Patent Application
20230203307
The invention relates to polymer compositions, including a polyamide and a reactive impact modifier, having excellent retention of mechanical properties after aging. The invention also relates to methods of making the polymer compositions and to articles incorporating the polymer compositions.
Traditional semi-aromatic polyamides are used for the manufacture of components exposed to engine coolant and brine solutions. The high chemical resistance and desirable mechanical performance of these traditional semi-aromatic polyamides are particularly suited for engine coolant and brine solution environments. However, because such articles are generally located in high temperature environments, the articles are exposed to elevated temperatures. Over time, the mechanical performance of such articles can degrade to undesirable levels.
In one aspect, the invention is directed to a polymer composition (PC) comprising: a polyamide (PA) and a reactive impact modifier (IM). The polyamide (PA) is derived from the polycondensation of monomers in a reaction mixture comprising: a diamine component (A) comprising: 20 mol % to 95 mol % of a C4 to C12 aliphatic diamine and 5 mol % to 80 mol % of bis(aminoalkyl)cyclohexane, wherein mol % is relative to the total moles of each diamine in the diamine component; a dicarboxylic acid component (B) comprising: 30 mol % to 100 mol % of terephthalic acid and 0 mol % to 70 mol % of a cyclohexanedicarboxylic acid, wherein mol % is relative to the total moles of each dicarboxylic acid in the dicarboxylic acid component. In some embodiments, the bis(aminoalkyl)cyclohexane is 1,3-bis(aminomethyl)cyclohexane or 1,4-bis(aminomethyl)cyclohexane. In some embodiments, the dicarboxylic acid component (B) comprises 1 mol % to 70 mol % of cyclohexanedicarboxylic acid, preferably 1,4-cyclohexanedicarboxylic acid, relative to the total moles of each dicarboxylic acid in the dicarboxylic acid component.
In some embodiments, the reactive impact modifier (IM) is a maleic anhydride functionalized impact modifier. In some embodiments, the reactive impact modifier (IM) concentration is from 1 wt. % to 20 wt. %. In some embodiments, the polymer composition (PC) further comprises, relative to the total weight of the polymer composition, from 5 wt. % to 70 wt. % of a reinforcing agent. In some embodiments, the reinforcing agent is glass fiber or carbon fiber, preferably glass fiber.
In some embodiments, the polymer composition (PC) comprises a tensile strength retention of at least 60% after aging in a 130° C., 50:50 ethylene glycol:water solution for 1000 hours. In some embodiments, the polymer composition (PC) comprises a flexural strength retention of at least 85% after heat aging in a 130° C., 26 wt. % aqueous NaCl solution for 1000 hours.
In another aspect, the invention is directed an article comprising the polymer composition (PC), wherein the article is an automotive component or a subterranean or sub-sea oil and gas component.
Described herein are polymer compositions (PC) including a polyamide (PA) and a reactive impact modifier. As explained in detail below, the polyamide (PA) is a semi-aromatic polyamide derived from the polycondensation of an aliphatic diamine, a bis(aminoalkyl)cyclohexane, terephthalic acid, and, optionally, a cyclohexanedicarboxylic acid. It was surprisingly discovered that semi-aromatic polyamides derived from the cycloaliphatic diamine bis(aminoalkyl)cyclohexane or the specific combination of the cycloaliphatic diamine bis(aminoalkyl)cyclohexane and the cycloaliphatic dicarboxylic acid cyclohexanedicarboxylic acid provided for polymer compositions (PC) having improved retention of mechanical properties (e.g. tensile strength and flexural strength) after aging in aqueous solutions, relative to analogous polyamides free of the bis(aminoalkyl)cyclohexane and the cyclohexanedicarboxylic acid. For clarity, as used herein, reference to “aging” implicitly refers to heat aging in aqueous solutions. Due at least in part to the improved retention of mechanical properties after aging, the polymer compositions (PC) can be desirably incorporated into articles that, during use, are exposed to elevated temperatures and are designed to convey or store aqueous solutions including, but not limited to, engine coolant and brine solutions. Additionally, the polymer compositions (PC) can be desirably incorporated into articles that are designed for use in down-oil recovery components and exposed to brine solutions.
In the present application, any description, even though described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present disclosure. Where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list; and any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges as well as the endpoints of the range and equivalents.
Unless specifically limited otherwise, the term “alkyl”, as well as derivative terms such as “alkoxy”, “acyl” and “alkylthio”, as used herein, include within their scope straight chain, branched chain and cyclic moieties. Examples of alkyl groups are methyl, ethyl, 1-methylethyl, propyl, 1,1-dimethylethyl, and cyclo-propyl. Unless specifically stated otherwise, each alkyl and aryl group may be unsubstituted or substituted with one or more substituents selected from but not limited to halogen, hydroxy, sulfo, C1-C6 alkoxy, C1-C6 alkylthio, C1-C6 acyl, formyl, cyano, C6-C15 aryloxy or C6-C15 aryl, provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied. The term “halogen” or “halo” includes fluorine, chlorine, bromine and iodine, with fluorine being preferred.
The term “aryl” refers to a phenyl, indanyl or naphthyl group. The aryl group may comprise one or more alkyl groups, and are called sometimes in this case “alkylaryl”; for example may be composed of a cycloaromatic group and two C1-C6 groups (e.g. methyl or ethyl). The aryl group may also comprise one or more heteroatoms, e.g. N, O or S, and are called sometimes in this case “heteroaryl” group; these heteroaromatic rings may be fused to other aromatic systems. Such heteroaromatic rings include, but are not limited to furanyl, thienyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, isoxazolyl, oxazolyl, thiazolyl, isothiazolyl, pyridyl, pyridazyl, pyrimidyl, pyrazinyl and triazinyl ring structures. The aryl or heteroaryl substituents may be unsubstituted or substituted with one or more substituents selected from but not limited to halogen, hydroxy, C1-C6 alkoxy, sulfo, C1-C6 alkylthio, C1-C6 acyl, formyl, cyano, C6-C15 aryloxy or C6-C15 aryl, provided that the substituents are sterically compatible and the rules of chemical bonding and strain energy are satisfied.
As noted above, it was surprisingly discovered that the polymer compositions (PC) had improved retention of mechanical properties after aging in an aqueous solution at elevated temperatures. In some embodiments, the aqueous solution is an aqueous polyol solution or a brine solution. A polyol is an organic compound containing at least two hydroxyl groups. Polyols of interest herein include, but are not limited to, ethylene glycol, propylene glycol and diethylene glycol. In general, engine coolant utilizes an aqueous polyol solution that has a weight ratio of water to polyol (e.g. ethylene glycol) of from 99.9/0.1 to 50:50. A brine solution refers to a solution containing water and at least 3.5 wt % of NaCl, relative to the total weight of water and NaCl. In some embodiments, the brine solution has an NaCl concentration of up to 26 wt. %, relative to the total weight of water and NaCl. Retention of mechanical properties can be determined according to following formula: 100*(X1/X0), where X1 is the value of a given mechanical property after aging and X0 is the value of the mechanical property prior to aging (e.g. as molded). Unless explicitly stated otherwise, as used herein aging in an aqueous polyol solution refers to submerging the polymer composition (PC) in a 130° C., 50:50 ethylene glycol:water solution for 1000 hours. Similarly and unless explicitly stated otherwise, as used herein aging in a brine solution refers to submerging the polymer composition (PC) in a 130° C., 26 wt. % aqueous NaCl solution for 1000 hours.
In some embodiments, the polymer compositions (PC) has a tensile strength retention after aging in an aqueous polyol solution of at least 60%, at least 70%. In some embodiments, the polymer compositions (PC) has as tensile strength retention after aging in an aqueous polyol solution of no more than 100%, no more than 95%, no more than 90%, no more than 85% or no more than 80%. In some embodiments, the polymer composition (PC) has a tensile strength retention after aging in an aqueous polyol solution of from 60% to 100%, from 60% to 95%, from 60% to 90%, from 60% to 85%, from 60% to 80%, 70% to 100%, from 70% to 95%, from 70% to 90%, from 70% to 85%, or from 70% to 80%. In some embodiments, the polymer composition (PC) has tensile strength after aging in an aqueous polyol solution of at least 120 MPa, at least 130 MPa, at least 140 MPa or at least 150 MPa. In some embodiments, the polymer composition (PC) has a tensile strength after aging in an aqueous polyol solution of no more than 190 MPa, no more than 180 MPa, no more than 170 MPa, or no more than 160 MPa. In some embodiments, the polymer composition (PC) has a tensile strength after aging in an aqueous polyol solution of from 120 MPa to 190 MPa, from 130 MPa to 180 MPa, from 150 MPa to 170 MPa or from 150 MPa to 160 MPa. Tensile strength can be measured as described in the Examples section.
In some embodiments, the polymer composition (PC) has a flexural strength retention after aging in a brine solution of at least 85%, at least 90% or at least 95%. In some embodiments, the polymer composition (PC) has a flexural strength retention after aging in a brine solution of no more than 105%, no more than 100% or no more than 99%. In some embodiments, the polymer composition (PC) has a flexural strength retention after aging in a brine solution of from 85% to 105%, from 90% to 105%, from 95% to 105%, from 85% to 100%, from 90% to 100%, from 95% to 100%, from 85% to 99%, from 90% to 99% or from 95% to 99%. In some embodiments, the polymer composition (PC) has a flexural strength after aging in a brine solution of at least 120 MPa, at least 130 Mpa, at least 140 or at least 150 MPa. In some embodiments, the polymer composition (PC) has a flexural strength after aging in a brine solution of no more than 180 MPa, no more than 170 MPa or no more than 160 MPa. In some embodiments, the polymer composition (PC) has a flexural strength after aging in a brine solution of from 120 MPa, to 180 MPa, from 130 MPa to 180 MPa, from 140 MPa to 180 MPa, from 150 to 180 MPa, from 120 MPa, to 170 MPa, from 130 MPa to 170 MPa, from 140 MPa to 170 MPa, from 150 to 170 MPa, from 120 MPa, to 160 MPa, from 130 MPa to 160 MPa, from 140 MPa to 160 MPa or from 150 to 160 MPa. Flexural strength can be measured as described in the Examples section.
The polymer composition (PC) includes a polyamide (PA). The polyamide (PA) is derived from the polycondensation of monomers in a reaction mixture comprising: (1) a diamine component (A) comprising 20 mol % to 95 mol % of a C4 to C12 aliphatic diamine and 5 mol % to 80 mol % of a bis(aminoalkyl)cyclohexane, where mol % is relative to the total moles of each diamine monomer in the diamine component; and (2) a dicarboxylic acid component (B) comprising: 30 mol % to 100 mol % of terephthalic acid and 0 mol % to 70 mol %, preferably 1 mol % to 70 mol %, of a cyclohexane dicarboxylic acid, wherein mol % is relative to the total moles of each dicarboxylic acid monomer in the dicarboxylic acid component. However, it was surprisingly discovered that the incorporation of the bis(aminoalkyl)cyclohexane, or the specific combination of the bis(aminoalkyl)cyclohexane and the cyclohexanedicarboxylic acid, into semi-aromatic polyamides provides for impact-modified polymer compositions (PC) having improved retention of mechanical properties (e.g. tensile and flexural strength) after aging. The polyamides described herein have a glass transition temperature (“Tg”) of at least 145° C., melting temperature (“Tm”) of at least 295° C., and a heat of fusion (“ΔHf”) of at least 30 J/g.
The diamine component (A) includes all diamines in the reaction mixture, including 20 mol % to 95 mol % C4 to C12 aliphatic diamine and 5 mol % to 80 mol % of a bis(aminoalkyl)cyclohexane. When referring to the concentration of monomers in the diamine component (A), it will be understood that the concentration is relative to the total number of moles of all diamines in the diamine component (A), unless explicitly noted otherwise.
In some embodiments, the C4 to C12 aliphatic diamine is represented by the following formula:
H2N—R1—NH2, (1)
where R1 is a C4 to C12 alkyl group, preferably a C6 to C10 alkyl group. In some embodiments, the C4 to C12 aliphatic diamine is selected from the group consisting of 1,4-diaminobutane (putrescine), 1,5-diaminopentane (cadaverine), 2-methyl-1,5-diaminopentane, hexamethylenediamine (or 1,6-diaminohexane), 3-methylhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethyl-hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 2,2,7,7-tetramethyloctamethylenediamine, 1,9-diaminononane, 2-methyl-1,8-diaminooctane, 5-methyl-1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, and 1,12-diaminododecane. Preferably, the C4 to C12 aliphatic diamine is selected from the group consisting of 1,6-diaminohexane, 3-methylhexamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethyl-hexamethylenediamine, 1,9-diaminononane, 2-methyl-1,8-diaminooctane, 5-methyl-1,9-diaminononane, and 1,10-diaminodecane. Preferably, the C4 to C12 aliphatic diamine is a C5 to C10 aliphatic diamine or a C5 to C9 aliphatic diamine. Most preferably, the C4 to C12 aliphatic diamine is 1,6-diaminohexane.
In some embodiments, concentration of the C6 to C12 aliphatic diamine is from 25 mol % to 95 mol %, from 30 mol % to 95 mol %, from 35 mol % to 95 mol %, from 40 mol % to 95 mol %, from 45 mol % to 95 mol %, or from 50 mol % to 95 mol %. In some embodiments, concentration of the C6 to C12 diamine is from 20 mol % to 90 mol %, from 25 mol % to 90 mol %, from 30 mol % to 90 mol %, from 35 mol % to 90 mol %, from 40 mol % to 90 mol %, from 45 mol % to 90 mol %, or from 50 mol % to 90 mol %.
The bis(aminoalkyl)cyclohexane is represented by the following formula:
where R2 and R3 are independently selected C1 to C10 alkyls; Ri, at each location, is selected from the group consisting of an alkyl, an aryl, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, and a quaternary ammonium; and i is an integer from 0 to 10. The —R3—NH2 groups are relatively positioned in the meta position (1,3-) or the para position (1,4-). Preferably, i is 0 and R2 and R3 are both —CH2—. Most preferably, the bis(aminoalkyl)cyclohexane is selected from 1,3-bis(aminomethyl)cyclohexane (“1,3-BAC”) and 1,4-bis(aminomethyl)cyclohexane (“1,4-BAC”). Of course, the bis(aminoalkyl)cyclohexane can be in a cis or trans conformation. Accordingly, the diamine component (A) can include only the cis-bis(aminoalkyl)cyclohexane, only trans-bis(aminoalkyl)cyclohexane or a mixture of cis- and trans-bis(aminoalkyl)cyclohexane.
In some embodiments, the concentration of the bis(aminoalkyl)cyclohexane is from 5 mol % to 75 mol %, from 5 mol % to 70 mol %, from 5 mol % to 65 mol %, from 5 mol % to 60 mol %, from 5 mol % to 55 mol %, or from 5 mol % to 50 mol %. In some embodiments, the concentration of the bis(aminoalkyl)cyclohexane is from 10 mol % to 75 mol %, from 10 mol % to 70 mol %, from 10 mol % to 65 mol %, from 10 mol % to 60 mol %, from 10 mol % to 55 mol %, or from 10 mol % to 50 mol %, or from 20 mol % to 40 mol %.
As noted above, in some embodiments, the diamine component (A) includes one or more additional diamines. The additional diamines are distinct from the C4 to C12 aliphatic diamine and distinct from the bis(aminoalkyl)cyclohexane. In some embodiments, one, some, or all of the additional diamines are represented by Formula (1), each distinct from each other and distinct from the C4 to C12 aliphatic diamine. In some embodiments, the each additional diamine is selected from the group consisting of 1,2 diaminoethane, 1,2-diaminopropane, propylene-1,3-diamine, 1,3 diaminobutane, 1,4-diaminobutane, 1,5-diaminopentane, 2-methyl-1,5-diaminopentane, 1,6-diaminohexane, 3-methylhexamethylenediamine, 2,5 dimethylhexamethylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethyl-hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 2,2,7,7 tetramethyloctamethylenediamine, 1,9-diaminononane, 2-methyl-1,8-diaminooctane, 5-methyl-1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,13-diaminotridecane, 2,5-bis(aminomethyl)tetrahydrofuran and N,N-Bis(3-aminopropyl)methylamine. Included in this category are also cycloaliphatic diamine such as isophorone diamine, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis-p-aminocyclohexylmethane. In some embodiments, the diamine component is free of cycloaliphatic diamines others than the bis(aminoalkyl)cyclohexane. As used herein, free of a monomer (e.g. bis(aminoalkyl)cyclohexane) means that the concentration of the monomer in the corresponding component (e.g. the diamine component (A)) is less than 1 mol %, preferably less than 0.5 mol. %, more preferably less than 0.1 mol %, even more preferably less than 0.05 mol %, most preferably less than 0.01 mol %.
The dicarboxylic acid component (B) includes all dicarboxylic acids in the reaction mixture, including 30 mol % to 100 mol % of terephthalic acid and 0 mol % to 70 mol %, preferably from 1 mol % to 70 mol %, of a cyclohexanedicarboxylic acid. When referring to the concentration of monomers in the dicarboxylic acid component (B), it will be understood that the concentration is relative to number of moles of all dicarboxylic acids in the dicarboxylic acid component (A), unless explicitly noted otherwise.
In some embodiments, the concentration of the terephthalic acid is from 35 mol % to 100 mol %, from 35 mol % to 100 mol %, from 40 mol % to 100 mol %, from 45 mol % to 100 mol %, or from 50 mol % to 100 mol %. In some embodiments, the concentration of the terephthalic acid is from 30 mol % to 99 mol %, from 35 mol % to 99 mol %, from 40 mol % to 99 mol %, from 45 mol % to 99 mol % or from 50 mol % to 99 mol %. In some embodiments, the concentration of the terephthalic acid is from 30 mol % to 95 mol %, from 35 mol % to 97 mol %, from 40 mol % to 97 mol %, from 45 mol % to 97 mol % or from 50 mol % to 97 mol %.
The cyclohexanedicarboxylic acid is represented by the following formula:
where Rj is selected from the group consisting of an alkyl, an aryl, an alkali or alkaline earth metal sulfonate, an alkyl sulfonate, and a quaternary ammonium; and j is an integer from 0 to 10. The explicit —COOH groups are relatively positioned in the meta position (1,3-) or the para position (1,4-), preferably the para position. Preferably, the cyclohexanedicarboxylic acid is 1,4-cyclohexanedicarboxylic acid (“CHDA”) (j is 0). Of course, the cyclohexanedicarboxylic acid can be in a cis or trans conformation. Accordingly, the dicarboxylic acid component (B) can include only the cis-cyclohexanedicarboxylic acid, only trans-cyclohexanedicarboxylic acid or a mixture of cis- and trans-cyclohexanedicarboxylic acid.
In some embodiments, the concentration of the cyclohexanedicarboxylic acid is from 1 mol % to 70 mol %, from 1 mol % to 65 mol %, from 1 mol %, to 60 mol %, from 1 mol % to 55 mol %, or from 1 mol % to 50 mol. %.
As noted above, in some embodiments, the dicarboxylic acid component (B) includes one or more additional dicarboxylic acids. Each additional dicarboxylic acid is distinct from each other and distinct from the terephthalic acid and the cyclohexanedicarboxylic acid. In some embodiments, one, some, or all of the additional dicarboxylic acids are represented by Formula (3), each distinct from each other and distinct from the cyclohexanedicarboxylic acid.
In some embodiments, the one or more additional dicarboxylic acids are independently selected from the group consisting of C4 to C12 aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and cycloaliphatic dicarboxylic acids. Examples of desirable C4 to C10 aliphatic dicarboxylic acids include, but are not limited to, succinic acid [HOOC—(CH2)2—COOH], glutaric acid [HOOC—(CH2)3—COOH], 2,2-dimethyl-glutaric acid [HOOC—C(CH3)2—(CH2)2—COOH], adipic acid [HOOC—(CH2)4—COOH], 2,4,4-trimethyl-adipic acid [HOOC—CH(CH3)—CH2—C(CH3)2—CH2—COOH], pimelic acid [HOOC—(CH2)5—COOH], suberic acid [HOOC—(CH2)6—COOH], azelaic acid [HOOC—(CH2)7—COOH], sebacic acid [HOOC—(CH2)8—COOH], 1,12-dodecanedioic acid [HOOC—(CH2)10—COOH].
Examples of desirable aromatic dicarboxylic acids include, but are not limited to, phthalic acids, including isophthalic acid (IA), naphthalenedicarboxylic acids (e.g. naphthalene-2,6-dicarboxylic acid), 4,4′ bibenzoic acid, 2,5-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, 2,2-bis(4-carboxyphenyl)propane, 2,2-bis(4-carboxyphenyl)hexafluoropropane, 2,2-bis(4-carboxyphenyl)ketone, 4,4′-bis(4-carboxyphenyl)sulfone, 2,2-bis(3-carboxyphenyl)propane, 2,2-bis(3-carboxyphenyl)hexafluoropropane, 2,2-bis(3-carboxyphenyl)ketone, bis(3-carboxyphenoxy)benzene.
Examples of desirably cycloaliphatic dicarboxylic acids include, but are not limited to, cyclopropane-1,2-dicarboxylic acid, 1-methylcyclopropane-1,2-dicarboxylic acid, cyclobutane-1,2-dicarboxylic acid, tetrahydrofuran-2,5-dicarboxylic acid, 1,3-adamantanedicarboxylic acid.
In some embodiments in which the polyamide (PA) includes one or more additional dicarboxylic acids, the total concentration of the one or more additional dicarboxylic acids is no more than 20 mol. %.
The polyamide (PA) formed from the polycondensation of the monomers in the diamine component and dicarboxylic acid component, as described above, includes recurring units RPA1 and RPA2, represented by the following formulae, respectively:
and additionally, when the cyclohexanedicarboxylic acid is present in the dicarboxylic acid component (B), recurring units RPA3 and RPA4 represented by the following formulae, respectively:
where R1 to R3, Ri, Rj, i and j are as defined above. The person of ordinary skill in the art will recognize that recurring unit RPA1 is formed from the polycondensation of the C4 to C12 aliphatic diamine with the terephthalic acid, recurring unit RPA3 is formed from the polycondensation of the C4 to C12 aliphatic diamine with the cyclohexane dicarboxylic acid, recurring unit RPA2 is formed from the polycondensation of the bis(aminoalkyl)cyclohexane with the terephthalic acid, and recurring unit RPA4 is formed from the polycondensation of the bis(aminoalkyl)cyclohexane with the cyclohexanedicarboxylic acid. In some embodiments, R1 is —(CH2)—m, where m is from 5 to 10, preferably from 5 to 9, most preferably 6. Additionally or alternatively, in some embodiments R2 and R3 are both —CH2—, and i and j are both zero. In some embodiments, the bis(aminalkyl)cyclohexane is 1,3-bis(aminomethyl)cyclohexane and the cyclohexanedicarboxylic acid is 1,4-cyclohexane dicarboxylic acid.
In some embodiments, the total concentration of recurring units RPA1 and RPA2 is at least 50 mol %, at least 60 mol %, at least 70 mol %, at least 80 mol %, at least 90 mol %, at least 95 mol %, at least 97 mol %, at least 98 mol %, at least 99 mol % or at least 99.5 mol %. In some embodiments in which the optional cyclohexanedicarboxylic acid is present in the dicarboxylic acid component (B), the total concentration of recurring units RPA1 to RPA4 is at least 50 mol %, at least 60 mol %, at least 70 mol %, at least 80 mol %, at least 90 mol %, at least 95 mol %, at least 97 mol %, at least 98 mol %, at least 99 mol % or at least 99.5 mol %. When referring to mol % of a recurring unit, it will be understood that the concentration is relative to the total number of recurring units in the indicated polymer, unless explicitly noted otherwise.
The polyamides (PA) are semi-crystalline polyamides. As used herein, a semi-crystalline polyamide is a polyamide that has a heat of fusion (“ΔHf”) of at least 5 Joules per gram (“J/g”). In some embodiments, the polyamides (PA) described herein have a ΔHf of at least 30 J/g, or at least 35 J/g. Additionally or alternatively, in some embodiments the polyamide (PA) has a ΔHf of no more than 60 J/g or no more than 55 J/g. In some embodiments, the polyamide (PA) has a ΔHf of from 30 J/g to 60 J/g or from 35 J/g to 60 J/g, from 30 J/g to 55 J/g, or from 35 J/g to 55 J/g. ΔHf can be measured according to ASTM D3418 using a heating rate of 20° C./minute.
The polyamide (PA) has a Tg of at least 145° C., preferably at least 150° C. In some embodiments, the polyamide (PA) has a Tg of no more than 190° C., no more than 180° C., or no more than 170° C. In some embodiments, the polyamide (PA) has a Tg of from 145° C. to 190° C., from 145° C. to 180° C., from 145° C. to 170° C., from 150° C. to 190° C., from 150° C. to 180° C., or from 150° C. to 170° C. Tg can be measured according to ASTM D3418.
The polyamide (PA) has a Tm of at least 295° C., preferably at least 300° C. In some embodiments the polyamide (PA) has a Tm of no more than 360° C., no more than 350° C., or no more than 340° C. In some embodiments, the polyamide (PA) has a Tm of from 295° C. to 360° C., from 295° C. to 350° C., from 295° C. to 340° C., 300° C. to 360° C., from 300° C. to 350° C., or from 300° C. to 340° C. Tm can be measured according to ASTM D3418.
In some embodiments, the polyamide (PA) has a number average molecular weight (“Mn”) ranging from 1,000 g/mol to 40,000 g/mol, for example from 2,000 g/mol to 35,000 g/mol, from 4,000 to 30,000 g/mol, or from 5,000 g/mol to 20,000 g/mol. The number average molecular weight Mn can be determined by gel permeation chromatography (GPC) using ASTM D5296 with polystyrene standards.
The polyamide (PA) described herein can be prepared by any conventional method adapted to the synthesis of polyamides and polyphthalamides. Preferentially, the polyamide (PA) is prepared by reacting (by heating) the monomers in presence of less than 60 wt. % of water, preferentially less than 50 wt. %, up to a temperature of at least Tm+10° C., Tm being the melting temperature of the polyamide (PA), where wt. % is relative to the total weight of the reaction mixture.
The polyamide (PA) described herein can for example be prepared by thermal polycondensation (also referred to as polycondensation or condensation) of aqueous solution of monomers and comonomers. In one embodiment, the polyamide (PA) is formed by reacting, in the reaction mixture, at least the C4 to C12 aliphatic diamine, the bis(aminoalkyl)cyclohexane, the terephthalic acid, and, if present in the dicarboxylic acid component (B), the cyclohexanedicarboxylic acid. In some embodiments, the total number of moles of diamines in the reaction mixture is substantially equimolar to the total number of moles of dicarboxylic acids in the reaction mixture. As used herein, substantial equimolar denotes a value that is ±15% of the indicated number of moles. For example, in the context of the diamine and dicarboxylic acid concentrations in the reaction mixture, total number of moles of diamines in the reaction mixture is ±15% of the total number of moles of dicarboxylic acids in the reaction mixture. The polyamides (PA) may contain a chain limiter, which is a monofunctional molecule capable of reacting with the amine or carboxylic acid moiety, and is used to control the molecular weight of the polyamide (PA). For example, the chain limiter can be acetic acid, propionic acid, benzoic acid and/or benzylamine. A catalyst can also be used. Examples of catalyst are phosphorous acid, ortho-phosphoric acid, meta-phosphoric acid, alkali-metal hypophosphite such as sodium hypophosphite and phenylphosphinic acid. A stabilizer, such as a phosphite, may also be used.
The polymer composition (PC) includes the polyamide (PA) and a reactive impact modifier. In some embodiments, the polymer compositions can include one or more optional components selected from the group consisting of reinforcing agents and additives. Additives include, but are not limited to, impact modifiers, plasticizers, colorants, pigments (e.g. black pigments such as carbon black and nigrosine), antistatic agents, dyes, lubricants (e.g. linear low density polyethylene, calcium or magnesium stearate or sodium montanate), thermal stabilizers, light stabilizers, flame retardants, nucleating agents, antioxidants, acid scavengers, and other processing aids.
In some embodiments, the polyamide (PA) concentration in the polymer composition (PC) is at least 5 wt. % or at least 10 wt. %. In some embodiments, the polyamide (PA) concentration in the polymer composition (PC) is no more than 80 wt. % or no more than 70 wt. %. In some embodiments, the polyamide (PA) concentration in the polymer composition (PC) is from 5 wt. % to 80 wt. % or from 10 wt. % to 70 wt. %.
Polymer compositions (PC) includes a reactive impact modifier (IM). An impact modifier is generally a low Tg, with a Tg for example below room temperature, below 0° C. o even below −25° C. As a result of its low Tg, the tougheners are typically elastomeric at room temperature. The polymer backbone of the impact modifier can be selected from elastomeric backbones comprising polyethylenes and copolymers thereof, e.g. terpolymers of ethylene, acrylic ester and glycidyl methacrylate, copolymers of ethylene and butyl ester acrylate; copolymers of ethylene, butyl ester acrylate and glycidyl methacrylate; ethylene-maleic anhydride copolymers; ethylene-butene; ethylene-hexene; ethylene-octene; polypropylenes and copolymers thereof; polybutenes; polyisoprenes; ethylene-propylene-rubbers (EPR); ethylene-propylene-diene monomer rubbers (EPDM); ethylene-acrylate rubbers; butadiene-acrylonitrile rubbers, ethylene-acrylic acid (EAA), ethylene-vinylacetate (EVA); acrylonitrile-butadiene-styrene rubbers (ABS), block copolymers styrene ethylene butadiene styrene (SEBS); block copolymers styrene butadiene styrene (SBS); core-shell elastomers of methacrylate-butadiene-styrene (MBS) type, or mixture of one or more of the above.
The reactive impact modifier (IM) is a functionalized impact modifier. The molecule that functionalizes the impact modifier includes a group that reacts with the polyamide to form a covalent bond. In some embodiments, the group reacts with amine groups on the polyamide. The reactive impact modifier (IM) can formed by copolymerization of monomers which include the functionalization or by grafting the impact modifier backbone with the functionalization molecule. In some embodiments, the impact modifier is anhydride functionalized, carboxyl functionalized, acrylate functionalized, epoxy functionalized, amino functionalized, or vinyl functionalized.
In some embodiments, the reactive impact modifier (IM) is selected from the group consisting of terpolymers of ethylene, acrylic ester and glycidyl methacrylate, copolymers of ethylene and butyl ester acrylate; copolymers of ethylene, butyl ester acrylate and glycidyl methacrylate; ethylene-maleic anhydride copolymers; EPR functionalized with maleic anhydride; styrene copolymers functionalized with maleic anhydride; EPDM functionalized with maleic anhydride, SEBS copolymers functionalized with maleic anhydride; styrene-acrylonitrile copolymers functionalized with maleic anhydride; ABS copolymers functionalized with maleic anhydride. Alternatively, the reactive impact modifier may be selected from any in the preceding list with epoxide functionalization in place of maleic anhydride. Excellent results were obtained with maleic anhydride grafted SEBS copolymers.
In some embodiments, the toughener concentration in the polymer composition (PC) is at least 1 wt. %, at least 2 wt. % or at least 3 wt. %. In some embodiments, the toughener concentration in the polymer composition (PC) is no more than 20 wt. %, no more than 15 wt. % or no more than 10 wt. %. In some embodiments, the toughener concentration is the polymer composition (PC) is from 1 wt. % to 20 wt. %, from 2 wt. % to 15 wt. % or from 3 wt. to 10 wt. %.
In some embodiments, the polymer composition (PC) includes a reinforcing agent. A large selection of reinforcing agents, also called reinforcing fibers or fillers may be added to the polymer composition (PC). In some embodiments, reinforcing agent is selected from mineral fillers (including, but not limited to, talc, mica, kaolin, calcium carbonate, calcium silicate, magnesium carbonate), glass fibers, carbon fibers, synthetic polymeric fibers, aramid fibers, aluminum fibers, titanium fibers, magnesium fibers, boron carbide fibers, rock wool fibers, steel fibers and wollastonite.
In general, reinforcing agents are fibrous reinforcing agents or particulate reinforcing agents. A fibrous reinforcing agent refers to a material having length, width and thickness, wherein the average length is significantly larger than both the width and thickness. Generally, such a material has an aspect ratio, defined as the average ratio between the length and the largest of the width and thickness of at least 5, at least 10, at least 20 or at least 50. In some embodiments, the fibrous reinforcing agent (e.g. glass fibers or carbon fibers) has an average length of from 3 mm to 50 mm. In some such embodiments, the fibrous reinforcing agent has an average length of from 3 mm to 10 mm, from 3 mm to 8 mm, from 3 mm to 6 mm, or from 3 mm to 5 mm. In alternative embodiments, fibrous reinforcing agent has an average length of from 10 mm to 50 mm, from 10 mm to 45 mm, from 10 mm to 35 mm, from 10 mm to 30 mm, from 10 mm to 25 mm or from 15 mm to 25 mm. The average length of the fibrous reinforcing agent can be taken as the average length of the fibrous reinforcing agent prior to incorporation into the polymer composition (PC) or can be taken as the average length of the fibrous reinforcing agent in the polymer composition (PC).
Among fibrous reinforcing agents, glass fibers are preferred. Glass fibers are silica-based glass compounds that contain several metal oxides which can be tailored to create different types of glass. The main oxide is silica in the form of silica sand; the other oxides such as calcium, sodium and aluminum are incorporated to reduce the melting temperature and impede crystallization. The glass fibers can be added as endless fibers or as chopped glass fibers. The glass fibers have generally an equivalent diameter of 5 to 20 preferably of 5 to 15 μm and more preferably of 5 to 10 μm. All glass fiber types, such as A, C, D, E, M, S, R, T glass fibers (as described in chapter 5.2.3, pages 43-48 of Additives for Plastics Handbook, 2nd ed, John Murphy), or any mixtures thereof or mixtures thereof may be used.
E, R, S and T glass fibers are well known in the art. They are notably described in Fiberglass and Glass Technology, Wallenberger, Frederick T.; Bingham, Paul A. (Eds.), 2010, XIV, chapter 5, pages 197-225. R, S and T glass fibers are composed essentially of oxides of silicon, aluminium and magnesium. In particular, those glass fibers comprise typically from 62-75 wt. % of SiO2, from 16-28 wt. % of Al2O3 and from 5-14 wt. % of MgO. On the other hand, R, S and T glass fibers comprise less than 10 wt. % of CaO.
In some embodiments, the glass fiber is a high modulus glass fiber. High modulus glass fibers have an elastic modulus of at least 76, preferably at least 78, more preferably at least 80, and most preferably at least 82 GPa as measured according to ASTM D2343. Examples of high modulus glass fibers include, but are not limited to, S, R, and T glass fibers. A commercially available source of high modulus glass fibers is S-1 and S-2 glass fibers from Taishan and AGY, respectively.
The morphology of the glass fiber is not particularly limited. As noted above, the glass fiber can have a circular cross-section (“round glass fiber”) or a non-circular cross-section (“flat glass fiber”). Examples of suitable flat glass fibers include, but are not limited to, glass fibers having oval, elliptical and rectangular cross sections. In some embodiments in which the polymer composition includes a flat glass fiber, the flat glass fiber has a cross-sectional longest diameter of at least 15 μm, preferably at least 20 μm, more preferably at least 22 μm, still more preferably at least 25 μm. Additionally or alternatively, in some embodiments, the flat glass fiber has a cross-sectional longest diameter of at most 40 μm, preferably at most 35 μm, more preferably at most 32 μm, still more preferably at most 30 μm. In some embodiments, the flat glass fiber has a cross-sectional diameter was in the range of 15 to 35 μm, preferably of 20 to 30 μm and more preferably of 25 to 29 μm. In some embodiments, the flat glass fiber has a cross-sectional shortest diameter of at least 4 μm, preferably at least 5 μm, more preferably at least 6 μm, still more preferably at least 7 μm. Additionally or alternatively, in some embodiments, the flat glass fiber has a cross-sectional shortest diameter of at most 25 μm, preferably at most 20 μm, more preferably at most 17 μm, still more preferably at most 15 μm. In some embodiments, the flat glass fiber has a cross-sectional shortest diameter was in the range of 5 to 20 preferably of 5 to 15 μm and more preferably of 7 to 11 μm.
In some embodiments, the flat glass fiber has an aspect ratio of at least 2, preferably at least 2.2, more preferably at least 2.4, still more preferably at least 3. The aspect ratio is defined as a ratio of the longest diameter in the cross-section of the glass fiber to the shortest diameter in the same cross-section. Additionally or alternatively, in some embodiments, the flat glass fiber has an aspect ratio of at most 8, preferably at most 6, more preferably of at most 4. In some embodiments, the flat glass fiber has an aspect ratio of from 2 to 6, and preferably, from 2.2 to 4. In some embodiments, in which the glass fiber is a round glass fiber, the glass fiber has an aspect ratio of less than 2, preferably less than 1.5, more preferably less than 1.2, even more preferably less than 1.1, most preferably, less than 1.05. Of course, the person of ordinary skill in the art will understand that regardless of the morphology of the glass fiber (e.g. round or flat), the aspect ratio cannot, by definition, be less than 1.
In some embodiments, the reinforcing agent (e.g. glass or carbon fibers) concentration in the polymer composition (PC) is at least 5 wt. %, at least 10 wt. %, at least 15 wt. % or at least 20 wt. %. In some embodiments, the reinforcing agent concentration in the polymer composition (PC) is no more 70 wt. %, no more than 65 wt. % or no more than 60 wt. %. In some embodiments, the reinforcing agent concentration in the polymer composition (PC) is from 5 wt. % to 70 wt. %, from 10 wt. % to 70 wt. %, from 10 wt. % to 65 wt. %, from 10 wt. % to 60 wt. %, from 15 wt. % to 60 wt. %, or from 20 wt. % to 60 wt. %.
In some embodiments, the halogen-free flame retardant is an organophosphorous compound selected from the group consisting of phosphinic salts (phosphinates), diphosphinic salts (diphosphinates) and condensation products thereof. Preferably, the organophosphorous compound is selected from the group consisting of phosphinic salt (phosphinate) of the formula (I), a diphosphinic salt (diphosphinate) of the formula (II) and condensation products thereof:
wherein, R1, R2 are identical or different and each of R1 and R2 is a hydrogen or a linear or branched C1-C6 alkyl group or an aryl group; R3 is a linear or branched C1-C10 alkylene group, a C6-C10 arylene group, an alkyl-arylene group, or an aryl-alkylene group; M is selected from calcium ions, magnesium ions, aluminum ions, zinc ions, titanium ions, and combinations thereof; m is an integer of 2 or 3; n is an integer of 1 or 3; and x is an integer of 1 or 2.
Preferably, R1 and R2 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, and phenyl; R3 is selected from methylene, ethylene, n-propylene, isopropylene, n-butylene, tert-butylene, n pentylene, n-octylene, n-dodecylene, phenylene, naphthylene, methylphenylene, ethylphenylene, tert-butylphenylene, methylnaphthylene, ethylnaphthylene, tert-butylnaphthylene, phenylmethylene, phenylethylene, phenylpropylene, and phenylbutylene; and M is selected from aluminum and zinc ions.
Phosphinates are preferred as organophosphorous compound. Suitable phosphinates have been described in U.S. Pat. No. 6,365,071, incorporated herein by reference. Particularly preferred phosphinates are aluminum phosphinates, calcium phosphinates, and zinc phosphinates. Excellent results were obtained with aluminum phosphinates. Among aluminum phosphinates, aluminium ethylmethylphosphinate and aluminium diethylphosphinate and combinations thereof are preferred.
In some embodiments, the polymer composition (PC) further includes an acid scavenger, most desirably in embodiments incorporating a halogen free flame retardant. Acid scavengers include, but are not limited to, silicone; silica; boehmite; metal oxides such as aluminum oxide, calcium oxide iron oxide, titanium oxide, manganese oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, cobalt oxide, bismuth oxide, chromium oxide, tin oxide, antimony oxide, nickel oxide, copper oxide and tungsten oxide; metal powder such as aluminum, iron, titanium, manganese, zinc, molybdenum, cobalt, bismuth, chromium, tin, antimony, nickel, copper and tungsten; and metal salts such as barium metaborate, zinc carbonate, magnesium carbonate, calcium carbonate, and barium carbonate. In some embodiments, in which the polymer composition (PC) includes an acid scavenger, the acid scavenger concentration is from 0.01 wt. % to 5 wt. %, from 0.05 wt. % to 4 wt. %, from 0.08 wt. % to 3 wt. %, from 0.1 wt. % to 2 wt. %, from 0.1 wt. % to 1 wt. %, from 0.1 wt. % to 0.5 wt. % or from 0.1 wt. % to 0.3 wt. %.
In some embodiments, the total additive concentration in the polymer composition (PC) is at least 0.1 wt. %, at least 0.2 wt. % or at least 0.3 wt. %. In some embodiments, the total additive concentration in the polymer composition (PC) is no more than 20 wt. %, no more than 15 wt. %, no more than 10 wt. %, no more than 7 wt. % or no more than 5 wt. %. In some embodiments, the total additive concentration in the polymer composition (PC) is from 0.1 wt. % to 20 wt. %, from 0.1 wt. % to 15 wt. %, from 0.1 wt. % to 10 wt. %, from 0.2 wt. % to 7 wt. % or from 0.3 wt. to 5 wt. %.
In some embodiments, the polymer composition (PC) further includes one or more additional polymers. In some such embodiments, at least one of the additional polymers is a semi-crystalline or amorphous polyamides, such as aliphatic polyamides, semi-aromatic polyamides, and more generally a polyamide obtained by polycondensation between an aromatic or aliphatic saturated diacid and an aliphatic saturated or aromatic primary diamine, a lactam, an amino-acid or a mixture of these different monomers.
The invention further pertains to a method of making the polymer composition (PC). The method involves melt-blending the polyamide (PA), the reactive impact modifier (IM) and any optional components (e.g. reinforcing agent).
Any melt-blending method may be used for mixing polymeric ingredients and non-polymeric ingredients in the context of the present invention. For example, polymeric ingredients and non-polymeric ingredients may be fed into a melt mixer, such as single screw extruder or twin screw extruder, agitator, single screw or twin screw kneader, or Banbury mixer, and the addition step may be addition of all ingredients at once or gradual addition in batches. When the polymeric ingredient and non-polymeric ingredient are gradually added in batches, a part of the polymeric ingredients and/or non-polymeric ingredients is first added, and then is melt-mixed with the remaining polymeric ingredients and non-polymeric ingredients that are subsequently added, until an adequately mixed composition is obtained. If a reinforcing agent presents a long physical shape (for example, long fibers as well as continuous fibers), drawing extrusion or pultrusion may be used to prepare a reinforced composition.
The present invention also relates to articles comprising the polymer composition (PC). At least in part due to the improved mechanical retention after aging in aqueous polyol solution or brine solution, the polymer compositions (PC) are desirably incorporated into any article that is exposed elevated temperatures and aqueous polyol solutions or brine solutions during their intended use.
In some embodiments, the article is selected from the group consisting of automotive components, marine components, and aerospace components. In some embodiments, the article is selected from the group consisting of fluid inlet/outlet ports, fluid inlet/outlet valves, fluid pump housings, fluid pump impellers, fluid hose connectors, fluid hoses, fluid reservoirs and fluid valves, where the fluid is an aqueous polyol solution, preferably an aqueous solution of ethylene glycol, propylene glycol or diethylene glycol. The polymer compositions (PC) are even further advantageously incorporated into such articles when such articles are used within engine bays (e.g. exposed to elevated temperatures).
In some embodiments, the article is selected from subterranean and sub-sea oil and gas components. In some embodiments, the article is selected from a sucker rod guide or other polymeric components in artificial lift systems. The sucker rod guides can be overmolded onto the sucker rod, adhered to the sucker rod, or a snap-on design to be installed in the field.
In some embodiments, the article is molded from the polymer composition (PC) by any process adapted to thermoplastics, e.g. extrusion, injection molding, blow molding, rotomolding or compression molding. The polymer composition (C) may also be used in overmolding pre-formed shapes to build hybrid structures.
In some embodiments, the article is printed from the polymer composition (PC) by a process including a step of extruding the polymer composition (PC), which is for example in the form of a filament, or including a step of laser sintering the polymer composition (PC), which is in this case in the form of a powder.
The present invention also relates to a method for manufacturing a three-dimensional (3D) object with an additive manufacturing system, including: providing a part material including the polymer composition (PC), and printing layers of the three-dimensional object from the part material.
The polymer composition (PC) can therefore be in the form of a thread or a filament to be used in a process of 3D printing, e.g. Fused Filament Fabrication, also known as Fused Deposition Modelling (“FDM”).
The polymer composition (PC) can also be in the form of a powder, for example a substantially spherical powder, to be used in a process of 3D printing, e.g. Selective Laser Sintering (“SLS”).
The present invention relates to the use of the polymer composition (PC) or articles for manufacturing an automotive component, marine component or an aerospace component, as described above. The present invention also relates to the use of the polymer composition (PC) or articles for manufacturing articles used in oil and gas recovery as described above. The present invention also relates to the use of the polymer composition (PC) for 3D printing an object.
The present examples demonstrate the synthesis, thermal performance, and mechanical performance of the polyamides.
The raw materials used to form the samples as provided below:
This example demonstrates the synthesis of Polyamide 1.
PA 1 was prepared in an autoclave reactor equipped with a distillate line fitted with a pressure control valve. The reactor was charged with 498 g of 70% hexamethylenediamine, 165 g of 1,3-bis(aminomethyl)cyclohexane, 635 g of terephthalic acid, 20 g of 1,4-cyclohexanedicarboxylic acid, 355 g of deionized water, 7.2 g of glacial acetic acid and 0.32 g of phosphorus acid. The reactor was sealed, purged with nitrogen and heated to 260° C. The steam generated was slowly released to keep the internal pressure at 120 psig. The temperature was increased to 335° C. The reaction mixture was kept at 335° C. for 60 minutes while the reactor pressure was reduced to atmospheric. The polymer was discharged from the reactor and used in the preparation of the compound formulations.
This example demonstrates the mechanical performance of the polymer compositions.
To demonstrate mechanical performance, polymer compositions were formed by melt blending the polymer resins with various additives in an extruder. The polymer compositions were then molded into test samples and mechanical properties (tensile and flexural properties) were tested prior to (“as molded”) and subsequent to (“after aging”) test sample aging in an aqueous polyol solution (submerging the test sample in a 130° C., 50:50 ethylene glycol:water solution for 1000 hours) or aging in a brine solution (submerging the test sample in a 130° C., 26 wt. % aqueous NaCl solution for 1000 hours). Tensile strength was measured according to ISO 527-2 on dumbbell-shaped, ISO type 1A tensile specimens with the following nominal dimensions: full length of 170 mm, gauge length of 75 mm, parallel section length of 80 mm, parallel section width of 10 mm, grip section width of 20 mm, and thickness of 4 mm. Flexural strength was measured according to ISO 178 on standard, ISO flexural specimens with the following nominal dimensions: length of 80 mm, width of 10 mm, and thickness of 4 mm. Table 1 displays sample parameters, Tables 2 displays the results of tensile strength measurements after aging in aqueous polyol solution and Table 3 displays the results of flexural strength measurements after aging in brine solution. In the Tables, “E” refers to an example and “CE” refers to a counter example. All values in Table 1 are reported in wt. %.
Referring to Table 2, the samples including PA1 surprisingly had increased retention of tensile strength, as well as increased values of tensile strength, after aging, relative to the samples including PA2 and PA4. For example E1 had significantly improved tensile strength retention relative to CE1 and CE2 (as well as improved tensile strength after aging).
Referring to Table 3, the samples including PA surprisingly had increased retention of flexural strength, and similar or improved flexural strength, after heat aging. As with tensile strength, E1 had improved retention of flexural strength relative CE3 to CE7. Additionally, after heat aging, E1 had similar flexural strength relative to CE-1, and improved flexural strength relative to CE4 to CE7
The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the inventive concepts. In addition, although the present invention is described with reference to particular embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention. Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20185587.1 | Jul 2020 | EP | regional |
The present application claims priority to U.S. provisional patent application No. 63/021,107, filed on May 7, 2020, and to European patent application no. 20185587.1, filed on Jul. 14, 2020, both of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/062079 | 5/6/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63021107 | May 2020 | US |
