Polyester aqueous dispersion

Abstract

The aqueous dispersion includes water, a dispersant, a polyamine having three or more amino groups, and a plurality of particles of a polyester, the polyester being aliphatic and having a glass transition temperature of 50° C. or less as measured in accordance with ASTM E1356-08.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to aqueous dispersions, and more particularly to aqueous dispersions comprising polyesters and polyamines.

[0002] (Introduction) Films and coatings are applied to a variety of articles, such as seeds, paper products, and crop additives. Traditional materials used to form films and coatings on these articles have included polymer latexes, such as acrylates and polyvinyl acetates. Typically, an aqueous dispersion of the film-forming material is applied to the article and then cured to form a film. In recent years, such films have come under increasing regulatory pressure due to the perceived lack of biodegradability and other environmental concerns posed by the film's components.

[0003] Achieving the same level of performance in films and coatings as that achieved with conventional materials but using readily biodegradable materials is challenging. Specifically, achieving comparable results with biodegradable materials in terms of water resistance is challenging. The water resistance of a film is typically measured in terms of the turbidity generated by the film when immersed in water (for films that sometimes contain small amounts of pigment) and based on a visual evaluation of the film after exposure to water. Achieving a turbidity value of 50 or less as measured according to the Turbidity Test and a visual rating of 5 or more as measured according to the Visual Water Resistance Test typically indicates that the film exhibits effective water resistance. A further concern with using readily biodegradable materials is the potential need for additional manufacturing steps. Some biodegradable materials may require a high-temperature curing step, greater than 50°C, to become water-resistant and / or form an adequate barrier. These high curing temperatures can be harmful to the article on which the film is formed. Eliminating the need for a high-temperature curing step would be advantageous in terms of cost and manufacturing complexity.

[0004] Despite the complexities encountered in creating biodegradable films, some attempts have been made. For example, World Intellectual Property Organization Publication No. 2022003195A1 ("'195 Publication") discloses the use of biopolymer film dispersions strengthened by the use of crosslinking agents. The biopolymer in the '195 Publication may be a polyester, and the dispersing agent used for the biopolymer is polyvinyl alcohol. The crosslinking agent contains a difunctional amine and acts to crosslink the polyvinyl alcohol to form a film by using dicarboxylic acid moieties, but requires high temperatures of about 130°C to cure the film.

[0005] In view of the above, it would be surprising to find an aqueous dispersion capable of producing a film that achieves a turbidity value of 50 or less as measured according to the Turbidity Test and a visual rating of 5 or greater as measured according to the Visual Water Fastness Test, without requiring a curing step above 50°C. Summary of the Invention

[0006] The inventors of the present disclosure have discovered aqueous dispersions capable of producing films that achieve turbidity values ​​of 50 or less as measured according to the Turbidity Test and visual ratings of 5 or greater as measured according to the Visual Water Fastness Test, without the need for a curing step above 50°C.

[0007] The present disclosure is the result of the discovery that aqueous dispersions of polyester particles can form water-resistant, biodegradable films by directly crosslinking the polyester rather than the dispersant (i.e., polyvinyl alcohol). To achieve this direct crosslinking of the polyester particles, the polyester should have a glass transition temperature ("Tg") of 50°C or less, and the crosslinking agent is a polyamine with three or more amino groups. Without being bound by theory, it is believed that polyesters with a Tg greater than 50°C do not exhibit sufficient chain mobility to provide bonding sites for the crosslinking agent to react. In other words, the steric hindrance of polyesters with a Tg greater than 50°C is too great for the crosslinking agent to effectively bond the polyester particles together. Furthermore, the crosslinking agent used must have enough amino functionality to not only overcome the steric hindrance of the polyester, but also to bond two or more polyester particles together. It has been discovered that, even with the appropriate polyester, two amino functional groups alone are not sufficient to achieve the desired turbidity and visual assessment goals. Rather, by combining a polyester with a Tg of 50°C or less with a polyamine having three or more amino groups, a film can be formed that not only meets but also exceeds the turbidity and visual evaluation goals. Furthermore, by selecting a polyester with a Tg of 50°C or less, there will be sufficient chain mobility for bonding, so the film does not require a heating step for cure.

[0008] According to a first aspect of the present disclosure, an aqueous dispersion includes water, a dispersant, a polyamine having three or more amino groups, and a plurality of particles of a polyester, wherein the polyester is aliphatic and has a glass transition temperature of 50° C. or less, measured according to ASTM E1356-08.

[0009] According to a second aspect of the present disclosure, the dispersant is selected from the group consisting of polyvinyl alcohol, fatty alcohol ethoxylates, ethylene oxide / propylene oxide block copolymers, salts of fatty acids, and mixtures thereof.

[0010] According to a third feature of the present disclosure, the polyester particles have a volume average diameter of 100 nm to 1500 nm measured according to a particle size test.

[0011] According to a fourth feature of the present disclosure, the aqueous dispersion includes 1 wt % to 20 wt % of a dispersant based on the total weight of the aqueous dispersion, 0.05 wt % to 5 wt % of a polyamine based on the total weight of the aqueous dispersion, and 20 wt % to 60 wt % of polyester particles based on the total weight of the aqueous dispersion.

[0012] According to a fifth aspect of the present disclosure, the polyamine is selected from the group consisting of polyethyleneimine, chitosan, diethylenetriamine, triethylenetetramine, and combinations thereof.

[0013] According to a sixth aspect of the present disclosure, the aqueous dispersion comprises 0.1 wt % to 1.0 wt % of a polyamine based on the total weight of the aqueous dispersion.

[0014] According to a seventh feature of the present disclosure, the glass transition temperature is -70°C to 20°C.

[0015] According to an eighth aspect of the present disclosure, the polyester is selected from the group consisting of polycaprolactone, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), polyhydroxyalkanoate, polybutylene adipate terephthalate, polybutylene succinate, polybutylene succinate adipate, poly(3-hydroxybutyrate), and mixtures thereof.

[0016] According to a ninth feature of the present disclosure, a method for forming a film includes the steps of applying the aqueous dispersion according to any one of claims 1 to 8 to an article, and curing the aqueous dispersion at a temperature of 10°C to 50°C to form a film.

[0017] According to a tenth aspect of the present disclosure, the article is selected from the group consisting of a seed, a paper article, and a crop additive. DETAILED DESCRIPTION OF THE INVENTION

[0018] As used herein, the term "and / or," when used in a list of two or more items, means that any one of the listed items can be used by itself, or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination, or A, B, and C in combination.

[0019] Unless otherwise stated, all ranges are inclusive of the endpoints.

[0020] As used herein, the term weight percent ("wt %") refers to the weight percentage that a component represents of the total weight of the glycol composition, unless otherwise specified.

[0021] As used herein, Chemical Abstract Services Registry Number ("CAS Number") refers to the unique numeric identifier last assigned to a chemical compound by the Chemical Abstract Service as of the priority date of this document.

[0022] Unless otherwise specified, all molecular weight measurements herein are determined by gas chromatography with mass spectrometry detection, as described below.

[0023] aqueous dispersion The present disclosure relates to aqueous dispersions and resulting films formed therefrom. The aqueous dispersions include water, a dispersant, a polyamine, and a polyester. The aqueous dispersions can be used to form films on surfaces and articles.

[0024] The aqueous dispersion may have 15% to 80% by weight of water, based on the total weight of the aqueous dispersion. For example, the aqueous dispersion may contain 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, or 75% or more by weight, and at the same time, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, or 20% or less by weight of water, based on the total weight of the aqueous composition.

[0025] Aqueous dispersions can be formed by various processes recognized by those skilled in the art. For example, a polyester can be combined with one or more dispersants and then continuously melt-mixed with water in an extruder (e.g., by the BLUEWAVE™ process) to form a melt-mixed emulsion product. Aqueous dispersions can also be formed in a batch melt process using water and one or more dispersants. In either a continuous or batch process, the temperature must be higher than the melting temperature of the polyester. When the temperature of the molding process is 100°C or higher, the pressure in the process must be controlled to be higher than the vapor pressure at the process temperature.

[0026] The aqueous dispersion may contain 15% to 70% by weight of solids, based on the total weight of the aqueous dispersion. For example, the aqueous dispersion may have a solids content of 15% by weight or more, or 20% by weight or more, or 25% by weight or more, or 30% by weight or more, or 35% by weight or more, or 40% by weight or more, or 45% by weight or more, or 50% by weight or more, or 55% by weight or more, or 60% by weight or more, or 65% by weight or more, while at the same time having a solids content of 70% by weight or less, or 65% by weight or less, or 60% by weight or less, or 55% by weight or less, or 50% by weight or less, or 45% by weight or less, or 40% by weight or less, or 35% by weight or less, or 30% by weight or less, or 25% by weight or less, or 20% by weight or less. The solids content of the aqueous dispersion may be measured using an infrared solids analyzer, such as an OHAUS® MB45 Moisture Analyzer or similar device.

[0027] The aqueous dispersion has a viscosity of 5 Pa or less, measured using an RV viscometer at 50 revolutions per minute using a spindle appropriate for the given viscosity. * s or less, or 4Pa * s or less, or 3Pa * s or less, or 2 Pa * s or less, or 1 Pa * It can be less than or equal to s.

[0028] Dispersants As used herein, a "dispersant" refers to a substance added to a melt-emulsification process to aid in the formation of emulsion particles, to allow suspension of solid particles in a liquid, to improve particle separation, and to prevent particle settling or agglomeration. The dispersant may be selected from the group consisting of polyvinyl alcohol, fatty alcohol ethoxylates, ethylene oxide / propylene oxide block copolymers, salts of fatty acids, water-dispersible sulfonated polyesters, and mixtures thereof.

[0029] In the example where polyvinyl alcohol is used, the polyvinyl alcohol used may be 88% to 98% saponified, and the viscosity (mPa of a 4% aqueous solution at 20°C) *The viscosity (seconds) is less than 30, and preferably less than 10. Examples of commercially available PVA include Poval™ 4-88 available from Kuraray Co., Ltd., Poval™ 6-88 available from Kuraray Co., Ltd., Poval™ 18-88 available from Kuraray Co., Ltd., Poval™ 10-98 available from Kuraray Co., Ltd., Selvol™ E310 available from Sekisui Specialty Chemicals America, and end-hydrophobically modified materials such as Exeval™ RS-2117 available from Kuraray Co., Ltd., and blends thereof.

[0030] The aqueous dispersion may contain 1% to 20% by weight of dispersant based on the total weight of the aqueous dispersion. For example, the aqueous dispersion may contain 1% by weight or more, or 2% by weight or more, or 4% by weight or more, or 6% by weight or more, or 8% by weight or more, or 10% by weight or more, or 12% by weight or more, or 14% by weight or more, or 16% by weight or more, or 18% by weight or more, and at the same time, 20% by weight or less, or 18% by weight or less, or 16% by weight or less, or 14% by weight or less, or 12% by weight or less, or 10% by weight or less, or 8% by weight or less, or 6% by weight or less, or 4% by weight or less, or 2% by weight or less of dispersant based on the total weight of the aqueous dispersion.

[0031] Polyamines The polyamine used in the aqueous dispersion is a polyamine having three or more amino groups. As defined herein, an amino group is a group consisting of one nitrogen atom and two hydrogen atoms bonded together and capable of undergoing aminolysis to form an amide bond with a polyester. The polyamine may have three or more amino groups, four or more amino groups, five or more amino groups, six or more amino groups, seven or more amino groups, eight or more amino groups, nine or more amino groups, ten or more amino groups, fifty or more amino groups, one hundred or more amino groups, two hundred or more amino groups, three hundred or more amino groups, four hundred or more amino groups, five hundred or more amino groups, six hundred or more amino groups, seven hundred or more amino groups, eight hundred or more amino groups, nine hundred or more amino groups, or one thousand or more amino groups. Each amino group present on the polyamine may independently be one of primary, secondary, or tertiary amino groups.

[0032] The polyamine is selected from the group consisting of polyethyleneimine, chitosan, diethylenetriamine, triethylenetetramine, and combinations thereof.

[0033] The aqueous dispersion may contain 0.05% to 5% by weight of polyamine based on the total weight of the aqueous dispersion. For example, the aqueous dispersion may contain 0.05% by weight or more, or 0.1% by weight or more, or 0.5% by weight or more, or 1.0% by weight or more, or 1.5% by weight or more, or 2.0% by weight or more, or 2.5% by weight or more, or 3.0% by weight or more, or 3.5% by weight or more, or 4.0% by weight or more, or 4.5% by weight or more, and at the same time, 5.0% by weight or less, or 4.5% by weight or less, or 4.0% by weight or less, or 3.5% by weight or less, or 3.0% by weight or less, or 2.5% by weight or less, or 2.0% by weight or less, or 1.5% by weight or less, or 1.0% by weight or less, or 0.5% by weight or less, or 0.1% by weight or less of polyamine based on the total weight of the aqueous dispersion.

[0034] polyester The aqueous dispersion includes a plurality of particles of a polyester. The polyester has a glass transition temperature of 50° C. or less as measured in accordance with ASTM E1356-08. For example, the polyester may be a polyester having a glass transition temperature of 50° C. or less as measured in accordance with ASTM E1356-08. Above -100°C, or above -95°C, or above -90°C, or above -85°C, or above -80°C, or above -75°C, or above -70°C, or above -65°C, or above -60°C, or above -55°C, or above -50°C, or above -45°C, or above -40°C, or above -35°C, or above -30°C, or above -25°C, or above -20°C, or above -15°C, or above -10°C, or above -5°C, or above 0°C, or above 5°C, or above 10°C, or above 15°C, or above 20°C, or above 25°C, or above 30°C, or above 35°C, or above 40°C, or above 45°C, measured in accordance with E1356-08 , or at the same time, may have a glass transition temperature of 50°C or less, or 45°C or less, or 40°C or less, or 35°C or less, or 30°C or less, or 25°C or less, or 20°C or less, or 15°C or less, or 10°C or less, or 5°C or less, or 0°C or less, or -5°C or less, or -10°C or less, or -15°C or less, or -20°C or less, or -25°C or less, or -30°C or less, or -35°C or less, or -40°C or less, or -45°C or less, or -50°C or less, or -55°C or less, or -60°C or less, or -65°C or less, or -70°C or less, or -75°C or less, or -80°C or less, or -85°C or less, or -90°C or less, or -95°C or less.

[0035] The polyesters can have a weight average molecular weight of 5,000 grams / mole (“g / mol”) to 100,000 g / mol as measured by gel permeation chromatography. For example, the polyester may have a molecular weight of 5,000 g / mol or more, or 10,000 g / mol or more, or 15,000 g / mol or more, or 20,000 g / mol or more, or 25,000 g / mol or more, or 30,000 g / mol or more, or 35,000 g / mol or more, or 40,000 g / mol or more, or 45,000 g / mol or more, or 50,000 g / mol or more, or 55,000 g / mol or more, or 60,000 g / mol or more, or 65,000 g / mol or more, or 70,000 g / mol or more, or 75,000 g / mol or more, or 80,000 g / mol or more, or 85,000 g / mol or more, or 90,000 g / mol or more, or 95,000 g / mol or more, as measured by gel permeation chromatography. g / mol or more, and at the same time, 100,000 g / mol or less, or 95,000 g / mol or less, or 90,000 g / mol or less, or 85,000 g / mol or less, or 80,000 g / mol or less, or 75,000 g / mol or less, or 70,000 g / mol or less, or 65,000 g / mol or less, or 60,000 g / mol or less, or 55,000 g / mol or less, or 50,000 g / mol or less, or 45,000 g / mol or less, or 40,000 g / mol or less, or 35,000 g / mol or less, or 30,000 g / mol or less, or 25,000 g / mol or less, or 20,000 g / mol or less, or 15,000 g / mol or less, or 10,000 g / mol or less.

[0036] The polyester is an aliphatic polyester. As used herein, the term "aliphatic" in reference to a polyester means that the carbon bonds of the polyester are open chain, not cyclic (i.e., the polyester is not aromatic). The polyester may be selected from the group consisting of polycaprolactone, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), polyhydroxyalkanoate, polybutylene adipate terephthalate, polybutylene succinate, polybutylene succinate adipate, poly(3-hydroxybutyrate), and mixtures thereof.

[0037] The plurality of polyester particles may have a volume average ("V average") diameter of 100 nm to 1500 nm as measured according to the Particle Size Test. As used herein, the term "volume average" is the diameter of a particle that, when multiplied by the total number of particles, equals the total volume of the sample. The polyester particles may be 100 nm or greater, or 150 nm or greater, or 200 nm or greater, or 250 nm or greater, or 300 nm or greater, or 350 nm or greater, or 400 nm or greater, or 450 nm or greater, or 500 nm or greater, or 550 nm or greater, or 600 nm or greater, or 650 nm or greater, or 700 nm or greater, or 750 nm or greater, or 800 nm or greater, or 850 nm or greater, or 900 nm or greater, or 950 nm or greater, or 1000 nm or greater, or 1050 nm or greater, or 1100 nm or greater, or 1150 nm or greater, or 1200 nm or greater, or 1250 nm or greater, or 1300 nm or greater, or 1350 nm or greater, or 1400 nm or greater, or 1450 nm or greater, as measured in accordance with the Particle Size Test. m or more, and at the same time have a V-average particle size of 1500 nm or less, or 1450 nm or less, or 1400 nm or less, or 1350 nm or less, or 1300 nm or less, or 1250 nm or less, or 1200 nm or less, or 1150 nm or less, or 1100 nm or less, or 1050 nm or less, or 1000 nm or less, or 950 nm or less, or 900 nm or less, or 850 nm or less, or 800 nm or less, or 750 nm or less, or 700 nm or less, or 650 nm or less, or 600 nm or less, or 550 nm or less, or 500 nm or less, or 450 nm or less, or 400 nm or less, or 350 nm or less, or 300 nm or less, or 250 nm or less, or 200 nm or less, or 150 nm or less.

[0038] The aqueous dispersion contains 20% to 60% by weight of polyester particles based on the total weight of the aqueous dispersion. For example, the aqueous dispersion contains 20% by weight or more, or 25% by weight or more, or 30% by weight or more, or 35% by weight or more, or 40% by weight or more, or 45% by weight or more, or 50% by weight or more, or 55% by weight or more, and at the same time 60% by weight or less, or 55% by weight or less, or 50% by weight or less, or 45% by weight or less, or 40% by weight or less, or 35% by weight or less, or 30% by weight or less, or 25% by weight or less, based on the total weight of the aqueous dispersion.

[0039] The aqueous dispersion has a weight ratio of dispersant to polyester particles of 10:90 to 40:60. For example, the weight ratio of dispersant to polyester particles can be 10:90 or more, or 20:80 or more, or 30:70 or more, and simultaneously 40:60 or less, or 30:70 or less, or 20:80 or less.

[0040] Additional ingredients The aqueous dispersions may optionally contain one or more additional ingredients, such as polymeric solids (e.g., waxes such as ethylene bis(stearamide) or N,N' ethylene bisstearamide), other aqueous dispersions, pigments, wetting agents, defoamers, solvents, rheology modifiers, surfactants, antioxidants, and other processing aids that improve the barrier and performance attributes of the dispersions, films formed from the dispersions, and articles coated with the films.

[0041] Film Formation Method As explained above, the aqueous dispersions can be used to form films and / or to coat substrates or articles with such films. Thus, a method of forming a film using the aqueous dispersions includes applying the aqueous dispersion to an article and curing the aqueous dispersion at a temperature of 10° C. to 50° C. to form the film.

[0042] The aqueous dispersion can be applied to an article in various ways. For example, the article can be dipped in the aqueous dispersion, or the aqueous dispersion can be sprayed onto the article. It will be understood that multiple coatings or applications of the aqueous dispersion to the article may be performed. The aqueous dispersion can be used to form a film on various types of articles. For example, the articles may include seeds, paper articles, and crop additives (e.g., fertilizers, crop aids, pesticides, etc.). The aqueous dispersion can also be cast onto a surface to form a film directly on the surface.

[0043] After the aqueous dispersion is applied to an article, the dispersion is cured to form a film. The curing of the aqueous dispersion may be carried out at a temperature of 10°C to 50°C to form a film. For example, the curing temperature may be 10°C or higher, or 15°C or higher, or 20°C or higher, or 25°C or higher, or 30°C or higher, or 35°C or higher, or 40°C or higher, while simultaneously being 50°C or lower, or 45°C or lower, or 40°C or lower, or 35°C or lower, or 30°C or lower, or 25°C or lower, or 20°C or lower, or 15°C or lower. As emphasized above, the aqueous dispersion can be cured to form a film at a temperature of 10°C to 50°C due to the increased chain mobility of the polyester (i.e., having a glass transition temperature of less than 50°C), thereby allowing the amino groups present on the polyamine to essentially crosslink polyester particles. This feature is advantageous in that articles that would be damaged by curing at high temperatures (e.g., seeds, paper products, etc.) will not be damaged by the curing of the aqueous dispersion. It will be appreciated that curing of the aqueous dispersion into a film may be carried out at temperatures above 50°C.

[0044] Films formed from the cured aqueous dispersions can exhibit a variety of beneficial properties. For example, the films can exhibit turbidity values ​​of 50 or less, or 45 or less, or 40 or less, or 35 or less, or 30 or less, or 25 or less, or 20 or less, or 15 or less, or 10 or less, or 5 or less, or 0, as measured according to the Turbidity Test. Additionally, the films can exhibit a visual rating of 5 or greater, or 6 or greater, or 7 or greater, or 8 or greater, or 9 or greater, or 10, as measured according to the Visual Water Fastness Test. [Example]

[0045] material The following are materials used to form inventive examples ("IE") and comparative examples ("CE").

[0046] PLA is a polylactic acid with a weight average molecular weight of 155,000 Da and is commercially available as Ingeo™ Biopolymer 4032D by NatureWorks, Inc. (Plymouth, Minnesota).

[0047] PCL is polycaprolactone with a weight average molecular weight of 25,000 g / mol and is commercially available as CAPA™ 6250 from Ingevity, Inc., North Charleston, South Carolina.

[0048] PVOH1 is polyvinyl alcohol, commercially available as Poval™ 4-88 from Kuraray Co., Ltd. (Tokyo, Japan).

[0049] PVOH2 is polyvinyl alcohol, commercially available as Poval™ 6-88 from Kuraray Co., Ltd. (Tokyo, Japan).

[0050] PVOH3 is polyvinyl alcohol, commercially available as Poval™ 18-88 from Kuraray Co., Ltd. (Tokyo, Japan).

[0051] PA1 is a branched polyethyleneimine having a number average molecular weight of 800 g / mol and 18 primary, secondary, and tertiary amino functionalities, and is commercially available from Sigma-Aldrich, St. Louis, Missouri.

[0052] PA2 is a branched polyethyleneimine having a number average molecular weight of 25,000 g / mol and 581 primary, secondary, and tertiary amino functionalities, and is commercially available from Sigma-Aldrich, St. Louis, Missouri.

[0053] DETA is diethylenetriamine with CAS number 111-40-0 and three amino functional sites, and is commercially available from Sigma-Aldrich, St. Louis, Missouri.

[0054] Jeffamine is a bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol with a molecular weight average of 1900 g / mol, CAS number 65605-36-9, and two amino functional groups, and is commercially available from Sigma-Aldrich, St. Louis, Missouri.

[0055] Preparation of dispersion The polyester dispersion components IE1-IE6 and CE1-CE8 had the polymer phase composition and physical properties shown in Table 2 and were formed from the raw materials described above and prepared according to the general procedures, processes, and conditions described herein. The polyester resin and PVOH listed for each example in Table 2 were fed into a 25 mm diameter twin-screw extruder at a total feed rate of 75.6 g / min using a rate-controlled feeder in the ratios listed in Table 2. The solid components were fed through the extruder and melted to form a liquid molten material, with the melt zone temperature within the extruder set higher than the melt temperature of the PVOH material. An initial amount of water was then added into the extruder at a rate approximately equal to the feed rate of the PVOH material. Additional dilution water was added later in the extruder at a rate that provided the composition percentage solids shown in Table 2. The extruder speed used was 600 rpm. At the extruder outlet, a backpressure regulator was used to adjust the pressure within the extruder barrel to a pressure suitable for suppressing steam formation (typically, the pressure was 2 MPa to 4 MPa). Each polyester dispersion exits the extruder and is first filtered through a 200 micrometer (μm) filter. The resulting filtered polyester dispersion has a solids content measured in weight percent (wt%), and the solid particles of the polyester dispersion have a volume average particle size measured in micrometers. The solids content of the polyester dispersion is measured using an infrared solids analyzer, and the particle size of the solid particles of the polyester dispersion is measured using a COULTER™ LS-230 particle size analyzer (Beckman Coulter, Fullerton, CA). The solids content and average particle size (particle size, PS) of the solid particles of the polyester dispersion compositions are shown in Table 2.

[0056] Sample preparation The polyester dispersions were mixed with or without selected polyamines according to Table 1. The samples were stored overnight in a cabinet. Five grams of each example was sampled and 0.12 grams of red pigment dispersion was added (as an indicator for subsequent visual waterfastness and turbidity testing). After vortex mixing for five minutes, 3 grams of each sample was poured into separate 47 mm Petri dishes and allowed to dry overnight in a fume hood exposed to ambient air at 23°C to cast films.

[0057] Test Method Visual Water Resistance Test For the water resistance test, a rectangular strip of approximately 0.2 g of film was cut and placed in a vial. 10 mL of deionized water was added to the vial. The color and appearance of the water were observed after 5, 30, and 60 minutes. The vial was gently rotated by hand every 5 minutes. Water resistance was visually rated on a scale of 1 to 10, with 1 representing no water resistance and 10 representing excellent water resistance. Samples that completely disintegrated within the first 5 minutes were assigned a rating of 1 to 2. Samples that did not disintegrate within 5 minutes but crumbled into small pieces and showed red color and cloudiness after 30 minutes were assigned a rating of 3 to 6. Samples that showed no disintegration after 60 minutes were given a rating of 7 to 10, depending on the color and clarity of the liquid.

[0058] Turbidity Test Turbidity measurements were used to quantitatively describe water resistance. Turbidity tests were performed by cutting 0.2 g pieces of cast film and placing them in vials. 20 mL of deionized water was added to each vial. After 60 minutes, the vials were gently rotated by hand, and then 3 mL of supernatant was removed from each vial and added to a 30 mL turbidity tube. The tubes were then filled to 30 mL with deionized water, and the turbidity was measured using a Hach Ratio Turbidimeter. The test was repeated three times using three separate pieces cut from the same cast film. The turbidity meter's measurement range is 0 to 200. A turbidity of 200 was recorded for samples that were outside the range.

[0059] Particle size test Particle size was measured by laser diffraction using a COULTER™ LS-230 Particle Size Analyzer (Beckman Coulter, Fullerton, Calif.) with the particle (sample) refractive index set to 1.5 and is reported as the volume mean diameter of the polyester particles.

[0060] Glass transition temperature Measure the glass transition temperature according to ASTM E1356-08(2014).

[0061] result Table 1 lists the compositions IE1-IE6 and CE1-IE8, as well as related performance results. Table 2 lists information about the polyester dispersions, including a column for "PE / DA," which is the relative weight ratio of polyester to dispersant based on the combined weight of polyester and dispersant.

[0062] [Table 1]

[0063] [Table 2]

[0064] Referring now to Table 1, CE1, CE2, CE5, and CE7 all demonstrate that the absence of polyamine in the aqueous dispersion readily results in the formation of non-water-resistant films, regardless of the type of polyester. This is evident from the low visual ratings and high turbidity values. CE3 and CE4 demonstrate that the high glass transition temperature (60°C-65°C) of polylactic acid is too high to provide sufficient chain mobility for polyamine crosslinking, even when polyamines with three or more amino groups are used. CE6 and CE8 demonstrate that the use of polyamines with only two amino groups fails to produce satisfactory results, even when polyesters with glass transition temperatures below 50°C (i.e., polycaprolactone) are used.

[0065] Referring now to IE1 to IE6, it is apparent that an aqueous dispersion comprising a polyamine having three or more amino groups and a plurality of particles of a polyester having a glass transition temperature of 50°C or less as measured in accordance with ASTM E1356-08 can achieve a turbidity value of 50 or less as measured in accordance with the Turbidity Test and a visual rating of 5 or more as measured in accordance with the Visual Water Fastness Test without requiring a curing step above 50°C. As explained above, the polyamine is believed to react and bond with the surface of the polyester particles via aminolysis. Upon drying, the particles approach each other, and unreacted amino groups on one particle react and bond with an adjacent particle, promoting film formation.

Claims

1. An aqueous dispersion comprising: Water and a dispersant; and a polyamine having three or more amino groups; a plurality of particles of a polyester, the polyester being aliphatic and having a glass transition temperature of 50° C. or less as measured in accordance with ASTM E1356-08.

2. 10. The aqueous dispersion of claim 1, wherein the dispersing agent is selected from the group consisting of polyvinyl alcohol, fatty alcohol ethoxylates, ethylene oxide / propylene oxide block copolymers, salts of fatty acids, and mixtures thereof.

3. 3. The aqueous dispersion of claim 1, wherein the polyester particles have a volume average diameter of from 100 nm to 1500 nm, measured according to the Particle Size Test.

4. The aqueous dispersion according to any one of claims 1 to 3, 1 wt % to 20 wt % of the dispersant based on the total weight of the aqueous dispersion; 0.05% to 5% by weight of the polyamine, based on the total weight of the aqueous dispersion; and 20% to 60% by weight of said polyester particles based on the total weight of said aqueous dispersion.

5. 5. The aqueous dispersion of claim 1, wherein the polyamine is selected from the group consisting of polyethyleneimine, chitosan, diethylenetriamine, triethylenetetramine, and combinations thereof.

6. 6. The aqueous dispersion of claim 1, wherein the aqueous dispersion comprises 0.1% to 1.0% by weight of the polyamine, based on the total weight of the aqueous dispersion.

7. 7. The aqueous dispersion according to claim 1, wherein the glass transition temperature is from -70°C to 20°C.

8. 8. The aqueous dispersion of any one of claims 1 to 7, wherein the polyester is selected from the group consisting of polycaprolactone, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), polyhydroxyalkanoate, polybutylene adipate terephthalate, polybutylene succinate, polybutylene succinate adipate, poly(3-hydroxybutyrate), and mixtures thereof.

9. 1. A method of forming a film, comprising: applying the aqueous dispersion of any one of claims 1 to 8 to an article; and curing the aqueous dispersion at a temperature of from 10°C to 50°C to form a film.

10. 10. The method of claim 9, wherein the article is selected from the group consisting of seeds, paper articles, and crop additives.

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