Patent Application
20150031838
Embodiments of the present disclosure generally relate to polymers mixed with metallic acrylate salts. Specifically, embodiments relate to polymers having improved properties.
Polymers may be used for applications such as foam extrusion, sheet extrusion/thermoforming, extrusion coating, pipe extrusion, blowing molding and blown films. It may be desirable in certain of these applications to increase the melt viscosity of the polymer, particularly at lower sheer stress.
An embodiment of the present disclosure includes a composition. The composition includes a polyolefin, a styrenic polymer, a polylactic acid or combinations thereof and a metallic acrylate salt.
Another embodiment of the present disclosure includes a method of making a composition. The method includes melt mixing a polyolefin, a styrenic polymer, a polylactic acid or combinations thereof with a metallic acrylate salt.
A detailed description will now be provided. The description includes specific embodiments, versions and examples, but the disclosure is not limited to these embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the disclosure when that information is combined with available information and technology.
Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition skilled persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing. Further, unless otherwise specified, all compounds described herein may be substituted or unsubstituted and the listing of compounds includes derivatives thereof.
Further, various ranges and/or numerical limitations may be expressly stated below. It should be recognized that unless stated otherwise, it is intended that endpoints are to be interchangeable. Further, any ranges include iterative ranges of like magnitude falling within the expressly stated ranges or limitations.
Polymers useful in this disclosure include polyolefins, including, but not limited to polyethylene and polypropylene, styrenic polymers, polylactic acids, and combinations thereof. The polymer can also include functionalized versions of the above, for instance maleated polypropylene.
Polyolefins useful in the present disclosure include, but are not limited to, linear low density polyethylene, elastomers, plastomers, high density polyethylenes, low density polyethylenes, medium density polyethylenes, polypropylene and polypropylene copolymers, for example.
Unless otherwise designated herein, all testing methods are the current methods at the time of filing. In one or more embodiments, olefin based polymers include propylene based polymers. As used herein, the term “propylene based” is used interchangeably with the terms “propylene polymer” or “polypropylene” and refers to a polymer having at least about 50 wt. %, or at least about 70 wt. %, or at least about 75 wt. %, or at least about 80 wt. %, or at least about 85 wt. % or at least about 90 wt. % polypropylene relative to the total weight of the polymer, for example.
In certain embodiments of the present disclosure, the polypropylene copolymer may be a “mini-random” polypropylene. A mini-random polypropylene has less than about 1.0 wt % of the comonomer. In certain embodiments, the comonomer in the mini-random polypropylene is ethylene. In other embodiments, the polypropylene may be, for instance, a propylene homopolymer, a propylene random copolymer, a propylene impact copolymer, a syndiotactic polypropylene, an isotactic polypropylene or an atactic polypropylene.
The propylene based polymers may have a molecular weight distribution (Mw/Mn) of from about 1.0 to about 50, or from about 1.5 to about 15 or from about 2 to about 12, for example.
The propylene based polymers may have a melting point (Tm) (as measured by DSC) of at least about 100° C., or from about 115° C. to about 175° C., for example.
The propylene based polymers may include about 15 wt. % or less, or about 12 wt. % or less, or about 10 wt. % or less, or about 6 wt. % or less, or about 5 wt. % or less or about 4 wt. % or less of xylene soluble material (XS), for example (as measured by ASTM D5492-06).
The propylene based polymers may have a melt flow rate (MFR) (as measured by ASTM D-1238) of from about 0.01 dg/min to about 2000 dg/min., or from about 0.01 dg/min. to about 100 dg/min., for example.
In one or more embodiments, the polymers include ethylene based polymers. As used herein, the term “ethylene based” is used interchangeably with the terms “ethylene polymer” or “polyethylene” and refers to a polymer having at least about 50 wt. %, or at least about 70 wt. %, or at least about 75 wt. %, or at least about 80 wt. %, or at least about 85 wt. % or at least about 90 wt. % polyethylene relative to the total weight of the polymer, for example.
The ethylene based polymers may have a density (as measured by ASTM D-792) of from about 0.86 g/cc to about 0.98 g/cc, or from about 0.88 g/cc to about 0.965 g/cc, or from about 0.90 g/cc to about 0.965 g/cc or from about 0.925 g/cc to about 0.97 g/cc, for example.
The ethylene based polymers may have a melt index (MI2) (as measured by ASTM D-1238) of from about 0.01 dg/min to about 1000 dg/min., or from about 0.01 dg/min. to about 25 dg/min., or from about 0.03 dg/min. to about 15 dg/min. or from about 0.05 dg/min. to about 10 dg/min, for example.
In one or more embodiments, the olefin based polymers include low density polyethylene. In one or more embodiments, the olefin based polymers include linear low density polyethylene. In one or more embodiments, the olefin based polymers include medium density polyethylene. As used herein, the term “medium density polyethylene” refers to ethylene based polymers having a density of from about 0.92 g/cc to about 0.94 g/cc or from about 0.926 g/cc to about 0.94 g/cc, for example.
In one or more embodiments, the olefin based polymers include high density polyethylene. As used herein, the term “high density polyethylene” refers to ethylene based polymers having a density of from about 0.94 g/cc to about 0.97 g/cc, for example.
Polylactic acids useful in the present disclosure include, for example, poly-L-lactide (PLLA), poly-D-lactide (PDLA), poly-LD-lactide (PDLLA) and combinations thereof. The polylactic acid may be formed by known methods, such as dehydration condensation of lactic acid (see, U.S. Pat. No. 5,310,865, which is incorporated by reference herein) or synthesis of a cyclic lactide from lactic acid followed by ring opening polymerization of the cyclic lactide (see, U.S. Pat. No. 2,758,987, which is incorporated by reference herein), for example. Such processes may utilize catalysts for polylactic acid formation, such as tin compounds (e.g., tin octylate), titanium compounds (e.g., tetraisopropyl titanate), zirconium compounds (e.g., zirconium isopropoxide), antimony compounds (e.g., antimony trioxide) or combinations thereof, for example.
The polylactic acid may have a density of from about 1.238 g/cc to about 1.265 g/cc, or from about 1.24 g/cc to about 1.26 g/cc or from about 1.245 g/cc to about 1.255 g/cc (as determined in accordance with ASTM D792), for example.
The polylactic acid may exhibit a melt index (210° C., 2.16 kg) of from about 5 g/10 min. to about 35 g/10 min., or from about 10 g/10 min. to about 30 g/10 min. or from about 10 g/10 min. to about 20 g/10 min (as determined in accordance with ASTM D1238), for example.
The polylactic acid may exhibit a crystalline melt temperature (Tm) of from about 150° C. to about 180° C., or from about 160° C. to about 175° C. or from about 160° C. to about 170° C. (as determined in accordance with ASTM D3418), for example.
The polylactic acid may exhibit a glass transition temperature of from about 45° C. to about 85° C., or from about 50° C. to about 80° C. or from about 55° C. to about 75° C. (as determined in accordance with ASTM D3417), for example.
The polylactic acid may exhibit a tensile yield strength of from about 4,000 psi to about 25,000 psi, or from about 5,000 psi to about 20,000 psi or from about 5,500 psi to about 20,000 psi (as determined in accordance with ASTM D638), for example.
The polylactic acid may exhibit a tensile elongation of from about 1.5% to about 10%, or from about 2% to about 8% or from about 3% to about 7% (as determined in accordance with ASTM D638), for example.
The polylactic acid may exhibit a flexural modulus of from about 250,000 psi to about 600,000 psi, or from about 300,000 psi to about 550,000 psi or from about 400,000 psi to about 500,000 psi (as determined in accordance with ASTM D790), for example.
The polylactic acid may exhibit a notched Izod impact of from about 0.1 ft-lb/in to about 0.8 ft-lb/in, or from about 0.2 ft-lb/in to about 0.7 ft-lb/in or from about 0.4 ft-lb/in to 0.6 about ft-lb/in (as determined in accordance with ASTM D256), for example.
Styrenic monomers useful in the present disclosure include monovinylaromatic compounds such as styrene as well as alkylated styrenes wherein the alkylated styrenes are alkylated in the nucleus or side-chain. Alphamethyl styrene, t-butylstyrene, p-methylstyrene, methacrylic acid, and vinyl toluene are monomers that may be useful in forming a polymer of the disclosure. These monomers are disclosed in U.S. Pat. No. 7,179,873 to Reimers et al., which is incorporated by reference in its entirety. The styrenic polymer may be a homopolymer or may optionally comprise one or more comonomers. As used herein the term styrene includes a variety of substituted styrenes (e.g. alpha-methyl styrene), ring substituted styrenes such as p-methylstyrene, distributed styrenes such as p-t-butyl styrene as well as unsubstituted styrenes, and combinations thereof.
The monovinylidene aromatic polymer may be general purpose polystyrene or a rubber modified polymeric composition, such as high impact polystyrene, where an amount of rubber in dispersed in a styrenic matrix. Polybutadiene or a polymer of a conjugated 1,3-diene may be used in an amount of from 0.1 wt % to 50 wt % or more, or from 1% to 30% by weight of the rubber-styrene solution.
Embodiments of the disclosure include contacting the polymer with certain metallic acrylate salts represented by the formula: M(OOC)—CR1=CR2,R3, where M is a metal and R1 is hydrogen or methyl and R2, R3 are hydrogen. M can be an alkali metal or alkaline earth metal such as Zn, Ca, Mg, Li, Na, Pb, Sn, K or combinations thereof. In certain embodiments, M is Zn. Examples of these salts include, but are not limited to, zinc diacrylate, zinc dimethacrylate, zinc monomethacrylate, and sodium acrylate such as those from HSC Cray Valley called Dymalinks. The mixture of the polymer and metallic acrylate salt may include between 0.001 and 30 wt % of the metallic acrylate salt, between 0.01 and 25 wt % of the metallic acrylate salt, between 0.1 and 20 wt % of the metallic acrylate salt, or from 0.5 to 15 wt % of the metallic acrylate salt.
In certain embodiments of the present disclosure, the metallic acrylate salt may be mixed with a peroxide activator. Peroxide activators may be organic peroxides, which include, but are not limited to LUPEROX® 101, commercially available from Arkema, Inc., Trigonox 101 and Trigonox 301, commercially available from AkzoNobel, Inc., for example. The concentration of the peroxide activator may range from 1 ppm to 50000 ppm, or from 10 ppm to 10000 ppm, or from 10 to 1000 ppm based on the concentration of the metallic acrylate salt.
Mixing of the metallic acrylate salt with the polymer may be performed by melt mixing using medium to high intensity mixing equipment including single and twin screw extruders, banbury mixers, or roll mill provided the metallic acrylate salt is adequately dispersed. Temperatures utilized for mixing may be 30° C. above the melting point of the polymer. In particular embodiments, the polymer/metallic acrylate salt may be heated above 200° C., or between 200-260° C. In certain embodiments of the present disclosure, such as when a peroxide activator is used, the metallic acrylate salt may be formed in situ, i.e., may be formed during the melt mixing process. For instance, in one embodiment, the metallic acrylate salt may be formed by mixing zinc oxide with acrylic acid while mixing with the polymer. The zinc oxide and acrylic acid will react during the melt mixing process to form a zinc acrylate.
In certain embodiments of the present disclosure, the mixture of the polymer and metallic acrylate salt may result in viscosity modification (increase), strain hardening, crystalline nucleation, heat deflection temperature (HDT) increase, and modulus increase.
The polymers and blends thereof are useful in polymer fabrication processes known to one skilled in the art, where high melt strength is required. These include foaming, sheet extrusion thermoforming, extrusion blow molding, injection stretch blow molding, blown film, extrusion coating, roto-molding, profile or pipe extrusion. Films include shrink film, cling film, stretch film, sealing films, oriented films, snack packaging, heavy duty bags, grocery sacks, baked and frozen food packaging, medical packaging, industrial liners, and membranes, for example, in food-contact and non-food contact applications. Extruded articles include foamed articles used for insulation board, acoustical dampening, energy absorbing articles for automotive parts etc., and foamed food packaging containers, for example. Extruded articles also include medical tubing, wire and cable coatings, sheets, such as thermoformed sheets (including profiles and plastic corrugated cardboard), geomembranes and pond liners, for example. Molded articles include single and multi-layered constructions in the form of bottles, tanks, large hollow articles, rigid food containers and toys, for example.
Total 6407 (commercially available from Total Petrochemicals and Refining USA, Inc.), a 0.7 dg/min MI2, 0.961 g/cc density polyethylene, was melt blended with 1% by weight Dymalink D705 (formerly called SR372), a metallic acrylate salt (zinc diacrylate) made by Cray Valley. Addition of D705 significantly lowered the melt indexes of Total 6407 as shown in Table 1. The rheological results also indicated significant increase in melt viscosity especially zero shear viscosity, which was consistent with the melt strength increase as evidenced by the results of extrusion melt strand sag resistance shown in Table 1 and in
Total Petrochemicals polypropylene 3270, 3371, and M3282 were melt blended with 2% and 5% Dymalink D705, a metallic carboxylate salt made by Cray Valley. Addition of D705 significantly lowered the melt indexes of all the polypropylene resins selected for the study, indicating increased viscosity of polypropylene in the presence of the metallic acrylate salt as shown in Table 2.
Different types of polypropylene were melt blended with 2% Dymalink D705 and the viscosity compared to the same polypropylene made without the Dymalink D705. Results are shown in Tables 2a.
RCP refers to polypropylene random copolymers, which for Table 2a, are Total 7625 and Total Z9450, commercially available from Total Petrochemicals and Refining USA, Inc. ICP refers to polypropylene impact copolymers, which, for Table 2a are Total 4524 and Total 4921, commercially available from Total Petrochemicals and Refining USA, Inc. siPP refers to metallocene-based syndiotatic polypropylene, which, for Table 2a is Total 1471, commercially available from Total Petrochemicals and Refining USA, Inc. miPP refers to metallocene-based isotactic polypropylene, which, for Table 2a, is Total 3282, commercially available from Total Petrochemicals and Refining USA, Inc.
The four examples were conducted by combining 1% by weight of the D705 additive with PP LX1-12-03, a mini-random polypropylene. Differential Scanning calorimetry (Example 2a), Heat Distortion Temperature (Example 2b), Dynamic Mechanical Analysis (Example 2c), and Hardness (Example 2d) testing were performed. For each example, four samples were created:
Injection Mold: Control
Injection Mold: D705
Compression Mold: Control
Compression Mold: D705
Both the control samples and the 1% by weight D705 samples were extruded at 390° F. The samples were produced by injection molding and compression molding.
The injection molded samples were produced using a DSM micro injection molding machine with the half IZOD mold. The samples were heated to 225° C. for 3 minutes and injected into the mold (set at 60° C.).
The compression molded samples were molded using an automated compression molder at 177° C. (10 min low pressure, 10 min high pressure) with a cooling rate of 10° C./min. A 0.120″ thick plaque was employed to produce samples that are about 3 mm thick. The samples were completely melted and uniform plaques obtained. After further cooling, the full IZOD specimens were punched out of the plaque. After at least 3 hours, to ensure complete cooling, each sample was polished flat by hand using a polish wheel in water before testing was performed.
The injection molded samples required more polishing than the compression molded samples. The injection molded control samples exhibited more shrinkage than the samples that included the D705 additive. The control samples required more polishing to produce a uniformly flat specimen.
Each of the four samples was tested using the DSC with heating and cooling rates of 10° C./min. The results are compiled in
The initial heating results may suggest the injection molded samples have less initial structure (i.e., crystallinity) than the compression molded samples. The D705 reduces the crystallinity of the injection molded samples, but has little impact on the compression molded parts. The subsequent cooling segments show that the crystallization temperature is raised by about 10° C. for the samples that included D705. The reheating segment shows a change in behavior as compared to the initial heating curve. In the injection molded samples with 1% D705, the energy was increased beyond the injection molded control case.
HDT testing was conducted on TA-Q800 (available form TA Instruments) with a method analogous to ASTM E2092-09, as described in ASTM Standard E2092-09: “Standard test method for distortion temperature in three-point bending by thermomechanical analysis”, Annual Book of Standards, Vol. 08.04, ASTM International, West Conshohocken, Pa., 2009. The settings and HDT values are summarized in Table 3. The 3pt-bend fixture that was employed has free ends, with stationary roller supports. Testing was extended beyond the normal maximum bending strain to illustrate the differences in performance for bending strains exceeding 0.5% strain. After test completion, the strain was shifted such that zero strain corresponded to an initial temperature of 30° C.
The test for each sample was repeated four times and averaged to produce the data in
TA-RDA-2 equipment was employed to conduct a temperature sweep (30° C. to 140° C.) at a torsional frequency of 5 Hz and a shear strain magnitude of 0.5% strain. The shear modulus (stiffness) versus temperature is presented in
The hardness was tested in duplicate on a flat segment of each tested HDT sample. The hardness was recorded to the nearest whole number after a 2 second holding period. The results were averaged over all measurements (at least 8 values). A summary of these averaged results is presented in Table 4. For both molding conditions, 1% by weight D705 additive resulted in an improvement in hardness.
As shown by Examples 2a-2d, adding 1% (by weight) of D705 to polypropylene:
increases the temperature of crystallization;
improves HDT;
increases torsional stiffness at room temperature; and
increases the hardness at room temperature.
Polybond 3150 (available from Addivant), a maleic anhydride grafted polypropylene was blended with 2% by weight Dymalink D705 (formerly called SR732). Significant melt index drop was obtained. When additional potassium hydroxide (1% by weight) was present, the melt index dropped even further, indicating a possible synergistic effect of PP-based ionomer and metallic acrylate salts on improving polypropylene melt strengths. These effects are shown in Table 5.
Total Petrochemicals polystyrene 523W (available from Total Petrochemicals and Refining USA, Inc.) was melt blended with 2% by weight Dymalink D705 made by Cray Valley. The melt flow rates were measured under polypropylene conditions. The addition of the Dymalink D705 effectively lowered the melt flow rate of the polystyrene, indicating that the metallic acrylate salt could effectively boost the melt strength of polystyrene-based materials. These effects are shown in Table 6.
Polypropylene fluff (Total 3354, 4.5 MFR, available from Total Petrochemicals and Refining USA, Inc.) was mixed with antioxidants (500 ppm of Irganox 1010, 500 ppm of Irgafos 168, both available from BASF), 500 ppm of a neutralizer (DHT 4V, available from Kisuma Chemicals), 200 ppm of a peroxide Trigonox 301 (available from AkzoNobel), and 2 ppm of Dymalink D705 (zinc diacrylate), 2 ppm of D708 (zinc dimethacrylate), or 2 ppm of D709 (zinc monomethacrylate), each available from Cray Valley, as shown in Table 7. The powder mixture was then pelletized using a twin screw extruder with targeted melt temperature of 445° F. The resulting melt flow rate (MFR) was measured according to ASTM D-1238. The results show the viscosity increase resulting from the D705, D708, or D709 addition.
Polypropylene fluff (Total 3354, 4.5 MFR, available from Total Petrochemicals and Refining USA, Inc.) was mixed with antioxidants (500 ppm of Irganox 1010, 500 ppm of Irgafos 168), 500 ppm of a neutralizer (DHT 4V), 50 ppm of a peroxide Perkadox 24L (available from AkzoNobel), and 2 ppm of either Dymalink D705, D636 (available from Cray Valley) or sodium acrylate powder as shown in Table 8. The powder mixture was then pelletized using a twin screw extruder with targeted melt temperature of 445° F. The resulting melt flow rate (MFR) was measured according to ASTM D-1238. The results show the viscosity increase resulting from the D705, D636, or sodium acrylate addition.
Polypropylene fluff (Total 3354, 4.5 MFR) was mixed with antioxidants (500 ppm of Irganox 1010, 500 ppm of Irgafos 168), 500 ppm of a neutralizer (DHT 4V), and Dymalink D705, zinc stearate or calcium stearate as shown in Table 9. The powder mixture was then pelletized using a twin screw extruder with targeted melt temperature of 445° F. The resulting melt flow rate (MFR) was measured according to ASTM D-1238. The results show the viscosity increase resulting from the D705 addition.
As shown in Comparative Example 1, calcium stearate and zinc stearate do not result in a viscosity increase, while zinc diacrylate does result in a viscosity increase.
Polypropylene fluff (Total LX1 12-03, 4.5 MFR) was mixed with antioxidants (500 ppm of Irganox 1010, 500 ppm of Irgafos 168), 500 ppm of a neutralizer (DHT 4V) for Sample A. Polypropylene fluff (Total LX1 12-03, 4.5 MFR) was mixed with antioxidants (500 ppm of Irganox 1010, 500 ppm of Irgafos 168), 500 ppm of a neutralizer (DHT 4V)+2% by weight of D705 for Sample B. The powder mixtures were pelletized using a twin screw extruder with targeted melt temperature of 445° F. The resulting pellets were extruded using a tandem foam extruder using CO2 gas injection to produce a foam sheet. The resulting sheet foam densities are shown in Table 10. The D705 addition effectively improved the foaming.
Polypropylene (Total 3354) was mixed and compounded with D705 at 380° F. and then re-extruded at 450° F.
Table 11 shows the elongational viscosity ratio (EVR) for samples extruded at 380° F. and then re-extruded at 450° F. The elongational viscosity ratio is defined by the equation: EVR=elongational viscosity (EV) at 10 sec÷ EV at 0.1 sec. A higher EVR corresponds with more strain hardening.
Depending on the context, all references herein to the “disclosure” may in some cases refer to certain specific embodiments only. In other cases it may refer to subject matter recited in one or more, but not necessarily all, of the claims. While the foregoing is directed to embodiments, versions and examples of the present disclosure, which are included to enable a person of ordinary skill in the art to make and use the disclosures when the information in this patent is combined with available information and technology, the disclosures are not limited to only these particular embodiments, versions and examples. Other and further embodiments, versions and examples of the disclosure may be devised without departing from the basic scope thereof and the scope thereof is determined by the claims that follow.
This application is a Non-Provisional of U.S. Provisional Application No. 61/857,510, filed on Jul. 23, 2013.
| Number | Date | Country | |
|---|---|---|---|
| 61857510 | Jul 2013 | US |
