CA2440608A1 - In-situ polymerization on recycled foam fragments - Google Patents
In-situ polymerization on recycled foam fragments Download PDFInfo
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- CA2440608A1 CA2440608A1 CA002440608A CA2440608A CA2440608A1 CA 2440608 A1 CA2440608 A1 CA 2440608A1 CA 002440608 A CA002440608 A CA 002440608A CA 2440608 A CA2440608 A CA 2440608A CA 2440608 A1 CA2440608 A1 CA 2440608A1
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- isocyanate
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/35—Composite foams, i.e. continuous macromolecular foams containing discontinuous cellular particles or fragments
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2375/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
- C08J2375/04—Polyurethanes
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- Engineering & Computer Science (AREA)
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- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Adhesives Or Adhesive Processes (AREA)
- Polyurethanes Or Polyureas (AREA)
Abstract
Process for preparing rebonded, flexible foam articles is provided. The process includes mixing together a mass of flexible foam crumbs with a liqui d reaction mixture comprising polyisocyanate having a free isocyanate group content of greater than 10 % by weight and polyfunctional organic isocynate- reactive material. The rebonded, flexible foam articles can be prepared in t he absence of steam as a curative agent.
Description
IN-SITU POLYMERIZATION OF BONDED FOAM ADHESIVES
This application claims the benefit of U.S. Provisional Application Serial No.
60/279,013, filed on March 27, 2001.
BACKGROUND OF THE INVENTION
The conventional method of manufacturing bonded foam entails supplying isocyanate, polyol and optional processing oil to a reactor to produce a prepolymer. The prepolymer then is blended with flexible foam crumb, as an adhesive. The resulting mass of adhesive (prepolymer) treated foam crumbs is molded under pressure and steam is simultaneously injected to cure the prepolymer and to produce a bonded foam product.
The conventional method described above has several disadvantages. These disadvantages include, for example, improper blending of components which results in a gelled polymer inside the reactor, moisture ingress into the prepolymer reactor which can 1 S cause solid reacted polymer to form in the reactor, and premature reactivity of the prepolymer with ambient moisture before the compression molding stage can reduce the tensile strength of the bonded foam. Separation of the components of the prepolymer, especially the diluent process oil, may occur in the conventional process. This bulk separation of the prepolymer causes serious handling and storage problems. Another serious disadvantage of the conventional foam re-bonding process concerns the use of steam as the curative agent for the prepolymer adhesive. The steam adds large quantities of moisture to the re-bonded foam product, which must subsequently be dried out of the product before the product can be used or packaged. This drying operation can be energy intensive. It also wastes time, floor space, and adds to the complexity of the overall process.
Additional disadvantages associated with the conventional method described above include restrictions on starting materials. The polyol employed typically is a nominal triol that has a number averaged molecular weight in the range of 3,000 to 3,500.
Use of polyols which are significantly outside this molecular weight range can cause problems in managing the viscosity and physical stability of the prepolymer. Moreover, the prepolymer is restricted to an isocyanate value of approximately 7% or greater due to constraints on the viscosity of the prepolymer which can be employed in the conventional method of the prior art. The viscosity restrictions at low isocyanate values are especially severe with MDI
based prepolymers. MDI based isocyanates are becoming increasingly preferred in the foam re bond industry for health and environmental reasons. This is because they have lower vapor pressures than TDI isocyanates. The limitations, imposed by viscosity considerations, on the minimum free isocyanate content of the prepolymer places serious restrictions on the range of adhesive properties that may be achieved. For example, if the free isocyanate content of the prepolymer is too high, then the adhesive will be too rigid and brittle upon curing. The S purpose of the polyol component in the adhesive is to impart flexibility to the adhesive bond.
The prepolymer method imposes restrictions on the amount of this flexibilizing polyol which may be incorporated into the adhesive. In general, in order to be processable, the prepolymer must have a viscosity of less than about 4000 cps at 25°C.
A need therefore exists for adhesives which can be used to produce bonded foam, and methods of producing bonded foam which avoid the disadvantages of the prior art prepolymer method. It would be particularly desirable not to have to make prepolymers at all, but to find another way of incorporating the flexibilizing polyol ingredient into the' adhesive composition which can accommodate any ratio of polyol to base (monomeric) polyisocyanate. Ideally, it would be desirable to be able to cure the adhesives without steam or added moisture.
SUMMARY OF THE INVENTION
There is disclosed an improved method for re-bonding foam crumbs with an isocyanate based adhesive composition. The adhesive composition comprises a plurality of separate reactive components including at least one organic polyisocyanate component and at least one organic isocyanate reactive component, wherein the separate reactive components are applied to a single mass of foam crumbs before the reaction between the separate components is substantially completed. The method of the invention overcomes the limitations associated with the use of single component isocyanate terminated prepolymer adhesives.
DETAILED DESCRIPTION OF THE INVENTION
Glossary:
As used herein, the following terms have the meanings defined below:
1. Calight RPO is naphthenic oil from Calumet Lubricants;
This application claims the benefit of U.S. Provisional Application Serial No.
60/279,013, filed on March 27, 2001.
BACKGROUND OF THE INVENTION
The conventional method of manufacturing bonded foam entails supplying isocyanate, polyol and optional processing oil to a reactor to produce a prepolymer. The prepolymer then is blended with flexible foam crumb, as an adhesive. The resulting mass of adhesive (prepolymer) treated foam crumbs is molded under pressure and steam is simultaneously injected to cure the prepolymer and to produce a bonded foam product.
The conventional method described above has several disadvantages. These disadvantages include, for example, improper blending of components which results in a gelled polymer inside the reactor, moisture ingress into the prepolymer reactor which can 1 S cause solid reacted polymer to form in the reactor, and premature reactivity of the prepolymer with ambient moisture before the compression molding stage can reduce the tensile strength of the bonded foam. Separation of the components of the prepolymer, especially the diluent process oil, may occur in the conventional process. This bulk separation of the prepolymer causes serious handling and storage problems. Another serious disadvantage of the conventional foam re-bonding process concerns the use of steam as the curative agent for the prepolymer adhesive. The steam adds large quantities of moisture to the re-bonded foam product, which must subsequently be dried out of the product before the product can be used or packaged. This drying operation can be energy intensive. It also wastes time, floor space, and adds to the complexity of the overall process.
Additional disadvantages associated with the conventional method described above include restrictions on starting materials. The polyol employed typically is a nominal triol that has a number averaged molecular weight in the range of 3,000 to 3,500.
Use of polyols which are significantly outside this molecular weight range can cause problems in managing the viscosity and physical stability of the prepolymer. Moreover, the prepolymer is restricted to an isocyanate value of approximately 7% or greater due to constraints on the viscosity of the prepolymer which can be employed in the conventional method of the prior art. The viscosity restrictions at low isocyanate values are especially severe with MDI
based prepolymers. MDI based isocyanates are becoming increasingly preferred in the foam re bond industry for health and environmental reasons. This is because they have lower vapor pressures than TDI isocyanates. The limitations, imposed by viscosity considerations, on the minimum free isocyanate content of the prepolymer places serious restrictions on the range of adhesive properties that may be achieved. For example, if the free isocyanate content of the prepolymer is too high, then the adhesive will be too rigid and brittle upon curing. The S purpose of the polyol component in the adhesive is to impart flexibility to the adhesive bond.
The prepolymer method imposes restrictions on the amount of this flexibilizing polyol which may be incorporated into the adhesive. In general, in order to be processable, the prepolymer must have a viscosity of less than about 4000 cps at 25°C.
A need therefore exists for adhesives which can be used to produce bonded foam, and methods of producing bonded foam which avoid the disadvantages of the prior art prepolymer method. It would be particularly desirable not to have to make prepolymers at all, but to find another way of incorporating the flexibilizing polyol ingredient into the' adhesive composition which can accommodate any ratio of polyol to base (monomeric) polyisocyanate. Ideally, it would be desirable to be able to cure the adhesives without steam or added moisture.
SUMMARY OF THE INVENTION
There is disclosed an improved method for re-bonding foam crumbs with an isocyanate based adhesive composition. The adhesive composition comprises a plurality of separate reactive components including at least one organic polyisocyanate component and at least one organic isocyanate reactive component, wherein the separate reactive components are applied to a single mass of foam crumbs before the reaction between the separate components is substantially completed. The method of the invention overcomes the limitations associated with the use of single component isocyanate terminated prepolymer adhesives.
DETAILED DESCRIPTION OF THE INVENTION
Glossary:
As used herein, the following terms have the meanings defined below:
1. Calight RPO is naphthenic oil from Calumet Lubricants;
2. Calsol~ 806 is naphthenic oil from Calumet Lubricants;
3. DABCO~ 33LV is 33% triethylene diamine in dipropylene glycol available from Air Products;
4. Dabco~ 120 is a tin catalyst from Air Products, Inc.;
5. Dabco~ 8154 is acid blocked Dabco 33LV available from Air Products;
6. Dabco~ T-45 is a potassium carboxylate catalyst formulation from Air Products and Chemicals, Allentown, PA;
7. JEFFOL~ PPG-3704 polyol is an EO tipped diol with a molecular weight of 3700 from Huntsman Polyurethanes.
8. RUBINATE~ 9041 isocyanate is a blend of 75% RUBINATE~ M isocyanate and 25% of an MDI isomer blend having 80% 4,4'MDI and 20% 2,4'MDI;
9. RUBINATE~ M isocyanate is polymeric MDI from Huntsman Polyurethanes having an isocyanate value of 31.5% by weight and a functionality of 2.7;
10. RUBINOL~ F459 polyol is a polyether polyol from Huntsman Polyurethanes with a hydroxyl number of 30 and a nominal functionality of 2;
11. Sundex~ 840 is an aromatic oil from Sun Oil Company;
12. Voranol~ 3512 is polyether polyol from Dow Chemical Company with a hydroxyl number of 48.1 and a nominal functionality of 3;
13. Over Index means a stoichiometric ratio of NCO:active -H groups > 1;
14. Under Index means a stoichiometric ratio of NCO:active -H groups < 1;
15. The functionalities and molecular weights of polymeric compounds are number averaged, unless otherwise specified. The functionalities and molecular weights of pure compounds are absolute, unless otherwise specified.
16. The term "nominal functionality" refers to the assumed functionality of a polymeric species (such as a polyol) based on the functionality of its monomers, ignoring side reactions. For example, the nominal functionality of a polyoxyalkylene polyol is the functionality of its initiator.
The invention relates to adhesive compositions comprising a plurality of reactive components, and methods of producing bonded foam crumb products therefrom. All of the components are preferably liquids at the temperature of application, and more preferably all the components are homogeneous liquids at ambient temperature. Advantageously, the multicomponent adhesive compositions can be directly or catalytically polymerized in-situ on the foam crumb without the need to use an intermediate prepolymer. The in-situ polymerization may be accomplished with steam, electromagnetic energy, or hot air. The adhesive compositions of the invention are not restricted by isocyanate value or prepolymer viscosity as in the prior art. Moreover, the prior art requires that an "A-side" (isocyanate component) and a "B-side" (polyol component) be separately prepared, mixed together, and then added to the foam crumbs. In an aspect of the invention, each component used can be added directly into a mass of foam crumbs without the need for making an A-side and B-side.
The use of moisture or steam to cure the adhesive is not required, and is generally less preferred than other methods of cure (such as the use of hot air or electromagnetic radiation).
In addition to the above noted advantages, the multicomponent adhesive compositions of the invention are less constrained, as compared to the prior art, in regard to the ranges of molecular weight or functionality of the flexibilizing polyols or the monomeric (base) polyisocyanates which can be used. Likewise, the flexibilizing polyol and the monomeric (base) polyisocyanate can be combined in virtually any desired ratio by using the multicomponent approach according to the invention. Moreover, if the energy source for curing the multicomponent adhesive is hot air or electromagnetic energy, then the need for an extra process step to remove moisture from the cured re-bond foam product is eliminated.
In an aspect of the invention, an isocyanate, polyol and optional oil are mixed in the presence of a metal catalyst and/or an amine type catalyst to produce an adhesive composition which can be polymerized with or without steam. The adhesive compositions are particularly suited for bonding of polyurethane foam crumb. The adhesive according to the invention is formulated and can be applied to the foam crumbs as two or more separate reactive components. The preferred mode is to use two separate reactive components, although any number of reactive components may be used if desired. In this preferred mode, the flexible polyol and the catalyst are combined into one component. The second component is the monomeric (base) polyisocyanate. The optional process oil, if used, may be combined with either or both of these two reactive components. The separate reactive components of the multicomponent adhesive may be added simultaneously or separately to the same mass of foam crumbs, in any desired overall amounts, or in any ratio with respect to each other. It is preferred that all the separate reactive components are added to the same mass of foam crumbs to be bonded. In a preferred mode all the reactive components are added simultaneously to the same mass of foam crumbs. In another embodiment the separate reactive ingredients may be pre-mixed immediately before application to the foam crumbs, under the proviso that significant reaction of the separate components does not occur in the pre-mix before the pre-mix is applied to the foam crumbs. If such a pre-mix is used, then less than 50% of the reactive isocyanate or isocyanate-reactive functional groups initially present should have reacted before the pre-mix is applied to the foam crumbs, preferably less than 40%, more preferably less than 30%, still more preferably less than 25%, and most preferably less than 20%. If the reaction of the separate ingredients in such a pre-mix is too far advanced at the time of application, it may become physically impossible to S apply the adhesive to the foam crumbs. If this reaction is too far advanced at the time the adhesive treated foam crumbs are compressed in the mold, then the adhesive may not bond the foam particles effectively and a poor quality product will result.
A particularly advantageous variant of the pre-mix method is to employ a multicomponent metering machine to meter together and mix the various components of the adhesive and then immediately apply the reacting mixture to the mass of foam crumbs. The reacting mixture may, for example, be applied to the foam crumbs by spraying or by means of a spinning disk applicator. The foam crumbs thus treated may preferably be tumbled while the reacting adhesive mixture is applied, or immediately thereafter, in order to maximize the distribution of the adhesive onto the foam crumbs.
A further advantage of the present invention is that bonded foam crumb products can be produced in surprisingly short cycle times. In this regard curing of the adhesive composition can occur in less than 30 minutes (measured from the time the press is closed) with or without the application of steam. More preferably curing occurs in less than 1 S
minutes and even more preferably curing can occur in less than 10 minutes. In an aspect of the invention curing of the adhesive can occur in from 1 to 10 minutes and, more preferably, in from 3 to 5 minutes.
MATERIALS:
Isocyanate Component:
The multicomponent adhesives of the invention comprise at least one isocyanate component. The isocyanate component comprises at least one organic compound wherein the organic compound contains a plurality of isocyanate groups. The preferred isocyanate compounds are monomeric (base) polyisocyanates.
Organic monomeric polyisocyanates which are useful as the isocyanate components in the context of the invention include aromatic, aliphatic and cycloaliphatic diisocyanates and polyisocyanates and combinations of these types.
Aromatic diisocyanates which may be used include 4,4'MDI, 3,3'-dimethyl-4,4'-diphenylenediisocyanate, 3,3'-dimethoxy-4,4'-bisphenylenediisocyanate, 3,3'-diphenyl-4,4'-biphenylenediisocyanate, 4,4'-biphenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, toluene diisocyanate, and 1,5-naphthalene diisocyanate. MDI isocyanates are preferred. Polymeric MDI having about 31.5% NCO and about 2.7 functionality is most preferred. Polymeric MDI is a combination of monomeric isocyanates which includes 4,4'-MDI, lesser amounts of 2,4'-MDI, minor amounts of 2,2'-MDI, and a mixture of 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 high functionality polymethylene polyphenyl polyisocyanate monomer species. Polymeric MDI is prepared by the phosgenation of mixed aromatic amines obtained from the condensation of aniline with formaldehyde. The preparation of polymeric MDI is well known in the art. It is also within the invention to use blends of polymeric MDI with additional amounts of diphenylmethane diisocyanates, particularly 4,4'-MDI. These blends will have number averaged isocyanate functionalities of from greater than 2.0 up to about 2.7, depending upon the ratio of the diphenylmethane diisocyanates to the polymethylene polyphenyl polyisocyanates in the blend.
Aliphatic isocyanates which 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-1,6-hexamethylene diisocyanate, and 1,12-dodecane diisocyanate.
Cycloaliphatic isocyanates which may be employed include but are not limited to cyclohexane-1,4-diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, 1-isocyanato-2-isocyanatomethyl cyclopentane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane (isophorone diisocyanate or IPDI), 2,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate.
Although it is preferred not to use prepolymers in this invention, it is within the scope of the invention to use as one or more components of the multicomponent adhesive composition an isocyanate terminated prepolymer. If an isocyanate terminated prepolymer is used as a component of the adhesive formulation, it is preferable that the prepolymer have a relatively high free isocyanate content. Preferably the prepolymer, if used at all, has an free isocyanate content of greater than 10% by weight, and more preferably greater than 15% by weight.
Isoc~anate Reactive Component:
The multicomponent adhesive formulations of the invention comprise at least one isocyanate reactive component. The isocyanate reactive component contains at least one organic compound having a plurality of isocyanate reactive groups. The preferred isocyanate reactive compounds are polyols. The isocyanate reactive component may optionally include water in addition to the organic isocyanate reactive ingredients, although it is preferable not to include water.
Suitable organic polyols useful for making the adhesive compositions of the invention include polyether, polyester, or amine polyols having a molecular weight range of about 50 to about 15,000 and a nominal functionality of about 1.0 to about 7.0, preferably polyether polyols with a molecular weight range of about 50 to about 6,000 and a nominal functionality of about 2.0 to about 3Ø Examples of useful polyols include but are not limited to ethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, diethylene glycol, triethylene glycol, glycerol, trimethylolpropane, triethanolamine, diethanolamine, triisopropanolamine, diisopropanolamine, butanediol, butenediol, butynediol, N-methyl diethanolamine, Rubinol~ F459, Rubinol~ F455 (both from Huntsman Polyurethanes) Arcol~
3022, Arcol~ 3128 (both from Lyondell Corporation), Voranol~ 220-028 (from Dow Chemical Corporation) and Pluracol~ P-2010 (from BASF Corporation). Other isocyanate reactive active hydrogen containing species which may be used include, but are not limited to, diethyltoluene diamine, and N-N,-di-sec-butyl-4,4'-diaminodiphenylmethane.
Simple polyols, containing only organic -OH groups as reactive termini, are preferred. The most preferred polyols contain primary or secondary -OH groups. Primary -OH groups are most preferred.
Rigid polyols also may be employed. Examples of rigid polyols which may be employed include but are not limited to Rubinol~ 8015, Rubinol~ 8180, and Rubinol~ 8260.
(from Huntsman Polyurethanes). These polyols have a functionality of about 2 to about 7 and a molecular weight from about 200 to about 1000.
The preferred polyols are flexible polyols, which contribute a flexibilizing effect to the cured adhesives. Useful flexible polyols have a molecular weight of about 300 to about 10,000, preferably 400 to about 8000, more preferably 1000 to about 6000, and a nominal functionality of about 1.0 to about 6.0, preferably about 2.0 to about 4Ø
Examples of flexible polyols which may be employed include, but are not limited to, Rubinol~ 459 and Rubinol~
455 (from Huntsman Polyurethanes).
Polyether and polyester flexible polyols which may be employed include primary or secondary hydroxyl groups.
Suitable polyether polyols which can be employed as the isocyanate reactive component include those which are prepared by reacting alkylene oxides, halogen-substituted or aromatic-substituted alkylene oxides or mixtures thereof with an active hydrogen-containing initiator compound.
Suitable oxides include, for example, ethylene oxide, propylene oxide, 1,2-butylene oxide, styrene oxide, epichlorohydrin, epibromohydrin, and mixtures thereof.
Suitable initiator compounds include water, ethylene glycol, propylene glycol, butanediol, hexanediol, glycerine, trimethylol propane, pentaerythritol, hexanetriol, sorbitol, sucrose, hydroquinone, resorcinol, catechol, bisphenols, novolac resins, phosphoric acid and mixtures thereof.
Suitable initiators further include, for example, ammonia, ethylenediamine, diaminopropanes, diaminobutanes, diaminopentanes, diaminohexanes, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentamethylenehexamine, ethanolamine, aminoethylethanolamine, aniline, 2,4-toluenediamine, 2,6-toluenediamine, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 1,3-phenylenediamine, 1,4-phenylenediamine, naphthylene-1,5-diamine, triphenylmethane 4,4',4"-triamine, 4,4'-di(methylamino)diphenylmethane, 1,3-diethyl-2,4-diaminobenzene, 2,4-diaminomesitylene, 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1,3,5-triethyl-2,6-diaminobenzene, 3,5,3', 5'-tetra-ethyl-4,4'-diamino-diphenylmethane, and amine aldehyde condensation products such as the polyphenylpolymethylene polyamines produced from aniline and formaldehyde and mixtures thereof.
Polyester polyols which may be employed 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 acid anhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic acid anhydride, tetrachlorophthalic acid anhydride, endomethylene tetrahydrophtalic acid anhydride, glutaric acid anhydride, malefic acid, malefic acid anhydride, 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 and mixtures thereof.
Typically, polyether nominal triols or polyester nominal triols which have a molecular weight of about 3,000 to about 3,500 are used. Diols may also be used. Blends of these polyols also may be employed. Polyether polyols are more preferred. The most preferred polyether polyols are based on propylene oxide, optionally in combination with minor amounts of ethylene oxide. Examples of these most preferred types of polyether polyols include Arcol~ 3022 (from Lyondell Corporation) and Voranol~ 3512 (from Dow Chemical Corporation).
Examples of amine terminated polyols which may be employed include but are not limited to JEFFAMINE~ amine terminated polyether polyols from Huntsman Petrochemicals Corporation.
Mixtures of different polyols may optionally be used. For example, mixtures of relatively high molecular weight polyols and relatively low molecular weight di or polyfunctional active hydrogen compounds may be used as an isocyanate reactive component in the practice of the invention.
The multicomponent adhesive compositions employed in the invention may comprise a catalyst for the reaction of the isocyanate reactive component with the isocyanate component. The catalysts may not be essential in all cases, but are usually preferred. In a particularly preferred embodiment the catalyst is blended together with all isocyanate reactive ingredients to form a single isocyanate reactive component.
Suitable catalysts for use in the adhesive formulations of the invention include but are not limited to triethylene diamine, bis-2-(N,N-dimethylamino)-diethyl ether, 2-(N,N-dimethylamino) ethanol, N-hexadecyl dimethylamine, N,N-dimethylamino propylamine, triethanolamine, triisopropanolamine, N,N-dimethyl cyclohexylamine, 3-(N,N-dimethyl amino)-propionamide, dibutyl tin dilaurate, alkyl tin mercaptide complexes, 2-ethyl hexanoic acid (octoic acid) potassium salt, potassium acetate, potassium oleate, combinations of these, and the like. The catalysts may also include acid blocked amines, an example of which is Dabco~ 8154 (from Air Products and Chemicals Corporation). A preferred catalyst for use in combination with hot air curing is Dabco~ T-45. This catalyst is believed to be a solution of potassium 2-ethyl hexanoate in dipropylene glycol, and is commercially available from Air Products and Chemicals Corporation. In the case of triethanolamine, triisopropanolamine, and other tertiary amine initiated polyols, the polyol and the catalyst ingredients may be the same chemical species.
Suitable diluents for use in the adhesive formulations of the invention include but are not limited to processing oils such as naphthenic, aromatic, and paraffinic oils, natural oils such as vegetable oils, or any blend of these. Napthenic process oils are preferred. Suitable diluents may include methylene chloride, ketone-based solvents, propylene carbonate, mixtures of these, and the like.
In a particularly preferred embodiment of the invention there are only two components to the adhesive system used. One component is a monomeric (base) 5 polyisocyanate composition. The other component is a blend of all the liquid or soluble isocyanate reactive compounds, catalysts, diluents, and any additional optional additives to the adhesive. Both components are preferably homogeneous liquids at ambient temperature (i.e., 25°C). It is, however, within the scope of the invention to use one or more liquid components that are not fully homogeneous, with the proviso that any inhomogeneous 10 ingredients are dispersed in a liquid component.
The relative proportions of the various components of the multicomponent adhesive system, and of the various ingredients to each component, may be adjusted in order to fine tune the properties of the final adhesive bonded foam product. A particularly advantageous feature of the instant invention is the absence of restrictions imposed due to handling requirements of the relative amounts of isocyanate and isocyanate reactive monomers that may be employed in the adhesive composition of the invention. Indeed, the effective "isocyanate index" (also known as "Index") of the adhesive formulation may take on any value. The isocyanate index is the ratio of isocyanate groups to isocyanate reactive groups in the formulation, and is usually expressed as a percent. A value of greater than 100% means that excess isocyanate is used (referred to as "over index"). A value of less than 100% means that excess isocyanate reactive material is used (referred to as "under index"). A value of 100% is indicative of an exact stoichiometric balance between the isocyanate and isocyanate reactive material in the adhesive formulation. Good re-bonded foam products can be prepared by using the multicomponent adhesives of the invention, at index values of less than 100%, at greater than 100%, or at exactly 100%. By contrast, using the prior art one-component (isocyanate terminated prepolymer) rebond adhesives, it is only possible to make re-bonded foam products at index values considerably above 100%. These prior art systems depend on moisture (usually in the form of steam) to react out the excess isocyanate groups present. This can result in undesirable properties (due to the high levels of urea linkages present in the cured adhesive) and problems with drying the re-bonded foam product, as described hereinabove.
Additional ingredients can be included in the adhesive formulations of the invention.
Examples of these additional ingredients include but are not limited to non-reactive chemicals such as trischloropropylphosphate or other fire retardants, dyes or colorants, wood or cellulosic fibers, rubber or elastomer particles, other inert fillers, mixtures of these and the like. These optional additional inert ingredients, if used at all, may be pre-mixed with any of the essential ingredients in any desired proportion prior to forming the reacting adhesive mixture. They may alternatively be combined with the other ingredients in the final mixing step, just prior to application of the reaction mixture to the foam crumbs.
The adhesive formulations may be employed with a variety of foam crumb types to produce bonded foam crumb products. Examples of types of foam crumb which may be used include polyether urethane foam crumb, polyester urethane foam crumb, reground rebond, cloth and foam from automotive recyclate, bedding process scrap, rubber process scrap, I O molded foam process scrap, post-consumer recyclate, slabstock process scrap. Blends of different types of foam crumb also may be used. Examples of useful foam blends include rigid foam with flexible foam, polyether urethane based foam with polyester urethane based foam and polyisocyanurate based foam.
The foam crumbs may also be combined with other solid additives prior to or 15 simultaneously with the application of the adhesive composition. Solid additives to the foam crumbs may include solid fire retardants such as melamine, ammonium polyphosphate, antimony oxide, alumina trihydrate, mixtures of these, and the like. The foam crumbs may also be combined with cellulosic or lignocellulosic particulate or fibrous materials as extenders. The foam crumbs may also be extended with inorganic fibrous materials such as 20 glass fibers, glass mats, mineral wool, and the like. Likewise, the foam crumbs may be combined with organic fibrous materials such as textile scraps, carpet scraps, and the like.
Also, it has been found effective to add calcium carbonate to the foam crumbs to increase the density of the obtained foam pad.
The invention will now be described by reference to the following non-limiting 25 examples. All amounts are expressed in weight percent based on the total weight of the composition.
EXAMPLES:
One composition of an adhesive according to the invention is shown below as 30 Adhesive A. It can be prepared by hand mixing 50 grams (total of all components used to form the adhesive) of adhesive with a tongue depressor, for about 10 seconds in a 4 ounce paper cup. The isocyanate can be added in an amount appropriate to produce the desired Index. In an aspect of the invention, all of the components can be added to the foam crumb at the same time, thus eliminating the need for first forming an A-side and B-side, combining the A-side and B-side, and then adding the combined A-side and B-side to the foam crumbs.
The following components can be used to produce Adhesive A:
Component Parts by wt.
RUBINATE~ 9041 isocyanate variable, depending on desired Index.
Voranol~ 3512 polyol 72.3 Dipropylene glycol 3.8 Dabco T45 catalyst 2.4 Caught RPO 21.5 Examples 1-15:
The components of each adhesive mixture were separately added to a cup and mixed with a tongue depressor for about 10 seconds until a homogeneous mixture was obtained.
The adhesive mixtures in~Examples 1-3 and 8-15 were applied to the foam crumb within 30 seconds after the completion of mixing. The adhesive mixtures in Examples 4-7 were prepared by adding the components to a cup, mixing the components, and then storing the mixture in an oven (40°C) for about 14 hours. The adhesive mixture was then removed from the oven and slowly poured over the foam crumb. The foam crumb was weighed and then transferred to a 30 gallon drum which served as a mixing vessel. A mixer blade was placed into the drum so that the mixer blade was about 1 inch from the bottom of the drum. The mixer was turned on to a rotation speed of about 282 rotations per minute and the mass of adhesive was slowly poured over the foam crumb. The foam crumb and adhesive were mixed for about 80 seconds. After about 80 seconds, the mixer was turned off and removed from the drum. The foam crumb coated with adhesive was then transferred to a mold where the foam crumb/adhesive mass was compressed and cured, as discussed below.
In each of the following Examples, 76 grams of the adhesive is blended with grams of foam crumb formed from a mixture of virgin polyether based polyurethane foam (about 546.4 grams), virgin polyester based polyurethane foam (about 102.5 grams), and reground rebond polyurethane foam (about 34.1 grams). The mixture of foam crumb and adhesive is compressed to form a block. Specifically, the mixture of foam crumb and adhesive is transferred to an about 17 inch by 17 inch aluminum mold. The mixture is then compressed using a mold plunger to an about two inch height and cured.
The preferred amount of the adhesive of the invention is 10% by weight (in 90%
by weight foam crumb). Adhesive is typically used at between 5% - 15% by weight in the re-bond foam industry.
In the examples below, the mixture of foam crumb and adhesive is compressed in the mold. The mold includes solid horizontal walls with perforated top and bottom plates. The perforated plates allow penetration of air or steam into the compressed foam sample, to promote cure of the adhesive. When air is employed for curing, the temperature of the air can vary from ambient up to about 170°C, preferably about 130°C.
The steam can be employed at ambient pressure or in an autoclave under a range of temperatures and pressures.
Examples 1-3 were generated using hot-air curing. Specifically, a heat gun (Master heat gun - model HG-751B, available from Master Appliance Corporation) was used to apply hot air to the compressed foam crumb/adhesive mixture. The heat gun was cycled as follows:
5 seconds of heating mixture and 15 seconds without heat. This cycling was repeated for 7 minutes and then the foam was demolded.
Examples 4-15 illustrate the resulting physical properties of re-bonded foam generated with conventional adhesives and adhesives according to the invention. All of these samples were cured with steam. Examples 8-11 show the resulting physical properties of the adhesives made with an aromatic diluent. Examples 12-15 show the resulting physical properties of the adhesives made with a napthenic diluent. Steam was used to cure all of adhesives in these examples.
Table I shows the weight percent of each component used to make the adhesive mixture for Examples 1-15, as well as certain test results from the foam samples obtained.
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The invention relates to adhesive compositions comprising a plurality of reactive components, and methods of producing bonded foam crumb products therefrom. All of the components are preferably liquids at the temperature of application, and more preferably all the components are homogeneous liquids at ambient temperature. Advantageously, the multicomponent adhesive compositions can be directly or catalytically polymerized in-situ on the foam crumb without the need to use an intermediate prepolymer. The in-situ polymerization may be accomplished with steam, electromagnetic energy, or hot air. The adhesive compositions of the invention are not restricted by isocyanate value or prepolymer viscosity as in the prior art. Moreover, the prior art requires that an "A-side" (isocyanate component) and a "B-side" (polyol component) be separately prepared, mixed together, and then added to the foam crumbs. In an aspect of the invention, each component used can be added directly into a mass of foam crumbs without the need for making an A-side and B-side.
The use of moisture or steam to cure the adhesive is not required, and is generally less preferred than other methods of cure (such as the use of hot air or electromagnetic radiation).
In addition to the above noted advantages, the multicomponent adhesive compositions of the invention are less constrained, as compared to the prior art, in regard to the ranges of molecular weight or functionality of the flexibilizing polyols or the monomeric (base) polyisocyanates which can be used. Likewise, the flexibilizing polyol and the monomeric (base) polyisocyanate can be combined in virtually any desired ratio by using the multicomponent approach according to the invention. Moreover, if the energy source for curing the multicomponent adhesive is hot air or electromagnetic energy, then the need for an extra process step to remove moisture from the cured re-bond foam product is eliminated.
In an aspect of the invention, an isocyanate, polyol and optional oil are mixed in the presence of a metal catalyst and/or an amine type catalyst to produce an adhesive composition which can be polymerized with or without steam. The adhesive compositions are particularly suited for bonding of polyurethane foam crumb. The adhesive according to the invention is formulated and can be applied to the foam crumbs as two or more separate reactive components. The preferred mode is to use two separate reactive components, although any number of reactive components may be used if desired. In this preferred mode, the flexible polyol and the catalyst are combined into one component. The second component is the monomeric (base) polyisocyanate. The optional process oil, if used, may be combined with either or both of these two reactive components. The separate reactive components of the multicomponent adhesive may be added simultaneously or separately to the same mass of foam crumbs, in any desired overall amounts, or in any ratio with respect to each other. It is preferred that all the separate reactive components are added to the same mass of foam crumbs to be bonded. In a preferred mode all the reactive components are added simultaneously to the same mass of foam crumbs. In another embodiment the separate reactive ingredients may be pre-mixed immediately before application to the foam crumbs, under the proviso that significant reaction of the separate components does not occur in the pre-mix before the pre-mix is applied to the foam crumbs. If such a pre-mix is used, then less than 50% of the reactive isocyanate or isocyanate-reactive functional groups initially present should have reacted before the pre-mix is applied to the foam crumbs, preferably less than 40%, more preferably less than 30%, still more preferably less than 25%, and most preferably less than 20%. If the reaction of the separate ingredients in such a pre-mix is too far advanced at the time of application, it may become physically impossible to S apply the adhesive to the foam crumbs. If this reaction is too far advanced at the time the adhesive treated foam crumbs are compressed in the mold, then the adhesive may not bond the foam particles effectively and a poor quality product will result.
A particularly advantageous variant of the pre-mix method is to employ a multicomponent metering machine to meter together and mix the various components of the adhesive and then immediately apply the reacting mixture to the mass of foam crumbs. The reacting mixture may, for example, be applied to the foam crumbs by spraying or by means of a spinning disk applicator. The foam crumbs thus treated may preferably be tumbled while the reacting adhesive mixture is applied, or immediately thereafter, in order to maximize the distribution of the adhesive onto the foam crumbs.
A further advantage of the present invention is that bonded foam crumb products can be produced in surprisingly short cycle times. In this regard curing of the adhesive composition can occur in less than 30 minutes (measured from the time the press is closed) with or without the application of steam. More preferably curing occurs in less than 1 S
minutes and even more preferably curing can occur in less than 10 minutes. In an aspect of the invention curing of the adhesive can occur in from 1 to 10 minutes and, more preferably, in from 3 to 5 minutes.
MATERIALS:
Isocyanate Component:
The multicomponent adhesives of the invention comprise at least one isocyanate component. The isocyanate component comprises at least one organic compound wherein the organic compound contains a plurality of isocyanate groups. The preferred isocyanate compounds are monomeric (base) polyisocyanates.
Organic monomeric polyisocyanates which are useful as the isocyanate components in the context of the invention include aromatic, aliphatic and cycloaliphatic diisocyanates and polyisocyanates and combinations of these types.
Aromatic diisocyanates which may be used include 4,4'MDI, 3,3'-dimethyl-4,4'-diphenylenediisocyanate, 3,3'-dimethoxy-4,4'-bisphenylenediisocyanate, 3,3'-diphenyl-4,4'-biphenylenediisocyanate, 4,4'-biphenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, toluene diisocyanate, and 1,5-naphthalene diisocyanate. MDI isocyanates are preferred. Polymeric MDI having about 31.5% NCO and about 2.7 functionality is most preferred. Polymeric MDI is a combination of monomeric isocyanates which includes 4,4'-MDI, lesser amounts of 2,4'-MDI, minor amounts of 2,2'-MDI, and a mixture of 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 high functionality polymethylene polyphenyl polyisocyanate monomer species. Polymeric MDI is prepared by the phosgenation of mixed aromatic amines obtained from the condensation of aniline with formaldehyde. The preparation of polymeric MDI is well known in the art. It is also within the invention to use blends of polymeric MDI with additional amounts of diphenylmethane diisocyanates, particularly 4,4'-MDI. These blends will have number averaged isocyanate functionalities of from greater than 2.0 up to about 2.7, depending upon the ratio of the diphenylmethane diisocyanates to the polymethylene polyphenyl polyisocyanates in the blend.
Aliphatic isocyanates which 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-1,6-hexamethylene diisocyanate, and 1,12-dodecane diisocyanate.
Cycloaliphatic isocyanates which may be employed include but are not limited to cyclohexane-1,4-diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, 1-isocyanato-2-isocyanatomethyl cyclopentane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane (isophorone diisocyanate or IPDI), 2,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate.
Although it is preferred not to use prepolymers in this invention, it is within the scope of the invention to use as one or more components of the multicomponent adhesive composition an isocyanate terminated prepolymer. If an isocyanate terminated prepolymer is used as a component of the adhesive formulation, it is preferable that the prepolymer have a relatively high free isocyanate content. Preferably the prepolymer, if used at all, has an free isocyanate content of greater than 10% by weight, and more preferably greater than 15% by weight.
Isoc~anate Reactive Component:
The multicomponent adhesive formulations of the invention comprise at least one isocyanate reactive component. The isocyanate reactive component contains at least one organic compound having a plurality of isocyanate reactive groups. The preferred isocyanate reactive compounds are polyols. The isocyanate reactive component may optionally include water in addition to the organic isocyanate reactive ingredients, although it is preferable not to include water.
Suitable organic polyols useful for making the adhesive compositions of the invention include polyether, polyester, or amine polyols having a molecular weight range of about 50 to about 15,000 and a nominal functionality of about 1.0 to about 7.0, preferably polyether polyols with a molecular weight range of about 50 to about 6,000 and a nominal functionality of about 2.0 to about 3Ø Examples of useful polyols include but are not limited to ethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, diethylene glycol, triethylene glycol, glycerol, trimethylolpropane, triethanolamine, diethanolamine, triisopropanolamine, diisopropanolamine, butanediol, butenediol, butynediol, N-methyl diethanolamine, Rubinol~ F459, Rubinol~ F455 (both from Huntsman Polyurethanes) Arcol~
3022, Arcol~ 3128 (both from Lyondell Corporation), Voranol~ 220-028 (from Dow Chemical Corporation) and Pluracol~ P-2010 (from BASF Corporation). Other isocyanate reactive active hydrogen containing species which may be used include, but are not limited to, diethyltoluene diamine, and N-N,-di-sec-butyl-4,4'-diaminodiphenylmethane.
Simple polyols, containing only organic -OH groups as reactive termini, are preferred. The most preferred polyols contain primary or secondary -OH groups. Primary -OH groups are most preferred.
Rigid polyols also may be employed. Examples of rigid polyols which may be employed include but are not limited to Rubinol~ 8015, Rubinol~ 8180, and Rubinol~ 8260.
(from Huntsman Polyurethanes). These polyols have a functionality of about 2 to about 7 and a molecular weight from about 200 to about 1000.
The preferred polyols are flexible polyols, which contribute a flexibilizing effect to the cured adhesives. Useful flexible polyols have a molecular weight of about 300 to about 10,000, preferably 400 to about 8000, more preferably 1000 to about 6000, and a nominal functionality of about 1.0 to about 6.0, preferably about 2.0 to about 4Ø
Examples of flexible polyols which may be employed include, but are not limited to, Rubinol~ 459 and Rubinol~
455 (from Huntsman Polyurethanes).
Polyether and polyester flexible polyols which may be employed include primary or secondary hydroxyl groups.
Suitable polyether polyols which can be employed as the isocyanate reactive component include those which are prepared by reacting alkylene oxides, halogen-substituted or aromatic-substituted alkylene oxides or mixtures thereof with an active hydrogen-containing initiator compound.
Suitable oxides include, for example, ethylene oxide, propylene oxide, 1,2-butylene oxide, styrene oxide, epichlorohydrin, epibromohydrin, and mixtures thereof.
Suitable initiator compounds include water, ethylene glycol, propylene glycol, butanediol, hexanediol, glycerine, trimethylol propane, pentaerythritol, hexanetriol, sorbitol, sucrose, hydroquinone, resorcinol, catechol, bisphenols, novolac resins, phosphoric acid and mixtures thereof.
Suitable initiators further include, for example, ammonia, ethylenediamine, diaminopropanes, diaminobutanes, diaminopentanes, diaminohexanes, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentamethylenehexamine, ethanolamine, aminoethylethanolamine, aniline, 2,4-toluenediamine, 2,6-toluenediamine, 2,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 1,3-phenylenediamine, 1,4-phenylenediamine, naphthylene-1,5-diamine, triphenylmethane 4,4',4"-triamine, 4,4'-di(methylamino)diphenylmethane, 1,3-diethyl-2,4-diaminobenzene, 2,4-diaminomesitylene, 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1,3,5-triethyl-2,6-diaminobenzene, 3,5,3', 5'-tetra-ethyl-4,4'-diamino-diphenylmethane, and amine aldehyde condensation products such as the polyphenylpolymethylene polyamines produced from aniline and formaldehyde and mixtures thereof.
Polyester polyols which may be employed 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 acid anhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic acid anhydride, tetrachlorophthalic acid anhydride, endomethylene tetrahydrophtalic acid anhydride, glutaric acid anhydride, malefic acid, malefic acid anhydride, 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 and mixtures thereof.
Typically, polyether nominal triols or polyester nominal triols which have a molecular weight of about 3,000 to about 3,500 are used. Diols may also be used. Blends of these polyols also may be employed. Polyether polyols are more preferred. The most preferred polyether polyols are based on propylene oxide, optionally in combination with minor amounts of ethylene oxide. Examples of these most preferred types of polyether polyols include Arcol~ 3022 (from Lyondell Corporation) and Voranol~ 3512 (from Dow Chemical Corporation).
Examples of amine terminated polyols which may be employed include but are not limited to JEFFAMINE~ amine terminated polyether polyols from Huntsman Petrochemicals Corporation.
Mixtures of different polyols may optionally be used. For example, mixtures of relatively high molecular weight polyols and relatively low molecular weight di or polyfunctional active hydrogen compounds may be used as an isocyanate reactive component in the practice of the invention.
The multicomponent adhesive compositions employed in the invention may comprise a catalyst for the reaction of the isocyanate reactive component with the isocyanate component. The catalysts may not be essential in all cases, but are usually preferred. In a particularly preferred embodiment the catalyst is blended together with all isocyanate reactive ingredients to form a single isocyanate reactive component.
Suitable catalysts for use in the adhesive formulations of the invention include but are not limited to triethylene diamine, bis-2-(N,N-dimethylamino)-diethyl ether, 2-(N,N-dimethylamino) ethanol, N-hexadecyl dimethylamine, N,N-dimethylamino propylamine, triethanolamine, triisopropanolamine, N,N-dimethyl cyclohexylamine, 3-(N,N-dimethyl amino)-propionamide, dibutyl tin dilaurate, alkyl tin mercaptide complexes, 2-ethyl hexanoic acid (octoic acid) potassium salt, potassium acetate, potassium oleate, combinations of these, and the like. The catalysts may also include acid blocked amines, an example of which is Dabco~ 8154 (from Air Products and Chemicals Corporation). A preferred catalyst for use in combination with hot air curing is Dabco~ T-45. This catalyst is believed to be a solution of potassium 2-ethyl hexanoate in dipropylene glycol, and is commercially available from Air Products and Chemicals Corporation. In the case of triethanolamine, triisopropanolamine, and other tertiary amine initiated polyols, the polyol and the catalyst ingredients may be the same chemical species.
Suitable diluents for use in the adhesive formulations of the invention include but are not limited to processing oils such as naphthenic, aromatic, and paraffinic oils, natural oils such as vegetable oils, or any blend of these. Napthenic process oils are preferred. Suitable diluents may include methylene chloride, ketone-based solvents, propylene carbonate, mixtures of these, and the like.
In a particularly preferred embodiment of the invention there are only two components to the adhesive system used. One component is a monomeric (base) 5 polyisocyanate composition. The other component is a blend of all the liquid or soluble isocyanate reactive compounds, catalysts, diluents, and any additional optional additives to the adhesive. Both components are preferably homogeneous liquids at ambient temperature (i.e., 25°C). It is, however, within the scope of the invention to use one or more liquid components that are not fully homogeneous, with the proviso that any inhomogeneous 10 ingredients are dispersed in a liquid component.
The relative proportions of the various components of the multicomponent adhesive system, and of the various ingredients to each component, may be adjusted in order to fine tune the properties of the final adhesive bonded foam product. A particularly advantageous feature of the instant invention is the absence of restrictions imposed due to handling requirements of the relative amounts of isocyanate and isocyanate reactive monomers that may be employed in the adhesive composition of the invention. Indeed, the effective "isocyanate index" (also known as "Index") of the adhesive formulation may take on any value. The isocyanate index is the ratio of isocyanate groups to isocyanate reactive groups in the formulation, and is usually expressed as a percent. A value of greater than 100% means that excess isocyanate is used (referred to as "over index"). A value of less than 100% means that excess isocyanate reactive material is used (referred to as "under index"). A value of 100% is indicative of an exact stoichiometric balance between the isocyanate and isocyanate reactive material in the adhesive formulation. Good re-bonded foam products can be prepared by using the multicomponent adhesives of the invention, at index values of less than 100%, at greater than 100%, or at exactly 100%. By contrast, using the prior art one-component (isocyanate terminated prepolymer) rebond adhesives, it is only possible to make re-bonded foam products at index values considerably above 100%. These prior art systems depend on moisture (usually in the form of steam) to react out the excess isocyanate groups present. This can result in undesirable properties (due to the high levels of urea linkages present in the cured adhesive) and problems with drying the re-bonded foam product, as described hereinabove.
Additional ingredients can be included in the adhesive formulations of the invention.
Examples of these additional ingredients include but are not limited to non-reactive chemicals such as trischloropropylphosphate or other fire retardants, dyes or colorants, wood or cellulosic fibers, rubber or elastomer particles, other inert fillers, mixtures of these and the like. These optional additional inert ingredients, if used at all, may be pre-mixed with any of the essential ingredients in any desired proportion prior to forming the reacting adhesive mixture. They may alternatively be combined with the other ingredients in the final mixing step, just prior to application of the reaction mixture to the foam crumbs.
The adhesive formulations may be employed with a variety of foam crumb types to produce bonded foam crumb products. Examples of types of foam crumb which may be used include polyether urethane foam crumb, polyester urethane foam crumb, reground rebond, cloth and foam from automotive recyclate, bedding process scrap, rubber process scrap, I O molded foam process scrap, post-consumer recyclate, slabstock process scrap. Blends of different types of foam crumb also may be used. Examples of useful foam blends include rigid foam with flexible foam, polyether urethane based foam with polyester urethane based foam and polyisocyanurate based foam.
The foam crumbs may also be combined with other solid additives prior to or 15 simultaneously with the application of the adhesive composition. Solid additives to the foam crumbs may include solid fire retardants such as melamine, ammonium polyphosphate, antimony oxide, alumina trihydrate, mixtures of these, and the like. The foam crumbs may also be combined with cellulosic or lignocellulosic particulate or fibrous materials as extenders. The foam crumbs may also be extended with inorganic fibrous materials such as 20 glass fibers, glass mats, mineral wool, and the like. Likewise, the foam crumbs may be combined with organic fibrous materials such as textile scraps, carpet scraps, and the like.
Also, it has been found effective to add calcium carbonate to the foam crumbs to increase the density of the obtained foam pad.
The invention will now be described by reference to the following non-limiting 25 examples. All amounts are expressed in weight percent based on the total weight of the composition.
EXAMPLES:
One composition of an adhesive according to the invention is shown below as 30 Adhesive A. It can be prepared by hand mixing 50 grams (total of all components used to form the adhesive) of adhesive with a tongue depressor, for about 10 seconds in a 4 ounce paper cup. The isocyanate can be added in an amount appropriate to produce the desired Index. In an aspect of the invention, all of the components can be added to the foam crumb at the same time, thus eliminating the need for first forming an A-side and B-side, combining the A-side and B-side, and then adding the combined A-side and B-side to the foam crumbs.
The following components can be used to produce Adhesive A:
Component Parts by wt.
RUBINATE~ 9041 isocyanate variable, depending on desired Index.
Voranol~ 3512 polyol 72.3 Dipropylene glycol 3.8 Dabco T45 catalyst 2.4 Caught RPO 21.5 Examples 1-15:
The components of each adhesive mixture were separately added to a cup and mixed with a tongue depressor for about 10 seconds until a homogeneous mixture was obtained.
The adhesive mixtures in~Examples 1-3 and 8-15 were applied to the foam crumb within 30 seconds after the completion of mixing. The adhesive mixtures in Examples 4-7 were prepared by adding the components to a cup, mixing the components, and then storing the mixture in an oven (40°C) for about 14 hours. The adhesive mixture was then removed from the oven and slowly poured over the foam crumb. The foam crumb was weighed and then transferred to a 30 gallon drum which served as a mixing vessel. A mixer blade was placed into the drum so that the mixer blade was about 1 inch from the bottom of the drum. The mixer was turned on to a rotation speed of about 282 rotations per minute and the mass of adhesive was slowly poured over the foam crumb. The foam crumb and adhesive were mixed for about 80 seconds. After about 80 seconds, the mixer was turned off and removed from the drum. The foam crumb coated with adhesive was then transferred to a mold where the foam crumb/adhesive mass was compressed and cured, as discussed below.
In each of the following Examples, 76 grams of the adhesive is blended with grams of foam crumb formed from a mixture of virgin polyether based polyurethane foam (about 546.4 grams), virgin polyester based polyurethane foam (about 102.5 grams), and reground rebond polyurethane foam (about 34.1 grams). The mixture of foam crumb and adhesive is compressed to form a block. Specifically, the mixture of foam crumb and adhesive is transferred to an about 17 inch by 17 inch aluminum mold. The mixture is then compressed using a mold plunger to an about two inch height and cured.
The preferred amount of the adhesive of the invention is 10% by weight (in 90%
by weight foam crumb). Adhesive is typically used at between 5% - 15% by weight in the re-bond foam industry.
In the examples below, the mixture of foam crumb and adhesive is compressed in the mold. The mold includes solid horizontal walls with perforated top and bottom plates. The perforated plates allow penetration of air or steam into the compressed foam sample, to promote cure of the adhesive. When air is employed for curing, the temperature of the air can vary from ambient up to about 170°C, preferably about 130°C.
The steam can be employed at ambient pressure or in an autoclave under a range of temperatures and pressures.
Examples 1-3 were generated using hot-air curing. Specifically, a heat gun (Master heat gun - model HG-751B, available from Master Appliance Corporation) was used to apply hot air to the compressed foam crumb/adhesive mixture. The heat gun was cycled as follows:
5 seconds of heating mixture and 15 seconds without heat. This cycling was repeated for 7 minutes and then the foam was demolded.
Examples 4-15 illustrate the resulting physical properties of re-bonded foam generated with conventional adhesives and adhesives according to the invention. All of these samples were cured with steam. Examples 8-11 show the resulting physical properties of the adhesives made with an aromatic diluent. Examples 12-15 show the resulting physical properties of the adhesives made with a napthenic diluent. Steam was used to cure all of adhesives in these examples.
Table I shows the weight percent of each component used to make the adhesive mixture for Examples 1-15, as well as certain test results from the foam samples obtained.
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~ r O . G4 C C G a G
~ ~ ~ ~ ~ ~
~ '~
' .-1 O ~ V ~' h v~ n v1 N
O k G 'C y V ~ O ~ M ~p .y M U fn !nC H
Q, fn y y C
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,~ ~ .~ ~
w 8 ~ ' ~ ~ H
~ ~ ~
G~. ~ v~~i1U G1 c E E G v~ cn U ~ ~ n. ~ cn v~ ~ n o ~ o ~ E a o n c ~ . ~, W o A a o o o o o o Q Q Q Q Q Q
.N c ' Wv ~ C~ V U f=titA
w ov ~ " D
Claims (20)
1. A process for preparing a rebonded flexible foam article, said process comprising the steps of:
a) providing a mass of flexible foam crumbs;
b) providing a polyisocyanate having a free isocyanate group content of greater than 10% by weight;
c) providing a polyfunctional organic isocyanate-reactive material;
d) preparing a liquid reaction mixture by premixing said polyisocyanate and said polyfunctional organic isocyanate reactive material;
e) applying said liquid reaction mixture to said foam crumbs, to form a mass of adhesive treated flexible foam crumbs;
f) molding and curing said mass of adhesive treated foam crumbs under the influence of heat and pressure for a duration of less than 30 minutes to form a rebonded flexible foam article;
g) removing an intact rebonded flexible foam article from the mold;
wherein less than 50% of the reactive isocyanate groups or isocyanate-reactive functional groups initially present have reacted before the said liquid reaction mixture has been applied to the foam crumbs.
a) providing a mass of flexible foam crumbs;
b) providing a polyisocyanate having a free isocyanate group content of greater than 10% by weight;
c) providing a polyfunctional organic isocyanate-reactive material;
d) preparing a liquid reaction mixture by premixing said polyisocyanate and said polyfunctional organic isocyanate reactive material;
e) applying said liquid reaction mixture to said foam crumbs, to form a mass of adhesive treated flexible foam crumbs;
f) molding and curing said mass of adhesive treated foam crumbs under the influence of heat and pressure for a duration of less than 30 minutes to form a rebonded flexible foam article;
g) removing an intact rebonded flexible foam article from the mold;
wherein less than 50% of the reactive isocyanate groups or isocyanate-reactive functional groups initially present have reacted before the said liquid reaction mixture has been applied to the foam crumbs.
2. The process according to Claim 1, wherein the polyisocyanate consists predominantly on a weight basis of isocyanates of the MDI series, and has a free isocyanate group content of greater than 15% by weight.
3. The process according to Claim 1, wherein the polyisocyanate is a monomeric polyisocyanate which is devoid of prepolymers.
4. The process according to Claim 2, wherein less than 30% of the reactive isocyanate groups or isocyanate-reactive functional groups initially present have reacted before the liquid reaction mixture has been applied to the foam crumbs.
5. The process according to Claim 2, wherein less than 20% of the reactive isocyanate groups or isocyanate-reactive functional groups initially present have reacted before the said liquid reaction mixture has been applied to the foam crumbs.
6. The process according to Claim 1, wherein the molding and curing step is achieved without the use of added steam or moisture.
7. The process according to Claim 6, wherein the polyfunctional organic isocyanate-reactive component is essentially free of water.
8. The process according to Claim 7, which is conducted in the substantial absence of moisture or steam.
9. The process according to Claim 1, wherein no drying of the rebonded foam article is required.
10. The process according to Claim 1, wherein the polyfunctional organic isocyanate-reactive material consists predominantly on a weight basis of one or more flexible polyols of number averaged molecular weight from 400 to 8000 and nominal functionality 2 to 4.
11. The process according to Claim 10, wherein the polyfunctional organic isocyanate-reactive material contains a minor amount of a weight basis of a process oil, the process oil being essentially free of isocyanate-reactive groups.
12. The process according to Claim 10, wherein the polyfunctional organic isocyanate-reactive material contains an effective amount of at least one catalyst.
13. The process according to Claim 12, wherein the catalyst comprises an alkali salt of a carboxylic acid.
14. The process according to Claim 12, wherein the catalyst comprises potassium 2-ethyl hexanoate.
15. The process according to Claim 10, wherein the polyfunctional organic isocyanate-reactive material contains a minor amount of a weight basis of an organic diol or triol or molecular weight less than 400.
16. The process according to Claim 15, wherein the organic diol or triol is a diol of molecular weight less than 250.
17. The process according to Claim 16, wherein the diol is dipropylene glycol.
18. The process according to Claim 9, wherein curing of the adhesive treated foam crumb mass is achieved by the application of a stream of hot air to the adhesive treated mass during the molding thereof.
19. The process according to Claim 1, wherein the flexible foam crumbs are derived from flexible polyurethane foam.
20. The rebonded flexible foam article prepared according to the process of any of Claims 1, 2, 3, 5, 9, 13, 18, or 19, wherein the demold time is less than 15 minutes.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US27901301P | 2001-03-27 | 2001-03-27 | |
| US60/279,013 | 2001-03-27 | ||
| PCT/US2002/008753 WO2002077083A2 (en) | 2001-03-27 | 2002-03-22 | In-situ polymerization on recycled foam fragments |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2440608A1 true CA2440608A1 (en) | 2002-10-03 |
Family
ID=23067308
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002440608A Abandoned CA2440608A1 (en) | 2001-03-27 | 2002-03-22 | In-situ polymerization on recycled foam fragments |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU2002252454A1 (en) |
| CA (1) | CA2440608A1 (en) |
| MX (1) | MXPA03008290A (en) |
| WO (1) | WO2002077083A2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DK2109637T3 (en) | 2007-01-16 | 2018-11-12 | Frank Prissok | HYBRID SYSTEMS OF FOAMED THERMOPLASTIC ELASTOMERS AND POLYURETHANES |
| WO2020068508A1 (en) | 2018-09-25 | 2020-04-02 | Lanxess Solutions Us Inc. | Rebonded polyurethane foam |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2719714A1 (en) * | 1977-05-03 | 1978-11-09 | Wolfgang Hippmann | Light wt. slabs filled with ground rigid polyurethane foam - using a matrix resin to obtain a smooth uniform structure |
| US4438248A (en) * | 1982-12-20 | 1984-03-20 | Basf Wyandotte Corporation | Trimerization catalysts and organo-mercury compounds as co-catalysts for the preparation of noncellular polyurethane elastomers |
| GB9410460D0 (en) * | 1994-05-25 | 1994-07-13 | Arco Chem Tech | Manufacture of low density products containing recycled foam |
-
2002
- 2002-03-22 MX MXPA03008290A patent/MXPA03008290A/en not_active Application Discontinuation
- 2002-03-22 AU AU2002252454A patent/AU2002252454A1/en not_active Abandoned
- 2002-03-22 CA CA002440608A patent/CA2440608A1/en not_active Abandoned
- 2002-03-22 WO PCT/US2002/008753 patent/WO2002077083A2/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| WO2002077083A2 (en) | 2002-10-03 |
| WO2002077083A3 (en) | 2003-04-03 |
| MXPA03008290A (en) | 2003-12-11 |
| AU2002252454A1 (en) | 2002-10-08 |
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| Date | Code | Title | Description |
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| FZDE | Discontinued |