Prepolymer compositions for insulating foams

Details Prepolymer compositions for insulating foams Prepolymer compositions for insulating foams

2000-05-15

2003-04-22

Gorr, Rachel (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Cellular products or processes of preparing a cellular...

C521S131000, C521S132000, C521S133000, C521S152000, C521S159000, C528S075000, C528S059000, C528S905000, C524S507000, C524S590000, C524S871000, C524S873000, C222S491000

Reexamination Certificate

active

06552097

ABSTRACT:

DESCRIPTION
This invention relates to a prepolymer composition for producing polyurethane insulating foams from a 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 polyisocyanate prepolymers based on hexamethylene-1,6-diisocyanates for producing prepolymer components for pressure-can polyurethane insulating foams, as well as to pressure cans with such a prepolymer composition and optionally a separate polyol component for producing polyurethane insulating foams.
The inventive prepolymer composition is used for producing polyurethane insulating foams which are used particularly for 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. 1C 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 a polyol which must be added directly before foam formation. Curing can be accelerated by catalysts. Bulk densities in 2C foams are characteristically 10 to 100 g/l.
Transitional forms between 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. These transitional forms have come to be known as “1.5C foams”. The invention also covers foaming agents with more than one separate reactive component.
Conventional prepolymer compositions for 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. The composition contains a certain quantity of monomeric isocyanate. Suitable isocyanates are for example isophorone di-isocyanate, 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 4,4-diisocyanatodiphenylmethane 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.
As mentioned above, PU prepolymers suitable for producing polyurethane insulating foams from pressure tanks contain a residual content of unreacted monomeric isocyanate which can be up to 40%. This residual content is usually due to manufacturing, but is also desirable since it has turned out that this residual content has a positive effect on the serviceability, in particular the inherent and dimensional stability, of the produced foams. On the other hand monomeric isocyanates are deemed dangerous substances subject to identification because of their toxicity, despite their generally rather low volatility. MDI, the preferred initial isocyanate for 1C foams, is subject to a maximum working place concentration of 0.01 ppm, as is HDI. Because of the toxicity of the contained substances packings having residues of these prepolymers are subject to cost-intensive restrictions on disposal.
Although it is possible to produce prepolymers with low residual monomer contents, the low serviceability of the produced foams has prevented the use of such prepolymer compositions up to now. No applicable polymer compositions for pressure cans have become known. It was generally assumed that monomer-free standardizations cannot be used in pressure cans. Monomer-free prepolymers can be produced for example by removal of the monomer through distillation and optionally further reaction with a reactive hydroxy polyether and/or polyester and/or vegetable oil, modified or unmodified.
EP-A-0 420 026 describes a method for producing low-monomer polyurethane prepolymer based on tolylene diisocynate. DE-A40 25 843 and EP-A-0 480 342 describe prepolymer compositions for producing polyurethane isulating foams from pressure tanks which consist of a prepolymer component with at least one PU prepolymer with free NCO groups and usual additives as well as a propellant component. Low-monomer pre-polymer components are accordingly not used.
In view of the disadvantages of known PU prepolymers containing monomeric isocyanate it is desirable to provide a PU prepolymer containing little or substantially no more monomeric isocyanate while guaranteeing the properties demanded particularly by the construction industry, e.g. dimensional stability of the foam. It is in particular the goal of the invention to provide a prepolymer composition for dimensionally stable 1.5C PU foams which contains toxic and/or irritant components in quantities so low that they are no longer subject to identification.
The following are the sources or trademarks for the indicated materials:
CASTOR OIL, a natural product,
LEVEGARD PP, a trademark for softener, a product of Bayer AG, Leverhusen, Germany,
IXOL M 125, a trademark for flameproofing agent, a product of Solvay, located at Brussels, Belgium,
TEGOSTAB B 1048, a trademark for a stabilizer, a product of Goldschmid AG, Essen, Germany,
TEXACAT DMDEE, a trademark for 2,2-dimorpholinodiethylether, a product of Texaco, Inc., White Plains, N.Y.,
THANCAT DMP, a trademark for dimethyl piperazine, a product of Condea GmbH, Hamburg, Germany,
DESMODUR N 3400, a trademark for an aliphatic polyisocyanate based on HDI with 20% NCO, a product of Bayer AG, Leverhusen, Germany,
DESMODUR N, a trademark for a polyisocyanate with 22% NCO, a product of Bayer AG,
DESMODUR L, a trademark for a polyisocyanate with 13% NCO, a product of Bayer AG,
DESMODUR Z 4370, a trademark for a polyisocyanate, a product of Bayer AG,
DESMODUR E 326S, a trademark for a polyisocyanate, a product of Bayer AG,
DESMODUR N 75, a trademark for a polyisocyanate with 16.4% NCO, a product of Bayer AG,
DESMODUR L 75, a trademark for a polyisocyanate with 13% NCO, a product of Bayer AG,
DESMODUR DA, a trademark for a polyisocyanate, a product of Bayer AG,
DESMODUR N 3390, a trademark for a polyisocyanate, a product of Bayer, AG,
R 134a, 1,1,2-tetrafluoroethane, a common abbreviation of a propellant,
R 152a, 1,1-difluoroethane, a common abbreviation of a propellant,
R 125, pentafluoroethane, a common abbreviation of a propellant,
R 143, 1,1,2-trifluoroethane, a common abbreviation of a propellant,
TEGOIMR 830, a trademark for a 10% emulsion of a liquid polybutadiene with a moleular weight of about 3000 and with a surface active agent, a product of Goldschmid, located at Essen, Germany,
BYK 160, a trademark for wetting additive, a product of BYK Chemie GmbH, Wesel, Germary,
BYK 051, a trademark for wetting additive, a product of BYK Chemie GmbH, Wesel, Germany,
BYK 052, a trademark for wetting additive, a product of BYK Chemie GmbH, Wesel, Germany,
BYK 053, a trademark for wetting additive, a product of BYK Chemie GmbH, Wesel, Germany,
Aerosil 200, a trademark for thixotroping agent, a product of Degussa AG, Frankfurt, Germany,
Finntalc M-15, a trademark for talcum, a product of Finnminerals Oy, Espoo, Finland,
Ultracarb U-5, a trademark for calcium carbonate, a product of Microfine Minerals and Chemicals Ltd., Derby, UK,
POLYOL 130, a trademark for a liquid polybutadiene a product of Hüls AG, Marl, Germany,
DABCO, a trademark

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