Patent Application
20250059360
There is a need for polymer formulations for the injection molding of complex parts, such as complex profiles. In addition, such profiles are typically formed from a foamed formulation. These formulations must have low viscosity for a fast, uniform flow within the mold cavity, and a fast cure response to build elasticity and strength during the injection molding process. Developing such a polymer formulation is an unmet need in the market.
U.S. Pat. No. 8,389,634 discloses a thermoplastic composition that comprises the following: (i) from 1 to 99 percent, by weight of the total composition, of at least one thermoplastic copolymer, for example, styrene block copolymers, and (ii) from 1 to 99 percent, by weight of the total composition, of at least one homogeneously branched ethylene/alpha-olefin interpolymer, for example ethylene/1-octene, having a density less than, or equal to, 0.899 g/cc and a Brookfield viscosity of greater than 500 cP (350° F.). See abstract. Other thermoplastic polymers include, but are not limited to, the natural or synthetic resins, such as styrene block copolymers, rubbers, linear low density polyethylene (LLDPE), high density polyethylene (HDPE), low density polyethylene (LDPE), ethylene/vinyl acetate (EVA) copolymer, ethylene-carboxylic acid copolymers (EAA), ethylene acrylate copolymers, polybutylene, polybutadiene, nylons, polycarbonates, polyesters, polypropylene, ethylene-propylene interpolymers such as ethylene-propylene rubber, ethylene-propylene-diene monomer rubbers, chlorinated polyethylene, thermoplastic vulcanizates, ethylene ethylacrylate polymers (EEA), ethylene styrene interpolymers (ES), polyurethanes, as well as graft-modified olefin polymers, and combinations of two or more of these polymers (see column 11, lines 1-16). See also, column 2, lines 42-56; column 3, line 7-22; and column 13, line 58, to column 14, line 3. The compositions can be used in injection molding processes (see, for example, column 11, lines 47-51, and column 13, lines 26-41).
CN107418061A (machine translation) discloses a polymer formulation for a door weather strip sponge, and containing two ethylene/propylene/diene rubbers, an activated zinc oxide, stearic acid, a dispersant, erucyl amide, PEG 4000, a POE, paraffin oil, carbon black, sulfur, an hygroscopic agent, an accelerator, a foaming agent and a blowing agent (see abstract of machine translation). The POE is a polyolefin elastomer (see page 4, first paragraph of machine translation).
International Publication WO2006/004750 discloses composition and methods for improving the adhesion of a film to a non-woven, a film to another film, or a nonwoven to another nonwoven. Depending on the structure, the improvement can be achieved by using low viscosity, low density ethylene-based or propylene-based polymers, which physically anchor to the substrate, or by using a similar polymer in a blend (components A and B) with one of the substrate film polymers to improve flow and adhesion (see abstract and claims 1-3). Useful polymers include thermoplastic compositions containing at least one low viscosity, homogeneously branched ethylene polymer, having a density from 0.855 g/cc to 0.899 g/cc, and a Brookfield viscosity of at least 500 cP, at 350° F. The thermoplastic composition may contain at least 50 wt percent, based on the total weight of the composition, of the thermoplastic polymer. Suitable examples of the thermoplastic polymer include, but are not limited to, synthetic rubbers, linear low density polyethylene (LLDPE), high density polyethylene (HDPE), low density polyethylene (LDPE), ethylene vinyl acetate (EVA) copolymer, polybutadiene and ethylene-propylene-diene. Additional useful polymers include polymer blends containing isotactic polypropylene and an alpha-olefin/propylene copolymer. See page 19, lines 3-17.
U.S. Publication 2015/0376385 discloses a composition comprising the following: A) an ethylene/alpha-olefin/diene interpolymer, B) a functionalized ethylene-based polymer selected from the group consisting of the following: a) an anhydride grafted ethylene/alpha-olefin interpolymer; b) an acid functionalized ethylene-based polymer, and c) an ester functionalized ethylene-based polymer; and C) a crosslinking agent; and wherein the weight ratio of component A to component B is from 98:2 to 60:40 (see abstract). In an embodiment, the ethylene/alpha-olefin/diene interpolymer is disclosed as having a Mooney viscosity (ML (1+4) at 125° C.) from 50 to 300 (see paragraph [0068]).
As discussed above, there remains a need for polymer compositions with excellent compound flows and fast cure rates, for the injection molding of complex parts of good quality and strength, and improved part productivity. This need has been met by the following invention.
A composition comprising at least the following components:
Compositions have been discovered that have fast flow rates and fast cure rates for the injection molding of complex parts.
As discussed above, a composition is provided, and which comprises at least the following components:
In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component a has a Mooney Viscosity (ML1+4 at 125° C.)≥11, or ≥12, or ≥14, or ≥16, or ≥18, or ≥20. In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component a has a Mooney Viscosity (ML1+4 at 125° C.)≤38, or ≤36, or ≤34, or ≤32, or ≤30.
In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component a has a density ≥0.850, or ≥0.852, or ≥0.854, or ≥0.856, or ≥0.858, or ≥0.859, or ≥0.860 g/cc, or ≥0.880, or ≥0.890, or ≥0.900, or ≥0.910, or ≥0.920, or ≥0.950 (1 cc=1 cm3). In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component a has a density ≤0.950, or ≤0.920, or ≤0.910, or ≤0.900, or ≤0.890, or ≤0.880, or ≤0.870, or ≤0.868, or ≤0.866, or ≤0.864, or ≤0.863, or ≤0.862, or ≤0.861 g/cc.
In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component a is an ethylene/alpha-olefin/non-conjugated diene interpolymer, further an ethylene/alpha-olefin/non-conjugated diene terpolymer, and further an EPDM.
In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component b has a melt viscosity (177° C.)≥5,000, or ≥5,500, or ≥6,000, or ≥6,200, or ≥6,400, or ≥6,600, or ≥6,800, or ≥7,000, or ≥7,200, or ≥7,400, or ≥7,600, or ≥7,800, or ≥8,000 mPa·s. In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component b has a melt viscosity (177° C.)≤45,000, or ≤40,000, or ≤35,000, or ≤30,000, or ≤28,000, or ≤26,000, or ≤24,000, or ≤22,000, or ≤20,000, or ≤18,000 mPa·s.
In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component b has a density ≥0.860, or ≥0.862, or ≥0.864, or ≥0.866, or ≥0.868, or ≥0.870 g/cc. In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component b has a density 5 0.890, or ≤0.885, or ≤0.880, or ≤0.879, or ≤0.878, or ≤0.877, or ≤0.876, or ≤0.875 g/cc, or ≤0.874 g/cc.
In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component b has a melting point (Tm)≥50° C., or ≥55° C., or ≥58° C., or ≥60° C., or ≥62° C., or ≥64° C., or ≥65° C., or ≥66° C., or ≥67° C., or ≥68° C. and/or ≤85° C., or ≤82° C., or ≤80° C., or ≤78° C., or ≤76° C., or ≤74° C., or ≤73° C., or <72° C., or ≤γ71° C., or ≤70° C.
In one embodiment, or a combination of two or more embodiments, each described herein, the at least one interpolymer of component b is an ethylene/alpha-olefin copolymer.
In one embodiment, or a combination of two or more embodiments, each described herein, the composition has a Mooney Viscosity (ML1+4 at 100° C.)≥6.2, or ≥6.4, or ≥6.6, or ≥6.8, or ≥7.0, or ≥7.1, or ≥7.2. In one embodiment, or a combination of two or more embodiments, each described herein, the composition has a Mooney Viscosity (ML1+4 at 100° C.)≤9.5, or ≤9.0, or ≤8.7, or ≤8.5, or ≤8.2, or ≤8.0, or ≤7.5.
In one embodiment, or a combination of two or more embodiments, each described herein, the ratio of the density of the at least one interpolymer of component a to the density of the at least one interpolymer of component b is ≥0.970, or ≥0.972, or ≥0.974, or ≥0.976, or ≥0.978, or ≥0.980, or ≥0.982, or ≥0.983, or ≥0.984, and/or ≤1.00, or ≤0.998, or ≤0.996, or ≤0.994, or ≤0.992, or ≤0.991, or ≤0.990, or ≤0.989.
In one embodiment, or a combination of two or more embodiments, each described herein, the weight ratio of component a to component b is ≥1.5, or ≥1.6, or ≥1.7, or ≥1.8, or ≥1.9, or ≥2.0, or ≥2.1, or ≥2.2, or ≥2.3, or ≥2.4, or ≥2.5, or ≥2.6, or ≥2.7, or ≥2.8, or ≥2.9, or ≥3.0 and/or 5 20, or ≤15, or ≤12, or ≤10, or ≤9.5, or ≤9.0, or ≤8.5, or ≤8.0, or ≤7.5, or ≤7.0, or ≤6.5, or ≤6.0, or ≤5.5, or ≤5.0, or ≤4.8, or ≤4.6, or ≤4.4, or ≤4.2, or ≤4.1, or ≤4.0, or ≤3.0, or ≤2.5, or ≤2.0.
In one embodiment, or a combination of two or more embodiments, each described herein, the composition comprises ≥20 wt %, or ≥22 wt %, or ≥24 wt %, or ≥26 wt %, or ≥28 wt %, or ≥30 wt %, or ≥32 wt %, or ≥34 wt %, and/or ≤50 wt %, or ≤48 wt %, or ≤46 wt %, or ≤44 wt %, or ≤42 wt %, or ≤40 wt %, or ≤38 wt %, or ≤36 wt %, of the sum of components a and b, based on the weight of the composition.
In one embodiment, or a combination of two or more embodiments, each described herein, the composition further comprises an oil (component c).
In one embodiment, or a combination of two or more embodiments, each described herein, the composition further comprises one or more fillers (component d).
In one embodiment, or a combination of two or more embodiments, each described herein, the composition further comprises at least one crosslinking agent, and further at least two crosslinking agents.
In one embodiment, or a combination of two or more embodiments, each described herein, the composition further comprises a blowing agent.
In one embodiment, or a combination of two or more embodiments, each described herein, the composition, upon thermal treatment at a temperature of 180° C., has a [(MH−ML)/tc90]value ≥2.00, or ≥2.10, or ≥2.20, or ≥2.30, or ≥2.40, or ≥2.50, or ≥2.60, or ≥2.80, or ≥3.00, or ≥3.20, or ≥3.40, or ≥3.50, or ≥3.60 dN*m/min, and/or ≤5.00, or ≤4.50, or ≤4.00, or ≤3.60, or ≤3.50 dN*m/min. The MH, ML and the tc90 values are determined by MDR as described herein.
Also provided is a crosslinked composition formed from the composition of any one embodiment or a combination of two or more embodiments as described herein.
Also provided is an article comprising at least one component formed from the composition of any one embodiment or a combination of two or more embodiments as described herein.
Also provided is a process to form a crosslinked composition, said process comprising thermally treating the composition of any one embodiment or a combination of two or more embodiments as described herein.
The ethylene/alpha-olefin/nonconjugated polyene interpolymers, as described herein, comprises, in polymerize form, ethylene, an alpha-olefin, and a nonconjugated polyene. The alpha-olefin may be either an aliphatic or an aromatic compound. Alpha-olefins include, but are not limited to, a C3-C20 alpha-olefins, further C3-C10 alpha-olefins, further C3-C8 alpha-olefins. In one embodiment, the interpolymer is an ethylene/propylene/nonconjugated diene interpolymer, further a terpolymer, further an EPDM. Suitable examples of nonconjugated polyenes include the C4-C40 nonconjugated dienes. Nonconjugated dienes include, but are not limited to, 5-ethylidene-2-norbornene (ENB), 5-vinyl-2-norbornene (VNB), dicyclopentadiene, 1,4-hexadiene, or 7-methyl-1,6-octadiene, and further from ENB, VNB, dicyclopentadiene or 1,4-hexadiene, and further from ENB or VNB, and further ENB.
Component b The ethylene/alpha-olefin interpolymer comprises, in polymerize form, ethylene, and an alpha-olefin. Alpha-olefins include, but are not limited to, a C3-C20 alpha-olefins, further C3-C10 alpha-olefins, further C3-C8 alpha-olefins, such as propylene, 1-butene, 1-hexene, and 1-octene.
An inventive composition may comprise one or more additives. Suitable additives include, but are not limited to, fillers, plasticizers (for example, oils), processing aids, stabilizers (for example, antioxidants, antiozonants, UV stabilizers), crosslinking agents, activators, blowing agents, scavengers, and combinations thereof. Fillers include, but are not limited to, carbon black, calcium carbonate, talc, silicon oxide, aluminum oxide, kaolinite, montmorillonite, silicates (for example, of aluminum, magnesium, calcium), titanium dioxide, natural fibers, synthetic fibers, and the like.
Oils include, but are not limited to, paraffinic oils, naphthenic oils and polyalkylbenzene oils. Blowing agents include, but are not limited to, azodicarbonamide (ADC), p,p′-oxybis-(benzene sulfonyl hydrazide) (OBSH), isocyanate, and sodium bicarbonate.
Stabilizers include, but are not limited to, hindered phenols, bisphenols, thiobis-phenols, and substituted hydroquinones. Typically, one or more stabilizers, in “ppm” amounts, are added to a polymer or a polymer composition. Processing aids include, but are not limited to, fatty acids and PEG compounds, oligomers and polymers.
Crosslinking agents include, but are not limited to, those that are sulfur based agents (for example, elemental sulfur), tetramethylthiuram disulfide (TMTD), dipentamethylenethiuram tetrasulfide (DPTT), 2-mercaptobenzothiazole (MBT), 2-mercaptobenzothiazolate disulfide (MBTS), zinc-2-mercaptobenozothiazolate (ZMBT), zinc diethyldithiocarbamate zinc (ZDEC), zinc dibutyldithiocarbamate (ZDBC), dipentamethylenethiuram tetrasulfide (DPTT), and mixtures thereof. Additional crosslinking agents include, but are not limited to, peroxides, phenolic resins, azides, vinyl silanes, hydrosilylation agents, substituted ureas, substituted guanidines, substituted xanthates, substituted dithiocarbamates, and mixtures thereof.
Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percents are based on weight, and all test methods are current as of the filing date of this disclosure.
The term “composition,” as used herein, includes a mixture of materials, which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition. Any reaction product or decomposition product is typically present in trace or residual amounts.
The term “polymer,” as used herein, refers to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus, includes the term homopolymer (employed to refer to polymers prepared from only one type of monomer, with the understanding that trace amounts of impurities can be incorporated into the polymer structure), and the term interpolymer as defined hereinafter. Trace amounts of impurities, such as catalyst residues, can be incorporated into and/or within the polymer. Typically, a polymer is stabilized with very low amounts (“ppm” amounts) of one or more stabilizers.
The term “interpolymer,” as used herein, refers to polymer prepared by the polymerization of at least two different types of monomers. The term interpolymer thus includes the term copolymer (employed to refer to polymers prepared from two different types of monomers) and polymers prepared from more than two different types of monomers.
The term “olefin-based polymer,” as used herein, refers to a polymer that comprises, in polymerized form, at least 50 wt % or a majority weight percent of an olefin, such as ethylene or propylene (based on the weight of the polymer), and optionally may comprise one or more comonomers.
The term “propylene-based polymer,” as used herein, refers to a polymer that comprises, in polymerized form, at least 50 wt % or a majority weight percent of propylene (based on the weight of the polymer), and optionally may comprise one or more comonomers.
The term “ethylene-based polymer,” as used herein, refers to a polymer that comprises, in polymerized form, at least 50 wt % or a majority weight percent of ethylene (based on the weight of the polymer), and optionally may comprise one or more comonomers.
The term “ethylene/alpha-olefin interpolymer,” as used herein, refers to a random interpolymer that comprises, in polymerized form, at least 50 wt % or a majority weight percent of ethylene (based on the weight of the interpolymer), and an alpha-olefin.
The term “ethylene/alpha-olefin/nonconjugated polyene interpolymer,” as used herein, refers to an interpolymer that comprises, in polymerized form, ethylene, an alpha-olefin, and a nonconjugated polyene. In one embodiment, the “ethylene/alpha-olefin/nonconjugated polyene interpolymer,” comprises, in polymerized form, at least 50 wt % or a majority weight percent of ethylene (based on the weight of the interpolymer). The term “ethylene/alpha-olefin/-nonconjugated diene interpolymer,” as used herein, refers to an interpolymer that comprises, in polymerized form, ethylene, an alpha-olefin, and a nonconjugated diene. In one embodiment, the “ethylene/alpha-olefin/nonconjugated diene interpolymer,” comprises, in polymerized form, at least 50 wt % or a majority weight percent of ethylene (based on the weight of the interpolymer). Note, the terms “ethylene/alpha-olefin/nonconjugated polyene terpolymer” and “ethylene/alpha-olefin/nonconjugated diene terpolymer” are similarly defined; however, for each, the terpolymer comprises, in polymerized form, ethylene, the alpha-olefin and the polyene (or diene) as the only three monomer types.
The term, “ethylene/alpha-olefin copolymer,” as used herein, refers to a random copolymer that comprises, in polymerized form, at least 50 wt % or a majority amount of ethylene (based on the weight of the copolymer), and an alpha-olefin, as the only two monomer types.
The phrase “a majority weight percent,” as used herein, in reference to a polymer (or interpolymer or terpolymer or copolymer), refers to the amount of monomer present in the greatest amount in the polymer.
The term “crosslinked composition,” as used herein, refers to a composition that has a network structure due to the formation of chemical bonds between polymer chains. The formation of this network structure can be indicated by the increase in the “MH−ML” differential, as discussed herein.
The terms “thermally treated,” “thermally treating,” “thermal treatment,” and similar terms, as used herein, in reference to a composition comprising components a and b as described herein, refer to the application of heat to the composition. Heat may be applied by conduction (for example, a heating coil), by convection (for example, heat transfer through a fluid, such as water or air), and/or by radiation (for example, heat transfer using electromagnetic waves). Preferably heat is applied by conduction and/or convection. Note, the temperature at which the thermal treatment takes place, refers to the internal temperature of the device, such as an MDR device (or tunnel), used to cure (or crosslink) the composition. Typically, the composition readily equilibrates (less than 30 seconds) to the temperature of the device.
The terms “comprising,” “including,” “having,” and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, “consisting essentially of” excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term “consisting of” excludes any component, step or procedure, not specifically delineated or listed.
A] A composition comprising at least the following components:
The cure properties of a composition was measured at 180° C. and with a 0.5 deg arc, using an Alpha Moving Die Rheometer (MDR-2000) following ASTM D5289-19. Sample size 25±2 grams. In this method, the ML (dNm) value refers to the Minimum Torque recorded by the rheometer, and it is a measure of the stiffness and viscosity of the composition at a given temperature. The lower the ML value, the better the composition flow before being fully crosslinked.
The MH (dNm) value refers to the Maximum Torque recorded by the rheometer, and is a measure of the crosslinking density of the crosslinked composition. An increased MH value indicates there is an increased in the crosslinking density. The higher the crosslink density, the better the rate of cure within a mold, for example a mold used in an injection molding process.
The MH−ML (dNm) differential refer to the is the torque difference recorded by the rheometer. This torque differential indicated the amount of crosslinking that occurred during the test, and this differential is related to the shear modulus of the composition. Higher the torque differential, the higher the crosslink density, and the higher the elastic recoverability of the crosslinked composition. A high elastic recoverability can help to improve regain properties of an injection molded part.
The tc90 value represents the curing time to reach 90% cure (or 90% of the “MH−ML” value). It is the time required for the cured rubber to reach 90% of the maximum accomplishable torque differential. So, the shorter tc90 value is preferable, especially for an injection molding process, since a shorter time helps to reduce the curing cycle time, and provides better productivity of the injection molded part. Note, the tc50 value represents the time to reach 50% cure (or 50% of the “MH−ML” value).
The ts2 value refers to the scorch time or the point at which the curing actually starts. In a composition, a higher ts2 value leads to a rough surface, because of a delayed curing action. However, if the ts2 value is too short, then there is a chance of composition scorch before the composition completely flows into the mold.
Overall, the best compositions have the following characteristics: lower ML value, for better composition flow, higher MH and MH−ML values for better crosslink density, lower tc90 value (for example, 1.4-1.9 minutes) for optimum cure rate and lower product cure time, and lower ts2 value (for example, 1.0-1.5 minutes) for reduced potential to scorch.
Mooney Viscosity (ML 1+4 at 125° C.) of each EPDM (neat form) is measured in accordance with ASTM D1646, with a one minute preheat time and a “four minute” rotor operation time. The instrument is an Alpha Technologies MV2000E Viscometer. Sample size around 25 grams.
Mooney Viscosity (ML 1+4 at 100° C.) of each composition was measured with an Alpha Technologies MV2000E Viscometer, according to ASTM D1646, at 100° C. (large rotor). The preheating time was one minute, and the rotor operation time was four minutes. The Mooney Viscosity of each formulated composition was measured using an uncured blanket or sheet (see experimental section) of about 25 grams.
Polymer density is measured in accordance with ASTM D297.
The melt index (I2) of an ethylene-based polymer is measured in accordance with ASTM D-1238, condition 190° C./2.16 kg. The melt flow rate (MFR) of a propylene-based polymer is measured in accordance with ASTM D-1238, condition 230° C./2.16 kg.
The EPDM terpolymers containing ethylene, propylene, and 5-ethylidene-2-norbornene were analyzed, using ASTM D3900 for ethylene content, and ASTM D6047 for ethylidene-norbornene (ENB) content. Similar analyses can be used to measure the monomer content (for example, C2, alpha-olefin or diene) of other interpolymers and terpolymers.
Melt viscosity was measured in accordance with ASTM D1084, using a Brookfield Viscometer (Model DV0III, version 3), and a SC-31 hot-melt viscometer spindle, at a temperature of 177° C. (350° F.). Sample size about 8-10 grams of pellets.
Differential Scanning Calorimetry (DSC) is used to measure Tm, Tc, Tg and crystallinity in ethylene-based (PE) and propylene-based (PP) polymer samples. Each sample (0.5 g) is compression molded into a film, at 25000 psi, 190° C., for 10-15 seconds. About 5 to 8 mg of film sample is weighed and placed in a DSC pan. The lid is crimped on the pan to ensure a closed atmosphere. The sample pan is placed in a DSC cell, and then heated, at a rate of approximately 10° C./min, to a temperature of 180° C. for PE (230° C. for PP). The sample is kept at this temperature for three minutes. Then the sample is cooled at a rate of 10° C./min to −90° C. for PE (−60° C. for PP), and kept isothermally at that temperature for three minutes. The sample is next heated at a rate of 10° C./min, until complete melting (second heat). Unless otherwise stated, the melting point (Tm) and the glass transition temperature (Tg) of each polymer sample are determined from the second heat curve, and the crystallization temperature (Tc) is determined from the first cooling curve. The Tg and the respective peak temperatures for the Tm and the Tc are noted. The percent crystallinity can be calculated by dividing the heat of fusion (Hf), determined from the second heat curve, by a theoretical heat of fusion of 292 J/g for PE (165 J/g for PP), and multiplying this quantity by 100 (for example, % cryst.=(Hf/292 J/g)×100 (for PE)).
The chromatographic system consists of a PolymerChar GPC-IR (Valencia, Spain) high temperature GPC chromatograph, equipped with an internal IRS infra-red detector (IRS). The autosampler oven compartment is set at 1600 Celsius, and the column compartment is set at 1500 Celsius. The columns are four AGILENT “Mixed A” 30 cm, 20-micron linear mixed-bed columns. The chromatographic solvent is 1,2,4-trichlorobenzene, which contains 200 ppm of butylated hydroxytoluene (BHT). The solvent source is nitrogen sparged. The injection volume is 200 microliters, and the flow rate is 1.0 milliliters/minute.
Calibration of the GPC column set is performed with 21 narrow molecular weight distribution polystyrene standards, with molecular weights ranging from 580 to 8,400,000, and which are arranged in six “cocktail” mixtures, with at least a decade of separation between individual molecular weights. The standards are purchased from Agilent Technologies. The polystyrene standards are prepared at “0.025 grams in 50 milliliters” of solvent, for molecular weights equal to, or greater than, 1,000,000, and at “0.05 grams in 50 milliliters” of solvent, for molecular weights less than 1,000,000. The polystyrene standards are dissolved at 80 degrees Celsius, with gentle agitation, for 30 minutes. The polystyrene standard peak molecular weights are converted to polyethylene molecular weights using Equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)): Mpolyethylene=A×(Mpolystyrene)B (EQ1), where M is the molecular weight, A has a value of 0.4315 and B is equal to 1.0.
A fifth order polynomial is used to fit the respective polyethylene-equivalent calibration points. A small adjustment to A (from approximately 0.375 to 0.445) is made to correct for column resolution and band-broadening effects, such that linear homopolymer polyethylene standard is obtained at 120,000 Mw.
The total plate count of the GPC column set is performed with decane (prepared at “0.04 g in 50 milliliters” of TCB, and dissolved for 20 minutes with gentle agitation.) The plate count (Equation 2) and symmetry (Equation 3) are measured on a 200 microliter injection according to the following equations:
where RV is the retention volume in milliliters, the peak width is in milliliters, the peak max is the maximum height of the peak, and ½ height is ½ height of the peak maximum; and
where RV is the retention volume in milliliters, and the peak width is in milliliters, Peak max is the maximum position of the peak, one tenth height is 1/10 height of the peak maximum, and where rear peak refers to the peak tail at later retention volumes than the peak max, and where front peak refers to the peak front at earlier retention volumes than the peak max. The plate count for the chromatographic system should be greater than 18,000, and symmetry should be between 0.98 and 1.22.
Samples are prepared in a semi-automatic manner with the PolymerChar “Instrument Control” Software, wherein the samples are weight-targeted at 2 mg/ml, and the solvent (contained 200 ppm BHT) is added to a pre nitrogen-sparged, septa-capped vial, via the PolymerChar high temperature autosampler. The samples are dissolved for two hours at 160° Celsius under “low speed” shaking.
The calculations of Mn(GPC), Mw(GPC), and Mz(GPC) are based on GPC results using the internal IRS detector (measurement channel) of the PolymerChar GPC-IR chromatograph according to Equations 4-6, using PolymerChar GPCOne™ software, the baseline-subtracted IR chromatogram at each equally-spaced data collection point (i), and the polyethylene equivalent molecular weight obtained from the narrow standard calibration curve for the point (i) from Equation 1. Equations 4-6 are as follows:
In order to monitor the deviations over time, a flowrate marker (decane) is introduced into each sample, via a micropump controlled with the PolymerChar GPC-IR system. This flowrate marker (FM) is used to linearly correct the pump flowrate (Flowrate(nominal)) for each sample, by RV alignment of the respective decane peak within the sample (RV(FM Sample)), to that of the decane peak within the narrow standards calibration (RV(FM Calibrated)). Any changes in the time of the decane marker peak are then assumed to be related to a linear-shift in flowrate (Flowrate(effective)) for the entire run. To facilitate the highest accuracy of a RV measurement of the flow marker peak, a least-squares fitting routine is used to fit the peak of the flow marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation is then used to solve for the true peak position. After calibrating the system, based on a flow marker peak, the effective flowrate (with respect to the narrow standards calibration) is calculated as Equation 7:
Processing of the flow marker peak is done via the PolymerChar GPCOne™ Software. Acceptable flowrate correction is such that the effective flowrate is within +/−0.7% of the nominal flowrate.
Commercial Polymers are shown in Tables 1 and 2. Additives are listed below these tables. PGP-25j
Inventive and comparative compositions are listed in Table 3 below.
A step by step mixing procedure was used to mix each composition as shown in Table 3 above. The initial mixing temperature was 50° C. For inventive composition 1 (Inv. 1), the NORDEL 6530 XFC EPDM was masticated for 30 seconds, and next the AFFINITY GA 1900 was added, and the resulting mixture was masticated for another 30 seconds (Bainite mixer, 1.6 liter internal mixer). The fill factor was 0.75 (Bainite mixing chamber). Then stearic acid, ZnO, the oil (½ total amount), carbon black (⅔ the total amount), and the white filler were added, and the resulting mixture was mixed at 50 RPM for 60 seconds (in the Bainite mixer). Next, the PEG and the remaining oil and carbon black were added, and the mixture was mixed for another 80 seconds at 50 RPM. The mixing device was then rammed up, swiped and cleaned, and the fillers on the ram were added back into the mixer chamber (1.6 liter). Mixing continued, until the mixture reached a temperature of 120° C. The mixture was dumped onto a tray, and mixing was continued on a 6 inch, temperature controlled, two-roll mill (Bharaj Machinery). A “0.5 inch thick” blanket was sheeted out, and kept at room temperature for 12 hours, to improve the polymer filler interaction (networking). All the remaining additives, including the blowing agent and the CaO, were thoroughly mixed into the blanket on the temperature controlled, two roll mill, and a “0.5 inch thick” blanket was sheeted out. After one hour at room temperature, the rheology and other properties of the uncured composition (blanket or sheet) were measured. Results are shown in Table 4 below.
Optimal cure properties for the injection molding of complex parts, for example complex profiles, are as follows: a) low tc90 values for a fast cure rate and reduced product cure time, b) high MH and “MH−ML” values for a higher crosslinking density, c) low ML values for better composition flow within a mold, and d) fairly low ts2 values to reduce the potential for scorching. In regard to the composition viscosity, lower Mooney values are preferred to ensure the complete filling of the mold. To reduce variation in the test results, for each composition, only the polymer variation was changed, and the amount of each additive was kept constant, as seen in Table 3. Inventive compositions 1-4 result in better complex profiles, as compared to the comparative compositions.
The comparative compositions A-C had Mooney values of 11MU, 15 MU and 13MU, respectively. Such high Mooney values lead to poor processability and short mold filled (that is, a low flow of the composition inside the mold). Inventive compositions 1-4, and comparative composition D, with a Mooney values of 7.3MU, 8.0 MU, 7.3 MU, 7.2 MU and 8-10 MU, respectively, are able to fill a complex mold. The comparative compositions also had higher ML values as compared to the inventive compositions, indicating a poorer composition flow within a mold.
Inventive compositions 1-4 had significantly lower tc90 values (1.74 min, 1.85 min, 1.80 min, 1.87 min) as compared to comparative composition D (2.12 min), which indicates that the inventive compositions had faster cure rates than the comparative composition. Inventive compositions 1-4 also had higher MH values (5.80 Nm, 5.20 Nm, 5.95 nm, 6.88 nm) and higher “MH−ML” values (5.55 Nm, 4.82 Nm, 5.65 Nm, 6.73), as compared to comparative composition D (MH=4.36 Nm, “MH−ML”=3.86 Nm). These results indicate a higher degree of crosslinking in the inventive compositions, which, in turn, provide for parts having better mechanical strength and properties. As discussed above, the inventive compositions also had lower ML values for better composition flow within a mold.
For inventive compositions 1 and 3, the scorch times (ts2), at 180° C., were 1.14 minutes and 1.18 minutes, respectively, and the tc90 times were 1.74 minutes and 1.80 minutes, respectively. The shorter tc90 and ts2 values of these compositions indicate a high curing rate at 180° C. (or higher temperatures), and a lower potential for scorching, and thus a better surface finish on the injection molded part.
Compositions have been discovered that provide optimum viscosity and cure properties for complex injection molding parts. As noted from the viscosity and cure data, the inventive compositions provide for a fast flow rate and a fast curing rate, for complex injection molded parts of good quality and strength, and increased productivity.
This application claims the benefit of priority to U.S. Provisional Application No. 63/265,652, tiled on Dec. 17, 2021.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/081846 | 12/16/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63265652 | Dec 2021 | US |
