DE1795637C3 - Use of polyester imides for electrical insulation - Google Patents

Description

The older patent application DE-AS 14 45 263 describes a process for the production of polyesterimides, which is characterized in that polybasic carboxylic acids with polyhydric alcohols, optionally with the addition of oxycarboxylic acids, one or more of the starting materials used consist wholly or partially of those compounds that are between the functional groups as Links one or more five-link, with to aromatic nuclei contain fused imide rings, condensed in a manner known per se In a manner known per se, instead of the free acids and / or alcohols, also their reactive derivatives can be used, and polyester-forming components, the five-membered imide rings in the specified Contain sense, can also be condensed into preformed polyester.

DE-AS 14 45 263 also describes the use of the polyesterimides produced in this way for stoving films described and claimed on electrical conductors, the use of the in the Claims 1 to 4 of the earlier patent 12 09 686 named reaction products of trimellitic anhydride with monoethanolamine and ethylene glycol in a molar ratio of 1 mol of trimellitic anhydride to 0.35 to 0.8 mol of monoethanolamine and 0.4 to 2 mol of ethylene glycol or the use of such reaction products, in which up to 40% of the amount used trimellitic anhydride by an equivalent Amount of pyromellitic anhydride have been replaced and / or the use of such reaction products, in which up to 30% of the amount used monoethanolamine by an equivalent amount of one aliphatic, aromatic or mixed aliphatic-aromatic diamines have been replaced, and / or the use of such reaction products in which up to 0.4 mol of ethylene glycol, based on I mol Trimellitic anhydride, has been replaced by an equivalent amount of a trihydric or polyhydric alcohol are not claimed in this embodiment.

In the parallel patent application DE = OS 14 95 100 a significant simplification of the manufacturing process for polyesterimides is envisaged, which the Use of preformed starting materials that act as a link between the functional groups or contain several five-membered imide rings fused to aromatic nuclei. These Rather, starting materials are formed in situ in the presence of the other reactants the separate production of these starting materials containing imide groups, as well as their isolation and work-up, are dispensed with and storage.

The object of the invention is to provide a material in the highly specialized field of electrical insulating materials to make available that are easy to manufacture and process with high quality properties in the End product, d. H. the finished electrical insulation, connects

The invention accordingly relates to the use of polyesterimides produced by condensation of polybasic carboxylic acids with polybasic alcohols, optionally with the addition of Oxycarboxylic acids, with one or more of the starting materials used wholly or partially those compounds exist that act as a link between the functional groups or contain several 5-membered imide rings fused with aromatic nuclei, have been produced and at which the compounds containing imide groups used as starting materials in the presence of the other Reactants prepared in situ for stoving insulation on electrical conductors.

The production of the polyesterimides used according to the invention is not claimed here, it is rather, the subject of the parallel patent application DE-OS 14 95 100. From these manufacturing information however, if the particularly preferred structure of the polyesterimides used according to the invention is derived, see above that the most important information on the production not claimed here is described below are.

Aromatic compounds are used to form the imide-containing components in the polyesterimide have been used, which in addition to a S-membered cyclic acid anhydride group or their equivalents reactive groups as further functional groups at least one carboxyl group, carboxylic acid ester group, Have hydroxyl group or carboxylic acid anhydride grouping and furthermore such Compounds which, in addition to a primary amino group, have at least one further primary amino group, contain a carboxyl group or a hydroxyl group as a reactive group, the Proportion of the imide group-forming carboxylic acid component at least equivalent to the amount of amine used is

These imide-containing components can be used in the presence of the pure polyester component or their starting materials are produced and then reacted immediately afterwards or at the same time have been. The order in which the starting materials are used and the sequence of reactions is not decisive. So it is possible in the production of polyester imides, for example, first of all pure polyester component through esterification of raw materials that cannot form imide groups, produce, then the resulting reaction product the starting materials for! the formation of the imide groups Add compounds to react these with one another and then the imide groups containing To let the compound react into the polyester resin. But it is also possible and sometimes It is expedient and advantageous to combine the starting materials for the formation of the component containing imide groups with the other raw materials for the polyester imides

to mix and implement the implementation in one go.

The starting materials for the components containing imide groups are in particular as acid components those compounds have been used which, in addition to a 5-membered cyclic acid anhydride group an o-position aromatic dicarboxylic acid have at least one further functional group. This functional group can be a carboxyl, carboxylic acid anhydride, carboxylic acid ester or hydroxyl group be. Instead of the cyclic acid anhydride group, this acid component can also contain other contain equivalent reactive groups for imide formation of the cyclic acid anhydride group, e.g. B. 2 on adjacent carbon atoms of the aromatic System-bound carboxylic acid groups or their esters, half-esters or half-amides.

The amine components of the compounds containing imide groups are derived from such compounds which contain at least one other reactive group in addition to a primary amino group, this further reactive group being a carboxyl, hydroxyl or a further primary Can be amino group. The free primary amino groups are functionally equivalent to derivatives of the same, z. B. salts with carboxylic acids, amides, lactams and polyamides, provided that the therein contained amino group is reactive for imide formation

Those polyesterimides which contain imide groups are particularly important for the invention Part of the reaction product of trimellitic acid or trimellitic anhydride and ρ, ρ'-diaminodiphenylmethane contain.

In the case of the production of the polyesterimides, which is not claimed here, the respective set amounts are Appropriately, starting materials should be chosen so that the proportion of the imide group-forming acid component is at least equivalent to the amount of amine used. Otherwise, part of the Nitrogen of the amine component not in the desired form of a cyclic imide ring, but as significantly more oxidation-sensitive amide groups are present. On the other hand, there is an excess of the acid component compared to the amine component is quite permissible, since the carboxylic acid, Carboxylic acid ester or carboxylic acid anhydride groups with the polyhydric alcohols below React ester formation.

The following example compares the results obtained according to the invention on the one hand (tests 1 and 2) and on the other hand with polyesterimides which have been prepared according to the teaching of the earlier law DE-AS 14 45 263 in such a way that the imide groups are initially containing dicarboxylic acid from 2 molar parts of trimellitic anhydride and one molar part ρ, ρ'-diaminodiphenylmethane and this imide-containing dicarboxylic acid is then reacted with the other components of the polyesterimides. O ₀

example
Attempt 1

388 g of dimethyl terephthalate, IHG ethylene glycol and 6s 75 g of glycerol are esterified in known manner at temperatures from 140 to 200 "C together with elimination of methyl alcohol and then added 80 g of technical cresol. After cooling to 8O ⁰ C the melt are 144 g of trimellitic anhydride and 74 g ρ, ρ'-diaminodiphenylmethane added and the temperature is then slowly increased to 215 ° C at about 140 ⁰ C is the melt turbid, light brown and highly viscous, but less viscous again on further temperature increase, and the haze gradually disappears.

After the melt has become clear at 215 ° C, 1 g of cadmium acetate is added and the cre: ol im Vacuum distilled off at 155.degree. C. The condensation is then continued at 215.degree. C. for about 3 hours.

Attempt 2

388 g of dimethyl terephthalate, 111 g ethylene glycol, 75 g of glycerol, 150 g of cresol, 144 g of trimellitic anhydride and 74 g of ρ, ρ'-diaminodiphenylmethane are melted together, and the temperature is gradually increased, while at about 130 ⁰ C the deposition of the diimide-dicarboxylic acid begins

With a further slow increase in temperature, methanol and water distill off. After 215 ° C are reached, this temperature is maintained for 3 hours and the resulting melt is again clear. Then 1 g of cadmium acetate is added. Then the cresol is at 175 ° C in a vacuum distilled off and the condensation continued for a further 3 hours at 225 ° C

The following experiments show that the polyesterimides produced by the process according to the invention are identical in their properties to polyesterimides, in their production one of preformed starting materials ran out, which between the functional groups as a link or several five-membered fused with aromatic nuclei Imide rings included.

Comparative experiment 1

According to the process of the earlier right DE-AS 14 45 263, 388 g of dimethyl terephthalate, 111 g of ethylene glycol and 75 g of glycerol were ^{transesterified with one another in a known manner at temperatures of 140 to 205 0} C with elimination of methyl alcohol 74 g of ρ, ρ'-diaminodiphenylmethane produced reaction product at 180 to 215 ° C in two portions in the terephthalate resin

After this product had been completely absorbed in the terephthalate resin, 1 g of cadmium acetate was added and condensation was continued for a further ^{3 hours at 215 ° C., finally under vacuum.}

Comparative experiment 2

144 g of trimellitic anhydride, 74 g ρ, ρ'-diaminodiphenylmethane and 500 g of technical-cresol were heated with vigorous stirring, at 15O ⁰ C the resulting suspension was very highly viscous. The temperature was increased to 195 ° C. and 27 ml of water were distilled off. At 120 ° C., 200 ml of cresol were then distilled off in vacuo and 388 g of dimethyl terephthalate, 111 g of ethylene glycol and 75 g of glycerol were added to the suspension of the diimide dicarboxylic acid formed.

The mixture was heated and methyl alcohol and water distilled off. The temperature was increased to 215 ° C and held until the resin melt became clear. Then I g of cadmium acetate added and at 170 ° C in a vacuum that

remaining cresol distilled off. Then the Melt post-condensed for a further 3 hours at 215 ° C.

The products obtained according to these tests and comparative tests were each in hot condition 450 g of technical cresol dissolved and their solutions each with a mixture of 9 g of butyl titanate and 27 g Cresol added.

After diluting with a mixture of two parts solvent naphtha and one part cresol to one Solids content of 34% in each case resulted in solutions whose viscosities according to DIN 53 211 were Product according to experiment 1 108 seconds, in experiment 2! 20 seconds, in the case of the product according to comparative experiment 1 120 seconds and, for the product according to the comparative experiment, were 2112 seconds.

These polyesterimide solutions were in continuous Procedure under the following data on copper wire. 1 mm diameter painted.

Horizontal wire enamelling oven, 3.5 m long, oven temperature 470 ° C ₁

Application device made of roll and felt, 6 orders,

Take-off speed 4 m / min, application thickness (increase in diameter of the wire) 0.05 mm.

The lacquer insulation was tested comparatively on the four samples obtained in this way, whereby showed that the two products produced according to the simplified process correspond to those according to the comparative tests manufactured products are equivalent. The following tests were carried out on the wire samples:

a) The pencil hardness of the insulation has been audited · have been kept on the untreated enamel wire as well as to the patterns' / 2 hour at 6O ⁰ C in either benzene or ethyl alcohol.

b) For the thermal shock test, a wire was annealed helically around a mandrel of diameter of the wire 1 hour Dei 155 ⁰ C. A wire coil around a mandrel three times the wire diameter was tempered at 200 ° C. for 1 hour. After this treatment, no cracks or defects in the insulating varnish layer could be seen.

c) For the heat aging test, the wire was ^{aged for 16 hours at 200 °} C. The elongation of the polyesterimide film and the appearance of a wire helix which was wound around a mandrel four times the wire diameter were then tested. In this winding sample, no cracks or holes could be seen in the insulating layer after winding.

d) In the torsion test for adhesive strength and flexibility of the insulating film, a piece insulated wire 28 cm long twisted around its own axis until the first damage the paint layer showed.

The results of the tests carried out are summarized in the following table:

Type of exam attempt 2 Comparative experiment 2 1 4H 1 4H a) Pencil hardness 4H 3H 4H 3H after storage in benzene 3H 2H 3H 3 H after storage in alcohol 3H 3H b) thermal shock test Well Well by tempering at 155 ° C Well Well Well Well by tempering at 200 ° C Well Well c) thermal aging test 21% 24% by stretching 23% Well 22% Well by wrapping test Well 113 Well 1.10 d) torsion test 108 112 (Number of revolutions)

Claims (1)

Claim: Use of polyesterimides obtained by condensation of polybasic carboxylic acids with polyhydric alcohols, optionally with the addition of oxycarboxylic acids, one or several of the starting materials used consist entirely or partially of compounds that between the functional groups as a link ι ο containing one or more five-membered imide rings fused to aromatic nuclei have been and in which the compounds containing imide groups used as starting materials in the presence of the other reaction participants mer have been made in situ, for burn-in insulation on electrical conductors.