WO2014120191A1

WO2014120191A1 - System and method for increasing foam hardness

Info

Publication number: WO2014120191A1
Application number: PCT/US2013/024073
Authority: WO
Inventors: Chi-Fan Hsu; Eugene PEIFFER
Original assignee: Johnson Controls Technology Company
Priority date: 2013-01-31
Filing date: 2013-01-31
Publication date: 2014-08-07

Abstract

An open cell, foam article includes a first section produced from a first reaction mixture including: a first polyol formulation, the first polyol formulation including a polyether polyol and a copolymer polyol; and an isocyanate mixture having a difunctional isocyanate, a polyfunctional isocyanate, or a combination thereof. The foam article also includes a second section continuous with the first section, wherein the second section is produced from a second reaction mixture including a second polyol formulation, the second polyol formulation having the polyether polyol, the copolymer polyol, and a polyol-based crosslinker having a higher functionality than the polyether polyol and the copolymer polyol. The second polyol formulation has a higher concentration of the polyol-based crosslinker than the first polyol formulation.

Description

SYSTEM AND METHOD FOR INCREASING FOAM HARDNESS

BACKGROUND

[0001] The present disclosure relates generally to the production of foam objects and, more specifically, to the production of foam seating.

[0002] Polyurethanes are a general class of polymers in which organic repeating units are joined by carbamate and urea linkages. Polyurethanes are typically produced by reactions in which polyols having two or more hydroxyl groups are reacted with an isocyanate having two or more isocyanate groups. The hydroxyl groups and isocyanate groups may react with one another in a one-to-one ratio to form carbamate and urea linkages, and in certain configurations, the relationship can be as wide ranging as from as low as about 0.6 to 1 up about to 1 to 1.3. To facilitate these polymerization reactions, the reaction materials may be heated and, alternatively or additionally, a catalyst may be provided.

[0003] Polyurethanes have a wide variety of molded uses, including foam seating, foam padding, sealants, gaskets, and so on. The end use of a given polyurethane is dependent on the particular starting materials reacted to produce the polyurethane (e.g., the molecular structure of the polyol and/or isocyanate), and the conditions under which the starting materials are reacted. For instance, polyurethane foam products, and in particular foam seating, foam paneling, and other shaped polyurethane foams, are often produced inside of a mold cavity having a shape corresponding to a desired shape of the foam.

[0004] To produce the polyurethane foam inside of the mold cavity, the materials of a foam formulation, which includes an unreacted mixture of polyol and isocyanate, are disposed in the mold. The mixture then reacts, for example after the mixture is heated. During the reaction, the mixture foams and expands to fill the interior of the mold cavity, thereby assuming the shape of the cavity. Additional materials may be provided to enhance foaming of the mixture. For example, water may be used as one type of many different blowing agents to allow the urethane mixture to fill the mold. Water, which is the most environmentally friendly blowing agent, reacts with the isocyanate to create urea. The foam is allowed to harden within the mold cavity. Once the foam hardens, the foam object (e.g., a seat cushion) may be removed from the mold and used (e.g., within a seat) after a cure time.

BRIEF DESCRIPTION OF THE INVENTION

[0005] The present disclosure includes embodiments directed toward the production of foam articles having sections of varying hardness. For example, a first embodiment includes a method of producing an open cell foam article. The method includes forming a first section of the open cell foam article using a first reaction mixture having: a first polyol formulation, the first polyol formulation including polyether polyols, copolymer polyols, and a polyol-based crosslinker having a higher functionality than the polyether polyol and the copolymer polyol; and an isocyanate mixture having a difunctional or polyfunctional isocyanate, or mixtures thereof. The method further includes forming a second section of the open cell foam article using a second reaction mixture comprising a second polyol formulation, the second polyol formulation comprising the polyether polyols, the copolymer polyols, and the polyol- based crosslinker, wherein the second polyol formulation has a higher concentration of the polyol-based crosslinker than the first polyol formulation.

[0006] Another embodiment provides an open cell, foam article. The article includes a first section produced from a first reaction mixture including: a first polyol formulation, the first polyol formulation including a polyether polyol and a copolymer polyol; and an isocyanate mixture having a difunctional isocyanate, a polyfunctional isocyanate, or a combination thereof. The foam article also includes a second section continuous with the first section, wherein the second section is produced from a second reaction mixture including a second polyol formulation, the second polyol formulation having the polyether polyol, the copolymer polyol, and a polyol-based crosslinker having a higher functionality than the polyether polyol and the copolymer polyol. The second polyol formulation has a higher concentration of the polyol-based crosslinker than the first polyol formulation. [0007] A further embodiment includes a vehicle seat produced using a method of producing an open cell foam article. The method includes forming a first section of the open cell foam article using a first reaction mixture having: a first polyol formulation, the first polyol formulation including polyether polyols, copolymer polyols, and a polyol-based crosslinker having a higher functionality than the polyether polyol and the copolymer polyol; and an isocyanate mixture having a difunctional or polyfunctional isocyanate, or mixtures thereof. The method further includes forming a second section of the open cell foam article using a second reaction mixture comprising a second polyol formulation, the second polyol formulation comprising the polyether polyols, the copolymer polyols, and the polyol- based crosslinker, wherein the second polyol formulation has a higher concentration of the polyol-based crosslinker than the first polyol formulation.

[0008] A further embodiment includes a vehicle seat incorporating an open cell, foam article. The article includes a first section produced from a first reaction mixture including: a first polyol formulation, the first polyol formulation including a polyether polyol and a copolymer polyol; and an isocyanate mixture having a difunctional isocyanate, a polyfunctional isocyanate, or a combination thereof. The foam article also includes a second section continuous with the first section, wherein the second section is produced from a second reaction mixture including a second polyol formulation, the second polyol formulation having the polyether polyol, the copolymer polyol, and a polyol-based crosslinker having a higher functionality than the polyether polyol and the copolymer polyol. The second polyol formulation has a higher concentration of the polyol-based crosslinker than the first polyol formulation.

DRAWINGS

[0009] FIG. 1 is a schematic illustration of an embodiment of a foam object production system in which a foam formulation is provided to a mold cavity to produce the foam object.

[0010] FIG. 2 is a process flow diagram illustrating an embodiment of a method for producing a foam object using the system of FIG. 1. [0011] FIG. 3 is a process flow diagram illustrating an embodiment of a method for producing a foam object having sections of varying hardness using the system of FIG. 1.

[0012] FIG. 4 is a plot depicting 25% Indentation Load Deflection of a foam as a function of polyol crosslinker amount.

[0013] FIG. 5 is a plot depicting 50% Indentation Load Deflection of a foam as a function of polyol crosslinker amount.

[0014] FIG. 6 is a plot depicting Push-Pull values of a foam as a function of polyol crosslinker amount.

[0015] FIG. 7 is a plot depicting tear strength of a foam as a function of polyol crosslinker amount.

[0016] FIG. 8 is a plot depicting the density of a foam as a function of polyol crosslinker amount.

DETAILED DESCRIPTION

[0017] As noted above, in a general sense, a foam product may be produced by a reaction mixture including a polyol formulation having polyol molecules with two or more hydroxyl moieties and an isocyanate formulation having isocyanate molecules with two or more isocyanate moieties. In some instances, other materials may be incorporated into the reaction mixture either separately or as a part of the polyol and/or isocyanate formulation to enhance various properties of the resulting foam. For example, in certain seating applications, it may be desirable to increase the hardness of the foam in certain areas so as to provide enhanced load-bearing capabilities, enhanced resistance to deformation, and enhanced appearance. One example of such a material is a styrene-acrylonitirile (SAN) copolymer polyol, which is produced from a polyol and a styrene-acrylonitirile copolymer. Unfortunately, the incorporation of these types of materials can lead to higher production costs and increased weight of the foam product. [0018] In accordance with the present disclosure, these and other shortcomings of existing approaches may be mitigated by utilizing one or more polyol-based crosslinkers to enhance the hardness of one or more sections of a foam object. In certain of these embodiments, the one or more polyol-based crosslinkers may replace all or a portion of the copolymer polyol utilized in a polyol formulation. Indeed, using such crosslinkers, it may be possible to achieve higher levels of hardness while maintaining foam density. In other words, present embodiments may provide foam objects, such as foam seating, having the same or greater hardness at the same or lower weight than a foam object not utilizing the crosslinkers disclosed herein. It should also be noted that all of the foams described herein are intended to denote open cell foams.

[0019] To facilitate discussion of the present techniques, a diagrammatical illustration of a system used to produce a foam object in accordance with present embodiments is provided in FIG. 1. In particular, FIG. 1 is a schematic overview of a system 10 for preparing a foam object 12 (e.g., a polyurethane seat cushion) within a mold 14. The mold 14 includes a mold material 16 and a mold cavity 18 formed into the mold material 16. The mold cavity 18 is configured to shape the foam object 12 as the foam is produced. The mold material 16 may include any material suitable for use during the foam production process such as a metal (e.g., aluminum, steel, nickel, or other alloyed metals), an epoxy, a composite, or similar materials that are capable of providing mechanical stability for the foam produced within the cavity 18.

[0020] As may be appreciated, the mold cavity 18 takes the form of the desired shape of the foam object 12 when closed, such as when bringing first and second mold pieces 20, 22 in contact with one another at their extents surrounding the cavity 18. While illustrated as including two pieces, the mold 14 may include less than two pieces (e.g., a single-piece closed mold), or more than two pieces (e.g., between 3 and 20), such that the mold cavity 18 is formed into the desired shape of the foam object 12 when the pieces are combined.

[0021] As depicted, the mold cavity 18 is configured to shape the foam object 12 into a seat having a first section 24, a second section 26, and a third section 28. In certain embodiments, such as the illustrated embodiment, the foam object 12 may be substantially symmetrical (e.g., symmetrical to the extent enabled by manufacturing tolerances) or may be unsymmetrical. By way of non-limiting example, the foam object 12 may be a seat cushion such that the first section 24 is the portion on which a person sits, and the second and third sections 26, 28 may be bolsters. As another example, the first section 24 may be a seat back, and the second and third sections 26, 28 may be side bolsters. As discussed in detail below, the different sections of the foam object 12 may have the same hardness or different hardness, the same densities or different densities, and so on.

[0022] In essence, the different sections of the foam object 12 are produced in different sections of the mold cavity 18. For example, in the illustrated embodiment, the first, second, and third sections 24, 26, 28 of the foam object 12 are produced in a first reaction zone 30, a second reaction zone 32, and a third reaction zone 34, respectively, of the mold cavity 18, where the foam chemistry may be varied in one or more of the zones. It should be further noted that, while illustrated as including three reaction zones that form the three discrete sections of the foam object 12, the mold 14 may include less than three, or more than three reaction zones such that the foam object 12 includes less than three, or more than three sections. For example, the mold 14 may include at least two reaction zones, such as between 2 and 20 reaction zones, between 2 and 10 reaction zones, or between 2 and 6 reaction zones such that the foam object 12 includes between 2 and 20 sections, between 2 and 10 sections, or between 2 and 6 sections. By way of further example, the mold cavity 18 may have a series of reaction zones such that the foam object 12 may have different sections including, but not limited to, a seat cushion, seat bolsters, a seat back, side bolsters, a headrest, armrests, leg rests, or any combination thereof.

[0023] During operation of the system 10, various materials are mixed to ultimately produce a foam formulation 40, which is a reactive mixture capable of forming the foam object 12 inside the mold 14 when subjected to suitable polymerization conditions. In the present context, the foam object 12 is a polyurethane foam object. Accordingly, the foam formulation 40 is produced from materials capable of forming repeating carbamate linkages (i.e., a polyurethane) and urea linkages from water and isocyanate. In the illustrated embodiment, the foam formulation 40 is produced by mixing, in a mixing head 42, a polyol formulation 44 and an isocyanate mixture 46. However, it will be appreciated that in certain embodiments, the foam formulation 40 may be produced upon mixing the polyol formulation 44 and the isocyanate mixture 46 directly in the mold cavity 18.

[0024] The polyol formulation 44 may include, among other reactants, polyhydroxyl compounds (e.g., small molecules or polymers having more than one hydroxyl unit including polyols and copolymer polyols). For example, the polyhydroxyl compounds may include polyether polyols, polyester polyols, and the like. In certain embodiments, a first polyol of the polyol formulation 44 may be a polyoxoalkylene polyol (i.e., a polyether polyol) formed using one or more alkylene oxides such as ethylene oxide, propylene oxide, or a combination thereof. In accordance with present embodiments, the average functionality of the first polyol may be between approximately 1 and 4, between approximately 2 and 4, or between approximately 2 and 3. As defined herein, the "average functionality" of a polyol is intended to denote the ratio of total moles of hydroxyl (OH) in the polyol to the total moles of polyol. Accordingly, the average functionality is the average number of hydroxyls per polyol molecule. It will therefore be appreciated that the average functionality of the first polyol may be any integer or non-integer between 1 and 4, such as 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0. While the first polyol may be present in the polyol formulation 44 in any amount, in a general sense, the first polyol may be present in an amount ranging from 0 to 100 parts per hundred polyol (pphp), such as between approximately 10 and 90, 20 and 80, 20 and 70, 20 and 60, 20 and 50, or 20 and 40 pphp.

[0025] The polyol formulation 44 may further include other polymeric materials, such as additional polyol materials, that are configured to impart certain physical properties to the foam object 12. One example of such a copolymer, as noted above, is a styrene-acrylonitirile (SAN) copolymer, which may be considered to be a second polyol of the polyol formulation 44. As defined herein, the copolymer polyols will include a copolymer having a polyol polymer and one or more non-polyol polymers. For example, the copolymer may be formed by the polymerization of a non-polyol component (e.g., styrene, acrylonitrile, and variants thereof) in the presence of a polyol. Generally, the non-polyol component will impart certain physical properties into the foam, such as increased hardness, increased weight or density, and the like. By way of example, to form the copolymer polyol, a polyol may be mixed with a styrene/acrylonitrile mixture such that a styrene-acrylonitrile copolymer grafts onto the polyol backbone. Therefore, the copolymer polyol will typically include a polyol (e.g., a polyether polyol or a polyester polyol) backbone, and at least one other polymeric domain that imparts a greater hardness and weight to the resulting foam than if the foam were produced with only the polyether or polyester polyol.

[0026] While the polyol used to produce the copolymer polyol may be any suitable polyol, in certain embodiments, the polyol used to produce the copolymer polyol may be similar to the first polyol. In other words, in certain embodiments, the copolymer polyol may have an average functionality that is different than, the same as, or similar to, the average functionality of the first polyol. By way of non-limiting example, the average functionality of the copolymer polyol may be between approximately 1 and 4, between approximately 2 and 4, or between approximately 2 and 3.

[0027] The copolymer polyol may be used in the polyol formulation 44 in any amount, such as between 0 and 100 pphp. By way of example, the copolymer polyol may be present in the polyol formulation 44 in an amount ranging from approximately 0 to 90 pphp, from approximately 10 to 90 pphp, from approximately 20 to 80 pphp, from approximately 30 to 80 pphp, from approximately 40 to 80 pphp, from approximately 50 to 80 pphp, or from approximately 60 to 80 pphp. Generally, as the amount of copolymer polyol increases, the hardness of the resulting foam object 12 increases. In addition, the density of the foam object 12 will also generally increase with increasing levels of copolymer polyol. As another example, the first polyol (e.g., polyether polyol) and the second polyol (e.g., copolymer polyol) are present in the polyol formulation 44 in a ratio of between approximately 0.1 :9.9 first polyol to second polyol and 9.9:0.1 first polyol to second polyol.

[0028] The polyol formulation 44 may also include a blowing agent (e.g., water, volatile organic solvents) in amounts ranging from approximately 0.1 to 9 pphp, such as between 0.5 and 6 pphp. One or more surfactants (e.g., silicone-based surfactants) may also be present in the polyol formulation 44 in amounts ranging from approximately 0.05 to 3 pphp, such as between approximately 0.2 and 1.4 pphp. Other additives (e.g., cell openers, stabilizers) may also be present in amounts ranging from 0 pphp to approximately 20 pphp. For example, natural oil polyols (e.g., polyols derived from oils occurring or extracted from agricultural products) may be present in the polyol formulation in amounts ranging from 0 to approximately 50 pphp, such as between approximately 1 and 20 pphp, or between approximately 5 and 10 pphp.

[0029] Further, the production of the foam object 12 via polymerization may be initiated by an external energy source (e.g., heat or other irradiation), or may be facilitated using a catalyst or other polymerization initiator provided as part of the polyol formulation 44. In certain embodiments, a catalyst configured to facilitate polyurethane production (e.g., reaction between the hydroxyl groups of the polyol formulation 44 and the isocyanate groups of the isocyanate mixture 46) may be used, and may be a part of the polyol formulation 44.

[0030] Examples of catalysts that may be incorporated into the polyol formulation 44 in accordance with present embodiments include gelation catalysts, blowing catalysts, or a combination thereof. Examples of suitable catalysts include tertiary amine catalysts such as l,4-diazabicyclo[2.2.2]octane and organometallic catalysts (e.g., tin-based catalysts, bismuth catalysts, dimetal catalysts). The use of catalysts in the polyol formulation 44 may reduce the temperature at which polyurethane formation is initiated, which may be beneficial for producing foam objects having desired properties and avoiding degradation of certain foam components.

[0031] In addition to the components discussed above, the polyol formulation 44 may also include one or more different types of crosslinkers. For example, the crosslinker may be an amine-based crosslinker such as diethanolamine (DEO A) preset in the polyol formulation in an amount ranging from approximately 0.05 to 4.0 pphp, such as between approximately 0.1 and 2.0 pphp. Additionally or alternatively, as depicted in FIG. 1, a polyol crosslinker 48 may be provided either directly to the mixing head 42 as a stream that is separate from the polyol formulation 44, or as a part of the polyol formulation 44, or a combination thereof. In certain embodiments, it may be desirable to provide a fixed amount of the polyol crosslinker 48 as a part of the polyol formulation 48 while using a separate stream of the polyol crosslinker 48 to adjust certain physical properties of the foam object 12. For example, in accordance with present embodiments, increased amounts of the polyol crosslinker 48 may increase the hardness of the foam object 12 (or one or more sections of the foam object 12), while maintaining or, in certain embodiments, even reducing the density of the foam object 12 (or one or more sections of the foam object 12).

[0032] Generally, the polyol crosslinker 48 will have a greater functionality and a greater hydroxyl number than the first polyol (e.g., polyether polyol) and the second polyol (e.g., copolymer polyol). For example, the polyol crosslinker 48 may have a functionality of at least 3, such as between approximately 3 and 30, between approximately 3 and 20, between approximately 3 and 17, between approximately 3 and 10, between approximately 3 and 8, or between approximately 4 and 6. As a further example, the average functionality of the polyol crosslinker 48 may be between approximately 4.2 and 6, or between approximately 4.4 and 5. The polyol- based crosslinker may be an amine-initiated polyol, or a hydroxyl-initiated polyol. For example, the polyol-based crosslinker may be initiated using sucrose, glycerin, trimethylolpropane, ethylene diamine, pentaerythritol, diethylenetriamine, sorbitol, or any combination thereof. In certain embodiments, the polyol-based crosslinker may be a dendrimer having at least 5 hydroxyls (i.e., a functionality of 5), such as between 5 and 30 hydroxyls (i.e., a functionality of between 5 and 30), or between 6 and 20 hydroxyls (i.e., a functionality of between 6 and 20). In certain embodiments, the dendrimer may be produced by polymerization or oligomerization of a polyalkoxylated monomer, such as a polyalkoxylated carboxylate (e.g., 2, 2- dimethylol propionic acid).

[0033] Suitable sources of the polyol-based crosslinker include VORANOL™ 360 sucrose/glycerin-initiated polyether polyol having an average functionality of 4.5, an average hydroxyl number of 360, and an average molecular weight of 701 , VORANOL™ 446 sucrose/glycerin-initiated polyether polyol having an average functionality of 4.5, an average hydroxyl number of 446, and an average molecular weight of 542, VORANOL™ 466 polyether polyol having an average hydroxyl number of 466, and VORANOL™ RA640 amine-initiated polyol having an average hydroxyl number of 640, which are available from The Dow Chemical Company. Suitable sources of dendritic polyol-based crosslinkers include BOLTORN® H20 polyhydroxylated dendritic polymer having 16 terminal hydroxyl groups and a nominal molecular weight of 1750 g/mol, BOLTORN® H2004 polyhydroxylated dendritic polymer having 6 terminal hydroxyl groups and a nominal molecular weight of 3100 g/mol, BOLTORN® H311 polyhydroxylated dendritic polymer having 23 terminal hydroxyl groups and a nominal molecular weight of 5300 g/mol, and BOLTORN® P500 polyhydroxylated dendritic polymer, which are available from Perstorp Holding AB of Perstorp, Sweden.

[0034] Again, the polyol crosslinker 48 may be used to adjust the properties of the foam object 12. For example, in certain embodiments, the polyol crosslinker 48 may be adjusted, relative to the polyol formulation 44, to an amount ranging between 0 and 20 pphp, such as between 1 and 15 pphp, or between 1 and 10 pphp. In certain embodiments, the polyol crosslinker 48 may be adjusted to between approximately 3 and 12 pphp, such as between approximately 3 and 10 pphp, between approximately 4 and 9 pphp, or between approximately 4 and 8 pphp. Though the polyol crosslinker 48 may be present in any amount, as another example, the polyol crosslinker 48 may be present in an amount between 0.05 weight percent (wt%) and 35 wt% of the polyol formulation 44, such as between approximately 1 and 15 wt%, of the total weight of the polyol formulation 44, or between approximately 3 wt% and 10 wt% of the total weight of the polyol formulation 44.

[0035] It should be noted that the use of the various components of the polyol formulation 44 may be balanced so as to provide a desired combination of hardness, weight (e.g., density), appearance, comfort, and the like, in the resulting foam object 12. An example set of ranges for components in the polyol formulation 44 is set forth in Table 1 below. Table 1- Example Polyol Formulation

Component Amount (parts per hundred polyol)

First Polyol (e.g., polyether polyol) 20-100

Second Polyol (e.g., copolymer polyol) 80-0

Water (Blowing Agent) 1-8

Amine Crosslinker 0.05-3

Catalyst 0.05-3

Surfactant 0.05-3

Additives 0-10

Polyol Crosslinker 0-20

[0036] In accordance with present embodiments, during production of the foam object 12, as the amount of the polyol crosslinker 48 is increased (e.g., while keeping the amount of polyether polyol and copolymer polyol substantially constant), the hardness of the foam object 12 is increased. Again, it should be noted that the polyol crosslinker may be provided as a stream that is separate from the polyol formulation 44, as a part of the polyol formulation 44, or a combination thereof. In certain embodiments, the amount of the polyol crosslinker 48 may be varied so as to adjust the hardness of the various sections of the foam object 12. For example, the amount of the polyol crosslinker 48 may be higher in the second and third sections 26, 28 (e.g., bolsters) than in the first section 24 (e.g., seating region) of the foam object 12. Thus, in accordance with present embodiments, the second and third sections 26, 28 may be harder than the first section 24. For example, the amount of polyol crosslinker 48 utilized in the second and third sections 26, 28 may be at least 5% more than, such as between 1 and 100 times more than, the amount of polyol crosslinker 48 utilized in the first section 24. Indeed, as a result of the increased amount of polyol crosslinker 48 in these sections, the second and third sections 26, 28 may be at least 1% harder, such as between approximately 10% and 100% harder, or between approximately 10% and 60% harder, as measured by indentation load deflection (ILD), compression load deflection (CLD), or other similar measurements.

[0037] As noted above, the isocyanate mixture 46 is reacted with the polyol formulation 44 in the mold 14 (and the polyol crosslinker 48 in embodiments where the polyol crosslinker 48 is provided as a separate stream). The isocyanate mixture 46 may include one or more different isocyanates (e.g., diisocyanate or polymeric isocyanate) compounds capable of reacting with the polyols to produce a polyurethane. Examples of such compounds include methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), or other such compounds having two or more isocyanate groups. The polymeric isocyanate compounds may also include prepolymers or polymers having an average of two or more isocyanate groups per molecule. The particular polymeric isocyanate compounds used may depend on the desired end use (e.g., the desired physical properties) of the foam object 12.

[0038] An embodiment of a method 60 for producing the foam object 12 using the polyol crosslinker 48 is illustrated as a process flow diagram in FIG. 2. The method 60 may be performed substantially automatically using an automated manufacturing system having suitably programmed control modules and various reaction vessels, molds (e.g., mold 14), measurement/metering devices, and the like. The control modules will typically include one or more computing devices each having one or more tangible, non-transitory, machine readable media collectively storing instructions executable by a processor to perform the functions described herein. In certain embodiments, the method 60 may be performed using a combination of a human operator and an automated system, where the operator may determine optimal conditions for foam production. In yet another embodiment, the method 60 may be performed entirely buy a human operator.

[0039] As illustrated, the method 60 includes providing (block 62) a polyol formulation (e.g., polyol formulation 44), a polyol crosslinker (e.g., polyol crosslinker 48), and an isocyanate mixture (e.g., isocyanate mixture 46). For example, as noted above, in one embodiment, the polyol formulation 44, polyol crosslinker 48, and isocyanate mixture 46 may be provided as separate streams to the mixing head 42 to produce the foam formulation 40. In another embodiment, the polyol formulation 44 and the crosslinker 48 may be provided as a single stream to the mixing head 42. In certain of these embodiments, the polyol crosslinker 48 may also be provided as a separate stream in addition to being provided as part of the polyol formulation 44. [0040] The amount of the polyol crosslinker 48 is then determined (block 64) based on the desired physical properties of the foam object 12. For example, the amount of polyol crosslinker 48 utilized in the foam formulation 40 (e.g., reaction mixture that produces the foam) may be determined based on a desired hardness of the foam object 12, a desired density of the foam object 12, based on the cost of the foam formulation 40, or a combination thereof. Again, as noted above, as the amount of polyol crosslinker 48 increases, the hardness of the foam object 12 may increase as well.

[0041] Once all of the components of the reaction mixture (e.g., foam formulation 40) are provided and the amounts of each determined, the components may be provided to the mold 14 to produce (block 66) the foam object 12. For example, the components of the foam formulation 40 may be injected into a closed mold, where the components begin to react. In embodiments where the mold cavity 18 is open while the foam formulation 40 is provided, the foam formulation 40 may be poured into the cavity 18. Again, it should be noted that the foam formulation 40 may be preformed (i.e., premixed) before provision to the mold cavity 18, or may be formed in the mold cavity 18 after its component streams (i.e., the polyol formulation 44, the polyol crosslinker 48, and the isocyanate mixture 46) are provided to the mold cavity 18.

[0042] As the components react, the polyurethane foam forms and rises to fill the mold cavity 18 and thereby take the shape of the mold cavity 18. For instance, to produce the foam object 12, heat may be provided to the foam formulation 40 to cause the formulation to polymerize. For example, the foam formulation 40 may reach an internal temperature of between approximately 160 and 190 °F (e.g., 170 °F). The acts according to block 66 may also include retaining the resulting foamed material within the mold cavity 18 for a period in which the foam is cured and allowed to harden. For example, the curing process may include heating the foam to between approximately 160 and 180 °F for between approximately 1 and 60 minutes. After curing, in certain embodiments, the foam object 12 may undergo one or more crushing processes (e.g., a time pressure release (TPR) process which is prior to removal from the mold 14) in which the sealing pressure of the mold 14 is reduced to allow gas to escape from the mold 14. Once the foam object 12 is produced, it may be removed from the mold cavity 18, or "demolded." The demolded object may also undergo one or more finishing steps, such as additional crushing or sanding.

[0043] Once produced in accordance with block 66, the method 60 proceeds to determining (query 68) whether the foam object 12 has a desired level of physical properties (e.g., hardness, appearance, density, tear strength). In embodiments where the foam object 12 does not meet the predetermined threshold level for the one or more desired physical properties, the method 60 progresses to adjusting (block 70) the amount of polyol crosslinker 48 provided as a part of the foam formulation 40. For example, the acts according to block 70 may cause the amount of the polyol crosslinker 48 to be increased to increase the hardness of the foam object 12, or may cause the amount of the polyol crosslinker 48 to be decreased to decrease the hardness of the foam object 12. As depicted, the method 60 then cycles back to the acts of block 64 to proceed with producing the foam object 12 in accordance with block 66. In embodiments where the foam is determined to have the desired level of physical properties, the method 60 may proceed to continue (block 72) producing the foam object 12 using the amount of polyol crosslinker 48 determined according to block 64.

[0044] The method 60 may include many other steps and processes, such as using different formulations for different sections of the foam object 12, and may also include, in certain configurations, using more than one mold for producing various sections of a foam article, such as a foam seat. For example, while FIG. 1 depicts the mold 14 has having the first, second, and third reaction zones 30, 32, 34 as being continuous with one another, in other embodiments, the first, second, and third reaction zones 30, 32, 34 may be partially or completely separate from one another and, in still further embodiments, may be in an entirely separate mold.

[0045] One embodiment of a method 80 for producing the foam object 12 using more than one reaction zone so as to produce different sections having different physical properties is depicted in FIG. 3 as a process flow diagram. It should be noted that while the acts of method 80 are presented in a certain order, that the method 80 is not limited to the particular order illustrated or order of description. For example, certain steps may occur at substantially the same time, or in another order altogether. The method 80 includes providing (block 62) the polyol formulation 44, the polyol crosslinker 48, and the isocyanate mixture 46 in the manner described above with respect to FIG. 2.

[0046] The amount of the polyol crosslinker 48 is determined (block 82) for a first reaction mixture that produces at least a first section of the foam object 12. For example, the amount of polyol crosslinker 48 may be determined based on desired physical properties of a first section of the foam object 12, such as the seating portion (e.g., a seat cushion).

[0047] Once the amount of polyol crosslinker is determined according to block 82, the method 80 proceeds to producing (block 84) a first section (e.g., first section 24) of the foam object 12 using the first reaction mixture. For example, the first section 24 may be produced so as to have a lower hardness than the other portions of the foam object, or a higher hardness than the other portions of the foam object. The acts according to block 84 may include all or a portion of the acts described above with respect to block 66 of FIG. 2. For example, the acts of block 84 may include providing the first reaction mixture to the first reaction zone (e.g., first reaction zone 30) of the mold 14, polymerizing the mixture to produce a foam, curing the foam, crushing the foam, post-processing the foam, or any combination thereof. While not illustrated, it should be appreciated that the method 80 may also include similar acts to those described above with respect to query 68 and blocks 70 and 72, where the resulting first section may be analyzed and, where appropriate, the amount of polyol crosslinker 48 may be adjusted in block 82.

[0048] The method 80 also includes determining (block 86) the amount of polyol crosslinker 48 to be used in a second reaction mixture for producing a second section (e.g., second and/or third sections 26, 28) of the foam object 12. By way of example, the amount of polyol crosslinker 48 in the second reaction mixture may be higher than the amount of polyol crosslinker 48 in the first reaction mixture when it is desirable for the second section to be harder than the first section. Alternatively, the amount of the polyol crosslinker 48 in the second reaction mixture may be lower than the amount of the polyol crosslinker 48 in the first reaction mixture when it is desirable for the first section to be harder than the second. In embodiments where the second section is harder, the amount of polyol crosslinker 48 in the second reaction mixture may be at least 1% greater, at least 10% greater, at least 50% greater, or at least 100% greater, than the amount in the first reaction mixture, such as between approximately 1 and 100 times greater, between approximately 1 and 50 times greater, between approximately 1 and 25 times greater, or between approximately 5 and 15 times greater. In certain embodiments, the hardness may be increased above by selecting the concentration of the polyol crosslinker in the second reaction mixture such that a density of the second section of the foam object 12 is between approximately 95% and 105%) of a density of the first section, such as between approximately 98%> and 102% of the density of the first section.

[0049] Once the amount of polyol crosslinker is determined according to block 86, the method 80 proceeds to producing (block 88) a second section (e.g., the second and/or third sections 26, 28) of the foam object 12 using the second reaction mixture. For example, the second section 26 and/or the third section 28 may be produced so as to have a lower hardness than the other portions of the foam object, or a higher hardness than the other portions of the foam object. The acts according to block 88 may include all or a portion of the acts described above with respect to block 66 of FIG. 2. For example, the acts of block 88 may include providing the second reaction mixture to a second reaction zone (e.g., the second and/or third reaction zones 32, 34) of the mold 14, polymerizing the mixture to produce a foam, curing the foam, crushing the foam, post-processing the foam, or any combination thereof. While not illustrated, it should be appreciated that the method 80 may also include similar acts to those described above with respect to query 68 and blocks 70 and 72, where the resulting second section may be analyzed and, where appropriate, the amount of polyol crosslinker 48 may be adjusted in block 86.

[0050] As set forth above, the polyol crosslinkers 48 used according to the present technique may affect the hardness, tear strength, and density of the foam object 12. In accordance with present embodiments, increasing the amount of the polyol crosslinker 48 in the foam formulation 44 may increase the hardness of the foam object 12 while maintaining the density of the foam object 12 at substantially the same level as would be obtained for a foam object where the polyol crosslinker 48 is not utilized. In other words, where the only difference in two foam formulations is the amount of polyol crosslinker 48, the foams produced from each may have the same density, while the foam produced using the formulation with the polyol crosslinker 48 has a greater hardness. Further, in certain embodiments, the density of the foam object 12 may, surprisingly, be reduced while increasing the hardness of the foam object 12 with the polyol crosslinker 48. For example, as discussed in the examples below, when the polyol crosslinker 48 is present in specific amounts, the density of the foam object 12 may decrease, or may be maintained within 98% or 99% of its original density, while the hardness (as measured by Indentation Load Deflection (ILD)) is increased by at least 10%>, such as between 10%> and 100%, or between 10% and 70%.

[0051] For example, in certain embodiments, providing the polyol crosslinker 48 to the foam formulation 44 in an amount between approximately 3 and 12 pphp may increase the hardness of the foam by more than 10%, while reducing the density of the foam. Provided in Table 2 below are example polyol formulations used to produce a foam object, where the formulations differ by the amount of polyol crosslinker utilized. Also provided in Table 2 are various measurements related to the strength and hardness of the foam. In particular, the Indentation Load Deflection (ILD) at 25%o and 50%> are provided, as well as push-pull measurements, density, and tear strength. All measurements were performed according to Toyota Engineering Standard TSM7100G.

Table 2 - Foam Formulation and Selected Physical Properties

Formulation 1 2 3 4 5

E833 Polyol 30.00 30.00 30.00 30.00 30.00

E850 Copolymer Polyol 70.00 70.00 70.00 70.00 70.00

V4053 Cell opener 1.00 1.00 1.00 1.00 1.00

Water Added 2.40 2.40 2.40 2.40 2.40

Total Water 2.55 2.55 2.55 2.55 2.55

DEOA 1.00 1.00 1.00 1.00 1.00

Pure DEOA 0.85 0.85 0.85 0.85 0.85

Catalyst

BLX-11 0.11 0.11 0.11 0.11 0.11

33LV 0.33 0.33 0.33 0.33 0.33

Surfactant

B8737LF2 0.60 0.60 0.60 0.60 0.60

B8724LF2 0.35 0.35 0.35 0.35 0.35

Polyol Crosslinker

V360 0.00 3.00 6.00 9.00 12.00

Total 105.79 108.79 111.79 114.79 117.79

Isocyanate

TM20 32.69 34.46 36.22 37.99 39.76

Physical Properties

Pad weight (g) 949.00 942.00 928.00 930.00 947.00

25% ILD (N) 407.70 454.64 482.54 519.70 548.74

50% ILD (N) 746.20 843.06 915.07 1017.52 1103.57

Push-pull (N) 22.00 29.40 36.30 41.50 48.80

Density (kg/m3) 51.00 50.40 49.50 49.20 49.80

Tear Strength (N/cm) 8.50 8.70 8.70 9.00 10.00 [0052] As provided in Table 2 above, the foam formulations were generated using a polyol formulation having HYPERLITE™ E833 polyether polyol (average functionality of 2.8) and HYPERLITE™ E850 styrene-acrylonitrile copolymer polyol, both available from Bayer Material Science, and Voranol® 4053 polyether polyol as a cell opener, available from The Dow Chemical Company. The foam formulations were also produced using water as a blowing agent, dietha.no 1 amine as an amine-based crosslinker, DABCO® BLX-11 amine catalyst available from Air Products and Chemicals, Inc. and 33LV DABCO® amine catalysts available from Sigma Aldrich. TEOOSTAB™ B8724LF2 and B8737LF2 silicone surfactants, available from Evonik, were also utilized. TM-20, a mixture of TDI and MDI, was utilized as the isocyanate mixture.

[0053] As also provided in Table 2, VORANOL™ 360 sucrose/glycerin-initiated polyether polyol having an average functionality of 4.5 was utilized as the polyol crosslinker in amounts ranging from 0 pphp (i.e., as a control) to 12 pphp. The physical properties noted in Table 2 are also depicted in chart form in FIGS. 4-8.

[0054] FIG. 4 is a chart 100 depicting 25% ILD (obtained according to Toyota Engineering Standard TSM7100G), which is a way of expressing the hardness of the foam, as a function of the amount of polyol crosslinker in each formulation. As shown, at 0 pphp polyol crosslinker as a control, the foam has a baseline 25% ILD of approximately 408 N. As depicted in the chart, the 25% ILD steadily increases with increasing amounts of polyol crosslinker, with the ILD increasing by approximately 15%) at 3 pphp, approximately 6%> at 6 pphp, approximately 8% at 9 pphp, and approximately 6% at 12 pphp.

[0055] FIG. 5 is a chart 110 depicting 50%> ILD (also obtained according to Toyota Engineering standard TSM7100G), which is another way of expressing the hardness of the foam, as a function of polyol crosslinker amount. As may be appreciated, the 50% ILD increases in a similar manner as set forth for the 25% ILD. As depicted in the chart 110, the 50% ILD steadily increases from a baseline of approximately 746.2 N with increasing amounts of polyol crosslinker, with the ILD increasing by approximately 13% at 3 pphp, approximately 9% at 6 pphp, approximately 11% at 9 pphp, and approximately 9% at 12 pphp. Accordingly, ILD may be considered to increase with increased amounts of polyol crosslinker.

[0056] FIG. 6 is a chart 120 depicting push-pull measurements (obtained according to Toyota Engineering standard TSM7100G), which is a measurement of foam strength, as a function of polyol crosslinker amount. As may be appreciated, the push-pull increases in a similar manner as set forth for the ILD measurements. As depicted in the chart 120, the push-pull values steadily increase from a baseline of approximately 22 N with increasing amounts of polyol crosslinker, with the push-pull increasing by approximately 34% at 3 pphp, approximately 23% at 6 pphp, approximately 14% at 9 pphp, and approximately 18% at 12 pphp. Accordingly, the strength of the foam may be considered to increase with increased amounts of polyol crosslinker.

[0057] FIG. 7 is a chart 130 depicting another measurement of the strength of the foams produced using the polyol crosslinker. In particular, the chart 130 plots tear strength (obtained according to Toyota Engineering standard TSM7100G) as a function of pphp of polyol crosslinker. As depicted, the tear strength of the foam has a baseline value of approximately 8.5 N/cm. As the levels of polyol crosslinker increase, so does the tear strength of the resulting foam - to approximately 10 N/cm at 12 pphp.

[0058] As the hardness and the strength of foams increase, it is generally expected that their weight will also increase due to the inclusion of various hardeners (e.g., fillers, increased copolymer polyol amounts) typically used for such purposes. However, when produced in accordance with the present approaches, the polyol crosslinker enables the formation of stronger and harder foams, at the same or even less weight due to reduced densities. FIG. 8 is a chart 140 depicting the density measurements of the foam produced from the formulations as a function of polyol crosslinker amount. As shown, at levels between 0 and 9 pphp, the polyol crosslinker causes the density of the foam to decrease, from a baseline of approximately 51 kg/m³ to approximately 49.2 kg/m³ at 9 pphp. At 12 pphp, the density begins to rise again, to approximately 49.8 kg/m³ - less than the baseline but higher than the foam produced at 9 pphp polyol crosslinker. It is therefore expected that at levels higher than 12 pphp, such as between approximately 13 pphp and 20 pphp, that the density will increase beyond that of the original baseline. Accordingly, the improvement and hardness and strength may be balanced with the increase in weight at higher polyol crosslinker concentrations. Therefore, in certain embodiments, the polyol crosslinker may be utilized to improve the hardness and strength of the foam while maintaining the density of the foam at or below the density of a foam article produced using no polyol crosslinker. For example, the amount may, in one embodiment, be between approximately 1 pphp and 15 pphp, such as between approximately 3 pphp and 12 pphp.

[0059] While only certain features and embodiments of the invention have been illustrated and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re- sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the invention, or those unrelated to enabling the claimed invention). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.

Claims

CLAIMS:

1. A method of producing an open cell foam article, comprising:

forming a first section of the open cell foam article using a first reaction mixture comprising:

a first polyol formulation, the first polyol formulation comprising polyether polyols, copolymer polyols, and a polyol-based crosslinker having a higher functionality than the polyether polyol and the copolymer polyol; and

an isocyanate mixture comprising a difunctional or polyfunctional isocyanate, or mixtures thereof; and

forming a second section of the open cell foam article using a second reaction mixture comprising:

a second polyol formulation, the second polyol formulation comprising the polyether polyols, the copolymer polyols, and the polyol-based crosslinker, wherein the second polyol formulation has a higher concentration of the polyol-based crosslinker than the first polyol formulation.

2. The method of claim 1, comprising selecting the concentration of the polyol-based crosslinker in the second polyol formulation such that a density of the second section of the open cell foam article is approximately equal to a density of the first section of the foam article.

3. The method of claim 2, comprising selecting the concentration of the polyol-based crosslinker in the second polyol formulation such that an Indentation Load Deflection (ILD) of the second section of the open cell foam article is greater than a ILD of the first section of the foam article.

4. The method of claim 1, comprising selecting the concentration of the polyol-based crosslinker in the second polyol formulation such that a density of the second section of the open cell foam article is between approximately 98% and 102% of a density of the first section of the foam article.

5. The method of claim 4, comprising selecting the concentration of the polyol-based crosslinker in the second polyol formulation such that a ILD of the second section of the open cell foam article is greater than a ILD of the first section of the foam article.

6. The method of claim 1, wherein the first polyol formulation, the second polyol formulation, or a combination thereof, further comprises an amine - based crosslinker.

7. The method of claim 1, wherein the first polyol formulation, the second polyol formulation, or a combination thereof, further comprises a blowing agent and a catalyst.

8. The method of claim 1, wherein a functionality of the poly ether polyol and the copolymer polyol is between approximately 1 and 4.

9. The method of claim 8, wherein a functionality of the polyol-based crosslinker is between approximately 3 and 8.

10. The method of claim 1, wherein the polyol-based crosslinker comprises a polyhydroxylated dendrimer.

11. The method of claim 1, wherein the polyol-based crosslinker comprises a sucrose-initiated, a trimethylolpropane-initiated, an ethylene diamine- initiated, a pentaerythritol-initiated, a diethylenetriamine-initiated, a sorbitol-initiated, or a glycerin-initiated polyether polyol, or any combination thereof.

12. The method of claim 1, wherein forming the first and second sections of the open cell foam article comprises providing the first reaction mixture to a first reaction zone having a first shape and the second reaction mixture to a second reaction zone having a second shape, wherein the first and second reaction zones are continuous with one another.

13. The method of claim 12, wherein the first section corresponds to a seat cushion and the second section corresponds to a seat bolster.

14. The method of claim 12, wherein providing the first reaction mixture to the first reaction zone and the second reaction mixture to the second reaction zone comprises providing the first reaction mixture to the first reaction zone, and increasing an amount of the polyol-based crosslinker in the first reaction mixture to produce the second reaction mixture.

15. The method of claim 14, wherein the polyol-based crosslinker is provided to the first reaction zone as a separate stream from the polyether polyol and the copolymer polyol.

16. The method of claim 1, wherein the polyol-based crosslinker is present in the second polyol formulation in an amount of between approximately 0.05 wt% and 20 wt % of the total weight of the second polyol formulation.

17. An open cell, foam article, comprising:

a first section produced from a first reaction mixture comprising:

a first polyol formulation, the first polyol formulation comprising a polyether polyol and a copolymer polyol; and

an isocyanate mixture comprising a difunctional isocyanate, a polyfunctional isocyanate, or a combination thereof; and

a second section continuous with the first section, wherein the second section is produced from a second reaction mixture comprising:

a second polyol formulation, the second polyol formulation comprising the polyether polyol, the copolymer polyol, and a polyol-based crosslinker having a higher functionality than the polyether polyol and the copolymer polyol, wherein the second polyol formulation has a higher concentration of the polyol-based crosslinker than the first polyol formulation.

18. The open cell, foam article of claim 17, wherein the first section is produced without using the polyol-based crosslinker.

19. The open cell, foam article of claim 17, wherein the first polyol formulation, the second polyol formulation, or a combination thereof, further comprises an amine-based crosslinker.

20. The open cell, foam article of claim 17, wherein the first polyol formulation, the second polyol formulation, or a combination thereof, further comprises a blowing agent and a catalyst.

21. The open cell, foam article of claim 17, a functionality of the polyether polyol and the copolymer polyol is between approximately 1 and 6.

22. The open cell, foam article of claim 17, wherein a functionality of the polyol-based crosslinker is between approximately 3 and 8.

23. The open cell, foam article of claim 17, wherein a functionality of the polyol-based crosslinker is between approximately 4.2 and 6.

24. The open cell, foam article of claim 17, wherein a functionality of the polyol-based crosslinker is between approximately 4.4 and 5.

25. The open cell, foam article of claim 17, wherein the polyol-based crosslinker comprises a polyhydroxylated dendrimer.

26. The open cell, foam article of claim 17, wherein the polyol-based crosslinker comprises a sucrose-initiated, a trimethylolpropane-initiated, an ethylene diamine-initiated, a pentaerythritol-initiated, a diethylenetriamine-initiated, a sorbitol- initiated, or a glycerin-initiated polyether polyol, or any combination thereof.

27. The open cell, foam article of claim 17, wherein a density of the second section of the open cell foam article is approximately equal to a density of the first section of the foam article.

28. The open cell, foam article of claim 17, wherein a density of the second section of the open cell foam article is between approximately 98% and 102% of a density of the first section of the foam article.

29. The open cell, foam article of claim 17, wherein an Indentation Load Deflection (ILD) of the second section of the open cell foam article is greater than an ILD of the first section of the foam article.

30. The open cell, foam article of claim 17, wherein the second reaction mixture comprises the difunctional isocyanate or an additional polyfunctional isocyanate.

31. The open cell, foam article of claim 30, wherein the difunctional isocyanate and the additional polyfunctional isocyanate independently comprise toluene diisocyanate (TDI), methylene diisocyanate (MDI), or a combination thereof.

32. The open cell, foam article of claim 17, wherein the first section corresponds to a seat cushion and the second section corresponds to a seat bolster.

33. The open cell, foam article of claim 17, wherein the polyol-based crosslinker is present in the second polyol formulation in an amount of between approximately 0.05 wt% and 35 wt % of the total weight of the second polyol formulation.

34. The open cell, foam article of claim 17, wherein the polyol-based crosslinker is present in the second polyol formulation in an amount of between approximately 1 wt% and 15 wt % of the total weight of the second polyol formulation.

35. The open cell, foam article of claim 17, wherein the polyol-based crosslinker is present in the second polyol formulation in an amount of between approximately 3 wt% and 10 wt % of the total weight of the second polyol formulation.

36. The open cell, foam article of claim 17, wherein the polyether polyol and the copolymer polyol are present in the second polyol formulation in a ratio of between approximately 0.1 :9.9 polyether polyol to copolymer polyol and 9.9:0.1 polyether polyol to copolymer polyol.

37. The open cell, foam article of claim 17, wherein a concentration of the copolymer polyol in the second polyol formulation is less than a concentration of the copolymer polyol in the first polyol formulation.

38. A vehicle seat produced by the method of claim 1.

39. A vehicle seat produced using the open cell, foam article of claim 17.