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Title:
PRESSURE SENSITIVE ADHESIVE BASED ON HYDROGENATED STYRENE BLOCK COPOLYMER
Document Type and Number:
WIPO Patent Application WO/2003/044087
Kind Code:
A2
Abstract:
An adhesive composition is provided comprising: (a) an A-B-A block copolymer with an A block that is non-elastomeric comprised of homopolymers and copolymers of vinyl monomers, and a B block that is elastomeric and is substantially hydrogenated, (b) a tackifying resin, and (c) optionally, a plasticizer in an amount of 20 % by weight or less, the A-B-A block copolymer being present in the composition in an amount ranging from 15-60 % by weight, and the tackifying resin being present in the composition in an amount ranging from 40-85 % by weight, each being based on the total weight of the composition, the block copolymer including a graft moiety in an amount within the range of from 0.5 to 5.0 % by weight, wherein the graft moiety is selected from the group consisting of ethylenically unsaturated carboxylic acids, ethylenically unsaturated carboxylic acid anhydrides, and derivatives thereof.

Inventors:
CARRIG, Thomas (328 Glen Rock Road, Glen Rock, PA, 17327, US)
Application Number:
US2002/037006
Publication Date:
May 30, 2003
Filing Date:
November 19, 2002
Export Citation:
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Assignee:
ADHESIVES RESEARCH, INC. (P.O. Box 100, Glen Rock, PA, 17327, US)
CARRIG, Thomas (328 Glen Rock Road, Glen Rock, PA, 17327, US)
International Classes:
C09J153/00; C09J153/02; (IPC1-7): C08L53/00
Foreign References:
US6214476B12001-04-10
Attorney, Agent or Firm:
HELLWEGE, James, W. (Birch, Stewart Kolasch & Birch, LLP,P.O. Box 74, Falls Church VA, 22040-0747, US)
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Claims:
WHAT IS CLAIMED IS: 1. An adhesive composition comprising: (a) an A-B-A block copolymer with an A block that is non-elastomeric comprised of homopolymers and copolymers of vinyl monomers, and a B block that is elastomeric and is substantially hydrogenated, (b) a tackifying resin, and (c) optionally, a plasticizer in an amount of 20 % by weight or less, said A-B-A block copolymer being present in said composition in an amount ranging from 15-60 % by weight, and said tackifying resin being present in said composition in an amount ranging from 40-85 % by weight, each being based on the total weight of the composition, said block copolymer including a graft moiety in an amount within the range of from 0.5 to 5.0 % by weight, wherein said graft moiety is selected from the group consisting of ethylenically unsaturated carboxylic acids, ethylenically unsaturated carboxylic acid anhydrides, and derivatives thereof.
2. The composition of claim 1, wherein said A-B-A block copolymer is present in an amount greater than 20 % by weight, based on the total weight of the composition.
3. The composition of claim 1, wherein said A-B-A block copolymer is present in an amount of from 25-60% by weight, based on the total weight of the composition.
4. The composition of claim 1, wherein said A-B-A block copolymer is a styrene- ethylene/butylene-styrene block polymer.
5. The composition of claim 1, wherein the A-B-A block copolymer is a styrene- ethylene/propylene-styrene block polymer.
6. The composition of claim 1, wherein said tackifying resin is a hydrogenated rosin ester.
7. The composition of claim 1, wherein said tackifying resin is a polyterpene derived from a-pinene, p-pinene or d-limonene.
8. The composition of claim 1, where the tackifying resin is a hydrogenated hydrocarbon.
9. The composition of claim 1, further containing a polyphenylene ether resin in an amount ranging from 1-8% by weight, based on the total weight of the composition.
10. The composition of claim 1, further containing a plasticizer in an amount of up to 20% by weight.
11. The composition of claim 1, further containing an inert material selected from the group consisting of pigments, fibers, solid and hollow spheres, clays, silica, and talc.
12. The composition of claim 6, further containing a crosslinking agent capable of reacting with the grafted functional groups on the block copolymer.
13. The composition of claim 1, comprising multiple tackifier resins, one of said tackifier resins having a softening point of less than 85°C while another of said tackifier resins having a softening point of greater than 85°C.
14. The composition of claim 1, comprising at least two block copolymers, with one of said block copolymer containing less than or equal to 25% by weight monoalkenyl arene, with said second block copolymer containing greater than 25% by weight monoalkenyl arene.
15. The composition of claim 1, further comprising a compatible thermoplastic polymer in an amount of up to 25% by weight.
16. The composition of claim 1, further comprising an incompatible thermoplastic polymer in an amount of up to 25% by weight. 17. The composition of claim 1, wherein said A block is present in said composition in an amount of at least 25 % by weight, based on the total weight of the composition.
18. An adhesive extrudate comprised of the composition of claim 1.
Description:

"Pressure Sensitive Adhesive Based on Hydrogenated Styrene Block Copolymer" Background of the Present Invention The present invention is directed to a novel adhesive composition which exhibits highly desirable properties.

A number of adhesive compositions are known based on rubber polymer- containing compositions, optionally together with one or more of a tackifier or plasticizer. See, for example, U. S. Patent Nos. 5,093, 422; 5,591, 792; 5,703, 162; 5,719, 226; 5,741, 840; 5,912, 295; 5,932, 648; 5,939, 483; 6,025, 071; 6,103, 814; 6,162, 868; 6,172, 156; 6,232, 391; 6,274, 666; 6,277, 488; 6,197, 419; 4,136, 699; 5,459, 193; 5,863, 977; RE 36,757 ; 5,618, 883; 4,286, 077; and 5,656, 687.

The disclosed compositions are primarily hot-melt type adhesive compositions, which are formulated to enable the composition to be used as a hot- melt. However, the formulations required to permit the satisfactory use of the compositions as a hot-melt also serve to diminish the adhesive properties of the compositions. For example, significant amounts of plasticizers are generally <BR> <BR> present in hot-melt compositions in amounts (i. e. , at least 10% by weight) which serve to diminish the adhesive properties of the composition. As a result, the high performance properties of the adhesive suffer.

It is thus desirable to provide an adhesive composition based on rubber polymers which exhibits high performance properties including temperature resistance as well as high shear and peel.

It has now been found that rubber polymer-based adhesive compositions can be provided which need not be used in the form of a hot-melt. In this case, hot melt application is considered to be two independent steps of compounding the adhesive in one step, followed by application of the compounded adhesive to release liners or substrates in a second step. Each step utilizes different process equipment. Typically, these two step operations impose limitations on adhesive melt rheology to facilitate efficient flow in the application step. In the absence of melt rheology limitations, formulation latitude is expanded which results in enhanced physical properties being attained.

The benefits of the present invention are many. As opposed to typical"high bond"adhesives, the present invention exhibits high peel adhesion values when used on adherands with such varied surface energy as stainless steel, aluminum, glass, PVC, high density polyethylene, polypropylene and wood. In connection with higher surface energy substrates such as glass and stainless steel, the adhesion exhibited is so great that the backing of the adhesive tape comprised of the adhesive of the present invention will fail prior to the adhesive. Peel adhesion values are measured in the range from 3 #/in up to in excess of 60 #/in, depending upon ingredients. Peel adhesion values in excess of 15#/in are extremely unusual in the art, even in cases where the adhesive exhibits poor cohesive strength as seen through low holding power or shear resistance. In conjunction with the high peel values of the present invention, the adhesive has also been shown to exhibit high shear strength on the order of 10,000 minutes static shear with a 1/2 x Y2 inch sample under 500 gm and 1000 gm loads when bonded to stainless steel. This balance of properties makes this adhesive composition useful for some applications that previously required a liquid"structural"adhesive.

Common to the prior art hot melt adhesive compositions based on block copolymers with substantially hydrogenated midblock is a focus on maintaining low melt viscosity for easy application. The benefits provided by these materials include high cohesive strength imparted at low levels (&lt;20% wt. ) and stability against degradation under melt processing relative to adhesive compositions based on block copolymers with unsaturated midblocks (isoprene or butadiene).

The present invention is not driven by low melt viscosity and therefore allows for wider formulation windows. In contrast to the teachings of the prior art, the present invention provides extremely high peel adhesion in conjunction with high cohesive strength using relative high levels of block copolymers of substantially hydrogenated midblock.

Another advantage of the present invention is the ability to formulate a thick adhesive composition that is substantially hydrogenated. This feature provides a system that is resistant to degradation by thermal, oxidative or ultraviolet radiation exposure. It is therefore of benefit for applications that must survive such exposures. U. S. Patent No. 4,286, 077 discloses weather resistant adhesive compositions based on block copolymers with a substantially hydrogenated midblock. Specific to that invention is such a block copolymer with monoalkenyl arene end blocks at levels of 7-22% by weight of the multiblock polymer. Further, the invention teaches that multiblock polymers with higher monoalkenyl arene endblock content requires a level of plasticizer to impart good adhesive properties with the result that cohesive properties are lost. U. S. Patent No. 6,197, 419 discloses the weather resistant attributes of the block copolymers of substantially hydrogenated midblock. The disclosed invention uses such polymers in conjunction with block copolymers of unsaturated midblocks. The unsaturated block copolymer is employed to impart good adhesive properties while the substantially hydrogenated block copolymer is used to provide enhanced holding power and weather resistance. By contrast, the present invention uses primarily or exclusively substantially hydrogenated block copolymers and places no limitation upon monoalkenyl arene content of such block copolymers.

It is well known to those skilled in the art that adhesive thickness (or coating weight) plays a critical role in adhesion values obtained. As thickness increases, the peel adhesion value also increases. In contrast, the holding power will decrease as a function of increasing adhesive thickness. The effects of increasing thickness upon peel adhesion typically plateau at a maximum peel adhesion when thickness is in the range of 0. 010"-0. 015"thickness. The adhesive of the present invention follows these same trends, and shows outstanding adhesion values at thickness of less than. 005". However the level of adhesion obtained in combination with good holding power are novel to the art at a thickness greater than 0.005".

Advantageously, while the adhesive of the present invention may be cured, the adhesive functions effectively even in the absence of curing. Typically, prior art adhesives require a curing or activation step to achieve high strength "structural"adhesion. Such activation generally comprises thermal or radiation activation (UV or electron beam activation). This is generally found to be a disadvantage as the backing material must be selected to be compatible with the activating energy which limits the applicability of these products.

The adhesive of the present invention desirably finds application in the areas of construction, automotive, marine and other areas where strong adhesive bonds or gap filling features are desired.

Summary of the Present Invention The present invention is directed to an adhesive composition comprising: (a) an A-B-A block copolymer with an A block that is non-elastomeric comprised of homopolymers and copolymers of vinyl monomers, and a B block that is elastomeric and is substantially hydrogenated, (b) a tackifying resin, and (c) optionally, a plasticizer in an amount of 20 % by weight or less, said A-B-A block copolymer being present in said composition in an amount ranging from 15-60% by weight and preferably containing said A block in an amount of at least 25 % by weight, and said tackifying resin being present in said composition in an amount ranging from 40-85 % by weight, each being based on the total weight of the composition, said block copolymer comprising a graft moiety selected from the group consisting of ethylenically unsaturated carboxylic acids, ethylenically unsaturated carboxylic acid anhydrides, and derivatives thereof.

In yet another embodiment of the present invention, the adhesive composition is in the form of an extrudate which may be used to adhere two surfaces together by placing the extrudate between and in contact with both surfaces to be bonded together, optionally with application of elevated temperature and/or pressure.

Detailed Description of the Present Invention The block copolymer used in the adhesive of the present invention may be selected from a variety of A-B-A block copolymers. In the block copolymer, the A block is a non-elastomeric block comprised of homopolymers or copolymers of vinyl monomers such as vinyl arenes, vinyl pyridines, vinyl halides and vinyl carboxylates, as well as acrylic monomers such as acrylonitrile, methacrylonitrile, esters of acrylic acids, etc. The A block may also comprise monovinyl aromatic hydrocarbons including styrene, vinyl toluene, vinyl xylene, ethyl vinyl benzene as well as dicyclic monovinyl compounds such as vinyl naphthalenes and the like.

Other non-elastomeric polymer A blocks may be derived from alpha olefins, alkylene oxides, acetals, urethanes, etc.

Polystyrene and its analogs and homologs are preferred as the A block of the block copolymer. Exemplary analogs and homologs include alpha-methyl styrene, t-butyl styrene, 3-methyl styrene, 4-n-propylstyrene, 4-p-propylstyrene, 1- vinylnaphthalene, 2-vinylnaphthalene and mixtures thereof.

The B block is an elastomeric block component which is preferably at least partially and most preferably at least substantially hydrogenated. Exemplary B blocks include but are not limited to polybutadiene, poly (ethylene-butylene), polyisoprene, poly (ethylene/propylene), etc.

The preferred block copolymer for use in the present invention is an styrene-ethylene/butylene-styrene (SEBS) block copolymer.

The content of the A block in the block copolymer generally ranges from about 10 to 45% by weight based on the total weight of the block copolymer, and preferably at least 25 % by weight, while the content of the B block in the block copolymer generally ranges from about 55 to 90% by weight.

The block copolymer includes a graft moiety selected from the group consisting of ethylenically unsaturated carboxylic acids, ethylenically unsaturated carboxylic acid anhydrides, and derivatives thereof. Exemplary unsaturated carboxylic acid and anhydrides thereof include but are not limited to mono-, di-or polycarboxylic acids such as (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, itaconic anhydride, maleic anhydride and substituted maleic anhydride, such as dimethyl maleic anhydride or citrontonic anhydride, nadic anhydride, nadic methyl anhydride, tetrahydrophthalic anhydride, etc. Maleic anhydride is particularly preferred as the graft moiety. Exemplary derivatives of the above include but are not limited to salts, imides, amides, and esters of the unsaturated carboxylic acids. Examples of such derivatives include mono-or disodium maleate, acrylamide, maleimide, glycidyl methacrylate and dimethyl fumarate.

Further exemplary derivatives of maleic anhydride include but are not limited to mono-esters of maleic anhydride or maleic acid with alcohols (i. e., monomaleates), corresponding diesters (dimaleates), amides obtained by amidation of maleic anhydride or maleic acid with ammonia or an amine (maleamides) and the corresponding imides (maleimides). The preferred graft moiety is maleic anhydride.

The amount of graft moiety which may be present on the block copolymer is not critical. It is believed that the presence of the graft moiety in an amount ranging from about 0.5 to 5.0 wt. % based on the weight of the block copolymer is satisfactory. However, it may be advisable to employ higher amounts of the graft moiety if deemed desirable.

Maleic anhydride grafted styrene-ethylene-butylene-styrene triblock polymers are disclosed in U. S. Patent No. 5,656, 687 and 6,093, 768, herein incorporated by reference. Such graft block copolymers are also commercially available under the trademark KRATON from KRATON Polymers LLC as KRATON FG1901X and KRATON FG1924X. Grafted polyisoprene polymers are disclosed in U. S. Patent No. 4,204, 046. Grafted polyolefin polymers are disclosed in U. S. Patent No. 6,228, 948. U. S. Patent No. 5,618, 883 discloses maleated ethylene-propylene diene polymers.

The block copolymer is generally present in the adhesive composition of the present invention in an amount of about 15 to 60 wt. %, based on the total weight of the composition. A combination of block copolymers may be employed to tailor the adhesive composition properties for specific attributes, the total amount of which is also about 15 to 60% wt. %. Preferably, the block copolymer is present in an amount of greater than 20% by wt. , and more preferably from 25- 60 % by wt.

A variety of tackifiers may be employed, with the tackifier being chosen for suitability depending upon whether it is deemed desirable for the tackifier to be compatible with the end blocks of the block copolymer or the midblocks, or whether a balance of compatibility properties is desired. Also, it may be useful for the tackifier to be hydrogenated in the event that the block copolymer is substantially hydrogenated in order to enhance the compatibility of the tackifier with the block copolymer. That is, it is preferred for at least 50%, and most preferably at least 80% of the unsaturated groups in the tackifier to be hydrogenated.

More specifically, exemplary tackifiers include but are not limited to natural and modified rosins (such as gum rosin, wood rosin, tall oil rosin, distilled rosin, hydrogenated rosin, dimerized rosin and polymerized rosin), glycerol and pentaerythritol esters of natural and modified rosins (such as glycerol ester of wood rosin, glycerol ester of hydrogenated rosin, glycerol ester of polymerized rosin, pentaerythritol ester of hydrogenated rosin, and phenolic modified pentaerythritol ester of rosin), hydrocarbon tackifier resins, aromatic hydrocarbon resins, aliphatic hydrocarbon resins (such as polymerization product of monomers comprised mainly of olefins and diolefins and hydrogenated aliphatic petroleum hydrocarbon resins), polyterpene resins (based on alpha pinene, beta pinene or d- limonen), modified terpenes (such as styrene/terpene, alpha methyl styrene/terpene, bicyclic monoterpene, hydrogenated polyterpenes, product of bicyclic terpene and phenol), alicyclic hydrocarbon resins, coumarone-indene resins, etc.

Desirably, the tackifier which is employed exhibits a softening point within the range of from about 60 to 150 °C. as determined by ASTM method E28-58 T.

The tackifier is generally present in the adhesive composition in an amount ranging from about 40 to 85 wt. % based on the weight of the adhesive composition. Of course, the tackifier is ultimately present in an amount effective to enable the composition to exhibit the desired pressure sensitive adhesive properties. The use of a tackifier which is substantially saturated will reduce the possibility that the combination of the tackifier with the block copolymer will be detrimental to the melt viscosity of the composition. Mixtures of the above tackifiers may also be employed as found desirable or advantageous. In particular, it is found that the use of at least two tackifier resins, the first with softening point below about 85°C and the second with softening point of greater than about 85°C, is of benefit. The two different tackifiers may be of the same or different chemistry, provided that they are compatible.

The adhesive composition may contain additional components including but not limited to plasticizers, fillers, antioxidants, crosslinkers, wood or cellulose fibers, thermoplastic polymers (such as hydroxypropyl cellulose, polyamides, etc.), fillers (such as thermal or electrical conductive fillers, clays, talc, solid spheres, <BR> <BR> silica, carbon, synthetic or natural fibers, dyes, pigments, etc. ), stabilizers (thermal,<BR> oxidative, UV, hydrolytic, etc. ), etc.

Exemplary stabilizers or antioxidants include those known to one of ordinary skill in the art such as hindered phenols either alone or in combination with a secondary antioxidant such as phosphite antioxidants.

Exemplary crosslinking agents include those known to one of ordinary skill in the art including but not limited to metallic, amine-type, epoxy-type, glycol- type, silane-type and isocyanate-type crosslinking agents. For example, in a paper titled"Crosslinking of Acid-Funtional Styrenic Block Polymers with Aluminum Acetylacetonate"by St. Clair of Kraton Polymers (TAPPI Hot melt Conference, Hilton head, SC; June 2001) the author demonstrates the relative efficacy of various metal chelates in crosslinking the base polymers of the present invention.

In terms of processing and performance, the aluminum acetylacetonate was found to be the most useful. Relative to the present invention, it is noted that the maximum peel adhesion cited in this paper (including uncrosslinked adhesives) is about 5.3 #/in, and static shear values of less than 60 minutes (25mm x 25 mm; 1 Kg). However the same crosslinking approach, in which SAFT increased 20-30°C as a result of crosslinking, can be employed to the present invention.

As an alternative to crosslinking as a means to increase the heat resistance of the present invention, one can also use additives that chemically associate with the styrenic end blocks of the base polymer. Examples of such additives are <BR> <BR> tackifiers based on styrene monomer (Endex 150 sold by Hercules, Inc. ), styrene modified terpenes (Sylvares TP-2040 sold by Arizona Chemical or SP-553 sold by Schenectady International), and polyphenylene ethers (SA-120 sold by General Electric Plastics). These end block associating resins are known in the art as means to increase heat resistance (see US Patent No. 6,277, 488), but they are also known to have a detrimental effect on peel adhesion and tack of a pressure sensitive adhesive. The adhesive composition of the present invention demonstrates the same effect. However, the peel adhesion of the composition prior to adding the end block reinforcing resin is so high that any decrease of peel adhesion is compensated for and a high performance product is still obtained.

Plasticizers which may be employed are those which are conventionally employed in conjunction with polymeric compositions. Such plasticizers are typically fluid so as to provide additional fluidity to the adhesive composition as well as to enhance the adhesive tack of the adhesive composition. Exemplary plasticizers include but are not limited to oil and liquid elastomers which flow at ambient temperature and are compatible with the block copolymer, such as mineral and petroleum based hydrocarbon oils, polybutene, liquid elastomers, functionalized oils such as glyceryl trihydroxyoleate or other fatty oils. The contemplated plasticizers are desirably low in aromatic content and are paraffinic or napthenic in character. Compatible tackifier chemistries that are liquid at room temperature also are considered useful plasticizers. Examples include but are not limited to C5 petroleum hydrocarbons, methyl ester of rosin, hydrogenated hydrocarbons and polyterpenes.

The plasticizer, if present, will generally be present in an amount of up to about 20 % by weight, based on the total weight of the adhesive composition, more preferably less than 10 % by weight, such that a balance of properties of the invention is maintained.

The adhesive composition of the present invention may also include blowing agents or hollow expandable or non-expandable microspheres to decrease the density of the extruded adhesive composition either by action of the blowing agents or by the presence of the hollow microspheres.

The block copolymer described above may also be combined with one or more compatible homo-, co-or block polymers compatible with the block copolymer. For example, it may be an advantage to incorporate a polystyrene block copolymer (grafted or non-grafted) which block copolymer does not have an elastomeric midblock. The presence of elastomeric A-B diblocks is also appropriate, with such diblocks being present in an amount of up to 30% by wt.

Such diblocks enhance adhesion while inhibiting shear strength. The presence of increased amounts of styrene in the adhesive composition will increase shear strength while inhibiting adhesion. Preferably, the block copolymer having the elastomeric midblock portion will comprise from about 25 to 100% by weight of the total block copolymers present in the composition. However, the ratio of such block copolymers is not critical, and may be modified in a manner sufficient to attain the desired balance of, for example, shear and adhesion.

The respective components can be combined by any conventional means.

Provided that all components of a particular formulation are soluble in the same solvent or solvent blend, the adhesive composition can be prepared as a solution, and then coated and dried by means known to those skilled in the art. A practical limitation of this method is the ability to attain a dried adhesive deposition of 0. 005" or more due to solvent evaporation at the surface of the coating prior to bulk evaporation. This method typically will yield a coating with high residual solvent content as well as entrapped solvent bubbles.

The preferred method of preparation is melt processing as 100% solids. For example, the components can be combined by continuous blending of the components in the melt at a suitable temperature in a twin screw extruder whereby a homogeneous blend is obtained. Alternatively, batch mixing of the components as a melt in a heated vessel such as a sigma blade mixer is also appropriate. Once the components are melt mixed to a uniform adhesive composition, the discharged mix can be immediately applied to a substrate (including release liners) to the desired shape and thickness. Coating techniques are known to those skilled in the art such as a heat die, heated rolls, etc. , which apply the adhesive composition to a release liner or backing substrate, typically in the form of roll. Melt processing is preferred as it is shown that relatively thick coatings (greater than 0. 005" and preferably from 0.005-0. 080" thickness) of the adhesive composition can be prepared without the need for evaporating solvents and thereby providing a coating free of defects.

The adhesive composition provides novel utility as a strong adhesive that can fill gaps, dampen vibration, act as a barrier, etc. , in applications that traditionally apply a cure-in-place sealant or caulk. As stated previously, the adhesive of the present invention requires no cure time. Therefore assemblies bonded with the adhesive composition of the present invention can be handled and further processed within minutes of forming the bond. It is well known that caulks and sealants require a much longer time to cure from a liquid or semi-solid before the assembled part can be handled. Such prior art cure times are typically recommended as hours, or even days.

The present invention will be further described in conjunction with the following Examples.

Examples The following examples demonstrate the high performance features of the present invention. Examples 1-9 and 12-15 illustrate the effect of the presence of styrene, maleic anhydride graft and diblock content on the various properties of the adhesive composition. Examples 10-12 additionally demonstrate the benefit of utilizing the high styrene content containing hydrogenated block copolymer.

Three block copolymers are employed at various ratios in these examples as shown in Table 1. KRATON FG1924X (KRATON Polymers, LLC) is a maleic anhydride SEBS copolymer having about 13 wt. % of styrene, about 30 wt. % styrene-ethylene/butylene diblock, and about 1 wt. % maleic anhydride graft.

KRATON FG1901X is also a maleic anhydride grafted SEBS block copolymer with about 30% wt. styrene, no diblock content, and about 2% wt. maleic anhydride. KRATON G1652 is a SEBS block copolymer with no maleic anhydride graft, 30% styrene content and no diblock.

The tackifiers represent a variety of chemistry. Resin H (Resinas Sinteticas) is a hydrogenated rosin with a softening point of about 70 °C and a <BR> <BR> minimum acid number of 158. Foral 105 (Hercules, Inc. ) is a pentaerithrytol ester of hydrogenated rosin with a softening point of about 105°C and an acid number in the range of 6-10. Sylvares TR-1085 (Arizona Chemical) is a polyterpene resin based on p-pinene with a softening point of about 85°C and an acid number of less than 1. Sylavrez TR-1100 (Arizona Chemical) is a polyterpene resin based on ß- pinene with a softening point of about 100°C and an acid number of less than 1.

Escorez 5380 (Exxon Mobil) is a hydrogenated hydrocarbon resin with a softening point of about 80°C and an acid number of less than 1. Wingtack 10 (Goodyear Tire & Rubber) is an aliphatic 5 petroleum hydrocarbon that is liquid at room temperature. Indopol H-1900 is a polybutene (BP Amoco). Hercolyn D (Pinova division of Hercules, Inc. ) is a methyl ester of rosin, also a liquid at room<BR> temperature. Cellolyn 21 (Pinova division of Hercules, Inc. ) is a phthalate ester of technical hydroabletyl alcohol with a softening point of 60-70 °C and an acid number of at least 10. Escorez 1580 (ExxonMobil Chemical) is an aliphatic hydrocarbon resin with a softening point of about 80 °C.

Table 1 Component % wt. Ex. I Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. I 1 Ex. 12 Ex. 13 Ex. 14 Ex. 15 40 0 40 0 30 0 0 30 0 13 23 33 0 0 0 KRATON X 0 0 0 0 0 30 0 0 0 20 10 0 25 30 40 KRATON FG1924X 0 40 0 40 0 0 30 0 30 0 0 0 0 0 0 KRATON G 1652 60 60 0 0 0 0 0 0 0 0 0 0 0 0 0 Resin H 0 0 60 60 0 0 0 30 30 0 0 0 70 55 40 Sylavrez TR-1085 0 0 0 0 30 30 30 0 0 20 20 20 0 0 0 Foral 105 0 0 0 0 30 30 30 0 0 0 0 0 0 0 0 Cellolyn 21 0 0 0 0 0 0 0 30 30 0 0 0 0 0 0 Escorez 5380 0 0 0 0 0 0 0 10 10 0 0 0 0 0 0 Indopol H-1900 0 0 0 0 0 0 0 0 0 40 40 40 0 0 0 Escorez 1580 0 0 0 0 10 10 10 0 0 0 0 0 0 0 0 Hercolyn D 0 0 0 0 0 0 0 0 0 7 7 7 0 7 0 Wingtack 10 0 0 0 0 0 0 0 0 0 0 0 0 5 8 20 Sylarez TR-1100 The adhesive compositions of Examples 1-15 were processed with a 19 mm diameter co-rotating, intermeshing twin screw extruder (B&P Process Equipment MP19-TC) without the use of a slot die, with the extruded mixture coated between two release liners on a simple two roll coater gapped to provide a coating thickness of 0.040". The respective components were fed by gravimetric or volumetric feeders into various sequential feed ports of the extruder. The length/diameter ratio in each instance was 40: 1. The polymers with the highest melt viscosity were fed into the extruder first, with the additives being fed downstream after mastication of the base polymer. In some cases, it was advisable to feed a portion of the tackifier with the base polymer to assist in mastication. The temperature within various zones of the respective extruders ranged from 60 to 240 °C., depending upon the function of the respective zone and the barrel diameter of the extruder. Upon discharge from the barrel of the extruder, the resulting homogeneous mixture was coated onto a desired substrate or backing material.

The preferred substrate is a release material in roll form. The Examples 1-15 were tested for properties as shown in Table 2.

Table 2 Property Ex. l Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. I I Ex. 12 Ex. 13 Ex. 14 Ex. 15 24 hr peel---------------------------27 35 29 62* 48* 34 SST (#/in) 24 hr peel 33 22 39 21 40 32 35 44 32------------------ Aluminu m (#/in) HDPE 11 13 5 13 26 16 7 24 23 5 26 14 HDPE (#/in) 24 hr peel --- --- --- --- --- -- -- --- --- 21 19 19 --- -- --- PP (#/in) SAFT --- --- --- --- --- --- --- --- --- 70 75 90 --- --- --- (°C) 500 gram >20K >20K >20K >20K------------------------------- static shear 1000 gram --- --- --- --- 6K 60 700 930 160 --- --- --- 900** >10K >10K @@@ static shear Note: All peel adhesions are 180° peels based on PSTC-1. The backing substrate for all examples was 0. 005" aluminum as plastic films typically failed during the peel<BR> testing prior to adhesive failure. Various substrate peel panels were used as indicated, with dwell time of the adhesive on the panels also noted.<BR> <P>Static shear test was on V2"x 1/2"adhesive overlap to stainless steel with various weights, as noted, suspended from the free end of the tape sample. Failure time in<BR> minutes was recorded.<BR> <P>Shear Adhesion Failure Temperature (SAFT) was obtained by bonding a l"xl"adhesive overlap to stainless steel panel and allowing the bond to dwell for 24 hours.<BR> <P>The panel was placed in apparatus similar to that for static testing that is in oven after programmed temperature control. A 500 gram weight was suspended from the sample and<BR> the oven was set for 40 °C. After 10 minutes, the temperature was increased at a rate of 5°C/min to 45°C, 10 minute dwell. The 5°C increment with 10 minute dwell every 5°C is<BR> continued until the adhesive fails. The temperature at failure is recorded.<BR> <P>Peel adhesions in #/in ; Shears in minutes<BR> denotes backing substrate failure before adhesive failure<BR> : *** Shear failure for Example 13 was not cohesive failure, but rather a slow creep failure. Shear failure for Examples 5-9 were adhesive failure.