COMPOSITION FOR PAINTING/COATING APPLICATIONS CONTAINING A PARTICULAR ACRYLATE COPOLYMER DISPERSANT

Abstract

The present invention relates to compositions for painting and/or coating containing particular copolymer dispersants. The invention also relates to the use of a copolymer according to the invention as a dispersant in a painting, coating and/or ink composition.

Claims

1. A composition for painting and/or coating comprising: (i) at least one copolymer having a weight average molecular weight ranging from 2 000 to 17 000 g/mol, obtainable by controlled radical polymerization of: at least the following monomers: a) at least one acrylic monomer selected from the group consisting of acrylic acid, (C.sub.1-C.sub.12)alkyl (meth)acrylate monomers, and mixtures thereof, b) at least one hydrophobic non-acrylic monomer, and c) at least one (C.sub.1-C.sub.12)alkyloxy polyethylene glycol (meth)acrylate monomer, with a radical polymerization control agent, and a free-radical polymerization initiator; said copolymer (i) comprising: up to 50 mol. % of units from acrylic monomer a), at least 35 mol. % of units from hydrophobic non-acrylic monomer b), at least 10 mol. % of units from (C.sub.1-C.sub.12)alkyloxy polyethylene glycol (meth)acrylate monomer c); and (ii) at least one pigment, and (iii) optionally, at least one water-based polymer.

2. The composition according to claim 1, wherein said copolymer (i) comprises up to 45 mol. % of units from acrylic monomer a).

3. The composition according to claim 1, wherein the (C.sub.1-C.sub.12)alkyl (meth)acrylate monomer(s) are (C.sub.1-C.sub.12)alkyl acrylates.

4. The composition according to claim 1, wherein the acrylic monomers a) are acrylic acid and at least one (C.sub.1-C.sub.12)alkyl (meth)acrylate monomer.

5. The composition according to claim 1, wherein the hydrophobic non-acrylic monomer(s) b) are vinyl aromatic monomers.

6. The composition according to claim 1, wherein said copolymer (i) comprises at least 40 mol. % of units from hydrophobic non-acrylic monomer b).

7. The composition according to claim 1, wherein the (C.sub.1-C.sub.12)alkyloxy polyethylene glycol (meth)acrylate monomer(s) c) are (C.sub.1-C.sub.4)alkyloxy polyethylene glycol (meth)acrylate monomer(s).

8. The composition according to claim 1, wherein said copolymer (i) comprises from 10 to 30 mol. % of units from (C.sub.1-C.sub.12)alkyloxy polyethylene glycol (meth)acrylate monomer c).

9. The composition according to claim 1, wherein the monomers used of the polymerization of said copolymer (i) further include a methacrylic acid monomer d), different from the acrylic monomer(s) a); and wherein said copolymer (i) comprises from 0.1 to 20 mol. % of units from methacrylic acid d).

10. The composition according to claim 1, wherein the polydispersity index of said copolymer ranges from 1 to 3.5.

11. The composition according to claim 1, wherein said copolymer (i) is free of unit from strong acid derivatives of (meth)acrylic acid monomers.

12. The composition according to claim 1, wherein the said copolymer (i) is obtainable by controlled radical polymerization of said monomers a), b), c), and optionally d), only, with said radical polymerization control agent and said free-radical polymerization initiator.

13. The composition according to claim 1, characterized in that the water-based polymer is chosen from latex polymers, polyurethane polymers, mixtures thereof.

14. The composition according to claim 13, characterized in that the water-based polymer is in the form of particles in dispersion in an aqueous medium.

15. The composition according to claim 1, characterized in that the composition is aqueous.

16. Use of A method, comprising adding the copolymer (i) of claim 1, as a dispersant in a painting and/or coating composition comprising at least one pigment.

17. Use of A method, comprising adding the copolymer (i) of claim 1, as a dispersant in an ink composition comprising at least one pigment.

Description

EXAMPLES

General Synthesis Procedure:

[0281] The copolymers A and C according to the invention were synthetized according to the same process.

[0282] The applied process in case of the examples A and C is based on the controlled radical polymerization technology in the presence of the RAFT (Madix) type transfer agent. The applied transfer agent chemistry is the xanthate and the grade used is the Rhodixan A1. The calculation of the quantity of the transfer agent to be used for polymerization is based on the target average number molar mass of the copolymer (equation below)

[00002]$\mathrm{masse}\left(\mathrm{grams}\right)\mathrm{Transfer}\mathrm{agent}=\frac{?\mathrm{masse}\left(\mathrm{grams}\right)\mathrm{of}\mathrm{all}\mathrm{monomers}*\mathrm{Mw}\mathrm{of}\mathrm{the}\mathrm{transfer}\mathrm{agent}}{\mathrm{Mn}\mathrm{target}\mathrm{of}\mathrm{the}\mathrm{polymer}}$

[0283] The target average number molecular mass of the copolymers A and C is Mn=5 000 g/mol.

[0284] The whole synthesis is conducted in typical polymerization reactor under nitrogen atmosphere at given temperature and with efficient mechanical agitation system. The polymerization solvent is the mixture of the ethanol and water. In the case of the copolymer C, the methoxypolyethylene glycol (MPEG 750) is also used as a co-solvent.

[0285] In a first time (polymerization step), the purged with nitrogen reactor is charged with all monomers, transfer agent and solvents and the reaction medium is heated to 75? C. under stirring. A part (20 wt. % of the overall amount) of the AMBN initiator ((2,2-Azobis(2-methylbutyronitrile)) solution (20 wt. % in ethanol) is added in one shot to the reaction mixture. The reaction is allowed to react for around 30 min. After this time, the rest of AMBN solution in ethanol is added over the course of around 3 hours by pump. Once the addition is completed, the reaction mixture is let to react for further 10 hours.

[0286] In a second time (ethanol removal step), the ethanol is evaporated using a rotatory evaporator, and then water is added to the mixture; the mass of water is the same as the quantity of the ethanol used initially for reaction.

[0287] In a third time (neutralization and transfer agent deactivation step) the copolymer solution in water is placed into the reactor, the pH is adjusted to about 7.5 to 8 with sodium hydroxide and heated at 70? C. under stirring. The hydrogen peroxide solution (30 wt. % in water) is added by pump over 1 hour. The reaction is let to react for around 3 hours. A sample is collected for analyses to determine residual monomers, transfer agent and ethanol. A dry extract is measured by gravimetric method. The copolymer solution in water is also tested on pH and viscosity.

[0288] According to this procedure several copolymers were synthetized, with different monomer molar ratios and copolymer molar masses.

[0289] The particular reagents and their amounts are given in the table below.

TABLE-US-00001 Quantities used in grams Raw material Copolymer A Copolymer C Ethanol (solvent) 321.12 260.55 Water (solvent) 228.88 226.80 2-Ethyl Hexyl Acrylate monomer 74.87 74.19 MPEGMA750 monomer 228.88 226.80 MPEG 750 solvent 0.00 62.64 Styrene monomer 89.92 89.11 Methacrylic Acid monomer 0.00 23.76 Acrylic Acid monomer 32.96 12.77 Rhodixan A1 transfer agent 17.07 17.07 Tert-dodecanethiol 0.00 0.00 AMBN initiator 6.30 6.30 Sodium hydroxide (50% in water) 43.18 42.90 Hydrogen peroxide (30% in water) 29.07 29.50

[0290] The table below regroups obtained copolymers characteristics.

TABLE-US-00002 Copolymer Properties Method Unit A C pH (at 25? C., solution as is) pH electrode 7.0 6.9 Solid Content Gravimetric % wt. 45.1 43.8 (115? C.; 30 min; 1 g) Viscosity (at 25? C.) Brookfield cP 920 100 Residual monomers (total) HPLC/GC % <0.5 <0.5

Molar Mass Determination

[0291] In the present patent application, unless otherwise indicated, when reference is made to molar mass, it will relate to the absolute weight-average molar mass, expressed in g/mol.

[0292] Light scattering is an absolute technique, meaning that it does not depend on any calibration standards or calibration curves (M. W. Spears, The Column 12(11), 18-21 (2016)).

[0293] The fundamental light scattering equation is:

[00003]$l\left(?\right)?M?c?{\left(\frac{\mathrm{dn}}{dc}\right)}^2?P\left(?\right)$

[0294] where the intensity of scattered light at an angle ? is directly proportional to the product of the molar mass M, the concentration c, the square of the specific refractive index increment dn/dc, and an angular factor P(?), which equals 1 at ?=0. The absolute intensity of scattered light extrapolated to ?=0 is used to calculate molecular weight, and the variance of this intensity with angle is used to calculate the root mean square (rms) radius of the sample.

[0295] The mass distribution of the polymer is measured by SEC MALS analysis (SEC: Size Exclusion ChromatographyMALS: Multi-Angle Laser Scattering) in order to obtain the real values, expressed in g/mol.

[0296] The SEC MALS analysis is performed with an HPLC chain equipped with 2 detectors: [0297] Differential refractometer RIthe concentration detector [0298] MALS detector (Multi-Angle Laser Scattering)the mass detector.

[0299] The software records the chromatograms of the detectors: [0300] One for the RI detector, [0301] One for each angle of the MALS detector.

[0302] For each slice of the chromatograms (for the polymeric species), the software calculates: [0303] The concentration of the polymer, RI signal=constant*dn/dc*concentration [0304] The mass Mi of the slice,

[0305] MALS detector=scattered light?constant?Mi?(dn/dc).sup.2?concentration

[0306] From particular Mi data, the software calculates the mass distribution: Mw, Mn and Polydispersity index PDI=Mw/Mn.

[0307] The calculation of the molar masses requires the refractive index increment, dn/dc of the polymer. It is a constant, depending on the nature of the mobile phase, the temperature of the experimental conditions and the wavelength of the laser among others.

[0308] This constant can be measured according to the eluted fraction from the SEC MALS analysis. This constant can be measured with a refractometer. This constant can be found also, for example, in the Polymer Handbook or website like www.ampolymer.com/dn-dc.html.

[0309] For these copolymers, dn/dc is calculated by the software according the mass recovery of the eluted fraction: the dn/dc=0.09 leads from 95 to 100% wt mass recovery.

[0310] For these copolymers, the molar mass were calculated based on the real Mi points, without any adjustment of the log(M) curve.

[0311] The applied injection amount and Standard sample concentration were as follows: 100 ?L, from 2.0 to 2.4 mg/mL (calculated as dry polymer).

[0312] Detailed Analysis conditions: [0313] Analysis instrument: Agilent SEC system with MALS detector [0314] Pump: Agilent 1100 [0315] Detector: Agilent 1100, Differential Refractometer (RI) [0316] Mobile phase: 100% THF, 0.01 mol/L tetrabutylammonium tetrafluoroborate, 100 ?L TFA/1L THF (TFA: trifluoroacetic acid) [0317] Column: Agilent Polypore (2*30 cm)+guard column [0318] Temperature: 35? C. [0319] Flow rate: 1.0 mL/min [0320] Injection amount and Sample concentration: 100 ?L, from 2.0 to 2.4 mg/mL (expressed in dry) [0321] Data processing: ASTRA 7 (Wyatt)

[0322] The measured for particular copolymers molar masses were the following:

TABLE-US-00003 Copolymer composition, mol. % Co- MPEG-MA Mw polymer AA MA St 2EHA 750 (g/mol) Mn PDI A 22.5 0 42.5 20 15 13900 5800 2.4 C 8.8 13.7 42.5 20 15 15600 7800 2.0

[0323] With AA=acrylic acid; MA=methacrylic acid; St=styrene; 2EHA=2-ethyl hexyl acrylate; MPEGMA750=methoxy polyethylene glycol methacrylate.

Formulation:

[0324] The following compositions (A), (C1) and (C2) according to the invention were prepared from the ingredients shown in the tables below, the amounts of which are expressed as weight percentages of active material (AM).

TABLE-US-00004 Composition (A) - Ingredients Amounts Copolymer A 2.7 Titanium dioxide 1.3 Deionized water Qs 100

TABLE-US-00005 Composition (C1) - Ingredients Amounts Copolymer C 1.3 Carbon black 0.6 Deionized water Qs 100

TABLE-US-00006 Composition (C2) - Ingredients Amounts Copolymer C 30 Raven 5000 Ultra II pigment 20 Defoamer 1 Ammonia 1.6 Deionized water Qs 100

[0325] These compositions were prepared as follows: as a starting point, prepare a formulation consisting of pigment, dispersant and deionized water, and defoamer and base (if needed). Liquid ingredients were added, including a small amount of polymeric dispersant as described herein, to the grind pot and mixed at low speeds using a high shear (Cowles) disperser. After a homogeneous mixture has been obtained, pigment was slowly added. Once all of the pigment had been added, mixed at a maximum speed needed to create a strong vortex. After premix finished, attached cooling water, added milling beads and prepared for milling. After 30 minutes milling, waited one minute and measured the viscosity via Brookfield viscometer. Continued to add dispersant incrementally and milled for 4-6 minutes after each addition.