Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
  • C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
  • C08J9/122—Hydrogen, oxygen, CO2, nitrogen or noble gases
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L33/04—Homopolymers or copolymers of esters
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2201/00—Foams characterised by the foaming process
  • C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
  • C08J2201/032—Impregnation of a formed object with a gas
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2203/00—Foams characterized by the expanding agent
  • C08J2203/06—CO2, N2 or noble gases
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2205/00—Foams characterised by their properties
  • C08J2205/04—Foams characterised by their properties characterised by the foam pores
  • C08J2205/044—Micropores, i.e. average diameter being between 0,1 micrometer and 0,1 millimeter
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2205/00—Foams characterised by their properties
  • C08J2205/04—Foams characterised by their properties characterised by the foam pores
  • C08J2205/052—Closed cells, i.e. more than 50% of the pores are closed
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2333/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers
  • C08J2333/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters
  • C08J2333/06—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Derivatives of such polymers esters of esters containing only carbon, hydrogen, and oxygen, the oxygen atom being present only as part of the carboxyl radical
  • C08J2333/10—Homopolymers or copolymers of methacrylic acid esters
  • C08J2333/12—Homopolymers or copolymers of methyl methacrylate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2423/04—Homopolymers or copolymers of ethene
  • C08J2423/06—Polyethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
  • C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
  • C08J2423/04—Homopolymers or copolymers of ethene
  • C08J2423/08—Copolymers of ethene

Definitions

• the present disclosure relates to polymeric foams, particularly to closed-cell polymeric foams, and processes for their preparation.
• microcellular foams are superior to those of conventional foams with higher cell sizes. Due to this reason in the last years the idea of reducing even more the cell size to create materials with improved properties has appeared and due to this sub- microcellular foams and nanocellular foams have been developed.
• thermoplastic polymers three main strategies can be distinguished.
• the first strategy is based on an homogeneous nucleation process in which a high gas uptake is needed and due to this, extreme processing conditions are used (very high pressures, very high pressure drop rates or even low saturation temperatures). In addition, polymers with high affinity to the gas phase are used.
• a second approach is the use of nanoparticles as nucleating agents for the cells. This strategy is based on an heterogeneous nucleation process.
• the third approach is the use of block copolymers creating a disperse phase (micelles) in which the cells are nucleated.
• This second phase has a high affinity for the gas phase and the number micelles should be high enough to produce submicrocellular and nanocellular foams.
• This strategy is also based on an heterogeneous nucleation process.
• the first one is to achieve the required degree of dispersion of the nanopartides in the polymer matrix, more than 10 11 particles/cm 3 .
• the second one is that in general it is also needed the use of high pressures and high pressure drop rates to obtain the number of cells required.
• the micelles should have a high affinity with the gas phase, in addition the micelles should have a lower glass transition temperature than the polymer matrix.
• thermoplastic particle foams obtained from two
• thermoplastic polymers are known in the art.
• thermoplastic particle foams wherein the cell membranes have a nanocellular or fibrous structure, and wherein the polymer matrix comprises a continuous phase which is rich in styrene polymer and a disperse polyolefin-rich phase.
• the polymer mixture can be produced by mixing the two incompatible thermoplastic polymers in an extruder.
• the present disclosure relates to closed-cell polymeric foams having a polymer matrix which comprises a continuous polymer phase and a disperse polymer phase.
• the continuous polymer phase comprises at least one acrylate polymer selected from a polyacrylate polymer, a polyalkylacrylate polymer and mixtures thereof in a concentration of at least 90 % w/w of the total continuous polymer phase weight; and the disperse polymer phase comprises at least a polyolefin polymer in a concentration of at least 90 % w/w of the total disperse polymer phase weight; the amount of continuous polymer phase is comprised of from 80 % w/w to 99.8 % w/w of the total polymer matrix.
• the closed-cell polymeric foams of the present disclosure show an improvement in the mechanical properties in comparison with other polymeric foams of the state of the art, particularly, the closed-cellpolymeric foams show impact resistance, glass transition temperature, and storage modulus properties within unexpected ranges which simultaneously are not present in any of the polymeric foams of the prior art.
• the mechanical properties such as toughness and strain at break are also improved, this enables their utilization as lightweight structural support, and in several areas such as catalysis, thermal insulation, sound insulation, electromagnetic shielding and tissue engineering.
• the present disclosure provides a process for producing the closed-cellpolymeric foams herein disclosed, which comprises
• polyacrylate polymer a polyalkylacrylate polymer and mixtures thereof, and the disperse phase comprising at least a polyolefin polymer
• a closed- cell polymeric foam having a polymer matrix comprising a continuous polymer phase and a disperse polymer phase; the continuous polymer phase comprising at least one of a polyacrylate polymer, a polyalkylacrylate polymer and mixtures thereof in a concentration of at least 90 % w/w of the total continuous polymer phase weight; and the disperse polymer phase
• the amount of continuous polymer phase is comprised of from 80 % w/w to 99.8% w/w of the total polymer matrix, obtainable by the process of the invention.
• Fig. 1 SEM micrographs of the cellular structure of several foams produced after CO 2 saturation at 25°C, at 30MPa (Fig. 1A), 10 MPa (Fig. 1 B) and 5MPa (Fig. 1 C) from neat polyalkylacrylate (PMMA, Comparative example CE1 Table I).
• FIG. 2 SEM micrographs of the cellular structure of several foams produced after CO 2 saturation at 25°C, at 30MPa (Fig. 2A), 10 MPa (Fig. 2B) and 5MPa (Fig. 2C) from a polyalkylacrylate/polyolefin mixture (PMMA/EBA, Example E1 Table I).
• FIG. 3 SEM micrographs of the cellular structure of several foams produced after CO 2 saturation at 25°C, at 30MPa (Fig. 3A), 10 MPa (Fig. 3B) and 5MPa (Fig. 3C) from a polyalkylacrylate/polyolefins mixture (PMMA/EBA-EVOH, Example E2 Table I).
• Fig. 4 SEM micrographs of the cellular structure of several foams produced after CO 2 saturation at 10MPa, at 25°C (Fig. 4A), 75°C (Fig. 4B) and 90°C (Fig. 4C) from neat polyalkylacrylate (PMMA, Comparative Example CE1 Table I).
• FIG. 5 SEM micrographs of the cellular structure of several foams produced after CO 2 saturation at 10MPa, at 25°C (Fig. 5A), 75°C (Fig. 5B) and 90°C (Fig. 5C) from a polyalkylacrylate/polyolefin mixture (PMMA/EBA, Example E1 Table I).
• PMMA/EBA polyalkylacrylate/polyolefin mixture
• FIG. 6 SEM micrographs of the cellular structure of several foams produced after CO 2 saturation at 10MPa, at 25°C (Fig. 6A), 75°C (Fig. 6B) and 90°C (Fig. 6C) from a polyalkylacrylate/polyolefins mixture (PMMA EBA-EVOH, Example E2 Table I).
• PMMA refers to poly(methylmethacrylate)
• EBA refers to ethylene- butyl acrylate
• EVOH refers to ethylene-vinyl alcohol.
• any ranges given include both the lower and the upper end-points of the range. Ranges given, such as temperatures, times, sizes, concentrations, and the like, should be considered approximate, unless specifically stated.
• foams are defined as materials containing gaseous voids surrounded by a denser matrix, which is usually a liquid or solid. Depending on the composition, cell morphology, and physical properties, polymer foams can be categorized as rigid or flexible foams.
• polymer foams can be classified as macrocellular (with cell sizes higher than 1000 ⁇ ), microcellular (with cell sizes comprised from 1 ⁇ to 1000 ⁇ ), submicrocellular (with cell sizes comprised from 30 nm to 3 ⁇ ), and nanocellular (with cell sizes comprised from 1 nm to 100 nm).
• macrocellular with cell sizes higher than 1000 ⁇
• microcellular with cell sizes comprised from 1 ⁇ to 1000 ⁇
• submicrocellular with cell sizes comprised from 30 nm to 3 ⁇
• nanocellular with cell sizes comprised from 1 nm to 100 nm.
• an acceptable overlapping in the values of the different classification is generally accepted. That overlapping is due to the term "cell size” is generally linked to a distribution of cell sizes, which may be narrow or broad.
• a "submicrocellular cell size” must be understood as an average cell size which falls within a distribution of cell size around 1 ⁇ .
• Polymer foams can also be defined as either closed-cell or open-cell foams.
• closed-cell foams the voids are isolated from each other and cavities are surrounded completely by the cell wall.
• open-cell foams cell walls are broken and the structure consists mainly of ribs and struts.
• closed cell foams have lower permeability, leading to better insulation properties.
• Closed cell foams are usually characterized by their rigidity and strength, in addition to the high R-value (Resistance to heat flow).
• Relative density (p re i) It is defined as the density of the foamed material (p f ) divided by the density of the solid material before foaming (p s ). Density of solid samples was measured with a gas pycnometer (Mod.
• Porosity (P) It is volume fraction (in percentage) of the gas phase. It is calculated using the following equation:
• Expansion ratio It is defined as the inverse of the relative density (p re i).
• N v Cell density
• micrographs are required, only the micrograph area (A) in cm 2 and the total number of cells (n) contained in the micrograph are measured. From these values N v can be calculated using the following equation:
• Cell nucleation density (N 0 ): It is defined as number of cells per cubic centimetre of the unfoamed solid material. This parameter can be calculated using the following equation:
• Average cell size ( ⁇ ) The three dimensional average cell size was obtained with a specialized software (Pinto J, Solorzano E, Rodriguez-Perez MA, de Saja JA. J Cell Plast 2013;49(6):555-575) based on ImageJ/FIJI (Abramoff MD, Magalhaes PJ, Ram SJ. Biophot Int 2004;1 1 (7):36-42). This software provides the cell size distribution, the average cell size ( ⁇ ), the standard deviation of the cell size distribution (SD), the cell anisotropy ratio
• Anisotropy ratio is defined as the ratio between the average cell size in two perpendicular directions.
• Potential nucleation density is defined as the ratio between the number of nucleants and the volume of an individual nucleant. For a nucleating agent it is calculated using the following equation: [Spitael, P.; Macosko, C. W.;
• ⁇ ⁇ is the nucleating agent content
• Pc is the density of the blend under study (polymer containing the nucleating agent)
• p p is the density of the nucleating agent
• v p is the volume of one individual particle of the nucleating agent.
• a value of 1 for this parameter means that each nucleating particle is able to create one cell in the final foam.
• a value much lower than one means that the nucleating agent has a poor efficiency and/or that processes that reduce the number of cells in the foam such as coalescence or coarsening are playing a key role during the production of the material.
• Degeneration Ratio It is defined as the inverse of the Nucleation Efficiency. In the context of the present disclosure, the term “percentage (%) by weight” refers to the percentage of each ingredient of the combination or composition in relation to the total weight.
• copolymer refers to both homopolymer and copolymer. Unless otherwise indicated, “copolymer” includes block copolymer, graft copolymer, alternating copolymer and random copolymer.
• alkylacrylate monomer refers to derivatives of alkylacrylic acid and the term “acrylate monomer” referes to derivatives of acrylic acid.
• polyacrylate polymer refers to polymerized acrylate monomers, whereas the term “polyalkylacrylate polymer” refers to polymerized
• alkylacrylate polymer can be a copolymer containing both alkylacrylate monomers and acrylate monomers and as such can be both an alkylacrylate polymer and an acrylate polymer.
• the polymeric foams of the present disclosure have a polymer matrix which comprises a continuous polymer phase and a disperse polymer phase.
• the continuous polymer phase defines a plurality of cells therein.
• the closed- cell polymeric foams may show an average cell size in the range of submicrocellular cell sizes, i.e. ranging from 30 nm to 3 ⁇ ; in some embodiments the average cell size ranges from 300 nm to 2.8 ⁇ ; in some other embodiments, the average cell size ranges from 600 nm to 2.75 ⁇ . In accordance with some embodiments, the average cell size ranges from 500 nm to 2.6 ⁇ .
• both the continuous polymer phase and the disperse polymer phase may contain one or more additives. Therefore, the additives may be present in the continuous polymer phase, in the disperse polymer phase or in both phases
• the additives are present in both polymer phases simultaneously, thus allowing an homogeneous distribution thereof in the polymeric foam.
• additives such as fillers (for example, talc, silica, titania, magnesia, calcium carbonate, carbon black, graphite, magnesium silicate or clays such as kaolinite and montmorillonite); flame retardants (for example, halogenated flame retardants, such as hexabromocyclododecane and brominated polymers,or phosphorous flame retardants such as
• triphenylphosphate dimethyl methylphosphonate, red phosphorous or aluminium diethyl phosphinate
• acid scavengers for example, calcium stearate, magnesium oxide, zinc oxide, tetrasodium pyrophosphate or hydrotalcite
• antioxidants for example, sterically hindered phenols, phosphites and mixtures thereof
• pigments and blowing agent stabilizers for example, pigments and blowing agent stabilizers.
• Sterically hindered phenols are well known in the art and refer to phenolic compounds which contain sterically bulky radicals, such as tert-butyl, in close proximity to the phenolic hydroxyl group thereof.
• phenolic compounds substituted with tert-butyl groups in at least one of the ortho positions relative to the phenolic hydroxyl group.
• the sterically hindered phenol has tert-butyl groups in both ortho-positions with respect to the hydroxyl group.
• hindered phenols include pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4- hydroxyphenyl)propionate), 1 ,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4- hydroxybenzyl) benzene, n-octadecyl-3(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 4,4'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-thiobis(6-tert- butyl-o-cresol), 6-(4-hydroxyphenoxy)-2,4-bis(n-ocytlthio)-1 ,3,5-triazine, 2,4,6- tris(4-hydroxy-3,5-di-tert-butyl-phenoxy)-1 ,3,5-triazine, di-n-octadecy
• the continuous polymer phase comprises at least one of a polyacrylate polymer, a polyalkylacrylate polymer and mixtures thereof, in combination with one or more additives.
• the continuous polymer phase comprises at least one of a polyacrylate polymer, a polyalkylacrylate polymer and mixtures thereof in a concentration comprised from 90 to 99.9 % w/w of the total continuous polymer phase weight, preferably from 95 to 99.8 % w/w of the total continuous polymer phase weight, yet more preferably from 97 to 99.7 % w/w of the total continuous polymer phase weight; the rest being additives such as fillers, flame retardants, acid scavengers, antioxidants, pigments and blowing agent stabilizers; being the sum total of components of the continuous polymer phase 100% w/w.
• the disperse polymer phase comprises at least a polyolefin polymer in combination with one or more additives.
• the disperse polymer phase comprises at least a polyolefin polymer in a concentration comprised from 90 to 99.
• the composition of the invention comprises, either in the continuous polymer phase, in the disperse polymer phase or in both the continuous and the disperse polymer phase simultaneously, from 0.01 to 0.3 % w/w, preferably 0.1 -0.15 % w/w of at least one antioxidant selected from sterically hindered phenols, aromatically substituted phosphites and mixtures thereof.
• the antioxidant is a mixture of a sterically hindered phenol and an aromatically substituted phosphite, e.g. a mixture of
• the disperse polymer phase comprises at least a homopolymer or copolymer of ethylene or a homopolymer or copolymer of propylene having a minimun content of ethylene or propylene of 50 % w/w based on the total of the disperse polymer phase.
• the disperse polymer phase comprises an homopolymer or copolymer of ethylene having a minimun content of ethylene of 50 weight percent based on the total of the disperse polymer phase.
• the homopolymer or copolymer of ethylene have a minimun content of ethylene of 55 % w/w; yet more preferably 60 % w/w; still more preferably 65 % w/w: being particularly preferably 70 % w/w.
• suitable copolymers of ethylene include ethylene-vinyl acetate (EVA), ethylene-butyl acrylate (EBA), ethylene-vinyl-alcohol (EVOH) copolymers and mixtures thereof (EBA-EVOH and EVA-EVOH) and low density polyethylene (LDPE) or linear low density polyethylene (LLDPE).
• EVA-EVOH and EVA-EVOH low density polyethylene
• LLDPE linear low density polyethylene
• LDPE or LLDPE polymers are ethylene-propylene copolymers, ethylene-butene copolymers, ethylene-hexene copolymers, and ethylene- octene copolymers.
• the disperse polymer phase comprises an homopolymer or copolymer of propylene having a minimun content of propylene of 50 weight percent based on the total of the disperse polymer phase.
• the homopolymer or copolymer of propylene have a minimun content of ethylene of 55 % w/w; yet more preferably 60 % w/w; still more preferably 65 % w/w: being particularly preferably 70 % w/w.
• Suitable copolymers of propylene include heterophasic or impact copolymers, plastomers and propylene-ethylene-butene terpolymers.
• heterophasic copolymers are copolymers having polypropylene homopolymer as a continuous phase and a disperse phase of ethylene-propylene rubber which shows the following properties: Flexural Modulus higher than700 MPa (UNE-EN ISO 178 standard method) and Charpy Notched Impact Strength (23°C) comprised from 3KJ/m 2 and 70 KJ/m 2 (UNE-EN ISO 179/1 standard method).
• terpolymer refers to polymers having two co-monomers ramdonly distributed showing the following properties: Flexural Modulus lower thanl 100 MPa (UNE-EN ISO 178 standard method) and Charpy Notched Impact Strength (23°C) comprised from 3KJ/m 2 and 50 KJ/m 2 (UNE-EN ISO 179/1 standard method).
• plastomer refers to a polymer having a co-monomer higher than 5 % w/w randomly distributed showing the following properties: Flexural Modulus ⁇ 700 MPa (UNE-EN ISO 178 standard method) and Charpy Notched Impact Strength (23°C) comprised from 6KJ/m 2 and 70 KJ/m 2 (UNE-EN ISO 179/1 standard method).
• the continuous polymer phase comprises at least one of a polyacrylate polymer, a
• polyalkylacrylate polymer and mixtures thereof.
• suitable polyalkylacrylate and polyacrylate polymers include poly(methylmethacrylate) (PMMA), poly(ethylmethacrylate) (PEMA), poly(butylmethacrylate) (PBMA), poly(methylacrylate) (PMA), poly(ethylacrylate) (PEA), poly(butylacrylate) (PBA), copolymers of methylmethacrylate and/or ethylmethacrylate with methylacrylate, ethylacrylate, butylacrylate, butylmethacrylate, acrylic acid, methacrylic acid, vinyl acetate or acrylonitrile.
• PMMA poly(methylmethacrylate)
• PEMA poly(ethylmethacrylate)
• PBMA poly(butylmethacrylate)
• PMA poly(methylacrylate)
• PEA poly(ethylacrylate)
• PBA poly(butylacrylate) (
• polyalkylacrylate polymer is PMMA.
• Particularly preferred examples of mixtures are PMMA/PMEA, PMMA/PMBA, PMMA/PMA, PMMA/PBA and PMMA/PEA.
• the continuous polymeric phase may contain a mixture of one or more polyalkylacrylates; or a mixture of one or more polyacrylates and one or more polyalkylacrylates; or alternatively a mixture of one or more polyacrylates.
• the amount of continuous polymer phase is comprised of from 80 % w/w to 99.8 % w/w of the total polymer matrix; yet more preferably from 85 % w/w to 99.5 % w/w; still more preferably frorm 90 % w/w to 98 % w/w.
• the continuous polymer phase comprises at least one of a polyacrylate polymer, a polyalkylacrylate polymer and mixtures thereof selected from poly(methylmethacrylate) (PMMA), poly(ethylmethacrylate) (PEMA), poly(butylmethacrylate) (PBMA), poly(methylacrylate) (PMA), poly(ethylacrylate) (PEA), poly(butylacrylate) (PBA), copolymers of methylmethacrylate and/or ethylmethacrylate with methylacrylate,
• a polyacrylate polymer a polyalkylacrylate polymer and mixtures thereof selected from poly(methylmethacrylate) (PMMA), poly(ethylmethacrylate) (PEMA), poly(butylmethacrylate) (PBMA), poly(methylacrylate) (PMA), poly(ethylacrylate) (PEA), poly(butylacrylate) (PBA), copolymers of methylmethacrylate and/or
• the disperse polymer phase comprises a copolymer of ethylene selected from ethylene- vinyl acetate (EVA), ethylene-butyl acrylate (EBA), ethylene-vinyl-alcohol (EVOH) copolymers and mixtures thereof (EBA-EVOH and EVA-EVOH) and low density polyethylene (LDPE) or linear low density polyethylene (LLDPE), in a concentration comprised from 90 to 99.9 % w/w of the total disperse polymer phase weight, preferably from 95 to 99.8 %
• the continuous polymer phase comprises at least one of poly(methylmethacrylate) (PMMA), poly(ethylmethacrylate) (PEMA), poly(butylmethacrylate) (PBMA), poly(methylacrylate) (PMA),
• PMMA poly(methylmethacrylate)
• PEMA poly(ethylmethacrylate)
• PBMA poly(butylmethacrylate)
• PMA poly(methylacrylate)
• the disperse polymer phase comprises a copolymer of ethylene selected from ethylene-vinyl acetate (EVA), ethylene-butyl acrylate (EBA), ethylene-vinyl-alcohol (EVOH) copolymers and mixtures thereof (EBA-EVOH and EVA-EVOH) and low density polyethylene (LDPE) in a concentration comprising from 95 % to 99.8 % w/w of the total disperse polymer phase weight; and wherein the amount of continuous polymer phase is comprised of from 90 % w/w to 98 % w/w of the total polymer matrix.
• EVA ethylene-vinyl acetate
• EBA ethylene-butyl acrylate
• EVOH ethylene-vinyl-alcohol copolymers and mixtures thereof
• LDPE low density polyethylene
• the continuous polymer phase have poly(methylmethacrylate) polymer, being the concentration of poly(methylmethacrylate) (PMMA) in the range of 99.5 % w/w to 99.8 % w/w of the total continuous polymer phase weight; and the disperse polymer phase comprises a copolymer of ethylene selected from ethylene-vinyl acetate (EVA), ethylene-butyl acrylate (EBA), ethylene-vinyl-alcohol (EVOH) copolymers (EVOH) and mixtures thereof (EBA-EVOH and EVA-EVOH) and low density polyethylene (LDPE) in a concentration in the range of 99.5 % w/w to 99.8 % w/w of the total disperse polymer phase weight; and wherein the amount of continuous polymer phase is comprised of from 85 % w/w to 90 % w/w of the total polymer matrix.
• EVA ethylene-vinyl acetate
• EBA ethylene-buty
• Another aspect of the present invention refers to processes for producing the submicrocellular polymeric foams herein disclosed.
• the process may be a batch process, a semi-continuous process or a continuous extrusion foam process.
• the skilled person in the art knows different preparation processes which may be applicable to the preparation of both the continuous or the disperse polymer phase.
• the continuous phase may be prepared for example by melt- blending together the at least one of a polyacrylate polymer, a
• the disperse polymer phase may be prepared by a similar process.
• the mixture of continuous polymer phase and disperse polymer phase is impregnated with a blowing agent to produce an expandable polymeric mixture.
• the blowing agent may be selected from any blowing agent commonly known in the art. Suitable blowing agents include any one or combination of more than one of inorganic gases such as argon, nitrogen, carbon dioxide, water and air; organic blowing agents such as aliphatic and cyclic hydrocarbons having from one to nine carbons including methane, ethane, n-propane, iso- propane, n-butane, iso-butane, n-pentane, iso-pentane, neo-pentane, cyclobutane and cyclopentane; fully and partially halogenated alkanes and alkenes having from one to five carbons, preferably the ones that are chlorine-free (e.g., difluoromethane (HFC-32), perfluoromethane, ethyl fluoride (HFC- 161 ), 1 , 1 ,- difluoroethane (HFC- 152a), 1 ,1 ,
• HFC- 143a 1 ,1 ,2,2-tetrafluoroethane (HFC- 134), 1 ,1 ,1 ,2 tetrafluoroethane (HFC- 134a), pentafluoroethane (HFC-125), perfluoroethane, 2,2- difluoropropane (HFC-272fb), 1 ,1 ,1 -trifluoropropane (HFC-263fb), 1 ,1 ,1 ,2,3,3, 3-heptafluoropropane (HFC-227ea), 1 ,1 ,1 ,3,3-pentafluoropropane (HFC- 245fa), and 1 , 1 ,1 ,3,3-pentafluorobutane (HFC-365mfc)); aliphatic alcohols having from one to five carbons such as methanol, ethanol, n-propanol, and isopropanol; carbon
• the blowing agent comprises CO 2 , N 2 , n-pentane, n-butane, s- butane, s-pentane and mixtures thereof.
• the blowing agent concentration in an expandable polymer composition is preferably comprised from 10 % w/w to 40 % w/w relative to total expandable polymeric mixture weight; more preferably from 15 % w/w to 30 % w/w; yet more preferably from 20 % w/w to 28 % w/w.
• Impregnation step with the blowing agent is preferably performed at a pressure of at least 5 MPa, preferably at least 10 MPa; and at a temperature of at least 10°C, preferably 25°C.
• the foaming step is performed at a saturation pressure in the range of 1 -30 MPa, preferably from 10 to 25 MPa; and at a temperature comprised of from 50-120 °C preferably 70-1 10°C.
• the closed-cell polymeric foam according to the present disclosure is characterized by having a cell density, measured according to the method described in Kumar et al., Polym Eng Sci 1990; 30(20):1323-1329, comprised from 10 10 to 10 18 cells/cm 3 ; preferably from 10 11 to 10 16 cells/cm 3 .
• the submicrocellular polymeric foam of the present disclosure has a porosity percentage comprised from 50 % to 99.9%; preferably from 60% to 90%.
• the closed-cell polymeric foam according to the present disclosure may be characterized by a relative density comprised from 0.1 to 0.6, preferably from 0.1 to 0.45, more preferably from 0.1 to 0.4.
• the closed-cell polymeric foam according to the present disclosure may be characterized by an impact resistance, measured according to UNE-EN ISO 179/1 standard method , comprised from 1 -30 KJ/m 2 ; preferably from 1 -20 KJ/m 2 ; more preferably from 1 -15 KJ/m 2 .
• the closed-cell polymeric foam according to the present disclosure may be characterized by a glass transition temperature, measured according to UNE- EN ISO 1 1357-1 :2010 and ISO 1 1357-3:1 1 , comprised from 60-180 °C;
• the closed-cell polymeric foam according to the present disclosure may be characterized by an storage modulus, measured according to DMA analysis, comprised from 200-500 MPa; preferably from 200-400 MPa; more preferably from 220-380 MPa.
• the closed-cell polymeric foam according to the present disclosure may be characterized by having
• an impact resistance measured according to UNE-EN ISO 179/1 standard method , comprised from 1 -30 KJ/m 2 ;
• the closed-cell polymeric foam according to the present disclosure may be characterized by having
• an impact resistance measured according to UNE-EN ISO 179/1 standard method , comprised from 1 to 15 KJ/m 2 ;
• a glass transition temperature measured according to UNE-EN ISO 1 1357-1 :2010 and ISO 1 1357-3:1 1 , comprised from 1 15 to 129 °C;
• an storage modulus measured according to DMA analysis, comprised from 200 to 400 MPa.
• Foaming may be performed by any foaming technique known in the art which is suitable for preparing thermoplastic polymeric foams including batch tank foaming and extrusion foaming.
• Batch tank foaming process comprises providing a thermoplastic polymer matrix that contains any optional additives into a pressure vessel (tank), providing blowing agent into the vessel and pressurizing the inside of the vessel with a pressure high enough so as to dissolve the blowing agent in the thermoplastic polymer matrix to a desired concentration. Once a desired concentration of blowing agent is dissolved in the thermoplastic polymer matrix, the pressure in the vessel is relieved while the thermoplastic polymer matrix is in a softened state at the foaming temperature, and the
• thermoplastic polymer matrix is allowed to expand into a thermoplastic polymeric foam article.
• An extrusion process can be continuous or semi-continuous (for example, accumulative extrusion).
• An extrusion foam process comprises providing a foamable composition in an extruder at an initial pressure and in a softened state and then expelling the foamable composition at a foaming temperature into an environment of lower pressure than the initial pressure to initiate expansion of the foamable composition into a thermoplastic polymer foam.
• a general extrusion process comprises preparing a foamable polymer composition by mixing a thermoplastic polymer with a blowing agent in an extruder by heating the thermoplastic polymer composition in order to soften it, mixing a blowing agent composition together with the softened
• thermoplastic polymer composition at a mixing (initial) temperature and initial pressure which precludes expansion of the blowing agent to any meaningful extent (preferably, that precludes any blowing agent expansion), desirably cooling the foamable polymer composition to a foaming temperature rather than using the initial temperature as the foaming temperature, and then expelling the foamable composition through a die into an environment having a temperature and pressure below the foaming temperature and initial pressure. Upon expelling the foamable composition into the lower pressure environment the blowing agent expands the thermoplastic polymer into a thermoplastic polymer foam.
• the process also comprises the steps of desirably, cooling the foamable composition after mixing and prior to expelling it through the die.
• accumulative extrusion is a semi-continuous extrusion process that comprises: 1 ) mixing a thermoplastic material and a blowing agent composition to form a foamable polymer composition; 2) extruding the foamable polymer composition into a holding zone which is maintained at a temperature and pressure which do not allow the foamable polymer composition to foam; the holding zone having a die defining an orifice opening into a zone of lower pressure at which the foamable polymer composition foams and an openable gate closing the die orifice; 3) periodically opening the gate while substantially concurrently applying mechanical pressure by means of a movable ram on the foamable polymer composition to eject it from the holding zone through the die orifice into the zone of lower pressure, and 4) allowing the ejected foamable polymer composition to expand into foam.
• the glass transition temperature (Tg), the melting temperature (Tm) and crystallinity were determined by Differential Scanning Calorimetry (DSC) according to UNE-EN ISO 1 1357-1 :2010 and ISO 1 1357-3:1 1 and the melt flow index (MFI) at 230°C and 3,8 Kg according to UNE-EN ISO 1 133:2001 .
• the polymeric foam samples of the invention were polished using a polishing machine (model LaboPOI2-LaboForce3, Struers) equipped with a silicon carbide grinding paper (P 180) to obtain homogeneous surfaces and to remove the outer solid or dense skin of the samples (Pinto J, Pardo S, Solorzano E, Rodriguez- Perez MA, Dumon M, de Saja JA. Defect Diffus Forum 2012;326-328:434- 439).
• a polishing machine model LaboPOI2-LaboForce3, Struers
• P 180 silicon carbide grinding paper
• samples had an average thickness of around 5 mm. Then, solid and polished samples were machined in different ways according to the test to be performed. Thus, DMA samples were prepared using a precision cutting machine Mod. 1000 from IsoMet. The test pieces were prepared to be approximately 2 mm in thickness, 7 mm in width, and 25 mm in length.
• a 0.5 J pendulum for Charpy impact testing Frank was used in order to determine the mechanical behavior at high strain rates. At least three specimens were used for each sample, all of them carried out at controlled humidity and temperature and performed according to UNE-EN ISO 179-1 . Viscoelastic behavior of foamed samples both at room temperature and as a function of temperature was analyzed using a dynamic mechanical analyzer model DMA 7 from Perkin Elmer. The experiments were performed in a three- point bending configuration with a frequency of 1 Hz and a dynamic stress of 3- 10 4 kPa for foams and of 1 ⁇ 10 5 kPa for the solids. A static stress of 1 ,2 times the value of the dynamic stress was applied in all the conducted tests.
• Measurements as a function of temperature were carried out at a rate of 3 °C/min from 0 to 1 10 °C. The onset of temperature was maintained constant during 3 min before starting the experiment in order to assure an equilibrium temperature.
• foamed and solid sample densities were determined according to internal methods or using conventional techniques. Particularly, the foamed and solid sample densities were determined by water displacement method, based on Archimedes' principle, using the density determination kit for an AT261 Mettler-Toledo balance. At least three measurements were carried out for each sample produced.
• the total amount of gas uptake was calculated as the percentage of weight increment of the sample due to the gas sorption.
• the final weight of the samples after the whole saturation process was evaluated from the
• the cellular structure of foamed samples was analyzed by SEM using an FEI Quanta 200FEG scanning electron microscope according to the following procedure. Foams were frozen in liquid nitrogen and fractured to assure that the microstructure remained intact. The fractured surface was coated with gold using a sputter coater (model SCD 004, Balzers Union). Some of the key parameters of the cellular structure were obtained with a specialized software (Pinto J, Solorzano E, Rodriguez-Perez MA, de Saja JA. J Cell Plast
• This method also provides an expression (Eq. (2)) to estimate the cell nucleation density (N 0 , number of cells per cubic centimetre of the solid unfoamed material) from N v and the relative density of the foam (p re i). This equation assumes that coalescence did not occur during the cell growing and stabilization stages:
• PLEXIGLAS V825 is a thermoplastic acrylic resin (PMMA) supplied by Arkema.
• EBA is an Ethylene Butyl acrylate resin (EBA) supplied by Repsol Quimica.
• EVAL F171 B is an Ethylene Vinyl Alcohol (EVOH) resin supplied by Kuraray.
• LDPE Low Density Polyethylene resin
• ALCUDIA PA539 is an Ethylene Vinyl Acetate resin (EVA) supplied by Repsol Quimica.
• Examples E1 -E7 and Comparative Examples CE1 -CE3 were obtained by blending Polyalkylacrylate and Polyolefins with different Polyalkylacrylate and Polyolefin amounts (from 5 to 70 wt%) in an extruder (Table I). All the materials were dried at 50 °C during 10 h prior to the extrusion. In particular, a ZSK-25 Coperion's twin screw extruder was operated using a temperature profile of 160 to 225°C at 12 Kg/h and 200 rpm. Pellets from each blend were obtained using a continuous cutting machine operating at the end of the extrusion line. In all cases ca.
• Example CE1 was prepared without using Polyolefin material.
• Example E2 and Comparative Example CE3 were prepared using a masterbatch of two Polyolefins (75% EBA/25%
• Polyacrylates and Polyolefin pellets were first dried in vacuum (680 mm Hg) at 50°C during 24 h before processing. Then, they were compression molded into precursors of 4 mm in thickness using a two-hot plates press. The temperature of the press was fixed at 250°C. The material was first molten without pressure for 8.5 min, then it was compacted under a constant pressure of 21 .8 bars for another minute and finally it was cooled down under the same pressure. The samples showed a good surface appearance with no presence of air bubbles inside the parts. Finally, these molded precursors were cut at 2.5 x 2.5 x 4 mm 3 dimensions and used later for foaming.
• the physical properties of the novel Polyalkylacrylate/Polyolefin solid precursors are summarized in Table III.
• the disperse phase diameter of the solid precursor is calculated in the same way as average cell size.
• the reactor is equipped with an accurate pressure pump controller (model SFT-10) provided by Supercritical Fluid Technologies Inc., and it is controlled automatically to keep the pressure at the desired values.
• the vessel is equipped with a clamp heater of 1200 W, and its temperature is controlled via a CAL 3300 temperature controller.
• the CO 2 vessel is equipped with a clamp heater of 1200 W, and its temperature is controlled via a CAL 3300 temperature controller.
• Comparative examples CE2 and CE3 consisted of 30% PLEXIGLAS V825 and 69.9% Polyolefins supplied commercially by Repsol Quimica SA do not foam and show values of density/disperse phase diameter as expected for the solid precursors.
• Ratio Degeneratio Ratio
• Table VI Physical properties of the novel Polyalkylacrylate/Polyolefin foams: Polyolefin Chemical Composition Effect on mechanical properties.
• polymeric foam compositions according to this invention present higher impact resistance, glass transition temperature and storage modulus normalized by the square of the relative density.
• these polymeric compositions have excellent relative and absolute densities. Therefore, a good balance between mechanical properties and sustainability of the materials is obtained in the polymeric compositions of this invention.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=58413037

Family Applications (1)

Country Status (2)

Families Citing this family (1)

Family Cites Families (3)

• 2018
  • 2018-03-09 EP EP18708444.7A patent/EP3592804A1/de not_active Withdrawn
  • 2018-03-09 WO PCT/EP2018/055920 patent/WO2018162717A1/en active Application Filing

Also Published As

Similar Documents

Legal Events