CA2194733A1 - Adhesive compositions and adhesive tapes comprising zwitterionic copolymers and novel zwitterionic copolymers - Google Patents

Abstract

The invention relates to adhesive compositions comprising zwitterionic copolymers, including repulpable adhesive compositions, and adhesive tapes made with such compositions. The adhesive compositions comprise a zwitterionic copolymer and a zwitterionic plasticizer or tackifier which can be coated on a backing to form an adhesive tape. The repulpable tapes are formed from a repulpable adhesive composition comprising a zwitterionic copolymer coated on a repulpable backing. Examples of zwitterionic copolymers are those derived from the monomers N-(3-sulphopropyl)-N-methacryloxy-ethyl-N,N-dimethhyl ammonium betaine or N-(3-sulphopropyl)-N-acryloxy-ethyl-N,N-dimethyl ammonium betaine. Some of the zwitterionic copolymers are novel.

Description

ADHESIVE COMPOSITIONS AND ADHESIVE TAPES COMPRISING
ZWITTERIONIC COPOLYMERS, AND NOVEL ZWITTERIONIC COPOLYMERS
The lnventlon relates to adheslve composltlons comprislng zwltterlonlc copolymers, lncludlng repulpable adheslve composltlons, and adheslve tapes made wlth such composltlons. Some of the zwltterlonlc copolymers are novel.
Adheslve composltlons, such as pressure-sensitlve adheslve (PSA) composltlons, commonly contaln an adheslve polymer together wlth a tacklfler or plastlclzer. The adheslve polymer provides coheslon and the tacklfler or plastlclzer lncreases tack.
Adheslves are useful ln a wlde range of appllcatlons and lnclude PSAs whlch are used ln labels, packaglng masklng tapes and protectlve coverlngs. Further, pressure sensltlve adheslve composltlons whlch are water-dlsperslble are used for fastenlng cloth on mammallan body coverlngs and ln papermaklng and prlntlng operatlons. In papermaklng they may be used, for example, to spllce the end of one roll of paper to the beglnnlng of another roll.
In papermaklng, ln partlcular, lt is deslrable that the adhesives used are repulpable. That is, they can be left wlth the paper to be repulped wlthout lnterferlng wlth subsequent papermaking processes and are free of components which would blemlsh the flnal paper product. To be repulpable, such adheslves should be water soluble or water dlsperslble.
The current trend in papermaklng is away from acid processing condltions toward alkallne processlng condltlons ' - 21 94~33 and toward an increased use of calcium carbonate filler.
Conventional repulpable adhesives are usually less suitable for such alkaline condltlons. Further, those adheslves whlch mlght be sultable, tend to react wlth the calclum lons of a calclum carbonate filler to form agglomerates which decrease the dispersablllty of the adheslve copolymers.
Adhesives used for spllclng in the paper industry may be sub~ected to elevated temperatures under high shear forces, for example in supercalender applicatlons. Any sllppage, even fractlons of a mllllmeter, may lead to blocking and subsequent web breakage. A high cohesive strength is deslrable to wlthstand hlgh pressure and heat, to resist lateral adhesive flow or "oozlng" (which would result in sllppage) and to reslst adheslve loss by penetration into the paper or "bleedlng". Further, an adhesive for use in papermaklng ls preferably repulpable under a varlety of pH
condltions ~both alkallne and acldlc).
Accordlng to one aspect of the present lnvention there ls provlded an adheslve composltlon comprising a zwltterlonlc copolymer and a zwltterlonlc plastlclzer or tackifler.
Accordlng to a further aspect of the present invention there ls provlded a repulpable adheslve tape comprlslng a repulpable backlng havlng coated thereon an adheslve composltlon comprlslng a repulpable zwitterionic copolymer.
The zwitterionic copolymer comprises a component derlved from a zwltterlonic monomer together wlth a component or components derlved from a hydrophobic or hydrophillc monomer or a mlxture of components derlved from hydrophoblc and hydrophilic monomers.
The zwitterionic monomer must be one which is copolymerlzable with any other monomer used. The zwitterlonic monomers of the present lnventlon include betaines. Mixtures of zwitterionic monomers may be used.
Suitable betalnes lnclude ammonlum carboxylates, ammonlum phosphates and ammonlum sulphonates, preferably ammonlum sulphonates. Preferred betaines are those of formulae RS IN -(CH~z Z ~ ~ N - (CH~ - Z
~ a~

in whlch R5 ls a group containing a carbon-carbon unsaturated bond such as (meth)acryloxy-(C2 4)alkyl, (meth)acrylamldo-(C2 4)alkyl or (C2-C6)alkenyl, R6 and R7 are each Cl 4 alkyl, (C2-C6)alkenyl, or (CH2)nOH ln whlch n ls 2, 3 or 4, R8 ls (C2-C6)alkenyl, z ls an integer of 2-4 and Z~ is S03~ or C02~. Preferably R is Cl-C4 alkyl, Z~ ls S03~ and z is 3.
Partlcular zwltterlonlc monomers which may be mentioned are N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine; N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dlmethyl ammonlum betaine;
N-(3-sulphopropyl)-N-methacrylamldo-propyl-N,N-dlmethyl ammonium betalne; l-(3-sulfopropyl)-2-vlnyl-pyrldlnlum betaine; N-(3-sulphopropyl)-N,N-diallyl-N-methyl ammonlum betalne; and N-(3-sulphopropyl)-N-allyl-N,N-~lmethyl ammonlum betalne.
Particularly preferred zwitterionic monomers are N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dlmethyl ammonium betalne and N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dlmethyl ammonlum betaine. N-~3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonlum betaine is commerclally available from Rashlg AG, Germany. N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dlmethyl ammonlum betalne may be prepared by condensatlon of N,N-dlmethyl amlnoethyl acrylate with 1,3-propanesultone. This latter betaine monomer may also be prepared by the addition of N,N-dimethyl amlnoethyl acrylate to the condensation product of epichlorohydrin and sodium bisulphite.
Generally the zwitterlonic monomer will comprise from about 10 to about 50 mole % of the monomer mlxture used to prepare the copolymer, preferably about 10 to about 20 mole %. The balance of the monomer mlxture wlll be a hydrophobic monomer, a hydrophlllc monomer or a mlxture of such monomers.
The hydrophoblc monomer must be one which ls copolymerlzable wlth the other monomers of the copolymer. A
comblnation of different hydrophoblc monomers can be used.
The hydrophoblc monomer may be an acryllc or methacryllc ester of a non-tertlary alcohol, whlch alcohol has from 1 to 14 carbon atoms, preferably from 2 to 12 carbon atoms. It ls preferred that the non-tertlary alcohol ls an alkanol.

Suitable alkanols to form the ester are alkanols such as ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, l-hexanol, 2-hexanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 2-ethyl-1-butanol, 3-methyl-1-pentanol,

2-ethyl-1-butanol, 3,5,5-trimethyl-1-hexanol, 3-heptanol, l-octanol, 2-octanol, lso-octanol, 2-ethyl-1-hexanol, 1-decanol, l-dodecanol, l-tridecanol and 1-tetradecanol.
Preferred hydrophoblc monomers are the esters of (meth)acryllc acid with butyl alcohol, lso-octyl alcohol or 2-ethyl-1-hexanol or a comblnation thereof.
The hydrophoblc monomer can range generally from 0 to about 85 mole % of the monomer mixture used to prepare the copolymer, more preferably from about 50 to about 75 mole %.
Generally a higher content of hydrophobic monomer will reduce water-dispersibllity of the final copolymer.
The hydrophllic monomer must be one which is copolymerizable with the other monomers of the copolymer.
The hydrophilic monomer may have hydroxy, alkoxy, or amide functional groups. Examples of suitable hydrophilic monomers are 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, ethoxyethoxyethyl acrylate, propoxyethyl acrylate, propoxypropyl acrylate, butoxyethyl acrylate, butoxypropyl acrylate, Carbowax* 750 mono-acrylate, Carbowax* 550 mono-acrylate and acrylamide. A mixture of different hydrophilic monomers may be used.
* Trade-mark 2 1 ~4 733 The hydrophlllc monomer can range generally from 0 to about 50, preferably up to about 20 mole % of the monomer mixture used to prepare the copolymer. Generally a hlgher hydrophlllc monomer content wlll lncrease the water-dlsperslbillty of the copolymer.
Some of the zwltterlonlc copolymers are novel.
Thus accordlng to another aspect of the present lnventlon there ls provided a zwltterionlc copolymer comprlslng:
(1) a unlt derlved from (a) N-(3-sulphopropyl)-N-methacryloxyethyl-N, N-dlmethyl ammonlum betalne, (b) N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dlmethyl ammonlum betalne or (c) a comblnatlon thereof, and (2) a unlt derlved from a comonomer copolymerizable wlth component (1), wlth the provlso that when component (1) ls other than the comblnatlon of (a) and (b), then the comonomer (2) ls at least one member selected from the group conslstlng of 2-(2-ethoxy)ethoxyethyl acrylate and 2-butoxyethyl acrylate.
In some partlcular embodlments, the copolymer comprlses:
(1) N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dlmethyl ammonlum betalne or N-(3-sulphopropyl)-N-acryloxyethyl-N, N-dlmethyl ammonlum betalne and (2) 2-(2-ethoxy)ethoxyethyl acrylate or 2-butoxyethyl acrylate; a comblnatlon of (1) unlts derlved from (l)(a) N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dlmethyl ammonium betalne, (l)~b) N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dlmethyl ammonlum 60557-4g86 betaine and (2) a further comonomer copolymerizable with (l~(a) and (l)(b); N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dlmethyl ammonium betaine and 2-(2-ethoxy)ethoxyethyl acrylate or 2-butoxyethyl acrylate; a comblnation of unlts derlved from (l)(a) N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonlum betalne , (l)(b) N-(3-sulphopropyl)-N-acryloxyethyl-N, N-dlmethyl ammonlum betalne and (2) a comonomer selected from the group conslstlng of 2-(2-ethoxy)ethoxyethyl acrylate, 2-butoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate and mlxtures thereof.
In formulatlon of the adheslve copolymers, several dlfferent monomers can be comblned, each selected to contrlbute some deslred property (such as polarity or water solublllty). Further, the polymerlsation process may be varled to modlfy propertles of the copolymer product. Such process varlatlons, as known in the art, can determine whether the copolymer formed ls linear, branched or core-shell. Sultable processes include batch, seml-batch, and pre-emulslflcatlon processes. Preferred processes are seml-batch or pre-emulslflcatlon processes wlth starve feed of the monomers.
An example of a sultable reactlon mlxture to prepare the copolymers ls from about 30% to about 40%, of the total welght of the reactlon mlxture, of monomers, up to about 2.0% of a chaln transfer agent, an lnltlator and from about 1% to about 2% of a surfactant, preferably about 2%.
It is partlcularly preferred to use a combinatlon of nonionic surfactant and lonic surfactant. The chain transfer agent may be used to modlfy propertles such as shear strength, heat resistance and water solubility or dlspersibility of the product. For example, a copolymer havlng satlsfactory adhesive properties but lacking satisfactory water solubility or water disperslbillty, may be rendered more water soluble or dlspersible by increasing the quantity of chain transfer agent ln the reaction mixture during polymerizatlon and formation of the copolymer.
Polymerization may be effected by dissolving or dispersing the monomers in deionized water at a concentration of about 30% to about 40% by weight to pre-emulsify them.
0.3% of the surfactant is added to the reaction vessel with the remainder added to the monomer mixture. For a general procedure where the polymerization ls conducted ln a reactlon volume of approximately 1 liter, the initiator is dissolved in about 30 ml of deionized water and 5 ml of this initiator solution ls added to the reactlon vessel. When a chaln transfer agent ls used, it is also added to the reaction vessel. The contents of the reaction vessel are heated to about 60 to 80~C to form free radicals. A portion of the pre-emulsified monomers (about 20 to about 30 mL) is fed into the reaction vessel. After about 5 minutes, polymerization is initiated. The monomers and the initiator are fed simultaneously and continuously into the reaction mixture dropwise until all the monomer and initiator have been added to the reaction vessel. The reaction is allowed to proceed for about 4 hours.

When the reaction is complete, the resulting copolymer solutlon ls cooled to room temperature and flltered to remove any coagulum. If other compounds are to form part of the adhesive composition, such as plasticlzers or tacklfiers, they may be added either before, during or after the polymerizatlon process. The resultlng aqueous, pressure sensitive adhesive composition typlcally comprlses from about 20% to 50% by welght sollds.
When an initiator is used whlch generates acld durlng the polymerlzatlon, such as persulfate lnltlators, it is customary to neutralize the final copolymer emulsion.
Neutrallzatlon can be accompllshed wlth, for example, butyldlethanol amlne or metal carbonates. Such neutrallzatlon reduces corroslveness of adheslve formulatlons prepared wlth the copolymers.
The chaln transfer agents may be water or oll soluble. Up to 5%, preferably from 0.5% to 1%, based on the total welght of the monomers, of the chaln transfer agent may be used. Typical chain transfer agents include mercaptoacetic acld, mercaptoethanol,

3-mercapto-1,2-propanediol, A-189 (available from Unlon Carblde) and l-dodecanethlol.
The inltiator is typlcally used at a level of 2%, preferably 0.5 to 1% by welght based on the total welght of the monomers. The lnltlators may be oll or water soluble.
Thermal, redox, or UV lnltlator systems may be used.
Suitable initiators include potassium persulfate and

4,4'-azobls(4-cyanovalerlc acld).

g The surfactant ls used in an amount of up to 5%, preferably from 1 to 2% by welght, based on the total weight of the monomers. The surfactant may be anlonic, nonionic or a comblnatlon thereof. Many surfactants are commerclally avallable. For example, alkylphenol ethoxylates are avallable under the Tradename Igepal CA or Igepal CO. Rhone-Poulenc offers the followlng surfactants: phosphate esters under the Tradename Rhodafac; sulphonates under the Tradename Rhodacal;
alkyl sulphates under the Tradename Rhodapon; amphoterlc surfactants under the Tradename Abex; and ethoxylated polyoxypropylene block copolymers under the Tradename Antarox. Henkel offers a surfactant under the Tradename Disponil AES-21 whlch ls an alkylphenol ether sulphate sodlum salt.
The presence of the zwltterlonlc component ln the copolymers means that cross-llnklng agents ~whlch are often added to pressure-sensltlve adheslve copolymers to lmprove coheslve strength and heat reslstance) are not always requlred slnce the zwitterlonic functlon provldes some lonlc cross-llnklng.
The use of a cross-llnklng agent may be advantageous to lmprove heat reslstance or coheslve strength.
However, lf a water soluble or water disperslble copolymer ls requlred, such as a repulpable copolymer for papermaklng, it should be noted that increaslng cross-linking reduces repulpabillty and that lf there is too much cross-llnklng the copolymer wlll not readlly dlsperse under the condltlons needed for repulplng ln a papermaklng process. Up to 2% by 2! 94733 weight, based on the total welght of the monomers, of a cross-llnking agent may be used. If a cross-llnklng agent ls used, a preferred range ls from 0.5 to 1% based on the total weight of the monomers. Sultable cross-llnklng agents include metal chelates, epoxldes, azlrldlnes, melamlne formaldehyde resins and polyamlde eplchlorohydrlns.
Generally the zwltterlonlc copolymers are water-dlspersible or water soluble and can be used as an adhesive component, wlth an approprlate tacklfier or plasticizer, of repulpable PSA compositions. Some of the zwitterlonic copolymers may need some additional modificatlon to be sultable for repulpable adhesive composltlons. For example, as mentioned above, chaln transfer agents may be added during polymerization to reduce the molecular welght of the final copolymer and thus increase the water solubllity or dlsperslbllity.
Plasticlzers and tackifiers are generally added to the adhesive copolymers to form adhesive compositions.
Conventional tackiflers include polysaccharide gums, roslns, rosln derlvatlves (such as Tacolyn 98 avallable from Hercules), alkyl/aryl hydrocarbon resins and derivatives, and petroleum-aliphatic resins. Conventlonal water dlsperslble plasticlzers include polyoxyethylene alkylphenyl ether phosphates, polyoxyethylenealkyl ether phosphates, polyethyleneglycolmonophenyl ethers, octylphenoxypoly(ethyleneoxy) ethanols and nonylphenoxypoly(ethyleneoxy) ethanols.
In vlew of the zwltterionlc nature of the adhesive ~ 1 94 733 copolymers, zwitterlonic tackifiers and plasticizers, such as those disclosed in applicant's copending applicatlon (attorney docket No. 60557-4987, hereby lncorporated by reference), have been found to be most suitable.
Such zwitterlonic tackifiers and plasticizers include the following compounds of formula I

R - IN -(cH2)~ ~EI-(CH2)y -Z (I) wherein R1, R2 and R3 are each alkyl, hydroxyalkyl, aminoalkyl or aryl which may be lnterrupted in the alkyl chaln by one or more oxygen atoms, R4 is H or OH, Z~ ls CO2~ or SO3~, x and y are each 0, 1 or 2 provided that the sum of x and y is less than or equal to 4 preferably the sum of x and y is less than or equal to 3.
Preferably the alkyl groups ln the above moleties of R1, R2 and R3 have from 1 to 12 carbon atoms, more preferably from 1 to 8 and in partlcular from 1 to 2 carbon atoms.
It is also preferred that R2 and R3 are the same and R1 ls dlfferent.
Partlcular examples of such tackifiers and plasticizers are:

4Hg-O-CH2-CH-CH2- 1 -CH2-CH-CH2-SO0 N (2_hYdrV~CY 3_S~ VY~1)-N,N dimethY1-N-(3-bUtY10AY-2-L~J~V~O~ betaine C8Hl7-O-CH2-CH~H2- 1 ~ -CH2-CH-CH2-SO3 N-(2-hYdrV~CY-3-SU1PI~V~ 1)-N,N-J~ 1-N-(3-OCtY1O~Y-2 ~V~Y,VY~V betaine N-(2-~ r~A~-3-sulpl~ y,l)-N,N-di~l-N-(3~ vA,~,~l)-~mm~ b~

HO-CHz-CH-CH2-IN -CHz-CH2-CH2-SO3 N-(3 L ~h~VY~1)-N,N~1~m~ ~1-N-(2,3-d;h~O~Y~ ne 2 0 H~-CHrCH2-~-CHrCHrN~9 -CHrCHrCH2-S00 N-(3 ~ )-N-N dime~YI-N-2-(2-~A,~ ~thyloAy)e~y~ . . betaine HO-CHrCHr IN~ ~HrCHrCH2-SO30 N_(3_;~ >~VY,1) N,N dim~yl N
(2-1~ ~A~ 1) a~--- ' ~ betaine CH3-CHrCH2-CHr~ -CH2-CHrCH2-SO3 tBU diEtOH

N-(3 ~ v~>~v-N~N-di(2-h~d~v.~,lh,~l)-N-butyl a~ . n ~ . betai~e CH3- IN~3 -CH2-CH2~HrSO3~ IMe diE~tOH
CHzCH20H
N-(3-slllr~ plolJ,I)-N,N di(2-l~ A~,thyl)-N-me~yl ~ ilTm be~ine HO-CH2-CH2-CH2- 1 -CH2-CH2-CH2-SO3 [diMe l-prOHl N-(3-s~ h-~ol~l)-N~N~l;~ -N-(3-h~hvA~ m betaine OH CHrCH2-OH
CH3-CH-CH2- IN -CH2-CHrCHrSO3 [diEtOH 2-prOHl CHrCH2-OH

N-(3 ~ pt~ l)-N~N-di(2-h~LvA~hyl)-N-(2-hyd - ~ m be~ine CH34cH2)r 1 -cH2-cH2-cH2-so3 N-(3~ul~ho~,1)-N,N di(2-hydtoAyethyl)-N oc~yl ammonium betaine CH3-(CH2)S- IN -CH2-CHrCHrSo/33 v~

N-(3 sul~ -N,N di(2-hyd~oyethyl~N-he~yl ~ 5~ betaine Of the above, N-(2-hydroxy-3-sulphopropyl)-N,N-dimethyl-N-13-hydroxypropyl)-ammonlum betalne, Bu dlEtOH, Me dlEtOH, diME l-prOH and dlEtOH 2pr-OH are preferred.
As ls known, varlous other compounds can be added to lmprove the characteristics of the final adhesive formulation. Compounds such as PVP K-30 and PVP K-90 (commercially avallable polyvlnylpyrrolldones of molecular welght 57,500 and 1,270,000 respectlvely) can be added to improve the strength and toughness of the base adhesive copolymer. FC-171 (a fluorochemical) can be added, for example as a 10% aqueous solution, to improve wetting characterlstlcs of the flnal adheslve formulatlon.
The tackifiers and plasticizers are added to an adheslve polymer, together wlth any other addltlves, to form an adhesive composition. Whilst the amounts used may vary dependlng on the nature of the components of the adheslve composltlon, generally they are effective when added at a rate of 30 to 100 parts by welght based on 100 parts by welght of the adhesive polymer. Such adhesive compositions may be prepared in the usual way by blendlng or mlxing. The tackifiers and plasticizers may be added, for example, to an aqueous emulsion of the formed adhesive polymer, or may be added to a monomer feed stream before formation of the adhesive polymer.
A pressure sensitive adhesive tape may be made by applylng the pressure sensltive adhesive composltlon to one or more surfaces of a substrate backlng to form a one-sided or double-slded tape. If the tape ls to be repulpable, the substrate backing should also be repulpable. The adheslve may be fortifled with a repulpable tlssue for the construction of double-slded tapes. Sultable repulpable tlssues may be obtalned from Burrows Paper Corporation.
A release liner may be used to cover and protect the exposed surfaces of the pressure sensltlve adheslve tape between manufacture and use. Commerclally avallable release llners lnclude sillconlzed paper release llners.
Repulpable adheslves may be applied directly to a substrate, that ls, wlthout any backlng, by means of a brush or ln the form of a spray or a bead. For example, ln papermaklng, the PSA may be applied to a paper surface ad~acent the tralllng edge of one roll and then the leadlng edge of the next roll may be pressed dlrectly onto the adhesive thus ioining the edges of the two rolls. When used wlthout a backlng, the adheslve can be fortlfled wlth flbres for easy handling. For a repulpable tape, sultable flbres lnclude celluloslc flbres or polyvlnyl alcohol flbres.
Repulpable PSA formulatlons should adhere to at least common types of paper such as AKD slzed; paper for offset prlntlng ("offset"); European bond paper; Canadlan bond paper; and paper for rotogravure prlntlng ("rotogravure").
It has been found that the use of zwltterionic polymers ln formulatlng adheslve composltlons may also provlde the followlng advantages both high tack and low tack formulatlons may be prepared from a common base polymer;
neutrallzatlon of the polymers may not be required to provide water dlspersibllity; curing agents may not be needed to give the polymers heat resistance and cohesive strength; and the polymers may be formulated into adheslve composltlons whlch have well-balanced propertles.
Besldes repulpable adheslves for papermaklng the adheslves and adheslve formulatlons of the lnvention are also useful for a variety of other appllcatlons such as for labels, masklng tapes and stamps as well as for vapour strippable products such as wall paper or other decorative wall coverlngs.

TEST PROCEDURES
It ls belleved that a brlef explanation of certaln test procedures will be helpful in understanding the invention.

Delrin wheel tack test In thls test, a standard Delrln wheel welghlng 28.8 g wlth dlameter of 8.13 cm ~3.2 lnches), a rlm wldth of 1.9 cm (0.75 lnches), a thickness of 0.16 cm (1/16 inches), a hollow axle with a dlameter of 1.27 cm (0.5 lnches) and a length of 3.175 cm (1.25 lnches) ls rolled down a plane havlng a length of 26.7 cm (10.51 inches) and lncline of 24 degress to a horizontal surface on which the tape to be evaluated is posltloned, adhesive slde up. The dlstance the wheel rolls along the horlzontal adhesive surface is measured in mm, the tack being inversely proportlonal to the dlstance.
For an adhesive formulation for a permanent tape, the 2! ~4733 distance the Delrln wheel rolls may be around 300 mm or more.
The shorter the dlstance the wheel rolls, the greater the tack. For example, for the greater tack requlred by an adheslve formulatlon for a temporary tape, a lower value, such as 30 mm, mlght be expected.

Repulpablllty Dlsperslbility is measured by evaluating repulpabillty accordlng to TAPPl test UM-213. Samples are prepared by coating 13-24 grains per 24 sq in (0.3 g per 8 sq ln) of the adheslve or adheslve formulatlon to be tested onto one side of a backlng strip 20 cm by 2.54 cm (on each slde to test double faced tape). For double faced tape, one sample is sandwlched between two 20 cm x 2.54 cm strips of blotter paper; and for slngle faced tape, two samples are adhered to blotter paper. The samples are cut into approximately 1.5 cm squares. To these squares are added a sufficient number of 1.5 cm squares of uncoated blotter paper to make a total of samples and uncoated blotter paper of 15 g, and all the squares are placed in a Waring blender with 500 mL of water.
The blender ls run at low speed (approxlmately 15,000 rpm).
After the blender has run for 20 seconds, lt is stopped for 1 mlnute whlle the stock which has splashed up the sldes is washed back lnto the bottom with a water bottle. The blender ls again run for 20 seconds, washed down as before, and run for a final 20 second cycle. The stock ls then removed from the blender and made lnto a handsheet on a sheet mold. The sheet ls removed from the mold, pressed between sheets of 2~ 94733 blotter stock for 1.5 minutes in a hydraulic press, dried, and examined for any particles of unrepulped tape. If no particles are present, the tape is considered to have passed the test.
Another method for determining the repulpability of these products is the PTS Method. In this method the adheslve or adhesive formulation was coated on akrosil backing at 13 to 15 grains per 24 square lnches. 2g strlps of the coated backing were combined with 48 g of European copy paper to form the samples to be tested. The test is normally conducted at pH 7, but pH 4 and pH 10 may be used for a full test to determine repulpability under acidic and alkaline conditions. The samples are added to 2000 ml of water and transferred into a standard dislntegrator. The sample is disintegrated for 10 minutes (+ 30 seconds) with a rotor speed of about 3000 rpm. The pulp suspenslon ls put ln a vessel, diluted to a total volume of 10 L and homogenized for approximately 2 mlnutes. 400 ml samples of the resultlng homogenlzed liquid are removed to make handsheets. The test handsheets, so prepared, are vlewed agalnst a light source.
Any defects or transparent spots, caused by non-disperslble constltuents ln the homogenized liquid used to prepare the handsheets, are counted and characterized by size and colour.
If no defects or transparent specs are observed, the formulation used in the sample will be considered repulpable. If a few transparent specs are observed, the formulation will be considered "marginally" repulpable. That is, the substance will be considered water dlsperslble but _ 21 94733 not repulpable according to the PTS test used.
These tests do not apply to tape products where the backing is a polyester film, which does not lend itself to repulping. Such backings are strong, however, and may be used in tape constructions, provlded the loosed backing ls mechanlcally removed.
Unless otherwlse stated, the PTS test method at pH
7 was used for repulpablllty tests ln the followlng examples.

T-Peel Adhesion test The sample is measured in the cross direction of the tape. The machine direction in the direction ln whlch the adhesive is laid down on the backlng as lt ls unwound.
The cross dlrectlon ls perpendlcular to the machlne direction.
A 1" (2.54 cm) sample of tape is cut in the cross direction of the tape approximately 8cm long. This sample is laminated to a slmllar slzed plece of test paper leaving approximately 2.5 cm un~oined to allow a strip of each layer of the laminate to be placed ln each of the two ~aws of a tensile tester. The prepared sample is rolled four times uslng a 2 kg roller. The sample is allowed to acclimatize for 1 minute (dwell time) before testing.
For a double-sided tape, the same slze sample ls laminated between two 1" (2.54 cm) wide strips approxlmately 8 cm long, so that the cross direction of the tape is in the direction of the long slde of the paper. The sample is then rolled in the same manner as for testing of a single sided tape.
For testlng, the sample is placed in the ~aws of the tenslle tester. The sample then resembles a "T" havlng the un~olned ends in each ~aw and the tail of the "T"
horizontal. The ~aws are then separated at a speed of 50 mm/min (2"/min). The force required to separate the ~aws is the T-peel value and is measured in Newtons/cm (N/cm). The mode of peel may also be recorded.

Statlc Shear A static shear test provides information on the ability of the splice to withstand shear forces in a paper processing operation. An overlap splice (2.54 cm x 2.54 cm) is prepared and pressed with a 2 kg roller (4 passes). The splices are condltioned for 20 minutes to acclimatize them to the temperature and humidity of the test conditlons, and then ~

a 1 kg weight ls suspended from the splice in a vertical manner. The time in minutes for the splice to fail is recorded.

Heat reslstance This test simulates the shear forces encountered by a paper splice at elevated temperature.
An overlap splice (2.S4 cm x 2.54 cm) is prepared and rolled twice wlth a 6.8 kg (15 lb) roller. Within one minute of preparation, the splice ls contacted with a curved heated surface, which is malntained at 150 C. One end of the splice is held with a clamp to prevent it from moving during the test. The other end of the splice is threaded over the curved surface. A 2 kg weight is attached to this end whlch is allowed to hang, supportlng the weight. The tlme requlred for the splice to separate (adhesive shear failure) is then measured ln seconds. The tlme ls measured from the moment of first contact with the heated surface. If the splice does not separate ln 2 minutes, the amount of sllppage ln mm ls recorded.

ABBREVIATIONS
In the following examples and tables, abbrevlations used are as follows:

AA stands for acrylic acid;
BA stands for butyl acrylate;
EOA stands for 2-ethoxyethyl acrylate;
EOEOA stands for 2-(2-ethoxy)ethoxyethyl acrylate;

IOA stands for iso-octyl acrylate;
MEA stands for 2-methoxyethyl acrylate;
BuOEtA stands for 2-butoxyethyl acrylate;
CTA stands for chaln transfer agent;
AES-21 stands for Disponil AES-21 whlch ls a surfactant;
SPE stands for N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betalne;
SP-A stands for N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dlmethyl ammonium betalne;
HEA stands for 2-hydroxyethyl acrylate;
EHA stands for 2-ethylhexyl acrylate;
Bu diEtOH, Me diEtOH, diMe 1-prOH and diEtOH 2-prOH refer to the zwltterlonic compounds obtained by reaction of 1,3-propane sultone wlth butyldlethanol amine, methyldiethanol amine, N,N-dimethyl-1-propanol amlne and N,N-dlethanol-2-propanol amine respectively. The full structures of these four zwitterionic compounds are glven above.

PREPARATION OF COPOLYMERS
BA/SPE
A 1-litre resin flask was charged with butyl acrylate (24 g,0.188 mol), SPE (16.8 g, 0.060 mol), Trlton X-200 (2.9 g, 2% by weight based on monomers, 28% active) and deionized water (122 mls). The flask was fltted wlth a mechanlcal stirrer and an argon purge. The contents were stlrred, heated at 60~C and purged for one hour. Potassium persulfate (0.397 g, 0.0015 mol) was added and the reactlon 21 ~4733 was continued for five hours. The emulsion was cooled to amblent temperature. The product was characterlzed by DMA
and elemental analysls.
The above method was repeated varying the mole % of the two monomers to obtaln a serles of copolymers of graded zwltterionic content. The mole % of the monomer mixtures used to obtaln each copolymer is shown below in Table A as Examples A through I.

TABLE A

Preparation Example BA SPE

The copolymers obtained, without formulation with other additives, were then tested for repulpabillty using the PTS method as described above. The copolymers of examples F, G, H and I were found to be repulpable without further modiflcation of the copolymer. The copolymers of examples D

and E showed some small specs and were considered marginally 30 repulpable.

2~ 94733 The other copolymers used in the examples were prepared simllarly to the preparatlon of BA/SPE glven above by varying the nature and quantity of the monomers.

Examples 1-1 to 1-8 Copolymers were prepared uslng varlous monomers in combination wlth the zwitterionic monomer SPE. The copolymers were prepared by batch or pre-emulsification polymerization.
To illustrate, details of the preparation of Examples 1-5 and 1-6 are provided. The other copolymers of Examples 1-1 to 1-8 were obtalned by similar procedures.

Preparatlon of ExamPles 1-5 and 1-6 PreParatlon of Example 1-5 Into a l-lltre reactlon vessel were placed the followlng monomers: butyl acrylate (27.1 g, 0.21 mol), iso-octyl acrylate (14.2 g, 0.08 mol), SPE (16.1 g, 0.06 mol) and 2-(2-ethoxy)ethoxyethyl acrylate (7.25 g, 0.04 mol). Trlton X-200 (4.62 g) and deionized water (194 g) were added and the flask was fitted wlth a mechanlcal stirrer and purge tubes.
The contents were stirred at 65 to 70~C with purging under argon for 45 minutes. Potassium persulfate (0.43 g) was added and the reaction was allowed to proceed for six hours.

Preparation of Example 1-6 Into a l-lltre reaction vessel were placed the following monomers: butyl acrylate (60 g, 0.47 mol), 2-hydroxyethyl acrylate (4.8 g, 0.04 mol), and SPE (16.8 g, 0.06 mol). Triton X-200 (5.8 g) and deionlzed water (163.2 g) were added and the flask was fltted wlth a mechanlcal stlrrer and purge tubes. The contents were stirred at 65 to 70~C with purging under argon for 45 mlnutes. Potassium persulfate (0.212 g) was added and the reactlon was allowed to proceed for five hours.
Table 1 shows the proportlons of monomers used ln each of the examples in mole % of the total monomer content of the polymerization mixture. The monomers BA and IOA are examples of hydrophobic monomers and EOEOA, HEA and AA are examples of hydrophilic monomers. The proportions used in Examples 1 to 8 produced copolymers havlng a hydrophoblc character.

Table 1 Hydrophobic Copolymers Exxmple BA IOA EOEOA HEA AA SPE

1-6 82 7.4 10.6 1-7 76.4 5.2 18.4 The copolymers of Examples 1-1 to 1-7 were then used as base adheslve copolymers to prepare adheslve formulations l-lF to 1-7F by addlng tacklflers, plastlclzers, PVP K-90 and FC-171 ( 10%) and ad~ustlng the pH with butyldlethanol amlne. The composition and final pH of each formulatlon ls shown ln Table lF . In each formulation ln Table lF, "tack 1" was Bu diEtOH, "tack 2" was Tacolyn 98 and "Plast" was N-(2-hydroxy-3-sulphopropyl)-N,N-dlmethyl-N-(3-hydroxypropyl)-ammonlum betalne. Besldes the pH values, the quantltles shown in Table lF are all parts by welght based on one hundred parts by weight of the base adheslve copolymer.
10 Table lF: Formulations for the Hydrophobic Copolymers 1-1 to 1-7 of Table CodeTack 1 Tack 2 Plast PVP FC-171 pH
l-lF 10 10 0.05 7.35 1-2F 40 10 0.05 6.78 1-3F 40 11.5 0.05 6.61 1-4F 40 10 0.05 7.68 1-5F 40 10 0.05 7.41 1-6F 60 2 2 0.06 4.51 1-7F 60 2 2 0.06 7.68 The seven formulatlons, l-lF to 1-7F, were tested on flve types of paper: AKD si2ed; offset; bond (European);
bond (Canadlan); and rotogravure. The tests were: shear strength; heat reslstance; T-peel; and wheel tack (Delrin wheel). The test procedures were those descrlbed above. The results for each formulatlon are shown ln Tables l-lF to 1-7F.

2 1 q4 733 Table l-lF ~BA/IOA/HEA/SPE, 55/20/5/20) Paper Shear Heat T-PeelWheel Tack Strength Resistance .
(150 C 2kg) N/cm mm min. sec.
mm AKD Sized 1226+ 120+ 0.04 300 0.1 Offset 10000 120+ 0.31 247 0.1 Bond (Eur) 1604 120+ 0.04 300 0.1 Bond (Can) 6629 120+ 0.08 300 0.1 Rotogravure 10000 120+ 0.63 42 0.1 Table 1-2F (BA/IOA/HEA/SPE, 52/21/16/11) Paper Shear Heat T-PeelWheel Tack Strength Resistance (150~C 2kg) N/cm mm min. sec.
mm AKD Sized 10000 120+ 0.12 300 0.1 Offset 10000 120+ 1.26 300 0.25 Bond (Eur) 10000 120+ 0.12 300 0.1 Bond (Can) 10000 120+ 0.47 300 0.1 Rotogravure 10000 120+ 0.94 104 0.25 Table 1-3F (BA/IOA/HEA/SPE, 55/20/10/15) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150 C 2kg) N/cm mm min. sec.
mm AKD Sized 1662 120+ 0.08 300 0.2 Offset 10000 120+ 0.83 92 0.15 Bond (Eur) 1507 120+ 0.08 300 0.1 Bond (Can) 5522 120+ 0.16 300 0.1 Rotogravure 10000 120+ 0.87 182 0.25 Table 1-4F (BA/IOA/HEA/SPE, 20/55/5/20) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150~C 2kg) N/cm mm min. sec.
mm AKD Sized 740 120+ 0.08 300 0.2 Offset 10000 120+ 0.71 245 0.5 Bond (Eur) 457 120+ 0.08 300 0.4 Bond (Can) 299 120+ 0.16 300 0.25 Rotogravure 10000 120+ 0.98 103 0.3 Table 1~5F (BA/IOA/EOEOA/SPE, 55/20/10/15) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150 C 2kg) N/cm mm min. sec.
mm AKD Sized 421 120+ 0.12 300 0.2 Offset 23630 120+ 0.91 197 0.5 Bond (Eur) 157 120+ 0.20 300 0.4 Bond (Can) 288 120+ 0.43 300 0.25 Rotogravure 10000 120+ 0.98 37 0.3 Table 1-6F ~BA/HEA/SPE, 82/7.4/10.6) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150 C 2kg) N/cm mm min. sec.
mm AKD Sized 2988 120+ 0.87 230 0.1 Offset 10000 120+ 1.65 75 0.1 Bond (Eur) 1529 120+ 0.98 114 0.0 Bond (Can) 10000 120+ 1.65 200 0.05 Rotogravure 10000 120+ 0.98 30 0.0 - 2! 94733 Table 1-7F (BA/AA/SPE, 76.4/5.2/18.4) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150~C 2kg) N/cm mm min. sec.
mm AKD Sized 263 120+ 0.98 300 0.3 Offset 1504 Failed 2.17 118 Bond (Eur) 243 120+ 1.14 300 0.15 Bond (Can) 486 120+ 1.73 300 0.3 Rotogravure 2550 120+ 0.75 65 0.2 Each of the seven formulations, l-lF to 1-7F, was tested for repulpablllty uslng the PTS method as descrlbed above. The formulatlons of Examples 1-2F and 1-7F were found to be repulpable wlthout further modlflcatlon of the base adhesive copolymers.

Examples 2-1 to 2-9 Copolymers were prepared uslng various monomers ln combinatlon wlth the zwltterlonlc monomer SPE or both SPE and 20 SP-A.
To lllustrate, detalls of the preparatlon of Examples 2-4, 2-5, 2-6, 2-7 and 2-8 are provlded. The other copolymers of Examples 2-1 to 2-9 were obtalned by slmilar procedures.

Preparation of Copolymers of Examples 2-4, 2-5, 2-6, 2-7 and Preparation of Example 2-4 Into a l-lltre reactlon vessel were placed SPE
(4.39 g, 0.016 mol), SP-A (4.17 g, 0.016 mol), AES-21 (1.70 g), Trlton X-405 (0.62 g), delonlzed water (103 g), and sodlum carbonate (0.13 g). The contents were stlrred at 70~C
and purged for 20 minutes. Potasslum persulfate (0.32 g) was dlssolved ln a mlnlmal amount of water and was added ln one portlon. 2-Ethoxyethyl acrylate (25.7 g, 0.178 mol) was added dropwlse over 12 minutes and the reactlon was allowed to proceed for an additional 50 mlnutes.

Preparation of Example 2-5 Into a 250 mL reaction vessel were placed SPE (3.74 g, 0.013 mol), SP-A (3.55 g, 0.013 mol), 2-hydroxethyl acrylate (2.84 g, 0.02 mol), 2-butoxyethyl acrylate (24.6 g, 0.14 mol), delonized water (105 g), AES-21 (1.77 g), and Trlton X-405 (0.2 g). The contents were stlrred for seven mlnutes and sodlum carbonate (0.14 g) was added to the reaction. The contents were brought to a temperature of 70~C. After purglng for 40 mlnutes the potasslum persulfate (0.35 g) was added. The reactlon was allowed to proceed for an additlonal 1 hour 25 minutes.

2! 94733 Preparatlon of Example 2-6 In a l-lltre reactlon vessel were placed the followlng monomers: 2-butoxyethyl acrylate (18.23 g, 0.11 mol), SPE (2.62 g, 0.009 mol), SP-A (2.49 g, 0.009 mol), Trlton X-200 (1.67 g), and deionlzed water (70 g). The flask was fitted with a mechanical stirrer and purge tubes. The contents were stirred at 65~C with purging under argon for 1 hour 30 minutes. Potassium persulfate (0.15 g) was added and the reactlon was allowed to proceed for eight hours.

Preparatlon of Example 2-7 Into a 500 mL reaction vessel were placed SPE (4.48 g, 0.016 mol), SP-A (4.26 g, 0.016 mol), deionized water (125 g), AES-21 (1.93 g), and Triton X-405 (0.24 g). The contents were stirred for 5 minutes and sodium carbonate (0.16 g) was added. The contents were brought to a temperature of 70~C.
After purging for 30 minutes the potassium persulfate (0.42 g) was added. 2-Butoxyethyl acrylate (22.81 g, 0.132 mol) and 2-ethylhexyl acrylate (10.18 g, 0.055 mol) were combined and added dropwise over 25 minutes. The reaction was allowed to proceed for an additlonal 52 mlnutes.

Preparation of Example 2-8 Into a 250 mL reaction vessel were placed SPE (4.60 g, 0.016 mol), SP-A (4.37 g, 0.016 mol), deionlzed water (105 g), AES-21 (1.95 g), and Triton X-405 (0.24 g). The contents were stirred for 15 minutes and sodium carbonate (0.17 g) was added to the reaction. The contents were brought to a temperature of 70~C. After purging for 34 minutes the potassium persulfate (0.43 g) was added. 2-Butoxyethyl acrylate (9.46 g, 0.06 mol) and 2-ethylhexyl acrylate (24.3 g, 0.13 mol) were comblned and added dropwlse over 20 minutes. The reaction was allowed to proceed for an additional one hour.
Table 2 shows the proportions of monomers used in each of the examples in mole % of the total monomer content of the polymerization mixture. The monomer EHA is a 10 hydrophobic monomer. Monomers MEA, EOEOA, EOA, BuOEtA and HEA are hydrophilic monomers. The copolymers prepared in these examples had a hydrophllic character.

Table 2 Hydrophilic Copolymers Example EHAMEA EOEOA EOA BuOEtA HEA SPE SP-A

2-4 85 7.5 7.5 2-5 7112 6.7 6.7 2-6 85 7.5 7.5 2-7 25 60 7.5 7.5 2-8 60 25 7.5 7.5 The copolymers of Examples 2-1 to 2-9 were then used as base adhesive copolymers to prepare adhesive formulations 2-lF to 2-9F by adding tackifiers, plastlcizers, PVP K-90 and FC-171 (10%) and ad~usting the pH with butyldiethanol amine as was done for Examples 1-1 to 1-7.
The base adhesive copolymers used for formulations 2-lAF and 2-3F were prepared by polymerlzing the monomer mixture in contact with 0.5 parts by weight, based on 100 parts by weight of the total monomer mixture, of l-dodecanethiol as a chaln transfer agent (CTA). The composltlon and flnal pH ls shown ln Table 2F. In each formulatlon ln Table 2F, "tack l"
was Bu diEtOH, "tack 2" was Tacolyn 98, "tack 3" was a mixture of 87% by weight of Bu diEtOH and 13% by welght of Me diEtOH, and "plast" was N-(2-hydroxy-3-sulphopropyl)-N,N-dimethyl-N-(3-hydroxypropyl)-ammonium betaine. Besldes the 10 pH values, the quantltles shown ln the table are all parts by welght based on one hundred parts by weight of the base adhesive copolymer.

Table 2F: Formulations for the Hydrophilic Copolymers 2-1 to 2-9 of Table Code Tack 1 Tack 2 Tack 3 Plast PVP FC-171 CTA pH
2-lF 40 10 0.05 7.65 2-lAF 40 10 0.05 0.5 7.95 2-2F 40 10 0.05 6.18 2-3F 40 10 0.05 0.5 8.53 2-4F 40 0.06 5.31 2-5F 40 10 0.06 3.47 2-6F 40 0.05 8.52 2-7F 40 0.06 4.19 2-8F 40 0.06 4.19 2-9F 70 0.8 0.07 8.22 Each of the formulatlons, 2-lF to 2-9F, was tested 30 on five types of paper: AKD sized; offset; bond (European);
bond (Canadian); and rotogravure. The tests were: shear strength; heat resistance; T-peel; and wheel tack (Delrin wheel). The test procec~ures were those described above. The 2~9~733 results for each formulatlon are shown ln Tables 2-lF to 2-9F.
Table 2-lF (MEA/SPE, 85/15) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150 C 2kg) N/cm mm min. sec.
mm AKD Sized 160 120+ 0.08 Not 0.2 Determined Offset 10000 120+ 1. 5 Not 0.25 Determined Bond (Eur) 1382 120+ 0.08 260 0.15 Bond (Can) 10000 120+ 0.35 Not 0.25 Determined Rotogravure 10000 120+ 1.14 200 0.1 Table 2-lAF (MEA/SPE, 85/15) Paper Shear Heat T-PeelWheel Tack Strength Resistance (150~C 2kg) N/cm mm min. sec.
mm AKD Sized 974 120+ 0.71 300 0.5 Offset 4032 120+ 0.79 31 0.7 Bond (Eur) 1557 120+ 0.98 300 0.6 Bond (Can) 1542 120+ 1.34 164 0.5 Rotogravure 3904 120+ 0.63 26 0.6 Table 2-2F (EOEOA/SPE, 90/10) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150~C 2kg) N/cm mm min. sec.
mm AKD Sized 142 120+ 0.12 300 0.5 Offset 4334 120+ 0.94 59 0.15 Bond (Eur) 482 120+ 0.16 300 0.15 Bond (Can) 577 120+ 0.63 205 0.1 Rotogravure 10000 120+ 0.95 41 0.15 Table 2-3F (EOEOA/SPE, 85/15) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150 C 2kg) N/cm mm min. sec.
mm AKD Sized 20.7 Failed 2.01 134 Offset 30.9 Failed 2.40 105 Bond (Eur) 24.1 Failed 2.28 300 Bond (Can~ 25.8 Failed 2.20 133 Rotogravure 39.1 Failed 1.97 38 21 q4733 Table 2-4F (EOA/SPE/SP-A, 85/7.5/7.5) Paper Shear Heat T-PeelWheel Tack Strength Resistance (150 C 2kg) N/cm mm min. sec.
mm AKD Sized 74.3 120+ 0.1 300 0.8 Offset 138 Failed 0.51 300 Bond (Eur) 84 120+ 0.08 300 0.3 Bond (Can) 66 120+ 0.16 Not 0.4 Determined Rotogravure 3562 120+ 0.79 Not 0.0 Determined Table 2-5F (BuOEtA/HEA/SPE/SP-A, 71/12/6.7/6.7) Paper Shear Heat T-PeelWheel Tack Strength Resistance (150 C 2kg) N/cm mm min. sec.
mm AKD Sized 16 120+ 0.06 300 0.0 Offset 5604 120+ 0.51 Not 0.0 Determined Bond (Eur) 11 120+ 0.12 300 0.0 Bond (Can) 4328 120+ 0.08 Not 0.3 Determined 20Rotogravure 5603 120+ 0.51 300 0.0 Table 2-6F (BuOEtA/SPE/SP-A, 85/7.5/7.5) Paper Shear Heat T-PeelWheel Tack Strength Resistance (150 C 2kg) N/cm mm min. sec.
mm AKD Sized 4260 120+ 2.63 21 0.6 Offset 4260 Failed 2.13 14 Bond (Eur) 4260 120+ 2.20 25 0.6 Bond (Can) 4260 120+ 2.36 17 0.8 Rotogravure 4260 120+ 2.36 24 0.35 Table 2-7F (EHA/BuOEtA/SPE/SP-A, 25/60/7.5/7.5) Paper Shear Heat T-PeelWheel Tack Strength Resistance (150~C 2kg) N/cm mm min. sec.
mm AKD Sized 35 120+ 0.2 42 0.2 Offset 1632 120+ 0.63 23 0.15 Bond (Eur) 113 120+ 0.39 55 0.1 Bond (Can) 29 120+ 0.43 23 0.1 Rotogravure 1632 120+ 1.1 20 0.0 Table 2-8F ~EHA/BuOEtA/SPE/SP-A, 60/25/7.5/7.5) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150~C 2kg) N/cm mm min. sec.
mm AKD Sized 585 120+ 0.74 70 0.2 Offset 1624 120+ 1.46 23 0.4 Bond (Eur) 1624 120+ 1.02 42 0.35 80nd (Can) 1624 120+ 1.46 21 0.3 Rotogravure 1624 120+ 1.46 16 0.4 Table 2-9F (MEA/SPE, 87/13) Paper Shear Heat T-Peel Wheel Tack Strength Resistance (150 C 2kg) N/cm mm min. sec.
mm AKD Sized 192 120+ 0.63 96 0.4 Offset 177 Failed 1.85 25 Bond (Eur) 86 120+ 0.71 86 0.4 Bond (Can) 111 120+ 0.83 43 0.4 Rotogravure 346 120+ 0.79 28 0.6 Each of the formulatlons, 2-lF to 2-9F, was also tested for repulpablllty uslng the PTS method as descrlbed above. The formulatlons of examples 2-lF, 2-lAF, 2-2F, 2-3F, 2-4F and 2-9F were found to be repulpable without further modiflcatlon of the base adheslve copolymers.

Examples 3-1 to 3-4 These examples demonstrate the effectiveness of zwltterlonlc tacklflers ln comblnatlon wlth the zwltterlonlc copolymers. A tacklfier was admixed wlth a copolymer, as the base adhesive copolymer, obtained by polymerizing SPE and MEA in a mole ratio of 13:87 (SPE MEA) (see Example 2-9 in Table 2). Four different zwitterlonlc tacklfiers were used, as shown ln the first column under the headlng "tacklfler".
These tacklfiers were used in varying proportlons of 0.5, 0.63 and 0.75 parts per part of base copolymer by weight and on two different types of paper, bond paper and offset paper.
Each of these composltlons was then subiected to the Delrln wheel test. The base adheslve copolymer alone had a Delrin wheel value of 300mm. The results, ln mm travelled by the Delrln wheel, are shown ln Table 3. As can be seen from the table, addltlon of the tacklfler slgnlflcantly lmproved tack.

Table 3 Tackifier Evaluation - Wheel Tack Paper Bond Offset Tackifier 1:0.501:0.63 1 0.75 1 0.501:0.63 1 0.75 Bu diEtOH 16 15 Me diEtOH 50 45 34 16 20 16 diMe l-prOH 55 63 54 27 23 33 diEtOH 2-prOH 35 18 Examples 4-1 and 4-2 Two PSA composltions, a high tack compositlon and a 30 low tack composltlon, were formulated. The base copolymer ln each case was the copolymer of Example 1-8 of Table 1, a 2~ 94733 copolymer of BA/SPE having a mole ratio of 80 20. The zwitterionic tackifier A was Me diEtOH and B was Bu diEtOH.
The zwitterionic plasticlzer A was N-(2-hydroxy-3-sulphopropyl)-N,N-dimethyl-N-~3-hydroxypropyl)-ammonlum betaine. PVP K-30 and PVP K-90 were added to improve the strength and toughness of the base copolymer of the formulation. FC-171 (10%) was added to improve wetting of the formulation. The quantities used are shown in Table 4 as parts by weight based on 100 parts by weight of the base copolymer.

Table 4 Formulations Material Ex 4-1 High Tack Ex 4-2 Low Tack (parts by weight)(parts by weight) BA/SPE Copolymer 100 100 Zwitterionic Tackifier "A" 60 Zwitterionic Tackifier "B" 50 Zwitterionic Plasticizer "A" 10 20 PVP K-30 3.4 FC-171 (10%) 0.067 0.092 These two formulations 4-1 and 4-2 were then tested on five types of paper: AKD sized; offset; bond (European);
bond (Canadian); and rotogravure. Measurements were taken for the following tests: shear strength; heat resistance; T-peel; wheel tack (Delrln wheel); and repulpablllty (PST
test). In the column headed "repulpablllty" the entry "yes"
indlcates that the formulation was repulpable according to the PTS test described above. The type of paper used is shown in the left hand column under "paper" in Tables 5 and 21 9q733 6. The results of the tests for formulatlon 4-1 (the hlgh tack formulatlon) are shown in Table 5 and the results of the tests for formulatlon 4-2 (the low tack formulatlon) are shown ln Table 6.

-~ 2 1 94733 Table 5 "High Tack" Results (for formulation of Example 4-1) Paper ShearHeat Resistance T-Peel Wheel Tack Repulp Strength , (150~C 2kg) min. sec. mm N/cm mm 10 min.
AKD Size 429.3 150 3.0 1.2 37 Yes Offset 4400 2.0 25 Yes Bond (Eur.) 461.7 150 0.0 1.6 49 Yes Bond ~Can.) 253.1 150 0.0 1.5 54 Yes 10Rotogravure 4400 21 Yes Ta~le 6 "Low Tack" Results ~for formulation of ExamPle 4-2) Paper ShearHeat Resistance T-Peel Wheel Tack Repulp Strength (150~C 2kg) min. sec. mm N/cm mm 10 min.
AKD Size 5600+ 130+ 0.1 0.59 Yes Offset 6944+ 130+ 0.2 1.8 300+ Yes 20Bond (Eur.) 213.2 130+ 0.2 0.19 49 Yes Bond (Can.) 3042+ 130+ 0.1 0.35 300+ Yes Rotogravure 3042+ 130+ 0.4 1.1 241 Yes

Claims (21)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An adhesive composition comprising a zwitterionic copolymer and a zwitterionic plasticizer or tackifier.

2. An adhesive composition according to claim 1 wherein the zwitterionic copolymer has a recurring unit derived from an unsaturated zwitterionic monomer of the formula:

or wherein R5 is a group containing a carbon-carbon unsaturated bond and being selected from the group consisting of (meth)acryloxy-(C2-4)alkyl, (meth)acrylamido-(C2-C4)alkyl or (C2-C6)alkenyl, R6 and R7 are each (C1-C4)alkyl, (C2-C6)alkenyl or (CH2)nOH in which n is 2, 3 or 4, R8 is (C2-C6)alkenyl, z is an integer of 2 to 4 and Z~ is SO3~ or CO2~, and a recurring unit derived from a monomer copolymerizable with the unsaturated zwitterionic monomer selected from the group consisting of a hydrophobic comonomer and a hydrophilic copolymer other than the unsaturated zwitterionic monomer.

3. An adhesive composition according to claim 2 wherein the zwitterionic copolymer comprises (a) N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine or N-(3-sulphopropyl)-N-acryloxyethyl-N, N-dimethyl ammonium betaine and (b) a hydrophobic or hydrophilic comonomer.

4. An adhesive composition according to claim 3 wherein the plasticizer or tackifier is a compound of the formula wherein R1, R2 and R3 are each alkyl, hydroxyalkyl, aminoalkyl or aryl which may be interrupted in the alkyl chain by one or more oxygen atoms, R4 is H or OH, Z~ is CO2~ or SO3~, x and y are each 0, 1 or 2 provided that the sum of x and y is less than or equal to 4.

5. An adhesive composition according to claim 2 wherein the plasticizer or tackifier is N-(2-hydroxy-3-sulphopropyl)-N,N-dimethyl-N-(3-hydroxypropyl)-ammonium betaine, N-(3-sulphopropyl)-N,N-di(2-hydroxyethyl)-N-butyl-ammonium betaine, N-(3-sulphopropyl)-N,N-di(2-hydroxyethyl)-N-methyl ammonium betaine, N-(3-sulphopropyl)-N,N-dimethyl-N-(3-hydroxypropyl)-ammonium betaine or N-(3-sulphopropyl)-N,N-di(2-hydroxyethyl)-N-(2-hydroxypropyl)-ammonium betaine.

6. An adhesive composition according to claim 3 wherein the zwitterionic copolymer comprises from 10 to 50 mole % of N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine or N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dimethyl ammonium betaine.

7. An adhesive composition according to claim 3 wherein the hydrophobic or hydrophilic comonomer is butyl acrylate, iso-octyl acrylate, 2-(2-ethoxy)ethoxy ethyl acrylate, 2-hydroxyethyl acrylate, acrylic acid, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate or 2-butoxyethyl acrylate.

8. An adhesive tape comprising a backing having coated thereon an adhesive composition according to any one of claims 1 to 7.

9. A repulpable adhesive tape comprising a repulpable backing having coated thereon an adhesive comprising a repulpable zwitterionic copolymer.

10. A repulpable tape according to claim 9 wherein the zwitterionic copolymer comprises units derived from a compound of formula II or III

or in which R5 is a group containing a carbon-carbon unsaturated bond such as (meth)acryloxy-(C2-4)alkyl, (meth)acrylamido-(C2-4)alkyl or (C2-C6)alkenyl, R6 and R7 are each C1-4 alkyl, (C2-C6)alkenyl, or (CH2)n OH in which n is 2, 3 or 4, R8 is (C2-C6)alkenyl, z is an integer of 2-4 and Z~
is SO3~ or CO2~.

11. A tape according to claim 9 wherein the zwitterionic copolymer comprises N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine or N-(3-sulphopropyl)-N-acryloxyethyl-N, N-dimethyl ammonium betaine.

12. A tape according to claim 11 wherein the zwitterionic copolymer comprises from 10 to 50 mole % of N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine or N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dimethyl ammonium betaine.

13. A tape according to claim 11 wherein the zwitterionic copolymer comprises (a) N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine or N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dimethyl ammonium betaine and (b) butyl acrylate, iso-octyl acrylate, 2-(2-ethoxy)ethoxyethyl acrylate, 2-hydroxyethyl acrylate, acrylic acid, 2-ethylhexyl acrylate, 2-methoxyethyl acrylate or 2-butoxyethyl acrylate.

14. A tape according to any one of claims 9 to 13 wherein the adhesive composition further comprises a zwitterionic plasticizer or tackifier.

15. A tape according to claim 14 wherein the plasticizer or tackifier is a compound of the general formula whereln R1, R2 and R3 are each alkyl, hydroxyalkyl, aminoalkyl or aryl which may be interrupted in the alkyl chain by one or more oxygen atoms, R4 is H or OH, Z~ is CO2~ or SO3~, x and y are each 0, 1 or 2 provided that the sum of x and y is less than or equal to 4.

16. A tape according to claim 14 wherein the plasticizer or tackifier is N-(2-hydroxy-3-sulphopropyl)-N,N-plasticizer or tackifier is N-(2-hydroxy-3-sulphopropyl)-N,N-dimethyl-N-(3-hydroxypropyl)-ammonium betaine, Bu diEtOH, Me diEtOH, diMe 1-prOH or diEtOH 2-prOH.

17. A zwitterionic copolymer comprising:
(1) a unit derived from (a) N-(3-sulphopropyl)-N-methacryloxyethyl-N, N-dimethyl ammonium betaine, (b) N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dimethyl ammonium betaine or (c) a combination of (a) and (b), and (2) a unit derived from a comonomer copolymerizable with component (1), with the proviso that when component (1) is other than (c) the combination of (a) and (b), then the comonomer (2) is at least one member selected from the group consisting of 2-(2-ethoxy)ethoxyethyl acrylate and 2-butoxyethyl acrylate.

18. A zwitterionic copolymer according to claim 17 comprising (1) N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine or N-(3-sulphopropyl)-N-acryloxyethyl-N,N-dimethyl ammonium betaine and (2) 2-(2-ethoxy)ethoxyethyl acrylate or 2-butoxyethyl acrylate.

19. A zwitterionic copolymer according to claim 17 comprising a combination of (1) units derived from (1)(a) N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine, (1)(b) N-(3-sulphopropyl)-N-acryloxyethyl-N, N-dimethyl ammonium betaine and (2) a further comonomer copolymerizable with (1)(a) and (1)(b).

20. A zwitterionic copolymer according to claim 17 comprising N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine and 2-(2-ethoxy)ethoxyethyl acrylate or 2-butoxyethyl acrylate.

21. A zwitterionic copolymer according to claim 17 comprising a combination of units derived from (1)(a) N-(3-sulphopropyl)-N-methacryloxyethyl-N,N-dimethyl ammonium betaine , (1)(b) N-(3-sulphopropyl)-N-acryloxyethyl-N, N-dimethyl ammonium betaine and (2) a comonomer selected from the group consisting of 2-(2-ethoxy)ethoxyethyl acrylate, 2-butoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-ethylhexyl acrylate, iso-octyl acrylate and mixtures thereof.