DE2251470A1 - FLEXIBLE POLYESTER COATING DIMENSIONS - Google Patents

Description

Patent Attorney H / D (499)

Dr. Michael Hann October 17th 1972

63 casting
Ludwigstrasse 67

PPG Industries, Inc., Pittsburgh, USA FLEXIBLE POLYESTER COATING COMPOUND

7ΨΨΙ ~~ ^ ~

Priority: October 22, W2 / USA Ser. No. 191,808

It is known to use lactones for the production of lactone polyesters, these polyesters as Plasticizers and as intermediates for the manufacture of elastomers. Foams and resins US Pat. No. 3,169,945 * In addition, the reaction of lactones with compounds is also possible with reactive hydrogen atoms, for example -OH, -NH- or -COOH groups, well known. Furthermore, it is also known, epsilon-caprolactone, dimethyl terephthalate and ethylene glycol in the presence of zinc borate to form copolyesters with a specified implement minimal molecular weight and use these polyesters as adhesives or coating compounds. In order to obtain useful masses, the molar ratio of the terephthaloyl units to the 6-0xycaproyl units is used in macromolecular chains in the range of

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30:70 to 80:20 kept and the molar ratio of terephthaloyle units to ethylenedioxy units in the molecular chains are kept essentially at 1: 1.

Polyesters have been used extensively for the manufacture of coating compositions. The polyesters used for this purpose have good flowability and good flow behavior immediately after application. Oil-free polyester has been used for covering coils with good ^{4 success.} Other areas of application for such coating compositions are the coating of aluminum, tin-plated iron, tin, steel, black boards and the like. These coating compounds have also been used in large quantities for coating metal furniture, tools and devices.

But there is a great need, especially for that Coating of coils, using oil-free polyester coating compounds that are flexible and yet remain tough and hard. To the Solution to this. Problem, i.e. to improve flexibility, a large number of proposals have been made. the However, previously known solutions for improving flexibility are associated with the occurrence of other undesirable properties. For example, polyether polyols are available for use Improvement in flexibility built in, but this makes the coating compositions so soft that the coating or film loses its protective effect '. Another approach has attempted a linear polyester by using it of oxalic acid or adipic acid, but an undesirable permanent softening

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. effect on. Funds for permanent flexibilization have already been added, but this results in masses that result in soft films and coatings that are particularly special
are sensitive to contamination.

It has now been found that by incorporating Epsilonr Caprolacton.in a polyester made from a polyol mixture, which contains at least one trivalent polyol and one diol, a product is obtained which can easily be formulated into coating compositions, these coating compositions hardening The result is coatings that are not only flexible, but also hard and dirt-resistant.

The coating compositions according to the invention are non-gelled, flexible polyester coating compositions which contain a reaction product of a polyol mixture, this mixture at least one trivalent polyol; an ester diol, at least one polybasic acid or its anhydride
and epsilon-caprolactone. The components mentioned above can be reacted with one another at the same time or in batches, but one can also use a pre-formed addition product of epsilon-caprolactone and the polyol and use this to replace at least part of the trivalent polyol. The reaction product of these reactions can then be used with
a suitable crosslinking agent and then 'cure these coating compositions to flexible, hard and dirt-resistant coatings.

For the production of the polyesters according to the invention, those commonly used for the production of polyester can be used Polyols are used. Such polyols

include, for example, the following compounds: ethylene glycol,

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Propylene glycol, butylene glycol, diethylene glycol, dipropylene glycol, Triethylene glycol, neopentyl glycol, trimethylene glycol, Polyethylene glycol, polypropylene glycol, 1,5-pentanediol, Trimethylolethane, trimethylolpropane, glycerine, 1,2,6-hexanetriol, Pentaerythritol, sorbitol, mannitol, methyl glycoside, 2,2-bis (hydroxylthoxyphenyl) propane, 2,2-bis (beta »hydroxypropoxyphenyl) propane and the same. If necessary, monohydric alcohols can also be used in conjunction with polyhydric alcohols Alcohols are used. For example, more flexible polyesters are obtained if a small amount of a monohydric alcohol is used is used to make some of the higher-valent alcohols too substitute. Monohydric alcohols in particular have about 3 to about 18 carbon atoms in their molecule into consideration. Suitable such alcohols include, for example, primary, secondary and tertiary Alcohols such as methanol, ethanol, propanol, isopropanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 3-pentanol, tert-amyl alcohol, 1 hexanol, 4-methyl-3-pentanol, 2-ethyl-l-butanol, 1-heptanol, 3-heptanol, 1-octanol, 2-ethyl-1-hexanol, 1-nonanol, 2,6-dimethyl-4-heptanol, 2,6,8-trimethyl-4-nonanol, 5-ethyl-2-nonanol, 7-ethyl-2-methyl-4-undecanol, 3,9-triethyl-6-decanol, lauryl alcohol; aromatic alcohols such as benzyl alcohol and Phenylmethylcarbinol and cycloaliphatic alcohols such as. Cyclohexanol and trimethylcyclohexanol.

. The diols listed below are generally suitable for the preparation of the polyesters: glycols of the formula HO (CH ₂ ) _n OH, where η is 2 to 10, glycols of the formula

HO ^ CH (CH ₃ ) CH ₃ O ^ _n H, where

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η is 1 to 40. As examples of such diols the following compounds may be mentioned: ethylene glycol, diethylene glycol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, N-methyl- and N-ethyl-diethanolaraine. Other suitable diols are 4,4-methylenebiscyclohexanol, 4,4'-Isopropylidenebiscyclohexanol and various sylenediols, hydroxymethylphenylethyl alcohols, Hydroxymethylphenylpropanols, phenylene diethanols, phenylene dipropanols and heterocyclic diols such as 1,4-piperazine diethanol and the like. Preferred diols are ester diols, such as 2, -Methyl-2-ethyl-1,3-propanediol, 2-ethyl-1,3-hexanediol and 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate and the same.

Trimethylolpropane is preferably used as the trivalent polyol; However, other trivalent polyols can also be used, such as trimethylolethane, 1,2,3-propanetriol, 1,2,4-butanetriol, 1,2,6-hexanetriol and the like.

As acid component, the polyesters according to the invention can be unsaturated acids, such as maleic acid, fumaric acid, itaconic acid, Citraconic acid, glutaconic acid, mesaconic acid and the like contain. Other polycarboxylic acids that can be used in addition to the "above" acids are saturated Polycarboxylic acids such as succinic acid, glutaric acid, sebacic acid and the like. Also some aromatic polycarboxylic acids and their derivatives are suitable, such as phthalic acid, isophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, Endomethylenetetrahydrophthalic acid and the like. Preferred acids are phthalic acid and isophthalic acid and terephthalic acid and the like. The one used here

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The term "acid" also includes the corresponding acid anhydrides one if they exist.

In some cases, a fatty acid can also be used in addition to the polycarboxylic acids. As fatty acids include, for example, saturated fat into account, such as capric acid, lauric acid, Myr is insäur e, palmitic acid, stearic acid, Licosan · ⁴ acid, behenic acid and the like. Unsaturated fatty acids can also be used, such as 9-octadecenoic acid, 9,12-octadecadienoic acid, 9,12,15-octadecatrienoic acid, 9,11,13-octadecatrienoic acid, 4-keto-9,11,13-octadecatrienoic acid,

German

12-hydroxy-9-octadecenoic acid, 13-docosenoic acid and the like.

The epsilon-caprolactone used for the production of the polyesters according to the invention is commercially available and its manufacturing methods are well known, cf. S. L. Friess, Journal of the American Chemical Society, 71, 2551 (1949) and Chemical Week, April 14 (1956) 92-94. Some of the physically important properties of epsilon-caprolactone are listed below:

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Empirical formula ^ 6 ^ 10 ^ 2

Structural formula. CH ₉ CH ₀ CH ₀ CH ₀ CH ₀ C = O

Z Z ZZ Zi

- 0-

Molecular weight. 114.07 specific weight

(20/20 ° C) 1.0776

Boiling point 146 ° C

Vapor pressure '(2O ⁰ C). <S>, 1 mm

Melting point -1> 3 C

Solubility in water (2O ⁰ C) OO weight%

Viscosity (20 ⁰ C) 6.6 centipoise

20th

Refractive index, n_ 1.4631

The polyester is produced using epsilon-caprolactone in a similar way to the other polyesters. The polymerization temperature is not essential to the invention and it can be, for example, at about 50 to about 240 ° C. The amount of the individual starting materials can be varied within wide limits. Individual components with reference to the total weight of the starting materials in the following amounts are preferred uses: ester diol about 27 to about 45%; 3-valued Polyol about 13 to about 25 percent; Epsilon-caprolactone about 9 to about 17% and polycarboxylic acid or its anhydride about 32 to about 54%.

If desired, the production of the polyester in The presence of an esterification catalyst. The usual esterification catalysts can be used Use catalysts such as dibutyltin oxide, tin

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II-chloride, tin-II-oxalate and the like.

The use of an esterification catalyst or a ring opening catalyst for epsilon-caprolactone is true not absolutely necessary, but often desirable because otherwise the condensation will only run slowly. In many In some cases, the catalyst is effective both for the esterification and for the opening of the ring. The polymerization or condensation of epsilon-caprolactone can in the present invention by a variety of basic, neutral and acidic transesterification catalysts. When using basic and neutral transesterification catalysts As a rule, reaction temperatures of higher than 150 C are required for the polymerization bring about. When using strongly acidic catalysts, temperatures below 150 ° C. are also sufficient.

Examples of effective transesterification catalysts are aluminum isopropoxide, tetraalkyl titanates, titanium chelates, Lead salts, lead oxides, zinc borate, antimony oxide, organic acid, inorganic acid such as sulfuric acid, hydrochloric acid and phosphoric acid, Lewis acids, such as boron trifluoride. The most effective transesterification catalysts are titanium compounds, such as tetraisopropyl titanate, tetrabutyl titanate, 2-ethylhexanediol-i, 3-titanate, hydroxytitanium stearate and Isopropoxytitanium stearate.

Catalysts specially designed for the opening of the ring of Epsilon-caprolactone are suitable include strong inorganic acids such as sulfuric acid, hydrochloric acid, phosphoric acid and boron trifluoride a.

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The amount of catalyst used is not essential to the invention and with amounts as low as 0.1% or less and with amounts as high as 0.5% or more, based on the solids weight of all starting materials, work. So much for the implementation When using catalyst, an amount of about 0.2% is preferred.

If a catalyst is used which is solid at room temperature, it is advantageous to use the starting materials to heat before the catalyst is added to give a more uniform distribution of the catalyst reach.

The polyester is usually manufactured in Presence of a solvent, the usual 'way used for the production of polyesters' Solvent used. Close such solvents e.g., aromatic or aliphatic hydrocarbons such as xylene, toluene, and the like.

To further explain the invention, the production of some polyesters and some coating compositions will now be described described. All details about parts and percentages are weight details, unless something else is expressly stated is specified.

Polyester A

In a reactor equipped with a thermometer, stirrer, distillation device with reflux cooling and water trap and with Means of maintaining an atmosphere of an inert

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Gas is equipped, 1075 parts of 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, 520 parts of triraethylolpropane, 393 parts of epsilon-caprolactone, 1292 parts of isophthalic acid, 3 parts of dibutyltin oxide and 90 parts of xylene are added. The reaction mixture is warmed to about 213 ° C. for a period of about 4 hours. This temperature is maintained until a Gardner-Holdt viscosity of XY is achieved. The viscosity is determined by withdrawing an aliquot of the reaction product and a solids content of 60% in a solution of 3 parts of a high boiling aromatic hydrocarbon (boiling range 188-210 ⁰ C) and one part diluted Äthylenglycolmonobutyläther. After the desired viscosity is reached, the reaction product with 1455 parts of a high boiling aromatic hydrocarbon (boiling range 188 - 21O ⁰ C) and 485 parts Äthylenglycolmonobutyläther, cooled and filtered in a known manner, for example with a conventional paper filter, a common Filter aid based on diatomaceous earth and at a pressure of about 3.50 to about 6.30 kg / cm. A total of 225 parts of water are removed during the reaction.

The reaction product obtained had the following features:

Acid number 4.65

Solids content (percent) 59.79
Weight / liter 1.04 kg / i-

(Weight / Gallon 8.73) Viscosity (Gardner-Holdt) XY Color (Gardner) 3-4

Hydroxyl number 111.0

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As has already been stated, one can use another

Embodiment of the invention an epsilon-caprolactone-polyol adduct prepare beforehand and then with a diol and a polybasic acid to form the polyester realize. Such adducts can be made by well known methods using those already mentioned Manufacture polyols. A trivalent polyol such as trimethylolpropane is preferably used. If higher polyols are used. are used, branched, higher molecular weight adducts are of course formed. It can e.g. Adducts with Molecular weights from as low as a few hundred to over ten thousand manufactured without difficulty will. The proportions of the starting materials for the production of the adducts are not essential to the invention and can be varied depending on the properties desired. However, if an adduct of trimethylol- ' propane and epsilon-caprolactone is used, it is advantageous to have a molar ratio between trimethylolpropane and epsilon-caprolactone from about 1.0 to about 3.56. To speed up implementation you can the catalysts already mentioned are used in the preparation of the adducts.

Adducts of the type described are also available commercially. For example, an adduct of trimethylolpropane and 'Epsilon-Caprolacton in Handel under deaf "designation "NIAX Polyol PCP-0300 .. This adduct is used to make the following polyester.

BATH

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Polyester B

The following starting materials are placed in a reaction vessel:

Parts by weight

2,2-dimethyl-3-hydroxypropyl-2,2-

Dimethyl 3-hydroxypropionate 1150

Trimethylol propane 458

Epsilon-caprolactone adduct

NIAX polyol PCP-0300 279

Isophthalic acid 1383

Dibutyl tin oxide 3

Xylene 90

The reaction vessel is heated to about 215 to 220 ^° C. and this temperature is maintained for about 2 hours until a Gardner-Holdt viscosity of YZ is reached. The viscosity is checked by taking an aliquot of the reaction product and diluting it to 60% solids in a solution of 3 parts Solvesso 150 and one part ethylene glycol monobutyl ether. After the desired viscosity has been reached, the reaction product is cooled and treated with 555 parts of a high-boiling aromatic hydrocarbon (boiling limits 188 - 210 ° c) and 485 parts of ethylene glycol mono-

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butyl ether diluted. The product obtained has a Solids content of 60% and an acid number of 10.

Polyester C

This reaction product is similar to the reaction product of B, except that the reaction product G Trimethylolpropane contains 12.5% less than the adduct of trimethylolpropane and epsilon-caprolactone . (NIAX Polyol PCP-0300) was replaced. The product C had a solids content of 60% after dilution and an acid number of about 10..

The reaction products according to the invention, the preparation of which has been explained above, can be used for formulation are used by coating compounds that result in coatings that are characterized by improved flexibility, Distinguish hardness and dirt resistance.

These reaction products are preferably used together with a crosslinking agent in the coating compositions. Condensation products of formaldehyde with melamine, urea or benzoguanamine, such as tetramethoxymethylbenzoguanamine, hexakis (methoxymethyl) melamine, trimethoxymethylmelamine, for example, can be used as crosslinking agents; Triethoxymelamine and the like * In addition, various modifiers containing amino groups can also be incorporated, such as Ν, Ν'-dimethylurea, benzyl urea, formaguanamine, acetoguanamine and the like.

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Other materials that are blended, mixed or, in some cases, incorporated with the polyesters according to the invention or can be crosslinked are nitrocellulose, phenolic resins, latexes of chlorinated synthetic Rubbers, vinyl resins, chlorinated paraffins, epoxy resins, polyisocyanates, silicones, reactive monomers, such as e.g. styrene, cellulose acetobutyrate, phenolic resin lacquers, polyamide plastics, natural resins such as shellac, Rosin and the like, monobasic aromatic acids and the like. These materials can additionally to the already mentioned crosslinking agents are used.

Die'Reaktionsprodukte according to this invention can with a crosslinking agent and / or other reactive functional materials mixed or blended and then hardened. These compositions can work well within a be cured in a wide temperature range, e.g. at temperatures as low as 177 ° C for 30 minutes or temperatures as high as 260 C for about 65 seconds. Some preparations can be used at much lower Cured temperatures or westerly higher temperatures depending on the properties desired will.

The coating compositions according to the invention can be easily pigment. The pigments usually close pigments used, e.g. iron oxide, lead oxide, carbon black, titanium dioxide, talc, barium sulfate, cadmium red, chrome yellow, Phthalocyanine blue, toluidine red and the like.

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The coating compositions can also contain other commonly used additives, e.g. B; Flow agents, plasticizers, bactericides, fungicides and the like.

The coating compositions explained in the examples below result in coatings of satisfactory hardness, which are characterized by higher flexibility, than the well-known polyesters that are not epsilon-caprolactone contain.

Example 1 .

Weight .-Parts 39 6th 1, 33 44, 3

Pigment paste (details later) Benzoguanamine (100% solids) * Polyester A

Epoxy resin (64.6% solids in toluene from a reaction product of 78.5 parts Epon 829 from Shell and 21.5 parts of bisphenol A) 5.1

para-toluenesulfonic acid (20% solution

in water) 3.25

Ethylene glycol monobutyl ether 15.0

Silicone flow aid 10 drops

* methylated, ethylated tetramethylolbenzoguanamine-formaldehyde resin

ORJGIMALiNSPECTED

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Pigment paste

Titanium dioxide

Benzoguanamine (100% solids) as above

Ethylene glycol monobutyl ether

The paste is ground in a ball mill until a Hegman fineness of about 6.5 is reached.

With the preparation of this example a /

Weight Parts 403 » 2 80, 4th 116 3

Coated to such a thickness that after baking for 65 seconds at 260 ° C a dry one The result is a film with a thickness of 25.4 microns. This coating is compared to an upper coating from a common polyester. For the comparison test a similarly pigmented and formulated preparation is used, a conventional polyester resin (without epsilon-caprolactone) is used, which consists of 123.6 parts of 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, 600 parts of trimethylolpropane, 148.7 parts of isophthalic acid, 8.0 parts of xylene, 144.0 parts of a high-boiling aromatic hydrocarbon (Boiling limits 188-210 ° C) and 68.1 parts of dibutyltin oxide was produced. When examining the Reverse impact at 50 and 60 inch-pounds gave the following results:

INSPECTED

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TABLE I. 50 inch * *
■ pounds βθ inch-pounds 0
fails very smaller
fracture
3 example 1
Comparative experiment

In Table I, a numerical scale from 0 to 10 is used to indicate impact strength, with 0 indicating no cracking of the coating and 10 indicating total failure of the coating. From the results is ^; It is easy to see that the coating made from the composition of Example 1 has the higher flexibility.

The coating composition according to Example 1 also shows a higher

Flexibility and higher impression strain resistance when ^{subjected to an "inside vise bend test 11} (inside vise bend) or an" inside T bend test ". The last-mentioned test is in contrast to the normal Tr-bending test, in which the coating is applied to the outer surface of the substrate and the coating remains on the outside, whereas in the "inside T-bending test" the substrate is bent around the coating. J. Duke and A. Gage, Behavior of Polymeric Coatings on Steel During Deep-Drawing, Journal of Oil and Color Chemistry Association (1970) 53, 774-791.

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Generally, the plate or other substrate is used bent over a given number of plate or substrate thicknesses, the designation 1-T means that the plate has been bent over a plate thickness. The names 2-T, 3-T etc. have a corresponding meaning. A plate with a coating of the coating composition from Example 1 is bent over 4 metal thicknesses (4-T) and compressed in vice jaws without cracking occurred along the outside of the bend angle. When the coated plate is subjected to a 2-T bend it shows an extraordinarily good one Compressive strength, as the film on the inside of the 2-T bend angle does not and does not wrinkle Forms cracks.

The coatings made from the composition of Example 1 also have good hardness (2H pencil hardness) and good Dirt resistance. The dirt resistance is tested by the usual compounds for a such tests are used, e.g. mustard, merthiolate, Lipstick, phosphoric acid (10% solution), sodium hydroxide (5% solution) and the like. the Soiling compounds are usually left in contact with the coatings overnight.

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The polyesters according to the invention, the epsilon-caprolactone contain, are particularly characterized by the fact that they are at the same time more flexible also have a satisfactory hardness and a satisfactory dirt resistance *

Example 2

■ Parts by weight Pigment paste 118.0 Melamine formaldehyde resin * 15.9 Q
Polyester B 116.5 Epoxy resin (as in example 1) 15.4 Ethylene glycol monobutyl ether 15.0 Silicone flow aid 0.3 Pigment paste

Titanium dioxide 67.2

Melamine formaldehyde resin * 13.4

Toluene 19.4

* Highly methylated hexmethylolmelamine product

The pigment paste is comminuted in a manner similar to that of the pigment paste of Example 1.

ORiGiNAL INSPECTED

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An aluminum coil as in Example 1 is coated with the coating compound from Example 2 and cured. The coating is compared with a coating made of a conventional polyester resin, which is similar Made in a manner similar to the polyester of Example 2.

The values for the measured physical properties are given in Table II below.

TABLE II Gloss Hardness Reverse Impact Dirt

countability constant CCfii-kf) - ability

OkJ UJ fäJ U.0

Example 2 95 3Hl 2 4 6 good

Comparative experiment 96 3 H 2 3 5 7 good

The information on impact strength is based on the in Example 1 explained scale. It can be seen again that the polyester modified with epsilon-caprolactone has improved flexibility compared to the usual polyester without epsilon-caprolactone, without that thereby an impairment of the hardness and the Dirt resistance occurs.

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Comparing coatings made from the comparative composition and the composition of Example 2 to the well-known "Erickson Subject to impact test "(Erickson Bump Test), the superior flexibility of the coating composition is also demonstrated according to the invention, since the coating withstood an impact with a depth of 1.75 cm, before cracking, whereas the comparative coating cracked on impact from a depth of 1.65 cm.

Example 3

This example is similar to Example 2, except that Example 2 is a melamine-formaldehyde resin is used as a crosslinking agent. The coating compound of this example also contains 0.5 parts of a homopolymer of 2-ethylhexyl acrylate. The comparative experiment carried out in Example 2 used a polyester which was free of epsilon-caprolactone and the rest Components were similar / to those of Example 2, except that 6.7 parts of a polyester; Epoxy terminated plasticizer is used became.

If one considers coatings of aluminum ^ and steel- bobbins and for 65 seconds at 260 ° C, one obtains coatings which in their properties correspond to those of Example 1 and Example 2

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correspond. The polyester resin, which is modified by incorporating epsilon-caprolactone, stands out also in this case by an increased impact strength and flexural strength and at the same time also has the desired hardness and dirt resistance.

The polyester reaction products described above can be modified in many ways. So you can z. B. perform the condensation in the absence of a catalyst or tin-11 chloride use as a catalyst. As a diol you can, for. B. also use 2-methyl-2-ethyl-1,3-propanediol. Instead of Isophthalic acid can be used with other acids, such as phthalic acid, use or use in addition to isophthalic acid. The coating composition can contain other crosslinking agents contain, such as hexamethoxymethylmelamine, N, N'-dimethoxymethylurea, Formaguanamine-formaldehyde resins and the like. The coating compositions can also contain pigments such as phthalocyanine blue, carbon black, talc and the like, be pigmented.

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Claims (15)

Patent claims: 1. Thermosetting, non-gelled flexible polyester coating compound, characterized in that they (a) a polyester made by reacting (1) at least one trivalent polyol, (2) a diol, (3) at least one tribasic acid or its anhydride and (4) Epsilon-Caprolactone or a Polycapro-. lactone polyol from trimethylolpropane and Epsilon-Caprolactone with a Hol ratio from trimethylolpropane to epsilon-caprolactone from about 1.0 to 3.56; and (b) contains a crosslinking agent. 2. coating composition according to claim 1, characterized in that that the trivalent polyol is trimethylol propane. 3. Coating mass according to one of the. Claims 1 or 2, characterized in that the diol is an ester diol is. 4. Coating composition according to claim 3, characterized in that that the ester diol is 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate is. 309817- / 1156 5. Coating composition according to one of claims 1 to 4, characterized in that the diol has one of the formulas HO (CH ₇ ) OH, where η is an integer from 2 to 10, HO (CH ₂ CH ₂ O) H, where η is an integer from 1 to 40 and corresponds to Ho / cH (CH ₃ ) CH ₂ O / _n H, where η is an integer from 1 to 40. 6. Coating composition according to one of claims 1 to 5, characterized in that the polybasic acid is isophthalic acid. 7. Coating composition according to one of claims 1 to 6, characterized in that the crosslinking agent is a Aldehyde condensation product of melamine, urea I ¹ and benzoguanamine 1st. 8. coating composition according to claim I _1, characterized in that it (a) a polyester (1) trimethylol propane, (2) 2, ^ - dimethyl-S-hydroxypropyl ^, 2-dimethyl-3-hydroxypropionate, (3) isophthalic acid and (4) epsilon caprolactone and (b) a crosslinking agent composed of a methylated, contains ethereal tetramethylol benzoguanamine formaldehyde resin. 3 0 9 8 17/1156 -25-225H70 9. A method for coating a substrate with a Polyester coating composition, characterized in that a coating composition is applied to the substrate and then cures, wherein the coating composition; {a) a polyester made by reacting (1) at least one trivalent polyol, (2) a diol, (3) at least one polybasic acid or its anhydride and (4) Epsilon-caprolactone or a polycaprolactone polyol made from trimethylolpropane and Epsilon-caprolactone with a molar ratio from trimethylolpropane to epsilon-caprolactone from about 1.0 to 3.56 and (b) contains a crosslinking agent. 10. The method according to claim 9, characterized in that that the trivalent polyol is trimethylol propane. 11. The method according to any one of claims 8 and 9, characterized characterized in that the diol is an ester diol. 12. The method according to claim 11, characterized in that that - <fas diol 2,2-dimethyl-3-hydroxylpropyl-2,2-dimethyl * 3-hydroxypropionate is. Ί 0 9 y I 7 / IISR 225 UVO 13. The method according to any one of claims 9 to 12, characterized in that the diol of one of the formulas HO (CHL) OH, where η is an integer from 2 to 10, HO (CH ^ CH ₉ O) H, where η is a is an integer from 1 to 40 and corresponds to HO / CH (CH JCH ₉ o / H, where η is an integer from 1 to 40, 14. The method according to any one of claims 9 to 13, characterized in that the polybasic acid Isophthalic acid. 15. The method according to claim 9, characterized in that the coating mass, (a) a thermosetting, ungelled flexible polyester made by reacting (1) trimethylol propane, (2) 2, -2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate, * · (3) isophthalic acid and (4) epsilon caprolactone and (b) a crosslinking agent composed of a methylated, ethylated tetramethylol benzoguanamine formaldehyde resin contains.