POLYPROPYLENE COMPOSITIONS WITH IMPROVED CLARITY

Abstract

A polymeric composition is disclosed. The composition can include (a) at least 95 wt. % of a polypropylene, (b) a clarifying agent, and (c) a nucleating agent, wherein the presence of the clarifying agent and nucleating agent in the polymeric composition decreases the haze value, as determined by ASTM D1003 at a thickness of 40-80 mil, of the polymeric composition when compared with the haze value of the polymeric composition having the clarifying agent but not the nucleating agent.

Claims

1. A polymeric composition comprising: (a) at least 95 wt. % of a polypropylene; (b) a clarifying agent; and (c) a nucleating agent, wherein the presence of the clarifying agent and nucleating agent in the polymeric composition decreases the haze value, as determined by ASTM D1003 at a thickness of 40-80 mil, of the polymeric composition when compared with the haze value of the polymeric composition having the clarifying agent but not the nucleating agent.

2. The polymeric composition of claim 1, wherein the composition comprises 0.01 to 0.5 wt. % of the clarifying agent, and 0.01 to 0.5 wt. % of the nucleating agent.

3. The polymeric composition of claim 2, wherein the composition comprises 0.1 to 0.3 wt. % of the clarifying agent, and 0.05 to 0.2 wt. % of the nucleating agent, or wherein the composition comprises the clarifying agent and the nucleating agent at a wt. % ratio of 0.01/5 to 0.5/0.01.

4. The polymeric composition of claim 3, wherein the clarifying agent is a nonitol-based clarifying agent or a trisamide-based clarifying agent and the nucleating agent is a phosphate ester based nucleating agent.

5. The polymeric composition of claim 4, wherein the nonitol-based clarifying agent is 1,2,3-trideoxy-4,5:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol, or the trisamide-based clarifying agent is a 1,3,5-benzenetrisamide amide derivative, preferably 1,3,5-tris(2,2-dimethyl propanamido)benzene.

6. The polymeric composition of claim 4, wherein the phosphate ester-based nucleating agent is 2,2-methylenebis (4,6,-di-tertbutylphenyl) phosphate.

7. The polymeric composition of claim 4, wherein the clarifying agent is 1,2,3-trideoxy-4,5:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol, and the nucleating agent is 2,2-methylenebis (4,6,-di-tertbutylphenyl) phosphate.

8. The polymeric composition of claim 1, wherein the presence of the clarifying agent and nucleating agent in the polymeric composition increases the tensile modulus, as determined by ASTM D638, of the polymeric composition when compared with the tensile modulus of the polymeric composition having the clarifying agent but not the nucleating agent.

9. The polymeric composition of claim 1, wherein the haze value is decreased by at least 1%, preferably by at least 2%, more preferably by 1% to 5%, or even more preferably by 2% to 5%.

10. The polymeric composition of claim 1, wherein the haze value of the polymeric composition comprising the clarifying agent and the nucleating agent is less than or equal to 20% or 15% to 20%, and wherein the haze value of the polymeric composition comprising the clarifying agent but not the nucleating agent is greater than 20% or greater than 20% to 25%.

11. The polymeric composition of claim 1, wherein the polypropylene is a homopolymer or a random copolymer or a blend thereof.

12. The polymeric composition of claim 1, wherein the polypropylene is a Zieglar-Natta catalyzed polypropylene or a metallocene-catalyzed polypropylene.

13. The polymeric composition of claim 1, wherein the polymeric composition has a melt flow index of 0.2 to 150 g/10 min as measured by ASTM D1238 (230 C./2.16 kg).

14. The polymeric composition of claim 1, wherein the polymeric composition further comprises an additive.

15. The polymeric composition of claim 14, wherein the additive is an antioxidant, an acid neutralizer, an antistatic agent, an antiblock agent, an antifog agent, an anticorrosion agent, a ultraviolet absorber, a lubricant, a plasticizer, a mineral oil, a wax, a clay, talc, calcium carbonate, diatomaceous earth, carbon black, mica, glass fibers, a filler, a slip agent, a pigment, an ultraviolet stabilizer, a fire retardant, a mold release agent, a dye, a blowing agent, a fluorescent agent, a surfactant, or any combination thereof.

16. The polymeric composition of claim 1, wherein the polymeric composition has at least one of the following properties: a tensile modulus of 200,000 to 230,000 psi, as measured by ASTM D638; a tensile strength at yield of 4,400 to 4,800 psi, as measured by ASTM D638; a flex modulus of 180,000 psi to 220,000 psi, as measured by ASTM D790; and/or a notched izod impact strength of 0.5 to 1.5 ft-lbs/in, as measured by ASTM D256.

17. The polymeric composition of claim 1, wherein the polymeric composition has a thickness of at least 2 mil, preferably at least 5 mil, more preferably at least 10 mil, or even more preferably 20 mil to 300 mil, or even still more preferably 20 mil to 100 mil.

18. The polymeric composition of claim 1, wherein the polymeric composition is an injection molded polymeric composition.

19. An article of manufacture comprising the polymeric composition of claim 1.

20. A method of making the article of manufacture of claim 19, the method comprising obtaining the polymeric composition of claim 1 and making the article of manufacture by injection molding, blow molding, compression molding, stretch molding, rotational molding, transfer molding, sheet extrusion thermoforming, shallow-draw thermoforming, deep-draw thermoforming, or profile extrusion.

21. The method of manufacture of claim 20, wherein the article of manufacture is an injection molded article of manufacture, preferably having a thickness of 20 mil to 100 mil.

22. A method of producing the polypropylene composition of claim 1, the method comprising: (a) obtaining a composition comprising: at least 95 wt. % of the polypropylene; a clarifying agent; and a nucleating agent; and (b) extruding the composition to obtain the polypropylene composition of claim 1.

23. The method of claim 22, wherein the extrusion conditions include melt temperatures of 200-260 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings.

[0035] FIG. 1 is a graph depicting tensile modulus of polypropylene compositions containing one or more additives.

[0036] FIG. 2 is a graph depicting tensile strength at yield of polypropylene compositions containing one or more additives.

[0037] FIG. 3 is a graph depicting flex modulus of polypropylene compositions containing one or more additives.

[0038] FIG. 4 is a graph depicting haze as a function of thickness of polypropylene molded plaques containing one or more additives.

DETAILED DESCRIPTION OF THE INVENTION

[0039] One aspect of the present invention is based on a discovery that a polypropylene composition that includes both a clarifying agent and a nucleating agent exhibits decreased haze when compared with the same composition without the nucleating agent and/or when compared to the same composition without the clarifying agent. This improved clarity can be particularly advantageous in applications where the polypropylene polymer has been formed (e.g., by injection molding) into an article of manufacture that has a thickness, for example, greater than 2 mil, preferably at least 5 mil, more preferably at least 10 mil, or even more preferably 20 mil to 300 mil, or even still more preferably 20 mil to 100 mil. Also, and as illustrated in the examples, the polypropylene compositions of the present invention can have increased mechanical properties when compared with formulations containing the clarifying agent but not the nucleating agent. Examples of increased mechanical properties include tensile modulus, tensile strength, flex modulus, and/or notched izod impact strength values. These attributes open up a wide range of applications and/or uses for the polypropylene compositions of the present invention.

[0040] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

A. Polypropylene

[0041] The polymers of the present invention can include homopolymers (e.g., isotactic, syndiotactic, atactic polypropylene) of polypropylene, random copolymers of propylene, and blends thereof. In some aspects, a controlled rheology grade polypropylene (CRPP) can be used. A CRPP is one that has been further processed (e.g., through a degradation process) to produce a polypropylene polymer with a targeted high melt flow index (MFI), lower molecular weight, and/or a narrower molecular weight distribution than the starting polypropylene.

[0042] Polypropylene can be prepared by any of the polymerization processes, which are in commercial use (e.g., a high pressure process, a slurry process, a solution process and/or a gas phase process) and with the use of any of the known catalysts (e.g., Ziegler Natta catalysts, chromium or Phillips catalysts, single site catalysts, metallocene catalysts, and the like). Polypropylene can be prepared using methods described in U.S. Pat. Nos. 8,957,159, 8,088,867, 8,071,687, 7,056,991 and 6,653,254. The polypropylene can also be purchased through a commercial source such as those from TotalEnergies (USA), Total SA, Lyondell Bassel Industries, Reliance Industries Ltd, Sinopec, and ExxonMobil Chemical Co. The polypropylene can be in previously extruded and/or be in solid form, for example, pellets.

[0043] The polypropylene compositions of the present invention can contain at least 90 wt. % polypropylene, such as 90 wt. % to 100 wt. %, or equal to any one of, at least any one of, at most any one of, or between any two of 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.1, 99.2, 99.3, 99.4, 99.5, 99.6, 99.7, 99.8 and 99.9, 99.95 and 100 wt. % of the polypropylene based on the total weight of the polypropylene. In some aspects, the polypropylene can be a polypropylene homopolymer or a random copolymer polypropylene. In certain aspects, the polypropylene can have, any one of, any combination of, or all of the following characteristics: (1) melt flow of 0.5 g/10 min to 150 g/10 min, or equal to any one of, at least any one of, at most any one of, or between any two of 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, and 150 g/10 min, measured in accordance with ASTM D1238 (230 C./2.16 kg), with a preferred melt flow being 5 to 15 g/10 min, (2) a tensile strength @ break of 2000 to 7000, preferably about 4,500 to 5,500 psi (MPa), as determined by D-882; (3) an elongation @ break of 300% to 1000%, preferably 600% to 800%, as determined by ASTM D-882; (4) a 1% secant modulus of 50,000 to 150,000, or preferably 75,000 to 125,000 psi, as determined by ASTM D-882; (5) a gloss @ 45 of 50 to 100, preferably 70 to 90, as determined by ASTM D-2457; (6) a melting point of 100 C. to 300 C., preferably 125 C. to 190 C., or even more preferably 140 C. to 180 C., or equal to any one of, at least any one of, at most any one of, or between any two of 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, and 180 C., as determined by ASTM D-3417, with melting point determined with a DSC-2 Differential Scanning Calorimeter; and/or (7) a density of 0.1 to 2 g/cc, preferably 0.7 to 1.1, g/cc, or even more preferably 0.85 g/cc to 0.95 g/cc, or equal to any one of, at least any one of, at most any one of, or between any two of 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, and 0.95 g/cc, as determined by ASTM D-1505. Data for (2)-(5) based on a non-oriented film2 mil (50 microns). In some aspects, the polypropylene is commercially available (e.g., Lumicene M6571 from TotalEnergies (Houston, Texas) can be used in the context of the present invention.

B. Clarifying Agents

[0044] Polypropylene compositions of the present invention can include a clarifying agent or a combination of clarifying agents. The clarifying agent can include a trisamide-based clarifier, a nonitol-based clarifier, and/or a sorbitol-based clarifier, or any combination thereof. Trisamide clarifiers include, but are not limited to, amide derivatives of benzene-1,3,5-tricarboxylic acid, amide derivatives of 1,3,5-benzenetriamine, derivatives of N-(3,5-bis-formylamino-phenyl)-formamide, derivatives of 2-carbamoyl-malonamide, and combinations thereof. In certain aspects the trisamide clarifier is N,N,N-benzene-1,3,5-triyltris(2,2-dimethylpropanamide). Nonitol-based clarifies include, but are not limited to, derivatives of nonitol, an example of which includes 1,2,3-trideoxy-4,5:5,7-bis-O-[(4-propylphenyl)methylene]-Nonitol (NX8000, CAS Reg. No. 882073-43-0, Milliken Chemical, Spartanburg, S.C.). Sorbitol clarifiers include, but are not limited to 1,2,3,4-dibenzylidene sorbitol (Millad 3905, CAS #: 32647-67-9, Milliken Chemical, Spartanburg, S. C.), 1,2,3,4-di-para-methylbenzylidene sorbitol (Millad 3940 CAS #: 54686-97-4, Milliken Chemical, Spartanburg, S.C.), and 1,2,3,4-di-meta, para-methylbenzylidene sorbitol (Millad 3998, CAS #: 135861-56-2, Milliken Chemical, Spartanburg, S.C.). Another clarifier that can be used in the context of the present invention includes NA-71 (ADK STAB NA-71) (Adeka Corporation, Tokyo, Japan). In some preferred aspects, the clarifier is 1,2,3-trideoxy-4,5:5,7-bis-O-[(4-propylphenyl)methylene]-Nontiol (NX8000, CAS Reg. No. 882073-43-0, Milliken Chemical, Spartanburg, S.C.). In other preferred aspects, the clarifier is a 1,3,5-benzenetrisamide amide derivative, preferably 1,3,5-tris(2,2-dimethyl propanamido)benzene (Irgacelar XT 386, BASF, Ludwigshafen, Germany).

[0045] The amount of clarifying agents that can be included in the polypropylene compositions of the present invention include 0.01 wt. % to 5 wt. % or any amount or range therein (e.g., 0.01 wt. %, 0.05 wt. %, 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, 0.5 wt. %, 0.6 wt. %, 0.7 wt. %, 0.8 wt. %, 0.9 wt. %, 1 wt. %, 1.5 wt. %, 2 wt. %, 2.5 wt. %, 3 wt. %, 3.5 wt. %, 4 wt. %, 4.5 wt. %, 5 wt. %). In some preferred aspects, the polypropylene compositions of the present invention can include 0.01 wt. % to 0.5 wt. % of the clarifying agent(s) or any amount or range therein (e.g., 0.01 wt. %, 0.02 wt. %, 0.03 wt. %, 0.04 wt. %, 0.05 wt. %, 0.06 wt. %, 0.07 wt. %, 0.08 wt. %, 0.09 wt. %, 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, or 0.5 wt. %).

C. Nucleating Agents

[0046] Polypropylene compositions of the present invention can include a nucleating agent or a combination of nucleating agents. The nucleating agent can include a phosphate ester based nucleating agent. Non-limiting examples of phosphate ester based nucleating agents include 2,2-methylenebis (4,6,-di-tertbutylphenyl) phosphate or Hyperform HPN 715 (Milliken Chemical, Spartanburg, S.C.). 2,2-methylenebis (4,6,-di-tertbutylphenyl) phosphate is commercially available from Adeka (Tokyo, Japan) under the tradenames ADK STAB NA-11 or ADK STAB NA-27. NA-27 is NA-11 in combination with a dispersant.

[0047] The amount of nucleating agents that can be included in the polypropylene compositions of the present invention include 0.01 wt. % to 5 wt. % or any amount or range therein (e.g., 0.01 wt. %, 0.05 wt. %, 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, 0.5 wt. %, 0.6 wt. %, 0.7 wt. %, 0.8 wt. %, 0.9 wt. %, 1 wt. %, 1.5 wt. %, 2 wt. %, 2.5 wt. %, 3 wt. %, 3.5 wt. %, 4 wt. %, 4.5 wt. %, 5 wt. %). In some preferred aspects, the polypropylene compositions of the present invention can include 0.01 wt. % to 0.5 wt. % of the nucleating agent or any amount or range therein (e.g., 0.01 wt. %, 0.02 wt. %, 0.03 wt. %, 0.04 wt. %, 0.05 wt. %, 0.06 wt. %, 0.07 wt. %, 0.08 wt. %, 0.09 wt. %, 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, or 0.5 wt. %).

[0048] In certain aspects, the polypropylene compositions of the present invention can include the clarifying agent and the nucleating agent at a wt. % ratio of 0.01/5 to 0.5/0.01 or any ratio therein (e.g., 0.0002:1, 0.001:1, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:, 45:1, 50:1).

D. Additives

[0049] The polypropylene compositions of the present invention can include various additives. Non-limiting examples of additives include an antiblocking agent, an antistatic agent, an antioxidant, a neutralizing agent, a blowing agent, a crystallization aid, a dye, a flame retardant, a filler, an impact modifier, a mold release agent, an oil, another polymer, a pigment, a processing agent, a reinforcing agent, a slip agent, a flow modifier, a stabilizer, an UV resistance agent, and combinations thereof. Additives are available from various commercial suppliers. Non-limiting examples of commercial additive suppliers include BASF (Germany), Dover Chemical Corporation (U.S.A.), AkzoNobel (The Netherlands), Sigma-Aldrich (U.S.A.), Atofina Chemicals, Inc., and the like. The amount of optional additives can range from 0.01 wt. % to 5 wt. % (e.g., 0.01 wt. %, 0.05 w.t %, 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, 0.5 wt. %, 0.6 wt. %, 0.7 wt. %, 0.8 wt. %, 0.9 wt. %, 1 wt. %, 1.5 wt. %, 2 wt. %, 2.5 wt. %, 3 wt. %, 3.5 wt. %, 4 wt. %, 4.5 wt. %, 5 wt. %, or any value or range there between) in the polypropylene composition.

E. Method of Making the Polymeric Composition

[0050] Polymeric compositions of the present invention can be made by blending the polypropylene with the clarifying and nucleating agents and optionally with other additives together. In some aspects, the polypropylene can be in a solid form (e.g., pellets) and can be melted and mixed with the clarifying and nucleating agents and optional other additives. Suitable blending machines are known to those skilled in the art. Non-limiting examples include mixers, kneaders and extruders. In certain aspects, the process can be carried out with an extruder by introducing the polypropylene and clarifying and nucleating agents and other additives to the extruder hopper. Non-limiting examples of an extruder includes single-screw extruders, contrarotating and co-rotating twin-screw extruders, planetary-gear extruders, ring extruders, or co-kneaders. The melt blending can be performed at a melt temperature of 200 C. to 260 C., or equal to any one of, at most any one of, or between any two of 200 C., 205 C., 210 C., 215 C., 220 C., 225 C., 230 C., 235 C., 240 C., 245 C., 250 C., 255 C., and 260 C. The polypropylene and the clarifying and nucleating agents and other additives can be subjected to an elevated temperature for a sufficient period of time during blending. The blending temperature can be above the softening point of the polypropylene.

[0051] The clarifying and nucleating agents and other additives can be premixed or added individually to the polypropylene. By way of example, the clarifying and nucleating agents and other additives can be premixed such that they are added to the polypropylene. Incorporation of clarifying and nucleating agents and other additives into the polypropylene can be carried out, for example, by mixing the above-described components using methods customary in process technology. The blending temperature can be above the softening point of the polypropylene. In certain aspects, a process can be performed at a temperature from about 160 C. to 250 C. Such melt mixing or melt compounding results in uniform dispersion of the present additives in the polypropylene.

F. Articles Containing the Polymeric Compositions

[0052] The polymeric compositions of the present invention can be included in an article of manufacture. In some aspects, the article of manufacture can be an extruded, a blow-molded, rotational-molded, an injection-molded, and/or thermoformed article. In some aspects, the article of manufacture can be transparent. Non-limiting examples of articles of manufacture can include, films, sheets, fibers, yarns, a packing filing, a forming film, a protective packaging, a shrink sleeve, and/or label, a shrink film, a twist wrap, a sealant film, a cap, a crate, a bottle, a jar, a funnel, a pipette tip, a well plate, a microtiter plate, a syringe, a suture, a face mask, personal protective equipment, a medical tool, a medical tray, a sample vial, a cuvette, a reaction vial, contact lens mold, a cigarette filter, a technical filter, woven socks, cold and warm weather sport clothing, undergarments, shoes, ropes, twines, bale warp, tape, construction/industrial fabrics, piping, non-electric fuses for initiating explosives, absorbent products (e.g., diapers), expandable foams, carpets, mats, rugs, furniture, toys, luggage, tote bags, duffle bags, sport bags backpacks, fabrics, food containers and lid, deli containers and lids, dairy containers and lids, vehicle parts, dashboards, bumpers, cladding, exterior trim, film cushioning, film skins, covers, interior vehicle elements. In these and other uses the resins may be combined with other materials, such as particulate materials, including talc, calcium carbonate, wood, and fibers, such as glass or graphite fibers, to form composite materials. Examples of such composite materials include components for furniture, automotive components and building materials, particularly those used as lumber replacement.

EXAMPLES

[0053] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.

Example 1 (Preparation of Polypropylene Composition)

[0054] A polypropylene composition (Example 1) was produced by combining a phenolic antioxidant (Irganox 1010, 0.06 wt. %), a secondary antioxidant (Irgafos 168, 0.06 wt. %), a neutralizer (calcium stearate, 0.03 wt. %), a nucleating agent (NA 27, 0.1 wt. %), and a metallocene polypropylene random copolymer base resin (M6571 in fluff form, balance), and extruding the mixture at a melt mass-flow rate (MFR) of 9 dg/min. The phenolic antioxidant, secondary antioxidant, and neutralizer are not believed to contribute to the haze value of the polypropylene composition. The compounds were produced on a 1 single screw extruder with three temperature zones (350 F.-410 F.-420 F. and 420 F. for the die).

Example 2 (Preparation of Polypropylene Composition)

[0055] A polypropylene composition (Example 2) was produced by combining a phenolic antioxidant (Irganox 1010, 0.06 wt. %), a secondary antioxidant (Irgafos 168, 0.06 wt. %), a neutralizer (calcium stearate, 0.03 wt. %), a nucleating agent (HPN 715, 0.1 wt. %), and a metallocene polypropylene random copolymer base resin (M6571 in fluff form, balance), and extruding the mixture at a melt mass-flow rate (MFR) of 9 dg/min. The phenolic antioxidant, secondary antioxidant, and neutralizer are not believed to contribute to the haze value of the polypropylene composition.

Example 3 (Preparation of Polypropylene Composition)

[0056] A polypropylene composition (Example 3) was produced by combining a phenolic antioxidant (Irganox 1010, 0.06 w t. %), a secondary antioxidant (Irgafos 168, 0.06 wt. %), a neutralizer (calcium stearate, 0.03 wt. %), a clarifier (Millad NX8000, 0.2 wt. %), and a metallocene polypropylene random copolymer base resin (M6571 in fluff form, balance), and extruding the mixture at a melt mass-flow rate (MFR) of 9 dg/min. The phenolic antioxidant, secondary antioxidant, and neutralizer are not believed to contribute to the haze value of the polypropylene composition.

Example 4 (Preparation of Polypropylene Composition)

[0057] A polypropylene composition (Example 4) was produced by combining a phenolic antioxidant (Irganox 1010, 0.06 wt. %), a secondary antioxidant (Irgafos 168, 0.06 wt. %), a neutralizer (calcium stearate, 0.03 wt. %), a nucleating agent (NA 27, 0.1 wt. %), a clarifier (Millad NX8000, 0.2 wt. %), and a metallocene polypropylene random copolymer base resin (M6571 in fluff form, balance), and extruding the mixture at a melt mass-flow rate (MFR) of 9 dg/min. The phenolic antioxidant, secondary antioxidant, and neutralizer are not believed to contribute to the haze value of the polypropylene composition.

Example 5 (Preparation of Polypropylene Composition)

[0058] A polypropylene composition (Example 5) was produced by combining a phenolic antioxidant (Irganox 1010, 0.06 wt. %), a secondary antioxidant (Irgafos 168, 0.06 wt. %), a neutralizer (calcium stearate, 0.03 wt. %), a nucleating agent (HPN 715, 0.1 wt. %), a clarifier (Millad NX8000, 0.2 wt. %), and a metallocene polypropylene random copolymer base resin (M6571 in fluff form, balance), and extruding the mixture at a melt mass-flow rate (MFR) of 9 dg/min. The phenolic antioxidant, secondary antioxidant, and neutralizer are not believed to contribute to the haze value of the polypropylene composition.

[0059] Table 1 below prepared polypropylene compositions from Examples 1-5.

TABLE-US-00001 TABLE 1* Example Number 1 2 3 4 5 Base Resin Type M6571 M6571 M6571 M6571 M6571 Additive wt. % wt. % wt. % wt. % wt. % Irganox 1010 0.06 0.06 0.06 0.06 0.06 Irgafos 168 0.06 0.06 0.06 0.06 0.06 Calcium Stearate 0.03 0.03 0.03 0.03 0.03 NA 27 0.1 0.1 HPN 715 0.1 0.1 Millad NX8000 0.2 0.2 0.2 *M6571 is a random copolymer metallocene polypropylene (TotalEnergies, Houston, Texas). It has a melt flow index of 9 g/10 min (2.16 Kg-230 C.). *Irganox 1010 is pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (BASF, Ludwigshafen, Germany). *Irgafos 168 is tris(2,4-di-tert-butylphenyl) phosphite (BASF, Ludwigshafen, Germany). *Calcium stearate is C.sub.36H.sub.70CaO.sub.4 (Baerlocher, Germany). NA 27 is 2,2-methylenebis (4,6,-di-tertbutylphenyl) phosphate with a dispersant (ADK STAB NA-27 Adeka (Tokyo, Japan)). *HPN 715 is Hyperform HPN 715 (Milliken Chemical, Spartanburg, S.C.). *Millad NX8000 is 1,2,3-trideoxy-4,5:5,7-bis-O-[(4-propylphenyl)methylene]-Nonitol (Milliken Chemical, Spartanburg, S.C.).

Example 6 (Results)

[0060] Polypropylene composition Example 1 included a nucleating agent (NA27) and no clarifier. This composition exhibited high tensile modulus (FIG. 1) and high flexural modulus (FIG. 2), but relatively poor clarity (high haze, FIG. 3). Similarly, polypropylene composition Example 2 included a nucleating agent (HPN-715) and no clarifier, and exhibited comparable properties.

[0061] Polypropylene composition Example 3 included a clarifier (NX8000) but no nucleating agents and exhibited the desired low haze (FIG. 3). This example, however, exhibited low tensile modulus (FIG. 1) and low flexural modulus (FIG. 2).

[0062] The polypropylene compositions (Examples 4 and 5) that included a nucleating agent (NA 27 or HPN 715, respectively) and a clarifier (NX8000) demonstrated high tensile modulus (FIG. 1), high flexural modulus (FIG. 2), and high clarity (low haze, FIG. 3). The decreased haze was more evident in thicker molded plaques, where the magnitude of haze difference over the single-additive compositions discussed above was greater (FIG. 4, see 80 mil plaque thickness). By including both a nucleating agent and a clarifier in polypropylene compositions, high stiffness polypropylene compositions that retain high clarity in thicker product applications has been obtained. These results can be attributed to a synergistic effect achieved by the combination of a nucleating agent and a clarifier in polypropylene compositions.

[0063] Table 2 below depicts Notched Izod Impact test results for the various polypropylene compositions described above.

TABLE-US-00002 TABLE 2 Example Number 1 2 3 4 5 Izod-Impact - Notched ft-lb/in 0.8 0.8 0.8 0.8 0.8 St. Dev ft-lb/in 0 0.1 0 0.1 0 Break Type - Notched Complete Complete Complete Complete Complete break break break break break

[0064] Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the above disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.