DE4422851A1 - Water-dilutable binder prepn. for poly:isocyanate-hardenable lacquers - Google Patents

Abstract

Prepn. of a water-dilutable binder comprises, either: (A) (i) forming a thixotropic agent as a stable aq. emulsion by: (a) addn. of an anionic, cationic or nonionic emulsifier to organic solns. of thixotropic polyester and/or polyacrylate resins known from solvent lacquer technology and having OH gp. content 1-8 wt.%, and (b) diluting with water; and (ii) mixing this thixotropic agent with a water-dilutable polyisocyanate-crosslinkable base binder contg. non-thixotropic polyester and/or polyacrylate resins; or (B) effecting step (i) with only part of the polyester and/or polyacrylate resin content being thixotropic.

Description

The invention relates to a method for producing a water-dilutable binder for one by adding Polyisocyanate curing two-component structural paint. Of the Two-component textured paint is by stirring in Polyiso cyanate in the binder ready for use for a limited time and cures with crosslinking of the binder with isocyanate out.

In a water-dilutable known from DE 38 29 587 A1 The binder consists of two-component coating agent from a polymer which sulfonate and / or carboxylate contains groups. In the manufacture of the polymer Monomers also used, the carboxyl and / or sulfonic acid group pen included. By neutralizing the acid groups with organic bases or amines becomes water-soluble or Dispersibility of the polymer achieved. From DE 41 01 527 A1 is a binder that can be crosslinked with polyisocyanate Two-component coating agent known, which consists of a aqueous solution or dispersion of a water-dilutable Polyol component consists, the polyol component of min least one urethane, carboxylate and hydroxyl groups pointing polyester resin. The well-known, water-diluted Binder for two-component coating agents run very well and are used as binders for textured paints not suitable. The addition of bentonites as known Thixotropic agent is not sufficient to apply the Coating agents to achieve a sufficient structure.  

Solvent-based paint practice has resulted in thixotropy Known polyester and polyacrylate resins after blending with non-thixotropic binders, for example Polymers and / or condensates and / or solvents or Diluent good as a binder for structural paints are suitable. A process for the thixotropy of polyols is known from DE-PS 23 59 923. The known method is suitable for OH-containing polyacrylate and polyester resins are externally crosslinkable with polyisocyanates and as Binders are suitable for two-component structural paints. From the solvent-based paint practice known thixotropic However, polyester and polyacrylate resins are not water-soluble and within the scope of the known measures for Production of a water-dilutable binder is not applicable.

The invention has for its object to dilute a water bar binder for a two-component structural paint, the by stirring polyisocyanate into the binder for be limited time is ready to use and with networking the bin cures with isocyanate.

To achieve this object, the invention teaches that from one known from solvent-based paint practice thixotropic ten polyester and / or polyacrylate resin, which in an or ganic solvent is dissolved and contains OH groups from 1 to 8% by weight, by adding an anionic, cationic or nonionic emulsifier and on final dilution with water a thixotropic agent is produced in the form of a stable aqueous emulsion and that the thixotropic agent with a water-dilutable, base binder crosslinkable with polyisocyanate, which  non-thixotropic polyester and / or polyacrylate resins holds, is mixed. The emulsifier is preferably used in amounts from 0.1 to 10% by weight, based on the solvent-containing form of the thixotropic polyester and / or polyacrylate resin set. The use of thixotropic poly is preferred ester and / or polyacrylate resins which according to the from DE-PS 23 59 923 known processes have been thixotropic.

Known from the solvent-based paint practice thixotropic OH-containing polyacrylates and polyesters are characterized by high Thixotropy. The teaching of the invention enables Use of these rheological properties in a water dilutable binder. By setting the mix ratio ratio of thixotropic and non-thixotropic The rheological properties are polyester and / or polyacrylates Controllable properties of the binder. The mixing ratio the thixotropic resins and the non-thixotropic resins is adjustable in a wide range from 0.02 to 4. Be a mixing ratio of 0.1 to 0.4 of thixo is preferred tropized resins to the non-thixotropic resins. The one position of their mixing ratio can be different Way.

An embodiment of the method according to the invention provides before that as a base binder one with an anionic, cationic or nonionic emulsifier stabilized aqueous emulsion from a solventborne paint practice known, water-insoluble dissolved in organic solvent union, carboxylate-free and sulfonate-free polyester and / or polyacrylate resin containing hydroxyl groups of 2.5 to 8 wt .-% is used. The solids content that is used for Production of the basic binder used polyester  and / or polyacrylate resins is in the range from 70 to approximately 100% by weight, mostly at 95% by weight, the rest organic Solvents. The lowest possible organic content Solvents are sought. The polyester or Polyacrylate resins have a viscosity of 1000 to 11,000 mPa · s / 23 ° C measured in a rotary viscometer. You will be in their water-insoluble form, i.e. carboxylate and sulfonate free, used in aqueous emulsion, the emulsion with With the help of a polyester and / or polyacrylate resin NEN emulsifier is produced.

According to another embodiment of the method according to the invention rens is used as a base binder and / or Dispersion of a polymer having hydroxyl groups an average molecular weight of 500 to 50,000 one Hydroxyl number from 16.5 to 264 mg KOH / g solid resin, an acid number up to 150 mg KOH / g solid resin, containing chemically ge bound carboxylate and / or sulfonate groups totaling 5 up to 417 milliequivalents per 100 g solid. Water solutions of such polymers are known (DE 38 29 587 A1). Finally, one can also be used as a basic binder DE 41 01 527 A1 known aqueous solution or dispersion at least one urethane, carboxylate and hydroxyl groups having polyester resin can be used.

According to the previously described embodiments of the fiction According to the process, a thixotropic agent is first used in Made in the form of a stable aqueous emulsion and this is then used as an additional component with a water-dilutable Polyisocyanate crosslinkable base binder, which is not contains thixotropic polymers, added. An alterna tive process variant provides that in the solvent  containing paint practice known polyester and / or polyacrylate resins which have an OH group content of 1 to 8% by weight have and which are present dissolved in organic solvents, by adding an anionic, cationic or non-ionic gene emulsifier and subsequent dilution with water a stable, aqueous emulsion is prepared, a Part of the polyester and / or polyacrylate resins as thixotro present resins. With this process variant non-thixotropic and thixotropic resins in their water-insoluble form first mixed and then to the binder emulsion according to the invention further processed. 10 to 35% by weight of polyester and / or poly are preferred acrylate resins used as thixotropic resins. Thereby emp it is true that those dissolved in organic solvents thixotropic and non-thixotropic resins with increased Temperature mixed, part of the solvent removed and the Emulsifier is also added at elevated temperature. The Processing temperature up to the addition of emulsifier is preferred wise in the range of 80 to 100 ° C. As a quantity of emulsifier recommends the invention 0.1 to 10 wt .-% based on the solvent-containing form of polyester and / or polyacrylate resins.

In the binder produced according to the invention, customary Auxiliaries and additives in paint technology, for example Pigments, dispersing agents for pigment distribution, Defoamers and the like can be added.

The binder is in the form of an aqueous emulsion. In the emulsion becomes a liquid organic polyisocyanate com component of at least one polyisocyanate with free isocya nat groups stirred in emulsifying. The NCO / OH equivalent  ratio can be set in the range from 0.5: 1 to 5: 1 and is preferably 1.15: 1. The mixture is ready for use for a limited time and hardens Crosslinking reaction. Surprisingly, they keep aqueous two-component Structural paints also structure after air and oven drying. They are known to those from organic paint practice are equivalent.

In the following the invention is illustrated by some Exemplary embodiments explained.

Binder A

116.5 parts of a thixotropic acrylic resin (Jagotex 218 tix 60 percent xylene, from Jäger, Düsseldorf) Vacuum distillation removed 16.5 parts of xylene, so that a 70th percent solution arises. By adding 0.7 parts Acrylic polyglycol ether and 0.3 part 2,4,7,9-tetra-methyl-5- decin-4,7-diol as emulsifiers and addition of 40 parts of water a 50 percent emulsion is created.

Binder B

A mixture of 35 parts of a thixotropic acrylic resin (Jagotex 218 tix 60 percent xylene) and 81 parts of one non-thixotropic acrylic resin (Joncryl 507 80 percent Butyl acetate, Johnson Polymer) are by Vacuum distillation 16 parts of solvent removed, so that a 74 percent solution arises. By adding 0.8 parts Acrylic polyglycol ether, 0.2 parts 2,4,7,9-tetra-methyl-5- decin4,7-diol, 0.5 parts sorbitan monooleate as emulsifiers and 50 parts water creates a 50 percent emulsion.  

Binder C

70 parts of a non-thixotropic base binder in the form an aqueous solution of a hydroxyl group Polymers (acrylic resin Bayhydrol VP LS 2052 38 percent Wasser, Bayer AG) are adjusted to pH = 7.2 with DMEA and mixed with 30 parts of binder A.

Binder D

45 parts of a water-dilutable, non-thixotropic Polyester resin (Synaqua 3510 W1 80 percent, from Cray Valley) are mixed with 32 parts of water and added set from DMEA to ph = 7 and with 23 parts Binder A mixed.

Binder E

A mixture of 35 parts of a thixotropic acrylic resin (Jagotex 218 tix 60 percent xylene) and 81 parts of one non-thixotropic acrylic resin (Joncryl 507 80 percent Butyl acetate) 16 parts by vacuum distillation Solvent removed so that a 74 percent solution arises. This solution is heated to 80 ° C, and by addition 0.8 parts of acrylic polyglycol ether, 0.2 parts 2,4,7,9-tetra-methyl-5-decyne-4,7-diol, 0.5 part sorbitan monooleat and 50 parts water creates a 50 percent Emulsion.

Structural paints were used with the described binders manufactured. This is explained using two exemplary embodiments.  

Recipe 1:
58 parts of binder B
25 parts of titanium dioxide rutile (R-KB-4, Bayer AG)
0.2 parts defoamer (Byk 034, Byk, Wesel).

This mixture was predispersed with a dissolver, then dispersed with a bead mill and finally diluted with 16.8 parts of water. This mixture was Parts of a commercially available polyisocyanate component (Desmodur VP LS 2025 90 percent, remainder organic solvent) transferred. The paint films obtained gave a rough structure, which could be varied by adding water. The films were hard, silky matt and tough elastic. The pot life of this Mixing was about 2.5 hours. Liability on various plastics and non-ferrous metals proved as very good.

Recipe 2:
62 parts of binder D
25 parts of titanium dioxide rutile (R-KB-4, Bayer AG)
0.4 parts defoamer (Byk 034, Byk, Wesel).

This mixture was predispersed with a dissolver and then with the pearl mill for 15 min. dispersed and with Diluted 12.6 parts water. This mixture was Parts of a commercially available polyisocyanate component (Desmodur VP LS 2025 90 percent, rest of organic solvent added. The paint films obtained also gave a rough structure, which could be varied by adding water. The films were shiny and tough elastic. The pot life of this mixture was at about 3.5 hours.  

By mixing the different binders A to E. Structure, pot life, degree of gloss, adhesion, hardening, weather and lightfastness, adaptation to processing procedure and the like are changed.

Claims (11)

1. A process for producing a water-thinnable bandage by means of a two-component structural lacquer hardening by adding polyisocyanate, wherein
from a thixotropic polyester and / or polyacrylate resin known from solventborne coating practice, which is dissolved in an organic solvent and has an OH group content of 1 to 8% by weight, by adding an anionic, cationic or nonionic Emulsifier and subsequent dilution with water is a thixotropic agent in the form of a stable aqueous emulsion and
the thixotropic agent is mixed with a water-dilutable, polyisocyanate-crosslinkable base binder which contains non-thixotropic polyester and / or polyacrylate resins. 2. The method of claim 1, wherein the emulsifier in amounts from 0.1 to 10% by weight based on the solvent-containing form of the thixotropic polyester and / or polyacrylate resin is set. 3. The method of claim 1 or 2, wherein the thixotropic resins and the non-thixotropic resins in the mixing process Ratio of 0.02 to 4, preferably in the mixing ratio from 0.1 to 0.3.   4. The method according to any one of claims 1 to 3, wherein as Basic binder one with an anionic, cationic or nonionic emulsifier stabilized aqueous emulsion one known from the solventborne paint practice, in or ganic solvent, water-insoluble, carboxylate and sulfonate-free polyester and / or polyacrylate resin a hydroxyl group content of 1 to 8% by weight is used becomes. 5. The method according to any one of claims 1 to 3, wherein as Base binder an aqueous solution and / or dispersion of a polymer having hydroxyl groups with a average molecular weight of 500 to 50,000 a hydroxyl number from 16.5 to 264 mg KOH / g solid resin, an acid number up to 150 mg KOH / g solid resin, containing chemically bound Carboxylate and / or sulfonate groups from a total of 5 to 417 Milliequivalents per 100 g of solid is used. 6. The method according to claim 5, wherein as a base binder aqueous solution or dispersion of at least one urethane, Polyester resin containing carboxylate and hydroxyl groups is used. 7. Process for making a water-thinnable bandage means for a curing by adding polyisocyanate Two-component structural paint, where from known in solventborne paint practice Polyester and / or polyacrylate resins that contain have from OH to 1 to 8 wt.% and the in organic solvent are dissolved, by addition an anionic, cationic or nonionic  Emulsifier and subsequent dilution with water a stable, aqueous emulsion is produced and a part of the polyester and / or polyacrylate resins as thixotropic resins are present. 8. The method of claim 7, wherein 10 to 35 wt .-% of Polyester and / or polyacrylate resins as thixotropic resins be used. 9. The method according to claim 7 or 8, wherein the in organic Solvent thixotropic and non-thixotropic Resins mixed at elevated temperature, part of the solvent removed and the emulsifier added at elevated temperature is set. 10. The method of claim 9, wherein the organic resin sol solution up to the emulsifier temperature of 80 to 100 ° C having. 11. The method according to any one of claims 7 to 10, wherein the Emulsifier the resin mixture in amounts of 0.1 to 10 wt .-% be moved to the solvent-based form of polyester and / or Polyacrylate resin is added.