Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2000-05-24
2001-11-13
Cooney, John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C252S182270, C521S137000, C521S159000, C521S174000, C521S914000
Reexamination Certificate
active
06316514
ABSTRACT:
The present invention relates to a process for producing sound-damping and energy-absorbing polyurethane (PUR) foams by reacting organic and/or modified organic polyisocyanates (a) with a polyetherol mixture (b) and, if desired, further compounds (c) bearing hydrogen atoms which are reactive toward isocyanates, in the presence of water and/or other blowing agents (d), catalysts (e) and, if desired, further auxiliaries and additives (f), in which a specific polyetherol mixture is used.
The production of PUR by reacting organic polyisocyanates with compounds having at least two reactive hydrogen atoms, for example polyoxyalkylenepolyamines and/or preferably organic polyhydroxyl compounds, in particular polyetherols having molecular weights of, for example, from 300 to 6000, and, if desired, chain extenders and/or crosslinkers having molecular weights of up to about 400 in the presence of catalysts, blowing agents, flame retardants, auxiliaries and/or additives is known and has been described many times. A summary overview of the production of PUR is given, for example, in Kunststoffhandbuch, Volume VII, polyurethane, Carl-Hanser-Verlag, Munich, 1
st
Edition 1966, edited by Dr. R. Vieweg and Dr. A. Höchtlen, and also 2nd Edition 1983 and 3
rd
Edition 1993, edited by Dr. G. Oertel.
The main application area for cold-cure flexible foams is upholstery elements for the furniture industry and seat elements for the automobile industry. In addition, numerous flexible PUR foams are employed for sound-damping purposes, e.g. in automobile carpets.
The open-pored foam framework offers favorable prerequisites for airborne sound absorption. The damping behavior of the flexible foams which can be described, for example, by the loss factor &eegr; is regarded in numerous documents as a parameter for optimizing the degree of sound damping. The loss factor &eegr;
&eegr;=
W
1
/2
&pgr;W
r
indicates the proportion of sound which is irreversibly converted into heat during one oscillation period. High loss factors accordingly give a higher degree of sound damping.
Sound-absorbing flexible PUR foams are described in a series of documents.
Thus, DE-A-2751774 describes a sound-damping composite system based on a combination of rigid foam polyols and flexible foam polyols which contains a high proportion of fillers, which has an unfavorable effect on the weight per unit area of the workpiece.
Ep-A-433878 discloses carpet foams having viscoelastic properties. These comprise a specific combination of hydrophilic and hydrophobic polyols. These systems have a good sound absorption performance, but demix after a short time during storage unless they are permanently stirred. DE-A-3942330 likewise describes specific polyol mixtures for producing such viscoelastic foams.
Ep-A-331941 claims acoustic foams having a loss factor of >0.5. These foams are produced using a combination of specific hydrophilic and hydrophobic polyetherols. Sound-damping properties can, according to DE-A-4001044, be achieved by a combination of polyester alcohols and polyether alcohols. These systems have a very strong tendency to demix.
In selected cases, attempts have been made to obtain an adhesive surface character of the foam by special processing, in particular substantial undercrosslinking. Here, foaming is generally carried out at an index of from about 60 to 80. (The index indicates the equivalence ratio of the isocyanate component to the polyol component). Thus, DE-A-3710731 describes such a flexible foam having sound-insulating properties. These carpet elements, which are manufactured with relatively high bulk densities, are produced with an adhesive surface. The adhesive surface properties, which are achieved as a particular advantage, require foaming in an index range below 80, preferably about 70.
DE-A-4129666 uses mutually incompatible polyols which slowly demix. The foams are processed at indexes of <80, which can affect the mechanical properties.
The inventions disclosed in the prior art do allow the production of flexible foams having sound-damping properties but leave considerable room for improvement in this class of materials with regard to the properties and the processability. In particular, it has to be noted that the mechanical properties of the carpets are frequently unsatisfactory at the indexes of <80, frequently <70, required according to the prior art.
It is an object of the present invention to produce sound-damping, easy-to-process flexible PUR foams having a loss factor of >0.3.
We have found that this objective is achieved by employing a polyetherol mixture (b) comprising
b1) at least one bifunctional to eight-functional polyetherol based on propylene oxide and/or butylene oxide and ethylene oxide, where the proportion of ethylene oxide, based on the total amount of alkylene oxide used, is more than 40% by weight, and having an OH number of from 20 to 1000 mg KOH/g and a proportion of primary OH groups of greater than 50%, with the proviso that b1) comprises at least one at least bifunctional polyetherol b1.1) having an OH number of from 20 to 100 mg KOH/g,
b2) at least one bifunctional to six-functional polyetherol based on propylene oxide and/or butylene oxide and having an OH number of greater than 30 mg KOH/g and
b3) at least one further polyetherol based on ethylene oxide and propylene oxide and having a proportion of primary OH groups of more than 25%,
where the component b1) is used in a proportion of more than 30% by weight, based on the total weight of the polyetherol mixture (b), for producing the sound-damping and energy-absorbing PUR foams.
The present invention accordingly provides a process for producing sound-damping and energy-absorbing flexible polyurethane foams by reacting organic and/or modified organic polyisocyanates (a) with a polyetherol mixture (b) and, if desired, further compounds (c) bearing hydrogen atoms which are reactive toward isocyanates, in the presence of water and/or other blowing agents (d), catalysts (e) and, if desired, further auxiliaries and additives (f), wherein the polyetherol mixture (b) comprises
b1) at least one bifunctional to eight-functional polyetherol based on propylene oxide and/or butylene oxide and ethylene oxide, where the proportion of ethylene oxide, based on the total amount of alkylene oxide used, is more than 40% by weight, and having an OH number of from 20 to 1000 mg KOH/g and a proportion of primary OH groups of greater than 50%, with the proviso that b1) comprises at least one at least bifunctional polyetherol b1.1) having an OH number of from 20 to 100 mg KOH/g,
b2) at least one bifunctional to six-functional polyetherol based on propylene oxide and/or butylene oxide and having an OH number of greater than 30 mg KOH/g and
b3) at least one further polyetherol based on ethylene oxide and propylene oxide and having a proportion of primary OH groups of more than 25%,
where the component b1) is used in a proportion of more than 30% by weight, based on the total weight of the polyetherol mixture (b).
The invention further provides the sound-damping and energy-absorbing PUR foams produced by this process and provides for their use as energy absorbers, damping material and for filling hollow spaces.
In our investigations we surprisingly found that use of the specific polyetherol mixture according to the present invention makes it possible to produce flexible, sound-damping PUR foams which are easy to process and have a high loss factor of ≧0.3, preferably from 0.30 to 1.5.
As regards the components used according to the present invention in the polyol mixture, the following may be said:
The constituent (b1) comprises at least one bifunctional to eight-functional polyetherol based on propylene oxide and/or butylene oxide and ethylene oxide and having an OH number of from 20 to 1000 mg KOH/g, preferably from 400 to 1000 mg KOH/g, and a proportion of primary OH groups of greater than 50%, preferably greater than 70%. The proportion of ethylene oxide in (b1) is, based on the total amount of alkylene oxide used, more than 40%
Falke Peter
Rotermund Inge
Schmaler Kirsten
Schmutzer Klaus
BASF - Aktiengesellschaft
Borrego Fernando A.
Cameron Mary K.
Cooney John M.
LandOfFree
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