Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1994-04-11
1996-10-29
Acquah, Samuel A.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
528272, 528302, 528308, 5283082, 5283083, 5283086, 528350, 528481, 528503, 525437, D02G 300, C08G 6926
Patent
active
055695108
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP93/01447, filed Jun. 8, 1993.
The present invention relates to a process for the production of polyester resins suitable for the manufacture of fibers and cords.
The polyester resins continuous production generally includes three stages: in the first one the esterification between an alkylenic glycol and an aromatic dicarboxylic acid, particularly terephthalic acid or the transesterification between an alkylenic glycol and a diester of dicarboxylic acid is carried out; the obtained product, prevalently formed of bis-beta-hydroxylethyleneterephthalate and of its oligomers, is passed to the second stage where it is polycondensed as polymer with higher molecular weight and finally it is further polycondensed in a third stage to the desired degree of intrinsic viscosity.
The melt polymeric mass can be sent to feed directly a spinnerets system; in this way the pelletization stage is avoided.
The reactor of the end stage polycondensation is generally formed by a cylinder with a rotating horizontal shaft, which maintains the highly viscous melt polymeric mass under agitation in order to allow the glycol removal from the melt mass.
The reactor is kept under high vacuum (less than 1.5 mm Hg) and the temperature is generally between 240.degree. and 330.degree. C.
Relatively long residence times are necessary to obtain the required intrinsic viscosity degree of the polymer resin (generally higher than 0.6 dl/g).
To increase the polycondensation speed it has been proposed to submit to polycondensation the bis-hydroxyethylene-terephthalate and its oligomers by feeding them as very thin film on an endless conveyor band (published Japanese application No. 5119/73 and European application No. 182 352).
The proposed method is very expensive and requires complicated equipment.
British patent No. 1,027,613 describes a method for polyester resins preparation suitable for fibers manufacture provided with better toughness, where the polycondensation stage is carried out in the presence of small quantities (0.1-2% mole on starting dicarboxylic acid) of a compound with three or more functional groups able to react with the ON and COOH endgroups.
Examples of utilizable polyfunctional compounds are glycerine, trimethylpropane, pentaerythrite, polycarboxylic acids, as trimesic acid and their anhydrides as trimellitic and pyromellitic anhydride.
The resulting polyesters are branched; the branching degree is not controllable, as the operating reaction conditions of high vacuum and the presence of the branching agent, do not allow to obtain reproducible results (see U.S. Pat. No. 4,217,440 that mentions the method of the above mentioned GB-1,027,613 patent, as example of conditions leading to non reproducible results).
Because the reaction cannot be controlled it is possible the formation of crosslinked products.
In the case of polyester resins preparation for fibers it is strongly requested that the polymer is linear.
It has now been found that it is possible to prepare polyester resins at high linearity degree with a simplified method which avoids the use of vacuum in the polycondensation end stage.
It has been unexpectedly found that by adding to the melt polymeric mass of the polycondensation end stage small quantity of a dianhydride of an aromatic tetracarboxylic acid and by passing an inert gas stream over the melt mass kept under agitation, it is possible to obtain, with high polycondensation speed, polyester resins of high molecular weight and substantially linear.
The result is unforseeable if one considers that the use of polyfunctional compounds as the dianhydrides of polycarboxylic acids in the polycondensation process leads to the uncontrolled formation of branched polyester resins containing crosslinking.
In the invention process, the dianhydride is used in a quantity between 0.1-3% by weight of the polyester resin.
The preferred dianhydride is pyromellitic anhydride.
The residence time is generally comprised between 5 and 30 minutes, preferential 10-20 minutes.
The amount of inert gas c
REFERENCES:
patent: 2965613 (1960-12-01), Milone et al.
patent: 3446778 (1969-05-01), Waller et al.
patent: 3553157 (1971-01-01), Dijkstra et al.
patent: 4176101 (1979-11-01), Leslie et al.
patent: 4234708 (1980-11-01), Edelman et al.
patent: 4273890 (1981-06-01), Hirzy
patent: 4382131 (1983-05-01), Binsack et al.
patent: 4598129 (1986-07-01), Borman et al.
patent: 4686262 (1987-08-01), Binsack et al.
patent: 4708975 (1987-11-01), Shain
patent: 4880860 (1989-11-01), Blocker
patent: 4942219 (1990-07-01), Yatsuka et al.
patent: 4981908 (1991-01-01), Wolfe, Jr.
patent: 5000991 (1991-03-01), Hayashi et al.
patent: 5049235 (1991-09-01), Barcus et al.
Yamamoto, et al., "Thermoplastic Polyester Resin Composition", Chemical Abstracts, vol. 89, No. 16, Oct. 16, 1978.
Mizuno, et al., "Fire-resistant Polyester Compositions", Chemical Abstracts, vol. 90, No. 4, Jan. 1, 1979.
Patent Abstracts of Japan, vol. 9, No. 78, Apr. 6, 1985.
Al Ghatta Hussain A. K.
Pizzetti Mario
Acquah Samuel A.
Manzo Edward D.
Murphy Mark J.
Ringsred Ted K.
Sinco Engineering S.p.A.
LandOfFree
Process for the production of polyester resins for fibers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the production of polyester resins for fibers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the production of polyester resins for fibers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1784613