MXPA06009073A - Electrically-dissipative propylene polymer composition - Google Patents

Abstract

Disclosed are electrically-dissipative propylene polymer compositions with a desirable balance of improved flow marks, conductivity and a good balance of impact resistance and stiffness.

Description

COMPOSITION OF ELECTRICALLY DISSIPATING PROPYLENE POLYMER This invention relates to electrically dissipative propylene polymer compositions. More particularly, this invention relates to electrically dissipative propylene polymer compositions, which demonstrate reduced surface imperfections, such as flow marks, in injection molded articles. It is known to prepare coated articles by electrostatic painting methods. In such methods, a paint or coating is charged or ionized and atomized onto a conducting article, to earth, and the electrostatic attraction between the paint or coating and the grounded article results in a more efficient painting process with less waste paint material and thicker and more consistent paint coverage, particularly when the article has a complex shape. When articles made from metals are painted, the metal, which is inherently conductive, is easily landed and painted efficiently. In recent years, there has been an emphasis on the use of polymeric materials, such as propylene polymers, in the manufacture of articles, particularly in applications that require reductions in weight and improved corrosion resistance, such as automotive applications. However, the polymers normally used in such processes are insufficiently conductive to efficiently obtain a satisfactory coating thickness and paint when the article is painted electrostatically. In addition, such articles are also known to exhibit surface imperfections, such as flow marks and silver lines. Silver lines are generally associated with a phenomenon of overheating, while imperfections of flow marks appear to be associated with the viscosity, or flow capacity, of the resin. The flow marks are manifested on the surface of molded articles injected as a series of bands or stripes of high and low gloss, sometimes leading to the term tiger scratching. The general trend of each band is approximately perpendicular to the direction of fusion flow during injection. These marks do not perceptibly affect the mechanical properties of the molded article, nor are they discernible by touch. However, their presence is aesthetically unacceptable and frequently results in an unacceptably high quality control rejection rate due to the appearance of inhomogeneity within the molded parts. The effect is pronounced in large molded articles with a high aspect ratio, such as automotive parts, for example, instrument panels and defense fascia. Methods for the incorporation of conductive fillers into polymers, such as impact-modified propylene polymers, are known in order to improve their conductivity for use in electrostatic coating applications. For example, USP 5,484,838 describes a polymeric mixture taught so useful in the preparation of electrostatically paintable articles, which comprises a crystalline polymer, an amorphous polymer and electrically conductive carbon black, wherein at least a portion of the carbon black is dispersed within of the crystalline polymer. Another example is USP 5,844,037 which discloses a two-phase polymer blend shown as useful in the preparation of electrostatically paintable articles, comprising an electrically conductive carbon black, wherein the carbon black is dispersed primarily within the minor phase. However, the conductivity of articles made therefrom, the amount of carbon black necessary to provide a composition with a particular conductivity, the processing requirements for the preparation of such compositions, as well as the physical and / or surface appearance of electrostatically coated articles prepared from them, may be less than desirable for certain applications. The art has attempted to improve surface appearance properties in molded articles by decreasing the viscosity of the propylene polymer resin. This technique decreased the appearance of the flow marks, however, the decrease in viscosity can detrimentally affect other physical properties. Flow marks can also be decreased by tempering the article after the molding process. However, this tempering step is not commercially feasible or desirable in view of the increased energy required to temper the article, prolonged time for quenching and modification of equipment necessary to allow injection molding apparatus to also serve as tempering means. The technique also described adding low viscosity rubber components to polypropylene to improve the appearance of the resulting welded or injection molded articles, see USP 5,468,808. Numerous methods have been tried either to impart conductivity or to decrease the flow marks in the propylene polymer compositions, however, to the knowledge of the inventor, these methods have failed to produce a propylene polymer composition that is both electrically dissipative and have reduced flow marks. Thus, there is a need to reduce the flow marks in articles produced from electrically dissipative propylene polymer compositions. The present invention is such a desirable electrically dissipative propylene polymer composition. The composition possesses a desirable balance of improved flow marks, conductivity and a good balance of rigidity and hardness. The electrically dissipative propylene polymer composition of the present invention comprises a propylene block copolymer having a gum, preferably an EP gum, with an Mz equal to or greater than 1,000,000; a polyolefin elastomer, preferably a substantially linear ethylene polymer or a linear ethylene polymer; an electrically conductive carbon, preferably an electrically conductive carbon black, carbon fiber or graphite, which is preferably present in an amount sufficient to provide a surface resistivity of less than or equal to 1012 Ohms; optionally, an olefinic polymer, preferably HDPE; and optionally a filler, preferably talc. Another embodiment of the present invention is a process for extruding or molding the aforementioned electronically dissipative propylene polymer composition in a manufactured article. Still another embodiment of the present invention is the above-mentioned electronically dissipative propylene polymer composition in the form of a manufactured article, preferably an automotive part, eg, a fender, a facia, a tire cover, a door, a instrument panel, interior finish, metal cladding, oscillator panel or grill. Component (a) in the electrically dissipative propylene polymer compositions of the present invention is a propylene block copolymer. The propylene block copolymer suitable for use in this invention is well known in the literature and can be prepared by known techniques. In general, the propylene block copolymer is in the isotactic form, although other forms may also be used (for example, syndiotactic or atactic). The propylene block copolymer used for the present invention is preferably high crystalline. The propylene block copolymer used for the present invention comprises from 99 to 30 weight percent block (a) (i), which is a polypropylene homopolymer; a random copolymer of propylene and an alpha-olefin, preferably an alpha-olefin of C2 or C to C20; or combinations thereof. Block (a) (i) comprises 100 to 90 weight percent of propylene portions and 0 to 10 weight percent of alpha olefin moieties. As used herein, unless otherwise defined, the molecular weight is weight average molecular weight (Mw). In the present invention, the propylene polymer portion, block (a) (i), preferably has an Mw of equal to or greater than 100,000, more preferably equal to or greater than 125,000, and most preferably equal to or greater than 150,000. . The propylene polymer portion preferably has an Mw of equal to or less than 500,000, more preferably equal to or less than 300,000 and most preferably equal to or less than 250,000. The propylene block copolymer used for the present invention comprises 70 to 1 weight percent block (a) (ii), a gum portion, which is a copolymer of propylene and an alpha-olefin, preferably an alpha -olefin of C2 or c4 to C20; or combinations thereof. Block (a) (ii) comprises 70 to 30 weight percent of propylene moieties and 30 to 70 weight percent of an alpha olefin moiety. Examples of the alpha-olefins of C2 and C4 to C20 include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-ketene, Adezene, 1 -dodecene, 1 -hexadodecene, 4-methylene-1 -pentene, 2-methyl-1-butene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, diethyl-1-butene, trimethi-1-butene, 3-methyl-1-pentene, ethyl -1-penten, propyl-1-penten, dimethyl-1-penten, methylethyl-1-penten, diethyl-1-hexen, trimethyl-1-penten, 3-methyl-1-hexen, dimethyl-1-hexen, 3 , 5,5, -trimethyl-1 -hexene, methylethyl-1-heptene, trimethyl-1-heptene, dimethyl ketene, ethyl-1-ketene, methyl-1-N-ene, vinylcyclopenene, vinylcyclohexene and vinylnorbornene, where the branching position of alkyl is not specified is generally in position 3 or greater of the alkene. Ethylene is the preferred alpha-olefin. Preferably, the rubber portion has an Mw equal to or greater than 100, 000, more preferably equal to or greater than 150,000, and most preferably equal to or greater than 200,000. The rubber portion preferably has an Mw of equal to or less than 500,000, more preferably equal to or less than 400,000 and most preferably equal to or less than 300,000. It is also desirable that the rubber portion have a high Mz. A high Mz is defined as an Mz equal to or greater than 1,000,000, more preferably equal to or greater than 1,500,000 and most preferably equal to or greater than 2,000,000. A high Mz in the gum portion can be obtained, for example, by using low hydrogen gas in the feed, or not using hydrogen gas at all. It is also possible to add a compound which reduces the sensitivity of the catalyst to the hydrogen gas, for example, an ester, to the reaction mixture upon termination of the block polymerization (a) (i) and before the block polymerization (a) ) (ii). Block (a) (i) and block (a) (ii) are different phases. Block (a) (ii) can be dispersed in block (a) (i), block (a) (i) can be dispersed in block (a) (ii), or blocks (a) (i) and (a) (ii) can be co-continuous. Preferably, the gum portion, block (a) (ii), is dispersed in the propylene polymer portion, block (a) (i), as distinct gum particles. Preferably, 40 percent of the gum particles have a gum particle size equal to or less than 0.9 microns (μm), more preferably 40 percent of the gum particles have a gum particle size equal to or less than 0.6 μm, still more preferably 90 percent of the gum particles have a gum particle size equal to or less than 0.9 μm and most preferably 90 percent of the gum particles have a gum particle size equal to or less than 0.6 μm . Preferably, the average rubber particle size is equal to or less than 10 μm, more preferably equal to or less than 5 μm, and most preferably equal to or less than 2.5 μm. The propylene block copolymer of the present invention can be prepared by various processes, for example, in a single step or in multiple stages, by such a polymerization method as curing polymerization, gas phase polymerization, bulk polymerization, solution polymerization or a combination thereof using a metallocene catalyst or a so-called Ziegler-Natta catalyst, which is usually one comprising a solid transition metal component comprising titanium. In particular, a catalyst consisting of, as a solid / transition metal component, a solid composition of titanium trichloride which contains as essential components titanium, magnesium and a halogen; as an organo-metallic component an organoaluminum compound; and if an electron donor is desired. Preferred electron donors are organic compounds containing a nitrogen atom, a phosphorous atom, a sulfur atom, a silicon atom or a boron atom, and silicon compounds, ester compounds or ether compounds containing these atoms.

Propylene block copolymers are commonly made by catalytically reacting propylene in a polymerization reactor with appropriate molecular weight control agents. A nucleating agent is added after the reaction is completed in order to promote crystal formation. The polymerization catalyst should have high activity and be capable of generating highly tactical polymer. The reactor system must be capable of removing the polymerization heat from the reaction mass, so that the temperature and pressure of the reaction can be controlled appropriately. The melt flow rate (MFR) or melt index (Ml), in accordance with ASTM D 1238 (unless noted otherwise, conditions are 230 ° C and an applied load of 2.16 kilograms (kg)) of the electrically dissipative propylene polymer composition of the present invention is equal to or greater than 0.1 grams / 10 minutes (g / 10 min), preferably greater than 0.5 g / 10 min, more preferably greater than 1 g / 10 min , and even more preferably greater than 2 g / 10 min. The melt flow rate for the propylene copolymer useful herein is generally less than 1 00 g / 10 min. , preferably less than 50 g / 10 min, more preferably less than 25 g / 10 min and more preferably less than 15 g / 10 min. The propylene block copolymer is present in an amount equal to or greater than 30 parts by weight, preferably equal to or greater than 35 parts by weight, more preferably equal to or greater than 40 parts by weight, and most preferably equal to or greater than 45 parts by weight. parts by weight, based on the weight of the electrically dissipative polymer composition.

The propylene block copolymer is present in an amount equal to or less than 90 parts by weight, preferably equal to or less than 80 parts by weight, more preferably equal to or less than 70 parts by weight, and most preferably equal to or less than 80. parts by weight, more preferably equal to or less than 70 parts by weight, and most preferably equal to or less than 65 parts by weight based on the weight of the electrically dissipative polymer composition. Component (b) in the compositions of this invention is a polyolefin elastomer. Suitable polyolefin elastomers comprise one or more C2 to C20 alpha-olefins in polymerized form, having a glass transition temperature (Tg) less than 25 ° C, preferably less than 0 ° C, most preferably less than -25 ° C. Tg is the temperature or range of temperatures at which a polymeric material shows an abrupt change in its physical properties, including, for example, mechanical force. The Tg can be determined by differential scanning calorimetry. Examples of the types of polymers from which the polyolefin elastomers present are selected include copolymers of alpha-olefins, such as copolymers of ethylene and propylene (EPR), ethylene and 1-butene (EBR), ethylene and 1 -hexene or ethylene and 1-ketene, and terpolymers of ethylene, propylene and a diene comonomer, such as hexadiene or ethylene norbornene (EDPM). The polyolefin elastomer is compatible, or miscible, with the rubber phase of the propylene block copolymer. The resulting combination of the polyolefin elastomer and the rubber phase comprise the elastomeric phase of the electrically dissipative propylene polymer composition. Preferably, the polyolefin elastomer is one or more substantially linear ethylene polymers or one or more linear ethylene polymers (S / LEP), or a mixture of one or more of each. Both substantially linear ethylene polymers and linear ethylene polymers are known. The substantially linear ethylene polymers and their method of preparation are fully described in USP 5,272,236 and USP 5,278,272. The linear ethylene polymers and their method of preparation are fully described in USP 3,645,992; USP 4,937,299; USP 4,701, 432; USP 4,937,301; USP 4,935,397; USP 5,055,438; EP 129,368; EP 260,999; and WO 90/07526. As used herein, a "linear ethylene polymer" means an ethylene homopolymer or a copolymer of ethylene and one or more alpha-olefin comonomers having a linear backbone (ie, without crosslinking), no long chain branching , a nw molecular weight distribution and, for alpha-olefin copolymers, a nw composition distribution. Also, as used herein, "a substantially linear ethylene polymer" means an ethylene homopolymer or a copolymer of ethylene and one or more alpha-olefin comonomers having a linear backbone, a specific and limited amount of branching long chain, a nw molecular weight distribution and, for alpha-olefin copolymers, a nw composition distribution. Short chain branches in a linear copolymer arise from the pendant alkyl group resulting from the polymerization of C3 to C20 alpha-olefin comonomers intentionally added. The distribution of nw composition is also sometimes referred to as homogeneous short chain branching. The nw composition distribution and the homogeneous short chain branching refer to the fact that the alpha-olefin comonomer is randomly distributed within a given copolymer of ethylene and an alpha-olefin comonomer and virtually all copolymer molecules have the same ratio of ethylene to comonomer. The nwness of the composition distribution is indicated by the value of the composition distribution branching index (CDBI) or sometimes referred to as the Short Chain Branching Discrimination Index. The CDBI is defined as the weight percentage of the polymer molecules having a comonomer content within 50 percent of the average molar comonomer content. CDBI is easily calculated, for example, by employing the temperature elevation levigation fractionation, as described in Wild, Journal of Polymer Science, Polymer Physics Edition, volume 20, page 441 (1 982), or USP 4,798,081. The CDBI for the substantially linear ethylene copolymers and the linear ethylene copolymers in the present invention is greater than 30 percent, preferably greater than 50 percent, and more preferably greater than 90 percent. The long chain branches in substantially linear ethylene polymers are polymer branches other than short chain branches. Normally, the long chain branches are formed by in situ generation of an oligomeric alpha-olefin via elimination of beta-hydride in a growing polymer chain. The resulting species is a vinyl-terminated hydrocarbon of relatively high molecular weight, which upon polymerization produces a long pendant alkyl group. The long chain branching can further be defined as hydrocarbon branches to a polymer backbone having a chain length greater than n minus 2 ("n-2") carbons, where n is the carbon number of the ala-olefin comonomer longer intentionally added to the reactor. Preferred long chain branches in ethylene homopolymers or ethylene copolymers and one or more C3 to C20 alpha-olefin comonomers have at least 20 carbons to more preferably the number of carbons in the polymer backbone from which the branching this slope. The long chain branching can be distinguished using 13C nuclear magnetic resonance spectroscopy alone, or with laser light scattering-gel permeation chromatography (GPC-LALS) or an analytical technique. Ethylene polymers substantially layered contain at least 0.01 long chain / 1000 carbon branches and preferably 0.05 long chain / 1000 carbon branches. In general, the substantially linear ethylene polymers contain less than or equal to 3 long chain branches / 1000 carbons and preferably less than or equal to 1 long chain branch / 1000 carbons. Preferred substantially linear ethylene polymers are prepared by using metallocene-based catalysts capable of readily polymerizing high molecular weight alpha olefin copolymers under the process conditions. As used herein, the copolymer means a polymer of two or more comonomers intentionally added, for example, as may be prepared by polymerizing ethylene with at least one other C3 to C20 comonomer. Preferred linear ethylene polymers can be prepared in a similar manner using, for example, metallocene or vanadium-based catalyst under conditions that do not allow the polymerization of monomers other than those intentionally added to the reactor. Other basic characteristics of substantially linear ethylene polymers or linear ethylene polymers include a low residue content (ie, a low concentration thereof of the catalyst used to prepare the polymer, unreacted comonomers and low molecular weight oligomers made during the course of polymerization), and a controlled molecular architecture, which provides good processability even when the molecular weight distribution is narrow in relation to conventional olefin polymers. Although substantially linear ethylene polymers or linear ethylene polymers used in the practice of this invention include substantially linear ethylene homopolymers or linear ethylene homopolymers, preferably substantially linear ethylene polymers or linear ethylene polymers comprise between 50 90 percent by weight of ethylene and 5 to 50, and preferably 10 to 25 percent by weight of at least one alpha-olefin comonomer. The comonomer content in substantially linear ethylene polymers or linear ethylene polymers is generally calculated based on the amount added to the reactor and how it can be measured using infrared spectroscopy according to ASTM D-2238, Method B. Typically, polymers substantially linear ethylene or linear ethylene polymers are copolymers of ethylene and one or more C3 to C20 alpha-olefins, preferably copolymers of ethylene and one or more alpha-olefin comonomers of C3 to C10, and more preferably copolymers of ethylene and one or more comonomers selected from the group consisting of propylene, 1-butene, 1-hexene, 4-methyl-1-pentane and 1-ketene. Most preferably, the copolymers are copolymers of ethylene and 1-ketene. The density of these substantially linear ethylene polymers or linear ethylene polymers is equal to or greater than 0.850 grams per cubic centimeter (g / cm3) and preferably equal to or greater than 0.860 g / cm3. In general, the density of these substantially linear ethylene polymers or linear ethylene polymers is less than or equal to 0.935 g / cm3 and preferably less than or equal to 0.900 g / cm3. The melt flow rate for substantially linear ethylene polymers, measured as l? 0 / l2, is greater than or equal to 5.63, is preferably from 6.5 to 15, and is more preferably from 7 to 10. I2 is measured from according to the designation ASTM D 1238 using the conditions of 190 ° C and 2.1 6 kilograms ("kg") of dough. I2 is measured according to the designation of ASTM D 1238 using the conditions of 190 ° C and 10.0 kg of mass. The molecular weight distribution (Mw / Mn) for substantially linear ethylene polymers is the weight average molecular weight (Mw) divided by the number average molecular weight (Mn). Mw and Mn are measured by gel permeation chromatography (GPC). For substantially linear ethylene polymers, the ratio of l10 / l2 indicates the degree of long chain branching, that is, the higher the ratio of l10 / l2, the longer chain branching exists in the polymer. In preferred linear substantially ethylene polymers the Mw / Mn is related to I? 0 / I2 by the equation: Mw / Mn <; (l? 0/12) - 4.63. In general, Mw / Mn for substantially linear ethylene polymers is at least 1.5 and preferably at least 2.0 and is less than or equal to 3.5, more preferably less than or equal to 3.0. In a highly preferred embodiment, the substantially linear ethylene polymers are also characterized by a single differential scanning calorimetry (DSC) melting peak. The preferred l2 melt index for these substantially linear ethylene polymers or linear ethylene polymers is from 0.01 g / 10 min, to 100 g / 10 min, and more preferably 0.1 g / 10 min to 10 g / 10 min. The polyolefin elastomer is employed in the blends of the present invention in amounts sufficient to provide the desired balance of processability and impact resistance. In general, the substantially linear ethylene polymer or linear ethylene polymer is employed in amounts equal to or greater than 5 parts by weight, preferably equal to or greater than 10 parts by weight, more preferably equal to or greater than 15 parts by weight, and most preferably equal to or greater than 20 parts by weight based on the weight of the electrically dissipative propylene composition. In general, the polyolefin elastomer is used in amounts less than or equal to 70 parts by weight, preferably less than or equal to 60 parts by weight, more preferably less than or equal to 50 parts by weight, even more preferably less than or equal to 35 parities by weight and most preferably less than or equal to 40 parts by weight based on the weight of the electrically dissipative propylene composition. The component (c) of the present invention is an electrically conductive carbon. The term "electrically conductive carbon" as used herein, refers to electronically conductive grades of carbon black, carbon fibers, graphite, or combinations thereof. Suitable carbon fibers include fiber agglomerates having an aspect ratio of at least five and a diameter in the range of 3.5 to 70 nanometers (nm) as described, for example, in WO 91/03057. Suitable graphite particles have a size in the range of 1 to 30 μm and a surface area in the range of 5 to 100 square meters per gram (m2 / g). Examples of suitable carbon blacks include carbon particles having an average primary particle diameter of less than 125 nm, more preferably less than 60 nm. The carbon black is preferably used as an aggregate or agglomerate of primary particles, the aggregate or agglomerate normally having a size of 5 to 10 times the size of primary paricule. The larger agglomerates, beads or pellets of carbon particles can also be used as a starting material in the preparation of the composition, as long as they are dispersed during the preparation or processing of the composition sufficient to reach an average size in the composition. cured composition of less than 10 μm, more preferably less than 5 μm and most preferably less than 1.25 μm. The carbon black preferably has a nickel surface area of at least 125 m2 / g, more preferably at least 200 m2 / g. The niologen surface area of the carbon black can be determined using the ASTM method no. D 3037-93. Absorption of phytalide from carbon styrene is preferably at least 75 cubic centimeters per 100 grams (cm 3/100 g), more preferably at least 1 00 cm 3/100 g, and can be measured according to the ASTM method no. 3 2414-93. The electrically conductive carbon is preferably used in a quantity, based on the weight of the composition, of equal to or greater than 0.1 parts by weight, more preferably equal to or greater than 0.5 parts by weight, even more preferably equal to or greater than 1. give rise to weight, more preferably equal to or greater than 5 paries by weight, and most preferably equal to or greater than 7 paries by weight. The electrically conductive carbon preferably is used in a quantity equal to or less than 30 per cent.more preferably equal to or less than 25 parishes by weight, even more preferably equal to or less than 20 paries by weight, and most preferably equal to or less than 18 paries by weight. If desired, mixtures of electrically conductive carbons with different properties can also be used. In one embodiment, the carbon blacks having a nihinogen surface area of less than 500 m2 / g and an absorption of dibutyl phthalate of less than 250 cm 3/100 g can be used in combination with carbon blacks, resulting in higher surface areas of niíógeno and numbers of filolaío of dibuíilo absorption. The component (d) is an olefinic polymer. The olefinic polymer may be a polyethylene, such as high density polyethylene (HDPE), linear low density polyethylene (LLDPE), or high density polyethylene (HDPE), polyolefin elastomer (selected from the polyolefin elasiomers described in present it with the proviso that a second polyolefin elastomer which is different from the first polyolefin elasomer component (b)), or combinations thereof. The olefinic polymer is employed in the present invention in amounts sufficient to provide the desired balance of processability, stiffness and resistance to impaction. Preferably, the olefinic polymer is comparable to the polyolefin elasíomer and / or the gum portion of the propylene block copolymer. In other words, the polyolefin elastomer and the olefin polymer will comprise a phase of the propylene polymer phase, block (a) (i). the rubber portion, block (a) (ii), can be dissipated in the propylene polymer phase, block (a) (i); the polyolefin elasiomer phase; or both. If present, the olefinic polymer is employed in amounts of equal to or greater than 1 part by weight, preferably equal to or greater than 2 parts by weight, and most preferably equal to or greater than 3 parts by weight based on the weight of the electrically dissipative propylene composition. In general, the olefin polymer is used in amounts less than or equal to 15 parts by weight, preferably less than or equal to 12 parts by weight, and most preferably less than or equal to 10 parts by weight based on the weight of the electrically dissipative propylene composition. Fillers that may be present in the composition include talc, wollastonite, clay, single layers of a layered silicate material, cation exchanger, graphite, calcium carbonate, feldspar, nepheline, silica or glass, smoked silica, alumina, magnesium, zinc oxide, barium sulfate, aluminum silicate, calcium silicate, titanium dioxide, titanates, glass microspheres or chalk. Of these fillers, talc, wollastonite, clay, calcium carbonate, silica / glass, alumina and titanium dioxide are preferred and talc is highly preferred. Ignition resistance fillers that can be used in the composition include antimony oxide, alumina trihydrate; magnesium hydroxide; borates, halogenated compounds, such as, but not limited to, halogenated hydrocarbons, halogenated carbonaceous oligomers, halogenated diglycidyl ethers; organophosphorus compounds, fluorinated olefins; and metal salts of aromatic sulfur, or a mixture thereof may be used. Of solids filled with respect to ignition, alumina trihydrate and magnesium hydroxide are preferred. Other miscellaneous fillers include wood fibers / flours / flakes, cotton, starch, glass fibers, synfèfic fibers (for example, polyolefin fibers) and carbon fibers. In some cases, it has been discovered that the addition of non-conductive filler flakes increased the conductivity of the composition. If used, they may be present in a quantity of at least 0.1 moles, preferably at least 1 part, more preferably at least 2 parts, and most preferably at least 5 parts by weight based on the total weight of the composition. . In general, the filler is present in an amount less than or equal to 30 parts, preferably less than or equal to 25 parts, more preferably less than or equal to 20 parts, more preferably less than or equal to 15 parts, and very preferably less than or equal to 10 parts by weight based on the total weight of the composition. In addition, the claimed electrically dissipative propylene polymer compositions may also optionally contain one or more additives that are commonly used in propylene copolymer compositions. Preferred additives of this type include, but are not limited to: stabilizers, said compositions stabilize polymer compositions against degradation caused by, but not limited to, heat, light and oxygen; colorants; antioxidants; antistatic; flow intensifiers; mold releasers, such as meatal stearals (eg, calcium stearate, magnesium stearate); nucleating agents, including clarifying agents; gliding agents (e.g., erucamide, oleamide, linoleamide, or esaramide); or a mixture thereof can be used. If used, the additives may be present in an amount of at least 0.01 parts, preferably at least 0.05 parts, more preferably at least 0.1 parts, more preferably at least 0.5 parts and most preferably at least 1 part by weight based on the total weight of the composition. In general, the additive is present in a quantity less than or equal to 10 parts, preferably less than or equal to 5 parts, more preferably less than or equal to 3 parts, more preferably less than or equal to 2 parts., and most preferably less than or equal to 1.5 parts by weight based on the total weight of the composition. The electrically dissipative propylene polymer compositions of the present invention are thermoplastic and comprise at least two phases. A first phase comprises the propylene polymer portion, block (a) (i), and a second phase, comprises the polyolefin elastomer and optionally the olefin polymer. In the present invention, preferably the second phase comprising the polyolefin elastomer is continuous. Preferably, the first and second phases are co-continuous. The rubber portion of the propylene block copolymer, block (a) (ii), may be distributed only in the first phase, only in the second phase, or partially in each phase. Preferably, the rubber portion is partially distributed in the first and second phases. In the composition of the present invention, the dissolution of the electrical carbon leads to the first phase and the second phase is not critical, as long as the electrolytic propylene composition is capable of dissipating an electrical charge, normally a surface resistivity of equal to or less than 1012 Ohms meets this requirement. However, it is preferable that the electrically conductive carbon be dispersed in the second phase in a quantity of equal to or greater than 50 percent, more preferably equal to or greater than 60 percent, still more preferably equal to or greater than 80 percent, yet more preferably equal to or greater than 90 percent and most preferably 100 percent of the electrically conductive carbon is dispersed within the second phase. The electrically dissipative propylene polymer composition of the present invention can be prepared by any convenient method, including dry blending the individual components and subsequently mixing the melt, either (1) by mixing the pre-melt in a separate mixer (per example, a Banbury mixer), (2) directly in a single or double screw extruder used to make pellets, sheet or profile of the composition, or (3) in an extruder capable of forming the finished article (for example, the parfa auíomoíriz), íal as an injection molding machine or a extrusion blow molding machine. The pre-melting mixing of the components can be carried out, for example, by wet mixing or dry mixing pellets or powders of the polymers and the electrically conductive carbon, which can then be optionally further mixed in a roller kneader. elevated lemperaires. In another embodiment, the solutions of the polymer (s) can be mixed with the electrically conductive carbon in a liquid medium. The amount of electrically conductive carbon that becomes dispersed in the elastomeric phase is influenced by various facors, including the relative free surface energies of the components, the relative viscosities of the polymers present and the configuration and duration of mixing. The process for preparing the composition and the relative qualities of the components can also affect the low lemoperauri force of the composition. The composition and the method for its preparation are preferably optimized experimentally to achieve the best combination of conductivity and physical properties, depending on the structural application for which the composition is to be used. There are many types of molding operations, which can be used to form articles or matrices made from the electrically dissipative propylene polymer compositions described herein, including various injection molding processes (e.g., as described in Modern). Plastics Encyclopedia / 89, Mid October 1988 Issue, vol 65, No. 1 1, pp. 264-268, "Inlroduction to Injection Molding" and on pp. 270-271, "Injection Molding Thermoplastics" (Thermoplastic injection molding) and blow molding processes (for example, as described in Modern Plasfics Encyclopedia / 89, Mid Ociober 1988 Issue, vol 65, No. 1 1, pp. 217 -218, "Exírusion-Blow Molding" (Extrusion-blow molding) and profile exfrusion. Examples of fabricated aries include aulomoiric paris, such as fenders, facia, hobby covers, doors, inscription panels, a bottom finish, a metal cladding, an oscillating panel, grills, as well as other home and personal items, including, for example , recipients for freezer. The composition preferably has a strength equal to or less than 1010 Ohms, more preferably equal to less than 105 Ohms, and even more preferably equal to or less than 10 Ohms. The term "resilience", as used in the present, refers to the surface resistivity of the composition in solid form, as can be measured in accordance with the procedure set forth in the following examples. Once fabricated, the electrically conductive arc can be painted or coated on at least one of its surfaces using any suitable elecrolymer coating process. The term "electrochromic coating process", as used in the present, refers to any coating process where there is an electrical potential between the sub-surface being coated and the coating material. Examples of electrochemical coating processes include electrostatic coating of liquids or powders, electrodeposition processes ("E-Coat"), electroshock vapor deposition and electroplating processes. The article can be pinnated or coated with any water-based or organic-based composition (or water / organic mixture), including primary conductive compositions which additionally increases the elecronic conductivity of the arithmetic or with a composition without solvency by a coating method. in powder or vapor deposition. Unless indicated otherwise, the following test terms and procedures referred to herein are defined as follows: Density is measured in accordance with ASTM D-792. The samples are tempered at ambient conditions for 24 hours before the measurement is imitated. The molecular weight is determined by using gel permeation chromatography (GPC) in a 150 ° C high-wapers chromatographic unit equipped with three columns of mixed porosity (Polymer Laboratories 103, 104, 105 and 106), operating at a System temperature of 140 ° C. The solution is 1, 2,4-arylbenzene, from which solutions of 0.3 per cent by weight of the samples for injection are prepared. The flow rate is 1.0 milliliter per minute (ml / min) and the injection size is 100 microliters. Molecular weights are determined by means of gel permeation chromatography (GPC) in an alpha-temperature chromatography unit Polymer Laboratories PL-GPC-220 of high temperaure equipped with linear mixed bed columns, 300 x 7.5 mm (Polymer Laboratories PLgel Mixed B (particle size of 10 microns)). The oven temperature is at 160 ° C with the hot zone of the auosomatter at 160 ° C and the zone heated at 145 ° C. The solvent is 1,2,4-chlorobenzene confining 200 ppm of 2,6-di-1-buyl-4-methyl-phenol. The flow rate is 1.0 milliliter / minute and the injection size is 100 microliters. A 0.15 percent by weight solution of the sample for injection is prepared by dissolving the sample in 1, 2,4-trichlorobenzene purged with nitrogen containing 200 ppm of 2,6-di-f-bufil-4-meitylphenol for 2.5 ha. 160 ° C with soft mixing. The molecular weight defermination is deduced by using ten narrow molecular weight distribution polystyrene standards (from Polymer Laboratories, EasiCal PS1 varying from 580-7,500,000 g / mol) in conjunction with their levigation volumes. The molecular weights of polypropylene equivalents are determined by using appropriate Mark-Houwink coefficients for polypropylene (as described by Th. G. Scholte, N.L.J. Meijerink, H.M. Schoffeleers and A.M.G. Brands, J. Appl.

Polym. Sci. 29, 3763-3782 (1984)) and polyesirene (as described by E. P. Orocka, R.J. Roe, N. Y. Hellman, P.M. Muglia, Macromolecules, 4, 507 (1 971)) in the Mark-Houwink equation: . { ? } = KMa where Kpp = 1 .90E-04, app = 0.725 and Kps = 1 .26E-04, aps = 0.702. The size of the rubber particle is determined as follows: 1. Sample preparation. The injection molded bars are examined near the center of the bars, so that the sections could be parallel to the direction of injection molding in the skin and core (approximately 1500 microns below the outer surface). The faces of the sample block are traversed with a shaver and cryo-polish before staining. The cryo-polished blocks are pre-stained with RuO vapors for 3 hours at ambient temperature. The stain solution is prepared by weighing 0.2 grams of Ruinium chloride hydrate (III) (RuCI3 x H2O) in a glass beaker with a screw lid and adding 10 milliliters (ml) of aqueous sodium hypochlorite at 5.25 per cent. to the jar. The samples are placed in the glass jar using a glass slide with double-sided film. The slide is placed on the bottle in order to suspend the blocks approximately 25.4 mm (1 in) above the staining solution. The blocks are exposed to the vapor phase of the staining solution for 3 hours at ambient temperature. Sections of approximately 100 nanometers in thickness are collected at ambient temperature using a diamani knife on a Leica UCT microtome. Sections are placed on virgin TEM screens of 400 mesh for observation. 2. Technique. Transmission electron micrograph images Bright field (TEM) are captured on Polaroid SO-163 film using a Hilachi H-8100 operated at an acceleration voltage of 100 kilovolts (kV). 3. Analysis of images. Image analysis is performed using a Leica Qwin Pro V2.4 computation program on 15kX TEM images. The selected increment for image analysis depends on the number and size of paris to be analyzed. 579 characteristics of the three images are measured. In order to allow the generation of binary images, the manual embedding of the rubber particles of the TEM impressions is done using a black Sharpie extra-fine dot marker. The traced TEM images are scanned using a Hewlett Packard Sean Jet 4c to generate digilals images. Digital images are embedded in the Leica Qwin Pro V2.4 program and converted to binary images by adjusting a gray level threshold to include the characteristic of inferes. Once binary images are achieved, other parameters are used to create an- imal images of image analysis. Some of these characteristics included removing edge features, accepting or excluding features, and manually modifying features that required separation. Once the pariículas in the images are measured, the dimensioning data was exported in an Excel sheet that was used to create bin ranges for the rubber particles. Sizing damages are placed in appropriate bin ranges and a histogram of particle lengths (maximum particle distance) is generated against frequency percentage. The parameters that are calculated are minimum, maximum, average, and standard deviation of the rubber particles. The reported values are the percentage of rubber particles with a particle size smaller than 0.6 μm. The following examples illustrate the invention, but are not intended to limit it in any way. Unless otherwise stated, all amounts are weight by weight based on the weight of the electrically dissipative propylene polymer compositions.

EXAMPLES Examples 1 and 2 and Comparative Example A were mixed in a Haake Rheocord 90 rheometer equipped with a mixing bowl of 200 cubic centimeters (cm 3)., with the mixing speed set at 75 revolutions per minute (rpm). The polymers (propylene block copolymer, polyolefin elastomer and olefin polymer) were mixed dry, then heated and kneaded in the mixing bowl at 185 ° C for about 4 minutes. That time was demineralized when the mixer was removed, when the polymer pellets were added initially, the torque was alio, in the range of 45 newfon mephros (Nm). Once the polymers were sufficiently melted, the torque approached the range of 5 Nm. This was when the components (for example, electrically conductive carbon, filler, stabilizers, etc.) were added. Normally the components were added by spatula about 1 to 1.5 minutes. Following the addition of the components, the lorque was elevated. The resulting propylene polymer composition was allowed to mix for about 10 minutes. When the torque fell significantly, the mixing was completed. The electrically dissipative propylene polymer composition was removed from the Haake mixer and placed in a glass baking dish. The polymer mixture was soaked with liquid ni- logen for approximately 5 minutes. The frozen material was placed directly in a Thomas Wiley Model 4 polymer grinding mill and ground into small hojueals. The flakes were supplied to an Arburg 28-ton injection molding machine for injection molding in tension bar test specimens. The following molding conditions were used: barrel temperature 204 ° C (400 ° F), mold temperaure: 52 ° C (125 ° F) and injection time: 1.5 seconds. The compositions of Examples 1 and 2 and Comparative Example A are shown in Table 1, the amounts are in parts by weight based on the total weight of the propylene polymer composition. In Table 1: "PP-1" is a propylene block copolymer comprising 7.3 per cent rubber EP having an MFR of 65 g / 10 min and a rubber Mz of about 2, 185,000; "PP-2" available as C705-44NAHP Polypropylene from The Dow Chemical Company is a propylene block copolymer having an MFr of 44 g / 10 min. , comprises 16.5 percent EP rubber with a rubber Mz of approximately 637,700; "EDPM" is an ethylene, propylene, diene low diene rubber with a viscosity of Moone 45 (ML 1 + 4 to 125 ° C, ASTM D1646) available as NORDEL R 3745P from DuPony Dow Elastomers; "S / LEP" is a subsitially linear copolymer of ethylene-ocphene with an Ml of 5 g / 10 min (determined at 190 ° C and an applied load of 2.16 kg) and a density of 0.870 grams per cubic centimeter (g / cm3) ) available as ENGAGEM R EG 8200 Poiyolefin Elastomer from DuPont Dow Elastomers; "HDPE" is a commercially available alpha density polyethylene having an Ml = 60 g / 10 min (demineminated at 190 ° C and an applied load of 2.16 kg) available from The Dow Chemical Company as IP-60 HDPE; "Carbon black" is a carbon black available as XC-72 from Caboí; "Talco" is a commercially available talc with an average particle size of 1.8 μm available from Luzannec under the trade name JETFILM R 700C; "B225" is a 1: 1 mixture of 3,5-bis (1,1 -dimethylethyl) -4-hydroxy-2,2-bis [3- [3,5-bis (1,1-dimethyl-ethyl) -4 -hydroxyphenyl] oxo-propoxy] methyl-1,3-propanediyl ester and irris (2,4-di-tertiary-butylphenyl) phosphite available from Ciba Geigy under the trade name IRGANOXMR B225; and "Calcium Stearate" is available from Whitco. The following tests are performed in Examples 1 and 2 and Comparative Example A and the resins of these tests are shown in Table 1: "MFR" is the melt flow rate determined in accordance with ASTM D 1238 at 230 ° C and an applied load of 2.16 kg, the values are reported in grams per 10 minutes (g / 10 min); "Flexural module" is determined in accordance with ASTM D 790, values are reported in pounds per square inch (psi) and megapascals (MPa); "Notched Izod" is determined in accordance with ASTM D 256A at 0 ° C (32 ° F), values are reported in foot pounds per inch (ft-Ib / in) and Joule per meter (J / m); "Density" is measured according to ASTM D 792, the values are reported in grams per cubic centimeter (g / cm3); "Delta Glitter" is determined on injection molded tension rods using a Tobins Associates MTI model speckle tester. The samples are taped onto the rotor and the detector traversed the sample collecting continuous data. The data is recorded in each peak and valley of signal intensity. The speckle data is converted to brightness data using the standards provided with the brightness measurement probe. The brightness delta is then obtained by subtracting the adjacent brightness values and selecting the maximum for each sample; and "Resistivity" is the surface resistivity measured according to the Cabot surface resistivity test method (CMT) EO42, based on the IEC 167 standard using an ITW Ransberg 76634-00 conductivity meter. The surface resistivity (SR) is calculated, taking into account the geometry of the electrodes, with the following equation: SR = R * L / g where: R is the resistance of the material to the load flow (Ohm); L is the length of the electrode (cm); and g is the distance between the electrodes (cm).

Table 1 As can be seen, the electrically dissipative propylene composition of the present invention demonstrated a good balance of improved flow marks (as measured by brightness delta), resistivity and a good flow balance, stiffness and hardness.

Claims (14)

1. CLAIMS 1 . An electrically dissipative propylene polymer composition comprising: (a) a propylene block copolymer comprising (i) a first block comprising a portion of propylene polymer and (ii) a second block comprising a portion of rubber that it comprises a propylene copolymer having an Mz equal to or greater than about 1,000,000; (b) a polyolefin elastomer; (c) an electrically conductive carbon; (d) optionally, an olefinic polymer; and (e) optionally, a filler.
2. 2. The dissipative, electrolytic propylene polymer composition of claim 1, wherein the propylene block copolymer comprises an ethylene and propylene gum.
3. 3. The electrically dissipative propylene polymer composition of claim 1, wherein the polyolefin elastomer is a substantially linear ethylene polymer, a linear ethylene polymer, or combinations thereof, wherein in the substantially linear ethylene polymer and / or linear ethylene polymer are characterized by having: (i) a density equal to or less than about 0.93 g / cm3; (ii) a molecular weight distribution, Mn / Mw, of equal to or less than about 3.0, and (iii) a branching index of composition dissipation equal to or greater than about 30 percent.
4. 4. The electrically dissipative propylene polymer composition of claim 1, wherein the electrically conductive carbon is present in a sufficient amount to provide a surface resistivity of equal to or less than 1012 Ohms.
5. The electrically dissipative propylene polymer melt composition of claim 1, wherein the electrically conductive carbon is carbon black, carbon fibers, graphite, or combinations thereof.
6. 6. The electrical propylene polymer composition as claimed in claim 1, further comprising one or more additives selected from the group consisting of a heat stabilizer, a light stabilizer, an oxidation stabilizer, a colorant, an antioxidant, an aníiestálico, an inlensificador of flow, a liberador of mold, an agenle nucleador, an agenie clarificante and a agent of slide.
7. The electrically dissipative propylene polymer composition of claim 6, wherein the mold releaser is calcium stearate, magnesium stearate or a combination thereof.
8. The electrically dissipative propylene polymer composition of claim 6, wherein the slip agent is erucamide, oleamide, linoleamide, stearamide or combinations thereof.
9. 9. The electrically dissipative propylene polymer composition of claim 1, wherein: (a) the propylene block copolymer is present in an amount of from 30 to 90 parts by weight, (b) the polyolefin elastomer is present in an amount since 5 to 70 parts by weight, (c) the electrically conductive carbon is present in a quantity from 0.1 to 30 parts by weight, (d) the olefinic polymer was present in a quantity from 0 to 15 parts by weight, and (e) ) the filler is present in an amount from 0 to 30 parts by weight, wherein the parts by weight are based on the total weight of the electrically dissipative propylene polymer composition.
10. 10. The electrical propylene polymer composition as claimed in claim 9, wherein: (d) the olefinic polymer is present in an amount of 1 parfe by weight to 15 parts by weight and is selected from the group consisting of HDPE, LLDPE , UHDPE, a polyolefin elastomer and combinations thereof wherein the parts by weight are based on the total weight of the electrically dissipative propylene polymer composition. eleven .
11. The electrical propylene polymer composition as claimed in claim 9, wherein: (e) the filler is present in a quantity from 0.1 weight per part up to 30 weight per cent and is selected from the group consisting of falco, wollaslonite, clay, simple layers of a silicate material in layers of cation exchange, graphite, calcium carbonate, feldspar, nepheline, silica, glass, smoked silica, alumina, magnesium oxide, zinc oxide, barium sulfate, aluminum silica, calcium silicafoxide, lithium dioxide, thianate, glass microspheres and gis, where the parts by weight are based on the total weight of the electrically dissipative propylene polymer composition.
12. 12. A process for extruding or molding the electrically dissipative propylene polymer composition of claim 1 in a manufactured article.
13. 13. The electrically dissipative propylene polymer composition according to claim 1 in the form of a manufactured article.
14. 14. The electrically dissipative propylene polymer composition according to claim 1 in the form of an automotive part selected from the group consisting of a fender, a facia, a tire cover, a door, a panel of instruments, an interior finish, a metal cladding, an oscillating panel or a grill.