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Description
Mineral wool fiber mats, their production and use
The present invention relates to mineral wool fiber mats impregnated with a selected binder. These mats are useful for example as insulants, for example for thermal insulation of roofs.
Aqueous polymeric dispersions for use as binders for mineral wool fiber mats are known per se. Mineral wool mats incorporating crosslinked polymers as binders form part of the subject matter of a wide variety of patent documents.
US-A-2008/0175997 describes binder compositions for glass mats that include an emulsion of a carboxyl-functionalized polymer and also a crosslinker having aziridine groups. Compared with conventional systems, a formaldehyde-free dispersion is concerned. It has comparable or even improved strength and flexibility compared with known systems. This document mentions further known binder systems for glass mats that derive from carboxyl-functionalized polymers and include specific crosslinkers, for example polyol compounds combined with phosphorus-containing accelerator, compounds containing active hydrogen, such as polyol, polyvinyl alcohol or polyacrylate, combined with fluoroborate accelerator, or crosslinkers which promote the esterification between COOH and OH groups in the polymer, or comprise epoxidized oils.
EP-A-1,018,523 discloses a polymer dispersion comprising a) dispersed addition polymer comprising 5-20% by weight interpolymerized carboxylic acid units, b) dissolved addition polymer comprising 60-100% by weight of interpolymerized carboxylic acid units, and c) selected alkoxylated long-chain amine as a crosslinker. This dispersion is useful as a binder for mineral wool mats for example.
DE-T-699 21 163 describes an insulating product based on mineral wool based on specific mineral fibers, the insulating product bearing a size based on a thermosetting resin admixed with a latex in order that mechanical strength after aging may be improved. The latex used comprises in particular polymers having hydrophilic groups, for example carboxyl, hydroxyl or carboxylic ester groups. Phenolic resin is mentioned as a thermosetting resin.
DE-A-197 38 771 and DE-A197 20 674 describe binders for mineral wool containing a) a thermoplastic polymer crosslinkable with phenolic resin, such as polyacrylate or polyvinyl ester, b) phenolic resin and c) flame retardant.
EP-A-1 164 163 discloses a binder for mineral wool, obtained by mixing a carboxylic acid and an alkanolamine under reactive conditions. An example of the carboxylic acid used is polyacrylic acid, polymethacrylic acid or a polymaleic acid.
WO-A-01/05,725 describes a binder for mineral wool, obtained by reacting a mixture which does not contain a polymer but includes an amine and also a first and a second anhydride. Typical representatives of the reaction mixture are diethanolamine, cyclic aliphatic anhydride, for example maleic anhydride succinic anhydride or hexahydrophthalic anhydride, and an aromatic anhydride, for example phthalic anhydride.
WO-A-2007/060,236 describes a formaldehyde-free binder for mineral wool comprising a) an aqueous dispersion of a polymeric polycarboxylic acid, b) a selected alkanolamine, for example ethanolamine, and c) an activated silane obtained by reacting a silane, for example alkoxysilane, with an enolizable ketone comprising at least one carboxyl group or with a ketone having at least one hydroxyl group, for example dihydroxyacetone or acetylacetone.
DE-A-100 14 399 discloses a mixture of two polymeric systems one of which bears mandatory carboxyl groups, while the second one contains interpolymerized functional groups capable of reacting with the carboxyl groups of the first polymeric system to form a covalent bond.
DE-A-26 04 544 discloses binders for consolidating glass fiber mats wherein a carboxyl-containing polymer is reacted with a crosslinker selected from the group of polyepoxides or capped isocyanates. The polymer basis for the binders used is restricted to polymers constructed from ethylenically unsaturated esters of acrylic or methacrylic acid.
JP-A-2006-089,906 describes a formaldehyde-free binder for mineral wool comprising a vinyl copolymer having hydroxyl groups and groups derived from an organic acid.
WO-A-2004/085,729 describes a formaldehyde-free binder for mineral wool comprising a) a compound having at least 2 cyclic ether groups and b) a copolymer having nucleophilic groups.
WO-A-2006/136,614 discloses a binder for mineral wool comprising a) phenol-formaldehyde binder and b) a hydroxylamine or an amino alcohol.
DE-A-40 24 727 discloses an agent for hydrophilicizing mineral wool fibers which comprises a) phenol-formaldehyde binder and, as hydrophilicizing agent, a mixture of b) water-soluble nitrogen-carbonyl compound, e.g., urea, c) acrylic resin and d) mixture of carboxyl-containing fatty acid condensation products with organic phosphoric esters.
There are also a number of documents already describing epoxy- or carboxyl-functionalized binders. Examples thereof are given in US-A-2008/0214716, USA2006/0258248, DEC199 56 420 and WOA03/104284. WOA03/104284 describes binder systems for producing glass fiber products in which low molecular weight epoxy compounds are crosslinked with functionalized polymeric compounds. USA2006/0258248 discloses epoxidized oils combined with multifunctionalized carboxylic acids or anhydrides as suitable crosslinking binders. USA2008/0214716 discloses binders for producing fiber weaves from a polymer based on ethylenically unsaturated monomers, a water-soluble polymer based on ethylenically unsaturated carboxylic acids and an alkoxylated or hydroxyalkylated crosslinker. DEC19956420 describes the use of water-soluble polymers based on ethylenically unsaturated carboxylic acids and certain amines in the presence of a crosslinking agent based on epoxy or acrylic resin for producing shaped articles.
There is increasing commercial demand for products which are formaldehyde-free in their formulations and emissions during application while retaining the current performance characteristics.
It is an object of the present invention to provide bound mineral wool fiber mats bonded together by formaldehyde-free binders and very useful as insulating materials. “Formaldehyde-free” is to be understood in the context of this description as meaning a composition having a formaldehyde content of less than 10ppm.
The present invention provides a mineral wool fiber mat bound with a binder containing an epoxy and/or carboxyl functionalized copolymer, more particularly containing an appropriately functionalized emulsion copolymer, preferably in dispersion form, and an amine and/or an amine derivative as crosslinker.
In a preferred embodiment of the present invention, the mineral wool fiber mats contain a biosoluble fiber material bonded by a formaldehyde-free binder applied in a pH range in which the fibers are not attacked. This range is ideally located above the neutral point. This pH range is preferably 7.5 – 10.
The mineral wool fiber mats of the present invention contain glass wool and/or rockwool and can in principle contain further aggregates known to a person skilled in the art and/or further fibers.
Glass wool can be produced using any of the foundation stocks known from the glass industry. Quartz sand, sodium carbonate and limestone are typically used; cullet can be admixed to these raw materials, for example at up to 70% by weight of cullet. The melt is fiberized in a conventional manner by centrifugal casting or jetting.
Rockwool can be produced in a similar manner to glass wool. Basalt, diabase, feldspar, dolomite, sand and limestone are typically used; these raw materials may likewise be admixed with cullet. The melt is fiberized in a conventional manner by centrifugal casting. In addition to the customary starting materials for producing rockwool, it is also possible to use slags generated as waste products in combustion or production processes, for example blast furnace slags. This form of rockwool known as slag wool is similarly known to a person skilled in the art.
The glass wool or rockwool used is preferably selected to have a high biosolubility. Biosolubility is to be understood as meaning the ability of the fibers to be dissolved and degraded in the body by endogenous substances.
The glass wool or rockwool fiber mats formed are additized with a binder to ensure their dimensional stability. The fiber mat is subsequently cured by heat treatment, for example in a hot air stream. Volatile constituents are additionally removed from the fiber mat in the course of the heat treatment. Web-forming processes of this type are described for example in US2008/0175997A1.
Alternatively, mineral wool fiber mats can also be produced by wet laying. To this end, fibers can be initially charged in an aqueous slurry together with the binder and be laid down on a moving support surface, for example a water-permeable conveyor belt, to form a fiber mat. After dewatering, the fiber mat is cured by heat treatment, for example in a hot air stream. Production processes for mineral wool mats of this type are described for example in DE60123 177T2.
Mineral wool mats may also contain further customary added substances. Mineral oils are frequently added, for instance, to improve further processability and imbued the mineral wool mats with improved water-rejecting properties. In addition, such mats may be laminated with aluminum foil or fibrous nonwoven webs when used as an insulating material in particular.
The mineral wool fiber mats of the present invention are endowed with a specific binder which contains an epoxy and/or carboxyl functionalized copolymer.
The epoxy and/or carboxyl functionalized copolymers are preferably derived from one or more ethylenically unsaturated compounds, such that at least one of these monomers must have one or more epoxy groups and/or one or more carboxyl groups.
These embodiments comprise by way of reactive groups either only interpolymerized epoxy groups or only interpolymerized carboxyl groups or, in addition to the interpolymerized epoxy groups, additionally interpolymerized carboxyl groups, for example from units derived from ethylenically unsaturated mono- or dicarboxylic acids. The selection of these embodiments depends inter alia on further additions to the binder formulation and/or on the reaction conditions prevailing at application (at the binding of the mineral wool in the binding process, for example).
In addition to these copolymers, it is also possible to use homo- or copolymers derived completely or overwhelmingly from carboxyl-containing ethylenically unsaturated monomers. Examples thereof are polyacrylic acid or salts thereof and also polymethacrylic acid or salts thereof, more particularly the alkali metal salts of these polymers.
The epoxy and/or carboxyl functionalized copolymers preferably comprise copolymers of vinyl esters and/or of esters of α,β-ethylenically unsaturated C3C8-mono or dicarboxylic acids and/or of alkenyl aromatics, each polymerized with ethylenically unsaturated comonomers comprising epoxy groups and/or carboxyl groups or anhydrides thereof.
In addition to the epoxy-containing monomers and/or the carboxyl-containing monomers, it is mainly the following groups of monomers which are contemplated as a basis for the classes of polymer mentioned:
One group is formed by vinyl esters of monocarboxylic acids having one to eighteen carbon atoms, examples being vinyl formate, vinyl acetate, vinyl propionate, vinyl isobutyrate, vinyl valerate, vinyl valerate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl decanoate, isopropenyl acetate, vinyl esters of saturated branched monocarboxylic acids having 5 to 15 carbon atoms in the acid moiety, more particularly vinyl esters of VersaticTM acids, vinyl esters of relatively long-chain saturated or unsaturated fatty acids such as for example vinyl laurate, vinyl stearate and also vinyl esters of benzoic acid and of substituted derivatives of benzoic acid such as vinyl p-tert-butylbenzoate. Among these, however, vinyl acetate is particularly preferred for use as principal monomer.
A further group of monomers is formed by esters of α,β-ethylenically unsaturated C3C8-mono or dicarboxylic acids with preferably C1C18-alkanols and more particularly C1C8-alkanols or C5C8-cycloalkanols. The esters of dicarboxylic acids may be monoesters, or preferably, diesters. Examples of suitable C1C8-alkanols are methanol, ethanol, n-propanol, i-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, n-hexanol and 2-ethylhexanol. Examples of suitable cycloalkanols are cyclopentanol or cyclohexanol. Examples are esters of acrylic acid, of methacrylic acid, of crotonic acid, of maleic acid, of itaconic acid, citraconic acid or of fumaric acid such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, nbutyl (meth)acrylate, isobutyl (meth)acrylate, 1-hexyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, di-n-methyl maleate or fumarate, di-n-ethyl maleate or fumarate, di-n-propyl maleate or fumarate, di-n-butyl maleate or fumarate, diisobutyl maleate or fumarate, di-n-pentyl maleate or fumarate, di-n-hexyl maleate or fumarate, dicyclohexyl maleate or fumarate, di-n-heptyl maleate or fumarate, di-n-octyl maleate or fumarate, di-(2-ethylhexyl) maleate or fumarate, di-n-nonyl maleate or fumarate, di-n-decyl maleate or fumarate, di-n-undecyl maleate or fumarate, dilauryl maleate or fumarate, dimyristyl maleate or fumarate, dipalmitoyl maleate or fumarate, distearyl maleate or fumarate and diphenyl maleate or fumarate.
Preferred principal monomers of this group are selected from the group of acrylates and methacrylates. Particular preference is given to methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 1-hexyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate.
A further group of monomers is formed by alkenyl aromatics. The alkenyl aromatics in question are monoalkenyl aromatics. Examples thereof are styrene, vinyl toluene, vinyl xylene, α-methylstyrene or o-chlorostyrene. Styrene in particular must be mentioned as a preferred monomer in this group.
The monomers mentioned generally form the principal monomers which, in relation to the total amount of the monomers to be polymerized, normally account for a proportion of more than 50% by weight and preferably more than 75%.
A further group of monomers which can mainly be used together with vinyl esters and/or esters of α,β-ethylenically unsaturated C3C8-mono- or dicarboxylic acids and/or alkenyl aromatics is formed by aliphatic, monoolefinically or diolefinically unsaturated, optionally halogen-substituted hydrocarbons, such as ethene, propene, 1-butene, 2-butene, isobutene, conjugated C4C8-dienes, such as 1,3-butadiene, isoprene, chloroprene, vinyl chloride, vinylidene chloride, vinyl fluoride or vinylidene fluoride.
The monomers are preferably to be selected so as to form an addition polymer or copolymer having good compatibility in common formaldehyde-free binder formulations which additionally has excellent binding properties in the production of mineral wool mats.
Preferably used binder polymers are derived from the following principal monomers or combinations thereof in addition to the epoxy-containing monomers and/or the carboxyl-containing monomers:
copolymers based on one or more vinyl esters, more particularly vinyl acetate;
copolymer based on esters of α, β-ethylenically unsaturated C3C8-mono with C1C8-alkanols, more particularly esters of (meth)acrylic acid;
copolymers based on vinyl esters and esters of α, β-ethylenically unsaturated C3C8-mono- or dicarboxylic acids with C1C8-alkanols, more particularly esters of (meth)acrylic acid and maleic/or fumaric acid;
copolymers based on vinyl esters, more particularly vinyl acetate, with ethylene;
copolymer based on esters of α, β-ethylenically unsaturated C3C8-mono- or dicarboxylic acids with C1C8-alkanols, more particularly esters of (meth)acrylic acid and maleic/or fumaric acid, with ethylene;
copolymers based on vinyl esters, ethylene and esters of α, β-ethylenically unsaturated C3C8-mono- or dicarboxylic acids with C1C8-alkanols, more particularly esters of (meth)acrylic acid and maleic/or fumaric acid; or
copolymers based on styrene and esters of α, β-ethylenically unsaturated C3C8-mono- or dicarboxylic acids with C1C8-alkanols, more particularly esters of (meth)acrylic acid and optionally ethylene and/or butadiene.