DE2351078A1 - Aq. polyesterimide dispersion for wire lacquering - contg. water, polyesterimide particles of defined size and esterification catalyst - Google Patents

Abstract

Heat-hardenable coating compsns., present as aq. dispersions, consist, by wt., of (A) 50-80% water and (B) 20-50% polyesterimide present as particles having dia. =5 mu. (B) contains 0.2-10 wt.% of at least one esterification catalyst. Dispersion has pH 5-9. Used for wire lacquering, insulating metal conductors, esp. wires and rails. Dispersions have good processing ability and storage stability. Gloss and smoothness of stoved lacquers cannot be distinguished from lacquer of same binder applied from soln.

Description

Our reference: O.Z. 30 150 Ls / Wil 6700 Ludwigshafen, October 9, 1975

Coating agents for wire enamelling

The present invention relates to thermosetting coating compositions for wire lacquering based on aqueous polyesterimide dispersions.

The production of polyesterimides and the use of their solutions for wire enamelling is known and for example in DT = AS 1 445 263, 1 ^ 95 152 and 1 645 435.

^ In order to process Polyesterimidesungen well must be set relatively low Peststoffgehalte ,, In addition, the Polyesterimides need because of the specific solubility properties as a solvent or "solvent mixtures phenols, cresols, xylenols ^, N-Methylpyrrolldon etc _e are used are ^ the most sehwerflüchtig and expensive and sometimes have a very unpleasant odor. Up © ine environmental pollution by this solutionimittsl to v © pm @ id @ n, additional very expensive devices are necessary because it is hardly possible to completely eliminate these solvents in the processing plants by incineration, absorption or other measures that they do not exist Cause odor nuisance. Further complications in the processing of these solutions result from the fact that solvent residues are deposited in the exhaust air systems, where they coke and have to be cleared out from time to time because of the risk of fire and explosion, which again led to operational disruptions

The relatively low solids content of the polyesterimides solutions is also the cause of processing uncertainties, such as sagging, edge alignment with Lackierung® *! * as well as Blistering in the course of drying »

It is known to circumvent such problems in that the binders are in the form of aqueous plastic dispersions

566/73 50 98177096 7/2

- 2 - O.Z. 30 150

begins. However, the production in dispersion form is not always possible directly. In DT-PS 1 285 08I it was suggested that Polyester resins have to be mechanically comminuted and dispersed in water ^ these dispersions are, however, not very stable. Around keeping them in workable condition must be continuously filtered to remove the agglomerated particles and to prevent settling of the dispersions. The agglomeration and the settling can such. E.g. DT-OS 2 210 484 it can be seen that can also be prevented by adding certain high molecular weight auxiliaries. Anyhow that exists here Danger of changing some properties of the dispersions in a disadvantageous way, in particular the gloss and flow of the Paintwork impaired.

The object of the present invention is to present thermosetting coating composition for the Drahtlaokierung based on polyester-imides which do not have the abovementioned disadvantages of the solutions and better as aqueous dispersions Verarbeltungseigenschaftsn, in particular as regards storage capability QhriQ change of the resulted Agglomerationssustandes and better properties of the coatings obtained therewith as the known aqueous polyester or polyesterimide dispersions.

The present invention relates to thermosetting coating agents for wire enamelling based on aqueous polyesterimide dispersions, which are characterized in that they essentially consist of

(A) 50 to 80 wt.% Water and

(B) 20 to 50 weight percent polyesterimide in the form of particles with particle size chmesser as 5 / um,

where (B) 0.2 to 10% by weight of at least one esterification catalyst and the pH of the dispersion is between 5 and 9.

Particularly advantageous are those thermosetting coating compositions according to the invention, the component (B) is at least 80 wt.% Of particles having a particle diameter between 0.05 and 1.5 / um.

509817/0967

- 3 - OZ ₉ 30 150

The coating agents according to the invention can also additionally contain small amounts of up to 8 percent by weight, based on the Contain component (B), leveling agent, protective colloid and / or dispersing agent.

The polyesterimide suspensions according to the invention can be stored unchanged for months; H. a change in the state of agglomeration could not be determined on thin films or when testing the filter residue in / u sieves.

In the production of electrical insulation coatings on copper wire, there was no significant difference in the lacquer-related and electrical properties compared to coatings made from the same binder when they were applied from solution; the hardness of the coatings was even higher. The processability was particularly advantageous: in the case of the dispersions according to the invention, there was no environmental nuisance, but a higher processing speed, which in the case of wire enamelling is expressed in a take-off speed that is 1.5 to 1.7 times higher. In terms of processing technology, it is also advantageous that the suspensions according to the invention can be processed in a more concentrated manner than the solutions made from the same binder. For example, example, a wire-coating suspension of the present invention are 33 # ig coated from a bath by means of air knives or Abstreiffilzen, while the same coating binders from solution in the same machine at the same take-off speed is usually only 23- to 25 # ig to process was.

Odor nuisance in the painting room, as it is for dissolved wire enamels, are characteristic cannot be determined in the suspensions. There is also no need for environmentally unfriendly Substances through exhaust or sewer pipes.

Special ventilation measures can therefore be used during processing of the dispersions according to the invention, there are no systems for solvent recovery or solvent incineration are not required. As a result, the new coating agents also have a decisive economic impact on the known processes Benefits on.

509817/0967

- 4 - O.Z. 30 150

Among the polyesterimides according to the present invention are condensation products of polybasic carboxylic acids or theirs Derivatives with polyhydric alcohols and polybasic primary amines, optionally with the use of hydroxycarboxylic acids, To understand aminocarboxylic acids and amino alcohols with a limit temperature of> 150 ° C.

The limit temperature of the polyesterimides is defined here as the temperature at which, after 5000 hours of storage, there is no impairment of the properties, measured against the electrical Dielectric strength, thermal compressive strength and thermal shock behavior can be determined.

The following is to be stated in detail with regard to the thermosetting, thermostable storage-producing coating agents according to the invention: Polyesterimides can be made by a variety of methods. For example, their production can be carried out according to the in the procedures described in DT-AS 1 445 263, 1 495 152 and 1 645 435 take place.

It is characteristic of the polyesterimides to be used according to the invention that they are condensation products, which contain both ester and imide groups. In particular, those polyesterimides are advantageous as connecting links contain five-membered imide rings fused with aromatic nuclei. A typical such condensate exists z. B. from ethylene glycol, trishydroxyethyl isocyanurate, terephthalic acid, Trimellitic anhydride and 4,4'-diaminodiphenylmethane. Instead of these individual components, reaction products of individual components or precondensates can also be used for their production. for example the reaction product of 4,4'-diaminodiphenylmethane and trimellitic anhydride.

Depending on how the binders are manufactured, the imide rings are introduced by certain precursors, but they can also be generated simultaneously with the formation of the ester groups will.

509817/0967 / 5

- 5 - 0.Z. 30 150

The binders are particularly resistant to thermal loads, and the load-bearing capacity is higher * the more itnide groups are included. For their preparation, proportionally di- or higher-valent primary amines can be used together with compounds which contain two or more carboxylic acid anhydride groups, but preferably tetracarboxylic acid dianhydrides. As a rule, the procedure is therefore to first esterify the tetracarboxylic acid components with an excess of dihydric alcohols in a first reaction stage and then condense the esterification product with the polyvalent primary amines and any other binder components.

Polyesterimides which are suitable for the coating compositions according to the invention can, for example, be composed of the following components in the form according to = the following proportions exist?

1) 10 to 50 parts by weight of the reaction product of 2 moles of a cyclic anhydride an aromatic tri- cross tetra-carboxylic acid with ortho carboxyl groups and 1 mole of a diprimary amine or a compound with a primary amino group and a further functional group or from the individual components, with

2) Terephthalic acid and / or isophthalic acid and / or 4,4 '= 3enzophenonedicarboxylic acid or derivatives of these acids, especially their alkyl mono- and / or diesters ^ halides or anhydrides «

5) one or more polyhydric alcohols in proportions from 1 to 1.8 equivalents per equivalent of carboxylic acid.

Preferred embodiments of the polyesterimides to be used according to the invention contain mixtures of polyhydric alcohols which contain tris = (2-hydroxyethyl) isocyanate or tris-β = hydroxy-thylimide of molitic acid. Polyesterimides with a higher proportion of these polyols have particularly good heat resistance and resistance to the effects of heat choking.

As cyclic anhydrides, aromatic tri- or tetracarboxylic acids with ortho carboxyl groups, tri- • mellitic anhydride are particularly suitable and pyromellitic anhydride, and others

509817/0967

/ 6

- β - O.Z. 30 150

aromatic carboxylic acid anhydrides such as naphthalenetetracarboxylic acid dianhydrides or dianhydrides of tetracarboxylic acids with two benzene nuclei in the molecule, in which the carboxyl groups in 3 * 3'- and 4,4'-position, furthermore compounds such as 2,2 ', 3 * 3'-benzophenone-tetracarboxylic acid dianhydride.

Examples of dlpriraäre diamines are z. B. ethylenediamine, tetramethylehdiamln, hexamethylenediamine and other allphatic diprimary diamines ", particularly suitable are aromatic diprimary diamines such as benzidine, dietninodiphenylthiiethan, dialiaodiphenylsulfone, ethers, sulfoxide, tri-methylene diamines, also molecules with diamonds, phenylenediamines, toluenediamines, and xylenediamines such as bis (4-aminophenoxy) -1,4-benzene and cycloaliphatic diamines such as 4,4 ^I -Dlcyelohexylmethanediamine,

Also suitable are amino-containing compounds with a further functional u-group _f z. B. monoethanolamine or monopropanolamine, aminocarboxylic acids such as glycine, aminopropionic acids, aminocaproic acids or aminobenzoic acids »

The condensations used to produce the polyether alloys are preferred 18sungsmltt @ lfr @ i durohgefUhrt «After the The condensate melts in a dry and / or wet state marry. It has been shown in numerous tests that a Combined dry and NaS grinding with a favorable space-time yield leads to a suspension with the required particle spectrum.

Surface-active agents are often added with advantage in small proportions in order to improve the wetting of the condensate zii more favorable grinding results and suspensions with better Flow behavior, to come «The known wetting agents can be used for this purpose, for example fatty acid esters, ethoxylated and / or propoxylated compounds, alcohols, amine or alkali salts of carboxylic acids, stilfonic acids, etc.

It is essential that the polyesterimides in aqueous dispersion in Forai Ψύη Tellohen with particle diameters s 5 / um *

509817 / Q9fe7 / 7

- 7 - ο.ζ. 30 150

preferably 0.05 to 1.5 μm and _{contain 0.1 to 1O 5,} preferably 0.5 to 5 percent by weight of at least one esterification catalyst.

Suitable esterification catalysts are tetrabutyl titanate ₅ Manganaeetat, CadmLumacetat, antimony acetate, and iron acetylacetonate Kresyltitanat.

The esterification catalysts are preferably used in the polyesterimide melt incorporated.

The pH of the dispersions according to the invention is, if necessary, adjusted to a value between 5 and 9 with a neutralizing agent (amine or acid) »

The component (E) content of the polyesterimide dispersions according to the invention is between 20 and 50, preferably 25 and 45 Weight percent.

The polyesterimide dispersions according to the invention can additionally contain small amounts of 1 to about 10 percent by weight, based on polyesterimide, leveling agents, such as. B, butanediol or diethylene glycol, and a protective colloid, e.g. B. polyvinyl alcohol, and / or a dispersant, such as. B. partially saponified copolymers of acrylates and acrylonitrile are added. Likewise, up to 50 percent by weight, based on polyesterimide, pigments, such as. B. TiO ₂ , iron oxide and lead chromate, fillers such. B. dolomites and silicates, or dyes can be incorporated to achieve certain effects.

The polyesterimide dispersions according to the invention can be used directly for electrical insulation of metallic conductors, especially of Wires and rails are used, with the usual application methods and devices can be used.

It was surprising and unforeseeable that the invention Dispersions are stable and without the known stabilizers and surface-active auxiliaries when stored in the

509817/0967

- j * - ο.ζ. 30 150

Remain stable at rest and while moving. Compared to the known Polyesterimidlaeklösungen or -dispersions no special measures are therefore required to maintain a constant product quality, such as stirring, Pumping, filtering, centrifuging, regrinding or addition thickeners or thixotropic agents to prevent settling.

Gloss and surface smoothness of a finished stove-enamel finish, produced from an aqueous dispersion according to the present invention, cannot be distinguished from a coating of the same binder from solution.

The parts and percentages given in the examples are based on weight, unless stated otherwise.

example 1

a) 388 parts of dimethyl terephthalate, 11? Share ethylene glycol and 75 parts of glycerol are reacted with one another while increasing the temperature to 210 ° C. and removing methanol by distillation. Then at temperatures from 180 to 215 ° C 137 Parts of dimidicarboxylic acid from 2 moles of trimellitic anhydride and 1 mole of diaminodiphenylmethane was added. After utter Dissolution, 1.8 parts of cadmium acetate are added and 3 Hours at 215 ° C, finally under vacuum, further condensed. The product obtained is dissolved in 480 parts of hot cresol and mixed homogeneously with 9 parts of butyl titanate (Example 1 from DAS 1 445 263).

b) For comparison, a condensate is produced for the production of a lacquer resin suspension in exactly the same way as in a), with the difference that after the vacuum condensation has ended, it is ^{cooled to 170 °} C. under normal pressure, 9 parts at this temperature in the course of 10 to 30 minutes Butyl titanate is stirred in and the resin is discharged onto a cooled belt. The resin is comminuted and ground in aqueous suspension to a particle size below 4 μm. The suspension contains 35% by weight of binder powder. There are ■ the dispersion 1 ,, ^ ^ ew-.i Bu ^ apdiol added as a paint leveling agent.

- 9 - O.Z. 30 150

c) Production of wire enamels with the enamels a) and b): Enamel a) was with solvent naphtha / xylene 2; 1 diluted to a Pestkörpergehalt of 30%, lacquer b) was mixed with deionized water also at 30% dilute Both paints were in a horizontal Drahtlackierofen of 3 $ 10 m length of copper wire of 1 mm diameter continuously applied "oven temperature 470 ⁰ C; 'application method: Roll and felt wiperj β orders, · take-off speed 4 m / minutej total lacquer application 50 / um »

The examination of the paintwork showed;

Paint a)

Lacquer b)

Pencil hardness ■

Pencil hardness after 1
at 60 ° C in benzene

Pencil hardness after 1
at 6O ⁰ C in ethanol

Hour storage hour storage

Thermal shock test (coil around "the proper = · diameter of the wire after tempering 1 hour at 155 ° C)

4 H. 5 H. 3 H. 3 H. 3 H. 3 H. in order in order

Unpleasant odors from Laek a) and paint b) when painting: Paint a) leads to strong odor nuisance _e In paint shops, the solvent must be removed by thermal or catalytic afterburning _e Apart from the costs caused by this, complete removal of all traces of solvent is not possible ^ see above that the chimney exhaust gases cause strong odor nuisance even at a relatively great distance.

In a large-scale test with paint b), no odor nuisance was found. It was merely catching water vapor and minor odorless condensation products released,

Example 3

This example shows the influence of the take-off speed on the properties of the coating. While with a withdrawal speed pVon Ά m / Miimte_no differences in the

/ 10

- 3tf - OZ 30 I50

Paint could be seen occurred at 5 m / minute and even more blisters in paint a) at 6 m / minute, while paint b) showed no change in appearance. As well as Coating a) as well as b) showed a decrease in pencil hardness at higher withdrawal speeds:

with painting a) a drop to 3 H, with painting b) a drop to 4 H.

Example 4

A precondensate is prepared from 300 parts of dimethyl terephthalate, 64 parts of ethylene glycol and 63 parts of glycerol. At 125 ° C this precondensate 248 parts of the ß-Hydroxyäthylimids of trimellitic anhydride was added and then heated to 190 ⁰ C and slowly from then heated to 220 ⁰ C was reached until an acid number of less than 10 degrees. The condensate is first dissolved in 450 parts of cresol, mixed with 11 parts of butyl titanate and then brought to a solids content of 25 % with a mixture of equal parts of cresol and solvent naphtha (paint o), viscosity in the flow cup with the nozzle 4 ram = 111 seconds.

For comparison, a Laek powder suspension in water is made from the same condensate. For this purpose, after the end of the condensation, the temperature is lowered to 180 ° C., 11 parts of butyl titanate are stirred in and the condensate is discharged onto a cooling belt. It is initially ground to a particle size below 20 / um and then milled strength together with water to a 30 # suspension with particle sizes below 4 / AM. The pH of the suspension is adjusted to 7 0 with ethanolamine. 85 % of the particles have a diameter of 0.03 to 1.2 μm (paint d)).

With varnish 0) and varnish d), copper wire with a diameter of 1 mm is like in example I c) painted. The properties of the coating correspond to those in Example 1 c). Again is the paintwork from the aqueous suspension in pencil hardness one unit higher than from solution. The possible suction speed without Disturbance of the surface of the paint is higher with the aqueous paint suspension compared to the solution by a factor of 1.5 to 1.7.

509817/0967

Claims (3)

- 11 ■■ O.Z, 30 150 patent claims 1. Heat-curable coating agents for wire enamelling on the 'basis of aqueous polyesterimide dispersions, characterized in that they consist essentially of (A) 50 to 80 wt. # Water and (B) 20 to 50 wt.% Polyester-imide in the form of particles with
Particle diameters ^ 5 / um, wherein (B) 0.2 to 10 percent by weight of at least one esterification catalyst contains, and the pH of the dispersion is between 5 and 9. 2. Coating agent according to claim 1, characterized in that
(B) at least 80 wt.% Of particles having a Teilehen-. diameter between 0.05 and 1.5 / µm. 3. Coating agent according to claim 1 or 2, characterized in that it also contains small amounts of a leveling agent,
Contain protective colloids and / or dispersants. BASF Aktiengesellschaft 509817/0967