Polymeric compositions containing block copolymers having high flow and high elasticity

[0001] The present application claims the benefit of U.S. Provisional patent application 60/549,570, filed Mar. 3, 2004, entitled Block Copolymers Having High Flow and High Elasticity, and U.S. Provisional patent application 60/617,941, filed Oct. 12, 2004, entitled Polymeric Compositions Containing Block Copolymers Having High Flow and High Elasticity.

[0002] 1. Field of the Invention

[0003] This invention relates to hydrogenated anionic block copolymers of mono alkenyl arenes and conjugated dienes, and to compositions made from such block copolymers. This invention particularly relates to compositions containing propylene polymers and copolymers with certain hydrogenated block copolymers of styrene and butadiene.

[0004] 2. Background of the Art

[0005] The preparation of block copolymers of mono alkenyl arenes and conjugated dienes is well known. One of the first patents on linear ABA block copolymers made with styrene and butadiene is U.S. Pat. No. 3,149,182. Uses for the block copolymers include injection molding, extrusion, blow molding, adhesives, and the like. These polymers have also been used in applications such as the modification of bitumen for the production of roofs and roads. Other uses of block copolymers include the production of films, fibers, and non-woven fabrics.

[0006] One example of such a block copolymer is in U.S. Pat. No. 4,188,432 to Holden, et al. Disclosed therein are shaped articles which are resistant to attack by fatty substances consisting essentially of high impact styrene-butadiene graft copolymer or a mixture thereof with no more than about 55% styrene homopolymer. The shaped articles also include small proportions of polyethylene or polypropylene and of a block copolymer X-Y-X in which each X is a polystyrene block of about 5,000 to 10,000 molecular weight and Y is a hydrogenated polybutadiene block of 25,000 to 50,000 molecular weight.

[0007] Another example of a block copolymer is found in U.S. Pat. No. 5,705,556 to Djiauw, et al. In this reference, it is disclosed that an extrudable elastomeric composition for making elastic fibers or films can be prepared using an elastomeric block copolymer, a polyphenylene ether, a polyolefin, and a tackifying resin. The article is further described as having from 25% to 75% by weight of a block copolymer having at least two monoalkenyl arene blocks separated by a hydrogenated conjugated diene block.

[0008] It is known in the art of preparing articles from polymers using injection molding, extrusion, and fiber spinning to use processing aids to reduce undesirable properties of the polymer being used. For example, fiber lubricants having excellent stability to smoking under conditions of use at elevated temperature in the mechanical and heat treatment operation subsequent to extrusion of the fiber, is disclosed in U.S. Pat. No. 4,273,946 to Newkirk, et al. What has now been found is that the certain polymers of the present invention can be blended with large amounts of propylene polymers and copolymers to prepare compounds having excellent translucency and impact properties, making them useful in a wide variety of end-use applications.

[0009] In one aspect, the present invention is a polymeric composition having improved toughness, clarity and processability containing 98 to 20 weight percent of one or more propylene polymers and 2 to 80 weight percent of a selectively hydrogenated block copolymer having an S block and an E or E₁ block and having the general formula:
S-E-S, (S-E₁)_n, (S-E₁)_nS, (S-E₁)_nX
or mixtures thereof, wherein: (a) prior to hydrogenation the S block is a polystyrene block; (b) prior to hydrogenation the E block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene and mixtures thereof, having a molecular weight of from 40,000 to 70,000; (c) prior to hydrogenation the E₁ block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene and mixtures thereof, having a molecular weight of from 20,000 to 35,000; (d) n has a value of 2 to 6 and X is a coupling agent residue; (e) the styrene content of the block copolymer is from 13 percent to 25 percent; (f) the vinyl content of the polydiene block prior to hydrogenation is from 60 to 85 mol percent; (g) the block copolymer includes less than 15 weight percent lower molecular weight units having the general formula:
S-E or S-E₁
wherein S, E and E₁ are as already defined; (h) subsequent to hydrogenation about 0-10% of the styrene double bonds have been hydrogenated and at least 80% of the conjugated diene double bonds have been hydrogenated; (i) the molecular weight of each of the S blocks is from 5,000 to 7,000; and (j) the melt index of the block copolymer is greater than or equal to 12 grams/10 minutes according to ASTM D1238 at 230° C. and 2.16 kg weight.

[0010] In still another aspect, the present invention is a transparent, flexible part prepared by a process selected from the group consisting of injection molding, slush molding, rotational molding, compression molding, and dipping. The article may be selected from the group consisting of a: film, sheet, coating, band, strip, profile, tube, molding, foam, tape, fabric, thread, filament, ribbon, fiber, plurality of fibers and fibrous web. The article or part is prepared using a polymeric composition containing 98 to 20 weight percent of one or more propylene polymers and 2 to 80 weight percent of a selectively hydrogenated block copolymer having an S block and an E or E₁ block and having the general formula:
S-E-S, (S-E₁)_n, (S-E₁)_nS, (S-E₁)_nX
or mixtures thereof, wherein: (a) prior to hydrogenation the S block is a polystyrene block; (b) prior to hydrogenation the E block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene and mixtures thereof, having a molecular weight of from 40,000 to 70,000; (c) prior to hydrogenation the E₁ block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene and mixtures thereof, having a molecular weight of from 20,000 to 35,000; (d) n has a value of 2 to 6 and X is a coupling agent residue; (e) the styrene content of the block copolymer is from 13 percent to 25 percent; (f) the vinyl content of the polydiene block prior to hydrogenation is from 60 to 85 mol percent; (g) the block copolymer includes less than 15 weight percent lower molecular weight units having the general formula:
S-E or S-E₁
wherein S, E and E₁ are as already defined; (h) subsequent to hydrogenation about 0-10% of the styrene double bonds have been hydrogenated and at least 80% of the conjugated diene double bonds have been hydrogenated; (i) the molecular weight of each of the S blocks is from 5,000 to 7,000; and (j) the melt index of the block copolymer is greater than or equal to 12 grams/10 minutes according to ASTM D1238 at 230° C. and 2.16 kg weight.

[0011] In one embodiment, the present invention is a polymeric composition of one or more propylene polymers and a selectively hydrogenated block copolymer, said blend having improved balance of toughness, clarity and processability. Said selectively hydrogenated block copolymer having an S block and an E or E₁ block and having the general formula:
S-E-S, (S-E₁)_n, (S-E₁)_nS, (S-E₁)_nX
or mixtures thereof, wherein: (a) prior to hydrogenation, the S block is a polystyrene block; (b) prior to hydrogenation, the E block or E₁ block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene and mixtures thereof. The block copolymer can be linear or radial having three to six arms. General formulae for the linear configurations include:
S-E-S and/or (S-E₁)_n and/or (S-E₁)_nS
wherein the E block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene and mixtures thereof, having a molecular weight of from 40,000 to 70,000; the E₁ block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene and mixtures thereof, having a molecular weight of from 20,000 to 35,000; and n has a value from 2 to 6, preferably from 2 to 4, and more preferably approximately 3. General formula for the radial configurations include:
wherein the E₁ block is a polydiene block, selected from the group consisting of polybutadiene, polyisoprene and mixtures thereof, having a molecular weight of from 20,000 to 35,000; and X is a coupling agent residue.

[0012] As used herein, the term “molecular weights” refers to the true molecular weight in g/mol of the polymer or block of the copolymer. The molecular weights referred to in this specification and claims can be measured with gel permeation chromatography (GPC) using polystyrene calibration standards, such as is done according to ASTM 3536. GPC is a well-known method wherein polymers are separated according to molecular size, the largest molecule eluting first. The chromatograph is calibrated using commercially available polystyrene molecular weight standards. The molecular weight of polymers measured using GPC so calibrated are styrene equivalent molecular weights. The styrene equivalent molecular weight may be converted to true molecular weight when the styrene content of the polymer and the vinyl content of the diene segments are known. The detector used is preferably a combination ultraviolet and refractive index detector. The molecular weights expressed herein are measured at the peak of the GPC trace, converted to true molecular weights, and are commonly referred to as “peak molecular weights”.

[0013] The block copolymers of the present invention are prepared by anionic polymerization of styrene and a diene selected from the group consisting of butadiene, isoprene and mixtures thereof. The polymerization is accomplished by contacting the styrene and diene monomers with an organoalkali metal 25 compound in a suitable solvent at a temperature within the range from about −150° C. to about 300° C., preferably at a temperature within the range from about 0° C. to about 100° C. Particularly effective anionic polymerization initiators are organolithium compounds having the general formula RLi_n where R is an aliphatic, cycloaliphatic, aromatic, or alkyl-substituted aromatic hydrocarbon radical having from 1 to 20 carbon atoms; and n is an integer of 1 to 4. Preferred initiators include n-butyl lithium and sec-butyl lithium. Methods for anionic polymerization are well known and can be found in such references as U.S. Pat. Nos. 4,039,593 and U.S. Reissue Pat. No. Re 27,145.

[0014] The block copolymers of the present invention can be linear, linear coupled, or a radial block copolymer having a mixture of 2 to 6 “arms”. Linear block copolymers can be made by polymerizing styrene to form a first S block, adding butadiene to form an E block, and then adding additional styrene to form a second S block. A linear coupled block copolymer is made by forming the first S block and E block and then contacting the diblock with a difunctional coupling agent. A radial block copolymer is prepared by using a coupling agent that is at least trifunctional.

[0015] Difunctional coupling agents useful for preparing linear block copolymers include, for example, methyl benzoate as disclosed in U.S. Pat. No. 3,766,301. Other coupling agents having two, three or four functional groups useful for forming radial block copolymers include, for example, silicon tetrachloride and alkoxy silanes as disclosed in U.S. Pat. Nos. 3,244,664, 3,692,874, 4,076,915, 5,075,377, 5,272,214 and 5,681,895; polyepoxides, polyisocyanates, polyimines, polyaldehydes, polyketones, polyanhydrides, polyesters, polyhalides as disclosed in U.S. Pat. No. 3,281,383; diesters as disclosed in U.S. Pat. No. 3,594,452; methoxy silanes as disclosed in U.S. Pat. No. 3,880,954; divinyl benzene as disclosed in U.S. Pat. Nos. 3,985,830; 1,3,5-benzenetricarboxylic acid trichloride as disclosed in U.S. Pat. No. 4,104,332; glycidoxytrimethoxy silanes as disclosed in U.S. Pat. No. 4,185,042; and oxydipropylbis(trimethoxy silane) as disclosed in U.S. Pat. No. 4,379,891.

[0016] In one embodiment of the present invention, the coupling agent used is an alkoxy silane of the general formula R_x—Si—(OR′)_y, where x is 0 or 1, x+y=3 or 4, R and R′ are the same or different, R is selected from aryl, linear alkyl and branched alkyl hydrocarbon radicals, and R′ is selected from linear and branched alkyl hydrocarbon radicals. The aryl radicals preferably have from 6 to 12 carbon atoms. The alkyl radicals preferably have 1 to 12 carbon atoms, more preferably from 1 to 4 carbon atoms. Under melt conditions these alkoxy silane coupling agents can couple further to yield functionalities greater than 4. Preferred tetra alkoxy silanes are tetramethoxy silane (“TMSi”), tetraethoxy silane (“TESi”), tetrabutoxy silane (“TBSi”), and tetrakis(2-ethylhexyloxy)silane (“TEHSi”). Preferred trialkoxy silanes are methyl trimethoxy silane (“MTMS”), methyl triethoxy silane (“MTES”), isobutyl trimethoxy silane (“IBTMO”) and phenyl trimethoxy silane (“PhTMO”). Of these the more preferred are tetraethoxy silane and methyl trimethoxy silane.

[0017] One important aspect of the present invention is the microstructure of the polymer. The microstructure relevant to the present invention is a high amount of vinyl in the E and/or E₁ blocks. This configuration can be achieved by the use of a control agent during polymerization of the diene. A typical agent is diethyl ether. See U.S. Pat. No. Re 27,145 and U.S. Pat. No. 5,777,031, the disclosure of which is hereby incorporated by reference. Any microstructure control agent known to those of ordinary skill in the art of preparing block copolymers to be useful can be used to prepare the block copolymers of the present invention.

[0018] In the practice of the present invention, the block copolymers are prepared so that they have from about 60 to about 85 mol percent vinyl in the E and/or E₁ blocks prior to hydrogenation. In another embodiment, the block copolymers are prepared so that they have from about 65 to about 85 mol percent vinyl content.

[0019] In still another embodiment, the block copolymers are prepared so that they have from about 70 to about 85 mol percent vinyl content. Another embodiment of the present invention includes block copolymers prepared so that they have from about 73 to about 83 mol percent vinyl content in the E and/or E₁ blocks.

[0020] In one embodiment, the present invention is a hydrogenated block copolymer. The hydrogenated block copolymers of the present invention are selectively hydrogenated using any of the several hydrogenation processes know in the art.

[0021] For example the hydrogenation may be accomplished using methods such as those taught, for example, in U.S. Pat. Nos. 3,494,942; 3,634,594; 3,670,054; 3,700,633; and Re. 27,145, the disclosures of which are hereby incorporated by reference. Any hydrogenation method that is selective for the double bonds in the conjugated polydiene blocks, leaving the aromatic unsaturation in the polystyrene blocks substantially intact, can be used to prepare the hydrogenated block copolymers of the present invention.

[0022] The methods known in the prior art and useful for preparing the hydrogenated block copolymers of the present invention involve the use of a suitable catalyst, particularly a catalyst or catalyst precursor comprising an iron group metal atom, particularly nickel or cobalt, and a suitable reducing agent such as an aluminum alkyl. Also useful are titanium based catalyst systems. In general, the hydrogenation can be accomplished in a suitable solvent at a temperature within the range from about 20° C. to about 100° C., and at a hydrogen partial pressure within the range from about 100 psig (689 kPa) to about 5,000 psig (34,473 kPa). Catalyst concentrations within the range from about 10 ppm to about 500 ppm by wt of iron group metal based on total solution are generally used and contacting at hydrogenation conditions is generally continued for a period of time with the range from about 60 to about 240 minutes. After the hydrogenation is completed, the hydrogenation catalyst and catalyst residue will, generally, be separated from the polymer.

[0023] In the practice of the present invention, the hydrogenated block copolymers have a hydrogenation degree greater than 80 percent. This means that more than 80 percent of the conjugated diene double bonds in the E or E₁ block has been hydrogenated from an alkene to an alkane. In one embodiment, the E or E₁ block has a hydrogenation degree greater than about 90 percent. In another embodiment, the E or E₁ block has a hydrogenation degree greater than about 95 percent.

[0024] In the practice of the present invention, the styrene content of the block copolymer is from about 13 percent to about 25 weight percent. In one embodiment, the styrene content of the block copolymer is from about 15 percent to about 24 percent. Any styrene content within these ranges can be used with the present invention. Subsequent to hydrogenation, from 0 to 10 percent of the styrene double bonds in the S blocks have been hydrogenated in the practice of the present invention.

[0025] The molecular weight of each of the S blocks in the block copolymers of the present invention is from about 5,000 to about 7,000 in the block copolymers of the present invention. In one embodiment, the molecular weight of each of the S blocks is from about 5,800 to about 6,600. The S blocks of the block copolymers of the present invention can be a polystyrene block having any molecular weight within these ranges.

[0026] In the practice of the present invention, the E blocks are a single polydiene block. These polydiene blocks can have molecular weights that range from about 40,000 to about 70,000 The E₁ block is a polydiene block having a molecular weight range of from about 20,000 to about 35,000. In one embodiment, the molecular weight range of the E block is from about 45,000 to about 60,000, and the molecular weight range for each E₁ block of a coupled block copolymer, prior to being coupled, is from about 22,500 to about 30,000.

[0027] One advantage of the present invention over conventional hydrogenated block copolymer is that they have high melt flows that allow them to be easily molded or continuously extruded into shapes or films or spun into fibers. This property allows end users to avoid or at least limit the use of additives that degrade properties, cause area contamination, smoking, and even build up on molds and dies. But the hydrogenated block copolymers of the present invention also are very low in contaminants that can cause these undesirable effects, such as diblocks from inefficient coupling. The block copolymers and hydrogenated block copolymers of the present invention have less than 15 weight percent of diblock content, such diblocks having the general formula:
SE or SE₁
wherein S, E and E₁ are as previously defined. In one embodiment, the diblock level is less than 10 percent in another embodiment less than 8 percent. All percentages are by weight.

[0028] One characteristic of the hydrogenated block copolymers of the present invention is that they have a low order-disordertemperature. The order-disorder temperature (ODT) of the hydrogenated block copolymers of the present invention is typically less than about 250° C. Above 250° C. the polymer is more difficult to process although in certain instances for some applications ODT's greater than 250° C. can be utilized. One such instance is when the block copolymer is combined with other components to improve processing. Such other components may be thermoplastic polymers, oils, resins, waxes and the like. In one embodiment, the ODT is less than about 240° C. Preferably, the hydrogenated block copolymers of the present invention have an ODT of from about 210° C. to about 240° C. This property can be important in some applications because when the ODT is below 210° C., the block copolymer may exhibit creep that is undesirably excessive or low strength. For purposes of the present invention, the order-disorder temperature is defined as the temperature above which a zero shear viscosity can be measured by capillary rheology or dynamic rheology.

[0029] For the purposes of the present invention, the term “melt index” is a measure of the melt flow of the polymer according ASTM D1238 at 230° C. and 2.16 kg weight. It is expressed in units of grams of polymer passing through a melt rheometer orifice in 10 minutes. The hydrogenated block copolymers of the present invention have a desirable high melt index allowing for easier processing than similar hydrogenated block copolymers that have higher melt indexes. In one embodiment, the hydrogenated block copolymers of the present invention have a melt index of greater than or equal to 12. In another embodiment, the hydrogenated block copolymers of the present invention have a melt index of greater than or equal to 20. In still another embodiment, the hydrogenated block copolymers of the present invention have a melt index of greaterthan or equal to 40. Another embodiment of the present invention includes hydrogenated block copolymers having a melt index of from about 12 to about 92. Still another embodiment of the present invention includes hydrogenated block copolymers having a melt index of from about 40 to about 85.

[0030] The hydrogenated block copolymers of the present invention are especially suited for use in preparing articles requiring a melt based processing. For example, the hydrogenated block copolymers of the present invention can be used in a process selected from the group consisting of injection molding, over molding, insert molding, dipping, extrusion, roto molding, slush molding, fiber spinning, film making, and foaming. Articles made using such processes include: film, sheet, coating, band, strip, profile, tube, molding, foam, tape, fabric, thread, filament, ribbon, fiber, plurality of fibers, fibrous web and laminates containing a plurality of film and or fiber layers.

[0031] The present invention particularly relates to blends of 98 to 20 weight percent of one or more propylene polymers, including copolymers, and 2 to 80 weight percent of the presently claimed block copolymer. Preferred ranges are 90 to 20 weight percent of one or more propylene polymers or copolymers and 10 to 80 weight percent block copolymer for medical, injection molding and overmolding applications. More specifically, for more flexible applications such as tubing and elastic films, the one or more propylene polymers or copolymers will preferably be present in an amount from about 50 to about 30 weight percent. In those applications that require a greater amount of stiffness while retaining toughness, the more preferred range of propylene polymer(s) or copolymer(s) will be from about 98 to about 51 weight percent. Preferred ranges are 98 to 70 weight percent propylene homopolymer(s) or copolymer(s) and 2 to 30 weight percent block copolymer for polymer toughening applications for packaging, molded articles, etc.

[0032] Propylene polymers used in this invention include, for example, polypropylene homopolymers, propylene copolymers with one or more alpha olefins, high impact polypropylene, branched polypropylene, and polypropylenes made using single site and metallocene catalysts. In one embodiment, the propylene polymers used are polypropylene terpolymers (i.e., propylene-ethylene-butene) such as Adsyl® and Clyrell® from Basell. Preferred are high clarity, polymers such as polypropylene copolymers, plastomers, elastomers and interpolymers. Some examples are propylene polymers and copolymers such as Profax or Mopolen from Basell. In another embodiment, the propylene homopolymer or copolymer is a high clarity polypropylene copolymer that can be polypropylene plastomer, elastomer or interpolymer. Examples include Versify polymers from Dow Chemical, Metocene polymers from Basell and Vistamaxx polymers from Exxon Mobil. Also included are styrene-grafted polypropylene polymers, such as those offered under the trade name Interloy®, originally developed by Himont, Inc. (now Basell).

[0033] While the hydrogenated copolymers of the present invention have such low order-disorder temperatures and high melt indexes that they can be blended with polypropylene homopolymers and copolymers to prepare articles without using processing aids, it is sometimes desirable to use such aids and other additives. Exemplary of such additives are members selected from the group consisting of other block copolymers, styrene polymers, tackifying resins, end block resins, polymer extending oils, waxes, fillers, reinforcements, lubricants, stabilizers, engineering thermoplastic resins, and mixtures thereof.

[0034] When the additive is an olefin polymer, exemplary polymers include, for example, ethylene homopolymers, ethylene/alpha-olefin copolymers, butylene homopolymers, butylene/alpha olefin copolymers, and other alpha olefin copolymers or interpolymers. Representative polyolefins include, for example, but are not limited to, substantially linear ethylene polymers, homogeneously branched linear ethylene polymers, heterogeneously branched linear ethylene polymers, including linear low density polyethylene (LLDPE), ultra or very low density polyethylene (ULDPE or VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE) and high pressure low density polyethylene (LDPE). Other polymers included hereunder are ethylene/acrylic acid (EM) copolymers, ethylene/methacrylic acid (EMAA) ionomers, ethylene/vinyl acetate (EVA) copolymers, ethylene/vinyl alcohol (EVOH) copolymers, ethylene/cyclic olefin copolymers, ethylene/propylene copolymers, polybutylene, ethylene carbon monoxide interpolymers (for example, ethylene/carbon monoxide (ECO) copolymer, ethylene/acrylic acid/carbon monoxide terpolymer and the like. Preferred are high clarity, soft olefin polymers such as polyethylene copolymers, plastomers, elastomers and interpolymers. Examples include Affinity and Engage polymers from Dow Chemical and Exact polymers from Exxon Mobil.

[0035] The hydrogenated copolymers of the present invention can also be admixed with styrene polymers. Styrene polymers include, for example, crystal polystyrene, high impact polystyrene, medium impact polystyrene, styrene/acrylonitrile copolymers, styrene/acrylonitrile/butadiene (ABS) polymers, syndiotactic polystyrene and styrene/olefin copolymers. Representative styrene/olefin copolymers are substantially random ethylene/styrene or propylene/styrene copolymers. The hydrogenated copolymers of the present invention can also be admixed with other block copolymers such as styrene-diene-styrene triblock, radial or star block polymers, styrene-diene diblock polymers, and the hydrogenated versions of these polymers. Examples of high vinyl polymers which may be used include HYBRAR® from Kurraray and Dynaron from JSR.

[0036] When the additives used with the hydrogenated block copolymers of the present invention are tackifying resins, exemplary resins include polystyrene block compatible resins and midblock compatible resins. The polystyrene block compatible resin may be selected from the group of coumarone-indene resin, polyindene resin, poly(methyl indene) resin, polystyrene resin, vinyltoluene-alphamethylstyrene resin, alphamethylstyrene resin and polyphenylene ether, in particular poly(2,6-dimethyl-1,4-phenylene ether). Such resins are e.g. sold under the trademarks “HERCURES”, “ENDEX”, “KRISTALEX”, “NEVCHEM” and “PICCOTEX”. Resins compatible with the hydrogenated (mid) block may be selected from the group consisting of compatible C5 hydrocarbon resins, hydrogenated C5 hydrocarbon resins, styrenated C5 resins, C5/C9 resins, styrenated terpene resins, fully hydrogenated or partially hydrogenated C9 hydrocarbon resins, rosins esters, rosins derivatives and mixtures thereof. These resins are e.g. sold under the trademarks “REGALITE”, “REGALREZ”, “ESCOREZ” and “ARKON”. Also, one may use both a polystyrene block compatible resin and a midblock compatible resin.

[0037] While the above referenced additives can be used, it is often desirable to limit their use to avoid problems inherent therewith including but not limited to smoking, die build up, mold build up, area contamination, and the like. In one embodiment, the total concentration of additives (other than polyolefins) present in an article prepared with a hydrogenated block copolymer of the present invention is less than about 25 percent by weight. In another embodiment the total concentration of additives present in an article prepared with a hydrogenated block copolymer of the present invention is less than about 10 percent by weight, preferably from about 0.001 to about 10 percent by weight. In still another embodiment, the total concentration of additives present in an article prepared with a hydrogenated block copolymer of the present invention is less than about 5 percent by weight, preferably from about 0.001 to about 5 percent by weight. In still another embodiment of the present invention includes one where the total concentration of additional additives present in an article prepared with a composition of the present invention is from about 0.001 percent to about 1 percent by weight.

[0038] The polymer of the present invention may be used in a large number of applications, either as a neat polymer or in a compound. The following various end uses and/or processes are meant to be illustrative, and not limiting to the present invention:

• • [0039] Polymer modification applications
  • [0040] Injection molding of toys, medical devices
  • [0041] Extruding films, tubing, profiles
  • [0042] Over molding applications for personal care, grips, soft touch applications, for automotive parts, such as airbags, steering wheels, etc
  • [0043] Dipped goods, such as gloves
  • [0044] Thermoset applications, such as in sheet molding compounds or bulk molding compounds for trays
  • [0045] Roto molding for toys and other articles
  • [0046] Slush molding of automotive skins
  • [0047] Thermal spraying for coatings
  • [0048] Blown film for medical devices
  • [0049] Blow molding for automotive/industrial parts
  • [0050] Films and fibers for personal hygiene applications
  • [0051] Tie layer for functionalized polymers
  • [0052] Roofing sheets
  • [0053] Geomembrane applications

[0054] The hydrogenated block copolymers of the present invention have very elastic properties and yet also very high melt indexes. This allows the polymer of the present invention to be readily blended with polymers and copolymers in common mixing equipment such as single screw extruders, twin screw extruders, injection molders, continuous mixers, 2 roll mills, kneaders, and the like. The compositions of the present invention are particularly useful for preparing an article selected from the group consisting of a film, tape, strip, tube, fiber, or filament made by direct extrusion capable of being used alone or in a laminate structure with a plurality of other layers; or a transparent, flexible part prepared by process selected from the group consisting of injection molding, slush molding, rotational molding, compression molding, and dipping. The surprising compatibility of the polymers of the present invention with polypropylene and poly-1-butene polymers and copolymers allows the production of transparent articles from the blends, however, fillers and colorants may be added to product an opaque article.

[0055] The following examples are provided to illustrate the present invention. The examples are not intended to limit the scope of the present invention and they should not be so interpreted. Amounts are in weight parts or weight percentages unless otherwise indicated.

[0056] A hydrogenated block copolymer was prepared by anionic polymerization of styrene and then butadiene in the presence of a microstructure control agent followed by coupling, then hydrogenation: a diblock polymer anion, S—B—Li, was prepared by charging 361 kg of cyclohexane and 16.7 kg, of styrene to a reactor. The reactor temperature was increased to about 40° C. Impurities were removed by adding small aliquots of s-butyllithium until the first evidence of color. 1,900 milliliters of a solution of an approximately 12% wt solution of s-butyllithium in cyclohexane was added, and the styrene was allowed to complete polymerization at about 60° C. The molecular weight of the polystyrene produced in this reaction was determined to be 6,400 by GPC. The temperature was maintained at 60° C., 320 g. of 1,2-diethoxypropane were added, and then 72.6 kg of butadiene were added at such a rate as to allow the temperature to remain about 60° C. A sample collected at the end of the butadiene polymerization had a styrene content of 21.3% wt and a vinyl content of 69% basis ¹H NMR and an overall molecular weight of 35,000 as determined by GPC.

[0057] Following polymerization of the majority of the butadiene, 623 g. of isoprene was added. The isoprene was allowed to polymerize, and then 257 g of TESi was added, and the coupling reaction was allowed to proceed for 60 minutes at 60° C. Methanol (8.5 g, 0.1 mol per mol of Li) was added to terminate the reaction. The final product had a coupling efficiency of 91%, and 72% of the coupled species were linear, the remaining being 3-arm radial.

[0058] A sample of the polymer was hydrogenated to a residual olefin concentration of 0.09 meq/g in the presence of 20 ppm Co/solution of a cobalt neodecanoate-aluminum triethyl catalyst (Al/Co=1.7 mol/mol). After hydrogenation under these conditions, the polymer remained 91% coupled. The catalyst was removed by washing with aqueous phosphoric acid, and the polymer was recovered via steam stripping, under conditions typical for hydrogenated polymers.

[0059] Samples were taken such that the molecular weight of the styrene block and butadiene/isoprene blocks could be determined. The amount of butadiene in the 1,2 configuration before hydrogenation and the coupling efficiency was also determined. The hydrogenated block copolymer was tested for melt flow and ODT. The results of the testing are displayed below in Table 1.

[0060] A hydrogenated block copolymer was prepared by anionic polymerization of styrene and then butadiene in the presence of a microstructure control agent followed by coupling then hydrogenation: a diblock polymer anion, S—B—Li, was prepared by charging 348 kg of cyclohexane and 26 kg, of styrene to a reactor. The reactor temperature was increased to about 40° C. Impurities were removed by adding small aliquots of s-butyllithium until the first evidence of color. 3,160 milliliters of a solution of an approximately 12% wt solution of s-butyllithium in cyclohexane was added, and the styrene was allowed to complete polymerization at about 60° C. The molecular weight of the polystyrene produced in this reaction was determined to be 6,200 by GPC. The temperature was maintained at 60° C., 450 g. of 1,2-diethoxypropane were added, and then 90 kg of butadiene were added at such a rate as to allow the temperature to remain about 60° C. A sample collected at the end of the butadiene polymerization had a styrene content of 22% wt and a vinyl content of 81% basis ¹H NMR and an overall molecular weight of 30,200 as determined by GPC. The butadiene was allowed to polymerize, and then 363 g of TESi was added, and the coupling reaction was allowed to proceed for 60 minutes at 60° C. Methanol (15 g, 0.1 mol per mol of Li) was added to terminate the reaction. The final product had a coupling efficiency of 89%, and 65% of the coupled species were linear, the remaining being 3-arm radial.

[0061] A sample of the polymer was hydrogenated to a residual olefin concentration of 0.17 meq/g in the presence of 20 ppm Ni/solution of a Nickel octanoate-aluminum triethyl catalyst (Al/Ni=2.1 mol/mol). After hydrogenation under these conditions, the polymer remained 89% coupled. The catalyst was removed by washing with aqueous phosphoric acid, and the polymer was recovered via steam stripping, under conditions typical for hydrogenated polymers.

[0062] Samples were taken such that the molecular weight of the styrene block and butadiene blocks could be determined. The amount of butadiene in the 1,2 configuration before hydrogenation and the coupling efficiency was also determined. The hydrogenated block copolymer is tested for melt flow and ODT. The results of the testing are displayed below in Table 1.

[0063] A hydrogenated block copolymer was prepared by anionic polymerization of styrene and then butadiene in the presence of a microstructure control agent followed by coupling then hydrogenation: a diblock polymer anion, S—B—Li, was prepared by charging 243 kg of cyclohexane and 20 kg, of styrene to a reactor. The reactor temperature was increased to about 40° C. Impurities were removed by adding small aliquots of s-butyllithium until the first evidence of color. 2,500 milliliters of a solution of an approximately 12% wt solution of s-butyllithium in cyclohexane was added, and the styrene was allowed to complete polymerization at about 60° C. The molecular weight of the polystyrene produced in this reaction was determined to be 6,100 by GPC. The temperature was maintained at 60° C., 210 g. of 1,2-diethoxypropane were added, and then 60 kg of butadiene were added at such a rate as to allow the temperature to remain about 60° C. A sample collected at the end of the butadiene polymerization had a styrene content of 22% wt and a vinyl content of 76% basis ¹H NMR and an overall molecular weight of 27,700 as determined by GPC. The butadiene was allowed to polymerize, and then 243 g of TESi was added, and the coupling reaction was allowed to proceed for 60 minutes at 60° C. The final product had a coupling efficiency of 94%, and 62% of the coupled species were linear, the remaining being 3-arm radial.

[0064] A sample of the polymer was hydrogenated to a residual olefin concentration of 0.17 meq/g in the presence of 10 ppm Ni/solution of a Nickel octanoate-aluminum triethyl catalyst (Al/Ni=2.1 mol/mol). After hydrogenation under these conditions, the polymer remained 89% coupled. The catalyst was removed by washing with aqueous phosphoric acid, and the polymer was recovered via steam stripping, under conditions typical for hydrogenated polymers.

[0065] Samples were taken such that the molecular weight of the styrene block and butadiene blocks could be determined. The amount of butadiene in the 1,2 configuration before hydrogenation and the coupling efficiency was also determined. The hydrogenated block copolymer was tested for melt flow and ODT. The results of the testing are displayed below in Table 1.

[0066] A polymer was prepared by the method of examples 2 and 3 where the styrene and butadiene charges were changed such that the styrene block had a molecular weight of 6,200, the overall molecular weight before coupling was 33,200, the vinyl content was 78% and the degree of coupling was 97%. After hydrogenation the coupling efficiency was 96% and the residual unsaturation was 0.1 meq/g.

[0067] A polymer was prepared by the method of examples 2 and 3 with the exception that methyl trimethoxy silane was used as the coupling agent. The styrene and butadiene charges were such that the styrene block had a molecular weight of 6,200, the overall molecular weight before coupling was 32,800, the vinyl content was 76 and the degree of coupling was 94.

[0068] A polymer was prepared by the method of examples 2 and 3 with the exception that tetramethoxy silane was used as the coupling agent. The styrene and butadiene charges were such that the styrene block had a molecular weight of 6,100, the overall molecular weight before coupling was 34,500, the vinyl content was 76 and the degree of coupling was 95.

[0069] Comparative hydrogenated block copolymers I and II were prepared and tested substantially identically to Example 2 except that the styrene block molecular weight was greater than the maximum molecular weight of the invention. Comparative example III was prepared by sequential polymerization of styrene then butadiene then styrene followed by hydrogenation. The results of the testing are displayed below in Table 1.

TABLE 1
Exam-			Coupling
ple	S Block	E Block	Effi-	1,2-butadiene	ODT	Melt
#	mwt (k)	mwt (k)	ciency	in E block %	° C.	Index
1	6.4	27.7	91	68	250	18
2	6.2	24.0	89	81	230	81
3	6.1	21.6	94	76	230	72
4	6.2	27.0	97	78	240	17
5	6.2	26.6	94	76	<250	31
6	6.1	28.5	95	76	<250	20
I	7.5	30.8	84	67	260	10
II	7.9	26.8	92	69	300+	6
III	7.2	55.8	8.5*	68	300+	7
The molecular weight values listed are true molecular weights determined using Gel Permation Chromatography and Polystyrene standards. For Comparative Example III, the polymer is a linear sequential S1-EB-S2 type block copolymer, and the asterisk shows the molecular weight of the S2 block.
The ODT's were measured using a Bohlin VOR rheometer.
Melt Index Test Method [230° C., 2.16 KG, ASTM D-1238]

[0070] Examples 1-4 and Comparative Examples I to III show that the molecular weight of the S block can have a significant effect on melting index and/or ODT.

[0071] Films were prepared from some of the polymers in Table 1 by adding 0.15% release agent and 0.02% Ethanox 330 stabilizer followed by extrusion on a Davis Standard cast film line at 230C. Polymers 2 and 3 gave low extrusion pressures and formed smooth, clear films because of their high flow. Comparative example III formed rougher films with high extrusion backpressure. The tensile and hysteresis properties of these films measured in the direction of extrusion according to ASTM D412 are shown in Table 2. All show excellent strength and elasticity, as demonstrated by the high first cycle recovery and low permanent set after elongation to 300%.

	TABLE 2
	POLYMER	2	3	III
	PROPERTIES	MD	MD	MD
	Stress-Strain at 2 in/min
	Max. Stress at Break (psi)	1887	1584	2044
	Strain at Break (%)	970	938	922
	Stress at 100%, psi	206	177	205
	Stress at 300%, psi	440	382	429
	Hysteresis to 300%, 3
	cycle.
	Cycle 1 recovery	74	75	81
	Permanent set (%)	9	8	10
	Max stress (psi)	404	358	346

[0072] The polymer of Example 4 was compounded with a polypropylene copolymer with a melt flow of 30, Dow Chemical 6D43, a low mw polypropylene homopolymer, Estaflex P1010 from Eastman Chemical, a hydrogenated hydrocarbon resin commercially available from Eastman Chemical as REGALREZ 1126 and a polystyrene commercially available from Nova Chemical as NOVA 555 in the proportions shown in Table 3 using a Brabender mixer at 220° C., the mixer running at about 65 RPM. The compounded hydrogenated copolymers were tested as above and the results are displayed below in Table 3.

	TABLE 3
	Example
	8	9	10	11	12	13	14	15	16
	Fraction	Fraction	Fraction	Fraction	Fraction	Fraction	Fraction	Fraction	Fraction
Polymer 3	1	0.95	0.9	0.8	0.9	0.9	0.8	0.8	0.8
Dow 6D43 PP		0.05	0.1	0.2					0.07
Regalrez 1126						0.1	0.1	0.13	0.13
Eastoflex					0.1			0.07
P1010
Nova 555 PS							0.1
Ethanox 330	0.0002	0.0002	0.0002	0.0002	0.0002	0.0002	0.0002	0.0002	0.0002
Total (g)	43.2	43.2	43.2	43.2	43.2	42.43	42.43	43.2	43.2
PROPERTIES
Clarity	Clear	Clear	Clear	Hazy	Clear	Clear	Hazy	Clear	Clear
Stress-Strain
at 2 in/min
Max. Stress at	1678	1406	1401	1239	1152	1350	1304	1266	1336
Break, psi
Strain at	936	915	932	747	951	1028	832	1082	1032
Break, %
Stress at	224	233	244	321	180	178	132	130	175
100%, psi
Stress at	450	451	465	666	359	348	327	272	356
300%, psi
Hysteresis to
300%, 3 cycle.
Cycle 1	73	65	60	52	68	70	84	75	65
recovery
Permanent	16	20	21	26	20	20	20	18	22
set (%)
Max stress	338	348	329	497	302	281	220	212	289
(psi)

[0073] Examples 9, 10 and 11 show that polypropylene can be added to increase stiffness, as shown by the modulus at 100 and 300% elongation, at the expense 5 of hysteresis recovery. Example 12 shows that adding the less crystalline P1010 polypropylene decreases modulus as does the addition of tackifying resin Regalrez 1126. Combinations of tackifying resins and PS or PP can be used to increase flow or stiffness while maintaining clarity, however, the base polymer without modification retains a superior balance of properties compared to most of the compounds. This demonstrates the importance of making articles in a practical process using the neat polymer with a minimum of additives.

[0074] In Examples 17 to 32, various blends of a block copolymer of the present invention with propylene polymers were compared with blends of a block copolymer of the prior art with propylene polymers and a blend of impact polypropylene with homopolypropylene. The block copolymer of the present invention is the polymer from Example 4, termed herein as Polymer 4. The other block copolymer, GRP 6924 from KRATON Polymers is a polymer specifically designed for high clarity when blended with polypropylene polymers.

[0075] The other polymers employed in Examples 17 to 32 are described below:

[0076] BP 6219 is high clarity, high heat resistance polypropylene homopolymer with a melt flow of 2.2 from BP.

[0077] BP 3143 is a polypropylene impact copolymer with a melt flow of 2.5 from BP.

[0078] FT-021-N is nucleated high flexural modulus polypropylene homopolymer with a melt flow of 2.6 from SUNOCO.

[0079] TI-4020-N is nucleated polypropylene impact copolymer with a melt flow of 2.0 from SUNOCO.

[0080] Samples were prepared by blending the polymers in a Berstorff 25-mm diameter co-rotating twin screw extruder. Injection molded test specimens were made from pelletized extrudate using a reciprocating screw injection molder. Instrumented impact testing was conducted on Dynatup 8250 according to ASTM D3763. Optical properties such as haze and transmission were measured on injection molded disks at 0.125 inch thick according to ASTM D-1003. All samples tested in these Examples were conditioned at 23° C. and 50% relative humidity for at least 24 hours. For low temperature impact testing, the samples were conditioned at 4° C. at least 2 hours before testing. For all the impact and optical testing, at least five samples were tested, and the average is reported as the final result.

[0081] The results are presented in Table 4 below:

TABLE 4
Example		Haze, %	Light	Impact energy	Impact energy
Number	BLENDS:	corrected	transmit. %	(in-lb) @ RT	(in-lb) @ 4 C.
17	BP 6219 PP	67	76.1	22	24
18	BP 3143 co-PP	100	46.2	312	392
19	BP6219 PP/Polymer 4	66.1	75.7	33
	(98/2)
20	BP6219 PP/Polymer 4	65.4	76.8	191	18
	(95/5)
21	BP6219 PP/Polymer 4	60.7	78.1	296	20
	(90/10)
22	BP6219 PP/Polymer 4	61.7	77.9	285	296
	(85/15)
23	BP6219 PP/Polymer 4	55.8	78.9	280	345
	(80/20)
C24	BP6219 PP/BP 3143	91.9	64	158	17
	co-PP (80/20)
C25	BP6219 PP/GRP6924	69.6	71.2	298	65
	(90/10)
26	SUNCO FT021N homo	61.3	76.1	24	25
	PP
27	SUNCO TI-4020-N co-	Opaque	opaque	311	411
	PP
28	FT021N PP/Polymer 4	65.7	77	159	20
	(95/5)
29	FT021N PP/Polymer 4	63.9	77.7	296	20
	(90/10)
30	FT021N PP/Polymer 4	61.6	78	285	350
	(85/15)
31	FT021N PP/Polymer 4	58.4	78.4	282	356
	(80/20)
C32	FT021N PP/TI-4020-N	opaque	opaque	70	18
	(80/20)

[0082] As shown in Table 4, adding Polymer 4 to BP6219 polypropylene homopolymer, examples 19-23, reduces the haze, and increases the transmission of the final blends while increasing the impact properties. The same trend can be seen for homo polypropylene from SUNOCO (i.e., FT021 N—Ex. 30 and 31). In contrast, comparative example 24 shows that adding BP 3143, a high impact copolymer, increases the haze and decreases light transmission while only modestly increasing impact. Therefore the polymer of the instant invention is shown to provide surprisingly improved toughness, better transparency and lower haze than a typical impact modifier.

[0083] Example 20 shows that polymer 4 is such an efficient toughener for polypropylene that only 5% produces higher impact at room temperature and low temperature than adding 20% impact copolymer, comparative example 24. The blend of 5% Polymer 4 and 95% homopolypropylene in example 20 also has lower haze and higher light transmission than the blend of 80% homopolypropylene and 20% impact copolypropylene, comparative example 24.

[0084] Comparative Example 25 shows that adding 10% GRP6924 to 90% BP 6219 homopolypropylene produces a slight increase in haze and reduction of light transmission which increasing toughness. By comparison, example 21 shows that blending 10% Polymer 4 and 90% BP 6219 homopolpropylene gives lower haze and higher transmission than the blend of GRP6924 and homopolypropylene.

[0085] The excellent optical properties (low haze and high transmission) and high impact of Polymer 4 and homopolypropylene blends can be used in a wide variety of applications, such packaging, injection molded containers and articles, extruded forms such as tubes, films and sheets. Some examples of packaging articles include, plates, spoons, bowls, trays, lids, cups, bottles and films. The high low temperature impact of the blend also is useful to make the containers in refrigerator or even freezer applications, such as yogurt cups.

[0086] The compounds for examples 33 through 37 were prepared in W&P ZSK25 co-rotating twin screw extruder. Five compounds were prepared: four based on the polymers of the current invention and one based on C-III, each with the following formulation:

• [0087] 70 parts SEBS
• [0088] 30 parts Polypropylene Moplen 340N from Basell
• [0089] 0.2 Irganox 1010
• [0090] 0.2 phr Irganox PS800

[0091] Circular disk samples (diameter 60 mm, thickness 2 mm) made on Battenfeld injection moulding machine, using a mold with polished surfaces. Visual transparency and instrumented transmission, haze (ASTM D1003-92) and clarity (ASTM D1746-70) have been measured on disks of 2 mm thick.

	TABLE 5
	Example
	33	34	35	36	37
Polymer	1	2	3	4	C III
IM of 2 mm plates	Low	very low	very low	low	medium
Injection pressure
MFR-230° C./2.16 kg (g/10 min)			40	15	5
Transmission	87	91	91	91	88
(%)
Haze (ASTM D-1003)	10	12	9	5	9
(%)
Clarity (ASTM D-1746)	98	98	99	99	96
(%)
visual transparency	Excellent	excellent	excellent	excellent	excellent
Hardness, Shore A (30s)	79	75	80	77	81

[0092] Compared to CIII, the compounds based on polymers 1-4 exhibit similar excellent 5 clarity and haze properties but with better flow, resulting in much lower injection molding pressures.

[0093] Examples 38 through 48 were compounded on a Ikegai co-rotating twin screw extruder (30 mm diameter screw) and injection molded using 210° C. on a Toshiba 55EN injection-molding machine. Haze was measured on 2 mm thick injection-molded sheet. Melt Flow rates were measured at 230° C. and 2.16 Kgm. The polypropylenes used were random copolymers supplied by Basell: ST866M and ST868M. Table 6 compares Polymer 4 with two commercial polymers from KRATON Polymers, GRP 6924 and G1652 in the same compounds.

	TABLE 6
	Example
	38	39	40	41	42	43	44	45	46	47	48
Polymer 4				20	40	60		20	40	60
GRP6924											40	60
G1652													40
ST866M	MI = 7.0	100	80	60	40					60	40	60
ST868M	MI = 15					100	80	60	40
MFR	g/10	min	7	6.8	11	12	15	17	18	18	1.8	<0.1	4
Hardness
Shore A	0	sec				88				89		88
	30	sec				86				86		86
Shore D	0	sec	66	59	51		66	59	51		51		55
	30	sec	60	51	41		60	52	41		41		47
Haze	%	39	30	21	7.6	69	39	31	8	26	14	38

[0094] Table 6 shows that in the same compositions Polymer 4 gives significantly better flow and clarity than either GRP6924, a polymer designed for high clarity with 5 polypropylene, or G1652, a standard SEBS triblock.

[0095] Polymer 4 and GRP 6924 were compounded on a Ikegai co-rotating twin screw extruder (30 mm diameter screw) with a terpolymer and injection molded at 210° C. using a Toshiba 55EN injection-molding machine. Haze and light transmittance were measured on 2 mm thick injection-molded sheets. Melt Index rates were measured at 230° C. and 2.16 Kgm. The terpolymer used was propylene-ethylene-butene copolymer supplied by Basell: Adsyl® 5C30F as shown in Table 7. Polymer 4 gives better clarity than either the terpolymer itself or GRP6924.

	TABLE 7
		Compara-		Compara-
		tive Ex-	Exam-	tive Ex-
	ASTM	ample I	ple 49	ample II
		Adsyl ®	Polymer	GRP6924/
		5C30F	4/Adsyl ®	Adsyl ®
		100 wt %	5C30F	5C30F
			10/90 wt %	10/90 wt %
Melt
Index
(gm/10
min)
230° C./	D1238	5.5	6.2	4.3
2.16 kg	g/10
	min
Hardness,	D2240
Shore D
0 sec		59	56	54
30 sec		54	50	49
After 24	D1003
hours
Light		87	86	85
Trans-
mittance
Haze		47	32	36

[0096] Example 49 of Table 7 shows that the addition of 10 wt % of polymer 4 to Adsyl® 5C30F reduces the haze while improving the flow as indicated by increased melt index. When 10 wt % of GRP9624 is added to the same terpolymer (Comparative Example II), the blend also exhibits improved haze but to a lesser extent than shown in Example 49. In addition, Comparative Example II shows a decreased flow compared to either Example 49 or the unmodified terpolymer (Comparative Example I).