MXPA99004014A - Impact-modified thermoplastic polyolefins and articles fabricated therefrom - Google Patents

Abstract

Melt processible thermoplastic compositions and method for making them are described, these compositions comprising a thermoplastic polymer resin matrix selected from the group consisting of thermoplastic polyurethanes, polyvinyl chlorides, styrenics, engineering thermoplastics, and polyolefins, at least 25 percent (by weight based on the total composition) of an elastomeric impact modifier dispersed as discrete particles in the thermoplastic matrix (a);and at least 10 percent (by weight based on the total composition) of at least one homogeneous linear or substantially linear ethylene polymer dispersed as discrete particles in at least the impact modifier (b), the ethylene polymer having a molecular weight distribution less than 3.5 and a density of at least 0.04 g/cm3 higher than the density of the impact modifier component (b), wherein the elastic modulus of the thermoplastic component (a) is at least 200 times greater than the elastic modulus of the impact modifier component (b). These thermoplastic compositions have improved processability. Processes for fabricating articles from them are described. The articles made with these compositions have improved properties such as low temperature impact strength, improved percent elongation to break, greater stiffness, and improved weld line strength, making them useful for applications requiring both strength and flexibility in low temperature environments, such as automotive components and facia.

Description

POLIOLEFINAB THERMOPLABTICAS MODIFIED TO THE IMPACT AND RTICLES MANUFACTURED TO ARTIR OF THE SAME This invention relates to thermoplastic polymers having a better packing modification, to processes for making these polymers, and to products made from these polymers. The thermoplastic olefins (TPO) are generally produced from mixtures of an elastomeric material, such as ethylene / propylene rubber (EPM) or ethylene / propylene diene monomer terpolymer (EPDM), and a more rigid material, such as isotactic polypropylene. Other materials or components may be added in the formulation, depending on the application, including oil, fillers and crosslinking agents. In general, thermoplastic olefins are characterized by a rigidity balance (modulus) and low temperature impact, good chemical resistance and wide usage temperatures. Due to characteristics such as these, thermoplastic olefins are used in many applications, including in automotive faces and wire and cable operations. It is well known that linear polymers of a narrow molecular weight distribution inconveniently have a low sensitivity to tearing d values and low I 10 12, which limit the possibility of extruding these polymers.

Additionally, these polymers have a low melt elasticity, causing problems in melt fabrication, such as in film forming processes or in blow molding processes (e.g., difficulty in holding a bubble in the film process). blown, or sinking in the blow molding process). Finally, these resins also undergo surface melting fracture properties at relatively low extrusion rates, thereby being processed in an unacceptable manner, and causing surface irregularities in the finished product. Although the development of new lower-modulus polymers, such as Union Carbide's Flexomer1111 chicken olefins, or Exxon's ExactMR polymers, has aided the market for thermoplastic olefins, there continues to be a need for more advanced and effective polymers because of the cost to mixed with polypropylene, which improve or maintain a low temperature impact performance, elongation to breakage, modulus, tensile strength, and resistance to the bond line. These and other needs are met by the present invention. In accordance with one aspect of this invention, a melt processable thermoplastic composition is described, characterized in that it comprises: (a) a thermoplastic polymer resin matrix selected from the group consisting of thermoplastic polyurethanes, polyvinyl chlorides, styrenics, engineering thermoplastics and polyolefins, (b) at least 25 percent (by weight, based on the total composition) of an elastomeric impact modifier having a first density, dispersed as separate particles in the thermoplastic matrix (a); (c) at least 10 percent (by weight, based on the total composition) of at least one homogeneous linear or substantially linear ethylene polymer, dispersed as separate particles on at least the impact modifier (b), having the polymer of ethylene a molecular weight distribution less than 3.5, and a second density of at least 0.04 grams / cm3 higher than the density of the impact modifier component (b), wherein the elastic modulus of the thermoplastic component (a) is at least 200 times greater than the elastic modulus of the impact modifier component (b). In accordance with another aspect of this invention, there is disclosed a process for manufacturing a thermoplastic olefin polymer composition, characterized by mixing, at elevated temperature, of: (a) a thermoplastic polymer resin matrix selected from the group consisting of consists in thermoplastic polyurethanes, polyvinyl chlorides, styrenics, engineering thermoplastics and polyolefins, (b) at least 25 percent (by weight, based on the total composition) of an elastomeric impact modifier having a first density; Y (c) at least 10 percent (by weight, based on the total composition) of at least one homogeneous linear substantially linear ethylene polymer, the ethylene polymer having a molecular weight distribution less than 3.5, and a second density at least ~ 0.04 grams / cm3 higher than the density of the impact modifier component (b), wherein the elastic modulus of the thermoplastic component (a) is at least 200 times greater than the elastic modulus of the impact modifier component (b) ). The present invention also includes articles comprising at least one of the melt-processable compositions of this invention, and the configuration of these articles, preferably in a melt processing operation. They will use the following definitions in reading the present application. "Polymer" means a large molecule made up of a number of repeating units called monomers. "Homopolymer" means a polymer made from a kind of monomer. "Interpolymer" means a polymer made from two or more kinds of monomers, and includes "copolymers" which are made of two kinds of monomers, "terpolymers" which are made of three kinds of monomers, and polymers of higher order. The thermoplastic polymer used in the practice of this invention is any polymer that can be remelted after it has previously been melted, processed and extruded into a shaped article. It may be substantially crystalline, for example, polypropylene or high density polyethylene, or substantially non-crystalline, such as the elastomeric polymers described above. The thermoplastic polymer is preferably substantially crystalline. The term "substantially crystalline" means that the polymer has at least 25 percent crystallinity. More preferably, the thermoplastic polymer has at least 50 percent crystallinity, and still more preferably the thermoplastic polymer has at least 75 percent crystallinity. Thermoplastic polymers that are beneficially modified at impact may be thermoplastic polyurethanes (such as Pellethane ™ polyurethane elastoplastic polymers, or Isoplast ™ polyurethane engineering thermoplastic resins, made by The Dow Chemical Company), polyvinylchlorides (PVC), styrenics, polyolefins (including, for example, ethylene-carbon monoxide copolymers (ECO), linear alternating ECO copolymers, such as those disclosed in U.S. Patent Nos. 5,554,777 and 5,565,547, and ethylene polymers / propylene-carbon monoxide (EPCO)), different engineering thermoplastics (such as polycarbonate, thermoplastic polyester, polyamides (such as nylon), polyacetals polysulf'ones). In general, the most commonly used polyolefin polymers are polyethylene (e.g., high density polyethylene, such as that produced by the pulp polymerization process, heterogeneously branched linear low density polyethylene (LLDPE), such as copolymers. of ethylene with at least one α-olefin of 3 to 20 carbon atoms, and recycled polyethylene (ie, high density polyethylene recycled after the consumer, recovered from waste bottles)) d polypropylene. In general, at least one polypropylene is most frequently useful in the compositions disclosed herein. Polypropylene is generally in the isotactic form of the polypropylene homopolymer, although other forms of polypropylene (eg, syndiotactic or atactic) can also be used. Polypropylene impact copolymers (ie, those where a secondary copolymerization step is employed which reacts ethylene with propylene), and random copolymers (also modified in reactor, and typically containing 1.5 to 7 percent ethylene copolymerized with propylene), however, can also be used in the thermoplastic olefin formulations disclosed in I presented. A complete discussion of different polypropylene polymers is contained in Modern Plastics Encvclopedia / 89. edition of mid-October 1988, Volume 65, Number 11, pages 86-92. The molecular weight of the polypropylene for use in the present invention is conveniently indicated using a melt flow measurement according to ASTM D-1238, Condition 230 ° C / 2.16 kg (formerly known as "Condition (L)", and also known As I2, the velocity of the melt flow is inversely proportional to the molecular weight of the polymer, therefore, the higher the molecular weight, the lower the melt flow rate, although the relationship is not linear. The melting point for the polypropylene useful herein is generally from 0.1 grams / 10 minutes (g / 10 min) to 100 grams / 10 minutes.For modification to the impact of automotive faces, the melt flow rate for polypropylene is generally 0.1 grams / 10 minutes at 35 grams / 10 minutes, preferably 0.5 grams / 10 minutes at 25 grams / 10 minutes, and especially from 1 gram / 10 minutes at 20 grams / minutes. thin walls (such as cups and lids made, for example, by using an injection molding process), the melt flow rate for polypropylene is generally 20 grams / 10 minutes to 100 grams / 10 minutes. High molecular weight thermoplastic polymers can be used to produce stronger compositions. The number average molecular weight (Mn) is from 7,000 to 1,000,000 or more, preferably from 10,000 to 500,000. The tensile modulus of the thermoplastic component is at least 200, preferably at least 1,000 times greater than the tensile modulus of the elastomeric impact modifier. The tensile modulus is measured in -present according to ASTM-D-638. "Elastomeric impact modifier" means a polymer that can be stretched with the application of tension to at least twice its length, and after releasing the tension, returns to its approximate original dimensions and shape. The elastic recovery of an elastomeric impact modifier is generally at least 40 percent, preferably at least 60-percent, and more preferably at least 80 percent, when measured in accordance with ASTM D- 412 This component is also referred to hereinafter as the "impact modifier" or the "elastomeric polymer". The elastomeric polymers suitable for used in this invention include ethylene / α-olefin interpolymers; isoprene rubbers, such as polyisoprene (including natural rubber), and isobutylene / isoprene rubber (butyl rubber); polychloroprene; butadiene rubbers, such as polybutadiene, styrene / butadiene rubber, and acrylonitrile / butadiene rubber; and block copolymer rubbers, such as styrene / isoprene / styrene triblock, styrene / butadiene / styrene triblock, and hydrogenated styrene / butadiene / styrene block copolymer, eg, styrene / ethylene / butene block copolymers / styrene. The term "α-olefin" means a hydrocarbon molecule, or a substituted hydrocarbon molecule (i.e., a hydrocarbon molecule comprising one or more atoms other than hydrogen and carbon, eg, halogen, oxygen and nitrogen, the hydrocarbon molecule: (i) only an ethylenic unsaturation, this unsaturation being located between the first and second carbon atoms, and (ii) at least 3 carbon atoms, preferably from 3 to 20 carbon atoms, in some cases preferably from 4 to 10 carbon atoms, and in other cases preferably from 4 to 8 carbon atoms Examples of the preferred α-olefins from which the elastomers used in this invention are prepared, include propylene, 1-butene , 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, and mixtures of two or more of these monomers.

Among the elastomeric polymers useful in the practice of this invention, ethylene / α-olefin interpolymers are preferred, particularly those having a density less than 0.870 grams / cm 3, such as those having a density on the scale of 0.855 to 0.870. grams / cm3. Also preferred are elastomeric polymers having a melt index (I2) of less than 5 grams / 10 minutes, more preferably less than 3 grams / 10 minutes. Preferred ethylene interpolymers include ethylene / α-olefin copolymers; ethylene / α-olefin / diene terpolymers; and interpolymers of ethylene and one or more other monomers which can be copolymerized with ethylene, such as ethylenically unsaturated carboxylic acids (both monofunctional and bifunctional), and their corresponding esters and anhydrides, for example, acrylic acid, methacrylic acid, vinyl ester (eg example, vinyl acetate), and maleic anhydride, and aromatic monomers containing vinyl group, such as styrene. The preferred α-olefins are derived from 1-octene, 1-hexene, 1-pentene, 4-methyl-1-pentene, 1-butene and propylene. These polymers include: (i) heterogeneous linear low density ethylene interpolymers (heterogeneous LLDPE) made using Ziegler-Natta catalysts in a pulp, gas phase, solution, or high pressure process, as described in the Patent of the States United States of America Number 4,076,698; "(ii) homogeneous linear ethylene polymers, such as (a) those described in U.S. Patent No. 3,645,992; (b) those made using so-called single-site catalysts in a batch reactor, having relatively high olefin concentrations, as described, for example, in U.S. Patent Nos. 5,026,798 and 5,055,438, and (iii) homogeneous substantially linear olefin polymers having long chain branching, as described, for example. , US Patents Nos. 5,272,236, 5,278,272 and 5,665,800 These polymers are commercially available Representative of commercially available homogeneous linear ethylene polymers are TAFMERMR made by Mitsui Petrochemical Industries, Ltd. and EXACTMR made by Exxon Chemical Co. The substantially linear ethylene polymers are discussed more fully m Further on, the ethylene / α-olefin / diene terpolymers can be used as the elastomeric impact modifier. Suitable a-olefins include the a-olefins described above as suitable for making the ethylene / α-olefin copolymers. The dienes suitable as monomers for the preparation of these terpolymers are conjugated or non-conjugated. Typically they are non-conjugated dienes that have 6 to 15 carbon atoms. Representative examples of suitable non-conjugated dienes that can be used to prepare the terpolymer include: a) Acyl straight chain acyls, such as 1,4-hexadiene, 1,5-heptadiene, piperylene (although the piperylene is conjugated), and 1, 6-octadiene; b) branched chain acyclic dienes, such as 5-methyl-l, 4-hexadiene, 3,7-dimethyl-l, 6-octadiene, and 3,7-dimethyl-l, 7-octadiene; c) single ring alicyclic dienes, such as 4-vinylcyclohexene, l-allyl-4-isopropylidenecyclohexane, 3-allylcyclopentene, 4-allylcyclohexene and l-isopropenyl-4-butenyl-cyclohexane; d) ring and aliphatic ring-bridged alkenes of multiple rings, such as dicyclopentadiene; alkenyl-, alkylidene-, cycloalkenyl- and cycloalkylidene norbornenes, such as 5-methylene-2-norbornene, 5-methylene-6-methyl-2-norbornene, 5-methylene-6,6-dimethyl-2-norbornene, -propeni1-2-norbornene, 5- (3-cyclopentenyl) -2-norbornene, 5-ethylidene-2-norbornene, and 5-cyclohexylidene-2-norbornene. Preferred dienes are selected from the group consisting of 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 7-methyl-1, 6-octadiene, piperylene; and 4-vinylcyclohexene. The preferred terpolymers for the practice of invention are terpolymers of ethylene, propylene and a non-conjugated diene (EPDM). Exemplary terpolymers are the NORDELK and NORDELMR-1P polymers, which are available from DuPont Dow Elastomers L.L.C. The total content of diene monomer in the terpolymer may suitably be from about 0.1 to 15 weight percent, preferably from 0.5 to 12 weight percent, and more preferably from 1.0 to 6.0 weight percent. Both the ethylene copolymers and the ethylene terpolymers comprise from 20 to 90 percent by weight, preferably from 30 to 85 percent by weight of ethylene, the rest comprising other constituents. Ethylene copolymers and terpolymers preferably have a weight average molecular weight (M ^,) of at least 10,000, and more preferably at least 15,000, and may have an M "of up to 1,000,000 or higher, preferably up to 500,000. .

The elastomeric polymer preferably has a Mooney viscosity of at least 20. The Mooney viscosity is defined herein at 100 ° C in accordance with ASTM D-1646. The elastomeric polymer is preferably substantially amorphous. The term "substantially amorphous" means that the polymer has a degree of crystallinity of less than 25 percent. The most elastomeric polymer preferably it has a crystallinity of less than 15 percent. The elastomeric polymer can be the product of a single polymerization reaction, d can be a polymer mixture resulting from the physical mixture of polymers obtained from different polymerization reactions and / 6 resulting from the use of a mixed polymerization catalyst. "Functionalized elastomeric polymer" means an elastomeric polymer or an elastomeric polymer blend comprising at least one reactive substituent that reacts with the reactive substituents of the crosslinking agent to at least partially cure the elastomer. Preferred reactive elastomer substituents are selected from the group consisting of carboxylic acid, carboxylic anhydride, carboxylic acid salt, carbonyl halide, hydroxy, epoxy and isocyanate.

The preferred ethylene / α-olefin interpolymers are copolymers of ethylene / 1-dodecene, ethylene / 1-decene, ethylene / 1-octene, ethylene / 1-hexene, ethylene / 4-methyl-1-pentene, ethylene / 1 -pentene, ethylene / 1-butene and ethylene / propylene, -produced by a single site catalyst of limited geometry. A process for making these copolymers is described in U.S. Patent Nos. 5,272,236, 5,278,272 and 5,665,800. These Ethylene interpolymers are preferably substantially linear olefin polymers having long chain branching. The substantially linear olefin polymers can be made by gas phase, solution phase, high pressure or paste polymerization. These polymers are preferably made by solution polymerization. The substantially linear ethylene polymers (SLEP) are commercially available from The Dow Chemical Co., under the registered trademark AFFINITY, and from DuPont Dow Elastomers L.L.C., under the registered trademark ENGAGE.

"Substantially linear polymer" means that the base structure of the polymer contains long chain branching, and is replaced by an average of up to three long chain branches / 1,000 carbon atoms. Preferred substantially linear polymers are substituted with 0.01 to 3 long chain branches / 1,000 carbon atoms, more preferably 0.01 to 1 long chain branches / 1,000 carbon atoms, and especially 0.3 to 1 long chain branches / 1,000 carbon atoms. These substantially linear polymers are characterized by: a) a melting point ratio, Iio / ^? ' - 5.63, b) a molecular weight distribution, M ^, / Mn, defined by the equation: Mw / Mn <; I10 I2"4.63; and c) a critical tear stress to the setting of the coarse melt fracture of more than about 4 x lo6 dynes / cm2." Long chain branching "means a pendant carbon chain having a chain length of at least 6 carbon atoms, above whose length it can not be distinguished using 13C nuclear magnetic resonance spectroscopy.The long chain branching can be as long as about the length of the base structure of the polymer to which it is attached. of the long chain branching can be determined in ethylene homopolymers, by using 13C nuclear magnetic resonance (NMR) spectroscopy, and quantified using Randall's method (Rev. Macromol. Chem. Phys., C29 (2 and 3), pages 285-297.) However, as a practical matter, current 13C nuclear magnetic resonance spectroscopy can not determine the length of a branch. long chain of more than 6 carbon atoms. For the ethylene / α-olefin copolymers, the long chain branching is longer than the short chain branching resulting from the incorporation of the α-olefins into the polymer backbone. For example, a substantially linear ethylene / 1-octene copolymer has a short chain branching length of six (6) carbon atoms, but a long chain branching length of at least seven (7) carbon atoms. Typically, SLEPs are copolymers of ethylene and an α-olefin of 3 to 20 carbon atoms (eg, propylene, l-butene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and styrene), preferably 3 to 10 carbon atoms, and more preferably these polymers are a copolymer of ethylene and 1-octene. The density of these substantially linear ethylene polymers is preferably in the range of 0.85 to 0.9, more preferably 0.85 to 0.88 grams per cubic centimeter (g / cm3), as determined by ASTM D-792. The proportion of the melt flow, measured as? Io ?? as defined in ASTM D-1238, Conditions 190C / 10kg and 190C / 2.16kg (formerly known as "Conditions (N) and (E)", respectively, and also known as I10 and I2, respectively), is greater than , or equal to, 5.63, and preferably is in the range of 6.5 to 15, more preferably in the scale of 7 to 10. The molecular weight distribution (Mw / Mn), measured by gel permeation chromatography (GPC) , preferably it is in the scale of 1.5 to 2.5. For substantially linear ethylene polymers, the ratio I10 / I2 indicates the degree of long chain branching, ie, the larger the proportion of long chain branching will be in the polymer. A unique feature of ethylene polymers eustantially linear, homogeneously branched, is the highly unexpected flow property, wherein the I10 / I2 value of the polymer is essentially independent of the polydispersity index (ie, Mw / Mn) of the polymer. This contrasts with linear heterogeneously branched heterogeneous linear linear branched polyethylene resins, which have redox properties such as to increase the I / I value. The polydispersity index should also be increased. The substantially linear olefin polymers have a critical tear index to the setting of the surface melt fracture of at least 50 percent greater than the tear rate critical to the setting of the surface melt fracture of a linear olefin polymer having approximately the same I2, y / j, and density. "Approximately the same" means that each value is within 10 percent of the comparative value. The preferred melt index, measured as I (ASTM D-1238, condition 190 / 2.16 (formerly condition E)), is 0.5 grams / 10 minutes at 200 grams / 10 minutes, more preferably from 1 to 20 grams / 10 minutes . Typically, the preferred SLEPs used in the practice of this invention are homogeneously branched, and do not have a measurable high density fraction, as measured by Fractionation. by Elution with Temperature Elevation described in U.S. Patent No. 5,089,321. In other words, these polymers do not contain a polymer fraction having a degree of branching less than or equal to two methyl groups / 1,000 carbon atoms. Preferred SLEPs also have a single melting peak in differential scanning calorimetry (DSC) between -30 ° C and 150 ° C, using a second heat at a scanning speed of 10 ° C / minute. The third component of the thermoplastic olefin polymer composition according to this invention is a homogeneous linear or substantially linear ethylene polymer having a molecular weight distribution of less than 3.5, preferably in the range of 1.8 to 2.5. The molecular weight distribution is the weight average molecular weight of the polymer, divided by the number average molecular weight of the polymer (measured by gel permeation chromatography (GPC) .The density of this component is from when less than 0.04, preferably at least 0.05, and more preferably at least 0.06 grams / cm3 higher than the density of the elastomeric impact modifier component, determined in accordance with ASTM D-792 In a preferred embodiment of this invention, the density of this component is on the scale of 0.90 to 0.95 grams / cm3.

The homogeneous linear ethylene polymer may be selected from (a) those described in US Pat. No. 3,645,992, and (b) those made using single-site catalysts in a batch reactor, having concentrations of relatively high olefin, as described, for example, in U.S. Patent Nos. 5,026,798 and 5,055,438. These polymers are commercially available. Representative examples are TAFMERMR made by Mitsui Petrochemical Industries, Ltd., and EXACT ™ EXCEEDMR and polymers made by Exxon Chemical Co. The homogeneous substantially linear ethylene polymer (SLEP) can be selected from those described above as elastomeric impact modifiers, with the condition that they must be selected to comply with the molecular weight and density distribution scales required for this component. Many different auxiliaries or additives are known to modify the costs and / or properties of the polymer. These can optionally be used in the present invention. Non-limiting examples include fillers, such as Ti02 or carbon black; extensor oils, including aliphatic or naphthenic or polyester oils; processing aids, such as stearic acid; phenolic, thioester and phosphite antioxidants, such as "Irganox 1010MR (commercially available at Ciba-Geigy) or Weston 619MR (commercially available at General Electric); acid neutralizers, such as MgO, calcium stearate, dihydro-talcite, tin mercaptans, and sodium tetrapyrrophosphate; and pigments. If the composition contains a crosslinking agent for vulcanization, auxiliaries may be added before d after dynamic vulcanization. Depending on the nature of the auxiliary and its interaction with the selected crosslinking chemistry, the auxiliary may preferably be added after the dynamic vulcanization has occurred. Although fillers and blending ingredients are not essential components of the thermoplastic composition of this invention, preferably, especially from a cost standpoint, different amounts of conventional fillers and / or blending ingredients normally used with elastomers are mixed with the compositions of this invention. Examples of these ingredients include extender oils, such as aromatic oils, paraffinic oils or naphthenic oils; inorganic fillers, such as different carbon blacks, clays, silica, alumina, calcium carbonate; pigments, such as titanium dioxide; antioxidants; antidegradants; processing aids, such as lubricants and waxes; and plasticizers, such as dialkyl phthalates, trialkyl meltates and adipates of dialkyl. An example of a preferred filler is talc, such as VANTALCMR supplied by R.T. Vanderbilt and manufactured by Luzinac. Preferably, the processing oils and / or the plasticizers and inorganic fillers are added to the thermoplastic composition to improve their processing characteristics, and the particular amounts used depend, at least in part, on the amounts of other ingredients in the composition, and of the desired properties of the composition. The thermoplastic compositions according to this invention comprise at least 25, preferably up to 35 weight percent of the elastomeric impact modifier component, and at least 10, preferably up to 20 weight percent of the polymeric ethylene component . The proportion by weight of the component of the impact modifier to the ethylene polymer component is preferably from at least 2 to 1, and more preferably up to 4 to 1. In general, amounts of 5 to 50 parts by weight may be used. of filler, based on 100 parts by weight of total polymers, and 10 to 100 parts by weight of blend ingredients, such as processing oils and plasticizers, based on 100 parts by weight of the total weight of the polymers. In a preferred embodiment, the thermoplastic composition contains 10 to 20 weight percent filler, and optionally 20 to 40 weight percent Mixing ingredients. The compositions according to this invention may also contain minor amounts (ie, less than 50 weight percent, preferably less than 10 weight percent) of one or more other polymers than the thermoplastic polymer resin matrix described above, the elastomeric impact modifier, and the homogeneous linear or substantially linear ethylene polymer (the "polymeric components"). Each of the polymer components can independently comprise mixtures. The remainder of the thermoplastic composition of this invention is the thermoplastic resin component. The thermoplastic resin component preferably comprises at least 30, more preferably at least 40 percent by weight of the composition. The formulations are mixed by any convenient method, including dry blending of the individual components, and subsequently melt blending, either directly in the extruder used to make the finished article (such as an automotive part), or by melt premix in a separate extruder (for example, a Banbury mixer). These thermoplastic olefins can be processed using conventional plastic processing equipment. There are many types of molding operations that can be used to form articles or fabricated parts useful from the thermoplastic olefin formulations disclosed herein, including different injection molding processes (such as that described in Modern Plastics EncycIopedia / 89, October edition of 1988, Volume 65, Number 1 1, pages 264-268, "Introduction to Injection Molding", and on pages 270-271, "Injection Moldi ng Termoplastics"), thermoforming blow molding processes (such as that described in Moderp Plastics Encyclopedia / 89, mid-October 1988 edition, Vol. 65, No. 1 1, pages 217-218, "Extrusion-Blow Molding"), and profile extrusion. Some of the items manufactured include automotive bumpers, faces, wheel covers and grills, as well as other household and personal items, including, for example, refrigerator and freezer components, and freezer containers. The freezer containers made with the thermoplastic compositions disclosed herein, have a unique combination of desired attributes, including good low temperature (to prevent container cracking if dropped), and good clarity for the container. see the food Good clarity is achieved through selection as the elastomeric impact modifier and as the third component of ethylene polymer, the ethylene polymer linear or substantially linear / α-olefin having a refractive index within 0.005 refractive index units from the refractive index of the thermoplastic to be modified, especially within 0.002 refractive index units, typically measured at 589 nandometers In general, polypropylene has a refractive index of about 1470 to about 1515, for example, the clarified polypropylene homopolymer has a refractive index of about 1.5065, and the clarified polypropylene random copolymer has a refractive index of about 1.5044 a 589 nanometers The thermoplastic compositions of this invention have important advantages in being able to achieve certain properties, particularly certain properties in combination. For example, it has been difficult to achieve a high percentage of elongation upon breakage of the thermoplastic compositions, while at the same time achieving a sufficient impact resistance, especially impact resistance at low temperature. When the density of the impact modifier is increased to improve the impact resistance, the inventors observed that it suffered the percentage of elongation at break, and vice versa. The present invention overcomes these drawbacks.

A preferred embodiment has at least 50 percent elongation to breakdown, and a notched Izod impact resistance at -30 ° C of at least 20 foot-pounds / inch2 (0.43 kilogram-meters / centimeter2). A more preferred embodiment has a breaking elongation of at least 70 percent for the same or higher Izod impact strength. Another preferred embodiment has a Notch Izod Impact Strength at -30 ° C of at least 26 foot-pounds / inch2 (0.56 kilogram-meters / centimeter2) for the same or higher percentage of elongation at break. In a preferred embodiment, these values are measured based on a thermoplastic composition containing 15 weight percent VANTALC 6H filler. The percentage of elongation at break is defined herein as the value measured according to ASTM D-638 at a deformation rate of 20 inches / minute (50 centimeters / minute), and at room temperature, using a sample molded by injection of the thermoplastic composition. The tensile test is carried out on an INSTRON machine. The test is under displacement control. The method of injection molding under the conditions are described below. The Izod notch impact strength at -30 ° C is defined herein as the value measured according to ASTM D-256 at -30 ° C, using a single-gate gate rod sample end molded by injection of the thermoplastic composition. The Izod notch impact test on single-ended gate bars (0.5 x 5.0 x 0.125 inches (1.3 x 13 x 0.3 centimeters)) uses a ground notch, and conforms to ASTM D-256. The injected bars are marked with notches in the center of the bar by means of a notch former, with a notch depth of 0.400 + 0.002 inches (1.02 + 0.005 centimeters) The Izod impact test uses a conventional unit equipped with a chamber cold temperature, and a 2 foot-pound (0.28 kilogram-meter) free-fall hammer The procedure and conditions of injection molding are described below The compositions of the present invention preferably have tensile modulus values within at least 10 percent, preferably within 5 percent, of the tensile module of the thermoplastic resin component Preferably, the compositions of the invention have tensile modulus values of at least about 1,200 MPa. it is measured in accordance with ASTM D-638. Another advantage of this invention is the ability to achieve high bond strength, especially in combination with the previous properties. In a preferred embodiment, the strength of the bond line is when minus 1,700 (11.8), more preferably at least 1,800 (12.4) pounds per square inch (MPa). The bond line strength values are measured according to ASTM-638 using a sample of the injection molded thermoplastic composition in the form of a double end gate bar, rather than a single end gate bar . The procedure and conditions of injection molding are described below. The method and conditions of injection molding to test these and other properties of the thermoplastic compositions are as follows. The thermoplastic compositions are prepared for injection molding using a Farrell Banbury BR type mixer, which has a capacity of 1.575 cubic centimeters. A total of 1,100 grams is used for each formulation. The entire amount of the formulation is added to a warm Banbury mixer, with the rotor speed at 200 rpm, until the material begins to flow (approximately 1 minute), at which time, subsequently the rotor speed becomes slower. 175 (or any rotor speed required to maintain a melting temperature below 180 ° C), and continue mixing for 3 minutes through the flow. Then the mixed formulation is discharged from the mixer, and passed through a cold rolling mill to make a sheet. The sheet is milled in flakes, and Subsequently, the flakes are injection molded to form test samples, using an "ASTM family mold". An Arburg injection molding unit of 70 tons (308 x lo3 kilograms) is used with the following basic positions: a temperature profile of 190 ° C / 210 ° C / 210 ° C / 210 ° C, a mold temperature of 74 ° F (23 ° C), an injection pressure of 300 psi (2.07 MPa) for 1.8 seconds, a holding pressure of 250 psi (1.72 MPa) for 15 seconds, and a cooling time of 30 seconds. The conditions of injection molding are mentioned in the following Table 1. Impact test, strength, tensile modulus, and bond line strength are then injection molded. All tests are performed after waiting at least 24 hours after the injection to allow the samples to reach equilibrium.

Table 1 Invention Molding Conditions for a 70 Ton Machine The thermoplastic compositions of this invention have a morphology that can be described as a multi-phase composition, having at least three phases, wherein particles separated from the homogeneous linear or substantially linear ethylene polymer component are dispersed, at least in the modifier component of the invention. Elastomeric impact, which in turn is dispersed inside the thermoplastic polymer matrix as separate particles. In a preferred embodiment, a larger amount is dispersed (i.e., more than 50 weight percent, preferably when minus 90 weight percent) of the polymer component of ethylene as separate particles within the phase of the elastomeric impact modifier. The number average particle size of the elastomeric impact modifier particles, including the ethylene polymer particles within, is preferably less than, or equal to, 2 microns, more preferably less than, or equal to 1 micron. The polydispersity index of the particle size of the elastomeric impact modifier is preferably less than 3, and more preferably less than _. The total volume occupied by the polymer particles of ethylene within the particles of the elastomeric impact modifier is preferably less than 90 percent of the total volume of the particles of the elastomeric impact modifier, including the ethylene polymer particles inside.

The following examples are presented as illustrative of the present invention. The present invention should not be considered in any way limited by these examples. Unless otherwise specified, all parts, percentages and proportions are by weight.

EXAMPLES Thermoplastic compositions are prepared for the test, using the procedure and conditions described above for the test samples of injection molding, using an "ASTM family mold". Each formulation of the thermoplastic composition contains HIMONT PRO-FAXMR PD-701 (an isotactic polypropylene homopolymer having a melting point index (I2) of 35 grams / 10 minutes, a density of 0.9 grams / cm3, and a resistance to the performance traction of 4,500 psi (31 MPa) available from Himont USA, Inc.), N0RDELMR 2522 (an EPDM having a Mooney viscosity in accordance with ASTM-D1646 at 100 ° C of 46, when combined with 50 weight percent of black 150 OIL (available from Sun Oil Co.), available from DuPont Company), and talcum (VANTALCMR (6H)). To each of these formulations was added a third phase specified in Table 2 below. The formulations of some comparative examples and controls are also listed in Table 2. The results of the Izod impact test of the examples are listed in Table 3, the results of the tensile test are shown in Table 4, and the Resistances of the binding line are shown in Table 5. Each result shown below is the average of the values obtained when testing five samples.

Table 2 The Formulation of the E-examples Table 3 Izod Impact Resistance at -30 ° C Table 4 Traction Properties at the Ambient Temperature Table 5 Resistance of the Union Line

Claims (14)

1. A thermoplastic olefin polymer composition characterized in that it comprises: (a) a thermoplastic polymer resin matrix selected from the group consisting of thermoplastic polyurethanes, polyvinyl chlorides, styrenics, engineering thermoplastics and polyolefins, (b) at least 25 percent (by weight, based on the total composition) of an elastomeric impact modifier dispersed as separate particles in the thermoplastic matrix (a); (c) at least 10 percent (by weight, based on the total composition) of at least one homogeneous linear or substantially linear ethylene polymer, dispersed as separate particles on at least the impact modifier (b), having the polymer of ethylene a molecular weight distribution less than 3.5, and a density of at least 0.04 grams / cm3 higher than the density of the impact modifier component (b), wherein the elastic modulus of the thermoplastic component (a) is at least 200 times greater than the elastic modulus of the impact modifier component (b).

2. The composition of claim 1, wherein the impact modifier (b) is an ethylene / α-olefin interpolymer having a density less than 0.87 grams / cm 3.

The composition of claim 1 or claim 2, wherein the impact modifier (b) is an ethylene / α-olefin / diene terpolymer, and the thermoplastic (a) is isotactic polypropylene.

The composition of any one of the preceding claims, which has at least one of a break elongation of at least 50 percent (tested in accordance with ASTM D-638, at a strain rate of 20 inches / minute ( 50 centimeter / minute) and at room temperature), and an Izod notch impact strength tested at -30 ° C in accordance with ASTM D-256 of at least 20 foot-pounds / inch2 (0.43 kilograms-meters / centimeter2); or a tensile modulus within 10 percent of that of the thermoplastic matrix of the component ^ (a), determined in accordance with ASTM D-638, at a tension rate of 20 inches / minute (50 centimeters / minute), the room temperature; or wherein a double end gate rod injection molded from this composition has a bond line strength, tested in accordance with ASTM D-638, of at least 1,700 psi (11.7 MPa); or wherein the tensile modulus of the thermoplastic component (a) is at least 1,000 times larger than the tensile modulus of the impact modifier component (b).

5. The composition of any of the preceding claims, which has a notched Izod impact strength tested at -30 ° C in accordance with ASTM D-256 of at least 26 ft.-lbs./inch.2 (0.57 kilogram-meters / cm2) ured when the composition does not contain filler.

6. The composition of any one of claims 1 to 6, which contains from 10 to 20 percent (by weight, based on the total composition) of at least one filler.

The composition of any of the preceding claims, wherein the ethylene polymer (c) is at least one substantially linear ethylene / α-olene polymer having: (a) a melt flow ratio, I? I2 > 5.63; _ (b) a molecular weight distribution, Mw / Mn, defined by the equation: (c) a critical tear rate at the establishment of the surface melt fracture of at least 50 percent greater than the critical tear index at establishment of the surface melt fracture of a linear ethylene / α-olefin polymer having approximately the same melt index (I2) and Mw / Mn.

8. The composition of claim 1, wherein the weight ratio of the impact modifier component (b) to the polymer component of ethylene (c) is at least 2: 1.

9. A thermoplastic olefin polymeric composition, which comprises: (a) an isotactic polypropylene homopolymer; (b) from 25 to 35 percent (by weight, based on the total composition) of an elastomeric impact modifier which is an interpolymer of ethylene and at least one α-olefin, which has a density on the scale of 0.855 to 0.870 grams / cm3, and at least one of a melt index (I2) of less than 5 degrees / 10 minutes, or a Mooney Viscosity measured in accordance with ASTM D-1646 at 100 ° C of at least 20, which is dispersed as separate particles in the isotactic polypropylene homopolymer (a); and (c) from 10 to 20 percent (by weight, based on the total composition) of at least one homogeneous linear or substantially linear ethylene polymer dispersed as separate particles on at least the impact modifier (b), having the polymer of ethylene a molecular weight distribution of 1.8 to 2.5, and a density of at least 0.04 grams / cm3 higher than the density of the impact modifier (b), and which is in the wherein the tensile modulus of the isotactic polypropylene homopolymer (a) is at least 200 times larger than the tensile modulus of the impact modifier component (b). The composition of claim 9, further characterized in that it has a tensile modulus of at least 1,200 MPa, determined in accordance with ASTM D-638, at a tension rate of 20 inches / minute (50 centimeters / minute) and at room temperature. 11. A process for manufacturing a thermoplastic olefin polymeric composition, which comprises mixing, at an elevated temperature: (a) a matrix of thermoplastic polymer resin selected from the group consisting of thermoplastic polyurethanes, polyvinyl chlorides, styrenics, thermoplastics of engineering, and polyolefins, (b) at least 25 percent (by weight, based on the total composition) of an elastomeric impact modifier; (c) at least 10 percent (by weight, based on the total composition) of at least one homogeneous linear or substantially linear ethylene polymer, the ethylene polymer having a molecular weight distribution less than 3.5, and a density of at least 0.04 grams / cm3 higher than the density of the impact modifier component (b), where the tensile modulus of the thermoplastic component (a) is at least 200 times greater than the tensile modulus of the impact modifier component (b). A process for manufacturing an article comprising an impact modified polyolefin, which comprises molding, thermoforming, or spreading a composition of any of claims 1 to 10. 13. A manufactured article comprising the composition of any one of the claims 1 to

10. The manufactured article of claim 21, selected from the group consisting of injection molded articles, blow molded, thermoformed, and profiled extruded. SUMMARY Melt-processable thermoplastic compositions and a method for making them are described, these compositions comprising a thermoplastic polymeric resin matrix selected from the group consisting of thermoplastic polyurethanes, polyvinyl chlorides, styrenics, engineered thermoplastics, and polyolefins, at least 25% by weight. percent (by weight, based on the total composition) of an elastomeric impact modifier dispersed as separate particles in the thermoplastic matrix (a); and at least 10 percent (by weight, based on the total composition) of at least one homogeneous linear or substantially linear ethylene polymer dispersed as separate particles on at least the impact modifier (b), the ethylene polymer having a molecular weight distribution less than 3.5, and a density of at least 0.04 grams / cm3 higher than the density of the impact modifier component (b), wherein the elastic modulus of the thermoplastic component (a) is at least 200 times greater than the elastic modulus of the impact modifier component (b). These thermoplastic compositions have a better processability. Processes for manufacturing articles are described from the same. The articles made with these compositions have better properties, such as impact resistance at low temperature, better percentage of elongation at break, greater rigidity, and better resistance of the bond line, making them useful for applications that require both strength and flexibility in media low temperature environments, such as components and automotive faces. * * * * *