WO2017189095A1

WO2017189095A1 - Propylene-based cushioning network structures, and methods of manufacturing thereof

Info

Publication number: WO2017189095A1
Application number: PCT/US2017/021048
Authority: WO
Inventors: Viraj SHAH; Rajen M. Patel; Selim Bensason; Jacquelyn A. Degroot; Ronald Wevers
Original assignee: Dow Global Technologies Llc
Priority date: 2016-04-29
Filing date: 2017-03-07
Publication date: 2017-11-02
Also published as: AR108221A1

Abstract

A cushioning network structure, or a method of manufacturing a cushioning network structure, comprising a plurality of random loops arranged in a three-dimensional orientation, wherein the plurality of random loops are formed from a propylene interpolymer comprising at least 60 wt.% units derived from propylene and between 1 and 40 wt.% units derived from ethylene, wherein the propylene interpolymer has a density of from 0.840 g/cm³ to 0.900 g/cm³, a highest DSC melting peak temperature of from 50.0°C to 120.0°C, a melt flow rate of from 1 to 100 g/10 min, and a molecular weight distribution of less than 4.

Description

PROPYLENE-BASED CUSHIONING NETWORK STRUCTURES, AND METHODS OF MANUFACTURING THEREOF

TECHNICAL FIELD

[0001] Embodiments of the present disclosure generally relate to cushioning network structures having a plurality of random loops arranged in a three-dimensional orientation, and specifically relate to cushioning network structures wherein the plurality of random loops comprise a propylene interpolymer.

BACKGROUND

[0002] Polyurethane foam is often used as a cushioning material for various articles, such as, for example, bed mattresses, seat cushions, back rest cushions, pillows, upholstered furniture, or any other article where support and/or cushioning is desired. The cushioning materials may be used to bear and distribute the weight of a user, thereby providing the desired support and comfort while balancing durability for a given application. Despite the durability and cushioning function that polyurethane foam has been known to offer, it can suffer from certain drawbacks. For instance, polyurethane foam can retain water and moisture leaving the foam susceptible to breeding bacteria. It may also absorb heat and lack suitable breathability, thus making the upper surface of the polyurethane foam warm. During the hotter months, the warm upper surface of the polyurethane foam can become uncomfortable to a user. Further, polyurethane foam may not be easy to reuse or recycle. Discarded polyurethane foam is generally incinerated or buried, which are undesirable options from an environmental and cost standpoint.

[0003] Accordingly, alternative cushioning network structures that provide suitable durability and cushioning function, while also providing breathability and recyclability, may be desirable.

SUMMARY

[0004] Disclosed in embodiments herein are cushioning network structures. The cushioning network structures comprise a plurality of random loops arranged in a three- dimensional orientation, wherein the plurality of random loops are formed from a propylene interpolymer. The propylene interpolymer comprises at least 60 wt.% units derived from propylene and between 1 and 40 wt.% units derived from ethylene, wherein the propylene interpolymer has a density of from 0.840 g/cm³ to 0.900 g/cm³, a highest DSC melting peak temperature of from 50.0°C to 120.0°C, a melt flow rate of from 1 to 100 g/10 min, and a molecular weight distribution of less than 4.

[0005] Also disclosed herein are methods of manufacturing a cushioning network structure comprising a plurality of random loops arranged in a three-dimensional orientation. The methods comprise providing a propylene interpolymer comprising at least 60 wt.% units derived from propylene and between 1 and 40 wt.% units derived from ethylene, wherein the propylene interpolymer has a density of from 0.840 g/cm³ to 0.900 g/cm³, a highest DSC melting peak temperature of from 50.0°C to 120.0°C, a melt flow rate of from 1 to 100 g/10 min, and a molecular weight distribution of less than 4; forming the propylene interpolymer into a plurality of random loops having a three-dimensional orientation to form a cushioning network structure.

[0006] Additional features and advantages of the embodiments will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0007] It is to be understood that both the foregoing and the following description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 schematically depicts fiber formation of an exemplary propylene interpolymer according to one or more embodiments herein in a water cooling unit disposed downstream of an extruder.

[0009] FIG. 2 schematically depicts bonding of the fibers formed in the water cooling unit. DETAILED DESCRIPTION

[0010] Reference will now be made in detail to embodiments of cushioning network structures, and methods of manufacturing cushioning network structures, characteristics of which are illustrated in the accompanying drawings. The cushioning network structures may be used in mattresses, cushions, pillows, upholstered furniture, or any other article where support and/or cushioning is desired. It is noted, however, that this is merely an illustrative implementation of the embodiments disclosed herein. The embodiments may be applicable to other technologies that are susceptible to similar problems as those discussed above. For example, the cushioning network structures described herein may be used in cushioned mats, cushioned floor pads, footwear inserts, etc., all of which are within the purview of the present embodiments.

Cushioning Network Structures

[0011] The cushioning network structures comprise a plurality of random loops arranged in a three-dimensional orientation. The plurality of random loops is formed from a propylene interpolymer. As used herein, "polymer" means a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term "polymer" embraces the terms "homopolymer," "copolymer," "terpolymer" as well as "interpolymer." "Interpolymer" refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term "interpolymer" includes the term "copolymer" (which is usually employed to refer to a polymer prepared from two different monomers) as well as the term "terpolymer" (which is usually employed to refer to a polymer prepared from three different types of monomers). It also encompasses polymers made by polymerizing four or more types of monomers.

[0012] Propylene interpolymer generally refers to polymers comprising propylene and an a-olefin having 2 carbon atoms or 4 or more carbon atoms. In embodiments herein, the propylene interpolymer comprises at least 60 wt.% of the units derived from propylene and between 1 and 40 wt.% of the units derived from ethylene (based on the total amount of polymerizable monomers). All individual values and subranges of at least 60 wt.% of the units derived from propylene between 1 and 40 wt.% of the units derived from ethylene are included and disclosed herein. For example, in some embodiments, the propylene interpolymer comprises (a) at least 65 wt.%, at least 70 wt.%, at least 75 wt.%, at least 80 wt.% , at least 82 wt.% , at least 85 wt.% , at least 87 wt.% , at least 90 wt.% , at least 92 wt.% , at least 95 wt.% , at least 97 wt.% , from 60 to 99 wt.%, from 60 to 99 wt.%, from 65 to 99 wt.%, from 70 to 99 wt.%, from 75 to 99 wt.%, from 80 to 99 wt.%, from 82 to 99 wt.%, from 84 to 99 wt.%, from 85 to 99 wt.%, from 88 to 99 wt.%, from 80 to 97 wt.%, from 82 to 97 wt.%, from 85 to 97 wt.%, from 88 to 97 wt.%, from 80 to 95.5 wt.%, from 82 to 95.5 wt.%, from 84 to 95.5 wt.%, 85 to 95.5 wt.%, or from 88 to 95.5 wt.%, of the units derived from propylene; and (b) between 1 and 40 wt.%, for example, from 1 to 35%, from 1 and 30%, from 1 and 25%, from 1 to 20 %, from 1 to 18%, from 1 to 16 %, 1 to 15%, 1 to 12%, 3 to 20%, 3 to 18%, 3 to 16%, 3 to 15%, 3 to 12%, 4.5 to 20%, 4.5 to 18%, 4.5 to 16%, 4.5 to 15%, or 4.5 to 12%, by weight, of units derived from ethylene. The comonomer content may be measured using any suitable technique, such as techniques based on nuclear magnetic resonance ("NMR") spectroscopy, and, for example, by 13C NMR analysis as described in U.S. Patent 7,498,282, which is incorporated herein by reference.

[0013] The propylene interpolymers can be made by any process, and include random, block and graft copolymers. In some embodiments, the propylene interpolymers are of a random configuration. These include interpolymers made by Ziegler-Natta, CGC (Constrained Geometry Catalyst), metallocene, and non-metallocene, metal-centered, heteroaryl ligand catalysis. Additional suitable metal complexes include compounds corresponding to the formula:

, where:

20

R is an aromatic or inertly substituted aromatic group containing from 5 to 20 atoms not counting hydrogen, or a polyvalent derivative thereof;

T³ is a hydrocarbylene or silane group having from 1 to 20 atoms not counting hydrogen, or an inertly substituted derivative thereof;

M³ is a Group 4 metal, preferably zirconium or hafnium;

G is an anionic, neutral or dianionic ligand group; preferably a halide, hydrocarbyl or dihydrocarbylamide group having up to 20 atoms not counting hydrogen; g is a number from 1 to 5 indicating the number of such G groups; and covalent bonds and electron donative interactions are represented by lines and respectively.

[0014] In some embodiments, such complexes correspond to the formula:

wherein:

T³ is a divalent bridging group of from 2 to 20 atoms not counting hydrogen, preferably a substituted or unsubstituted, C3-6 alkylene group; and

Ar² independently each occurrence is an arylene or an alkyl- or aryl-substituted arylene group of from 6 to 20 atoms not counting hydrogen;

M³ is a Group 4 metal, preferably hafnium or zirconium;

G independently each occurrence is an anionic, neutral or dianionic ligand group; g is a number from 1 to 5 indicating the number of such X groups; and electron donative interactions are represented by arrows.

[0015] Exam les of metal complexes of the foregoing formula include the following

compounds: where M³ is Hf or Zr;

Ar⁴ is C₆-2o aryl or inertly substituted derivatives thereof, especially 3,5- di(isopropyl)phenyl, carbazole, 3,5-di(isobutyl)phenyl, dibenzo-lH-pyrrole-l-yl, or anthracen-5-yl, and

T⁴ independently each occurrence comprises a C₃-6 alkylene group, a C₃-6 cycloalkylene group, or an inertly substituted derivative thereof;

R²¹ independently each occurrence is hydrogen, halo, hydrocarbyl, trihydrocarbylsilyl, or trihydrocarbylsilylhydrocarbyl of up to 50 atoms not counting hydrogen; and

G, independently each occurrence is halo or a hydrocarbyl or trihydrocarbylsilyl group of up to 20 atoms not counting hydrogen, or 2 G groups together are a divalent derivative of the foregoing hydrocarbyl or trihydrocarbylsilyl groups.

[0016] Without limiting in any way the scope of the invention, one means for making a propylene interpolymer as described herein is as follows: in a stirred-tank reactor, the monomers to be polymerized are introduced continuously together with any solvent or diluent, and, in some embodiments, the solvent is an alkane hydrocarbon solvent, such as, ISOPAR™ E. The reactor contains a liquid phase composed substantially of monomers together with any solvent or diluent and dissolved polymer. Catalyst along with cocatalyst and, optionally, chain transfer agent, are continuously or intermittently introduced in the reactor liquid phase or any recycled portion thereof. The reactor temperature may be controlled by adjusting the solvent/monomer ratio, the catalyst addition rate, as well as by use of cooling or heating coils, jackets or both. The polymerization rate is controlled by the rate of catalyst addition. Pressure is controlled by the monomer flow rate and partial pressures of volatile components. The propylene content of the polymer product is determined by the ratio of propylene to comonomer in the reactor, which is controlled by manipulating the respective feed rates of these components to the reactor. The polymer product molecular weight is controlled, optionally, by controlling other polymerization variables such as the temperature, monomer concentration, or flow rate of the previously mentioned chain transfer agent. Upon exiting the reactor, the effluent is contacted with a catalyst kill agent such as water, steam, or an alcohol. The polymer solution is optionally heated, and the polymer product is recovered by flashing off gaseous unreacted monomers as well as residual solvent or diluent at reduced pressure, and, if necessary, conducting further devolatilization in equipment, such as, a devolatilizing extruder. In a continuous process, the mean residence time of the catalyst and polymer in the reactor generally is from 5 minutes to 8 hours, and, in some embodiments, is from 10 minutes to 6 hours.

[0017] Without limiting in any way the scope of the invention, another means for making a propylene interpolymer as described herein is as follows: continuous solution polymerizations may be carried out in a computer controlled autoclave reactor equipped with an internal stirrer. Purified mixed alkanes solvent (ISOPAR™ E available from ExxonMobil, Inc.), ethylene, propylene, and hydrogen may be continuously supplied to a 3.8 L reactor equipped with a jacket for temperature control and an internal thermocouple. The solvent feed to the reactor may be measured by a mass-flow controller. A variable speed diaphragm pump controls the solvent flow rate and pressure to the reactor. At the discharge of the pump, a side stream is taken to provide flush flows for the catalyst and cocatalyst injection lines and the reactor agitator. These flows may be measured by mass flow meters and controlled by control valves or by the manual adjustment of needle valves. The remaining solvent is combined with monomers and hydrogen and fed to the reactor. A mass flow controller is used to deliver hydrogen to the reactor as needed. The temperature of the solvent/monomer solution is controlled by use of a heat exchanger before entering the reactor. This stream enters the bottom of the reactor.

[0018] The catalyst and cocatalyst component solutions may be metered using pumps and mass flow meters and are combined with the catalyst flush solvent and introduced into the bottom of the reactor. The catalyst may be a metal complex as described above. In some embodiments, the catalyst may be bis((2-oxoyl-3-(dibenzo-lH-pyrrole-l-yl)-5- (methyl)phenyl)-2-phenoxymethyl)-methylenetrans- 1 ,2-cyclohexanediylhafnium (IV) dimethyl, as outlined above. The cocatalyst may be a long-chain alkyl ammonium borate of approximate stoichiometry equal to methyldi(octadecyl)ammonium tetrakis(pentafluorophenyl)borate (MDB) combined with a tertiary component, tri(isobutyl)aluminum-modified methalumoxane (MMAO) containing a molar ratio of i- butyl/methyl groups of about 1/3. The catalyst/cocatalyst may have a molar ratio based on Hf of 1.0/1 to 1.5/1, and MMAO (ratio of 25/1 - 35/1, Al/Hf). The reactor may be run liquid-full at 500-525 psig (3.45-3.62 MPa) with vigorous stirring. The reactor temperature may range from 125°C to 165°C and the propylene conversion percent may be about 80%. The reactor operates at a polymer concentration of between about 15 to 20 wt.%. The propylene conversion in the reactor may be maintained by controlling the catalyst injection rate. The reaction temperature may be maintained by controlling the water temperature across the shell side of the heat exchanger. The polymer molecular weight may be maintained by controlling the hydrogen flow.

[0019] Product is removed through exit lines at the top of the reactor. All exit lines from the reactor are steam traced and insulated. Polymerization may be stopped by the addition of a small amount of water into the exit line along with any stabilizers or other additives and passing the mixture through a static mixer. The product stream may then be heated by passing through a heat exchanger before devolatilization. The polymer product may be recovered by extrusion using a devolatilizing extruder and water cooled pelletizer.

[0020] Exemplary propylene interpolymers may include Exxon-Mobil Chemical Company VISTAMAXX™ polymers, and VERSIFY™ polymers by The Dow Chemical Company.

[0021] In embodiments herein, the propylene interpolymers have a density of from 0.840 g/cm³ to 0.900 g/cm³, as measured by ASTM D-792. All individual values and subranges of from 0.840 g/cm³ to 0.900 g/cm³ are included and disclosed herein. For example, in some embodiments the propylene interpolymer has a density of from 0.850 g/cm³ to 0.890 g/cm³, from 0.855 g/cm³ to 0.890 g/cm³, or from 0.860 g/cm³ to 0.890 g/cm³.

[0022] In embodiments herein, the propylene interpolymers have a differential scanning calorimetry ("DSC") melting peak temperature of from 50.0°C to 120.0°C. All individual values and subranges of from 50.0°C to 120.0°C are included and disclosed herein. For example, in some embodiments the propylene interpolymer has a highest DSC melting peak temperature of from 50.0°C to 115.0°C, from 50.0°C to 110.0°C, from 50.0°C to 100.0°C, from 50.0°C to 90.0°C, from 50.0°C to 85.0°C, from 70.0°C to 120.0°C, from 70.0°C to 110.0°C, from 70.0°C to 100.0°C.

[0023] In embodiments herein, the propylene interpolymers have a melt flow rate of from 1 to 100 g/10 min, as measured according to ASTM D-1238 (2.16 kg, 230°C). All individual values and subranges of 1 to 100 g/10 min are included and disclosed herein. For example, in some embodiments, the propylene interpolymers have a melt flow rate of from 2 to 50 g/10 min, or from 6 to 30 g/10 min. [0024] In embodiments herein, the propylene interpolymers have a molecular weight distribution of less than 4. Molecular weight distribution is the ratio of the weight average molecular weight to the number average molecular weight (Mw/Mn). The molecular weights may be determined by gel permeation chromatography. All individual values and subranges of less than 4 are included and disclosed herein. For example, in some embodiments, the propylene interpolymers have a molecular weight distribution of from 2 to 4, 2 to 3.7, 2 to 3.5, 2 to 3.2, 2 to 3, or 2 to 2.8.

[0025] In embodiments herein, the propylene interpolymers may have a weight average molecular weight (Mw) of at least 50,000 g/mol. All individual values and subranges of at least 50,000 g/mol are included and disclosed herein. For example, in some embodiments, the propylene interpolymers may have a weight average molecular weight (Mw) of between 50,000 and 1,000,000 g/mol, between 50,000 and 500,000 g/mol, between 50,000 and 400,000 g/mol, between 50,000 and 300,000 g/mol, or between 50,000 and 250,000 g/mol.

[0026] In embodiments herein, the propylene interpolymers may have a DSC crystallization onset temperature, Tc-Onset, of less than 85°C. All individual values and subranges of less than 85 °C are included and disclosed herein. For example, in some embodiments, the propylene interpolymers may have a DSC crystallization onset temperature, Tc-Onset, of from 45 to 85°C, or 50 to 85°C.

[0027] In embodiments herein, the propylene interpolymers may have a temperature differential between the highest DSC melting peak temperature (Tm) and the DSC crystallization peak temperature (Tc), Tm-Tc, of 25°C-50°C. All individual values and subranges of 25°C-50°C are included and disclosed herein. For example, in some embodiments, the propylene interpolymers may have a temperature differential of Tm - Tc of 30°C-50°C, or 35°C-50°C.

[0028] In embodiments herein, the propylene interpolymers may have a percent crystallinity, as determined by DSC, in the range of from 0.5 % to 45%. All individual values and subranges of from 0.5 % to 45% are included and disclosed herein. For example, in some embodiments, the propylene interpolymers may have a percent crystallinity, as determined by DSC, in the range of from 2% - 42%.

[0029] In further embodiments herein, the cushioning network structures comprise a plurality of random loops arranged in a three-dimensional orientation, wherein the plurality of random loops are formed from a propylene interpolymer comprising at least 60 wt.% units derived from propylene and between 1 and 20 wt.% units (or, in the alternative, 3 - 18 wt.% units) derived from ethylene, wherein the propylene interpolymer has a density of from 0.860 g/cm³ to 0.900 g/cm³ (or, in the alternative, 0.855 to 0.890 g/cm³), a highest DSC melting peak temperature of from 50°C to 100.0°C (or, in the alternative, 50°C to 90°C); a melt flow rate of from 2 to 50 g/10 min (or, in the alternative, 6 to 30), and a molecular weight distribution of less than 4.

[0030] The propylene interpolymers herein may further comprise additional components such as one or more other polymers and/or one or more additives. Such additives include, but are not limited to, antistatic agents, color enhancers, dyes, lubricants, fillers such as T1O2 or CaCC^, opacifiers, nucleators, processing aids, pigments, primary antioxidants, secondary antioxidants, processing aids, UV stabilizers, anti-blocks, slip agents, tackifiers, fire retardants, anti-microbial agents, odor reducer agents, anti-fungal agents, and combinations thereof. The propylene interpolymers may contain from about 0.1 to about 10 percent by the combined weight of such additives, based on the weight of the propylene interpolymers including such additives.

[0031] In embodiments herein, the plurality of random loops may be made from a blend of a propylene interpolymer as described herein and at least one other polymer. The at least one other polymer can be a thermoplastic elastomer, a thermoplastic non-elastic polymer or a combination thereof (polymer blend). In certain embodiments, the plurality of random loops are formed from a composite fiber of an propylene interpolymer and a thermoplastic elastomer, a composite fiber of a propylene interpolymer and a thermoplastic non- elastomer, or a composite fiber of a propylene interpolymer, a thermoplastic elastomer, and a thermoplastic non-elastic polymer.

[0032] When present, the amount of the at least one other polymer in the plurality of random loops may be less than about 90%, about 80%, about 70%, about 60%, about 50%, about 40%, about 30%, about 20%, about 10%, or about 5% of the total weight of the polymers present in the blend.

[0033] Examples of polymeric materials that the propylene interpolymers may be blended with can include, for e.g., a polyester elastomer, polyamide elastomer, and polyurethane elastomer, a low density polyethylene (LDPE), or a linear low density polyethylene (LLDPE). Such LDPEs or LLDPEs are commercially available under the tradenames DOWLEX™, DNDA, and ATTANE™, all of which are available from The Dow Chemical Company (Midland, Michigan).

Method of Manufacturing

[0034] The plurality of random loops may be formed by allowing continuous filaments to bend and come in contact with one another in a molten state, thereby being heat-bonded at random contact points. Thus, in some embodiments, the plurality of random loops is at least partially bonded with one another. The cushioning network structures provided herein can be prepared by any method known in the art. Examples of such as methods are described in U.S. Pat. Nos. 5,639,543, 6,378, 150, 7,622, 179, and 7,625,629, which are incorporated herein by reference.

[0035] In embodiments herein, the cushioning network structure comprising a plurality of random loops arranged in a three-dimensional orientation may be manufactured by providing a propylene interpolymer according to one or more embodiments described herein, and forming the propylene interpolymer into a plurality of random loops having a three-dimensional orientation to form a cushioning network structure.

[0036] In some embodiments, the cushioning network structure comprising a plurality of random loops arranged in a three-dimensional orientation may be manufactured by providing a propylene interpolymer comprising at least 60 wt.% units derived from propylene and between 1 and 40 wt.% units derived from ethylene, wherein the propylene interpolymer has a density of from 0.840 g/cm³ to 0.900 g/cm³, a highest DSC melting peak temperature of from 50°C to 120.0°C; a melt flow rate of from 1 to 100 g/10 min, and a molecular weight distribution of less than 4; and forming the propylene interpolymer into a plurality of random loops having a three-dimensional orientation to form a cushioning network structure.

[0037] In other embodiments, the cushioning network structure comprising a plurality of random loops arranged in a three-dimensional orientation may be manufactured by providing a propylene interpolymer comprising at least 60 wt.% units derived from propylene and between 1 and 20 wt.% units (or, in the alternative, 3 - 18 wt.% units) derived from ethylene, wherein the propylene interpolymer has a density of from 0.860 g/cm³ to 0.900 g/cm³ (or, in the alternative, 0.855 to 0.890 g/cm³), a highest DSC melting peak temperature of from 50°C to 100.0°C (or, in the alternative, 50°C to 90°C); a melt flow rate of from 2 to 50 g/10 min (or, in the alternative, 6 to 30), and a molecular weight distribution of less than 4; and forming the propylene interpolymer into a plurality of random loops having a three-dimensional orientation to form a cushioning network structure.

[0038] An exemplary method for manufacturing a cushioning network structure is shown in FIGS. 1 and 2. Referring to FIGS. 1 and 2, molten propylene interpolymer 2 is delivered to a water cooling unit 4. Upon cooling, the molten propylene interpolymer composition 2 forms into three dimensional random loops 3. Thus, the water cooling of the molten propylene interpolymer 2 facilitates formation of three-dimensional random loops 3 which at least partially bond to form the cushioning network structure. Without being bound by theory, it is believed that the propylene interpolymers described herein have a sufficiently low crystallization temperature in order to allow good bonding of the touching filament loops. This can allow for sufficient time prior to solidification in the water bath. The temperature of the water-bath can be used to control the solidification and annealing of the thus formed loop structure. It is believed that compositions with a larger differential between Tm and Tc, Tm-Tc are preferred herein. The solidified material may stay for some time in the water bath to aid secondary crystallization of the polymer for at least 1 minute or more.

[0039] As shown in FIG. 2, the propylene interpolymer 2 is delivered to the water cooling unit 4 via a drive mechanism 7 shown at least partially submerged (of course, it may be fully submerged), in the water cooling unit 4. The drive mechanism 7 may generally comprise at least one belt, a plurality of rollers, at least one conveyor, or combinations thereof. The drive mechanism 7 may be an underwater mechanism which constrains a thickness of the cushioning network structure. Considering the significant number of filaments being delivered to the water cooling unit 4, there may be significant bonding of the filaments during looping thereby creating a network structure. Without being bound by theory, it is believed that the cooling or solidifying of the 3D loop structure increases with the increasing depth into the water cooling unit 4.

[0040] As depicted in FIG. 2, the propylene interpolymer 2 may be in pelletized form and are heated and melted in an extruder 10. The extruder 10 may generally include a hopper, screw and barrel, motor to turn the screw and heaters to heat the barrel. Of course, other configurations for extruder 10 may be used as is known in the art. The propylene interpolymer pellets enter the hopper and are melted in the heated barrel due to heat and shear. As the flight clearance between the screw and barrel reduce going from the hopper to the die end, the solid pellets get softer and melt from the feed zone to the transition zone and finally, at the end near the die, the metering of the melt happens, like a pump, thus generating positive extrusion pressure as the melt exits the die 5.

[0041] The molten propylene interpolymer exiting the die, which is now under positive pressure, may be transferred through a heated transfer pipe into the die 5. The die may consist of several rows of holes in series. The melt, which enters the die from a round transfer pipe, is uniformly distributed so it can exit the die from each of the individual holes uniformly. The die may be in a horizontal arrangement such that the melt exiting the die, which is now in the form of filaments, travels downward vertically before breaking the surface of the water in the water tank. The air gap or the distance between the die surface and the surface of water is adjustable.

[0042] Upon leaving the water cooling unit 4, the three-dimensional random loops 3 should be sufficiently bonded together to form the cushioning network structure. Excess water may be removed by various mechanisms. Moreover, there is a mechanism to cut the continuously forming structure into a desired length. The network structure provided herein can be a laminate or a composite of various network structures made of loops having different sizes, different deniers, different compositions, different densities, and so on as appropriately selected so as to meet the desired property.

[0043] The loop size of the plurality of random loops may vary based on industrial application, and specifically may be dictated by the diameter of the holes in the die. The loop size of the plurality of random loops may also be dictated by the polymer, melt temperature of the filaments coming out of the die, the distance between the die and water, the speed of the belts or rollers or other mechanism under water etc. In some embodiments, the random loop may have a diameter of about 0.1 mm to about 3 mm, or a diameter of about 0.6 mm to about 1.6 mm. The apparent density may range from about 0.016 to about 0.1 g/cm³, or about 0.024 to about 0.1 g/cm³ and can be achieved by adjusting various factors. TEST METHODS

Melt Index/Melt Flow Rate

[0044] Melt index (12), for ethylene-based polymers, is measured in accordance with ASTM D 1238-10, Condition, 190°C/2.16 kg, and is reported in grams eluted per 10 minutes. Melt index (110), for ethylene-based polymers, is measured in accordance with ASTM D 1238-10, Condition 190°C/10 kg, and is reported in grams eluted per 10 minutes. Melt Flow Rate, MFR2, for propylene-based polymers is measured in accordance with ASTM D 1238-10, Condition 230°C/2.16 kg, and is reported in grams eluted per 10 minutes. Melt Flow Rate, MFR10, for propylene-based polymers is measured in accordance with ASTM D 1238-10, Condition 230°C/10 kg, and is reported in grams eluted per 10 minutes.

Density

[0045] Density is measured in accordance with ASTM D792. High Temperature Gel Permeation Chromatography (HT-GPC) Propylene Interpolymers

[0046] The polymers are analyzed by gel permeation chromatography (GPC) on a Polymer Laboratories PL-GPC-220 high temperature chromatographic unit equipped with three linear mixed bed columns, 300 x 7.5 mm (Polymer Laboratories PLgel Mixed B (10- micron particle size)). The oven temperature is at 160°C with the autosampler hot zone at 160°C and the warm zone at 145°C. The solvent is 1 ,2,4-trichlorobenzene containing 200 ppm 2,6-di-t-butyl-4-methylphenol (BHT). The flow rate is 1.0 milliliter/minute and the injection size is 100 microliters. A 0.15% by weight solution of the sample is prepared for injection by dissolving the sample in nitrogen purged 1,2,4-trichlorobenzene containing 200 ppm 2,6-di-t-butyl-4-methylphenol for 2.5 hrs at 160°C with gentle mixing.

[0047] The molecular weight determination is deduced by using ten narrow molecular weight distribution polystyrene standards (from Polymer Laboratories, EasiCal PS1 ranging from 580 - 7,500,000 g/mole) in conjunction with their elution volumes. BHT was used as a relative flowrate marker referencing each chromatographic run back to the polystyrene narrow standards calibration curve. [0048] The equivalent polypropylene molecular weights are determined by using appropriate Mark-Houwink coefficients for polypropylene (as described by Th.G. Scholte, N.L.J. Meijerink, H.M. Schoffeleers, and A.M.G. Brands, J. Appl. Polym. Sci., 29, 3763 - 3782 (1984), incorporated herein by reference) and polystyrene (as described by E. P. Otocka, R. J. Roe, N. Y. Hellman, P. M. Muglia, Macromolecules, 4, 507 (1971) incorporated herein by reference) in the Mark-Houwink equation (EQ 1), which relates intrinsic viscosity to molecular weight. The instantaneous molecular weight (M₍pp₎) at each chromatographic point is determined by EQ 2, using universal calibration and the Mark- Houwink coefficients as defined in EQ 1. The number-average, weight-average, and z- average molecular weight moments, Mn, Mw, and Mz were calculated according to EQ 3, EQ 4, and EQ 5, respectively, wherein RI is the baseline-subtracted refractometer signal height of the polymer elution peak at each chromatographic point (i).

{ η } = KM^a (EQ 1) where K_{pp =} 1.90E-04 , a_{pp =} 0.725 and K_{ps =} 1.26E-04_, a_{ps =} 0.702.

Ethylene-Based Polymers

[0049] A PolymerChar (Valencia, Spain) high temperature Gel Permeation Chromatography system consisting of an infra-red concentration detector (IR-5) was used for MW and MWD determination. The solvent delivery pump, the on-line solvent degas device, auto-sampler, and column oven were from Agilent. The column compartment and detector compartment were operated at 150°C. The columns were three PLgel 10 μιη Mixed-B, columns (Agilent). The carrier solvent was 1,2,4-trichlorobenzene (TCB) with a flow rate of 1.0 mL/min. Both solvent sources for chromatographic and sample preparation contained 250 ppm of butylated hydroxytoluene (BHT) and were nitrogen sparged. Polyethylene samples were prepared at targeted polymer concentrations of 2 mg/mL by dissolving in TCB at 160°C for 3 hour on the auto-sampler just prior the injection. The injection volume was 200 μΐ,.

[0050] Calibration of the GPC column set was performed with 21 narrow molecular weight distribution polystyrene standards. The molecular weights of the standards ranged from

580 to 8,400,000 g/mol, and were arranged in 6 "cocktail" mixtures, with at least a decade of separation between individual molecular weights. The polystyrene standard peak molecular weights were converted to polyethylene molecular weights using the following equation (as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)):

^^polyethylene A(M polystyrene)

(i)

[0051] Here B has a value of 1.0, and the experimentally determined value of A is around 0.42.

[0052] A third order polynomial was used to fit the respective polyethylene-equivalent calibration points obtained from equation (1) to their observed elution volumes. The actual polynomial fit was obtained so as to relate the logarithm of polyethylene equivalent molecular weights to the observed elution volumes (and associated powers) for each polystyrene standard.

[0053] Number-, weight- and z-average molecular weights are calculated according to the following equations: _ ∑Wf;

(2) ∑(^ * , )

MW = :

(3)

_ x te * ,² )

(4)

Where, Wfi is the weight fraction of the z^'-th component and M, is the molecular weight of the z^'-th component. The MWD is expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn).

[0054] The accurate A value was determined by adjusting A value in equation (1) until Mw, the weight average molecular weight calculated using equation (3) and the corresponding retention volume polynomial, agreed with the independently determined value of Mw obtained in accordance with the linear homopolymer reference with known weight average molecular weight of 120,000 g/mol.

Differential Scanning Calorimetry (DSC)

[0055] Differential Scanning Calorimetry (DSC) is used to measure the melting and crystallization behavior of a polymer over a wide range of temperatures. For example, the TA Instruments Q1000 DSC, equipped with an RCS (refrigerated cooling system) and an autosampler is used to perform this analysis. During testing, a nitrogen purge gas flow of 50 ml/min is used. Each sample is melt pressed into a thin film at about 175°C; the melted sample is then air-cooled to room temperature (approx. 25 °C). The film sample is formed by pressing a "0.1 to 0.2 gram" sample at 175°C at 1,500 psi, and 30 seconds, to form a "0.1 to 0.2 mil thick" film. A 3-10 mg, 6 mm diameter specimen is extracted from the cooled polymer, weighed, placed in a light aluminum pan (ca 50 mg), and crimped shut. Analysis is then performed to determine its thermal properties. The thermal behavior of the sample is determined by ramping the sample temperature up and down to create a heat flow versus temperature profile. First, the sample is rapidly heated to 180°C, and held isothermal for five minutes, in order to remove its thermal history. Next, the sample is cooled to -40°C, at a 10 °C/minute cooling rate, and held isothermal at -40 °C for five minutes. The sample is then heated to 150°C (this is the "second heat" ramp) at a 10°C/minute heating rate. The cooling and second heating curves are recorded. The cool curve is analyzed by setting baseline endpoints from the beginning of crystallization to -20°C. The heat curve is analyzed by setting baseline endpoints from -20°C to the end of melt. The values determined are peak melting temperature (Tm), peak crystallization temperature (Tc), onset crystallization temperature (Tc onset), heat of fusion (Hf) (in Joules per gram), the calculated % crystallinity for polyethylene samples using: % Crystallinity for PE = ((Hf)/(292 J/g)) x 100, and the calculated % crystallinity for polypropylene samples using: % Crystallinity for PP = ((Hf)/165 J/g)) x 100. The heat of fusion (Hf) and the peak melting temperature are reported from the second heat curve. Peak crystallization temperature and onset crystallization temperature are determined from the cooling curve.

13C-NMR

Sample Preparation

[0056] The samples were prepared by adding approximately 2.7g of a 50/50 mixture of tetrachloroethane-d2/orthodichlorobenzene containing 0.025 M Cr(AcAc)3 to 0.25g sample in a Norell 1001-7 10mm NMR tube. The samples were dissolved and homogenized by heating the tube and its contents to 150°C using a heating block and vortex mixer. Each sample was visually inspected to ensure homogeneity.

Data Acquisition Parameters

[0057] The data were collected using a Bruker 400 MHz spectrometer equipped with a Bruker Dual DUL high-temperature CryoProbe. The data were acquired using 320 transients per data file, a 6 sec pulse repetition delay, 90 degree flip angles, and inverse gated decoupling with a sample temperature of 120°C. All measurements were made on non-spinning samples in locked mode. Samples were allowed to thermally equilibrate for 7 minutes prior to data acquisition. The ¹³C NMR chemical shifts were internally referenced to the mmmm pentad at 21.90 ppm or the EEE triad at 30.0 ppm.

Data Analysis

[0058] Composition was determined using the assignments from S. Di Martino and M. Keclchtermans, "Determination of the Composition of Ethylene-Propylene-Rubbers Using 13C-NMR Spectroscopy," Journal of Applied Polymer Science, Vol. 56, 1781-1787 (1995), and integrated CI 3 NMR spectra to solve the vector equation s=fM where M is an assignment matrix, s is a row vector representation of the spectrum, and / is a mole fraction composition vector. The elements of / were taken to be triads of E and O with all permutations of E and O. The assignment matrix M was created with one row for each triad in / and a column for each of the integrated NMR signals. The elements of the matrix were integral values determined by reference to the assignments in Ref. 1. The equation was solved by variation of the elements of / as needed to minimize the error function between s and the integrated C13 data for each sample. This is easily executed in Microsoft Excel using the Solver function.

Apparent Density

[0059] A sample material is cut into a square piece of 15 cm x 15 cm in size. The volume of this piece is calculated from the thickness measured at four points. The division of the weight by the volume gives the apparent density (an average of four measurements is taken).

Height Loss and 25% Deflection Force

[0060] The cushioning net structure is tested for height loss and 25% deflection force in accordance with ASTM D 3574, Test B2. After the initial measurement of height and 25% deflection force, the cushioning net structure is subjected to constant force pounding of 10,000 cycles, where the fatigue tester is calibrated to 220N and the pounder has a rate of 80 cycles/min. After waiting for 24 hours once pounding is completed, the cushioning net structure is tested for height and 25% deflection force again. Loss in height and 25% deflection force are measured in percent.

EXAMPLES

Inventive Resin

[0061] The inventive propylene interpolymer was prepared via the method described above, and has a density of 0.876 g/cc and a melt flow rate, MFR, of 25.0 g/10 min (230°C/2.16 kg). Additional properties of the inventive propylene interpolymer are outlined in Table 1 below.

Comparative Resins

[0062] Comparative resin A is an ethylene/alpha-olefin block copolymer having a density of 0.877 g/cc and a melt index, 12, of 15 g/10 min (190°C/2.16 kg), which is available as INFUSE™ 9817 from The Dow Chemical Company (Midland, MI).

[0063] Comparative resin B is an ethylene-based plastomer having a density of 0.907 g/cc and a melt index, 12, of 12 g/10 min (190°C/2.16 kg), which is available as KERNEL™ KS571 from Japan Polychem Corporation (Japan). Table 1 lists additional properties of the comparative resins below.

[0064] Table 1

[0065] The inventive and comparative resins were used to make cushioning net structures. The cushioning net structures were made according to the procedure described in U.S. Patent 7,625,629, which is incorporated by reference herein in its entirety. As shown in Table 2 below, the cushioning net structures were tested for height loss and 25% deflection force.

[0066] Table 2

[0067] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as "40 mm" is intended to mean "about 40 mm."

[0068] Every document cited herein, if any, including any cross- referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0069] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.

Claims

We claim:

1. A cushioning network structure comprising a plurality of random loops arranged in a three-dimensional orientation, wherein the plurality of random loops are formed from a propylene interpolymer comprising at least 60 wt.% units derived from propylene and between 1 and 40 wt.% units derived from ethylene, wherein the propylene interpolymer has a density of from 0.840 g/cm³ to 0.900 g/cm³, a highest DSC melting peak temperature of from 50.0°C to 120.0°C, a melt flow rate of from 1 to 100 g/10 min, and a molecular weight distribution of less than 4.

2. The cushioning network structure of claim 1, wherein the propylene interpolymer has a density of from 0.850 g/cm³ to 0.890 g/cm³.

3. The cushioning network structure of claims 1 or 2, wherein the propylene interpolymer has a melt flow rate of from 2 to 50 g/10 min.

4. The cushioning network structure of claims 1 - 3, wherein the propylene interpolymer has between 1 and 20 wt.% units derived from ethylene.

5. The cushioning network structure of claim 4, wherein the propylene interpolymer has between 3 and 18 wt.% units derived from ethylene.

6. The cushioning network structure of claims 1-5, wherein the propylene interpolymer has a DSC crystallization onset temperature, Tc-Onset, of less than 85°C.

7. The cushioning network structure of claims 1- 6, wherein the propylene interpolymer has a temperature differential between the highest DSC melting peak temperature, Tm, and the DSC crystallization peak temperature, Tc, of 25°C-50°C.

8. The cushioning network structure of claims 1-7, wherein the propylene interpolymer has a weight average molecular weight (Mw) of at least 50,000 grams per mole (g/mol).

9. The cushioning network structure of claims 1-8, wherein the propylene interpolymer has a percent crystallinity in the range of from 0.5 % to 45%.

10. The cushioning network structure of claims 1 - 9, wherein each of the plurality of random loops in the cushioning network structure has a diameter of about 0.1 mm to about 3 mm.

11. The cushioning network structure of claims 1 - 10, wherein the cushioning network structure has an apparent density in a range of about 0.016 g/cm³ to about 0.1 g/cm³.

12. A method of manufacturing a cushioning network structure comprising a plurality of random loops arranged in a three-dimensional orientation, wherein the method comprises: providing a propylene interpolymer comprising at least 60 wt.% units derived from propylene and between 1 and 40 wt.% units derived from ethylene, wherein the propylene interpolymer has a density of from 0.840 g/cm³ to 0.900 g/cm³, a highest DSC melting peak temperature of from 50.0°C to 120.0°C, a melt flow rate of from 1 to 100 g/10 min, and a molecular weight distribution of less than 4; and forming the propylene interpolymer into a plurality of random loops having a three- dimensional orientation to form a cushioning network structure.