Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From aldehyde or derivative thereof as reactant
Patent
1999-01-15
2000-03-07
Truong, Duc
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From aldehyde or derivative thereof as reactant
528259, 528266, 528268, 528502R, 528503, C08G 400
Patent
active
060342013
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a novel method for the manufacture of urea formaldehyde resins as well as these resins themselves.
2. Description of the Related Art
The closest prior art is European Patent 0 319 751, which describes urea formaldehyde resin, its manufacture and use.
claim 1 of European Patent 0 319 751 relates to a strongly exothermically hardening urea formaldehyde resin obtained by the condensation of urea with formaldehyde in an alkaline environment which can be obtained by performing a first Condensation Stage I as follows: preferably 1.7 to 2.2 Mol formaldehyde in the form of solid paraformaldehyde, in an exclusively alkaline medium, with an initial pH of 8-12, and preferably 9-11. the presence of 2.5 to 50 m Mol guanine base and 0 to 80 m Mol NH.sub.3 per Mol of formaldehyde. minutes, followed by a Second Condensation stage II is conducted as follows:
This method of the prior art for the manufacture of strongly exothermically hardening urea formaldehyde resins works in two condensation stages and is well suited for use on a laboratory scale or a small industrial scale, whereby the respective amounts manufactured can be approximately 100 kg.
It has since been found, however, that this method of the prior art cannot be used under industrial conditions, i.e. for batches in the range of tons, or at least not optimally, because the resulting resins cannot always be used for the manufacture of high-quality foam products.
SUMMARY OF THE INVENTION
The object of this invention is therefore to dramatically improve the method described in European Patent 0 319 751 so that it can be used on an industrial scale, and whereby the resins manufactured according to this invention can be used for the manufacture of high-quality foam products in the same manner as those that were obtained on a laboratory or small industrial scale using the method described in European Patent 0 319 751.
The invention teaches the following method for the accomplishment of the object described above: temperature of 60 to 120.degree. C., preferably to 80 to 100.degree. C. molar quantities are added to the heated paraformaldehyde and are intensively dry-mixed and heated until, after approximately 15 minutes, a temperature of 80 to 110.degree. C., preferably 85 to 100.degree. C. has been reached. to the heated mixture and heated further, whereby within 10 minutes the mixture is liquefied and in spite of the added thermal energy, is cooled to 65.degree. C., and the mixture is heated by the further additional of thermal energy to the boiling range of approximately 103 to 110.degree. C., and is condensed in the first condensation stage, whereby the beginning of the Condensation Period I is arbitrarily set at a temperature of 90.degree. C., and the Condensation Period I is 30 to 100 minutes, preferably 50 to 85 minutes. urea, dicyandiamide etc. is added to the boiling mixture in a corresponding molar ratio, and is condensed in a second condensation stage for 90 to 180 minutes at a condensation temperature of 105 to 120.degree. C. boiling heat with lactic acid, and the resin is cooled for approximately 120 minutes to approximately 25 .degree. C.
The molar quantities used theoretically are the same as in the reference cited by the closest prior art, which is European Patent 0 319 780.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The essence of this invention is explained in greater detail below on the basis of the following exemplary embodiments which represent the preferred embodiments. paraformaldehyde, and heated for 15 minutes to approximately 90.degree. C. temperature drops to approximately 65.degree. C. I begins, boiling range approximately 10. 75 minutes, and dissolved. The temperature drops to approximately 90 .degree. C. The Condensation Period II, namely 120 minutes, begins upon the addition of the urea. A boiling range of approximately 114 to 110.degree. C. is reached. Condensation Period II is 120 minutes. 25.degree. C.
The resulting resin has a viscosity of 240
REFERENCES:
patent: 5010164 (1991-04-01), Schollhorn
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