WO2003011947A1

WO2003011947A1 - Improved formulations for isocyanate-based polymer compositions containing hydrocarbon oils

Info

Publication number: WO2003011947A1
Application number: PCT/US2002/023951
Authority: WO
Inventors: Robert G. Sawitski, Jr.; Chin-Chang Shen; David R. Macfarland
Original assignee: Huntsman International Llc
Priority date: 2001-08-02
Filing date: 2002-07-26
Publication date: 2003-02-13

Abstract

Formulations useful for the preparation of isocyanate-based polymers. The formulations contain hydrocarbon oils of increased safety and high compatibility. The isocyanate-based formulations according to the invention are particularly useful as adhesives and for the preparation of polyurethane gels.

Description

IMPROVED FORMULATIONS FOR ISOCYANATE-BASED POLYMER COMPOSITIONS CONTAINING HYDROCARBON OILS

CROSS REFERENCE TO RELATED APPLICATIONS: This application claims priority to U.S. Provisional Applications, serial no.

60/309,575, which was filed on August 2, 2001 and serial no. 60/332,703, which was filed on November 14, 2001.

FIELD OF THE INVENTION: The invention relates to formulations for the preparation of polymers based on the chemistry of polyisocyanates. The formulations contain an aromatic hydrocarbon oil having certain specified characteristics.

BACKGROUND OF THE INVENTION: Isocyanate-based reaction systems for the preparation of polymers are often diluted with hydrocarbon oils. The hydrocarbon oils serve to modify the processing characteristics of the reaction system, such as its viscosity, or to modify the properties of the final polymeric material. Two common applications of such reaction systems include the preparation of polyurethane gels and the re-bonding of particulate flexible foam scrap. In the former application, the oil serves as a plasticizer that softens the polymer, providing a gel like consistency. In the latter application, the primaiy purpose of the oil is to reduce the viscosity of the adhesive system used in re-bonding of foam particles. In both sets of applications, the oil is necessarily used at high concentrations, typically about 5 to 50% by weight or even more relative to the weight of the total formulation (polymer precursors plus oil). In order to be effective, the oil needs to have a high degree of miscibility with the polymer and with the chemical precursors thereof (in the reactive formulation used to produce the polymer). Because it is used at a high level and remains in the polymer, the oil must be safe and environmentally benign. Finally, the oil should not adversely affect the reaction chemistry that converts the reaction system into the final polymer. Various applications of polyisocyanates, especially isocyanate prepolymers, benefit from the use of inert process oils as diluents. During the manufacture of polyurethane prepolymers, such as those used for bonding flexible polyurethane foam crumb, a process oil such as an aromatic or a naphthenic hydrocarbon oil is often included in the prepolymer formulation in amounts of about 5 to 50% by weight. The process oils have the beneficial effect of reducing the surface tension of the polyisocyanate and reducing its viscosity. Prepolymers, of the type used in flexible foam rebonding, require viscosities in the range of about 300 to about 4000 cP at 25°C. The process oils are useful for reducing the viscosity of rebond prepolymers so that they conform to this range. The viscosity of prepolymers depends upon variables such as the functionality of the polyol used, the polyol molecular weight, the functionality of the polyisocyanate, the type of polyisocyanate used, and the isocyanate value (percentage of-NCO groups by weight) of the prepolymer. The use of a process oil provides an additional mechanism for managing the viscosity of prepolymers and also for non-prepolymerized polyisocyanates. The rebonding of flexible polyurethane foam crumbs by using polyisocyanate prepolymer adhesives is a particularly important application, although not the only application where process oils have been used as diluents. The re-bonding of flexible polyurethane foam crumbs has traditionally been accomplished by mixing the crumbs with an isocyanate terminated prepolymer adhesive containing a process oil. The prepolymer is typically made from the reaction of an MDI or a TDI isocyanate with a flexible polyol. The flexible polyols are typically polyether polyols having molecular weights of between 300 and 8000, and more commonly between 1000 and 6000, on a number averaged basis. The polyols are most commonly polyether triols (having a nominal hydroxyl functionality of 3), although nominal diols have been used more recently. The flexible polyols in these prepolymers contribute essential flexibility to the adhesive bond.

The technology for making flexible polyols and derived isocyanate terminated prepolymers is well known in the art. Process oils that have been added to these polyurethane prepolymer formulations include naphthenic, paraffinic, and aromatic hydrocarbon oils. Aromatic oils have been the industry standard. The aromatic oils which have hitherto been used, however, suffer the disadvantage of being labeled as possible carcinogens by some regulatory authorities. This labeling indicates that the safety of using these aromatic oils may be questionable. These safety concerns appear to be due to the presence of a limited range of impurities in most of the aromatic oils.

Naphthenic and paraffinic oils, however, exhibit much lower natural solubilities in polyurethane prepolymers, and in monomeric polyisocyanates as well, relative to the aromatic oils. As a result, prepolymer formulations and monomeric polyisocyanates, in which naphthenic or paraffinic oils are employed as diluents tend to be unstable with respect to bulk physical separation of the oil. This is not the case with aromatic oils, however. Recently it has been found that certain compatibilizing agents can be used to increase the stability of polyisocyanate compositions that contain naphthenic oils, but the use of these compatibilizing agents adds to the complexity of the process and to the cost. Another recent technique for improving the compatibility of naphthenic oils with polyisocyanate prepolymers involves using certain diols, instead of the triols traditionally used in foam rebond applications, in making the prepolymers. Unfortunately, this has a limited range of utility, and tends to be more expensive due to the relatively higher prices of the diols used. Moreover, this latter method is obviously not helpful in situations were the polyisocyanate does not contain a prepolymer. A need therefore exits for blends of polyisocyanates with process oils that are inherently compatible, preferably miscible in all proportions, but free of the safety concerns associated with the aromatic oils that have been used in the prior art. The ideal process oil for use in blends with polyisocyanates will be fully soluble in the polyisocyanate in all proportions, in the presence or absence of prepolymers, will be nonvolatile, will not have the safety concerns associated with the prior-art aromatic oils, and will not separate from the polyisocyanate during storage. The ideal oil will be non-flammable and should be substantially free of volatile organic species (NOC's). The ideal process oil should also be substantially free of species causing offensive odors.

Soft gels derived from a polymer containing a plurality of urethane linkages (a polyurethane) and a high level of plasticizer are well known in the art. Such gels have been used as potting compositions for electrical and telecommunications equipment, as energy absorbing and cushioning materials, and in many related applications. Further examples of specific applications of such materials include shoe inserts such as arch supports, bicycle seat cushions, computer mouse pads, ergonomic elbow and wrist supports, helmet linings, specialized arm rests and seat cushions, and the like. Cushioning and ergonomic applications represent a growth area for these gel materials because these materials can be formulated to a consistency very similar to human fat. Such a consistency is ideal for supporting human body members that come into prolonged contact with an otherwise hard surface, such as the edge of a computer keyboard or the core of a bicycle seat. For similar reasons, these gels are finding a range of applications in medical applications and in items of personal protective equipment. These highly plasticized gels have viscoelastic properties well suited to impact protection. The soft gels are generally solid gels, but are sometimes foamed to a modest degree to produce microcellular soft elastomers. The polyurethane gels are often, although not always, used behind a layer of fabric or of elastomeric material. They are sometimes completely encapsulated by one or more such flexible facing (or backing) materials. Sometimes these encapsulated polyurethane gels are not solid, but instead may be flowable (albeit highly viscous) liquids. In this special situation, the encapsulating structures retain the gel in place.

The gels are typically formed from the reaction of a polyfunctional organic isocyanate with a polyfunctional isocyanate reactive material in the presence of a non- volatile inert liquid. The polyurethane component of the gel is typically crosslinked (thermoset), but the isocyanate reactive material contributes flexibility. The polyurethane component of the gel, under the most preferred circumstances, couples to the non- volatile organic liquid by secondary bonding forces, such as hydrogen bonding and Nan Der Waals interactions, in order to form a completely compatible plasticized gel in which the non- volatile liquid component(s) are bound and do not migrate or exude during use. The isocyanate reactive materials typically consist predominantly (on a weight basis) of flexible polyols known in the art. These polyols have equivalent weights greater than 500, typically about 1000 or greater, and nominal isocyanate reactive group functionalities of 2 to 4. The isocyanate reactive materials commonly used are polyether or polyester polyols. Aliphatic polyethers based on propylene oxide, sometimes in combination with ethylene oxide, are highly preferred. Nominal diols and triols are particularly preferred, and mixtures of these are sometimes used. The polyols contain predominantly primary or secondary hydroxyl groups, or combinations thereof. Typical gel formulations may also contain relatively low levels of low molecular weight chain extenders and/or crosslinkers known in the art.

Examples of typical polyisocyanates used in making polyurethane gels include both aromatic and aliphatic polyfunctional isocyanates. The isocyanates of the MDI and TDI series are very widely used.

The loading of the non- volatile inert liquid in polyurethane gels is typically quite high. It is almost always higher than 10% by weight of the total gel composition, and is typically higher than 30% by weight of the total gel composition. Plasticizer loadings of greater than 50% of the total composition are well known.

Plasticizers (typically inert, non- volatile liquids) that have been used in the past in preparing polyurethane gels include phthalate plasticizers such as DIOP, vegetable oils, mineral oils, liquid resins such as polybutene resins, other kinds of ether and ester containing liquids, mixtures of these, and the like.

The following references provide examples of prior art approaches to polyurethane gels, and of some of the known applications for said gels: US RE 33761; US 4231986; US 4168258; US 4281210; US 4375521; US RE 33392; US RE 33754; US 4533598; US 4596743; US RE 33755; US 4666968; US RE 33354; US 4705724; US 4666969; US 4705723; US 4176239; US 4171998; US 4008197; US 4355130; US RE 30321; US 3846364; and US 3869421.

One of the oldest and most serious problems encountered in formulating polyurethane gel systems with high plasticizer loadings is overcoming the tendency of the plasticizer to separate, or migrate, out of the gel onto the surface thereof. Such migration, if severe enough, degrades the gel-like properties of the material over time. It can also create problems with staining, due to the presence of excessive amounts of oily liquid on the surface of the gel. Many techniques have been used in the past to increase the compatibility of the plasticizer with the polyurethane in the gel. These techniques have included the use of special mixtures of plasticizers, such as mixtures of oils and phthalate plasticizers. The ester containing phthalate plasticizers are sometimes called "coupling agents", because they are believed to be capable of improving the compatibility of oils, such as mineral and vegetable oils, with the polyurethane component of the gel. It has been observed that certain ester containing plasticizers, particularly the popular phthalate plasticizers, can cause reduced cure rates in the reactive polyurethane portion of the gel formulation. The reasons for this retardation of cure rates is not altogether clear, but may be related to the presence of traces of acid in the ester based plasticizers. Complete elimination of all residual acidic species in ester containing plasticizers is very difficult and expensive. As a result of the retarding effect of these prior art plasticizers, higher loadings of urethane catalyst must be used. This adds to the cost of the system, and it would therefore be desirable not to have to add extra catalyst.

Petroleum based oils with a high aromatic content tend to have good compatibility in polyurethane gels and with the chemical precursors thereof (especially isocyanates). Unfortunately, these aromatic oils have serious issues regarding toxicity. To be sold in the United States such oils must typically carry a cancer suspect agent warning. As noted above, these warnings may be due to the presence of certain impurities in these oils. Inclusion of such oils into polyurethane gels is therefore problematic from a safety standpoint, especially if the gels are likely to come into contact, directly or indirectly, with people. Such is likely to be the case in many of the growth applications of polyurethane gels noted above. It should also be noted in this context that phthalate type plasticizers have come under recent scrutiny for possible toxic hazards. Therefore, it would be desirable not to use phthalate plasticizers. There is accordingly a strong need in the industry for polyurethane based gel systems that contain compatible plasticizing agents wherein said agents do not cause cure problems and do not require a cancer suspect label or other serious toxicity warnings. There is a particularly acute need for polyurethane gel systems that contain such improved plasticizing agents at very high loadings, typically greater than 30% or even greater than 50% by weight of the total gel system, with good compatibility between the polyurethane resin and the plasticizing agent(s) and good cure properties.

SUMMARY OF THE INVENTION:

The invention pertains to a reaction system for forming isocyanate-based polymers, to a process for preparing isocyanate-based polymers using the reaction system, and to isocyanate-based polymers made from the reaction system. The reaction system comprises:

A) a polyfunctional organic isocyanate, said isocyanate containing a plurality of organically bound isocyanate groups per molecule,

B) a hydrocarbon process oil having a content of aromatic species of at least 48% by weight and characterized by having an initial boiling point at 1 atmosphere pressure of at least

400°F and wherein at least 88% by weight of the oil distills between 400°F and 650°F, and

C) optionally, a polyfunctional isocyanate reactive material other than an isocyanate, said material containing at least two isocyanate reactive groups per molecule.

The hydrocarbon process oil is preferably used at a level of greater than 10% by weight of the total reaction system, more preferably greater than 20%, and most preferably greater than 30% by weight of the total reaction system. The hydrocarbon process oil is preferably used in the absence of phthalate type plasticizers, and most preferably in the absence of any aromatic group containing ether or ester containing plasticizer. Most preferably, the hydrocarbon process oil is used alone. The hydrocarbon process oil preferably remains compatible with the final isocyanate-based polymer made from the reaction system, and does not exhibit bulk migration. Preferably, the hydrocarbon process oil is a hydrocarbon containing at least 80% by weight of aromatic hydrocarbons. The invention further pertains to processes for making isocyanate-based polymers from the reaction system, and to polymers obtained therefrom.

In one preferred embodiment of the invention, the reaction system is suitable for the preparation of polyurethane gels. In another preferred embodiment of the invention, the reaction system comprises a compatible mixture of a polyfunctional isocyanate and a hydrocarbon process oil, said mixture being suitable for use as an adhesive for the re-bonding of particulate flexible polyurethane foam. The reaction systems of the invention do not require the use of extra additives to compatibilize the oil.

DETAILED DESCRIPTION OF THE INVENTION:

The inventions disclosed herein are directed towards a reaction system for forming isocyanate-based polymers, to a process for preparing isocyanate-based polymers using the reaction system, and to isocyanate-based polymers made from the reaction system. The reaction system comprises:

B) a hydrocarbon process oil having a content of aromatic species of at least 48% by weight and characterized by having an initial boiling point at 1 atmosphere pressure of at least 400°F and wherein at least 88% by weight of the oil distills between 400°F and 650°F, and

The Polyisocyanate:

Organic polyisocyanates that are useful in practicing the invention include aromatic, aliphatic, and cycloaliphatic diisocyanates, other polyisocyanates of higher functionality, and combinations of these types. The polyisocyanate species useful in the invention contain a plurality of free (unblocked) isocyanate (-NCO) groups. In addition, the polyisocyanate may comprise isocyanate (-NCO) group functional prepolymers or variants derived from any of these basic classes of organic polyisocyanates.

Aromatic polyisocyanates are highly preferred in the context of this invention. Aromatic polyisocyanates which may be used include 4,4'-diphenylmethane diisocyanate (4,4'-MDI); 2,4'-diphenylmethane diisocyanate (2,4'-MDI); higher functionality polymethylene polyphenyl polyisocyanates (such as the crude, or "polymeric", MDI products known in the art); 3,3'-dimethoxy-4,4'-bisphenylenediisocyanate; 3,3'-diphenyl-4,4'- biphenylenediisocyanate; 4,4'-biphenylenediisocyanate; 4-chloro-l,3-phenylene diisocyanate; 3,3'-dichloro-4,4'-biphenylene diisocyanate; 2,4-toluene diisocyanate (2,4- TDI); 2,6-toluene diisocyanate (2,6-TDI); 1,5-naphthalene diisocyanate; mixtures of these, and the like. MDI and TDI series isocyanates are highly preferred among the aromatic polyisocyanates, with MDI series isocyanates being particularly preferred. Suitable MDI series polyisocyanates include the MDI diisocyanates, particularly 4,4'-MDI, 2,4'-MDI, 2,2'- MDI, mixtures and isocyanate functional derivatives of these. Polymeric MDI, having about a 31.5% by weight -NCO group content and a number averaged -NCO group functionality of about 2.7, and prepolymers derived therefrom, may also be used. The polymeric MDI may be used either by itself or in combination with added MDI diisocyanate isomers. Polymeric MDI is a combination of monomeric polyisocyanates which includes 4,4'-MDI, lesser amounts of 2,4'-MDI, traces of 2,2'-MDI, and a mixture of tri and higher functionality polymethylene polyphenyl polyisocyanate oligomers. The preferred polymeric MDI has a number averaged isocyanate functionality of 2.7, due to the presence of the mixed higher functionality polymethylene polyphenyl polyisocyanate monomer species. Polymeric MDI is usually prepared by phosgenation of mixed aromatic amines obtained from the condensation of aniline with formaldehyde. The MDI series diisocyanates are typically obtained from crude polymeric MDI by distillation or crystallization. The preparation of polymeric MDI and MDI diisocyanates is well known in the art. It is also within the scope of the invention to use blends of polymeric MDI with additional amounts of diphenylmethane diisocyanates, particularly 4,4'-MDI and/or 2,4'-MDI. These isocyanate blends will have number averaged isocyanate functionalities of greater than 2.0 to less than 2.7, depending upon the ratio of the diphenylmethane diisocyanates to the polymethylene polyphenyl polyisocyanates present. Aliphatic isocyanates that may be employed include, but are not limited to, ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 2,4,4- tri-methyl-l,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, mixtures of these, and the like. Cycloaliphatic isocyanates that may be employed include, but are not limited to, cyclohexane- 1 ,4-diisocyanate, cyclobutane- 1 ,3 -diisocyanate, cyclohexane- 1 ,3 -diisocyanate, l-isocyanato-2-isocyanatomethyl cyclopentane, l-isocyanato-3,3,5-trimethyl-5- isocyanatomethyl cyclohexane (isophorone diisocyanate, or lPDI), 2,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, mixtures of these, and the like. In some embodiments of the invention, the polyisocyanate composition may comprise one or more isocyanate functional prepolymers. A wide range of isocyanate functional prepolymers and methods for their preparation are known in the art. When prepolymers are used at all, a particularly preferred class of isocyanate functional prepolymers are derived from flexible polyols or mixtures of flexible polyols. The use of these flexible polyol prepolymers is particularly preferred in flexible foam re-bond adhesive applications.

Non-limiting examples of specific polyisocyanate products suitable for use in the reaction systems of the invention include RUBINATE® M isocyanate and SUPRASEC® 9500 isocyanate, both of which are commercially available from Huntsman International

LLC. RUBINATE M isocyanate is a polymeric MDI product having a number averaged -

NCO group functionality of 2.7 and a concentration of -NCO groups of 31.5% by weight.

SUPRASEC 9500 isocyanate comprises prepolymers of flexible polyols in an MDI base polyisocyanate composition. SUPRASEC 9500 isocyanate has a number averaged -NCO group functionality of greater than 2 but less than 2.1 and a concentration of -NCO groups of

8% by weight. Blends of SUPRASEC 9500 isocyanate and RUBINATE M isocyanate represent a particularly preferred class of polyisocyanate compositions suitable for use in the reaction systems of the invention.

The polyisocyanate component overall preferably has a number averaged functionality in the range of from 2.0 to 3.0, more preferably from 2.05 to 2.75. In foam re-bond applications, a higher functionality polyisocyanate is generally used, typically in the range of from above 2.4 up to about 2.75.

The terms "base isocyanate" or "base polyisocyanate" may be used occasionally in this disclosure to denote the isocyanate functional precursor to a prepolymer. The "base isocyanate (polyisocyanate)" in this context is understood to refer to monomeric polyisocyanate, or a mixture of different monomeric polyisocyanates, in the absence of process oils, other plasticizers, other diluents, or prepolymer species.

The term "polyisocyanate" as used throughout this specification is to be understood to encompass diisocyanates as well as isocyanate species that are higher than difunctional, and any mixtures of these.

The Process Oil:

The process oil suitable for use in the invention may be any hydrocarbon oil that has an initial boiling point greater than 300°F at 1 atmosphere pressure (defined as 760 mm pressure) and that does not require a carcinogen or a suspect carcinogen label for sales in the United States. The process oil is preferably an oil wherein at least 48% by weight, preferably at least 50% by weight, of its constituents are aromatic compounds. More preferably the oil contains at least 80% by weight, still more preferably at least 90% by weight, and even more preferably at least 95% by weight of aromatic compounds. Most preferably, the process oil contains 97 to 100% by weight of aromatic compounds. It is additionally preferred that the molar concentration, expressed in mole percent of the process oil, of aromatic compounds in the process oil is greater than 80%, more preferably greater than 90%, and most preferably greater than 95%. The preferred process oil is further more preferably a high boiling point oil with an initial boiling point of greater than 350°F at 1 atmosphere pressure, still more preferably an initial boiling point of 400°F or greater, and even more preferably an initial boiling point of 450°F or greater at 1 atmosphere pressure. Preferably, the oil contains less than 15% by weight of species considered volatile organic compounds (NOC's) according to EPA Method 24 [using a 3 ml sample run, for 1 hr at 230°F (110°C) in a forced air oven]. More preferably the oil contains less than 12% by weight, still more preferably less than 11% by weight, and even more preferably less than 10% by weight of species considered NOC's (according to the method defined above). More desirably still, the oil contains less than 5% by weight of species considered volatile organic compounds (VOC's), still more desirably less than 3% by weight of NOC's, even more desirably less than 2% by weight of NOC's, and ideally 1% by weight or less of NOC's (according to the method defined above). Although not absolutely essential to the invention, it is highly desirable that the process oil be miscible with the base polyisocyanate up to at least 25% by weight at 25°C relative to the weight of the final blend, more preferably up to at least 30% by weight, still more preferably up to 40% by weight, even more preferably up to at least 50% by weight, relative to the final blend, and most preferably is miscible with the base isocyanate in all proportions at 25°C. By "miscible" it is meant that the oil is freely soluble in the isocyanate without the need to use a compatibilizing agent and the blend does not separate on standing at 25°C without agitation for at least 30 days, preferably at least 60 days, more preferably at least 180 days, still more preferably 365 days or more. Most preferably the isocyanate + oil blend is permanently non-separating at 25°C. It is also preferable that the oil be compatible with the isocyanate reactive component of the reaction system, at similar proportions, and under similar conditions, as noted above for the polyisocyanate. Ideally, the oil is soluble in both components. The more preferred process oils suitable for use in the blends of the invention have a distillation range at 1 atmosphere pressure of from 400 to 650°F, still more preferably between 500 and 650°F, even more preferably from 525 to 625°F, and most preferably from 550 to 620°F, wherein the distillation range is as determined by ASTM D-850 (preferably according to version-93 of ASTM D-850, known as ASTM D-850-93), and the lower end of the distillation range is the initial boiling point (or IBP). Preferably, at least 88% of the oil by weight boils within this distillation range. More preferably, at least 89% by weight, still more preferably at least 95% by weight, and most preferably at least 98% by weight of the oil boils within this distillation range.

The more preferred process oils are substantially free of materials boiling above 625 °F, and more preferably are substantially free of materials boiling above 620°F, at 1 atmosphere pressure. By "substantially free" it is meant that the oil contains less than 10% by weight of said higher boiling materials, preferably less than or equal to 5%, more preferably less than 3% still more preferably 1% or less, even more preferably less than 0.5%, and most preferably less than 0.25% by weight of said higher boiling materials. The preferred hydrocarbon oils according to the invention do not cause retardation of curing of the urethane system, unlike certain important prior art plasticizers such as the phthalate plasticizers.

The preferred process oils suitable for use in the invention are not listed as carcinogenic or as suspect carcinogens according to OSHA, NTP, IARC, or California Proposition 65. The commercial oils preferably do not require a carcinogen or a suspect carcinogen label for sale in the United States. An example of a particularly preferred commercial aromatic process oil that meets these requirements (as of August- 1-2000) is NYCEL U-1500 oil. The VYCEL U-1500 oil is commercially available from Crowley Chemical Co. It has very high miscibility with MDI type polyisocyanates and prepolymers thereof. It is generally considered to be substantially free of species having offensive odors. The initial boiling point (IBP) of NYCEL U-1500 oil is 550°F at 1 atmosphere pressure, according to ASTM D-850. The flash point of NYCEL U-1500 oil is 275°F (COC; according to ASTM D-92), and 300°F (TOC; according to ASTM D-1310). Due to its high flash point, this oil is not considered flammable. The viscosity of NYCEL U-1500 oil is 13 cps at room temperature. The boiling range of NYCEL U-1500 oil is from 550°F (initial boiling point) and extends up to 620°F, according to ASTM D-850.

The process oil suitable for use in the invention preferably has a viscosity (at 25°C) which is less than the viscosity of the base polyisocyanate (also measured at 25°C). The viscosity of a blend of the base polyisocyanate with the process oil is preferably lower than the viscosity of the base polyisocyanate itself (compared at 25°C).

The process oil is a hydrocarbon oil and is substantially free of compounds that are not hydrocarbons. By "hydrocarbon" is meant a compound that contains only the elements carbon and hydrogen. By "substantially free" in this context it is meant that the process oil contains less than 20% by weight of non-hydrocarbon compounds, preferably less than 15% by weight, more preferably less than 10% by weight, still more preferably less than 5% by weight, most preferably less than 2% by weight, and ideally less than 1% by weight of non- hydrocarbon compounds.

The preferred process oils of the invention may optionally be used as diluents for monomeric polyisocyanates and/or isocyanate terminated prepolymers. Alternatively, the oil may be mixed with the optional separate isocyanate-reactive component, if there is one. Those skilled in the art will recognize an infinite number of intermediate possibilities, in which the oil is distributed between both of the reactive components of such a two- component reaction system. Blends may be made from polyisocyanate compositions comprising isocyanate terminated prepolymers. The preferred isocyanate terminated prepolymers, when these are used, are those derived from flexible polyether polyols (as described below).

Methods for producing aromatic process oils having reduced content of carcinogenic or potentially carcinogenic species are known in the art, but there does not appear to be any disclosure of the use of such oils in adhesive formulations or polyurethane gel formulations according to the instant invention. References to methods for obtaining aromatic oils having reduced concentrations of carcinogenic or suspectedly carcinogenic materials include: European Patent No. EP0839891; and US Pat. Nos. 5034119, 5488193, and 5178747.

The Optional Isocyanate-Reactive Component:

The optional isocyanate-reactive component is a non-isocyanate group containing polyfunctional composition that is capable of forming a polymer by reaction with polyfunctional isocyanates under the conditions employed in the processing of the reaction system of the invention. Any suitable polyfunctional isocyanate reactive compound or mixture of such compounds may be used as the optional isocyanate-reactive component in this invention, provided that said compound or mixture of compounds is capable of reacting with the said polyisocyanate to form a polymer. The said polymer should contain a plurality of urethane groups, but the term "polyurethane" is used loosely to broadly encompass true polyurethanes as well as other polymers prepared from the reaction of a polyisocyanate with a polyfunctional isocyanate reactive material. Other polymers in this broad category include the polyureas. The polymer may be linear, but is preferred to be crosslinked (thermoset) and solid (gelled).

Examples of polyfunctional isocyanate reactive species that may be used include water, polyols, polyamines, aminoalcohols, polycarboxylic acids, mixtures of these, and the like. Polyfunctional isocyanate-reactive species containing only isocyanate-reactive functional groups selected from the group consisting of primary alcohols, secondary alcohols, primary amines, secondary amines, or combinations of these groups are preferred. Water, in the form of ambient moisture, moisture applied to the bonding substrate, and/or steam, is a preferred isocyanate reactive component used in the re-bonding of flexible foam crumbs.

A separate organic polyfunctional isocyanate-reactive component is more commonly encountered in polyurethane gel applications, although they may also be used in adhesive systems. Aliphatic alcohol groups are more preferred than aromatic alcohol groups. Among the amines, organic amines are preferred. Organic aliphatic polyols are the most preferred isocyanate reactive species in making polyurethane gels. Water is less preferred in gel applications because it tends to cause foaming. Although foams and microcellular materials are within the scope of the invention, solid gels are more preferred. Amines are generally less preferred because they often tend to react to rapidly. Mixtures of amines with polyols may however be used more conveniently. Organic flexible polyols are the most preferred category of polyols for use in the reaction systems of the invention.

Organic flexible polyol compositions suitable for use in the invention include polyether, polyester, and amine terminated polyols. Useful flexible polyols have a molecular weight of about 300 to about 10,000, preferably 500 to about 8000, more preferably 1000 to about 6000, and a nominal isocyanate reactive group functionality of greater than 1.0 to about 6.0, preferably about 2.0 to about 4.0. Polyether and polyester flexible polyols that may be used preferably include primary and/or secondary hydroxyl groups.

All functionalities, molecular weights, and equivalent weights described herein with respect to polymeric materials are "number average". All functionalities, molecular weights, and equivalent weights described herein with respect to pure compounds are "absolute". The term "nominal functionality" is occasionally used to denote the expected functionality of a polyol based upon the known functionalities of the monomeric species used in its manufacture. In the manufacture of polyoxyalkylene polyether polyols, for example, the nominal functionality of the polyol is the functionality of the initiator. Nominal functionality ignores side reactions, which may sometimes occur during the manufacture of polyols and may cause the number average functionality of the polyol to differ from the expected value. Suitable polyether polyols which can be employed in preparing the preferred prepolymers for use in the invention include those which are prepared by reacting alkylene oxides, halogen substituted or aromatic substituted alkylene oxides, or mixtures of these with an active hydrogen-containing initiator compound. Suitable oxides include, for example, ethylene oxide, propylene oxide, 1,2-butylene oxide, styrene oxide, epichlorohydrin, epibromohydrin, mixtures of these and the like. Ethylene oxide, propylene oxide, and combinations of these oxides, are particularly preferred. Suitable initiator compounds include water, ethylene glycol, propylene glycol, butanediol, hexanediol, glycerine, trimethylolpropane, trimethylol ethane, pentaerytliritol, hexanetriol, sorbitol, sucrose, hydroquinone, resorcinol, catechol, bisphenols, novolac resins, phosphoric acid, mixtures of these, and the like.

Suitable initiators further include, for example, ammonia, ethylenediamine, diaminopropanes, diaminohexanes, diaminobutanes, diaminopentanes, diaminohexanes, diethylenetriamine, triethyleneteframine, tetraethylenepentamine, pentamethylenehexamine, ethanolamine, aminoethylethanolamine, aniline, 2,4-toluenediamine, 2,6-toluenediamine, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 1,3-phenylenediamine, 1,4- phenylenediamine, naphthylene-l,5-diamine, triphenylmethane-4,4'-4"-triamine, 4,4'-di- (methylamino)-diphenylmethane, l,3-diethyl-2,4-diaminobenzene, 2,4-diminomesitylene, 1- methyl-3,5-diethyl-2,4-diaminobenzene, l-methyl-3,5-diethyl-2,6-diaminobenzene, 1,3,5- triethyl-2,6-diaminobenzene, 3,5,3',5'-tetraethyl-4,4'-diamino-diphenylmethane, and amine aldehyde condensation products such as the polyphenylpolymethylene polyamines produced from aniline and formaldehyde, and mixtures thereof.

Polyester polyols suitable for use in the invention include, for example, those prepared by reacting a polycarboxylic acid or anhydride with a polyhydric alcohol. The polycarboxylic acids may be aliphatic, cycloaliphatic, aromatic, and/or heterocyclic and may optionally be substituted (e.g., with halogen atoms) and/or unsaturated. Examples of suitable carboxylic acids and anhydrides include succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylene tetrahydrophthalic anhydride, glutaric anhydride, maleic anhydride, maleic acid, fumaric acid, dimeric and trimeric fatty acids such as those of oleic acid, which may be in admixture with monomeric fatty acids. Simple esters of polycarboxylic acids may also be used as starting materials for polyester polyols, such as terephthalic acid dimethyl ester, terephthalic acid bisglycol ester, adipic acid diethyl ester, and mixtures of these.

Preferably, aliphatic polyether nominal diols or triols or aliphatic polyester nominal diols or triols that have a molecular weight of about 2000 to about 6000 are used. Blends of these polyols may also be employed. Polyether polyols are more preferred than polyesters. The most preferred polyether polyols are based on propylene oxide, optionally in combination with minor amounts of ethylene oxide. Non- limiting examples of these most preferred types of polyether polyols include ARCOL 3022 polyol, which is a nominal triol available commercially from Lyondell Chemical Corporation; NORANOL 3512 polyol, which is available from the Dow Chemical Company; JEFFOL® G-31-28 polyol, which is a nominal triol available from Huntsman Petrochemical Corporation; JEFFOL PPG-3709 polyol, which is a nominal diol also available from Huntsman Petrochemical Corporation; and mixtures of these polyether polyols. Blends of JEFFOL G-31-28 polyol and/or JEFFOL PPG-3709 polyol with minor amounts by weight, relative to the combined weight of the flexible polyols, of dipropylene glycol (DPG) are particularly preferred isocyanate reactive compositions suitable for use in the reaction systems of the invention.

Non-limiting examples of amine terminated polyols which may be used in the invention include the JEFF AMINE® amine terminated polyether polyols from Huntsman Petrochemical Corporation. These amine functional resins, when used, are preferably used in combination with ordinary (non-aminated) polyols, in order to moderate the very fast reactivity of the amine groups present.

Non-limiting examples of optional chain extenders and crosslinkers that may be used, as minor components by weight, in admixture with said preferred flexible polyols include ethylene glycol, propylene glycol, dipropylene glycol, fripropylene glycol, diethylene glycol, triethylene glycol, N-methyl diethanolamine, polyether nominal diols or triols having hydroxyl equivalent weights of less than about 250 and containing predominantly primary or secondary -OH groups, diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, alkoxylates of ethylene diamine or diethylene triamine having -OH equivalent weights of less than about 250 and containing predominantly primary or secondary -OH groups, alkoxylates of aniline having -OH equivalent weights of less than about 250 and containing predominantly primary or secondary -OH groups, 1,4-butanediol, 1,3- butanediol, 1,3-propanediol, 1,6-hexanediol, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, mixtures of these, and the like. The chain extenders and crosslinkers preferably have molecular weights lower than those of flexible polyols, and generally less than 500, preferably less than 250. The nominal isocyanate reactive group functionalities of species used as chain extenders or crosslinkers generally range from 2 to about 6, but more preferably 2 to 4, and most preferably 2 to 3. Chain extenders are usually difunctional species and crosslinkers have functionalities greater than 2. Higher levels of these types of low molecular weight species will produce harder, stiffer, gels. Softer gels are obtained when such species are used at low levels or not at all.

The optional isocyanate reactive component overall preferably has a number averaged functionality in the range of from about 2 to 3, more preferably from 2.05 to 2.7. When a separate organic polyfunctional isocyanate reactive component is used in the preparation of polyurethane gels, as is commonly the case, the ratio of isocyanate group equivalents to isocyanate-reactive-group equivalents in the total reaction system is preferably in the range of from 0.6 to less than 1.5. This ratio is known in the art as the Index and is sometimes multiplied by 100 and expressed as a percent. A more preferred range of Index values for two-component reactively processed polyurethane gel formulations is from 0.7 to 1.3.

The isocyanate-reactive component may optionally also contain monofunctional organic isocyanate-reactive species. These species, when present, are also considered in the calculation of the Index of the formulation. Monofunctional polyether alcohols are sometimes used, in combination with polyols, in forming polyurethane gels.

It is within the scope of the invention to use mixtures of polyols and/or mixtures of polyisocyanates in making the polyisocyanate-based reaction systems according to the invention. Likewise, mixtures of process oils can be used, provided that the resulting mixture conforms to the restrictions on the process oil described above. When a combination of process oils is used it is preferable that the individual components of the combination should each individually meet the restrictions on the process oil noted above.

Adhesive Applications:

A particularly preferred application of the polyisocyanate-based reaction systems according to the invention is adhesives. The adhesives may be used for a wide range of purposes, such as the bonding of wood, cellulosic, or lignocellulosic materials, the rebonding of rubber granules into mats, the bonding of organic or mineral fibers into mats or pre-forms, and similar applications. Most preferably, the adhesives based on the formulations of the invention are used for the rebonding of flexible foam crumbs. In this preferred application, the formulation should preferably comprise a miscible blend of a polyisocyanate and the process oil, without any separate isocyanate-reactive component (other than water, as described below). The polyisocyanate composition may be any of the types of polyisocyanates described above. However, in particularly preferred adhesives embodiments the polyisocyanate composition comprises an isocyanate teraiinated prepolymer derived from the reaction of a flexible polyol with a base polyisocyanate. In this important application area, the polyisocyanate + oil blend is mixed with the flexible foam crumbs and the resulting mass is then compressed by use of a pressing means shortly thereafter, usually within about 15 minutes of mixing. Curing of the adhesive usually coincides with pressing and is facilitated by moisture on the crumbs or in the ambient air. Curing of the adhesive may be further facilitated by the injection of moisture or steam during the pressing operation, or through the use of catalysts, of a combination thereof. The pressed and cured mass of re- bonded foam crumbs may then be cut into desired shapes for use. Usually, the cured re- bonded foam is cut into sheets for use as carpet backing. In this application, the absence of carcinogenicity concerns, with regard to the process oil used in the adhesive, is understandably a very significant advantage of the instant invention. The improved polyisocyanate + process oil blends according to this embodiment of the invention do not require the use of compatibilizing additives to increase the stability of the blends with respect to separation of the oil. The inventive polyisocyanate + oil blends exhibit sufficient stability on their own. Nevertheless, it is within the scope of the invention to use any additives known in the art in conjunction with these blends. Suitable optional additives include, but are not limited to, known catalysts for the reaction of isocyanate groups with moisture, known catalysts for the trimerization of isocyanate groups, known catalysts for the conversion of isocyanate groups into carbodiimide groups, known catalysts for the formation of urethane groups, fillers, dyes, surfactants, fire retardants, smoke suppressants, fragrances, biocides, pigments, antistatic agents, combinations of these, and like additives known in the art.

Preferably, the optional additives, if used, should be stable in the presence of isocyanate groups during the preparation and storage of the inventive blends. The additives should not cause unwanted self-reactions of the isocyanate groups present, until such time as the blend is intended to be cured.

Catalysts are an especially preferred class of optional additives. Preferred groups of catalysts are organic tertiary amines and/or organometallic compounds that can be mixed with the isocyanate blends and stored for at least a short period of time (e.g., at least 5 minutes, up to several days or preferably longer). Preferred tertiary amines known in the art and suitable for this purpose include, but are not limited to, dimorpholino diethyl ether (DMDEE) and bis-2-(N,N-dimethylamino)-diethyl ether. Suitable loadings for such optional tertiary amine catalysts in the blends according to this embodiment of the invention are from 0.001 to about 5% by weight of the final blend, preferably from 0.005% to about 2%, more preferably from 0.01% to about 1.5%, still more preferably from 0.01% to about 1%, even more preferably from 0.02% to 0.5%, and most preferably from 0.03% to 0.3% by weight based on the weight of the final blend (including the catalyst and any other optional additives). Organometallic catalysts suitable for use as the optional catalyst additives in the blends according to this embodiment of the invention include, but are not limited to, isocyanate soluble organic complexes of iron or titanium. These complexes of iron or titanium include, for example, compounds based on acetoacetate complexes wherein the acetoacetate may optionally be used in excess. Suitable loadings for such optional organometallic catalysts in the blends of the invention are from 0.001 to about 5% by weight of the final blend, preferably from 0.005% to about 2%, more preferably from 0.01% to about 1.5%, still more preferably from 0.01% to about 1%, even more preferably from 0.015% to 0.5%, and most preferably from 0.025% to 0.3% by weight based on the weight of the final polyisocyanate + oil blend (including the catalyst and any other optional additives). Combinations of tertiary amine catalysts and organometallic catalysts may be used, if desired. Examples of suitable optional fire retardants include liquid organic phosphonates and phosphates, such as, for example, trischloroisopropylphosphate (TCPP). Other examples of suitable fire retardants include solid fillers such as alumina trihydrate, melamine, antimony oxides, and the like. Other organic fire retardants include brominated and/or chlorinated aromatic compounds. Isocyanate soluble fire retardants are more preferred in this embodiment. The loading of fire retardant may be quite high. It may in fact be 100% by weight or more relative to the combined weight of the polyisocyanate + process oil. But lower loadings of fire retardant are generally preferred, preferably from about 5% to about 50%, more preferably from about 10% to about 25% by weight relative to the combined weight of the polyisocyanate and the process oil. Mixtures of two or more different types of fire retardant additives may be used, if desired.

Examples of suitable optional surfactants, which are sometimes used to improve the flow and wetting properties of the preferred isocyanate + oil blends, include ethoxylated phenols, polysiloxane polyoxyalkylene copolymers, mixtures of these, and the like. Surfactants, when used, are normally employed at about 0.1 to about 5% by weight of the blend, more preferably from about 0.2 to 2% by weight, and still more preferably from about 0.25 to about 1.5% by weight relative to the combined weight of the polyisocyanate plus the process oil. The preferred polyisocyanate + oil blends according to this embodiment of the invention are most preferably liquids at 25°C and are stable with respect to solids formation for at least 30 days, more preferably for at least 60 days, and most preferably for 180 days or longer at 25°C, when stored under dry conditions. The blends according to the invention preferably have viscosities in the range of from about 15 cps to about 10,000 cps at 25 °C, more preferably from 25 cps to about 5000 cps, still more preferably from about 40 cps to about 4000 cps, and most preferably from 50 cps to 2000 cps at 25°C. The viscosity of the blend at 25°C preferably should not change by more than 25%, more preferably by not more than 15%, and most preferably by not more than 5% between the time it is manufactured and the time it is used.

It is preferred that the weight percentage of the process oil in the blends according to this (adhesives) embodiment of the invention be 5% or greater, more preferably 10% or greater, still more preferably 15% or greater, even more preferably 20% or greater, most preferably from about 21% to about 50%, and ideally from 21% to 40%. These preferred oil concentration ranges also apply to polyisocyanate + oil blends that do not contain prepolymers.

It is most preferred that the process oil be fully miscible with the polyisocyanate (or the polyisocyanate blend, and/or prepolymer) in all proportions and permanently stable with respect to separation, over the entire temperature range which the final blend composition is likely to experience during its preparation, storage, and ultimate use.

Polyurethane Prepolymer Manufacture:

In the more preferred embodiments of the adhesives applications of the reaction systems of the invention, as described above, it is desirable to use a polyisocyanate composition which comprises an isocyanate terminated prepolymer of a flexible polyol.

Prepolymers may, of course, optionally be used in other applications of the invention as well. These prepolymers are made from the reaction of a monomeric (base) polyisocyanate and an isocyanate reactive material such as a polyol. Flexible polyols are most preferred for this purpose. The range of flexible polyols that may be used in making the prepolymers are the same as described above (under the description of the optional isocyanate-reactive component). The only added consideration here is that the type of polyol selected should be of a sort which will form a stable prepolymer, and not promote self-reaction of the isocyanate groups in the adhesive formulation prior to use thereof. The selection of appropriate polyols for this purpose will be appreciated by those skilled in the art. When prepolymers are used, the polyisocyanate and isocyanate reactive material may be reacted within a wide stoichiometric range to produce prepolymers containing isocyanate groups. The base polyisocyanate is always used in stoichiometric excess, so that isocyanate terminated prepolymer species are obtained. During the manufacture of the optional prepolymers, the process oil according to the invention can be added to the prepolymer formulation in amounts of about 5% to about 50% based on the weight of the final prepolymer formulation. Preferably, the final prepolymer formulation has greater than 20% up to about 40% by weight of process oil, relative to the total weight of the final blended adhesive formulation [including the prepolymer itself, the process oil, and any remaining monomeric polyisocyanate].

The order in which the ingredients of the final preferred adhesive blend comprising the said isocyanate terminated prepolymer (ie. the organic monomeric polyisocyanate, the flexible polyol, and the process oil) are combined is not particularly important. The order of addition of ingredients may be adjusted to suit the available processing equipment used to make the final preferred blend comprising the said prepolymer. For example; the process oil may be, if desired, combined with the polyol or with the monomeric polyisocyanate before the prepolymer reaction is performed. Alternatively, the reaction of the monomeric polyisocyanate and the polyol to form the prepolymer may be completed first, followed by introduction of the process oil. Other suitable variations will be apparent to those skilled in the art.

Manufacture of Polyurethane Gels:

The preparation of polyurethane gels is another important end-use application of the reaction systems according to the invention, although there are potentially many other end applications that are possible within the broader scope of the invention. In the preparation of gels, it is much more preferable to use a two (or more) component reaction system comprising the polyisocyanate component and a separate organic isocyanate-reactive component. Polymerization is initiated by mixing of these organic components. Mixing activated gel formulations having just two components are most preferred. It is within the scope of the invention to use a polyisocyanate component that comprises a prepolymer, although it is certainly not essential to use prepolymers. The use of prepolymers is less important in the manufacture of gels, when the reaction system comprises a separate organic isocyanate-reactive component (as is most commonly the case). The polyisocyanate component, the isocyanate reactive component, and the process oil are combined under conditions that provide for the reaction of the polyisocyanate and the isocyanate reactive ingredients to form a polyurethane. The polyurethane is broadly defined, as noted previously, to encompass related polymers such as, but not limited to, polyureas and polyurethaneureas. The preferred types of polymers in the context of this application of the invention include polyurethanes (narrowly defined), polyureas, and polyurethanureas.

The polyisocyanate and the isocyanate reactive ingredients may be combined by any suitable means known in the art, and under any known conditions for forming these types of polymers. The polymers are preferred to contain some covalent crosslinking. As such, at least one of the polymer foπning reactants will, in most situations, have a functionality of greater than 2. Sometimes several of the reactive ingredients are of functionality greater than 2. The remaining ingredients are preferably at least nominally difunctional, although it is within the scope of the invention to incorporate monofunctional reactive ingredients under the condition that the system forms a gel. The polyisocyanate may be a mixture of polyisocyanate species, optionally comprising isocyanate terminated prepolymers. Likewise, the isocyanate reactive component may be a mixture of isocyanate reactive species. The process oil may be a blend of different oils, provided that the oil blend, and preferably all the oil components used to make the said blend, satisfies the constraints on the process oil noted above. The process oil may be added to the polyisocyanate, added to the separate isocyanate- reactive component, added to the reaction system as a third stream during processing, or any combination thereof. The reaction system is most preferably processed into a gel as a two stream mixing activated system. However, it is within the scope of the invention, albeit less preferred, to process as a single component system (wherein atmospheric moisture is an isocyanate reactive component, which cures the gel). In this one component mode, the polyisocyanate is preferably a prepolymer containing polyisocyanate having a relatively low free -NCO content by weight. In the one component mode, the free -NCO content of the polyisocyanate component is preferably below 15% by weight, more preferably below 12% by weight, and most preferably below 10% by weight (as measured in the absence of the process oil and any optional additives). The prepolymer isocyanate in this mode is formed by reaction of organic isocyanate reactive species with an excess of a base polyisocyanate.

It is also within the scope of the invention to prepare the gels by using three or more separate reactive components and combining them all at the point of processing, as a multicomponent mixing activated system. The compositions of the individual reactive streams in this multicomponent mode of processing are not particularly important, provided that the system overall fits the compositional limitations described above, and the system can be processed into a gel.

The viscosities of the individual liquid components (regardless of their number or chemical compositions), which are ultimately mixed together to form a reaction mixture in the gel forming process, should be low enough to promote adequate mixing thereof Typically all of these liquid components should be less than 10,000 cps viscosity at the temperature at which they are mixed. Preferably they are less than 10,000 cps at 25°C. More preferably they are less than 5000 cps at 25°C. The liquid precursors to the gels may be mixed by hand, by machine, or by any suitable combination thereof which provides for adequate mixing.

The gels produced from the reaction system of the invention may optionally be expanded by including either chemical or physical blowing agents, or combinations thereof, into the reaction system. However, full density (non-expanded) gels are preferred. The extent of expansion (blowing), when used at all, is preferably minimal.

The level of the process oil in the final gel composition is preferably from greater than 10% to about 80% by weight of the final gel composition, but is more preferably in the range of from greater than 20% to 75% by weight, more preferably still from 30% to 70%, and most preferably from greater than 30% to less than 60% by weight of the total gel composition. The oil should remain compatible with the gel under the conditions of use thereof, and should not migrate to the surface of the gel. It has unexpectedly been found that the oils according to the invention have excellent compatibility with the polyurethane component of the gel, even at very high loadings, even in the preferred mode wherein the oils according to the invention are the sole plasticizers present in the gel composition. Although it is within the scope of the invention to use other kinds of plasticizers, such as ester or ether containing plasticizers, in combination with the oils according to the invention, it is preferred that the collective weight of all the optional additional plasticizers in the reaction system be less than the weight of the process oil according to the invention. More preferably the collective weight of all optional additional plasticizers will be less than 50% by weight of the process oil according to the invention, still more preferably less than 25% by weight, even more preferably less than 10% by weight, and most preferably less than 5%.

The ratio of isocyanate (-NCO) groups to isocyanate-reactive groups in misapplication of the reaction system according to the invention is from greater than 0.6 and less than 1.5, but is more preferably in the range of from 0.7 to 1.3, still more preferably in the range of from 0.8 to 1.2, and most preferably in the range of from 0.9 to 1.1.

The polyisocyanate and the isocyanate reactive components of the reaction system of the invention are preferably both fully liquid at 25°C, and free of solids. However, it would be within the scope of the invention to use one or more components that are solid at 25 °C or that contain solids in dispersed form, provided that these can be processed into gels. The oil is preferably a liquid at 25°C. However it would be within the scope of the invention to use oils which are solid at 25°C, provided that these can be dissolved in at least one of the reactive components and provided that it makes a flexible (soft) gel material. It is within the scope of this embodiment of the invention, and is sometimes preferred, to use other additives in the reaction systems of the invention. Suitable optional additives include, but are not limited to, known catalysts for the reaction of isocyanate groups with active hydrogen groups, known catalysts for the trimerization of isocyanate groups, known catalysts for the conversion of isocyanate groups into carbodiimide groups, known catalysts for the formation of urethane groups, fillers, dyes, surfactants, fire retardants, smoke suppressants, fragrances, biocides, pigments, antistatic agents, combinations of these, and like additives known in the art.

Catalysts are an especially preferred class of optional additives. Catalysts capable of promoting the formation of urethane groups from the reactions of polyisocyanates with polyols are particularly preferred. Well known types of urethane catalysts are organic tertiary amines and/or organometallic compounds. Preferred tertiary amines known in the art and suitable for this purpose include, but are not limited to, dimorpholino diethyl ether (DMDEE) and bis-2-(N,N-dimethylamino)-diethyl ether, triethylenediamine, salts of triethylenediamine, combinations of these, and the like. Suitable loadings for such optional tertiary amine catalysts in this application of the reaction systems of the invention are from 0.001 to about 5% by weight of the total reaction system, preferably from 0.005% to about 2%, more preferably from 0.01% to about 1.5%, still more preferably from 0.01% to about 1%, even more preferably from 0.02% to 0.5%, and most preferably from 0.03% to 0.3% by weight based on the weight of the total reaction system (including the catalyst and any other optional additives).

Examples of organometallic catalysts suitable for use as the optional catalyst additives in the reaction systems according to this embodiment of the invention include, but are not limited to, organic compounds of iron, tin, zinc, lead, bismuth, mercury, calcium, sodium, lithium, potassium, zirconium, or titanium. Organotin catalysts are particularly preferred organometallic catalysts in this end use application. Examples of preferred tin based organometallic catalysts include dibutyltin diluarate, dibutyltin diacetate, dimethyltin dioleate, organotin mercaptides, combinations of these, and the like. Preferred compounds of iron or titanium include, for example, compounds based on acetoacetate complexes wherein the acetoacetate may optionally be used in excess. Suitable loadings for the optional organometallic catalysts in the reaction systems according to this end use embodiment of the invention are from 0.001 to about 5% by weight of the total reaction system, preferably from 0.005% to about 2%, more preferably from 0.01% to about 1.5%, still more preferably from 0.01% to about 1%, even more preferably from 0.015% to 0.5%, and most preferably from 0.025% to 0.3% by weight based on the weight of the total reaction system (including the catalyst and any other optional additives). Combinations of tertiary amine catalysts and organometallic catalysts may be used, if desired.

Examples of suitable optional fire retardants include liquid organic phosphonates and phosphates, such as, for example, trischloroisopropylphosphate (TCPP). Other examples of suitable fire retardants include solid fillers such as alumina trihydrate, melamine, antimony oxides, and the like. Other organic fire retardants include brominated and/or chlorinated aromatic compounds. Soluble fire retardants are the more preferred. Loadings of fire retardant, when used, may vary considerably depending upon the purpose of the gel. Different types and loadings of the optional fire retardants, for specific end use applications of the gels, will be appreciated by those skilled in the art. Mixtures of two or more different types of fire retardant additives may be used, if desired.

Examples of suitable optional surfactants, which are sometimes used to improve the flow and wetting properties of the reaction systems of the invention during the mixing and processing thereof, include ethoxylated phenols, polysiloxane polyoxyalkylene copolymers, mixtures of these, and the like. Surfactants, when used, are normally employed at about 0.1 to about 5% by weight of the total reaction system, more preferably from about 0.2 to 2% by weight, and still more preferably from about 0.25 to about 1.5% by weight relative to the total reaction system (including any optional additives the system may contain).

As noted previously, the preferred gel compositions contain a crosslinked polymer matrix. The crosslinked polymer matrix (the polyurethane) is thermoset, and therefore not soluble. Because it is not soluble, it can be softened by the oil, but will not dissolve in the oil. The gel therefore remains solid, albeit a very soft and flexible solid, because of the crosslinked polymer matrix. The crosslinked polymer, formed from the reaction of the polyisocyanate with the isocyanate reactive materials in the reaction system, prevents the gel from flowing like a liquid. In the most preferred situation, the oil is evenly distributed throughout the gel and does not form a separate phase within the gel or migrate to the surface of the gel. This preferred situation provides for the most useful combination of properties. The gels prepared from the reaction systems according to the invention may be processed into shapes by reactive molding, directly from liquid precursors. They may optionally be encapsulated within other materials, most preferably flexible materials such as fabric or elastomers. Examples of preferred composite structures prepared from the gels include gels which have been covered on at least one side with a decorative layer, such as a fabric layer, a flexible plastic layer, leather, or like material. Further examples of preferred composite structures prepared from the gels include gels which have been covered on one side with a decorative layer and on the opposing side with a solid elastomer, gels that have been formed inside a flexible pouch, wherein said pouch may then optionally be sealed, and the like. In particularly preferred embodiments of the invention, the gels are completely encapsulated on all sides by flexible covering materials. Particularly preferred flexible covering materials comprise elastomeric coverings.

The reaction systems according to the invention may be processed into gels under any suitable processing conditions known in the art. Conditions will likely vary with the composition of the raw materials and the amount/types of catalysts used. Once the chemical ingredients are combined and mixed the system will begin to react. The rate of reaction will be faster at higher temperatures. The process temperature range may extend from about 20°C to about 110°C, but is more preferably in the range of from about 40°C to about 90°C, still more preferably in the range of from 50°C to 85°C, and most preferably in the range of from 70°C to 80°C. The mixed reaction system is preferably maintained at its processing temperature at least until gellation occurs. This time will vary from a minute or less to several days, depending on the composition and temperature, but is preferably in the range of from about a minute to 8 hours, and more preferably in the range of from about 1 minute to 10 minutes. An advantage of the gel forming reaction systems according to the preferred embodiments under this end use application is that the process oil according to the invention does not interfere with cure (ie. by poisoning the catalyst) to nearly the same extent as prior art plasticizers such as phthalate esters.

Although foam re-bonding adhesives and systems for making polyurethane gels are particularly important end-use applications of the reaction systems of the invention, other possible end use applications will the appreciated by those skilled in the art as being within the broader scope of the invention.

The following examples are provided to illustrate the invention and should not be construed as limiting thereof.

EXAMPLES:

Part- A: Adhesive Systems: GLOSSARY: 1) ARCOL^® F3022 polyol: Is a polyether polyol having a MW of 3000 and a OH# of 56, available from Bayer Corporation. 2) RUBINATE^® 9471 polyisocyanate: Is a polymeric MDI having an NCO value of 32% and a functionality of 2.5, available from Huntsman Polyurethanes. 3) SUNDEX 840 oil: Is an aromatic hydrocarbon oil available from Sun Oil.

4) NYCEL^® U-1500 oil: Is an aromatic hydrocarbon oil available from Crowley Chemical Company.

5) NYCEL^® U-1500N oil: Is an aromatic hydrocarbon oil with vanilla masking agent, available from Crowley Chemical Company.

6) NIPLEX 110C oil: Is a naphthenic hydrocarbon oil available from Crowley Chemical Company.

Examples 1-8: The physical properties listed in Table 1 were obtained from the production ofa l7 X 17 X 2 inch, 5-PCF block of bonded carpet underlayment. The block of underlayment was produced in appropriate weights based on 10-percent adhesive (see the individual adhesive compositions in Table 1) and 90-percent polyether-urethane foam crumb (average 3-4 PCF and ground to approximately 3/8 inch diameter).

Examples 1, 2, 3 and 4 evaluate the effects of an adhesive produced with SUΝDEX 840 oil and with NYCEL^® U-1500 oil at increased oil loadings on the physical properties of a 5-PCF rebond carpet pad. Example 1 (Control 1) was produced with SUΝDEX 840 oil. As Table 1 shows, the use of NYCEL^® U-1500 oil in place of SUΝDEX 840 oil does not reduce the pad's physical properties. Furthermore, increased levels of NYCEL^® U-1500 oil do not reduce the pad's physical properties. However, the use NYPLEX U-1500 oil produces an adhesive and pad with a slightly noticeable odor.

Examples 3, 3a, 3b, and 3c evaluate the affect of decreased prepolymer ΝCO content on the pad's physical properties. As the results in Table 1 show, the reduced prepolymer ΝCO does not negatively affect the pad's physical properties. Again, the use of NYCEL^® U- 1500 oil produced an adhesive and pad with a slightly noticeable odor.

Example 5 and 6 compare the use of Sundex 840 oil (Control 2) with the same 30% loading using NYCEL^® U-1500N oil (Example 6).

Examples 7 and 8 evaluate the effect of using a diluent blend of NYCEL^® U-1500N oil (aromatic hydrocarbon with vanilla masking agent) and NIPLEX 110C oil (naphthenic hydrocarbon with minimal odor) on the pad's physical properties. While NYCEL^® U-1500N oil does have an odor, it is not as noticeable as NYCEL^® U-1500 oil itself. Additionally, a 60-percent by weight NYCEL^® U-1500N oil, 40-percent NIPLEX 110C oil blend used in an adhesive at 30-percent by weight of the total adhesive produced a pad with an odor less noticeable than Example 5 (Control 2) produced at the same loading with SUΝDEX 840 oil. SUΝDEX 840 oil is considered to be a standard as a bonded foam adhesive diluent. Furthermore, the use of the blends in Examples 7 and 8 did not produce physical properties worse than Example 5 (Control 2).

The Control Examples 1 and 5 [Control 1 and Control 2, respectively] are comparative, and not within the scope of the invention. All the other Examples in Part- A are according to the invention.

Table 1. Summary of Physical Property Data.

Part-B: Gel Systems. Glossary:

1) RUBINATE M polyisocyanate: Is a polymeric MDI product having a free %NCO content of about 31.5%, a number averaged NCO group functionality of about 2.7, and is available from Huntsman International LLC.

2) RUBINATE-9500 polyisocyanate: Is an MDI prepolymer of flexible polyether polyols. This product has a free %NCO content of about 8%, and is available from Huntsman International LLC. This flexible prepolymer product has a number averaged NCO functionality of less than 2.3.

3) JEFFOL G-31-28 polyol: Is a flexible polyether nominal triol based on propylene oxide and ethylene oxide, having a number averaged molecular weight of about 6000. This polyol is available from Huntsman Petrochemical Corporation.

4) JEFFOL PPG-3709 polyol: Is a flexible polyether nominal diol based on propylene oxide and ethylene oxide, having a number averaged molecular weight of about 3500. This polyol is available from Huntsman Petrochemical Corporation.

5) DPG: Is dipropylene glycol.

6) DIOP: Is diisooctyl phthalate.

7) 33LV: Is DABCO® 33LN catalyst, which is a tertiary amine based catalyst available from Air Products and Chemicals Inc.

8) NYCEL U-1500 oil: Is as defined hereinabove (in Part-A of these Examples).

9) NIPLEX 110C oil: Is as defined hereinabove (in Part-A of these Examples).

Table 2 contains the compositions by weight of a series of gel-forming reaction systems according to the invention. The most preferred Examples in Table 2 are those containing NYCEL^®U-1500 oil, i.e., Examples 1-6.

TABLE 2

N.G.: Not Gelled over night at 80°C, but remained a viscous liquid.

33LV is believed to be a 33% by weight solution of triethylenediamine in DPG.

The Examples in Table 2 were processed into gels as two component systems, wherein the isocyanate component contains the blend of isocyanates shown, and the isocyanate reactive component contains all polyols, chain extenders, crosslinkers, and additives (including all the process oils, other plasticizers, and catalysts used in each formulation). The two component formulations were mixed by hand and stirred for 30 seconds (until homogeneous). Each reaction mixture was poured into a pre-heated aluminum mold over a flexible vinyl film and allowed to cure at 80°C for the length of time shown in the Table 2. The samples that gelled were then demolded. The flexible vinyl film used in all these Examples was Rochell, obtained from CIPCO

Inc.

Observations (gel systems):

The hardness of resulting elastomers (gels) were at shore 00 and below. The elastomers were also sometimes sticky and need to be covered with flexible films.

Two products were tested in the Examples, VYCEL^® U-1500 oil and NIPLEX 110C oil. VYCEL^® U-1500 oil has a higher aromatic content than NIPLEX 1 IOC oil (about 100% for VYCEL^® U-1500 oil vs. 50% for 110C). It was found that VYCEL^® U-1500 oil had better compatibility with urethane formulations than VIPLEX 110C oil to make the desired softness urethane gel. In order to reach the desired softness, it takes about minimum 40 wt% of total plasticizer loading relative to overall composition.

It was also found that the aromatic content in the aromatic process oils played an important role in the compatibility with urethane formulations. At the same level of oil content (46%) added into urethane formulations, the gel based on VYCEL^® U-1500 oil did not have compatibility problems (such as oil migrating to the surface of the gel) but the gel based on VIPLEX 110C oil did show the oil migrating to the surface right after cure.

The results indicate that VYCEL^® U-1500 oil has a broad range of compatibility with urethane formulations. The maximum amount of VYCEL^® U-1500 oil added was 55% by weight in formulation 5 and 6.

There was evidence indicating that the loading of VYCEL^® U-1500 oil could go higher than 60%. Higher loadings were not investigated because the PU gels (shown) were already soft enough to meet the application requirements.

Claims

CLAIMS:

What is claimed is:

L A reaction system for forming isocyanate-based polymers comprising:

(a) a organic polyisocyanate composition containing a plurality of free organically bound isocyanate groups,

(b) a hydrocarbon process oil having a content of aromatic species of at least 48% by weight and having an initial boiling point at 1 atmosphere pressure of at least 400°F, wherein at least 88% by weight of the oil distills between 400°F and 650°F, and optionally

(c) a polyfunctional isocyanate-reactive material containing at least two isocyanate- reactive groups per molecule.

2. The reaction system of claim 1, wherein the organic polyisocyante composition comprises an aromatic polyisocyanate.

3. The reaction system of claim 1, wherein the organic polyisocyante composition comprises one or more isocyanate functional prepolymers.

4. The reaction system of claim 1, wherein the reaction system comprises greater than 10% by weight of the hydrocarbon process oil.

5. The reaction system of claim 1, wherein the reaction system comprises greater than 20% by weight of the hydrocarbon process oil.

6. The reaction system of claim 5, wherein the hydrocarbon process oil has a content of aromatic species of at least 80% by weight.

7. The reaction system of claim 6, wherein the aromatic hydrocarbon process oil and the polyfunctional isocyanate-reactive material are fully miscible in all proportions at 25°C.

8. The reaction system of claim 1, wherein the polyfunctional isocyanate-reactive material is selected from the group consisting of water, polyols, polyamines, aminoalcohols, polycarboxylic acids, and mixtures thereof.

9. A reaction system for forming isocyanate-based polymers comprising:

(b) a hydrocarbon process oil having a content of aromatic species of at least 80% by weight and having an initial boiling point at 1 atmosphere pressure of at least 525 °F, wherein at least 95% by weight of the oil distills between 525°F and 625°F, and optionally

10. The reaction system of claim 9, wherein the organic polyisocyante composition comprises an aromatic polyisocyanate.

11. The reaction system of claim 9, wherein the organic polyisocyante composition comprises one or more isocyanate functional prepolymers.

12. The reaction system of claim 9, wherein the reaction system comprises greater than 20% by weight of the hydrocarbon process oil.

13. The reaction system of claim 9, wherein the aromatic hydrocarbon process oil and the polyfunctional isocyanate-reactive material are fully miscible in all proportions at 25°C.

14. The reaction system of claim 9, wherein the polyfunctional isocyanate-reactive material is selected from the group consisting of water, polyols, polyamines, aminoalcohols, polycarboxylic acids, and mixtures thereof.

15. A method of making an isocyanate-based polymer comprising the step of reacting:

(a) a organic polyisocyanate composition containing a plurality of free organically bound isocyanate groups, (b) a hydrocarbon process oil having a content of aromatic species of at least 80% by weight and having an initial boiling point at 1 atmosphere pressure of at least 525°F, wherein at least 95% by weight of the oil distills between 525°F and 625°F, and optionally

16. The method of claim 15, wherein the organic polyisocyante composition comprises an aromatic polyisocyanate.

17. The method of claim 15, wherein the organic polyisocyante composition comprises one or more isocyanate functional prepolymers.

18. The method of claim 17, wherein the aromatic hydrocarbon process oil and the polyfunctional isocyanate-reactive material are fully miscible in all proportions at 25°C.

19. The method of claim 15, wherein the polyfunctional isocyanate-reactive material is selected from the group consisting of water, polyols, polyamines, aminoalcohols, polycarboxylic acids, and mixtures thereof.

20. A polyurethane gel comprising the reaction product of:

(b) a hydrocarbon process oil having a content of aromatic species of at least 48% by weight and having an initial boiling point at 1 atmosphere pressure of at least 400°F, wherein at least 88% by weight of the oil distills between 400°F and 650°F, and

21. The polyurethane gel of claim 20, wherein the organic polyisocyanate composition comprises an isocyanate terminated prepolymer.

22. The polyurethane gel of claim 20, wherein the polyurethane gel comprises from greater than 10% to about 80% by weight of the hydrocarbon process oil.

23. An adhesive comprising the reaction product of:

(b) a hydrocarbon process oil having a content of aromatic species of at least 48% by weight and having an initial boiling point at 1 atmosphere pressure of at least 400°F, wherein at least 88% by weight of the oil distills between 400°F and 650°F,

(c) water, and optionally

(d) an additive.

24. The adhesive of claim 23, wherein the additive is selected from the group consisting of catalysts, surfactants, fire retardants, and mixtures thereof.

25. The adhesive of claim 23, wherein the organic polyisocyanate composition comprises an isocyanate terminated prepolymer of a flexible polyol.