CA1126893A

CA1126893A - Pressure-sensitive low viscosity resin solutions of low stringiness

Info

Publication number: CA1126893A
Application number: CA197,084A
Authority: CA
Inventors: Lawrence W. Mckenna
Original assignee: Monsanto Co
Current assignee: Solutia Inc
Priority date: 1973-04-09
Filing date: 1974-04-08
Publication date: 1982-06-29
Also published as: DE2416991B2; BE813425A; FR2224535A1; NL173538C; DE2416991C3; GB1448937A; NL173538B; DE2416991A1; NL7404665A; IT1006390B; AU6762774A; FR2224535B1

Abstract

Case C-06-12-0362 APPLICATION FOR
LETTERS PATENT
FOR

SOLUTIONS OF PRESSURE-SENSITIVE RESIN
SOLUTIONS WITH IMPROVED VISCOSITY AND FLOW
AND PRESSURE SENSITIVE FILMS UTILIZING SAME.

ABSTRACT OF THE DISCLOSURE
Pressure-sensitive resin solutions containing chelate esters of orthotitanic acid and interpolymers comprising at least one monomer containing a hydroxyl, carboxyl ot enolizable keto group.
The solutions exhibit improved viscosity and now and thus are suitable for application on high speed roll coaters for coating a substrate.

Description

C - 0 6 - 1 ~ - 036Z
SOLUTIONS OF PRESSURE~SENSITIVE RESIN SOLUTIONS WITH
IMPROVED Vl~COSITY AND FLOW
BACKGROUND OF I~E IlWENTION
-1. Fi~ld of the Invention The present invention relates to organic solvent ~olutions containing chelate esters of orthotitanic acid and resins with functional groups capable of reaction with the esters. In another aspect, the invention relates to a proces!Q of manuacture of articles containing films of pressure-sensitive resilL

2, Description of the Prior Art Pressure-sensitive resins are used conventionally in the form of films to provide adhesive bonds between normally non-adhering 3uperstrates and substrates. The films may be prepared by casting them from organic soIvent solutions and evaporating the ~olvent.
Constraints are placed on the molecular weight of the pressure-sensiti~e resin by the viscosity of the solution necessary for ease of coating on commercial coating machines and by the solution concentration required for economical operation. In general, low solution viscosity and high solution concentration are desired in the presslure-sensitive resin solution, and, hence, a re~in of relatively low molecular weight is preferred for film casting.
2(1 Onc e a bond has been made by a pressure-sensitive film placed between a slubstrate and a 3uperstrate, the pres~ure-sensitive film may be subjected to stress generated by the weight of the super-strate or by dimenYional change in the substrate or superstFate caused by thermal expansion, stress relaxation, plasticizer migration or the like.
In general, a high molecular weight and a high cohesive strength is l~Zi~ 3 desired in the pressure-sen3itive resin 50 that it may resist the stresses induced in the adhesive film. The opposing requirements of low molecular weight resin for ease of coating and high molecular weight resin for load holding ability are conventionally reconciled by the use of cros~linkable resin system~ which can be applied at low molecular weight and cured to a high molecular weight.
Metal alkoxides ase taught by Blance in U. S. Patent

3, 53Z, 708 a~ crosslinking agent~ for solution pressure-sensitive adhesives. They offer the potential of cure at room temperature merely by evaporation of ~he solvent. Of particular interest have been tetra-alkyl titanates which are formulated with hydroxy pressure-sensitiYe re~ins in alcohol solutions to yield ~table solutions from which cross-linked pressure-sensitive resins are obtained by evaporation of the alcoholic solvent. However, such titanates particularly the lower alkyl titanates impart high solution vi8c08ity and unde~irable flow to the re~in solutions .
The undesirable flow is manifested by the tendency of the resin solution to form a highly extended "string" or column of nuid when a spatula or like object is pulled rapidly out of the solution.
ZO Solutions e~ibiting such "stringiness" are difficult to apply on modern high-speed coating machinery. Uneven splitting and transfer of the adhesive solution on the rolls causes uneven coating. On rever~e roll coaters, the format.ion of strings at the roll nips produces a ribbed effect in the coating and on gravure rolls, webs of solution produce coating defects.
There is, therefore, a need in the art for pressure-sensitive resin solutions with suitable viscosity and flow for applicatie~n by coating rolls ancl which yield pressure-sensitive resins curable at ~2~ 3 ~;-06-1~!-0362 room temperature Dr at ~lightly elevated temperat~re~ to yield adequate cohesiYe ~treng~h.
SUMMARY OF THE lNVENTlON
The above-mentioned need in the art is fulfilled by the present invention which provide~ pressl~re-sensitive resin solutions with improved viscosity and flow. The rressu]re-sensitive re~in ~olutions comprise an orga~c solvent ~olution of:
~1) an interpolymer having a weight average molecular we~ght in the range of 10, 000 to 50S), 000 and a glass tran~iffon tem-perature in the range of -15 to -75C., the interpolymer comprisin~:
~A) behReen 0. 5 and ?0 weight per cent of at least one monomer containing a hydroxyl, carboxyl or enolizable keto group, (B~ at least one monomer selected from the group l~ consisting of esters of acrylic acid and methacrylic acid con-taining from 6 to 20 carbon atom~, and (iC) optionally, a monomer selected from the group consisting of ~-olefin~ containing from 2 to l0 carbon atoms, vinyl esters of alkanoic acid~ containing from 3 to 10 carbon atoms, ethyl and methyl esters of acrylic and methacrylic acids, acrylonitrile, methacrylon~trile, styrene and vinyl chloride;
and a chelate ester of orthotitanic acid having the formula:

~2~ 3 ¦ O---C / .

(RIO)n Ti~ C--R4 3 4-n ~herein n is an integer of 2 or 3, Rl is a C2 to C10 alkyl, alkenyl, substituted alkyl or substituted alkenyl group, R2 is a Cl to C6 alkyl, alkoxy, alkenyl or alkenoxy group, E?3 is a Cl to C6 alkyl or alkenyl group or a C6, to C10 aryl group and R4 is hydrogen or a Cl to ~6 alkyl or alkenyl group, and R2 and R3 may be colnbined as an ethylene or a trimethylene group.
The invention furtner provides a process for preparing ~`
pressure-sensitive resin solutions with improved viscosity and flow arld a process or coating them as films on substrates to provide articles of ~nanufacture coi~prising films of pressure-sensitlve interpolymer con-taining tne above-described chelate esters of orthotitanic acid.
DESCRIPTION OF THE: INVENTION
The practice of the present invention involves the prepara--, tion of the interpolymer which is then formulated with the chelate ester of orthot;t2nic acid in a ~uitable organic solvent. The solution is cast on a substrate ~he or~anic solvent is dispelled and the resulting lm is cured to a creep-resis~ant per~anently tacky compositlon.
The interpolymer comprises monomers selected from the groups A, B, and C described above. Group A monomers contain hydroxyl, carboxyl or enolizable keto groups. Monomers containing -hydroxyl groups are exemplified by hydroxyalkyl acrylates, methacrylates, fumarates or maleates . ~ :

C;-06-1Z-0362 wherein the al~yl group contains from 2 ItO 4 carbon atoms. Pre-ferred hydroxy monomers include 2-hydroxyethyl acrylate or meth-acrylate, Z-hydroxypropyl acrylate or methacrylate7 3-hydroxy-propyl acrylate or methacrylate, or bisl2-hydroxyethyl) fumarate S ~r maleate. Monomers containing carboxyl grvups are exemplified by acrylic acid, me~hacrylic acid, crotonic acid, iaocrotonic acid, and the like, maleic acid, fumaric acid, citracon~s~ acid, itaconic acid, and the like, and the alkyl monoesters of maleic acid, fumaric acid, citraconic acid and itaconic acid in which the alkyl group contains from 1 to 8 carbon atomE~ ~3uch as me~hyl, ethyl, propyl, butyl and octyl maleates and the like, Preferred acid monomers include acrylic acid and methacrylic acid. Monomer:~ containing enolizable keto groups include N, N-diacetonyiacrylamide and N, N-diacetonylmethacrylamide. The amount of group A monomer in the interpolymer is generally in the l range of 0. 5 to 20 weight per cent of the interpolymer, and is preferably in the range of 1 to 10 per cent for adequate crosslinking potential with-out excessive solution viscosity.
Group B monomers include ~he ester~ of acrylic and methacrylic acid containing from 6 to 20 carbon atoms. Preferred e~ter~
contain branched chain alkyl groups such as isobutyl acrylate, 2-ethyl-hexyl acrylate and 2-ethylhexyl methacrylate. The pressure-sensitive resin need only contain monomers from groups A and B. However, optionally, monomers from Group C may also be present. Group C
includes o~-olefins containing from 2 to 10 carbon atoms, vinyl esters of alkanoic acids containing 3 to 10 carbon atoms such as vinyl acetate and vinyl octoate, ethyl and methyl esters of acrylic and methacrylic 8~3 C-06-12-~362 acids, acrylomtrile, methacrylonitrile, styrene and vinyl chloride.
The ratio of monomers in the intf~rpolymer is selected 30 that the gla~s transition temperature is in the range of -15 to -75S;.
A suitable ratio i~ conventionally calculaLted from the equation:

1 Wl + W2 ~ _~_ Wn Tg ~ Tg2 Tgn where T is the glass transition temperature of the interpolymer expressed as degrees Kelvin, Tgl, Tg2, etc. are the glass tranf~ition temperatures of the homopolymers of the respective comonomers and Wl, W2, etc. are the w~ight fractions of comonorners required for a ~pecific glass tran~ition temperature of the interpolymer. GlasY
transition temperature~ are determined experimentally by conven-tional method~ such as by means of the duPont Differential Thermal Analyzer.
The weight average molecular weight of the interpolymer is in the range of 10, 0Q0 to 500, 000, corre~ponding to a relative viscosity in the range of 1. 3 to 8. 0 measured on a solution of 2 grams of inter-polymer per deciliter of benzene. The preferred molecular weight range is from 20, 000 to 300, 000, providing adequate cohe3ive strength to the interpolymer without excessive solution viscosity.
The interpolymers are conveniently prepared by organic solvent polymerization technique~ involving in ~ome cases delayed addition of monomer when there is a great disparity between reactivity ratios as for example between the reactivity ratio~ of vinyl acetate and acrylate monomers. The time interval for the delayed addition may range from ZS abollt 60 to about 600 minutes and longer. The techniquea in general, '~ ~
:

;i8~93 C-06-1~-0~2 involve the polymerization of the respective monomer mixtures in suitable orga~uc solvent~, the polymerization being initiated by heat activated free radical initia~ors.
The choice of solvents for the interpolyrner used in the prac~ce of this invention is governed by the solubility requirements of the monomers and the resulting interpolymers in that both the monomers and the resulting interpolymers should be soluble in the selected solvent or mixture3 of solvents. A further requirement is that the interpolymer solution should contain less than 3 per cent water by weight, ba~ed on the total weight of the ss7lvent, In order to avoid adverse interference with the metal alkoxide component. More preferably, t~e interpolymer 801u-tion should contain less than 2 per cent water by weight.
Examples of ~uit~ble solvents for the interpolymers include aromatic solvents such as benzene, toluene, xylene, etc. Suitable aliphatic solvents include esters such as ethyl acetate, propyl acetate, i~opropyl acetate, butyl acetate, etc.; ketones such as methyl ethyl ketone, acetone, etc" aliphatic hydrocarbons such as hexane, pentane, etc.
Especially useful are mixtures of the foregoing.
The polymer systems of this invention may also be prepared in mass or non-aqueou~ dispersion type polymerization processes as are well known to those skilled in the art. However, solution poly-merization processes are preferred~
Polymerization initiators suitable for the preparation of the special interpolymers of this invention include organic peroxides, such as tert-butyl hydroperoxide, di-tert-butylperoxide, cumene hydro-peroxide, di-cumyl peroxideJ be~szoyl peroxide and the like. Equally suitable are organic peroxygen compounds 0uch a~ tert-butyl per~ceta~e, acetate, tert-butyl perbenzoate, di-tert-butyl perphthalate; other initiators would include o~ azo-di-isobutyronitrile, ultraviolet light, gamma radiation, etc.
The following Examples 1 to 13 illustrate the preparation formulation and testing of the special interpolymers which are to be used in the practice of this inYention and are not to be construed as limitations thereof. All part~ and percentages are by weight unless otherwi3e specified and the expres~ion~ polymer and interpolymer are 1 0 us e d inter changeably.
PREPARATION OF INTERPOLYMERS
Example 1 Thi~ Example illu~trates the preparation of an inter-polymer comprising 50. 5 part~ 2-ethylhexyl acrylate, 45 part3 methyl acrylate and 4. 5 part~ 2-hydroxyethyl acrylate.
The polymer is prepared under reflux cunditions in a kettle equipped with a stirrer, condenser, holding tanks and pumps.
AMOUNT OF INGREDIE:NTS, Parts by Weight Initial Subsequent charge3 Charge 1 2 3 2-ethylhe~yl acrylate 14. 1 6. 97 Methyl acrylate 12. 6 6. 20 2-hydroxyethyl acrylate 1. 26 0. 62 Ethyl acetat,e 19. 6912. 3 9, 0 ~Iexane S. 14 2.749.26 oC, O~ ' -azo-diisobutyronitrile 0. 07 6 0. 038 Dodecyl mercaptan 0. 0027 0. 0013 C-06-lZ -0362 Charges 1 and 2 are made at uniform ratc~ ov~r thc 14 hour period after the initial charge reaches reflux~ After 6i! hours of reflux, the batch is cooled and charge 3 is added. The solids content is 41. 0 per cent. The Brook~ield viscosity is 3, 000 cps. The relative 5 viscosity, determined with a solution of 2 grams of resin in 100 ml. ben~ene is 4.1.
- Examples 2 to 11 The gene~al procedure of Example 1 is followed except that different monomers and monomer ratios are used in order to illu3trate a variety of interpolymer~ used in the practice of this invention.

COMPOSITIONS OF INTERPOLYMERS
- ~EPARED IN EXAMPLES 1 to 11 .. . _ _ . .. .
Ex:. Monomeric Components Weight Ratio - 15 1 EHA/MA/HEA 50. 5145/4. 5 $
i~ EHA/YAc/AA 59/39. 5/1. 5 3 EHA/VAc/AA - 52/47/1. 0

4 EHA/~A/AA Sl/33/6. 2 EHA/I~A/HEA 71/Z4/5 6 iBA/MA/HEA 71/24/5 7 VAc/EHA/HPA 45/50/5 8 VActEHA/HEMA 35/60/5 9 VAc/EHA/HEF 40/55/5 11 VCl/EHA/HEMA 30/65/5 ~J.~ 3 C-0~-12-03~
L EGE ND
EHA 2-ethylhexyl acrylate ~L~ m ethyl acrylate HEA 2-hydroxye~hyl acrylate YAc vinyl acetate ~ acrylic acid H PA 3-hydroxypropyl acrylate HE~ 2-hydroxyethyl m ethac~ylate H EF bis-(2-hydroxyethyl3furnarate A N acrylonitrile VCl vinyl chloride iBA isobutyl acrylate . , i8~3 o g o g g o o o o o ~ t, o o o o ,~, o CO U7 ~
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~1 0 o FORMULATION OF RE~SIN SOLUTIONS WITH
CHELATE_TE~RS OF ORTHOTITANIC ACID
After the preparation of the interpolymer, the interpoLymer solution is formulated with at least one chelate ester of orthotitanic acid of the general formula:

(Rl~n Ti O=C\

R3 4-n `:
- wherein n is an integer of 2 or 3, Rl is a C2 to C10 alkyl, alkenyl, sul~-stituted alkyl or substituted alkenyl group, Rz is a Cl to C6 alkyl, alko~y, alkenyl or alkeno~y group, R3 is a Cl to C6 alkyl or alkenyl group or a C6 to C1 0 aryl group and R4 i9 hydrogen or a Cl to C6 alkyl or a~kenyl group, and R2 and R3 may be combined as an ethylene or a trirnethylene group.
The chelate esters are prepared by conventional Inethods such as the addition of the appropriate chelating agent to an alkyl or alkenyl titanate wherein the alkyl or alkenyl group contains 2 to 10 carbon atom3.
Among the chelating agents which can be used are, for example, acetylacetone, propionylacetone, benzoylacetone, 1, 3-cyclopentandione, 1, 3-cycloheY~ndione, alkyl acetoacetates, such as ethyl acetoacetate, and the alkyl and alkenyl substituted derivatives of these diketone~ and acetoacetates. Thus, where acetylacetone is used as the chelating agent the Rz and R3 groups are methyl and the R4 group iY hydrogen. The chelating agents may be reacted with the lower alkyl or alkenyl titanate in a molar ratio ranging from 1:1 to 2:1. The preferred ratio is about _13-~" .

~R.~Zfi~33 ~:1 so that, for example, when acetylacetone is used, a di-alkoxy titanium diacetylacetonate is obtained. The alkanol generated by the reaction may be distilled~ Alternatively, it may be allowed to remain so -that the product of reaction is essentially a solu-tion of chelate ester in alkanol. The pre-ferred chelate esters are dialkoxy titanium diacetylacetonates, dialkoxy titanium di(l,3-cyclopentandiona-tes) and dialkoxy titanium di(l,3-cyclohexandionates).
The ~mount of chelate ester used in a given resin solution will depend on the type of reactive group in the interpolymer, the molecular weight of the interpolymer, the concentration of interpolymer in the solution, the composition of the solvent and the degree of cross-linking desired in the pressure-sensitive resin after it has been cast from solution.
As little as 0.01 parts by weight of the chelate ester per 100 parts by weight of interpolymer can give a significant effect on the cohesive strength of the polymer as measured ~y -the creep resistance. As much as 4.0 parts by weight of the chelate ester per 100 parts by weight of interpolymer can be used especially with lower molecular weight interpolymers and/or : lower concentrations of functional groups. However, the pre-erred range is between 0.1 and 1.0 parts by weight per 100 parts of interpolymer to achieve an appreciable degree of crosslinking without an undesirable increase in the viscosity of the resin solution.
Unlike the lower alkyl titanates, the chelate esters of orthotitanic acid may be added to the interpolymer solutions in the absence of highly polar solvents such as the lower alcohols and much higher concentrations of resin and chelate ester can be achieved in the solution without excessive viscosity, stringiness or gelling. However, it may ~ -14-~3~ i8~93 ~-06-12-0362 still be advantageous to include a lower alcohol in the ~esin solution to increase the solubility parameter of the solvent, particularly ~,vhen the sub~trate to be coated can be swollen by the less polar solvents which are conventionally uaed in the aolution interpolymerization proces~.
Apart from the optional use of a lower aloohol, conventional solvents and solvent blends are selected for use in the pressure-sensitive resin solutions of thi3 invention on the basis of the solubility requirements of the resin and the nature of the substrate which is to be coated, The solids content of the resin solutions can be varied between 10 per cent and 60 per cent for application to the substrate. The preferred concentration iB between 20 and 50 per cent.
EVALUATION OF PRESSURE-SENSITIVE
RESIN SOLUTIONS
In the evaluation of pressure-sensitive resin ~olutions containing esters of orthotitanic acid, the solutions are formulated to 32 weight per cent solids. The esters of orthotitanic acid are added in ethanol solution gradually with stirring to the pre~sure-sensitive resin solution, the amount of ethanol being 25 weight per cent of the total solvent in the final solution.
The solution~ are subjected to determination of viscosity and "stringiness index". Viscosity iB determined at 20C, by the conventional method using a Brookfield Model LVF Viscometer and the appropriate spindle and speed. Vi9cosity stability is determined from viscosity measurennents over a 7 day period.
The stringiness index (S. I. ) i~ determined by immersing a platinum surface tension ring of 3. 6 cm diameter, -one inch below the ~3~ 3 C -Ob- lZ -036 2 surface of the pres~ure-sen~itive reain ~olution contairled in a 7.62 cm diameter jar. The ring i~ mounted in the jaw of an ln~tron l'est Machiné
and is withdrawn from the solution by allawing the cros~he~d upon which the jar rests to de~cend at a rate of 12.7 cm/mln. The tensile S fs~rce exerted on the ring i~ recorded by means of the A cell on the chart oct at lO ~ram~ full RCalC and moVi~ t 12.7 crn/min. I h~
stringi~e~s index is mea~ured from the peak of rr1aximum extensional force to the failure point of the elongating curtain of ss>lution. Five mea~uremel~t~ are made in rapid succession. The arithmetic average 0 e~cpre~o~d in cms. i8 the ~tringine~s index. In general, a stringiness index of le~ than o.76 cm indicatee that a resin solution haa good 10w properties and that the solution will not form string~ on conventional high-~peed roll coaters at normal speeds of operation. The tendency of a pressure-sensitive reAin solution to develop ~tringiness is determined by measurement of the stringines~ index over a 7 day period.
The dlata for viscosi2y and stringine~ index of Ihe inter-polymer ~olutions of Examples 1-4 formulated with various esters alf orthotitanic acid are preiented in Tables 3 and 4. The ~olids content of the solutions i3 32 per cent. Ethanol forms 25 per cent of the solvent.
'O In the Tables, TBT ~ignifies tetrabutyl titanate and TAA signifies di-isopropoxy titanium diacetylacetonate which i~ formed by rea~ 2ion of 2 rnole~ of acetylacetone with 1 mole of tetra-isopropyl titanate.

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:~ . 3 t ' The data show the higher viscosities, the tendency to gel and the hi~her stringiness indices of pressure-sensitive resin solutions containing -tetrabutyl titanate in comparison with solutions containing diisopropoxy titanium diacetyl-acetonate especially at higher concentrations of the titanateester.
Data for stringiness index of interpolymer solutions of Examples 3 and 6 through 11 formulated with various chelate esters of orthotitanic acid are presented in Table 5. The solids content of the solutions is 30 percent. Ethanol forms 25 percent of the solvent. The concentration of chelate ester of titanium is 0.4 parts per 100 parts by weight of resin.
~- EVALUATION OF PRESSURE-SENSITIVE RESINS
The pressure-sensitive resin solutions listed in Table 3 are cast on silicone release paper, and the cast films are dried at room temperature, then at 90C. for 2 minutes to dispel the organic solvent. The (0.002 cm thickness) films are cooled to room temperature and applied to polyvinyl chloride film (Ultron* Polyvinyl Chloride UL-58 Film, 0.0076 cm thick, supplied by Monsanto Company). The laminate is cut into 2.54 cm strips. The strips are conditioned at 22C and 50~
relative humidity for 24 hours. The release paper is removed and the strips are applied to steel panels (ASTM 1000-651 with a Pressure-Sensitive Tape Council roller. Peel strength is determined on an Instron Test Machine by peeling the strip at a 180 angle and at a rate of 15.1 cm per minute from the steel panel. "Green" strength is gauged by comparing the peel strength of the bond 20 minutes after formation and 24 hours after formation. Data are presented in Table 6.

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The data show that titanate ~ter causes a decrease ;n peel strength in direct relation to f,he concentration of titanate ester, Ho~ever, the effects of tetrabutyl titanate and diisopropoxy titanium diacetylaceton~te are essentially equivalent and in no case is the peel st}ength reduced below a useful value, The co~lesive strength nf the pressure-sensitive adhesive is gauged from the creep resistance of a 1.61 cm;~ 0.002cm thick bond formed by the film of adhesive between a strip of Mylar*
Polyester filrn ~a product of E. I, duPont de Nemours and Company) and a polished stainless steel bar, The Mylar*strip is loaded with a one-pound weight, The bond is held in a vertical plane at 22C and 50%
relative humidity and the tirne in hours for failure after application of the load is determined, The data are presented in Table 7, CRE~EP RF:SISTANCE OF PRESSURE-SENSITIVE RESINS ~hours to failure) Titanate RESIN
Concentration, g. ~ ~x. ~;x, ~;x.
per 100 g, re~in Type 1 2 3 4 0 none 0, 2 0, 3 0, 7 0, 5 0, 2 TBT 3 3 4, 6 -_ 0. 4 TBT 10 55 40 --0, 6 TBT -- 52 -_ __ * Trademark ~ %~ ?t3 Note that at loYv coneentrations of titanate e~ter, the initial creep resistance i~ roughly the same for resins containing tetrabutyl titanate and those containing diisopropoxy titanium diacetylacetonate;but at higher concentrations, the creep resistance improves to a higher level for TAA formuiations than iEor the TBT
systems. An exception is the Exampl~ 2 system for which TBT may be a more efficient crosslinker.
While the present invention has been described with parti-cular reference to certain spec;fic embodiments thereof, it will be understood that certain changes, substitutions and modifications may be made therein without departing from the scope thereof. This invention also contemplates the use of filler3, extenders, s~abili~;ers, antioxi-dants, plasticizers, tackifiers, flow control agents, adhesion promoters, dyes, etc. in the pressure-sensitive resin solutions and the pressure-sensitive resins of this invention.
The compositions of the present invention may be used as the adhesive component in pressure-sensitive tapes, films and foams.
They adhere well to resin 3urfaces such as plasticized polylvinyl chloride3 Mylar, cellulose acetate, nylon, polyethylene and polypropylene, as well as to paper, metal and painted surfaces. They are e3pecially useful as the adhesive component of decorative vinyl sheets and decals, conferring - excellent shrink resistance to vinyl film. Their excellent tack retention, creep resistance and resistance to plasticizer migration make them u3eful as adhesives for vinyl foam and tile~.Their outstanding tack, wetting and holding power may be used to advantage in transfer adhesive applications.

8~3 C - 0~ - 1 2 - 03 62 Articles of manufacture ~uch as tapes, decals, decorative vinyl 8heet8 and transfer films containing the pressure-sensitive re~in composition of the present invention are prepared by coating the resin on the appropriate substrate by conventional coating methods. Such artieles conventionally include a release paper for teml?orary protection of the adhesive film until lhe adhesive l~-n-l is rna~le. The thi~:kn~s~
of the adhesive film is generally in the range of 0.00051 to 0.0127 cm Application of the film to the sub~trate is conventionally carried out on roll coater~ ~uch as reverse roll and gravure roll coater~.
The resin ~olution visco~ity i~ adjusted to between 25 and 5, 000 centipoiRe~ with higher viscositieu within the range preferred for reverse roll coating and lower visco3ities within the range preferred for gravure coating. The coatings are applied to the substrate moving through the rolls a~ a rate of between 5.1 cm~sec. and ~o~.n n~m/~?C.
Example l 2 This ~:xample i8 ~let forlh lo colllpdre Ille perforll~al~ce of a resin aolution formulated with letrabutyl titanale with a resin solution formulated with diisopropoxy titanium diacetylacetonate in reverse roll application to a polylvinyl chloride) substrate at a rate of 25.4 cDnJ~ec.
Polymer solutions made according to Example l are diluted to 30 per cent solids and formulated with 0. 5 parts tetrabutyl titanate or diisopropoxy titanium diacetylacetonate per lOO parts of resin. The levels of titanate con~pound are ~elected to give the desired cohesive ~trength in the dried films. The TBT solution had a Stringiness Index of about 1.14 cms. and g:ives poor coatings of rough surface texture and uneven Ihi~:hn~ . A l~r~ ul~ r ~f "~IrinK~" ~re ~ erve(l I)etw( (~n Ine _ 2 4 _ ..

. . . . . . . .

application roll and Lhe sub~tra~te during tile coating operation. Th~ ac coatinga are judged unsuitable Ior commercial u~e. The TAA solution has a Stringpness Lndex of abous Q.50 cm. and gives smooth coatings of uniforln thickneas. These filma are judged satisfactory for commercial u~e.

.~ .

~ -25 -

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An organic solvent solution for a pressure sensitive, creep-resistant permanently tacky resin comprising:
(A) a chelate ester of orthotitanic ester having the formula:

wherein n is an integer of 2 or 3, R1 is a C2 to C10 alkyl, alkenyl, substituted alkyl or substituted alkenyl group, R2 is a C1 to C6 alkyl, alkoxy, alkenyl or alkenoxy group, R3 is a C1 to C6 alkyl or alkenyl group or a C6 to C10 aryl group and R4 is hydrogen or a C1 to C6 alkyl or alkenyl group, and R2 and R3 may be combined as an ethylene or a trimethylene group; and (B) an interpolymer of monomers consisting essentially of:
(1) between 0.5 and 20 weight percent of at least one monomer containing a hydroxyl, carboxyl or enolizable keto group, and (2) at least one monomer selected from the group con-sisting of esters of acrylic acid and meth-acrylic acid containing from 6 to 20 carbon atoms, wherein the interpolymer has a weight average molecular weight in the range of 10,000 to 500,000 and a glass transition temp-erature in the range of -15 to -75°C;
wherein there are between 0.01 and 4 parts by weight of the chelate ester per 100 parts of interpolymer, the stringiness index of the solution being less than 0.76 cm.

2. The organic solvent solution of claim 1 wherein said one monomer containing a hydroxyl, carboxyl or enolizable keto group is selected from the group consisting of N,N-diacetonylacrylamide and N,N-diacetonylmethacrylamide.

3. The organic solvent solution of claim 1 wherein the stringiness index of the solution is less than 0.76 cm.
and above about .50 cm.

4. An organic solvent solution according to claim 1 characterized wherein said chelate ester is the reaction product of a tetraalkyl or tetraalkenyl titanate wherein the alkyl or alkenyl group contains 2 to 10 carbon atoms, and an enolizable keto compound of acetylacetone, benzoyl-acetone, 1,3-cyclopentandione, 1,3-cyclohexandione, alkyl acetoacetates, and their C1 to C6 alkyl or alkenyl sub-stituted derivatives, the mole ratio of tetraalkyl or tetraalkenyl titanate to enolizable keto compound being in the range of 1:1 to 1:2.

5. An organic solvent solution according to claim 4 wherein said enolizable keto compound is acetylacetone.

6. An organic solvent solution according to claim 1 characterized wherein said interpolymer is formed from a hydroxy monomer of 2-hydroxyethyl acrylate and methacrylate, 2-hydroxy-propyl acrylate and methacrylate, 3-hydroxypropyl acrylate and methacrylate, bis(2-hydroxyethyl) fumarate, or bis(2-hydroxy-ethyl) maleate.

7. An organic solvent solution according to claim 6, characterized wherein said interpolymer is formed from 2-ethylhexyl acrylate or 2-hydroxyethyl acrylate.

8. An organic solvent solution according to claim 1 characterized wherein said interpolymer is formed from a carboxy monomer of acrylic acid, methacrylic acid, crotonic acid, isocrotonic acia, maleic acid, fumaric acid, citraconic acid, itaconic acid or the alkyl mono esters of maleic acid, fumaric acid, citraconic acid, or itaconic acid in which the alkyl group contains from 1 to 8 carbon atoms.

9 An organic solvent solution according to claim 1, characterized wherein said interpolymer is formed from 2-ethylhexyl acrylate and acrylic or methacrylic acid or N,N-diacetonylacrylamide or N,N-diacetonylmethacrylamide

10. An organic solvent solution according to claim 3, characterized wherein said chelate ester is the reaction product of a tetraalkyl or tetraalkenyl titanate wherein the alkyl or alkenyl group contains 2 to 10 carbon atoms, and an enolizable keto compound of acetylacetone, benzoylacetone, 1,3-cyclopentandione, 1,3-cyclohexandione, alkyl acetoacetates, and their C1 to C6 alkyl or alkenyl substituted derivatives, the mole ratio of tetraalkyl or tetraalkenyl titanate to enolizable keto compound being in the range of 1:1 to 1:2.

11. An organic solvent solution according to claim 10 wherein said enolizable keto compound is acetylacetone.

12. A pressure sensitive, creep-resistant permanently tacky resin containing:
(A) a chelate ester of orthotitanic ester having the formula:

wherein n is an integer of 2 or 3, R1 is a C2 to C10 alkyl, alkenyl, substituted alkyl or substituted alkenyl group, R2 is a C1 to C6 alkyl, alkoxy, alkenyl or alkenoxy group, R3 is a C1 to C6 alkyl or alkenyl group or a C6 to C10 aryl group ana R4 is hydrogen or a C1 to C6 alkyl or alkenyl group, and R2 and R3 may be combined as an ethylene or a trimethylene group; and (B) an interpolymer of monomers consisting essentially of (1) between 0.5 and 20 weight percent of at least one monomer containing a hydroxyl, carboxyl or enolizable keto group, and (2) at least one monomer selected from the group consisting of esters of acrylic acid and methacrylic acid containing from 6 to 20 carbon atoms, wherein the interpolymer has a weight average molecular weight in the range of 10,000 to 500,000 and a glass transition temperature the interpolymer has a weight average molecular weight between 0.01 and 4 parts by weight of the chelate ester per 100 parts of interpolymer.

13. The resin of claim 12 wherein said interpolymer is formed from N,N-diacetonylacrylamide or N,N-diacetonylmeth-acrylamide.

14. An article of manufacture which comprises a substrate coated on at least one side with the pressure-sensitive resin of claim 13.

15. An article of manufacture according to claim 15, characterized wherein said substrate is a film of plasticized polyvinyl chloride, polyethylene terephthalate, cellulose acetate, nylon, polyethylene, polypropylene, paper or silicone treated paper.

16. A pressure-sensitive, creep-resistant permanently tacky resin according to claim 12 in which the chelate ester of orthotitanic ester has the given formula wherein R1 is isopropyl, R2 and R3 are each methyl groups, R4 is a hydrogen atom and n is two.