Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1992-12-28
1994-12-20
Marquis, Melvyn I.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525438, 525439, 525444, 525466, 525533, C08F 2000
Patent
active
053746902
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to block copolyester resins and to the method of preparation thereof.
It is known that blends of polyester resins can be prepared by extruding the resins in a mono or twin screw extruder.
The extrusion temperature is not too much higher than the melting point of the polyester and the residence time is the shortest possible to avoid undesired ester interchange reactions (Journ Pol. Sci. Polym Physics Vol. 18, 2299-2301--1980).
The resins do not present properties of practical interest.
The availability of block copolyester containing block selected in function of the desired properties of the end article and upgraded to sufficiently high molecular weight opens the perspective of broad range of applications in any sector from that of the blow molding to the coating, tubing and foaming.
Such copolyesters however are not known.
It has now surprisingly found that it is possible to prepare block copolyesters wherein two different polyester blocks are bounded to an organic radical. The preparation is made by blending in the molten state different polyester resins in the presence of a compound capable of additive reactions with the terminal COOH and OH groups of the polyester, pelletizing the molten product and then subjecting the granules to upgrading reaction in the solid state at temperatures from 100.degree. to 220.degree. C.
The copolyester compositions of this invention comprise block copolymers of formula organic radical, deriving from a bifunctional compound capable of additive reactions with the COOH and OH terminal groups of the polyester.
Preferably A is a radical deriving from a dianhydride of a cycloaliphatic or aromatic tetracarboxylic acid.
Preferably X and Y are block of polyethyleneterephthalate, copolyethylenterephthalate containing up to 20% by weight of the resin of units deriving form isophthalic acid or from 5-tert-butyl 1.3 benzene dicarboxylic acid.
X or Y may be also blocks from polybutyleneterephthalate, polycyclobenzenedimethylterephthalate, polycaprolactone or polyester elastomers. Preferred are the compositions in which the copolymers contain blocks of polyethyleneterephthalate and copolyethyleneterephthalate.
Depending on the composition of the starting polyester mixture, the block copolymer can be present in different proportion with respect to the polyesters of the starting mixture.
Besides the block copolymer, the compositions may contain also the homopolymer of the starting polyesters.
The upgrading reaction by polyaddition in the solid state comprises a crystallization step after blending the resins with the upgrading additive and pelletization of the resin.
The crystallization step is carried out at temperatures higher than the TG of the polyester and comprised in general between 130.degree. and 180.degree. C.
The process is preferably carried out in continuous way using continuous crystallizers and reactors where the chips are fed counter currently with a stream of a heated gas, e.g. air, nitrogen or other inert gas, such as carbon dioxide.
The upgrading additive is preferably selected from the group consisting of pyromellitic dianhydride, benzophenone dianhydride, 2,2-bis(3,4-dicarboxyphenyl) propane dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, bis(3,4-dicarboxyphenyl) ether dianhydride, bis(3,4-dicarboxyphenyl) thioether dianhydride, bisphenol A bisether dianhydride, 2,2-bis(3,4 dicarboxyphenyl) hexafluoropropane dianhydride, 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, bis(3,4-dicarboxyphenyl) sulfone dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, hydroquinone bisether dianhydride, bis(3,4-dicarboxyphenyl) sulfoxide dianhydride, 3,4,9,10-perylene tetracarboxylic acid dianhydride and mixtures thereof.
The most preferred aromatic dianhydrides are pyromellitic dianhydride and 3,3',4,4' benzophenonetetracarboxylic acid dianhydride and mixtures thereof.
Dianhydrides of aliphatic, cycloaliphatic and tetrahydrofuran tetracarboxylic acids are also suitable
REFERENCES:
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Gulakowski Randy
Kolomayets Andrew G.
M. & G. Ricerche S.p.A.
Manzo Edward D.
Marquis Melvyn I.
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