Highly branched polyamide graft copolymers

Details Highly branched polyamide graft copolymers Highly branched polyamide graft copolymers

2000-06-29

2002-05-21

Woodward, Ana (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S326700, C525S328200, C525S374000, C525S375000, C525S540000, C424SDIG001, C528S324000, C528S329100, C528S335000, C528S350000

Reexamination Certificate

active

06391982

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to highly branched polyamide graft copolymers which are composed of a polyamine moiety and grafted-on polyamide chains.
2. Background of the Invention
Graft copolymers based on polyamine and polyamide are known. They may be prepared, for example, by cationic polymerization of caprolactam in the presence of polyethyleneimine hydrochloride dendrimers as core molecules (J. M. Warakomski, Chem. Mater. 1992, 4, 1000-1004). Compared with linear nylon-6, nylon-6 dendrimers of this type have markedly reduced melt viscosity and solution viscosity, but unchanged tensile strength, stiffness, melting points, enthalpies of fusion and barrier action with respect to oxygen.
A description of graft copolymers based on polyvinylamine and polyamide is provided in U.S. Pat. No. 2,615,863. U.S. Pat. No. 3,442,975 describes graft copolymers which are prepared by polymerizing lactams in the presence of high-molecular-weight polyethyleneimine.
DE 19 15 772 describes polymer blends prepared from a polyiminepolyamide graft copolymer, and also from a polyolefin and/or polyester, which are processed to give fibers which can readily be colored.
Finally, DE 196 54 179 describes H-shaped polyamides which are prepared from lactams or aminocarboxylic acids, from an at least trifunctional amine, from dibasic carboxylic acids and from monobasic carboxylic acid. The reference discloses a certain ratio between the two last-mentioned compounds and between these two compounds and the functional groups of the at least trifunctional amine. The products have improved melt stability.
However, in many applications where the use of such polyamide graft copolymers is desirable, it has become apparent that these graft copolymers have insufficient solvent resistance and fuel resistance. Properties which are in many cases unsatisfactory are hydrolysis resistance, alcoholysis resistance, environmental stress cracking resistance and swelling behavior, and also dimensional stability. Further, the barrier action with respect to diffusion is unsatisfactory. A need continues to exist for polyamine-polyamide graft copolymers which exhibit better solvent resistance and fuel resistance.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a polyamine-polyamide graft copolymer which exhibits better solvent resistance and fuel resistance.
Briefly, this object and other objects of the present invention as hereinafter will become more readily apparent can be attained by a graft copolymer prepared by a process comprising:
graft polymerizing polyamide-forming monomers selected from the group consisting of lactams and &ohgr;-aminocarboxylic acids and an oligocarboxylic acid selected from the group consisting of from 0.015 to about 3 mol. % of dicarboxylic acid and from 0.01 to about 1.2 mol. % of tricarboxylic acid, in each case the stated amounts of dicarboxylic acid and tricarboxylic acid being based on a molar amount of lactam, &ohgr;-aminocarboxylic acid or combination thereof, onto from 0.5 to 25% by weight, based on the graft copolymer, of a polyamine having at least 11 nitrogen atoms and a number-average molecular weight M
n
of at least 500 g/mol., wherein the amino group concentration in the graft copolymer ranges from 100 to 2500 mmol./kg.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the present invention the polyamine component of the graft copolymer is employed in the grafting reaction in an amount of from 0.5 to 25% by weight, preferably from 1 to 20% by weight and particularly preferably from 1.5 to 16% by weight, based on the graft copolymer. The polyamine has at least 11 nitrogen atoms and a number-average molecular weight M
n
of at least 500 g/mol., preferably at least 800 g/mol.
The amount of oligocarboxylic acid reactant is 0.015 to about 3 mol. % of dicarboxylic acid or from 0.01 to about 1.2 mol. % of tricarboxylic acid, in each case based on per mol. amount of lactam and/or &ohgr;-aminocarboxylic acid.
The amino group concentration in the graft copolymer is from 100 to 2500 mmol./kg.
The upper limits stated above for the dicarboxylic acid and tricarboxylic acid reactants are merely intended to ensure that the graft copolymer produced is thermoplastic and not crosslinked. According to current understanding these upper limits are good guide values. However, in individual cases, especially when using relatively high amounts of polyamine, even higher amounts of oligocarboxylic acid may be added. Graft copolymers of this type are also within the scope of the invention.
Examples of classes of the polyamine component employed in the present process for the preparation of graft copolymer are as follows:
polyvinylamines (Römpp Chemie Lexikon [Römpp's Chemical Encyclopedia], 9th edition, Vol. 6, p. 4921, Georg Thieme Verlag Stuttgart 1992);
polyamines prepared from alternating polyketones (DEA 196 54 058);
dendrimers, such as:
((H
2
N—(CH
2
)
3
)
2
N—(CH
2
)
3
)
2
)—N(CH
2
)
2
—N((CH
2
)
2
—N((CH
2
)
3
—NH
2
)
2
)
2
as described in DE 196 54 179, or
3,15-bis(2-aminoethyl)-6,12-bis[2-[bis(2-aminoethyl)amino]ethyl]-9-[2-[bis[2-bis(2-aminoethyl)amino]-ethyl]amino]ethyl]-3,6,9,12,15-pentaazaheptadecane-1,17-diamine as described by J. M. Warakomski in Chem. Mat. 1992, 4, 1000-1004;
linear polyethyleneimines which can be prepared by polymerizing 4,5-dihydro-1,3-oxazoles, followed by hydrolysis as described in Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry] Vol. E20, pp. 1482-1487, Georg Thieme Verlag Stuttgart, 1987;
branched polyethyleneimines which are prepared by polymerizing aziridines as described in Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Vol. E20, pp. 1482-1487, Georg Thieme Verlag Stuttgart, 1987 and generally have the following amino group distribution:
from 25 to 46% of primary amino groups,
from 30 to 45% of secondary amino groups, and
from 16 to 40% of tertiary amino groups.
The polyamine preferably has a number-average molecular weight M
n
of not more than 20,000 g/mol., particularly preferably not more than 10,000 g/mol. and in particular not more than 5000 g/mol.
Lactams and &ohgr;-aminocarboxylic acid which are used as polyamide-forming monomers contain from 4 to 19 carbon atoms, in particular from 6 to 12 carbon atoms. Particularly preferred lactams and &ohgr;-aminocarboxylic acids are &egr;-caprolactam, &egr;-aminocaproic acid, capryllactam, &ohgr;-aminocaprylic acid, laurolactam, &ohgr;-aminododecanoic acid and/or &ohgr;-aminoundecanoic acid.
The oligocarboxylic acid may be any desired di- or tricarboxylic acid having from 6 to 24 carbon atoms such as adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, trimesic acid and/or trimellitic acid.
If a dicarboxylic acid is employed, it is preferably used in an amount of from 0.03 to 2.2 mol. %, particularly preferably from 0.05 to 1.5 mol. %, very particularly preferably from 0.1 to 1 mol. % and in particular from 0.15 to 0.65 mol. % based on a molar amount of lactam or &ohgr;-aminocarboxylic acid used. If a tricarboxylic acid is employed, the amount is preferably from 0.02 to 0.9 mol. %, particularly preferably from 0.025 to 0.6 mol. %, very particularly preferably from 0.03 to 0.4 mol. % and in particular from 0.04 to 0.25 mol. %, based on a molar amount of lactam or &ohgr;-aminocarboxylic acid used. Tricarboxylic acid is used especially when molding compositions with increased melt stiffness are to be prepared for extrusion purposes.
If desired, an aliphatic, alicyclic, aromatic, aralkyl and/or alkylaryl-substituted monocarboxylic acid having from 3 to 50 carbon atoms, e.g. lauric acid, unsaturated fatty acids, acrylic acid or benzoic acid, may be employed as a regulator in the reaction. These regulators can reduce the concentration of amino groups without altering the form of the

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