Low-VOC, low cost coalescent for certain aqueous polymeric dispersions

Abstract

A coalescent consisting essentially of a residue from a process for forming propyleneglycol phenyl ether, the coalescent consisting essentially of 65%-75% by weight, based on the weight of the residue, dipropyleneglycol phenyl ether, 8%-10% by weight, based on the weight of the coalescent, monopropyleneglycol phenyl ether, 4%-6% by weight, based on the weight of the coalescent, tripropyleneglycol phenyl ether, and 0.1%-10% by weight, based on the weight of the coalescent, alkalinity (reported as NaOH) is provided. Also provided is a method for forming certain low-VOC, low cost, coalesced aqueous polymeric dispersions including, as copolymerized units, from 70% to 100% by weight, based on the solids weight of the aqueous polymeric dispersion, vinyl acetate monomer and an aqueous coating composition including the coalesced aqueous polymeric dispersion.

Claims

1. A coalescent consisting essentially of a residue from a process for forming a propyleneglycol phenyl ether, said residue consisting essentially of 65%-75% by weight, based on the weight of said residue, dipropyleneglycol phenyl ether, 8%-10% by weight, based on the weight of said residue, monopropyleneglycol phenyl ether, 4%-6% by weight, based on the weight of said residue, tripropyleneglycol phenyl ether, and 0.1%-10% by weight, based on the weight of said residue, alkalinity as NaOH.

2. A method for forming a coalesced aqueous polymeric dispersion comprising: a) providing a coalescent consisting essentially of a residue from a process for forming a propyleneglycol phenyl ether, said residue consisting essentially of 65%-75% by weight, based on the weight of said residue, dipropyleneglycol phenyl ether, 8%-10% by weight, based on the weight of said residue, monopropyleneglycol phenyl ether, 4%-6% by weight, based on the weight of said residue, tripropyleneglycol phenyl ether, and 0.1%-10% by weight, based on the weight of said residue, alkalinity as NaOH; and b) contacting an aqueous polymeric dispersion comprising, as copolymerized units, from 70% to 100%, by weight based on said aqueous polymeric dispersion solids weight, vinyl acetate monomer, with from 0.5% to 20% by weight, based on said aqueous polymeric dispersion solids weight, said coalescent.

3. The method of claim 2 wherein a second coalescent different from said coalescent is provided before, during or after step (b).

4. An aqueous coating composition comprising a) an aqueous polymeric dispersion comprising, as copolymerized units, from 70% to 100%, by weight based on said aqueous polymeric dispersion solids weight, vinyl acetate monomer; and b) from 0.5% to 20% by weight, based on said aqueous polymeric dispersion solids weight, of a coalescent consisting essentially of a residue from a process for forming a propyleneglycol phenyl ether, said residue consisting essentially of 65%-75% by weight, based on the weight of said residue, dipropyleneglycol phenyl ether, 8%-10% by weight, based on the weight of said residue, monopropyleneglycol phenyl ether, 4%-6% by weight, based on the weight of said residue, tripropyleneglycol phenyl ether, and 0.1%-10% by weight, based on the weight of said residue, alkalinity as NaOH.

5. The aqueous coating composition of claim 4 further comprising a second coalescent different from said coalescent.

6. The aqueous coating composition of claim 4 wherein said aqueous polymeric dispersion comprises, as copolymerized units, from 90% to 100%, by weight based on said aqueous polymeric dispersion solids weight, vinyl acetate monomer.

7. The aqueous coating composition of claim 4 further comprising at least one inorganic pigment.

8. The aqueous coating composition of claim 5 further comprising at least one inorganic pigment.

9. The aqueous coating composition of claim 6 further comprising at least one inorganic pigment.

Description

EXPERIMENTAL METHODS

(1) Determination of Percent VOC in Solvents by ASTM D2369

(2) The volatiles content of coalescent were obtained by ASTM D2369. Determinations were conducted in triplicate using aluminum weigh boats that had been previously labeled with an engraver. An empty weigh boat was placed on an analytical balance and the weight recorded. The weigh boat was then tared and 0.5000 g of the test coalescent was added in a circular motion. This procedure was repeated with the other two weigh boats. The loaded weigh boats were placed in a 110 C. oven for 1 hour as per the ASTM method. The weigh boats were then removed from the oven using metal tweezers and placed in a desiccator to cool. Once cooled, the boats were reweighed on the analytical balance. Percent volatiles were calculated using the equation that follows:

(3) $\mathrm{Percent}\mathrm{Volatiles}=100\frac{\text{[Coalescent wt.}-\text{(wt. of boat after 1 hour}-\text{wt. empty boat]}}{\text{Coalescent wt. (g)}}$
Determination of Alkalinity of Coalescent

(4) A sample of the coalescent was dissolved in methanol and titrated with 0.5000 N hydrochloric acid in methanol to the potentiometric inflection point using a Mettler T70 Autotitrator equipped with one internal 10 mL burette: (available from Mettler-Toledo, Inc.), a 100 cc. polypropylene titration beaker and a Ross Orion Sure Flow ElectrodePart No. 8172BN (available from Thermo Fisher Scientific, 81 Wyman Street, Waltham, Mass. 02454 USA). One mole of acid neutralizes one mole of alkalinity, reported as sodium hydroxide.

(5) All samples of the coalescent of the invention used in the examples contained (all values are by weight, based on the weight of the coalescent) 65%-75% dipropyleneglycol phenyl ether, 8-10% monopropyleneglycol phenyl ether, 4%-6% tripropyleneglycol phenyl ether, and 1.55% alkalinity (reported as NaOH).

Example 1. Determination of the Coalescent Efficiency

(6) The coalescent of the invention was added to a poly(VA/VV/AMPS) (94.4/5/0.6. wt.) aqueous polymeric dispersion at the indicated levels and the MFFT of the equilibrated mixtures was determined.

(7) TABLE-US-00001 TABLE 1.1 Coalescence of a poly(vinyl acetate/butyl acrylate) (95/5, wt) aqueous polymeric dispersion Wt % Coalescent MFFT( C.) 0 17 2 12 4 8 6 5
The coalescent of the present invention is an effective coalescent for the 94.4% vinyl acetate aqueous polymeric dispersion.

Example 2. Determination of the Coalescent Efficiency of the Coalescent of the Present Invention Relative to the Higher Cost Commercial Coalescent Agents Optifilm 400 and DPBA

(8) Coalescent at a 10 or 15 weight % level based on the weight of aqueous dispersion solids was added to a poly(vinyl acetate/butyl acrylate) (95/5, wt) aqueous polymeric dispersion. The mixture was stirred for 1 hr. at 25 C. The mixture was held at 25 C for 2 hrs before drawing down the samples on the MFFT bar and measuring the MFFT. Results are presented in Table 2.1 below.

(9) TABLE-US-00002 TABLE 2.1 Coalescence of a poly(vinyl acetate/butyl acrylate) (95/5, wt) aqueous polymeric dispersion Coalescent Wt % Coalescent MFFT( C.) None 0 40 DPBA 10 30 DPBA 20 30 OPTIFILM 10 32 OPTIFILM 20 23 Residue 10 15 Residue 20 5 DPBA = dipropyleneglycol n-butyl adipate
The coalescent of the present invention exhibits greater efficiency in coalescing a 95% poly(vinyl acetate) aqueous polymeric dispersion relative to the other higher cost, low-VOC capable coalescents.

Example 3. Determination of the Coalescent Efficiency of the Residue Relative to the Higher Cost More Volatile Commercial Coalescent Agent TEXANOL

(10) The indicated coalescent was added to an aqueous polymeric dispersion at the indicated levels and the abrasive scrub resistance of the coating formed therefrom {coating was an above critical PVC formulation (63PVC, 30VS)} was determined according to the teachings of ASTM method D2486 after equilibration for 7 days at 77 F. and 50% RH as a proxy for effective film formation and resultant film toughness.

(11) TABLE-US-00003 TABLE 3.1 Determination of residue coalescent efficacy relative to TEXANOL coalescent. Coalescent Polymeric of dispersion TEXANOL the invention composition (wt.) (wt. % on (wt. % on Abrasive Abrasive VA/BA/VV/ polymer polymer Scrub- Scrub std. AMPS/IA solids) solids) mean deviation 78.5/16/5/0.3/0.2 7 0 226 44 94.4/0/5/0.6/0 7 4 150 24 94.4/0/5/0.6/0 11 0 141 19 94.4/0/5/0.6/0 0 11 112 20 78.5/16/5/0.3/0.2 0 7 226 44 The coalescent of the invention functions comparably to the higher cost TEXANOL in a lower VOC formulation. TEXANOL is 100% volatile by the ASTM test D2369 detailed hereinabove while coalescent of the invention is only 38.8% volatile.

Example 4. Determination of Hydrolytic Stability of Certain Polymeric Dispersions Coalesced with Various Coalescents

(12) A polymeric dispersion including as copolymerized units, 85% vinyl acetate, by weight based on polymer weight was loaded with 4%, 6%, 8% coalescent by weight based on polymer solids. The coalesced dispersion was neutralized to pH 8.35 with ammonia and subjected to heat aging in an oven at 50 C. and the pH recorded over a period of 14 days. The pH change was taken as a measure of the degree of hydrolysis of the polymer of the polymeric dispersion, lower pH corresponding to a higher degree of hydrolysis.

(13) TABLE-US-00004 TABLE 4.1 Data regarding polymer hydrolysis Initial Adj. 1 day 4 day 7 day 14 day 14 day Description pH pH HA HA HA HA R.T. No 4.56 8.35 7.64 6.89 6.68 6.57 7.61 coalescent 4% Coal. of 4.87 8.35 7.45 6.80 6.63 6.56 7.55 invention 6% Coal. of 5.05 8.52 7.91 7.13 6.90 6.77 7.95 invention 8% Coal. of 5.10 8.46 7.63 6.92 6.74 6.67 7.72 invention 4% DPPH 4.66 8.32 7.48 6.82 6.64 6.57 7.54 6% DPPH 4.60 8.22 7.30 6.74 6.57 6.53 7.44 8% DPPH 4.72 8.26 7.36 6.74 6.60 6.53 7.47 DPPH = Dipropyleneglycol phenyl ether

(14) The coalescent of the invention in the method of the present invention at 6% and 8% loadings beneficially slows the hydrolysis of the vinyl acetate polymer relative to DPPH coalescent.