Rheology modifier blends with nonionic surfactant

Abstract

The present invention is a composition comprising a) water; b) an acid suppressed HEUR thickener; c) an ASE or a HASE thickener; and d) a nonionic surfactant having a hydrophilic lipophilic balance in the range of from 11 to 19; wherein the weight-to-weight ratio of the acid suppressed HEUR thickener to the ASE or the HASE thickener is in the range of from 20:80 to 95:5. The composition of the present invention provides desirable heat-stability.

Description

[0001] Rheology Modifier Blends with Nonionic Surfactant

[0002] Background of the Invention

[0003] The spray-coat application of a paint onto a vertical surface is promoted by high sag resistance and ease of spray application of the paint; therefore, a rheology modifier that provides low shear viscosity, high sag resistance, and resistance to sedimentation, while still maintaining relatively low viscosities at mid-shear and high shear realms would be especially beneficial for the desired application. Hydrophobically modified ethylene oxide urethane polymers (HEUR thickeners) provide excellent flow and leveling as well as water and corrosion resistance; however, HEUR thickeners do not provide the necessary shear-thinning performance as thickeners such as alkali swellable emulsions (ASE thickeners) and hydrophobically modified alkali swellable emulsions (HASE thickeners). On the other hand, these highly acidic ASE and HASE thickeners in paint formulations provide films that are less resistant to water, therefore more prone to blistering; moreover, the adverse impact on film performance (e.g., scrub resistance) is exacerbated at higher concentrations of these hydrophilic thickeners.

[0004] Blending HEUR and ASE thickeners have been found to improve shear-thinning profiles; nevertheless, blending these two classes of rheology modifies often results in phase separation or gelation of the polymers. In some instances, the blends may initially appear to be stable, but phase-separate or gel upon heat aging. Accordingly, it would be an advance in the art of spraycoating technology to discover a heat-age stable thickener composition that provides coating compositions with the desired viscosity profiles.

[0005] Summary of the Invention

[0006] The present invention addresses a need in the art of spray-coating by providing a composition comprising a) water; b) an acid suppressed HEUR thickener; c) an ASE or a HASE thickener; and d) a nonionic surfactant having a hydrophilic lipophilic balance in the range of from 9 to 19; wherein the weight-to-weight ratio of the acid suppressed HEUR thickener to the ASE or the HASE thickener is in the range of from 20:80 to 95:5; and wherein the concentration of the sum of the HEUR and the ASE or HASE thickeners is in the range of from 15 to 35 weight percent, based on the weight of the composition. The composition of the present invention provides desirable heat-stability. Detailed Description of the Invention

[0007] The present invention is a composition comprising a) water; b) an acid suppressed HEUR thickener; c) an ASE or a HASE thickener; and d) a nonionic surfactant having a hydrophilic lipophilic balance in the range of from 9 to 19; wherein the weight-to-weight ratio of the acid suppressed HEUR thickener to the ASE or the HASE thickener is in the range of from 20:80 to 95:5; and wherein the concentration of the sum of the HEUR and the ASE or HASE thickeners is in the range of from 15 to 35 weight percent, based on the weight of the composition.

[0008] A HEUR thickener is conveniently prepared by contacting under suitable reactive conditions, a) a water-soluble poly alkylene glycol; b) a stoichiometric excess of a diisocyanate relative to the polyalkylene glycol; and c) a hydrophobic compound functionalized with a secondary or a tertiary amine. An acid suppressed HEUR thickener is an alkylene oxide polymer modified with a hydrophobic portion functionalized with a protonated secondary or a protonated tertiary amine. As used herein, the term “hydrophobic portion” refers to the hydrophobic compound except for the hydrogen atom or atoms associated with group or groups that react with the isocyanate portion of the ethylene oxide polymer backbone. For example, if the hydrophobic compound used to form the hydrophobic portion is 2-(dibutylamino) ethanol, the hydrophobic portion is characterized by the following formula: where the dotted line represents the point of attachment to the alkylene oxide polymer backbone.

[0009] The hydrophobic portion is also known as the structural unit of the hydrophobic compound.

[0010] Examples of hydrophobic compounds that can be used to generate hydrophobic groups include

[0011] 2-(diethylamino)ethanol; 2-(z-butylamino)ethanol; 2-(dibutylamino)ethanok

[0012] 2-(dipentylamino)ethanol; 2-(dioctylamino)ethanol; 2-(diheptylamino)ethanol;

[0013] 2-(bis(2-ethylhexyl)amino)ethanol; 2-(dihexylamino)ethanol; S-ldibutylaminoJpropanol;

[0014] 4-(dimethylamino)- 1-butanol; l-dimethylamino-2-propanol 2-(diisopropylamino)ethanol; dibenzylaminoethanol; 2-(dimethylamino)ethanol 3-(dimethylamino)-l,2-propanediol; l-(dibutylamine)-2-butanol; l-(benzyl(2-hydroxyethyl)amino)-3-alkoxypropan-2-ols such as l-(benzyl(2-hydroxyethyl)amino)-3-butoxypropan-2-ol and l-(benzyl(2-hydroxyethyl)amino)-3- (2-ethylhexyl)oxypropan-2-ol; l-[bis(phenylmethyl)amino]-3-[(2-alkoxy]-2-propanols such as l-[bis(phenylmethyl)amino]-3-[(2-butyl)oxyl]-2-propanol and l-[bis(phenylmethyl)amino]-3- [(2-ethylhexyl)oxyl]-2-propanol; and dibenzylaminopolyalkylene oxides of the type: where R1is methyl or ethyl and n is from 1 to 10.

[0015] The nonionic surfactant having a hydrophilic-lipophilic balance (HLB) in the range of 9 or from

[0016] 11, to 19. HLB is determined by the equation:

[0017] MW of hydrophilic group

[0018] HLB = 20 x - , — - - ; - : -

[0019] MW of molecule where MW is molecular weight.

[0020] An example of a preferred class of nonionic surfactants is a linear or branched alcohol ethoxylate having the following formula:

[0021] R1(CHR2CH2O)X-H where R1is a saturated or partially unsaturated linear or branched Ce-Ceo-alkyl group; and each R2is independently H, methyl, or ethyl, and x is from 2 to 100. As used herein, “partially unsaturated” allows for the presence of one or more double bonds in R1group. R1is preferably a Cio-C24-alkyl group; each R2is preferably independently H or CH3; most preferably each R2is H; and x is preferably in the range of from 6 to 50. Examples of commercially available nonionic surfactants include TERGITOL™ 15-S-7 Surfactant (15-S-7, HLB = 12.1), TERGITOL™ 15-S-9 Surfactant (15-S-9, HLB = 13.3), TERGITOL™ 15-S-20 Surfactant (15-S-20, HLB = 16.3); TERGITOL™ 15-S-40 Surfactant (15-S-40, HLB = 18); and Ecosurf SA-7 Surfactant (SA-7, HLB = 9.7). (TERGITOL is a Trademark of The Dow Chemical Company or its Affiliates.) The nonionic surfactant is used in a sufficient amount to eliminate or substantially eliminate formation of sediment in the composition when subjected to a temperature of 50 °C for two weeks. Preferably the concentration of the nonionic surfactant is preferably in the range of from 0.5, more preferably from 1 weight percent, to 10, more preferably to 6 weight percent, based on the weight of the composition. Preferably, at least 90, more preferably at least 95, and most preferably at least 98 weight percent of the composition comprises water, the HEUR, the ASE or HASE, and the nonionic surfactant.

[0022] The concentration of the sum of the HEUR and the ASE or HASE thickeners is preferably in the range of from 15 to 30 weight percent, based on the weight of the composition. The composition of the present invention provides a heat-age stable thickener that can be used in coating compositions with desired viscosity profiles.

[0023] Examples

[0024] In the following examples, DR-5500 refers to ACRYSOL™ DR-5500 HASE Thickener; ASE-60 refers to ACRYSOL™ ASE-60 Thickener (ACRYSOL™ is a Trademark of The Dow Chemical Company or its Affiliates); 15-S-40 refers to TERGITOL 15-S-40 Surfactant; HEUR1 refers to the HEUR described in US 7,741,401 (Bobsein), Example 1.

[0025] Example 1 - Preparation of HEUR / HASE Blend with Nonionic Surfactant

[0026] DR-5500 (55.22 g, 30% solids) was added to a vessel with gentle mixing. 15-S-40 Surfactant (8.53 g, 70% solids) was then added followed by addition of HEUR1 (55.65 g, 18% solids). The composition had a %HEUR1 (100 x HEUR / (HASE + HEUR)) of 37.7%.

[0027] Example 2 - Preparation of HEUR / ASE Blend with Nonionic Surfactant

[0028] ASE-60 (59.25 g, 28% solids) was added to a vessel with gentle mixing. 15-S-40 Surfactant (8.80 g, 70% solids) was then added followed by addition of HEUR1 (55.18 g, 18% solids). The composition had a %HEUR1 of 37.4%.

[0029] Example 3 - Preparation of HEUR / HASE Blend with Nonionic Surfactant

[0030] The method of Example 1 was repeated except that DR-5500 (5.42 g), 15-S-40 (6.69 g), and HEUR1 (81.56 g) were used. The composition had %HEUR1 of 90.0%.

[0031] Comparative Examples 1-3 were prepared as described above except that nonionic surfactant was not added to any of these compositions. Heat-Age Testing

[0032] The example and comparative example compositions were heated at 50 °C for 2 weeks and evaluated for stability. Table 1 illustrates the results of the heat-age studies. “Pass” means that the blend was free of gel formation or sediment while “Fail” means that gel formation or sediment or both were observed.

[0033] Table 1 - Heat- Age Results of Thickener Compositions

[0034] The comparable examples were all derived from Bobsein. Specifically, Comp. 1 was prepared as described for Blend M3, Comp. 2 was prepared as described for M4, and Comp. 3 was prepared as described for M7. (See Table 2, column 17 of Bobsein.) Each of these samples showed heat instability under heat-age conditions while the samples that contained nonionic surfactant showed either no observable sediment or gel or trace levels.

[0035] Additional experiments were carried out to demonstrate that 15-S-7, 15-S-9, 15-S-20, and SA-7 surfactants were also effective at 5% wt concentrations in eliminating or substantially eliminating gel and sediment formation in the composition subjected to heat-age conditions.

Claims

Claims:

1. A composition comprising a) water; b) an acid suppressed HEUR thickener; c) an ASE or a HASE thickener; and d) a nonionic surfactant having a hydrophilic lipophilic balance in the range of from 9 to 19; wherein the weight-to- weight ratio of the acid suppressed HEUR thickener to the ASE or the HASE thickener is in the range of from 20:80 to 95:5; and wherein the concentration of the sum of the HEUR and the ASE or HASE thickeners is in the range of from 15 to 35 weight percent, based on the weight of the composition.

2. The composition of Claim 1 wherein the acid suppressed HEUR thickener comprises structural units of a hydrophobic compound selected from the group consisting of 2-(diethylamino)ethanol; 2-(r-butylamino)ethanol; 2-(dibutylamino)ethanol;2-(dipentylamino)ethanol; 2-(dioctylamino)ethanol; 2-(diheptylamino)ethanol; 2-(bis(2-ethylhexyl)amino)ethanol; 2-(dihexylamino)ethanol; 3-(dibutylamino)propanol; 4-(dimethylamino)- 1-butanol; l-dimethylamino-2-propanol 2-(diisopropylamino)ethanol; dibenzylaminoethanol; 2-(dimethylamino)ethanol 3 -(dimethylamino)- 1 ,2-propanediol; l-(dibutylamine)-2-butanol; l-(benzyl(2-hydroxyethyl)amino)-3-alkoxypropan-2-ols such as l-(benzyl(2-hydroxyethyl)amino)-3-butoxypropan-2-ol and l-(benzyl(2-hydroxyethyl)amino)-3- (2-ethylhexyl)oxypropan-2-ol; l-[bis(phenylmethyl)amino]-3-[(2-alkoxy]-2-propanols such as l-[bis(phenylmethyl)amino]-3-[(2-butyl)oxyl]-2-propanol and l-[bis(phenylmethyl)amino]-3- [(2-ethylhexyl)oxyl]-2-propanol; and dibenzylaminopolyalkylene oxides of the type:where R1is methyl or ethyl and n is from 1 to 10.

3. The composition of Claim 2 wherein the nonionic surfactant is a linear or branched alcohol ethoxylate having the following formula:R’(CHR2CH2O)X-H where R1is a saturated or partially unsaturated linear or branched Ce-G.o-alkyl group; and each R2is independently H, methyl, or ethyl, and x is from 2 to 100; wherein the concentration of the nonionic surfactant is in the range of from 0.5 to 10 weight percent, based on the weight of the composition; and the acid suppressed HEUR thickener comprises structural units of a hydrophobic compound selected from the group consisting of (bis(2-ethylhexyl)amino)ethanol, 2-(dioctylamino)ethanol, dibenzylaminoethanol, l-(benzyl(2-hydroxyethyl)amino)-3-((2- ethylhexyl)oxy)propan-2-ol, l-(benzyl(2-hydroxyethyl)amino)-3-butoxypropan-2-ol, l-[bis(phenylmethyl)amino]-3-[(2-butyl)oxyl]-2-propanol and l-[bis(phenylmethyl)amino]-3- [(2-ethylhexyl)oxyl]-2-propanol.

4. The composition of Claim 3 where R1is a Cw-C24-alkyl group; each R2is independently H or CH3; and x is in the range of from 6 to 50.

5. The composition of Claim 1 wherein at least 90 weight percent of the composition comprises water, the HEUR, the ASE or the HASE, and the nonionic surfactant.

6. The composition of Claim 4 wherein at least 98 weight percent of the composition comprises water, the HEUR, the ASE or the HASE, and the nonionic surfactant.

7. The composition of Claim 6 wherein the concentration of the sum of the HEUR and the ASE or HASE thickeners is in the range of from 15 to 30 weight percent, based on the weight of the composition.

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