Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Patent
1996-10-08
1997-12-30
Mosley, Terressa
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
528198, 528370, C08G 6400
Patent
active
057031967
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a process for producing a polycarbonate having terminal hydroxyl groups useful as a starting material for polyurethane in an emulsion, a coating, a thermoplastic elastomer, a paint, an adhesive or the like.
As the process for producing a polycarbonate having terminal hydroxyl groups, there is a process which comprises subjecting a carbonate monomer along with a divalent alcohol monomer to interesterification to obtain a low molecular weight polycarbonate and then self-condensing this to obtain a high molecular weight polycarbonate as disclosed in JP-B-63-12,896 (corresponding to U.S. Pat. No. 4,131,731). In this process, self-condensation is effected in the latter half of the process, so that the amount of the divalent alcohol monomer distilled out becomes large, and therefore, the yield of polycarbonate is low and it is necessary to apply severe conditions of high temperature and high vacuum over a long period of time. When a product is exposed to a high temperature for a long period of time, the coloration of the product is feared, and decomposition of product becomes easy to cause. Therefore, in order to keep a high vacuum under such conditions, a cooling trap having a higher performance and a vacuum pump of a larger size become necessary. Under such circumstances, there has been desired a development of a process for producing a polycarbonate more economically without applying severe conditions of high temperature and high vacuum over a long period of time.
In particular, when a butanediol type polycarbonate is produced using 1,4-butanediol as the divalent alcohol monomer according to the above-mentioned prior art, there have been such problems that tetrahydrofuran is easily produced as a by-product by reaction of the carbonate monomer with the butanediol and/or decomposition of the 1,4-butanediol residue terminals of the polycarbonate produced and that in the step of self-condensation requiring the application of severe conditions of high temperature and high vacuum, the reaction under reduced pressure becomes difficult because of the large amount of hydrofuran produced as a by-product and the molecular weight does not become high. Moreover, since it is difficult to completely trap the tetrahydrofuran in the vacuum system using a cooling trap, an equipment such as an absorption tower or the like becomes necessary for lowering the concentration of the tetrahydrofuran discharged into the atmosphere through the vacuum pump and the commercial scale production of a high molecular weight butanediol type polycarbonate has been difficult.
However, 1,4-butanediol is very inexpensive and hence a butanediol type polycarbonate produced using the same can become very inexpensive. In addition, it is clear that a polyurethane obtained using a low molecular weight butanediol type polycarbonate is superior in chemical resistance to other polyurethanes obtained using other polyols; however, even when the low molecular weight butanediol type polycarbonate is used, for example, as the soft segment of a polyurethane, the proportion of the hard segment becomes high and no urethane having soft and good feeling is obtained. Therefore, the low molecular weight butanediol type polycarbonate has not been so often used as the starting material for polyurethane.
Under such circumstances, a development of a process for producing a high molecular weight butanediol type polycarbonate has been desired.
In JP-A-4-153,218, a process is proposed which comprises subjecting a carbonate monomer and a divalent alcohol monomer to interesterification, to obtain a low molecular weight polycarbonate, then adding thereto a carbonate monomer and further subjecting the resulting mixture to interesterification reaction to heighten the molecular weight. This process is effective for heightening the conversion of the dihydric alcohol monomer to increase the one batch yield; however, the reaction for heightening the molecular weight is not fast, and the production of polycarbonate per unit volume per unit time is small. In ad
REFERENCES:
patent: 4131731 (1978-12-01), Lai et al.
patent: 4978691 (1990-12-01), Murai et al.
patent: 5322919 (1994-06-01), Kurosawa et al.
Funakoshi Shinji
Kawai Kenzou
Asahi Kasei Kogyo Kabushiki Kaisha
Mosley Terressa
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