Uncured articles with improved shelf-life

Abstract

Disclosed are formaldehyde-free, thermally-curable, alkaline, aqueous binder compositions. Also disclosed are compositions comprising formaldehyde-free, thermally-curable binder compositions, as described herein, applied to non-woven fibers. Uses of the disclosed binder compositions as binders for non-woven fibers are also disclosed.

Description

TECHNICAL FIELD

This invention relates to binders and binder technology applicable in the preparation of compositions that include non-woven fibers. More particularly, the present invention relates to uncured mineral wool, i.e., uncured glass wool (fiberglass) and/or uncured stone wool, products (articles) prepared with formaldehyde-free binders that are cured (e.g., by molding) in a secondary step after the corresponding uncured products are collected.

BACKGROUND

So called “shipout uncured” and “plant uncured” fiberglass insulation is manufactured with an uncured, thermosetting binder. The resulting uncured insulation products are collected, packaged into rolls, bagged, and sealed in plastic bags. At various times thereafter, the bagged insulation material is i) transported to, ii) stored at, and iii) ultimately processed via a distinct separate manufacturing sequence by, a customer to yield a finished part. This manufacturing sequence includes heat curing of the binder. The time between collection of the uncured product and curing the binder can span several days to several weeks. In the case of “shipout uncured” fiberglass insulation, the uncured product is transported to customers that require the product to have a long shelf-life during ambient storage and transportation conditions. Ideally, “shipout uncured” fiberglass insulation has a minimum shelf-life of 2 to 4 weeks.

Standard binder for “shipout uncured” and “plant uncured” fiberglass insulation has historically been based on phenol-formaldehyde (PF) binder chemistry. PF binders exhibit the disadvantage of formaldehyde emissions. Binders based on reducing sugar carbohydrates for cured product lines are known in the art. Due to an increasingly uncertain regulatory situation as it pertains to the use of formaldehyde-containing binders and/or formaldehyde-liberating products, there has been steadily increasing interest in, if not demand for, a sustainable, formaldehyde-free binder based on carbohydrates for “shipout uncured” and “plant uncured” fiberglass insulation. Heretofore, the prior art has not described such a binder, or an equivalent binder composition, for such uncured fiberglass insulation products.

Initial trials aimed at discovering a carbohydrate-based binder for uncured fiberglass insulation product lines involved dextrose as the carbohydrate source. The resulting uncured product rolls displayed major disadvantages, which included the fact that: a) the dextrose-based binder crystallized out and caused poor loft and poor recovery when unrolling the fiberglass rolls, b) the dextrose-based binder migrated to the glass surface and segregated out into binder “islands,” which islands were noticeable after curing/molding as a darkly-colored dotted pattern, c) due to binder migration, the inner part of the fiberglass layer was depleted of binder whereas the outer pelt surface was binder rich, which depletion caused weakened integrity of the cured/molded product whereas binder enrichment and crystallization on the pelt surface resulted in poor handling characteristics when molding (i.e., binder rich areas tended to stick to the mold platens, which often resulted in the destruction of the molded part when removing it from the platen), and d) when a permeable membrane (e.g., non-woven glass veil) was used, binder rich spots often bled through the veil upon molding.

OBJECTS OF THE INVENTION

One object of the present invention is to provide a carbohydrate-based binder that enables the manufacture of uncured fiberglass insulation products with good shelf-life during ambient transportation and storage conditions (e.g., in winter and summer; in northern and southern climate).

Another object of the present invention is to provide a carbohydrate-based binder that does not significantly and/or noticeably migrate within finished uncured fiberglass insulation products with concomitant localized depletion of binder.

Another object of the present invention is to provide a carbohydrate-based binder that does not crystallize out in finished uncured fiberglass insulation products and thereby form dotted patterns therein after cure.

Yet another object of the present invention is to provide a carbohydrate-based binder that does not significantly and/or noticeably migrate within finished uncured fiberglass insulation products with concomitant localized enrichment of binder.

SUMMARY

One aspect of the present invention provides a carbohydrate-based binder in accordance with claim 1; the dependent claims define alternative and/or preferred embodiments.

In another illustrative aspect, the present invention provides a carbohydrate-based binder solution comprising a mixture of carbohydrates, an acid precursor derivable from an inorganic salt and/or an ammonium salt of one or more polycarboxylic acids, a source of nitrogen, and optionally ammonia.

In another illustrative aspect, the present invention provides a binder based on a mixture of carbohydrates that has a tendency to generate supersaturated aqueous solutions of sugars that do not crystallize out while storing at ambient conditions over a time span of at least 3 days, preferably over a time span of longer than 2 weeks even when in contact with fiberglass.

In another illustrative aspect, the present invention provides for a carbohydrate-based binder wherein the mixture of sugars in the binder has a lower crystallization point than dextrose.

In another illustrative aspect, the present invention provides for a carbohydrate-based binder wherein the mixture of sugars is fructose and dextrose present in high fructose corn syrup (HFCS), which is used as a carbohydrate source.

In another illustrative aspect, the present invention provides for a carbohydrate-based binder which permits close control of the ratio of moisture to binder concentration in a fiberglass product.

In another illustrative aspect, the present invention provides for a carbohydrate-based binder where impurities may be added to mixtures of fructose and dextrose (e.g., mixtures obtained by dissolving fructose and dextrose or by inverting sucrose under known conditions to invert sugar). Such impurities may be dextrins and/or maltodextrins. Another form of impurities can be generated by heating tcarbohydrate solutions to form some degradation products.

In another illustrative aspect, the present invention provides for a carbohydrate-based binder where various additives may be added to improve binder performance and processability. Typical additives known in the art include, but are not necessarily limited to, adhesion promoters, coupling agents, silanes, amino-silanes, silicones, non-aqueous moisturizers, flame retardants, additives to prevent self-heating upon curing, dedusting oils, polymeric additives (e.g., styrene-maleic anhydride copolymers, acrylic copolymers), and cross-linkers (e.g., mono-, di-, and polyfunctional amines, epoxides, isocyanates, blocked isocyanates, hydroxyl-containing compounds, and carboxy-containing compounds, as well as aldehyds and ketones.)

In another illustrative aspect, a method for treating fibers, including non-woven fibers, is enabled that includes contacting mineral fibers (e.g., glass fibers) with a thermally-curable, aqueous binder composition comprising a mixture of carbohydrates, an acid precursor derivable from an inorganic salt and/or an ammonium salt of one or more polycarboxylic acids, a source of nitrogen, and optionally ammonia, as described herein, and effecting removal of most of the water from the thermally-curable, aqueous binder composition in contact with mineral fibers.

In another illustrative aspect, a fiberglass product is described that includes a binder composition, as described herein, in contact with glass fibers, which product may be processed to form one of several types of uncured fiberglass insulation, wherein the glass fibers are present in the range from about 80% to about 99% by weight.

Binder solutions used in accordance with the present invention may be “substantially formaldehyde free”, that is to say that they liberate less than 5 ppm formaldehyde as a result of drying and/or curing (or appropriate tests simulating drying and/or curing). Such binder solutions are preferably “formaldehyde free”, that is the say they liberate less than 1 ppm formaldehyde in such conditions.

Products in accordance with the present invention (for example, uncured fiberglass insulation materials) may be “substantially formaldehyde free;” that is to say that they comprise less than 5 ppm or less than detectable limits of free formaldehyde and/or consist of materials which together comprise less than these amounts of free formaldehyde and/or release levels of formaldehyde in standardized tests adapted to simulate their ordinary use which allows them to be classified as having no or undetectable levels of formaldehyde release. Preferably, such products release less than 10 μg/m³, more preferably less than 5 μg/m³, of formaldehyde during the period of 24-48 hours from the start of testing in accordance with ISO 16000.

Additional features of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of illustrative embodiments exemplifying the best mode of carrying out the invention as presently perceived.

DETAILED DESCRIPTION

It has been found that binders according to the present invention may have at least equivalent and, in some instances, improved properties compared to, for example, the tri-ammonium citrate-dextrose system of WO 2007/014236 and compared to, for example, the triammonium phosphate-dextrose system of WO 2009/019235. WO 2007/014236 teaches binder systems based, inter alia, on a combination of a carbohydrate (for example, a reducing sugar), ammonia and a polycarboxylic acid and suggests that a Maillard type reaction may form the basis of the curing chemistry. WO 2009/019235 teaches binder systems based, inter alia, on a combination of a carbohydrate (for example, a reducing sugar), an acid precursor derivable from an inorganic salt, and ammonia and suggests that a Maillard type reaction may form the basis of the curing chemistry. It would have been thought that inclusion of a mixture of at least two carbohydrates would not have a significant effect on the properties of the resulting uncured binder, particularly if the carbohydrates are both reducing sugars. It is thus surprising that a mixture of at least two carbohydrates (e.g., dextrose and fructose) should provide improved properties in an otherwise apparently similar binder system.

Use of an acid precursor derivable from an inorganic salt may have significant advantages in terms of cost, availability and ease of handling. The acid precursor derivable from an inorganic salt of the binder solution may comprise a species selected from the group consisting of sulfates, phosphates, nitrates and carbonates. A particular advantage can be achieved by use of one or more inorganic ammonium salts, for example, an ammonium sulfate, an ammonium phosphate or an ammonium carbonate salt. An ammonium salt may provide the or part of the acid precursor and/or the or part of the source of nitrogen and/or the or part of a pH control system. An ammonium nitrate salt may also work; however, ammonium nitrate may oxidise aldehyde groups of the carbohydrate (for example, aldehyde groups in dextrose) and/or require precautions to avoid explosions.

Ammonium sulfate is particularly advantageous but ammonium phosphate may be used in addition to or instead of ammonium sulfate Ammonium phosphate may be monoammonium phosphate, diammonium phosphate or triammonium phosphate; it may be an ammonium hydrogen phosphate. An ammonium carbonate, alone or in combination with the other materials disclosed herein, may also provide good results. The ammonium carbonate may be an ammonium bicarbonate.

The acid precursor, particularly when this consists essentially of inorganic ammonium salt(s), may make up at least 5%, preferably at least 7%, more preferably at least 9% by dry weight of the uncured binder solution; and/or less than 25% or 20%, preferably less than 18%, more preferably less than 16% by dry weight of the uncured binder solution.

The term “consist or consisting essentially of” is intended to limit the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the claimed invention.

The acid may comprise: a sulfuric acid, a phosphoric acid, a nitric acid or a weak acid.

The binder may comprise between 5% and 25%, preferably 10% to 20%, more preferably 15% to 20% by dry weight of acid precursor (particularly where this is an inorganic ammonium salt) to total carbohydrate (particularly when this is a mixture of reducing sugars).

A carbohydrate-based binder comprising a mixture of carbohydrates, as described herein, may alternatively or in addition contain an ammonium salt of one or more polycarboxylic acid components, where the salt is monobasic or dibasic when the polycarboxylic acid component is a dicarboxylic acid, or where the salt is monobasic, dibasic, or tribasic when the polycarboxylic acid component is a tricarboxylic acid, and so on and so forth.

As used herein, the term “ammonium” includes, but is not limited to, ⁺NH₄, ⁺NH₃R¹ and ⁺NH₂R¹R², where R¹ and R² are each independently selected in ⁺NH₂R¹R², and where R¹ and R² are selected from alkyl, cycloalkyl, alkenyl, cycloalkenyl, heterocyclyl, aryl, and heteroaryl.

The term “alkyl” refers to a saturated monovalent chain of carbon atoms, which may be optionally branched; the term “cycloalkyl” refers to a monovalent chain of carbon atoms, a portion of which forms a ring; the term “alkenyl” refers to an unsaturated monovalent chain of carbon atoms including at least one double bond, which may be optionally branched; the term “cycloalkenyl” refers to an unsaturated monovalent chain of carbon atoms, a portion of which forms a ring; the term “heterocyclyl” refers to a monovalent chain of carbon and heteroatoms, wherein the heteroatoms are selected from nitrogen, oxygen, and sulfur, a portion of which, including at least one heteroatom, form a ring; the term “aryl” refers to an aromatic mono or polycyclic ring of carbon atoms, such as phenyl, naphthyl, and the like; and the term “heteroaryl” refers to an aromatic mono or polycyclic ring of carbon atoms and at least one heteroatom selected from nitrogen, oxygen, and sulfur, such as pyridinyl, pyrimidinyl, indolyl, benzoxazolyl, and the like. It is to be understood that each of alkyl, cycloalkyl, alkenyl, cycloalkenyl, and heterocyclyl may be optionally substituted with independently selected groups such as alkyl, haloalkyl, hydroxyalkyl, aminoalkyl, carboxylic acid and derivatives thereof, including esters, amides, and nitriles, hydroxy, alkoxy, acyloxy, amino, alkyl and dialkylamino, acylamino, thio, and the like, and combinations thereof It is further to be understood that each of aryl and heteroaryl may be optionally substituted with one or more independently selected substituents, such as halo, hydroxy, amino, alkyl or dialkylamino, alkoxy, alkylsulfonyl, cyano, nitro, and the like.

As used herein, the term “polycarboxylic acid” indicates a dicarboxylic, tricarboxylic, tetracarboxylic, pentacarboxylic, and like monomeric polycarboxylic acids, and anhydrides, and combinations thereof, as well as polymeric polycarboxylic acids, anhydrides, copolymers, and combinations thereof In one aspect, the polycarboxylic acid ammonium salt reactant is sufficiently non-volatile to maximize its ability to remain available for reaction with a mixture of carbohydrates in a Maillard reaction. In another aspect, the polycarboxylic acid ammonium salt reactant may be substituted with other chemical functional groups.

Illustratively, a monomeric polycarboxylic acid may be a dicarboxylic acid, including, but not limited to, unsaturated aliphatic dicarboxylic acids, saturated aliphatic dicarboxylic acids, aromatic dicarboxylic acids, unsaturated cyclic dicarboxylic acids, saturated cyclic dicarboxylic acids, hydroxy-substituted derivatives thereof, and the like. Or, illustratively, the polycarboxylic acid(s) itself may be a tricarboxylic acid, including, but not limited to, unsaturated aliphatic tricarboxylic acids, saturated aliphatic tricarboxylic acids, aromatic tricarboxylic acids, unsaturated cyclic tricarboxylic acids, saturated cyclic tricarboxylic acids, hydroxy-substituted derivatives thereof, and the like. It is appreciated that any such polycarboxylic acids may be optionally substituted, such as with hydroxy, halo, alkyl, alkoxy, and the like. In one variation, the polycarboxylic acid is the saturated aliphatic tricarboxylic acid, citric acid. Other suitable polycarboxylic acids are contemplated to include, but are not limited to, aconitic acid, adipic acid, azelaic acid, butane tetracarboxylic acid dihydride, butane tricarboxylic acid, chlorendic acid, citraconic acid, dicyclopentadiene-maleic acid adducts, diethylenetriamine pentaacetic acid, adducts of dipentene and maleic acid, ethylenediamine tetraacetic acid (EDTA), fully maleated rosin, maleated tall-oil fatty acids, fumaric acid, glutaric acid, isophthalic acid, itaconic acid, maleated rosin oxidized with potassium peroxide to alcohol then carboxylic acid, maleic acid, malic acid, mesaconic acid, biphenol A or bisphenol F reacted via the KOLBE-Schmidt reaction with carbon dioxide to introduce 3-4 carboxyl groups, oxalic acid, phthalic acid, sebacic acid, succinic acid, tartaric acid, terephthalic acid, tetrabromophthalic acid, tetrachlorophthalic acid, tetrahydrophthalic acid, trimellitic acid, trimesic acid, and the like, and anhydrides, and combinations thereof

Illustratively, a polymeric polycarboxylic acid may be an acid, for example, polyacrylic acid, polymethacrylic acid, polymaleic acid, and like polymeric polycarboxylic acids, copolymers thereof, anhydrides thereof, and mixtures thereof Examples of commercially available polyacrylic acids include AQUASET-529 (Rohm & Haas, Philadelphia, Pa., USA), CRITERION 2000 (Kemira, Helsinki, Finland, Europe), NF1 (H. B. Fuller, St. Paul, Minn., USA), and SOKALAN (BASF, Ludwigshafen, Germany, Europe). With respect to SOKALAN, this is a water-soluble polyacrylic copolymer of acrylic acid and maleic acid, having a molecular weight of approximately 4000. AQUASET-529 is a composition containing polyacrylic acid cross-linked with glycerol, also containing sodium hypophosphite as a catalyst. CRITERION 2000 is an acidic solution of a partial salt of polyacrylic acid, having a molecular weight of approximately 2000. With respect to NF1, this is a copolymer containing carboxylic acid functionality and hydroxy functionality, as well as units with neither functionality; NF1 also contains chain transfer agents, such as sodium hypophosphite or organophosphate catalysts.

With respect to the mixture of carbohydrates in the binder described herein, it may include a mixture of two or more reducing sugars. In one aspect, any carbohydrate in said mixture should be sufficiently nonvolatile to maximize its ability to remain available for reaction with the acid precursor derivable from an inorganic salt and/or the polycarboxylic acid ammonium salt. The carbohydrate mixture may include a monosaccharide in its aldose or ketose form, including a triose, a tetrose, a pentose, a hexose, or a heptose; or a polysaccharide; or combinations thereof A carbohydrate may be a reducing sugar, or one that yields one or more reducing sugars in situ under thermal curing conditions. For example, when a triose serves as the carbohydrate in combination with other reducing sugars and/or a polysaccharide, an aldotriose sugar or a ketotriose sugar may be utilized, such as glyceraldehyde and dihydroxyacetone, respectively. When a tetrose serves as the carbohydrate in combination with other reducing sugars and/or a polysaccharide, aldotetrose sugars, such as erythrose and threose; and ketotetrose sugars, such as erythrulose, may be utilized. When a pentose serves as the carbohydrate in combination with other reducing sugars and/or a polysaccharide, aldopentose sugars, such as ribose, arabinose, xylose, and lyxose; and ketopentose sugars, such as ribulose, arabulose, xylulose, and lyxulose, may be utilized. When a hexose serves as the carbohydrate in combination with other reducing sugars and/or a polysaccharide, aldohexose sugars, such as glucose (i.e., dextrose), mannose, galactose, allose, altrose, talose, gulose, and idose; and ketohexose sugars, such as fructose, psicose, sorbose and tagatose, may be utilized. When a heptose serves as the carbohydrate reactant in combination with other reducing sugars and/or a polysaccharide, a ketoheptose sugar such as sedoheptulose may be utilized.

One or more aldotriose sugars may be used in combination with one or more ketotriose sugars. One or more aldotetrose sugars may be used in combination with one or more ketotetrose sugars. One or more aldopentose sugars may be used in combination with one or more ketopentose sugars. One or more aldohexose sugars may be used in combination with one or more ketohexose sugars.

One or more aldotriose sugars may be used in combination with one or more ketotetrose sugars. One or more aldopentose sugars may be used in combination with one or more ketohexose sugars. One or more aldohexose sugars may be used in combination with one or more ketopentose sugars. One or more ketohexose sugars may be used in combination with one or more aldotetrose sugars. And so on and so forth.

Other stereoisomers of such carbohydrates not known to occur naturally are also contemplated to be useful in preparing the binder compositions as described herein. When a polysaccharide serves as a carbohydrate in combination with monosaccharides, sucrose, lactose, maltose, starch, and cellulose may be utilized.

Furthermore, the mixture of carbohydrates in the binder described herein may be used in combination with one or more non-carbohydrate polyhydroxy reactant. Examples of non-carbohydrate polyhydroxy reactants which can be used in combination with a mixture of carbohydrates include, but are not limited to, trimethylolpropane, glycerol, pentaerythritol, polyvinyl alcohol, partially hydrolyzed polyvinyl acetate, fully hydrolyzed polyvinyl acetate, and mixtures thereof In one aspect, the non-carbohydrate polyhydroxy reactant is sufficiently nonvolatile to maximize its ability to remain available for reaction with the acid precursor derivable from an inorganic acid and/or with a monomeric or polymeric polycarboxylic acid ammonium salt. It is appreciated that the hydrophobicity of the non-carbohydrate polyhydroxy reactant may be a factor in determining the physical properties of a binder prepared as described herein.

Commercial quality high fructose corn syrup, HFCS 42, which contains 42% fructose, may be used as the mixture of carbohydrates for the binders described herein. In one illustrative embodiment, the binder described herein may be derived essentially from HFCS and an inorganic ammonium salt in aqueous solution. In another illustrative embodiment, the binder described herein may alternatively or also comprise an ammonium salt of a polycarboxylic acid, particularly a dicarboxylic acid or tricarboxylic acid, preferably citric acid.

Binders which comprise or consist essentially of the components described herein may include additives, for example, additives selected from: silanes, mineral oils, coupling agents, silicones or siloxanes (particularly for water repellency), silicon containing compounds, surfactants, hydrophilic additives, hydrophobic additives, waxes, substances useful for controlling the pH (e.g. ammonium hydroxide) and ammonia. Ammonium hydroxide when used, and indeed other additives, may provide the and/or an additional source of nitrogen. Preferably, the total quantity of additives (excluding ammonia) is less than 5% by weight (excluding the weight of water present), more preferably less than 3% or less than 2% by weight. Particularly for mineral fiber products, it is preferred to include a silane as an additive. The binder and/or binder solution may comprise at least 0.1% and/or less than 1% of a silane by dry weight. The silane may be amino substituted; it may be a silyl ether and it is believed that its presence may significantly improve the long term strength of the binder, particularly after weathering.

Preferences for the pH of the binder are: preferred, pH≥7; more preferred, pH≥8; and most preferred, pH≥9, at least in the state in which the binder is applied to a material to be bound and/or recovered in a waste water recuperation system. Such a neutral or alkaline pH of the binder may alleviate problems of corrosion of manufacturing equipment which have been encountered with some essentially acidic prior art binder systems. Such prior art binders include binders consisting essentially of polyacrylic acids or polymeric polycarboxylic acids. One particular advantage of the present invention is thus the use of a binder system that can operate in such neutral or alkaline conditions. When cured, the binder may become acidic during the curing process. However, equipment corrosion considerations are less significant in this case due to the minimal contact between the manufacturing equipment and the binder when in this state. The pH of the binder may be less than or equal to 13, preferably less than or equal to 12, 11 or 10. A preferred pH may be in the range of 7.5 to 9.5, particularly 8 to 9. Binder which has been applied to the material to be bound and is subsequently dissolved in water may have a pH of greater than 6.

It is preferred to arrange the pH of the binder solution at an appropriate level to prevent precipitation of its constituents and particularly to ensure that the acid precursor derivable from an inorganic salt remains in solution. This is particularly the case where ammonium phosphate provides the acid precursor. Better dry and/or weathered strengths and/or more homogeneous products may be achieved by using homogeneous binder solutions comprising ammonium salt acid precursors which are free from precipitates, particularly when ammonium phosphate is used and the binder solution is free from phosphate precipitates.

The binder composition may be provided in the form of an aqueous solution; it may contain free ammonia or excess ammonia in solution. A neutral or alkaline pH of the binder may be generated by an excess of alkaline groups compared with acid groups present in the binder solution, for example, due partially or substantially to the presence of ammonia in the solution. Additional ammonia may be added to the binder solution, for example 0.2%-1% by weight, or indeed more; this may help to keep a wash water system alkaline over the long term, particularly for the manufacture of mineral wool insulation.

In the case or mineral wool fibers particularly for thermal insulation products, when binder solution is sprayed onto hot mineral wool fibers just after they have been formed, the residual heat of the mineral wool fibers may cause a significant portion of any water in the binder solution to evaporate. Consequently, the mineral wool fibers which are then collected to form a bat may have binder present on them in the form of a sticky, viscous or tacky liquid. This may facilitate bonding between individual fibers via the binder.

One of the many advantages of this binder system is that it is applied, for example, by being sprayed onto mineral wool fibers, in a substantially unreacted state. The ability to apply the binder solution in a substantially unreacted state may alleviate problems associated with pre-reacting the binder components in solution which have been encountered with some prior art binder systems in which the components are pre-reacted. Such prior art binders include binders consisting essentially of pre-reacted polymers or resins which are applied to the materials to be bound. With substantially unreacted binder present in the form of a sticky, viscous or tacky liquid on the material to be bound, the reaction between the binder components may occur in a substantially dry state. One may describe the reaction as a bulk polymerization because it is occurring without the benefit of a solvent. A particular advantage of the present invention is thus the use of a binder system that can polymerize in a substantially dry state or through a bulk polymerization.

Mineral fibers used in the context of the invention may be formed by internal or external spinning. They may have a temperature in the range 20° C. to 200° C., generally 30° C. to 100° C. or 150° C., when sprayed with the binder solution. The quantity of binder solution sprayed may be used with or without additional water sprays to assist in cooling the mineral fibers to a desired temperature between their formation and their collection to form a batt.

A particular advantage of using ammonia in solution to control the pH of the binder solution applied to the mineral fibers is that at least part of the ammonia of binder solution that sticks to the fibers may flash off due to the residual heat of the mineral wool fibers. Consequently, the binder solution that coats the fibers may have a lower pH than the binder solution sprayed.

The present invention extends to a method of manufacturing a mineral fiber thermal insulation product comprising the sequential steps of: forming mineral fibers from a molten mineral mixture; spraying a substantially formaldehyde free binder solution on to the mineral fibers, the binder solution comprising: a mixture of carbohydrates (particularly a mixture of reducing sugars), an acid precursor derivable from an inorganic salt and/or an ammonium salt of a polycarboxylic acid, and a source of nitrogen; and collecting the mineral fibers to which the binder solution has been applied to form a uncured batt of mineral fibers. Wash water may be sprayed on to mineral fibers between their formation and their collection to form a bat, at least a part of the wash water having been sprayed on mineral fibers and subsequently returned to a wash water system to be reused as wash water. The binder solution may comprise wash water.

The binder may eventually be cured, for example in a curing oven; it may form a thermoset binder. In its cured form, the binder may: comprise melanoidins; and/or be thermoset; and/or be water insoluble or substantially water insoluble. The binder solution may be substantially colorless or white to off-white; upon curing, the binder may take on a dark color, particularly a dark brown color. The cured product may be dark in color, particularly dark brown in color. The binder may be free of proteins; it may be free of cellulosic feedstock. One of the many advantages of this binder system is that the extent of curing can be determined by the color. Substantially dehydrated binder appears white or off-white. Progressively cured to a greater extent, the binder appears progressively darker in color (a darker shade of brown). When applied to mineral fibers, the extent to which the mineral wool insulation has cured can be determined by its color.

When applied to the material to be bound and/or prior to curing, the binder may be free or substantially free of melanoidins and/or other reaction products derived from curing. Curing of the binder may produce glucosylamine, particularly as an intermediate product. Consequently, a cured or particularly a partially cured product may comprise glucosylamine The reaction of the binder upon curing may be essentially a Maillard type reaction as described for example in WO2007/14236. The binder may comprise polymerization products of a mixture that comprises a mixture of reducing sugars and a material selected from the group consisting of ammonium sulfate, ammonium phosphate, ammonium nitrate and ammonium carbonate.

The binder solution may be formulated by combining: a mixture of reducing sugar carbohydrates (e.g., provided by HFCS), an acid precursor derivable from an inorganic salt (preferably an ammonium sulfate or ammonium phosphate) and/or an ammonium salt of a polycarboxylic acid, a source of nitrogen, and water. The formulation may comprise optional or additional ammonia provided in the form of an aqueous ammonia solution. The water may comprise wash water or recycled process water.

Forming the binder solution from a mixture of carbohydrates, an acid precursor comprising an inorganic ammonium salt and/or an ammonium salt of a polycarboxylic acid provides one particular advantageous preparation method. This may be achieved in a simple mixing chamber which may be open and/or at atmospheric pressure. The mixture of carbohydrates and the acid precursor and/or the ammonium salt may be added in powder or liquid form. The preparation is preferably carried out at room temperature. Preferably it is not necessary to supply heat to prepare the binder solution; nevertheless, the binder solution may be heated during its preparation, for example to a temperature with the range 20° C. to 80° C., particularly where this facilitates dissolving and/or mixing of its ingredients.

The binder solution, particularly in the state applied to the material to be bound, may comprise: at least 5% 10%, 15% or 18% solids and/or less than 70% or 60% (particularly in the case of wood board applications) or less than 50%, 40% or 20% solids (particularly in the case of mineral fiber insulation applications) particularly determined as bake out solids by weight after drying at 140° C. for 2 hours.

The collection of loose matter bound together by means of the binders described herein may comprise materials selected from: fibers, fibrous materials, mineral fibers, glass fibers, stone wool fibers, cellulosic fibers (including wood fibers, wood shavings, wood particles and sawdust), wood veneers, facings, wood facings, particles, woven or non-woven materials, loosely assembled materials, woven or non-woven materials.

The loose matter may be shaped and/or dimensioned and/or molded with the aid of the binder. The material produced may be selected from: a thermal insulation material, a mineral fiber product, a wood board product (including chip board, orientated strand board, particle board, medium density fiber board, wood facing products), foundry sands.

The matter to be bound may be at a temperature in the range 20° C. to 100° C. when the binder is applied. The binder solution, particularly when applied to the loose matter, may have a viscosity appropriate for application by spraying or pouring. Its viscosity at 20° C. may be less than about 1.5 Pas, preferably less than about 1×10⁻² Pas, and/or greater than about 2×10⁻⁴ Pas, preferably greater than about 5×10⁻⁴ Pas.

EXAMPLES

The following examples illustrate specific embodiments in further detail. These examples are provided for illustrative purposes only and should not be construed as limiting the invention or the inventive concept to any particular physical configuration in any way.

An uncured binder composition was prepared as HFCS 42:Ammonium Sulfate=76.4:16 based on dry solids. HFCS 42 is commercial quality High Fructose Corn Syrup with 42% Fructose concentration. The preferred moisture content of an uncured fiberglass insulation product is 0.5% to 4%.

Example 1: For a fiberglass insulation product with 7% LOI after cure, the free moisture content of the uncured fiberglass insulation product is in the range of 0.5% to 7%_.

Example 2: For a fiberglass insulation product with 15% LOI after cure, the free moisture content of the uncured fiberglass insulation product is in the range of 1% to 7%.

In order to demonstrate the supersaturated nature of a carbohydrate-based binder of the present invention, a preferred uncured fiberglass insulation product from Example 2 has 5% free moisture.

The uncured fiberglass insulation product of Example 2 with an LOI of 15% contains approximately 21.5% binder solids of HFCS 42:Ammonium Sulfate=76.4:16. This corresponds to 17.8% HFCS and 3.7% Ammonium Sulfate based on dry weight of uncured product. Said uncured product has a free moisture concentration of 2.5%. The ratio of Ammonium Sulfate to free moisture is 3.7:2.5. The ratio of HFCS 42:free moisture is 17.8:2.5 At ambient temperatures (e.g., 20° C.) these ratios are beyond the solubility ratios of HFCS:Water of approximately 17.8:7.7 and HFCS:Ammonium Sulfate=3.7:5.

Molding of 9-month-old uncured fiberglass insulation made with HFCS/AS (Cured binder LOI: 15-17%; Moisture of Uncured: 1.5%-3%; product stored in PE bag at 15° C.-24° C.) was associated with essentially no crystallization, and the uncured insulation product was soft, showed good recovery, and processed well. This is in contrast to Dextrose/AS migrating and crystallizing out within 2 weeks, which illustrates an economic advantage of using HFCS.

Claims

1. A composition comprising an uncured binder disposed on mineral fibers, wherein the uncured binder consists of an aqueous mixture of (a) at least two reducing sugars comprising 1) at least one aldohexose sugar selected from the group consisting of dextrose, mannose, galactose, allose, altrose, talose, gulose, and idose; and 2) at least one ketohexose sugar selected from the group consisting of fructose, psicose, sorbose and tagatose, wherein the mixture has a lower crystallization point than a carbohydrate mixture consisting of dextrose; and (b) an acid precursor derivable from an inorganic salt selected from the group consisting of ammonium sulfate salts, ammonium phosphate salts, ammonium nitrate salts, ammonium carbonate salts and combinations thereof and/or (c) an ammonium salt of a polycarboxylic acid; optionally (d) a silicon-containing compound; and optionally (e) a corrosion inhibitor.

2. The composition of claim 1, wherein the inorganic salt is selected from the group consisting of ammonium sulfate salts, ammonium phosphate salts, ammonium carbonate salts, and combinations thereof.

3. The composition of claim 1, wherein the polycarboxylic acid is selected from the group consisting of unsaturated aliphatic polycarboxylic acids, saturated aliphatic polycarboxylic acids, aromatic polycarboxylic acids, unsaturated cyclic polycarboxylic acids, saturated cyclic polycarboxylic acids, and combinations thereof.

4. The composition of claim 1, wherein the silicon-containing compound is selected from the group consisting of gamma-aminopropyltriethoxysilane, gamma-glycidoxypropyltrimethoxysilane, and mixtures thereof.

5. The composition of claim 1, wherein the corrosion inhibitor is capable of decreasing the corrosivity of the composition.

6. The composition of claim 5, wherein the corrosion inhibitor is selected from the group consisting of dedusting oil, monoammonium phosphate, sodium metasilicate pentahydrate, and melamine.

7. The composition of claim 1, wherein the composition is a fiberglass insulation product.

8. The composition of claim 1, wherein the mineral fibers comprise fibers selected from glass fibers and stone wool fibers.

9. The composition of claim 8, wherein the mineral fibers comprise glass fibers.

10. The composition of claim 1, wherein the mixture of at least two reducing sugars is provided as high fructose corn syrup (HFCS).

11. The composition of claim 1, wherein the binder has a moisture content of 1.5-3%.

12. The composition of claim 1, wherein the binder has a pH of 7.5-9.5.

13. The composition of claim 1, wherein the mineral fibers comprise glass fibers at a compositional concentration of 80-99% by weight.

14. The composition of claim 1, wherein the binder compriscs has 5-25% by dry weight of an acid precursor derivable from an inorganic salt selected from the group consisting of ammonium sulfate salts, ammonium phosphate salts, ammonium nitrate salts, ammonium carbonate salts and combinations thereof.

15. The composition of claim 1, wherein the binder has 10-20% by dry weight of an acid precursor derivable from an inorganic salt selected from the group consisting of ammonium sulfate salts, ammonium phosphate salts, ammonium nitrate salts, ammonium carbonate salts and combinations thereof.

16. The composition of claim 1, wherein the aqueous mixture is a viscous or tacky liquid.