Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-11-10
2004-06-15
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C222S129000, C252S182200, C252S182220, C521S108000, C521S130000, C521S131000, C521S132000, C521S137000, C521S140000, C521S159000, C521S168000, C521S172000, C521S114000
Reexamination Certificate
active
06750265
ABSTRACT:
BACKGROUND
This invention relates to a prepolymer composition for producing polyurethane insulating foams with fire-retardant properties from pressure tanks which consists of a prepolymer component with at least one PU prepolymer with a content of NCO groups of 4 to 20 wt % and usual additives as well as a propellant component. The invention furthermore relates to the use of softening phosphates and phosphonates as a firetardant additive to prepolymer compositions for producing pressure-can polyurethane insulating foams, as well as to pressure cans with such a prepolymer composition for producing polyurethane insulating foams.
The inventive prepolymer composition is used for producing polyurethane insulating foams which are used particularly for insulating purposes by foaming in cavities. The main areas of application are the construction industry, but also technical products in which cavities must be filled to avoid condensation nests. When one-component polyurethane foams are spoken of, these are applied by discharging the prepolymer composition from pressure tanks, for example aerosol cans, on the spot with the help of propellants with a bulk density of 10 to 50 g/l, and processed. One component foams are moisture-hardening, i.e. they can be cured solely with the help of the moisture contained in the air.
Two component polyurethane foams require a second hydroxy component for curing the prepolymer composition, generally as a polyol which must be added directly before foam formation. Curing can be accelerated by catalysts. Bulk densities in two component foams are characteristically 10 to 100 g/l.
Transitional forms between one component (1C) and two component (2C) hereinafter (1C) and (2C)) foams are possible. In this case a quantity of a hydroxyl component insufficient for reacting the isocyanate groups is added to the prepolymer before discharge. Such “transitional foams (hereinafter referred to as 1.5C foams or 1.5C)” are also covered by the invention.
Conventional prepolymer compositions for 1C and 2C polyurethane insulating foams contain a prepolymer component having a minimum content of reactive NCO groups. The prepolymer itself is a polymer of suitable viscosity with terminal NCO groups. Suitable isocyanates are for example isophorone diisocyanate, referred to as IPDI, tolylene diisocyanate, also referred to as TDI, diisocyanatotoluene, 1,5-diisocyanatonaphthalene, referred to as NDI, triisocyanatotrimethylmethane, 1,6-diisocyanatohexane, referred to as HDI, or 4,4diisocyanatodiphenylmethane in a raw and pure form or as a mixture. An especially common one is 4,4-diisocyanatodiphenylmethane, also referred to as MDI, which is used both in a raw form (raw MDI) and in the form of pure 2,4- and 4,4-isomers or mixtures thereof. One can likewise use the two common TDI isomers alone or in a mixture. For producing the prepolymer component one reacts such isocyanates with hydroxy polyethers, polyesters or polyvalent alcohols, making sure the prepolymer acquires a viscosity suitable for the composition.
Insulating foams to be wed in the construction industry, so-called B2 foams, must be set to be fire-retardant according to the national specifications. This is usually done by adding fire-retardant substances to the foaming materials, in particular chlorine- and bromine-containing organic compounds. Particularly well-known ones are chlorine and bromine derivatives from diphenyl ether and biphenyl, for example pentabromobiphenyl ether and polychlorinated biphenyls. Despite their excellent fire-retardant properties these substances have fallen into dispute for toxicological reasons. If their approval has not yet lapsed, there are phasing-out deadlines. In addition, packings containing foamer residues polluted with such fire-retardant substances are subject to cost-intensive restrictions on disposal. The same applies to the finished foams when they are no longer needed and must be removed.
The problem of the invention is therefore to provide a PU prepolymer which can be set to be fire-retardant without using conventional chlorine- and bromine-containing organic materials and is thus halogen-free in the prepolymer component.
This goal is achieved with a prepolymer composition of the abovementioned type wherein the prepolymer component is substantially halogen-free and has a content of 5 to 40 wt %, based on the prepolymer component, of softening phosphates and/or phosphonates.
The inventively applied phosphates and phosphonates have the general formulae O═P(OR)
3
and O═P(OR)
2
R, wherein R can have different meanings in one and the same molecule and means alkyl, aryl, alkyl aryl or aralkyl with up to 10 C atoms.
The inventive prepolymer compositions generally contain a PU prepolymer based on known aliphatic and aromatic polyisocyanates and polyester polyols. It has turned out that particularly polyester polyols make a considerable contribution to the fire-retardant standardization of the inventive prepolymer compositions.
For producing the inventively applied prepolymer composition one uses conventional aliphatic and aromatic polyisocyanates. In particular one uses polyfunctional isocyanates with a mean of 2 to 4 isocyanate groups, both in monomeric and in oligomeric form. As stated at the outset, these pre-polymer compositions are themselves reaction products from monomers or oligomers containing isocyanate groups, and components reactive therewith, in particular hydroxyfunctional compounds. Suitable initial polyisocyanates are the ones mentioned at the outset and those stated for example in DE-A-42 15 647.
Especially suitable isocyanate prepolymers for these prepolymer compositions are ones based on HDI, MDI, TDI, NDI, 4,4-dicyclohexylmethanediisocyanate and PDI. The isocyanate prepolymers can be set to be low-monomer or substantially monomer-free. The NCO content in the applied prepolymer component is between 4 and 20 wt %, preferably between 6 and 18 wt % and in particular between 7 and 13 wt %.
When producing the isocyanate prepolymers one uses usual hydroxy components, for example polyether, polyester or modified vegetable oils with a sufficient hydroxyl number, approximately in the range of 100 to 300. Castor oil with a hydroxyl number of about 160 is suitable, as are usual glycols, in particular polyethylene glycols.
It is particularly suitable for inventive purposes to use polyesterols and native polyhydroxy compounds, which develop a synergistic effect with the inventively added softening phosphates and phosphonates. Polyester polyols that can be used are ones based on ethylene glycol or glycerine and aromatic or aliphatic, preferably native, polycarboxylic acids. These polyester polyols can be wholly or partly phosphorus-modified. Suitable polyester polyols have proved to be ones based on phthalic acid, isophthalic acid, terephthalic acid and adipic acid with molecular weights of 1000 to 2000, the polyol component being generally provided by glycols, glycerine and butanediols in a monomeric or oligomeric form. It is also suitable to use polyhydroxy compounds based on aliphatic fatty acids and suitable triglyceride derivatives, as are commercially available. The polyhydroxy compound applied in forming the prepolymer should have a hydroxy functionality in the range of 2 to 4.
The addition of a low quantity of polybutadiene makes it possible to improve the serviceability of the produced foams and obtain a fully foamable, dimensionally stable insulating material. Polybutadiene can be used in combination with PU prepolymers from all usual isocyanates, but is especially advantageous in combination with PU prepolymers based on HDI and MDI.
Suitable polybutadienes to be used are particularly liquid products as are offered by Hülls A G with a viscosity of at least 500 mPa.s at 20° C. Viscosity is preferably at least 2000 mPa.s at 20° C. and in particular about 3000 mPa.s at 20° C. An especially suitable liquid polybutadiene is sold under the designation Polyol 130 with about 75% 1,4-cis double bonds, about 24% 1,4-trans double bonds and about 1% vinyl double bonds and
Pauls Mathias
Schumacher Rene
Peters Howard M.
Peters, Verny, Jones & Schmitt, L.L.P.
Sergent Rabon
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