Foams made with silicone-functionalized polyethylene and methods for making same

Abstract

According to various embodiments, an extruded foam is formed from a composition comprising 1 to 99 weight percent of a silicone-functionalized polyethylene comprising the reaction product of the polymerization of ethylene and a (meth)acrylate-functionalized polydimethylsiloxane, and a physical blowing agent. The foam has a density of 0.200 g / cm3 or less as measured according to ASTM D1622-88 at 25°C. 3 It has the following density:

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to ethylene polymer foams, and more particularly to foams made using silicone-functionalized polyethylene. [Background technology]

[0002] 0.200 g / cm, known as "low density foam" 3 Conventional polyethylene foams having densities less than 1000 MPa can be produced by a variety of processes and using a variety of polymers. However, the processes for producing such foams can exhibit low foaming efficiency. Furthermore, such foams, especially when produced by extrusion processes, are typically limited to closed-cell structures.

[0003] Therefore, there is a need for alternative ethylene polymer foams. Summary of the Invention

[0004] The present disclosure meets these needs by providing extruded foams formed from compositions comprising a silicone-functionalized polyethylene comprising a functionalized polydimethylsiloxane bonded to the polyethylene and a physical blowing agent. In embodiments, the foams have a density of 0.200 g / cc or less, as measured in accordance with ASTM D1622-88 at 25°C. Such foams can have an open-cell or closed-cell structure and, in embodiments, exhibit improved blowing agent efficiency (i.e., lower density) than foams that do not contain the silicone-functionalized polyethylene using the same amount of blowing agent.

[0005] According to a first embodiment of the present disclosure, an extruded foam is formed from a composition comprising 1 to 99 wt. % of a silicone-functionalized polyethylene comprising the reaction product of the polymerization of ethylene and a (meth)acrylate-functionalized polydimethylsiloxane, and a physical blowing agent, wherein the foam has a density of 0.200 g / cm or less as measured in accordance with ASTM D1622-88 at 25°C.

[0006] According to a second embodiment, the extruded form comprises the extruded foam of the previous embodiment, wherein the silicone functionalized polyethylene has a polydispersity index (PDI) of 3-14.

[0007] According to a third embodiment, the extruded form comprises the extruded foam of any of the previous embodiments, wherein the silicone functionalized polyethylene has the following structure:

[0008] [ka] wherein R is methyl or hydrogen, R1 is a bridging group connecting the functional group ((meth)acrylate) with the siloxane, R2 is a terminal group selected from the group consisting of alkyl, substituted alkyl, aryl, alkenyl, H, and OH, x is an integer from 10 to 1000, and y is an integer from 1 to 20.

[0009] According to a fourth embodiment, the extruded form comprises the extruded foam of any of the previous embodiments, wherein the composition further comprises greater than 0 to 99 wt. % of an olefin polymer.

[0010] According to a sixth embodiment, the extruded form comprises the extruded foam of any of the previous embodiments, wherein the olefin polymer comprises LDPE.

[0011] According to a seventh embodiment, the extruded form comprises the extruded foam of any of the previous embodiments, wherein the composition further comprises greater than 0 to 2 wt. % of a permeability modifier.

[0012] According to an eighth embodiment, the extruded form comprises the extruded foam of any of the previous embodiments, wherein the permeability modifier comprises an amide or ester of a C10 to C24 fatty acid.

[0013] According to a ninth embodiment, the extruded form comprises the extruded foam of any of the previous embodiments, wherein the physical blowing agent comprises isobutane, carbon dioxide, n-butane, an isomer of pentane, a hydrocarbon, or a mixture thereof.

[0014] According to a tenth embodiment, the extruded form comprises the extruded foam of any of the previous embodiments, wherein the physical blowing agent is present in an amount of 5 to 20 wt %.

[0015] According to an eleventh embodiment, the extruded form comprises the extruded foam of any of the previous embodiments, wherein the foam is open-celled.

[0016] According to a twelfth embodiment, the extruded form comprises the extruded foam of any of the previous embodiments, wherein the foam has a density of 0.090 to 0.200 g / cm 3 It has a density of

[0017] According to a thirteenth embodiment, the extruded form comprises the extruded foam of any of the first to tenth embodiments, wherein the foam is closed-cell.

[0018] According to a fourteenth embodiment, the extruded form comprises the extruded foam of any of the first to tenth or thirteenth embodiments, the foam having a density of 0.015 to 0.200 g / cm 3 It has a density of

[0019] These and other embodiments are described in more detail in the detailed description that follows. DETAILED DESCRIPTION OF THE INVENTION

[0020] Specific embodiments of the present application will now be described. However, this disclosure may be embodied in different forms and should not be construed as limited to the embodiments set forth in this disclosure. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present subject matter to those skilled in the art.

[0021] definition All references to the Periodic Table of the Elements are to the International Union of Pure and Applied Chemistry (IUPAC) Periodic Table.

[0022] Numerical ranges disclosed herein include all values ​​from the lower limit to the upper limit, inclusive. Ranges including explicit values ​​(e.g., 1 or 2, or 3-5, or 6, or 7) include all subranges between any two explicit values ​​(e.g., the 1-7 range above includes subranges of 1-2, 2-6, 5-7, 3-7, 5-6, etc.).

[0023] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percentages are by weight and all test methods are current as of the filing date of this disclosure.

[0024] The term "composition" refers to a mixture of materials that comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0025] The terms "comprising," "including," "having," and their derivatives are not intended to exclude the presence of any additional element, step, or procedure, whether or not it is specifically disclosed. In contrast, the term "consisting essentially of" excludes from the scope of any subsequent recitation any other component, step, or procedure, excepting those that are not essential to operability. The term "consisting of" excludes any element, step, or procedure not specifically delineated or listed. The term "or," unless expressly stated otherwise, refers to the listed items individually as well as in any combination. The use of the singular includes the use of the plural, and vice versa.

[0026] As used herein, "pendant functional group" refers to a functional group on the polymer backbone at a position other than the terminal end.

[0027] The term "polymer" refers to a polymeric compound prepared by polymerizing monomers of the same or different types, which, in polymerized form, provide multiple and / or repeating "units" that make up the polymer. Thus, the generic term polymer encompasses the term "homopolymer," which is commonly used to refer to a polymer prepared from only one type of monomer, as well as "copolymer," which refers to a polymer prepared from two or more different monomers. It should be noted that while polymers are often referred to as being "made of" one or more particular monomers, "based on" particular monomers or monomer types, "comprising" particular monomer content, etc., in this context, the term "monomer" is understood to refer to the polymerized residue of the particular monomer.

[0028] As used herein, the terms "blend" or "polymer blend" refer to a mixture of two or more polymers. A blend may or may not be miscible (not phase separated at the molecular level). A blend may or may not be phase separated. A blend may be achieved by physically mixing two or more polymers at a macro level (e.g., melt blending resins or compounding) or at a micro level (e.g., co-molding in the same reactor).

[0029] As used herein, the term "terminal alkene group" refers to a double bond between two carbon atoms in a polymer chain, where one of the carbons in the double bond is a =CH group. Terminal double bonds are located at the end of a polymer chain and / or at the end of a branched polymer chain. As used herein, the term "internal alkene group" refers to a 1,2-disubstituted carbon-carbon double bond, where the carbon atoms are in the trans configuration (not the cis configuration). Terminal and internal alkene groups are measured by infrared spectroscopy (IR).

[0030] As used herein, an "olefin-based polymer" or "polyolefin" or "olefin polymer" is a polymer that contains greater than 50 weight percent polymerized olefin monomers (based on the total amount of polymerizable monomers) and may optionally contain at least one comonomer. Non-limiting examples of olefin-based polymers include ethylene-based polymers and propylene-based polymers (such as polypropylene).

[0031] "Polyethylene" or "ethylene polymer" or "ethylene-based polymer" shall mean a polymer containing more than 50 mole percent units derived from ethylene monomers. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of polyethylene known in the art include low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE).

[0032] The term "LDPE" may also be referred to as "high pressure ethylene polymer" or "highly branched polyethylene" and is defined to mean that the polymer is partially or fully homopolymerized or copolymerized in an autoclave or tubular reactor at pressures greater than 14,500 psi (100 MPa) using a free radical initiator such as a peroxide (see, for example, U.S. Pat. No. 4,599,392, incorporated herein by reference). LDPE resins typically have a density in the range of 0.916 to 0.935 g / cm.

[0033] As used herein, the term "siloxane" includes polysiloxanes and lower molecular weight siloxanes. In embodiments, the siloxane is polydimethylsiloxane (PDMS) with various end groups as described below.

[0034] As used herein, the term "cell density" refers to the number of foam cells per unit volume of the foam composition.

[0035] As used herein, the term "closed-cell foam" is a foam in which the foam cells are separated by unopened walls of polymeric material. The closed-cell volume is not readily in fluid communication with its external atmosphere as an open-cell foam. As used herein, the term "open-cell foam" is one in which (i) there are no walls of polymeric material separating the foam cells, or (ii) openings exist in the walls of the polymeric material. The open-cell volume is in fluid communication with its external atmosphere.

[0036] As used herein, the terms "foam" and "foam composition" refer to a structure composed of a polymer and containing a plurality of channels extending from a surface of the structure into and through the structure. The channels are non-directional relative to the longitudinal extension of the structure. The channels contain a plurality of foam cells that are in fluid communication with the external atmosphere. As used herein, the terms "foam cells" or "cells" are discrete spaces within a foam composition. The foam cells are separated or otherwise defined by membrane walls comprising the polymer of the foam composition.

[0037] The term "foaming temperature" refers to the final set point temperature in a foam extruder or other suitable heat exchanger, cooling section, or cooling section of another suitable heat exchanger located immediately upstream of the exit die. For example, the foaming temperature may be the set point temperature of the last zone of the extruder used to cool the foamable composition. The set point temperature may or may not be different from the extrudate (foamable composition) melt temperature measured at the exit die.

[0038] Silicone-functionalized polyethylene Various embodiments include foams prepared from compositions comprising one or more silicone-functionalized polyethylenes and a physical blowing agent. The silicone-functionalized polyethylene comprises a copolymer of ethylene and functionalized polydimethylsiloxane (f-PDMS). In some such embodiments, where the polyethylene is low-density polyethylene (LDPE), the silicone-functionalized polyethylene may be referred to herein as "LDPE-co-PDMS." In embodiments, the copolymer is formed by high-pressure free-radical polymerization by reacting ethylene monomer with f-PDMS or by reacting ethylene monomer with a mixture of functionalized polysiloxanes. In embodiments, the PDMS is bonded to the high-pressure ethylene polymer through several covalent bonds, which result from the reaction of the initial functional groups of the functionalized PDMS with the growing, propagating chain of the ethylene polymer, followed by further reaction with ethylene monomer, including crosslinking between the polymerized functional groups and the siloxane. Methods for preparing LDPE-co-PDMS are described herein.

[0039] In embodiments, the LDPE-co-PDMS may comprise 0.1 wt % to 50 wt % PDMS, such as 0.1 wt % to 20 wt %, 0.1 wt % to 15 wt %, 0.5 wt % to 15 wt %, 3 wt % to 15 wt %, or 5.0 wt % to 15 wt %, based on the total weight of the LDPE-co-PDMS composition, which also includes LDPE formed during copolymerization but not covalently bonded to the PDMS.

[0040] In various embodiments, copolymers of ethylene and f-PDMS include, but are not limited to, LDPE-co-PDMS having one or more of the following structures:

[0041] [ka] where R is methyl or hydrogen, and R 1is a bridging group that connects the functional group ((meth)acrylate) with the siloxane, and R 2 is a terminal group selected from the group consisting of alkyl, substituted alkyl, aryl, alkenyl, H, and OH, x is an integer from 10 to 1000, and y is an integer from 1 to 20. 1 and R 2 The groups may be the same or different.

[0042] In embodiments, the crosslinking groups of the LDPE-co-PDMS are substituted or unsubstituted C-C 20 The linker is selected from alkylene linkers, and one or more carbon atoms may be replaced with oxygen and / or silicon, substituted or unsubstituted aryl groups, and derivatives and combinations thereof. In embodiments, the functional group attached to the crosslinking group is attached to the high-pressure ethylene polymer by polymerization with ethylene monomers. In various embodiments, the functional group is a (meth)acrylate ester group. In further embodiments, the crosslinking group is the group shown below.

[0043] [ka] In the above structural formula, the ethylene-based polymer branch is shown as being polyethylene (PE), however, in embodiments, it is contemplated that the ethylene-based polymer branch may be a homopolymer (e.g., LDPE) or a copolymer, such as an ethylene (meth)acrylic acid ester copolymer, or an ethylene (meth)acrylic acid copolymer, or an ethylene vinyltrimethoxysilane copolymer, or an ethylene vinyl acetate copolymer.

[0044] The polymer comprises polysiloxane units, which in embodiments are derived from a functionalized polydimethylsiloxane (e.g., f-PDMS). In embodiments, the functionalized polysiloxane is a (meth)acrylate ester-functionalized polymethyldisiloxane (f-PDMS), where the (meth)acrylate functional groups are bonded to the PDMS via crosslinks.

[0045] Functionalized Polysiloxane Polysiloxanes can be any of a variety of classes of polymers that are produced as fluids, resins, or elastomers. Polysiloxanes are partially organic compounds, but unlike most polymers, they have a carbon-free backbone, as shown above, and instead are composed of alternating silicon and oxygen atoms. In the structural formula shown above, each silicon is shown as being bonded to a methyl and / or R group, but it is contemplated that each of these positions can individually be alkyl, vinyl, phenyl, hydrogen, hydroxyl, acetoxy, enoxy, oxime, methoxy, ethoxy, alkoxy, dimethylamino, aminopropyl, hydroxypropyl, mercaptopropyl, chloropropyl, acryloxypropyl, methacryloxypropyl, epoxypropoxypropyl, or epoxycyclohexylethyl. In an embodiment, each position is methyl.

[0046] In some embodiments, x is sufficiently large so that the polysiloxane has a viscosity of 100 or more, 200 or more, or 500 or more centistokes (CST). In embodiments, x is no greater than to produce a polysiloxane having a viscosity of 2.5 million CST or less. However, upper viscosity limits below 2.5 million CST, e.g., 1 million or 600,000 CST, are contemplated.

[0047] Suitable polysiloxanes for use in various embodiments include those described in U.S. Patent No. 6,239,244, the entire contents of which are incorporated herein by reference in their entirety. Polysiloxanes are commercially available from several different manufacturers, including, but not limited to, Dow, Momentive, Wacker, Shin-Etsu, and Evonik.

[0048] In various embodiments described herein, the polysiloxane is a polydimethylsiloxane (PDMS) containing one or more functional groups, and is therefore referred to as functionalized PDMS or f-PDMS. In various embodiments, the f-PDMS is a (meth)acrylate ester-functionalized PDMS, where the (meth)acrylate ester groups are bonded to the PDMS via crosslinking groups. The PDMS may be monofunctional, difunctional, or multifunctional, and the functional group(s) may be linked at terminal or pendant positions on the siloxane. Thus, in embodiments, the f-PDMS comprises a structural formula of one of the following formulas or a combination thereof:

[0049] [ka] wherein R is methyl or hydrogen, and R 1 is a bridging group, and R 2 is a terminal group selected from alkyl, aryl, alkenyl, H or OH, x is an integer of 10 to 1000, and y is an integer of 1 to 20).

[0050] Process - Functionalized Polysiloxane In various embodiments, each of the crosslinking groups in f-PDMS is determined by the method by which the siloxane backbone is linked to the (meth)acrylate functional group. In embodiments, the siloxane backbone is linked to the (meth)acrylate functional group via direct hydrosilylation with an alkenyl (meth)acrylate, hydrosilylation of mono- or polyvinyl PDMS using a SiH-functional (meth)acrylate converter, or equilibration / condensation with a (meth)acrylate-functional alkoxysilane. Depending on the specific embodiment, other methods for linking the siloxane backbone to the (meth)acrylate functional group may be contemplated and used.

[0051] Process - Copolymer of ethylene with functionalized polysiloxane In various embodiments, LDPE-co-PDMS is formed in the presence of ethylene. In embodiments, LDPE-co-PDMS is produced via a high-pressure free-radical polymerization process. Two different types of high-pressure free-radical initiated polymerization processes are known. The first process type uses a stirred autoclave reactor with one or more reaction zones. The autoclave reactor contains several injection points for initiator or monomer feed, or both. The second process type uses a jacketed tube reactor, which contains one or more reaction zones. Suitable reactor lengths include, but are not limited to, 100 to 3,000 meters (m) or 1,000 to 2,000 m. In both types of reactor, the start of the reaction zone is typically defined by a side injection of the reaction initiator, ethylene, chain transfer agent (or telomer), comonomer, or a combination thereof. The high-pressure process can be carried out in an autoclave reactor or a tubular reactor with one or more reaction zones, or in a combination of an autoclave reactor and a tubular reactor, each containing one or more reaction zones.

[0052] In various embodiments, chain transfer agents (CTAs) can be used to control polymer properties, including but not limited to, the molecular weight and melt index of the resulting polymer. Chain transfer is associated with the termination of growing polymer chains, thus limiting the final molecular weight of the polymeric material. Chain transfer agents are typically hydrogen atom donors that react with growing polymer chains and terminate the chain polymerization reaction. In the case of high-pressure free-radical polymerization, CTAs can be of many different types, such as saturated hydrocarbons, unsaturated hydrocarbons, aldehydes, ketones, or alcohols. Non-limiting examples of CTAs include propylene, isobutane, n-butane, 1-butene, methyl ethyl ketone, acetone, ethyl acetate, propionaldehyde, products available under the trade name ISOPAR™ (available from ExxonMobil Chemical Co.), and isopropanol. In embodiments, the amount of CTA used in the process is 0.01% to 10% by weight of the total reaction mixture.

[0053] In embodiments, the free radical initiator may include a CTA as a solvent or as a blend for co-injection with ethylene. For example, the CTA may be blended with ethylene, pressurized, and then injected into the reactor.

[0054] In various embodiments, one or more free radical initiators are used to produce LDPE-co-PDMS. Free radical initiators commonly used to produce ethylene-based polymers such as LDPE are oxygen and peroxides. Non-limiting examples of free radical initiators include t-butyl peroxypivalate, di-t-butyl peroxide, t-butyl peroxy acetate (TPA), t-butyl peroxyoctoate (TPO), t-butyl peroxy-2-hexanoate, and combinations thereof. Other initiators known and used in the art are also contemplated. In embodiments, the initiator is included in conventional amounts, such as 0.005% to 0.2% by weight, based on the weight of the polymerizable monomers. In embodiments, the initiator is injected before or within the reaction zone where free radical polymerization is induced. Termination of catalyst activity can be achieved by a combination of high reactor temperatures for the free radical polymerization portion of the reaction, or by feeding the reactor with an initiator dissolved in a polar solvent such as propanol, water, or a mixture of conventional initiator solvents such as branched or unbranched alkanes. In embodiments, the free radical initiator initiates polyethylene chain formation, followed by attack of this propagating chain on a functional group of the f-PDMS (e.g., a (meth)acrylate ester group), followed by further reaction of the newly formed α-carbonyl radical with ethylene monomer, thus allowing ethylene (either in monomeric or polymeric form) to bond to the (meth)acrylate ester.

[0055] In embodiments, at least one hydrocarbon solvent may be included in the free radical initiator system. The hydrocarbon solvent may be, for example, a C5 to C6 30The solvent may be a hydrocarbon solvent. Exemplary hydrocarbon solvents include, by way of example and not limitation, mineral solvents, normal paraffin solvents, isoparaffin solvents, recycle solvents, and the like. In embodiments, the hydrocarbon solvent is selected from the group consisting of n-octane, isooctane (2,2,4-trimethylpentane), n-dodecane, isododecane (2,2,4,6,6-pentamethylheptane), and other isoparaffinic solvents. Examples of hydrocarbon solvents, such as isoparaffinic solvents, are commercially available from ExxonMobil Chemical Co. under the trademarks ISPAR C, ISOPAR E, and ISOPAR H. In embodiments, the hydrocarbon solvent comprises less than 99% by weight of the free radical initiator system.

[0056] An embodiment includes an alcohol co-solvent (e.g., C1-C 30 The free radical initiator system may further include a polar co-solvent such as an alcohol, an aldehyde, a ketone, or an ester. The alcohol functionality of the alcohol co-solvent may be monofunctional or polyfunctional. Suitable alcohol co-solvents may include, by way of example and not limitation, isopropanol (2-propanol), allyl alcohol, 1-pentanol, methanol, ethanol, propanol, 1-butanol, 1,4-butanediol, combinations thereof, or mixtures thereof. In embodiments, the polar co-solvent may be included in an amount less than 40% by weight of the free radical initiator system.

[0057] Other additives such as processing aids, plasticizers, stabilizers, UV absorbers, antistatic agents, pigments, dyes, nucleating agents, fillers, slip agents, flame retardants, lubricants, smoke suppressants, viscosity modifiers, antiblocking agents, etc. In embodiments, one or more of the additives is included in an amount of less than 50 wt.% of the total weight of the additives, based on the weight of the polymer.

[0058] In embodiments, the process includes a process recycle loop to further improve conversion efficiency. In such embodiments, the downstream reaction region or zone is maintained at a temperature below the temperature at which the ethylene-based polymer phase separates from the polysiloxane. In embodiments, the recycle loop may be treated to neutralize residues or by-products from previous reaction cycles, as such residues or by-products may inhibit polymerization of either the polysiloxane or the ethylene-based polymer.

[0059] Ethylene, f-PDMS, initiator, and CTA are each added to the reactor at one or more locations to achieve the desired ratio of components in the feed to and / or within the reaction zone of the reactor. As will be appreciated by those skilled in the art, the selection of the feed point for each component to the reactor and / or reaction zone depends on several factors, including, but not limited to, the solubility and / or condensation of the components in the pressurized ethylene and / or fouling that may occur in a preheater used to heat the reactor contents prior to initiator injection.

[0060] The ethylene used for the production of LDPE-co-PDMS can be purified ethylene obtained by removing polar components from the loop recycle stream, or a reaction system configuration in which only fresh ethylene is used to make the LDPE-co-PDMS polymer.

[0061] In one embodiment, polymerization is carried out in a continuous stirred tank reactor using propylene as a chain transfer agent. Ethylene and propylene are fed to the top of the reactor via the stirrer shaft. In one embodiment, tert-butyl peroxyacetate (TPA) and tert-butyl peroxyoctoate (TPO) are used as initiators injected into the side of the reactor. In one embodiment, f-PDMS is injected separately into the side of the reactor.

[0062] In further embodiments, the maximum temperature in each reaction zone is from 150°C to 360°C, from 170°C to 350°C, or from 200°C to 325°C. In embodiments, the polymerization pressure at the first inlet of the reactor is from 100 MPa to 360 MPa, further from 150 MPa to 340 MPa, and further from 185 MPa to 320 MPa. After polymerization, the contents of the reactor, including unreacted reactants and LDPE-co-PDMS polymer, are discharged from the reactor outlet.

[0063] The LDPE-co-PDMS polymer can be separated from any remaining reactants according to any method known and used in the art. In embodiments, spraying is used to separate the LDPE-co-PDMS polymer from the remaining reactants, and the LDPE-co-PDMS polymer is collected in powder form.

[0064] While certain LDPE-co-PDMS structures are illustrated in the figures and structures presented herein, it is contemplated that other structures are possible and contemplated. Furthermore, in embodiments, the LDPE-co-PDMS polymer is present in a blend comprising one or more of the structures shown herein. For example, in embodiments, in addition to the attachment of f-PDMS to LDPE by copolymerizing the double bond of the functional group with ethylene, the reaction may also result in a certain amount of a by-product in which LDPE is attached to PDMS through the methyl groups of PDMS via a chain transfer mechanism. Furthermore, it should be understood that LDPE-co-PDMS may constitute only a partial amount of the reaction product, with the majority of the reaction product being LDPE. In embodiments, the LDPE-co-PDMS is present in a blend comprising at least one additional polymer. The additional polymer can be, for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (ULDPE), very low density polyethylene (VLDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), a copolymer comprising a (meth)acrylate ester, a copolymer comprising (meth)acrylic acid, a mono- or diester of maleic acid, a copolymer comprising vinyl acetate, a copolymer comprising trialkoxyvinylsilane, a grafted polyethylene, or a derivative or combination thereof.

[0065] In an embodiment, the LDPE-co-PDMS is 3.0 to 50.0, for example, 3.0 to 45.0, 3.0 to 40.0, 3.0 to 35.0, 3.0 to 30.0, 3.0 to 20.0, 3.0 to 15.0, 3.0 to 10.0, 4.0 to 50.0, for example, 4.0 to 45.0, 4.0 to 40.0, 4.0 to 35.0, 4.0 to 30.0, 4.0 to 20.0, 4.0 to 15.0, 4.0 to 10.0, 5.0 to 50.0, for example, 5.0 to 45.0, 5.0 to 40.0, 5.0 to 3 The LDPE-co-PDMS may have a polydispersity index (PDI) of 5.0, 5.0 to 30.0, 5.0 to 20.0, 5.0 to 15.0, 5.0 to 10.0, 7.0 to 50.0, for example, 7.0 to 45.0, 7.0 to 40.0, 7.0 to 35.0, 7.0 to 30.0, 7.0 to 20.0, 7.0 to 15.0, 7.0 to 10.0, 8.0 to 50.0, for example, 8.0 to 45.0, 8.0 to 40.0, 8.0 to 35.0, 8.0 to 30.0, 8.0 to 20.0, 8.0 to 14.0, or 8.0 to 10.0. In embodiments, the LDPE-co-PDMS may have a PDI of 3.0 to 14.0, 5.0 to 14.0, or 7.0 to 14.0. In embodiments, the LDPE-co-PDMS can have a melt index (I2) of 0.15 to 500.00 g / 10 min, e.g., 0.15 to 100 g / 10 min, 0.15 to 25.00 g / 10 min, 0.15 to 10.00 g / 10 min, 0.3 to 1.7, 0.3 to 2.0, 0.3 to 3.0, 0.3 to 10, 0.5 to 1.7, 0.5 to 2.0, 0.5 to 3.0, 0.5 to 10, 1.0 to 1.7, 1.0 to 2.0, 1.0 to 3.0, 1.0 to 10, 1.3 to 1.7, 1.3 to 2.0, 1.3 to 3.0, 1.3 to 10, 0.50 to 10.00 g / 10 min, or 0.50 to 7.50 g / 10 min. PDI is determined by "conventional GPC" or "3D-GPC".

[0066] Physical Blowing Agent As noted above, in addition to the silicone-functionalized polyethylene, the composition from which the foam is formed includes a physical blowing agent.

[0067] As used herein, the term "physical blowing agent" refers to a compound or composition that (i) is sufficiently soluble in the polymer composition at those conditions to dissolve in the polymer composition under extrusion conditions, and (ii) comes out of solution under the conditions (temperature, pressure) encountered during the formation of the foam composition as the foamable composition exits the die. The physical blowing agent is added to the polymer composition under extrusion conditions to form the foamable composition. As used herein, the term "foamable composition" refers to a mixture of the polymer composition and the physical blowing agent under extrusion conditions.

[0068] In embodiments, the physical blowing agent is added to the polymer composition at a location downstream of the extruder inlet.

[0069] As described herein, extrusion conditions at temperatures between 50°C and 250°C include a pressure sufficiently high to (i) prevent the blowing agent from expanding the polymeric composition and / or foamable composition in the extruder or other suitable melt processing equipment, and (ii) allow for homogeneous dispersion of the blowing agent within the polymeric composition. In embodiments, the extrusion conditions include a temperature between 140°C and 200°C and a pressure between 1.40 and 3.00 MPa, or a temperature between 150°C and 190°C and a pressure between 1.80 and 2.80 MPa, or a temperature between 160°C and 180°C and a pressure between 2.20 and 2.60 MPa.

[0070] Non-limiting examples of suitable physical blowing agents include: 1-6 Hydrocarbons such as acetylene, propane, propene, n-butane, butene, butadiene, isobutane, isobutylene, cyclobutane, cyclopropane, ethane, methane, ethene, isomers of pentane, pentene, cyclopentane, pentadiene, hexane, cyclohexane, hexene, and hexadiene, C 1-5 Organic halogens, C 1-6 Alcohol, C 1-6 Ether, C 1-5 Estelle, C 1-5Examples include amines, alcohols, ammonia, nitrogen, carbon dioxide, water, neon, helium, and combinations thereof. In embodiments, the physical blowing agent is one or more of n-butane, isobutane, n-pentane, isopentane, neopentane, carbon dioxide, ethanol, and 1,1-difluoroethane (HFC-152a).

[0071] The physical blowing agent, (e.g., isobutane), may be present in an amount of 0.5 to 30 wt. %, or 2 to 25 wt. %, or 5 to 20 wt. %, or 8 to 15 wt. %, based on the total weight of the foamable composition, depending on the particular embodiment. In embodiments, LDPE-co-PDMS exhibits improved foaming efficiency, such that the amount of physical blowing agent can be reduced to achieve a given foam density compared to a similar foamable composition that does not include LDPE-co-PDMS (e.g., a composition comprising LDPE and a blowing agent).

[0072] In one embodiment, a chemical blowing agent is used that generates one or more physical blowing agents by thermal decomposition in the process. Chemical blowing agents include (but are not limited to) azodicarbonamide, azodiisobutyronitrile, barium azodicarboxylate, N,N'-dimethyl-N,N'-dinitrosoterephthalamide, benzenesulfonhydrazide, 4,4-oxybenzenesulfonylsemicarbazide, p-toluenesulfonylsemicarbazide, trihydrazinotriazine, and mixtures such as those of citric acid and sodium bicarbonate. Examples of chemical blowing agents are various products sold under the trade name Safoam™ (Reedy International products; Reedy Chemical Foam).

[0073] Permeability Modifier In embodiments, the composition may further comprise a permeability modifier. As used herein, the term "permeability modifier" refers to a compound or composition that reduces the permeability of a blowing agent in a given polyolefin so that the blowing agent permeates a foam made from that polyolefin at approximately the same rate as air diffuses. This allows for dimensionally stable foams to be obtained. Without a permeability modifier, a blowing agent such as isobutane permeates the foam faster than air permeates, which can lead to dimensional instability of the foam, particularly at low foam densities, thereby causing foam shrinkage and deterioration of foam properties.

[0074] Non-limiting examples of permeability modifiers that may be used in various embodiments include C 2 hydroxybenzoates, as described in U.S. Pat. Nos. 3,644,230 and 4,214,054. 10 ~C 24 These include amides and esters of fatty acids, each of which is incorporated herein by reference in its entirety. Esters may also reduce static electricity during and after foam production. In embodiments, permeability modifiers include stearyl stearamide, glycerol monostearate, glycerol monobehenate, and sorbitol monostearate. Combinations of any of these permeability modifiers are possible and contemplated. When used, such permeability modifiers are typically used in amounts ranging from greater than 0 to 10 wt. % based on the total weight of the polymer composition. For example, the permeability modifier may be present in an amount of 0.01, or 0.1, or 0.2, or 0.3, or 0.5, to 1.0, or 2.0, or 5.0 wt. % based on the total weight of the polymer composition. In embodiments, the permeability modifier is present in an amount of 0.01 to 5.0, or 0.1 to 2.0, or 0.2 to 2.0 wt. % based on the total weight of the polymer composition.

[0075] In embodiments, the permeability modifier is a fatty acid ester. The fatty acid ester has an alpha-monoester (or monoglyceride) content in the range of 30-99%, or 40-95%, or 50-90%. In embodiments, the permeability modifier is glycerol monostearate.

[0076] In embodiments, a permeability modifier (e.g., glycerol monostearate) is a component of the masterbatch. In such embodiments, the permeability modifier (e.g., glycerol monostearate) can be present in an amount of from 0.5, or 1, or 1.5, or 2 to 2.5, or 3.5, or 5, or 10, or 20, or 30, or 40, or 50, or up to 60% by weight. For example, the permeability modifier (e.g., glycerol monostearate) can be present in the masterbatch in an amount of 0.5-60% by weight, or 1-50% by weight, or 2-30% by weight, or 5-20% by weight.

[0077] Extrusion Process - Foam In various embodiments, the composition is used to produce an extruded foam. The extruded foam can be produced according to any extrusion foaming process known and used in the art. For example, the LDPE-co-PDMS and permeability modifier (if included) can be simultaneously heated and blended in one or more extruders (e.g., mixing extruders) at temperatures of 140°C to 250°C, 150°C to 230°C, 160°C to 220°C, 170°C to 200°C, or 160°C to 190°C and pressures of 0.1 to 70, 0.5 to 60, 1 to 50, 2 to 40, 3 to 30, 4 to 20, or 6 to 10 megapascals (MPa) to form a flowable polymeric composition. The polymeric composition can also be known as an extrudate.

[0078] In embodiments, one or more additional ingredients, such as a bubble nucleating agent, an olefin polymer, an antistatic agent, a pigment, a filler, or other additives known and used in the art, may be added to the extrudate along with the LDPE-co-PDMS and permeability modifier.

[0079] When added to the extrudate, a bubble nucleating agent can promote the formation of one or more foam cells, resulting in smaller cell size and higher cell density. In embodiments, the bubble nucleating agent can be talc or calcium carbonate or a chemical foaming agent. For example, the bubble nucleating agent can be added to the extrudate as a talc coating on LDPE-co-PDMS pellets. When included, the bubble nucleating agent can be present in an amount of 0.01 to 10.0 wt. %, based on the total weight of the foamable composition.

[0080] An olefin polymer, such as polyethylene or polypropylene, may be included with the LDPE-co-PDMS. For example, in embodiments, the LDPE-co-PDMS may be one polymer in a blend of polymers. In embodiments, the LDPE-co-PDMS and one or more polyethylene polymers (e.g., LDPE) may be blended together and added to an extruder. The olefin polymer may be present in an amount of greater than 0 to 99 wt%, 10 to 98 wt%, 20 to 96 wt%, 30 to 95 wt%, 35 to 94 wt%, or 40 to 93 wt%, based on the total weight of the foamable composition.

[0081] Thus, the LDPE-co-PDMS may be present in an amount of 1 wt% to 99 wt%, 1 wt% to 95 wt%, 1 wt% to 90 wt%, 1 wt% to 80 wt%, 1 wt% to 70 wt%, 1 wt% to 60 wt%, 1 wt% to 50 wt%, 1 wt% to 25 wt%, 1 wt% to 10 wt%, 10 wt% to 99 wt%, 10 wt% to 95 wt%, 10 wt% to 90 wt%, 10 wt% to 80 wt%, 10 wt% to 70 wt%, 10 wt% to 60 wt%, 10 wt% to 50 wt%, 10 wt% to 25 wt%, 20 wt% to 99 wt%, 20 wt% to 95 wt%, 20 wt% to 90 wt%, 20 wt% to 80 wt%, 20 wt% to 70 wt%, based on the total weight of the foamable composition. The foamable composition may contain 20% by weight to 60% by weight, 20% by weight to 50% by weight, 20% by weight to 25% by weight, 30% by weight to 99% by weight, 30% by weight to 95% by weight, 30% by weight to 90% by weight, 30% by weight to 80% by weight, 30% by weight to 70% by weight, 30% by weight to 60% by weight, 30% by weight to 50% by weight, 40% by weight to 99% by weight, 40% by weight to 95% by weight, 40% by weight to 90% by weight, 40% by weight to 80% by weight, 10% by weight to 70% by weight, 40% by weight to 60% by weight, 40% by weight to 50% by weight, 50% by weight to 99% by weight, 50% by weight to 95% by weight, 50% by weight to 90% by weight, 50% by weight to 80% by weight, 50% by weight to 70% by weight, or 50% by weight to 60% by weight.

[0082] In embodiments, one or more antistatic agents, pigments, fillers, or other additives may be included in the composition. Examples of other additives include, but are not limited to, antioxidants, acid scavengers, ultraviolet absorbers, flame retardants, processing aids, extrusion aids, etc. If present, such additives may be present in an amount of from greater than 0 to 20 wt. %, based on the total weight of the foamable composition.

[0083] In embodiments, the physical blowing agent is added to the extruder at a location downstream from the extruder inlet at a temperature and pressure sufficient to prevent the blowing agent from causing expansion of the polymer composition within the extruder or other suitable melt processing equipment and to allow for uniform distribution of the blowing agent within the composition.

[0084] Following addition of the physical blowing agent, the composition comprising LDPE-co-PDMS, the physical blowing agent, and optionally the permeability modifier (herein referred to as the "foamable composition") is cooled to a foaming temperature. For example, the foamable composition can be cooled in a cooling extruder. In embodiments, the foaming temperature is within a range from 10°C below the peak melting temperature of the LDPE-co-PDMS to 10°C above the peak melting temperature of the LDPE-co-PDMS. In embodiments, the foaming temperature is from about 50°C to about 180°C. For example, the foaming temperature may be 70°C to 160°C, 90°C to 140°C, 100°C to 130°C, 100°C to 120°C, 100°C to 110°C, 105°C to 110°C, or 105°C to 118°C.

[0085] Without being bound by theory, in embodiments, it is believed that LDPE-co-PDMS allows for reduced power to the extruder(s) because the foamable compositions exhibit improved processability due to increased lubricity in addition to increased foaming efficiency. Furthermore, due to the likely higher polydispersity index and greater shear thinning of LDPE-co-PDMS, it is believed that the foamable compositions exhibit less shear heating, which may result in improved cooling in large-scale lines.

[0086] After cooling to the foaming temperature, in embodiments, the foamable composition is forced through an exit die at the end of the cooled extruder and cured to form a foam composition. Foaming is achieved when the foamable composition passes through the extruder die into a region of lower pressure compared to the pressure inside the extruder, resulting in a pressure drop when the foamable composition exits the extruder exit die. The pressure drop causes the physical blowing agent to expand the foamable composition, thereby resulting in foaming.

[0087] In embodiments, the resulting foam has a modulus of 0.200 g / cm as measured according to ASTM D1622-88 at 25°C. 3 For example, in an embodiment, the foam has a density of 0.015 to 0.200 g / cm 3 , 0.025~0.200g / cm3 , 0.050~0.200g / cm 3 , 0.075~0.200g / cm 3 , 0.090~0.200g / cm 3 , 0.015~0.150g / cm 3 , 0.025~0.150g / cm 3 , 0.050~0.150g / cm 3 , 0.075~0.150g / cm 3 , 0.090~0.150g / cm 3 , 0.015~0.100g / cm 3 , 0.025~0.100g / cm 3 , 0.050~0.100g / cm 3 , 0.075~0.100g / cm 3 or 0.090 to 0.100 g / cm 3 In embodiments, the foam is an open-cell foam, and in other embodiments, the foam is a closed-cell foam. For example, in embodiments, the foam has a density of 0.090 to 0.200 g / cm 3 As another example, in embodiments, the foam may be an open-cell foam having a density of 0.015 to 0.200 g / cm. 3 The foam may be a closed-cell foam having a density of 0.1 to 1.0 mm.

[0088] Purpose Embodiments of the silicone-functionalized polyethylene foams described herein may be in any known physical form, including, but not limited to, extruded sheets, rods, planks, films, etc. Such foams may be used, for example, in cushion packaging, athletic and recreational products, egg cartons, meat trays, building structures, acoustic insulation liners, pipe insulation, gaskets, vibration pads, luggage liners, desk pads, shoe holes, gymnastics mats, greenhouse insulation blankets, case inserts, absorbent foams (e.g., for cleaning, such as for health and hygiene applications), and display foams. Other uses, such as insulation for refrigeration, buoyancy applications, and floral and craft applications, are contemplated and possible.

[0089] Test Method Test methods include:

[0090] Melt Index (I2) Melt index (I2) is measured according to ASTM D-1238 at 2.16 kg at 190° C. Values ​​are reported in g / 10 min (or dg / min), which corresponds to grams dissolved per 10 minutes.

[0091] density The foam density is measured in grams per cubic centimeter (g / cc or g / cm) according to ASTM D1622-88 at 25°C. 3 Polymer densities are reported in grams per cubic centimeter (g / cc or g / cm) measured according to ASTM D792 at 25°C. 3 ) to report.

[0092] Melt Strength Melt strength measurements were performed on a Gottfert Rheotens 71.97 (Gottfert Inc.; Rock Hill, SC) coupled to a Gottfert Rheotester 2000 capillary rheometer. The molten sample (approximately 25-30 grams) was fed into the Gottfert Rheotester 2000 capillary rheometer with a length of 30 mm, a diameter of 2.0 mm, and a flat entrance angle (180 degrees) with an aspect ratio (length / diameter) of 15. After equilibrating the sample at 190°C for 10 minutes, the piston was run at a constant piston speed of 0.265 mm / s. The standard test temperature was 190°C. The sample was run at a constant piston speed of 2.4 mm / s against a set of accelerating nips located 100 mm below the die. 2 The strands were uniaxially stretched at an acceleration of 0.265 mm / s. The tensile force was recorded as a function of the take-up speed of the nip rolls. Melt strength was reported as the plateau force (cN) before strand breakage. The following conditions were used in the melt strength measurements: plunger speed = 0.265 mm / s, wheel acceleration = 2.4 mm / s. 2 , capillary diameter = 2.0 mm, capillary length = 30 mm, and barrel diameter = 12 mm.

[0093] DSC crystallinity Differential scanning calorimetry (DSC) can be used to measure the crystallinity of a sample at a given temperature over a wide temperature range. In the examples, tests were performed using a TA Model Q1000 DSC (TA Instruments, New Castle, DE) equipped with an RCS (refrigerated cooling system) cooling accessory and an autosampler module. A nitrogen purge gas flow of 50 mL / min was used during testing. The resin was compression molded into 3 mm thick, 1 inch circular plaques at 350 °C under 1500 psi pressure in air for 5 minutes. The samples were then removed from the press, placed on a counter, and allowed to cool to room temperature (approximately 25 °C). A 3-10 mg sample of the cooled material was cut into a 6 mm diameter disk, weighed, placed in a lightweight aluminum pan, and crimped shut. The thermal behavior of the samples was then tested.

[0094] The thermal behavior of the sample was determined by raising and lowering the sample's temperature and creating a response versus temperature profile. To remove any previous thermal history, the sample was first rapidly heated to 180°C and held isothermal for 3 minutes. The sample was then cooled to -40°C at a cooling rate of 10°C / min and held at -40°C for 3 minutes. The sample was then heated to 150°C at a heating rate of 10°C / min. The cooling curve and the second heating curve were recorded. The measured values ​​were the peak melting temperature (T m ), peak crystallization temperature (T c ), heat of fusion (H f ) (J / g), and the calculated % crystallinity of the polyethylene sample using Equation 1:

[0095]

number

[0096] Heat of fusion (H f ) and peak melting temperature are reported from the second heat curve. The peak crystallization temperature was measured from the cooling curve.

[0097] Gel Permeation Chromatography (GPC) The GPC system consisted of a PolymerChar GPC-IR (Valencia, Spain) high-temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) and a 4-capillary solution viscometer (DV) coupled to a Precision Detectors (now Agilent Technologies, Amherst, MA) two-angle laser light scattering (LS) detector model 2040. GPC with the last two independent detectors and at least one first detector is sometimes referred to as "3D-GPC," although the term "GPC" alone generally refers to conventional GPC. For all absolute light scattering measurements, a 15° angle was used. The autosampler oven compartment was operated at 160 °C, and the column compartment was operated at 150 °C. The columns used were four Agilent "Mixed A" 30 cm, 20 micrometer linear mixed-bed columns. The chromatographic solvent used was 1,2,4-trichlorobenzene containing 200 ppm butylated hydroxytoluene (BHT). The solvent source was sparged with nitrogen. The polyethylene sample was gently stirred at 160 °C for 4 h. The injection volume was 200 μL. The flow rate through the GPC was set at 1 mL / min.

[0098] Prior to performing the examples, the GPC column set was calibrated by running at least 20 narrow molecular weight distribution polystyrene standards. The molecular weights (MW) of the standards ranged from 580 to 8,400,000 grams per mole. The standards contained six "cocktail" mixtures. Each standard mixture had at least one decade of separation between the individual molecular weights. The standard mixtures were purchased from Agilent Technologies. The polystyrene standards were prepared at 0.025 g in 50 mL of solvent for molecular weights equal to or greater than 1,000,000 g / mol and 0.05 g in 50 mL of solvent for molecular weights less than 1,000,000 g / mol. The polystyrene standards were dissolved at 80°C for 30 minutes with gentle stirring. The narrow standard mixtures were run first and in order of decreasing highest molecular weight component to minimize degradation. Polystyrene standard peak molecular weights were converted to polyethylene molecular weights using Equation 2 (as described in Williams and Ward, J. Polym. Sci., Polym. Letters, 6, 621 (1968)): M ポリエチレン =A×(M ポリスチレン ) B (Formula 2) where M is the molecular weight of polyethylene (as marked), A has a value of 0.43 and B is equal to 1.0.

[0099] A polynomial between third and fifth order was used to fit each polyethylene-equivalent calibration point. Total plate counts of the GPC column set were performed using Eicosane (prepared at 0.04 g in 50 mL of TCB and dissolved for 20 minutes with gentle agitation). Plate counts (Equation 3) and symmetry (Equation 4) were measured with a 200 μL injection according to the following equations:

[0100]

number

[0101]

number

[0102] Samples were prepared in a semi-automated fashion using PolymerChar "Instrument Control" software, with a target sample weight of 2 mg / mL, and solvent (containing 200 ppm BHT) added via a PolymerChar high-temperature autosampler to a pre-nitrogen-sparged septa-capped vial. Samples were dissolved at 160°C for 2 hours with "slow" shaking.

[0103] Mn (GPC) , Mw (GPC) , and Mz (GPC) was calculated based on GPC results using PolymerChar's GPCOne™ software and the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR chromatograph according to Equations 5-7, using the baseline-subtracted IR chromatogram at each equally spaced data collection point (i) and the polyethylene equivalent molecular weight obtained from the narrow standard calibration curve at point (i) from Equation 2.

[0104]

number

[0105] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by the PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate (Flow Rate (Nominal)) for each sample by matching the RV of the respective decane peak in the sample (RV (FM Sample)) to the RV of the decane peak in the narrow standard calibration (RV (FM Calibrated)). Any change in time of the decane marker peak was then assumed to be related to a linear shift in flow rate (Flow Rate (Effective)) throughout the experiment. To facilitate the highest accuracy in the RV measurement of the flow rate marker peaks, a least-squares fitting routine was used to fit the peaks in the flow rate marker concentration chromatogram to a quadratic equation. The first derivative of the quadratic equation was then used to solve for the true peak position. After calibrating the system based on the flow rate marker peaks, the effective flow rate (with respect to the narrow standard calibration) was calculated as shown in Equation 8. Processing of the flow rate marker peaks was performed via PolymerChar's GPCOne™ software. Acceptable flow correction is one where the effective flow rate is within + / - 2% of the nominal flow rate.

[0106]

number

[0107] Triple Detector GPC (3D-GPC) The chromatographic system, analytical conditions, column set, column calibration and calculation and distribution of conventional molecular weight moments were performed according to the methods described in Gel Permeation Chromatography (GPC).

[0108] For the determination of viscometer and light scattering detector offsets from the IR5 detector, a systematic procedure for the determination of multiple detector offsets was performed in a manner consistent with that published by Balke, Mourey et al. (Mourey and Balke, Chromatography Polym., Chapter 12, (1992)) (Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym., Chapter 13, (1992)) using PolymerChart GPCOne™ software to measure triple detector logs (Mw / Mn) from broad homopolymer polyethylene standards (Mw / Mn>3). w and intrinsic viscosity) results were optimized against narrow standard column calibration results from a narrow standard calibration curve.

[0109] Absolute molecular weight data were obtained using PolymerChar GPCOne™ software in a manner consistent with that published by Zimm (Zimm, BH, J. Chem. Phys., 16, 1099 (1948)) and Kratochvil (Kratochvil, P., Classical Light Scattering from Polymer Solutions, Elsevier, Oxford, NY (1987)). The total injected concentration used in determining the molecular weight was obtained from the mass detector area and mass detector constant derived from a suitable linear polyethylene homopolymer or one of the polyethylene standards of known weight average molecular weight. The calculated molecular weight (using GPCOne™) is obtained using the light scattering constant derived from one or more of the stated polyethylene standards and a refractive index concentration coefficient (dn / dc) of 0.104. Generally, the mass detector response (IR5) and light scattering constant (measured using GPCOne™) should be determined from linear standards with molecular weights above approximately 50,000 g / mol. Viscometer calibration (determined using GPCOne™) can be achieved using the method described by the manufacturer, or alternatively, by using published values ​​of suitable linear standards, such as Standard Reference Material (SRM) 1475a (available from the National Institute of Standards and Technology (NIST)). A viscometer constant (obtained using GPCOne™) is calculated, relating the specific viscosity area (DV) and injected mass for the calibration standard to its intrinsic viscosity. The chromatographic concentration is assumed to be sufficiently low to eliminate consideration of second viral coefficient effects (concentration effects on molecular weight).

[0110] Absolute weight average molecular weight (Mw (Abs)) is obtained by dividing (using GPCOne™) the Light Scattering (LS) area integrated chromatogram (factored by the light scattering constant) by the mass recovered from the mass constant and the mass detector (IR5) area. The molecular weight and intrinsic viscosity responses are linearly extrapolated (using GPCOne™) at the chromatographic end where the signal-to-noise is low. Each of the other moments Mn (Abs) and Mz (Abs) is calculated according to the following equations 9 and 10.

[0111]

number

[0112] High temperature liquid chromatography (HTLC) High-temperature liquid chromatography (HTLC) was used for the separation and characterization of Si-PE hybrids. Free PDMS was quantified by external standard calibration. Sample solutions were prepared at approximately 2.0 mg / mL in anhydrous decane. The samples were dissolved at 130 °C for approximately 1 h using a laboratory shaker. The sample solutions were then transferred to a PolymerChar autosampler. The sample solutions were reheated and shaken at 130 °C in the PolymerChar autosampler for 1 h before injection. HTLC was based on a PolymerChar high-temperature 2DLC / GPC instrument. The LC pump was an Agilent 1260 HPLC system set at a flow rate of 1.0 mL / min. The injection loop contained 20 μL of solution. A Thermo-Fisher hypercarb column (4.6 mm id x 100 mm, 5 μm particle size and 260 Å pore size) maintained at 130 °C was used for the separation. The detector was an Agilent HT-ELSD detector (model G7826A) with a nebulizer temperature set at 160°C. The vaporizer temperature was 120°C and the N2 flow rate was 0.2 SLM. A gradient of decane vs. ODCB was applied for the separation. Data were collected using PolymerChar software version 1.1 and processed using Agilent SEC software Cirrus 3.3.

[0113] [Table 1]

[0114] nuclear magnetic resonance (NMR) Samples were prepared in Norell 1001-7, 10 mm NMR tubes by adding approximately 0.1–0.2 g of sample to 3.25 g of 50 / 50 weight ratio tetrachloroethane-d2 / perchloroethylene with 0.001 M Cr(AcAc)3. To prevent oxidation, the sample was purged by bubbling N2 through the solvent through a pipette inserted into the tube for approximately 5 minutes, capped, and sealed with Teflon tape. The sample was heated to 115–135 °C and vortexed to ensure homogeneity. Analysis was performed on a Bruker AVANCE 600 MHz spectrometer equipped with a Bruker 10 mm CryoProbe at a sample temperature of 120 °C. 1 H NMR was performed. The spectrum was acquired with a ZG pulse, 16 scans, AQ 1.8 seconds, and D 114 seconds. The polymer integral, approximately 0.6 to 2.6 ppm, was arbitrarily set. Dividing this value by 2 gives the total moles of polymer CH2. Multiplying the total moles of CH2 by 14 g / mol gives the polymer weight. Dividing the PDMS integral, approximately -0.3 to 0.6 ppm, by 6 gives the moles of PDMS. Multiplying by 74.1 g / mol of PDMS gives the PDMS weight. The two weights are used to calculate the PDMS weight percent. [Example]

[0115] The following examples illustrate features of the present disclosure but are not intended to limit the scope of the disclosure.

[0116] Example 1 f-PDMS was formed as a 1:2:1 mixture of the following three siloxanes:

[0117] [ka]

[0118] Polymerization was carried out in a 300 mL continuously stirred tank reactor (CSTR) heated to 220 °C using four electric heater bands. The agitator speed was 1800 revolutions per minute (RPM). The reactor pressure was controlled at approximately 193 MPa. Propylene was used as a chain transfer agent. Ethylene and propylene were fed to the top of the reactor along the agitator shaft at a flow rate of 5440 to 5470 g / h ethylene, in the ratios reported in Table 1 below. TPA and TPO were used as initiators in a mass ratio of 0.61:1. The initiators were diluted with ISOPAR E (available from ExxonMobil Chemical Co.) and injected into the side of the reactor at a pressure of 193 MPa in a ratio of 30 to 33 ppm by weight of TPA and 50 to 54 ppm by weight of TPO relative to ethylene. The f-PDMS was diluted to 30 wt % in ethyl acetate (available from Sigma Aldrich) and injected separately into the side of the reactor at the flow rates reported in Table 1 below.

[0119] The residence time in the reactor was approximately 1.5 minutes. All unreacted reactants and polymer were discharged through a single outlet located at the bottom of the reactor. The LDPE-co-PDMS polymer was then separated from the remaining reactants by atomization, and the stream was depressurized to approximately 0.1 MPa while simultaneously cooling the stream to ambient temperature. The LDPE-co-PDMS polymer was then collected in powder form.

[0120] The process conditions under which the LDPE-co-PDMS polymer was prepared are reported in Table 2.

[0121] [Table 2]

[0122] High-temperature liquid chromatography (HTLC) was used for the separation and characterization of the Si-PE hybrids. Free PDMS was quantified by an external standard calibration method.

[0123] DSC analysis of the LDPE-co-PDMS showed a peak melting temperature of 107.7°C and a heat of fusion of 136.1 J / g.

[0124] The samples were further analyzed using conventional GPC and 3D-GPC. Table 3 reports the molecular weight characteristics of the samples.

[0125] [Table 3]

[0126] For comparison, DOW™ LDPE 450E, available from The Dow Chemical Company (Midland, MI), was analyzed using DSC, conventional GPC, and 3D-GPC. It exhibited a peak melting temperature of 110.8°C and a heat of fusion of 157.5 J / g. Table 4 reports the molecular weight properties of DOW™ LDPE 450E.

[0127] [Table 4]

[0128] Thus, as can be seen from the data presented above, LDPE-co-PDMS has a lower peak melting temperature and heat of fusion, and (in this particular case) an increased PDI.

[0129] The melt strength of both LDPE-co-PDMS and DOW™ LDPE 450E was also analyzed. LDPE-co-PDMS exhibited a melt strength of approximately 8-9 cN at 190°C, which is similar to the melt strength of LDPE 450E.

[0130] The amounts of both bound and unbound PDMS are 1 The amount of unbound f-PDMS was estimated by H NMR, which indicated 7.77 wt% PDMS in the LDPE-co-PDMS. The amount of unbound f-PDMS was estimated using HTLC analysis. The average value from two replicates was 3.0 wt% of unbound PDMS in the LDPE-co-PDMS.

[0131] LDPE-co-PDMS exhibits a melt index of approximately 3.5 dg / min. DOW™ LDPE 450E has a melt index of 2.0 dg / min. The density of DOW™ LDPE 450E was 0.923 g / cc, and the density of LDPE-co-PDMS was 0.9256 g / cc.

[0132] Example 2 Foams were then prepared using LDPE-co-PDMS and / or DOW™ LDPE 450E. The foam compositions were prepared in a tandem extrusion system having a mixing extruder and a cooling extruder fed by the mixing extruder. The mixing extruder was a co-rotating twin-screw extruder with a 34 mm diameter screw specially configured to ensure good mixing of the polymer composition and the blowing agent while forming the foamable composition. The mixing extruder was operated at a screw speed of 55 rpm and a set temperature across all zones of 180°C.

[0133] The cooling extruder was a single screw extruder equipped with a 40 mm diameter screw. The barrel and die temperatures of the cooling extruder were controlled among four zones using separate oil heaters. Zones 1 and 2 were operated at set temperatures of 129°C and 116°C, respectively. The set temperature of Zone 3 was the foaming temperature of the foamable composition. The cooling extruder was operated at a screw speed of 22 rpm. A 3 mm diameter rod die was attached to the end of the cooling extruder. The die temperature was maintained at 125°C.

[0134] The components of the polymer composition were dry blended and then fed into the inlet of the mixing extruder through a solid metering feeder. Once complete melting of the polymer components was achieved, the blowing agent (isobutane) was injected into the mixing extruder at 20 L / D using a positive displacement pump (dual piston HPLC pump). The polymer flow rate was maintained at 36 grams per minute (g / min). The residence time of the process from the addition of the solid components to the extruder inlet to the exit die was 12 minutes.

[0135] Foams of different compositions and densities were produced under various processing conditions, as shown in Table 5. In particular, foams in Examples 1 to 4 contained LDPE-co-PDMS, and CS1 was prepared using only LDPE.

[0136] HS-E01 is a masterbatch of the permeability modifier glycerol monostearate (GMS) in an LDPE carrier resin. It is available from Polyvel Inc. and has the following properties: 50% GMS content, 90% alpha mono content, white color, melt index 320 g / 10 min, and softening point 70°C.

[0137] Mistron Vapor R is a talc with a median particle size of 2.2 μm and is available from Imerys Talc.

[0138] [Table 5] * Example 3 was a visual observation during the transition from Example 2 to Example 4.

[0139] In each of CS1 and Examples 1-4, GMS was present in the polymer composition in an amount of 1 wt % and isobutane was present in the foamable composition in an amount of 9 wt %.

[0140] As reported in Table 5, the foams of Examples 1, 2, and 3 had closed-cell structures, while the foam of Example 4 was predominantly open-cell. Typically, such an open-cell structure cannot be achieved with LDPE, even over a wide range of foaming temperatures. Furthermore, the compositions of Examples 1-4 tended to exhibit lower extruder amplitudes than that of CS1, likely due in part to the presence of silicone in the LDPE-co-PDMS.

[0141] Furthermore, the closed-cell foams of Examples 1-3 were significantly lower in density than the foam of CS1 using a fixed amount of isobutane blowing agent. Example 3 relates to visual observations made during the transition from Example 2 to Example 4. When observed, the foam extrudate significantly increased in diameter, indicating a lower foam density, with approximately half of the change. The increased foaming efficiency observed in the Examples containing LDPE-co-PDMS is a beneficial attribute for enabling downgauging and reducing the amount of blowing agent required for a given foam density. Without being bound by theory, increased foaming efficiency may also suggest decreased blowing agent permeability and / or increased blowing agent solubility, which may be beneficial when using fast-permeating blowing agents such as carbon dioxide.

[0142] In addition, due to the silicone present in the LDPE-co-PDMS, the polydispersity index (PDI; reported in Tables 1 and 2) is relatively large, and the shear thinning properties of the LDPE-co-PDMS used in Examples 1-4 are high, which is expected to result in low shear heating and good cooling in large-scale (e.g., commercial) extrusion foaming lines.

[0143] It will be apparent that modifications and variations are possible without departing from the scope of the present disclosure, as defined in the appended claims. More specifically, while certain aspects of the present disclosure have been identified herein as preferred or particularly advantageous, it is not intended that the present disclosure be necessarily limited to these aspects. The present application also relates to the following aspects: (1) 1. An extruded foam formed from a composition, the composition comprising: 1 to 99 weight percent of a silicone-functionalized polyethylene comprising the reaction product of the polymerization of ethylene and a (meth)acrylate-functionalized polydimethylsiloxane; a physical blowing agent; and the foam has a viscosity of 0.200 g / cm as measured in accordance with ASTM D1622-88 at 25°C. 3 An extruded foam having a density of: (2) The extruded foam according to (1) above, wherein the silicone-functionalized polyethylene has a polydispersity index (PDI) of 3 to 14. (3) The silicone-functionalized polyethylene has the following structure:

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Claims

1. An extruded foam formed from a foamable composition, comprising: The foamable composition comprises: 1 to 99 wt %, based on the total weight of the foamable composition, of a silicone-functionalized polyethylene comprising the reaction product of the polymerization of ethylene and a (meth)acrylate-functionalized polydimethylsiloxane; a physical blowing agent; and the extruded foam has a modulus of elasticity of 0.200 g / cm3 as measured in accordance with ASTM D1622-88 at 25°C. ３ An extruded foam having a density of:

2. 10. The extruded foam of claim 1, wherein the silicone-functionalized polyethylene has a polydispersity index (PDI) of 3-14.

3. The silicone-functionalized polyethylene has the following structure: 【Chemistry 1】 wherein R １ is a bridging group linking the functional group ((meth)acrylate) with the siloxane, and R ２ is an end group selected from the group consisting of alkyl, substituted alkyl, aryl, alkenyl, H, and OH; x is an integer from 10 to 1000; and y is an integer from 1 to 20.

4. The extruded foam of any one of claims 1 to 3, wherein the foamable composition further comprises from greater than 0 to 96 wt% of an olefin polymer, based on the total weight of the foamable composition.

5. 5. The extruded foam of claim 4, wherein the olefin polymer comprises LDPE.

6. 6. The extruded foam of any one of claims 1 to 5, wherein the composition further comprises from greater than 0 to 2 wt% of a permeability modifier.

7. The permeability modifier is C １０ ~C ２４ 7. The extruded foam of claim 6, comprising an amide or ester of a fatty acid.

8. The extruded foam of any one of claims 1 to 7, wherein the physical blowing agent comprises isobutane, carbon dioxide, n-butane, an isomer of pentane, a hydrocarbon, or a mixture thereof.

9. An extruded foam described in any one of claims 1 to 8, wherein the physical blowing agent present in the foamable composition is in an amount of 5 to 20 weight percent based on the total weight of the foamable composition.

10. The extruded foam of any one of claims 1 to 9, wherein the foam is open-celled.

11. The foam has a viscosity of 0.090 to 0.200 g / cm ３ 11. The extruded foam of claim 10 having a density of

12. The extruded foam of any one of claims 1 to 9, wherein the foam is closed-cell.

13. The foam has a viscosity of 0.015 to 0.200 g / cm ３ 13. The extruded foam of claim 12 having a density of

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