WO2009039147A1 - A polymeric composition and method for making low warpage, fiber reinforced parts therefrom - Google Patents

A polymeric composition and method for making low warpage, fiber reinforced parts therefrom Download PDF

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Publication number
WO2009039147A1
WO2009039147A1 PCT/US2008/076620 US2008076620W WO2009039147A1 WO 2009039147 A1 WO2009039147 A1 WO 2009039147A1 US 2008076620 W US2008076620 W US 2008076620W WO 2009039147 A1 WO2009039147 A1 WO 2009039147A1
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Prior art keywords
polymeric composition
filler
concentrate
elastomer
polymeric
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PCT/US2008/076620
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French (fr)
Inventor
Nigel Shields
Sebastien Tanguy
David Medlin
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Dow Global Technologies, Inc.
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Publication of WO2009039147A1 publication Critical patent/WO2009039147A1/en

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    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/04Reinforcing macromolecular compounds with loose or coherent fibrous material
    • C08J5/0405Reinforcing macromolecular compounds with loose or coherent fibrous material with inorganic fibres
    • C08J5/043Reinforcing macromolecular compounds with loose or coherent fibrous material with inorganic fibres with glass fibres
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/10Homopolymers or copolymers of propene
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/10Homopolymers or copolymers of propene
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08KUse of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00Use of inorganic substances as compounding ingredients
    • C08K3/01Use of inorganic substances as compounding ingredients characterized by their specific function
    • C08K3/013Fillers, pigments or reinforcing additives
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08LCOMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04Homopolymers or copolymers of ethene
    • C08L23/08Copolymers of ethene
    • C08L23/0807Copolymers of ethene with unsaturated hydrocarbons only containing more than three carbon atoms
    • C08L23/0815Copolymers of ethene with aliphatic 1-olefins

Definitions

  • the present invention relates to a polyolefin composition and a process for forming and/or using the same. More particularly, the present invention relates to a thermoplastic material that is a blend of thermoplastic polyolefin and reinforcement material (e.g., glass fiber), and filler, elastomer, or both and to a process of forming and/or using the same.
  • a thermoplastic material that is a blend of thermoplastic polyolefin and reinforcement material (e.g., glass fiber), and filler, elastomer, or both and to a process of forming and/or using the same.
  • thermoplastic polyolefin composition that exhibits desirable characteristics such as little or no warpage, strength durability, ductility, or any combination thereof without the need to employ costly ingredients, processes, or the like.
  • a polymeric composition particularly, a thermoplastic polyolefin composition that exhibits desirable characteristics such as little or no warpage, strength durability, ductility, or any combination thereof
  • a first aspect of the invention is directed at a polymeric composition for the manufacture of a shaped plastic article, comprising: a reinforcement concentrate including an admixture of at least one reinforcement material and a first polymeric material, a filler concentrate including an admixture of a filler and a second polymeric material; and a thermoplastic polyolefin; wherein the polymeric composition has a highly crystalline portion having a crystallinity of at least about 62 wt.%, wherein the highly crystalline portion of the polymeric composition is present at a concentration of at least about 30% by weight based on the total weight of the first polymeric material, the second polymeric material and the thermoplastic polyolefin.
  • the reinforcement material includes long glass fibers having an average fiber length greater than about 1 mm; the reinforcement material is present at a concentration of at least about 40 wt.% based on the total weight of the reinforcement concentrate; the filler is selected from the group consisting of talc, mica, and wollastonite; the filler is present at a concentration of at least about 40 wt.% based on the total weight of the filler concentrate; the filler is present at a concentration of at least about 60 wt.% based on the total weight of the filler concentrate; the filler includes talc; the first polymeric material, the second polymeric material, or both the first and second polymeric materials includes an elastomer, a polyethylene homopolymer, a polyethylene copolymer, a polypropylene homopolymer, a polypropylene copolymer, or any combination thereof; the thermoplastic polyolefin is formed of a poly
  • This process aspect of the invention may be further characterized by one or any combination of the following: the process further comprises: admixing the reinforcement concentrate, the filler, and the thermoplastic polyolefin to form a polymeric composition; the process further comprises shaping the polymeric composition into a part; the second polymeric material, the thermoplastic polyolefin, or combinations thereof include a highly crystalline portion that is at least 30% by weight of the reinforcement concentrate, the filler concentrate, the thermoplastic polyolefin, or combinations thereof; the part exhibits a warpage of less than about 30 mm according to the tray warpage test; the admixing step, includes a step of admixing the fiber concentrate and the filler concentrate prior to adding the thermoplastic polyolefin; the shaping step includes injection molding the polymeric composition, compression molding the polymeric composition, or both; the admixing step includes a step of mixing the thermoplastic polyolefin with at least a portion of either the filler concentrate or the reinforcement concentrate.
  • Yet another aspect of the invention is directed at a molded part having at least one section containing a polymeric composition as described herein.
  • a further aspect of the invention is directed at a molded part having at least one section which is molded according to a process described herein.
  • FIG. 1A is a perspective view of an exemplary article in accordance with an aspect of the present invention.
  • Fig. 1 B is a perspective view of another exemplary article in accordance with an aspect of the present invention.
  • Fig. 2 is side view of the exemplary articles in Figs. 1A-1 B in accordance with an aspect of the present invention.
  • Fig. 3 illustrates the relationship between warpage and the difference in fiber length between the skin and the core.
  • Fig. 4 is a perspective view illustrating a warped part on a flat surface being held down on three corners.
  • Fig. 5 illustrates the geometry of the tray and the measurement of the warpage, d, of a part.
  • Fig. 5 is a top view.
  • Fig. 5A is a cross-section of Fig. 5 showing the left edge of the tray.
  • Fig. 5B is a cross-section of Fig. 5 showing the right edge of the tray.
  • Fig. 5C is a cross-section of Fig. 5 showing the rear edge of the tray.
  • Fig. 5D is a cross-section of Fig. 5 showing the front edge of the tray.
  • the present invention is directed to an improved polymeric composition, processes of forming and/or using the composition as well as components or parts formed of the polymeric composition and/or by the processes.
  • the polymeric composition can be employed to form parts or components with desirable characteristics at relatively low cost.
  • the polymeric composition is typically comprised of thermoplastic polyolefin, reinforcement material, filler material, and one or more additives that can include, without limitation, antioxidant, demolding agent, blowing agents, UV additives (e.g., UV absorbers) and stabilizers, amine, amide, combinations thereof or others.
  • the thermoplastic polyolefin can be comprised of one or more thermoplastics, but typically includes polypropylene (PP), polyethylene (PE), the like, or combinations thereof and at least a portion of the thermoplastic typically has a relatively high crystallinity.
  • the reinforcement material can include particles, chopped materials, strands, combinations thereof, or the like.
  • the reinforcement material includes fibers and more preferably includes glass fibers.
  • the filler material can include one or more fillers and preferably includes a mineral filler such as talc, mica, wollastonite, combinations thereof, or the like.
  • the fiber material, the filler material, or both the fiber and filler materials may further include a polymeric material (e.g., the fiber materials may include a first polymeric material and the filler material may include a second polymeric material) having one or more thermoplastic polyolefins (e.g., one or more polypropylenes), one or more elastomers, or both.
  • the polymeric composition can include a variety of polymers such as thermoplastic polymers, elastomers or any combination thereof.
  • thermoplastic polymers can include, without limitation, thermoplastics such as polycarbonates (“PC”), ABS, polypropylene (“PP”), high impact polystyrene (“HIPS”), polyethylene (“PE”), polyester, polyacetyl, thermoplastic elastomers, thermoplastic polyurethanes (“TPU”), polyamide (e.g., Nylon), ionomer (e.g., Surlyn), polyvinyl chloride (“PVC”) and including blends of two or more of these thermoplastics such as PC and ABS.
  • thermoplastics such as polycarbonates (“PC”), ABS, polypropylene (“PP”), high impact polystyrene (“HIPS”), polyethylene (“PE”), polyester, polyacetyl, thermoplastic elastomers, thermoplastic polyurethanes (“TPU”), polyamide (e.g., Nylon), ionomer (e.g., Surlyn), polyvinyl chloride (“PVC”) and including blends of two or more of these thermoplastics
  • the overall polymeric composition that can form a part includes a substantial portion of thermoplastic polyolefin, and more particularly, includes a substantial portion of polypropylene, polyethylene, or both.
  • the thermoplastic polyolefin is substantially entirely polypropylene (e.g., at least about 80 wt.%, 90 wt.%, or more polypropylene based on the total weight of the thermoplastic polyolefin).
  • the polymeric composition typically includes at least about 10% although possibly less, more typically at least about 45% and still more typically at least about 60% by weight of the thermoplastic polyolefin.
  • the polymeric composition also typically includes less than about 95% although possibly more, more typically less than about 90% and possibly less than about 85% by weight of the thermoplastic polyolefin.
  • the polymeric composition typically includes at least about
  • the polymeric composition also typically includes less than about 50% and possibly less than about 30% of the reinforcement material.
  • the polymeric composition also typically includes at least 3% although possibly less, more typically at least 10% and even possibly at least about 15% by weight of the filler material.
  • the polymeric composition also typically includes less than about 35% and possibly less than about 25% by weight of the filler material based on the total weight of the polymeric composition.
  • the polymeric composition may typically include at least about 2% although possibly less, more typically at least about 5% and still more typically at least about 10% by weight of the elastomer.
  • the polymeric composition also typically includes less than about 30% and possibly less than about 20% by weight of the elastomer, when included.
  • the thermoplastic polyolefin and particularly the one or more polypropylenes can be co-polymers, homopolymers, or both. However, it is additionally contemplated that such terms and such material can allow for some degree of impurity which is typically less that 5%, more typically less than 2% and even more typically less that 0.8% by weight of whichever ingredient is specified.
  • thermoplastic polyolefin of the polymeric composition is typically relatively highly crystalline.
  • the thermoplastic polyolefin will typically be comprised of ingredients (e.g., polypropylene, polyethylene, the like, or combinations thereof) present at a concentration of at least 10% but possibly less, more typically at least 50%, and still more typically at least about 60%, but typically less than 90%, although possibly more by weight of the thermoplastic polyolefin.
  • the percentage of crystallinity of the ingredients in the thermoplastic polyolefin may vary (e.g., higher or lower) depending on the application.
  • Patent No. 6,403,692 incorporated by reference (see e.g., 6,403,692, column 2, lines 30-58) is well known in the literature and can be prepared by known techniques.
  • the polypropylene is in the isotatic form, although other forms can also be used (e.g., syndiotatic or atatic).
  • the polypropylene used for the present invention is preferably a homopolymer of polypropylene or a copolymer, for example, a random or block copolymer, of propylene and an ⁇ -olefin, preferably a C 2 , or C 4 to C 2 o ⁇ -olefin.
  • the ⁇ -olefin is present in the polypropylene of the present invention in an amount of not more than 20 percent by mole, preferably not more than 15 percent, even more preferably not more than 10 percent and most preferably not more than 5 percent by mole.
  • Examples of the C 2 , or C 4 to C 20 ⁇ -olefins for constituting the propylene and ⁇ -olefin copolymer include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1- octene, 1-decene, 1-dodecene, 1-hexadodecene, 4-methyl- 1-pentene, 2-methyl-1- butene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, diethyl-1-butene, trimethyl-1-butene, 3-methyl-1-pentene, ethyl-1-pentene, propyl-1-pentene, dimethyl-1-pentene,
  • Percent crystallinity is measured by differential scanning calorimetry, according to ASTM D3417.
  • a milligram size sample of polymer is sealed into an aluminum DSC pan.
  • the sample is placed into a DSC cell with a 25 cubic centimeter per minute nitrogen purge and cooled to -100 0 C.
  • a standard thermal history is established for the sample by heating at 10°C/minute to 225 0 C.
  • the sample is then cooled (at 10° C/minute) to -100 0 C and reheated at 10 °C/minute to 225 0 C.
  • the observed heat of fusion for the second scan is recorded ( ⁇ H observed ).
  • the observed heat of fusion is related to the degree of crystallinity in weight percent based on the weight of the polypropylene sample by the following equation:
  • %Crystallinity AH ' ⁇ ⁇ 1 x 100 ,
  • a high degree of crystallinity is at least about 62 weight percent, more preferably at least about 64 weight percent, even more preferably at least about 66 weight percent, even more preferably at least about 68 weight percent and most preferably at least about 70 weight percent based on the weight of the polypropylene.
  • the degree of crystallinity for the polypropylene as determined by DSC is less than or equal to about 100 weight percent, preferably less than or equal to about 90 weight percent, more preferably less than or equal to about 80 weight percent, and most preferably less than or equal to about 70 weight percent based on the weight of the polypropylene.
  • the relatively high crystallinity portion of the thermoplastic polyolefin and/or the entire thermoplastic polyolefin is comprised of at least 40 wt%, more typically at least 75 wt%, even more typically at least 95 wt% or even substantially entirely or entirely of one or more polypropylenes (e.g., one type of polypropylene or a blend of 2, 3, 4, or more polypropylenes).
  • the thermoplastic polyolefin can comprise one or more lower crystallinity grades of polypropylene, polyethylene, or both (i.e., grades having crystallinity below the relatively highly crystallinity of the polypropylene, polyethylene, or both as discussed above), which may be isotactic, syndiotactic or atactic.
  • the low cryallinity grades may have a crystallinity lower than the crystallinity of the high crystallinity grade.
  • the low crystallinity grades may have a crystallinity less than about 62 wt.% or even less than about 50 wt.%.
  • suitable low crystallinity grades may have a crystallinity less than about 30 wt.%, preferably less than about 20 wt%, and more preferably less than about 15 wt.%, as measured for example by differential scanning calorimetry.
  • such lower crystallinity materials will typically comprise at least about 0.5% but possibly less, more typically at least about 2.0% and even more typically at least about 6%, but typically less than about 40%, although possibly more, more typically less than about 16% and even more typically less than about 10% by weight of the overall polymeric composition.
  • the percentage of crystallinity of polypropylene, polyethylene, or both in the thermoplastic polyolefin may vary (e.g., higher or lower) depending on the application.
  • thermoplastic polyolefin in one preferred embodiment, is comprised in a polyolefin matrix.
  • the thermoplastic polyolefin in the matrix includes a relatively high crystallinity portion.
  • the matrix may include essentially the thermoplastic polyolefin or the thermoplastic polyolefin and one or more ingredients as discussed herein and is configured to be admixed with the reinforcement material, the filler material, the elastomer, or combinations thereof to form the overall polymeric composition.
  • the polyolefin matrix may include the thermoplastic polyolefin, the first polymeric material, and the second polymeric material (as well as any optional polyolefin materials present in the thermoplastic composition).
  • the polyolefin matrix may include a high crystallinity portion greater than about 30 wt.%, preferably greater than about 50 wt.% and more preferably greater than about 60 wt.% based on the total weight of the polyolefin matrix.
  • the polymeric composition includes reinforcement material.
  • the reinforcement material can include strands of material, or otherwise.
  • the reinforcement material may be fiber reinforced or otherwise reinforced with materials such as ceramic, glass (e.g., long glass fibers,), or other fibers.
  • the reinforcement material includes or is substantially entirely of fibers, and more preferably includes or is substantially entirely (e.g., at least about 95% by weight) of long glass fibers.
  • the overall polymeric composition or the parts formed therefrom include fibers (e.g., long fibers) having an average or mean length of approximately greater than about 1 mm, more preferably greater than about 4 mm even more preferably greater than about 6 mm and most preferably between about 8 mm and about 20 mm.
  • fibers e.g., long fibers having an average or mean length of approximately greater than about 1 mm, more preferably greater than about 4 mm even more preferably greater than about 6 mm and most preferably between about 8 mm and about 20 mm.
  • the following process is utilized: Weighing the glass fiber polymer samples including the crucible. The next step is placing the sample (in the crucible) in the oven set at about 550 C (e.g. at about 600 0 C) for 1 hour, (maximum 12 grams of sample). The temperature preferably is lower than a temperature at which sintering of the glass fibres may occur, above which the fiber length measurement may be compromised. Controlling samples for remains of polymer by making a visual inspection of the sample. If any doubts that the polymer remains in the sample, the ashing procedure is repeated. After the second period of ashing, the weight should be the same and the sample is free of the remaining polymer.
  • the samples include a core part surrounded by a skin structure having a depth of 1 mm.
  • the samples are viewed using the Leica QWIN imaging software and are measured by comparing each glass fiber against a material of known length. Pictures of the sample (ashed glass fibers) are taken with a high resolution digital camera. The software then converts the information and calculates the curve length of the fibers (e.g., calculates the distribution of the fiber lengths).
  • the fiber length distribution of the different samples are analyzed taking into account that glass fibers having a length greater than about 1 mm are considered long glass fibers.
  • the difference between the amount of long glass fibers embedded in the core part and the long glass fibers embedded in the skin structure relates to the anisotropy of the sample in the z (thickness) direction.
  • the amount of long glass fibers is generally greater in the core layer (percentage of long glass fibers (LGF) in the core part is greater than the percentage of LGF in the skin structure), the part is generally free of warpage as shown in Fig. 3.
  • LGF long glass fibers
  • the warpage, measured in mm is plotted against the difference in the concentration of long glass fibers in the skin and the core (i.e., the concentration of the LGF in the skin part minus the concentration of LGF in the core part).
  • the percent of LGF in the skin structure is greater than the percent of LGF in the core part, warpage in the part (e.g., tray) becomes increasingly prevalent.
  • the combination of the long glass fibers with filler generally perturbs the flow of the composite material when filling the part.
  • the part may be influenced by the fillers so that the resulting structure of the layers across the thickness of the part tends to reduce warpage.
  • the fiber length distribution of the reinforcement material within the polyolefin composition has been shown to have a significant impact on reducing warpage. Without being bound by theory, it is believed that the interaction between the thermoplastic polyolefin matrix, the filler particles, and the fibers can provide a fiber length distribution across the thickness of the molded articles, which leads to a product with reduced warpage.
  • the filler material can comprise multiple different fillers or one singular filler material.
  • the filler includes or is substantially entirely composed of one or more mineral fillers.
  • suitable filler materials include, without limitation, clay, aramid, calcium carbonate, talc, kaolin, mica, wollastonite, hollow glass beads, titaninum oxide, silica, carbon black, potassium titanate, silicate material, combinations thereof or the like which can take the form of powders, platelets or otherwise.
  • One preferred talc is a powdered talc sold under the tradename Mistron®, which is commercially available from Luzenac.
  • the polymeric composition may further include one or more elastomers, which may be a single elastomer or combination of elastomers. More specifically, the one or more elastomer of the present invention may be a polyolefin elastomer.
  • Suitable polyolefin elastomers comprises one or more C2 to C20 ⁇ -olefins in polymerized form, having a glass transition temperature (Tg) less than about 25 0 C, preferably less than about 0 0 C, most preferably less than about -25°C.
  • Tg is the temperature or temperature range at which a polymeric material shows an abrupt change in its physical properties, including, for example, mechanical strength. Tg can be determined by differential scanning calorimetry.
  • Examples of the types of polymers from which the present polyolefin elastomers are selected include copolymers of ⁇ -olefins, such as ethylene and propylene, ethylene and 1-butene, ethylene and 1-hexene or ethylene and 1-octene copolymers, and terpolymers of ethylene, propylene and a diene comonomer such as hexadiene or ethylidene norbornene.
  • ⁇ -olefins such as ethylene and propylene, ethylene and 1-butene, ethylene and 1-hexene or ethylene and 1-octene copolymers
  • terpolymers of ethylene, propylene and a diene comonomer such as hexadiene or ethylidene norbornene.
  • the elastomer may comprise a variety of elastomers such as a thermoplastic elastomer that may include one or more ⁇ -olefin elastomers (e.g., one or more ethylene ⁇ -olefin elastomers, one or more polypropylene elastomer, or any combination).
  • the elastomer may comprise substantially linear ethylene polymers (SLEPs), linear ethylene polymers (LEPs) or both.
  • the elastomer may be a neat elastomer or a blend.
  • Substantially linear and linear ethylene polymers (SLEPs) are particularly preferred.
  • Substantially linear ethylene polymers and linear ethylene polymers and their method of preparation are fully described in U.S.
  • a linear or substantially linear ethylene polymer means a homopolymer of ethylene or a copolymer of ethylene and one or more ⁇ -olefin comonomers having a linear backbone (i.e. no cross linking), a specific and limited amount of long-chain branching or no long-chain branching, a narrow molecular weight distribution, a narrow composition distribution (e.g., for ⁇ -olefin copolymers) or a combination thereof. More explanation of such polymers is discussed in U.S. Patent 6,403,692, which is incorporated herein by reference for all purposes.
  • Illustrative ⁇ -olefins include propylene, 1-butene, 1-hexene, 4-methyl-1- pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1 -hexadodecene, 4-methyl-1- pentene, 2-methyl-1-butene, 3-methyl-1-butene, 3,3-dimethyl-i-butene, diethyl-1-butene, trimethyl-1-butene, 3-methyl-1-pentene, ethyl-1-pentene, propyl-1-pentene, dimethyl-1- pentene, methylethyl-1-pentene, diethyl-1-hexene, trimethyl-1-pentene, 3-methyl-1- hexene, dimethyl-1-hexene, 3,5,5-trimethyl-i-hexene, methylethyl-1-heptene, trimethyl- 1-heptene
  • the ⁇ -olefin is desirably a C 3 -C 20 or C 3 -C 10 ⁇ -olefin.
  • Preferred copolymers include ethylene/propylene (EP), ethylene/1 -butene (EB), ethylene/1 -hexene (EH) and ethylene/1 -octene (EO) polymers.
  • Illustrative terpolymers include an ethylene/propylene/octene terpolymer as well as terpolymers of ethylene, a C 3 -C 20 ⁇ -olefin and one (or more) diene such as dicyclopentadiene, 1 ,4-hexadiene, piperylene or 5-ethylidene-2-norbomene.
  • the polyolefin elastomers can have densities less than about 0.9 g/cc, melt flow rates of about 0.1 to about 30g/10 min (tested according to ASTM D1238 at 190 0 C, 2.16kg), and more specifically about 0.5 to about 25g/10 min (tested according to ASTM D1238 at 190 0 C, 2.16kg) and can have glass transition temperatures of less than about -30 C, or any combination thereof.
  • Patent No. 5,272,236 (e.g., column 2, lines 41-51 and column 3, lines 25-30) may be characterized as substantially linear olefin polymers having the following novel properties: a) a melt flow ratio, I 1O /I 2 , ⁇ 5.63, b) a molecular weight distribution, M w /M n , defined by the equation:
  • Such a polymer may be an be interpolymers of ethylene with at least one C 3 -C 20 ⁇ - olefin.
  • the melt flow ratio, li ⁇ /l 2 is the ratio of "I 10 " (the melt flow index measured in accordance with ASTM D-1238 (190/10)) and "I 2 " (the melt flow index measured in accordance with ASTM D-1238 (190/2.16).
  • These "substantially linear" polymers may have a polymer backbone that is either unsubstituted or substituted with up to 3 long chain branches/1000 carbons (where a long chain branch contains at least about 6 carbons).
  • Preferred polymers are substituted with about 0.01 long chain branches/1000 carbons to about 3 long chain branches/1000 carbons, more preferably from about 0.01 long chain branches/1000 carbons to about 1 long chain branches/1000 carbons, and especially from about 0.3 long chain branches/1000 carbons to about 1 long chain branches/1000 carbons.
  • the measurement of the polydispersity index of this polymer, as described in U.S. Patent No. 5,272,236 column 5, lines 18-40, is done according to the following technique: The polymers are analyzed by gel permeation chromatography (GPC) on a Waters 150C high temperature chromatographic unit equipped with three linear mixed bed columns (Polymer Laboratories (10 micron particle size)), operating at a system temperature of 140 0 C.
  • the solvent is 1 ,2,4-trichlorobenzene, from which about 0.5% by weight solutions of the samples are prepared for injection.
  • the flow rate is 1.0 milliliter/minute and the injection size is 100 microliters.
  • the molecular weight determination is deduced by using narrow molecular weight distribution polystyrene standards (from Polymer Laboratories) in conjunction with their elution volumes.
  • the equivalent polyethylene molecular weights are determined by using appropriate Mark- Houwink coefficients for polyethylene and polystyrene (as described by Williams and Word in Journal of Polymer Science, Polymer Letters, Vol. 6,(621) 1968, incorporated herein by reference) to derive the equation:
  • Mpolyethylene (a)(M po
  • Mw (R)(W 1 )(M 1 ) where Wj and Mi are the weight fraction and molecular weight respectively of the ith fraction eluting from the GPC column.
  • the critical shear stress at onset of gross melt fracture is measured by a gas extrusion rheometer (GER) as described in U.S. Patent No. 5,272,236 (e.g., column 4, lines 10-45).
  • the gas extrusion rheometer is described by M. Shida, R. N. Shroff and L. V. Cancio in Polymer Engineering Science, Vol. 17, no. 11 , p.
  • the critical shear stress at the OGMF and the critical shear stress at the OSMF for the substantially linear ethylene polymers described herein is greater than about 4 x 10 6 dyne/cm 2 and greater than about 2.8 x 10 6 dyne/cm 2 , respectively.
  • EP Patent No. 0495099 filed December 12, 1989, incorporated by reference herein.
  • EP Patent No. 0495099 describes ethylene copolymers having (a) structural units derived from ethylene and (b) structural units derived from ⁇ -olefin of 3-20 carbon atoms, which are characterized in that they have (i) a density of 0.85-0.92 g/cm 3 ,
  • MFR10/MFR2 a (MFR10/MFR2) ratio of MFR10 under a load of 10 kg to MFR2 under a load of 2.16 kg of 8-50 as measured at 190 0 C.
  • MFR10 and MFR2 may be measured for example, using ASTM D-1238 at 190 0 C with a load of 10kg and 2.16kg respectively.
  • the elastomer may be polymermized using any suitable catalyst system.
  • the elastomer may be polymerized using a catalyst containing a Ziegler- Natta catalyst, a metallocene catalyst, an activated nonmetallocene metal-centered heteroaryl ligand catalyst, and the like. Combinations of catalysts may also be used.
  • one exemplary catalyst is a metallocene catalyst.
  • the elastomer may be polymerized using a catalyst which includes a metallocene catalyst as described in EP Patent Application No. 129368, filed on June 5, 1984 (Ewen et. al.) incorporated herein by reference.
  • Such metallocene may be a compound of the general formula:
  • Me is a Group 4b, 5b, 6b metal
  • (C 5 R' m ) is a cyclopentadienyl or substituted cylcopentadienyl
  • each R' which can be the same or different, is hydrogen, an alkyl, an alkenyl, aryl, alkylaryl, or arylalkyl radical having from 1 to 20 carbon atoms or two R' substituents together form a fused C 4 -C 6 ring
  • R" is a C 1 -C 4 alkylene radical, a dialkyl germanium or silicone, or an alkyl phosphine or amine radical bridging two (C 5 - R' m ) rings
  • each Q which can be the same or different, is aryl, alkyl, alkenyl, alkylaryl, or arylalkyl radical having from 1 to 20 carbon atoms or halogen
  • Q' is an alkylidene radical having from 1 to 20
  • the elastomer may also include or consist essentially of a polypropylene elastomer.
  • Suitable polypropylene elastomers may contain propylene monomer at a concentration greater than about 50 wt.%, preferably greater than about 65 wt.%, more preferably greater than about 70 wt.%, and most preferably greater than about 80 wt.% based on the weight of the polypropylene elastomer.
  • the polypropylene elastomer may also contain one or more additional C 2-I2 ⁇ -olefin comonomers (e.g., a comonomer including ethylene, or consisting of ethylene) at a concentration greater than about 5 wt.%, preferably greater than about 7 wt.%, more preferably greater than about 9 wt.%, and most preferably greater than about 12 wt.% based on the total weight of the polypropylene elastomer.
  • additional C 2-I2 ⁇ -olefin comonomers e.g., a comonomer including ethylene, or consisting of ethylene
  • the comonomer content may range from about 5 to about 40 percent by weight of the polypropylene elastomer composition, more preferably from about 7 to about 30 percent by weight of the polypropylene elastomer composition, and still more preferably from about 9 to about 15 percent by weight of the polypropylene elastomer composition.
  • the polypropylene elastomer may have some crystallinity or may be amorphous.
  • Suitable polypropylene elastomers may have a peak melting temperature less than about 130 0 C, preferably less than about 115 0 C, and most preferably less than about 100 °C, as measured by differential scanning calorimetry at a heating rate of about 10°C/min on a sample which has been cooled from about 220 0 C to about 0 0 C at a rate of about 10°C/min.
  • the polypropylene elastomer may exhibit a Shore A hardness according to ASTM D 2240-05 of at least about 40, more preferably at least about 50, still more preferably at least about 65.
  • the Shore A hardness may also be less than about 97, preferably less than about 92, more preferably less than about 85, still more preferably less than about 80.
  • the polypropylene elastomer may have a Shore A hardness from about 40 to about 92, more preferably from about 50 to about 85, and still more preferably from about 65 to about 80 Shore A.
  • the polypropylene elastomer exhibit at least some crystallinity
  • the crystallinity may be at least about 2, preferably at least about 5, and still more preferably at least about 7 percent by weight of the polypropylene elastomer material.
  • suitable polypropylene elastomers may have a crystallinity less than about 40, preferably less than about 35, more preferably less than about 28, and still more preferably less than about 20 percent by weight of the polypropylene elastomer material.
  • the crystallinity may range from about 2 to about 40, more preferably from about 5 to about 35, and still more preferably about 7 to about 20 percent by weight of the polypropylene elastomer material.
  • propylene elastomers that may be employed in accordance with the present teachings include those disclosed in WO 03/040201 A1 filed on May 6, 2002, published US Application No. 2003-0204017 filed on May 5, 2002, and U.S. Patent No. 6,525,157 issued on February 25, 2003, all of which are incorporated by reference.
  • the propylene elastomer may be a low elasticity ethylene- propylene copolymer (i.e., an LEEP copolymers) taught in U.S. Patent No. 6,525,157 issued on February 25, 2003, incorporated herein by reference.
  • LEEP low elasticity ethylene- propylene copolymer
  • Such an LEEP, as described in U.S. Patent No. 6,525,157 issued on February 25, 2003 from column 2, line 15 to column 3, line 54 may be (LEEP) copolymers that when produced in the presence of a metallocene catalyst and an activator, in a single steady state reactor, show a surprising and unexpected balance of flexural modulus, tensile strength and elasticity.
  • these and other properties of the (LEEP) copolymers show surprising differences relative to conventional polymer blends, such as blends of isotactic polypropylene and ethylene-propylene copolymers.
  • the (LEEP) copolymer includes from a lower limit of
  • the copolymer is substantially free of diene-derived units.
  • features of the (LEEP) copolymers include some or all of the following characteristics, where ranges from any recited upper limit to any recited lower limit are contemplated:
  • a melting point ranging from an upper limit of less than 110° C, or less than 90° C 1 or less than 80° C, or less than 70° C, to a lower limit of greater than 25°
  • M is the 500% tensile modulus in MPa
  • a heat of fusion ranging from a lower limit of greater than 1.0 joule per gram (J/g), or greater than 1.5 J/g, or greater than 4.0 J/g, or greater than 6.0 J/g, or greater than 7.0 J/g, to an upper limit of less than 125 J/g, or less than 100 J/g, or less than 75 J/g, or less than 60 J/g, or less than 50 J/g, or less than 40 J/g, or less than 30
  • a tacticity index m/r ranging from a lower limit of 4 or 6 to an upper limit of 8 or 10 or 12;
  • (xiii) a solid state proton nuclear magnetic resonance ( 1 H NMR) relaxation time of less than 18 milliseconds (ms), or less than 16 ms, or less than 14 ms, or less than 12 ms, or less than 10 ms;
  • MPa or greater than 1.0 MPa, or greater than 2.0 MPa.
  • the LEEP copolymer be made in the presence of a bridged metallocene catalyst, in a single steady-state reactor.
  • Embodiments of the LEEP copolymer are elastic after tensile deformation.
  • the elasticity represented by the fractional increase in the length of the sample, represented as percent of the length of the sample, is measured according to the general procedure ASTM D790. During tensile elongation, the copolymer sample is stretched, and the polymer attempts to recover its original dimensions when the stretching force is removed. This recovery is not complete, and the final length of the relaxed sample is slightly longer than that of the original sample. Elasticity is represented by the fractional increase in the length of the sample, expressed as a percent of the length of the original un-stretched sample.
  • the protocol for measuring the elasticity of the sample consists of prestretching the deformable zone of the dumbbell, made according to the procedure described above for the measurement of elongation and tensile strength, which is the narrow portion of the specimen, to 200% of its original length to prestretch the sample. This is conducted at a deformation rate of 10 inches (25 cm) per minute. The sample is relaxed at the same rate to form an analytical specimen which is a prestretched specimen of the original sample. This slightly oriented, or prestretched, sample is allowed to relax for 48 hours, at room temperature, prior to the determination of elasticity.
  • the length of the deformation zone in the sample is measured to be d ⁇ After the 48 hours, it is again deformed at 10 inches per minute for a 200% extension of the deformation zone of the sample and allowed to relax at the same rate. The sample is removed and after 10 minutes of relaxation the sample is measured to have a new length of the deformation zone of d 2 . The elasticity of the sample as a percent is determined as 100 * (d 2 -d i)/di.
  • Embodiments of the LEEP copolymer may have elasticity, as measured by the procedure described above, of less than 30%, or less than 20%, or less than 10%, or less than 8% or less than 5%.
  • the copolymer of embodiments of the LEEP copolymer should have a measurable tensile strength at 500% elongation (also known as 500% tensile modulus), of greater than 0.5 MPa, or greater than 0.75 MPa 1 or greater than 1.0 MPa, or greater than 2.0 MPa; and second, the copolymer should have the above-described elasticity.
  • the relationship of elasticity to 500% tensile modulus may be described.
  • the elasticity as a function of 500% tensile modulus in MPa is defined by:
  • Softness of the copolymers of embodiments of the LEEP copolymer may be measured by flexural modulus. Flexural modulus is measured in accordance with
  • the values of the flexural modulus over the range of composition of the copolymer vary with the tensile strength of the sample as measured by the 500% tensile modulus.
  • Flexural modulus of this family of copolymers is thus represented by two criteria: (a) extensibility to 500% elongation with a measurable modulus (500% tensile modulus); and (b) flexural modulus.
  • 500% tensile modulus in MPa is defined by:
  • An m/r ratio of 1.0 generally describes a syndiotactic polymer, and an m/r ratio of 2.0 an atactic material.
  • An isotactic material theoretically may have a ratio approaching infinity, and many byproduct atactic polymers have sufficient isotactic content to result in ratios of greater than 50.
  • LEEP copolymers can have a tacticity index m/r ranging from a lower limit of 4 or 6 to an upper limit of 8 or 10 or 12.
  • test method for measuring the molecular weight and polydispersity index of the LEEP copolymer as described in U.S. Patent No. 6,525,157 from column 5, line 1 to 57 includes the following:
  • MWD Molecular weight distribution
  • Mz, Mw and Mn can be measured using gel permeation chromatography
  • GPC size exclusion chromatography
  • SEC size exclusion chromatography
  • the desired MWD function e.g., M w /M n or M z /M w ) is the ratio of the corresponding M values. Measurement of M and MWD is well known in the art and is discussed in more detail in, for example, Slade, P. E.
  • the LEEP copolymer is included having a weight average molecular weight (M w ) of from 15,000-5,000,000, or from 20,000 to 1 ,000,000 and a molecular weight distribution M w /M n (sometimes referred to as a "polydispersity index" (PDI)) ranging from a lower limit of 1.5 or 1.8 to an upper limit of 40 or 20 or 10 or 5 or 3.
  • M w weight average molecular weight
  • M w /M n sometimes referred to as a "polydispersity index" (PDI)
  • the test method for measuring the triad of the LEEP copolymer as described in U.S. Patent No. 6,525,157 from column 6, line 37 to column 7, line 44 is: [0088]
  • An ancillary procedure for the description of the tacticity of the propylene units of the LEEP copolymer is the use of triad tacticity.
  • the triad tacticity of a polymer is the relative tacticity of a sequence of three adjacent propylene units, a chain consisting of head to tail bonds, expressed as a binary combination of m and r sequences.
  • PPP(mm), PPP(mr) and PPP(rr) denote peak areas derived from the methyl groups of the second units in the following three propylene unit chains consisting of head-to-tail bonds:
  • the 13 C NMR spectrum of the propylene copolymer is measured as described in U.S. Pat. No. 5,504,172.
  • the spectrum relating to the methyl carbon region (19-23 parts per million (ppm)) can be divided into a first region (21.2-21.9 ppm), a second region (20.3-21.0 ppm) and a third region (19.5-20.3 ppm).
  • Each peak in the spectrum was assigned with reference to an article in the journal Polymer, Volume 30 (1989), page 1350.
  • the methyl group of the second unit in the three propylene unit chain represented by PPP (mr) resonates, and the methyl group (PPE- methyl group) of a propylene unit whose adjacent units are a propylene unit and an ethylene unit resonates (in the vicinity of 20.7 ppm).
  • the methyl group of the second unit in the three propylene unit chain represented by PPP (rr) resonates, and the methyl group (EPE- methyl group) of a propylene unit whose adjacent units are ethylene units resonates (in the vicinity of 19.8 ppm).
  • the LEEP copolymers have a triad tacticity of three propylene units, as measured by 13 C NMR, of greater than 75%, or greater than 80%, or greater than 82%, or greater than 85%, or greater than 90%.
  • the measurement of the 1 ,3 insertion requires the measurement of the ⁇ y peak.
  • Two structures can contribute to the Uy peak: (1) a 1 ,3 insertion of a propylene monomer; and (2) from a 2,1 -insertion of a propylene monomer followed by two ethylene monomers.
  • This peak is described as the 1.3 insertion peak and we use the procedure described in U.S. Pat. No. 5,504,172, which describes this ⁇ y peak and understand it to represent a sequence of four methylene units.
  • the proportion (%) of the amount of these errors was determined by dividing the area of the ⁇ y peak (resonance in the vicinity of 27.4 ppm) by the sum of all the methyl group peaks and 1/2 of the area of the ⁇ y peak, and then multiplying the resulting value by 100. If an ⁇ -olefin of three or more carbon atoms is polymerized using an olefin polymerization catalyst, a number of inversely inserted monomer units are present in the molecules of the resultant olefin polymer.
  • 2,1 -insertion or 1 ,3-insertion takes place in addition to the usual 1 ,2-insertion, such that inversely inserted units such as a 2,1- insertion or a 1 ,3-insertion are formed in the olefin polymer molecule (see, Macromolecular Chemistry Rapid Communication, Volume 8, page 305 (1987), by K.
  • the proportion of inversely inserted propylene units of LEEP copolymers, based on the 2,1 -insertion of a propylene monomer in all propylene insertions, as measured by 13 C NMR, is greater than 0.5%, or greater than 0.6%.
  • the proportion of inversely inserted propylene units of embodiments of our LEEP copolymers, based on the 1 ,3-insertion of a propylene monomer, as measured by 13 C NMR, is greater than 0.05%, or greater than 0.06%, or greater than 0.07%, or greater than 0.08%, or greater than 0.085 percent.
  • the test method for measuring the reactivity ratios of the LEEP copolymer as described in U.S. Patent No. 6,525,157 from column 11 , lines 10-60 uses monomer sequence distribution. Starting with a polymer having a known average composition, the monomer sequence distribution can be determined using spectroscopic analysis. Carbon 13 nuclear magnetic resonance spectroscopy ( 13 C NMR) can be used for this purpose, and can be used to establish diad and triad distribution via the integration of spectral peaks. (If 13 C NMR is not used for this analysis, substantially lower
  • the reactivity ratio product ri r 2 where T 1 is the reactivity of ethylene and r 2 is the reactivity of propylene, can be calculated from the measured diad distribution
  • K 11 and K 12 are kinetic insertion constants for ethylene
  • K 21 and K 21 are kinetic insertion constants for propylene.
  • a reactivity ratio product r,r 2 of 0 can define an "alternating" copolymer, and a reactivity ratio product of 1 is said to define a "statistically random” copolymer.
  • a copolymer having a reactivity ratio product T 1 T 2 of between 0.6 and 1.5 is generally said to be random (in strict theoretical terms, generally only a copolymer having a reactivity ratio product nr 2 greater than 1.5 contains relatively long homopolymer sequences and is said to be "blocky").
  • the LEEPO copolymers will have a reactivity ratio product T 1 r 2 of less than 1.5, or less than 1.3, or less than 1.0, or less than 0.8.
  • the substantially uniform distribution of comonomer within polymer chains of the LEEP copolymer generally precludes the possibility of significant amounts of propylene units or sequences within the polymer chain for the molecular weights (weight average) disclosed herein.
  • the test method for measuring the intermolecular tacticity of the LEEP copolymer is described in U.S. Patent No. 6,525,157 from column 9, line 42 to column 10, line 15.
  • the LEEP copolymers may have a statistically insignificant intermolecular difference of tacticity of polymerized propylene between different chains (intermolecularly). This is determined by thermal fractionation by controlled dissolution generally in a single solvent, at a series of slowly elevated temperatures. A typical solvent is a saturated hydrocarbon such as hexane or heptane. These controlled dissolution procedures are commonly used to separate similar polymers of different crystallinity due to differences in isotactic propylene sequences, as shown in the article in Macromolecules, Vol. 26, p2064 (1993). For the LEEP copolymers where the tacticity of the propylene units determines the extent of crystallinity, we expected this fractionation procedure will separate the molecules according to tacticity of the incorporated propylene.
  • At least 75% by weight, or at least 80% by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight, or at least 97% by weight, or at least 99% by weight of the copolymer is soluble in a single temperature fraction, or in two adjacent temperature fractions, with the balance of the copolymer in immediately preceding or succeeding temperature fractions.
  • These percentages are fractions, for instance in hexane, beginning at 0 C and the subsequent fractions are in approximately 8 0 C increments above 23°C Meeting such a fractionation requirement means that a polymer has statistically insignificant intermolecular differences of tacticity of the polymerized propylene.
  • the R 2 for polypropylene (control) and an exemplary LEEP copolymer are 0.9945 and 0.9967, respectively. Therefore, the T 1p relaxation for both polypropylene homopolymer and an exemplary LEEP copolymer can be well fitted by a single-exponential. From the fit, the T 1p of polypropylene and LEEP copolymer, are calculated as 25 milliseconds (ms) and 8.7 ms, respectively. The large difference in the T 1p is reflective of their difference in morphology. [00110] The hypothetical polypropylene-like regions would have T 1p relaxation similar to that in polypropylene homopolymer.
  • T 1p 25 ms
  • the T 1 p , relaxation time can be less than 18 ms, or less than 16 ms, or less than 14 ms, or less than 12 ms, or less than 10 ms.
  • NMR Nuclear Magnetic Resonance
  • X is the ratio of the peak height at 1155 cm “1 to peak height at either 722 cm '1 or 732 cm “1 , which ever is higher.
  • propylene elastomer which may be used is a region-error containing propylene-ethylene copolymer (i.e., a R-EPE copolymer) as described in U.S. Patent Application Publication No. 2003/0204017 (published October 30, 2003).
  • the R-EPE copolymers may be characterized as comprising at least about 60 weight percent (wt %) of units derived from propylene, about 0.1-35 wt % of units derived from ethylene, and 0 to about 35 wt % of units derived from one or more unsaturated comonomers, with the proviso that the combined weight percent of units derived from ethylene and the unsaturated comonomer does not exceed about 40.
  • copolymers are also characterized as having at least one of the following properties: (i) 13 C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity, (ii) a B- value greater than about 1.4 when the comonomer content, i.e., the units derived from ethylene and/or the unsaturated comonomer(s), of the copolymer is at least about 3 wt %, (iii) a skewness index, S 1x , greater than about -1.20, (iv) a DSC curve with a T me that remains essentially the same and a T max that decreases as the amount of comonomer, i.e., the units derived from ethylene and/or the unsaturated comonomer(s), in the copolymer is increased, and (v) an X-ray diffraction pattern that reports more gamma-form crystals than a
  • the sample is prepared by adding approximately 3 mL of a 50/50 mixture of tetrachloroethane-d2/orthodichlorobenzene that is 0.025M in chromium acetylacetonate (relaxation agent) to 0.4 g sample in a 10 mm NMR tube.
  • the headspace of the tube is purged of oxygen by displacement with pure nitrogen.
  • the sample is dissolved and homogenized by heating the tube and its contents to 150 C C. with periodic refluxing initiated by heat gun.
  • the skewness index of the R-EPE copolymer is related to the shape of the curve for the temperature-rising elution fractionation test and can be determined using the method described in U.S. Patent Application Publication No. 2003/0204017 (published October 30, 2003) paragraphs 112-116:
  • the determination of crystallizable sequence length distribution can be accomplished on a preparative scale by temperature-rising elution fractionation (TREF).
  • the relative mass of individual fractions can be used as a basis for estimating a more continuous distribution.
  • This scaled down version, analytical temperature-rising elution fractionation (ATREF) is not concerned with the actual isolation of fractions, but with more accuractely determining the weight distribution of fractions.
  • TREF was originally applied to copolymers of ethylene and higher ⁇ -olefins, it can also be used for the analysis of copolymers of propylene with ethylene (or higher ⁇ -lefins).
  • the analysis of copolymers of propylene requires higher temperatures for the dissolution and crystallization of pure, isotactic polypropylene, but most of the copolymerization products of interest elute at similar temperatures as observed for copolymers of ethylene.
  • the following table is a summary of conditions used for the analysis of copolymers of propylene. Except as noted the conditions for TREF are consistent with those of Wild, et al., ibid, and Hazlitt, Journal of Applied Polymer Science: Appl. Polym. Symp., 45, 25(1990).
  • the data obtained from TREF are expressed as a normalized plot of weight fraction as a function of elution temperature.
  • the separation mechanism is analogous to that of copolymers of ethylene, whereby the molar content of the crystallizable component (ethylene) is the primary factor that determines the elution temperature.
  • ethylene crystallizable component
  • copolymers of propylene it is the molar content of isotactic propylene units that primarily determines the elution temperature.
  • FIG. 5 is a representation of the typical type of distribution one would expect for a propylene/ethylene copolymer made with a metallocene polymer and an example of the R-EPE copolymer.
  • the shape of the metallocene curve in FIG. 5 is typical for a homogeneous copolymer. The shape arises from the inherent, random incorporation of comonomer. A prominent characteristic of the shape of the curve is the tailing at lower elution temperature compared to the sharpness or steepness of the curve at the higher elution temperatures. A statistic that reflects this type of assymetry is skewness. Equation 1 mathematically represents the skewness index, S 1x , as a measure of this asymmetry.
  • T max> is defined as the temperature of the largest weight fraction eluting between 50 and 90 0 C in the TREF curve.
  • T 1 and w are the elution temperature and weight fraction respectively of an abitrary, i th fraction in the TREF distribution.
  • the distributions have been normalized (the sum of the W 1 equals 100%) with respect to the total area of the curve eluting above 30 0 C.
  • the index reflects only the shape of the crystallized polymer and any uncrystallized polymer (polymer still in solution at or below 3O 0 C) has been omitted from the calculation shown in Equation 1.
  • DSC Differential scanning calorimetry
  • DSC Differential Scanning Calorimetry
  • the heat of fusion and the onset of melting of the indium sample are determined and checked to be within 0.5 0 C. from 156.6 0 C. for the onset of melting and within 0.5 J/g from 28.71 J/g for the heat of fusion. Then deionized water is analyzed by cooling a small drop of fresh sample in the DSC pan from 25 C° to -30 0 C at a cooling rate of 10 °C/min. The sample is kept isothermally at -30 0 C for 2 minutes and heated to 30 0 C at a heating rate of 10 °C/min. The onset of melting is determined and checked to be within 0.5 0 C from 0 0 C.
  • the polypropylene samples are pressed into a thin film at a temperature of 190 0 C.
  • About 5 to 8 mg of sample is weighed out and placed in the DSC pan.
  • the lid is crimped on the pan to ensure a closed atmosphere.
  • the sample pan is placed in the DSC cell and the heated at a high rate of about 100 °C/min to a temperature of about 30 0 C above the melt temperature.
  • the sample is kept at this temperature for about 3 minutes.
  • the sample is cooled at a rate of 10 °C/min to -40 0 C, and kept isothermally at that temperature for 3 minutes. Consequently the sample is heated at a rate of 10 °C/min until complete melting.
  • High B-value and similar terms mean the ethylene units of a copolymer of propylene and ethylene, or a copolymer of propylene, ethylene and at least one unsaturated comonomer, is distributed across the polymer chain in a nonrandom manner.
  • B-values range from 0 to 2 with 1 designating a perfectly random distribution of comonomer units. The higher the B-value, the more alternating the comonomer distribution in the copolymer. The lower the B-value, the more blocky or clustered the comonomer distribution in the copolymer.
  • the high B-values of the R-EPE copolymers are typically at least about 1.3, preferably at least about 1.4, more preferably at least about 1.5 and most preferably at least about 1.7.
  • B-values can be calculated for other copolymers in an analogous manner by assignment of the respective copolymer diads. For example, calculation of the B-value for a propylene/1 - octene copolymer uses the following equation: f(EO+PO)
  • the B-values are typically between 1.1 and 1.3.
  • the B-values are typically between 0.9 and 1.0.
  • the B- values of the R-EPE copolymers, typically made with an activated nonmetallocene, metal-centered, heteroaryl ligand catalyst are above about 1.4, typically between about 1.5 and about 1.85.
  • the elastomer typically at least 50%, although possibly less, more typically at least about 70% and even more typically at least about 90% by weight of the elastomer is comprised of one or more of the above discussed polyolefin elastomers (e.g., a SLEP, a LEP, a polypropylene elastomer, or any combination thereof). It is also contemplated that the elastomer may be entirely, substantially entirely or consist essentially of one or more of the SLEPs 1 LEPs or a combination thereof as discussed herein.
  • the elastomer may be entirely, substantially entirely or consist essentially of one or more of the SLEPs 1 LEPs or a combination thereof as discussed herein.
  • Examples of a suitable material that includes or consists essentially of an SLEP or an LEP elastomer are commercially available from The Dow Chemical Company under the designation of ENGAGE® (e.g., including EG- 8100, EG-8150 and/or EG-8200).
  • Examples of a suitable polypropylene elastomer include commercially available elastomers available from Dow Chemical Company under the designation of VERSIFYTM and from ExxonMobil Chemical Company under the designation of Vl STAM AXX TM.
  • the polymeric composition can include a variety of other additives such as surfactants, flexibilizers, ignition resistant additives, stabilizers, colorants, antioxidants, antistats, slip-aids (i.e., slip resistance aid), flow enhancers, nucleating agents, including clarifying agents, etc.
  • additives such as surfactants, flexibilizers, ignition resistant additives, stabilizers, colorants, antioxidants, antistats, slip-aids (i.e., slip resistance aid), flow enhancers, nucleating agents, including clarifying agents, etc.
  • additives may be added to the polymeric composition such that the parts or components are "molded-in-color.”
  • Preferred examples of additives are ignition resistance additives, such as, but not limited to halogenated hydrocarbons, halogenated carbonate oligomers, halogenated diglycidyl ethers, organophosphorous compounds, fluorinated olefins, antimony oxide and metal salts of aromatic sulfur, or a mixture thereof may be used.
  • compounds which stabilize thermoplastic compositions against degradation caused by, but not limited to heat, light, and oxygen, or a mixture thereof may be used.
  • antioxidant which, when included, is typically included in a relatively small weight percentage of the overall polymeric composition (e.g., less than about 1 or 2 percent).
  • One preferred antioxidant is IRGANOX B225 antioxidant commercially available from Ciba Specialy Chemicals Corporation.
  • Irganox B225 antioxidant is a blend of 1 part Irganox 1010 antioxidant (Tetrakis(methylene(3,5-di-t-butyl-4- hydroxyhydrocinnamate))methane) and 1 part lrgafos 168 tris(2,4-t-butylphenyl) phosphite.
  • Another preferred additive is a demolding agent (e.g., a wax, mold relief or slip-aid).
  • One preferred demolding agent is a nitrogen or ammonia group containing compound such as an amine or an amide.
  • One preferred amide containing compound is ethylene bisstearamide (EBS).
  • Another preferred category of mould release agents is "stearates" such as Glycerol MonoStearate commercially available from Danisco or Ciba Specialty Chemicals under the tradename Atmer.
  • One preferred nitrogen containing compound, which is a wax is an erucamide sold under the tradename KENAMIDE ULTRA E, commercially available from Chemtura Corporation, Middlebury, Connecticut.
  • the composition may include various additives such as UV absorber, neutralizing agent, blowing agent, foam inhibitor, and crosslinking agent.
  • additives such as UV absorber, neutralizing agent, blowing agent, foam inhibitor, and crosslinking agent.
  • additional various additives may be included in the composition such as copper inhibitor, plasticizer, and foaming agent.
  • Such additives may be incorporated into the composition physically, chemically, or both physically and chemically.
  • Physical blowing agents typically undergo a physical change to form a foamed product. For example, a physical change may occur by converting a liquid to a gas under the influence of heat.
  • One such physical blowing agent such as water, the like, or otherwise, forms a gas upon boiling the water.
  • Chemical blowing agents are stable at normal temperatures and (typically) undergo a decomposition reaction at a certain temperature to produce the gas that forms the cells in the foamed part.
  • types of chemical blowing agents may include nitrogen containing compounds, acids such as citric acid, the like, or otherwise.
  • the various components of the polymeric composition can be admixed and/or compounded according to a variety of protocols. Preparation of the filled polymeric composition of this invention can be accomplished using a variety of techniques. The ingredients may be mixed using an extruder or any of a variety of commercially available mixers.
  • the filled thermoplastic compositions of this invention can be fabricated into articles using conventional techniques such as compression molding, injection molding, gas assisted injection molding, thermoforming, extrusion and/or blow molding, alone or in combination.
  • the filled thermoplastic compositions can also be formed multi-layer laminates or extruded sheets, or can be compounded with one or more organic or inorganic substances, on any machine suitable for such purpose.
  • the filled thermoplastic compositions of the present invention are preferably injection molded.
  • the ingredients of the polymeric composition are combined in such a manner that one or more ingredients are compounded together to form a first admixture, then compounding the remaining ingredients to form a second admixture followed by compounding the first admixture with the second admixture to form the polymeric composition.
  • the first admixture could be formed of the reinforcement material and the lower crystallinity thermoplastic polyolefin to form a reinforcement concentrate.
  • the second admixture could be formed of the filler and the high crystallinity polyolefin to form a thermoplastic polyolefin matrix.
  • thermoplastic polyolefin matrix may further include the elastomer such as a polyolefin elastomer (e.g., ENGAGE), the demolding agent (e.g., the erucamide wax), the antioxidant, or any combination thereof.
  • the highly crystallinity thermoplastic polyolefin matrix may further include an additive (such as the demolding agent (e.g., the erucamide wax), the antioxidant, the UV additives, the heat stabilizers, the like, or otherwise).
  • the reinforcement concentrate may be combined (e.g., melt mixed or blended) with the thermoplastic polyolefin matrix at a later time such as at the molding of the article (e.g., during or just prior to injection molding of the polymeric composition).
  • the ingredients of the polymeric composition are combined in such a matter that the one or more ingredients are compounded to form a plurality of admixtures to be compounded with a high crystallinity thermoplastic polyolefin matrix.
  • the first admixture could be formed of the reinforcement material and a thermoplastic polyolefin to form a reinforcement concentrate.
  • the second admixture could be formed of the filler and a thermoplastic polyolefin or combination of thermoplastic polyolefins and elastomer to form a filler concentrate.
  • the thermoplastic polyolefin matrix may further include an additive (such as the demolding agent, the antioxidant, the like, or otherwise).
  • the reinforcement concentrate and the filler concentrate may be combined (e.g., melt mixed or blended) separately or simultaneously with the thermoplastic polyolefin matrix at a later time such as at the molding of the article (e.g., during or just prior to injection molding of the polymeric composition).
  • the present invention mixes a reinforcement concentrate with a mineral filler filled thermoplastic polyolefin compound on a molding machine to achieve a low warpage molded article.
  • the reinforcement material may be introduced by way of a reinforcement concentrate that includes the reinforcement material in a thermoplastic polyolefin and more specifically, the reinforcement concentrate includes fibers (e.g., glass fibers) in PP.
  • the reinforcement concentrate includes at least about 40%, more typically at least about 60%, and even possibly, at least about 85% by weight of the reinforcement material (e.g., fibers), and particularly long glass fibers.
  • Suitable reinforcement concentrates may contain from about 30 to about 95% by weight, preferably from about 50 wt.% to about 90 wt.% of the reinforcement material.
  • the physical properties of the part thus achieved are comparable with a PP part having the same amount of long glass fibers content with the exception of having higher stiffness and/or improved impact performance.
  • glass fibers having a fiber length of at least about 1 mm are considered to be long glass fibers.
  • the initial reinforcement concentrate may include long glass fibers having an average length of approximately greater than about 1 mm, preferably greater than about 5 mm, more preferably greater than about 7 mm, even more preferably greater than about 10 mm and most preferably between about 7 mm and about 25 mm.
  • the filler may be included in the bulk polyolefin matrix or may be introduced by way of a filler concentrate that includes the filler in a thermoplastic polyolefin.
  • the filler concentrate includes at least about 40%, more typically at least about 60%, and even more typically, at least about 90% by weight mineral filler, particularly talc.
  • the elastomer when used, will typically be present in an amount less than 30%, more typically less than about 20%, and even more typically, less than about 10% by weight of the reinforcement concentrate, the filler concentrate, or both.
  • the reinforcement concentrate, the filler concentrate, the polyolefin matrix, or combinations thereof may be admixed in various orders. It is further contemplated that the reinforcement concentrate, the filler concentrate, the polyolefin matrix, or combinations thereof, may be separately fed through two or more feeds to a molding machine.
  • the process e.g., the molding process
  • the polymeric composition, or both may achieve reduced warpage behavior in a molded part while maintaining existing property behavior as defined by impact resistance, Heat Distortion Temperature (thermal resistance), or both while still using standard molding equipment.
  • stiffness properties may be increased without reducing the impact performance, thereby enhancing the impact/stiffness balance.
  • thermoplastic polyolefin e.g., low warpage and other discussed herein or otherwise
  • reinforcement material e.g., reinforcement material, filler, and optionally polyolefin elastomer, particularly if those ingredients are chosen appropriately without the need for grafted polymers.
  • polymeric composition of the present invention can be substantially with or without any grafted polymers or may consist essentially of non-grafted polymers. It is also contemplated, however, that such ingredients can be included in the polymeric composition unless otherwise indicated.
  • the polymeric composition of the present invention can be employed in forming parts of a variety of articles of manufacture.
  • it can be used in forming articles such as a tray, a table, a plate, an appliance housing, a freezer container; lawn and garden furniture, building and construction sheets, a shoe, a boot, an outer ski boot shell, or an outer skate shell, snow mobile cowling or body cover, a personal water craft cowling or body cover, an all terrain vehicle cowling, fender, panel or body cover, an electrical equipment device housing, or the like.
  • articles such as a tray, a table, a plate, an appliance housing, a freezer container; lawn and garden furniture, building and construction sheets, a shoe, a boot, an outer ski boot shell, or an outer skate shell, snow mobile cowling or body cover, a personal water craft cowling or body cover, an all terrain vehicle cowling, fender, panel or body cover, an electrical equipment device housing, or the like.
  • the polymeric composition may also be used to form automotive parts such as a panel, fascia (e.g., bumper fascia), automotive trim, door modules, closures, tailgates, front end carrier, body under the hood, automotive cowling, console (e.g., center overhead and/or floor assemblies) bumper beam, pillar, instrument panel, glove box assemblies including doors, knee bolster assemblies or instrument panel retainer assemblies or structural components.
  • fascia e.g., bumper fascia
  • automotive trim e.g., door modules, closures, tailgates, front end carrier, body under the hood, automotive cowling, console (e.g., center overhead and/or floor assemblies) bumper beam, pillar, instrument panel, glove box assemblies including doors, knee bolster assemblies or instrument panel retainer assemblies or structural components.
  • the process for molding the parts may provide freedom to adjust the level of filler and/or elastomer to a bulk thermoplastic polyolefin matrix independently of the level of reinforcement material to achieve reduced warpage or warpage free parts.
  • the polymeric composition was molded to form trays 10 and 12 as illustrated in Figs. 1A, 1B 1 and 2, wherein tray 10 includes a top surface 14, a front edge 16, a rear edge 18, and left and right edges 20 and 22, respectively.
  • tray 12 includes a top surface 24, a front edge 26, a rear edge 28, and left and right edges 30 and 32, respectively.
  • Tray 10 seen in a perspective view in Fig. 1A and in a frontal view on the left side of Fig. 2, is seen to be generally flat and having a low warpage.
  • Tray 12 seen in a perspective view in Fig. 1B and in a frontal view on the right side of Fig. 2, is seen to be warped and nonplanar.
  • T it will be understood that, whatever part or article is formed from the polymeric composition of the present invention, ingredients may be added to tailor the material to a particular use (e.g., it may be desirable to add a UV stabilizer to the material when used to form an exterior component of a vehicle).
  • Materials resulting from the teachings herein will have any combination of at least one, two (and more specifically at least 3 or all) of the following properties; namely, an E Modulus (ISO 527-2) that ranges from about 3000 to about 11 ,000 MPa, more specifically about 4000 to about 8000 MPa; an elongation at break that ranges from about 1.0 to about 4.0 %, more specifically about 2.0 to about 3.0 %; a notched Izod (ISO 180-1 A @ 23 0 C) that ranges from about 5 to about 40; more specifically, from about 15 to about 30; a notched Izod (ISO 180-1 A @ -3O 0 C) that ranges from about 5 to about 45; a notched Izod (@ -4O 0 C) that ranges from about 10 to about 20; a flexural modulus ISO 178 that ranges from about 3000 to about 11000 MPa, more specifically, from about 4000 to 8000 MPa; heat distortion under load (ISO 527
  • the warpage may be measured on injection molded trays having a wall thickness of about 3 mm and a dimension of about 395 mm x 245 mm x 25 mm, which are, for example, injection molded with a center cold sprue gate.
  • Fig. 4 shows a perspective of a warped tray 10 placed on a flat surface 6 and held in place on three corners by a force, F.
  • the geometry of the tray 10 is shown in Fig. 4 and Fig. 5.
  • the measurement of the warpage is illustrated in Figs. 5, 5A, 5B, 5C, and 5D.
  • Fig. 5 is a top view of the tray 10 on a surface 6.
  • FIG. 5A is a cross section of Fig..5, through line A-A showing the left edge 20 of the tray 10.
  • Fig. 5B is a cross section of Fig..5, through line B-B showing the right edge 22 of the tray 10.
  • Fig. 5C is a cross section of Fig..5, through line C-C showing the rear edge 18 of the tray 10.
  • Fig. 5D is a cross section of Fig..5, through line D-D showing the front edge 16 of the tray 10.
  • Warpage, d is quantified for the reinforced products by fixing three of the four corners to a flat (i.e., planar) surface 6 and measuring the distance along a line normal to the surface between the 4 th corner (i.e. the free corner) and the flat surface. As seen in Fig.
  • the distortion of the part 10 is measured to be approximately 50 mm from the reference surface.
  • the warpage of the part 12 molded from the LGF concentrate diluted into a talc filled polypropylene, such as INSPIRE DTF3800.00S (containing about 30 wt.% talc, about 20 wt.% elastomer and about 50 wt.% polypropylene and having a flexural modulus of about 1800 MPa). is measured to be approximately zero, as given by Example 1 (EX.1 ) in Table I.
  • the warpage of the part molded from the LGF concentrated diluted in a talc filled polypropylene containing about 22 wt.% talc and about 78 wt.% polypropylene (and having a flexural modulus of about 2300 MPa) is measured to be about 23 mm, as given by Example 2 (EX.2( in Table I.
  • Suitable polymeric material may have warpage measured according to this technique of less than about 30 mm, more typically, less than about 20 mm, even more typically less than about 5 mm, or even less than about 2 mm.
  • the comparative example, (C.E.1 ) shown in Table I has a warpage greater than about 30 mm (e.g., about 52.5 mm).
  • the polymeric system comprises of long glass fibers and a filler/elastomer compounded with a PP matrix results in equivalent impact and thermal behavior (e.g., the heat distortion temperature) to the systems based only on long glass fiber in PP, thereby indicating that the presence of a mineral filler in combination with additional rubber does not effect the stiffness performance of the polymeric composition.
  • the modulus values of Examples 1 and 2 are significantly higher than the modulus values of C.E.1 , for example, approximately 20% higher.
  • Comparative Example 2 (CE.2) is prepared by mixing a concentrate
  • LGF concentrate 60 (containing about 60 wt.% long glass fibers in polypropylene) with a polypropylene copolymer having a flexural modulus of about 1450 MPa.
  • the formulation and properties of the compound are shown in Table II.
  • Examples 3-6 are prepared by mixing the LGF concentrate 60 and the polypropylene copolymer used in comparative example 2 with a talc concentrate containing about 70 wt.% talc and about 30 wt% elastomer (e.g., a blend of about 15 wt.% ethylene elastomer and about 15 wt.% polypropylene elastomer and about 70 wt.% talc).
  • CE. 2 and EX. 3-6 all contain about 20 wt.% long glass fiber.
  • CE. 2 is free of talc
  • EX. 3-6 contain from about 8 wt.% to about 20 wt.% talc as shown in Table II.
  • the warpage is measured using the tray warpage test given for EX. 1 and
  • CE. 1 The warpage of CE. 2 and EX.3-6 are shown in Table II. The addition of talc and elastomer reduces the warpage. TABLE Il
  • Comparative Example 3 (C.E.3) is prepared by mixing a concentrate,
  • LGF concentrate 60 (containing about 60 wt.% long glass fibers in polypropylene) with a polypropylene copolymer having a flexural modulus of about 1450 MPa.
  • the formulation and properties of the compound are shown in Table III.
  • Examples 7-10 are prepared by mixing the LGF concentrate 60 and the polypropylene copolymer used in comparative example 3 with a talc concentrate containing about 70 wt.% talc and about 30 wt% elastomer (e.g., a blend of about 15 wt.% ethylene elastomer, about 15 wt.% polypropylene elastomer and about 70 wt.% talc).
  • CE. 3 and EX. 7-10 all contain about 30 wt.% long glass fiber.
  • CE. 2 is free of talc
  • EX. 3-6 contain from about 8 wt.% to about 20 wt.% talc as shown in Table
  • CE. 1 The warpage of CE. 3 and EX.7-10 are shown in Table III. The addition of talc and elastomer reduces the warpage.
  • Comparative Example 4 (CE.4) is prepared by mixing a concentrate,
  • LGF concentrate 60 (containing about 60 wt.% long glass fibers in polypropylene) with a polypropylene copolymer having a flexural modulus of about 1450 MPa.
  • the formulation and properties of the compound are shown in Table IV.
  • Examples 11-14 (EX.11-14) are prepared by mixing the LGF concentrate
  • talc concentrate containing about 70 wt.% talc and about 30 wt% elastomer (e.g., a blend of about 15 wt.% ethylene elastomer, about 15 wt.% polypropylene elastomer, and about
  • CE. 4 and EX. 7-10 all contain about 40 wt.% long glass fiber.
  • CE. 2 is free of talc, whereas EX. 3-6 contain from about 5 wt.% to about 13 wt.% talc as shown in Table IV.
  • CE. 1 The warpage of CE. 4 and EX.11-14 are shown in Table IV. The addition of the talc and the elastomer reduces the warpage.

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Abstract

The present invention is directed to a polymeric composition, particularly a thermoplastic material that includes one or more thermoplastic polyolefins, a glass fiber material, and a filler material.

Description

A POLYMERIC COMPOSITION AND METHOD FOR MAKING LOW WARPAGE, FIBER REINFORCED PARTS THEREFROM
CLAIM OF PRIORITY
[0001] The present application claims the benefit of U.S. Provisional Patent
Application Nos. 60/973,232 (filed on September 18, 2007) and 61/012,088 (filed on December 7, 2007) which are both hereby incorporated by reference in their entirety for all purposes.
TECHNICAL FIELD
[0002] The present invention relates to a polyolefin composition and a process for forming and/or using the same. More particularly, the present invention relates to a thermoplastic material that is a blend of thermoplastic polyolefin and reinforcement material (e.g., glass fiber), and filler, elastomer, or both and to a process of forming and/or using the same.
BACKGROUND OF THE INVENTION
[0003] Much effort has been put into forming polymeric compositions that exhibit desirable properties, lower costs, or both. Examples of prior polymeric compositions and processes of forming those compositions are discussed in: U.S. Patent Nos. 6,300,419; 6,869,993; 6,967,225; 6,734,253; 6,177,515; 6,251 ,997; 6,329,454; 6,689,841; 6,403,692 and U.S. Patent Publication 2006/0058434 all of which are hereby expressly incorporated by reference for all purposes.
[0004] Still, it remains desirable to provide a polymeric composition, particularly, a thermoplastic polyolefin composition that exhibits desirable characteristics such as little or no warpage, strength durability, ductility, or any combination thereof without the need to employ costly ingredients, processes, or the like. For example, it may be desirable to avoid the use of relatively high cost or highly processed (e.g., grafted) polymers, specialty fillers or agents, or other additional or alternative relatively costly ingredients, processes or the like while still maintaining desirable characteristics.
SUMMARY OF THE PRESENT INVENTION
[0005] A first aspect of the invention is directed at a polymeric composition for the manufacture of a shaped plastic article, comprising: a reinforcement concentrate including an admixture of at least one reinforcement material and a first polymeric material, a filler concentrate including an admixture of a filler and a second polymeric material; and a thermoplastic polyolefin; wherein the polymeric composition has a highly crystalline portion having a crystallinity of at least about 62 wt.%, wherein the highly crystalline portion of the polymeric composition is present at a concentration of at least about 30% by weight based on the total weight of the first polymeric material, the second polymeric material and the thermoplastic polyolefin.
[0006] This aspect of the invention may further be characterized by one or any combination of the following: the reinforcement material includes long glass fibers having an average fiber length greater than about 1 mm; the reinforcement material is present at a concentration of at least about 40 wt.% based on the total weight of the reinforcement concentrate; the filler is selected from the group consisting of talc, mica, and wollastonite; the filler is present at a concentration of at least about 40 wt.% based on the total weight of the filler concentrate; the filler is present at a concentration of at least about 60 wt.% based on the total weight of the filler concentrate; the filler includes talc; the first polymeric material, the second polymeric material, or both the first and second polymeric materials includes an elastomer, a polyethylene homopolymer, a polyethylene copolymer, a polypropylene homopolymer, a polypropylene copolymer, or any combination thereof; the thermoplastic polyolefin is formed of a polyethylene homopolymer, a polyethylene copolymer, a polypropylene homopolymer, a polypropylene copolymer, or any combination thereof; the reinforcement concentrate includes from about 30 to about 95% by weight of the at least one reinforcement material; the polymeric composition includes from about 10 to about 50% by weight of the at least one reinforcement material; the filler concentrate includes from about 30 to about 90 parts by weight of the filler; the polymeric composition includes one or more elastomers selected from the group consisting of SLEPs, LEPs, polypropylene elastomers, and any combination thereof; the polymeric composition includes an elastomer selected from the group consisting of SLEPs and LEPs; the polymeric composition includes a polypropylene elastomer; the reinforcement material includes long glass fiber present at a concentration greater than about 40 wt.% based on the total weight of the reinforcement concentrate, the long glass fibers have an average fiber length greater than about 1 mm, the first polymeric material includes a polypropylene, the filler is present at a concentration greater than about 40 wt.% based on the total weight of the filler concentrate, the second polymeric material includes an elastomer, the thermoplastic polyolefin comprises at least 75 wt.% of one or more polypropylenes, the elastomer is selected from the group consisting of SLEPs, an LEP, polypropylene elastomer, or any combination thereof, and the elastomer is present at a concentration less than about 30 wt.% based on the total weight of the polymeric composition; the elastomer includes a polypropylene elastomer having a propylene concentration greater than about 50 wt.%; or the elastomer includes an SLEP or an LEP. [0007] An additional aspect of the invention is directed at a process for manufacturing a part having a composition as disclosed herein, wherein the process comprises: providing the reinforcement concentrate, providing the filler concentrate, and providing the thermoplastic polyolefin.
[0008] This process aspect of the invention may be further characterized by one or any combination of the following: the process further comprises: admixing the reinforcement concentrate, the filler, and the thermoplastic polyolefin to form a polymeric composition; the process further comprises shaping the polymeric composition into a part; the second polymeric material, the thermoplastic polyolefin, or combinations thereof include a highly crystalline portion that is at least 30% by weight of the reinforcement concentrate, the filler concentrate, the thermoplastic polyolefin, or combinations thereof; the part exhibits a warpage of less than about 30 mm according to the tray warpage test; the admixing step, includes a step of admixing the fiber concentrate and the filler concentrate prior to adding the thermoplastic polyolefin; the shaping step includes injection molding the polymeric composition, compression molding the polymeric composition, or both; the admixing step includes a step of mixing the thermoplastic polyolefin with at least a portion of either the filler concentrate or the reinforcement concentrate. [0009] Yet another aspect of the invention is directed at a molded part having at least one section containing a polymeric composition as described herein. [0010] A further aspect of the invention is directed at a molded part having at least one section which is molded according to a process described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Fig. 1A is a perspective view of an exemplary article in accordance with an aspect of the present invention.
[0012] Fig. 1 B is a perspective view of another exemplary article in accordance with an aspect of the present invention. [0013] Fig. 2 is side view of the exemplary articles in Figs. 1A-1 B in accordance with an aspect of the present invention.
[0014] Fig. 3 illustrates the relationship between warpage and the difference in fiber length between the skin and the core.
[0015] Fig. 4 is a perspective view illustrating a warped part on a flat surface being held down on three corners.
[0016] Fig. 5 illustrates the geometry of the tray and the measurement of the warpage, d, of a part. Fig. 5 is a top view. Fig. 5A is a cross-section of Fig. 5 showing the left edge of the tray. Fig. 5B is a cross-section of Fig. 5 showing the right edge of the tray. Fig. 5C is a cross-section of Fig. 5 showing the rear edge of the tray. Fig. 5D is a cross-section of Fig. 5 showing the front edge of the tray.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention is directed to an improved polymeric composition, processes of forming and/or using the composition as well as components or parts formed of the polymeric composition and/or by the processes. Advantageously, the polymeric composition can be employed to form parts or components with desirable characteristics at relatively low cost. The polymeric composition is typically comprised of thermoplastic polyolefin, reinforcement material, filler material, and one or more additives that can include, without limitation, antioxidant, demolding agent, blowing agents, UV additives (e.g., UV absorbers) and stabilizers, amine, amide, combinations thereof or others. The thermoplastic polyolefin can be comprised of one or more thermoplastics, but typically includes polypropylene (PP), polyethylene (PE), the like, or combinations thereof and at least a portion of the thermoplastic typically has a relatively high crystallinity. The reinforcement material can include particles, chopped materials, strands, combinations thereof, or the like. Preferably, the reinforcement material includes fibers and more preferably includes glass fibers. The filler material can include one or more fillers and preferably includes a mineral filler such as talc, mica, wollastonite, combinations thereof, or the like. Optionally, the fiber material, the filler material, or both the fiber and filler materials may further include a polymeric material (e.g., the fiber materials may include a first polymeric material and the filler material may include a second polymeric material) having one or more thermoplastic polyolefins (e.g., one or more polypropylenes), one or more elastomers, or both. [0018] The polymeric composition can include a variety of polymers such as thermoplastic polymers, elastomers or any combination thereof. Suitable plastic materials (i.e., thermoplastic polymers) can include, without limitation, thermoplastics such as polycarbonates ("PC"), ABS, polypropylene ("PP"), high impact polystyrene ("HIPS"), polyethylene ("PE"), polyester, polyacetyl, thermoplastic elastomers, thermoplastic polyurethanes ("TPU"), polyamide (e.g., Nylon), ionomer (e.g., Surlyn), polyvinyl chloride ("PVC") and including blends of two or more of these thermoplastics such as PC and ABS. Of course, the polymeric composition can include other polymers or additives within the scope of the present invention.
[0019] According to preferred embodiments, the overall polymeric composition that can form a part includes a substantial portion of thermoplastic polyolefin, and more particularly, includes a substantial portion of polypropylene, polyethylene, or both. In one preferred embodiment, the thermoplastic polyolefin is substantially entirely polypropylene (e.g., at least about 80 wt.%, 90 wt.%, or more polypropylene based on the total weight of the thermoplastic polyolefin). The polymeric composition typically includes at least about 10% although possibly less, more typically at least about 45% and still more typically at least about 60% by weight of the thermoplastic polyolefin. The polymeric composition also typically includes less than about 95% although possibly more, more typically less than about 90% and possibly less than about 85% by weight of the thermoplastic polyolefin.
[0020] Additionally, the polymeric composition typically includes at least about
5% although possibly less, more typically at least about 15% and even possibly at least about 20% by weight of the reinforcement material. The polymeric composition also typically includes less than about 50% and possibly less than about 30% of the reinforcement material.
[0021] Further, the polymeric composition also typically includes at least 3% although possibly less, more typically at least 10% and even possibly at least about 15% by weight of the filler material. The polymeric composition also typically includes less than about 35% and possibly less than about 25% by weight of the filler material based on the total weight of the polymeric composition. Optionally, the polymeric composition may typically include at least about 2% although possibly less, more typically at least about 5% and still more typically at least about 10% by weight of the elastomer. The polymeric composition also typically includes less than about 30% and possibly less than about 20% by weight of the elastomer, when included. [0022] The thermoplastic polyolefin and particularly the one or more polypropylenes can be co-polymers, homopolymers, or both. However, it is additionally contemplated that such terms and such material can allow for some degree of impurity which is typically less that 5%, more typically less than 2% and even more typically less that 0.8% by weight of whichever ingredient is specified.
[0023] In one example embodiment, it is further contemplated that a portion of the thermoplastic polyolefin of the polymeric composition is typically relatively highly crystalline. The thermoplastic polyolefin will typically be comprised of ingredients (e.g., polypropylene, polyethylene, the like, or combinations thereof) present at a concentration of at least 10% but possibly less, more typically at least 50%, and still more typically at least about 60%, but typically less than 90%, although possibly more by weight of the thermoplastic polyolefin. The percentage of crystallinity of the ingredients in the thermoplastic polyolefin may vary (e.g., higher or lower) depending on the application.
[0024] A polypropylene suitable for use in this invention, consistent with US
Patent No. 6,403,692, incorporated by reference (see e.g., 6,403,692, column 2, lines 30-58) is well known in the literature and can be prepared by known techniques. In general, the polypropylene is in the isotatic form, although other forms can also be used (e.g., syndiotatic or atatic). The polypropylene used for the present invention is preferably a homopolymer of polypropylene or a copolymer, for example, a random or block copolymer, of propylene and an α-olefin, preferably a C2, or C4 to C2o α-olefin. The α-olefin is present in the polypropylene of the present invention in an amount of not more than 20 percent by mole, preferably not more than 15 percent, even more preferably not more than 10 percent and most preferably not more than 5 percent by mole. [0025] Examples of the C2, or C4 to C20 α-olefins for constituting the propylene and α-olefin copolymer include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1- octene, 1-decene, 1-dodecene, 1-hexadodecene, 4-methyl- 1-pentene, 2-methyl-1- butene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, diethyl-1-butene, trimethyl-1-butene, 3-methyl-1-pentene, ethyl-1-pentene, propyl-1-pentene, dimethyl-1-pentene, methylethyl-1-pentene, diethyl-1-hexene, trimethyl-1-pentene, 3-methyl-1-hexene, dimethyl-1-hexene, 3,5,5-trimethyl-1-hexene, methylethyl-1-heptene, trimethyl-1-heptene, dimethyloctene, ethyl-1-octene, methyl-1-nonene, vinylcyclopentene, vinylcyclohexene and vinylnorbornene, where alkyl branching position is not specified it is generally on position 3 or higher of the alkene.
e [0026] Percent crystallinity is measured by differential scanning calorimetry, according to ASTM D3417. A milligram size sample of polymer is sealed into an aluminum DSC pan. The sample is placed into a DSC cell with a 25 cubic centimeter per minute nitrogen purge and cooled to -1000C. A standard thermal history is established for the sample by heating at 10°C/minute to 2250C. The sample is then cooled (at 10° C/minute) to -1000C and reheated at 10 °C/minute to 2250C. The observed heat of fusion for the second scan is recorded ( ΔHobserved ). The observed heat of fusion is related to the degree of crystallinity in weight percent based on the weight of the polypropylene sample by the following equation:
%Crystallinity = AH'Λ^^1 x 100 ,
A" isotacticPP where the heat of fusion for isotactic polypropylene as reported in B. Wunderlich, Macromolecular Physics, Volume 3, Crystal Melting, Academic Press, New York, 1980, p. 48, is 165 Joules per gram of polymer.
[0027] As defined herein, consistent with US Patent No. 6,403,692, incorporated by reference (see e.g., 6,403,692, column 3, lines 17-29) a high degree of crystallinity, as determined by DSC, is at least about 62 weight percent, more preferably at least about 64 weight percent, even more preferably at least about 66 weight percent, even more preferably at least about 68 weight percent and most preferably at least about 70 weight percent based on the weight of the polypropylene. The degree of crystallinity for the polypropylene as determined by DSC is less than or equal to about 100 weight percent, preferably less than or equal to about 90 weight percent, more preferably less than or equal to about 80 weight percent, and most preferably less than or equal to about 70 weight percent based on the weight of the polypropylene. [0028] Typically there is a preference for the relatively high crystallinity portion of the thermoplastic polyolefin and/or the entire thermoplastic polyolefin to be comprised of at least 40 wt%, more typically at least 75 wt%, even more typically at least 95 wt% or even substantially entirely or entirely of one or more polypropylenes (e.g., one type of polypropylene or a blend of 2, 3, 4, or more polypropylenes).
[0029] In another exemplary embodiment, it is also contemplated that the thermoplastic polyolefin can comprise one or more lower crystallinity grades of polypropylene, polyethylene, or both (i.e., grades having crystallinity below the relatively highly crystallinity of the polypropylene, polyethylene, or both as discussed above), which may be isotactic, syndiotactic or atactic. In general the low cryallinity grades may have a crystallinity lower than the crystallinity of the high crystallinity grade. For example, the low crystallinity grades may have a crystallinity less than about 62 wt.% or even less than about 50 wt.%. Without limitation, suitable low crystallinity grades may have a crystallinity less than about 30 wt.%, preferably less than about 20 wt%, and more preferably less than about 15 wt.%, as measured for example by differential scanning calorimetry. When included, such lower crystallinity materials will typically comprise at least about 0.5% but possibly less, more typically at least about 2.0% and even more typically at least about 6%, but typically less than about 40%, although possibly more, more typically less than about 16% and even more typically less than about 10% by weight of the overall polymeric composition. The percentage of crystallinity of polypropylene, polyethylene, or both in the thermoplastic polyolefin may vary (e.g., higher or lower) depending on the application.
[0030] In one preferred embodiment, a substantial portion of the thermoplastic polyolefin is comprised in a polyolefin matrix. Preferably, the thermoplastic polyolefin in the matrix includes a relatively high crystallinity portion. The matrix may include essentially the thermoplastic polyolefin or the thermoplastic polyolefin and one or more ingredients as discussed herein and is configured to be admixed with the reinforcement material, the filler material, the elastomer, or combinations thereof to form the overall polymeric composition. For example, the polyolefin matrix may include the thermoplastic polyolefin, the first polymeric material, and the second polymeric material (as well as any optional polyolefin materials present in the thermoplastic composition). The polyolefin matrix may include a high crystallinity portion greater than about 30 wt.%, preferably greater than about 50 wt.% and more preferably greater than about 60 wt.% based on the total weight of the polyolefin matrix.
[0031] It is contemplated that the polymeric composition includes reinforcement material. The reinforcement material can include strands of material, or otherwise. The reinforcement material may be fiber reinforced or otherwise reinforced with materials such as ceramic, glass (e.g., long glass fibers,), or other fibers. Preferably, the reinforcement material includes or is substantially entirely of fibers, and more preferably includes or is substantially entirely (e.g., at least about 95% by weight) of long glass fibers.
[0032] Furthermore, the overall polymeric composition or the parts formed therefrom include fibers (e.g., long fibers) having an average or mean length of approximately greater than about 1 mm, more preferably greater than about 4 mm even more preferably greater than about 6 mm and most preferably between about 8 mm and about 20 mm.
[0033] In one specific example, to determine the mean glass fiber length, the following process is utilized: Weighing the glass fiber polymer samples including the crucible. The next step is placing the sample (in the crucible) in the oven set at about 550 C (e.g. at about 6000C) for 1 hour, (maximum 12 grams of sample). The temperature preferably is lower than a temperature at which sintering of the glass fibres may occur, above which the fiber length measurement may be compromised. Controlling samples for remains of polymer by making a visual inspection of the sample. If any doubts that the polymer remains in the sample, the ashing procedure is repeated. After the second period of ashing, the weight should be the same and the sample is free of the remaining polymer. (If there are remains of polymer, the glass fibers will not float in the butanediol, as required in the following steps.) Weighing the sample. Pouring butanediol and the glass fiber cluster, (ashed sample), into a bottle. Mixing sample to obtain a representative glass fiber mixture in butanediol, wherein a polymer sample of 1 gram 40% glass fibers and talc can be mixed with 2 liters of fluid. (Avoid sinking of fibers by measuring the sample after mixing. Sinking of fibers or pour dilution cause unrepresentative samples.) Stir the mixture with air at a low pressure to avoid splashing of mixture. Placing a funnel in a side arm flask, seal off the parts, and install a filter in the funnel. Turn on the pump. Emptying the bottle containing butanediol and the glass fibers into the funnel. (Rinse bottle with butanediol into the funnel to remove remaining glass fibers and/or empty the side arm flask containing the recycled butanediol into bottle to repeat cycle if necessary to further remove glass fiber.) Pouring the sample into a Petri dish. Setting up hardware to take pictures of the sample by positioning the camera perpendicularly to the sample, wherein the lens is parallel thereto. Light intensity over the picture is not equal in all areas, which causes the picture to blur, therefore, the frame in Leica QWIN imaging software must be adjusted to have an area with the same light intensity to determine the dimensions of the glass fibers. Avoid pictures depicting crossed fibers, which are not measurable. (Samples filled with filler, such as talc, must be poured quickly and a picture taken as fast as possible because the sample will blur as a result of the filler rising to the surface of the sample and becoming visible.)
[0034] The samples include a core part surrounded by a skin structure having a depth of 1 mm. The samples are viewed using the Leica QWIN imaging software and are measured by comparing each glass fiber against a material of known length. Pictures of the sample (ashed glass fibers) are taken with a high resolution digital camera. The software then converts the information and calculates the curve length of the fibers (e.g., calculates the distribution of the fiber lengths).
[0035] Once the fibers lengths are determined, the fiber length distribution of the different samples are analyzed taking into account that glass fibers having a length greater than about 1 mm are considered long glass fibers. The difference between the amount of long glass fibers embedded in the core part and the long glass fibers embedded in the skin structure relates to the anisotropy of the sample in the z (thickness) direction. As long as the amount of long glass fibers is generally greater in the core layer (percentage of long glass fibers (LGF) in the core part is greater than the percentage of LGF in the skin structure), the part is generally free of warpage as shown in Fig. 3. In Fig. 3, the warpage, measured in mm, is plotted against the difference in the concentration of long glass fibers in the skin and the core (i.e., the concentration of the LGF in the skin part minus the concentration of LGF in the core part). When the percent of LGF in the skin structure is greater than the percent of LGF in the core part, warpage in the part (e.g., tray) becomes increasingly prevalent. The combination of the long glass fibers with filler generally perturbs the flow of the composite material when filling the part. As a result, the part may be influenced by the fillers so that the resulting structure of the layers across the thickness of the part tends to reduce warpage. [0036] The fiber length distribution of the reinforcement material within the polyolefin composition has been shown to have a significant impact on reducing warpage. Without being bound by theory, it is believed that the interaction between the thermoplastic polyolefin matrix, the filler particles, and the fibers can provide a fiber length distribution across the thickness of the molded articles, which leads to a product with reduced warpage.
[0037] The filler material can comprise multiple different fillers or one singular filler material. Preferably, the filler includes or is substantially entirely composed of one or more mineral fillers. Examples of suitable filler materials include, without limitation, clay, aramid, calcium carbonate, talc, kaolin, mica, wollastonite, hollow glass beads, titaninum oxide, silica, carbon black, potassium titanate, silicate material, combinations thereof or the like which can take the form of powders, platelets or otherwise. In one preferred embodiment, it is contemplated that the filler be comprised substantially entirely of mineral filler particularly talc. One preferred talc is a powdered talc sold under the tradename Mistron®, which is commercially available from Luzenac. One preferred talc filled PP compound is sold under the tradename INSPiRE (DTF3800, TF1500SC, DTF1600S, or DTF2502.02ESU)1 which are commercially available from Dow. [0038] The polymeric composition may further include one or more elastomers, which may be a single elastomer or combination of elastomers. More specifically, the one or more elastomer of the present invention may be a polyolefin elastomer. Suitable polyolefin elastomers comprises one or more C2 to C20 α-olefins in polymerized form, having a glass transition temperature (Tg) less than about 250C, preferably less than about 00C, most preferably less than about -25°C. Tg is the temperature or temperature range at which a polymeric material shows an abrupt change in its physical properties, including, for example, mechanical strength. Tg can be determined by differential scanning calorimetry. Examples of the types of polymers from which the present polyolefin elastomers are selected include copolymers of α-olefins, such as ethylene and propylene, ethylene and 1-butene, ethylene and 1-hexene or ethylene and 1-octene copolymers, and terpolymers of ethylene, propylene and a diene comonomer such as hexadiene or ethylidene norbornene. The elastomer may comprise a variety of elastomers such as a thermoplastic elastomer that may include one or more α-olefin elastomers (e.g., one or more ethylene α-olefin elastomers, one or more polypropylene elastomer, or any combination). For example the elastomer may comprise substantially linear ethylene polymers (SLEPs), linear ethylene polymers (LEPs) or both. The elastomer may be a neat elastomer or a blend. Substantially linear and linear ethylene polymers (SLEPs) are particularly preferred. Substantially linear ethylene polymers and linear ethylene polymers and their method of preparation are fully described in U.S. Pat. Nos. 5,272,236; 5,278,272;. 3,645,992; 4,937,299; 4,701 ,432; 4,937,301 ; 4,935,397; 5,055,438; and EP 129,368; EP 260,999; and WO 90/07526, which are fully incorporated herein by reference for all purposes.
[0039] As used herein, "a linear or substantially linear ethylene polymer" means a homopolymer of ethylene or a copolymer of ethylene and one or more α-olefin comonomers having a linear backbone (i.e. no cross linking), a specific and limited amount of long-chain branching or no long-chain branching, a narrow molecular weight distribution, a narrow composition distribution (e.g., for α-olefin copolymers) or a combination thereof. More explanation of such polymers is discussed in U.S. Patent 6,403,692, which is incorporated herein by reference for all purposes. [0040] Illustrative α-olefins include propylene, 1-butene, 1-hexene, 4-methyl-1- pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1 -hexadodecene, 4-methyl-1- pentene, 2-methyl-1-butene, 3-methyl-1-butene, 3,3-dimethyl-i-butene, diethyl-1-butene, trimethyl-1-butene, 3-methyl-1-pentene, ethyl-1-pentene, propyl-1-pentene, dimethyl-1- pentene, methylethyl-1-pentene, diethyl-1-hexene, trimethyl-1-pentene, 3-methyl-1- hexene, dimethyl-1-hexene, 3,5,5-trimethyl-i-hexene, methylethyl-1-heptene, trimethyl- 1-heptene, dimethyloctene, ethyl-1-octene, methyl-1-nonene, vinylcyclopentene, vinylcyclohexene and vinylnorbomene, where alkyl branching position is not specified it is generally on position 3 or higher of the alkene and styrene. The α-olefin is desirably a C3-C20 or C3-C10 α-olefin. Preferred copolymers include ethylene/propylene (EP), ethylene/1 -butene (EB), ethylene/1 -hexene (EH) and ethylene/1 -octene (EO) polymers. Illustrative terpolymers include an ethylene/propylene/octene terpolymer as well as terpolymers of ethylene, a C3-C20 α-olefin and one (or more) diene such as dicyclopentadiene, 1 ,4-hexadiene, piperylene or 5-ethylidene-2-norbomene. The polyolefin elastomers can have densities less than about 0.9 g/cc, melt flow rates of about 0.1 to about 30g/10 min (tested according to ASTM D1238 at 190 0C, 2.16kg), and more specifically about 0.5 to about 25g/10 min (tested according to ASTM D1238 at 190 0C, 2.16kg) and can have glass transition temperatures of less than about -30 C, or any combination thereof.
[0041] Without limitation, an exemplary LEP or SLEP, as described in U.S.
Patent No. 5,272,236 (e.g., column 2, lines 41-51 and column 3, lines 25-30) may be characterized as substantially linear olefin polymers having the following novel properties: a) a melt flow ratio, I1O/I2, ≤ 5.63, b) a molecular weight distribution, Mw /Mn, defined by the equation:
Mw /Mn ≤ I1o/I2 - 4.63, and c) a critical shear stress at onset of gross melt fracture of greater than about 4 x106 dyne/cm2.
Such a polymer, may be an be interpolymers of ethylene with at least one C3 -C20 α- olefin. The melt flow ratio, liθ/l2,is the ratio of "I10" (the melt flow index measured in accordance with ASTM D-1238 (190/10)) and "I2" (the melt flow index measured in accordance with ASTM D-1238 (190/2.16). These "substantially linear" polymers may have a polymer backbone that is either unsubstituted or substituted with up to 3 long chain branches/1000 carbons (where a long chain branch contains at least about 6 carbons). Preferred polymers are substituted with about 0.01 long chain branches/1000 carbons to about 3 long chain branches/1000 carbons, more preferably from about 0.01 long chain branches/1000 carbons to about 1 long chain branches/1000 carbons, and especially from about 0.3 long chain branches/1000 carbons to about 1 long chain branches/1000 carbons. The measurement of the polydispersity index of this polymer, as described in U.S. Patent No. 5,272,236 column 5, lines 18-40, is done according to the following technique: The polymers are analyzed by gel permeation chromatography (GPC) on a Waters 150C high temperature chromatographic unit equipped with three linear mixed bed columns (Polymer Laboratories (10 micron particle size)), operating at a system temperature of 140 0C. The solvent is 1 ,2,4-trichlorobenzene, from which about 0.5% by weight solutions of the samples are prepared for injection. The flow rate is 1.0 milliliter/minute and the injection size is 100 microliters. The molecular weight determination is deduced by using narrow molecular weight distribution polystyrene standards (from Polymer Laboratories) in conjunction with their elution volumes. The equivalent polyethylene molecular weights are determined by using appropriate Mark- Houwink coefficients for polyethylene and polystyrene (as described by Williams and Word in Journal of Polymer Science, Polymer Letters, Vol. 6,(621) 1968, incorporated herein by reference) to derive the equation:
Mpolyethylene = (a)(Mpo|yStyrene)
In this equation, a=0.4316 and b=1.0. Weight average molecular weight, Mw, is calculated in the usual manner according to the formula:
Mw =(R)(W1)(M1) where Wj and Mi are the weight fraction and molecular weight respectively of the ith fraction eluting from the GPC column. The critical shear stress at onset of gross melt fracture. The critical shear stress at onset of gross melt fracture is measured by a gas extrusion rheometer (GER) as described in U.S. Patent No. 5,272,236 (e.g., column 4, lines 10-45). The gas extrusion rheometer is described by M. Shida, R. N. Shroff and L. V. Cancio in Polymer Engineering Science, Vol. 17, no. 11 , p. 770 (1977), and in "Rheometers for Molten Plastics" by John Dealy, published by Van Nostrand Reinhold Co. (1982) on page 97, both publications of which are incorporated by reference herein in their entirety. All GER experiments are performed at a temperature of 190 0C, at nitrogen pressures between 5250 to 500 psig using a 0.0296 inch diameter, 20:1 L/D die. An apparent shear stress vs. apparent shear rate plot is used to identify the melt fracture phenomena. According to Ramamurthy in Journal of Rheology, 30(2), 337-357, 1986, above a certain critical flow rate, the observed extrudate irregularities may be broadly classified into two main types: surface melt fracture and gross melt fracture. Surface melt fracture occurs under apparently steady flow conditions and ranges in detail from loss of specular gloss to the more severe form of "sharkskin". Gross melt fracture occurs at unsteady flow conditions and ranges in detail from regular (alternating rough and smooth, helical, etc.) to random distortions. For commercial acceptability, (e.g., in blown film products), surface defects should be minimal, if not absent. The critical shear rate at onset of surface melt fracture (OSMF) and onset of gross melt fracture (OGMF) will be used herein based on the changes of surface roughness and configurations of the extrudates extruded by a GER. Preferably, the critical shear stress at the OGMF and the critical shear stress at the OSMF for the substantially linear ethylene polymers described herein is greater than about 4 x 106 dyne/cm2 and greater than about 2.8 x 106 dyne/cm2, respectively.
[0042] Without limitation, another example of a suitable elastomer is described in
EP Patent No. 0495099, filed December 12, 1989, incorporated by reference herein. EP Patent No. 0495099 describes ethylene copolymers having (a) structural units derived from ethylene and (b) structural units derived from α-olefin of 3-20 carbon atoms, which are characterized in that they have (i) a density of 0.85-0.92 g/cm3,
(ii) an intrinsic viscosity [ η ] of 0.1-10 dl/g as measured in decalin at 135 0C, (iii) a (MwZMn) ratio of a weight average molecular weight (Mw) to a number average molecular weight (Mn) of 1.2-4 as measured by GPC, and
(iv) a (MFR10/MFR2) ratio of MFR10 under a load of 10 kg to MFR2 under a load of 2.16 kg of 8-50 as measured at 190 0C. MFR10 and MFR2 may be measured for example, using ASTM D-1238 at 1900C with a load of 10kg and 2.16kg respectively. [0043] The elastomer may be polymermized using any suitable catalyst system.
For example, the elastomer may be polymerized using a catalyst containing a Ziegler- Natta catalyst, a metallocene catalyst, an activated nonmetallocene metal-centered heteroaryl ligand catalyst, and the like. Combinations of catalysts may also be used. Without limitation, one exemplary catalyst is a metallocene catalyst. For example, the elastomer may be polymerized using a catalyst which includes a metallocene catalyst as described in EP Patent Application No. 129368, filed on June 5, 1984 (Ewen et. al.) incorporated herein by reference. Such metallocene may be a compound of the general formula:
[0044] (C5R'm)pR"5(C5R'm)MeQ3-p and R"s(C5R'm)MeQ'
[0045] wherein Me is a Group 4b, 5b, 6b metal, (C5R'm) is a cyclopentadienyl or substituted cylcopentadienyl, each R', which can be the same or different, is hydrogen, an alkyl, an alkenyl, aryl, alkylaryl, or arylalkyl radical having from 1 to 20 carbon atoms or two R' substituents together form a fused C4-C6 ring, R" is a C1-C4 alkylene radical, a dialkyl germanium or silicone, or an alkyl phosphine or amine radical bridging two (C5- R'm) rings, each Q, which can be the same or different, is aryl, alkyl, alkenyl, alkylaryl, or arylalkyl radical having from 1 to 20 carbon atoms or halogen, Q' is an alkylidene radical having from 1 to 20 carbon atoms, s is 0 or 1 , p is 0, 1 or 2; when p is 0, s is 0; m is 4 when s=1 ; and m is 5 when s is 0 and at least one R' is a hydrocarbyl radical when Q is an alkyl radical.
[0046] The elastomer may also include or consist essentially of a polypropylene elastomer. Suitable polypropylene elastomers may contain propylene monomer at a concentration greater than about 50 wt.%, preferably greater than about 65 wt.%, more preferably greater than about 70 wt.%, and most preferably greater than about 80 wt.% based on the weight of the polypropylene elastomer. The polypropylene elastomer may also contain one or more additional C2-I2 α-olefin comonomers (e.g., a comonomer including ethylene, or consisting of ethylene) at a concentration greater than about 5 wt.%, preferably greater than about 7 wt.%, more preferably greater than about 9 wt.%, and most preferably greater than about 12 wt.% based on the total weight of the polypropylene elastomer. For example, the comonomer content may range from about 5 to about 40 percent by weight of the polypropylene elastomer composition, more preferably from about 7 to about 30 percent by weight of the polypropylene elastomer composition, and still more preferably from about 9 to about 15 percent by weight of the polypropylene elastomer composition. The polypropylene elastomer may have some crystallinity or may be amorphous. Suitable polypropylene elastomers may have a peak melting temperature less than about 130 0C, preferably less than about 115 0C, and most preferably less than about 100 °C, as measured by differential scanning calorimetry at a heating rate of about 10°C/min on a sample which has been cooled from about 2200C to about 00C at a rate of about 10°C/min.
[0047] The polypropylene elastomer may exhibit a Shore A hardness according to ASTM D 2240-05 of at least about 40, more preferably at least about 50, still more preferably at least about 65. The Shore A hardness may also be less than about 97, preferably less than about 92, more preferably less than about 85, still more preferably less than about 80. For example, the polypropylene elastomer may have a Shore A hardness from about 40 to about 92, more preferably from about 50 to about 85, and still more preferably from about 65 to about 80 Shore A.
[0048] It is preferred that the polypropylene elastomer exhibit at least some crystallinity The crystallinity may be at least about 2, preferably at least about 5, and still more preferably at least about 7 percent by weight of the polypropylene elastomer material. Without limitation, suitable polypropylene elastomers may have a crystallinity less than about 40, preferably less than about 35, more preferably less than about 28, and still more preferably less than about 20 percent by weight of the polypropylene elastomer material. For example, the crystallinity may range from about 2 to about 40, more preferably from about 5 to about 35, and still more preferably about 7 to about 20 percent by weight of the polypropylene elastomer material.
[0049] Additional specific examples of propylene elastomers that may be employed in accordance with the present teachings include those disclosed in WO 03/040201 A1 filed on May 6, 2002, published US Application No. 2003-0204017 filed on May 5, 2002, and U.S. Patent No. 6,525,157 issued on February 25, 2003, all of which are incorporated by reference.
[0050] For example, the propylene elastomer may be a low elasticity ethylene- propylene copolymer (i.e., an LEEP copolymers) taught in U.S. Patent No. 6,525,157 issued on February 25, 2003, incorporated herein by reference. Such an LEEP, as described in U.S. Patent No. 6,525,157 issued on February 25, 2003 from column 2, line 15 to column 3, line 54 may be (LEEP) copolymers that when produced in the presence of a metallocene catalyst and an activator, in a single steady state reactor, show a surprising and unexpected balance of flexural modulus, tensile strength and elasticity. Moreover, these and other properties of the (LEEP) copolymers show surprising differences relative to conventional polymer blends, such as blends of isotactic polypropylene and ethylene-propylene copolymers.
[0051] In one embodiment, the (LEEP) copolymer includes from a lower limit of
5% or 6% or 8% or 10% by weight to an upper limit of 20% or 25% by weight ethylene- derived units, and from a lower limit of 75% or 80% by weight to an upper limit of 95% or 94% or 92% or 90% by weight propylene- derived units, the percentages by weight based on the total weight of propylene- and ethylene-derived units. The copolymer is substantially free of diene-derived units.
[0052] In various embodiments, features of the (LEEP) copolymers include some or all of the following characteristics, where ranges from any recited upper limit to any recited lower limit are contemplated:
[0053] (i) a melting point ranging from an upper limit of less than 110° C, or less than 90° C1 or less than 80° C, or less than 70° C, to a lower limit of greater than 25°
C, or greater than 35° C, or greater than 40° C, or greater than 45° C;
[0054] (ii) a relationship of elasticity to 500% tensile modulus such that Elasticity
<0.935M+12, or Elasticity <0.935M+6, or Elasticity <0.935M, where elasticity is in percent and M is the 500% tensile modulus in megapascal (MPa);
[0055] (iii) a relationship of flexural modulus to 500% tensile modulus such that
Flexural Modulus <4.2eO 27M+5O, or Flexural Modulus ≤4.2e027M +30, or Flexural Modulus
≤4.2e027M +10, or Flexural Modulus ≤4.2e027M +2, where flexural modulus is in MPa and
M is the 500% tensile modulus in MPa;
[0056] (iv) a heat of fusion ranging from a lower limit of greater than 1.0 joule per gram (J/g), or greater than 1.5 J/g, or greater than 4.0 J/g, or greater than 6.0 J/g, or greater than 7.0 J/g, to an upper limit of less than 125 J/g, or less than 100 J/g, or less than 75 J/g, or less than 60 J/g, or less than 50 J/g, or less than 40 J/g, or less than 30
J/g;
[0057] (v) a triad tacticity as determined by carbon-13 nuclear magnetic resonance (13C NMR) of greater than 75%, or greater than 80%, or greater than 85%, or greater than 90%;
[0058] (vi) a tacticity index m/r ranging from a lower limit of 4 or 6 to an upper limit of 8 or 10 or 12;
[0059] (vii) a proportion of inversely inserted propylene units based on 2,1 insertion of propylene monomer in all propylene insertions, as measured by 13C NMR, of greater than 0.5% or greater than 0.6%;
[0060] (viii) a proportion of inversely inserted propylene units based on 1,3 insertion of propylene monomer in all propylene insertions, as measured by 13C NMR, of greater than 0.05%, or greater than 0.06%, or greater than 0.07%, or greater than 0.08%, or greater than 0.085%;
[0061] (ix) an intermolecular tacticity such that at least X % by weight of the copolymer is soluble in two adjacent temperature fractions of a thermal fractionation carried out in hexane in 8 0C increments, where X is 75, or 80, or 85, or 90, or 95, or 97, or 99;
[0062] (x) a reactivity ratio product T1T2 of less than 1.5, or less than 1.3, or less than 1.0, or less than 0.8;
[0063] (xi) a molecular weight distribution Mw/Mn ranging from a lower limit of
1.5 or 1.8 to an upper limit of 40 or 20 or 10 or 5 or 3;
[0064] (xii) a molecular weight of from 15,000-5,000,000;
[0065] (xiii) a solid state proton nuclear magnetic resonance (1H NMR) relaxation time of less than 18 milliseconds (ms), or less than 16 ms, or less than 14 ms, or less than 12 ms, or less than 10 ms;
[0066] (xiv) an elasticity as defined herein of less than 30%, or less than 20%, or less than 10%, or less than 8%, or less than 5%; and
[0067] (xv) a 500% tensile modulus of greater than 0.5 MPa, or greater than 0.8
MPa, or greater than 1.0 MPa, or greater than 2.0 MPa.
[0068] The LEEP copolymer be made in the presence of a bridged metallocene catalyst, in a single steady-state reactor.
[0069] The test methods for the LEEP copolymer are described in U.S. Patent
No. 6,525,157.
[0070] The test method for the measurement of the melting temperature and the heat of fusion of the LEEP copolymer is described in U.S. Patent No. 6,525,157 from column 19, line 12 to column 19, line 29: The melting point and heat of fusion are measured by Differential Scanning Calorimetry (DSC) follows. About 6 to 10 mg of a sheet of the polymer pressed at approximately 200 0C to 230 0C is removed with a punch die. This is annealed at room temperature for 24 hours. At the end of this period, the sample is placed in a Differential Scanning Calorimeter (Perkin Elmer 7 Series
Thermal Analysis System) and cooled to about -50 0C to about -70 0C. The sample is heated at 20 °C/min to attain a final temperature of about 200 0C to about 220 0C. The thermal output is recorded as the area under the melting peak of the sample, which is typically peaked at about 30 0C to about 175 0C and occurs between the temperatures of about 0 0C and about 200 CC, and is measured in joules as a measure of the heat of fusion. The melting point is recorded as the temperature of the greatest heat absorption within the range of melting of the sample. [0071] The test methods for the measuring the elasticity, the 500% elastic modulus and the flexural modulus of the LEEP copolymer are described in U.S. Patent No. 6,525,157 from column 17, line 1 to column 18, line 60:
[0072] Embodiments of the LEEP copolymer are elastic after tensile deformation.
The elasticity, represented by the fractional increase in the length of the sample, represented as percent of the length of the sample, is measured according to the general procedure ASTM D790. During tensile elongation, the copolymer sample is stretched, and the polymer attempts to recover its original dimensions when the stretching force is removed. This recovery is not complete, and the final length of the relaxed sample is slightly longer than that of the original sample. Elasticity is represented by the fractional increase in the length of the sample, expressed as a percent of the length of the original un-stretched sample.
[0073] The protocol for measuring the elasticity of the sample consists of prestretching the deformable zone of the dumbbell, made according to the procedure described above for the measurement of elongation and tensile strength, which is the narrow portion of the specimen, to 200% of its original length to prestretch the sample. This is conducted at a deformation rate of 10 inches (25 cm) per minute. The sample is relaxed at the same rate to form an analytical specimen which is a prestretched specimen of the original sample. This slightly oriented, or prestretched, sample is allowed to relax for 48 hours, at room temperature, prior to the determination of elasticity. The length of the deformation zone in the sample is measured to be d^ After the 48 hours, it is again deformed at 10 inches per minute for a 200% extension of the deformation zone of the sample and allowed to relax at the same rate. The sample is removed and after 10 minutes of relaxation the sample is measured to have a new length of the deformation zone of d2. The elasticity of the sample as a percent is determined as 100*(d 2 -d i)/di.
[0074] Embodiments of the LEEP copolymer may have elasticity, as measured by the procedure described above, of less than 30%, or less than 20%, or less than 10%, or less than 8% or less than 5%.
[0075] These values of the elasticity over the range of composition of the copolymer vary with the tensile strength of the sample as measured by the 500% tensile modulus. Elasticity of this family of copolymers is thus represented by two criteria: (a) extensibility to 500% elongation with a measurable modulus (500% tensile modulus) and (b) elasticity from an extension to 200% elongation on a slightly oriented sample as described above. First, the copolymer of embodiments of the LEEP copolymer should have a measurable tensile strength at 500% elongation (also known as 500% tensile modulus), of greater than 0.5 MPa, or greater than 0.75 MPa1 or greater than 1.0 MPa, or greater than 2.0 MPa; and second, the copolymer should have the above-described elasticity.
[0076] Alternatively, the relationship of elasticity to 500% tensile modulus may be described. In embodiments of the LEEP copolymer, the elasticity as a function of 500% tensile modulus in MPa is defined by:
Elasticity (%) < 0.935 M+12; or
Elasticity (%) < 0.935 M+6; or
Elasticity (%) < 0.935 M where M is the 500% tensile modulus in MPa.
[0077] Flexural Modulus
[0078] Softness of the copolymers of embodiments of the LEEP copolymer may be measured by flexural modulus. Flexural modulus is measured in accordance with
ASTM D790, using a Type IV dogbone at crosshead speed of 0.05 in/min (1.3 mm/min).
The values of the flexural modulus over the range of composition of the copolymer vary with the tensile strength of the sample as measured by the 500% tensile modulus.
Flexural modulus of this family of copolymers is thus represented by two criteria: (a) extensibility to 500% elongation with a measurable modulus (500% tensile modulus); and (b) flexural modulus.
[0079] The flexural modulus of the LEEP copolymer in MPa as a function of
500% tensile modulus in MPa, is defined by:
Flexural Modulus ≤ 4.2 e02™ + 50; or
Flexural Modulus ≤ 4.2 e02™ + 30; or
Flexural Modulus ≤ 4.2 eO 2™ + 10; or
Flexural Modulus ≤ 4.2 e027M + 2. [0080] The test method for measuring the tacticity index of the LEEP copolymer is described in U.S. Patent No. 6,525,157 from column 6, line 22 to 36: The tacticity index, expressed herein as "m/ r", is determined by 13C nuclear magnetic resonance (NMR). The tacticity index m/r is calculated as defined in H. N. Cheng, Macromolecules, 17, 1950 (1984). The designation "m" or "r" describes the stereochemistry of pairs of contiguous propylene groups, "m" referring to meso and "r" to racemic. An m/r ratio of 1.0 generally describes a syndiotactic polymer, and an m/r ratio of 2.0 an atactic material. An isotactic material theoretically may have a ratio approaching infinity, and many byproduct atactic polymers have sufficient isotactic content to result in ratios of greater than 50. LEEP copolymers can have a tacticity index m/r ranging from a lower limit of 4 or 6 to an upper limit of 8 or 10 or 12.
[0081] The test method for measuring the molecular weight and polydispersity index of the LEEP copolymer as described in U.S. Patent No. 6,525,157 from column 5, line 1 to 57 includes the following:
[0082] Molecular weight distribution (MWD) is a measure of the range of molecular weights within a given polymer sample. It is well known that the breadth of the MWD can be characterized by the ratios of various molecular weight averages, such as the ratio of the weight average molecular weight to the number average molecular weight, Mw/Mn, or the ratio of the Z-average molecular weight to the weight average molecular weight, Mz/Mw.
[0083] Mz, Mw and Mn can be measured using gel permeation chromatography
(GPC), also known as size exclusion chromatography (SEC). This technique utilizes an instrument containing columns packed with porous beads, an elution solvent, and detector in order to separate polymer molecules of different sizes. In a typical measurement, the GPC instrument used is a Waters chromatograph equipped with ultrastyro gel columns operated at 145 0C. The elution solvent used is trichlorobenzene. The columns are calibrated using sixteen polystyrene standards of precisely known molecular weights. A correlation of polystyrene retention volume obtained from the standards, to the retention volume of the polymer tested yields the polymer molecular weight.
[0084] Average molecular weights M can be computed from the expression:
Figure imgf000022_0001
[0085] where Nj is the number of molecules having a molecular weight Mj. When n=0, M is the number average molecular weight Mn. When n=1 , M is the weight average molecular weight Mw. When n=2, M is the Z-average molecular weight Mz. The desired MWD function (e.g., Mw/Mn or Mz/Mw) is the ratio of the corresponding M values. Measurement of M and MWD is well known in the art and is discussed in more detail in, for example, Slade, P. E. Ed., Polymer Molecular Weights Part II, Marcel Dekker, Inc., NY, (1975) 287-368; Rodriguez, F., Principles of Polymer Systems 3rd ed., Hemisphere Pub. Corp., NY, (1989) 155-160; U.S. Pat. No. 4,540,753; Verstrate et al., Macromolecules, vol. 21, (1988) 3360; and references cited therein. [0086] In embodiments of the LEEP copolymer, the LEEP copolymer is included having a weight average molecular weight (Mw) of from 15,000-5,000,000, or from 20,000 to 1 ,000,000 and a molecular weight distribution Mw/Mn (sometimes referred to as a "polydispersity index" (PDI)) ranging from a lower limit of 1.5 or 1.8 to an upper limit of 40 or 20 or 10 or 5 or 3.
[0087] The test method for measuring the triad of the LEEP copolymer as described in U.S. Patent No. 6,525,157 from column 6, line 37 to column 7, line 44 is: [0088] An ancillary procedure for the description of the tacticity of the propylene units of the LEEP copolymer is the use of triad tacticity. The triad tacticity of a polymer is the relative tacticity of a sequence of three adjacent propylene units, a chain consisting of head to tail bonds, expressed as a binary combination of m and r sequences. It is usually expressed for copolymers of the present LEEP copolymers as the ratio of the number of units of the specified tacticity to all of the propylene triads in the copolymer. [0089] The triad tacticity (mm fraction) of a propylene copolymer can be determined from a 13C NMR spectrum of the propylene copolymer and the following formula: mm Fraction = PPP(mm) / [PPP(mm) + PPP(mr) + PPP(rr)]
[0090] where PPP(mm), PPP(mr) and PPP(rr) denote peak areas derived from the methyl groups of the second units in the following three propylene unit chains consisting of head-to-tail bonds:
CHg CH3 CHg
PPP(mm): ' ' '
' CH-CH2 )— ( CH-CH2 )— ( CH-CH2 CH3 CH3
I I
PPP(mr): — ( CH-CH2 )— ( CH-CH2 )— ( CH-CH2
I CH3
CH3 CH3
I I
PPP(rr): — ( CH-CH2 )— ( CH-CH2 )— ( CH-CH2
I CH,
[0091] The 13C NMR spectrum of the propylene copolymer is measured as described in U.S. Pat. No. 5,504,172. The spectrum relating to the methyl carbon region (19-23 parts per million (ppm)) can be divided into a first region (21.2-21.9 ppm), a second region (20.3-21.0 ppm) and a third region (19.5-20.3 ppm). Each peak in the spectrum was assigned with reference to an article in the journal Polymer, Volume 30 (1989), page 1350.
[0092] In the first region, the methyl group of the second unit in the three propylene unit chain represented by PPP (mm) resonates.
[0093] In the second region, the methyl group of the second unit in the three propylene unit chain represented by PPP (mr) resonates, and the methyl group (PPE- methyl group) of a propylene unit whose adjacent units are a propylene unit and an ethylene unit resonates (in the vicinity of 20.7 ppm).
[0094] In the third region, the methyl group of the second unit in the three propylene unit chain represented by PPP (rr) resonates, and the methyl group (EPE- methyl group) of a propylene unit whose adjacent units are ethylene units resonates (in the vicinity of 19.8 ppm).
[0095] Calculation of the Triad Tacticity and Errors in Propylene Insertion: The calculation of the triad tacticity is outlined in the techniques shown in U.S. Pat. No. 5,504,172. Subtraction of the peak areas for the error in propylene insertions (both 2,1 and 1 ,3) from peak areas from the total peak areas of the second region and the third region, the peak areas based on the 3 propylene units-chains (PPP(mr) and PPP(rr)) consisting of head-to-tail bonds can be obtained. Thus, the peak areas of PPP(mm), PPP(mr) and PPP(rr) can be evaluated, and hence the triad tacticity of the propylene unit chain consisting of head-to-tail bonds can be determined. [0096] The LEEP copolymers have a triad tacticity of three propylene units, as measured by 13C NMR, of greater than 75%, or greater than 80%, or greater than 82%, or greater than 85%, or greater than 90%.
[0097] The test method for measuring the stereo- and region-errors in insertion of propylene (e.g., the proportion of inversely inserted propylene units based on 1 ,3 insertions and/or 2,1 insertions of the propylene) for the LEEP copolymer is described in U.S. Patent No. 6,525,157 from column 7, line 45 to column 9, line 29. The proportion of the 2,1 -insertions to all of the propylene insertions in the LEEP copolymer may be calculated by the following formula with reference to article in the journal Polymer, vol. 30 (1989), p. 1350:
Proportion of inversely inserted unit based on 2,1 -insertion (%) =
0.25U(structure(m + 0.5 Ufstructurefli)) x100 lαα + U(structure(ii) + 0.5(lαγ + U(structure(i)) + lαδ
[0098] Naming of the peaks in the above formula was made in accordance with a method by Carman, et al. in the journal Rubber Chemistry and Technology, volume 44 (1971 ), page 781 , where U denotes a peak area of the αδ+ secondary carbon peak. It is difficult to separate the peak area of labp (structure (i)) from lαiϊ (structure (N)) because of overlapping of the peaks. Carbon peaks having the corresponding areas can be substituted therefor.
[0099] The measurement of the 1 ,3 insertion requires the measurement of the βy peak. Two structures can contribute to the Uy peak: (1) a 1 ,3 insertion of a propylene monomer; and (2) from a 2,1 -insertion of a propylene monomer followed by two ethylene monomers. This peak is described as the 1.3 insertion peak and we use the procedure described in U.S. Pat. No. 5,504,172, which describes this βy peak and understand it to represent a sequence of four methylene units. The proportion (%) of the amount of these errors was determined by dividing the area of the βy peak (resonance in the vicinity of 27.4 ppm) by the sum of all the methyl group peaks and 1/2 of the area of the βy peak, and then multiplying the resulting value by 100. If an α-olefin of three or more carbon atoms is polymerized using an olefin polymerization catalyst, a number of inversely inserted monomer units are present in the molecules of the resultant olefin polymer. In polyolefins prepared by polymerization of .α.-olefins of three or more carbon atoms in the presence of a chiral metallocene catalyst, 2,1 -insertion or 1 ,3-insertion takes place in addition to the usual 1 ,2-insertion, such that inversely inserted units such as a 2,1- insertion or a 1 ,3-insertion are formed in the olefin polymer molecule (see, Macromolecular Chemistry Rapid Communication, Volume 8, page 305 (1987), by K.
Soga, T. Shiono, S. Takemura and W. Kaminski).
[00100] The proportion of inversely inserted propylene units of LEEP copolymers, based on the 2,1 -insertion of a propylene monomer in all propylene insertions, as measured by 13C NMR, is greater than 0.5%, or greater than 0.6%.
[00101] The proportion of inversely inserted propylene units of embodiments of our LEEP copolymers, based on the 1 ,3-insertion of a propylene monomer, as measured by 13C NMR, is greater than 0.05%, or greater than 0.06%, or greater than 0.07%, or greater than 0.08%, or greater than 0.085 percent.
[00102] The test method for measuring the reactivity ratios of the LEEP copolymer as described in U.S. Patent No. 6,525,157 from column 11 , lines 10-60 uses monomer sequence distribution. Starting with a polymer having a known average composition, the monomer sequence distribution can be determined using spectroscopic analysis. Carbon 13 nuclear magnetic resonance spectroscopy (13C NMR) can be used for this purpose, and can be used to establish diad and triad distribution via the integration of spectral peaks. (If 13C NMR is not used for this analysis, substantially lower
T1T2 products are normally obtained.) The reactivity ratio product is described more fully in Textbook of Polymer Chemistry, F. W. Billmeyer, Jr., lnterscience Publishers, New
York, p.221 et seq. (1957).
[00103] The reactivity ratio product ri r2, where T1 is the reactivity of ethylene and r2 is the reactivity of propylene, can be calculated from the measured diad distribution
(PP, EE, EP and PE in this nomenclature) by the application of the following formulae: rir2=4 [EE][PP][EP]2
T1= K11ZK12 = 2 X [EE]/[EP] r2= K22/K21 = 2 X [PP]/[EP]
P=[PP]+[EP]/2
E=[EE]+[EP]/2 where
MoI. %E = [(E)/(E+P)]*100;
X=E/P in reactor;
K11 and K12 are kinetic insertion constants for ethylene; and
K21 and K21 are kinetic insertion constants for propylene. [00104] As is known to those skilled in the art, a reactivity ratio product r,r2 of 0 can define an "alternating" copolymer, and a reactivity ratio product of 1 is said to define a "statistically random" copolymer. In other words, a copolymer having a reactivity ratio product T1T2 of between 0.6 and 1.5 is generally said to be random (in strict theoretical terms, generally only a copolymer having a reactivity ratio product nr2 greater than 1.5 contains relatively long homopolymer sequences and is said to be "blocky"). The LEEPO copolymers will have a reactivity ratio product T1 r2 of less than 1.5, or less than 1.3, or less than 1.0, or less than 0.8. The substantially uniform distribution of comonomer within polymer chains of the LEEP copolymer generally precludes the possibility of significant amounts of propylene units or sequences within the polymer chain for the molecular weights (weight average) disclosed herein.
[00105] The test method for measuring the intermolecular tacticity of the LEEP copolymer is described in U.S. Patent No. 6,525,157 from column 9, line 42 to column 10, line 15. The LEEP copolymers may have a statistically insignificant intermolecular difference of tacticity of polymerized propylene between different chains (intermolecularly). This is determined by thermal fractionation by controlled dissolution generally in a single solvent, at a series of slowly elevated temperatures. A typical solvent is a saturated hydrocarbon such as hexane or heptane. These controlled dissolution procedures are commonly used to separate similar polymers of different crystallinity due to differences in isotactic propylene sequences, as shown in the article in Macromolecules, Vol. 26, p2064 (1993). For the LEEP copolymers where the tacticity of the propylene units determines the extent of crystallinity, we expected this fractionation procedure will separate the molecules according to tacticity of the incorporated propylene.
[00106] In the LEEP copolymer, at least 75% by weight, or at least 80% by weight, or at least 85% by weight, or at least 90% by weight, or at least 95% by weight, or at least 97% by weight, or at least 99% by weight of the copolymer is soluble in a single temperature fraction, or in two adjacent temperature fractions, with the balance of the copolymer in immediately preceding or succeeding temperature fractions. These percentages are fractions, for instance in hexane, beginning at 0C and the subsequent fractions are in approximately 8 0C increments above 23°C Meeting such a fractionation requirement means that a polymer has statistically insignificant intermolecular differences of tacticity of the polymerized propylene. [00107] Fractionations have been done where boiling pentane, hexane, heptane and even di-ethyl ether are used for the fractionation. In such boiling solvent fractionations, LEEP copolymers will be totally soluble in each of the solvents, offering no analytical information. For this reason, the fractionation should be performed as described above and as detailed herein, to find a point within these traditional fractionations to more fully describe the copolymer and the surprising and unexpected insignificant intermolecular differences of tacticity of the polymerized propylene copolymer.
[00108] The test method for measuring the solid state proton nuclear magnetic relaxation time of the LEEP copolymer is described in U.S. Patent No. 6,525,157 from column 12, line 10 to 60 and Table I.
[00109] The principle of solid state proton NMR relaxation time (1H NMR T1p) and its relationship with polymer morphology have been discussed in Macromolecules 32 (1999), 1611. The experimental Tip relaxation data of the LEEP copolymer, and polypropylene (PP) homopolymer (control sample) are shown in U.S. Patent No. 6,525,157 FIG. 1 , which plots the natural log of the crystalline intensity versus time; the experimental procedure for collecting these data is described below. To fit the data with single exponential function, linear regression was performed on the In(I) vs. t data, where I is the intensity of the crystalline signal. Then, the quality of the fit, R2, is calculated. The R2 for a perfect linear correlation is 1.0. The R2 for polypropylene (control) and an exemplary LEEP copolymer are 0.9945 and 0.9967, respectively. Therefore, the T1p relaxation for both polypropylene homopolymer and an exemplary LEEP copolymer can be well fitted by a single-exponential. From the fit, the T1p of polypropylene and LEEP copolymer, are calculated as 25 milliseconds (ms) and 8.7 ms, respectively. The large difference in the T1p is reflective of their difference in morphology. [00110] The hypothetical polypropylene-like regions would have T1p relaxation similar to that in polypropylene homopolymer. As a result, should such regions exist in embodiments of the LEEP copolymers, the T1p relaxation would contain a component that has a T1p relaxation time characteristic of polypropylene homopolymer (i.e., T1p =25 ms). As seen in FIG. 1 of U.S. Patent No. 6,525,157 the relaxation of the LEEP copolymer can only be well fitted by a single exponential. Incorporation of a component whose Tip =25 ms would deteriorate the fit. This demonstrates that the LEEP copolymers of do not contain long continuous isotactic propylene units. In certain LEEP copolymers, the T1 p, relaxation time can be less than 18 ms, or less than 16 ms, or less than 14 ms, or less than 12 ms, or less than 10 ms.
[00111] Tip Measurement: The experiments are performed on a Bruker DSX-500
Nuclear Magnetic Resonance (NMR) spectrometer, with a 1H frequency of 500.13 MHz and 13C frequency of 125.75 MHz. The pulse sequence was a 90° (1H) pulse followed by spin lock and cross polarization ("CP"; time=0.1 ms). A spin lock field strength of Y1 =2τr*60 kHz is used. After the spin lock, the magnetization is transferred to 13C by CP and then the signal is detected. The crystalline methine signal at 26.7 ppm is recorded and normalized and its natural logarithm (Ln) is plotted against spin lock time. [00112] The ethylene concentration of the LEEP copolymer may be measured according to ASTM D3900 as described in U.S. Patent No. 6,525,157 from column 18, line 61 to column 19, line 12 as ethylene wt. % according to ASTM D3900 as follows. A thin homogeneous film of the copolymer component, pressed at a temperature of at or greater than 150 0C, is mounted on a Perkin Elmer PE 1760 infra red spectrophotometer. A full spectrum of the sample from 600 cm"1 to 4000 cm"1 is recorded, and the ethylene weight percent of the copolymer component is calculated from: Ethylene wt. % = 82.585 - 111.98X + 30.045X2
where X is the ratio of the peak height at 1155 cm"1 to peak height at either 722 cm'1 or 732 cm"1, which ever is higher.
[00113] Another example of a propylene elastomer which may be used is a region-error containing propylene-ethylene copolymer (i.e., a R-EPE copolymer) as described in U.S. Patent Application Publication No. 2003/0204017 (published October 30, 2003).
[00114] As disclosed in U.S. Patent Application Publication No. 2003/0204017
(published October 30, 2003) paragraph [0006], the R-EPE copolymers may be characterized as comprising at least about 60 weight percent (wt %) of units derived from propylene, about 0.1-35 wt % of units derived from ethylene, and 0 to about 35 wt % of units derived from one or more unsaturated comonomers, with the proviso that the combined weight percent of units derived from ethylene and the unsaturated comonomer does not exceed about 40. These copolymers are also characterized as having at least one of the following properties: (i) 13C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity, (ii) a B- value greater than about 1.4 when the comonomer content, i.e., the units derived from ethylene and/or the unsaturated comonomer(s), of the copolymer is at least about 3 wt %, (iii) a skewness index, S1x, greater than about -1.20, (iv) a DSC curve with a Tme that remains essentially the same and a Tmax that decreases as the amount of comonomer, i.e., the units derived from ethylene and/or the unsaturated comonomer(s), in the copolymer is increased, and (v) an X-ray diffraction pattern that reports more gamma-form crystals than a comparable copolymer prepared with a Ziegler-Natta (Z-N) catalyst. Typically the copolymers of this embodiment are characterized by at least two, preferably at least three, more preferably at least four, and even more preferably all five, of these properties.
[00115] The measurement of the 13C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm is described in U.S. Patent Application Publication No. 2003/0204017 (published October 30, 2003) paragraph 128: The data is collected using a Varian UNITY Plus 400 MHz NMR spectrometer, corresponding to a 13C resonance frequency of 100.4 MHz. Acquisition parameters are selected to ensure quantitative 13C data acquisition in the presence of the relaxation agent. The data is acquired using gated 1H decoupling, 4000 transients per data file, a 7 sec pulse repetition delay, spectral width of 24,200 Hz and a file size of 32K data points, with the probe head heated to 130 0C. The sample is prepared by adding approximately 3 mL of a 50/50 mixture of tetrachloroethane-d2/orthodichlorobenzene that is 0.025M in chromium acetylacetonate (relaxation agent) to 0.4 g sample in a 10 mm NMR tube. The headspace of the tube is purged of oxygen by displacement with pure nitrogen. The sample is dissolved and homogenized by heating the tube and its contents to 150 CC. with periodic refluxing initiated by heat gun.
[00116] The skewness index of the R-EPE copolymer is related to the shape of the curve for the temperature-rising elution fractionation test and can be determined using the method described in U.S. Patent Application Publication No. 2003/0204017 (published October 30, 2003) paragraphs 112-116:
[00117] The determination of crystallizable sequence length distribution can be accomplished on a preparative scale by temperature-rising elution fractionation (TREF). The relative mass of individual fractions can be used as a basis for estimating a more continuous distribution. L. Wild, et al., Journal of Polymer Science: Polymer. Physics Ed., 20, 441 (1982), scaled down the sample size and added a mass detector to produce a continuous representation of the distribution as a function of elution temperature. This scaled down version, analytical temperature-rising elution fractionation (ATREF), is not concerned with the actual isolation of fractions, but with more accuractely determining the weight distribution of fractions.
[00118] While TREF was originally applied to copolymers of ethylene and higher α-olefins, it can also be used for the analysis of copolymers of propylene with ethylene (or higher α-lefins). The analysis of copolymers of propylene requires higher temperatures for the dissolution and crystallization of pure, isotactic polypropylene, but most of the copolymerization products of interest elute at similar temperatures as observed for copolymers of ethylene. The following table is a summary of conditions used for the analysis of copolymers of propylene. Except as noted the conditions for TREF are consistent with those of Wild, et al., ibid, and Hazlitt, Journal of Applied Polymer Science: Appl. Polym. Symp., 45, 25(1990).
[00119] Parameters Used for TREF Parameter Explanation. Column type and size: stainless steel shot with 1.5 cc interstitial volume; mass detector: single beam infrared detector at 2920 cm'1; injection temperature: 150 0C; temperature control device: GC oven; solvent: 1,2,4-trichlorobenzene; concentration: 0.1 to 0.3% (weight/weight); cooling rate 1 : (140 0C to 120 0C) @ -6.0 °C/min; cooling rate 2: (120 0C to 44.5 0C) @ - 0.1 °C/min; cooling rate 3: (44.5 0C to 20 0C) @ -0.3 °C/min; heating rate: (20 0C to 140 0C) @ 1.8 °C/min; data acquisition rate: 12/min.
[00120] The data obtained from TREF are expressed as a normalized plot of weight fraction as a function of elution temperature. The separation mechanism is analogous to that of copolymers of ethylene, whereby the molar content of the crystallizable component (ethylene) is the primary factor that determines the elution temperature. In the case of copolymers of propylene, it is the molar content of isotactic propylene units that primarily determines the elution temperature. U.S. Patent Application Publication No. 2003/0204017 (published October 30, 2003) FIG. 5 is a representation of the typical type of distribution one would expect for a propylene/ethylene copolymer made with a metallocene polymer and an example of the R-EPE copolymer.
[00121] The shape of the metallocene curve in FIG. 5 is typical for a homogeneous copolymer. The shape arises from the inherent, random incorporation of comonomer. A prominent characteristic of the shape of the curve is the tailing at lower elution temperature compared to the sharpness or steepness of the curve at the higher elution temperatures. A statistic that reflects this type of assymetry is skewness. Equation 1 mathematically represents the skewness index, S1x, as a measure of this asymmetry.
[ ∑ w, * (Tl - Tmaxf ]1/3
S1x = (Equation 1 )
[ ∑ w, * (T, - Tmax)2 ]1/2
[00122] The value, Tmax> is defined as the temperature of the largest weight fraction eluting between 50 and 90 0C in the TREF curve. T1 and w, are the elution temperature and weight fraction respectively of an abitrary, ith fraction in the TREF distribution. The distributions have been normalized (the sum of the W1 equals 100%) with respect to the total area of the curve eluting above 300C. Thus, the index reflects only the shape of the crystallized polymer and any uncrystallized polymer (polymer still in solution at or below 3O0C) has been omitted from the calculation shown in Equation 1. [00123] The measurement of Tme and Tmax of the R-EPE copolymer is described in
U.S. Patent Application Publication No. 2003/0204017 (published October 30, 2003) paragraphs [0098] to [0100]:
[00124] Differential scanning calorimetry (DSC) is a common technique that can be used to examine the melting and crystallization of semi-crystalline polymers. General principles of DSC measurements and applications of DSC to studying semi-crystalline polymers are described in standard texts (e.g., E. A. Turi, ed., Thermal Characterization of Polymeric Materials, Academic Press, 1981 ). Certain of the R-EPE copolymers are characterized by a DSC curve with a Tme that remains essentially the same and a Tmax that decreases as the amount of unsaturated comonomer in the copolymer is increased. Tme means the temperature at which the melting ends. Tmax means the peak melting temperature.
[00125] Differential Scanning Calorimetry (DSC) analysis is determined using a model Q1000 DSC from TA Instruments, Inc. Calibration of the DSC is done as follows. First, a baseline is obtained by running the DSC from -90 0C to 290 0C without any sample in the aluminum DSC pan. Then 7 milligrams of a fresh indium sample is analyzed by heating the sample to 180 °C, cooling the sample to 140 0C at a cooling rate of 10 °C/min followed by keeping the sample isothermally at 140 0C for 1 minute, followed by heating the sample from 140 0C to 180 0C at a heating rate of 110 °C/min. The heat of fusion and the onset of melting of the indium sample are determined and checked to be within 0.5 0C. from 156.6 0C. for the onset of melting and within 0.5 J/g from 28.71 J/g for the heat of fusion. Then deionized water is analyzed by cooling a small drop of fresh sample in the DSC pan from 25 C° to -30 0C at a cooling rate of 10 °C/min. The sample is kept isothermally at -30 0C for 2 minutes and heated to 300C at a heating rate of 10 °C/min. The onset of melting is determined and checked to be within 0.5 0C from 0 0C.
[00126] The polypropylene samples are pressed into a thin film at a temperature of 190 0C. About 5 to 8 mg of sample is weighed out and placed in the DSC pan. The lid is crimped on the pan to ensure a closed atmosphere. The sample pan is placed in the DSC cell and the heated at a high rate of about 100 °C/min to a temperature of about 30 0C above the melt temperature. The sample is kept at this temperature for about 3 minutes. Then the sample is cooled at a rate of 10 °C/min to -40 0C, and kept isothermally at that temperature for 3 minutes. Consequently the sample is heated at a rate of 10 °C/min until complete melting. The resulting enthalpy curves are analyzed for peak melt temperature, onset and peak crystallization temperatures, heat of fusion and heat of crystallization, Tme, and any other DSC analyses of interest. [00127] The measurement of Tme and Tmax of the R-EPE copolymer is described in
U.S. Patent Application Publication No. 2003/0204017 (published October 30, 2003) paragraphs [0102] to [0105]:
[00128] "High B-value" and similar terms mean the ethylene units of a copolymer of propylene and ethylene, or a copolymer of propylene, ethylene and at least one unsaturated comonomer, is distributed across the polymer chain in a nonrandom manner. B-values range from 0 to 2 with 1 designating a perfectly random distribution of comonomer units. The higher the B-value, the more alternating the comonomer distribution in the copolymer. The lower the B-value, the more blocky or clustered the comonomer distribution in the copolymer. The high B-values of the R-EPE copolymers are typically at least about 1.3, preferably at least about 1.4, more preferably at least about 1.5 and most preferably at least about 1.7. The B-value is calculated as follows. [00129] B is defined for a propylene/ethylene copolymer as: f(EP+PE) B = 2 FEFP
[00130] where f(EP+PE)=the sum of the EP and PE diad fractions; and FE and FP
= the mole fraction of ethylene and propylene in the copolymer, respectively. B-values can be calculated for other copolymers in an analogous manner by assignment of the respective copolymer diads. For example, calculation of the B-value for a propylene/1 - octene copolymer uses the following equation: f(EO+PO)
Figure imgf000034_0001
[00131] For propylene polymers made with a metallocene catalyst, the B-values are typically between 1.1 and 1.3. For propylene polymers made with a constrained geometry catalyst, the B-values are typically between 0.9 and 1.0. In contrast, the B- values of the R-EPE copolymers, typically made with an activated nonmetallocene, metal-centered, heteroaryl ligand catalyst, are above about 1.4, typically between about 1.5 and about 1.85. In turn, this means that for any R-EPE copolymers, not only is the propylene block length relatively short for a given percentage of ethylene but very little, if any, long sequences of 3 or more sequential ethylene insertions are present in the copolymer, unless the ethylene content of the polymer is very high. [00132] The make-up of the elastomer is typically such that the elastomer is comprised of a substantial amount or entirely of polyolefin elastomer. Typically at least 50%, although possibly less, more typically at least about 70% and even more typically at least about 90% by weight of the elastomer is comprised of one or more of the above discussed polyolefin elastomers (e.g., a SLEP, a LEP, a polypropylene elastomer, or any combination thereof). It is also contemplated that the elastomer may be entirely, substantially entirely or consist essentially of one or more of the SLEPs1 LEPs or a combination thereof as discussed herein. Examples of a suitable material that includes or consists essentially of an SLEP or an LEP elastomer are commercially available from The Dow Chemical Company under the designation of ENGAGE® (e.g., including EG- 8100, EG-8150 and/or EG-8200). Examples of a suitable polypropylene elastomer include commercially available elastomers available from Dow Chemical Company under the designation of VERSIFY™ and from ExxonMobil Chemical Company under the designation of Vl STAM AXX ™.
[00133] It is also contemplated that the polymeric composition can include a variety of other additives such as surfactants, flexibilizers, ignition resistant additives, stabilizers, colorants, antioxidants, antistats, slip-aids (i.e., slip resistance aid), flow enhancers, nucleating agents, including clarifying agents, etc. For example, it will be understood that one or more pigments or colorants may be added to the polymeric composition such that the parts or components are "molded-in-color." Preferred examples of additives are ignition resistance additives, such as, but not limited to halogenated hydrocarbons, halogenated carbonate oligomers, halogenated diglycidyl ethers, organophosphorous compounds, fluorinated olefins, antimony oxide and metal salts of aromatic sulfur, or a mixture thereof may be used. Further, compounds which stabilize thermoplastic compositions against degradation caused by, but not limited to heat, light, and oxygen, or a mixture thereof may be used. One preferred additive is antioxidant, which, when included, is typically included in a relatively small weight percentage of the overall polymeric composition (e.g., less than about 1 or 2 percent). One preferred antioxidant is IRGANOX B225 antioxidant commercially available from Ciba Specialy Chemicals Corporation. Irganox B225 antioxidant is a blend of 1 part Irganox 1010 antioxidant (Tetrakis(methylene(3,5-di-t-butyl-4- hydroxyhydrocinnamate))methane) and 1 part lrgafos 168 tris(2,4-t-butylphenyl) phosphite. Another preferred additive is a demolding agent (e.g., a wax, mold relief or slip-aid). One preferred demolding agent is a nitrogen or ammonia group containing compound such as an amine or an amide. One preferred amide containing compound is ethylene bisstearamide (EBS). Another preferred category of mould release agents is "stearates" such as Glycerol MonoStearate commercially available from Danisco or Ciba Specialty Chemicals under the tradename Atmer. One preferred nitrogen containing compound, which is a wax, is an erucamide sold under the tradename KENAMIDE ULTRA E, commercially available from Chemtura Corporation, Middlebury, Connecticut. [00134] As can be appreciated, other additives are possible as well such as those disclosed in the U.S. Patent documents identified in the Background of the Invention. For example, as taught in paragraph 80 of 20060058434, the composition may include various additives such as UV absorber, neutralizing agent, blowing agent, foam inhibitor, and crosslinking agent. Furthermore as taught in 6,869,993 and 6,251 ,997, additional various additives may be included in the composition such as copper inhibitor, plasticizer, and foaming agent. Such additives may be incorporated into the composition physically, chemically, or both physically and chemically. Physical blowing agents typically undergo a physical change to form a foamed product. For example, a physical change may occur by converting a liquid to a gas under the influence of heat. One such physical blowing agent such as water, the like, or otherwise, forms a gas upon boiling the water. Chemical blowing agents are stable at normal temperatures and (typically) undergo a decomposition reaction at a certain temperature to produce the gas that forms the cells in the foamed part. For example, types of chemical blowing agents may include nitrogen containing compounds, acids such as citric acid, the like, or otherwise. [00135] The various components of the polymeric composition can be admixed and/or compounded according to a variety of protocols. Preparation of the filled polymeric composition of this invention can be accomplished using a variety of techniques. The ingredients may be mixed using an extruder or any of a variety of commercially available mixers.
[00136] When softened or melted by the application of heat, the filled thermoplastic compositions of this invention can be fabricated into articles using conventional techniques such as compression molding, injection molding, gas assisted injection molding, thermoforming, extrusion and/or blow molding, alone or in combination. The filled thermoplastic compositions can also be formed multi-layer laminates or extruded sheets, or can be compounded with one or more organic or inorganic substances, on any machine suitable for such purpose. The filled thermoplastic compositions of the present invention are preferably injection molded. [00137] In one preferred embodiment, it is contemplated that the ingredients of the polymeric composition are combined in such a manner that one or more ingredients are compounded together to form a first admixture, then compounding the remaining ingredients to form a second admixture followed by compounding the first admixture with the second admixture to form the polymeric composition. For example, the first admixture could be formed of the reinforcement material and the lower crystallinity thermoplastic polyolefin to form a reinforcement concentrate. The second admixture could be formed of the filler and the high crystallinity polyolefin to form a thermoplastic polyolefin matrix. Optionally the thermoplastic polyolefin matrix may further include the elastomer such as a polyolefin elastomer (e.g., ENGAGE), the demolding agent (e.g., the erucamide wax), the antioxidant, or any combination thereof. The highly crystallinity thermoplastic polyolefin matrix may further include an additive (such as the demolding agent (e.g., the erucamide wax), the antioxidant, the UV additives, the heat stabilizers, the like, or otherwise). Then, the reinforcement concentrate may be combined (e.g., melt mixed or blended) with the thermoplastic polyolefin matrix at a later time such as at the molding of the article (e.g., during or just prior to injection molding of the polymeric composition).
[00138] In another preferred embodiment, it is contemplated that the ingredients of the polymeric composition are combined in such a matter that the one or more ingredients are compounded to form a plurality of admixtures to be compounded with a high crystallinity thermoplastic polyolefin matrix. For example, the first admixture could be formed of the reinforcement material and a thermoplastic polyolefin to form a reinforcement concentrate. The second admixture could be formed of the filler and a thermoplastic polyolefin or combination of thermoplastic polyolefins and elastomer to form a filler concentrate. The thermoplastic polyolefin matrix may further include an additive (such as the demolding agent, the antioxidant, the like, or otherwise). Thereafter, the reinforcement concentrate and the filler concentrate may be combined (e.g., melt mixed or blended) separately or simultaneously with the thermoplastic polyolefin matrix at a later time such as at the molding of the article (e.g., during or just prior to injection molding of the polymeric composition).
[00139] In one exemplary method of formation, the present invention mixes a reinforcement concentrate with a mineral filler filled thermoplastic polyolefin compound on a molding machine to achieve a low warpage molded article. The reinforcement material may be introduced by way of a reinforcement concentrate that includes the reinforcement material in a thermoplastic polyolefin and more specifically, the reinforcement concentrate includes fibers (e.g., glass fibers) in PP. Preferably, the reinforcement concentrate includes at least about 40%, more typically at least about 60%, and even possibly, at least about 85% by weight of the reinforcement material (e.g., fibers), and particularly long glass fibers. Suitable reinforcement concentrates may contain from about 30 to about 95% by weight, preferably from about 50 wt.% to about 90 wt.% of the reinforcement material. The physical properties of the part thus achieved are comparable with a PP part having the same amount of long glass fibers content with the exception of having higher stiffness and/or improved impact performance. [00140] It is appreciated that glass fibers having a fiber length of at least about 1 mm are considered to be long glass fibers. The initial reinforcement concentrate may include long glass fibers having an average length of approximately greater than about 1 mm, preferably greater than about 5 mm, more preferably greater than about 7 mm, even more preferably greater than about 10 mm and most preferably between about 7 mm and about 25 mm.
[00141] The filler may be included in the bulk polyolefin matrix or may be introduced by way of a filler concentrate that includes the filler in a thermoplastic polyolefin. Preferably, the filler concentrate includes at least about 40%, more typically at least about 60%, and even more typically, at least about 90% by weight mineral filler, particularly talc. [00142] Furthermore, it is contemplated that the elastomer, when used, will typically be present in an amount less than 30%, more typically less than about 20%, and even more typically, less than about 10% by weight of the reinforcement concentrate, the filler concentrate, or both.
[00143] In view of the foregoing, it is contemplated that the reinforcement concentrate, the filler concentrate, the polyolefin matrix, or combinations thereof may be admixed in various orders. It is further contemplated that the reinforcement concentrate, the filler concentrate, the polyolefin matrix, or combinations thereof, may be separately fed through two or more feeds to a molding machine.
[00144] The invention, the process (e.g., the molding process), the polymeric composition, or both may achieve reduced warpage behavior in a molded part while maintaining existing property behavior as defined by impact resistance, Heat Distortion Temperature (thermal resistance), or both while still using standard molding equipment. Furthermore, stiffness properties may be increased without reducing the impact performance, thereby enhancing the impact/stiffness balance.
[00145] Advantageously, it has been found that desired properties (e.g., low warpage and other discussed herein or otherwise) can be achieved through a proper balance of thermoplastic polyolefin, reinforcement material, filler, and optionally polyolefin elastomer, particularly if those ingredients are chosen appropriately without the need for grafted polymers. Thus, it is contemplated that the polymeric composition of the present invention can be substantially with or without any grafted polymers or may consist essentially of non-grafted polymers. It is also contemplated, however, that such ingredients can be included in the polymeric composition unless otherwise indicated. [00146] The polymeric composition of the present invention can be employed in forming parts of a variety of articles of manufacture. For example, it can be used in forming articles such as a tray, a table, a plate, an appliance housing, a freezer container; lawn and garden furniture, building and construction sheets, a shoe, a boot, an outer ski boot shell, or an outer skate shell, snow mobile cowling or body cover, a personal water craft cowling or body cover, an all terrain vehicle cowling, fender, panel or body cover, an electrical equipment device housing, or the like. The polymeric composition may also be used to form automotive parts such as a panel, fascia (e.g., bumper fascia), automotive trim, door modules, closures, tailgates, front end carrier, body under the hood, automotive cowling, console (e.g., center overhead and/or floor assemblies) bumper beam, pillar, instrument panel, glove box assemblies including doors, knee bolster assemblies or instrument panel retainer assemblies or structural components.
[00147] The process for molding the parts may provide freedom to adjust the level of filler and/or elastomer to a bulk thermoplastic polyolefin matrix independently of the level of reinforcement material to achieve reduced warpage or warpage free parts. [00148] For the purpose of displaying the desirable properties achieved by the present invention, the polymeric composition was molded to form trays 10 and 12 as illustrated in Figs. 1A, 1B1 and 2, wherein tray 10 includes a top surface 14, a front edge 16, a rear edge 18, and left and right edges 20 and 22, respectively. Similarly, tray 12 includes a top surface 24, a front edge 26, a rear edge 28, and left and right edges 30 and 32, respectively. Advantageously, a tray as illustrated in Figs. 1A, 1 B, and 2 can have multiple desired properties such as reduced warpage when formed of the polymeric composition of the present invention. Tray 10, seen in a perspective view in Fig. 1A and in a frontal view on the left side of Fig. 2, is seen to be generally flat and having a low warpage. Tray 12, seen in a perspective view in Fig. 1B and in a frontal view on the right side of Fig. 2, is seen to be warped and nonplanar. T [00149] It will be understood that, whatever part or article is formed from the polymeric composition of the present invention, ingredients may be added to tailor the material to a particular use (e.g., it may be desirable to add a UV stabilizer to the material when used to form an exterior component of a vehicle).
[00150] The following examples illustrate various aspects of the present invention.
The values shown are approximate and should not be regarded as limiting of the inventions, unless otherwise specified. Variations in the processing parameters are possible as disclosed throughout the specification. In addition, the results shown may vary as well (e.g., by +/- 10% or +/- 25% of the stated values or even higher). [00151] Materials resulting from the teachings herein will have any combination of at least one, two (and more specifically at least 3 or all) of the following properties; namely, an E Modulus (ISO 527-2) that ranges from about 3000 to about 11 ,000 MPa, more specifically about 4000 to about 8000 MPa; an elongation at break that ranges from about 1.0 to about 4.0 %, more specifically about 2.0 to about 3.0 %; a notched Izod (ISO 180-1 A @ 230C) that ranges from about 5 to about 40; more specifically, from about 15 to about 30; a notched Izod (ISO 180-1 A @ -3O0C) that ranges from about 5 to about 45; a notched Izod (@ -4O0C) that ranges from about 10 to about 20; a flexural modulus ISO 178 that ranges from about 3000 to about 11000 MPa, more specifically, from about 4000 to 8000 MPa; heat distortion under load (ISO 75-A - HDT @ 1.82 MPa) greater than about 145 0C and more typically greater than about 150 0C; and warpage less than about 35 mm, preferably less than about 20 mm, and specifically less than about 10 mm and more specifically less than 5 mm as measured on the tray mould described herein.
[00152] EXAMPLES
[00153] Examples of formulations for polymeric compositions in accordance with the present invention are provided in Table I as well as properties measured for one of the polymeric compositions below:
TABLE I
Figure imgf000040_0001
[00154] For purposes of quantifying warpage, a tray warpage test is employed.
The warpage may be measured on injection molded trays having a wall thickness of about 3 mm and a dimension of about 395 mm x 245 mm x 25 mm, which are, for example, injection molded with a center cold sprue gate. Fig. 4, shows a perspective of a warped tray 10 placed on a flat surface 6 and held in place on three corners by a force, F. The geometry of the tray 10 is shown in Fig. 4 and Fig. 5. The measurement of the warpage is illustrated in Figs. 5, 5A, 5B, 5C, and 5D. Fig. 5 is a top view of the tray 10 on a surface 6. Fig. 5A is a cross section of Fig..5, through line A-A showing the left edge 20 of the tray 10. Fig. 5B is a cross section of Fig..5, through line B-B showing the right edge 22 of the tray 10. Fig. 5C is a cross section of Fig..5, through line C-C showing the rear edge 18 of the tray 10. Fig. 5D is a cross section of Fig..5, through line D-D showing the front edge 16 of the tray 10. Warpage, d, is quantified for the reinforced products by fixing three of the four corners to a flat (i.e., planar) surface 6 and measuring the distance along a line normal to the surface between the 4th corner (i.e. the free corner) and the flat surface. As seen in Fig. 2, the distortion of the part 10 is measured to be approximately 50 mm from the reference surface. The warpage of the part 12 molded from the LGF concentrate diluted into a talc filled polypropylene, such as INSPIRE DTF3800.00S (containing about 30 wt.% talc, about 20 wt.% elastomer and about 50 wt.% polypropylene and having a flexural modulus of about 1800 MPa). is measured to be approximately zero, as given by Example 1 (EX.1 ) in Table I. The warpage of the part molded from the LGF concentrated diluted in a talc filled polypropylene containing about 22 wt.% talc and about 78 wt.% polypropylene (and having a flexural modulus of about 2300 MPa) is measured to be about 23 mm, as given by Example 2 (EX.2( in Table I. Suitable polymeric material may have warpage measured according to this technique of less than about 30 mm, more typically, less than about 20 mm, even more typically less than about 5 mm, or even less than about 2 mm. The comparative example, (C.E.1 ), shown in Table I has a warpage greater than about 30 mm (e.g., about 52.5 mm).
[00155] The improvement in warpage behavior/reduction was an unexpected result. It was assumed that the filler, (relatively hard mineral filler), was breaking up the long glass fibers giving essentially a short glass (length less than about 1 mm) filled part, which has been seen to impart lower warpage. The physical properties of the molded samples were tested using the conventional ISO tensile bar insert according to ISO 3167 type 1A. If the fibers were broken, thereby defining short glass fibers, particular properties such as stiffness, impact resistance, and thermal performance would be observed as significantly reduced as typically found in short glass fiber molded parts. The results as shown in Figure 3 comprise examples containing a 60% LGF concentrate diluted to a 20% glass fiber content in the final part. However, the results did not show a significant drop in properties such as stiffness, impact resistance, or thermal performance, rather the polymeric composition based on a LGF PP system showed reduced warpage and enhanced physical properties.
[00156] From the data of Table I, it can be concluded that the polymeric system comprises of long glass fibers and a filler/elastomer compounded with a PP matrix results in equivalent impact and thermal behavior (e.g., the heat distortion temperature) to the systems based only on long glass fiber in PP, thereby indicating that the presence of a mineral filler in combination with additional rubber does not effect the stiffness performance of the polymeric composition. It is appreciated that the modulus values of Examples 1 and 2 (EX.1 and EX.2) for the first two samples, respectively, are significantly higher than the modulus values of C.E.1 , for example, approximately 20% higher.
[00157] Furthermore, it is appreciated that from the short to the long glass systems, the mechanical properties increased by about 50 to about 70% and the impact performance of the polymeric composition increased by about 300% for long glass fiber systems. By incorporating the filler/elastomer component within the system, an increase of the stiffness performances was shown without sacrificing the thermal properties of the polymeric composition. Furthermore, by incorporating the filler material within the system, a significant reduction of warpage resulted. [00158] Comparative Example 2 and Examples 3-6.
[00159] Comparative Example 2 (CE.2) is prepared by mixing a concentrate,
LGF concentrate 60 (containing about 60 wt.% long glass fibers in polypropylene) with a polypropylene copolymer having a flexural modulus of about 1450 MPa. The formulation and properties of the compound are shown in Table II.
[00160] Examples 3-6 (EX.3-6) are prepared by mixing the LGF concentrate 60 and the polypropylene copolymer used in comparative example 2 with a talc concentrate containing about 70 wt.% talc and about 30 wt% elastomer (e.g., a blend of about 15 wt.% ethylene elastomer and about 15 wt.% polypropylene elastomer and about 70 wt.% talc). CE. 2 and EX. 3-6 all contain about 20 wt.% long glass fiber. CE. 2 is free of talc, whereas EX. 3-6 contain from about 8 wt.% to about 20 wt.% talc as shown in Table II. [00161] The warpage is measured using the tray warpage test given for EX. 1 and
CE. 1. The warpage of CE. 2 and EX.3-6 are shown in Table II. The addition of talc and elastomer reduces the warpage. TABLE Il
Figure imgf000043_0001
[00162] Comparative Example 3 and Examples 7-10.
[00163] Comparative Example 3 (C.E.3) is prepared by mixing a concentrate,
LGF concentrate 60 (containing about 60 wt.% long glass fibers in polypropylene) with a polypropylene copolymer having a flexural modulus of about 1450 MPa. The formulation and properties of the compound are shown in Table III.
[00164] Examples 7-10 (EX.7-10) are prepared by mixing the LGF concentrate 60 and the polypropylene copolymer used in comparative example 3 with a talc concentrate containing about 70 wt.% talc and about 30 wt% elastomer (e.g., a blend of about 15 wt.% ethylene elastomer, about 15 wt.% polypropylene elastomer and about 70 wt.% talc). CE. 3 and EX. 7-10 all contain about 30 wt.% long glass fiber. CE. 2 is free of talc, whereas EX. 3-6 contain from about 8 wt.% to about 20 wt.% talc as shown in Table
III.
[00165] The warpage is measured using the tray warpage test given for EX. 1 and
CE. 1. The warpage of CE. 3 and EX.7-10 are shown in Table III. The addition of talc and elastomer reduces the warpage.
TABLE III
Figure imgf000043_0002
[00166] Comparative Example 4 and Examples 11-14.
[00167] Comparative Example 4 (CE.4) is prepared by mixing a concentrate,
LGF concentrate 60 (containing about 60 wt.% long glass fibers in polypropylene) with a polypropylene copolymer having a flexural modulus of about 1450 MPa. The formulation and properties of the compound are shown in Table IV.
[00168] Examples 11-14 (EX.11-14) are prepared by mixing the LGF concentrate
60 and the polypropylene copolymer used in comparative example 3 with a talc concentrate containing about 70 wt.% talc and about 30 wt% elastomer (e.g., a blend of about 15 wt.% ethylene elastomer, about 15 wt.% polypropylene elastomer, and about
70 wt.% talc). CE. 4 and EX. 7-10 all contain about 40 wt.% long glass fiber. CE. 2 is free of talc, whereas EX. 3-6 contain from about 5 wt.% to about 13 wt.% talc as shown in Table IV.
[00169] The warpage is measured using the tray warpage test given for EX. 1 and
CE. 1. The warpage of CE. 4 and EX.11-14 are shown in Table IV. The addition of the talc and the elastomer reduces the warpage.
TABLE IV
Figure imgf000044_0001
[00170] It should be understood that various ingredients may be substituted, added or removed from the above formulations without departing from the scope of the present invention. Moreover, it is contemplated that the weight percentages of the above ingredients and the values of the properties listed may vary up to or greater than ±5%, +10%, ±25% or ±50% of the values listed. For example, a value of 10 ±10% results in a range of 9 to 11.
[00171] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. Plural structural components or steps can be provided by a single integrated structure or step. Alternatively, a single integrated structure or step might be divided into separate plural components or steps. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of "comprising" or "including" also contemplates embodiments that "consist essentially of or "consist of the recited feature.
[00172] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the invention, its principles, and its practical application. Those skilled in the art may adapt and apply the invention in its numerous forms, as may be best suited to the requirements of a particular use. Accordingly, the specific embodiments of the present invention as set forth are not intended as being exhaustive or limiting of the invention. The scope of the invention should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes.

Claims

CLAIMSWhat is claimed is:
1. A polymeric composition for the manufacture of a shaped plastic article, comprising: i) a reinforcement concentrate including an admixture of at least one reinforcement material and a first polymeric material; ii) a filler concentrate including an admixture of a filler and a second polymeric material; and iii) a thermoplastic polyolefin; wherein the polymeric composition has a highly crystalline portion having a crystallinity of at least about 62 wt.%, wherein the highly crystalline portion of the polymeric composition is present at a concentration of at least about 30% by weight based on the total weight of the first polymeric material, the second polymeric material and the thermoplastic polyolefin.
2. A polymeric composition of claim 1 wherein the reinforcement material includes long glass fibers having an average fiber length greater than about 1 mm.
3. A polymeric composition of claim 1 or 2 wherein the reinforcement material is present at a concentration of at least about 40 wt.% based on the total weight of the reinforcement concentrate.
4. A polymeric composition of any of claims 1 to 3 wherein the filler is selected from the group consisting of talc, mica, and wollastonite.
5. A polymeric composition of any of claims 1 to 4 wherein the filler is present at a concentration of at least about 40 wt.% based on the total weight of the filler concentrate.
6. A polymeric composition of any of claims 1 to 5 wherein the filler is present at a concentration of at least about 60 wt.% based on the total weight of the filler concentrate.
7. A polymeric composition of any of claims 1 to 6 wherein the filler includes talc.
8. A polymeric composition of any of claims 1 to 7 wherein the first polymeric material, the second polymeric material, or both the first and second polymeric materials includes an elastomer, a polyethylene homopolymer, a polyethylene copolymer, a polypropylene homopolymer, a polypropylene copolymer, or any combination thereof.
9. A polymeric composition of any of claims 1 to 8 wherein the thermoplastic polyolefin is formed of a polyethylene homopolymer, a polyethylene copolymer, a polypropylene homopolymer, a polypropylene copolymer, or any combination thereof.
10. A polymeric composition of any of claims 1 to 9 wherein the reinforcement concentrate includes from about 30 to about 95% by weight of the at least one reinforcement material.
11. A polymeric composition of any of claims 1 to 10 wherein the polymeric composition includes from about 10 to about 50% by weight of the at least one reinforcement material.
12. A polymeric composition of any of claims 1 to 11 wherein the filler concentrate includes from about 30 to about 90 parts by weight of the filler.
13. A polymeric composition of any of claims 1 to 12 wherein the polymeric composition includes one or more elastomers selected from the group consisting of SLEPs, LEPs, polypropylene elastomers, and any combination thereof.
14. A polymeric composition of any of claims 1 to 13 wherein the polymeric composition includes an elastomer selected from the group consisting of SLEPs and LEPs.
15. A polymeric composition of any of claims 1 to 14 wherein the polymeric composition includes a polypropylene elastomer.
16. A polymeric composition of claim 1 , wherein the reinforcement material includes long glass fiber present at a concentration greater than about 40 wt.% based on the total weight of the reinforcement concentrate, the long glass fibers have an average fiber length greater than about 1mm, the first polymeric material includes a polypropylene, the filler is present at a concentration greater than about 40 wt.% based on the total weight of the filler concentrate, the second polymeric material includes an elastomer, the thermoplastic polyolefin comprises at least 75 wt.% of one or more polypropylenes, the elastomer is selected from the group consisting of SLEPs1 an LEP, polypropylene elastomer, or any combination thereof, and the elastomer is present at a concentration less than about 30 wt.% based on the total weight of the polymeric composition.
17. A polymeric composition of claim 16 wherein the elastomer includes a polypropylene elastomer having a propylene concentration greater than about 50 wt.%.
18. A polymeric composition of claim 16 or 17 wherein the elastomer includes an SLEP or an LEP.
19. A process for manufacturing a part having a composition according to any of claims 1 to 18 wherein the process comprises: providing:
(i) the reinforcement concentrate; (ii) the filler concentrate; and (iii) the thermoplastic polyolefin.
20. A process for manufacturing a part according to claim 19 wherein the process further comprises: admixing the reinforcement concentrate, the filler, and the thermoplastic polyolefin to form a polymeric composition; and shaping the polymeric composition into a part; wherein the second polymeric material, the thermoplastic polyolefin, or combinations thereof include a highly crystalline portion that is at least 30% by weight of (i), (ii), (iii), or combinations thereof.
21. The process of any claim 20 wherein the part exhibits a warpage of less than about 30 mm according to the tray warpage test.
22. The process as in claim 20 or 21 wherein the admixing step, includes a step of admixing the fiber concentrate and the filler concentrate prior to adding the thermoplastic polyolefin. .
23. The process as in any of claims 20 to 23 wherein the shaping step includes injection molding the polymeric composition, compression molding the polymeric composition, or both.
24. The process as in any of claims 20, 21 or 23, wherein the admixing step includes a step of mixing the thermoplastic polyolefin with at least a portion of either the filler concentrate or the reinforcement concentrate..
25. A molded part having at least one section containing the composition of any of claims 1 to 19.
26. A molded part having at least one section which is molded according to the process of any of claims 20 to 24.
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CN115181359A (en) * 2022-07-28 2022-10-14 江苏金发科技新材料有限公司 Low-warpage glass fiber reinforced polypropylene material and preparation method thereof

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