POLY (METHYLPENTENE) COMPOSITION INCLUDING HOLLOW GLASS MICROSPHERES AND METHOD OF USING THE SAME
WIPO Patent Application WO/
A composition includes poly(4-methylpent-1-ene) and hollow glass microspheres. The composition has a density of less than 0.8 grams per cubic centimeter. Articles made from the composition and methods of making an article by injection molding the composition are also disclosed.
Inventors:
YALCIN, Baris (3M Center, Post Office Box 33427Saint Paul, Minnesota, , US)
HUNTER, Robert W. (3M Center, Post Office Box 33427Saint Paul, Minnesota, , US)
GUNES, Ibrahim S. (3M Center, Post Office Box 33427Saint Paul, Minnesota, , US)
Application Number:
Publication Date:
07/09/2015
Filing Date:
12/29/2014
Export Citation:
3M INNOVATIVE PROPERTIES COMPANY (3M Center, Post Office Box 33427Saint Paul, Minnesota, , US)
International Classes:
C08L23/18; C08J5/00; C08J9/00; C08K7/28
View Patent Images:
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Domestic Patent References:
Foreign References:
645563046924807658794
Other References:
See also references of EP
Attorney, Agent or Firm:
GROSS, Kathleen B. et al. (3M Center Office of Intellectual Property Counsel, Post Office Box 33427Saint Paul, Minnesota, , US)
What is claimed is:
1. A composition comprising:
poly(4<<methylpent- 1 -ene); and
hollow glass .microspheres,
wherein the composition has a density of less than 0.S grams per cubic centimeter,
2. The composition of cl i 1 , wherein the hollow glass microspheres have an average true density less than 0.5 grams per cubic centimeter.
3. The composition of claim 1 , comprising at least twenty-five percent by weight of the hollow glass microspheres, based on the total weight of the composition.
4. The composition of claim 11 wherein the composition has a density of up to 0,75 grams per cubic centimeter.
5. The composition of claim I, wherein a isostatic pressure at which ten percent by volume of the hollow glass microspheres collapses is in a 'range from about 70 megapascais t about 250 megapascais.
6. The. composition of claim 1, having m isostatic pressure resistance- with less than five percent volume loss more than double than, the isostatic pressure at which ten percent by volume of the hollow glass microspheres collapses.
7. The composition of claim 1, further comprising a polyolefin impact modifier that is chemically non-crosslinked and free of polar functional groups .
S. The composition of claim I , further comprising a polyolefin compatib 'zer modified with polar functional groups.
9. The composition of claim 8, wherein the composition comprises an impact modifier, wherein the composition has an isostatic pressure resistance with greater than 25 percent volume loss substantially the same as the isostatic pressure -at which ten percent by vol ume of the. hollow glass microspheres collapses.
10. The composition of claim 1 s wherein the impact modifier is an ethylene prop lene elastomer, an ethylene, octene elastomer, an ethylene propylene diene elastomer, an ethylene propy lene octene elastomer, or a combination thereof, and wherein the compatihilizer is a maleic anhydride-modified polyokfio,
1 \ . The composition of claim I , wherein the- po!y( methyl pentene) is microceUular.
12, An article comprising a solidified composition of any one of claims ] to 1 1 ,
13 , Th article of claim \ 2, wherein the article is spherical.
14. A conduit comprising the article of claim 12 within.
15, A method of making an article, the method comprising injection molding the' composition of one of claims 1 to 1 1 to make the article.
Description:
POLY ( ET BY LPE E E) COMPOSITION INCLUDING HOLLOW GLASS 'MICROSPHERES AND
METHOD OF USING THE SAME
Cross-Reference to Related Application
This application claims priority to U.S. Provisional Application No. 61 /921,831 , tiled December 30, 2013, the disclosure of which is incorporated by reference its entirety herein.
Background
Hollow glass microspheres having an average diameter of less than about 500 micrometers, also commonly known as "glass microbu bles", "glas bubbles "hollow glass beads", or "glass balloons" are widely used in industry, for example, as .additives to polymeric compositions. In many industries, hollow glass microspheres are useful, for example, for lowering weight and improving processing, dimensional stability, and flow properties of a polymeric composition. Generally, it is desirabl 'that the hollow glass microspheres be strong enough to avoid being crashed or broken during processing of the particular polymeric compound. Hollow glass microspheres have been incorporated into pol-y{4-me ylpen.t- 1 ^ene). compositions for m acoustic diaphragm in Japanese Pat No. 06-284496, published 1994.
The p esent -disclosure provides very low-density compositions that include poly(4- methy!pem ] -ene) and hollow glass -microspheres.
In one aspect the present disclosure pro ides a composition including poly(4-meth ipeni-l.- ens) and hollow glass microspheres. The composition has a density of less than 0.8 grams per .cubic centimeter.
n another aspect, the presen disclosure provides an article including such a composition, typically, when it is solidified,
Irs another aspect, the present- d isclosure provides a method of making an article. The method includes 'injection molding the -composition described above to make the article.
i some, embodiments, the compositions according to the present disclosure and articles made from them display an advantageous and unexpected combination of very low density, high isostatic pressure resistance, (e.g., at least twice that of the hollow glass microspheres measured by themselves), and low viscosit as measured by a high melt, flow rate. This combination of properties was not achieved with polypropylene, another low density thermoplasiic, as shown in the Examples, below,
in some embodiments, the compositions according to the present disclosure and articles made from mem not only display very low- density but also exhibit quick volume loss above a threshold isostatic pressure. Such behavior can be useful, for example, for pressure release or signaling a pressure build-up m various applications.
In this application, terms such as "a", "an'' and "the" are not intended to refer to only a singular entity, but include the general class of which a. specific example may be used for illustration. The terms "a", "an", and "the" are used interchangeably with the term "at least one". The phrases "at least one of and "comprises at least on(C) of followed by a list refers to any one of the items in the list and any combination of two or more items in the list. All numerical ranges are inclusive of their eodpoints and non-integral values between the endpoints unless otherwise stated (e.g., I to 5 includes 1 , 1 .5, 2, 2.75, 1, 3.80, 4, S, etc.).
The term "cross!inked" refers to joining polymer chains together by covatent chemical bonds, usually via crosslinkmg molecules or groups, to form a network polymer. Therefore, a chemically non-crosslmked polymer s a polymer that lacks polymer chains joined together by covalent chemical bonds to form a network polymer. A crosslinked polymer is generally characterized by insolubility, but may be s eilable in the presence of an appropriate solvent A non-erossHnked polymer is typically soluble in certain solvents and is typically elt-processa e. A polymer that is chemically nors-cross3inked may also be referred, to as a linear polymer,
A "polar functional group" is a functional group that includes -at least one atom that is more electronegative than .carbon. Common elements of organic compounds that are more electronegative than carbon are oxygen, nitrogen, sulfur,, and halogens, in some embodiments, a polar functional groiap is a functional group tha includes at least one oxygen atom. Such groups include hydroxyl and carbonyj groups (e.g., such as those in ketones, aldehydes, earboxylic acids, earboxyamides, earboxylic acid anhydrides, and earboxylic acid esters).
The above summary of the present disclosure' is not intended to describe each disclosed em bodimen t or ever&' implementation of the. present disclosure. The description that fellows more particularly .exemplifies- illustrative embodiments. It is to be understood, therefore, that the following description should not be read in a manner that would unduly limit the scope of this disclosure.
Brief Description of the Drawings
FIG. 1 is a graph of volume loss vs. pressure used to measure isostatic pressure resistance for a sample in the E
FIG. 2 is a graph of volume loss vs. pressure used to measure isostaiic pressure resistance for a different type of sample in the E and
FIG. 3 is a graph showing isostatic pressure resistance for Examples CE . .EX3, EX4, and EX 5, Detailed Description
Compositions according to the present disclosure include poIy(4-methyIpent- 1 -ene), which has 8 density of 0,825 grams per cable centimeter. Poly(4-methyipent-i -ene), abbreviated hereinafter as PMP is available commercially, for example, from Mitsui Chemicals, inc.. Tokyo. Japan, under the trade designation ' "TPX".
Compositions according to the present disclosure also include hollow glass microspheres. Hollow glass microspheres useful in the compositions and methods according to the present disclosure can he made by techniques known in the art (see, e.g., li. S. Pat. Nos. 2,978,340 (Veatch et ah); 3,030,215 (Veatch et ah); 3, 1.29,086 (Veatch et ah); and 3,230,064 (Veatch et ah); 3,365,315 (Beck et ah); 4,391 ,646 (Howell); and 4,767,726 (Marshall); and U. S. Pat. App, Pub. No.
(Marshall et. al). Techniques for preparing hollow glass microspheres typically include heating milled frit, commonly referred to as "feed", which contains a blowing agent (e.g., sulfur or a compound of oxygen and sulfur). Frit can be made by heating mineral components of glass at high temperatures until molten glass is formed.
Although the frit and/or the feed may have any composition that is capable of forming a glass, typically, on a total weight basis, the frit comprises from 50 to 90 percent of SiOj, from 2 to 20 percent of alkali metal oxide, from 1 to 30 percent of B2O3, from Θ.005-Θ.5 percent of sulfur (for example, as elemental sulfur, sulfate or sulfite), from 0 to 25 percent divalent meial oxides (for example, CaO, 'MgO, BaO, SrO, ZnO, or PbO), from 0 to 10 percent of tetravalent metal oxides other than SiO'2 (for example, Τ?? 3/4 >> ft02<< or Ζι
3/4 ), ro 0 to 20 percent of trivalent metal oxides (for example, AI2O3, F jO^, or Sb20 3/4 ), from O to 10 percent of oxides of pent&valent atoms (for example, PjOs or V O5), and fro 0 to 5 .percent -fluorine (as fluoride) which, may act as a fluxing agent to facilitate melting of the glass composition. Additional ingredients are useful in frit compositions and can he included in the frit, for example, to contribute particular properties or characteristics (for example, hardness or color) to the resultant glass bubbles.
In some -embodiments, the hollow glass microspheres useful in the compositions and methods according to the present disclosure have a glass composition comprising more alkaline earth metal oxide than alkali metal oxide, in. some of these embodiments, the weight ratio of alkaline earth metal oxide to alkali metal oxide is in a range from 1 .2: 1 to 3: 1. In some embodiments, the hollow glass microspheres have a glass composition comprising B2O3 in a range fro 2 percent to 6 percent based on the total weight of the glass bubbles, in some embodiments, the hollow glass microspheres have a glass composition comprising up to 5 percent by weight AS2O3. based on the total weight of the- hollow glass microspheres, in some embodiments, the glass composition is essentially free of AijOs. "Essentially free 0TAI2O3" may mean up to 5, 4, 3, 2, 1, 0.75, 0,5, 0.25, or 0.1 percent by weight AI2O5. Glass compositions that are "essentially free of A O?" also include glass compositions having no A!JOJ. Hollow glass microspheres useful for practicing the present disclosure may have, Irs some embodiments, a chemical composition wherein at least 90%,· 94%, or even at least 97% of the glass com prises at least 67% Si h, (e.g., a range of 70% to 80% SiOi), a range of 8% to 15% of an alkaline earth metal oxide (e.g., CaO), a range of 3% to 8% of an alkali metal oxide (e.g., NajO), a range of 2% to 6% B2O5, and a range of 0.125% to 1.5% SOj, In some- embodiments, the glass comprises in range from 30% to 40% Si, 3% to 8% N&, 5% to 1 1% Ca, 0.5% to 2% B, and 40% to 55% O, based on the total of the glass composition.
The "average true density" of hollow glass microspheres is the quotient obtained by dividing the mass of a sample of hollow glass mtcrospheres by the true volume of that mass of hollow glas microspheres as measured by a gas pycnometer. The "true volume" is the aggregate total volume of the hollow glass microspheres, not the bulk volume. The average true density of the hollow glass mtcrospheres useful for practicing the present disclosure is generally at least 0.20 grams per cubic centimeter (g/ce), 0.25 g/cc, or 0.30 g/cc. In some embodiments, the hollow glas microspheres useful for practicing the present disclosure have an average true density of up to about 0,65 g/cc. "About 0.65 g ec" means 0.65 g/ec ± five percent, in some of these embodiments, to efficiently lower the density (C)fthe composition, the average true density of the hollow glass microspheres is up to 0,5' g/cc of less Shan 0,5 g/cc. For example, the average true density of the hollow glass microspheres disclosed herein may be in a range from 0.2 g cc to 0.65 g/cc. 0.2 g/cc to'0.5 g/cc, 0,2 g cc to 0.49 g/cc, 0.3 g/cc to 0,50 g cc, 0,3 g/cc to 0,49 g/cc, or 0,3 g cc to 0.48 g ec. Hollow 'glass microspheres having any of these densities can be useful for lowering the density of the composition according to th
For the purposes of this disclosure, average true density- is measured using a pycnometer according, to ASTM D2S40- 69, " Average True Particle Density of Hollow Microspheres". The pyenometer may be obtained, for example, under the trad designation. "ACCUPYC 1330
PYCNOMETER" from Micromeritics, Norcross, Georgia, or under the trade designations
"PENTAPyCNDMETER" or "ULTRAPYCNOMETBR 1000" from Formanex,
3/4 c, San Diego, CA. Average true density can typically be measured with an accuracy of 0.001 g/cc. Accordingly, -each of the density vakres provided above can be.-t. five percent,
A variety of sizes of hollow glass microspheres may be useful. .As used herein, the term size is considered to be equivalent with the diameter and height of the hollow glass microspheres, hi some embodiments, the hollow glass microspheres can have a median size by volume in a range from 14 to 45 micrometers (in -some embodiments from 15 to 40 micrometers, 20 to 45 micrometers, or 20 to 40 micrometers). The median size is also called the "050 size, where 50 percent by volume of the hollow glass .microspheres in the distribution are smaller than the indicated size. For the purposes of the present disclosure, the median size by volume is determined by laser light diffraction by dispersing the hollow glass microspheres in deaeraied, deionized water. Laser light diffraction particle size analyzers are available, for example, under the trade designation "SATURN DIG!SIZER" from Micromeritics. The size distribution of the hollow glass microspheres useful for practicing the present disclosure may be Gaussian, normal, or non-normal. Non-normal distributions may be uniraodal or multi-modal (e.g., b nodal).
The hollow glass microspheres useful in the compositions and methods according to the present disclosure typically need to be strong enough to survive the injection molding process. A useful isostatie pressure at which ten percent: by volume of the hollow glass microspheres collapses is at least about 17 (in some embodiments, at least about 20, 38, SO, or 55) Megapasca!s (MPs). "About 17 MPa" means 17 MPa ± five percent. In some embodiments, a isostatie pressure at which ten percent by volume of the hollow glass microspheres collapses can be at least 100, 1 10, or 120 MPa. In some embodiments, a isostatie pressure at which ten percent, or twenty percent, by volume of the hollow glass microspheres collapses s up to 250 (in some embodiments, u to 210, 190, or 170} MPa. The Isostaiic pressure at which ten percent by volume of hollow glass microspheres collapses may be in a range from 17 MPa to 250 MPa, 38 MPa to 210 MPa, 50 MPa. to 210 MPa, or 70 MPa to 250 MPa. For the purposes of the present disclosure, the collapse strength of the hollow glass
microspheres is measured on a dispersion of the hollow glass microspheres in glycerol using ASTM D3102 -72 "Hydrostatic Col lapse Strength of Hollow Glass Microspheres"; with the exception that the sample size (in grams) is equal to 10 time the density of the glass bubbles. Collapse strength can typically be measured with as accuracy of ± about five percent. Accordingly, each of the collapse strength values provided above -can be ± five percent.
It should be understood by a person skilled in the art thai not all hollow glass microspheres with the same density have the same collapse .strength and that an increase in density does not always correlate with an increase in collapse strength. As described in the Examples below, one hollow glass microsphere that was incorporated into PMP had an average true density of 0.46 g/ce and a collapse strength of 16,000 psi ( 1 .10 MPa), and another hollow glass microsphere that was incorporated into PMP had an average true density of 0.46 g/cc and a collapse strength of 6000 psi (41 MPa), it. is therefore evident that a person skilled in the art would not know the collapse strength of a hollow glass microsphere from the density alone.
Hollo glass microspheres useful for practicing the present disclosure can be obtained commercially and include those marketed by 3M Company, St. Paul MN, under the trade designation "3M GLASS BUBBLES" (e.g., grades l , K15, S I 5, S22, 20, K25, S32, K37, S38, S38HS, S38XHS. K46, A 16/500, A2O/IOO0, D32/4500, H50/10000, S60, S60HS, 1.M30 , iM l6 , S38HS, S38XHS, K42HS, 46, and H50/I0000). Other suitable hollow glass microspheres can be obtained, for example, from Potters industries. Valley Forge, PA, (an affiliate of PQ Corporation) under the trade designations "SPHERICEL HOLLOW GLASS SPHERES" (e.g., grades U 0P8 and 6GP18) and "Q-CEL HOLLOW SPHERES" (e.g., grades 30, , 602$, ,
, 5023, and 5028), from Silbrico Corp,, Hodgkins, it, under the trade designation "SIL -CELL" (e.g., grades SIL 3.5/34, SlL-32, SfL-42, and SIL- 3), and from Sinostee! Maanshan lost, of Mining. Research. Co., Maanshan, China, under the trade designation "Y8000".
Although the glass microspheres available from Zeetan Industries, I.nc. under the trade designation "ZEEOSPHERES 200" are referred to in UK Pat. Appi. G, published August 31 , 1989, as hollow, glass microspheres,, such microspheres are thick-wailed beads typically haying a density of about. 2.5 g ce. Therefore, such glass microspheres are not capable of providing a composition according to the present disclosure having a density of less than 0.8 g/ec.
The hollow glass microspheres are present in the composition disclosed herein at a level of at least 10 percent by weight, based on the total weight of the composition. In some embodiments, the hollow glass microspheres are present in the composition at least at 10, 15, or 20 percent by weight based Oil the total weight of the composition . In some embodiments, the hollow glass microspheres are present in the composition at a level of up to 35, 30. or 25 percent by weight, based on the total weight of the composition. For example, the hollow glass microspheres may be present in th composition in a range from 1 to 35, 15 to 35, or 20 to 35 percent by weight based on the total weight of the composition.
The composition according to the present disclosure, including the PMP and the hollow glas omicrospheres, has a density of less than 0.8 -g cc In some embodiments, the composition has a density of up to 0.79 g cc, .0.78 g cc, 0.77 g/ee, 0,76 g ec, or 0,75 g/ce. Typically the composition has a density- of at least 0,65 g/cc, 0.66. g cc, or 0.67 g/cc. The compositions may have a density in a range, for example, from 0.65 g cc to 0.79 g/ec, 0.65 g/ce to 0.75 g/cc, or 0.67 g/ec to 0.75 g cc.
Typically, and surprisingly, in some embodiments, compositions, according to the present disclosure an isostatic pressure resistance with l ess than five · percent - volume loss at least twice the isostaiie pressure at which, ten percent by volume of the ollow glass microspheres collapses, in. some embodiments, the isostatic pressure .resistance with less than five percent volume loss of the corn-position disclosed herein is more than twice or 2.5 times the isostatic pressure at- which ten percent by volume of the hollow glass microspheres collapses. Compositions with an isostatsc pressure- resistance greater than the isostatic crush strength of the hollow- glass microspheres is even possible when the hollow glass microspheres are present in an amount of about '30 percent by weight, or about 40 percent by volume, or more, based on the weight or volume of the composit ion. As shown in the Examples, below, the composite of Example 3 resists greater than 170 MPa of isostatic pressure without any volume loss with more than 90% hollow glass microsphere survival. Since the isostatic crush strength of the. hollow glass microsphere used in Example 3 is around i 10 MPA for 90% survival, It is 'believed the PMP matrix reinforces the composite and -increases the compressive isostatic pressure resistance. In some embodiments, the composition according to the present disclosure further comprises a polyolefin compatibl!zer modified with polar functional groups. Suitable compatibiiizers include those made from monomers having the general structure CH;&=CH !&), wherein Rfe a hydrogen or alkyl. In some embodiments, Rso having up to 10 carbon atoms or from one to six carbon atoms. The repealing units of such poiyolefms would have the general formula ~[CH2~CHRia]-, wherein RU1 is defined as In any of the aforementioned embodiments. Examples of suitable polyolefln backbones for the compatibilizer
poly (!-butene); poly (3- poly {4-rnethylpen.tene); copolymers of ethylene with propylene. 1 -h ieoe, 1-hexene, 1 -octene,. f-decene, 4-meth.yi-l-pentene, and i- and blends of polyethylene and polypropylene. Typically, the compaiibilizer is based on at least one of a polyethylene or polypropylene backbone, ft should be understood that a polyoleiirs comprising polyethylene may be a polyethylene homopolymer or a copolymer containing ethylene repeating units. Similarly, it should be understood that a poiyolefin comprising polypropylene may be a polypropylene homopolymer or a copolymer containing propylene repeating units. The poiyolefin eompatibilizer may also be part a blend of different poiyolefms that includes at least one of polypropylene or polyethylene. The compatibiizer also Includes repeating units modified, with polar functional groups. In some embodiments,, the polar functional groups include ma!eie anhydride, carboxy!ie acid groups, and hydroxy! groups,. In some embodiments, the-.compatibUizer is a male ic anhydride-modified poiyolefin (e.g., am.aleic anhydride- modified polypropylene or maieic anhydride-modified polyethylene). In some embodiments, eompatibilizer Is present in the compos ition in an amount -greater than two percent, based on. the total weight of the composition, in some- embodiments, co patibi-lizsr is present in the composition -in amount o at: least 2.5, 3, or 3.5 percent based on the total weight of the composition, in some embodiments, cpr<<patibi!i 3/4 er is present in the composition in amount of up to 4 or 5 percent, based on the total weight of the composition.
in some embodiments, the composition according to the present disclosure .further comprises an Impact modifier. In some embodiments, the impact modifier also is a polyoiefm, is. chemically non-crossHnked, and is free of polar functional groups. For example, the impact modifier is free of any of the polar functional groups described above in .connection with the comp&tibilizer. In some embodiments, the impact modifier incl udes on ly carbon-carbon -.and -carbon-hydrogen bonds. In some embodiments, the polyoiefm impact modifier is an ethylene propylene elastomer, an ethylene octene elastomer, an ethylene propylene diene elastomer, an ethylene propylene octene elastomer, polybutadiene, a butadiene copolymer, polybutene, or a combination thereof, in some embodiments, the polyolefln impact modifier is an ethylene octene elastomer.
The impact modifier may be selected to have a relatively low viscosity as measured by melt flow index. A combination of impact' modifiers having different melt flow indexes may also be useful, in some embodiments, at least one of the polyoiefm impact modifiers has a melt flow index at 190 *C and 2, 16 kilograms of at .least 10 grams per 10 minutes (in some embodiments,, at least 1 1. 12, or 13 grams per 10 minutes). The melt flow index of tli impact modifiers b measured by ASTM DI238 - 13 : Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastomeier.
Other common types of Impact modifiers such as gro nd rubber, core-shell particles, f octionafized elastomers available, for example, from Dow Chemical Company, Midland, ML under the trade designation "AMPLIFY G.R-216", and particles available, for example, from Akzo Nobel Amsterdam, The Netherlands, under the trade designation "EXPANCEL" are at least one of ehenucal!y crosslinked or functionalked. However, many of these impact modifiers increase the viscosity of a -composition, making the composition less suitable for some polymer processing techniques (e.g., injection molding). In addition, "EXPANCEL" particles and similar particles require more strict thermal control and more precise handling than the polyolefin impact modifiers described herein., which ca present challenges during processing.
The impact modifier can be added to the composition according to the present disclosure in an amount sufficient to improve the impact strength of the composition, in some embodiments, impact modifier is present in the composition in a range from .10 percent to 20 percent, based on the total weight of the composition, in some embodiments, impact modifier is present in the composition in amount of at least 14, 15, or 16 percent and up to about 20 percent, based on the iota! weight of the composition.
Typically, in some embodiments in which the composition according to the present disclosure further comprises, an impact modifier and polyolefin compatibilizer modified with polar functional ogroups, the composition has an- isostatic pressure resistance with at least 25 percent volume loss substantially the same as the 'isostatic pressure at which ten percent. y volume of the hollow glass microspheres collapses. When si is said that the isostatic .pressure -resistance: is substantially the same as- he isostatic pressure at hich the hollow glass microspheres collapse, it means that the isostatic pressure 'resistance can be within H)%, 5%, 2.5%, r 1% of the isostatic pressure at. which the hollow glass microspheres collapse. In these embodiments, the volume loss of at least 25 percent typically occurs in a narrow pressure range, for example, a range of 14 MPa, ? MPa, 4 MPa, or 3 MFa. The Isostatic pressure resistance with at least 25 percent volume loss can occur in any .range described above for the collapse strength of the hollow glass microspheres described above. A useful isostatic pressure resistance may be in a range, for example, between 100 MPa and 140 MPa. Advantageously, the threshold isostatic pressure at which a composition exhibits quick volume loss may be tailored as desired for a particular application by selection of hollow glass microspheres and the addition of any compatibilizer and impact modifier.
The composition according to the present disclosure and/or useful for practicing the method disclosed herein, which includes PMP, the hollow glass microspheres, and optionally the
compatibilizer and impact modifier as described above in any of their embodiments has a melt flow index thai renders it suitable for injection molding. Typically, the composition, has a melt flow index at 190 "C and 2.16 kilograms of at least 5 grams pe 10 minutes (in some embodiments, at least 10, 15, 20. 25:, 30, 35, 40. or 50 grams per 10 minutes). The melt flow index of the composition is measured by AST Dl 238 - 13 : Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer.
Compositions according to the present disclosure are suitable for injection molding.
Accordingly, the present disclosure provides a method of making an article by injection molding of a composition disclosed herein. Elevated temperatures (e.g., in a range from 100 °C to 225 °C& may be useful for mixing the components of the composition in an extruder, in some embodiments, hollow glass microspheres may be added to the composition alter the pol olefin, compatilizer. and impact modifier are combined. The method of injection molding the composition disclosed herein can utilize any type of injection molding equipment, generally including a material hopper (e.g., barrel), a plunger (e.g., injection ram or screw-type), and a heating unit.
in some embodiments, the PMP in the composition according to the present disclosure is niicroceliu!ar. This means the PMP is porous. The terns "nncr celhdar" typically refers to. pore sizes from 9.1 .micrometer to 300 micrometers. In some embodiments, the articles formed from the mjcroceiia!ar compositions exhibit pore sizes in a range from 0.1 micrometer to 200 micrometers, in some embodiments, in a range from O. i micrometer to 100 micrometers or, in some embodiments, in a range from 0.1 micrometer to 30 micrometers, Providing PMP can be achieved, for example, through controlled use of a fluid in its supercritical state during extrusion or injection, molding of a composition disclosed herein. The term "supercritical 'fluid" refers to any substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist. Useful fluids may include CO2,
water, and argon.
in some embodiments, the method of making an article disclosed herein includes feeding the composition disclosed herein into a niierccellular foam injection molding machine, injecting a supercritical fluid into the composition, blending the composition arid the supercritical fluid at high pressure to form a blend, and injecting the blend into a molding tool. In some embodiments, the supercritical fluid is essentially CX 3/4
or ? in its 'supercritical fluid state.
The creation of the single-phase solution, in which the supercritical fluid is fully dissolved and uniformly dispersed in the molten polymer, in some embodiments, takes place inside the injection barrel under carefully controlled process conditions. The supercritical fluid may be mass flow metered into the polymer for a fixed amount of time. During that dosing period, the right conditions of temperature, pressure and shear are established within the barrel. Back-pressure, screw-speed and barrel-temperature control, as well as the geometry of the mixing screw and supercritical fluid injector, all play a role in establishing the process conditions that create the single-phase solution. To impart a microcellular structure to molded parts, the raicroceiloiar foaming process typically relies on the homogeneous eel! n cleation that occurs when a single-phase solution of polymer and supercritical fluid passes through an injection gate and into a mold cavity. The addition of supercritical fluid to the molten polymer pressurizes the solution, and the pressure drop as the solution enters the mold allows the supercritical fluid to create cell nuclei. The ceils then grow until the material fills the mold, the expansion capabilities of the supercritical fluid are expended, or the flow front freezes.
An apparatus for making a mierocellular composition may be, for instance, a "MUCELL" enabled injection molding machine available, for example, from Eagle, Guelph, Ontario, Canada. "MUCELL" is a registered trademark ofTrexel, Inc., Wilmington, Mass.
Further details about composite materials comprising hallow glass microspheres and a microceHular thermoplastic resin and methods of making them can be found in Int. Pat. AppK Pub. No. WO (Quaes et al.).
In some embodiments of the composition according to the present disclosure, the hollow glass microspheres may be treated with a coupling agent to enhance the interaction between the hollow glass microspheres and the po!yoiefm matrix. In other embodiments, a coupling agent can be added directly to the composition. Examples of useful coupling agents include zireonates,, si lanes, or tiiaoates. Typical titanate and zireonate coupling agents are known to those skilled in the art and a detailed overview of the uses and selection criteria for these materials: can be found in Monte. S.J., enrich Petrochemicals, Inc., "Ken-React(R) Reference Manual - Titanate, Zireonate and Ahiminate Coupling Agents", Third Revised -Edition, March, S 995. if 'used, coupling agents are commonly included in an amount of about 1% to 3% by weight, based on the total weight of the hollow glass microspheres in the composition.
Suitable sHanes are coupled to glass surfaces through condensation -reactions to form sifoxa-ne linkages with the siliceous glass. This treatment renders the filler more wet-able or promotes the adhesion of materials to the hollow glass microsphere surface. This provides a mechanism to bring about covalent, ionic or dipo!e bonding between hollow glass microspheres and organic matrices. Si lane, coupling, agents are chosen based oft the particular functionalit desired. Another approach to achieving Intimate hollow glass mkrosphere~po!ynier interactions Is to functkma!ize the surface of microsphere with a suitable coupling agent that contains a po!ymerizable moiety, thus Incorporating the material directly into the polymer backbone. Examples of pofymerizable moieties are materials that contain olefink functionality such as siyrenic, vinyl (e.g., vtnyltriethoxysHane, vinyitri(2- roethoxyethoxy) silane), acrylic and methacrylic moieties (e.g.,. 3- metacrylroxypropyltrimethoxysiiaae). Examples of useful silanes that may participate in
vulcanization crossHnking include 3-mercaptopropyltrimedioxysilane,
bis(triethoxysjlipropyl)tetrasulfane (e.g., available under the trade designation "Si-6'9" from Evonik industries, Wesseling, Germany), and thiocyanatopro yhrieihoxysiiane. Still other useful silane coupling agents may have amino functional groups (e.g., N-2<<(aminoethyI)-3- aminopropyitrimethoxysilane and (3^minopropyf)trimethoxysilane). Coupling agents useful for peroxide-cured rubber compositions typically include vinyl silanes. Coupling agents usefiil for sulfiir- cured rubber compositions typically include mereapto or polysulfido silanes. Suitable silane coupling strategies are outlined in Silane Coupling Agents: Connecting Across Boundaries, by Barry Arkles, pg 165 - 189, Gelest Catalog 3000-A Silanes and Silicones: Gelest inc. Morrisviile, PA,
Although coupling agents are useful in some embodiments, advantageously, the compositions according to the present disclosure provide good mechanical properties even in the absence of coupling agents. Accordingly, in some" embodiments, the hollow glass microspheres in the compositions according to the present disclosure are not treated with a silane coupling agent.
In some embodiments, the composition according to and/or useful in the method according to the present disclosure includes one or more stabi lizers (e.g., antioxidants or hindered amine light stabilizers (HALS)). Examples of useful antioxidants include hindered phenol-based compounds and phosphoric acid ester-based compounds (e.g., those available from BASF, Fiorham Park, N J, under the trade designations "IRGANOX" and "IRGAFOS" such as "'I GANOX 1076" and "IRGAFOS 168", those available- rom Songwon Ind. Co, U!san, Korea, .under the trade designations
"SO GNOX", and butyiated hydroxyteluene (BHT)). Antioxidants, when used, can be present in an amount from about 0.00! to- 1 percent by weight based on the total weight of the composition ., HALS are typically compounds that 'can scavenge .free-radicals, which can result from photodegradation or other degradation processes. Suitable HALS include decanedioic acid, bis (2,256,6^etnanethyl 1- - &octyl.oxy)- -piperidmy!)esier. Suitable HALS include those available, for example, from BASF under the trade .designations- "Ti UVIN" and "CH ASSORB". Such compounds, when used, can be present in an amount from about 0,001 to 1 percent by weight based on the total weight of the composition.
Reinforcing filler may be useful in the composition according to and/or useful in the method according to the presen disclosure. Reinforcing filler c n be useful, for example, for enhancing the tensile, ilexural, and/or impact strength of the composition. 'Examples of useful reinforcing fillers include silica (including aanosiliea), other metal oxides, metal hydroxides, and carbon black. Other useful fillers include glass fiber, woHastonite, talc, calcium carbonate, titanium dioxide (including nano-titanium dioxide), wood flour, other natural fillers and fibers (e.g., walnut shells, hemp, and com silks), and clay (including nano-c ay).
However, in some embodiments, the presence of silica in the composition according to the present disclosure ears lead to an undesirable increase in the density of the composition.
Advantageously, the compositions according to the present disclosure and/or useful in the methods according to the present disclosure provide good mechanical properties even in the absence of reinforcing fillers. As shown In the Examples, below, it has been found that compositions disclosed oherein have high tensile, flexural, and impact strength even in the absence of silica filler or other reinforcing tiller. Accordingly, in some embodiments, the composition is free of reinforcing filler or contains op to 5 , , 3, 2, or 1 percent by weight reinforcing filler, based on the total weight of the composition.
Other additives may be incorporated into the composition disclosed herein in any of the embodiments described above. Examples of oilier additives that may be useful, depending on the intended use of the composition, include preservatives, mixing agents, colorants, dispersants, floating or anti-setting agents, flow or processing agents, wetting agents, anti-ozorsant, and odor scavengers.
The composition and method according to the present disclosure are useful for making low density articles (e.g., having a density in a range from 0.65 g/cc to Θ.79 g/cc, 0.6S g cc. to 0.75 g/cc, or 0,67 g/cc to 0.75 g/cc),
In some embodiments, the article according to the present disclosure, is useful as a proppant for a 'fracturing and propping operation on a gas or oil well. Typically, a proppant is spherical with a size in a range from 100 micrometers to 3000 micrometers (i.e., about 140 'mesh to about 5 mesh (ANSI)) (in some embodiments, m a range -from 1000 micrometers to 3000 micrometers, 1.000 micrometers to 2000 micrometers, 1000 micrometers to 1700.micrometers (I.e., about 18 mesh to about 12 mesh), 850 micrometers to 1700 micrometers (i.e., about 20 mesh to about 12 mesh), 850 micrometers to 1200 micrometers (i.e., about 20 mesh to about 16 mesh), 6.00· micrometers to 1200 micrometers (i.e., about 30 mesh to about 16 mesh), 425 micrometers to 850 micrometers ( .e.. 'about 40 mesh to about 20.mesh), or 300 micrometers to 600 micrometers (i.e., about 50 mesh to about 30 mesh). The size of the proppant articles desired may depend, for example, on the characteristics of a subterranean formation selected for a fracturing and propping operation.
For an article according to- the present disclosure that is spherical, the article will typically meet or exceed the standard's for sphericity and roundness as measured according to American
Petroleum institute Method RP56, "Recommended. Practices for Testing Sand Used in Hydraulic Fracturing Operations", Section 5, (Second Ed., 1 9S) (referred, to herein as "API P 56"). As used herein, the terms "sphericity" and "roundness" are -defined as described in' the API RP's and 'can be determined using the procedures' set forth in the API RP's. in some embodiments, the sphericity of the article disclosed herein is si least 0.6 (in some embodiments, at least 0.7, 0.8, or 0.9). in some embodiments, the roundness of the article is at least 0.6 (in some embodiments, at least 0.7. 0.8, or 0.9).
it may be useful to mix the proppant articles disclosed herein and other particles. The other particles may be con ventional proppant materials such as at least one of sand, resin-coated sand, graded nut shells, resin-coated nut shells, sintered bauxite, particulate ceramic materials, glass beads, and particulate thermoplastic materials. Sand particles are available, for example, from Badger Mining Corp., Berlin, Wl; Borden Chemical, Columbus, OH; Fairmont Minerals, Chardon, OH. Thermoplastic particles are available, for example, from the Dow Chemical Company, Midland, M.I: and Baker Hughes, Houston, XX. Clay-based particles are available, for example, from
CarboCeramics, Irving, TX; and Saint-Gobain, Courbevoie, France. Sintered bauxite ceramic particles are available, for example, from Borovichi Refractories, Borovichi, R 3M Company, St. Paul, MN; CarboC and Saint Gobaio.. Glass beads are available, for example, from Diversified Industries, Sidney, British Columbia, C and 3M Company. Generally, the sizes of other particles may be in any of the size ranges described above for the plurality of proppant particles disclosed herein. Mixing other particles (e.g., sand) and the plurality of particles disclosed herein may he useful, for example, for reducing the cost of proppant particles while maintaining at least some of the beneficial properties of the proppant articles disclosed herein.
In some embodiments, the proppant articles disclosed herein are dispersed in. a fluid. The fluid may be a carrier fluid useful, for example, for depositing proppant articles into a f acture. A variety of aqueous and non-aqueous carrier fluids can be used with the proppant articles disclosed herein, to some embodiments, the fluid comprises at least one of water, a brine, an alcohol, carbon dioxide (e.g., gaseous, liquid, or supercritical carbon dioxide), nitrogen gas, or a hydrocarbon, in some embodiments, the fluid further comprises at least one of a surfactant, Theological modifier, salt, gelling agent, breaker, scale inhibitor,, dispersed gas, or other particles.
Illustrative examples of suitable aqueous fluids and brines- include fresh water, sea water, sodium chloride brines, ea!e sum chloride brines, potassium chloride brines, sodium bromide brines, calcium bromide brines, -potassium bromide brines, zinc bromide brines, ammonium chloride brines, tetramethyl ammonium chloride brines, sodium formate 'brines, -potassium formate brines, cesium oformate brines, -and any- combination thereof. Rheological modifiers may be added to a ueous fluid to modify the flow characteristics of the fluid, for example, 'Illustrative examples of suitable water- soluble polymers that can be added to aqueous fluids include guar and guar derivatives: such as hydroxypropyi guar (HPG), carboxymethylhydroxyprppyl .guar (CMHPG), carboxymethyl guar (CMG), hydroxyethyl cellulose (HEC), carboxymetby!hydroxyethyl cellulose (CMHEC), carboxymethyl cellulose- (CMC), 'starch based polymers, xanthan based polymers, and biopolymers such as gum Arabic, carrageenan, as well as any combination thereof. Such polymers may crosslink under downhole conditions. As the polymer undergoes hydration and erossi inking, the viscosity -of the fluid increases, which may render the fluid more capable of carrying the proppant. Another class of Theological modifier Is viscoeiastic surfactants ("VES's").
Examples of suitable non-aqueous fl uids useful for practicing the present disclosure include alcohols (e.g., methanol, ethanoL isopropanoi, and other branched and l inear alkyl alcohols); condensat refined hydrocarbons (e.g., gasoline, naphthalenes, xylenes, toluene and toluene derivatives, hexanes, pentanes, and ligroin); gases (e.g., carbon dioxide and nitrogen gas); l supercritical carbon,. and combinations thereof. Some hydrocarbons suitable for use as such fluids can be obtained, for example, from SynOil, Calgary, Alberta, Canada under the trade. designations "PLATINUM", "TG-74Q", "SF-770**, "SF-800", "SF-830", and "SF-840". Mixtures of the above nonaqueous fluids with water (e.g., mixtures of water and alcohol or several alcohols or mixtures of carbon dioxide (e.g., liquid carbon dioxide) and water) may also be useful for practicing the present disclosure. Mixtures can be made of miseible or immiscible fluids, Rheological modifiers (e.g., a phosphoric acid ester) can be useful in non-aqueous fiuids as well, in some of these embodiments, the fluid further comprises an activator (e.g., a source of polyvalent metal ions such as ferric sulfate, ferric chloride, aluminum chloride, sodium aluminaie, and aluminum isopropoxide) for the gellin agent.
Fluid containing proppant articles according to the present disclosure dispersed therein can also include ai least one breaker material (e.g., to reduce viscosity of the fluid once it is in the well). Examples of suitable breaker materials include enzymes, oxidative breakers (e.g., ammonium peroxydisulfate), encapsulated breakers such as encapsulated potassium persutfate (e.g., available, for example, under the trade designation "ULTRAPB M CRB" or ^SUPERULTRAPERM CR8 from Baker Hughes), and breakers described in ?. S. Pat No. 7,066,262 (Funkhouser).
Fluids having proppant articles according to the present disclosure dispersed therein may also be foamed. Foamed fluids may contain* for example, nitrogen, carbon dioxide, or mixtures thereof at volume fractions ranging from 10% to 90% of the total fluid volume.
The fluids described above, in any of their embodiments,, may be useful, for example, for practicing the method of fracturing a subterranean geological formation penetrated by a welibore according to the present disclosure. Techniques for fracturing subterranean geological formations comprising hydrocarbons are known in the art, as are techni ues for introducing proppaats into the .fractured formation to prop open fracture openings, In some methods, a fracturing fluid is injected into the subterranean geological, formation at rates and pressures sufficient to open a fracture therein. When injected at the high pressures exceeding fee rock strength, the fracturing fluid opens a fracture in the rock. The fracturing fluid may be an aqueous or non-aqueou fluid having any of the additives described above. Proppant articles described herein can be included in the fractoring fluid. That is, in some embodiments, injecting the fracturing fluid and introducing the proppant articles are carried out simultaneously, in other embodiments, the proppant articles disclosed herein may be present in a second fluid (described in any of the above embodiments) that is introduced into the well after the fracturing fluid is introduced. As used herein, the term "introducing" (and its variants "introduced'1, etc.) includes pumping, injecting, pouring, releasing, displacing, spotting, circulating, or otherwise placing a fluid or material (e.g., proppant articles) within a well, welibore, fracture or subterranean formation using any -suitable manner known in fee art. The proppant. articles according to the present disclosure can serve to bold the walls of the fracture apart after the pumping has stopped and the fracturing fluid has leaked off or flowed back. The proppant articles according to the present disclosure may also be useful, for example, in fractures produced by etching (e.g., acid etching). Fracturing may be carried out at a depth, for example, k a range from 500 to 8000 meters, 1000 to 7500 meters, 2500 to 7000 meters, or 2500 to 6000 meters.
Compositions according to the present disclosure may also be useful as syntactic foams for insulation in a variety of applications, for example, for wet insulation applications (i.e., insulation that is exposed to sea water) for off-shore oil pipelines or flowlines. In some embodiments of the article disclosed herein, the article comprises a conduit, which may be surrounded by a composition disclosed herein or contain the composition within, in some embodiments, the conduit is submerged in water (including in an ocean, sea, bay, gulf, lake, or river) at a. depth of at least 100 meters (in some embodiments, at least 500 meters, 1000 meters, 1500 meters, 2000 meters, 2500 meters, 3000 meters, or even at least 3500 meters). The conduit may also contain a least oil within. Examples of structures that may be insulated by a- composition aecording to the present disclosure include conduits', production trees, manifolds, and jumpers,, which can be used, for example, in underwater
environments- (e.g., submerged in the ocean). Low densit articles, which may be spherical, made from the compositions disclosed herein may also be used m connection with any of these -structures For deep water buoyancy. These ma be useful, for example, for plugging a flow!ine at a certain depth.
Articles according to the present disclosure, whic may be spherical, may also be useful as di verier - bails for a variety of oil and gas well completion, well workover, and intervention
applications. Di verier bails may be useful, for example, for sealing perforations in a formation that are. accepting the most treatment fluid so that reservoir treatments can be di verted to other targeted portions of the hydrocarbon-bearing formation. Diverter balls used in connection with hydraulic fracturing may also be called frac bails.
.Embodiments, of the compositions disclosed herein that exhibit quick volume loss above, a. threshold isostatie pressure may be useful as syntactic foams- for deep offshore oil well construction applications for control of annular pressure build-up with a wellbore. Using PMP and an appropriate selection of hollow glass microspheres and any compaiibiHzer and impact: modifier, the threshold s'sostatic pressure -at wh ch a compositio exhibits quick volume loss may be tailored -as desired for a particu far app \ \ cats on .
Some .Embodi ents^^
In a first embodiment, the present disclosure provides a. composition comprising:
poly(4<<roethy !pemv 1 -ene); and
hollow glass microspheres,
wherein the composition has a density of less than 0,8 grams per cubic centimeter. in a second embodiment, the present disclosure provides the composition of the first embodiment, wherein the hollow glass microspheres have an average true density less than 0.5 grams per cubic centimeter.
In a third embodiment, the present disclosure provides the composition of the first or second embodiment, comprising at least twenty-five percent by weight of the hollow glass microspheres, based on the total weight of the composition.
in a fourth embodiment, the present disclosure provides the composition of any one of the first to third embodiments, wherein the composition has a density of up to 0.75 grams per cubic centimeter.
In a fifth embodiment, the present disclosure provides the composition of an one of the firs to fourth embodiments, wherein a isostatic pressure at which ten percent by volume of the hollow glass microspheres collapses is in a range from shout 70 megapascals to about 250 megapascais.
Irs a sixth embodiment, the present disclosure provides the composition of any one of the first to fifth embodiments, having an isosiatic -pressure resistance with less than five percent volume loss more than double the isostatic pressure at which ten percent by volume of the hollow ceramic microspheres collapses,
in a seventh embodiment, the present disclosure provides the composition of any one of the first to fifth embodiments, further comprising a polyo!efm impact modifier that is chemically non- crosslmked and free of polar functional groups.
In an eighth, embodimen t, the present disclosure provides the composition of any one of the first to fifth or seventh embodiments,, further comprising a polyolefi eornpaiiblizer■modified with polar fun ional groups.
In a ninth embodiment, the present di sclosure provides the composition of the eighth embodiment, wherein the composition comprises an impact -modifier, wherein th composition has an isostatic pressure resistance with greater than 25 percent volume loss substantially the same as the isostatic pressure at which ten percent by volume of the hollow glass microspheres collapses.
in a tenth embodiment, the present disclosure provides the composition -any one of the first to ninth embodiments, wherein the impact modifier is an. ethylene propylene elastomer, an ethylene oetene- elastomer, .an ethylene propylene diene elastomer, an ethylene propylene octene elastomer, or a combination thereof, and wherein the eompatibilizer is a ma!eic anhydride-modified polyolefin.
In an eleventh embodiment, the present disclosure provides the composition of any one of the first to tenth embodiments, wherein the po!y(methyl pentene) is microceliular.
fc.a twelfth embodiment the present disclosure provides an article comprising a solidified composition of any one of the first to eleventh embodiments.
In a thirteenth embodiment, the present disclosure provides the article of the twelfth embodiment, wherein the article is spherical. in a fourteenth embodiment, the presen t disclosure provides the article of the thirteenth embodiment, wherein the article is a propp&ra.
In a fifteenth embodiment, the present disclosure provides the articl of the thirteenth embodiment, wherein -the article is a buoyancy device.
In a sixteenth embodiment, th present disclosure provides a conduit comprising the article of any one of the twelfth to fifteenth embodiments within.
In a seventeenth embodiment, the present disclosure provides the conduit of the sixteenth embodiment, further comprising oil within.
In an eighteenth embodiment, the presen t disclosure pro vides the conduit of the sixteenth or seventeenth embodiment, submerged at. a depth of at least 1 0 meters.
in a ni neteenth embodiment, the present disclosure provides a method of making an article, the method comprising injection molding the composition of any one of the First to eleventh, embodiments to make the article.
in a twentieth embodiment, the present disclosure provides the method of the nineteenth embodiment, further comprising feeding the composition into a microcellis!ar foam injec
injecting a supercritical fluid
blending the composition md the supercritical fluid at high pres an
injecting the blend into a molding too!,
Tn a twent -first embodiment, the present disclosure provides a method of fracturing a subterranean geological formation penetrated by a wellbore, the method comprising:
injecting into 'the wellbore penetrating the subterranean geological formation a fracturing fluid at rate and pressure sufficient to for and
introducing into the fracture a p l urality of articles according to the twelfth or thirteenth embodiment.
In a twenty-second embodiment,: the present disclosure provides a method according to the twenty-first .embodiment, wherein injecting the fracturing fluid and introducing the plurality of articles are carried out simultaneously, and wherein, the fracturing fluid comprises the plurality of articles.
In a twenty-third embodiment, the .present disclosure provides a method according to the twenty-first or twenty-second embodiment, wherein the fracturing is carried out at a depth of at least 500 meters.
In a twenty-fourth embodiment the present disclosure provides a hydrocarbon-bearing formation penetrated by a wellbore, wherein the hydrocarbon-bearing formation comprises a fracture, and wherein the .fracture includes an article of the twelfth or thirteenth embodiment within. The following specific, but non-limiting, examples will serve to illustrate the invention. In these examples, ll amounts are expressed in pasts per hundred resisi (phr) unless specified otherwise, in these examples, N M means "not measured".
Table 1 :Materiais
Compound ing Procedure
Samples were compounded in a co-rotating interraeshmg I inch twin screw extruder (L/D: 25) equipped with 7 heating zones. Polymer pellets (PMP or PP) alone or in the presence of the impact modifier and compatibilizer were dry blended and fed in zone 1 via a resin feeder and then passed through a set of kneading blocks and conveying elements. The extrudate was cooled in a water bath and pelktized. Glass bubbles were side fed downstream in zone 4. At the point of glass bubble side feeding as well as for the res of the downstream processing, high channel depth conveying elements (OD/!D: 1.75) were used. For polypropylene, the temperature in zone I was set to 200°C and all other zones to 220°C, For PMP, zone ] was set to 260°C and all others were set to 300 °C respectively. When impact modifier was used in the formulation, zone 1 temperature was decreased down to 150°C to prevent build-up of rubber on the extruder Met zone. The screw rotation speed was set to 250 rpm in both PP and PMP cases. The extrudate was cooled in a water bath and peUetized. gc ia MoMm Procedure
All samples were molded using a BOY22D injection molding mach ne with a 28mm general purpose barrel and screw manufactured by Boy Machines Inc., Exion, PA, A standard ASTM mold wish cavities for tensile, flex and impact bar was used for ail molded parts. The injection molded specimens were kept on a lab bench at room temperature..and under ambient conditions for at least 36 hours before perform ing any testing.
Density of the molded parts was determined using the following procedure. First, the molded parts were exposed to high temperature in an oven (Naberiherm(R) N300/14) in order to volatilize the polymer resin. The oven was set with a temperature ram profile to run from 200°C to 550 °C in 5 hours. After the temperature reached 550 °C>> it was kept constant for 12 hours. Weigh percent of glass bubbles was calculated from the known amounts of molded part before and after burn process using below equation.
Weight % of Glass Bubbles = (Weight -of Residual inorganics After Burn) / (Weight of Molded Material Before Burn) xl OO
We then determine the -density of ihe glass bubble residue doe-res) using a helium gas pycnometer, AccuPcy 1 330 from M-ieromerities.
Finally, the molded pari density is calculated from the known weight percent of glass bubble residue (W%. G8), weight percent of polymer phase (l-w%GB), the density of glass bubble residue (O K*) and the known polymer density (d from supplier datasheet
Dm <<Kro ^(.
3/4 ^ breaks (g cc) was also calculated, assuming initial density of GBs used as the dc,B-res value.
The amount of volume loss due to bubble breakage after compounding and injection molding (%Vol Loss in process) was calculated from the known density of the glass bubble residue (das-re*), the initial density of GBs (doB-imsiai) ,density of solid glass (2.54 g/cc) and using equation below. %Vol loss in process = Mechanical properties of the injection-molded composites were measured using ASTM standard test methods listed in Tabic 2, An MTS frame with a SkN load ceil and tensile and 3 point bending grips were ased for tensile and ilexural properties, respectively. Jo tensile testing mode, the test procedure described in ASTM D-638-10 standard was followed., however no strain gauge was used, and instead, grip .separation distance was used to determine the sample elongation. Troias Olsen model IT503 impact tester and its specimen noteher were used to measure room temperature Notched Ixod impact strength of the molded pans, A Tinius Olsen MP200 extrusion plastometer was used for inch: flow index testing on samples. At least 5 different specimens from a given sample were tested in all tensile, f!exural, and impact tests. Arithmetic average of the results were determined and reported in the following examples. The results were observed to be highly repeatahle and the standard deviation in test results was observed to be in the range of 3-5% or lower. At least two different specimens were tested in melt flow index tests. The melt flow tests were observed to be highly repeatabie with almost identical experimental results, Arithmetic average of the results were determined and reported in the following examples.
Table 2 Propert Test Methods
Test (Unit) Abbr. AST # j Tensile Modulus (MPa) ( 3/4
20 XI TM D-63J 0 j Tensile Strength at yield (MPa) @ 20 X j TS D-63S-10
Elongation at break (%) EL D-638-10 j Notched Izod Impact @ °2QC (j/m) ! .? D-256-10 j
F!exural Modulus (MPa) 1 FM 13-790-10 j
F!exural Strength at yield (MPa) FS D-.7 0-10
Melt Flow Index D- 1238- 13 j
Bulk isostatic compression testing of .injection Molded Parts
In this test, the molded plastic part is exposed to high isostatic pressure. The molded plastic part is placed directly into the oil containing pressure chamber. Therefore, the working pressure around the GBs is the plastic resin which in turn is pressurized by the surrounding oil. Hie amount of plastic part that is put in the pressure chamber contains■-■ 10 ml of GBs,
Once the sample is in the pressure chamber, it is pressurized to a predetermined pressure while recording both pressure and volume. This process is repeated to get a second set of pressure- volume data, and both data sets are plotted, as pressure vs. volume (P vs. V) curves. The Initial pressurizaiion is known as the collapse curve (P versus V I ), and the second pressurization provides the system compression curve (P versus V2). The two curves are used to determine the percentage of collapsed GSs in the test. ela se
VT refers to the total volume collapse calculated by the difference in the collapse and compression curve values ai zero pressure.
VT = Vtosai (p. !)
Vp is the void volume collapsed at that pressure and is calculated by
where Υ ·(Ρ) and V^ ) are the volume values of the compression and collapse curves, respectively, a the pressure of in res
Since the interior glass bubble void space is the major contributor to volume loss in the process of molded bar pre-ssurization, the o iginai volume (Vv) of the glass bubble interior void space in the molded part is found by subtracting the volume of the wall material (Vm) from the 'volume occupied by the GBs ν ) m the molded part. "v ~ Vap - Vm
Then, the percent volume survival (V survival at. pressure P is found as (V, (?) - V2(P)V (Vap - V,,,}] in our examples, a tangent is drawn to the volume loss curve and the pressure value at the midpoint of the tangent is taken as the pressure point. at which considerable volume loss occurs. This is shown in PIGS. I and 2, with FIG. I exhibiting a more gradual volume loss compared to that in FIG. 2 where the volume loss happens more instantly and at a higher pressure value. Comparative Example A and 'Examples 1-4 Solid Syntactic Poiymethyipetitene Formulations Table 3 Solid Syntactic Polymethyiperiiene Formulations The PMP/GB 1 composite syntactic -material of EX3 exhibits 25000 PSI isostaiic pressure without any volume loss with more than 90% glass bubble survival Since G 1 isostaiic crush strength is around 16000 PSI at 90% survival, this shows that die PMP matrix reinforces the composite and increases the compressive isostaiic pressure resistance.
E.X4 was developed to improve the impact resistance of EX3 by introducing a combination of an impact modifier and a compaiibilizer. Note that the introduction of 20.9 wt% eiastomeric impact modifier softens the matrix and the composite isostaiic pressure resistance reduces to 16000 psi which is thai of the G81 itself. In other words, the glass bubble phase becomes the strength determining phase. 1 000 psi resistance at a density of 0.69 g/cc s still very useful for various oil and gas applications, in addition, EX4 exhibits very high MFI indicating easy flow for injection molding application.
Example 5 and Comparative Example B Supercritically Foamed Syntactic Poiymethylpentene
Formulations Another method of density reduction is ia supercritical foaming and combination of supercritical foaming- ith -glass- bubbles. CEA and EX! compounded materials were molded in a MuCe!i(R) enabled Engel injection molding machine (ES200/10OTL equipped with SCF system Model # TR.3.50O0G using CO2 as the- upercritical gas) to produce CBB and EX5, Table 2 compares supercritical l 'foamed material against nfoamed so id syntactic material. Note that the volume los in CBB ( supercritical iy foamed only) occurs at a much lower pressure after which, it stabilizes indicating that the ceils created by the supercritical foaming are totally compressed. EX5, on the other hand, contains bo glass bubbles and. supercritically foamed cells and the volume loss occurs at a ..higher