1. Patent Search
  2. Details

Process for Producing Foam Article

20230407030 ยท 2023-12-21

    Inventors

    Cpc classification

    International classification

    Abstract

    The present disclosure provides a process. In an embodiment, the process includes providing a foamable composition. The foamable composition includes an ethylene-based elastomer, a blowing agent, and a peroxide. The process includes heating the foamable composition to form a pliable formulation. The pliable formulation has (i) a viscosity (0.1 rad/s at 180 C.) from greater than 70,000 Pa.Math.s to 2,000,000 Pa.Math.s, (ii) a tan delta (0.1 rad/s at 180 C.) from 0.2 to less than 2, (iii) a strain hardening index greater than 2.5 to 6, and (iv) an extensional viscosity (1 s.sup.1 at 180 C.) from greater than 400,000 Pa-s to 7,000,000 Pa-s. The process includes introducing the pliable formulation into a mold having an expandable mold cavity and unidirectionally expanding the expandable mold to form a crosslinked foam article. The process includes cooling, in the expanded mold, the crosslinked foam article; and removing the crosslinked foam article from the expandable mold.

    Claims

    1. A process comprising: providing a foamable composition comprising an ethylene-based elastomer, a blowing agent, and a peroxide; heating the foamable composition to form a pliable formulation having (i) a viscosity (0.1 rad/s at 180 C.) from greater than 70,000 Pa.Math.s to 2,000,000 Pa.Math.s, (ii) a tan delta (0.1 rad/s at 180 C.) from 0.2 to less than 2, (iii) a strain hardening index greater than 2.5 to 6, (iv) an extensional viscosity (1 s.sup.1 at 180 C.) from greater than 400,000 Pa-s to 7,000,000 Pa-s; introducing the pliable formulation into a mold having an expandable mold cavity; unidirectionally expanding the expandable mold to form a crosslinked foam article; cooling, in the expanded mold, the crosslinked foam article; removing the crosslinked foam article from the expandable mold; and forming a crosslinked foam article having an average aspect ratio from 1.7 to 1.9.

    2. The process of claim 1 comprising removing, before the expanding, air from the mold cavity.

    3. The process of claim 1 comprising forming a crosslinked foam article having (i) an average cell size 150 microns to 275 microns, or (ii) a density (with skin) from 0.170 g/cc to 0.250 g/cc, or (iii) a compression set (24 hr) 5% to less than 10%, or (iv) a Shore A hardness 10 to 25, or (v) a rebound resilience from 30% to 50%.

    4. The process of claim 3 comprising providing a foamable composition comprising from 88 wt % to 90 wt % of an ethylene-based elastomer that is an ethylene/octene multi-block copolymer having a density from 0.870 g/cc to 0.890 g/cc and a melt index from 1.0 g/10 min to 5.0 g/10 min, a chemical blowing agent, and from 0.5 wt % to 3.0 wt % of an organic peroxide; first heating the foamable composition to form a pliable formulation having (i) a viscosity (0.1 rad/s at 180 C.) from greater than 70,000 Pa.Math.s to 2,000,000 Pa.Math.s, (ii) a tan delta (0.1 rad/s at 180 C.) from 0.2 to less than 2, (iii) a strain hardening index greater than 2.5 to 6, (iv) an extensional viscosity (1 s.sup.1 at 180 C.) from greater than 400,000 Pa-s to 7,000,000 Pa-s; second heating the pliable formulation; introducing the pliable formulation into a mold having an expandable mold cavity; closing the mold and third heating the pliable formulation in the closed mold; opening the mold and unidirectionally expanding in the z-axis only the expandable mold to form a crosslinked foam article; and forming a crosslinked foam article having (i) an average cell size 150 microns to 275 microns, and (ii) an average aspect ratio from 1.7 to 1.9, and (iii) a density (with skin) from 0.170 g/cc to 0.250 g/cc, and (iv) a compression set (24 hr) 5% to less than 10%, and (v) a Shore A hardness 10 to 25, and (vi) a rebound resilience from 30% to 50%.

    5. The process of claim 1 comprising first heating the foamable composition at a temperature of 110 C. for 15 minutes to form the pliable formulation.

    6. The process of claim 5 comprising second heating the pliable formulation in an oven at a temperature of 110 C. for 15 minutes.

    7. The process of claim 6 comprising placing a pre-foamed part in the mold cavity; introducing the pliable formulation in direct contact with, the pre-foamed part; and forming a crosslinked foam article directly onto the pre-foamed part.

    Description

    [0105] The process includes introducing the pliable formulation into a mold having an expandable mold cavity. As shown in FIG. 1, a mold 10 includes a housing 12 and a movable part 14 in reciprocal and operative communication with housing 12. Movable part 14 moves unidirectionally, that is movement along the z-axis only. The operation between movable part 14 and housing 12 permits no movement in the x-axis and permits no movement in the y-axis. FIG. 1 shows pliable formulation 16 in the mold cavity and movable part 14 in a first position A that is a closed position. With movable part 14 in the closed position, mold 10 is heated to a temperature to kick-off or otherwise initiate the peroxide (a temperature to decompose the peroxide) and kick-off or otherwise initiate the chemical blowing agent (when a chemical blowing agent is used). In an embodiment, pressure (positive pressure or negative pressure) is also applied to the mold cavity when movable part 14 is in the closed position A so as to remove any air present in the mold cavity and/or remove any air present in the pliable formulation 16.

    [0106] The process includes unidirectionally expanding the expandable mold to form a crosslinked foam article. FIG. 2 shows movable part 14 moved to a second position B, or otherwise an expanded position. Moving movable part 14 to the expanded position B expands, or otherwise increases, the volume of the mold cavity, thereby triggering the pliable formulation to expand and foam. The expanding and foaming pliable formulation fills, or completely fills, the expanded volume of the mold cavity and forms a crosslinked foam article 18. The resultant crosslinked foam article 18 takes the shape of the expanded mold cavity. As mentioned above, movable part 14 moves along the z-axis only, thereby restricting the expansion of the foaming pliable formulation in a single axis, along the z-axis only. During expanding and foaming the pliable formulation 16 (and resultant crosslinked foam article 18) is/are not exposed to the ambient environment. The unidirectional mold expansion forms anisotropic cells in the crosslinked foam article. An anisotropic cell, is a foam cell having an asymmetric shape, whereby the length of the cell is larger in one dimension than the length of the cell in the other dimensions.

    [0107] The process includes cooling the crosslinked foam article 18 in the expanded mold. Cooling occurs with movable part 14 remaining at expanded position B. Cooling is conducted for a time duration sufficient for the crosslinked foam article to solidify and to set. In an embodiment, the process includes cooling the crosslinked foam article to a temperature from 15 C. to 25 C.

    [0108] The process forms a crosslinked foam article 18 having one, some, or all of the following properties: [0109] (i) an average cell size 150 microns to 275 microns, and/or [0110] (ii) an average aspect ratio from 1.5 to 2.0, and/or [0111] (iii) a density (with skin) from 0.170 g/cc to 0.250 g/cc, and/or [0112] (iv) a compression set (24 hr) 5% to less than 10%, and/or [0113] (v) a Shore A hardness 10 to 25, and/or [0114] (vi) a rebound resilience 30% to 50%.

    [0115] In an embodiment, the process includes [0116] providing a foamable composition comprising [0117] (i) from 88 wt % to 90 wt % of an ethylene-based elastomer that is an [0118] ethylene/octene multi-block copolymer having a density from 0.870 g/cc to 0.89 g/cc and a melt index from 1.0 g/10 min to 5.0 g/10 min or 5.0 g/10 min, [0119] (ii) a chemical blowing agent, and [0120] (iii) from 0.5 wt % to 3.0 wt %, or from 0.7 wt % to 2.7 wt % of an organic peroxide. Weight percent is based on total weight of the foamable composition. The process includes heating the foamable composition to form a pliable formulation having [0121] (i) a viscosity (0.1 rad/s at 180 C.) from greater than 70,000 Pa.Math.s to 2,000,000 Pa.Math.s, [0122] (ii) a tan delta (0.1 rad/s at 180 C.) from 0.2 to less than 2, [0123] (iii) a strain hardening index greater than 2.5 to 6, [0124] (iv) an extensional viscosity (1 s.sup.1 at 180 C.) from greater than 400,000 Pa-s to 7,000,000 Pa-s. The process further includes introducing the pliable formulation into a mold having an expandable mold cavity; [0125] unidirectionally expanding the expandable mold to form a crosslinked foam article; [0126] cooling, in the expanded mold, the crosslinked foam article; and [0127] forming a crosslinked foam article having [0128] (i) an average cell size 150 microns to 275 microns, or from 200 microns to 260 microns, and/or [0129] (ii) an average aspect ratio from 1.5 to 2.0, or from 1.7 to 1.9 and/or [0130] (iii) a density (with skin) from 0.170 g/cc to 0.250 g/cc, and/or [0131] (iv) a compression set (24 hr) 5% to less than 10%, and/or [0132] (v) a Shore A hardness 10 to 25, and/or [0133] (vi) a rebound resilience from 30% to 50% (hereafter referred to as foam 1).

    [0134] In an embodiment, the process includes placing a shoe part (such as a pre-foamed part) in the mold cavity and introducing the pliable formulation with previously-described properties (i)-(iv) on, and in direct contact with, the pre-foamed part. The process includes performing heating, unidirectionally expanding, cooling, and forming a crosslinked foam article (foam 1) directly onto the pre-foamed part. In this way foam 1 is foamed onto, or otherwise fused onto, the pre-foamed part.

    [0135] The present crosslinked foam article can be molded and shaped as an article of footwear or incorporated into an article of footwear. Nonlimiting examples of suitable footwear articles for the present crosslinked foam article include an outsole, a midsole, an insole, and combinations thereof.

    [0136] By way of example, and not limitation, some embodiments of the present disclosure are described in detail in the following examples.

    Examples

    [0137] The raw materials used in the preparation for the present crosslinked foam composition, the adhesive layer, and the substrate in the Inventive Examples (IE) are provided in Table 1 below.

    TABLE-US-00001 TABLE 1 Starting materials for the foam Component Specification Source INFUSE 9100 Ethylene/octene multi-block copolymer, density: The Dow Chemical Company 0.877 g/cc; MI: 1.0 g/10 min, Tm: 120 C. INFUSE 9500 Ethylene/octene multi-block copolymer, density: The Dow Chemical Company 0.877 g/cc; MI: 5.0 g/10 min, Tm: 122 C. Luperox DC40P Crosslinking agent, Dicumylperoxide ((40%) blended Arkema with an inert filler and scorch protected) Luvobatch BA 5332 Chemical Blowing agent, azodicarbonamide (40%) Lehvoss Omyalite 95T Filler, Ca CO.sub.3 (powder) OMYA AG Switzerland Zinc Oxide (ZnO) Blowing agent activator, CAS: 1314-13-2 Brenntag Schweizerhall AG Zinc Stearate (ZnSt) Blowing agent activator, CAS: 557-05-1 Brenntag Schweizerhall AG

    1. Composition Preparation

    [0138] INFUSE 9100 or INFUSE 9500 (ethylene-based elastomer that is ethylene/octene multi-block copolymer) is added onto a Colin Roll mill with the front roll at 130 C. and the back roll at 125 C. and a rotation speed of 8 rounds per minute (rpm). Zinc oxide, zinc stearate and CaCO.sub.3 filler subsequently are added upon complete melting of the ethylene/octene multi-block copolymer. The blowing agent and peroxide are added last after the fillers and blowing agent activators are uniformly incorporated into the ethylene/octene multi-block copolymer to form the foamable composition. The foamable compositions are provided in Table 2 below.

    TABLE-US-00002 TABLE 2 Foamable Compositions Example IE1 IE2 IE3 CS-1 CS-2 CS-3 IE-4/CS-4 IE-5/CS-5 IE-5/CS-6 Component Parts/wt Parts/wt Parts/wt Parts/wt Parts/wt Parts/wt Parts/wt Parts/wt Parts/wt INFUSE 9500 100 100 100 0 0 0 100 100 100 INFUSE 9100 0 0 0 100 100 100 Luperox DC40P- 0.5 1 1.5 2 2.5 3 2 2.5 3 SP2 Luvobatch BA 5 5 5 5 5 5 5 5 5 5332 ZnO 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 ZnSt 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Omyalite 95T 5 5 5 5 5 5 CScomparative sample, IEinventive example

    2. Foaming Procedure

    [0139] The foaming procedures for the comparative samples (CS) and the inventive examples (IE) are provided in Table 3 below.

    TABLE-US-00003 TABLE 3 Foaming procedures for comparative samples and inventive examples Comparative samples Inventive examples 1. An amount of a CS composition from Table 1 was 1. An amount of an IE composition from Table 1 was weighed to weighed to completely fill the mold volume as shown fill completely the bottom compartment of the mold as shown in in FIG. 1. FIG. 1. The IE composition was heated in the mold for 15 minutes at 110 C. until it was sufficiently pliable and form the IE pliable formulation. 2. The CS composition then was removed from the 2. The IE pliable formulation was transferred to a molding ring mold and was heated for 10 minutes at 110 C. in an (inner diameter of 120 mm and height of 8 mm) and oven to soften and form the CS pliable formulation. compression molded in a Colin Table press P 200E for 5 minutes at 120 C. between silicone paper to form the pre-mold. 3. The mold was heated (to 180 C.) and was treated 3. The pre-mold was heated a second time, this time in an oven with silicone release agent, which was sprayed on the at 110 C. for 15 minutes. hot mold interior surfaces, the release agent cured for 20 minutes to prevent sticking of the foam upon opening of the mold. 4. The CS pliable formulation was removed from the 4. After the second heating, the pre-mold was transferred to oven and placed in the open mold, making sure that the mold and pressed tightly in the mold cavity to ensure the the mold surface was covered as well as possible. absence of air in the mold cavity. 5. The heated mold (180 C.) was closed for 10 5. After closing the mold, the pre-mold was compressed inside minutes to allow for curing and decomposition of the the molding cavity at 180 C. at 150 bar for 11 minutes to allow blowing agent under a pressure of 150 bar. A vacuum for curing and decomposition of the blowing agent. was applied to ensure proper filling of the mold cavity. 6. After 10 minutes, the mold was fully opened upon 6. After 11 minutes, the mold was then opened to an expansion which rapid foam expansion occurred in all directions ratio of 3.75, permitting expansion unidirectionally, in the z-axis (x-axis, y-axis, z-axis), ejecting the foam from the only, as shown in FIG. 2. mold. The crosslinked foam material was recovered and cooled in a fume hood. 7. The mold was cooled to room temperature and the crosslinked foam article removed from the mold.

    [0140] Table 4 provides properties for foamable compositions, pliable formulations, and inventive crosslinked foam articles and comparative samples.

    TABLE-US-00004 TABLE 4 CS-A IE2 IE3 IE4 IE5 IE6 CS-1 wt % wt % wt % wt % wt % wt % wt % Component INFUSE 9500 90.01 89.61 89.21 88.81 88.42 88.03 INFUSE 9100 88.81 Luperox DC40P- 0.45 0.90 1.34 1.78 2.21 2.64 1.78 SP2 Luvobatch BA 4.50 4.48 4.46 4.44 4.42 4.40 4.44 5332 ZnO 0.27 0.27 0.27 0.27 0.27 0.26 0.27 ZnSt 0.27 0.27 0.27 0.27 0.27 0.26 0.27 Omyalite 95T 4.50 4.48 4.46 4.44 4.42 4.40 4.44 Pliable formulation S* (Pa .Math. s) at 0.1 25667.4 71326.2 261771 572573 759010 1192470 1737030 rad/s 180 C. Tandelta at 0.1 3.04 1.38 0.70 0.40 0.34 0.26 0.25 rad/s 180 C. E+ (Pa .Math. s) at H = 2 54976 406300 784150 1731600 2416100 5099500 5393700 180 C. SHI 180 C. 1.04 3.70 2.76 3.36 3.72 5.29 3.95 Foam part Ave cell size 277 257 229 249 206 178 124 Ave aspect ratio 1.60 1.72 1.82 1.88 1.82 1.77 1.63 Density w/skin 0.194 0.226 0.215 0.234 0.234 0.191 Density w/o skin 0.201 0.136 0.134 0.139 0.163 0.178 Compression set 12.2 14.4 24.6 17.9 17.7 15.5 37.0 30 min Compression set 9.1 9.6 8.8 6.5 6.9 8.9 4.2 24 hr Shore A 12.6 15.9 20.4 16.9 20.6 23.6 16.5 Rebound 49.5 45.2 38.5 41.3 39.3 50.8 resilience Split tear 1.4 1.8 1.9 1.9 1.9 CS-2 CS-3 CS-4 CS-5 CS-6 wt % wt % wt % wt % wt % Component INFUSE 9500 88.81 88.42 88.03 INFUSE 9100 88.42 88.03 Luperox DC40P- 2.21 2.64 1.78 2.21 2.64 SP2 Luvobatch BA 4.42 4.40 4.44 4.42 4.40 5332 ZnO 0.27 0.26 0.27 0.27 0.26 ZnSt 0.27 0.26 0.27 0.27 0.26 Omyalite 95T 4.42 4.40 4.44 4.42 4.40 Pliable formulation S* (Pa .Math. s) at 0.1 2369680 2877680 572573 759010 1192470 rad/s 180 C. Tandelta at 0.1 0.19 0.16 0.40 0.34 0.26 rad/s 180 C. E+ (Pa .Math. s) at H = 2 1731600 2416100 5099500 180 C. SHI 180 C. 3.36 3.72 5.29 Foam part Ave cell size 116 104 120 107 94 Ave aspect ratio 1.65 1.66 1.58 1.58 1.61 Density w/skin 0.220 0.255 0.152 0.152 0.174 Density w/o skin 0.187 0.226 0.136 0.142 0.163 Compression set 32.3 24.2 46.2 36.6 22.7 30 min Compression set 5.6 6.6 8.5 6.4 6.7 24 hr Shore A 19.2 24.5 8.7 10.6 14.8 Rebound 49.2 47.5 52.7 51.7 50.8 resilience Split tear 2.0 2.1 1.2 1.5 1.6 IE = inventive example, CS = comparative sample

    [0141] The present process enables the production of crosslinked foam article using lower levels of peroxide from (0.5 wt % to 3.0 wt %, or from 0.7 wt % to 2.7 wt %) and still achieving suitable foam properties for use in footwear, and for use in midsoles in particular. The present process also produces inventive examples of crosslinked foam article having a greater aspect ratio (1.72-1.88) in combination with greater average cell size (206-257 microns) than the comparative samples (aspect ratio 1.58-1.65 and average cell size 94-277 microns).

    [0142] The present process enables the production of a crosslinked foam article in a single (one-to-one) foaming step without the need for an additional foam compression step as in a phylon foaming process, for example. A foam part can be placed into the mold cavity, onto which the present pliable formulation is placed and subsequently unidirectionally foamed and crosslinked for direct foaming of the instant crosslinked foam article onto the pre-inserted foam part.

    [0143] It is specifically intended that the present disclosure not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.