FOAMED POLYMER COMPOSITIONS INCLUDING A NANOSTRUCTURED FLUOROPOLYMER

A foamed polymer composition includes a matrix polymer component, and from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof. The matrix polymer component includes polybutylene terephthalate (PBT), polyetherimide (PEI), polyethylene terephthalate (PET), polycarbonate (PC), poly(p-phenylene oxide) (PPO), polystyrene (PS), polyphenylene sulfide (PPS), polypropylene (PP), polyamide (PA), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), copolymers thereof, or a combination thereof. Methods for forming foamed polymer compositions, including core-back molding methods and extrusion foaming methods, are also described.

FIELD OF THE DISCLOSURE

The present disclosure relates to foamed polymer compositions, and in particular to foamed polymer compositions including a nanostructured fluoropolymer.

BACKGROUND OF THE DISCLOSURE

For a number of polymer processing methods a certain melt strength is required. This can be achieved by tailoring the molecular weight distribution and the molecular architecture, such as by introducing branches. A drawback of this approach is that for each resin specific chemistries need to be developed, which may not be economically attractive. Another method is to use an anisotropic (nano) additive with a high aspect ratio. It has been demonstrated that by using polytetrafluoroethylene (PTFE) the melt strength of several resins can be increased. The efficiency of these additives is a relevant characteristic from a technological and economic point of view.

Polymer processing methods that are known to benefit from an increased melt strength are foaming, melt impregnation of carbon and glass fibers (short, long and continuous), film blow molding, thermoforming, film extrusion with (un)filled resins. Numerous processes exist to make polymeric foams: extrusion foaming, foam injection molding, bead foaming, and batch foaming. In each of these processes either chemical or physical blowing agents can be used. Examples of physical blowing agents include nitrogen, carbon dioxide and hydrocarbons (e.g., pentane, isopentane, cyclopentane). Chemical blowing agents include isocyanate and water for polyurethane, azodicarbonamide for vinyl, hydrazine and other nitrogen-based materials for thermoplastic and elastomeric foams, and sodium bicarbonate for thermoplastic foams. Gaseous products and other byproducts are formed by a chemical reaction of the chemical blowing agent, promoted by the heat of the foam production process or a reacting polymer's exothermic heat. In addition, mixtures of chemical/physical blowing agents might be used.

In each of these foaming processes several steps exist to control the cell size distribution and the properties of such foamed products, i.e., nucleation of the cells, expansion of the cells and fixation of the foam structure. This can lead to open-cell or closed-cell foams.

Next to the foam nucleation step, a very important parameter in the foaming processes, i.e., extrusion foaming, foam injection molding, bead foaming, or batch foaming, is the melt strength of the materials to control and stabilize the expansion of the foam, thereby controlling the final density and properties of the foam. The melt strength can be improved by introducing branches on the polymer backbone as done for, e.g., low density polyethylene (LDPE), branched polypropylene (PP) or polyethylene terephthalate (PET) by using specific chain extender/branching agents, or by using specific additives with a certain aspect ratio higher than 1. The dispersion/distribution of these fillers is important.

Depending on the preferred route to make foams, i.e. extrusion foaming, foam injection molding, and batch foaming, different resins with a range of additives need to be used/optimized and the processing parameters need to be optimized. A universal approach is still desirable.

These and other shortcomings are addressed by aspects of the disclosure

SUMMARY

Aspects of the disclosure relate to a foamed polymer composition including:

from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof.

Aspects of the disclosure further relate to methods for making a foamed polymer composition, including:

forming a mixture including a matrix polymer component and from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof;

melting the mixture;

injecting the melted mixture into a mold; and

reducing pressure and/or temperature on the mixture to form the foamed polymer composition.

Further aspects of the disclosure relate to methods for making a foamed polymer composition, including:

forming a mixture including a matrix polymer component and from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof;

melting the mixture; and

extruding the mixture in the presence of a blowing agent to introduce the blowing agent into the mixture and form the foamed polymer composition.

DETAILED DESCRIPTION

The present disclosure can be understood more readily by reference to the following detailed description of the disclosure and the Examples included therein. In various aspects, the present disclosure pertains to foamed polymer compositions including: a matrix polymer component and from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof. The matrix polymer component includes polybutylene terephthalate (PBT), polyetherimide (PEI), polyethylene terephthalate (PET), polycarbonate (PC), poly(p-phenylene oxide) (PPO), polystyrene (PS), polyphenylene sulfide (PPS), polypropylene (PP), polyamide (PA), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high density polyethylene (HDPE), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), copolymers thereof, or a combination thereof.

Before the present compounds, compositions, articles, systems, devices, and/or methods are disclosed and described, it is to be understood that they are not limited to specific synthetic methods unless otherwise specified, or to particular reagents unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

Various combinations of elements of this disclosure are encompassed by this disclosure, e.g., combinations of elements from dependent claims that depend upon the same independent claim.

Definitions

As used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a nanostructured fluoropolymer” includes mixtures of two or more nanostructured fluoropolymers.

As used herein, the term “combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.

Ranges can be expressed herein as from one value (first value) to another value (second value). When such a range is expressed, the range includes in some aspects one or both of the first value and the second value. Similarly, when values are expressed as approximations, by use of the antecedent ‘about,’ it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as “about” that particular value in addition to the value itself. For example, if the value “10” is disclosed, then “about 10” is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

As used herein, the terms “optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where said event or circumstance occurs and instances where it does not. For example, the phrase “optional additional additives” means that the additive can or cannot be included and that the description includes foamed compositions that both include and that do not include one or more additional additives.

As used herein, the terms “number average molecular weight” or “Mn” can be used interchangeably, and refer to the statistical average molecular weight of all the polymer chains in the sample and is defined by the formula:

where Miis the molecular weight of a chain and Niis the number of chains of that molecular weight. Mncan be determined for polymers, e.g., polycarbonate polymers, by methods well known to a person having ordinary skill in the art using molecular weight standards, e.g. polycarbonate standards or polystyrene standards, preferably certified or traceable molecular weight standards.

As used herein, the terms “weight average molecular weight” or “Mw” can be used interchangeably, and are defined by the formula:

where Miis the molecular weight of a chain and Niis the number of chains of that molecular weight. Compared to Mn, Mwtakes into account the molecular weight of a given chain in determining contributions to the molecular weight average. Thus, the greater the molecular weight of a given chain, the more the chain contributes to the Mw. Mwcan be determined for polymers, e.g., polycarbonate polymers, by methods well known to a person having ordinary skill in the art using molecular weight standards, e.g., polycarbonate standards or polystyrene standards, preferably certified or traceable molecular weight standards.

The terms “BisA,” “BPA,” or “bisphenol A,” which can be used interchangeably, as used herein refers to a compound having a structure represented by the formula:

BisA can also be referred to by the name 4,4′-(propane-2,2-diyl)diphenol; p,p′-isopropylidenebisphenol; or 2,2-bis(4-hydroxyphenyl)propane. BisA has the CAS #80-05-7.

As used herein, “polycarbonate” refers to an oligomer or polymer including residues of one or more dihydroxy compounds, e.g., dihydroxy aromatic compounds, joined by carbonate linkages; it also encompasses homopolycarbonates, copolycarbonates, and (co)polyester carbonates.

The terms “residues” and “structural units”, used in reference to the constituents of the polymers, are synonymous throughout the specification.

As used herein the terms “weight percent,” “wt %,” and “wt. %,” which can be used interchangeably, indicate the percent by weight of a given component based on the total weight of the composition, unless otherwise specified. That is, unless otherwise specified, all wt % values are based on the total weight of the composition. It should be understood that the sum of wt % values for all components in a disclosed composition or formulation are equal to 100.

Unless otherwise stated to the contrary herein, all test standards are the most recent standard in effect at the time of filing this application.

Each of the materials disclosed herein are either commercially available and/or the methods for the production thereof are known to those of skill in the art.

Foamed Polymer Compositions

The present disclosure builds further on the use of a specially designed die for improving the nanostructuring of the fluoropolymer (e.g., PTFE) in a polymeric resin. This allows the preparation of masterbatches with high loadings of nanostructured fluoropolymer which can be diluted by the same base resin or with other resins.

The approach is to blend in an extruder the nanostructured fluoropolymer masterbatch with a non-fluoropolymer containing polymer which can be the same base resin as used in the masterbatch with the same melt flow index (MFI) or a different MFI, or a miscible polymer (at least thermodynamically miscible with the matrix resin) to, e.g., lower or increase the glass transition temperature, or an immiscible resin.

By varying the extrusion conditions and the choice of the feeding section of the extruder (feeding at the beginning together with the other components or with a side-feeder) the extent of dispersion of the nanostructured fluoropolymer over the complete matrix can be modified, and the compositions including the fluoropolymer can be foamed.

At least the following situations can occur:1. The nanostructured fluoropolymer is perfectly distributed in the matrix;2. The nanostructured fluoropolymer-rich regions form the continuous phase and the nanostructured fluoropolymer-poor regions form the dispersed phase;3. The nanostructured fluoropolymer-poor regions form the continuous phase and the nanostructured fluoropolymer-rich regions form the dispersed phase;4. A co-continuous morphology of the nanostructured fluoropolymer-poor and the nanostructured fluoropolymer-rich regions is formed.

The nanostructured fluoropolymer-containing regions will have a different nucleation behavior to initiate the foam depending on the interaction of the nanostructured fluoropolymer with the chemical or physical blowing agent. It is known, e.g., from literature that PTFE can absorb high amounts of supercritical CO2. Furthermore, the different melt strength can be controlled with the fluoropolymer concentration and the aspect ratio of the nanostructured fluoropolymer. As described, this is relevant for the control of the expansion of the foam.

Use of a non-random distribution of the nanostructured fluoropolymer regions with a different melt strength may lead to a multimodal (e.g., bimodal) cell size distribution irrespective of the resin composition for a wide range of foaming processes. Various possible cell size distributions could be generated using this blending approach.

One aspect that is different in comparison to studies using conventional fillers such as multiwalled carbon nanotubes (MWCNT) is the much higher aspect ratio of the nanostructured fluoropolymer filler. For the MWCNT filler the choice of the pristine CNT and the surface modification to get a reasonable dispersion within a polymer matrix are the primary parameters for the aspect ratio in the foam end product, mainly to limit the break-down process of the CNTs. For the nanostructured fluoropolymer/PTFE different processing parameters affect the aspect ratio.

The nanostructured PTFE can also act as a nucleating agent for the foaming process of the polymer matrix. The effectiveness of PTFE has already been demonstrated in polycarbonate matrix materials in U.S. Pat. No. 5,314,925, the disclosure of which is incorporated herein by this reference in its entirety. The PTFE is an efficient nucleating agent in terms of surface area per volume added and how much the crystallization temperature is raised compared to other nucleating agents. In addition, the epitaxial growth controls the orientation of the crystals that grow from the PTFE surface and they help to improve the mechanical properties. Epitaxial growth may be particularly desirable for foam injection molding.

For foam injection molding applications, this may lead to desirable anisotropic foam properties of the final product. In the first step of the overall injection molding cycle, i.e., the melt injection stage, the nanostructured fluoropolymer orients in the flow direction, contributing to improved melt strength. Expansion of the foam is affected by the local melt strength leading to anisotropic structures and the structure is solidified when the material is cooled in the mold. This effect will be more prominent when using resins that can crystallize upon cooling and form so-called shish-kebab structures (long central fiber cores (shish) surrounded by lamellar crystalline structures (kebab) periodically attached along the shish) with a much higher elastic modulus. An exemplary injection molding apparatus showing an included supercritical fluid supply system for forming the foamed composition is illustrated inFIG.1A.

In the foam injection molding process the mold can be also be opened just after injecting the hot melt and after partial foaming has already occurred. This is known as a core-back molding process.FIG.1Billustrates a conventional core-back process for forming a foamed polymer composition according to aspects of the disclosure. Diagrams of an exemplary core-back mold are shown inFIG.1C. The initial figure illustrates the filled cavity; the subsequent figure illustrates the mold after it is opened in one direction to allow the mold to breathe. The breathing results in a pressure drop, causing the melt to foam.FIG.1Dis a diagram showing an exemplary mold cavity for use in the core-back mold ofFIG.1C. In some aspects the temperature of the hot melt is reduced after it is introduced into the mold, which increases the gas solubility of the holt melt.

In a core-back molding process, the overall density of the foam can be reduced and further anisotropic structures can be obtained. This process can be controlled with the concentration of the nanostructured fluoropolymer/PTFE as well as the overall distribution of the nanostructured fluoropolymer using a completely homogeneous distribution or a heterogeneous distribution. This also affects the final properties of the foamed product in terms of local stiffness, compressive strength and impact properties.

Foaming injection molding including core-back molding processes are further described in EP application no. 19203067.4, filed Oct. 14, 2019 and entitled “Compositions of improved through-plane thermal conductivity using foam injection molding with core-back technology,” the disclosure of which is incorporated herein by this reference in its entirety.

Aspects of the disclosure thus relate to foamed polymer compositions including:

from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof.

In particular aspects the foamed polymer composition includes:

from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof.

The matrix polymer component may be modified or unmodified. For example, the matrix polymer component (e.g., PET) may include chain extenders or branching agents.

In some aspects the matrix polymer component includes PET, PEI, PPO, PS, PPS, PC, PP, PA, copolymers thereof, or a combination thereof. In specific aspects the matrix polymer component includes PET and PEI, including copolymers thereof. In further aspects the matrix polymer component includes PPO and PP, including copolymers thereof. In yet further aspects the matrix polymer component includes PPO and PA, including copolymers thereof. In even further aspects the matrix polymer component includes PPO and PS, including copolymers thereof. Exemplary polyamides include but are not limited to nylon, including any nylon blend (such as but not limited to nylon 6, nylon 6,6, nylon 6,12, nylon 11 and nylon 12).

In a specific aspect the composition includes from 1 wt % to 99 wt % PEI and from 1 wt % to 99 wt % PET. In further aspects the composition includes from 1 wt % to 20 wt % PEI and from 80 wt % to 99 wt % PET, or from 20 wt % to 80 wt % PEI and from 20 wt % to 80 wt % PET, or from 80 wt % to 99 wt % PEI and from 1 wt % to 20 wt % PET.

The foamed polymer composition has in some aspects an average cell size of from 1 micron (μm) to 1000 μm. In particular aspects the foamed polymer composition has an average cell size of from 5 to 800 μm, from 5 to 600 μm, from 5 to 400 μm, from 5 to 200 μm, or from 5 to 100 μm.

The encapsulating polymer includes in some aspects a styrene-acrylonitrile copolymer, an acrylonitrile-butadiene-styrene copolymer, alpha-alkyl-styrene-acrylonitrile copolymer, an alpha-methylstyrene-acrylonitrile copolymer, a styrene-butadiene rubber, or a combination thereof.

In a particular aspect the fluoropolymer includes polytetrafluoroethylene (PTFE). In further aspects the fluoropolymer encapsulated by an encapsulating polymer is styrene-acrylonitrile copolymer (SAN)-encapsulated PTFE, also known as TSAN.

As is known, fluoropolymers are available in a variety of forms, including powders, emulsions, dispersions, agglomerations, and the like. “Dispersion” (also called “emulsion”) fluoropolymers are generally manufactured by dispersion or emulsion, and generally include about 25 to 60 weight % fluoropolymer in water, stabilized with a surfactant, wherein the fluoropolymer particles are approximately 0.1 to 0.3 micrometers in diameter. “Fine powder” (or “coagulated dispersion”) fluoropolymers may be made by coagulation and drying of dispersion-manufactured fluoropolymers. Fine powder fluoropolymers are generally manufactured to have a particle size of approximately 400 to 500 microns. “Granular” fluoropolymers may be made by a suspension method, and are generally manufactured in two different particle size ranges, including a median particle size of approximately 30 to 40 micrometers, and a high bulk density product exhibiting a median particle size of about 400 to 500 micrometers. Pellets of fluoropolymer may also be obtained and cryogenically ground to exhibit the desired particle size.

In one aspect the fluoropolymer is at least partially encapsulated by an encapsulating polymer that may be the same or different as the matrix polymer (hereinafter referred to as an “encapsulated polymer”). Without being bound by theory, it is believed that encapsulation may aid in the distribution of the fluoropolymer within the matrix, and/or compatibilize the fluoropolymer with the matrix.

Particularly preferred encapsulating polymers include a styrene-acrylonitrile copolymer, an acrylonitrile-butadiene-styrene copolymer, alpha-alkyl-styrene-acrylonitrile copolymer, an alpha-methylstyrene-acrylonitrile copolymer, a styrene-butadiene rubber, or a combination thereof. Styrene-acrylonitrile copolymer encapsulated polytetrafluoroethylene is one preferred aspect.

The encapsulating polymers may be obtained by polymerization of monomers or mixtures of monomers by methods known in the art, for example, condensation, addition polymerization, and the like. Emulsion polymerization, particularly radical polymerization may be used effectively. In one aspect, the encapsulating polymer is formed from monovinylaromatic monomers containing condensed aromatic ring structures, such as vinyl naphthalene, vinyl anthracene and the like. Examples of suitable monovinylaromatic monomers include styrene, 3-methylstyrene, 3,5-diethylstyrene, 4-n-propylstyrene, alpha-methylstyrene, alpha-methyl vinyltoluene, alpha-chlorostyrene, alpha-bromostyrene, dichlorostyrene, dibromostyrene, tetra-chlorostyrene, and the like, and combinations including at least one of the foregoing compounds. Styrene and/or alpha-methylstyrene may be specifically mentioned.

Mixtures of the foregoing monovinylaromatic monomers and monovinylic monomers may also be used, for example mixtures of styrene and acrylonitrile (SAN). The relative ratio of monovinylaromatic and monovinylic monomers in the rigid graft phase may vary widely depending on the type of fluoropolymer, type of monovinylaromatic and monovinylic monomer(s), and the desired properties of the encapsulant. The encapsulant may generally be formed from up to 100 wt %, or up to about 100 wt %, of monovinyl aromatic monomer, specifically 30 to 100 wt %, or about 30 to about 100 wt %, more specifically, 50 to 90 wt %, or about 50 to about 90 wt % monovinylaromatic monomer, with the balance being comonomer(s). A preferred fluoropolymer is TSAN, which includes SAN and PTFE. See, U.S. Pat. Nos. 5,804,654 and 6,040,370, the disclosures of which are incorporated herein by this reference in their entireties.

Elastomers may also be used as the encapsulating polymer, as well as elastomer-modified graft copolymers. Suitable elastomers include, for example, conjugated diene rubbers; copolymers of a conjugated diene with less than about 50 wt % of a copolymerizable monomer; olefin rubbers such as ethylene propylene copolymers (EPR) or ethylene-propylene-diene monomer rubbers (EPDM); ethylene-vinyl acetate rubbers; silicone rubbers; elastomeric C1-8 alkyl (meth)acrylates; elastomeric copolymers of C1-8 alkyl (meth)acrylates with butadiene and/or styrene; or combinations including at least one of the foregoing elastomers.

Examples of conjugated diene monomers that may be used are butadiene, isoprene, 1,3-heptadiene, methyl-1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-pentadiene; 1,3- and 2,4-hexadienes, and the like, as well as mixtures including at least one of the foregoing conjugated diene monomers. Specific conjugated diene homopolymers include polybutadiene and polyisoprene.

Copolymers of a conjugated diene rubbers may also be used, for example those produced by aqueous radical emulsion polymerization of a conjugated diene and up to 10 wt %, or up to about 10 wt %, of one or more monomers copolymerizable therewith. Specific copolymers include styrene and acrylonitrile.

(Meth)acrylate monomers suitable for use as an elastomeric encapsulating monomer include the cross-linked, particulate emulsion homopolymers or copolymers of C4-8 alkyl (meth)acrylates, in particular C4-6 alkyl acrylates, for example n-butyl acrylate, t-butyl acrylate, n-propyl acrylate, isopropyl acrylate, 2-ethylhexyl acrylate, and the like, and combinations including at least one of the foregoing monomers. Exemplary comonomers include but are not limited to butadiene, isoprene, styrene, methyl methacrylate, phenyl methacrylate, phenethylmethacrylate, N-cyclohexylacrylamide, vinyl methyl ether or acrylonitrile, and mixtures including at least one of the foregoing comonomomers. Optionally, up to 5 wt % a polyfunctional crosslinking comonomer may be present, for example divinylbenzene, alkylenediol di(meth)acrylates such as glycol bisacrylate, alkylenetriol tri(meth)acrylates, polyester di(meth)acrylates, bisacrylamides, triallyl cyanurate, triallyl isocyanurate, allyl (meth)acrylate, diallyl maleate, diallyl fumarate, diallyl adipate, triallyl esters of citric acid, triallyl esters of phosphoric acid, and the like, as well as combinations including at least one of the foregoing crosslinking agents.

Suitable elastomer-modified graft copolymers may be prepared by first providing an elastomeric polymer (for example, as described above), then polymerizing the constituent monomer(s) of the rigid phase in the presence of the fluoropolymer and the elastomer to obtain the graft copolymer. The elastomeric phase may provide 5 to 95 wt %, or about 5 to about 95 wt %, of the total graft copolymer, more specifically, 20 to 90 wt %, about 20 to about 90 wt %, and even more specifically, 40 to 85 wt %, or about 40 to about 85 wt % of the elastomer-modified graft copolymer, the remainder being the rigid graft phase. Depending on the amount of elastomer-modified polymer present, a separate matrix or continuous phase of ungrafted rigid polymer or copolymer may be simultaneously obtained along with the elastomer-modified graft copolymer.

In another aspect, the encapsulating polymer includes SAN, ABS copolymers, alpha-(C1-3)alkyl-styrene-acrylonitrile copolymers, alpha-methylstyrene-acrylonitrile (AMSAN) copolymers, SBR, and combinations including at least one of the foregoing. In yet another aspect the encapsulating polymer is SAN or AMSAN.

Suitable amounts amount of encapsulating polymer may be determined by one of ordinary skill in the art without undue experimentation, using the guidance provided below. In one aspect, the encapsulated fluoropolymer includes 10 to 90 weight percent (wt %), or about 10 to about 90 wt % fluoropolymer and 90 to 10 wt %, or about 90 to about 10 wt %, of the encapsulating polymer, based on the total weight of the encapsulated fluoropolymer. Alternatively, the encapsulated fluoropolymer includes 20 to 80 wt %, or about 20 to about 80 wt %, more specifically, 40 to 60 wt %, or about 40 to about 60 wt % fluoropolymer, and 80 to 20 wt %, or about 80 to about 20 wt %, specifically, 60 to 40 wt %, or about 60 to about 40 wt % encapsulating polymer, based on the total weight of the encapsulated polymer.

As described herein, the fluoropolymer is nanostructured. As used herein, the term “nanostructure” refers to a material in which one dimension of the material is equal to or less than 1000 nm (e.g., one dimension is 1 to 1000 nm in size). In a particular aspect, the nanostructure includes at least two dimensions that are equal to or less than 1000 nm (e.g., a first dimension is 1 to 1000 nm in size and a second dimension is 1 to 1000 nm in size). In another aspect, the nanostructure includes three dimensions that are equal to or less than 1000 nm (e.g., a first dimension is 1 to 1000 nm in size, a second dimension is 1 to 1000 nm in size, and a third dimension is 1 to 1000 nm in size). The shape of the nanostructure can be of a wire, a particle (e.g., having a substantially spherical shape), a rod, a tetrapod, a hyper-branched structure, a tube, a cube, or mixtures thereof. The nanostructures can be monodisperse, where all particles are of the same size with little variation, or polydisperse, where the particles have a range of sizes and are averaged.

The nanostructured fluoropolymer can be prepared in a masterbatch, for example, during extrusion of a polymer, a filler, or both simultaneously. Methods for the preparation of the nanostructured fluoropolymer are described on WO 2018/122747, the disclosure of which is incorporated herein by this reference in its entirety. Thus in some aspects the fluoropolymer is fibrillated. “Fibrillation” is a term of art that refers to the treatment of fluoropolymers so as to produce, for example, a “node and fibril,” network, or cage-like structure. In one aspect, the fluoropolymer includes fibrils having an average diameter of 5 nanometers (nm) to 2 micrometers (pun), or from about 5 nm to about 2 pun. The fluoropolymer may also have an average fibril diameter of 30 nanometers to 750 nanometers, more specifically 5 nanometers to 500 nanometers. In a further example, the fluoropolymer may also have an average fibril diameter of about 30 nanometers to about 750 nanometers, more specifically about 5 nanometers to about 500 nanometers. Field Emission Scanning Electron Microscopy can be employed to observe the extent of fibrillation of the fluoropolymer throughout the matrix polymer in the fibrillated compositions.

In some aspects the foamed polymer composition includes from 0.01 wt % to less than 0.1 wt %, based on the weight of the polymer composition, of the nanostructured fluoropolymer, the nanostructured fluoropolymer encapsulated by an encapsulating polymer, or the combination thereof. In further aspects the nanostructured fluoropolymer, the nanostructured fluoropolymer encapsulated by an encapsulating polymer, or the combination thereof are present in the foamed polymer composition in an amount of from 0.01 wt % to 0.5 wt %, or from 0.01 wt % to 0.09 wt %, or from 0.03 wt % to 0.10 wt %, or from 0.03 wt % to 0.09 wt %, or from 0.05 wt % to 0.10 wt %, or from 0.05 wt % to 0.09 wt %.

The foamed polymer composition may further include in some aspects at least one additional additive including a reinforcing filler, acid scavenger, anti-drip agent, antioxidant, antistatic agent, chain extender, colorant, de-molding agent, flow promoter, lubricant, mold release agent, plasticizer, quenching agent, flame retardant, UV reflecting additive, and combinations thereof. The at least one additional additive may be included in the foamed polymer composition in any amount that will not significantly adversely affect the desired properties of the thermoplastic composition.

In a particular aspect the at least one additional additive is a flame retardant. Suitable flame retardant that may be added may be organic compounds that include phosphorus, bromine, and/or chlorine. Non-brominated and non-chlorinated phosphorus-containing flame retardants may be preferred in certain applications for regulatory reasons, for example organic phosphates and organic compounds containing phosphorus-nitrogen bonds.

One type of exemplary organic phosphate is an aromatic phosphate of the formula (GO)3P═O, wherein each G is independently an alkyl, cycloalkyl, aryl, alkaryl, or aralkyl group, provided that at least one G is an aromatic group. Two of the G groups may be joined together to provide a cyclic group, for example, diphenyl pentaerythritol diphosphate, which is described by Axelrod in U.S. Pat. No. 4,154,775. Other suitable aromatic phosphates may be, for example, phenyl bis(dodecyl) phosphate, phenyl bis(neopentyl) phosphate, phenyl bis(3,5,5′-trimethylhexyl) phosphate, ethyl diphenyl phosphate, 2-ethylhexyl di(p-tolyl) phosphate, bis(2-ethylhexyl) p-tolyl phosphate, tritolyl phosphate, bis(2-ethylhexyl) phenyl phosphate, tri(nonylphenyl) phosphate, bis(dodecyl) p-tolyl phosphate, dibutyl phenyl phosphate, 2-chloroethyl diphenyl phosphate, p-tolyl bis(2,5,5′-trimethylhexyl) phosphate, 2-ethylhexyl diphenyl phosphate, or the like. A specific aromatic phosphate is one in which each G is aromatic, for example, triphenyl phosphate, tricresyl phosphate, isopropylated triphenyl phosphate, and the like. Thus, in particular aspects the retardant is a phosphorous-based flame retardant.

Suitable blowing agents include, but are not limited to, low boiling halohydrocarbons and those that generate carbon dioxide; blowing agents that are solid at room temperature and when heated to temperatures higher than their decomposition temperature, generate gases such as nitrogen, carbon dioxide ammonia gas, such as azodicarbonamide, metal salts of azodicarbonamide, 4,4′ oxybis(benzenesulfonylhydrazide), sodium bicarbonate, ammonium carbonate, or the like, or combinations including at least one of the foregoing blowing agents. Blowing agents are generally used in amounts of 0.01 to 15 parts by weight, or about 0.01 to about 15 parts by weight, based on 100 parts by weight of the polymer portion of the composition.

The foamed polymer compositions formed according to the methods describe herein may include any of the components described herein. For example, in some aspects the matrix polymer component includes polybutylene terephthalate (PBT), polyetherimide (PEI), polyethylene terephthalate (PET), polycarbonate (PC), poly(p-phenylene oxide) (PPO), polystyrene (PS), polyphenylene sulfide (PPS), polypropylene (PP), polyamide (PA), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high density polyethylene (HDPE), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), copolymers thereof, or a combination thereof.

The foamed polymer compositions formed according to the methods describe herein may include the components in any amount described herein, and may have any of the properties or characteristics (e.g., average cell size) described herein.

In some aspects the foamed polymer compositions are formed by passing the melted/molten polymer mixture through a die incorporated into the extruder or injection molding machine. Some non-limiting examples of suitable dies include an annular die, coat hanger die, spiral mandrel die, crosshead die, T-die, fishtail die, spider die, single, or double roller die, or profile extrusion die. Particularly suitable dies may include, but are not limited to, those described in WO 2018/122747, the disclosure of which is incorporated herein by this reference in its entirety.

Articles Including the Foamed Polymer Composition

Aspects of the disclosure further relate to articles including the foamed polymer composition described herein. Exemplary articles include, but are not limited to, film, tape, breads, strands, sheets, tubes and rods. The article may have any cross section, including but not limited to circular, square, polygonal and annular.

In particular aspects the article is a component of an aircraft, including but not limited to an interior or an exterior component of an aircraft. Examples of aircraft include, but are not limited to, jets, small aircraft, helicopters and spacecraft. Example interior components include, but are not limited to, foldout trays on the rear of a passenger aircraft seat, seat filling, intermediate wall filling, and interior doors. Example exterior components include, but are not limited to, filling for the outer skin of the aircraft, the aircraft nose, the wings, the outer doors, rudders and rotor blades.

Various combinations of elements of this disclosure are encompassed by this disclosure, e.g., combinations of elements from dependent claims that depend upon the same independent claim.

Aspects of the Disclosure

In various aspects, the present disclosure pertains to and includes at least the following aspects.

Aspect 1. A foamed polymer composition comprising, consisting of, or consisting essentially of:

from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof.

Aspect 2. The foamed polymer composition according to Aspect 1, wherein the matrix polymer component comprises PET, PEI, PPO, PS, PPS, PC, PP, PA, copolymers thereof, or a combination thereof.

Aspect 3. The foamed polymer composition according to Aspect 1 or 2, wherein the foamed composition has an average cell size of from 1 micron (μm) to 1000 μm.

Aspect 4. The foamed polymer composition according to any of Aspects 1 to 3, wherein the matrix polymer component comprises from 1 wt % to 99 wt % PEI and from 1 wt % to 99 wt % PET, or from 1 wt % to 20 wt % PEI and from 80 wt % to 99 wt % PET, or from 20 wt % to 80 wt % PEI and from 20 wt % to 80 wt % PET, or from 80 wt % to 99 wt % PEI and from 1 wt % to 20 wt % PET.

Aspect 5. The foamed polymer composition according to any of Aspects 1 to 4, wherein the fluoropolymer comprises polytetrafluoroethylene, polyhexafluoropropylene, polyvinylidene fluoride, polychlorotrifluoroethylene, ethylene tetrafluoroethylene, fluorinated ethylene-propylene, polyvinyl fluoride, ethylene chlorotrifluoroethylene, or a combination thereof.

Aspect 6. The foamed polymer composition according to any of Aspects 1 to 5, wherein the encapsulating polymer comprises a styrene-acrylonitrile copolymer, an acrylonitrile-butadiene-styrene copolymer, alpha-alkyl-styrene-acrylonitrile copolymer, an alpha-methylstyrene-acrylonitrile copolymer, a styrene-butadiene rubber, or a combination thereof.

Aspect 7. The foamed polymer composition according to any of Aspects 1 to 6, wherein the fluoropolymer comprises polytetrafluoroethylene.

Aspect 8. The foamed polymer composition according to any of Aspects 1 to 7, wherein the fluoropolymer encapsulated by an encapsulating polymer is styrene-acrylonitrile copolymer encapsulated polytetrafluoroethylene.

Aspect 9. The foamed polymer composition according to any of Aspects 1 to 8, comprising from 0.01 wt % to less than 0.1 wt %, based on the weight of the polymer composition, of the nanostructured fluoropolymer, the nanostructured fluoropolymer encapsulated by an encapsulating polymer, or the combination thereof.

Aspect 10. The foamed polymer composition according to any of Aspects 1 to 9, wherein the composition further comprises at least one additional additive comprising a reinforcing filler, acid scavenger, anti-drip agent, antioxidant, antistatic agent, chain extender, colorant, de-molding agent, flow promoter, lubricant, mold release agent, plasticizer, quenching agent, flame retardant, UV reflecting additive, and combinations thereof.

Aspect 11. The foamed polymer composition according to Aspect 10, wherein the at least one additional additive comprises a flame retardant, and the flame retardant is a phosphorous-based flame retardant.

Aspect 12. An article comprising the foamed polymer composition according to any of Aspects 1 to 11.

Aspect 13. The article according to Aspect 12, wherein the article is a film or a tape.

Aspect 13A. The article according to Aspect 12 or 13, wherein the article is a component of an aircraft, including but not limited to an interior component or an exterior component of an aircraft.

Aspect 14. A method for making a foamed polymer composition, comprising, consisting of, or consisting essentially of:

forming a mixture comprisinga matrix polymer component, andfrom 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof;

melting the mixture;

injecting the melted mixture into a mold; and

reducing pressure and/or temperature on the mixture to form the foamed polymer composition.

Aspect 15. The method according to Aspect 14, wherein the mold is a core-back mold.

Aspect 16. A method for making a foamed polymer composition, comprising, consisting of, or consisting essentially of:

forming a mixture comprisinga matrix polymer component, andfrom 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof;

melting the mixture; and

extruding the mixture in the presence of a blowing agent to introduce the blowing agent into the mixture and form the foamed polymer composition.

Aspect 18. The method according to any of Aspects 14 to 17, wherein the matrix polymer component comprises PET, PEI, PPO, PS, PPS, PC, PP, PA, copolymers thereof, or a combination thereof.

Aspect 19. The method according to any of Aspects 14 to 18, wherein the foamed composition has an average cell size of from 1 micron (μm) to 1000 μm.

Aspect 20. The method according to any of Aspects 14 to 19, wherein the matrix polymer component comprises from 1 wt % to 99 wt % PEI and from 1 wt % to 99 wt % PET, or from 1 wt % to 20 wt % PEI and from 80 wt % to 99 wt % PET, or from 20 wt % to 80 wt % PEI and from 20 wt % to 80 wt % PET, or from 80 wt % to 99 wt % PEI and from 1 wt % to 20 wt % PET.

Aspect 21. The method according to any of Aspects 14 to 20, wherein the fluoropolymer comprises polytetrafluoroethylene, polyhexafluoropropylene, polyvinylidene fluoride, polychlorotrifluoroethylene, ethylene tetrafluoroethylene, fluorinated ethylene-propylene, polyvinyl fluoride, ethylene chlorotrifluoroethylene, or a combination thereof.

Aspect 22. The method according to any of Aspects 14 to 21, wherein the encapsulating polymer comprises a styrene-acrylonitrile copolymer, an acrylonitrile-butadiene-styrene copolymer, alpha-alkyl-styrene-acrylonitrile copolymer, an alpha-methylstyrene-acrylonitrile copolymer, a styrene-butadiene rubber, or a combination thereof.

Aspect 23. The method according to any of Aspects 14 to 22, wherein the fluoropolymer comprises polytetrafluoroethylene.

Aspect 24. The method according to any of Aspects 14 to 23, wherein the fluoropolymer encapsulated by an encapsulating polymer is styrene-acrylonitrile copolymer encapsulated polytetrafluoroethylene.

Aspect 25. The method according to any of Aspects 14 to 24, comprising from 0.01 wt % to less than 0.1 wt %, based on the weight of the polymer composition, of the nanostructured fluoropolymer, the nanostructured fluoropolymer encapsulated by an encapsulating polymer, or the combination thereof.

Aspect 26. The method according to any of Aspects 14 to 25, wherein the composition further comprises at least one additional additive comprising a reinforcing filler, acid scavenger, anti-drip agent, antioxidant, antistatic agent, chain extender, colorant, de-molding agent, flow promoter, lubricant, mold release agent, plasticizer, quenching agent, flame retardant, UV reflecting additive, and combinations thereof.

Aspect 27. The method according to Aspect 26, wherein the at least one additional additive comprises a flame retardant, and the flame retardant is a phosphorous-based flame retardant.

Aspect 28. An article comprising the foamed polymer composition formed according to the method of any of Aspects 14 to 27.

Aspect 29. The article according to Aspect 28, wherein the article is a film or a tape.

Aspect 30. The article according to Aspect 28 or 29, wherein the article is a component of an aircraft, including but not limited to an interior component or an exterior component of an aircraft.

Aspect 31. A foamed polymer composition comprising, consisting of, or consisting essentially of:

from 0.01 wt % to 2 wt %, based on the weight of the polymer composition, of a nanostructured fluoropolymer, a nanostructured fluoropolymer encapsulated by an encapsulating polymer, or a combination thereof.

Aspect 33. The foamed polymer composition according to Aspect 31, wherein the matrix polymer component comprises PET, PEI, PPO, PS, PPS, PC, PA, copolymers thereof, or a combination thereof.

Aspect 34. The foamed polymer composition according to Aspect 31 or 32, wherein the foamed composition has an average cell size of from 1 micron (μm) to 1000 μm.

Aspect 35. The foamed polymer composition according to any of Aspects 31 to 34, wherein the matrix polymer component comprises from 1 wt % to 99 wt % PEI and from 1 wt % to 99 wt % PET.

Aspect 36. The foamed polymer composition according to any of Aspects 31 to 35, comprising from 0.01 wt % to less than 0.1 wt %, based on the weight of the polymer composition, of the nanostructured fluoropolymer, the nanostructured fluoropolymer encapsulated by an encapsulating polymer, or the combination thereof.

Aspect 37. The foamed polymer composition according to any of Aspects 31 to 36, wherein the composition comprises a nanostructured fluoropolymer encapsulated by an encapsulating polymer.

Aspect 38. The foamed polymer composition according to Aspect 37, wherein the encapsulating polymer comprises a styrene-acrylonitrile copolymer, an acrylonitrile-butadiene-styrene copolymer, alpha-alkyl-styrene-acrylonitrile copolymer, an alpha-methylstyrene-acrylonitrile copolymer, a styrene-butadiene rubber, or a combination thereof.

Aspect 39. The foamed polymer composition according to any of Aspects 31 to 38, wherein the fluoropolymer encapsulated by an encapsulating polymer is styrene-acrylonitrile copolymer encapsulated polytetrafluoroethylene.

Aspect 40. The foamed polymer composition according to any of Aspects 31 to 39, wherein the composition further comprises at least one additional additive comprising a reinforcing filler, acid scavenger, anti-drip agent, antioxidant, antistatic agent, chain extender, colorant, de-molding agent, flow promoter, lubricant, mold release agent, plasticizer, quenching agent, flame retardant, UV reflecting additive, and combinations thereof.

Aspect 41. The foamed polymer composition according to any of Aspects 31 to 40, wherein the nanostructured fluoropolymer is fibrillated.

EXAMPLES

There are numerous variations and combinations of reaction conditions, e.g., component concentrations, desired solvents, solvent mixtures, temperatures, pressures and other reaction ranges and conditions that can be used to optimize the product purity and yield obtained from the described process. Only reasonable and routine experimentation will be required to optimize such process conditions.

Several polymer base compositions including various matrix polymer components and SAN/PTFE were injection molded. The base compositions are set forth in Table 1:

Compositions 1 and 6 did not include SAN/PTFE and are considered comparative compositions. The SAN/PTFE was an encapsulated nanostructured fluoropolymer (n-structured TSAN) masterbatch in either PBT or PP (depending on the respective base composition), manufactured as described in WO2018122747, the disclosure of which is incorporated by this reference in its entirety.

The base compositions were extruded using the barrel temperatures set forth in Table 2:

TABLE 2Barrel Temperatures for Extruding the Base CompositionsPP70/100/150/200/240/240/240/240/240/240/240/240° C.PBT70/150/200/250/280/280/280/280/280/280/280/280° C.

The base compositions were foamed with nitrogen gas using an injection molding core-back process according to aspects described herein.

Various PP foamed samples were formed from pellets of base composition 4 according to specifications set forth in Table 3:

Photographs of several of the samples are shown inFIGS.2A-2D. From the samples the following observations were made:The neat PP foamed samples (C3.2 and C3.3) exhibited an inhomogeneous foam structure in both the thickness direction and in the foam direction.PP can be foamed to a core back expansion ratio of at least 130% by including up to 2 wt % TSAN.Addition of TSAN results in a much more homogeneous cell size distribution in the foamed core.The expansion ratio in the hot runner sections shows that the maximum achievable expansion ratio is much larger than 130%The amount of TSAN in the samples can be substantially reduced as compared to previously known compositions.

The tensile modulus and strength of the samples were determined according to ISO 527. Results are illustrated inFIGS.3and4. From the graphs it is observed that the foamed samples including TSAN do not suffer from a significant loss in modulus and strength as compared to the solid samples.

Various PBT foamed samples were formed from pellets of base compositions 2 and 3 according to specifications set forth in Table 3:

Photographs of several of the samples are shown inFIGS.5A-5D.FIG.5Cshowing sample C4.3 (no TSAN, foamed with 50% core-back expansion ratio) demonstrates a large gradient in cell sizes. From the samples the following observations were made:PBT can be foamed to a core back expansion ratio of at least 130% by including up to 1 wt % TSAN.The stiffness of the foamed materials tended to increase with increasing core back expansion.The melt temperature profile was more sensitive for PBT than for PP and the processing window was smaller.A strong flow-induced crystallization effect was observed for thin parts or thin runner sections.

Cross-sectional scanning electron microscopy (SEM) images of PP foamed samples are shown inFIGS.6A(Sample C3.3) and6B (Sample Ex3.2). The images show that the foamed sample that does not include nanostructured TSAN (FIG.6A) includes an inhomogeneous foam structure in both the thickness direction and in the flow direction, while the sample including TSAN (FIG.6B) had a homogeneous cell size distribution throughout the foamed core.

Additional foamed PP samples were formed from a 3 wt % nanostructured TSAN masterbatch composition. The PP was PP 525P from SABIC, which has a MFI of 3. The samples were foamed using isobutane with an annular die. 2, 4, 8 and 16 wt % of the masterbatch composition was combined with neat PP to form the foamed samples (i.e., the final TSAN content of the foamed samples was 0.06 wt %, 0.12 wt %, 0.24 wt % and 0.48 wt %, respectively), and the density of the foamed samples was determined. The final PTFE content of the foamed samples was 0.03 wt %, 0.06 wt %, 0.12 wt % and 0.24 wt %, respectively. In addition, comparative foam samples including neat PP foam (100% 525P) and blends of PP with a high melt strength PP (Daploy™ WB140HMS) were formed. The density of all samples as a function of temperature is shown inFIG.7. From the graph it is observed that by adding nanostructured TSAN to the PP density is minimized and the processing window increases.

Open cell content of the samples as a function of temperature is shown inFIG.8. As observed, the PP/nanostructured TSAN foamed samples had substantially no open cell content over a wide temperature range.

Images of PET foams formed according to aspects of the disclosure are shown inFIGS.9A and9B. The images are cross sections of PET including 0.045 wt % nanostructured TSAN. The images illustrate the closed cell content of the samples.

Foam compositions including a blend of matrix polymer component were formed as shown in Table 5:

The PPC was a polyphthalatecarbonate (50:50 molar ratio of isophthalate ester to terephthalate ester), LEXAN™ 4501 with a MFR at 300° C./5 kg of 10 g/10 min (measured in accordance with ISO 1133).

Polyetherimide foam compositions were formed according to Table 6:

The compositions of Table 6 were formed according to the conditions of Table 7:

Additional blended compositions including PET (Ramapet® N180) and PEI (Ultem™) were formed and tested as set forth in Table 8 below:

The compositions in Table 8 were extruded with barrel settings (in ° C.) of 60-270-340-320-300-280-280-280-280-280 at an extrusion rate of 20 kg/hr. In the granulate appearance “chunks” refers to clusters or lumps of badly dispersed TSAN particles.

A graph of MVR vs. TSAN content (3% nanostructured TSAN in Ramapet® N180) is provided inFIG.10. As shown, increasing the amount of TSAN allows for very high flow (MVR); and from Table 8 it is observed that there is no a significant change in Tg. This demonstrates the efficiency of TSAN in its nanostructured form.

Further blended compositions including PET (Ramapet® N180) and PEI (Ultem™) were formed and tested as set forth in Table 9 below:

The compositions in Table 9 were extruded with barrel settings (in ° C.) of 60-270-340-320-300-280-280-280-280-280 at an extrusion rate of 20 kg/hr.

The compositions in Table 9 do not include PTFE, but from the evaluated Tg properties it is observed that Tg can be tuned by blending PEI and PET. Pure PEI (e.g., Ultem™) cannot be processed at temperatures below the melting point of PTFE (330° C.). Processing above the melting point of PTFE melts the fiber, eliminating the property advantages of using PTFE. In addition, processing above the Tm of PTFE can cause degradation of the PTFE, resulting in serious environmental, health, and safety (EHS) concerns. Addition of PET lowers the Tg significantly. Even at a 50/50 mix the Tg is reduced by about 90° C. Over the range the melting temperature (Tm) is fairly constant just below 250° C. This makes a processing temperature between 280 and 310° C. possible. In contrast, pure PEI begins to be processable at 360° C., with typical processing conditions between 360 and 400° C. In combination with the results from Table 8, it is observed that addition of PTFE does not strongly influence Tg.