a peel adhesion from glass o~ 30 ~/dm with a shear of 550 minutes with pop-of f f ailure .
Examl~le 7 : A solution of 5 g of the copolymer of ~xamp~e 3e) in~10 mL of toluene~wa~ knife-coated onto polyester : film.: The layer of copolymer:obtained was cured in an 20 RPC processor under high inten~ity W with a dose of 600 mJ/:cm2. Af~er conditioning overnight at constant temperature (22C) and humidity ~50% RH), peel adhesion : from glass of the tape obtain~d was measured. The tape had a peel adhesion from glass of 30 N/dm with a shear 2~5~ of 55Q minute with:pop-of~ failure.

: : EX~glLle 8 : A solution of 9.g5 parts of copolymar prepared in Example 2C) and 0.05 parts of hydrosiloxane Compound 9 3~ and 250 ppm of cy:clopentadienyltrimethyl platinum were ~dissolved in 30 parts of toluene. The polymer solution vbtained was then coated:using a hand spread coater.
he oopolym~r coating was cured in RPC processor under high intensity W with a dose of 600 mJ/cm2. After ~ ;
35 conditioning overnight at constant temperature (22C) and humidity (50% RH), ~he peel adhesion o~ the pre~sure-sensitive tape obtained was measured. The ~' :

~322ol :
WOg3t21278 PCT/~S93/OZ074 tape had a peel adhesion from glass of 28 N/dm with a .
shear of 1550 minutes with pop-off failure.

Examles 9 - 12 :
The curable PSA compositions from Examples 5, 6, 7, and 8 and using the procedures disclo~ed..therein were coated onto Kapton~-H polyimide backing (Dupont), and were aged at 300C for 24 hours in air. The cured PSAs showed no change in peel adhesion as compared to 10 unaged cured PSA samples of Examples 5, 6, 7, and 8, indicating their utility for high temperature application.

Various modifications and alterations of this 15 invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth herein.

Claims (10)

CLAIMS:

1. A crosslinkable silarylene-siloxane pressure sensitive adhesive copolymer composition comprises a copolymer comprising a backbone having randomly arranged silarylene units and siloxane units, of which siloxane units at least 55 mol percent are arylsiloxane units, said copolymer comprising at least 0.05 mol percent crosslinking functionality.

2. The composition according to claim 1 wherein said silarylene group of said copolymer has the formula wherein R3 is independently a lower alkyl group having 1 to 4 carbon atoms;
Ar is an arylene or alkylenearylene group having 6 to 20 carbon atoms, and said siloxane group has the formula wherein each R4 is an organic group independently selected from aryl groups having 6 to 12 carbon atoms, linear and branched alkyl groups having 1 to 6 carbon atoms, of which R4 groups 55 to 95 mol % are aryl groups, 5 to 45 mol % are alkyl groups, and 0.05 to 5 mol % are R5 groups; and R5 is a functional crosslinking group selected from organic groups containing a) an ethylenically-unsaturated group selected from 1) groups crosslinkable under the influence of free radicals, and 2) groups crosslinkable in a hydrosilation reaction with copolyhydrosilane, b) an oxirane group, and c) a group that is photoinitiator of crosslinking with the provisos:
(1) that when R6 is not R5, then at least 0.05 mol percent of R5 is at least one of R4 or R6, (2) that (a) when R5 is an acrylic group there is present in the composition a sufficient amount of an initiator of free radicals to effect polymerization, (b) when R5 is a vinyl group attached directly to a Si atom there is present in the composition a sufficient amount of polyhydrosiloxane and a sufficient amount of catalyst for a hydrosilation reaction, and (c) when R5 is an oxirane-containing group there is present in the composition a sufficient amount of epoxy resin curative, and (d) when R5 is a photocrosslinker there is sufficient amount of photocrosslinking group present in the composition to crosslink the copolymer.

3. The silarylene-siloxane copolymer composition according to any preceding claim which is curable to a pressure-sensitive adhesive comprising a copolymer having a general formula wherein R3, Ar, and R4 are as previously defined, and c is a number having a value of 0.8 to 1.2 expressing the number of siloxane groups per arylene or alkarylene groups;
d is a number having an average value of 50 to 500;
e is a number having a value from 1 to about 200;
and each R6 is a terminal group.

4. The composition according to any preceding claim wherein Ar of said copolymer is a phenylene or biphenylene group, optionally substituted by lower alkyl (C1 to C4) groups.

5. The composition according to any preceding claim further comprising an effective amount of at least one catalyst, initiator, or curative to effect crosslinking.

6. The composition according to any preceding claim wherein the crosslinking functionality is a photocrosslinking group selected from the group consisting of , , , and .

7. The composition according to claim 1 wherein said backbone comprises no more than six consecutive units of either siloxane or siloxylene units.

8. The crosslinked composition according to any preceding claim.

9. The composition according to claim 8 which is a coating on a flexible backing or which is incorporated in a laminate comprising two or more substrates, there being between each of the substrates a layer of said cured composition.

10. A process for preparing silarylene-siloxane copolymers of any preceding claim comprising the steps of a) condensing one or more a silarylene compound having the structural formula with a diorganic group substituted silane having the structural formula in which R3, R4, and Ar are as previously defined and Y
and Z are mutually reactive groups which independently are hydroxyl or a hydrolyzable group, b) optionally, reacting said silarylene-siloxane copolymer with a chain extending silyl compound to provided a copolymer having a weight average molecular weight of at least 500,000, and c) optionally, curing said copolymer to provide a crosslinked copolymer.