Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2002-01-10
2003-12-09
McKane, Joseph K. (Department: 1712)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
active
06660869
ABSTRACT:
BACKGROUND OF INVENTION
(1) Field of Invention
The invention relates to a process for the preparation of an aromatic bisoxazoline such as for example phenylene-bis-oxazoline (PBO). The invention also relates to a powder paint binder composition and to a polymer composition comprising the aromatic bisoxazoline obtained with the process according to the present invention.
(2) Discussion of Prior Art
The preparation of an aromatic oxazoline such as for example 1,3-phenylene-bis-oxazoline is described in Liebigs Ann. Chem. (1974, 996-1009) by Witte and Seeliger. The product obtained with this process shows discolouration. Furthermore the process is relatively expensive because of the use of nitrites.
SUMMARY AND OBJECT OF INVENTION
It is the object of the present invention to provide a cheaper process for the preparation of an aromatic bisoxazoline such as for example PBO. The process has also to result in a product with the required properties.
The invention is characterised in that, in a first step, an aromatic carboxylic acid or an ester hereof reacts with an alkanolamine, after which the hydroxyalkylamide obtained is in a second step converted into an aromatic oxazoline in the presence of a catalyst.
The process according to the invention results in a relatively cheap product. This product is suitable to be used for example as a crosslinking agent in a powder paint binder composition or as a chain extender in polymer compositions.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS
Suitable aromatic carboxylic acid or esters are for example di- or tricarboxylic acids or esters such as for example terephthalic acid, isophthalic acid, di(C
1
-C
4
)alkyl terephthalate and/or di(C
1
-C
4
)alkyl isophthalate.
Preferably dimethyl terephthalate and dimethyl isophthalate are applied.
Examples of suitable alkanolamines may be represented according to formula (I):
where R
1
, R
2
and R
3
may be the same or different and may independently of one another be H, or a (C
6
-C
10
)aryl or (C
1
-C
8
)(cyclo)alkyl radical or CH
2
OH.
Examples of suitable alkanolamines are ethanolamine, 1,1-dimethylethanolamine, isobutanolamine, &bgr;-cyclohexanolamine, isopropanolamine, 2-aminopropanol, 2-methyl-2-aminopropanol and/or trishydroxymethylmethylamine.
Preferably ethanolamine and/or isopropanolamine are applied.
Preferably the catalyst in the second step is an acid catalyst or a basic catalyst.
According to a preferred embodiment of the invention the catalyst is phosphinic acid, a (C
1
-C
26
) alkyl phosphinic acid, a (C
6
-C
20
) aryl phosphinic acid or an ester or an anhydride derived from any one of these acids or a catalyst with a cyclic structure such as 1,8-naphthalene diylphosphine ester acid (for example Struktol Polydis PD 3710™).
According to another preferred embodiment of the invention the catalyst is a compound according to formula (II) or formula(III):
where
R
4
=H, (C
1
-C
26
)alkyl or (C
6
-C
20
)aryl
R
5
=H, (C
1
-C
26
)alkyl or (C
6
-C
20
)aryl and
R
6
=H, (C
1
-C
26
)alkyl or (C
6
-C
20
)aryl.
According to a further preferred embodiment of the invention the catalyst is phenyl phosphinic acid.
The amount of catalyst in the second step will generally be between 0.05 and 3 wt. % (relative to the hydroxyalkylamide). Preferably this amount is between 0.5 and 2.2 wt. %.
Preferably there is no catalyst applied in the first step, however a catalyst may optionally also be added during the first step in an amount between for example 0.05 and 3 wt. %.
Suitable catalysts are, for example, metal salts of aliphatic carboxylic acids such as zinc acetate, magnesium stearate, lithium acetate, nucleophilic tertiary amines such as for example diaza[2,2,2]tricyclooctane (DABCO), diazabicycloundecene (DBU), dimethylaminopyridine (DMAP) and the catalysts mentioned for the second step.
Preferably, the catalyst used in the second step is the catalyst used in the first step.
The aromatic bisoxazoline obtained with the process according to the invention may be for example 1,3-PBO, 1,4-PBO, 1,2-naphthalene bisoxazoline, 1,8-naphthalene bisoxazoline, 1,1
1
-dimethyl-1,3-PBO and 1,1
1
-dimethyl-1,4-PBO.
According to another preferred embodiment of the invention the aromatic oxazoline is 1,4-PBO (2,2
1
-(1,4-phenylene)bis-2,(4,5-dihydrooxazole).
Usually an excess amount of amine relative to the acid or ester is used in the first step. The molar ratio is usually between 1:2 and 1:4.
The reaction temperature in the first step will usually be between 20° C. and 200° C. and will be preferably between 70° C. and 180° C.
The temperature in the second step is usually between 100° C. and 250° C. and is preferably between 125° C. and 200° C.
This reaction may be carried out either with or without a solvent.
Preferably, the reaction in the second step is carried out in the presence of a solvent. Suitable solvents include for example xylene, propylene carbonate and/or acetic anhydride.
Preferably, the solvent is propylene carbonate.
On heating for example bis(2-hydroxyethyl)terephtphalamide a small amount of amine can be formed. Amines may deactivate some catalysts. Additives being capable to react with amines and that don't interfere with the desired reaction may optionally be used. Suitable additives include for example esters such as for example di- or tricarboxylic acids or esters such as for example terephthalic acid, isophthalic acid, di(C
1
-C
4
)alkyl terephthalate and/or di(C
1
-C
4
)alkyl isophthalate.
A product obtained with the process according to the invention may be used in many technical applications, such as for example as sizing agent, photosensitive material, solvent, cosmetic, membrane-separation material, emulsifier, surfactant, toner and monomer in polymer preparations.
The aromatic bisoxazoline obtained with the process according to the invention is particularly suitable for use as the crosslinking agent in a powderpaint composition or as a chain extender in a polyester or nylon composition.
Thermosetting powder paints have a better resistance to chemicals than thermoplastic powder paints. On account of this, attempts have for a long time been made to develop crosslinking agents and polymers for thermosetting powder coatings. Efforts are still being made to find binder compositions for thermosetting powder paints with good flow behaviour, good storage stability, low toxicity and good reactivity. A thermosetting binder composition for powder paints generally contains more than 50 wt. % polymer and less than 50 wt. % crosslinking agent.
The coating ultimately obtained with the powder paint must meet many, varying requirements. Various systems are known. Volatile components are released from some systems during curing. These systems present the disadvantage that they form coatings containing blisters and/or that undesired emissions are released. As far as the latter is concerned, the volatile component, if it is organic in origin, can cause undesired environmental or health problems. It has moreover been found that the desired properties of the powder paint or coating are not always all realised.
In many systems use is made of a polyester and a crosslinking agent that contains an epoxy group. In general, no volatile components are released from these systems. The use of bisphenol-A epoxy resins in so-called hybrid systems however results in coatings that show a relatively high degree of yellowing and chalking on exposure to UV light, while the commonly used cross-linking agent triglycidyl isocyanurate (TGIC) is toxicologically suspect.
It has been found that the use of the aromatic bisoxazoline, preferably PBO, as a cross-linking agent in binder compositions for powder paints results in a combination of highly desirable properties such as for example good flow behaviour and good resistance to chemicals, desired gloss without blistering of the surface up to and including layer thicknesses of at least 120 &mgr;m, a high resistance to scratching, good mechanical properties, good powder stability, good weather resistance and a good colour retention of the powder coating
Hendriks Patrick H. M.
Loontjens Jacobus A.
Plum Bartholomeus J. M.
Van Benthem Rudolfus A. T. M.
DSM N.V.
Saeed Kamal
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