Patent Application
20240084156
The present invention relates to an aqueous blend of a pigment and an alkoxylated amine. The composition provides an aqueous blend of a pigment and an alkoxylated amine that is resistant to microbial growth in the absence of a biocide.
TiO2 is the opacifying pigment of choice for paint formulations. TiO2 can be added to a formulation as a dry powder or as an aqueous slurry. A slurry requires a preservative, most prevalently isothiazolinones, to prevent microbial contamination during production and storage. However, isothiazolinones are known skin sensitizers that have come under increased scrutiny by regulators for use in a variety of consumer products. In 2016, the European Commission issued a directive to limit the use of methylisothiazolinone (MIT) in most consumer products, including house paint. By 2021, the EU will not permit final formulations of these products to contain more than 15 ppm of MIT. These stringent restrictions present a challenge for paint formulators looking to control the amount of biocide in their final product. It would therefore be an advance in the art of architectural coatings to discover a way to preserve inorganic pigment containing slurries without using biocides.
The present invention addresses a need in the art by providing 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:
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.
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:
Pigments include opacifying inorganic pigments such as TiO2 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. TiO2 is an especially preferred opacifying inorganic pigment, and nepheline syenite is an especially preferred inorganic extender.
The preferred concentration of opacifying pigment, preferably TiO2, 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 TiO2-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.
Where y is 0, the compound of Formula I is preferably represented by Formula Ia:
where R4 is preferably C6-C14-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, R4=decyl), TRITON™ RW-50 (RW-50, x=5, R4=decyl), and TRITON™ RW-150 (RW-150, x=15, R4=decyl) Surfactants. (TRITON is a Trademark of The Dow Chemical Company or its Affiliates.)
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.
Another subgenus of the compound of Formula I is represented by Formula Ib:
where R3 is preferably saturated or partially saturated C14-C20-alkyl, more preferably saturated or partially saturated C16-C18-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.
Yet another subgenus of the surfactant of Formula I is illustrated by Formula Ic:
where R1 is preferably C12-C18-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).
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.
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.
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.
Preparation of Samples for Microbial Resistance
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 106-107 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.
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. C1, C2 and C3 refer to challenge 1, challenge 2 and challenge 3. A sample that failed challenges 1 and 2 was not subjected to challenge 3. TiO2 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.
The data show the impact of the ethoxylated amine of suppression of microbial growth over three challenge tests.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/013087 | 1/20/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 63142141 | Jan 2021 | US |
| Child | 18260626 | US |
