EP1799733A1

EP1799733A1 - Acid groups-containing polyurethane resins

Info

Publication number: EP1799733A1
Application number: EP05786751A
Authority: EP
Inventors: Anton Arzt; Julius Burkl; Gudrun Garber; Gerlinde Petritsch; Markus Schafheutle; Achim VÖLKER; Jörg Wango
Original assignee: Cytec Surface Specialties Austria GmbH
Current assignee: Allnex Austria GmbH
Priority date: 2004-10-07
Filing date: 2005-09-27
Publication date: 2007-06-27
Also published as: EP1645581A1; JP2008516021A; WO2006040003A1; US20080249279A1

Abstract

The invention relates to acid groups-containing polyurethane resins comprising partially unsaturated oil A derived components, of olefinically unsaturated aliphatic acids B or the anhydrides B' thereof, of compounds C comprising functional groups reactive with the acid groups or acid anhydride groups selected from epoxide, hydroxyl, mercaptan and amino groups which react, when brought into contact with the compounds B or B', with an ester, thioester or an acid amide group formation, wherein the compound C is selected from compounds C'' additionally containing sulphonic or carboxylic acid groups activated by electron-attracting substituents and compounds C' additionally containing at least one hydroxyl group which remains intact during the reaction with compounds B and B', at least 25 mass % of compounds C containing the compounds C'' and multifunctional isocyanates D. A method for producing said products, the use thereof in the form of catalysts for curing hydroxyl groups-containing binders with aminoplast resins and stovable varnishes containing said catalysts are also disclosed.

Description

Polyurethane resins with acid groups

The invention relates to water-dilutable polyurethane resins having acid groups, a process for their preparation and their use as catalysts for the curing of binders containing hydroxyl groups with melamine-formaldehyde resins.

The curing of resins containing hydroxyl groups as functional groups can be carried out at room temperature with polyfunctional compounds such as isocyanates, the isocyanate hardener being added only immediately before application or even during application (two-component binder). It is also possible to use hardeners which become active only at elevated temperature (one-component binder), in which case the mixing of resin and hardener can take place before the application and the ready-formulated binders have sufficient storage stability. To accelerate the curing reaction at elevated temperature usually catalysts are added. The addition of catalysts is always required when at least partially etherified aminoplast resins, ie reaction products of formaldehyde with Amiαoplastbüdnern as melamine, guanamines, ureas or mixtures thereof are used as a curing agent with lower aliphatic linear and branched alcohols having one to four carbon atoms. The transesterification reaction occurring during the curing is usually catalysed by acid. The catalysts used are preferably organic acids such as para-toluenesulfonic acid or derivatives thereof. However, such low molecular weight compounds can be extracted from the cured paint film, they are also subject to low molecular compounds as the Chemicals Act and the Reststoffverordαung.

It is therefore an object to provide catalysts which, because of their macromolecular

Character can not be extracted from the cured paint film, and have at least as good effectiveness as the known catalysts. Furthermore, they should not adversely affect the mechanical and chemical properties of the cured paint film and not lead to discoloration or gloss drop of the paint film.

This object is achieved by starting materials derived from vegetable or animal oils for the synthesis of polyurethanes are used, these on average each have at least one Säufegruppe in the molecule, which has catalytic activity for the saturation of aminoplast resins.

The invention therefore relates to water-dilutable polyurethane resins ABCD having acid groups, wherein the polyurethane resins contain components derived from oils A, which are at least partially unsaturated, of olefinically unsaturated aliphatic acids B or their anhydrides B ', of compounds C with functional groups reactive toward acid groups or acid anhydride groups selected from epoxide groups, hydroxyl groups, mercaptan groups and amino groups, which react with the compounds B or B 'to form an ester group, a thioester group or a

Acid amide react, wherein the compounds C are selected from compounds C "which additionally contain sulfonic acid groups or by electron-attracting substituents activated carboxylic acid groups, and compounds C, which additionally contain at least one hydroxyl group which is obtained in the reaction with the compounds B or B ' and wherein at least a mass fraction of 25% of the compounds C from

Compounds C ", and multi-functional isocyanates D.

Another object of the invention is a process for the preparation of water-dilutable, acid group-containing polyurethane resins ABCD comprising the steps of a) grafting an oil A with an olefinically unsaturated aliphatic acid B or the anhydride B 'of such an acid, b) polymer-analogous reaction of the adduct AB from step a) with a compound C having acid groups or acid anhydride reactive functional groups selected from epoxide groups, hydroxyl groups, mercaptan groups and amino groups which react on reacting with the compounds B or B 'to form an ester group, a thioester group or an acid amide group the

Compounds C are selected from compounds C ", which additionally contain sulfonic acid groups or by electron-attracting substituents activated carboxylic acid groups, and compounds C, which additionally contain at least one hydroxyl group which remains in the reaction with the compounds B or B ', wherein at least a mass fraction of 25% of the compounds C consists of compounds C ", and wherein the use of the

Compounds C is then preferred if the graft product AB itself is free of hydroxyl groups or in the reaction of the acid groups or acid anhydride groups in the Graft product AB no hydroxyl groups have arisen, and c) addition of the products ABC to the tert-functional isocyanates D with urethane formation.

Further objects of the invention are the use of the water-dilutable polyurethane resins ABCD as a catalyst in the curing of hydroxyl-containing

Binders with aminoplast resins, and stoving lacquers containing hydroxyl groups have binders, aminoplast resins and the water-dilutable polyurethane resins ABCD.

The acidity of the acid group is measured by its pKa value; if the pKa value is lower than that of acetic acid, its acidity is greater than that of acetic acid.

Suitable oils A are all drying and semi-drying oils having at least one olefinic double bond per molecule, in particular oils having an iodine value of 100 cg / g to 200 cg / g, for example, soybean oil, linseed oil, rapeseed oil, sunflower oil, tall oil, cottonseed oil, safflower oil, perilla oil and poppy seed oil. Also suitable are animal oils such as herring oil, menhaden oil or sardine oil. Particularly preferred are linseed oil, perilla oil, wood oil and tall oil.

Suitable acids B are in particular maleic acid, its anhydride, acrylic and methacrylic acid, vinylacetic acid, crotonic acid, itaconic, citraconic and mesaconic acid, and also tetrahydrophthalic acid and its anhydride.

Suitable compounds C contain functional groups reactive toward acid groups or acid anhydride groups and selected from epoxide groups, hydroxyl groups, mercaptan groups and amino groups which react with compounds B or B 'to form an ester group, a thioester group or an acid amide group, the compounds C being selected are from compounds C "which additionally contain sulfonic acid groups or by electron-attracting substituents activated carboxylic acid groups, and compounds C, which additionally contain at least one hydroxyl group which is obtained in the reaction with the compounds B or B ', and wherein at least a mass fraction of 25% the compounds C consists of compounds C ".

Therefore, those compounds Cl are suitable which react with cyclic acid anhydrides with ring opening or with renewed formation of the cyclic structure, such as, for example Hydoxy (alkylene) amines having at least one primary amino group and at least one hydroxyl group, compounds C2 which react with acid anhydrides with addition and formation of a hydroxyl group, such as epoxy compounds, and compounds C3 which react with acids under addition or esterification and at least one not among the Conditions of the reaction under esterification with acid-reactive hydroxyl group, for example, a secondary or tertiary hydroxyl group. In addition, compounds of these classes Cl, C2 and C3 contain either at least one sulfonic acid group or electron attractive substituent activated carboxylic acid group and then form the class C "or additionally at least one hydroxyl group which is retained in the reaction with the compounds B or B ' then in class C. At least one

A mass fraction of 25%, preferably at least 30%, and especially at least 40% of the compounds C are those compounds C "which contain at least one acid group which causes the compound C to be a stronger acid than acetic acid, such as electron-withdrawing substituent activated carboxylic acid groups or particularly preferably sulphonic acid groups Suitable compounds C are, for example, ethanolamine, 2- and 3-

Propanolamine and N, N-bis-2-hydroxyethyl-diaminoethane. A suitable compound C "is in particular taurine.

Suitable polyfunctional isocyanates D are aliphatic and aromatic isocyanates having at least two isocyanate groups per molecule, in particular diisocyanates such as aliphatic linear, branched and cyclic isocyanates such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 2,2, 4, - and 2,4,4-trimethylhexane diisocyanate, dodecamethylene diisocyanate, 1, 4-

Diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI) and bis (4-isocyanatocyclohexyl) methyl (HMDI), and aromatic isocyanates such as 2,4- and 4-isocyanatocyclohexyl) -methyl (HMDI) 2,6-Toluylendüsocyanat or a mixture thereof, bis (4-isocyanatophenyl) methane, tetramethylxylylene diisocyanate and the isomeric 1,5-, 1,8- and 2,3-Naphthalindiiso- cyanate.

The acidic water-dilutable polyurethane resins obtainable according to the invention can be prepared inter alia in mixtures of water-dilutable binders and in particular as

Catalysts in the curing of hydroxyl-containing binders with

Use aminoplast resins. It is preferred that the quotient of the mass of water-dilutable polyurethane resin and the mass of Aminoplastharzes 0.5% to 10%.

The polyurethane resins preferably have a mass fraction of acid groups of from 0.5 cg / g to 5 cg / g, more preferably from 1.0 cg / g to 4.0 cg / g, and especially from 1.5 cg / g to

3 cg / g. The mass fraction of acid groups is calculated by dividing the mass of the acid groups (-SO ₃ H for sulfonic acids, -COOH for carboxylic acid groups, including the ionized acid groups in the protonated form in the calculation) in the resin by the mass of the resin solid. The information is given in "cg / g" or "%".

The invention is illustrated by the following examples. In the examples which follow, just as in the preceding text, all statements with the unit "%" denote mass fractions (quotient of the mass of the relevant substance and the mass of the mixture), unless stated otherwise. Concentration data in "%" are mass fractions of the solute in the solution (mass of the solute divided by the mass of the solution).

Examples

Example 1: Preparation of an adduct of linseed oil and maleic anhydride

880 g of linseed oil was mixed with 220 g of maleic anhydride (MSA). This mixture was slowly heated to 210 ^° C. with stirring and nitrogen atmosphere. At this temperature, the batch was kept until no more free MSA was detectable by titration of the aqueous extract with methyl orange as an indicator. It was then cooled to room temperature.

Example 2: Addition of taurine to the linseed oil-maleic anhydride adduct

9.8 g of taurine were dissolved in a mixture of 8.9 g of ethanolamine and 10 g of deionized water in the heat (about 80 ⁰ C). After complete dissolution, this solution was mixed with 30.4 g

Triethylamine (TEA) added. To this biphasic mixture was at 80 ⁰ C slowly rising temperature, wherein the boiling triethylamine was condensed and the Reaktions¬ mixture was fed back, 110 g of the product from Example 1 over 90 minutes added. After completion of the addition was heated to a maximum of 180 ⁰ C and distilled off the TEA water azeotrope, wherein the TEA was recycled. After 140 g of water was removed from the reaction mixture, the TEA was removed by distillation under reduced pressure. There was obtained a viscous resin having an acid value of 37.4 mg / g and an amine value of less than 0.4 mg / g, which was clearly soluble in water. A solution from

10 g of the resin in 100 g of the solution had a pH of 3.9.

Example 3: Preparation of an aqueous dispersion of an acidic polyurethane resin

30 g of the resin from Example 2 and 10 g of castor oil were mixed with ό g of N-methylpyrrolidone and heated to about 40 ⁰ C. To this solution was added 6 g of tolylene diisocyanate. It was heated to 70 ⁰ C to 72 ° C by utilizing the Exothermrnie. At this temperature was held until an isocyanate concentration of 1.6% to 1.65% was reached. Then, 2.3 g of diethanolamine was added and stirred. A warming up to 82 ° C was observed. After renewed cooling to 70 ⁰ C, the resin was diluted with 87.8 g of deionized water. This gave a very finely divided dispersion with a non-volatile content of 34% and a pH, measured on a solution of 10 g of the resin in 100 g of the solution of 7.2.

Example 4: Aqueous dispersion of a high molecular weight chain-extended polyurethane resin

30 g of the resin of Example 2 and 30 g of castor oil were mixed in 11 g of N-Methylpyrrok ^'don and heated to 40 ° C. To this solution was first added 4 g of tolylene diisocyanate and immediately thereafter 8.4 g of isophorone diisocyanate. Using the Exothermrnie the mixture was heated to 70 ° C to 72 ° C and held at this temperature until the

Isocyanate concentration was between 1.8% and 1.9%. Upon reaching this concentration the resin with 109.7 g of heated (70 ⁰ C) and deionized water was dispersed. Immediately thereafter was chain-extended with a solution of 2.6 g of isophorone diamine in 12.6 g of deionized water. After a stirring time of 120 minutes, a finely divided dispersion with a non-volatile content of 36%, a viscosity (23 ⁰ C, 25 s ^"1 ) of

87 mPa 's and a pH of 7.6, measured on a solution of 10 g of the resin in 100 g of the solution. The mass fraction of acid groups (sulfonic acid groups) was about 2.0 cg / g. Example 5: Paint Test

Kkdack:

Made of 75.71 g of ®Macrynal VSM 2872/70 BAC (hydroxyl-containing acrylic resin), 42.90 g of ®Maprenal VMF 3924 / 70B (modified with methanol and n-butanol highly reactive

Melamine resin dissolved in n-butanol; both Surface Specialties Germany GmbH & Co. KG), 28.50 g

®Setalux 91756 (acrylic resin, Akzo Nobel Resins NV, hydroxyl number 90 mg / g), and the

Stabilizers 2.50 g of ®Tinuvin 384 and 1.20 g of ®Tiαuvin 123 (Ciba Specialty Chemicals), 45.00 g

Methoxypropylacetat, and 0.20 g ®Byk 310 (substrate wetting additive, Byk Chemie GmbH) was formulated a clearcoat having a spray viscosity corresponding to a flow time of 27 s, measured in a DIN 4 cup at 23 ⁰ C (DIN 53 211).

Comparative catalysts for the crosslinking reaction:

VKl: Para-Toluolsulfonsäute ('TTSA', Affied Signal Riedel de Haen), solved to a

50% solution in iso-butanol.

VK2: amine-blocked dodecylbenzenesulfonic acid (®Nacure 5225, King Industries)

The mass fraction w _{κ of} the catalyst is based on the mass of the solid in the

Aminoplast Maprenal VMF 3924. The catalyst (vkl, _κ w - 1% and VK2, _κ w = 0.8%, and the dispersion of the invention according to Example 4, w _κ ^~ 4%) is added to the fully formulated clear lacquer.

Preparation of the test sheets

Degreased gradient sheets of rolled steel (DIN 1624, 400 mm X 100 mm, thickness 0.8 mm) were sprayed with the solvent-containing primer described below (with an air pressure of 4 bar = 0.4 MPa), the coated sheets were during

Baked at 140 ⁰ C for 25 minutes. The precursor was formulated from 34.90 g © Vialkyd AN 951 / 70SNA (polyester resin, Surface Specialties Germany GmbH & Co. KG), 16.30 g rutile-type titanium dioxide pigment (Kronos titanium), 16.30 g carbon black (®Printex 300, DegussaHüls AG), 16.30 g of ®Blanc fixe micro (Sachtleben), 0.25 g © Aerosil 380 (finely divided silica, DegussaHüls AG), 2.00 g of 2-ethylhexanol, 6.50 g of methoxypropyl acetate and 6.10 g of ®Solvesso 150 (aromatic mixture with a medium

Boiling point of 150 ⁰ C, Exxon Chemicals) which were ground together in a bead mill at 50 ° C and 7000 min ^"1 for thirty minutes. Then, 0.20 g © Additol® XL (Surface Specialties Germany GmbH & Co. KG, leveling agents ), 14.80 g © Maprenal MF 590 / 55iBX (melamine crosslinking resin, Surface Specialties Germany GmbH & Co. KG), and 2.30 g of isobutanol were added, the mixture was at 2000 min ' ¹ more 20 minutes at 25 ° C to

30 ° C stirred. The viscosity was then adjusted by adding additional solvent for 27 to 30 seconds flow time from a 4 mm cup (DIN 53211, 23 ⁰ C) for spraying.

The thickness of the baked paint film was 40 μm to 50 μm.

On this primer / filler layer, a primer of an aqueous black paint ("Emerald Black", DuPont Performance Coatings GmbH & Co. KG) was sprayed at a pressure of 0.4 MPa to 0.5 MPa (4 to 5 bar); This gave a dry film thickness of 13 .mu.m to 17 .mu.m after drying for five minutes at room temperature and five minutes at 80.degree.

Thereafter, the clearcoat according to the above formulation was sprayed at 0.4 MPa (4 bar) air pressure and baked at 140 ⁰ C for 20 minutes to a dry film thickness of 35 .mu.m to 45 .mu.m.

On these sheets was the appearance ("Wave Scan", long-wave and short-wave component), the

Gloss, hardness, elasticity and acid and solvent resistance.

To determine the scratch resistance (Amtec-Kistler test) and the sensitivity to burn over, galvanically tin-coated sheets (180 mm × 105 mm, thickness 0.24 mm) were coated and baked in the same manner with the primer; for the test on overburning 60 minutes at 140 ⁰ C was baked on closing further. After the sheets had been cooled to room temperature, the basecoat and the clearcoat were applied, and the coating was baked at 140 ° C. for 20 minutes. Test sizes and test equipment:

1. Surface: A device "wave scan plus laboratoty" BYK-Gardner in D-82534 Geretsried

2. Gloss: Gloss meter Micro Tri-Gloss Fa Byk-Gardner

3. Adhesion: crosscut with 1 mm cutting distance, according to EN ISO 2409

Method, on the cut surface strips of ®TESA 4651 adhesive tape from Beiersdorf, Hamburg, were glued on and peeled off, assessment 0: best value, 5 worst adhesion

4. Acid test with aqueous sulfuric acid solution (mass fraction of H ₂ SO ₄ in the solution 10%)

The coated gradient sheets were placed on a gradient oven preheated to 60 ° C (BYK-Gardner Furnace 2615), and with a Eppendorf Multipipette (4780), a 50 μl drop of this acid was applied to the heated sheet for 30 minutes each minute applied, then the plate is washed off with deionized water. The evaluation is made after 24 hours rest at room temperature. The time required for the first damage to the clearcoat film (4.1) to the complete destruction of the clearcoat film (4.2) until the first damage to the clearcoat film (4.1)

Basecoat (4.3) and until the complete destruction of the basecoat and clearcoat (4.4) was noted as values.

5. Chemical resistance according to the DaimlerChrysler test method PBODC 371 A:

A gradient type 2615 from BYK-Gardner was heated to 30 ⁰ C to 80 ° C, to a painted metal test panel solutions were the

Chemicals according to Table 1 applied, then the sheet was placed on the Gradientenheiztisch for 30 minutes. Table 1 Test chemicals and test conditions

Temperature difference: 1 K per heating element.

To remove the tree resin after exposure, the coated sheet was after

Cool to 25 ⁰ C with benzine cleaned; all other chemicals were through

Rinse with cold water (15 ⁰ C) away.

After 24 hours rest of the panels was evaluated by determining the lowest temperature at which initial damage to the clearcoat by the chemical of interest was seen

* 1 sulfuric acid, p. A., mass fraction of acid in the solution 1%

2 Pancreatin (Merck GmbH, Darmstadt, Art. 7130) triturated in a porcelain mortar with the same mass of deionized water

3 Tree Resin (DuPont Performance Coatings GmbH & Co. KG, Wuppertal) 4 deionized water

6. Elasticity: is tested with an "Erichsen Cambering Machine 202"; Specification of the impression depth at which the paint does not break off

7. Scratch resistance: determined with an Amtec-Kistler car wash according to DIN 55668. The tinned sheets are used for 10 washing cycles. Thereafter, the sheets are rinsed and the gloss according to test 2. is measured directly thereafter and after annealing at 60 ⁰ C for 2 hours (so-called "refiow" condition). Re2eptur of the clearcoat:

75.71 kg of a hydroxy-functional acrylate resin (®Viacryl VSC 2872, Surface Specialties Germany GmbH & Co. KG, hydroxyl number 145 mg / g, solids content 70%, dissolved in butyl acetate) and 28.5 kg of a hydroxyfanktionellen acrylate resin (®Setalux 91756 Akzo Nobel Resins NV, Hydroxylzalil 90 mg / g) were mixed with light stabilizer, 35 kg of methoxypropyl acetate as further solvent, and 42.9 kg of a melamine-formaldehyde resin etherified with methanol and butanol (®Maprenal VMF 3924, solids content 70%, dissolved in n-butanol, average degree of polymerization 1.5) to form a clearcoat having a solids content by mass of about 54%. The flow time (DIN cup, 4 mm, 23 ^° C.) was 36 seconds; it was adjusted to 27.5 s by adding an additional 10 kg of methoxypropyl acetate (solids content by mass 51%). This clearcoat was divided into four portions, and sprayed as the topmost layer on the sheets prepared as described above.

After baking, the Erichsen cupping (6), the acid resistance (4), the gloss

(2), which determines surface quality (1), chemical resistance (5), scratch resistance (7) and adhesion (3), comparing to an uncatalyzed clearcoat composition.

The following results were obtained:

Table 2 Results of the paint test

From the paint tests, it is clear that the clearcoats catalyzed by the Har2 of Example 4 show consistently better results in the tests; only the scratch resistance in the washer test without subsequent recovery "reflow" shows one of my advantages for the para-toluenesulfonic acid catalyzed clearcoat.

The goal of using a polymeric catalyst for the curing of baked enamels

To provide aminoplast resins that are equivalent to the known low molecular weight catalysts has been achieved.

-o-o-o-o-

Claims

claims:

1. Water-dilutable polyurethane resins having acid groups, the polyurethane resins containing building blocks derived from oils A, which are at least partially unsaturated, from olefinically unsaturated aliphatic acids B or their anhydrides B ', from compounds C with acid groups or acid anhydride reactive groups selected from epoxy groups, Hydroxyl groups, mercaptan groups and amino groups which, when reacted with the compounds B or B ', react to form an ester group, a thioester group or an acid amide group, wherein the compounds C are selected from compounds C "which additionally contain sulfonic acid groups or electron-activating substituent-activated carboxylic acid groups, and compounds C, which additionally contain at least one hydroxyl group which is retained in the reaction with the compounds B or B ', and wherein at least a mass fraction of 25% of the compounds C from Verbindunge n C, and mehtfunktionellen isocyanates D.

2. Water-dilutable polyurethane resins according to claim 1, characterized in that they have a mass fraction of acid groups of 0.5 cg / g to 5 cg / g.

3. Process for the preparation of water-dilutable polyurethane resins according to claim 1, comprising the steps of a) grafting an oil A with an olefinically unsaturated aliphatic acid B or the anhydride B ¹ of such an acid, b) polymer-analogous reaction of the adduct AB from step a ) with a compound C with respect to acid groups or acid anhydride reactive functional

Groups selected from epoxide groups, hydroxyl groups, mercaptan groups and amino groups which react upon reacting with the compounds B or B 'to form an ester group, a thioester group or an acid amide group, said compounds C being selected from compounds C "which additionally contain sulfonic acid groups or electron withdrawing groups Substituents activated

Containing carboxylic acid groups, and compounds C, which additionally contain at least one hydroxyl group, in the reaction with the compounds B or B ' is maintained, wherein at least a mass fraction of 25% of the compounds C consists of compounds C ", and c) addition of the products ABC to the polyfunctional isocyanates D below

Urethane.

4. The method according to claim 3, characterized in that the compounds C are used when the graft AB itself is free of hydroxyl groups or in the reaction of the acid groups or acid anhydride groups in the graft AB no hydroxyl groups have formed.

5. The method according to claim 3, characterized in that in step a) oils A having an iodine value of 100 cg / g to 200 cg / g are used.

6. The method according to claim 3, characterized in that are used as acids B maleic acid or its anhydride.

7. The method according to claim 3, characterized in that is used as compound C "taurine.

8. Use of the water-dilutable polyurethane resins according to claim 1 as

Catalyst in the curing of hydroxyl-containing binders with aminoplast resins.

9. stoving lacquers containing hydroxyl groups have binders, aminoplast resins and the water-dilutable polyurethane resins according to claim 1.

10. stoving enamels according to claim 9, characterized in that the quotient of the mass of the water-dilutable polyurethane resin and the mass of Aminoplastharzes 0.5% to 10%. -o-o-o-o-