WO2013028640A2

WO2013028640A2 - Aqueous pigment dispersion containing low molecular weight polytrimethylene ether glycol

Info

Publication number: WO2013028640A2
Application number: PCT/US2012/051629
Authority: WO
Inventors: Rajesh Gopalan Saliya; Ayumu Yokoyama; Hari Babu Sunkara
Original assignee: E. I. Du Pont De Nemours And Company
Priority date: 2011-08-19
Filing date: 2012-08-20
Publication date: 2013-02-28
Also published as: WO2013028640A3

Abstract

The present disclosure is directed to an aqueous pigment dispersion comprising low molecular weight polytrimethylene ether glycol. This disclosure is further directed to an antimicrobial aqueous pigment dispersion comprising the low molecular weight polytrimethylene ether glycol. The pigment dispersion can be used in coating compositions as interior and exterior top coats, basecoats, primers, primer surfacers and primer fillers. The disclosure is particularly directed to an aqueous pigment dispersion comprising components derived from renewable resources.

Description

TITLE

AQUEOUS PIGMENT DISPERSION CONTAINING LOW MOLECULAR WEIGHT POLYTRIMETHYLENE ETHER GLYCOL FIELD OF DISCLOSURE

[01] The present disclosure is directed to an aqueous pigment dispersion comprising low molecular weight polytrimethylene ether glycol. This disclosure is further directed to an antimicrobial aqueous pigment dispersion comprising the low molecular weight polytrimethylene ether glycol. The disclosure is particularly directed to an aqueous pigment dispersion comprising

components derived from renewable resources.

BACKGROUND OF DISCLOSURE

[02] Coating compositions are utilized to form coatings, such as, for example, primers, basecoats and clearcoats, for protective and decorative purposes. These coatings can be used in buildings, machineries, equipments, automotive OEM and refinish, and other coating applications. The coating can provide one or more protective layers for the underlying substrate and can also have an aesthetically pleasing value. The coating compositions can contain one or more organic solvents or other organic contents, known as volatile organic content (VOC) that may enter the environment. Pigments, either organic or inorganic, are typically used in coating compositions to provide desired colors, appearances, or protections, such as corrosion protections or radiation protections. Pigments are typically dispersed into pigment dispersions with one or more dispersants and the resulted dispersion can be incorporated into coating compositions.

[03] Water based low VOC coating compositions or pigment dispersions, also known as waterborne or aqueous coating compositions, or waterborne or aqueous pigment dispersions, respectively, are susceptible to microbial growth. Antimicrobial agents and preservatives have been used to kill or inhibit the growth of harmful microorganisms. Commonly used antimicrobial agents can include parabens, esters of p-benzoic acid, formaldehyde releasers, isothiazolinones, organic acids, and organic alcohols. Certain metals, metal particles or metal salts, such as copper quinolinolate or silver nano-particles, can also be used as antimicrobial agents. Some of the antimicrobial agents can be used in coatings for inhibiting the growth of microorganisms on surfaces or substrates. However, each of the antimicrobial agents has certain limitations such as biocide tolerance, public perception, toxicity (including skin irritation or sensitization), incompatibility or insolubility with other ingredients in the formulation, stability, deactivation by pH, and odor.

[04] There are continued needs for new dispersants and new processes for producing pigment dispersions.

STATEMENT OF DISCLOSURE

[05] This disclosure is directed to an aqueous pigment dispersion

comprising:

A) one or more pigments;

B) a polytrimethylene ether glycol having a Mn (number average

molecular weight) in a range of from 100 to 490; and

C) one or more solvents;

wherein said aqueous pigment dispersion comprises in a range of from

20% to 90% of water, percentage based on total weight of said aqueous pigment dispersion.

[06] This disclosure is also directed to a coating composition comprising the aqueous pigment dispersion disclosed herein.

[07] This disclosure is also directed to a process for forming an aqueous pigment dispersion, said process comprising the steps of:

(i) providing one or more pigments;

(ii) mixing said one or more pigments with a polytrimethylene ether glycol having a Mn (number average molecular weight) in a range of from 100 to 490, and optionally one or more solvents; wherein said aqueous pigment dispersion comprises in a range of from 20% to 90% of water, percentage based on total weight of said aqueous pigment dispersion.

DETAILED DESCRIPTION

[08] The features and advantages of the present disclosure will be more readily understood, by those of ordinary skill in the art, from reading the following detailed description. It is to be appreciated that certain features of the disclosure, which are, for clarity, described above and below in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the disclosure that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any sub-combination. In addition, references in the singular may also include the plural (for example, "a" and "an" may refer to one, or one or more) unless the context specifically states otherwise.

[09] The use of numerical values in the various ranges specified in this application, unless expressly indicated otherwise, are stated as

approximations as though the minimum and maximum values within the stated ranges were both proceeded by the word "about." In this manner, slight variations above and below the stated ranges can be used to achieve substantially the same results as values within the ranges. Also, the disclosure of these ranges is intended as a continuous range including every value between the minimum and maximum values.

[10] As used herein:

[11] The term "antimicrobial composition" refers to a composition that comprises one or more antimicrobial agents. An antimicrobial agent can be a molecule, a reagent, a compound, or a mixture, that either kills or retards the growth of one or more microorganisms. The antimicrobial agents can include antibacterial, antiviral, antifungal, antiparisitic agents, or a combination thereof. In one example, the antimicrobial agents can include a natural or synthetic chemical. In another example, the antimicrobial agents can include natural or synthetic chemicals that can be added to products such as foods, cosmetics or pharmaceuticals to prevent spoilage of the products by one or more microorganisms. In yet another example, the antimicrobial agents can prevent the growth of, or kill molds, yeasts, bacteria, or a combination thereof. In yet another example, the bacteria can include Gram-negative bacteria, such as Escherichia coli, Gram-positive bacteria, such as Staphylococcus aureus, or a combination thereof.

[12] The term "microbe", "microbial" or "microorganism" refers to any microorganism including prokaryotes, such as bacteria, either gram-negative or gram-positive, and archaea; eukaryotes, such as yeasts, algae, and mold; and viruses.

[13] The term "coating composition" can include "two-pack coating composition", also known as 2K coating composition, refers to a coating composition having two packages that are stored in separate containers and sealed to increase the shelf life of the coating composition during storage; or a "one-pack coating composition", also known as 1 K coating composition, refers to a coating composition having one package that is stored in one container and sealed to increase the shelf life of the coating composition during storage. The 2K coating composition can comprise a crosslinkable component and a crosslinking component and the two components can be mixed just prior to use to form a pot mix, which has a limited pot life, typically ranging from a few minutes (15 minutes to 45 minutes) to a few hours (4 hours to 8 hours). The 1 K coating composition can be formulated to be cured at certain curing conditions. Examples of such curing conditions can include: radiation, such as UV radiation including UV-A, UV-B, and UV-C radiations, electron beam (e- beam) radiation, infrared (IR) radiation, or lights in visible or invisible wavelengths; moisture, such as water accessible to the coating composition; thermal energy, such as high temperatures; or other chemical or physical conditions.

[14] The term "vehicle", "automotive", "automobile", "automotive vehicle", or

"automobile vehicle" refers to an automobile such as car, van, mini van, bus,

SUV (sports utility vehicle); truck; semi truck; tractor; motorcycle; trailer; ATV (all terrain vehicle); pickup truck; heavy duty mover, such as, bulldozer, mobile crane and earth mover; airplanes; boats; ships; and other modes of transport that are coated with coating compositions.

[15] This disclosure is directed to an aqueous pigment dispersion. The aqueous pigment dispersion can comprise:

[16] A) one or more pigments;

[17] B) a polytrimethylene ether glycol having a Mn (number average molecular weight) in a range of from 100 to 490; and

[18] C) one or more solvents;

[19] wherein said aqueous pigment dispersion comprises in a range of from 20% to 90% of water, percentage based on total weight of said aqueous pigment dispersion.

[20] In one example, the aqueous pigment dispersion can consist essentially of:

[21] A) one or more pigments; [22] B) a polytrimethylene ether glycol having a Mn (number average molecular weight) in a range of from 100 to 490; and

[23] C) one or more solvents;

[24] wherein said aqueous pigment dispersion comprises in a range of from 20% to 90% of water, percentage based on total weight of said aqueous pigment dispersion. The term "consist essentially of means that the aqueous pigment dispersion contains, if any, 5% or less of other materials not listed above. The one or more pigments can comprise hydrophobic pigments. In one example, the one or more pigments can comprise in a range of from 20% to 100% hydrophobic pigments.

[25] The aqueous pigment dispersion can be essentially free from film forming polymers selected from acrylic polymers, polyester polymers, or a combination thereof. The term "essentially free from" means that the aqueous pigment dispersion contains, if any, 5% or less of the film forming polymers. The aqueous pigment dispersion can contain in a range of from 0% to 5% in one example, in a range of from 0% to 2% in another example, in a range of from 0% to 1 % in yet another example, in a range of from 0% to 0.5% in yet another example, or in a range of from 0% to 0.1 % in yet another example, of the film forming polymers. The term "film forming polymer" refers to polymers that can form durable coating films upon drying or curing. The curing can be achieved by reacting with chemical curing agents such as reacting with one or more crosslinking functional groups or exposed to radiations such as ultraviolet (UV) radiations. Typical film forming polymers can include acrylic polymers with or without crosslinkable functional groups, or polyester polymers with or without crosslinkable functional groups.

[26] The aqueous pigment dispersion can comprise in a range of from 0.01 % to 75% of said polytrimethylene ether glycol, percentage based on total weight of said aqueous pigment dispersion. The aqueous pigment dispersion can comprise in a range of from 0.01 % to 75% in one example, 0.1 % to 50% in another example, 0.1 % to 30% in yet another example of the

polytrimethylene ether glycol, percentage based on total weight of said aqueous pigment dispersion.

[27] The polytrimethylene ether glycol can comprise in a range of from 5% to 100% of trimethylene glycol dimers, percentage based on the total weight of the polytrimethylene ether glycol. The polytrimethylene ether glycol can comprise in a range of from 5% to 100% in one example, 5% to 80% in another example, 5% to 50% in yet another example, 5% to 20% in yet another example, of trimethylene glycol dimers.

[28] The trimethylene glycol dimers can be polymerized from bio-derived 1 ,3-propanediol.

[29] The one or more solvents can comprise water, one or more inorganic solvents, one or more organic solvents, or a combination thereof. In one example, the organic solvents can be water soluble or water miscible. The aqueous pigment dispersion can comprise in a range of from 20% to 90% of water, percentage based on total weight of said aqueous pigment dispersion. The aqueous pigment dispersion can comprise in a range of from 20% to 90% in one example, 20% to 80% in another example, 20% to 60% in yet another example, of water.

[30] The one or more pigments can comprise organic pigments, inorganic pigments, metallic pigments, or a combination thereof. Any pigments suitable for coatings, including those effect pigments such as metallic flakes, pearlescent pigments, or a combination thereof, can be suitable. Inorganic and organic colored pigments, metallic flakes and powders, such as, aluminum flake and aluminum powders; special effects pigments, such as, coated mica flakes, coated aluminum flakes colored pigments, or a

combination thereof, can be suitable. Transparent pigments or pigments having the same refractive index as the cured binder can also be suitable. The one or more pigments can comprise in a range of from 20% to 100% in one example, 40% to 100% in another example, 60% to 100% in yet another example, 80% to 100% in yet another example, hydrophobic pigments, percentage based on the total weight of the pigment solids. In a further example, the aqueous pigment dispersion can comprise 100% hydrophobic pigments, percentage based on the total weight of the pigment solids. The hydrophobic pigments can include pigments having hydrophobic surface treatments. Examples of commercial hydrophobic pigments can include: Carbon Black Raven 5000 Ultrall Powder from Columbian Chemical (1800 West Oak Commons Court, Marietta, Georgia 30062-2253); DPP Red BO from BASF (100 Campus Drive, Florham Park, NJ 07932); and HOSTAPERM BLUE BT-617-D from Clariant (4000 Monroe Rd., Charlotte, NC 28205). Other hydrophobic pigments known to or developed by those skilled in the art can also be suitable.

[31] The aqueous pigment dispersion can further comprise one or more antimicrobial agents, wherein the antimicrobial agents and the

polytrimethylene ether glycol are at a mixing ratio in a range of from 0.1 :100 to 100:0.1 . Examples of antimicrobial agent can include parabens, esters of p- benzoic acid, formaldehyde releasers, isothiazolinones, organic acids, organic alcohols, metals, metal particles or metal salts, such as copper quinolinolate or silver nano-particles, or a combination thereof. Any of the aforementioned antimicrobial agents or a combination thereof can be suitable.

[32] The polytrimethylene ether glycol can be prepared by an acid- catalyzed polycondensation of 1 ,3-propanediol (herein referred to as "PDO"), which is also synonymous to "trimethylene glycol", such as described in U.S. Patent Nos. 6,977,291 and 6,720,459. The polytrimethylene ether glycol can also be prepared by a ring opening polymerization of a cyclic ether, oxetane, such as described in J. Polymer Sci., Polymer Chemistry Ed. 28, 449 to 444 (1985). The polycondensation of 1 ,3-propanediol is preferred over the use of oxetane since the diol is a less hazardous, stable, low cost, commercially available material and can be prepared by use of petro chemical feed-stocks or renewable resources.

[33] A bio-route via fermentation of renewable resources can be used to obtain the 1 ,3-propanediol (PDO). One example of the renewable resources is corn since it is readily available and has a high rate of conversion to 1 ,3- propanediol and can be genetically modified to improve yields to the 1 ,3- propanediol. Examples of typical bio-route can include those described in US Patent No. 5, 686,276, US Patent No. 5,633,362 and US Patent No.

5,821 ,092. The 1 ,3-propanediol obtained from the renewable source and the coating compositions therefrom can be distinguished from their petrochemical derived counterparts on the basis of radiocarbon dating such as fraction of modern carbon (f_M), also know as ¹⁴C (†M) and dual carbon-isotopic

fingerprinting ¹³C/¹²C such as the one known as 5¹³C. The fraction of modern carbon f_M is defined by National Institute of Standards and Technology (NIST) Standard Reference Materials (RFMs) 4990B and 4990C. [34] The radiocarbon dating method usefully distinguishes chemically- identical materials, and apportions carbon in the polymer by source (and possibly year) of growth of the biospheric (plant) component. The isotopes, ¹⁴C and ¹³C, bring complementary information to this problem. The

radiocarbon dating isotope (¹⁴C), with its nuclear half life of 5730 years, clearly allows one to apportion specimen carbon between fossil ("dead") and biospheric ("alive") feedstocks (Currie, L. A. "Source Apportionment of Atmospheric Particles," Characterization of Environmental Particles, J. Buffle and H. P. van Leeuwen, Eds., 1 of Vol. I of the lUPAC Environmental

Analytical Chemistry Series (Lewis Publishers, Inc) (1992) 3-74). The basic assumption in radiocarbon dating is that the constancy of ¹⁴C concentration in the atmosphere leads to the constancy of ¹⁴C in living organisms. When dealing with an isolated sample, the age of a sample can be deduced approximately by the relationship

f=(-5730/0.693)/rc(A/Ao)

[35] where f=age, 5730 years is the half-life of radiocarbon, and A and A₀ are the specific ¹⁴C activity of the sample and of the modern standard, respectively (Hsieh, Y., Soil Sci. Soc. Am J., 56, 460, (1992)). However, because of atmospheric nuclear testing since 1950 and the burning of fossil fuel since 1850, ¹⁴C has acquired a second, geochemical time characteristic. Its concentration in atmospheric CO2, and hence in the living biosphere, approximately doubled at the peak of nuclear testing, in the mid-1960s. It has since been gradually returning to the steady-state cosmogenic (atmospheric) baseline isotope rate (¹⁴C/¹²C) of ca. 1 .2*10^"12, with an approximate relaxation "half-life" of 7-10 years. (This latter half-life must not be taken literally; rather, one must use the detailed atmospheric nuclear input/decay function to trace the variation of atmospheric and biospheric ¹⁴C since the onset of the nuclear age.) It is this latter biospheric ¹⁴C time characteristic that holds out the promise of annual dating of recent biospheric carbon. ¹⁴C can be measured by accelerator mass spectrometry (AMS), with results given in units of "fraction of modern carbon" (f_M).†M is defined by National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) 4990B and 4990C, known as oxalic acids standards HOxl and HOxll, respectively. The fundamental definition relates to 0.95 times the ¹⁴C/¹²C isotope ratio HOxl (referenced to AD 1950). This is roughly equivalent to decay-corrected pre-lndustrial Revolution wood. For the current living biosphere, such as current plant materials or components derived from current plant materials, herein referred to as new carbon materials, fM^s1 .1 .

[36] The stable carbon isotope ratio (¹³C/¹²C) provides a complementary route to source discrimination and apportionment. The ¹³C/¹²C ratio in a given biosourced material is a consequence of the ¹³C/¹²C ratio in atmospheric carbon dioxide at the time the carbon dioxide is fixed and also reflects the precise metabolic pathway. Regional variations also occur. Petroleum, C3 plants (the broadleaf), C₄ plants (the grasses), and marine carbonates all show significant differences in ¹³C/¹²C and the corresponding 5¹³C values. Furthermore, lipid matter of C3 and C₄ plants analyze differently than materials derived from the carbohydrate components of the same plants as a

consequence of the metabolic pathway. Within the precision of measurement, ¹³C shows large variations due to isotopic fractionation effects, the most significant of which for the present disclosure is the photosynthetic

mechanism. The major cause of differences in the carbon isotope ratio in plants is closely associated with differences in the pathway of photosynthetic carbon metabolism in the plants, particularly the reaction occurring during the primary carboxylation, i.e., the initial fixation of atmospheric CO₂. Two large classes of vegetation are those that incorporate the "C3" (or Calvin-Benson) photosynthetic cycle and those that incorporate the "C₄" (or Hatch-Slack) photosynthetic cycle. C3 plants, such as hardwoods and conifers, are dominant in the temperate climate zones. In C₃ plants, the primary CO₂ fixation or carboxylation reaction involves the enzyme ribulose-1 ,5- diphosphate carboxylase and the first stable product is a 3-carbon compound. C₄ plants, on the other hand, include such plants as tropical grasses, corn and sugar cane. In C plants, an additional carboxylation reaction involving another enzyme, phosphoenol-pyruvate carboxylase, is the primary

carboxylation reaction. The first stable carbon compound is a 4-carbon acid, which is subsequently decarboxylated. The CO2 thus released is refixed by the C₃ cycle.

[37] Both C₄ and C3 plants exhibit a range of ¹³C/¹²C isotopic ratios, but typical values are ca. -10 to -14 per mil (C₄) and -21 to -26 per mil (C3) (Weber et al., J. Agric. Food Chem., 45, 2942 (1997)). Coal and petroleum fall generally in this latter range. The ¹³C measurement scale was originally defined by a zero set by pee dee belemnite (herein referred to as PDB) limestone, where values are given in parts per thousand deviations from this material. The "5¹³C" values are in parts per thousand (per mil), abbreviated as %o, and are calculated as follows:

(¹³C / ¹²C)sample - (¹³ C / ¹²C)standard

0^C - C Wstandard °°

[38] Since the PDB reference material (RM) has been exhausted, a series of alternative RMs have been developed in cooperation with the IAEA, USGS, NIST, and other selected international isotope laboratories. Notations for the per mil deviations from PDB is 5¹³C. Measurements are made on CO2 by high precision stable ratio mass spectrometry (IRMS) on molecular ions of masses 44, 45 and 46.

[39] Bio-derived 1 ,3-propanediol, and resulted compositions, such as polytrimethylene ether glycol, comprising bio-derived 1 ,3-propanediol, therefore, can be completely distinguished from their petrochemical derived counterparts on the basis of ¹⁴C (†M) and dual carbon-isotopic fingerprinting, indicating new compositions of matter. The ability to distinguish these products is beneficial in tracking these materials in commerce. For example, products comprising both "new carbon materials" and "old carbon materials" (for example, carbon materials from petroleum products) can be distinguished from products made only of "old carbon materials" by isotope profiles.

[40] The polytrimethylene ether glycol can have a Mn in a range of from 100 to 650. In one example, the polytrimethylene ether glycol can have a Mn in a range of from 100 to 490. In another example, the polytrimethylene ether glycol can have a Mn in a range of from 200 to 490. In yet another example, the polytrimethylene ether glycol can have a Mn in a range of from 250 to 490. In yet another example, the polytrimethylene ether glycol can have a Mn in a range of from 100 to 310. In yet another example, the polytrimethylene ether glycol can have a Mn in a range of from 100 to 250. The polytrimethylene ether glycol suitable for this disclosure need to be within the aforementioned range of Mn that can be controlled by polymerization process to have polymers with desired range of Mn, fractionation of polymers to obtain polymers having desired Mn distribution, or a combination thereof. The polymerization can be controlled, for example by polymerization timing, reaction temperature, reaction pressure, or a combination thereof, to produce polymers having Mn within the aforementioned range.

[41] The polytrimethylene ether glycol can be fractionated or unfractionated. The unfractionated polytrimethylene ether glycol can have un-polymerized monomers and polymerized oligomers or polymers, such as dimers, trimer, tetramers, and pentamers. In one example, the unfractionated

polytrimethylene ether glycol can have, such as, 1 ,3-propanediol (PDO) monomers, dimers (also referred to as "trimethylene glycol dimers", "1 ,3- propanediol dimers", or "di(1 ,3-propanediol)"), trimers (also referred to as "trimethylene glycol trimers"), tetramers (also referred to as "trimethylene glycol tetramers"), pentamers (also referred to as "trimethylene glycol pentamers"), hexamers (also referred to as "trimethylene glycol hexamers") and heptamers (also referred to as "trimethylene glycol heptamers"). The fractionated polytrimethylene ether glycol can have different contents based on fractionation. In one example, the fractionated polytrimethylene ether glycol can have PDO monomers, dimers, trimers, tetramers, and pentamers. In another example, the fractionated polytrimethylene ether glycol can have PDO dimers, trimers, tetramers, and pentamers. In yet another example, the fractionated polytrimethylene ether glycol can have trimers, tetramers, pentamers and hexamers. In further example, the fractionated

polytrimethylene ether glycol can have tetramers, pentamers, hexamers and heptamers. The fractionated polytrimethylene ether glycol can comprise in a range of from 10% to 100% of trimethylene glycol dimers in one example, 20% to 100% of trimethylene glycol dimers in another example, 30% to 100% of trimethylene glycol dimers in yet another example, 40% to 100% of trimethylene glycol dimers in yet another example, in a range of from 50% to 100% of trimethylene glycol dimers in yet another example, all percentage based on the total weight of the polytrimethylene ether glycol.

[42] The polytrimethylene ether glycol can include copolymers of

polytrimethylene ether glycol that can also be suitable for the coating composition of this disclosure. Examples of such suitable copolymers of polytrimethylene ether glycol can be prepared by copolymerizing 1 ,3- propanediol with another diol, such as, ethane diol, 1 ,2-propanediol, hexane diol, 2-methyl-1 ,3-propanediol, 2,2-dimethyl-1 ,3-propanediol, trimethylol propane and pentaerythritol. In one example, the copolymers of

polytrimethylene ether glycol can be polymerized from monomers have 1 ,3- propanediol in a range of from 50% to 99%. In another example, the copolymers of polytrimethylene ether glycol can be polymerized from monomers have 1 ,3-propanediol in a range of from 60% to 99%. In yet another example, the copolymers of polytrimethylene ether glycol can be polymerized from monomers have 1 ,3-propanediol in a range of from 70% to 99%.

[43] The polytrimethylene ether glycol useful in the compositions and methods disclosed herein can contain small amounts of other repeat units, for example, from aliphatic or aromatic diacids or diesters, such as disclosed in U.S. Pat. No. 6,608,168. This type of trimethylene ether glycol oligomer can also be called a "random polytrimethylene ether ester", and can be prepared by polycondensation of 1 ,3-propanediol reactant and about 10 to about 0.1 mole % of aliphatic or aromatic diacid or esters thereof, such as terephthalic acid, isophthalic acid, bibenzoic acid, naphthalic acid, bis(p- carboxyphenyl)methane, 1 ,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene dicarboxylic acid, 4,4'-sulfonyl dibenzoic acid, p-(hydroxyethoxy)benzoic acid, and combinations thereof, and dimethyl terephthalate, bibenzoate, isophthlate, naphthalate and phthalate; and combinations thereof. Of these, terephthalic acid, dimethyl terephthalate and dimethyl isophthalate are preferred.

[44] The polytrimethylene ether polymers with functional groups other than hydroxyls end groups can also be used. Examples of polytrimethylene ether glycol oligomers with amine and ester end functional groups can include those disclosed in U.S. Patent Publication No. 2008/0108845 with Serial No.

12/704867.

[45] The polytrimethylene ether glycol can have in a range of from 5% to 100% of trimethylene glycol dimers, percentage based on the total weight of the polytrimethylene ether glycol. The polytrimethylene ether glycol can have in a range of from 5% to 100% of trimethylene glycol dimers in one example, in a range of from 10% to 100% of trimethylene glycol dimers in another example, in a range of from 20% to 100% of trimethylene glycol dimers in another example, and in a range of from 30% to 100% of trimethylene glycol dimers in a yet further example, or in a range of from 50% to 100% of trimethylene glycol dimers in yet another example, all percentage based on the total weight of the polytrimethylene ether glycol. Fractionation, distillation or other separation or purification techniques can be used to produce polytrimethylene ether glycol having desired contents of dimers, trimers, or tetramers, etc. Fractionation, distillation or other separation or purification techniques can also be used to remove undesired contents from

polytrimethylene ether glycol.

[46] The polytrimethylene ether glycol can be polymerized from bio-derived 1 ,3-propanediol. The polytrimethylene ether glycol can be polymerized from monomers comprising in a range of from 10% to 100% of bio-derived 1 ,3- propanediol in one example, in a range of from 20% to 100% of bio-derived 1 ,3-propanediol in another example, in a range of from 40% to 100% of bio- derived 1 ,3-propanediol in yet another example, in a range of from 60% to 100% of bio-derived 1 ,3-propanediol in yet another example, in a range of from 80% to 100% of bio-derived 1 ,3-propanediol in yet another example, and 100% of bio-derived 1 ,3-propanediol in a further example, all percentage based on the total weight of monomers used for polymerizing the

polytrimethylene ether glycol.

[47] The aqueous pigment dispersion can further comprise one or more polymers selected from one or more acrylic polymers, one or more polyester polymers, one or more polyesterurethanes, one or more polyetherurethanes, one or more poly(meth)acrylamides, one or more polyepoxides, one or more polycarbonates, or a combination thereof. The aqueous pigment dispersion can also be mixed with one or more components to form a coating

composition. Typical acrylic polymers, polyester polymers,

polyesterurethanes, polyetherurethanes, poly(meth)acrylamides,

polyepoxides, or polycarbonates that are suitable for coating compositions can be suitable.

[48] The aqueous pigment dispersion can be essentially free from milling media, wetting agent, surfactant, emulsion agent, or a combination thereof. The polytrimethylene ether glycol disclosed herein can function as a pigment dispersant and a wetting agent. Typically, milling media have to be removed after pigment dispersions are formed. The aqueous pigment dispersion disclosed herein can be advantageous in that no need to add or remove such milling media. This can be particularly useful if any of the milling media, wetting agent, surfactant, or emulsion agent could have undesired effect on properties of the dispersion or coating compositions. The term "essentially free from" used herein means the dispersion can have 5% or less the aforementioned wetting agent, surfactant, emulsion agent, or a combination thereof, percentage based on the total weight of the aqueous pigment dispersion. The aqueous pigment dispersion can comprise in a range of from 0% to 5% in one example, in a range of from 0% to 1 % in another example, in a range of from 0% to 0.1 % in yet another example, in a range of from 0% to 0.01 % in yet another example, or in a range of from 0% to 0.001 % in a further example, of the above mentioned materials.

[49] This disclosure is also directed to a coating composition comprising the aqueous pigment dispersion disclosed herein.

[50] The coating composition can be a 2K or a 1 K coating composition. The coating composition can be a waterborne coating composition and can comprise in a range of from 20% to 80% of water, percentage based on the total weight of said waterborne coating composition. The waterborne coating composition can comprise in a range of from 20% to 80% of water in one example, in a range of from 40% to 80% of water in another example, percentage based on total weight of the waterborne coating composition. The waterborne coating composition can also comprise one or more organic solvents or one or more reactive diluents. Although water miscible organic solvent can be preferred, any typical organic solvents can be used to form the coating composition of this disclosure. The waterborne coating composition can comprise one or more detergents or emulsion agents.

[51] The waterborne coating composition of this disclosure can be used as a primer, a basecoat, a top coat, or a clearcoat. It can also be used as a single layer coat that can function as a primer, a basecoat and a top coat.

[52] The waterborne coating composition can further comprise one or more solvents, ultraviolet light stabilizers, ultraviolet light absorbers, antioxidants, hindered amine light stabilizers, leveling agents, rheological agents, thickeners, antifoaming agents, wetting agents, catalysts, or a combination thereof.

[53] This disclosure is further directed to an antimicrobial coating layer formed from the waterborne coating composition disclosed herein, wherein the antimicrobial coating layer comprises polytrimethylene glycol dimers polymerized from bio-derived 1 ,3-propanediol.

[54] This disclosure is further directed to a substrate coated with the aforementioned antimicrobial coating layer. The substrate can be selected from wood, concrete, metal, plastic, glass, paper, fiber, gypsum plaster, cement, stone, rock, brick, masonry, or a combination thereof, or other man made or natural materials. The substrate can be a vehicle, such as the aforementioned vehicles or automobiles; home appliance, such as

refrigerators, washing machines, dishwashers, microwave ovens, cooking and baking ovens; electronic appliances, such as television sets, computers, electronic game sets, audio and video equipments; recreational equipments, such as bicycles, ski equipments, all terrain vehicles; and home or office furniture, such as tables, file cabinets. The substrate can also have one or more existing coating layers. The antimicrobial coating layer of this disclosure can be the out most coating layer of the substrate.

[55] This disclosure is further directed to a process for forming an aqueous pigment dispersion. The process can comprise the steps of:

[56] (i) providing one or more pigments;

[57] (ii) mixing said one or more pigments with a polytrimethylene ether glycol having a Mn (number average molecular weight) in a range of from 100 to 490, and optionally one or more solvents;

[58] wherein said aqueous pigment dispersion comprises in a range of from 20% to 90% of water, percentage based on total weight of said aqueous pigment dispersion.

[59] The aqueous pigment dispersion can be essentially free from wetting agent, surfactant, emulsion agent, or a combination thereof. The aqueous pigment dispersion can be formed by mixing, shaking, agitating, stirring, or a combination thereof. [60] The process can further comprise the step of milling said one or more pigments in said polytrimethylene ether glycol. The process can also further comprise the step of milling said one or more pigments in said

polytrimethylene ether glycol in the presence of one or more milling media, said one or more solvents, or a combination thereof. Any milling media suitable for pigment dispersion can be suitable.

[61] In one example, the milling can comprise the step of directing two high speed streams of the mixture formed in step (ii) at each other from two opposite directions forcing the collision of the two streams. The collision energy can lead to the production of pigment dispersion. In another example, the pigments can be milled in a mechanical miller, such as a high speed rotary miller or a grinder. In any of the aforementioned examples, the milling can be done in the presence of one or more milling media, the one or more solvents, or a combination thereof.

[62] One advantage of the aqueous pigment dispersion of this disclosure is that it contains a component that is derived from a renewable resource.

Another advantage is that the aqueous pigment dispersion can be

antimicrobial that can inhibit microbial growth in the dispersion. Yet another advantage is that the antimicrobial agent, particularly the polytrimethylene ether glycol as disclosed herein, of the aqueous pigment dispersion is from a renewable resource and can be readily degradable once entering the environment.

[63] Typically, aqueous pigment dispersions can be prone to microbe growth. That would shorten the storage time of the aqueous pigment dispersions especially when a single container of the dispersion is repeatedly used and stored. The aqueous pigment dispersion of this disclosure can provide improved storage time due to antimicrobial effects of the

polytrimethylene ether glycol having a Mn (number average molecular weight) in a range of from 100 to 650, preferred in a range of from 100 to 490, particularly the trimethylene glycol oligomers, such as trimethylene glycol dimers. The aqueous pigment dispersion can be an antimicrobial composition that can inhibit the growth of one or more bacteria. In one example, the bacteria can include Gram-negative bacteria, such as Escherichia coli, Gram- positive bacteria, such as Staphylococcus aureus, or a combination thereof. The polytrimethylene ether glycol disclosed herein, particularly, the

trimethylene glycol dimers, can be used as both a pigment dispersant and an antimicrobial agent.

[64] The present invention can be further defined in the following Examples. It should be understood that these Examples, while indicating preferred embodiments of the invention, are given by way of illustration only. From the above discussion and these Examples, one skilled in the art can ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various uses and conditions.

Testing Procedures

[65] Viscosity - (in Krebs unit, or "KU")) - determined according to ASTM D 562 Method D.

[66] Pigment wetting - determined by mixing 0.1 gram of pigments in 20 grams of water in a glass vial and shaking the mixture for a minute. If no pigment wetting occurs, the pigments stay at the air/water interface. If some pigments go into the water phase, the pigment wetting is determined as "marginal". If all the pigments go into the water phase, the pigment wetting is determined as "good".

[67] Molecular weight and hydroxyl number of the polytrimethylene ether diol are determined according to ASTM E222.

[68] Molecular weights Mw and Mn and the polydispersity (Mw/Mn) of the acrylic polymer and other polymers are determined by GPC (Gel Permeation Chromatography) using polystyrene standards and tetrahydrofuran as the solvent.

[69] Assay for antimicrobial activity - The Time-Kill test can be performed according to ASTM E2315 - 03. The results can be expressed as percent of reduction of the testing microbe: 0% reduction representing no antimicrobial activity and 100% reduction representing complete reduction of the microbes tested.

[70] In the following examples, all parts and percentages are on a weight basis unless otherwise indicated. "Mw" weight average molecular weight and "Mn" means number average molecular weight. "PBW" means parts by weight. EXAMPLES

Procedure 1 : Preparation of Low Molecular Weight Polytrimethylene

Ether Glycol

Twelve kilogram (kg) renewably sourced 1 ,3-propanediol (PDO) monomers commercially available from DuPont Tate & Lyle Bioproducts, Wilmington, DE, USA, were added to a 20L glass reactor equipped with a condenser and an agitator. The glass reactor was purged with N₂ at the rate 3L/min. Triflic acid (trifluoromethanesulfonic acid) was added into the reactor to a final concentration of 0.1 wt % and the mixture was heated up to 180°C with agitation set to 200 RPM to allow the acid-catalyzed polycondensation to proceed. The reaction volatiles were condensed in the condenser and the crude polymer product was retained in the reactor. Crude polymer samples were taken periodically for color and molecular weight analysis. Once the desired Mn was achieved, the polymerization was terminated by turning the heat down. An antioxidant, BHT (Butylated hydroxyl toluene), available from Aldrich, St. Louis, MO, USA, was added to the crude polymer to a final concentration about 200 ppm. The polymer was neutralized by treating the crude polymer with XUS ion exchange resin, available from Dow Chemical, Midland, Michigan, USA, in 2 stages. In the first stage, 2 weight parts of the XUS ion exchange resin and 98 weight parts of the crude polymer were mixed at a temperature of about 105°C for about 1 hour. In the second stage, an additional 2 weight parts of the XUS ion exchange resin was added to the crude polymer and further mixed for additional 3 hours. Neutralization was conducted under sub-surface nitrogen sparging of 5 L/min and a mixing speed of 200 RPM. The product was filtered to remove the ion exchange resin.

Filtration was done at 60°C. Once the product was free of solids, it was dried by heating to about 95°C, with sub-surface nitrogen sparging of about 10 L/min and mixing speed of 150 RPM.

The product had about 2.7% of 1 ,3-propanediol monomer, 15% 1 ,3- propanediol dimer (also referred to as "trimethylene glycol dinner"), 80% or more of other oligomers of 1 ,3-propanediol including trimer, tetramer, pentamer, hexamer, heptamer, etc., percentage based on the total weight of the product. Procedure 2: Fractionation of Low Molecular Weight Polytrimethylene

Ether Glycol

To a 500 ml_, 3-neck round bottom flask equipped with a mechanical stirrer, a distillation adapter, a condenser and a graduated distillation receiver, 367.6 g of polytrimethylene ether glycol having number average molecular weight of 250, as produced in Procedure 1 , was added. The polymer was heated with a proportional integral derivative (PID) controller connected to a heating mantle and thermocouple. The controller was set to maintain a batch temperature of 50 °C at a power setting of 50% (300 ml_ - 2L). The fraction was collected from the overhead collection path by passing polymer product through a short path distillation unit at 100 mL/min, 130°C, 1 .38 torr. The fractionated polymer product was analyzed by GC and contained 24.2% of 1 ,3-propanediol (PDO) monomer, 61 .7% of 1 ,3-propanediol dimer (also referred to as "trimethylene glycol dimer"), and 15.1 % of other oligomers of the 1 ,3-propanediol, percentage based on the total weight of the polymer product.

Calculated molecular weights (Mn) for the 1 ,3-propanediol oligomers are shown in Table 1 . Table 1. Molecular weight (Mn) of 1 ,3-propanediol oligomers.

EXAMPLE 1

Pigment dispersions of Example 1 (Exp 1 ) and Comparative

dispersions 1 (Comp 1 ) and 2 (Comp 2) were prepared according to Table 2.

Pigment wetting was assessed for the dispersions according to the Testing Procedures. The results are shown in Table 2. Table 2. Pigment Dispersions (Weight Parts).

Unfractionated polytrimethylene ether glycol was from Procedure 1.

Poly(ethylene glycol), MW 300, was from was from Sigma Aldrich, St. Louis, MO, USA. Cat No. 202371.

The pigment used was hydrophobic red pigment Cinilex® DPP Red SR1 C, available from Cinic Chemicals America, LLC, Pittsburgh, PA, under respective trademarks.

Claims

CLAIMS What is claimed is:

1 . An aqueous pigment dispersion comprising:

A) one or more pigments;

B) a polytrimethylene ether glycol having a Mn (number average molecular weight) in a range of from 100 to 490; and C) one or more solvents;

wherein said aqueous pigment dispersion comprises in a range of from 20% to 90% of water, percentage based on total weight of said aqueous pigment dispersion.

2. The aqueous pigment dispersion of claim 1 , wherein the polytrimethylene ether glycol has a Mn in a range of from 100 to 310.

3. The aqueous pigment dispersion of claim 1 , wherein said aqueous

pigment dispersion comprises in a range of from 0.01 % to 75% of said polytrimethylene ether glycol, percentage based on total weight of said aqueous pigment dispersion.

4. The aqueous pigment dispersion of claim 1 , wherein said aqueous

pigment dispersion comprises in a range of from 0.1 % to 50% of said polytrimethylene ether glycol, percentage based on total weight of said aqueous pigment dispersion.

5. The aqueous pigment dispersion of claim 1 , wherein said

polytrimethylene ether glycol comprises in a range of from 5% to 100% of trimethylene glycol dimers, percentage based on the total weight of the polytrimethylene ether glycol.

6. The aqueous pigment dispersion of claim 5, wherein said trimethylene glycol dimers is polymerized from bio-derived 1 ,3-propanediol.

7. The aqueous pigment dispersion of claim 1 , wherein said aqueous pigment dispersion comprises in a range of from 20% to 90% of water, percentage based on total weight of said aqueous pigment dispersion.

8. The aqueous pigment dispersion of claim 1 , wherein the polytrimethylene ether glycol is polymerized from bio-derived 1 ,3-propanediol.

9. The aqueous pigment dispersion of claim 1 , wherein said one or more pigments comprise organic pigments, inorganic pigments, metallic pigments, or a combination thereof.

10. The aqueous pigment dispersion of claim 1 , wherein said one or more pigments comprise in a range of from 20% to 100% hydrophobic pigments, percentage based on the total weight of the pigment solids.

1 1 . The aqueous pigment dispersion of claim 1 further comprising one or more antimicrobial agents, wherein said antimicrobial agents and said polytrimethylene ether glycol are at a mixing ratio in a range of from 0.1 :100 to 100:0.1 .

12. The aqueous pigment dispersion of claim 1 further comprising one or more polymers selected from one or more acrylic polymers, one or more polyester polymers, one or more polyesterurethanes, one or more polyetherurethanes, one or more poly(meth)acrylamides, one or more polyepoxides, one or more polycarbonates, or a combination thereof.

13. The aqueous pigment dispersion of claim 1 , wherein said aqueous

pigment dispersion is essentially free from film forming polymers selected from acrylic polymers, polyester polymers, or a combination thereof.

14. The aqueous pigment dispersion of claim 1 , wherein said aqueous

pigment dispersion is essentially free from wetting agent, surfactant, emulsion agent, or a combination thereof.

15. A coating composition comprising the aqueous pigment dispersion of claim 1 .

16. The coating composition of claim 15, wherein said coating composition is a waterborne coating composition and comprises in a range of from 20% to 80% of water, percentage based on the total weight of said

waterborne coating composition.

17. An antimicrobial coating layer formed over a substrate from the

waterborne coating composition of claim 16, wherein said antimicrobial coating layer comprises polytrimethylene glycol dimers polymerized from bio-derived 1 ,3-propanediol.

18. A substrate coated with the antimicrobial coating layer of claim 17,

wherein said substrate is selected from wood, concrete, metal, plastic, glass, paper, fiber, gypsum plaster, cement, stone, rock, brick, masonry, or a combination thereof.

19. A process for forming an aqueous pigment dispersion, said process

comprising the steps of:

(i) providing one or more pigments;

20. The process of claim 19 further comprising the step of milling said one or more pigments in said polytrimethylene ether glycol. The process of claim 19, wherein said aqueous pigment dispersion essentially free from wetting agent, surfactant, emulsion agent, or a combination thereof.

The process of claim 19 further comprising the step of milling said one or more pigments in said polytrimethylene ether glycol in the presence of one or more milling media, said one or more solvents, or a combination thereof.