WO2015195616A1 - Adhesive tape bearing a pressure-sensitive adhesive that comprises a polar phenolic tackifier - Google Patents

Abstract

An adhesive tape with a pressure-sensitive adhesive that includes at least one natural rubber elastomer and/or synthetic rubber elastomer and a polar phenolic tackifier.

Description

ADHESIVE TAPE BEARING A PRESSURE-SENSITIVE ADHESIVE THAT COMPRISES A POLAR PHENOLIC TACKIFIER

Background

Architectural coatings are increasingly used on the interior and exterior of structures such as houses, apartments and office buildings. Pressure-sensitive adhesive compositions, and tapes based on such compositions, that possess enhanced ability to bond to architectural coatings are desired.

Summary

In broad summary, herein is disclosed an adhesive tape that comprises a pressure-sensitive adhesive that comprises at least one natural rubber elastomer and/or synthetic rubber elastomer, and at least one polar phenolic tackifier. These and other aspects will be apparent from the detailed description below. In no event, however, should this broad summary be construed to limit the claimable subject matter, whether such subject matter is presented in claims in the application as initially filed or in claims that are amended or otherwise presented in prosecution.

Brief Description of the Drawing

Fig. 1 is a schematic cross-sectional view of an adhesive tape as disclosed herein.

Fig. 1 is not to scale and is chosen for the purpose of illustrating different embodiments of the invention. In particular the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the Figure.

As used herein as a modifier to a property or attribute, the term "generally", unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring a high degree of approximation (e.g., within +/- 20 % for quantifiable properties). The term "substantially", unless otherwise specifically defined, means to a high degree of approximation (e.g., within +/- 10% for quantifiable properties). The term "essentially" means to a very high degree of approximation (e.g., within plus or minus 2 % for quantifiable properties); it will be understood that the phrase "at least essentially" subsumes the specific case of an "exact" match. However, even an "exact" match, or any other characterization using terms such as e.g. same, equal, identical, uniform, constant, and the like, will be understood to be within the usual tolerances or measuring error applicable to the particular circumstance rather than requiring absolute precision or a perfect match. Those of ordinary skill will appreciate that as used herein, terms such as "essentially free of, and the like, do not preclude the presence of some extremely low, e.g. 0.1% or less, amount of material, as may occur e.g. when using large scale production equipment subject to customary cleaning procedures. All references herein to numerical parameters (dimensions, ratios, and so on) are understood to be calculable (unless otherwise noted) by the use of average values derived from a number of measurements of the parameter, particularly for the case of a parameter that is variable. Detailed Description

Glossary

As used herein, the term "pressure-sensitive" adhesive (composition) denotes a composition that obeys the Dahlquist criterion, which criterion will be well known and understood by the ordinary artisan working in the art of pressure-sensitive adhesives.

As used herein, the term "tackifier" (e.g., a tackifying resin) means a material that is part of a pressure-sensitive adhesive as a rheological modifier to increase glass transition temperature, decrease modulus, increase tack, or a combination of two or more of these.

As used herein, the term "acid number" means the number of mg of potassium hydroxide (KOH) required to neutralize the acidic functionality present in 1 g of a tackifier compound.

As used herein, the term "hydroxyl number" means the number of mg KOH equivalent to the hydroxyl functionality present in 1 g of a tackifier compound.

With reference to Fig. 1 , disclosed herein are adhesive tapes 1 comprising a tape backing 4 with a pressure-sensitive adhesive 2 disposed on at least one major surface 3 of the backing, which tapes may display enhanced performance e.g. when bonded to architectural coatings (although the tapes of course may be bonded to any desired surface).

Pressure-sensitive adhesive 2 includes at least one polar tackifier (tackifying resin). The polar tackifier can exhibit heteroatom based polarity. In some embodiments the polar tackifier includes a phenolic moiety and is characterized by a hydroxyl value of between 20 and 130, in some cases between 20 and 90, in some cases between 40 and 80, in some case between 50 and 70, and in some cases between 55 and 65. The polar tackifier including a phenolic moiety can have an acid number of less than 0.5, in some cases less than 0.25, and in some cases about 0.

The phenolic moiety is an aromatic moiety having at least one hydroxyl group covalently bonded directly thereto; the simplest phenolic moiety is derived from the compound phenol (hydroxybenzene). In some embodiments, the phenolic moiety includes two or more aromatic rings bonded or fused together, either directly or through a linking group. In some embodiments the phenolic moiety has two or more hydroxyl groups bonded thereto. In some embodiments one or more additional substituents, such as alkyl groups, are present on the phenolic moiety. Blends of phenolic compounds are also suitably employed in the reactions leading to the terpene phenolic tackifiers useful in the pressure-sensitive adhesives described herein.

Phenolic compounds include polyhydroxylated benzenes. Useful polyhydroxylated benzene compounds include dihydroxybenzenes and trihydroxybenzenes. Dihydroxybenzene compounds useful in reactions herein can include, in embodiments, hydroquinone (1,4-dihydroxybenzene), catechol (1,2- dihydroxybenzene), and resorcinol (1,3-dihydroxybenzene). Trihydroxybenzene compounds useful in reactions herein can include, in embodiments, phloroglucinol (1,3,5-trihydroxybenzene),

hydroxyhydroquinone (1,2,4-trihydroxybenzene), and pyrogallol (1,2,3-benzenetriol). In some embodiments, polyhydroxylated adducts of naphthalene are useful in the reactions herein; examples of such compounds include, in embodiments, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 1,6- dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, and the like.

In some embodiments, hydroxylated and polyhydroxylated anthracene, phenanthrene, azulene, and the like are suitably employed in the reactions that form one or more terpene phenolics useful as tackifiers in the pressure-sensitive adhesive. Bisphenols, such as bisphenol A and other compounds having non- fused multiple aromatic rings bonded via a linking group are also useful; it is not necessary for each aromatic ring to have a hydroxyl group as long as at least one aromatic ring has at least one hydroxyl group present bonded directly thereto.

Additionally, dimers, trimers, and oligomers of phenolic compounds and blends thereof are suitably employed in the reactions that form one or more terpene phenolics useful as tackifiers in the pressure-sensitive adhesive. Such compounds include, for example, dimerized or oligomerized phenolic compounds formed via condensation with an aldehyde to result in methylene or methylol ether linking groups. Such compounds are widely used in the industry as precursors or prepolymers for phenol- formaldehyde resins. In some embodiments, both novalac and resole type precursors can be useful;

however, in some such embodiments novalac precursors are preferred. In some embodiments the phenolic compound, or a blend of phenolic compounds, are pre-condensed or oligomerized. In somewhat more detail, a phenolic compound, or a combination of two or more phenolic compounds are combined with an amount of an aldehyde that is selected to provide the desired level of oligomerization, and an acidic or basic catalyst employed under conditions of mild heat, for example between 50° C and 100° C, to obtain the condensation products thereof. The oligomers thus formed have multiple reaction sites that are useful in subsequent steps in the formation of the tackifiers useful in the adhesive compositions herein, as will be readily recognized by one of skill. In some embodiments, suitable phenolic oligomers include naturally occurring oligomeric structures, such as tannic acid, humic acid, fulvic acid, and Quebracho extracts.

In some embodiments one or more additional substituents are present on one or more rings of the phenolic compounds. For example one or more alkyl, ether, halogen, amino, amido, imino, carbonyl, or other substituents, or a combination of two or more thereof, may be present as substituents bonded to the aromatic ring(s) of the phenolic compounds, or present as a substituent on an alkyl or alkenyl group bonded to the aromatic ring(s) of the phenolic compounds. In many embodiments, however, the one or more additional substituents substantially exclude or completely exclude acidic or potentially acidic moieties. In some embodiments, tackifiers used in the pressure-sensitive adhesives are characterized by an acid number of less than about 0.5. In some embodiments, tackifiers used in the pressure-sensitive adhesives herein are characterized by an acid number of less than about 0.4. In some embodiments, tackifiers used in the pressure-sensitive adhesives are characterized by an acid number of less than about 0.3. In some embodiments, tackifiers used in the pressure-sensitive adhesives are characterized by an acid number of less than about 0.25. In some embodiments, tackifiers used in the pressure-sensitive adhesives are characterized by an acid number of less than about 0.2. In some embodiments, tackifiers used in the pressure-sensitive adhesives are characterized by an acid number of less than about 0.1. In some embodiments, tackifiers used in the pressure-sensitive adhesives herein are characterized by an acid number of about 0.

In some embodiments, carboxylate, sulfonate, phosphonate, and other groups are excluded from the group of additional substituents that may be present in any moiety bonded to the tackifiers useful in the pressure-sensitive adhesives herein. Examples of suitable phenolic compounds having one or more additional substituents present thereon include various isomers of hydroxytoluene, orcinol (3,5- dihydroxytoluene) and 2,5-dimethyl resorcinol.

In some embodiments, phenolic compounds having more than one more than one hydroxyl group, more than one aromatic group, and one or more additional substituents are suitably employed in the reactions that form one or more tackifiers that are useful in the pressure-sensitive adhesives herein. Some examples of such compounds include 4,4'-((lE)-l-penten-4-yne-l,5-diyl)biscatechol, quercetin (2-(3,4- dihydroxyphenyl)-3,5,7-trihydroxychromen-4-one), myricetin (3,5,7-trihydroxy-2-(3,4,5- trihydroxyphenyl)chromen-4-one), theaflavin (l,8-bis(3-alpha,5,7-trihydroxy-2-alpha-chromanyl)-5H- benzocyclohepten-5-one) and gossypol (7-(8-formyl- 1 ,6,7-trihydroxy-3-methyl-5-propan-2-ylnaphthalen- 2-yl)-2,3,8-trihydroxy-6-methyl-4-propan-2-ylnaphthalene- l-carbaldehyde).

Blends of two or more of any of the phenolic compounds described herein are useful in various embodiments to form the tackifiers useful in the pressure-sensitive adhesives herein. The use of any of the above alone or in combination is not particularly limited; rather, the selection and use thereof is suitably adjusted to result in the desired end product useful in one or more adhesive compositions described herein or others that will be envisioned by one of skill.

The phenolic compounds as described above can be reacted with alkenyl compounds having at least 10 carbons, and no acidic moieties, to form the polar tackifiers useful in the adhesive compositions herein. The alkenyl compounds can be linear, branched, cyclic, or a combination thereof, and contain one or more unsaturated moieties that are reactive with a phenolic compound when catalyzed by an acid. One class of such alkenyl compounds is the terpenes. Terpenes are a class of hydrocarbons occurring widely in plants and animals, although synthetic versions are both available and useful herein. Empirically the terpenes are dimers, trimers, and higher oligomers of isoprene, or 2-methyl-l,3-butadiene. Isoprene has the formula CH2=C(CH3)-CH=CH2, or (CsHs); terpene compounds have the formula (CsH8)n where n is 2 or more. Terpenes can include one or more cyclic moieties. Terpenes are generally referred to in accordance with the number of isoprene units in the molecule: monoterpenes (C10H16) contain two isoprene units; sesquiterpenes (C₁₅H₂₄), three; diterpenes (C₂0H3₂), four; triterpenes (C30H₄8), six; and tetraterpenes (C₄0H6₄), eight. Monoterpenes, sesquiterpenes, and diterpenes are abundant in the essential oils of plants. Monoterpenes include a-pinene, its isomers β-pinene and γ-pinene, linalool, myrcene, limonene, carene, and camphene. Turpentine contains several monoterpenes. Sesquiterpenes include caryophyllene, zingiberene, humulene, cadinene, longifolene, cedr-8-ene, and farnesene. Diterpenes include ferruginol, cafestol, cembrene, sclarene, steviol, and taxadiene. Vitamin A is a diterpene derivative, as are the rosin acids. The triterpene squalene, obtainable from shark-liver oil, may be converted to cholesterol and many other steroids. The carotenes (α, β, γ, δ, ε, and ζ isomers, among others) are the best known tetraterpenes.

Terpene compounds are reacted with phenolic compounds to result in terpene phenolic tackifiers useful in the pressure-sensitive adhesives disclosed herein. For the purposes of this disclosure, terpene phenolic tackifiers, or terpene phenolics, have at least one aromatic group bearing at least one hydroxyl group bound directly to the aromatic group; and at least one branched alkyl or alkenyl group bonded directly to an aromatic group. In some embodiments, the branched alkyl or alkenyl group is derived from an oligomer of isoprene. In some embodiments, the terpene phenolic has a single aromatic group having one or more hydroxyl groups and one or more branched alkyl or alkenyl group bonded directly thereto. In other embodiments, the terpene phenolic has more than one aromatic group having one or more hydroxyl groups and one or more branched alkyl or alkenyl group bonded directly to one or more aromatic groups. In some embodiments, the terpene phenolic tackifier is non-reactive; in other embodiments, the terpene phenolic tackifier may be reactive (e.g., it may comprise one or more reactive groups).

Conventional methods are employed to make the terpene phenolic tackifiers useful in the adhesive compositions herein. Some representative methods that are useful to form terpene phenolic tackifiers include those described in US Patent Nos. 3,347,935; 3,692,844; 3,976,606; 5,457, 175; and 6,160,083; and EP 1504074. In some embodiments, the terpene phenolic tackifiers are 1 : 1 addition products of phenolic compounds with terpene compounds. In some such embodiments, the reaction is catalyzed by acidic or acid-forming catalysts. Using limonene and phenol as exemplary reagents for illustrative purposes only, the reaction proceeds via path a or path b below, typically resulting in a

B C

Compound A is an aromatic ether, while compounds B and C are modified phenolics. In many embodiments reaction path b favors formation of product C over B. Only reaction path b results in residual hydroxyl functionality. The degree of selectivity of reaction path a over reaction path b, and thus the degree of hydroxyl functionality of the final product, is one factor that determines the utility of the terpene phenolic tackifiers that are useful in the adhesive compositions herein. It is important to note that a mixture of A, B, and C type products in a tackifier is acceptable: it is the total hydroxyl content of the tackifier, measured and expressed as the hydroxyl number, that is important for the tackifiers useful in the adhesive compositions herein. Measurement of hydroxyl number is discussed below.

In the reaction scheme pictured above, it is important to note that in some embodiments the reaction does not yield only the 1 : 1 addition reaction products as pictured. In some embodiments, two or more terpenes react with one phenolic compound. In other embodiments, two or more phenolic compounds react with one terpene. In embodiments where the phenolic compound has more than one site available for reaction with a terpene compound (in the case of phenol itself, there are 3 potential reactive sites), or where the terpene has more than one site available for reaction with a phenolic compound, X:Y phenolic compound : terpene compound reaction products can arise. For example, in embodiments 3: 1, 2: 1, 1 :2, 1 :3, or other reaction product ratios arise. This is particularly true where oligomeric phenolic compounds having multiple aromatic hydroxyls are employed as the phenolic compound starting material. In such embodiments, the relative amounts of 1 : 1, 1 :2, or other reaction products present in a reaction mixture, or in a blend formed after the reaction, may be expressed as an average phenolic:terpene reaction product ratio such as e.g. 1 : 1.5,1.7: 1, 1 : 1.02, and the like. For the purposes of the terpene phenolic tackifiers useful in the adhesive compositions herein, such ratios are not particularly limited. In some embodiments, the average phenolic:terpene reaction product ratio is between about 2: 1 and 1 :2, or between about 1.5: 1 and 1 : 1.5.

In some embodiments, terpene phenolics useful in the adhesive compositions have average molecular weights of about 200 g/mol to 3000 g/mol, or about 200 g/mol to 1600 g/mol, or about 250 g/mol to 1500 g/mol, or about 300 g/mol to 1000 g/mol, or about 300 g/mol to 800 g/mol, or about 400 g/mol to 800 g/mol, or about 500 g/mol to 700 g/mol. In some embodiments, terpene phenolics useful in the adhesive compositions have a polydispersity of about 1 to 3, or about 1 to 2, or about 1 to 1.5. In some embodiments, terpene phenolics useful in the adhesive compositions herein can have glass transition temperatures of about 40°C to 120°C, or about 50°C to 100°C. In some embodiments, terpene phenolics useful in the adhesive compositions herein have softening points of about 80°C to 200°C, about 80°C to 150°C, or about 90°C to 130°C, or about 100°C to 120°C, or about 105°C to 160°C, or about 105°C to 125°C, or about 1 10°C to 120°C, or about 1 15°C, 130°C or 160°C.

In various embodiments, terpene phenolic tackifiers that are useful in the adhesive compositions disclosed herein include those with an acid number that is very low. By way of example, in some embodiments terpene phenolic tackifiers used herein can have an acid number of less than about 0.5. In some embodiments terpene phenolic tackifiers used herein can have an acid number of less than about 0.25. In some embodiments terpene phenolic tackifiers used herein can have an acid number of less than about 0.1. In some embodiments terpene phenolic tackifiers used herein can have an acid number of about 0. Acid number is the number of mg of potassium hydroxide (KOH) required to neutralize the acid functionality in a 1 g aliquot of the tackifier compound. Various methods are employed by the skilled practitioner to determine acid number. In one typical procedure, a known amount of the tackifier is dissolved in organic solvent is titrated with a solution of KOH of known concentration, employing phenolphthalein as a color indicator. Other acid number tests include ASTM D 974 and ASTM D664. Included in the definition of "about 0" is an acid number that is very close to 0, such as 0.05, in order to account for minimal amounts of impurities or error in the testing measurements.

The terpene phenolic tackifiers can have a hydroxyl number between about 0 (such as for a nearly pure Compound A aromatic ether type reaction product shown above) and 220. In embodiments, terpene phenolic tackifiers that are useful in the adhesive compositions herein include those with a hydroxyl number in the range of about 20 to 130, or about 20 to 90, or about 30 to 80, or about 40 to 80, or about 50 to 70 or about 55 to 65. The hydroxyl number is defined as the number of mg KOH corresponding to the hydroxyl functionality in a 1 g aliquot of the tackifier compound. Various methods are employed by the skilled practitioner to determine hydroxyl number. The most frequently described method is conversion of the sample with acetic acid anhydride in pyridine with subsequent titration of the released acetic acid (also described in ASTM D 1957-86(2001) Standard Test Method for Hydroxyl Value of Fatty Oils and Acids (Withdrawn 2007)). Also widely employed is the method according to ASTM E 1899, wherein primary and secondary hydroxyl groups are converted with toluene-4-sulfonyl-isocyanate (TSI) into an acid carbamate, which is then titrated with tetrabutylammonium hydroxide (TBAH) in a nonaqueous medium.

In many embodiments, commercially available terpene phenolics are useful in the adhesive compositions herein. Terpene phenolic tackifiers are sold, for example, by the Arizona Chemical Company of Jacksonville, FL, under the trade name SYLVARES®; by MeadWestvaco Corporation of North Charleston, SC under the trade name DERTOPHENE®; and by the Yasuhara Chemical Company, Ltd. of Fuchu City, Japan under the trade name POLYSTER®. Specific tackifiers can include, but are not limited to, SYLVARES® TP 1 15, SYLVARES® TP 96, SYLVARES® TP 2019, POLYSTER® T160, POLYSTER® T130, POLYSTER® T100, POLYSTER® Tl 15, POLYSTER® T145, POLYSTER® TH130, POLYSTER® Ul 15 and UH1 15, and POLYSTER® T80. Also potentially suitable may be the hydrogenated terpene phenol available from Yasuhara Chemical Company under the trade designation TH130.

The ordinary artisan will appreciate e.g. based on the Working Examples presented herein, that the inclusion of a polar phenolic tackifier, e.g. a terpene phenolic tackifier, can provide enhanced adhesion to at least some architectural coatings (e.g., various low-VOC paints), particularly under conditions of elevated humidity. The ordinary artisan will also understand that due to the wide variety of architectural coating compositions, such enhancement may not necessarily occur to the same degree for every architectural coating (alternatively phrased, different levels of polar phenolic tackifier, and/or polar phenolic tackifiers of different composition, may be optimum for use with different architectural coatings).

It will be understood that "phenolic tackifier" includes blends of two or more such tackifiers. Blends of two or more phenolic tackifiers are useful in some embodiments of the adhesive compositions herein. In some embodiments, the blends of phenolic tackifiers include blends of tackifiers differing solely in terms of molecular weight, degree of branching, or types of terpenes and/or phenolic compounds employed as starting materials to make the phenolic tackifiers. In other embodiments, the blends of phenolic tackifiers have more than one such difference.

In some embodiments, pressure-sensitive adhesive 2 also includes at least one nonpolar tackifier.

As defined herein, nonpolar tackifier means a compound or mixture of compounds that function as tackifiers in a pressure-sensitive adhesive as disclosed herein and that do not include polar groups. While not being particularly limited, such nonpolar tackifiers often have a softening point between about 100°C and 135°C, or about 110°C to 120°C, and in at least some instances are compatible in mixtures with styrene block copolymers.

Any suitable nonpolar tackifier(s) may be used. Potentially suitable tackifying resins may include (but are not limited to) e.g. aliphatic olefin-derived resins such as the ESCOREZ™ 1000 series (from ExxonMobil Chemical Co.) and the WINGTACK™ series (from Cray Valley USA, LLC); aromatic modified aliphatic resins such as the ESCOREZ™ 2000 series (from ExxonMobil Chemical Co.) and the NORSOLENE™ M series (from Cray Valley USA, LLC); cycloaliphatic hydrocarbons, such as the

ESCOREZ™ 5000 series (from ExxonMobil Chemical Co.); hydrogenated pure monomer resins such as the REGALREZ™ series (from Eastman Chemical Co.); gum rosin esters such as the FORAL™ series and the STAYBELITE-E™ series (both from Pinova, Inc.); tall oil rosin esters such as the

SYLVATAC™ and SYLVALITE™ series (from Arizona Chemical), the WESTREZ™ 5000 series (from MeadWestvaco Corp.) and the PERMALYN™ series (from Eastman Chemical Co.); polyterpenes such as the PICCOLYTE™ A, F, C and S series (from Pinova, Inc.) Other nonpolar tackifiers that may be potentially suitable include but are not limited to polyaromatics such as the PICCO™ 6100 aromatic hydrocarbon resin (from Eastman Chemical Co.); coumarone-indene resins such as CUMAR™ P-25 (from Neville Chemical Co.) and other high-solubility parameter resins derived from coal tar or petroleum and having softening points above about 85°C such as SYLVARES™ SA 100 alpha-methyl styrene resin (from Arizona Chemical) and the PICCOTEX™ series of alpha-methyl styrene/vinyl toluene resins (from Eastman Chemical Co.). Hydrogenated (either partially or completely) tackifiers may also be used. Examples of hydrogenated tackifiers include, for example, hydrogenated rosin esters (commercially available as FORAL 85 from Pinova, Incorporated, Brunswick, GA); hydrogenated aromatic hydrocarbon resins; hydrogenated aromatic-modified hydrocarbon-based resins; hydrogenated aliphatic hydrocarbon-based resins; and combinations thereof.

In some embodiments one or more e.g. nonpolar tackifiers may be chosen so as to be particularly effective at tackifying natural rubber elastomer. Potentially suitable candidates may generally include but are not limited to aliphatic olefin-derived resins such as the PICCOTAC™ 1000 series (from Eastman Chemical Co.) and ESCOREZ™ 1000 series (from ExxonMobil Chemical Co.); gum rosin esters such as the FORAL™ series and the STAYBELITE-E™ series (both from Pinova, Inc.); tall oil rosin esters such as the SYLVATAC™ and SYLVALITE™ series (from Arizona Chemical), the WESTRES™ 5000 series (from MeadWestvaco Corp.) and the PERMALYN™ series (from Eastman Chemical Co.); polyterpenes such as the PICCOLYTE™ A, F, C and S series (from Pinova, Inc.); cycloaliphatic hydrocarbons, such as the ESCOREZ™ 5000 series (from ExxonMobil Chemical Co.). Other particular examples include e.g. the aliphatic hydrocarbon-based resins commercially available as QUINTONE K100 from Zeon

Corporation, Tokyo, Japan, and WINGTACK 95 from Cray Valley USA, LLC, Exton, PA.

In some embodiments, the tackifier may be an aliphatic material (and, if multiple tackifiers are present, they may all be aliphatic materials). In particular embodiments, the tackifier or tackifiers may be a hydrocarbon material. In specific embodiments, the tackifier or tackifiers may be a so-called C5-derived aliphatic resin, which are generally derived from the oligomerization or polymerization of monomers with five carbons as will be well understood by the ordinary artisan. Potentially suitable C5-derived aliphatic resins may include e.g. the materials available from Eastman Chemical Co. under the trade designations PICCOTAC 1020, 1095, 1098, 1 100, and 1 115. So-called C9-derived aliphatic resins, and/or C5/C9- derived resins, may also be used.

Pressure-sensitive adhesive 2 also includes at least one elastomer that is chosen from natural rubbers and synthetic rubbers and combinations thereof. The ordinary artisan will appreciate that natural rubber (being comprised in large part of poly-cz^'s-isoprene) is conventionally considered to be a "non- thermoplastic hydrocarbon elastomer" that often may exhibit no measurable melting temperature as measured using Differential Scanning Calorimetry (DSC); accordingly, in some cases it may require special processing or compounding in order to be incorporated into a pressure-sensitive adhesive.

In further detail, natural rubber is predominantly cis- 1 ,4-polyisoprene and may range in grade from a light pale crepe grade to a darker ribbed smoked sheet. Examples of commercially available natural rubbers that may be useful as an elastomeric component of the herein-disclosed pressure-sensitive adhesive compositions include the material available from Akrochem, Akron Ohio, under the trade designation CLARIMER CV-60 (a controlled viscosity rubber grade) and SMR-5 (a ribbed smoked sheet rubber grade). Natural rubber may range in molecular weights from e.g. about 100,000 g/mol to about 1,000,000 g/mol. As mentioned above, because of their non-thermoplastic nature, many natural rubber grades may need to be masticated to reduce their molecular weight to facilitate e.g. hot-melt coating. This may be conventionally done by pre-processing e.g. in a Banbury mixer. Alternatively, US Pat. No.

5,539,033 to Bredahl describes a twin-screw extrusion compounding operation for processing natural rubber into a condition in which can be incorporated into a hot-melt coatable composition.

As disclosed herein, a synthetic rubber can be chosen from e.g. butyl rubber, synthetic polyisoprene rubber, ethylene-propylene rubber, ethylene -propylene- diene rubber, polybutadiene rubber, polyisobutylene rubber, poly(alpha-olefin) rubber, nitrile rubber, and styrene -butadiene rubber, and may, if needed, be processed in the manner described above for natural rubber.

In some embodiments, pressure-sensitive adhesive 2 may optionally include one or more block copolymers that include substantially only hydrogen and carbon atoms. In some embodiments the hydrocarbon block copolymers include discrete blocks wherein one block is substantially free of content from another block. In other embodiments the hydrocarbon block polymers include one or more blocks having measurable or even significant content attributable to another block; in such embodiments, the hydrocarbon block copolymers are referred to as "blocky". It will be understood that where hydrocarbon block copolymers are discussed herein, the discussion relates to both discrete block copolymers and blocky copolymers unless otherwise specified.

In particular embodiments, the pressure-sensitive adhesive can include block copolymers that are styrene block copolymers (SBCs). SBCs generally comprise copolymers of the A-B or A-B-A type and combinations thereof, where A represents a thermoplastic polystyrene block and B represents an elastomeric block of e.g. polyisoprene, polybutadiene, poly(ethylene/butylene), poly(ethylene/propylene) or poly(isoprene/butadiene). SBC molecular weights typically range from about 100,000 g/mole to about 1,500,000 g/mole.

Examples of useful styrene-based block copolymers include styrene-isoprene block copolymers, styrene-ethylene block copolymers, styrene -propylene block copolymers, styrene-ethylene-propylene block copolymers, styrene-ethylene-butylene block copolymers, styrene -butadiene block copolymers, styrene-isoprene-butadiene-styrene block copolymers, and combinations thereof. In some embodiments, the styrene based block copolymers are diblock, triblock, or higher block copolymers. In some embodiments, the styrene-based block copolymer is a styrene-isoprene diblock copolymer, a styrene- isoprene-styrene triblock copolymer, and combinations and mixtures thereof. In some embodiments, functionalized (e.g., maleated) versions of any of the above block copolymers may be used.

SBCs can exist in various molecular architectures including linear, branched, radial, star and tapered geometries. Variation of the volume fraction of styrene in the two-phase composition leads to polystyrene domains in the shape of spheroids, cylinders, plates and co-continuous structures. In various embodiments, the styrene component in the one or more styrene block copolymers can range from e.g. about 5 % styrene to about 50 wt. %, or from about 8 % styrene to about 40 %, or from about 15 wt. % to 35 wt. %, or from about 20 wt. % to about 30 wt. %.

Non-limiting examples of commercially available SBCs useful in formulating pressure-sensitive adhesives (PSAs) include styrene-isoprene block copolymers such as KRATON™ Dl 16 IP (from Kraton Performance Polymers, Inc.), VECTOR™ 41 13 (from Dexco Polymers LLP), QUINTAC™ 3620 (from Zeon Corp.) and EUROPRENE™ SOL T 91 13 (from Polimeri Europa S.p.A.); styrene-ethylene/butylene block copolymers such as KRATON™ G1657 (from Kraton Performance Polymers, Inc.); styrene- ethylene/propylene block copolymers such as KRATON™ G1702 (from Kraton Performance Polymers, Inc.); styrene-butadiene block copolymers such as KRATON™ Dl 1 18X (from Kraton Performance Polymers, Inc.) and styrene-isoprene/butadiene block copolymers such as KRATON™ Dl 17 IP (from Kraton Performance Polymers, Inc.). High molecular weight (e.g., > 800,000 g/mole) SBC's based on multi-arm star-block copolymer architectures such as those described in US Pat. Nos. 5,296,547 and 5,773,506 (which are incorporated by reference in their entirety herein) may be particularly useful. In particular embodiments, the SBC is a block copolymer that comprises isoprene units and is at least substantially free of butadiene units. In specific embodiments, the SBC is a styrene-isoprene block copolymer that is at least substantially free of butadiene units and that exhibits a multi-arm star-block architecture.

SBCs can be modified if desired by the addition of one or more tackifiers and/or plasticizing oils e.g. to increase the pressure-sensitive tack. Any suitable tackifier that is particularly effective in combination with an SBC may be used in the pressure-sensitive adhesive, e.g. along with the earlier- described polar tackifier. In particular embodiments, a single nonpolar tackifier may be used that is effective in tackifying both natural rubber and an SBC; in other embodiments, at least one first nonpolar tackifier may be present primarily for the purpose of tackifying the natural rubber, and at least one second nonpolar tackifier may be present primarily for the purpose of tackifying the SBC.

In some embodiments, a non-styrenic hydrocarbon block copolymer or combination thereof can be used, either along with a styrenic block copolymer, or without any styrenic block copolymer being present. Such block copolymers may include e.g. isoprene-butadiene block copolymers, ethylene-butylene block copolymers, and ethylene -propylene block copolymers.

In some embodiments, the hydrocarbon block copolymer (e.g., styrene block copolymer) may include a blends of two or more such copolymers. In some embodiments, the blends of block copolymers include blends of polymers differing solely in terms of overall molecular weight, molecular weight of one or more blocks, degree of branching, chemical makeup of blocks, number of blocks, or molecular weight of block fractions. In other embodiments, the blends of block copolymers have more than one such difference. In some embodiments, a blend of substantially linear triblock copolymer blended with a substantially linear block copolymer may be employed.

As noted, pressure-sensitive adhesive composition 2 will include at least one polar tackifier, optionally at least one nonpolar tackifier, and at least one elastomer that is chosen from natural rubbers and synthetic rubbers and combinations thereof. In some embodiments the adhesive composition may optionally include a hydrocarbon block copolymer, e.g. a block copolymer based on styrene and isoprene, also as noted. (Other components may also be present and are discussed later herein.)

In various embodiments, the polar tackifier may be present in the pressure-sensitive adhesive composition at at least about 4, 8, 16, 18, 20, 22, 24, or 27 wt. % based on the total weight of the pressure-sensitive adhesive composition. In further embodiments, the polar tackifier may be present at at most about 50, 44, 40, 36, 34, 32, 30, or 28 wt. %, again based on the total weight of the pressure- sensitive adhesive composition. It is specifically noted that these and all such weight percentages, ratios of weight percentages, and so on, are based on the total weight of the pressure-sensitive components of the adhesive (as it is present on the tape backing), and specifically do not take into account the presence of any inert filler (e.g., a mineral filler such as calcium carbonate, titanium dioxide, talc, glass powder, silica and so on) that may be present. That is, for the purposes of all of the compositional calculations and ranges disclosed herein, the presence of any mineral filler will be ignored. In various embodiments, the nonpolar tackifier, if present, may be present in the pressure- sensitive adhesive composition at at least about 8, 16, 18, 20, 22, or 24 wt. % based on the total weight of the pressure-sensitive adhesive composition. In further embodiments, the nonpolar tackifier may be present at at most about 50, 40, 36, 34, 32, 30, 26, or 24 wt. %, again based on the total weight of the pressure-sensitive adhesive composition. In various embodiments, the weight ratio of total polar tackifier to total nonpolar tackifier can be at least about 35:65, 40:60, 45:55, or 50:50. In further embodiments, this ratio may be at most about 65:35, 60:40, 55:45, or 50:50. In various embodiments, all tackifiers

(including both polar and nonpolar) may be present at at least about 20, 25, 30, 35, 40, 45, 50, or 55 wt. % based on the total weight of the pressure-sensitive adhesive composition. In further embodiments, all tackifiers (including both polar and nonpolar) may be present at at most about 65, 60, 55, 50, 45, 40, or 35 wt. % based on the total weight of the pressure-sensitive adhesive composition.

In various embodiments, the elastomer that is chosen from natural rubbers and synthetic rubbers and combinations thereof may be present in the pressure-sensitive adhesive composition at at least about 20, 25, 30, 35, or 40 wt. % based on the total weight of the pressure-sensitive adhesive composition. In further embodiments, the elastomer may be present at at most about 65, 60, 55, 50, 45, or 40 wt. %, again based on the total weight of the pressure-sensitive adhesive composition.

If a hydrocarbon block copolymer (e.g. a styrene-isoprene block copolymer) is present, in various embodiments the hydrocarbon block copolymer may be present in the pressure-sensitive adhesive composition at at least about 10, 12, 14, or 16 wt. % based on the total weight of the pressure-sensitive adhesive composition. In further embodiments, the hydrocarbon block copolymer may be present at at most about 35, 30, 24, 22, 20, or 18 wt. %, again based on the total weight of the pressure-sensitive adhesive composition. If a hydrocarbon block copolymer is present, the weight ratio of the hydrocarbon block copolymer to the total amount of tackifier (both polar and nonpolar) in the pressure-sensitive adhesive composition may be at least about 25:75, 30:70 or 35:65. In further embodiments, this weight ratio may be at most about 50:50, 45:55, or 40:60.

The pressure-sensitive adhesive composition may optionally include one or more oils (which oils may generally be distinguished from e.g. a tackifier by way of their lower molecular weight). Such oils may serve as e.g. rheology modifiers, plasticizers, and so on. Potentially useful oils include, but are not limited to the TUFFLO™ HR series of naphthenic oils (from Calumet Specialty Products Partners, LP), NYFLEX™ 222B naphthenic oil (from Nynas AB), KAYDOL™ heavy white mineral oil (from

Sonneborn Refined Products B.V.) and liquid polyisobutylene such as OPPANOL™ B10 (from BASF). If present, such an oil (or combination of oils) may be present at from e.g. at least at about 1, 2, 4, or 8 wt. %; in further embodiments, it may be present at less than about 24, 20, 16, 12, 8, or 4 wt. %. In some embodiments, the pressure-sensitive adhesive composition is at least substantially free of any such oil.

In some embodiments, the pressure-sensitive adhesive composition may optionally include one or more additional components, as desired for any purpose. Such additional components might be, but are not limited to, e.g. an anti-aging agent, a light and/or ultraviolet stabilizer (such as e.g. a hindered amine light stabilizer), a colorant, a thermal stabilizer, an antimicrobial agent, a filler, a crosslinker, and/or any mixture thereof.

In various embodiments, pressure sensitive adhesive compositions herein can include an antioxidant. While not intending to be bound by theory, it is believed that antioxidants can be useful to prevent oxidation reactions from affecting components of the compositions. Oxidation of components can lead to various negative effects including, but not limited, to color changes, changes in molecular weight of polymeric components, rheological changes, changes in tack, changes to release properties, and the like.

Antioxidants can include various agents including, but not limited to, phenols (including but not limited to hindered phenolics and bisphenolics), mercaptan group containing compounds (including, but not limited to thioethers, thioesters, and mercapto-benzimidazoles), di-hydroquinolines, hydroquinones, lactates, butylated paracresols, amines, unsaturated acetals, fluorophosphonites, phosphites, and blends of these. It will be appreciated that these groups are not exclusive in some cases. By way of examples, a phenolic compound could also have a mercaptan group.

Examples of phenolic antioxidants can include, but are not limited to ETHANOX® 330,

ETHANOX® 702, CYANOX® 425, CYANOX® 2246, CYANOX® 1790, ULTRANOX® 276, HOSTANOX® 03, ISONOX® 129, ISONOX® 132, NAUGARD® BHT, NAUGARD® 76 and NAUGARD® 10, NAUGARD® SP, NAUGARD® 529, TOPANOL® CA, TOPANOL® CA-SF and TOPANOL® 205, IRGANOX® 1010, IRGANOX® 1035, IRGANOX® 1076, IRGANOX® 1098, IRGANOX® 245, IRGANOX® 31 14, and IRGANOX® 565.

Examples of mercaptan group containing antioxidants can include, but are not limited to, IRGANOX® 1726 and IRGANOX® 1520 L.

Other mercaptan group containing antioxidants, in the form of thioether antioxidants, can include, but are not limited to, IRGANOX® PS800 and IRGANOX® PS802.

Other mercaptan group containing antioxidants, in the form of thioester antioxidants, can include, but are not limited to, CYANOX® LTDP, CYANOX® STDP, CYANOX® MTDP, CYANOX® 1212, and CYANOX® 71 1.

Examples of fluorophosphonite antioxidants can include, but are not limited to, ETHANOX®

398.

Examples of phosphite antioxidants can include, but are not limited to, WESTON 619,

HOSTANOX® PAR 24, WYTOX® 312 and NAUGARD® P, NAUGARD® 524, Irgafos 126, and Irgafos 168

Further examples of antioxidants can include, IRGANOX® 1330, IRGANOX® 1425,

IRGANOX® 1425 WL, IRGANOX® 245 DW, IRGANOX® 5057, IRGANOX® B 1 171, IRGANOX® B 215, IRGANOX® B 225, IRGANOX® B 501 W, IRGANOX® B 900, IRGANOX® E 201,

IRGANOX® L 06, IRGANOX® L 101, IRGANOX® L 107, IRGANOX® L 109, IRGANOX® L 1 15, IRGANOX® L 1 18, IRGANOX® L 135, IRGANOX® L 150, IRGANOX® L 55, IRGANOX® L 57, IRGANOX® L 64, IRGANOX® L 67, IRGANOX® L 74, IRGANOX® MD-1024, IRGANOX® ML- 81 1, IRGANOX® ML-820, IRGANOX® ML-840, IRGANOX® PS 802 FL, IRGANOX® XT 500, and IRGASTAB® FS 042.

In some embodiments, the antioxidant specifically has hydroxyl and/or hydroperoxide decomposing ability.

In some embodiments, the amount of the antioxidant used is greater than about 0.01 wt. %, 0.05 wt. %, 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, 0.5 wt. %, 1.0 wt. %, 1.5 wt. %, or greater than 2.0 wt. %. In some embodiments, the amount of the antioxidant used is less than about 5 wt. %, 4 wt. %, 3 wt. %, 2.5 wt. %, 2 wt. %, 1.5 wt. %, or 1.0 wt. %, 0.8 wt. %, or 0.5 wt. %. In some embodiments, the amount of the antioxidant used can be in a range wherein any of the preceding numbers can form the lower bound or higher bound of the range wherein the higher bound is higher than the lower bound. In some

embodiments, the amount of the antioxidant can be in a range of about 0.10 wt. % to about 2.0 wt. %.

In some embodiments the pressure-sensitive adhesive compositions herein have a glass transition temperature (Tg) of 15°C or less, 0°C or less, or - 10°C or less as measured by dynamic mechanical analysis, and determined as the tan δ (delta) peak parameter at a frequency of lHz and a temperature ramp rate of 3°C. In some embodiments, the Tg of the composition measured using this technique is between about -40°C and about 0°C, or between about -30°C and about -10°C, or between about -20°C and about - 15°C.

In some embodiments the pressure-sensitive adhesive compositions herein are characterized by a storage modulus (G', measured at 1 Hz)) of about 70,000 Pa to about 1,500,000 at 25°C, as measured by dynamic mechanical analysis. In some embodiments the pressure-sensitive adhesive compositions herein are characterized by storage modulus (G') of about 400,000 Pa or less at 25°C, as measured by dynamic mechanical analysis. In some embodiments, the storage modulus (G') is about 350,000 Pa or less at 25°C. In some embodiments, the storage modulus (G') is about 300,000 Pa or less at 25°C. In some

embodiments, the storage modulus (G') is about 250,000 Pa or less at 25°C. In some embodiments, the storage modulus (G') is about 100,000 Pa or less at 25°C. In some embodiments, the storage modulus (G') is about 100,000 Pa or more at 25°C. In some embodiments, the storage modulus (G') is about 150,000 Pa or more at 25°C. In some embodiments, the storage modulus (G') is about 200,000 Pa or more at 25°C. In some embodiments, the storage modulus (G') is about 250,000 Pa or more at 25°C.

Pressure-sensitive adhesive 2 as disclosed herein can be disposed on at least a portion of a major surface 3 surface of a tape backing 4 to form an adhesive tape 1, e.g. a masking tape as depicted in the Figure. The thickness of the tape backing is not particularly limited; however, in some embodiments, the thickness of the tape backing is between about 1 μηι and 1000 μηι, or between about 25 μηι and 500 micron, or between about 50 μηι and about 100 μηι.

Suitable tape backings can be formed from a variety of thermoplastic polymers. Representative examples of suitable thermoplastic polymers include polyolefms such as polyethylene, polypropylene, polybutylene, ethylene -propylene copolymers, linear low-density polyethylene, high density polyethylene, ultrahigh density polyethylene, and the like; polyvinyl chloride, polyvinyl acetate, ethylene/acrylate copolymers, ethylene/methacrylate copolymers, ethylene/vinyl acetate copolymers, acrylonitrile/butadiene/styrene copolymers, polyurethanes, polyamides, polyamides, polyesters, polycarbonates, as well as mixtures and copolymers thereof. In some embodiments, a natural material such as paper is employed to form a suitable adhesive backing; composites or mixtures of paper and one or more thermoplastics are employed in some embodiments to form an adhesive backing suitable for use with the pressure-sensitive adhesives of the embodiments herein. In some embodiments the backing may be a creped paper backing. In some embodiments, a useful adhesive backing film includes ethylene -vinyl acetate copolymer. In particular embodiments, the tape backing may be a polyolefinic blend material chosen from those described in U.S. Patent Application Publication No. 2014-0138025 to Bartusiak, which is incorporated by reference in its entirety herein.

Adhesive tape 1 includes at least a tape backing 4 and a pressure-sensitive adhesive 2 as disclosed herein, wherein the adhesive is disposed, e.g. coated, on at least a portion of one major surface 3 of the tape backing. In some embodiments, pressure-sensitive adhesive 2 may be disposed on a major surface of tape backing 4 by disposing a pressure-sensitive adhesive precursor on the major surface and then transforming the precursor into pressure-sensitive adhesive 2. In some embodiments this may be performed by way of the precursor being a solvent mixture that is coated on the major surface and the solvent then removed so that the dried material resulting therefrom is pressure-sensitive adhesive 2. (Optionally, the material may be additionally cured, crosslinked, or the like).

In other embodiments, the disposing of pressure-sensitive adhesive 2 onto the tape backing may be a solventless process; e.g. a hot-melt coating process in which the pressure-sensitive adhesive precursor is coated while at an elevated temperature and, after being deposited, is cooled and transformed into pressure-sensitive adhesive 2. In many embodiments, this may be facilitated by curing (i.e., crosslinking) of various components of the precursor, as promoted e.g. by the application of an electron beam or like energy source as will be well understood by the ordinary artisan. In some embodiments, at least a natural rubber elastomer component of the precursor, if present, may be pre-processed e.g. in a Banbury mixer so as to bring the elastomer into a state in which it can undergo molten flow and can be mixed with the other components. In other embodiments, a continuous process may be used in which a natural rubber elastomer component of the precursor composition is processed (e.g. in a twin-screw extruder), and combined with other components of the precursor composition, in the general manner described in U.S. Reissue Patent No. RE36855, which is incorporated by reference in its entirety herein. The thickness of the resulting pressure-sensitive composition may be any desired value, e.g. ranging from about 1 μηι to about 200 microns.

Thus, in some embodiments pressure-sensitive adhesive 2 is a hot-melt coated pressure-sensitive adhesive. The ordinary artisan will appreciate that such a hot-melt coated pressure-sensitive adhesive may be distinguished from pressure-sensitive adhesives prepared by other methods (e.g., solvent coating and the like) by way of specific signatures left behind in the adhesive (e.g. the presence or absence of solvent residue, and/or other indications that may be known to the ordinary artisan.) And, in some specific embodiments, pressure-sensitive adhesive 2 is an ebeam-cured pressure-sensitive adhesive. In similar manner, an ebeam-cured adhesive may be distinguished from other adhesives (e.g. that are cured by the use of chemical crosslinking agents, or that are merely solvent-cast and dried and are not cured at all) e.g. by the presence or absence of residue from chemical initiators, by the nature of the crosslinks themselves, and so on.

In some embodiments, adhesive tape 1 may optionally include a low adhesion backsize 6 that is disposed on opposing major surface 5 of the tape backing. Any suitable low adhesion backsize may be used, chosen e.g. from those materials described in U.S. Patent Application Publication No. 2014- 0138025 to Bartusiak.

Adhesive tape 1 may be provided in any useful form generally known in the art as useful for pressure-sensitive adhesive tapes. Such forms include, without limitation, sheets, such as perforated sheets, rolls, discs, stacks, tablets, and combinations thereof. In some embodiments the adhesive articles of the embodiments herein are provided in suitable packaging including, without limitation, dispensers, bags, blister packs, boxes, and cartons. The pressure-sensitive adhesive compositions herein and adhesive tapes using such compositions may be applied to an adherend using any suitable method. One example of a useful method includes contacting the surface of the adherend with a first major side of an adhesive article, wherein said first major side includes a layer of a pressure-sensitive adhesive composition of the embodiments herein; applying finger pressure or some other static or dynamic pressure along the length of the tape or article.

In at least some embodiments, adhesive tape 1 is a masking tape, that may be applied to a portion of a surface (e.g. of an architectural coating that has already been applied to a substrate and allowed to dry) so as to mask that surface portion from being coated when an adjacent portion of the surface is coated (e.g., with another architectural coating). Such masking tapes and requirements and features thereof will be well understood by the ordinary artisan.

List of Exemplary Embodiments

Embodiment 1 is an adhesive tape comprising: a tape backing; a pressure-sensitive adhesive composition disposed on at least a portion of a first major side of the tape backing, the pressure-sensitive adhesive composition comprising at least one elastomer that is chosen from natural rubbers and synthetic rubbers and combinations thereof and that is present at from about 20 wt. % to about 50 wt. % based on the total weight of the pressure-sensitive adhesive composition, and at least one polar phenolic tackifier comprising a phenolic moiety and having a hydroxyl value of between 20 to 130 and an acid value of less than 0.5 and being present at from about 5 wt. % to about 50 wt. % based on the total weight of the pressure-sensitive adhesive composition.

Embodiment 2 is the adhesive tape of embodiment 1, wherein the at least one elastomer that is chosen from natural rubbers and synthetic rubbers and combinations thereof is present at from about 35 wt. % to about 45 wt. % based on the total weight of the pressure-sensitive adhesive composition. Embodiment 3 is the adhesive tape of any of embodiments 1 -2, wherein the synthetic rubber, if present, is chosen from the group consisting of butyl rubber, synthetic polyisoprene rubber, ethylene-propylene rubber, ethylene-propylene- diene rubber, polybutadiene rubber, polyisobutylene rubber, poly(alpha- olefin) rubber, nitrile rubber, styrene-butadiene rubber, and combinations thereof.

Embodiment 4 is the adhesive tape of any of embodiments 1-3, the polar phenolic tackifier comprising a terpene phenolic tackifier. Embodiment 5 is the adhesive tape of any of embodiments 1 -4, the polar phenolic tackifier having a hydroxyl value of between 20 to 90. Embodiment 6 is the adhesive tape of any of embodiments 1-5, the polar phenolic tackifier an acid value of less than about 0.25.

Embodiment 7 is the adhesive tape of any of embodiments 1 -6, the polar phenolic tackifier having a softening point of about 105 to about 160 degrees Celsius. Embodiment 8 is the adhesive tape of any of embodiments 1-7, the polar phenolic tackifier having a molecular weight of about 400 to about 800. Embodiment 9 is the adhesive tape of any of embodiments 1-8, wherein the polar phenolic tackifier is present at from about 10 wt. % to about 35 wt. % based on the total weight of the pressure-sensitive adhesive composition.

Embodiment 10 is the adhesive tape of any of embodiments 1 -9, wherein the pressure-sensitive adhesion composition further comprises at least one nonpolar tackifier. Embodiment 11 is the adhesive tape of embodiment 10, wherein the nonpolar tackifier is a terpene resin. Embodiment 12 is the adhesive tape of any of embodiments 10-1 1, wherein the nonpolar tackifier is present at from about 10 wt. % to about 45 wt. % based on the total weight of the pressure-sensitive adhesive composition. Embodiment 13 is the adhesive tape of any of embodiments 10-12, wherein the polar tackifier and the nonpolar tackifier in combination are present at from about 40 wt. % to about 60 wt. % based on the total weight of the pressure-sensitive adhesive composition.

Embodiment 14 is the adhesive tape of any of embodiments 1-13, wherein the pressure-sensitive adhesive composition further comprises at least one hydrocarbon block copolymer. Embodiment 15 is the adhesive tape of embodiment 14, wherein the hydrocarbon block copolymer is a styrene-isoprene block copolymer. Embodiment 16 is the adhesive tape of embodiment 15, wherein the styrene-isoprene block copolymer exhibits a multi-arm star-block copolymer architecture. Embodiment 17 is the adhesive tape of any of embodiments 14- 16, wherein the hydrocarbon block copolymer is present at from about 10 wt. % to about 30 wt. % based on the total weight of the pressure-sensitive adhesive composition.

Embodiment 18 is the adhesive tape of any of embodiments 1-17, the pressure-sensitive adhesive composition having a glass transition temperature of about -30° C to -10° C. Embodiment 19 is the adhesive tape of any of embodiments 1-18, wherein the tape backing is a paper backing and wherein the adhesive tape is a masking tape. Embodiment 20 is the adhesive tape of any of embodiments 1-18, wherein the tape backing is a polyolefinic blend and wherein the adhesive tape is a masking tape.

Embodiment 21 is the adhesive tape of any of embodiments 1-20, wherein a second major side of the tape backing comprises a low adhesion backsize disposed on at least a portion of thereof. Embodiment 22 is the adhesive tape of any of embodiments 1-21, the pressure-sensitive adhesive further comprising from about 0.01 to about 5 wt. % of an antioxidant.

Embodiment 23 is the adhesive tape of any of embodiments 1-22, wherein the pressure-sensitive adhesive composition is a hot-melt-coated pressure-sensitive adhesive composition. Embodiment 24 is the adhesive tape of any of embodiments 1-23, wherein the pressure-sensitive adhesive composition is an ebeam-cured pressure-sensitive adhesive composition.

Embodiment 25 is a method of coating a first surface portion while masking a second surface portion so that it is not coated, the method comprising: adhesively attaching a length of the adhesive tape of any of embodiments 1 -24 to the second surface portion and then applying a liquid coating mixture to at least the first surface portion.

Examples

The invention is further explained with reference to the following nonlimiting examples.

Materials

The following materials were used in the Examples as indicated below.

Table 1

Test Methods

The following test methods were used in the Examples as indicated below.

Test Adherends

Panels of Baltic birch wood sized 0.64 cm x 15.2 cm x 30.5 cm (1/4 inch x 6 inch x 12 inch), obtained from Mailand Wood Products, Centuria, WI, were painted with Behr PREMIUM PLUS

ULTRA® Primer and Paint 2 in 1 Flat Egyptian Nile (FEN) (("Behr FEN PPU" or "FEN") obtained from Behr Process Corporation of Santa Ana, CA) or Sherwin-Williams PROMAR® 200 Zero VOC, Interior Acrylic Latex White Eg-shel Paint (("Promar 200 Zero VOC") obtained from the Sherwin-Williams Company of Cleveland, OH) or Valspar Contractor Finishes 2000 Series, Interior Eggshell Latex Paint High Hide White (("Valspar Contractor 2000") obtained from The Valspar Corporation of Wheeling, IL).

Procedure for painting: a first coat of primer (Sherwin Williams PROMAR 200 Zero VOC primer was applied to the wood panel using a 0.95 cm (3/8 inch) nap paint roller, followed by air drying for at least 2 hours at ambient conditions. A coat of paint was then applied using a fresh 0.95 cm (3/8 inch) nap paint roller followed by air drying at ambient conditions for 1 -2 hours, or until dry to the touch. A second coat of paint was then applied using the same nap paint roller that was used to apply the first coat of paint (paint on roller was not allowed to dry out). The painted wood panel was allowed to air dry at ambient conditions for 7 days. The painted panel was then stored at ambient conditions until use.

180° Angle Peel Adhesion Testing

The 180° angle peel adhesion of the example masking tapes was measured using the procedure generally described in PSTC-101, Method A, with the following modifications. A 20.3 cm (8 inches) long strip of the example tape was gently applied by hand to the painted surface of the wood panel. The painted surface was not wiped prior to peel testing. A 2.04 kg (4.5 pound), 4.45 cm (1.75 inches) wide, calibrated rubber roller was centered horizontally relative to the width of the tape. The roller was then passed lengthwise back and forth by hand two times, for a total of two individual passes over the tape at a rate of approximately 30.5 cm (12 inches) per minute for a total of two passes. The tape strips were peeled from the panel using an IMASS peel tester (Model No. SP-2100, available from IMASS Inc., Accord, MA) using a 2 second delay and a 5 second runtime at a speed of 229 cm/minute (90

inches/minute). The force required to effect peel was measured and recorded. For immediate adhesion or "zero dwell" samples, the tape strip was applied to the adherend in the conditions stated in the Tables and peeled within five minutes. Similarly, the adhesion for samples labeled "5 day dwell" was measured by applying the tape to the adherend and waiting 5 days before testing the peel adhesion. The values represent an average. Typically three replicates of each tape sample were tested. Approximately 61 cm (2 feet) of tape was removed from the tape roll between each test sample.

Pressure Sensitive Adhesive Formulations

Examples were prepared using a compounding and coating apparatus for processing natural and synthetic non-thermoplastic elastomer hot melt based PSA generally similar to that described in U.S. Patent. No. Re. 36,855 (Reissue of U.S. Patent. No. 5,539,033, Bredahl et al.). Example 1

A 5.1 cm (2 inch) diameter BON OT single-stage extruder (The Bonnot Company, Uniontown, Ohio) fitted with a 3.0 cubic centimeters/revolution (cc/rev) ZENITH gear pump (Zenith Pumps, Monroe, NC) was used to feed a CV60 natural rubber into Barrel Zone 1 of a 40 mm (15.7 inch ) diameter fully intermeshing co-rotating twin screw extruder (TSE) having conveying and kneading sections and a L/D of 48: 1 (Steer MEGA Series Model MEGA 40, Steer America, Uniontown, OH), at a rate of 58.85 grams/minute. KRATON 1340 was fed into Barrel Zone 1 of the twin scre extruder at a rate of 25.22 grams/minute using a K-TRON loss-in- weight feeder (Coperion K-TRON, Sewell, N J). The K-TRON loss-in-weight feeder is a constant rate feeder that controls rate of material delivered to the twin screw extruder by continuously monitoring the weight of the material in the feed hopper. Q U IN TONE Kl 00 tackityiag resin was fed into Barrel Zone 1 of the twin scre extruder at a rate of 8.41 grams/minute using a K-TRON loss-in-weight feeder. Barrel Zone 1 was set at a temperature of 75 °F (24 °C). Barrel Zone 2 was set at a temperature of 150 °F (66 °C). SYLVARES TP 96 taekifying resin was fed into Barrel Zone 3 of the twin screw extruder at a rate of 33.63 grams/minute using a K-TRON loss-in-weight feeder. Barrel Zone 3 was set at a temperature of 150 °F (66 °C). Barrel Zone 4 was set at a temperature of 150 °F (66 °C). QUINTONE K100 was fed into Barrel Zone 5 of the twin screw extruder using a K- TRON loss-in-weight feeder at a rate of 25.22 grams/minute. Barrel Zone 5 was set at a temperature of 250 °F (121 °C). Barrel Zone 6 was set at a temperature of 250 °F (121 °C). IRGANOX 1520L antioxidant was fed into Barrel Zone 7 of the twin screw extruder at a rate of 2.27 grams/minute using a syringe pump. Barrel Zone 7 was set a temperature of 250 °F (121 °C). Barrel Zone 8 was set at a temperature of 250 °F ( 121 °C). The adhesive was transported through the remaining Barrel Zones of the extruder, which were set at a temperature of 2.50 °F (121 °C). The twin screw speed was maintained at 325 rpm. The adhesive was delivered to an extrusion die using a 5.0 cc/rev ZENITH gear pump that was set at 1 1.8 rpm to deliver a theoretical mass throughput of 59 grams/minute at a density of 1 gram/cc. The extrusion die deposited a 15.2 em (6 inch) wide coating of the adhesive onto a 17.8 cm (7 inch) wide crepe paper masking tape backing that passed around a coating roll that was set at a temperature of 70° F (21 °C). The crepe paper had polymer saturant absorbed or impregnated into the backing and was coated on one side first with a barrier layer and then with a lo adhesion backsize (LAB) so that the tape could be dispensed in roil form (similar to the backing used for SCOTCH Masking Tape #2020 sold by 3M Company, St. Paul, MN). The line speed was maintained at about 10. 4 meters/minute (34 feet/minute) to result in an average coating weight of 38 grams/meter² (9 grains per twenty 24 square inches). The adhesive coating was electron beam cured in-line at an accelerating voltage of 125 kV and a 4 Mrad dose. The adhesive tape was then wound into roll form and slit to 2.54 cm (1 inch) wide rolls that were used for 180° angle peel adhesion testing using the procedures as described above.

Examples 2 - 24 and Comparative Example C 1

Examples 2 - 24 and Comparative Example CI were prepared in a manner similar to that described for Example 1 , adjusting the using extrusion parameters to result in the compositions provided in Tables 2 and 3. The values in Tables 2 and 3 are in weight percent based on the total solids of the adhesive composition.

Table 2 - Pressure Sensitive Adhesive Compositions'

Antioxidant (IRGANOX® 1520L) was added at 1.5 weight percent on top of total pressure sensitive adhesive solids excluding the antioxidant contribution.

Table 3 - Pressure Sensitive Adhesive Compositions'¹

Antioxidant (IRGANOX® 1520L) was added at 1.5 weight percent on top of total pressure sensitive adhesive solids excluding the antioxidant contribution.

The example masking tapes were then evaluated for 180° angle peel adhesion strength on various adlierends. The data are presented in Tables 4 and 5. Table 4

Immediate Adhesion to Adherends at "CTH" Conditions (72°F/50 % Relative Humidity) and 79 °F/ 4 % Relative Humidity

Table 5

5 Day Dwell Adhesion to Adherends "CTH" (72°F/50 % Relative Humidity) and 79 °F/74 % Relative

Humidity

The foregoing Examples have been provided for clarity of understanding only, and no unnecessary limitations are to be understood therefrom. The tests and test results described in the Examples are intended to be illustrative rather than predictive, and variations in the testing procedure can be expected to yield different results. All quantitative values in the Examples are understood to be approximate in view of the commonly known tolerances involved in the procedures used.

It will be apparent to those skilled in the art that the specific exemplary elements, structures, features, details, configurations, etc., that are disclosed herein can be modified and/or combined in numerous embodiments. All such variations and combinations are contemplated by the inventor as being within the bounds of the conceived invention, not merely those representative designs that were chosen to serve as exemplary illustrations. Thus, the scope of the present invention should not be limited to the specific illustrative structures described herein, but rather extends at least to the structures described by the language of the claims, and the equivalents of those structures. Any of the elements that are positively recited in this specification as alternatives may be explicitly included in the claims or excluded from the claims, in any combination as desired. Any of the elements or combinations of elements that are recited in this specification in open-ended language (e.g., comprise and derivatives thereof), are considered to additionally be recited in closed-ended language (e.g., consist and derivatives thereof) and in partially closed-ended language (e.g., consist essentially, and derivatives thereof). To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document incorporated by reference herein, this specification as written will control.

Claims

What is claimed is:

1. An adhesive tape comprising:

a tape backing;

a pressure-sensitive adhesive composition disposed on at least a portion of a first major side of the tape backing, the pressure-sensitive adhesive composition comprising

at least one elastomer that is chosen from natural rubbers and synthetic rubbers and combinations thereof and that is present at from about 20 wt. % to about 60 wt. % based on the total weight of the pressure-sensitive adhesive composition, and

at least one polar phenolic tackifier comprising a phenolic moiety and having a hydroxyl value of between 20 to 130 and an acid value of less than 0.5 and being present at from about 5 wt. % to about 50 wt. % based on the total weight of the pressure-sensitive adhesive composition.

2. The adhesive tape of claim 1, wherein the at least one elastomer that is chosen from natural rubbers and synthetic rubbers and combinations thereof is present at from about 45 wt. % to about 55 wt. % based on the total weight of the pressure-sensitive adhesive composition.

3. The adhesive tape of claim 1, wherein the synthetic rubber, if present, is chosen from the group consisting of butyl rubber, synthetic polyisoprene rubber, ethylene-propylene rubber, ethylene-propylene- diene rubber, polybutadiene rubber, polyisobutylene rubber, poly(alpha-olefin) rubber, nitrile rubber, styrene -butadiene rubber, and combinations thereof.

4. The adhesive tape of claim 1, the polar phenolic tackifier comprising a terpene phenolic tackifier.

5. The adhesive tape of claim 1, the polar phenolic tackifier having a hydroxyl value of between 20 to 90.

6. The adhesive tape of claim 1, the polar phenolic tackifier an acid value of less than about 0.25.

7. The adhesive tape of claim 1, the polar phenolic tackifier having a softening point of about 105 to about 160 degrees Celsius.

8. The adhesive tape of claim 1, the polar phenolic tackifier having a molecular weight of about 400 to about 800.

9. The adhesive tape of claim 1, wherein the polar phenolic tackifier is present at from about 10 wt.

% to about 35 wt. % based on the total weight of the pressure-sensitive adhesive composition.

10. The adhesive tape of claim 1, wherein the pressure-sensitive adhesion composition further comprises at least one nonpolar tackifier.

1 1. The adhesive tape of claim 10, wherein the nonpolar tackifier is a terpene resin.

12. The adhesive tape of claim 10, wherein the nonpolar tackifier is present at from about 10 wt. % to about 45 wt. % based on the total weight of the pressure-sensitive adhesive composition.

13. The adhesive tape of claim 10, wherein the polar tackifier and the nonpolar tackifier in combination are present at from about 40 wt. % to about 60 wt. % based on the total weight of the pressure-sensitive adhesive composition.

14. The adhesive tape of claim 1, wherein the pressure-sensitive adhesive composition further comprises at least one hydrocarbon block copolymer.

15. The adhesive tape of claim 14, wherein the hydrocarbon block copolymer is a styrene-isoprene block copolymer.

16. The adhesive tape of claim 15, wherein the styrene-isoprene block copolymer exhibits a multi- arm star-block copolymer architecture.

17. The adhesive tape of claim 14, wherein the hydrocarbon block copolymer is present at from about 10 wt. % to about 30 wt. % based on the total weight of the pressure-sensitive adhesive composition.

18. The adhesive tape of claim 1, the pressure-sensitive adhesive composition having a glass transition temperature of about -30° C to -10° C.

19. The adhesive tape of claim 1, wherein the tape backing is a paper backing and wherein the adhesive tape is a masking tape.

20. The adhesive tape of claim 1, wherein the tape backing is a polyolefinic blend and wherein the adhesive tape is a masking tape.

21. The adhesive tape of claim 1, wherein a second major side of the tape backing comprises a low adhesion backsize disposed on at least a portion of thereof.

22. The adhesive tape of claim 1, the pressure-sensitive adhesive further comprising from about 0.01 to about 5 wt. % of an antioxidant.

23. The adhesive tape of claim 1, wherein the pressure-sensitive adhesive composition is a hot-melt- coated pressure-sensitive adhesive composition.

24. The adhesive tape of claim 23, wherein the pressure-sensitive adhesive composition is an ebeam- cured pressure-sensitive adhesive composition.

25. A method of coating a first surface portion while masking a second surface portion so that it is not coated, the method comprising:

adhesively attaching a length of the adhesive tape of claim 1 to the second surface portion and then applying a liquid coating mixture to at least the first surface portion.