AQUEOUS BLEND OF PIGMENT AND AN ALKOXYLATED AMINE

Abstract

The present invention is composition comprising water, a pigment, and a compound of Formula I:

##STR00001##

wherein R, R.sup.1, x, and y are as defined herein.

The present invention addresses a need in the art by providing an aqueous inorganic pigment solution or dispersion that does require biocide to resist promotion of microbial growth.

Claims

1. A composition comprising, based on the weight of the composition, from 18 to 80 weight percent water, from 18 to 80 weight percent of a pigment, and from 50 ppm to 5000 ppm of a compound of Formula I: ##STR00007## wherein each R is independently H, methyl, or ethyl; R.sup.1R.sup.2NR.sup.3(CH.sub.2CH.sub.2O).sub.zH; or C.sub.6-C.sub.18; or C(CH.sub.3).sub.2R.sub.4; x is from 1 to 40; y is from 0 to 39; and z is from 0 to 39; with the proviso that when y is 0, R.sup.1 is C(CH.sub.3).sub.2R.sup.4; and when y is from 1 to 39, R.sup.1 is R.sup.2NR.sup.3(CH.sub.2CH.sub.2O).sub.yH or C.sub.6-C.sub.18; R.sup.2 is CH.sub.2CH.sub.2CH.sub.2 or CH(CH.sub.3)CH.sub.2 or CH.sub.2CH(CH.sub.3); R.sup.3 is saturated or partially unsaturated C.sub.10-C.sub.22-alkyl; R.sup.4 is C.sub.1-C.sub.2O-alkyl; and x+y+z=1 to 40; with the proviso that the water and the pigment comprise at least 95 percent by weight of the composition; and with the further proviso that when y is 0 and x is 1, the composition comprises less than 100 ppm of a biocide.

2. The composition of claim 1 which is an aqueous dispersion of an opacifying pigment having a concentration in the range of from 60 to 79 weight percent, based on the weight of the composition; wherein the composition has a pH in the range of from 8 to 10.

3. The composition of claim 2 wherein the opacifying pigment is TiO.sub.2 having a concentration in the range of from 70 to 78 weight percent, based on the weight of the composition; wherein the concentration of the water is in the range of from 20 to 28 percent; wherein the concentration of the compound of Formula I is in the range of from 50 ppm to 2000 ppm; and wherein the composition has a pH in the range of 8.5 to 9.5; wherein the composition further comprises one or more materials selected from the group consisting of dispersants, surfactants, and humectants; and wherein the TiO.sub.2, the water, and the compound of Formula I comprise at least 98 weight percent of the composition.

4. The composition of claim 3 wherein the compound of Formula I is represented by the compound of Formula Ia: ##STR00008## where R.sup.4 is C.sub.6-C.sub.14-alkyl, and x=2 to 30.

5. The composition of claim 4 wherein R.sup.4 is decyl and x=2 to 10.

6. The composition of claim 1 wherein the pigment is an inorganic extender.

7. The composition of claim 6 wherein the inorganic extender is nepheline syenite having a concentration in the range of from 20 to 50 weight percent; wherein the concentration of water is in the range of from 48 to 78 weight percent; wherein the compound of Formula I is represented by the compound of Formula Ia: ##STR00009## where R.sup.4 is C.sub.6-C.sub.14-alkyl, and x=2 to 30; wherein the concentration of the compound of Formula I is in the range of from 50 ppm to 2000 ppm; wherein the composition further comprises one or more materials selected from the group consisting of dispersants, surfactants, and humectants; and wherein the nepheline syenite, the water, and the compound of Formula I comprise at least 98 weight percent of the composition.

8. The composition of claim 1 wherein the pigment is a colorant.

9. The composition claim 1 which comprises less than 100 ppm of a biocide.

10. The composition of claim 9 which comprises 0 ppm of a biocide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention is a composition comprising, based on the weight of the composition, from 18 to 80 weight percent water, from 18 to 80 weight percent of a pigment, and from 50 ppm to 5000 ppm of a compound of Formula I:

##STR00003## [0016] wherein each R is independently H, methyl, or ethyl; [0017] R.sup.1R.sup.2NR.sup.3(CH.sub.2CH.sub.2O).sub.zH; or C.sub.6-C.sub.18; or C(CH.sub.3).sub.2R.sub.4; [0018] x is from 1 to 40; y is from 0 to 39; and z is from 0 to 39; [0019] with the proviso that when y is 0, R.sup.1 is C(CH.sub.3).sub.2R.sup.4; and when y is from 1 to 39, R.sup.1 is R.sup.2NR.sup.3(CH.sub.2CH.sub.2O).sub.yH or C.sub.6-C.sub.18; [0020] R.sup.2 is CH.sub.2CH.sub.2CH.sub.2 or CH(CH.sub.3)CH.sub.2 or CH.sub.2CH(CH.sub.3); [0021] R.sup.3 is saturated or partially unsaturated C.sub.10-C.sub.22-alkyl; [0022] R.sup.4 is C.sub.1-C.sub.20-alkyl; and [0023] x+y+z=1 to 40; [0024] with the proviso that the water and the pigment comprise at least 95 percent by weight of the composition; and [0025] with the further proviso that when y is 0 and x is 1, the composition comprises less than 100 ppm of a biocide.

[0026] Pigments include opacifying inorganic pigments such as TiO.sub.2 and ZnO; inorganic extenders such as talc, clay, mica, sericite, nepheline syenite, feldspar, wollastonite, kaolinite, and diatomaceous earth; and inorganic and organic colorants such as phthalocyanine blue, phthalocyanine green, monoarylide yellow, diarylide yellow, benzimidazolone yellow, heterocyclic yellow, quinacridone magenta, quinacridone violet, metallized azo reds, nonmetallized azo reds, carbon black, lampblack, black iron oxide, yellow iron oxide, brown iron oxide, and red iron oxide. TiO.sub.2 is an especially preferred opacifying inorganic pigment, and nepheline syenite is an especially preferred inorganic extender.

[0027] The preferred concentration of opacifying pigment, preferably TiO.sub.2, is in the range of from 60, more preferably from 65, and most preferably from 70 weight percent to 79, more preferably to 78 weight percent, based on the weight of the composition. Correspondingly, the concentration of water in a TiO.sub.2-water dispersion is preferably is in the range of from 19, more preferably from 20 weight percent, to 38, more preferably to 33, and most preferably to 28 weight percent, based on the weight of the composition. Where the pigment is an inorganic extender, preferably nepheline syenite, the preferred concentration is in the range of from 20 to 50 weight percent, and the preferred concentration of water is in the range of from 48 to 78 weight percent.

[0028] Where y is 0, the compound of Formula I is preferably represented by Formula Ia:

##STR00004##

where R.sup.4 is preferably C.sub.6-C.sub.14-alkyl, and x=2 to 30, more preferably 2 to 10, and most preferably 2 to 5. Examples of commercial surfactants within the scope of Formula Ia include TRITON RW-20 (RW-20, x=2, R.sup.4=decyl), TRITON RW-50 (RW-50, x=5, R.sup.4=decyl), and TRITON RW-150 (RW-150, x=15, R.sup.4=decyl) Surfactants. (TRITON is a Trademark of The Dow Chemical Company or its Affiliates.)

[0029] In another aspect, the concentration of the compound of Formula I is from 100 ppm, in another aspect from 150 ppm, and in another aspect from 200 ppm; to preferably 2000 ppm, more preferably to 1500 ppm.

[0030] Another subgenus of the compound of Formula I is represented by Formula Ib:

##STR00005##

where R.sup.3 is preferably saturated or partially saturated C.sub.14-C.sub.20-alkyl, more preferably saturated or partially saturated C.sub.16-C.sub.18-alkyl, and x+y+z=2 to 32. As used herein, partially unsaturated refers to the presence of one or two double bond within the alkyl chain. Examples of commercial surfactants within the scope of Formula Ib include Ethox DT-15 (DT-15, x+y+z=15); and Ethox DT-30 (DT-30, x+y+z=30) Tallow diamines.

[0031] Yet another subgenus of the surfactant of Formula I is illustrated by Formula Ic:

##STR00006##

where R.sup.1 is preferably C.sub.12-C.sub.18-alkyl, and x+y=12 to 18. An example of a commercial surfactant within the scope of Formula Ic is Ethox CAM-15 Cocoamine (CAM-15, x+y=15).

[0032] The pH of the composition is preferably in the range of from 8, more preferably from 8.5, to 10, more preferably to 9.5. The desired pH is conveniently achieved by addition of a neutralizer such as an alkali metal hydroxide, ammonia, an alkyl amine, or an alkanol amine.

[0033] The composition of the present invention may further include other materials such dispersants, surfactants, and humectants. Preferably the pigment, water, and the compound of Formula I comprise at least 98 weight percent of the composition.

[0034] It has been surprisingly discovered that slurries of pigments can be formulated in the absence of or substantial absence of biocides, yet remain unsusceptible to microbial contamination. Accordingly, the composition of the present invention comprises less than 100 ppm of a biocide where in the compound of Formula I y is 0 and x is 1; for all values of x and y, the composition preferably comprises less than 100 ppm, more preferably less than 20 ppm, more preferably less than 5 ppm, more preferably less than 1 ppm, and most preferably 0 ppm of a biocide such as an isothiazolinone, a triazine, an aldehyde, and a phenolic.

[0035] Preparation of Samples for Microbial Resistance

[0036] All samples were prepared on a speedmixer (Flaktek, Inc.). Water, inorganic pigment, surfactant, and neutralizer were added and mixed at 1500 rpm for 2 min. Samples were inoculated 3 times at 7-d intervals with 10.sup.6-10.sup.7 colony forming units per milliliter of sample (CFU/mL) of a standard pool of bacteria, yeasts, and molds obtained from American Type Culture Collection (ATCC) that are common contaminants in coatings. Once inoculated, the samples were stored in 25 C. incubators. Test samples were monitored for microbial contamination by agar plating using a standard streak plate method. Samples were plated 1 d and 7 d after each microbial challenge onto trypticase soy agar (TSA) and potato dextrose agar (PDA) plates. All agar plates were checked daily up to 7 d after plating to determine the number of microorganisms surviving in the test samples. When not being checked, the agar plates were stored in incubators, 30 C. for TSA plates and 25 C. for PDA plates. The extent of microbial contamination was established by counting the colonies, where the rating score was determined from the number of microbial colonies observed on the agar plates. Reported results come from day 7 readings. Results are described by the rating score for each type of microorganism: B=bacteria, Y=yeast, and M=mold. For example, a 3B describes a plate with 3 rating score for bacteria, or a Tr Y(1) describes a plate with trace yeast (1 colony on plate). Table 1 illustrates the rating system used to estimate the level of microbial contamination on streak plates. Colonies refers to the number of colonies on the plate.

TABLE-US-00001 TABLE 1 Rating system for estimating microbial contamination Colonies Rating Score Contamination Result None 0 None Pass 1-9 Tr Trace Pass 10 to 99 1 Very Light Fail 100 to ~1000 2 Light Fail ~1000 to 10,000 3 Moderate Fail >10,000 4 Heavy Fail

EXAMPLES

[0037] In Table 1, Pass means that no microbial growth was detected on plates 14 d after the inoculation. Fail means that more than five distinct colonies were detected on plates 14 days d inoculation. C.sub.1, C.sub.2 and C.sub.3 refer to challenge 1, challenge 2 and challenge 3. A sample that failed challenges 1 and 2 was not subjected to challenge 3. TiO.sub.2 refers to Ti-Pure R-706 Titanium Dioxide, RW-20 refers to TRITON RW-20 Surfactant, (A Trademark of The Dow Chemical Company or its Affiliates), and Minex 4 refers to Minex 4 nepheline syenite.

TABLE-US-00002 TABLE 1 Slurry Formulations with and without Ethoxylated Amine Comp. 1 Pigment RW-20 C1 C2 C3 Ex. 1 TiO.sub.2 none Fail Fail NA Ex. 2 TiO.sub.2 250 ppm Pass Pass Pass Ex. 3 TiO.sub.2 5000 ppm Pass Pass Pass Ex. 4 Minex 4 1250 ppm Pass Pass Pass

[0038] The data show the impact of the ethoxylated amine of suppression of microbial growth over three challenge tests.