WO2002094920A2

WO2002094920A2 - Hydrogenated resin modified polyolefin nanocomposite

Info

Publication number: WO2002094920A2
Application number: PCT/US2002/016354
Authority: WO
Inventors: Juan M. Garces; Steve R. Lakso
Original assignee: The Dow Chemical Company
Priority date: 2001-05-22
Filing date: 2002-05-22
Publication date: 2002-11-28
Also published as: WO2002094920A9; WO2002094920A3; AU2002326301A1

Abstract

A nanocomposite composition of from one to thirty weight percent hydrogenated C9 aromatic polymer, from one to thirty weight percent cation exchanging layered silicate material, and from ninety eight to forty weight percent polyolefin, the hydrogenated C9 aromatic polymer and the cation exchanging layered silicate material being dispersed in the polyolefin polymer. The instant invention is also a method for making such nanocomposition by blending the hydrogenated C9 aromatic polymer, the cation exchanging layered silicate material and the polyolefin at a temperature sufficiently high to melt or soften the polyolefin polymer.

Description

HYDROGENATED RESIN MODIFIED POLYOLEFIN NANOCOMPOSITE

This application is under a United States Government contract with The Department of Commerce (NIST)- Advanced Technology Program Project #70NANB7H3028.

The instant invention relates to polyolefin (such as polyethylene or polypropylene) reinforced with delaminated or exfoliated cation-exchanging multi- layered silicates. Such composite materials are known in the art as a "nanocomposite polymers" when at least one dimension of the exfoliated multi-layered silicate material is less than sixty nanometers. Nanocomposite polymers generally have enhanced mechanical property characteristics vs. conventionally filled polymers, for example, increased tensile or flex modulus together with increased impact toughness.

Typically, the thickness of a single layer of a delaminated multi-layered silicate material is in the range of one to two nanometers while the length and width of such layer can be in the range of, for example, one hundred to one thousand nanometers. Photomicrographs of nanocomposite polymers usually show a dispersion of multiple layer units of the multi-layered silicate material in the polymer, for example, two, three, four and more layer units dispersed in the polymer. It is generally desired to achieve a high degree of exfoliation of the multi-layered silicate material. Ideally the degree of such exfoliation is so extensive that only single layer units are present. However, some improvement may be seen even if the multi-layered silicate material is only swelled with the bulk polymer, that is, "intercalated". If the multi-layered silicate material is not at least partially exfoliated or intercalated, then the mechanical property improvement of the polymer composite will usually be no better than if a conventional micron sized filler is dispersed in the polymer.

Multi-layered silicate materials have been treated with organic onium ions to facilitate exfoliation when blended with polar polymers such as polyamide polymers, United States Patent 5,973,053, herein fully incorporated by reference. As discussed in the '053 patent, when such onium ion treated multi-layered silicate materials are blended with non-polar polymers (such as polyethylene or polypropylene) essentially no exfoliation occurs. However, as disclosed in the '053 patent, by incorporating more than ten percent of a polar substituted main guest molecule as a compatibalizer, it is possible to achieve an effective degree of exfoliation of the onium treated multi-layered silicate material into the non-polar polymer.

In their natural state, the layers of cation-exchanging multi-layered silicates, such as montmorillonite, are held together by ionic bonds to the exchangeable cations. As discussed by Kawasumi et al. in Macromolecules, 1997, 6333-6338, when such silicates are blended with softened or melted polyolefin, the resulting shear forces are not sufficient to delaminate or exfoliate the silicate layers even when the cation is a quaternary ammonium ion because polyolefins are a relatively non-polar material.

Usuki et al., United States Patent 5,973,053, solved this problem with regard to polypropylene using two related approaches. The first approach (also described by Kawasumi et al.) was to blend a quaternary ammonium exchanged multi-layered silicate with a maleic anhydride modified polypropylene oligomer and then add an unmodified polypropylene polymer. The maleic anhydride modified polypropylene oligomer had sufficient polarity to exfoliate the silicate under the shear conditions of the blending process.

The second approach of Usuki et al. was to blend a quaternary ammonium exchanged multi-layered silicate with a maleic anhydride modified polypropylene polymer. The maleic anhydride modified polypropylene polymer had sufficient polarity to exfoliate the silicate under the shear conditions of the blending process.

Howeveer, a maleated polypropylene has poorer modulus characteristics than its non-maleated polypropylene counterpart. Blending a certain amount of a cation- exchanging milti-layered silicate with such maleated polypropylene is therefore necessary just to make the resulting modulus be the same as the modulus of the non- maleated polypropylene counterpart. It would be an advance in the art of polyolefin nanocomposites if an additive were discovered to facilitate the dispersion of a cation exchanging layered silicate material into a polyolefin that did not suffer from the above- mentioned problem associated with the use of maleated polypropylene.

The instant invention is a solution to the above-mentioned problem. The instant invention is a nanocomposite composition, comprising: from one to thirty weight percent hydrogenated C9 aromatic polymer, from one to thirty weight percent cation _. exchanging layered silicate material, and from ninty eight to forty weight percent polyolefin, the hydrogenated C9 aromatic polymer and the cation exchanging layered silicate material being dispersed in the polyolefin polymer.

The instant invention is also a method for making such nanocomposite composition by blending the hydrogenated C9 aromatic polymer, the cation exchanging layered silicate material and the polyolefin at a temperature sufficiently high to melt or soften the polyolefin polymer.

Fig. 1 is an idealized drawing made from an electron photo micrographic examination of a composition of the instant invention showing more than one half of the cation exchanging layered silicate material being present as one, two, three, four or five layer units.

The nanocomposite of the instant invention comprises from one to thirty weight percent hydrogenated C9 aromatic polymer, from one to thirty weight percent cation exchanging layered silicate material, and from ninety eight to forty weight percent polyolefin, the hydrogenated C9 aromatic polymer and the cation exchanging layered silicate material being dispersed in the polyolefin polymer. Preferably, more than one half of the cation exchanging layered silicate material is present as one, two, three, four or five layer units upon examination by electron microscopy (and most preferably, more than one half of the material is so apparent as one, two or three layer units). Photomicrographs of nanocomposite polymer compositions typically show a dispersion of multiple layer units of the cation exchanging multi-layered silicate material in the polymer. It is generally desired to achieve a high degree of exfoliation of the multi-layered silicate material. Ideally, the degree of such exfoliation is so extensive that only single layer units are present.

Referring now to Fig. 1, therein is shown a drawing reproduction of an electron photomicrograph of a polypropylene nanocomposite composition of the instant invention. The layered silicate material is shown delaminated or exfoliated as: three single layer units, one two layer unit, one three layer unit, one four layer unit, one five layer unit and two eight layer units. A one-layer unit typically is a platelet about 1 nanometers thick and 100-1000 nanometers wide.

The term "weight average molecular weight" is well known in the instant art and can be determined by, for example, gel permeation chromatography. The term "cation exchanging layered silicate material" is well known in the instant art and includes the "clay mineral" of United States Patent 5,973,053, fully incorporated herein by reference. Examples of cation exchanging layered silicate materials of the platy type include: l) biophilite, kaolinite, dickalite or talc clays,

2) smectite clays,

3) vermiculite clays,

4) mica, fluoromica

5) brittle mica, 6) Magadiite

7) Kenyaite,

8) Octosilicate,

9) Kanemite,

10) Hectorite, fluorohectorite l l) Makatite, and

12) Zeolitic layered materials such as ITQ-2, MCM-22 precursor, exfoliated ferrierite and exfoliated mordenite.

Many of the above clay materials exist in nature, and also can be synthesized, generally in higher purity than the native material. Any of the naturally occurring or synthetic cation exchanging layered silicate clay materials may be used in the present invention. Preferred are smectite clays, including montmorillonite, bidelite, saponite and hectorite.

The term "cation exchanging layered silicate material" also includes the "fibrous cation exchanging layered silicate material". The term "fibrous cation exchanging layered silicate material" includes materials such as attapulgite, boehmite, imogolite and sepiolite. The fibrous cation exchanging layered silicate materials can exfoliate to produce multi-fiber units (herein multi-layer units) and most preferably they exfoliate to produce single fiber units (herein single layer units) dispersed in the polyolefin polymer. Single fibers of a fibrous cation exchanging layered silicate material are typically about 500 nanometers long and can have a diameter of about 20 nanometers.

An "onium treated cation exchanging layered silicate material" is a cation exchanging layered silicate material that has been exposed to onium cations (usually organic quaternary ammonium compounds) so that the original cation of the cation exchanging layered silicate material is exchanged, at least in part, for the onium cations.

Onium treated cation exchanging layered silicate materials are well known in the instant art, for example, see the above-mentioned United States Patent 5,973,053. Onium treated cation exchanging layered silicate materials are commercially available from, for example, Southern Clay Company in the United States. It should be understood that onium treated or non-onium treated cation exchanging layered silicate material may be used in the instant invention. Hydrogenated C9 aromatic polymer is specifically defined herein as a polymer consisting of more than fifty weight percent of polymer having the following formula:

where a, b and c are the relative amounts of each unit in the polymer. Hydrogenated C9 aromatic polymer is commercially available from Arakawa Chemical Industries, LTD as ARKON brand hydrogenated hydrocarbon resin. Hydrogenated C9 aromatic polymer can be made by polymerizing the C9 fraction of a naphtha cracker and then hydrogenating the resulting polymer. Preferably, the weight average molecular weight of the hydrogenated C9 aromatic polymer is in the range of from one thousand to five thousand as determined by gel permeation chromatography. The term "hydrogenated C9 aromatic polymer" is more broadly defined herein as any polymer that is equivalent in the instant invention to the specific hydrogenated C9 aromatic polymber defined above in this paragraph.

Preferably, the amount of hydrogenated C9 aromatic polymer used is from 0.5 to 1.5 times the weight percent of cation exchanging layered silicate material. Most preferably, the amount of hydrogenated C9 aromatic polymer used is about the same as the amount of cation exchanging layered silicate material, that is, wherein the weight percent of hydrogenated C9 aromatic polymer is from 0.8 to 1.2 times the weight percent of cation exchanging layered silicate material. Preferably, the amount of cation exchanging layered silicate material used is from 3 to 20 weight percent. Most preferably, the amount of cation exchanging layered silicate material used is from 8 to 12 weight percent. The cation exchanging layered silicate material can be onium treated or not onium treated. Preferably, the polyolefin used in the instant invention is selected from the group of polyolefins polymerized from olefin monomers having from two to ten carbon atoms. Such olefin monomers include, for example, ethylene, propylene, octene, butadiene and mixtures thereof. Most preferably, the polyolefin used is polypropylene.

The instant invention is also a method for making a nanocomposite composition comprising from one to thirty weight percent hydrogenated C9 aromatic polymer, from one to thirty weight percent cation exchanging layered silicate material, and from ninety eight to forty weight percent polyolefin, the hydrogenated C9 aromatic polymer and the cation exchanging layered silicate material being dispersed in the polyolefin polymer, the method comprising the step of: blending the hydrogenated C9 aromatic polymer, the cation exchanging layered silicate material and the polyolefin at a temperature sufficiently high to melt or soften the polyolefin. Preferably, the cation exchanging layered silicate material has been pretreated by dispersing it in water under high shear conditions (such as by sonication or high shear mixing) followed by drying (such as spray drying or more preferably by freeze drying).

COMPARATIVE EXAMPLE 1 Grade PD-191 polypropylene from Montell is ground into a sand like powder that is then molded at 170 degrees Celsius and 30,000 pounds per square inch to form test bars for modulus testing using ASTM test method D882. The test indicates a tensile modulus of 220,000 pounds per square inch.

COMPARATIVE EXAMPLE 2

Ten grams of grade PI 40 ARKON brand hydrogenated C9 aromatic polymer from Arakawa Chemical Industries, LTD is blended with ninety grams of grade PD-191 polypropylene from Montell at 165 degrees Celsius for 10 minutes in a Haake torque reometer at a speed of 60 m to produce a polymer blend. The polymer blend is cooled and ground into a sand like powder which is then molded at 170 degrees Celsius and 30,000 pounds per square inch to form test bars for modulus testing using ASTM test method D882. The test indicates a tensile modulus of 274,000 pounds per square inch.

COMPARATIVE EXAMPLE 3

Ten grams of sepiolite are blended with ninety grams of grade PD-191 polypropylene from Montell at 165 degrees Celsius for 10 minutes in a Haake torque reometer at a speed of 60 φm to produce a polymer blend. The polymer blend is cooled and ground into a sand like powder which is then molded at 170 degrees Celsius and 30,000 pounds per square inch to form test bars for modulus testing using ASTM test method D882. The test indicates a tensile modulus of 344,000 pounds per square inch.

EXAMPLE 1

Ten grams of grade PI 40 ARKON brand hydrogenated C9 aromatic polymer from Arakawa Chemical Industries, LTD and ten grams of CLAYTONE HY (quat treated montmorillonite from Southern Clay) are blended with eighty grams of grade PD-191 polypropylene from Montell at 165 degrees Celsius for 10 minutes in a Haake torque reometer at a speed of 60 φm to produce a polymer blend. The polymer blend is cooled and ground into a sand like powder which is then molded at 170 degrees Celsius and 30,000 pounds per square inch to form test bars for modulus testing using ASTM test method D882. The test indicates a tensile modulus of 411,000 pounds per square inch. EXAMPLE 2

Ten grams of grade PI 40 ARKON brand hydrogenated C9 aromatic polymer from Arakawa Chemical Industries, LTD and five grams of sepiolite are blended with eighty- five grams of grade PD-191 polypropylene from Montell at 165 degrees Celsius i for 10 minutes in a Haake torque reometer at a speed of 60 φm to produce a polymer blend. The polymer blend is cooled and ground into a sand like powder which is then molded at 170 degrees Celsius and 30,000 pounds per square inch to form test bars for modulus testing using ASTM test method D882. The test indicates a tensile modulus of 413,000 pounds per square inch.

EXAMPLE 3

Ten grams of grade PI 40 ARKON brand hydrogenated C9 aromatic polymer from Arakawa Chemical Industries, LTD and ten grams of sepiolite are blended with eighty grams of grade PD-191 polypropylene from Montell at 165 degrees Celsius for 10 minutes in a Haake torque reometer at a speed of 60 φm to produce a polymer blend. The polymer blend is cooled and ground into a sand like powder which is then molded at 170 degrees Celsius and 30,000 pounds per square inch to form test bars for modulus testing using ASTM test method D882. The test indicates a tensile modulus of 480,000 pounds per square inch.

EXAMPLE 4

4.1 grams of sepiolite (Pangel S9 from Tolsa Chemical) is melt blended with 32.9 grams of Amoco brand 9934x high crystalline polypropylene (melt flow rate = 35g/10min), 4.1 grams of Arkon brand PI 40 resin (from Arakawa Chemical Industries) and 0.08 grams of Irganox B225 in a Brabender plasticorder at 180 degrees Celsius and 150 φm for 7 minutes. The polymer is premelted for 3 minutes prior to the addition of the sepiolite. The resulting blend is molded at 170 degrees Celsius and 30,000 pounds per square inch to form test bars for modulus testing using ASTM test method D882. The test indicates a tensile modulus of 646,000 pounds per square inch with a 1 percent elongation at break.

EXAMPLE 5 5 grams of sepiolite (Pangel S9 from Tolsa Chemical) is shaken with 95 grams of water and then sonicated at about 50 degrees Celsius for 4 hours. 5 grams of fiuoromica (Somasif ME 100 from Coop Chemical) is shaken with 95 grams of water and then sonicated at about 50 degrees Celsius for 4 hours. The two dispersions are then mixed and shaken for one hour, sonicated at about 50 degrees Celsius for 4 hour, air dried, then ground in a morter and then melt blended with 80 grams of Amoco brand 9934x high crystalline polypropylene (melt flow rate = 35g/10min), 10 grams of Arkon brand P140 resin (from Arakawa Chemical Industries) and 0.08 grams of Irganox B225 in a Brabender plasticorder at 180 degrees Celsius and 150 φm for 7 minutes. The polymer is premelted for 3 minutes prior to the addition of the sepiolite/fluoromica. The resulting blend is molded at 170 degrees Celsius and 30,000 pounds per square inch to form test bars for modulus testing using ASTM test method D882. The test indicates a modulus of 659,000 pounds per square inch with a 1 percent elongation at break.

Claims

WHAT IS CLAIMED IS:

1. A nanocomposite composition, comprising: from one to thirty weight percent hydrogenated C9 aromatic polymer, from one to thirty weight percent cation exchanging layered silicate material, and from ninety eight to forty weight percent polyolefin, the hydrogenated C9 aromatic polymer and the cation exchanging layered silicate material being dispersed in the polyolefin polymer.

2. The composition of Claim 1 , wherein more than one half of the cation exchanging layered silicate material is present as one, two, three, four or five layer units upon examination by electron microscopy.

3. The composition of Claims 1 -2, wherein the weight average molecular weight of the hydrogenated C9 aromatic polymer is in the range of from one thousand to five thousand as determined by gel-permeation chromatography.

4. The composition of Claims 1-3, wherein the weight percent of hydrogenated C9 aromatic polymer is from 0.5 to 1.5 times the weight percent of cation exchanging layered silicate material.

5. The composition of Claim 4, wherein the weight percent of hydrogenated C9 aromatic polymer is from 0.8 to 1.2 times the weight percent of cation exchanging layered silicate material.

6. The composition of Claim 4, wherein the amount of cation exchanging layered silicate material is from 3 to 20 weight percent.

7. The composition of Claim 5, wherein the amount of cation exchanging layered silicate material is from 8 to 12 weight percent.

8. The composition of Claims 1-7, wherein the cation exchanging layered silicate material is a mixture of platy and fibrous cation exchanging layered silicate material.

9. The composition of Claims 1-7, wherein the cation exchanging layered silicate material is selected from the group consisting of magadiite, kenyaite, montmorillonite, fiuoromica, sepiolite, boehmite, imogolite and attapulgite.

10. The composition of Claim 8-9, wherein the cation exchanging layered silicate material is an onium treated cation exchanging layered silicate material.

11. The composition of Claims 1-10, wherein the polyolefin polymer is polypropylene.

12. A method for making nanocomposite composition comprising from one to thirty weight percent hydrogenated C9 aromatic polymer, from one to thirty weight percent cation exchanging layered silicate material, and from ninety eight to forty weight percent polyolefin, the hydrogenated C9 aromatic polymer and the cation exchanging layered silicate material being dispersed in the polyolefin polymer, the method comprising the step of: blending the hydrogenated C9 aromatic polymer, the cation exchanging layered silicate material and the polyolefin at a temperature sufficiently high to melt or soften the polyolefin.