Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-05-21
2002-04-30
Cooney, Jr., 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...
C510S412000, C521S155000, C521S170000, C521S172000, C521S174000
Reexamination Certificate
active
06380275
ABSTRACT:
The invention relates to a method for production of polyurethane foams and of foamed, thermoplastic synthetic resins, to new blowing agents suitable for this purpose as well as to polyurethane foam and to foamed synthetic resins, which can be obtained using the blowing agents.
Polyurethane foams are used as thermally insulating and noise-insulating building materials. The production of one-component and multi-component polyurethane foams with blowing agents based on liquefied carbon dioxide is disclosed in the WO 96/14354.
Foamed, thermoplastic synthetic resins can be used, for example, in the form of panels, as thermally insulating and noise-insulating building materials. U.S. Pat. No. 5,276,063 discloses a method for producing extruded, closed-cell alkenylaromatic polymers using a blowing agent mixture, which contains 1,1-difluoroethane as well as a further blowing agent with a lower vapor pressure and an even higher solubility in the molten polymer. Suitable alkenylaromatic polymers are, for example, polymers of styrene, &agr;-methylstyrene, ethylstyrene, vinylbenzene, vinyltoluene, chlorostyrene and bromostyrene. These polymers can, if desired, contain copolymers, such as acrylic acid, acrylonitrile or butadiene. U.S. Pat. No. 5,204,169 discloses the production of foamed, thermoplastic polymers, such as polystyrene, using perfluorinated hydrocarbons with two carbon atoms. The foamed material is suitable particularly for food packaging. The EP-A-0 436 847 discloses the production of foamed thermoplastic molded objects based on polyphenylene ether resins. Hydrocarbons are recommended as blowing agents. Halogenated hydrocarbons with one or two carbon atoms are also mentioned as being usable.
It is an object of the present invention to provide a method for the production of polyurethane foams by means of a selected, novel advantageous blowing agent. This objective is accomplished by the method and the blowing agents of the present invention.
It is an object of the present invention to provide a method for the production of foamed, thermoplastic synthetic resins by means of a novel, advantageous blowing agent. This objective is accomplished by the method and the blowing agents of the present invention.
The starting point was the surprising realization that pentafluorobutane, particularly 1,1,1,3,3-pentafluorobutane (HFC-365mfc), in admixture with certain other blowing agents, is a very suitable composition for the production of polyurethane foams or of thermoplastic synthetic resin foams.
According to the inventive method for producing polyurethane foams and of foamed thermoplastic resins by foaming a thermoplastic synthetic resin with the help of a blowing agent, a composition is used as blowing agent, which contains or consists of a) pentafluorobutane, preferably 1,1,1,3,3-pentafluorobutane (HFC-365mfc) and b) at least one further blowing agent selected from the group comprising low-boiling, optionally halogenated hydrocarbons, ethers and halogenated ethers; difluoromethane (HFC-32); difluoroethane, preferably 1,1-difluoroethane (HFC-152a); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1,2-tetrafluoroethane (HFC-134a); pentafluoropropane, preferably 1,1,1,3,3-pentafluoropropane (HFC-245fa); hexafluoropropane, preferably 1,1,2,3,3,3-hexafluoropropane (HFC-236ea) or 1,1,1,3,3,3-hexafluoropropane (HFC-236fa); and heptafluoropropane, preferably 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea).
The preferred pentafluorobutane is HFC-365mfc. This is explained in greater detail in the following.
According to one embodiment, a blowing agent is used, which consists of 1,1,1,3,3-pentafluorobutane, 1,1,1,3,3-pentafluoropropane and at least one of the blowing agents named under b).
The preferred embodiment contains 1,1,1,3,3-pentafluorobutane as the component named under a).
The inventive method provides that a composition is used as blowing agent, which contains or consists of 1,1,1,3,3-pentafluorobutane (HFC-365mfc) and at least one further blowing agent selected from the group consisting low-boiling, optionally halogenated hydrocarbons, ethers and halogenated ethers; difluoromethane (HFC-32); difluoroethane, preferably 1,1-difluoroethane (HFC-152a); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1,2-tetrafluoroethane (HFC-134a); pentafluoropropane, preferably 1,1,1,3,3-pentafluoropropane (HFC-245fa); hexafluoropropane, preferably 1,1,2,3,3,3-hexafluoropropane (HFC-236ea) or 1,1,1,3,3,3-hexafluoropropane (HFC-236fa); and heptafluoropropane, preferably 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea).
The concept of “low-boiling, optionally halogenated hydrocarbons, ethers and halogenated ethers” means compounds with a boiling point lower than 70° C., preferably lower than 55° C. Suitable hydrocarbons are especially those with two to five carbon atoms, for example, ethane, propane, butane, pentane, cyclopentane and hexane, as well as mixtures thereof. Moreover, isomerically pure compounds or mixtures of different isomers can be used. “Butane” is understood to be mixtures of n-butane and i-butane. Such mixtures are commercially available. Pure n-butane or i-butane or their mixtures of any composition can also be used, but are very expensive. The same holds true for higher homologs, such as pentane, etc. CH
2
Cl
2
, for example, is a usable halogenated hydrocarbon.
Preferably, the blowing agent composition contains 5 to 95% by weight of 1,1,1,3,3-pentafluorobutane and especially 10 to 70% by weight.
Blowing agent compositions which, in addition to HFC-365mfc and one or several of the fluorinated hydrocarbons or hydrocarbons given above, also contain liquefied carbon dioxide, are likewise well suited for use in the inventive method. In that case, preferably 2 to 50% by weight of carbon dioxide are contained in the blowing agent composition. In addition, the blowing agent composition may contain up to 30% by weight of additives, which modify the properties of the synthetic resin that is to be produced.
Particularly suitable blowing agents include, for example, the following compositions, which may contain or consist of (examples of compositions, the parts by weight being given in parentheses):
HFC-365mfc and HFC-152a (70:30);
HFC-365mfc and HFC-32 (
70:30);
HFC-365mfc, HFC-152a and CO
2
(60:30:10);
HFC-365mfc, HFC-32 and CO
2
(60:30:10);
HFC-365mfc, HFC-152a and butane (60:30:10);
HFC-365mfc, HFC-32 and butane (60:30:10);
HFC-365mfc, HFC-152a and HFC-134a (60:25:15);
HFC-365mfc, HFC-32 and HFC-134a (60:25:15);
HFC-365mfc and dimethyl ether (80:20);
HFC-365mfc and pentane (50:50);
HFC-365mfc and propane (70:30);
HFC-365mfc and ethane (90:10);
HFC-365mfc, pentane and CO
2
(45:45:10);
HFC-365mfc, butane and CO
2
(50:40:10);
HFC-365mfc, propane and CO
2
(70:20:10);
HFC-365mfc, ethane and CO
2
(90:5:5).
Preferred blowing agent compositions contain 1,1,1,3,3-pentafluorobutane and/or difluoromethane and 1,1,-difluoroethane or they consist of these compounds. In particular, compositions are used, which contain or consist of 10 to 70% by weight of HFC-365mfc and 90 to 30% by weight of HFC-152a and/or HFC-32.
A preferred embodiment, the preparation of polyurethane (PU) foams, is explained in detail.
The outstandingly useful flame retardants include, for example reactive flame retardants, such as brominated polyols. Flame retardants, based on organic phosphorus compounds, such as phosphate esters and phosphonates, are likewise suitable. These have organic groups, which may be substituted by one or more halogen atoms. The organic groups have an aliphatic or aromatic character. Very well suitable are phosphate esters and phosphonate esters, which are substituted by three C
1
to C
6
alkyl groups, which may have one or two halogen atoms, such as trischloroisopropyl phosphate, trischloroethyl phosphate, trischloropropyl phosphate, dimethylethyl phosphate, trisdichloroisopropyl phosphate, dimethylmethyl phosphonate; trischloropropyl phosphate is preferred.
One embodiment of the inventive method of producing polyurethane foams provides that if a) is HFC-365mfc and b) 1,1,1,2-tetrafluoroethane (HFC 134a); 1,1,1,3,3-pe
Kruecke Werner
Zipfel Lothar
Cooney Jr. John M.
Crowell & Moring LLP
Solvay Fluor und Derivate GmbH
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