CA2214678A1

CA2214678A1 - Diblock and triblock polydiorganosiloxane-polyurea block copolymers

Info

Publication number: CA2214678A1
Application number: CA 2214678
Authority: CA
Inventors: Charles M. Leir; William R. Bronn
Original assignee: Individual
Current assignee: 3M Co
Priority date: 1995-03-24
Filing date: 1996-02-14
Publication date: 1996-10-03
Also published as: KR100375798B1; EP0815154B1; KR19980703183A; WO1996030426A1; DE69603357D1; US5670598A; JP3780324B2; JPH11502560A; DE69603357T2; MX9707094A; EP0815154A1; US5792554A

Abstract

Diblock (B-A) and triblock (B-A-B) polydiorganosiloxane-polyurea block copolymers comprise non-functional polydiorganosiloxane endblock B and polyurea block A. When used to provide release coatings, the block copolymers allow for easier release compared to traditional block copolymers of the (AB)n type having comparable amounts of polydiorganosiloxane. Articles incorporating the copolymers as a release material are also disclosed.

Description

D~RT OCK ANl~ TRIBLOCK PO~ IORGANOS~O~ANE POLYUREA
R~)CK COPOLYMERS

FrF~ n OF T~F INVF.l~TION
The present invention relates generally to polydio,~l-os;l~Y~nP-polyurea m~t~.ri~l~ and, more spec-ific~l1y~ to diblock and triblock copolymers thereof.
The invention further relates to release materials based on these block copoly.l.ers as well as various articles com~ri~in~ the block c~polymers.
10 BACKGROUND OF THE INVENI~ON
S~U1G sensitive adhesive (PSA) articles such as tapes, labels and other types of PSA-coated sheets, often require the use of either a release liner or ab~r1~inE having a low adhesion b~r~i7P- (LAB). Release liners and LABs provide a surface to which the adhesive does not pe~ n~ y adhere, so that the 15 adhesive releases th~lerl~ l prior to use.
A b~rkin~ having a LAB is particularly useful for providing an adhesive article such as a tape in roll form. In this case, adhesive is coated onto the side of the b~r~ing opposi~ the LAB so that when the adhesive coated b~cl~inE is rolled, the adhesive contacts the LAB. The adhesive adheres well enough to the 20 LAB so that the roll does not come undone or "tcle~ol)e", yet not so well that the tape cannot be unrolled.
Release liners may be used in a variety of ways to provide numerous types of adhesive articles. In some cases, the release liner function~ as a su~o,l for a layer of adhesive. For eY~mr'~, a layer of adhesive may be coated onto thet 2~ release surface of the release liner to provide a transfer tape. In this case, the b~r~ e of the release liner may also have a LAB so that the t~ansfer tape may ~ be provided in roll form. In other cases, the release liner functions as a protecli~e surface for the adhesive. For eY~mpl~, the release liner may be releasably adhered to the adhesive surface of a tape, label or other adhesive W 096/30426 PCTrUS96/02083 article. The release liner is slli~ped from the adhesive article prior to application of the article to a surface.
The release liner or LAB comprises a release coating which is e~pecled to provide an ap~rop~ e level of release from the adhesive of interest. The level 5 of release is measured by the ~mount of force r~uiled to remove the release liner or LAB from the adhesive. Release levels within the range of 1.0 N/dm to 40 N/dm are typical for LABs used to provide adhesive articles in roll form.
Release levels below 2.0 N/dm are ~Pner~lly pr~fe.led for release liners to provide smooth and easy release and are considered to be "premiumH.
Release co~ting~ may comprise a wide variety of m~teri~l~ such as ~ilir4~lPS, epo~y~;lironP-s, polyolefins (such as polyethylene and polypr~ylene), fluorocarbon polymers, acrylic polymers and copolymers, urethane polymers and copolymers, and the like. Further ~i~U~ion of release co~ting~ can be found in ~ntihook of Pl~ U~ Sensitive Adhesives, Satas, 1989, Van Nostrand Reinhol-l~
pages 585-626.
One type of release coating that is known to be suitable for a wide variety of PSAs comprises polydior~nosilo~nP-polyurea sPgmP-nt~ block copolymers of the (AB)n type. U.S. Patent No. 5,214,119 (Leir) describes such an (AB)D
se~ nl~ block copolymer whe.~l A replese~ an polydiorganosiloxane sPPmtont and B ,~.esen~ a polyurea segmPnt This reference discloses that the ~e~mPnt~ copolymers may be tailored to have a wide range of release pro~ lies through variation in the ratio of segmPnt~, the nature of the chain eYtPnd~Prs used to form the sPgmPnt~, and the mol~~ r weight of the polydio,~,~no~;loY~n,o segm~nt While the aforennP-ntionP~d release c~ting~ based on (AB)n block copolymers have proven acceptable for numerous applications, other release co~ting~ providing advantages over the prior art are sought.

SUMMARY OF THE l[NVF~TION
The present invention provides ~7.ihln~7~ (B A) and triblock (B-A-B) polydiol~nc.~;loY~nP-polyurea block copolymers which may be used, for example, to provide release m?tPri~l~ In gPne7~ U1~S of diblock and S triblock copolymers are typically provided, the ~ ult preferably being predo...i~-~..lly triblock (B-A-B) copolymer. In these block copolymers, B
compri~s a non-functional polydior~no~ilQ~Y~np endblock and A comp7i~es a polyurea block. As used herein, the term "non-f ~nrtion~l" means that the block is non-reactive to isoc~ ale. The term Hpolyurea block" is d.~fins~,7 as a block10 having at least one urea, w~ e, or thiourea moiety ~tt~<~h~ to the block.
Surpri~in~ly, diblock and triblock copolymers of the present invention can provide unique advantages over (AB)n type block copolymers where the polydiorganosiloYAane block (B) is typically int~rn~l to the block copolymer. For eY~mple, when release co3tin~S are p,~ ed, the B-A diblock and B-A-B
15 triblock copolymers aUow for easier release co---~ed to traditional block copolymers of the (AB)n type having col..pa~able amounts of polydior~nosiloY~ne. Furthe~mol~, block copolymers of the present invention comprising relatively low levels of the B s~ t provide release levels that are typicaUy only e~hibited by 100% silicone release co~tingS~ Furthermore, the B-20 A diblock and B-A-B triblock copolymers may be readily tailored for specific appli~tion~ by ~ncol~l~ g various groups into the A slo~mP!nt This ability to tailor the block copolymer aUows it to be used in a variety of applif~tion~
incl~din~, for e~mp7e, l,lot~~ e c~ting~ and prolec~i~e flms.
In one e~nhoJim~qnt diblock and triblock copolymers of the present 25 invention may be described by the formula B-A-X wherein B comprises a non-functional polydliorganosiloxane endblor7~, A compr~ s a polyurea block, and X
~ is sel~t~d from the group con.~i~ting of hydr~gen, a non-funrtion~lpolydior~nosilos~ne en-.7bloc7~, or an isocyanate 7~r7ir~1. More preferably, B has the structure:

W 096/30426 PCTrUS96/02083 R~ ~--~i ~--~i Y ~ ;
R~ R ~n R D
and A has the ;,llu~ilul~;

O O
C--I--Z--Nl--C--A'--B'--A' H H _m In the case of the diblock, X is hydr~ge. or has the structure:

C--~1--Z--N=C=O
H

10 In the case of the triblock, X has the structure:

O O ~ ~ ~
C-~--Z--~-C-~-Y--Si-O Si-O--Si-R
H H D ~ ~ n ~

In all of the structures pr~nlRd above, D, Y, R, n, m, Z, A' and B' are defined as follows:~5 each D is individually s~l~t~ from ~e group con~i~ting of hydrogen, an allyl radical having from 1 to 10 carbon atoms, and a phenyl radical;

W 096/30426 PCTrUS96/02083 each Y is individually s~l~ct~ from the group concistin~ of an aLkylene radical having~rom l to lOcarbonatoms, anarallylr~ 1, andanarylradical;
each R is individually s~1~t,Yl from the group conc;cting of a monovalent alkyl radical having from 2 t~ 12 carbon atoms, a ~slilu~d aL~cyl radical S having ~rom 2 to 12 carbon atoms, a vinyl radical, a phenyl r~<lic~1, and a s~bstitl-~ phenyl radical, with the proviso ~at at least 50% of the n~mber of R radicals are methyl;
each n is an integer which is 5 or g~
m is an integer which is l to about 25;
each Z is s~ cl~d from the group con~icting of aromatic, aliphatic, ~ra1irh~tic and cyclo~1irh~tic divalent r~rlir~l.c;
each A is se1~cb~d from the group concictin~ of -O-, -N- and -S- where G is G
s~ct~ from the group concicting of hydl~gell, an alkyl radical having from l to lO carbon atoms, a phenyl radical, and a radical which when combined with B forms a heterocycle; and each B is s~-l~t~ from the group concicting of aromatic, ~1irh~tic~ ar~1iph~tic and cycloaliphatic ra-lic~1c, polyethylene oxide, poly~r~ylene oxide, polylenA---Pthylene oxide, polyethylene adipate, polycaprc~1~~tone, polybut~liPnp7 polyamide, polyci1OY~ne, ~ ul~s thereof, and a radical co~llp'~'ing a ring sllu~;lure with A' to form a he~.~;ycle.

It is noted that when D, Y, R, n, Z, A and B appear more than once in the diblock or triblock structure, ~ey may be the same or dirrerenl.
.

W 096/30426 PCTrUS96/02083 I~ef~ldl)ly, each D is a hyd~en; each Y is sel~tPcl from the group cQn~i~tin~ of alkylene r~ir~1~ having from 1 to 10 carbon atonls, more preferably having 1 to 3 carbon atoms, most preferably propylene; each R is methyl; each n is a mlmher from 40 to 400; m is a nllmher from S to 15; each Z
S is individuaUy ~lectPd from the group con~i~ting of k~ ylene, methylene bis-(phenylene), lG~dlntlhyl xylylene, isophorone, tetramethylene, cyclohexylene, and methylenedicyclohexylene; and A' is SPl~P~tP~l from the group-N- and -~.

The present invention also provides release m~t~.ri~l~ comprising these diblock and triblock copolymers and articles comprising said release m~Pri~
The article may comprise a b~rl~ing having at least one layer of release m~tPri~15 applied thereto. The article may further comprise an adhesive layer coated onto the b~cl~ing. The adhesive layer may be coated onto the side of the backing opposite the release m~tPri~1, or directly on the release m~tPri~1 The present invention also provides a l~ le construction wll~.Gin a release liner is removably adhered to an adhesive article such as a tape. Preferably, the 20 adhesive is a rubber resin adhesive or other adhesive having a low acid content of less than about 2% by weight.
DFTAILED DESCRIPIION OF THE INVENTION
The B-A diblock and B-A-B triblock copolymers of the present invention may be produced by mixing, under reactive con~itions~ a mo~ ...;n~P--functional 25 polydiorganosiloy~np~ a ~ and/or dihydluAy chain eYtP-n~ler and a diiso~;y~lale. The non-function~l polydior~nosilc x~ne te- Illin~l se~ -nt is derived from the mon~minP-filn~tion~1 polydic,~lo~iloxane, while the polyurea se~mPnt is derived from the diisocya"ale and ~ mine and/or dihyd,vAy chain eYtP-nder. The colllbilled molar ratio of mono~lllinp-functional 30 polydior~nosiloY~nP and ~i~mine and/or dihydruAy chain eYt~n~e~ to W 096/30426 PCTrUS96/02083 diis~nate in the reaction is that suitable for the form~tion of a block copolymer with desired p~ L~s. Pl~f~dbly the ratio is ~ in~ ~l in the range of about 0.95:1.0 to 1.0:0.95, with 1.0:1.0 being most ~fef~led.
Mon~minr--runcl;ol-~l Polydiorp~n~ siloxane S l~e mon~min~-funrtion~l polydio~A~-os;loY~n~ has the following general structure:
IR - R - R
R--Si ~$i ~Y N--H
IR - R - n R D

wherein D, Y, R and n are defined above.
The mo~ -functional polydior~nocilnY~nP can be p,e~a,ed by a 10 variety of mrth~s. A useful means of synthrAi7ing such m~tr.ri~lc iS via a pl~tinllm catalyzed hydrosilation reaction of a mono-SiH-~e- IllillAled polydior~nociloYane and an alpha-olefinic alkylamine co.ll~und. This method is des~rihed by Clouet et al. in Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 31, 3387-3396 (1993). Care should be eYercised during the 15 p~e~- .li~n of the mon~min~-functional polydior~nosiloY~n~- to avoid side re~rtionc which could lea~ to undesired impurities in the m~tPri~l which will carry over into the final block copolymeric products. For example, -SiH groups may hydrolyze in the presence of water and the pl~tin~lm catalyst to form silanol groups. These silanol funrtion~l polydiorg~nosiloY~nes could be impurities which20 could adversely affect the elastomeric ~ro~llies and release char~cterictics of the diblock and triblock copolymers formed. A ~ cucciQn of the ~eleterinus effects such silanol te, ...in~ted species can have in ~lasl,."eric silicone-polyurea block copolymers can be found in U.S. Patent No. 5,290,615 (Tushaus et al.) A ~Ç~d means of pre~i.lg the mon~min~functional polydio~nncilox~n~o can be found in U.S. Patent No. 5,091,483 (Mazurek et W 096/30426 PCT~US96/02083 al.). This method involves the use of an amine-s~sliluled fluorosilane to t~.,lil-atG the anionic polymP~i7~tion product of a cyclic siloY~ne monomer.
n~ t~
Any suitable organic diiso~;y~ate, such as an ar~ alic, cycloaliphatic, S ~lirh~tic, or araliphatic diisocy~alG, may be used either alone or in IllLl~lUlGS of two or more. Suitable aromatic diis~;yai~al~s include 2,4-toluene diisocyanate, 2,~toluene diisocya,~ale, a dimer of toluene diis~;y~ate (available under the tr.1P.m~rk DP~modllr'M IT from Miles ~o~ting Division), diphGI~yl~ ç
4,4'-diisocyanate (MDI), 1,5-diis<~iya,~ato-n~l)h~t ~lPne, 1,4-phenylene 10 diisocyal ale, 1,3-phenylene diiso-;y~ alc, and IlliAlules thereof.
F~ PS of useful cyclc~liph~tic diisocy~lates include dicyclohexylmPth~ne diiso~;y;lnate (Hl2MDI, commercially available as DesmodurlMW from Miles Coating Division), isophorone diisocyanate (IPDI), 1,4-cycl< hP~nP diis~;y~ale (CHDI), 1,4-cyclohP~nebis(methylene isocyanate) 15 (BDI), 1 ,3-bis(is~y~at~ ethyl)cycloh~ A~e (H6XDI), and mixtures thereof.
FY~mr'~s of useful aliphatic diisocyanates include hP.~metllylene 1,~
diisocyanate (HDI), 1,12 dodP~nP diiso~;y~ale, 2,2,4-trimethyl-he~mPthylene diiso iy~ate (TMDI), 2,4,4-trimethyl-hPY~methylene diisocyanate (TMDI), 2-methyl-1 ,5-pent~methylene diisocy~nal~, dimeryl diisch~y~ate, urea of 20 hPY~mP~hyl diis~;y~al~, and llliAtUl w thereof.
FY~mp'ns of useful araliphatic polysiso~yd,lales include m-b~tr~methyl xylylene diisocyanate (m-TMXDI), p-tet~mPthyl xylylene diisocyanate (p TMXDI), 1 ,4-xylylene diiso~iy~nate (XDI), 1 ,3-xylylene diisocyanate, and IlliAlUl~ s thereof. ~r~led diisocyanates, in ~PnP~l, include those selected 25 from the group con~i~ting of isophorone diisocyanate, toluene diisocyanate, dicyclohexylmeth~n~P 4,4'-diisocy~ ate, 1,4-cycloh.A~e diis~cy~ate, m-t~ l yl xylylene diiso-;y~nale, p-tet~methyl xylylene diiso~iyanale~
derivatives of all the aforem~ntioned, and IlliAlules thereof.

W 096/30426 PCTrUS96/02083 (~h~in P-tPn-lPrs Suitable chain eY~n~prs include tli~minP and dihydluAy chain çytpn~ers.
The chain PYtP~d~rs may be short chain ~ Ps such as hPY~mPthylene mine~ xylylene ~i~ ...inP, 1 ,3-di(4-piperidyl)p,u~le (DIPIP), N-2-~minoethyl S ~ llyldirnP-thoY-ysilane (DAS), 1,3~ii~mino~rl~le (DAMP), 1,4-,.;nf~pe..~ P, ~ , piperidyl ~rvpalle and the like, with 1 ,3-di(4-piperidyl)~lo~e and 1 ,3-rli~mino~)elll~le being ~.ef~ led. Examples of useful dihyd~Ay chain extP-ndPr~ include but are not limited to those se~t~l from the group con~i~tin~ of 1,4-b~-t~n~Aiol, ethylene glycol, diethylene glycol, 10 dip,u~lene glycol, llP ~ yl glycol, 1-6-hPY~nP~iûl, 1~4-cyclohP,Y~nP
Q1~ and IlliAIUl~S therF,of.
Polymeric ~ ...ines as well as polymeric glycols may also be used.
Useful polymeric ~1;~ ;nFS include those which have a funrtiQn~lity appr~hing 2.0 such as polyethylene oxide ~ n~s; poly~r~pylene oxide ~ mines; and 15 poly~e~ l-ylene oxide ~i~minPS having a mol~Pcul~r weight in the range of from 300 to 10,000, with a rnc~lP~ r weight in the range of 400 to 5,000 being most ~lc;r~;lled. Such polytetr~mPthylene oxide ~ n~ s and methods of making the same can be found in U.S. Patent No. 4,933,396 (Leir et al.). Other useful polymeric rli~minps are polyether ~ minP~s~ sold under the tr~len~mP
20 J~FA~E, available from the ~~ n C~hPmi~l Co. Suitable polymeric diols include poly~L~amethylene oxide glycol, polyethylene oxide glycol, polyethylene adipate glycol, poly~-~ylene oxide glycol, polybllt~rliPne glycol, polycaprn1~~tonP- glycol, and the like.
It is also possible to inco.~lale poly~iloY~ne into the A sPp..~-t of the 25 block copolymer by using a ~ minP or diol polysiloxane chain eYten~lp~r. These chain eYtPn~P~s typically have mol~ r weights of from about 500 to about 35,000, more preferably from about 1,000 to about 20,000. FY~mpl~3 of useful diol function~l poly~iloY~nç chain e~ include triblock copolymers comprising a polydimethyl~iloY~nP midblock and a polyethylene oxide endblock g W 096/30426 PCTrUS96102083 ~l.llin~ with hydroxyl function. lity. One such mqtPriql is commerci. lly available from Dow Corning Co. under the trade decignqtion DC Q4-3667.
Diamine funetionq-l polycilnY~q-ne chain eYten.1P s can be pre~a~ by a variety of mPtho~lc known in the art, most preferably according to the methods described inU.S. Patent No. 5,214,119 and WO 95/03354.
The physical ~l ,~-lies of the rP~sl~lting block copolymer (such as tensile strength, haf~ness, abrasion reCict~nr~ glass trtqncition ~lll~lalule~ flexibility, etc.) are affected by the sP~ction of chain e~tender. In gPnPrql, low molP~ r weight ch. in e~t~Pn~l~Prs may be used to increase the tensile strength, h, rdness and abrasion reci~t-qn~ of the block copolymer, while polymeric ~ minps and polymeric glycols may be used to provide soft, flexible and elastic block copolymers. For e~ ple, when a diiso~iyana~ is combined with large q~ntitip~s of relatively low molPcul~r weight chain e~t~-n~lPrs (preferably having a molccul~r weight less than 300), the hard character of the block copolymer is enh~n-xd and a leathery product may be obtained. By way of another example, when the block copolymer compri~es high levels of polydiorganociloY~n~ and polymeric ~ mines or polymeric glycol chain eYten~Pr.s are used, soft or pliablem~t~.ri~ls are formed which may be used as ~l~ntc or additives. By way of yet another example, when ~i~minP or diol polysiloxane chain e~tPnders are used, polysiloxane is incor~,~ted in both the endblock and midblock segmPntc of the r~sulting block copolymer. This allows for increased flexibility in tailoring release m~tPri~lc to provide a desired level of release. A ~1i~uscion of the effects of various types of chain e~tPn~lers on the .. ~h~.)ir~l ~o~.Lies of block copolymers may be found at page 172 in Abouzahr, S. and Wilkes, G.L.
25 ".eeg..~ Copolymers with Emphasis on Se~mtonte~ Polyurelllalles'' in etructure and ~ lies of Block Copolymers, Folkes, M.F., Elsevier, New York.

W 096/30426 PCTrUS96/02083 Preferably, the se~ res~lting from the chain eYte-nder comprise less than about 50% by weight of the copolymer form~ tion"lPpPn~lin~ on the ~,lies of the res~lt~nt copolymer desired.
P,~dtion ofDiblock and Triblock Polydior~n--siloxane-Polyurea Copolymers The diblock and triblock copolymers of the present invention are plGpared from the reaction of ~ t.~lG5 of m~ ne-functional polydior~nosiln~n~
and chain e~tPn~Pr~ with approxim~tP-ly stoichiometric amounts of diisocyanale.
The re~cfic~ are con~luct~P~ in a dry solvent, or ~ lul~,s of solvents, l -ute~ d frorn ~I-..o~l.h~r1c moisture. The solvents are ~l~f~ldbly unreactive with the 10 diis~yana~s and chain e~ e~. The starting m~tPri~l~ and final products fe~ably remain completely miscible in the solvents during and after comrleticn of the polym~ri7~tion. Suitable solvents include polar liquids, such as ~1',Qh~ , ethers, esters, and ch10~ t~ hydf~c~l~ns, with tetrahyd-urul~l and methylene c-hlor ~le being esperi~lly useful. Ple~elled solvents are delGl,..ined 15 by the nature of the re~Pntc. For eY~mplc, when all the r~t~nt~ are amine ~mction~l and are react_d with aliphatic diisocyanates, s~o~ hol~, such as isopn,panol or 2-butanol, are plere.l~d, either alone, or in combination withnon-polar solvents such as toluene or cycloh~ n~. For reactions involving al~.,-aticdiisocyanateste.g.,diphenyl...~ ne4,4'-diisocyanate(MDI)], 20 tetrahydf~ruldn cont;~inin~ 10 to 25% of a dipolar aprotic co-solvent such as dimell-ylrc,....~...i~e is pf,relled.
The reaction conllitions and ~Jl'~lUl'~,S for L,l~ on of the block copolymers will also vary depel--iing upon the nature of the re~t~nt~. For re~cti-,n~ involving only amine fimction~l starting m~tPri~l~, it is l)f~fellcd to run 25 the polymeri7~tion in two stages in order to ensure complete incc,l~l~ion of the mon~minP-filncti--n~l polydior~no~ilo~.~n~o(npolysiloxane~t) into the final ~l~ducl. In the first step, the poly.~ilo~n~ is added, either neat or in solution, to a soll~tion of at least a fourfold molar e.~cess of diiso-;y~lale to provide a solution of a mixlul~ of a polydio~nos;loY~ne ureido monoiso~;y~nale and diisocyanate.

W 096/30426 PCTrUS96/02083 In the second step, the rçm~in~ler of the diisocyai~ale, if any, is added, followed by a sQl~lhon of the other ~ ;n~ r~-t~ntc. The pl~fe.-~ molar ratio of total amines to diisoc~ates is in the range of from 0.95:1.0 to 1.0 to 0.95, most ~f~ dbly in a ratio 1.0:1.0 in order to provide for ...~,~i....,... molcc~ r weight 5 of the final block copolymer product. These reactions can be cond~1ctP~I at IGIII~C1dlU1CS from 0 to 150~C. The reaction is plcrGl~bly carried out at ambient t~ to 50~C. The reaction of amines with diisocyanates is exothermic, and no catalyst is l~uil~.
For co...l oc;l;onc which incol~atG diols into the formulation, a two stage procedure for the plcp~ l;on is also p~fcllcd. Again, it is p~f~lcd to add the polyciloY~ne to a solution of excess diisocy~ate in a non-hydr~ylic solvent, most prcf~dbly tetrahyd-~ rul~am To this Ill~lulc is added the diols and a small amount of a catalyst such as ~ldnnous octoate or dibulyltin ~ 1lratP, and heated at reflux for 1 to 2 hours, or until the reaction is complete. The ~lGfe molar ratio of amine plus diols to diisocyanat~s is 0.95:1.0 to 1.0:0.95. It is also possible to run the reaction initially at lower molar ratios of 0.70-0.90:1.0 to provide Illi~lurGs of isocyanate-tcl..~ tlod u~dllal~e oligomers. PolymPri7~ti(-n is then completed by the ~ ition of sufficient rli~minP chain e~tPndPr to the reaction to bring the final amine/alcohol to diisocyanate molar ratio to 0.95-1.0:
1.0, most preferably 1.0 to 1Ø
The diblock and triblock co~)olylllc.~ of this invention can be ~-e~ to have a wide range of useful pl~ ies by varying the weight ratio of cP.gmPnt B
to se~mPnt A, the nature of the chain eYtend~Pr.c and other polymers employed, and the molecul~r weight of the poly~iloY~n~o endblocks. The block copolymers of this invention, for most applications, do not require curing to achieve theirdesirable pr~llies, but yield tough solvent-cast films upon drying. When lition~l stability, solvent r~cict~nee or strength is desired, the cili-~nP block copolymers can be cros~l;.-~ after casting or coating by any of the convention~
mPtho~lc known in the art, such as electron beam r~ tion, or use of peroxides.

Ml~n~ESO~ MIN~NG & MNFG. CO. ~O~ n our re~: A 2552 PCT
- S:Ea-~ S~ S~E4 , ~ Mai lq9~ r~i-C~ 4()15 The diblock and triblock copolymers of the present invention are suitable for use as release co~tingc for a variety of ~ ule-sensitive adhesives. They have good stability in solution, are film-fonning, and have l1nllc~ 1y high strength plus desirable me~h~nical and elastomeric plo~.lies. In addition, they 5 do not require high tG~ll~ldlUlG curing or long p~es~ing times, a d~ide~l advantage in pressu~e-sensitive tape m~m-f~lring.
The block copolymers of this invention may be pr~palcd to give varying arnounts of rele~e through v~ri~tionC in the ratio of siliconç segm~ntc to non-silicone segmPnt~ (i.e. the ratio of B to A), the amount and nature of the chain10 PYten~erS employed, and the molP~ul~r weight of the polydiorganosi1O,Y-~ne block. In general, the amount of release can vary from l.0 Nldm or less to about35 Nldm. Certain copolymers are especially useful as low-adhesion b~ i7Ps (LABs) for ~,es~ul~-sensitive adhesives tapes such as m~cl~ing tapes. LABs for tapes in roll forrn typically exhibit release values in the range of from about 6 to 15 about35Nldm. r ~ ~v~ c~o~/7 --The ~lGÇt;.ledlpolydiorg~nc ci1O~nP- s~ nt content for copolymers of the present invention used as release c~l;ngs for p~ulc:-sensitive adhesives is from about l to about S0 percent by weight, the ~lGÇt;ll~d ranges being dependent on the specific adhesive and its ~11tim~tç use. In general, thin film 20 co~tings of copolymers comprising l to about 50 weight percent ~ - ~
polydior~nosi1O~ne exhibit the n~CeS~ combination of adequate unwind on fresh tape with only a mode~te increase in unwind force after adverse aging con-litio~c of heat and h~1mitlity. For ~ ium release co~ting~c (i.e., release coAI;l g~ having release values of less than about 2 N/dm), a higher content of ~-~
25 polydiorg~nosi1O~ne is ~uLed in the form~ tion, preferably from about 25 to50 percent by weight polydiol~n-s~;1O~nP. In applications where modç~tP
release values are ~-c~pt~hle, the polysi1nY~nP- content may be reduced to lowerlevels, for e~mp1e, 15% by weight and lower.

A~N~E~ S~

W O 96/30426 PCTrUS96/02083 Typical mlmbPr average molecular weights for the enAblorL- of block copolymers int~nd~P~ for use in release mqteriql~ are in the range of from 5,000to about 30,000. The nu,llber average molecular weight of the midblock may vary over a wide range depen~ing on the chain eYt~on~iPr used to make this block.
S The poly~ilo~q-nP~-polyurea diblock and triblock co~ .;t;ons of this invention, depen~ling upon their viscosity, can be coated via any of a variety of conventiorlql coating mPtho-~, such as roll, knife, or curtain co~ting, or extrusion coating. These colll~ ;on~ can be applied to at least a portion of at least one major surface of a suitable flexible or inflPYible b~r~in~ m~tPri~l and dried to produce release~oated sheet m~ten~l~. Useful flexible b~.-k ing m~tPri~ include paper, plastic films such as poly(propylene), poly(ethylene), poly(vinyl chlori~e), poly(t~Ptrall-Jo~ ylene), polyester [e.g., poly(ethylene ~ lAl~te)], polyimide film such as DuPont~s Kapton'M, c~llulose ~ t~tç, and ethyl cP~ lose. R~ ing~ can also be of woven fabric formed of threads of s~ leLic or na~ural m~tPri~l~ such as cotton, nylon, rayon, glass, or cer~mic m~tPn~l, or they can be of nonwoven fabric such as air-laid webs of natural or synthetic fibers or blends of these. In ~ ition, suitable b~cl~ings can be formed of metal, mPt~lli7Pd polymeric film, or c~mic sheet m~teri~l. The coated sheet materials can take the form of any article convention~lly known to be utilized with PSA compositio~ such as labels, tapes, transfer tapes (comrri~ing a film of the PSA borne on at least one release liner), signs, covers, m~rking in~ices,and the like. Primers can be utili7~, but they are not always n~,~.y.
This invention is further illu,l~ Pd by the following e~mples which are not int~n-l~ to be limiting in scope. Unless in~ic~t~d otherwise, the mol~cul~r weights refer to ~u~bel average molecular weights. All parts, ~ç~nl;~ges and ratios are by weight unless otherwise sperified.

W 096/30426 PCT~US96/02083 TEST METHODS
~ed ~'~1P~CP V~lue This test ll.e~ul~s the effectiveness of the silicone release cc"..l~silion after a period of heat aging. The aged release value is a 4~ e measure of the force rGquir~cl to remove a flexible adhesive tape from a sul,sL,~te coated with the test COIll~ ;li~ n, Aged release testing was con~ cte~l using a tape sample commerciaUy available from 3M Co. as general purpose m~ in~ tape no. 232. This tape compri~ a t~ kifi~d natural rubber ~n,i~ul~ sensitive adhesive coated on a 1.27 cm wide resin i.npf~~ t~d crepe paper b~in~. The tape was rolled down with S passes from a 2 kg rubber roller onto a 2.54 cm by 25 cm strip of release coated ~Ul~Slldte ~JlepalC:d according to the following eY~mrles andL allowed todwell in intim~e contact for three days at 65~C. These l~min~tPs were then aged for at least 6 hours at 22.2~C and 50% relative h~lmi-lity and then adhered tapeside up to the stage of an In~ n~o. ~, Inc. slip/peel tester (~odlel 3M90) with double coated t~pe. The force l~uir~d to remove the 232 m~lring tape at an angle of 180~ and a speed of 228.6 cm/min was measured.
~ed Re~dhesion Aged re~lhçsions were measured by ~lhçrinp the freshly peeled tape from the above test to a clean glass plate and measuring the peel ~rlh~cion using the same Instrum~ntors slip/peel tester infii-~ted above, again peeling at 228.6cm/min and at a 180~ peel angle, after allowing the test tape to dwell on the glass plate for 30 ~or~ These mea~u~.-.~ were taken to dt;~.---ine 25 whether a drop in the ~lh~cion value occul-ed due to nndecir~hle co~ in~lion of the adhesive surface by transfer of unincol~ldled silicone in the release ~ coating. RP~-lh~cions are lepoll~d as a percenldge of the force l~uir~d to remove the aged sample from a clean glass plate versus the force required to remove a control tape sample from a clean glass plate which has not been CA 022l4678 l997-09-04 W 096/30426 PCTrUS96/02083 adhered to the release coating. Pr,f.,r~bly the re~ hPsiQn values are 100%
inr1iA~ting no ~ ;,Ç~,r of the S;1;A~OI1P in the release c,oating to the tape.
lhP.~ n values of about 80-90%, however, are A~ ptA-' le.
AhbreviAti~n~
5K Mo~ ~q-lkyl~ ed polydimethyl~iloYAmP having a theoretical m~'Acul~r weight of 5,000 1 OK Mf )n o~ .. i 1~ Q 1 kyl L.. i ~ ~ ~ t~d polydimethyl~iloxAne having a theoretical molecular weight of 10,000 20K Mol o~ QA~lkyl-~,.......... ;.~t~
polydi...t;lhyl~iloYAne having a theoretical 1 5 m ol. ~ ul weight of 20, 000 D400 J~ rl~."i~e~M D400, an a,a~-~l;q.~-h~Q~lu~l poly(propylPnPoxide) chain eYtPn~lPr having an a~-oAim-qtP n~ hPI average molecular weight of 400, commercially available from ~Iml~lllql~ t~.hPmiA-ql Co.
D4000 JeffqminP,~M D4000, an a,a)--~1iAmim p~
poly(propylP-nPoxide) chain eYtender having a n approximqt~ number average mo~ lAr weight of 4000, commercially available from ~I~ l- ChP-mi~A-ql Co.
DAMP 1,3~1iqmino~"~
DU700 JeffAminP~M DU700, an a,~-~ Amin~
poly~propylen~xide) chain ~Ytender co~ ;ni,-g internal urea groups having an a~.u,.im-q-tr number average mo1~cll1qr weight of 900, commercially available from - C-hf~mir-ql Co.

W O 96/30426 PCTrUS96/02083 IPDI isophorone diis~;r~lalG
Mn nu~ average molcc~ rweight SK DIAMINE Di~min~lkyl-tel,.. n~t~
polydimethyl~ Y~ne having a theoretical mrl-c~ r weight of 5,000 E~AMPLE 1 P~ ~lion of Aminoalkyl Fluorn~ nP Te.,..in~;n~ A~ent A 500 ml, 3 neck round bottom flask was cha~ d with 49.6 g 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 29.6 g ammonium fl~loride, and 300 ml cycloh~ While heating under reflux, water was removed by neans of a Dean-Stark trap. After 18 hours, 4.4 ml of water had been collected, and the clear, colorlec~ soll-tion was transferred while warm to a 500 ml l-neck round 15 bottom flask. The solvent was di~till~ on a rotary evapolatl~r to provide 165grams of white solid. This was dissolved in 200 ml of methylene chloride; 30 g of hPY~metllyltlR~ 7~ne was added; and the ~ lult; was stirred and heated under reflux for 5 hours. The flask was fitted for ~ till~tion and the solvent removedunder a~ dtor vacuum. The product was ~ till~d (boiling point of 70~C.) under 20 ~i.;.~or vacuum to provide 3-aminopropyl~iim~otl~yl fluorosilane as a clear, colorless oil. The yield was 54 g (100%), which was d~;~l,llih~ed to be pure by vapor phase ch~ tog.,~l-hy. The structure was confirmed by NM[R
sco~y.
E~Al!~LE 2~5 P~ dlion of Aminopropyl-Tellllin~çd Polydimethylsiloxane n-Butyl lithium (10 ml, 2.5 M) was added to 7.4 grams oc~;~---kll-ylcyclotetr~iloxane under argon to form lithium ~ nol~te iniliatol.
After stirring for 30 "~ ules, a solution of 250 grams hPY~m.othylcyclotrisiloxane in 250 grams dry tetrahydruruldi~ was added and the reaction stirred at room 30 ~Illpeldlule for 18 hours. To the rPs~-lting viscous syrup was added 3.4 grams 3-aminopr~yldim~thyl fluorosilane te...~ g agent described in Example 1.

W 096/30426 PCTrUS96/02083 The viscosity rapidly decreased. After stirring for 2 hours, the solvent was til1~d off on a rotary e~d~old~ol. The pr~lu.;l was filtered to remove lithium flllori-lç and provided 250 grdms of ~ilicone monn~minp as a clear, colorless oil.
Titration with 1.0 N HCl gave a nulllbGr averdge moloc~ r weight, Mn~ of 9400 5 (theoretical Mn = 10,000). Using this procedure, but varying the reaction timeand using a molar excess of ~ h~ g agent to cyclic siloxane, aminop,~,p~l-termin~t~ polydimethyl~iloY~nes of theoretical Mn of 5,000 (titrated n~.mber average molecular weight = 5,038) and 20,000 (titrdted number average molecular weight = 19,274) were similarly pr~a,Gd.

~el~dtion of Diblock and Triblock Polysiloxane-Polyurea In an 100 ml round bottom flask, 0.10 gram of the aminopr~l-~....;n~ poly~ Y~nP macromonomer of E,~.lple 2 (Mn=9400)and 2.9 grams Jeff~minP~M DU700 were combined. After heating this ~ lulG to 100~C under 15 vacuum, 25 ml iso~ropyl alcohol were added to this IlliLX~Ul~. In a second flask ~ui~ed with a mPch~nir~l stirrer, 5.02 grams of IPDI were mixed with 25 ml isopropyl ~lcohc l The co.-le~.t~i of the first flask where then added to the con~P~ of the second flask and the combined col~ lc stirred for about 10 es. 1.98 grams of DAMP were then dissolved in 40 ml isop,upyl alcohol 20 and added in one portion to the second flask. This mixture was stirred for several hours. Suffiri~nt isopropyl alcohol was then added to result in a 5%
solution of the block copolymeric product.
This 10% solids solution was then coated directly onto a 15.24 cm x 1 m strip of a 1.5 mil polyester film using a #6 Mayer rod and tested for release and 25 re~lhP,sion as des i,il~d above. The results of these tests were recol~ed and can be found in Table I.

Block copolymers were ple~d by the method of Example 3 by varying amounts of the aminopropyl-~ ...in~ poly~iloY~nP, JPff~minP~ DU700, IPDI

and DAMP in the poly~ ;,, tion ~ ul~. The ratios of these starting m~tPri~l.c are given in Table I. Release co...pos;l;o~c were ple~d and coated as in F.Y~mrlP. 3 except using a 5% solids s~ ffon~ Release and re~-lhPcion test results are given in Table I.
S E~AMPLES ~9 To ~P.mo~ le the effect of m~lP~ul~r weight on the polydimethylciloY~np endblocks of the col-,posilions of the present invention, two ~n~logc of Example S were pr~red using the lower molecular weight (Mn =
5,038) and higher m~ r weight (Mn = 19,274) aminopropyl-termin~t~
10 polydimethylciloY~nç starting m~tP.ri~lc of FY~mp'~ 2. The ratios of these starting m~t~P.ri~lc are given in Table I. Release CGIllpos;lic nc were pr~al~d and coated as in Example 3. Release and re~lhP.cis)n test results are given in Table I.

Example 10 illu~ ~s the use of a higher mol~l-l~r weight polymeric chain eYtPn~er~ D4000. A Illi~lUlc~ comprising 25 percent by dry weight of an ~min~lkyl-~....;n~ polydimethylciloY~np~ (Mn = 9,257), 50 percent by weight IPDI /DAMP, and 25 percent by weight D4000 was pre~ar~d, coated and tested according to the metho lc of Examples 8-9 except using a #3 Mayer rod. Release and re~lhpcion test results are given in Table I.

W 096/30426 PCTrUS96/02083 COMPARATIVE EXAMPLE C-l A st~ d silicone-polyurea block copolymer was pre~ cd using the method of U.S. Patent No. 5,214,119 (Leir et al.). The block copolymer compri~ 20 p~l~ t by weight of a ~ ,Olle rli~min~P. (Mn = 10~000) prep~u~d according to the two-step method of U.S. Patent No. 5,214,119 using a tetram~ yl~ o~ nol~t~ catalyst, 60 percent by weight IPDIlDAMP and 20 ~l~nt by weight DU700. A release colnpos;~ion was pre~ ed and coated as in Example 3. Release and rP"~lhP~ion tests were run and the results are in Table I.
Table I
Aged Aged Poly- J rr ~ IPDI DAMP Release 12~ ~-E~c. silo~ane (wt96) (wt%)(wt%) Value (%) (wt%) (N/dm) 3 1 29(DU700) 50.2 19.8 36.3 92.2 4 3 27(DU700) SO.O 20.0 17.3 82.5 S 25(DU700) 49.9 20.1 12.0 lOS.O
6 20 20(DU700) 42.8 17.2 S.9 99.6 7 35 lO(DU700) 38.6 16.4 l.S 97.3 8 S (SK) 25(DU700) SO.O 20 lO.S 87.8 g S (20K) 25(DU700) 49,9 20.1 ll.S 90.4 25 (lOK)25 (D4000) 34.7 15.3 0.8 83.9 C-1 201 20(DU700) 43.1 16.9 10.0 99.2 D- - -"-yl I ~ ' polysilo~ane used instead of ~ ~' yl . ~ I polysilo~ane W 096/30426 PCTrUS96/02083 Table I ill..,l.a~s that a full range of release char~-~teri~tics were obtained through var.,ving the amounts and mol ~ cul~r weights of the various col~lponelll~
used to make the block copolymer of the present invention. Surpri~ingly, useful release coating oo-l-po~;lion~ in the m~r~tP to tight release range (i.e., release values in the range of 10-40 N/dm) were ~r~ ed using as little as 1-5 wt%
poly~ Y~ne macromonomer. Pn_miu--~ release values (i.e., release values less than 2N/dm) were observed for co. p os;lion~ having only 35 wt% of the monofi-nction~1 poly~i1OY~n~o- CO~--pO~ t. Such low release values are typicallyonly seen in 100% silironP co.nl)osilions. Furthermore, Example 6 and Co~.pA~ e Py~mple C-l clearly dçmon~trate the effect of different polymer arch;~ es (B-A and B-A-B copolymers of the present application vs. (A-B)n se~mtonted block copolymers of C-l) on release pel~---ance of co~tin~
compri~ing the same amount of polydiorganosiloxane. At the same polysiloxane, diisocyanate and chain eyten~er content, the copolymers of the present inventionpossess a siPnificantly lower peel adhesion than their ~gm.onted counte EXAMPLES 1~14 To further demonstrate the release pl~pellies of the co---l)osilions of the present invention, the co~ting~ of Examples 8-10 were measured for release and re~(lhe~ion as described above using an alternative tape sample (t~ ifie~ styrene-isoprene-styrene (SIS) block copolymer adhesive on a polypropylene backing, commercially available as high pelÇoln~lce box sealing tape no. 375 from 3M
Co.). The results of these tests are recorded below in Table II.

W O96/30426 PCTrUS96/02083 Table II
Aged Aged ~ Je~ ~ rPDI DA~P Relo~e E~%) (~ %) (~n%)V~ue (%) ~N/dm) 12S(SK) 25~DU700) SO.O 20.0 5.8 79.6 135(20K) 25~DU700) 49.9 20.1 lS.9 80.6 1425(lOK) 25~D4000) 34.7 15.3 1.2 79.2 Again, these ~ s show that a range of levels of release can be ob~ined for adhesives comrri~ing t~ifiP~ SIS block copolymers.

P.~ .dlion of an Ol~nnpolysilo~Yane Diamine Chain FYte~(ler A sollltion of 14.79 g of bis-(3-aminoplvpyl) tetramethyl ~ iloY~ne and 352.9 g ~ el1~ylcyclotetr~ilox~ne was purged with argon for 20 min. and then heated to 150~C; 0.06 g (100 ppm) of 50% aqueous cesium hydlu~ide was 10 added and heating ~-~ çd for 6 hours until the a--lino~l~yl rli~iloY~n~p had been con~-mPd. The reactiûn was cooled to 70~C, nPutr~li7~d with excess triethylamine and acetic acid, and heated under high vacuum to remove cyclic ~;1QY~n~PS over a period of at least 5 hours. After cooling to ambient ~ dtule and filtering to remove cesium ~ret~te, an i~ol~tP~ d;~ .~r~yl-~l...;ll~ted 15 polydi~c~lyl~iloy~n~ product was obtained having a theoretical molecular weight of 5,000 (titrated number average molx~ r weight = 5,276).

Example 16 ~lçmon~t-ates the use of the combination of mon-)~min~r~l t~....il-~t~ polydimethyl.~ilo~ne of Example 2 (Mn = 5,038) and the silicone di~minP chain ç~tPn~çr of Example 15 (Mn = 5,276). These mixed a.,linoplopyl f~mction~l poly~iloY~nes, each used in the plu~llion of 10 percent by weight, were combined as in F.~...ple 3 with 25 weight percent -~ -W 096/30426 PCTrUS96/02083 polymeric chain e-t~n~er D400 and SS percent by weight IPDI/DAMP. These compo~it~ c were then coated and tested as in E~L~IIP1_ 3. The results of these tests are given in Table m.
Table II~
Aged pOlycilo~ J~ c IPDI DAMP Rele~ce Aged Ex. (wt%) (wt~) (wt%) (wt%) Value ~ lh~5i~n (N/dm) (%) 16 lO(5K)+ 25 (D400) 41.8 13.2 2.3 94.6 lO(5K DIAMINE) This Example ill4s~ .s that near ~lell)iUIn release levels may be achieved at low polysiloxane content (20 weight percent) by hlcG~ g both polyciloY~ne endblocks and midblocks in the block copolymer by using both mono~min~lkyl - and rli~min~lkyl t~.---inA~ poly~iloY~n~- starting m~t~
10 E~IPLES 17-18 FY~mple 17 was ple~ ~ by making a block copolymer solllti~m using the same procedure of FY2mple 3 except for the use of both mono~minoAlkyl-d polysiloxane (~n = 5,038) of Example 2 and ~i~mino~lkyl-in~l~l polysiloxane ~n = 5,276) of FY~mrle lS.
Example 18 was p~ d by making a block copolymer solution using the same procedure of Example 3 except for the use of both mono~mino~lkyl-~l...inA~l poly.~ Y~ne (Mn = 10,489) made using the same procedure of Example 2 and ~ min~lkyl te~ inA~ed poly-~ilQY~ne (Mn = S,276) of Example 15.
The block copolymer soll~ti~n~ were coated according to the procedure given in Example 3 and tested for release and re~1hP-sion using the procedure of: PY~mp'~~ 12-14. Results of these tests are recorded below in Table IV.

W 096/30426 PCTrUS96/02083 Table IV
Aged Poly~ilo~ P Jtrr;.. ;,.~ IPDI DAMP Release Aged E~. (wt~) (wt%) (wt%) (wt%) ValueR.o~-lhe~irm (Nldm) (%) 17 10(5K)+ 25 41.8 13.2 1.8 80.8 10(5K DIAMINE) (D400) 18 10(10K)+ 0 34.8 15.2 1.6 80.4 40(5K DIAMINE) TlliS FY:lmrlc illU~IldleS that y~ liulll release levels may be achieved using poly~iloY~ne contenl~ of 20% and 50% when both the endblocks and S midblocks comprise polysiloxane.

Claims

WHAT IS CLAIMED IS:
1. A block copolymer having the structure B-A-X wherein B
comprises a non-functional polydiorganosiloxane endblock derived from a monoamine-functional polydiorganosiloxane, A comprises a polyurea block, and X is selected from the group consisting of hydrogen, a non-functional polydiorganosiloxane endblock, and an isocyanate radical.
2. A block copolymer according to Claim 1, wherein:
B has the structure:

;

A has the structure:

; and X is selected from the group consisting of hydrogen and the following structures:

, and ;

wherein:
each D is individually selected from the group consisting of hydrogen, an alkyl radical having from 1 to 10 carbon atoms, and a phenyl radical;
each Y is a divalent radical individually selected from the group consisting of an alkylene radical having from 1 to 10 carbon atoms, an aralkyl are radical, and an aryl are radical;
each R is individually selected from the group consisting of a monovalent alkyl radical having from 2 to 12 carbon atoms, a substituted alkyl radical having from 2 to 12 carbon atoms, a vinyl radical, a phenyl radical, and a substituted phenyl radical, with the proviso that at least 50 % of the number of R radicals are methyl;
each n is an integer which is 5 or greater;
m is an integer which is 1 to about 25;
each Z is individually selected from the group consisting of aromatic, aliphatic, araliphatic and cycloaliphatic divalent radicals;
each A is individually selected from the group consisting of -O-, and -S-where G is selected from the group consisting of hydrogen, an alkyl radical having from 1 to 10 carbon atoms, a phenyl radical, and a radical which when combined with B' forms a heterocycle; and each B is a divalent radical individually selected from the group consisting of aromatic, aliphatic, araliphatic and cycloaliphatic radicals, polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polyethylene adipate, polycaprolactone, polybutadiene, polyamide, polysiloxane, mixtures thereof, and a radical completing a ring structure with A' to form a heterocycle.
3. A block copolymer according to Claim 2 wherein:
each D is hydrogen;
each Y is individually selected from the group consisting of alkylene radicals having from 1 to 10 carbon atoms;

each R is methyl;
each n is an integer from 40 to 400;
m is an integer from 5 to 15;
each Z is individually selected from the group consisting of hexamethylene, methylene bis-(phenylene), tetramethyl xylylene, isophorone, tetramethylene, cyclohexylene, and methylene dicyclohexylene; and each A is individually selected from the group consisting of and -O-.

4. A block copolymer according to Claim 3, wherein Y is propylene.
5. A block copolymer according to Claim 1, comprising from about 1 to about 50 percent by weight of said nonfunctional polydiorganosiloxane.
6. A block copolymer according to Claim 1, comprising from about 25 to about 50 percent by weight of said nonfunctional polydiorganosiloxane.
7. A block copolymer according to Claim 1, comprising less than 15 percent by weight of said nonfunctional polydiorganosiloxane.
8. A block copolymer according to Claim 1 prepared by reacting a monoamine-functional polydiorganosiloxane, a chain extender and diisocyanate.
9. A block copolymer according to Claim 8, wherein said diisocyanate is isophorone diisocyanate.
10. A block copolymer according to Claim 8, wherein said chain extender is selected from the group consisting of diamine and diol chain extenders and mixtures thereof.
11. A block copolymer according to Claim 8, wherein the combined molar ratio of said monoamine-functional polydiorganosiloxane and said chain extender to said diisocyanate is 0.95:1.0 to 1.0:0.95.

12. An article comprising a backing having at least one release material applied thereto, said release material comprising a block copolymer having the structure B-A-X wherein B comprises a non-functional polydiorganosiloxane endblock; A comprises a polyurea block and X is selected from the group consisting of hydrogen, a non-functional polydiorganosiloxane endblock, and an isocyanate radical 13. An article according to Claim 12, wherein B has the structure:

;

A has the structure;

; and X is selected from the group consisting of hydrogen and the following structures:

and ;

wherein:
each D is individually selected from the group consisting of hydrogen, an alkyl radical having from 1 to 10 carbon atoms, and a phenyl radical;
each Y is a divalent radical individually selected from the group consisting of an alkylene radical having from 1 to 10 carbon atoms, an aralkyl are radical, and an aryl are radical;
each R is individually selected from the group consisting of a monovalent alkyl radical having from 2 to 12 carbon atoms, a substituted alkyl radical having from 2 to 12 carbon atoms, a vinyl radical, a phenyl radical, and a substituted phenyl radical, with the proviso that at least 50% of the number of R radicals are methyl;
each n is an integer 5 or greater; .
m is an integer from 1 to about 25;
each Z is individually selected from the group consisting of aromatic, aliphatic, araliphatic and cycloaliphatic divalent radicals;
each A' is individually selected from the group consisting of -O-, and -S-where G is selected from the group consisting of hydrogen, an alkyl radical having from 1 to 10 carbon atoms, a phenyl radical, and a radical which when combined with B' forms a heterocycle; and each B' is a divalent radical selected from the group consisting of aromatic, aliphatic, araliphatic and cycloaliphatic radicals, polyethylene oxide, polypropylene oxide, polytetramethylene oxide, polyethylene adipate, polycaprolactone, polybutadiene, polyamide, polysiloxane, mixtures thereof, and a radical completing a ring structure with A' to form a heterocycle.

14. An article according to Claim 12, wherein said backing comprises a material selected from the group consisting of paper, poly(propylene), poly(ethylene), poly(vinyl chloride), poly(tetrafluoroethylene), polyester, polyimide, cellulose acetate, ethyl cellulose, woven fabric and nonwoven fabric.15. An article according to Claim 12, wherein said backing further comprises at least one layer of adhesive applied thereto.
16. An article according to Claim 15, wherein said adhesive is applied to said backing on a surface opposite to that of said release material.
17. An article according to Claim 15, wherein said adhesive is applied onto said release material.
18. An article according to Claim 12, removably adhered to an adhesive tape as a release liner.
19. An article according to Claim 12, wherein said block copolymer is prepared by reacting a monoamine-functional polydiolganosiloxane, a chain extender and diisocyanate.
20. An article according to Claim 19, wherein said diisocyanate is isophorone diisocyanate.
21. An article according to Claim 19, wherein said chain extender is selected from the group consisting of diamine and diol chain extenders and mixtures thereof.
22. A block copolymer according to Claim 8 wherein said chain extender is selected from the group consisting of diamine polysiloxane and diol polysiloxane chain extenders.
23. An article according to Claim 19 wherein said chain extender is selected from the group consisting of diamine polysiloxane and diol polysiloxanechain extenders.