CA1060600A

CA1060600A - Polyurethane foam-backed pressure-sensitive adhesive tape

Info

Publication number: CA1060600A
Application number: CA267,825A
Authority: CA
Inventors: Donald L. Esmay
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1976-01-19
Filing date: 1976-12-14
Publication date: 1979-08-14
Also published as: AU2140777A; ZA77272B; DE2702305C2; GB1531641A; JPS557480B2; JPS5289140A; BR7700343A; DE2702305A1; FR2338318B1; US3993833A; FR2338318A1; IT1082679B

Abstract

ABSTRACT

Foam-backed pressure-sensitive adhesive tape having an open-cell polyurethane roam backing containing a foam-stabilizing fluoroaliphatic substance such as a fluoroaliphatic oligomer which affords repellency to oil and water. Moieties of the fluoroaliphatic substance similar to moieties of the polyurethane afford solubility in the polyurethane-forming mixture which is balanced against the insolubilizing effect of the carbon-bonded fluorine to concentrate the fluoroaliphatic substance at the cell membrane surfaces of the foam.

Description

~ 912,594 1~60600 POLYURETHANE FOAM-BACKED
PRESSURE-SENSITIVE ADHESIVE TAPE

Foam-backed pressure-sensitive adhesive tapes are used in a wide variety of applicàtions. Some such tapes have a pressure-sensitlve adhesive layer on each surface and may be used for mounting objects such as pictures on walls or plastic body side molding on automobiles. Other such tapes have only one adhesive layer. For example, a single-adhesive layer may function to position the foam backing as a cushioning gasket for an automobile window which is sealed by ~astenlng a metal strip to the window frame. Most such applications require the foam backing to have both good compressibility and good resilience. For good compres-sibility, the foam should have an open-cell structure.
The backing o~ one such pressure-sensitlve ad-hesive tape is a polyurethane foam, as disclosed in Canadian patent No. 747,341, but polyurethane foams tend to swell excessively in contact with oils such as gasoline, ~
especially when of open-cell structure. Open-cell poly- ~ -urethane fo~ms tend to wick both gasoline and water and, in automotive use, may carry such liquids into the interior of the vehicle. Hence, tapes o~ the Canadian patent have been put to little or no exterior automotive use.
~ he present invention fills the need for a foam-backed pressure-sensitive a~hesive tape which is inexpen-sive, has good compressibility and resilience, is repellent -to gasoline and water, and will remain ~irmly adhered to -~

substrates to which it is applied. These accomplishments are attalned by employing as the ~oam backlng a compressible, resilient, open-cell poIyurethane foam-incorporating a .

~k ' ' ... . .

foam-stabilizing fluoroaliphatIc substance containing covalently bonded ~a) a plurality of fluoroaliphatic radicals and (b) at least one solubllizlng moiety, viz., a moiety similar in s~ructure to a moiety of the polyurethane in order to provide a degree of solubility in the foamable polyurethane-~orming mixture. For the same reason, the number average molecular ~eight of any polymeric component of the fluoroaliphatic substance should be about 25,000 or less.
According to the presen~ invention there is provided pressure-sensitive adhesive tape having an open-cell polyurethane foam backing and incorporating in the polyurethane a foam-stabilizing fluoroaliphatic sub-stance containing covalently bonded (a) a plurality of fluoroaliphatic radicals having at least three fully fluorina~ed carbon atoms, one of which is terminal, and (b) at least one moiety similar in structure to a moiety of the polyurethane, said solubilizing moieties providing 5 to 40 weight percent and carbon-bonded fluorine providing 10 to 45 weight percent of the fluoroaliphatic substance, the fluoroaliphatic substance being free of functional groups containing active hydrogen atoms and being present in an amount affording repellency to gasoline. .. . -The present in~ention also relates to pressure-sensitive adhesive tape having an open-cell polyurethane foam backing with dense skins, a pressure-sensitive adhesive layer united to one or both skins, and in-corporating in the polyurethane one or more foam.stabilizing fluoroaliphatic oligomers of the general formula:

[(Rf)mQ(RQ'A)n]z :~ :

where Rf is a fluaroaliphatic radical having at least three fully fluorinated carbon atoms, one of which is terminal, R is a divalent organic radical, Q is a linkage throughwwhich R and R radicals are covalently bonded together, A is a monovalent terminal organic radical or a valence bond interconnecting a Q-bonded R radical to another Q, Q' ls a linkage through wIth A and R are co~alently bonded together, m is an integer of at :
least 2, _ and z are integer~ not exceeding:30, and the products mz and nz iB

106~600 do not exceed 30, ~ and Q together comprise solubilizing moieties providing 5 to 40 weight percent of total oligomer, carbon-bonded fluorine provides 10 to 45 weight percent of total oligomer, and the fluoroaliphatic oligomer is free of functional groups containing active hydrogen atoms and is present in an amount affording repellency to gasoline.
The fluoroaliphatic substance should have limited solubility in the foamable mixture, and by virtue of this, tend to be concentrated at the cell membrane surfaces. Because of such concentration, as little as 0.02 part of the fluoroaliphatic substance per 100 parts by weight of foam can provide significant repellency to gasoline and water. The desired degree of solubility may be realized by balancing in the fluoro-aliphatic substance the antisoluhilizing effect of increased fluorine -~
content and .increased ~olecular weigh~ against the~solubilizing effect of the moieties which are similar in structure to moieties of the polyurethane. For example, for use with a polyether polyurethane, the solubilizing moieties o~ the fluoroaliphatic substance may be repeating oxyalkylene units having on the average 2.5 to 4 carbon atoms. For use with a polyester polyurethane, the solubilizing moieties may be polyester groups. For use with any of the polyether, polyester or polyether-zO polyester polyurethanes, the solubilizing moieties may comprise urethane linkages, -OC~O)NH-. Such solubilizing moieties may provi~e 5 to 40, preferably 10 to 20, weight percent of the fluoroaliphatic substance.

- 2a -.
- L~

106(;~600 The fluoroaliphatic substance should be free of functional groups containing active hydrogen atoms. The term "active hydrogen atom" means a hydrogen atom (other than an amido hydrogen atom) which is reactive with a Grignard reagent, as described in Journal Am. Chem. Soc., 49, 3181 (1927). The desired repellency to gasoline and water can be attained with the fluoroaliphatic substance comprising 10-45 weight percent carbon-bonded fluorine.
At fluorine contents approaching 45 weight percent, it is preferred that the solubilizing moieties provide about 20 weight percent of the fluoroaliphatic substance. For optimum all-around properties including good repellency to gasoline and water, the fluorine content should provide about 20-40 weight percent and solubilizing moieties should provide about 10-25 weight percent of the fluoro-aliphatic substance.
Although the fluoroaliphatic substance acts as a foam stabilizer in the foaming of the polyurethane, 0.02 weight percent of the fluoroaliphatic substance may be insufficient to yield the desired open-cell structure unless some other foam stabilizer is also present. For example, silicone surfactants which are known to enhance the formation of open-cell polyurethane foam may be included in the foaming composition. When the foaming polyurethane composition comprises about 0.1 to 10 weight percent of the -fluoroaliphatic substance, the desired open-cell structure can generally be attained without any other foam stabilizer.
More than about two weight percent would tend to be un-economical.
By "open-cell" is meant a foam pro~iding a water take-up of at least 60 percent of the internal free volume (ASTM D 1056-73). For optimum compressibility and resilience, the interior of the foam should have about 8 to 40 cells per linear centimeter. By "compressible" a~d "resilient" is meant a foam which has compressibility under 2 N/cm2 of at least 10 percent and a recovery with-in 30 minutes of at least 90 percent from 50 percent de-flection at 23C as measured by ASTM D 1564-71.
Preferred as the fluoroaliphatic substance are fluoroaliphatic oligomers of the general formula ~(Rf)mQ(RQ'A)n]z where Rf is a fluoroaliphatic radical, R is a divalent organic radical, Q is a linkage through which Rf and R radicals are covalently bonded together, A is a monovalent terminal organic radical or a valence bond interconnecting a Q-bonded R
radical to another Q, Q' is a linkage through which A and R are covalently bonded together, m is an integer of at least 2, and can be as high as 25, n and z are each integers not exceedin~ 30, and neither product of mz nor nz exceeds 30.
The fluoroaliphatic radicals, Rf, are saturated, and generally monovalent aliphatic moieties. They can be straight chain, branched chain, and, if sufYiciently large, cyclic, or combinations thereof, such as alkyl-cycloaliphatic radicals. The fluoroaliphatic skeletal chain can include catenary oxygen and/or trivalent nitrogen hetero atoms bonded only to carbon atoms, such hetero atoms providing stable linkages between fluorocarbon groups and not interfering with the inert character o~ the Rf radical. While R~ can have a large number of carbon atoms, R~ radicals having not more than 20 carbon atoms will be adequate and preferred since larger radicals usually represent a less efficient utilization of fluorine than is possible with smaller Rf radicals. Rf should have at least three fully fluorinated carbon atoms, one of which is terminal, and should contain 40 to 78 weight percent carbon-bonded fluorine. Preferably R~ has 6 to about 12 ~
carbon atoms and contains 50 to 77 weight percent carbon- ~-bonded fluorine. The terminal portion of the Rf radical has preferably at least three fully fluorinated carbon atoms, e.g., CF3CF2CF2-, and the preferred Rf radical is substantially completely fluorinated, as in the case where Rf is perfluoroalkyl, CnF2n+l.
These attributes o~ Rf radicals of the ~luoro- ~
20 aliphatic oligomer also apply to fluorinated radicals o~ --useful foam-stabilizing fluoroaliphatic substances which are not oligomers. - -Either or both of R and Q of useful fluoro-aliphatic oligomers may comprise solubilizing moieties.
~or example, R may comprise repeating oxyalkylene units and/or polyester groups and Q may comprise urethane linkages, as mentioned above. Likewise, such solubilizing moieties should provide 5 to 40 weight percent of the fluoroaliphatic oligomer.
The fluoroaliphatic oligomers used in the in-vention are generally non~ionic, normally liquid or low melting solids, being relatively low molecular weight linear polymers, branched polymers, or lightly crosslinked polymers, containing from 3 or 4 up to about 25 or 30 monomer units. Thus they are oligomeric, as contrasted to "high polymers" having molecular weight o~ 100,000 or higher. Preparation of such fluoroaliphatic oligomers is disclosed in U. S. patent No. 3,787,351.
The pressure-sensitive adhesive tape of the invention is conveniently manufactured as disclosed in the aforementioned Canadian patent No. 747,341. In brief, the foam-producing mixture is coated onto a pressure-sensitive adhesive transfer tape, and either a similar transfer tape or a web having a low-adhesion surface is lightly pressed against the foam-producing coating.
Preferably the pressure-sensitive adhesive layer of such t,ransfer tape has been overcoated with a barrier or tie coating which serves to improve adhesion to the foam and to act as a barrier against substances tending to migrate from the foam into the adhesive. Foaming against the low~adhesion web and the pressure-sensitive adhesive coatings (or barrier coatings) produces dense skins.
More specifically, the viscous foam-producing batter mixture that is applied to a transfer tape may consist essentially of a mixture of isocyanate-terminated prepolymer, chain-extending agent, fluoroaliphatic sub-stance, foam-generating agent and catalyst, together with flame retardant agent and other additives, if desired.
The mixture is promptly coated over the adhesive layer or b,arrier coating of a transfer tape. ~o obtain a double-1~60600 coated foam, a second transfer tape is added. Free foaming of the mixture occurs, together with ~urther polymerization of the polyurethane, as the webs are drawn through a heating zone to provide a relatively thick and low-density foam layer. Upon leaving the heating zone, this warm and incompletely polymerized layer may, if desired, be gradually compressed to a relatively high bulk density foam layer having the desired ultimate thickness. Sufficient time is per-10 mitted thereafter for the polymerization reaction to ~-be essentially completed so as to result in a stable cured foam layer integrally united to the adhesive coating or coatings.
The presently preferred pressure-sensitive -adhesives are viscoelastic polyacrylates which in-herently are aggressively tacky and highly cohesive.
The polyacrylate is a copolymer of an alkyl acrylate having an average o~ 6 to 12 carbon atoms in the alkyl group and a small proportion (about 3 to 12%) of a co-polymerizable monomer having a strongly polar func-tional group (such as acrylic acid, methacrylic acid, itaconic acid, acrylamide, methacrylamide, acrylo-nitrile, methacrylonitrile or mixtures thereof). A
90:10 copolymer o~ isooctyl acrylate and acrylic acid is exemplary. These copolymers are described in U. S.
patent Nos. Re.24,906 and 3,008,850. Internal cohesive strength and shear strength can be increased by cross-linking curing as described in U. S. patent Nos.

2,925,174 and 2,973,286.
The gasoline repellency of various poly-1~60600 urethane foams containing fluoroaliphatic substances was evaluated as ~ollows. A series of open-cell ~oams were prepared from mixtures of by weight (a) 100 parts of an isocyanate prepolymer with an isocyanate number of about 450 (prepared from castor oil, phthalic anhydride and ~0:20 tolylene diisocyanate as described in U. S. patent No. 2,921,916), (b) fluoroaliphatic substance in solution or solution-suspension as listed at the botkom of Table I, (c) 5.9 parts of glycerine crosslinking agent, (d) 4.24 parts of a poly(oxy-propylene) diol of about 400 molecular weight as a chain-extending agent, (e~ 0.4 part of diethyl-2-hydroxyethyl amine catalyst, (f) 0.2 part of stannous octoate catalyst and (g) 7.0 parts of CC13F blowing agent. After vigorous stirring for about 30 seconds, each mixture was applied between two polyethylene-coated paper webs. This was placed in an oven at about 80C for about 10 minutes, removed, allowed to cool to room temperature, and the paper webs were re-moved, providing an open-cell foam about 6 mm in thick-ness. Where "parts" are indicated in connection with Table I and thereafter, "parts by weight" is intended;
where "molecular weight" is indicated for a polymer, "number a~erage molecular weight" is intended.

Gasoline Repellency Test Gasoline repellency was determined by positioning a freshly cut foam surface in a horizontal position, placing a drop of automotive gasoline on the cut surface, and measuring the time until the drop of gasoline had reached the level of the cut surface.

1Ç~60600 Each time reported in Table I is an average of three determinations at three different locations separated by at least 2.5 cm.

Table I
Weight % of Oligomer FalrutOrO
Fluoro- provided by aliphatic Density Time Foam aliphatic F Moieties in Foam (Kg/m3) (Minutes) No. Substance 1 None None None None 300 ~0.02 2 A 61 None 0.2 270 ~0.02

3 B 34 None 0.4 270 ~0.02

4 C 26 None 0.12 220 <0.1 D 52 20 0.5 220 0.2 6 E 44 10 0.4 220 0.5 ` -7 F 44 17 0.5 270 0.5 8 G 30 18 0.4 300 3 9 H 21 19 0.5 270 3 I 41 10 0.4 240 3 11 J 37 19 0.5 240 3.5 12* Jl 37 19 0.5 240 3.5 A was a fluoroaliphatic oligomer of l,l-dihydroperfluoro-octyl methacrylate of U. S. patent No. 2,803,615 in a 2% solution in xylene hexafluoride.
B was a copolymeric fluoroaliphatic oligomer of 65 parts ~ -N-methyl per~luorooctanesul~onamidoethyl methacrylate and 35 parts octadecyl methacrylate of U. S. patent No.
2,803,615 in a 40% solution in l,l,l-trichloroethane. -C was a copolymeric ~luoraaliphatic oligomer from the same starting materials as B except a 1:1 ratio of reactants was used and it was employed in a 25% solution in n-heptane. -*Amount of poly(oxyproplylene)diol reduced to 3.44 parts to ccmpensate for --added hydroxyl content provided by the poly(oxypropylene glycol)triol.
.
~ - 9 - ~

~060600 D was the reacti.on product of 2 mols of N-ethyl perfluoro-octanesulfonamidoethanol and one mol of 80:20 tolylene diisocyanate of U. S. patent No. 3,398,182 in a 33%
soluti.on-suspension in methylisobutyl ketone.
E was a 1:1 mixture of B and D in a 20% solution in CC12FCC1~2:2-ethoxyethanol:tetrahydrofuran :: 7:3:1.
F was a fluoroaliphatic carbodiimide oligomer of N-methyl perfluorooctanesulfonamidobutanol and tolylene diiso-cyanate of U. S. patent No. 3,896,251 in a 44%
solution in methyl isobutylketone.
G was a mixture of 90 parts o~ (a) a copolymeric fluoro-aliphatic oligomer of 35 parts N-methyl per~luoro-octanesulfonamidobutyl methacrylate, 35 parts of N-methyl perfluorooctanesulfonamidoethyl methacrylate, 20 parts of a poly(oxytetramethylene) acrylate and 10 parts of butyl acrylate, and 10 parts of (b) a fluoroaliphatic carbodiimide of one mol of N-ethyl perfluorooctanesulfonamidoethanol and one mol of 80:20 tolylene diisocyanate, which mixture was in a 40% solu~ion in CC12FCClF2:methylisobutyl ketone ::
2:1. -H was a copolymeric fluoroaliphatic oligomer of 40 parts N-methyl perfluorooctanesulfonamidoethyl acrylate, ~ .
40 parts octadecyl methacrylate and 20 parts of poly-(oxytetramethylene) acrylate of U. S. patent No.
3,787,351 in a 50% solution in methylisobutyl ketone.
I was a copolymeric fluoroaliphatic oli~omer of (a) 45 parts N-methyl perfluorooctanesulfonamidoethyl .
acrylate, (b) 45 parts of a reaction product of one --mol of N-methyl perfluorooctanesulfonamidoethanol, one mol of 2-hydroxypropyl methacrylate and one mol of 80:20 tolylene diisocyanate, and (c) 10 parts of butyl acrylate in a 20% solution in CC12FCClF2:
methyl isobutyl ketone :: 1:1 o -J was a copolymeric fluoroaliphatic oligomer of 70 parts N-methyl perfluorooctanesulfonam~doethyl acrylate, 20 parts poly(oxytetramethylene) acrylate, .

~ - 10 -,.~

1~60600 and 10 parts butyl acrylate in a 50% solution in methylisobutyl ketone.
Jl was Oligomer J in a 20% solution-suspension in 1500 molecular weight poly(oxypropylene) triol.
Results reported in Table I show that a fluoroaliphatic substance may not improve the gasoline repellency of poly-urethane foam if it lacks solubilizing moieties (as in Fluoroaliphatic Oligomers A and B) or may provide an insignificant improvement taS does Fluoroallphatic Oligomer C). Hence, Fluoroaliphatic Oligomers A, B and C are not useful in the present invention in the absence of an appreciable amount of a much more soluble fluoro-aliphatic substance. Fluoroaliphatic Substance D would be of submarginal utility, apparently not being suf-ficiently soluble in the polyurethane to afford good repellency to gasoline, its solubility being limited by its high fluorine content. Fluoroaliphatic Sub-stances E-J, having a suitable balance of solubilizing and insolubilizing moieties for this particular poly-urethane foam, were indicated to be useful for the purposes of the invention, and superior in the case of --Fluoroaliphatic Substances G-J.

Foam No. 13 Foam No. 13 was prepared in the same manner as Foam No. 12 except that 0.5 part of water was used in place of the CC13F blowing agent. Foam No. 13 was open-cell, had a density of 130 kg/m3 and had a value of 3.5 minutes in the above-described Gasoline Repel-lency Test.

106~)600 ~oams No. 14-18 A series of ~oams of the formulations given in parts by weight in Table II was made by weighing the in-gredients (60 g of mixture) into a plastic-coated 6-ounce (180 cm3) paper cup, stirring vigorously ~or 30 seconds, then placing in an oven at about 80C for about lO minutes. In each case a good foam of about 450 kg/m3 density was obtained which had raised out of the cup.

Table II
Parts by weight Foam No. 14 15 16 17 18 Isocyanate prepolymera lO0~0 100.0 100.0 lO0.0 lO0.0 CCl3F blowing agent 7.0 7.0 7.0 7.0 7.0 Fluoroaliphatic additiveb - 0.34 0.52 1.56 3.12 Silicone surfactant 1.3 1.3 1.3 1.3 1.3 Glycerine 5.9 5.9 5.9 5.9 5.9 Diold 4.24 4.02 3.82 3.18 2.12 Dlethyl-2-hydroxyethyl amine 0.8 0.8 0.8 o.8 0.8 Stannous octoate 0.2 0.2 0.2 0.2 0.2 .
aAn isocyanate prepolymer having an isocyanate number of about 450 prepared from 42 parts tolylene diisocya~ate and lO0 parts of a 1500 molecular wei~ht poly(oxypropylene) triol based on glycerine.
Fluoroaliphatic Oligomer J except as a 32 weight percent solution-suspension in a 400 molecular weight poly(oxy- -propylene)diol.

Poly(dimethylsiloxane), v~scosity 50 centistokes.

400 molecular weight poly(oxypropylene)diol.

.

~060600 The cooled ~oam was sliced to expose a cut surface of cells, and gasoline repellency was determined as in the Gasoline Repellency Test described abo~e except that the time re-corded was that required for the gasoline to essentially disappear (i.e., no light reflection from a liquid surface).
The values given in Table III are averages of three determinations.

Table III

Foam No. 14 15 16 17 18 10 Weight percent of Foam of Fluoroaliphatic Oligomer J 0 0.1 0.2 0.5 1.0 ~ -Gasoline repellency (minutes) <0.02 3 3.5 4.5 8.5 Example 1 Two double-coated pressure-sensitive adhesive open-cell foam tapes (Tapes L and M) were prepared as described above using a transfer tape as described in the Example of Canadian patent No. 747,341 (i.e., 90:10 iso-octyl acrylate:acrylic acid adhesive and butadiene-styrene copolymer barrier coat). The foam of Tape M was prepared in the same way as ~oam No. 12 except contain~ng a lower proportion (0.2 part) of the Fluoroaliphatic Oligomer Jl which is a copolymer of fluoroaliphatic poly(oxyalkylene) acrylate and fluorine-free hydrocarbon acrylate. Tape L

was identical to Tape M except it included no fluoro-aliphatic substance. Each of Tapes L and M had an overall thickness of 1.7 mm (exclusive of the disposable webs).
Tests on Tapes L and M are reported in Table IV.

... . . .. .

Table IV
Tape L Tape M
Foam dens~ty (kg/m3) 190 340 Compression at 2 N/cm2 (ASTM D 1564-71) 18% 13%
Resilience, 50% deflection at 23C (ASTM D 1564-71) 98% 98% :
Tensile strength (measured :
normal to surface) N/cm2 53 68 Peel strength in N/100 mm (180) 72 60 Gasoline repellency in minutes :
(as tested in Table I) <0.02 1.0 Example 2 Two single-coated pressure-sensitive adhesive foam tapes (Tapes N and O) were made in the same manner as described in Example 1 except that polyethylene-coated paper was substituted for one of the transfer tapes and the mixtures of ~oam producing batter were as indicated :-below. -.
Tape N Tape 0 (parts) (parts) Premixture of 25.55 parts o~ poly(oxy-propylene) diol of 2000 molecular weight, 24 parts of 1500 molecular weight poly-(oxypropylene) triol based on glycerine, 43.65 parts of kaoline clay5 5 parts of color paste of one part carbon black in 4 parts o~ poly(oxypropylene) diol of 2000 molecular weight, 0.4 part antioxidant (butylated hydroxytoluene), 0.3 part process stabilizer (calcium 2-ethylhexanoate), 0.1 part W stabil-izer and 1.0 part viscosity control t 100 0 100 0 agen ..................................

- 14 - ;

lV6~600 Tape N Tape 0 (parts) (parts) Stannous octoate ........... ,................ 1.O 1.O
2-ethoxyethanol ............................. 0.5 0.5 Fluoroaliphatic Oligomer Jl ~ 1.0*
Isocyanate prepolymer prepared from 66~1 parts of tolylene diisocyanate, 17.73 parts of poly(oxypropylene) diol of 2000 molecular weight, and 16.17 parts of tripropylene glycol .................................... 15.9 15.9 CC13~ blowing agent ........................ 8.o 8.o After foaming, both Tapes N and 0 had overall thicknesses about 6 mm and densities of 160 kg/m3. Tapes N and 0 exhibited water take-up of 44% and 77%, respectively, indicating that only the foam o~ Tape 0 had essentially open-cell structure as a consequence of its flu~roaliphatic ollgomer content. Tape 0 passed the Water Barrier Test described below, while Tape ~ failed within a few minutes.

Water Barrier Test A tape 1.27 cm in width is adhered by its own ad-hesive to a glass plate in the shape of a "U" with the legs of the "U" spaced about 10 cm. The tape is compressed by a second glass plate to 70% of its original thickness (30%
compression). A 5.0-cm static head of water is placed in the "U". If no water leaks through in less than one hour, the foam tape is considered to be effective as a water barrier.

*5.0 parts of the 20% solution-suspension of Table I

. , :

.... . . . -- . - .
.
~, . -; 1060600 Example 3 Two sin~le-coated pressure-sensitive adhesive foam tapes (Tapes P and Q) were made as in Example 2 except that each premixture contained 0.5 part phenylmercuric acetate as catalyst, 0.5 part of silicone surfactant [a polydimethyl-siloxane-poly(alkyleneoxide) copolymer], no stannous octoate and no CC13F. Also the amount of the Fluoroaliphatic Oligomer Jl (used only in making Tape Q) was reduced (as compared to Tape 0) to 0.5 part, and o.8 part water was used as the blowing agent with enough additional isocyanate terminated prepolymer (about 8.o parts) to react with the water. Both Tapes P and Q had an overall thickness of about 6 mm and a density of 160 kg/m3.
Tape P which included no fluoroaliphatic oligomer failed the Water Barrier Test within a few minutes, where-as Tape Q passed. In the Gasoline Repellency Test Tapes P and Q exhibited ~alues of ~0.02 and 2.5 minutes, respectively.

; 20 Foam No. 19 A foam essentially the same as that of Tape Q, except that the fluoroaliphatic oligomer le~el was about 4 weight percent of the foam, was tested for repellency to a variety of chemicals using the procedure described for the Gasollne Repellency Test. Excellent repellency ~-(~ minutes or more for a drop of the liquid to disappear, i.e., no light reflection) was obtained for each of isopropyl alcohol, propylene glycol, 1~4-butanediol, -heptane, methyl ethyl ketone, toluene, 2-ethylhexanoic acid, ethyl acetate, dibutylamine and poly(dimethylsiloxane).

~ .

The only liquid tested that was rapidly absorbed was CC12FCClF2. A drop of each of these liquids on a similar foam except ~or omission of the ~luoroaliphatic oligomer was absorbed in about one second or less.

:
':

.
: - 17 . :

.

,~ . , ; : ,. . ~ , .: .. ~ .

Claims

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

1. Pressure-sensitive adhesive tape having an open-cell polyurethane foam backing and incorporating in the polyurethane a foam-stabilizing fluoroaliphatic substance containing covalently bonded a) a plurality of fluoroali-phatic radicals having at least three fully fluorinated carbon atoms, one of which is terminal, and b) at least one moiety similar in structure to a moiety of the polyurethane, said solubilizing moieties providing 5 to 40 weight percent and carbon-bonded fluorine providing 10 to 45 weight percent of the fluoroaliphatic substance, the fluoroaliphatic sub-stance being free of functional groups containing active hydrogen atoms and being present in an amount affording repellency to gasoline.

2. Pressure-sensitive adhesive tape as defined in claim 1 wherein the fluoroaliphatic substance provides 0.02 to 10 weight percent of the polyurethane foam backing.

3. Pressure-sensitive adhesive tape as defined in claim 1 wherein the polyurethane is a polyether poly-urethane and said solubilizing moieties are predominately repeating oxyalkylene units having on the average 2,5 to 4 carbon atoms.

4. Pressure-sensitive adhesive tape as defined in claim 1 wherein the polyurethane is a polyester poly-urethane and said solubilizing moieties are predominately polyester groups.

5. Pressure-sensitive adhesive tape as defined in claim 1 wherein said solubilizing moieties are pre-dominately urethane linkages.

6. Pressure-sensitive adhesive tape as defined in claim 1 wherein fluorine provides 20-40 weight percent and said solubilizing moieties provide 10-25 weight percent of the fluoroaliphatic substance.

7. Double-coated pressure-sensitive adhesive tape as defined in claim 1.

8. Single-coated pressure-sensitive adhesive tape as defined in claim 1.

9. Pressure-sensitive adhesive tape having an open-cell polyurethane foam backing with dense skins, a pressure-sensitive adhesive layer united to one or both skins, and incorporating in the polyurethane one or more foam stabilizing fluoroaliphatic oligomers of the general formula:
[(Rf)mQ(RQ'A)n]z where Rf is a fluoroaliphatic radical having at least three fully fluorinated carbon atoms, one of which is terminal, R is a divalent organic radical, Q is a linkage through which Rf and R radicals are covalently bonded together, A is a monovalent terminal organic radical or a valence bond interconnecting a Q-bonded R
radical to another Q, Q' is a linkage through which A and R are covalently bonded together, m is an integer of at least 2, n and z are integers not exceeding 30, and the products mz and nz do not exceed 30,

[Claim 9 - cont.]

R and Q together comprise solubilizing moieties providing 5 to 40 weight percent of total oligomer, carbon-bonded fluorine provides 10 to 45 weight percent of total oligomer, and the fluoroaliphatic oligomer is free of functional groups containing active hydrogen atoms and is present in an amount affording repellency to gasoline.

10. Pressure-sensitive adhesive tape as defined in claim 9 wherein the polyurethane is a polyether polyurethane and said solubilizing moieties are provided by repeating oxyalkylene units having on the average 2.5 to 4 carbon atoms in R.

11. Pressure-sensitive adhesive tape as defined in claim 9 wherein the polyurethane is a polyester polyurethane and said solubilizing moieties are provided by polyester groups in R.

12. Pressure-sensitive adhesive tape as defined in claim 9 wherein said solubilizing moieties are provided by urethane linkages in Q.

13. Pressure-sensitive adhesive tape as defined in claim 9 wherein carbon-bonded fluorine provides 20-40 weight percent and said solubilizing moieties provide 10-25 weight percent of total oligomer.

14. Pressure-sensitive adhesive tape as defined in claim 9 wherein there is a single fluoroaliphatic oligomer which is a copolymer of fluoroaliphatic poly(oxyalkylene) acrylate and fluorine-free hydrocarbon acrylate in an amount providing 0.1-2.0 weight percent of the foam backing.