Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1998-04-23
2000-04-18
Foelak, Morton
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521172, 528 1, 528 745, 528 80, 528 85, C08G 1832
Patent
active
060516232
DESCRIPTION:
BRIEF SUMMARY
APPLICATION FIELDS
The present invention concerns polymers made of cashew nut shell oil (hereinafter referred to as CNSO), which together with di- and/or polyisocyanates can constitute many different molecular structures.
PRIOR ART
CNSO is a by-product of the cashew nut preparation food industry.
This liquid, which is found in the shell of the nut and is released when the shell is opened, is a 9:1 mixture of a fatty acid (anacardic acid, which has one phenyl radical at the benzenoid ring) and a diphenol (Cardol), both with side chains with 15 carbon and 27 hydrogen atoms and one with three double bonds.
The current uses of this product are mainly in the field of phenoplastics, where, by neglecting the double bonds of the chains: products characterised by their great resistance to heat and abrasion.
Showa's Japanese patent no. 33-27 905 of 1.sup.st Oct. 1958 contains a new application for this product by reacting it with di- and/or polyisocyanates. This method of manufacturing polyurethane, owing to a reaction between the CNSO and a polyisocyanate, demonstrates the possibility of dimerising the CNSO in the presence of a polymerisation catalyst at temperatures of up to 140.degree. C. The result of this method is a product with high viscosity, which has to be washed and dried before it is used practically with isocyanates.
German patent no. 2152 606 of 22.sup.nd Oct. 1971, belonging to Bayer AG, shows in the context of a process for the internal plastification of an epoxy resin, that phenyl radicals can be used to temporarily block the NCO radicals from the excess polyisocyanates of the prepolymers. After a subsequent reaction, when tertiary amines take the place of the phenyls, these remain free in the final product.
CONTENTS OF THE INVENTION
The present invention demonstrates a simpler way of manufacturing polymers made of CNSO and a cleaner way of manufacturing products with blocked NCO radicals, by linking up the free phenyl radicals to an available aldehyde. Thanks to the processes invented, it is possible to manufacture products as varied as rigid foam, elastomers, thermoplastic rubber or single-component resins without solvents.
DESCRIPTION OF THE INVENTION
CNSO can, together with the polyisocyanates, react on three different levels:
The first level is always interesting when a product is intended to be expanded. Thus, with the simultaneous attack of a polyisocyanate on the three levels, a rigid foam of excellent quality can be obtained. Different components which can be polymerised can be obtained either by simply heating the CNSO or by the following method: add a small quantity of diluted sulphuric acid to the CNSO and heat. At around 130.degree. C., the CO.sub.2 of the carboxyl is released. By heating further, concentration and dimerisation increase. By adding a polyisocyanate, more or less reticulated products are obtained.
In relation to the above-mentioned Bayer patent and the possibility of temporarily blocking the NCO radicals of an isocyanate, the following method is used: CNSO is heated up to 180.degree. C. with a small quantity of diluted sulphuric acid, it is left to cool down to 120.degree. C. and then an equivalent quantity of TDI is added. This mixture is kept at 80.degree. C. until there is no more free isocyanate.
Starting with such a product and adding a second one, it is easy to manufacture a single-component glue.
This second component would be, for example, a mixture of CNSO and Furfural, which had been heated beforehand with a small quantity of triethylamine and then cooled down to room temperature. (It has been discovered that such a mixture remains stable at this temperature.)
If the quantity of Furfural in the second mixture corresponds to the total quantity of decarboxylated CNSO and the mixture of the first preparation is heated up with the mixture of the second preparation to a temperature higher than 150.degree. C., then the initially blocked NCO radicals will be released and react with the COOH of the second preparation. The phenyl radicals react with the Furfura
REFERENCES:
patent: 4301254 (1981-11-01), Blount
patent: 4631322 (1986-12-01), Isayama et al.
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