阅读说明：本技术 具有高刚度特性的聚丙烯聚合物组合物 (Polypropylene polymer compositions with high stiffness characteristics ) 是由 约翰·卡托 钟京 阿玛伊娅·蒙托亚-戈尼 于 2020-04-03 设计创作，主要内容包括：本发明公开了聚丙烯聚合物组合物,这些聚丙烯聚合物组合物具有优异的刚度特性。这些聚丙烯聚合物组合物通过将第一聚丙烯聚合物与第二聚丙烯聚合物组合来制备。已发现,这些聚合物的组合可制备除了具有优异的韧性特性之外还具有高刚度特性的组合物。此外,该聚合物组合物具有用于模塑成各种产品和制品的良好流动特性。特别有利的是,可以相对高的催化剂活性制备不同的聚丙烯聚合物,尤其在与过去制备的高结晶聚合物相比时。(Polypropylene polymer compositions are disclosed which have excellent stiffness characteristics. These polypropylene polymer compositions are prepared by combining a first polypropylene polymer with a second polypropylene polymer. It has been found that the combination of these polymers can produce compositions having high stiffness characteristics in addition to excellent toughness characteristics. In addition, the polymer compositions have good flow characteristics for molding into various products and articles. It is particularly advantageous that different polypropylene polymers can be prepared with relatively high catalyst activity, especially when compared to the high crystalline polymers prepared in the past.)

1. A polypropylene polymer composition comprising:

a combination of a first polypropylene polymer having a melt flow rate of from about 0.1g/10min to about 3g/10min and having a xylene solubles content of from about 1.0 wt.% to about 7 wt.%, and a second polypropylene polymer having a melt flow rate of from about 5g/10min to about 100g/10min and having a xylene solubles content of from about 1 wt.% to about 7 wt.%; and is

Wherein the polypropylene polymer composition has a flexural modulus according to the formula:

FX≥2072*XS^-0.18

wherein FX is flexural modulus, XS is xylene solubles content of the polypropylene polymer composition, the xylene solubles content of the polypropylene polymer composition is from about 2.5 wt% to about 7 wt%.

2. The polypropylene polymer composition of claim 1, wherein the first polypropylene polymer has a xylene solubles content of from about 2.5 wt% to about 7 wt% and the second polypropylene polymer has a xylene solubles content of from about 2.5 wt% to about 7 wt%.

3. The polypropylene polymer composition of claim 1, wherein one of the polypropylene polymers has a xylene solubles content of greater than 5 wt% and the other polypropylene polymer has a xylene solubles content of less than about 4 wt%.

4. The polypropylene polymer composition of claim 1, wherein one of the polypropylene polymers has a xylene solubles content of greater than 6 wt% and the other polypropylene polymer has a xylene solubles content of less than about 4 wt%.

5. The polypropylene polymer composition according to any one of the preceding claims, wherein the polypropylene polymer composition is prepared according to the following process:

polymerizing propylene monomer in the presence of a non-phthalate Ziegler-Natta catalyst to produce the polypropylene polymer composition.

6. The polypropylene polymer composition according to claim 1, wherein the first polypropylene polymer is present in the polymer composition in an amount of less than about 66 wt% and in an amount of greater than about 30%.

7. The polypropylene polymer composition according to claim 1, wherein the composition comprises a nucleating agent.

8. The polypropylene polymer composition according to claim 1, wherein the composition does not comprise a nucleating agent.

9. The polypropylene polymer composition according to any one of the preceding claims, wherein the polypropylene polymer composition has a melt flow rate of from about 0.5g/10min to about 30g/10min and has a xylene solubles content of from about 3 wt% to about 7 wt%, such as from about 3.5 wt% to about 6.8 wt%.

10. The polypropylene polymer composition according to any one of the preceding claims, wherein the polypropylene polymer composition has a polydispersity index of from about 5 to about 10.

11. The polypropylene polymer composition according to any one of the preceding claims, wherein the first polypropylene polymer has a polydispersity index of from about 4 to about 5.5 and the second polypropylene polymer has a polydispersity index of from about 4 to about 5.5.

12. The polypropylene polymer composition according to any one of the preceding claims, wherein the weight ratio between the first polypropylene polymer and the second polypropylene polymer is from about 5: 95 to about 80: 20, such as from about 30: 70 to about 67: 33.

13. The polypropylene polymer composition according to any one of the preceding claims, wherein the first polypropylene polymer and the second polypropylene polymer both comprise a non-phthalate ziegler-natta catalyzed polypropylene polymer.

14. The polypropylene polymer composition according to any one of the preceding claims, wherein the polypropylene polymer composition has a flexural modulus of from about 1,500MPa to about 2,500 MPa.

15. The polypropylene polymer composition according to any one of the preceding claims, wherein the polypropylene polymer composition has a melt flow rate of from about 0.5g/10min to about 3g/10 min.

16. The polypropylene polymer composition according to claim 15, wherein the composition has a xylene solubles content of from 3.5 to 7 wt%.

17. The polypropylene polymer composition according to any one of claims 1 to 14, wherein the polypropylene polymer composition has a melt flow rate of from about 5g/10min to about 30g/10 min.

18. The polypropylene polymer composition according to any one of the preceding claims, wherein said polypropylene polymer composition has an izod impact resistance of greater than about 40J/m and less than about 90J/m.

19. The method of claim 5, wherein the first polypropylene polymer and the second polypropylene polymer are each formed in a gas phase reactor.

20. The process of claim 5, wherein the first polypropylene polymer and the second polypropylene polymer are each formed in a bulk phase reactor.

21. The method of claim 5, wherein one of the first polypropylene polymer and the second polypropylene polymer is formed in a gas phase reactor and the other of the first polypropylene polymer and the second polypropylene polymer is formed in a bulk phase reactor.

22. The method of claim 21, wherein the first polypropylene polymer is formed in a bulk phase reactor and the second polypropylene polymer is formed in a gas phase reactor.

23. The method of claim 5, wherein each of the first polypropylene polymer and the second polypropylene polymer are formed in separate reactors and then combined together.

24. The method of claim 5, wherein the first polypropylene polymer and the second polypropylene polymer are formed sequentially in a series of reactors.

25. A polymer article formed from the polypropylene polymer composition of any one of claims 1 to 18.

26. The polymer article of claim 25, wherein the polymer article comprises a storage container or a packaging container.

Background

One important characteristic of many polymeric materials is stiffness. Stiffness refers to the rigid property of a material and can be measured by determining the flexural modulus of the material. Flexural modulus relates to the ability of a material to bend, or in other words, its resistance to bending when a force is applied perpendicular to a molded plate formed from a polymer.

Polymers with increased stiffness provide various advantages when molded into products and articles. For example, high stiffness polymers generally do not deform when subjected to external forces. Thus, free standing products and shape retention products can be made from high stiffness polymers. For example, increasing the stiffness of the polymer may translate into minimizing the thickness of various polymeric articles, such as containers, while still having sufficient stiffness and shape-conforming characteristics.

In the past, various measures have been taken to increase the strength of polypropylene polymers. For example, in the past, the stiffness of polypropylene polymers has been increased by increasing the crystallinity of the material. Increasing the crystallinity of the material provides the desired increase in stiffness. However, various problems are encountered.

For example, increasing the crystallinity of a polypropylene polymer can reduce the toughness of the polymer and result in brittleness of the final product. In addition, highly crystalline polypropylene can be somewhat difficult to process. For example, increasing the crystallinity of polypropylene polymers can shorten the operating window for melt processing the polymers, which increases the difficulty in forming the product.

In addition, the production cost of highly crystalline polypropylene may be somewhat high. For example, increasing the crystallinity of a polymer can reduce the effectiveness of a catalyst used to prepare the polymer. For example, as the crystallinity of the polymer increases, the catalyst activity of the Ziegler-Natta catalyst decreases. Therefore, a larger amount of catalyst is required to prepare the polymer, which can greatly increase the cost of preparing the polymer.

In view of the above, there is a need for polypropylene polymer compositions having relatively high stiffness properties and high toughness properties. There is also a need for a process for preparing polypropylene polymer compositions having high stiffness characteristics without reducing catalyst activity.

Disclosure of Invention

Generally, the present disclosure relates to a polypropylene polymer composition having relatively high stiffness characteristics. The polymer composition of the present disclosure can be prepared without reducing the catalyst activity and with a broad molecular weight distribution. The broad molecular weight distribution improves the processability of the composition.

In one embodiment, the present disclosure relates to a polypropylene polymer composition comprising a combination of a first polypropylene polymer and a second polypropylene polymer. The first polypropylene polymer has a melt flow rate greater than about 0.1g/10min and less than about 3g/10 min. The first polypropylene polymer has a xylene solubles content of greater than about 1 wt% (such as greater than about 2.5 wt%, such as greater than about 3 wt%, such as greater than about 3.5 wt%) and typically less than about 8 wt% (such as less than about 7 wt%). In one aspect, the xylene solubles content is greater than about 5 wt.%, such as greater than about 6 wt.%. In another aspect, the xylene solubles content is less than about 4 wt.%. The first polypropylene polymer may have a polydispersity index that is generally greater than about 4 and less than about 10.

The second polypropylene polymer added to the first polypropylene polymer may have a melt flow rate greater than about 5g/10min and less than about 100g/10 min. The second polypropylene polymer may have a xylene solubles content of greater than about 1 wt% (such as greater than about 2.5 wt%, such as greater than about 3 wt%, such as greater than about 4 wt%) and typically less than about 8 wt% (such as less than about 7 wt%). The second polypropylene polymer may have a polydispersity index greater than about 4 and less than about 5.5.

In one aspect, one of the polypropylene polymers has a xylene solubles content of greater than about 5 wt% (such as greater than about 6 wt%), and the other polypropylene polymer has a xylene solubles content of less than about 4 wt%.

The first polypropylene polymer may be present in the polypropylene polymer composition in a weight ratio of from about 5: 95 to about 80: 20 (such as from about 30: 70 to about 67: 33) relative to the second polypropylene polymer. In a particular embodiment, the first low melt flow rate polypropylene polymer is present in an amount less than the second polypropylene polymer. For example, in one embodiment, the weight ratio of the first polypropylene polymer to the second polypropylene polymer may be from about 5: 95 to about 45: 55. The overall polypropylene polymer composition may typically have a melt flow rate of greater than about 0.5g/10min (such as greater than about 0.7g/10min, such as greater than about 1g/10min) and typically less than about 30g/10min (such as less than about 25g/10min, such as less than about 20g/10 min). In one embodiment, for example, the melt flow rate may be from about 0.5g/10min to about 3g/10 min. In an alternative embodiment, the melt flow rate can be from about 5g/10min to about 20g/10 min.

The polypropylene polymer composition may have a total xylene solubles content typically greater than about 3 wt% (such as greater than about 3.5 wt%, such as greater than about 4 wt%) and typically less than about 8 wt% (such as less than about 7 wt%, such as less than about 6.8 wt%). The polypropylene polymer composition can have an overall polydispersity index greater than about 5 and less than about 10.

As noted above, the polypropylene polymer compositions of the present disclosure have relatively high stiffness characteristics. For example, the polypropylene polymer composition may have a flexural modulus (ASTM test D790) according to the formula:

2072*XS^-0.18

wherein XS is the xylene solubles content of the polypropylene polymer composition, and wherein the xylene solubles content of the polypropylene polymer composition may be from about 2.5 wt% to about 8 wt%.

For example, the polypropylene polymer compositions of the present disclosure can have a flexural modulus of greater than about 1500MPa (such as greater than about 1550MPa, such as greater than about 1600MPa, such as greater than about 1650MPa, such as greater than about 1700MPa) and typically less than about 2500 MPa. In addition to having excellent stiffness characteristics, the polypropylene polymer composition may exhibit an Izod impact resistance of greater than about 40J/m (such as greater than about 45J/m, such as greater than about 55J/m) and typically less than about 90J/m.

In one embodiment, both the first polypropylene polymer and the second polypropylene polymer may comprise polypropylene homopolymers. In an alternative embodiment, at least one of the polypropylene polymers may be a copolymer, such as a copolymer comprising ethylene units.

In one embodiment, the polypropylene polymer compositions of the present disclosure may be formed in a process that: in which a propylene polymer is polymerized in the presence of a non-phthalate ziegler-natta catalyst. The Ziegler-Natta catalyst may have a catalyst activity of greater than about 50kg/g to produce a polypropylene polymer composition. The polypropylene polymer may be prepared in a gas phase reactor or a bulk phase reactor.

In one embodiment, each of the first polypropylene polymer and the second polypropylene polymer are formed in separate processes and then combined. Alternatively, the first polypropylene polymer and the second polypropylene polymer may be formed sequentially in a series of reactors.

The polypropylene polymer compositions of the present disclosure can be used to form all different types of molded articles. In one embodiment, the polymer composition may be used to prepare all of the different types of molded articles using any suitable thermoforming or molding process. For example, extrusion blow molding, injection molding, rotational molding, extrusion, and the like may be used to prepare the article. The polypropylene polymer composition may also be used to prepare biaxially oriented polypropylene films. Articles that can be prepared according to the present disclosure include storage containers or packaging containers, such as food containers.

Other features and aspects of the present disclosure are discussed in more detail below.

Drawings

A full and enabling disclosure of the present disclosure, including the reference to the accompanying figures, is set forth more particularly in the remainder of the specification, in which:

figure 1 is a graphical representation of the results obtained in the following examples.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.

Defining and testing programs

As used herein, the term "polypropylene homopolymer" is a homopolymer comprising propylene monomer units.

As used herein, the term "propylene-ethylene copolymer" is a copolymer containing a majority weight percent of propylene monomer with ethylene monomer as a minor component. A "propylene-ethylene copolymer" (also sometimes referred to as polypropylene random copolymer, PPR, PP-R, RCP, or RACO) is a polymer having a single repeat unit of ethylene monomer, which is present in the polymer chain in random or statistical distribution.

The Melt Flow Rate (MFR) as used herein of the propylene-based polymer is measured with a 2.16kg weight at 230 ℃ according to ASTM D1238 test method.

Xylene Solubles (XS) is defined as the weight percentage of resin that remains in solution after a polypropylene random copolymer resin sample is dissolved in hot xylene and the solution is cooled to 25 ℃. This is also referred to as the XS method using gravimetric 90 minute settling time according to ASTM D5492-06 and is also referred to herein as the "wet process". XS can also be measured according to the Viscotek method as follows: 0.4g of the polymer was dissolved in 20mL of xylene and stirred at 130 ℃ for 60 minutes. The solution was then cooled to 25 ℃ and after 60 minutes the insoluble polymer fraction was filtered off. The resulting filtrate was analyzed by flow injection Polymer analysis using a Viscotek ViscoGEL H-100-3078 column with THF as the mobile phase at a flow rate of 1.0 mL/min. The column was connected to a Viscotek model 302 with light scattering, viscometer and refractometer detector operating at 45 deg.CTriple Detector Array (Viscotek Model 302 Triple Detector Array). Using Viscotek PolyCAL^TMPolystyrene standards maintain instrument calibration. Polypropylene (PP) homopolymer, such as biaxially oriented polypropylene (BOPP) grade Dow 5D98, was used as a reference material to ensure that the Viscotek instrument and sample preparation procedure provided consistent results by using polypropylene homopolymer, such as 5D98, as a control to check for process performance. The values for reference polypropylene homopolymers (such as 5D98) were originally derived from testing using the ASTM methods described above.

The above mentioned ASTM D5492-06 method may be suitable for determining the xylene soluble fraction. Generally, the procedure consists of the following steps: 2g of sample was weighed and dissolved in 200mL of o-xylene in a 400mL flask with 24/40 adapter. The flask was connected to a water cooled condenser and placed under nitrogen (N)₂) The contents were stirred and heated to reflux under conditions, and then maintained at reflux for an additional 30 minutes. The solution was then cooled in a temperature-controlled water bath at 25 ℃ for 90 minutes to crystallize the xylene insoluble fraction. Once the solution was cooled and the insoluble fraction precipitated from the solution, separation of the xylene soluble fraction (XS) from the xylene insoluble fraction (XI) was achieved by filtration through 25 micron filter paper. 100ml of the filtrate was collected in a pre-weighed aluminum pan and o-xylene was evaporated from this 100ml of filtrate under a stream of nitrogen. After evaporation of the solvent, the pan and contents were placed in a vacuum oven at 100 ℃ for 30 minutes or until dry. The pan was then cooled to room temperature and weighed. The xylene soluble fraction was calculated as XS (wt%) [ (m)₃-m₂)*2/m₁]100, wherein m₁Is the initial weight of the sample used, m₂Is the weight of an empty aluminum pan, and m₃Is the weight of the disc and residue (asterisk multiplication of the indicated terms or values is indicated here and elsewhere in this disclosure).

Ethylene content, measured using Fourier Transform Infrared (FTIR), and the like¹³The ethylene values measured by C NMR as the main method are relevant. The correlation and agreement between measurements made using both methods is described, for example, in the following documents: paxson, J.C.Randall, "Quantitative Measurement of Ethylene Incorporation into Propylene Copolymers by Carbon-13 Nuclear Magnetic Resonance and Infrered Spectroscopy, Analytical Chemistry, Vol.50, No. 13, p.11 1978, 1777 and 1780.

Flexural modulus was determined according to ASTM D790-10 method A using type 1 specimens at 1.3mm/min according to ASTM 3641 and molded according to ASTM D4101.

The polydispersity index was measured by Small Amplitude Oscillatory Shear (SAOS). The test was carried out using a stress-controlled dynamic spectrometer ARES G2(TA Instruments) manufactured by TA Instruments using a method according to Zeichner GR, Patel P D, 1981, "A comprehensive Study of Polypropylene Melt Rheology", the second world chemical engineering conference of Montreal, Canada. The temperature was controlled at 180 ℃. + -. 0.1 ℃ using an ETC oven. The oven interior was purged with nitrogen to prevent the sample from being degraded by oxygen and moisture. The sample holder was a 25mm diameter parallel plate. The samples were compression molded at 230 ℃ with a diameter of 25mm and a thickness of 2 mm. An oscillation frequency sweep was used to obtain the storage modulus (G'), loss modulus (G ") at 190 ℃ and under a nitrogen atmosphere. The Polydispersity (PDI) was calculated using the crossing Gc of G 'and G' at 190 ℃ using the following formula:

PDI＝10⁵/Gc

this test method is also generally described in us patent 9,045,570, which uses different sample sizes and cone-plate rheometers.

Izod impact strength was measured according to ASTM D256 and D4101.

Detailed Description

One of ordinary skill in the art will understand that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present disclosure.

Generally, the present disclosure relates to polypropylene compositions having a unique combination of physical properties. For example, in one embodiment, the polymer composition may be formulated to have a combination of relatively high stiffness properties with excellent toughness properties. In addition, the polymer composition can be formulated to have good flow characteristics. Thus, the polymer composition is particularly suitable for forming thermoformed products and molded articles, such as injection molded articles. In one embodiment, for example, the polymer composition may be used to form a container. Containers and other articles having an internal volume can be formed with minimal wall thickness due to the stiffness and toughness characteristics of the polymer composition. In this way, a polymer article can be efficiently formed using a minimum amount of polymer composition.

It is particularly advantageous that the polypropylene polymer compositions of the present disclosure can be formulated to have high stiffness characteristics while also having a broad molecular weight distribution and using a catalyst system that maintains high catalyst activity during polymerization. For example, during polymerization of the polymers of the present disclosure, non-phthalate Ziegler-Natta catalysts that maintain an activity of greater than about 50kg/g (such as greater than about 55kg/g, such as greater than about 60kg/g) during the preparation of the polymer composition may be used.

Generally, the polypropylene polymer compositions of the present disclosure comprise a blend of polymers. More specifically, the polymer composition comprises a combination of a first polypropylene polymer and a second polypropylene polymer. The first polypropylene polymer typically has a relatively lower melt flow rate than the second polypropylene polymer. It has been unexpectedly found that a relatively small amount of a low melt flow rate polymer in combination with a second polypropylene polymer is required to obtain a polymer composition having the desired high stiffness characteristics. In fact, the low melt flow rate polypropylene polymer may be present in the composition in an amount of less than 50 wt.% (such as in an amount of less than 40 wt.%, such as in an amount of less than 30 wt.%, such as in an amount of less than 20 wt.%) and still provide an overall polymer composition having excellent stiffness characteristics. These results are significant and unexpected.

Furthermore, as described above, polypropylene polymer compositions having a relatively broad molecular weight distribution can be prepared. The broad molecular weight distribution significantly improves the processability of the composition.

In addition, the xylene solubles content of the first and second polypropylene polymers are selectively controlled in order to maintain high catalyst activity during the preparation of the polymers while also maximizing the stiffness. For example, the resulting polymer composition can exhibit a flexural modulus according to the following formula:

2072*XS^-0.18

wherein XS is the xylene solubles content of the polypropylene polymer composition. The xylene solubles content of the polypropylene polymer composition may be, for example, from about 2.5 wt.% to about 8 wt.%.

For example, in one embodiment, the polypropylene polymer compositions of the present disclosure may have a flexural modulus of greater than about 1500MPa (such as greater than about 1550MPa, such as greater than about 1600MPa, such as greater than about 1650MPa, such as greater than about 1700MPa, such as greater than about 1750MPa) and typically less than about 2500MPa (such as less than about 2000 MPa). For example, in one embodiment, the polypropylene polymer composition can have a flexural modulus of greater than about 1525MPa and less than about 2000MPa, including all 25MPa increments therebetween.

In addition to excellent stiffness characteristics, the polypropylene polymer compositions of the present disclosure also have excellent toughness characteristics. For example, the polypropylene polymer compositions of the present disclosure may have an Izod impact strength greater than about 40J/m (such as greater than about 50J/m, such as greater than about 55J/m, such as greater than about 60J/m, such as greater than about 65J/m). The Izod impact strength is typically less than about 90J/m, such as less than about 80J/m.

As noted above, the polypropylene polymer compositions of the present disclosure comprise a first polypropylene polymer blended with a second polypropylene polymer. The first polypropylene polymer typically has a low melt flow rate and contributes significantly to the stiffness characteristics of the resulting composition. For example, the first polypropylene polymer can have a melt flow rate of less than about 3g/10min (such as less than about 1g/10min, such as less than about 0.8g/10min, such as less than about 0.5g/10min) and typically greater than about 0.01g/10min (such as greater than about 0.1g/10 min). While having a low melt flow rate, the first polypropylene polymer typically has a xylene solubles content of greater than about 2.5 wt% (such as greater than about 3 wt%, such as greater than about 3.5 wt%, such as greater than about 4 wt%, such as greater than about 4.5 wt%) and typically less than about 8 wt% (such as less than about 7 wt%). The first polypropylene polymer may be formed using a ziegler-natta catalyst and may have a relatively broad molecular weight distribution. In one embodiment, the first polypropylene polymer has a polydispersity index greater than about 4 and typically less than about 10 (such as less than about 8.5, such as less than about 7, such as less than about 5.5).

The second polypropylene polymer in combination with the first polypropylene polymer generally has a higher melt flow rate. For example, the second polypropylene polymer can have a melt flow rate generally greater than about 5g/10min (such as greater than about 7g/10min, such as greater than about 9g/10 min). The melt flow rate is typically less than about 100g/10min, such as less than about 40g/10min, such as less than about 30g/10min, such as less than about 25g/10 min. The xylene solubles content of the second polypropylene polymer is similar to the xylene solubles content of the first polypropylene polymer. For example, the xylene solubles content of the second polypropylene polymer is typically greater than about 1 wt.%, such as greater than about 2 wt.%, such as greater than about 2.5 wt.%, such as greater than about 3 wt.%, such as greater than about 4 wt.%. In certain embodiments, the xylene solubles content of the second polypropylene polymer may be greater than about 5 wt.%, such as greater than about 6 wt.%, such as greater than about 6.5 wt.%. The xylene solubles content of the second polypropylene polymer is typically less than about 10 wt%, such as less than about 9 wt%, such as less than about 8 wt%, such as less than about 7.5 wt%.

The second polypropylene polymer may also be formed using a ziegler-natta catalyst which maintains high catalyst activity during polymerization. The second polypropylene polymer may have a relatively broad molecular weight distribution and may have a polydispersity index greater than about 4 and typically less than about 10 (such as less than about 8.5, such as less than about 7, such as less than about 5.5).

In one embodiment, both the first polypropylene polymer and the second polypropylene polymer may be polypropylene homopolymers. In an alternative embodiment, one of the polypropylene polymers may be a copolymer. For example, the first polypropylene polymer may be a homopolymer and the second polypropylene polymer may be a copolymer. Alternatively, the first polypropylene polymer may be a copolymer and the second polypropylene polymer may be a homopolymer. In another embodiment, the first polypropylene polymer and the second polypropylene polymer are both copolymers. When present as a copolymer, one or both of the polypropylene polymers may contain minor amounts of comonomers, such as ethylene. For example, ethylene may be present in an amount less than about 1.5 wt.%, such as in an amount less than 1 wt.%. The copolymer may be a random copolymer, such as a micro-random copolymer.

According to the present disclosure, a first polypropylene polymer is blended with a second polypropylene polymer to produce a polypropylene polymer composition. The weight ratio between the first polypropylene polymer and the second polypropylene polymer in the final composition is typically from about 5: 95 to about 80: 20, such as from about 30: 70 to about 67: 33. In one embodiment, the first polypropylene polymer or the low melt flow rate polypropylene polymer may be present in an amount less than the second polypropylene polymer and still have the desired stiffness characteristics. For example, the first polypropylene polymer may be present in an amount of less than about 50 wt% (such as in an amount of less than about 45 wt%, such as in an amount of less than about 40 wt%, such as in an amount of less than about 35 wt%, such as in an amount of less than about 30 wt%, such as in an amount of less than about 25 wt%, such as in an amount of less than about 20 wt%) and typically in an amount of greater than about 5 wt% (such as in an amount of greater than about 10 wt%, such as in an amount of greater than about 15 wt%, such as in an amount of greater than about 20 wt%), based on the weight of the two polypropylene polymers present. In one aspect, the first polypropylene polymer is present in the polymer composition in an amount of about 30 wt.% to about 66 wt.% (such as about 30 wt.% to about 50 wt.%, such as about 30 wt.% to about 45 wt.%).

The resulting polypropylene polymer compositions not only have good stiffness characteristics, but are also well suited for thermoformable processes and molding processes (such as injection molding processes), especially due to the broad molecular weight distribution, for use in the preparation of various articles. For example, the composition can have a melt flow rate of greater than about 0.5g/10min (such as greater than about 0.7g/10min, such as greater than about 1g/10min, such as greater than about 2g/10min, such as greater than about 3g/10min, such as greater than about 5g/10min, such as greater than about 8g/10min, such as greater than about 10g/10min, such as greater than about 12g/10min, such as greater than about 15g/10 min). The melt flow rate is typically less than about 30g/10min, such as less than about 25g/10min, such as less than about 20g/10 min. In one embodiment, the melt flow rate of the polypropylene composition may be relatively low and may be from about 0.5g/10min to about 3g/10 min. Alternatively, the melt flow rate can be higher and can generally be from about 5g/10min to about 20g/10 min. The melt flow rate can be adjusted by adjusting the relative amounts of the different polymers to produce a polymer composition having a desired physical characteristic in combination with a desired flow characteristic.

The total xylene solubles content of the polypropylene polymer composition is typically greater than about 2 wt%, such as greater than about 2.5 wt%, such as greater than about 3 wt%, such as greater than about 3.5 wt%. The total xylene solubles content is typically less than about 10 wt.%, such as less than about 8 wt.%, such as less than about 7 wt.%, such as less than about 6.8 wt.%. The polydispersity index of the polymer composition is typically greater than about 4 (such as greater than about 5, such as greater than about 6) and typically less than about 10 (such as less than about 9, such as less than about 8).

In addition to the first polypropylene polymer and the second polypropylene polymer, the polypropylene polymer compositions of the present disclosure may also comprise various other additives and ingredients.

For example, the polypropylene composition may contain nucleating agents, mold release agents, slip agents, antiblocking agents, UV stabilizers, heat stabilizers (e.g., DSTDP), colorants/colorants, and the like. In one embodiment, the polymer composition may contain an antioxidant, such as a hindered phenol antioxidant. The polymer composition may also contain an acid scavenger. Each of the additives is typically present in the polymer composition in an amount of less than about 3 wt.%, such as less than about 2 wt.%, such as less than about 1 wt.%, such as less than about 0.5 wt.%, and typically greater than about 0.001 wt.%.

For example, in one embodiment, the polymer composition may optionally comprise a nucleating agent, such as an alpha-nucleating agent. The nucleating agent may typically be present in an amount greater than about 0.001 wt% and typically in an amount less than about 1 wt% (such as in an amount less than about 0.5 wt%, such as in an amount less than about 0.3 wt%).

In one embodiment, inorganic nucleating agents, such as talc, may be used. Other nucleating agents include sodium benzoate or polymeric nucleating agents such as partially metallic salts of rosin acid.

In another embodiment, the nucleating agent may be selected from phosphorus-based nucleating agents, such as a phosphate metal salt represented by the following formula.

Wherein R1 is oxygen, sulfur, or a hydrocarbon group having 1 to 10 carbon atoms; each of R2 and R3 is hydrogen or a hydrocarbon or hydrocarbon group having 1 to 10 carbon atoms; r2 and R3 may be the same as or different from each other, two R2 in R2, two R3 in R3, or R2 and R3 may be bonded together to form a ring, M is a monovalent to trivalent metal atom; n is an integer from 1 to 3, and m is 0 or 1, with the proviso that n > m.

Preferred examples of the α -nucleating agent represented by the above formula include sodium 2,2 ' -methylene-bis (4, 6-di-t-butylphenyl) phosphate, sodium 2,2 ' -ethylene-bis (4, 6-di-t-butylphenyl) phosphate, lithium 2,2 ' -methylene-bis (4, 6-di-t-butylphenyl) phosphate, lithium 2,2 ' -ethylene-bis (4, 6-di-t-butylphenyl) phosphate, sodium 2,2 ' -ethylene-bis (4-isopropyl-6-t-butylphenyl) phosphate, lithium 2,2 ' -methylene-bis (4-methyl-6-t-butylphenyl) phosphate, lithium 2,2 ' -methylene-bis (4-ethyl-6-t-butylphenyl) phosphate, lithium, Bis [2, 2 '-thiobis (4-methyl-6-t-butylphenyl) calcium phosphate ], bis [2, 2' -thiobis (4-ethyl-6-t-butylphenyl) calcium phosphate ], bis [2, 2 '-thiobis (4, 6-di-t-butylphenyl) magnesium phosphate ], bis [2, 2' -thiobis (4-t-octylphenyl) magnesium phosphate ], 2 '-butylidene-bis (4, 6-dimethylphenyl) sodium phosphate, 2' -butylidene-bis (4, 6-di-t-butylphenyl) sodium phosphate, 2 '-t-octylmethylene-bis (4, 6-dimethylphenyl) sodium phosphate, sodium 2, 2' -t-octylmethylene-bis (4, 6-dimethylphenyl) phosphate, sodium hydrogen phosphate, sodium hydrogen phosphate, sodium carbonate, sodium hydrogen phosphate, sodium hydrogen carbonate, sodium hydrogen carbonate, sodium hydrogen carbonate, sodium hydrogen carbonate, sodium hydrogen carbonate, sodium hydrogen carbonate, sodium hydrogen carbonate, 2,2 '-tert-octylmethylene-bis (4, 6-di-tert-butylphenyl) -sodium phosphate, bis [2, 2' -methylene-bis (4, 6-di-tert-butylphenyl) -calcium phosphate ], bis [2, 2 '-methylene-bis (4, 6-di-tert-butylphenyl) -magnesium phosphate ], bis [2, 2' -methylene-bis (4, 6-di-tert-butylphenyl) -barium phosphate ], 2 '-methylene-bis (4-methyl-6-tert-butylphenyl) -sodium phosphate, 2' -methylene-bis (4-ethyl-6-tert-butylphenyl) sodium phosphate, (4, 4 '-dimethyl-5, 6' -di-tert-butyl-2, sodium 2 '-biphenyl) phosphate, bis- [ (4, 4' -dimethyl-6, 6 '-di-tert-butyl-2, 2' -biphenyl) phosphate ], sodium 2,2 '-ethylene-bis (4-m-butyl-6-tert-butylphenyl) phosphate, sodium 2, 2' -methylene-bis- (4, 6-dimethylphenyl) -phosphate, sodium 2,2 '-methylene-bis (4, 6-di-tert-ethyl-phenyl) phosphate, sodium 2, 2' -ethylene-bis (4, 6-di-tert-butylphenyl) -phosphate, bis [2, 2 '-ethylene-bis (4, 6-di-tert-butylphenyl) -phosphate ], bis [2, 2' -ethylene-bis (4, magnesium 6-di-tert-butylphenyl) -phosphate ], bis [ barium 2,2 ' -ethylidene-bis- (4, 6-di-tert-butylphenyl) -phosphate ], hydroxy-bis [ aluminum 2,2 ' -methylene-bis (4, 6-di-tert-butylphenyl) -phosphate ], tris [ aluminum 2,2 ' -ethylidene-bis (4, 6-di-tert-butylphenyl) -phosphate ].

A second group of phosphorus-based nucleating agents includes, for example, hydroxy-bis [2, 4, 8, 10-tetrakis (1, 1-dimethylethyl) -6-hydroxy-12H-dibenzo- [ d, g ] -dioxo-phospha-octacyclo-6-oxyaluminum ] and their blends with lithium myristate or stearate.

Among the phosphorus-based nucleating agents, sodium 2,2 '-methylene-bis (4, 6-di-tert-butylphenyl) phosphate or hydroxy-bis [2, 2' -methylene-bis (4, 6-di-tert-butylphenyl) -phosphate ] or hydroxy-bis- [2, 4, 8, 10-tetrakis (1, 1-dimethylethyl) -6-hydroxy-12H-dibenzo- [ d, g ] -dioxo-phospha-octacyclo-6-oxyaluminum ] or their blends with lithium myristate or stearate are particularly preferred.

Sorbitol-based nucleating agents such as optionally substituted dibenzylidene sorbitol (e.g., 1, 3: 2, 4 dibenzylidene sorbitol, 1, 3: 2, 4 bis (methylbenzylidene) sorbitol, 1, 3: 2, 4 bis (ethylbenzylidene) sorbitol, 1, 3: 2, 4 bis (3, 4-dimethylbenzylidene) sorbitol, etc.) or rosin may also be used as nucleating agents.

Further suitable alpha-nucleating agents are polymeric nucleating agents selected from the group consisting of polymers of vinylcycloalkanes and polymers of vinylalkanes. Nucleation using these polymeric nucleating agents is achieved either by special reactor technology, where the catalyst is prepolymerized with monomers such as for example Vinylcyclohexane (VCH), or by blending the propylene polymer with the vinyl (cyclo) alkane polymer.

Nucleating agents such as ADK NA-11 (methylene-bis (4, 6-di-tert-butylphenyl) phosphate sodium salt) and ADK NA-21 (including hydroxy-bis [2, 4, 8, 10-tetrakis (1, 1-dimethylethyl) -6-hydroxy-12H-dibenzo- [ d, g ] -dioxo-phospha-octacyclo-6-oxyaluminum ]) are commercially available from Asahi Denka Kokai and are nucleating agents that can be added to polyolefin compositions. Millad NX8000 (nonanol, 1, 2, 3-trideoxy-4, 6: 5, 7-bis-O- [ (4-propylphenyl) methylene) ], Millad 3988(3, 4-dimethylbenzylidene sorbitol), Millad 3905, and Millad 3940, available from Milliken & Company, are other examples of nucleating agents that may be used.

Additional commercially available alpha-nucleating agents that may be used in the compositions are, for example, Irgaclear XT 386(N- [3, 5-bis- (2, 2-dimethyl-propionylamino) -phenyl ] -2, 2-dimethylpropionamide) from Ciba Specialty Chemicals, Hyperform HPN-68L and Hyperform HPN-20E from Milliken & Company.

According to one embodiment, the at least one alpha-nucleating agent consists of a polymeric nucleating agent selected from the group consisting of vinylcycloalkane polymers and vinylalkane polymers, preferably polyvinylcyclohexane (pVCH).

According to another embodiment, the at least one alpha-nucleating agent is selected from hydroxyl-bis [2, 4, 8, 10-tetrakis (1, 1-dimethylethyl) -6-hydroxy-12H-dibenzo- [ d, g ] -dioxa-phospha-octacyclo-6-oxyaluminum ] based nucleating agents (e.g. ADK NA-21, NA-21E, NA-21F), sodium 2,2 '-methylene-bis (4, 6-di-tert-butylphenyl) phosphate (ADKNA-11), aluminum hydroxy-bis [2, 2' -methylene-bis (4, 6-di-tert-butylphenyl) -phosphate ] and sorbitol based nucleating agents (e.g. Millad 3988, Millad 3905 and Millad 3940).

In one embodiment, the polypropylene composition may further contain a clarifying agent. Clarifying agents may be added to further improve the transparency characteristics of the composition. The clarifying agent may, for example, comprise a compound capable of creating a gelled network within the composition.

In one embodiment, the clarifying agent may include a sorbitol compound, such as a sorbitol acetal derivative. In one embodiment, for example, the clarifying agent can include dibenzyl sorbitol.

With respect to sorbitol acetal derivatives, which may be used as additives in some embodiments, the sorbitol acetal derivatives are shown in formula (I):

wherein R1-R5 comprise the same or different moieties selected from hydrogen and C1-C3 alkyl.

In some embodiments, R1-R5 are hydrogen, such that the sorbitol acetal derivative is 2, 4-dibenzylidene sorbitol ("DBS"). In some embodiments, R1, R4, and R5 are hydrogen, and R2 and R3 are methyl groups, such that the sorbitol acetal derivative is a 1, 3: 2, 4-di-p-methyldibenzylidene-D-sorbitol ("MDBS"). In some embodiments, R1-R4 are methyl groups and R5 is hydrogen such that the sorbitol acetal derivative is a 1, 3: 2, 4-bis (3, 4-dimethylol benzylidene) sorbitol ("DMDBS"). In some embodiments, R2, R3, and R5 are propyl groups (-CH2-CH2-CH3), and R1 and R4 are hydrogen, such that the sorbitol acetal derivative is a 1, 2, 3-trideoxy-4, 6: 5, 7-bis-O- (4-propylphenylmethylene) nonanol ("TBPMN").

Other embodiments of clarifying agents that may be used include:

1,3: 2, 4-dibenzylidene sorbitol

1,3: 2, 4-bis (p-methylbenzylidene) sorbitol

Bis (p-methylbenzylidene) sorbitol

Bis (p-ethylbenzylidene) sorbitol

Bis (5 ', 6', 7 ', 8' -tetrahydro-2-naphthylidene) sorbitol

In one embodiment, the fining agent may further comprise a bisamide, such as a benzenetriamide. The above clarifying agents may be used alone or in combination.

When present in the polymer composition, the one or more clarifying agents are typically added in an amount greater than about 200ppm, such as in an amount greater than about 1,800ppm, such as in an amount greater than about 2,000ppm, such as in an amount greater than about 2,200 ppm. The one or more fining agents are typically present in an amount less than about 20,000ppm, such as less than about 15,000ppm, such as less than about 10,000ppm, such as less than about 8,000ppm, such as less than about 5,000 ppm. The amount of clarifying agent present in the composition can depend on a variety of factors, including the type of clarifying agent used.

Various different polymerization methods and procedures can be used to prepare the first polypropylene polymer and the second polypropylene polymer. In one embodiment, both polymers are formed from propylene monomers in the presence of a Ziegler-Natta catalyst. For example, olefin polymerization may occur in the presence of a catalyst system comprising a catalyst, an internal electron donor, a co-catalyst, and optionally an external electron donor and/or an activity limiting agent. The polymerization process for preparing these two polymers can be carried out using known techniques. For example, the polymer may be formed in a gas phase reactor or a bulk phase reactor. In particular, the polymer may be formed in a gas phase reactor using a fluidized or stirred bed reactor, or in a slurry phase using an inert hydrocarbon solvent or diluent or liquid monomer. For example, both the first polypropylene polymer and the second polypropylene polymer can be formed in a gas phase reactor. Alternatively, both the first polypropylene polymer and the second polypropylene polymer may be formed in a bulk (liquid propylene) phase reactor. In another embodiment, one of the first polypropylene polymer and the second polypropylene polymer is formed in a gas phase reactor and the other of the first polypropylene polymer and the second polypropylene polymer is formed in a bulk phase reactor. For example, the first polypropylene polymer may be formed in a bulk phase reactor and the second polypropylene polymer may be formed in a gas phase reactor.

In one embodiment, the first polypropylene polymer and the second polypropylene polymer are prepared in two different polymerization processes and then combined together. Alternatively, the first polypropylene polymer and the second polypropylene polymer may be prepared sequentially in a process comprising a series of reactors. For example, one of the polypropylene polymers may be produced in a first reactor and then transferred to a second reactor where the other polypropylene polymer is produced.

In one embodiment of the present disclosure, the polymerization is carried out in the presence of a stereoregular olefin polymerization catalyst. For example, the catalyst may be a ziegler-natta catalyst. For example, in one embodiment, a catalyst sold under the trade name CONSISTA and commercially available from W.R. Grace & Company may be used. In one embodiment, the electron donor is selected to be phthalate free.

In one embodiment, the catalyst comprises a procatalyst composition containing a titanium moiety, such as titanium chloride, a magnesium moiety, such as magnesium chloride, and at least one internal electron donor.

The procatalyst precursor may include (i) magnesium, (ii) a transition metal compound from groups IV through VII of the periodic table, (iii) a halide, oxyhalide, and/or alkoxide of (i) or (i) and/or (ii), and (IV) a combination of (i), (ii), and (iii). Non-limiting examples of suitable procatalyst precursors include halides, oxyhalides, alkoxides, and combinations thereof of magnesium, manganese, titanium, vanadium, chromium, molybdenum, zirconium, hafnium.

In one embodiment, the procatalyst precursor contains magnesium as the sole metal component. Non-limiting examples include anhydrous magnesium chloride and/or its alcohol adduct, magnesium alkoxide, and/or magnesium aryl ether, mixed alkoxy magnesium halide, and/or carboxylated magnesium dialkoxide or magnesium aryl ether.

In one embodiment, the procatalyst precursor is an alcohol adduct of anhydrous magnesium chloride. Anhydrous magnesium chloride adducts are generally defined as MgCl₂-nROH, where n has 1.5-6.0, preferably 2.5-4.0, and most preferably 2.8-3.5 moles total alcohol. ROH is straight-chain or branched C₁-C₄An alcohol, or a mixture of alcohols. Preferably, ROH is ethanol, or a mixture of ethanol and a higher alcohol. If the ROH is a mixture, the molar ratio of ethanol to higher alcohol is at least 80: 20, preferably 90: 10, and most preferably at least 95: 5.

In one embodiment, the substantially spherical MgCl can be formed by a spray crystallization process₂-nEtOH adduct. In one embodiment, the MgCl is in spherical form₂Average particle size of precursor (Malvern d)₅₀) Between about 15-150 microns, preferably between 20-100 microns, and most preferably between 35-85 microns.

In one embodiment, the procatalyst precursor contains a transition metal compound and a magnesium metal compound. The transition metal compound has the general formula TrXx, wherein Tr is a transition metal, and X is halogen or C_1-10Hydrocarbyloxy or hydrocarbyl groups, and X is the number of such X groups in the compound, as well as in the magnesium metal compound. Tr may be a group IV, group V or group VI metal. In one embodiment, Tr is a group IV metal, such as titanium. X can be chloride ion, bromide ion, C_1-4Alkoxide or phenoxide or mixtures thereof. In one embodiment, X is chloride.

The precursor composition can be prepared by chlorination of the above-described mixed magnesium compound, titanium compound, or a mixture thereof.

In one embodiment, the precursor composition is of the formula Mg_dTi(OR^e)_fX_gIn which R is a mixed magnesium/titanium compound of^eIs an aliphatic or aromatic hydrocarbon radical having from 1 to 14 carbon atoms or COR ', wherein R' is an aliphatic or aromatic hydrocarbon radical having from 1 to 14 carbon atoms; each OR^eThe radicals are identical or different; x is independently chlorine, bromine or iodine; d is 0.5 to 56; or 2-4, or 3; f is 2 to 116, or 5 to 15; and g is 0.5 to 116, or 1 to 3.

According to the present disclosure, the above-described procatalyst precursor is combined with at least one internal electron donor. The internal electron donor may comprise a substituted phenylene aromatic diester.

In one embodiment, the first internal electron donor comprises a substituted phenylene aromatic diester having the following structure (I):

wherein R is₁-R₁₄Are the same or different. R₁-R₁₄Each of which is selected from the group consisting of hydrogen, substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, heteroatoms, and combinations thereof. R₁-R₁₄At least one of which is not hydrogen.

In one embodiment, the substituted phenylene aromatic diester can be any substituted phenylene aromatic diester as disclosed in U.S. patent application serial No. 61/141,959, filed 12/31/2008, which is incorporated herein by reference in its entirety.

In one embodiment, the substituted phenylene aromatic diester can be any substituted phenylene aromatic diester as disclosed in WO12088028, filed 12/20/2011, the entire contents of which are incorporated herein by reference.

In one embodiment, R₁-R₄At least one (or two, or three, or four) R group(s) in (a) is selected from the group consisting of substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, heteroatoms, and combinations thereof.

In one embodiment, R₅-R₁₄At least one (or some, or all) of the R groups in (a) are selected from substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, heteroatoms, and combinations thereof. In another embodiment, R₅-R₉At least one of andR₁₀-R₁₄at least one of which is selected from the group consisting of substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, heteroatoms, and combinations thereof.

In one embodiment, R₁-R₄At least one of (1) and R₅-R₁₄At least one of which is selected from the group consisting of substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, heteroatoms, and combinations thereof. In another embodiment, R₁-R₄At least one of (1), R₅-R₉At least one of (1) and R₁₀-R₁₄At least one of which is selected from the group consisting of substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, heteroatoms, and combinations thereof.

In one embodiment, R₁-R₄Any consecutive R groups in (a), and/or R₅-R₉Any consecutive R groups in (a), and/or R₁₀-R₁₄Any consecutive R groups in (a) may be linked to form an inter-ring structure or an intra-ring structure. The structure between/within the rings may or may not be aromatic. In one embodiment, the inter-ring structure/intra-ring structure is C₅Or C₆A membered ring.

In one embodiment, R₁-R₄At least one of which is selected from the group consisting of substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, and combinations thereof. Optionally, R₅-R₁₄At least one of which may be a halogen atom or an alkoxy group having 1 to 20 carbon atoms. Optionally, R₁-R₄And/or R₅-R₉And/or R₁₀-R₁₄May be joined to form an inter-ring structure or an intra-ring structure. The structures in the rings may or may not be aromatic.

At one endIn one embodiment, R₁-R₄And/or R₅-R₉And/or R₁₀-R₁₄Wherein any consecutive R groups may be C₅-C₆A member of a membered ring.

In one embodiment, structure (I) includes R₁、R₃And R₄Is hydrogen. R₂Selected from the group consisting of substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, and combinations thereof. R₅-R₁₄Are the same or different, and R₅-R₁₄Each of which is selected from the group consisting of hydrogen, substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, halogens, and combinations thereof.

In one embodiment, R₂Is selected from C₁-C₈Alkyl radical, C₃-C₆Cycloalkyl or substituted C₃-C₆A cycloalkyl group. R₂There may be mentioned methyl groups, ethyl groups, n-propyl groups, isopropyl groups, tert-butyl groups, isobutyl groups, sec-butyl groups, 2, 4, 4-trimethylpent-2-yl groups, cyclopentyl groups and cyclohexyl groups.

In one embodiment, structure (I) includes R₂Is methyl, and R₅-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₂Is ethyl, and R₅-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₂Is tert-butyl, and R₅-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₂Is ethoxycarbonyl, and R₅-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₂、R₃And R₄Are all hydrogen, and R₁Is selected from the group consisting of compounds having 1 to 20Substituted hydrocarbyl groups of carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, and combinations thereof. R₅-R₁₄Are the same or different and are each selected from the group consisting of hydrogen, substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, halogens, and combinations thereof.

In one embodiment, structure (I) includes R₁Is methyl, and R₅-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₂And R4 is hydrogen, and R₁And R₃Are the same or different. R₁And R₃Each of which is selected from the group consisting of substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, and combinations thereof. R₅-R₁₄Are the same or different, and R₅-R₁₄Each of which is selected from the group consisting of substituted hydrocarbyl groups having 1 to 20 carbon atoms, unsubstituted hydrocarbyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, halogens, and combinations thereof.

In one embodiment, structure (I) includes R₁And R₃Are the same or different. R₁And R₃Each of which is selected from C₁-C₈Alkyl radical, C₃-C₆Cycloalkyl radicals or substituted C₃-C₆A cycloalkyl group. R₅-R₁₄Are the same or different, and R₅-R₁₄Each of which is selected from hydrogen, C₁-C₈Alkyl groups and halogens. Suitable C₁-C₈Non-limiting examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, and 2, 4, 4-trimethylpent-2-yl groups. Suitable C₃-C₆Non-limiting examples of cycloalkyl groups include cyclopentyl and cyclohexyl groups. In another embodimentIn the scheme, R₅-R₁₄At least one of is C₁-C₈An alkyl group or a halogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₂、R₄And R₅-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁And R₃Is an isopropyl group. R₂、R₄And R₅-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁、R₅And R₁₀Each of which is a methyl group, and R₃Is a tert-butyl group. R₂、R₄、R₆-R₉And R₁₁-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁、R₇And R₁₂Each of which is a methyl group, and R₃Is a tert-butyl group. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which is an ethyl group. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁、R₅、R₇、R₉、R₁₀、R₁₂And R₁₄Each of which is a methyl group, and R₃Is a tert-butyl group. R₂、R₄、R₆、R₈、R₁₁And R₁₃Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₅、R₇、R₉、R₁₀、R₁₂And R₁₄Each of which is an isopropyl group. R₂、R₄、R₆、R₈、R₁₁And R₁₃Each of which is hydrogen.

In one embodiment, the substituted phenylene aromatic diester has structure (II) comprising R₁Is a methyl group, and R₃Is a tert-butyl group. R₂And R₄Each of which is hydrogen. R₈And R₉Is C forming a 1-naphthoyl moiety₆A member of a membered ring. R₁₃And R₁₄Is C forming another 1-naphthoyl moiety₆A member of a membered ring. Structure (II) is provided below.

In one embodiment, the substituted phenylene aromatic diester has structure (II) comprising R₁Is a methyl group, and R₃Is a tert-butyl group. R₂And R₄Each of which is hydrogen. R₆And R7 is C forming a 2-naphthoyl moiety₆A member of a membered ring. R₁₂And R₁₃Is C forming a 2-naphthoyl moiety₆A member of a membered ring. Structure (III) is provided below.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which is an ethoxy group. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which is a fluorine atom. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which is a chlorine atom. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which is a bromine atom. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which is an iodine atom. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₆、R₇、R₁₁And R₁₂Each of which is a chlorine atom. R₂、R₄、R₅、R₈、R₉、R₁₀、R₁₃And R₁₄Each of (1) toOne is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₆、R₈、R₁₁And R₁₃Each of which is a chlorine atom. R₂、R₄、R₅、R₇、R₉、R₁₀、R₁₂And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₂、R₄And R₅-R₁₄Each of which is a fluorine atom.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which is a trifluoromethyl group. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which is an ethoxycarbonyl group. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which is an ethoxy group. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a tert-butyl group. R₇And R₁₂Each of which isIs a diethylamino group. R₂、R₄、R₅、R₆、R₈、R₉、R₁₀、R₁₁、R₁₃And R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group, and R₃Is a 2, 4, 4-trimethylpentan-2-yl radical. R₂、R₄And R₅-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁And R₃Each of which is a sec-butyl group. R₂、R₄And R₅-R₁₄Each of which is hydrogen.

In one embodiment, the substituted phenylene aromatic diester has structure (IV) whereby R₁And R₂Is C forming a 1, 2-naphthalene moiety₆A member of a membered ring. R₅-R₁₄Each of which is hydrogen. Structure (IV) is provided below.

In one embodiment, the substituted phenylene aromatic diester has the structure (V), whereby R₂And R₃Is C forming a 2, 3-naphthalene moiety₆A member of a membered ring. R₅-R₁₄Each of which is hydrogen. Structure (V) is provided below.

In one embodiment, structure (I) includes R₁And R₄Each is a methyl group. R₂、R₃、R₅-R₉And R₁₀-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁Is a methyl group. R4 is an isopropyl group. R₂、R₃、R₅-R₉And R₁₀-R₁₄Each of which is hydrogen.

In one embodiment, structure (I) includes R₁、R₃And R₄Each of which is an isopropyl group. R₂、R₅-R₉And R₁₀-R₁₄Each of which is hydrogen.

In one embodiment, R₁And R₄Each of which is selected from a methyl group, an ethyl group, and a vinyl group. R₂And R₃Each of which is selected from hydrogen, a secondary alkyl group or a tertiary alkyl group, wherein R is₂And R₃Not hydrogen at the same time. In other words, when R2 is hydrogen, R3 is not hydrogen (and vice versa).

In one embodiment, a second internal electron donor may be used, which typically comprises a polyether that can coordinate in a bidentate fashion. In one embodiment, the second internal electron donor is a substituted 1, 3-diether having structure VI:

wherein R is₁And R₂Are identical or different and are methyl, C₂-C₁₈Straight or branched alkyl, C₃-C₁₈Cycloalkyl radical, C₄-C₁₈Cycloalkyl-alkyl, C₄-C₁₈Alkyl-cycloalkyl, phenyl, organosilicon, C₇-C₁₈Arylalkyl radical or C₇-C₁₈An alkylaryl group; and R is₁Or R₂And may also be a hydrogen atom.

In one embodiment, the second internal electron donor may comprise a 1, 3-diether having a cyclic or polycyclic structure VII:

wherein R is₁、R₂、R₃And R₄Is as for R of structure VI₁And R₂Said, or may be combined to form one or more C₅-C₇A fused aromatic or non-aromatic ring structure optionally containing N, O or S heteroatoms. Specific examples of the second internal electron donor include:

4, 4-bis (methoxymethyl) -2, 6-dimethylheptane, 9-bis (methoxymethyl) fluorene, or a mixture thereof.

The precursor is converted to a solid procatalyst by further reaction (halogenation) with an inorganic halide compound, preferably a titanium halide compound, and incorporation of an internal electron donor.

One suitable method for halogenating the precursor is by reacting the precursor at elevated temperature with a tetravalent titanium halide, optionally in the presence of a hydrocarbon or halocarbon diluent. The preferred tetravalent titanium halide is titanium tetrachloride.

The resulting procatalyst composition may generally contain titanium in an amount from about 0.5 wt.% to about 6 wt.%, such as from about 1.5 wt.% to about 5 wt.%, such as from about 2 wt.% to about 4 wt.%. The solid catalyst may contain magnesium typically in an amount of greater than about 5 wt.%, such as in an amount of greater than about 8 wt.%, such as in an amount of greater than about 10 wt.%, such as in an amount of greater than about 12 wt.%, such as in an amount of greater than about 14 wt.%, such as in an amount of greater than about 16 wt.%. Magnesium is contained in the catalyst in an amount of less than about 25 wt.%, such as less than about 23 wt.%, such as less than about 20 wt.%. The internal electron donor may be present in the catalyst composition in an amount of less than about 30 wt%, such as in an amount of less than about 25 wt%, such as in an amount of less than about 22 wt%, such as in an amount of less than about 20 wt%, such as in an amount of less than about 19 wt%. The internal electron donor is typically present in an amount greater than about 5 wt.%, such as greater than about 9 wt.%.

In one embodiment, the procatalyst composition is combined with a cocatalyst to form a catalyst system. The catalyst system is a system that forms an olefin-based polymer when contacted with an olefin under polymerization conditions. The catalyst system may optionally comprise an external electron donor, an activity limiting agent, and/or various other components.

As used herein, a "cocatalyst" is a substance capable of converting a procatalyst into an active polymerization catalyst. The promoter may comprise hydrides, alkyls, or aryls of aluminum, lithium, zinc, tin, cadmium, beryllium, magnesium, and combinations thereof. In one embodiment, the cocatalyst is of the formula R₃A hydrocarbyl aluminum cocatalyst represented by Al, wherein each R is an alkyl, cycloalkyl, aryl, or hydride group; at least one R is a hydrocarbyl group; two or three R groups may be joined in a cyclic group, thereby forming a heterocyclic structure; each R may be the same or different; and each R that is a hydrocarbyl group has from 1 to 20 carbon atoms, and preferably from 1 to 10 carbon atoms. In another embodiment, each alkyl group may be straight or branched chain, and such hydrocarbyl groups may be mixed groups, i.e., the groups may contain alkyl, aryl, and/or cycloalkyl groups. Non-limiting examples of suitable groups are: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, 2-methylpentyl, n-heptyl, n-octyl, isooctyl, 2-ethylhexyl, 5-dimethylhexyl, n-nonyl, n-decyl, isodecyl, n-undecyl, n-dodecyl.

Non-limiting examples of suitable hydrocarbylaluminum compounds are as follows: triisobutylaluminum, tri-n-hexylaluminum, diisobutylaluminum hydride, di-n-hexylaluminum hydride, isobutylaluminum dihydride, n-hexylaluminum dihydride, diisobutyhexylaluminum, isobutyldihexylaluminum, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, tri-n-octylaluminum, tri-n-decylaluminum, tri-n-dodecylaluminum. In one embodiment, the preferred cocatalyst is selected from the group consisting of triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, diisobutylaluminum hydride, and di-n-hexylaluminum hydride, and the most preferred cocatalyst is triethylaluminum.

In one embodiment, the cocatalyst is represented by the formula R_nAlX_3-nThe hydrocarbylaluminum compounds of wherein n ═ 1 or 2, R is an alkyl group, and X is a halide or alkoxide. Non-limiting examples of suitable compounds are as follows: methyl radicalAlumoxane, isobutylalumoxane, diethylaluminum ethoxide, diisobutylaluminum chloride, tetraethyldialumoxane, tetraisobutyldialumoxane, diethylaluminum chloride, ethylaluminum dichloride, methylaluminum dichloride and dimethylaluminum chloride.

In one embodiment, the catalyst composition comprises an external electron donor. As used herein, an "external electron donor" is a compound that is added independently of the formation of the procatalyst and contains at least one functional group capable of donating an electron pair to a metal atom. Without being bound by a particular theory, it is believed that the external electron donor enhances the catalyst stereoselectivity (i.e., reduces xylene solubles material in the derivative polymer).

In one embodiment, the external electron donor may be selected from one or more of the following: alkoxysilanes, amines, ethers, carboxylates, ketones, amides, carbamates, phosphines, phosphates, phosphites, sulfonates, sulfones, and/or sulfoxides.

In one embodiment, the external electron donor is an alkoxysilane. The alkoxysilane has the general formula: SiR_m(OR′)_4-m(I) Wherein each occurrence of R is independently hydrogen or a hydrocarbyl or amino group, optionally substituted with one or more substituents containing one or more group 14, group 15, group 16 or group 17 heteroatoms, said R' containing up to 20 atoms (hydrogen and halogen not counting); r' is C_1-4An alkyl group; and m is 0, 1, 2 or 3. In one embodiment, R is C_6-12Aryl, alkyl or aralkyl, C_3-12Cycloalkyl radical, C_3-12Branched alkyl or C_3-12A cyclic or acyclic amino group, R' is C_1-4Alkyl, and m is 1 or 2. Non-limiting examples of suitable silane compositions include dicyclopentyldimethoxysilane, di-t-butyldimethoxysilane, methylcyclohexyldimethoxysilane, methylcyclohexyldiethoxysilane, ethylcyclohexyldimethoxysilane, diphenyldimethoxysilane, diisopropyldimethoxysilane, di-n-propyldimethoxysilane, diisobutyldimethoxysilane, diisobutyldiethoxysilane, isobutylisopropyldimethoxysilaneDi-n-butyldimethoxysilane, cyclopentyltrimethoxysilane, isopropyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, diethylaminotriethoxysilane, cyclopentylpyrrolidindimethoxysilane, bis (pyrrolidine) dimethoxysilane, bis (perhydroisoquinolino) dimethoxysilane, and dimethyldimethoxysilane. In one embodiment, the silane composition is dicyclopentyldimethoxysilane (DCPDMS), methylcyclohexyldimethoxysilane (MChDMS), diisopropyldimethoxysilane (DIPDMS), n-propyltrimethoxysilane (NPTMS), Diethylaminotriethoxysilane (DATES), or n-Propyltriethoxysilane (PTES), and any combination thereof.

In one embodiment, the external donor may be a mixture of at least 2 alkoxysilanes. In further embodiments, the mixture may be dicyclopentyldimethoxysilane and methylcyclohexyldimethoxysilane, dicyclopentyldimethoxysilane and tetraethoxysilane, or dicyclopentyldimethoxysilane and n-propyltriethoxysilane.

In one embodiment, the external electron donor is selected from one or more of the following: benzoate esters and/or glycol esters. In another embodiment, the external electron donor is 2,2, 6, 6-tetramethylpiperidine. In another embodiment, the external electron donor is a diether.

In one embodiment, the catalyst composition comprises an Activity Limiting Agent (ALA). As used herein, an "activity limiting agent" ("ALA") is a material that reduces the activity of a catalyst at elevated temperatures (i.e., temperatures above about 85 ℃). ALA suppresses or otherwise prevents a polymerization reactor from malfunctioning and ensures that the polymerization process is continuously running. Generally, as the reactor temperature increases, the activity of the Ziegler-Natta catalyst increases. Ziegler-Natta catalysts also typically maintain high activity near the melting point temperature of the polymer being produced. The heat generated by the exothermic polymerization reaction can cause the polymer particles to form agglomerates and can ultimately lead to disruption of the continuity of the polymer production process. ALA reduces catalyst activity at elevated temperatures, thereby preventing reactor upsets, reducing (or preventing) particle agglomeration, and ensuring that the polymerization process is continuously conducted.

The activity limiting agent can be a carboxylic acid ester, a diether, a poly (alkylene glycol) ester, a glycol ester, and combinations thereof. The carboxylic acid ester may be an aliphatic or aromatic monocarboxylic or polycarboxylic acid ester. Non-limiting examples of suitable monocarboxylic acid esters include ethyl and methyl benzoates, ethyl p-methoxybenzoate, methyl p-ethoxybenzoate, ethyl acrylate, methyl methacrylate, ethyl acetate, ethyl p-chlorobenzoate, hexyl p-aminobenzoate, isopropyl naphthenate, n-pentyl toluate, ethyl cyclohexane and propyl pivalate.

In one embodiment, the external electron donor and/or the activity limiting agent may be added separately to the reactor. In another embodiment, the external electron donor and the activity limiting agent may be mixed together in advance and then added to the reactor as a mixture. In this mixture, more than one external electron donor or more than one activity limiting agent may be used. In one embodiment, the mixture is dicyclopentyldimethoxysilane and isopropyl myristate, dicyclopentyldimethoxysilane and poly (ethylene glycol) laurate, dicyclopentyldimethoxysilane and isopropyl myristate and poly (ethylene glycol) dioleate, methylcyclohexyldimethoxysilane and isopropyl myristate, n-propyltrimethoxysilane and isopropyl myristate, dimethyldimethoxysilane and methylcyclohexyldimethoxysilane and isopropyl myristate, dicyclopentyldimethoxysilane and n-propyltriethoxysilane and isopropyl myristate, and dicyclopentyldimethoxysilane and tetraethoxysilane, isopropyl myristate, amyl valerate, and combinations thereof.

In one embodiment, the catalyst composition comprises any of the foregoing external electron donors in combination with any of the foregoing activity limiting agents.

The first polypropylene polymer and the second polypropylene polymer may each be formed from a catalyst system as described above. The propylene polymers may be formed from the same non-phthalate ziegler-natta catalyst system or may be made from different non-phthalate ziegler-natta catalyst systems. It has been found that by using a catalyst system as described above in combination with controlling the xylene solubles content of the propylene polymer, a first polypropylene polymer and a second polypropylene polymer can be produced with relatively high catalyst activity while still producing a polypropylene polymer composition having excellent stiffness characteristics. For example, the first polypropylene polymer and the second polypropylene polymer may be prepared from a catalyst system as described above during a process wherein the catalyst activity is at least 50kg/g (such as at least 55kg/g, such as at least 60kg/g, such as even greater than about 65 kg/g). The catalyst activity is generally less than about 100 kg/g. According to the present disclosure, two different polypropylene polymers are then combined in order to maximize the stiffness properties without reducing toughness. Overall, the polypropylene polymer composition can be produced more efficiently than the high stiffness polypropylene polymers produced in the past. In addition, the polypropylene polymer compositions of the present disclosure have excellent thermoformability and moldability characteristics in addition to excellent stiffness and toughness characteristics, and can be easily molded into a variety of different articles and products.

For example, the polypropylene polymer compositions of the present disclosure are well suited for the preparation of molded articles. For example, the polypropylene compositions can be used in injection molding, blow molding, extrusion, and rotational molding applications.

The polypropylene polymer compositions of the present disclosure can be used to make a wide and varied range of articles and products. Polypropylene polymer compositions can be used to make all different types of free standing articles and products due to, for example, high stiffness characteristics and excellent flow characteristics. The high stiffness properties allow the article to be made with relatively thin walls while still having the desired shape retention properties. In addition, the high stiffness and toughness characteristics allow products and articles made according to the present disclosure to withstand impact forces that may result from dropping or other external events.

For example, the polypropylene polymer compositions of the present disclosure are well suited for the production of all different types of containers while minimizing wall thickness and thus minimizing the amount of polymer required to produce the article. Containers that can be prepared according to the present disclosure include, for example, storage containers, packaging containers, food containers, and the like. Other containers may include cups and other beverage or liquid holding containers.

The disclosure may be better understood with reference to the following examples.

Examples

Various polypropylene polymer compositions were prepared and tested for stiffness and toughness in accordance with the present disclosure. The samples were compared to a base reactor grade polypropylene polymer.

Samples prepared according to the present disclosure comprise a combination of a first polypropylene polymer and a second polypropylene polymer to form a polypropylene polymer composition. All of the polypropylene polymers produced were polymerized in the presence of a non-phthalate ziegler-natta catalyst system as described above. Specifically, the catalyst used was a CONSISTA catalyst sold by w.r.grace & Co. These polymers are produced in a gas phase reactor. In this example, only a polypropylene homopolymer was prepared.

Specifically, a sample of polymer pellets injection molded into a specimen is prepared. Specimens were prepared according to ASTM test D4101 to produce specimens for testing flexural modulus and izod impact resistance.

The melt flow rate and xylene solubles content of each polypropylene polymer produced were measured. The following results were obtained:

figure 1 is a graphical representation of the results shown above. In particular, fig. 1 compares the flexural modulus of the polymer with xylene solubles content. As shown, the polymers prepared according to the present disclosure have significantly better stiffness properties than the comparative samples. In one aspect, a sample prepared according to the present disclosure can exhibit a flexural modulus according to the following formula:

2072*XS^-0.18

wherein the xylene solubles content varies between 3 and 6.8 wt.%.

These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. Further, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Additionally, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.