Aqueous polyurethane dispersions, prepolymers, and shaped articles made therefrom

Abstract

The present application relates to aqueous polyurethane dispersions, prepolymers, and shaped articles made therefrom. Provided are prepolymers, aqueous polyurethane dispersions prepared therefrom, shaped articles comprising the same having improved whiteness retention and tensile strength, and methods for their use in shaped articles.

Description

[0001] This application was filed on April 25, 2017, with application number [Application Number Missing]. This is a divisional application of the invention patent application entitled "Waterborne polyurethane dispersion, prepolymer, and molded articles made therefrom".

[0002] Cross-reference to related applications This application claims the benefit of U.S. Provisional Application 62 / 376,003, filed August 17, 2016, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to prepolymers and aqueous polyurethane dispersions made therefrom, as well as shaped articles and films made from these dispersions, and methods of using them in shaped articles. Background Technology

[0004] Shapewear is designed to temporarily alter the wearer's body shape for a more fashionable silhouette. In recent years, fashion trends have favored clothing and garment designs that increasingly emphasize the natural curves of the human body, and form-fitting clothing has become a growing trend in the market. Its primary applications are in women's clothing, such as underwear, shapewear, jeans, and woven trousers. Many female consumers seek comfortable clothing that enhances their figure while highlighting their best features, such as shapewear jeans that can reduce belly fat, tighten thighs, and lift the buttocks. This type of clothing improves the wearer's appearance and self-esteem.

[0005] Current shaping techniques primarily utilize different yarn loop structures with long float stitches, higher denier, or high mesh elastic fibers; or apply special contour patterns to strategically selected areas. Other common practices include introducing a second layer of fabric or padding sewn together with the bottom fabric, or selecting fabrics with different elasticities and sewing them together in different locations. See, for example, U.S. Patents 7,950,069, 7,341,500, and 7,945,970, WO2013 / 154445 A1, U.S. Patent Application Publications 2010 / 0064409A1 and 2011 / 0214216A1, GB2477754A, and EP 0519135B1. In one design, a rigid plate is added inside the jeans at the front of the abdomen to help slim the stomach area. In another, a pad or sponge is inserted into the pants to lift and enhance the wearer's visual hip contour. However, all these designs and methods compromise the wearer's comfort and are often visible from the surface of the garment.

[0006] Polyurethane (including polyurethane urea) can be used as an adhesive for a wide range of substrates, including textiles. Typically, this polyurethane is a fully formed, non-reactive polymer or a reactive isocyanate-terminated prepolymer. Such reactive polyurethane adhesives generally require extended curing times to achieve sufficient bond strength, which can be disadvantageous during manufacturing. Furthermore, the isocyanate groups of polyurethane are known to be sensitive to moisture, which limits storage stability and reduces the shelf life of products incorporating such polyurethane. Typically, when fully formed, these polymers are dissolved in solvents (solvent-based), dispersed in water (aqueous), or processed as thermoplastic solids (hot melt). It is noteworthy that solvent-based adhesives face increasingly stringent health and environmental regulations aimed at reducing emissions of volatile organic compounds (VOCs) and harmful air pollutants (HAPs). Therefore, alternatives to traditional solvent-based products are needed.

[0007] While hot melt adhesives are environmentally safe and easy to apply as films, they typically exhibit high firmness and poor resilience when subjected to repeated stretching cycles. Therefore, improvements are needed.

[0008] Many attempts have been made to develop waterborne polyurethane adhesives to overcome these shortcomings.

[0009] U.S. Patent 5,270,433 discloses an "adhesive composition comprising a substantially transparent and solvent-free aqueous one-component polyurethane dispersion containing (a) a polyol mixture comprising polypropylene glycol, (b) a polyfunctional isocyanate mixture comprising ααα1α1-tetramethylxylene diisocyanate (TMXDI), (c) a functional component capable of forming a salt in aqueous solution, and (d) a reaction product optionally containing a chain extender." The adhesive film formed from this composition exhibits low resilience and poor heat resistance due to the asymmetric structure and steric hindrance of the isocyanate groups on the TMXDI, which prevents the formation of strong inter-chain hydrourea bonds in the hard segments of the polymer.

[0010] U.S. Patent Application Publication 2004 / 0014880A1 discloses an aqueous polyurethane dispersion for adhesive bonding in wet and dry laminates, which is claimed to have excellent coatability, bond strength, and heat resistance. The dispersion contains a large amount of the organic solvent methyl ethyl ketone (MEK).

[0011] U.S. Patent Application Publication 2003 / 0220463A1 discloses a method for preparing polyurethane dispersions free of organic solvents such as N-methylpyrrolidone (NMP). However, this composition is limited to prepolymers with low free diisocyanate species, such as methylene bis(4-phenyl isocyanate) (4,4'-MDI). The method for preparing such prepolymers with low free diisocyanate is complex (as disclosed in U.S. Patent 5,703,193). This processing also requires short-path distillation of the free diisocyanate, making it uneconomical in preparing prepolymers for polyurethane dispersions.

[0012] US Patent 4,387,181 discloses a stable aqueous polyurethane dispersion containing N-methylpyrrolidone (NMP) solvent, prepared by reacting an oxime-blocked isocyanate-terminated prepolymer with carboxylic acid groups with a polyamine. The prepolymer is prepared by reacting an aromatic diisocyanate, such as 4,4'-diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI), with a polyether or polyester polyol and a dihydroxyalkanoic acid. The oxime-blocked isocyanate groups can react with the polyamine within 6 to 18 hours at 60 to 80°C. The dispersion is storage stable, and the film formed from the dispersion exhibits good tensile properties. However, the dispersion still contains organic solvents, and the required long curing time is unsuitable for practical fabric bonding and lamination.

[0013] U.S. Patent 5,563,208 describes an acetone method for preparing a substantially solvent-free aqueous polyurethane dispersion comprising a urethane prepolymer having blocked isocyanate groups and a polyamine with a molecular weight ranging from 60 to 400, wherein the molar ratio of the blocked isocyanate groups to the primary amine and / or primary amine groups is 1:0.9 to 1:1.5. This dispersion is stable at room temperature and provides a heat-resistant adhesive in coatings. However, it requires a long curing time (up to 30 minutes), which remains unsuitable for fabric bonding and adhesion. Furthermore, the acetone method requires an additional distillation step to remove acetone from the dispersion, making the method less economical.

[0014] U.S. Patent 6,586,523 describes an acetone method for preparing a self-crosslinking polyurethane dispersion for use as a sizing agent, comprising a prepolymer having partially capped and partially extended isocyanate groups, and an excess of a polyfunctional compound having a molecular weight of 32 to 500 having primary or secondary amino and / or hydroxyl groups. This dispersion composition reduces the curing time to some extent, but still has drawbacks because an additional distillation step is required to remove the acetone.

[0015] U.S. Patent 6,555,613 describes a solvent-free aqueous dispersion of a reactive polyurethane having a number-average molecular weight (Mn) of 800 to 14,000, a branching degree of 0.0 to 3.0 mol / kg, and an isocyanate functionality of 2.0 to 6.0 per mole. This polyurethane is made from polyester polyols, polyisocyanates, and polyisocyanate adducts, with low molecular weight polyols and anion-forming units introduced into the polymer chain after neutralization, and possessing end-capped isocyanate groups capable of further crosslinking reactions. The result of this dispersion is a hard, glossy, and elastic coating material, but this coating material lacks the elastic characteristics and stretch / recovery properties required for adhesives used with stretched fabrics.

[0016] U.S. Patent 7,240,371 discloses polymer compositions such as polyurethane urea films and tapes comprising fully formed polyurethane urea with blocked isocyanate end groups. These compositions are prepared from a solvent-free system comprising a prepolymer containing at least one polyether or polyester polyol, a mixture of MDI isomers, and a diol.

[0017] U.S. Patent 9,346,932 discloses an aqueous polyurethane dispersion that provides a mixture of at least one polyether, polyester or polycarbonate polyol, MDI isomers and diol, and a molded three-dimensional article formed therefrom in a solvent-free system of a prepolymer.

[0018] Carmen, C. et al. disclosed a method in patent EP 2280619B1 to add a polymer composition to the edge of clothing to form a garment edge band and to add a film to clothing such as a bra to form a laminated fabric. U.S. Patent Application Publication No. 2009 / 0181599A1 disclosed a fabric laminate or fabric band having a multilayer structure including at least one fabric layer and at least one polymer layer that has been joined or bonded together.

[0019] Other examples of polymeric compositions are polyurethane tapes, such as those available from Bemis, and polyolefin resins that can form films, such as those available under the trade name VISTAMAXX from ExxonMobil. These films can be bonded to fabrics by heat. Summary of the Invention

[0020] One aspect of this disclosure relates to a prepolymer for use in aqueous polyurethane dispersions. The prepolymer comprises a glycol, an aliphatic diisocyanate, and a diol. In one embodiment, the prepolymer further comprises 1-hexanol. The ratio of isocyanate groups in the aliphatic diisocyanate to hydroxyl groups in the glycol and diol is about 1.30 to about 2.20, or about 1.30 to about 2.00. The milliequivalent concentration (Meq acid / kg CG) of the carboxylic acid groups per kg of prepolymer ranges from about 140 to about 250 or from about 150 to about 220.

[0021] Another aspect of this disclosure relates to an aqueous polyurethane dispersion comprising a prepolymer, including diols, aliphatic diisocyanates, and diols, and optionally 1-hexanol. The aqueous polyurethane dispersion may further comprise water, a neutralizing agent, a surfactant, an antifoaming agent, an antioxidant, and / or a thickener. The neutralizing agent may be triethylamine (TEA) and / or 2-dimethylamino-2-methyl-1-propanol (DMAMP).

[0022] This disclosure also relates to molded articles, such as films, derived from these aqueous polyurethane dispersions, having improved resistance to oxidative discoloration and improved tensile properties such as toughness, load and unload forces, and tensile and recovery properties. The molded articles can be applied to a substrate in areas where improved tensile or tension properties are desired.

[0023] Another aspect of this disclosure relates to a method for producing molded articles, comprising applying an aqueous polyurethane dispersion to a substrate and curing the aqueous polyurethane dispersion onto the substrate. Attached Figure Description

[0024] Figure 1 It is a bar graph depicting the membrane whiteness retention rate of six membrane samples after heat exposure.

[0025] Figure 2 This is a bar graph depicting the whiteness retention rate of six membrane samples after UV exposure.

[0026] Figure 3 This is a bar graph depicting the membrane whiteness retention rate of six membrane samples after NO2 exposure. Detailed Implementation

[0027] The aqueous polyurethane dispersions falling within this disclosure are provided by specific urethane prepolymers, which are also disclosed herein. The aqueous polyurethane dispersions and prepolymers are free of organic solvents or co-solvents, alkyl ethoxylates, or organotin catalysts. Molded articles, including films, prepared by applying the aqueous polyurethane dispersion to a substrate including textile fabrics are also disclosed. The dispersion can be applied by padding, coating, printing, bonding, laminating, or other processing methods, followed by curing (or drying) for a residence time of about 1 to about 5 minutes. Upon drying, these articles exhibit high tensile strength and resilience, improved chlorine resistance and improved whiteness retention, among other benefits.

[0028] As used herein, the term "dispersion" refers to a system in which the dispersed phase consists of finely broken particles and the continuous phase can be a liquid, solid, or gas.

[0029] As used herein, the term "aqueous polyurethane dispersion" refers to a composition containing at least a polyurethane or polyurethane urea polymer or prepolymer (such as the polyurethane prepolymer described herein) dispersed in an aqueous medium such as water (including deionized water).

[0030] As used herein, a dried aqueous polyurethane dispersion is an aqueous polyurethane dispersion that has undergone curing or drying by any suitable method. A dried aqueous polyurethane dispersion may be in the form of molded articles, such as films.

[0031] Unless otherwise stated, the term “solvent” as used herein refers to a non-aqueous medium, which includes organic solvents, including volatile organic solvents (such as acetone) and less volatile organic solvents (such as MEK or NMP).

[0032] As used herein, the terms “substantially solvent-free” or “substantially solvent-free system” refer to a composition or dispersion in which most or a majority of the components of the composition are not dissolved or dispersed in a solvent.

[0033] As used herein, the term "molded article" can refer to one of a variety of objects, including, for example, films, strips, dots, nets, stripes, beads, and foams. In one embodiment, the molded article is a film. A film can describe a sheet of any shape and can be a layer (or multiple layers) of a dried aqueous polyurethane dispersion having a certain length and width, which may or may not be applied to a substrate for support. The film can be continuous or discontinuous, molded or free-form. In one embodiment, the film can be substantially two-dimensional and / or relatively flat. A strip can describe a film in the form of a narrow strip. A film can be in the form of a strip. As used herein, the term "molded article" is a layer comprising an aqueous polyurethane dispersion containing a polyurethane prepolymer as described herein, which can be dried, can be applied to a substrate or release paper, and can be used for bonding and / or forming a rigid or elastic article.

[0034] The article is a molded substrate or textile fabric. The article can be clothing. The article preferably comprises a dried aqueous polyurethane dispersion, which can be in the form of a molded article and a substrate such as a textile fabric, and may or may not have at least one elastic property, which is partly due to the application of the aqueous polyurethane dispersion or molded article as described herein. The article can be of any suitable construction, such as one-dimensional, two-dimensional, and / or three-dimensional.

[0035] As used herein, the term "narrow strip" refers to a shape having both length and width, wherein the length is at least twice the width. The length can vary and depends on the size of the garment to which it is applied.

[0036] As used herein, the term "textile fabric" refers to knitted, woven, or nonwoven materials. Knitted fabrics can be plain knitted, circular knitted, warp-knitted, narrow elastic, and / or lace. Woven fabrics can be of any construction, such as satin, twill, plain weave, oxford, basket weave, and / or narrow elastic. Nonwoven materials can be meltblown, spunbond, carded fiber-based short fiber webs, etc.

[0037] As used herein, the term "substrate" refers to any material to which a molded article or aqueous polyurethane dispersion can be applied. Substrate can be substantially one-dimensional, such as in fibrous form; two-dimensional, such as in planar sheet form; or three-dimensional, such as in an article or an irregular sheet. For example, planar sheets may include textiles, paper, flocked articles, and / or mesh. For example, three-dimensional articles may include leather and / or foam. Other substrates may include wood, paper, plastics, metals, and composites such as concrete, asphalt, stadium flooring, and plastic sheets.

[0038] As used in this article, the term "stiff yarn" refers to yarn that is essentially inelastic.

[0039] As used herein, the term "molded" article refers to an article or shaped article whose shape changes in response to the application of heat and / or pressure.

[0040] As used herein, the term "derived from" means that a substance is formed from another object. For example, molded articles can be derived from dried aqueous dispersions.

[0041] As used in this article, the term "modulus," also known as the elastic modulus, is a measure of the stiffness of a fabric.

[0042] Prepolymers used in the aqueous polyurethane dispersions of this disclosure include diols, aliphatic diisocyanates, and diols.

[0043] Diol components suitable as raw materials for preparing the prepolymers disclosed herein include polycarbonate and polyester, polycarbonate diol, polyether diol and polyester diol.

[0044] Examples of usable polyether glycols include, but are not limited to, those derived from ring-opening polymerization and / or copolymerization of ethylene oxide, propylene oxide, oxetane, tetrahydrofuran, and 3-methyltetrahydrofuran having two or more hydroxyl groups, or from polyols (such as glycols or mixtures of glycols) having less than 12 carbon atoms in each molecule, such as those derived from the condensation polymerization of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol. Linear bifunctional polyether polyols are preferred, and in one embodiment, poly(tetramethylene ether) glycols with a molecular weight of about 1,700 to about 2,100 are used, such as Terathane® 1800 (Invista) with a functionality of 2.

[0045] Examples of usable polyester diols include those ester diols having two or more hydroxyl groups, produced by the condensation polymerization of low molecular weight aliphatic polycarboxylic acids and polyols or mixtures thereof having no more than 12 carbon atoms per molecule. Examples of suitable polycarboxylic acids are malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, and dodecanoic acid. Examples of suitable polyols for preparing polyester polyols are ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol. In one embodiment, a linear bifunctional polyester polyol with a melting temperature of about 5°C to about 50°C is used.

[0046] Examples of usable polycarbonate diols include those having two or more hydroxyl groups, produced by the condensation polymerization of low molecular weight phosgene, chloroformate, dialkyl carbonate or diallyl carbonate and aliphatic polyols or mixtures thereof having no more than 12 carbon atoms per molecule. Suitable polyols for preparing polycarbonate polyols include diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentanediol, 3-methyl-1,5-pentanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol. In one embodiment, a linear bifunctional polycarbonate polyol with a melting temperature of about 5°C to about 50°C is used.

[0047] In one embodiment, the prepolymer contains at least about 60%, at least about 65%, or at least about 70% of diols, based on the total weight of the prepolymer. In another embodiment, the prepolymer contains about 60% to about 85%, about 65% to about 80%, about 68% to about 78%, or about 70% to about 77% of diols, based on the total weight of the prepolymer.

[0048] Any aliphatic diisocyanate may be used in this disclosure. In one embodiment, the isocyanate is a dicyclohexylmethane diisocyanate, preferably including a mixture of its isomers. Examples of suitable isocyanate components are dicyclohexylmethane diisocyanate or 4,4'-methylenebis(cyclohexylisocyanate) (“PICM”) such as Vestanate® H12MD1 (Evonik) or Desmodur® W (Covestro).

[0049] In one embodiment, the prepolymer contains at least about 10%, at least about 20%, at least about 22%, or at least about 24% isocyanate, based on the total weight of the prepolymer. In another embodiment, the prepolymer contains about 15% to about 35%, about 13% to about 32%, about 20% to about 30%, or about 22% to about 27% isocyanate, based on the total weight of the prepolymer.

[0050] Diols suitable as further starting materials for the preparation of the prepolymers disclosed herein include at least one diol having two hydroxyl groups capable of reacting with isocyanates and at least one carboxylic acid group capable of forming a salt upon neutralization and incapable of reacting with isocyanates. Examples of diols having carboxylic acid groups include, but are not limited to, 2,2-dimethylolpropionic acid (such as DMPA from GEO Specialty Chemicals). ® And Bis-MPA from Perstorp), 2,2-dimethylolbutyric acid, 2,2-dimethylolvalerate and DMPA-induced caprolactones such as CAPA TMHC 1060 (Solvay). In one embodiment, the diol is DMPA.

[0051] In one embodiment, the prepolymer may contain at least about 1%, or at least about 2.2%, or at least about 2.4% of a diol, based on the total weight of the prepolymer. In another embodiment, the prepolymer contains about 1.5% to about 3.5%, about 2.0% to about 3.0%, about 2.2% to about 2.8%, or about 2.4% to about 2.5% of a diol, based on the total weight of the prepolymer.

[0052] The prepolymer may contain at least about 60% diols, at least about 10% isocyanates, and at least about 1% glycols based on the total weight of the prepolymer. The prepolymer may contain at least about 70% diols, at least about 20% isocyanates, and at least about 2.2% glycols based on the total weight of the prepolymer. Based on the total weight of the prepolymer, the prepolymer may contain about 60% to about 80% diols, about 15% to about 35% isocyanates, and about 1.5% to about 3.5% glycols.

[0053] In one embodiment, the prepolymer further comprises a monofunctional alcohol, such as, but not limited to, methanol, ethanol, propanol, butanol, and 1-hexanol. Based on the total weight of the prepolymer, the prepolymer may contain less than about 1%, less than about 0.6%, or less than about 0.5% of a monofunctional alcohol. In another embodiment, based on the total weight of the prepolymer, the prepolymer contains about 0.20% to about 0.70%, about 0.25% to about 0.60%, about 0.31% to about 0.55%, or about 0.31% to about 0.51% of a monofunctional alcohol.

[0054] In one embodiment, the prepolymer further comprises 1-hexanol. Based on the total weight of the prepolymer, the prepolymer may contain less than about 1%, less than about 0.6%, or less than about 0.5% of 1-hexanol. In another embodiment, based on the total weight of the prepolymer, the prepolymer contains about 0.20% to about 0.70%, about 0.25% to about 0.60%, about 0.31% to about 0.55%, or about 0.31% to about 0.51% of 1-hexanol.

[0055] When the prepolymer contains 1-hexanol, it may contain at least about 60% diols, at least about 10% isocyanates, at least about 1% glycols, and less than about 1% 1-hexanol, based on the total weight of the prepolymer. In another embodiment, the prepolymer comprises at least about 70% diols, at least about 20% isocyanates, at least about 2.2% glycols, and less than about 0.6% 1-hexanol, based on the total weight of the prepolymer. The prepolymer may contain about 60% to about 80% diols, about 15% to about 35% isocyanates, about 1.5% to about 3.5% glycols, and about 0.20% to about 0.70% 1-hexanol, based on the total weight of the prepolymer.

[0056] The prepolymer can be formulated to have an NCO / OH ratio (molar ratio of isocyanate groups to hydroxyl groups) of about 1.30 to about 2.20, about 1.30 to about 2.00, about 1.40 to about 1.90, or about 1.50 to about 1.85. The NCO groups are derived from isocyanates, and the OH groups are derived from diols and glycols. It has been found that if the NCO / OH ratio is too low, the prepolymer viscosity will be too high to disperse. Furthermore, a low NCO / OH ratio results in low resilience of the films of the dry aqueous polyurethane dispersions disclosed herein. On the other hand, an excessively high NCO / OH ratio causes the film to lose elasticity or elongation.

[0057] It is believed that adding a monohydric alcohol to the prepolymer reduces viscosity because it limits the increase in molecular weight. A lower viscosity is preferred for dispersibility of the prepolymer. In one embodiment, the viscosity is below about 3000 poise at 40°C, preferably below about 2500 poise at 40°C, and more preferably below about 2000 poise at 40°C. The viscosity at 40°C can be from about 3000 to about 500 poise, from about 2500 to about 600 poise at 40°C, or from about 2000 to about 700 poise at 40°C.

[0058] The prepolymer can be formulated to have a specific Meq acid / kg CG, where Meq is the milliequivalent of a specific functional group (here, a carboxylic acid) per kg of prepolymer or end-capped diol (CG). The carboxylic acid group is derived from a diol such as DMPA, which has two hydroxyl groups capable of reacting with diisocyanates and one carboxylic acid group that cannot react with diisocyanates. The prepolymer can be formulated to have a concentration of carboxylic acid groups per kg of prepolymer milliequivalent of about 140 to about 250, about 150 to about 230, about 150 to about 220, about 155 to about 220, about 170 to about 190, or about 185.

[0059] Importantly, the amount of acid in the prepolymer contributes to the viscosity of the prepolymer and the stability of the aqueous dispersion made from it. For example, if the acid concentration is too high, it means a high glycol concentration, resulting in a prepolymer with high viscosity, which cannot be properly dispersed in water to form a homogeneous dispersion with small particle size. If the acid concentration is too low, it will not provide enough hydrophilic sites after neutralization, and the aqueous dispersion made from the prepolymer will be unstable.

[0060] In one embodiment, the prepolymer can be formulated to have an NCO / OH ratio of about 1.30 to about 2.00 or about 1.40 to about 1.90, and an acid concentration ranging from about 150 to about 220 milliequivalents / kg prepolymer, about 155 to about 220 milliequivalents / kg prepolymer, or about 180 to about 190 milliequivalents / kg prepolymer. Aqueous dispersions made from these prepolymers have been found to have good processability and stability, and films cast from these aqueous dispersions exhibit good whiteness retention and elasticity.

[0061] The prepolymer can be prepared by mixing a diol, isocyanate, and glycol together in one step and reacting them at a temperature of about 50°C to about 100°C for a sufficient time until all hydroxyl groups are substantially consumed and the desired %NCO of isocyanate groups is achieved. Alternatively, the prepolymer can be prepared by charging molten diol into a reactor at about 55°C, followed by the addition of DMPA solid powder, accompanied by stirring and circulation, until the glycol solid particles are dispersed and dissolved in the diol. Molten isocyanate is then charged into the reactor with continuous stirring, and the end-capping reaction is carried out at about 90°C for about 240 minutes, still with continuous stirring. Optionally, a tin-free catalyst such as K-KAT® XK-640 (King Industries Specialty Chemicals) can be used to accelerate the formation of the prepolymer. The resulting viscous prepolymer is then sampled to determine the extent of reaction by titrating the weight percentage (%NCO) of the isocyanate groups in the prepolymer. Assuming a diol MW of 1800, the theoretical %NCO value after the reaction is complete is 2.97. If the determined %NCO value is higher than the theoretical value, the reaction should be allowed to continue until the theoretical value is reached or the %NCO value becomes constant. Once the reaction is determined to be complete, the prepolymer temperature should be maintained between 85°C and 90°C. It is worth noting that the prepolymer is essentially solvent-free and free of alkyl ethoxylates or organotin catalysts. Preferably, the reaction for preparing the prepolymer is carried out in an anhydrous, nitrogen-covered atmosphere to avoid side reactions.

[0062] The prepolymer disclosed herein can be used to produce aqueous polyurethane dispersions. The aqueous polyurethane dispersion may contain about 30% to about 55% or about 35% to about 48% of the prepolymer based on the total weight of the aqueous polyurethane dispersion.

[0063] The amount of prepolymer added may be such that the aqueous polyurethane dispersion contains at least about 25% or at least about 30% diols, at least about 5% or at least about 10% isocyanates, and at least about 1% glycols based on the total weight of the aqueous polyurethane dispersion. In another embodiment, the amount of prepolymer added may be such that the aqueous polyurethane dispersion contains about 25% to about 35% diols, about 5% to about 15% isocyanates, and about 0.5% to about 1.5% glycols based on the total weight of the aqueous polyurethane dispersion. In another embodiment, the amount of prepolymer added may be such that the aqueous polyurethane dispersion contains about 30% diols, about 10% isocyanates, and about 1% glycols based on the total weight of the aqueous polyurethane dispersion.

[0064] The waterborne polyurethane dispersion may further contain one or more of water, neutralizing agents, surfactants, defoamers, antioxidants, and thickeners.

[0065] In one embodiment, a prepolymer containing carboxylic acid groups along its polymer chain can be dispersed into a deionized water medium using a high-speed disperser. This medium comprises: at least one neutralizing agent to form an ionic salt with an acid; at least one surfactant (ionic and / or nonionic dispersant or surfactant); and optionally, at least one diamine chain-extending component. Alternatively, the neutralizing agent can be mixed with the prepolymer before dispersion into the aqueous medium. At least one antifoaming agent and / or defoamer and at least one rheology modifier can be added to the aqueous medium before, during, or after prepolymer dispersion.

[0066] Based on the total weight of the aqueous polyurethane dispersion, the aqueous polyurethane dispersion may contain at least about 50% water, at least about 1% surfactant, at least about 1% thickener, less than about 1% neutralizer, less than about 1% antioxidant and less than about 1% defoamer.

[0067] Based on the total weight of the aqueous polyurethane dispersion, water may be present in approximately 40% to approximately 60% or approximately 50%.

[0068] Neutralizing agents used in these dispersions must be able to convert acid groups into salt groups. Examples include, but are not limited to, tertiary amines (e.g., triethylamine (TEA), N,N-diethylmethylamine, N-methylmorpholine, N,N-diisopropylethylamine, 2-dimethylamino-2-methyl-1-propanol (DMAMP), and triethanolamine) and alkali metal hydroxides (e.g., lithium hydroxide, sodium hydroxide, and potassium hydroxide). Primary and / or secondary amines may also be used as neutralizing agents for acid groups. The degree of neutralization is typically from about 60% to about 140%, for example, in the range of about 80% to about 120% for acid groups. Based on the total weight of the aqueous polyurethane dispersion, the neutralizing agent may be present at about 0.5% to about 0.9%.

[0069] The neutralizing agent may contain TEA, or may contain TEA and a second neutralizing agent. The neutralizing agent may contain both TEA and DMAMP.

[0070] The neutralizing agent may contain DMAMP. Based on the total weight of the aqueous polyurethane dispersion, the aqueous polyurethane dispersion may contain about 0.2% to about 2.0% or about 0.5% to about 1.5% DMAMP. The aqueous polyurethane dispersions disclosed herein may be TEA-free. As used herein, "TEA-free" means less than about 0.01% TEA, preferably 0.00% TEA, based on the total weight of the aqueous polyurethane dispersion. In one embodiment, the aqueous polyurethane dispersion contains less than about 0.1% TEA based on the total weight of the aqueous polyurethane dispersion.

[0071] The neutralizing agent may comprise DMAMP and a second neutralizing agent, wherein the second neutralizing agent is not a TEA. The second neutralizing agent may be, but is not limited to, tertiary amines (other than TEAs, such as N,N-diethylmethylamine, N-methylmorpholine, N,N-diisopropylethylamine, 2-dimethylamino-2-methyl-1-propanol, and triethanolamine), alkali metal hydroxides (such as lithium hydroxide, sodium hydroxide, and potassium hydroxide), primary amines, secondary amines, or any combination thereof. When present, the aqueous polyurethane dispersion may comprise about 0.3% to about 2.0% DMAMP and 0.1% to about 1.0% of the second neutralizing agent based on the total weight of the aqueous polyurethane dispersion. Based on the total weight of the aqueous polyurethane dispersion, the aqueous polyurethane dispersion may comprise about 0.5% to about 1.2% DMAMP and about 0.2% to about 0.8% of the second neutralizing agent to maintain a degree of neutralization between 60% and 140%.

[0072] Water can be used as a chain extender for prepolymers. Optionally, diamines such as ethylenediamine (EDA) can be used as co-chain extenders.

[0073] Examples of surfactants include, but are not limited to, anionic, cationic, or nonionic dispersants or surfactants, such as alkyl diphenyl ether disulfonates, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, ethoxylated nonylphenol, and laurylpyridinium bromide. Based on the total weight of the aqueous polyurethane dispersion, the surfactant may be present in amounts of about 1.0% to about 5.0%, about 1.0% to about 2.0%, or about 1.0% to about 1.5%.

[0074] Examples of suitable defoamers include, but are not limited to, mineral oils and / or silicone oils, such as BYK 012 and Additive65 (a silicone additive from Dow Corning) and Surfynol. TM DF 110L (High molecular weight acetylene glycol nonionic surfactant, from Air Products & Chemicals). The defoamer may be present in amounts from about 0.1% to about 1.0%, from about 0.1% to about 0.5%, or from about 0.1% to about 0.3% based on the total weight of the aqueous polyurethane dispersion.

[0075] Examples of suitable thickeners include, but are not limited to, polyurethanes such as Munzing's Tafigel PUR 61, hydrophobically modified ethoxylated polyurethane (HEUR), hydrophobically modified alkaline swelling emulsion (HASE), and hydrophobically modified hydroxyethyl cellulose (HMHEC). The thickener may be present in amounts of about 1.0% to about 5.0%, about 1.0% to about 2.0%, or about 1.0% to about 1.5% based on the total weight of the aqueous polyurethane dispersion.

[0076] Examples of antioxidants include, but are not limited to, hindered phenols such as Irganox 245 (BASF) or Cyanox 1790 (Cytec). Based on the total weight of the aqueous polyurethane dispersion, the antioxidant may be present in amounts of about 0.3% to about 1.0%, about 0.5% to about 1.0%, or about 0.5% to about 0.8%.

[0077] Furthermore, diamines include ethylenediamine, and similar materials can be used as diamine chain extenders instead of water. Examples of suitable diamine chain extenders include: 1,2-ethylenediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,12-dodecanediamine, 1,2-propanediamine, 2-methyl-1,5-pentanediamine, 1,2-cyclohexanediamine, 1,4-cyclohexanediamine, 4,4'-methylenebis(cyclohexylamine), isophoronediamine, 2,2-dimethyl-1,3-propanediamine, m-tetramethylxylenediamine, and Jeffamine® (Texaco) with a molecular weight less than 500.

[0078] Other additives that may be optionally included in the aqueous polyurethane dispersion or prepolymer include: antioxidants, UV stabilizers, siloxanes, mineral oils, colorants, pigments, matting agents, crosslinking agents, phase change materials (e.g., Outlast®, commercially available from Outlast Technologies, Boulder, Colorado), antimicrobial agents, minerals (e.g., copper), microencapsulated health additives (e.g., aloe vera, vitamin E gel, aloe vera, seaweed, nicotine, caffeine, aroma or flavor), nanoparticles (e.g., silica or carbon), calcium carbonate, flame retardants, anti-adhesion additives, anti-chlorination additives, vitamins, pharmaceuticals, fragrances, conductive additives and / or dye auxiliaries (e.g., Methacrol®, commercially available from El DuPont de Nemours, Wilmington, Delaware). Other additives that may be added to the prepolymer or aqueous dispersion include adhesion promoters, durability improvers, modulus modifiers, structure improvers, tackifiers, antistatic agents, anti-cracking agents, anti-creeping agents, optical brighteners, coalescing agents, conductive additives, luminescent additives, flow and leveling agents, freeze-thaw stabilizers, lubricants, organic and inorganic fillers, preservatives, structure improvers, thermochromic additives, insect repellents and wetting agents, as well as other additives known to those skilled in the art for use to achieve the desired benefits and properties.

[0079] In one embodiment, a matting agent such as titanium dioxide may be added to the aqueous polyurethane dispersion. Any desired amount, known in the art, that imparts the desired properties may be added. For example, based on the total weight of the aqueous polyurethane dispersion, approximately 0.2% to approximately 10% of the matting agent may be added.

[0080] This optional additive may be added to the aqueous polyurethane dispersion before, during, or after the prepolymer dispersion, as permitted by the process. Organic solvents should never be added to the aqueous dispersion.

[0081] In one embodiment, the dispersion can be prepared by adding the prepolymer using a rotor / stator high-speed disperser. The prepolymer prepared as described above is transferred directly to the disperser head and dispersed under high shear force in deionized water, which preferably contains at least one surfactant, neutralizer, antioxidant, and foam control agent. Slightly more prepolymer than required for the dispersion formulation is needed to compensate for losses in the delivery lines and reactor. Once the prepolymer addition is complete, a thickener can be added.

[0082] Aqueous polyurethane dispersions falling within the scope of this disclosure are expected to have a solids content of about 10% to about 50% by weight, about 30% to about 50% by weight, about 30% to about 45% by weight, or about 35% to about 46% by weight. The viscosity of aqueous polyurethane dispersions falling within the scope of this disclosure can vary over a wide range, depending on processing and application requirements, from about 10 centipoise to about 100,000 centipoise. For example, in one embodiment, the viscosity is in the range of about 500 centipoise to about 30,000 centipoise. The viscosity can be varied by using an appropriate amount of thickener, for example, based on about 0 to about 5.0 wt% of the total weight of the aqueous polyurethane dispersion.

[0083] The aqueous polyurethane dispersions disclosed herein offer manufacturing advantages over other dispersions, particularly those containing aromatic isocyanates instead of aliphatic isocyanates. This is primarily due to the relative reactivity of aliphatic isocyanates compared to aromatic isocyanates. The aliphatic isocyanates used in the aqueous polyurethane dispersions disclosed herein react much more slowly when the prepolymer is dispersed in water, allowing sufficient time for the viscous prepolymer to break down into finer droplets. Consequently, the dispersions have smaller and more uniform particles, which can be easily filtered through online filtration systems. When aromatic isocyanates are used instead, the dispersions react rapidly in water, potentially causing the prepolymer droplets to solidify before breaking down into smaller particles. This leaves a significant amount of sand in the dispersion, necessitating offline filtration and reducing yield and productivity.

[0084] It has been found that, upon drying, the dried aqueous polyurethane dispersion of this disclosure can form a continuous elastic film with high tensile strength and resilience. Given that films and fabrics are porous materials, it is recognized that the film or dispersion can partially or completely impregnate the fabric of a shaped article. For example, the dried aqueous polyurethane dispersion can form a layer partially separated from the surrounding layers, or it can be completely transferred to one or more surrounding layers to form a monolithic article without a distinguishable film layer.

[0085] Furthermore, the aqueous polyurethane dispersions described herein are resistant to yellowing and hydrolysis. In particular, compared to other films or articles made from other dispersions known in the art, such as those containing aromatic isocyanates, the aqueous polyurethane dispersions of this disclosure and molded articles made therefrom have been found to have improved whiteness retention (also referred to as improved resistance to oxidative discoloration (or yellowing)). This is especially important for consumer products, as yellowing or fading is particularly undesirable in clothing and consumer goods.

[0086] The CIE whiteness index is a whiteness measurement standard developed by the French International Commission on Illumination (CIE), using D65 illumination, which represents outdoor daylight. Whiteness retention is a measure of resistance to color change after treatment or exposure, measured by the change of the CIE whiteness index over time. Therefore, improved whiteness retention in a fabric means greater resistance to color change. As used herein and unless otherwise stated, the CIE whiteness index (absolute value) should be understood as the CIE whiteness index of a sample free of color-enhancing additives such as pigments, colorants, brighteners, dyes, etc. Those skilled in the art will understand that such additives can be added to waterborne polyurethane dispersions or molded articles, which will alter the absolute value of the CIE whiteness index.

[0087] Coated in Mylar ® Molded articles, such as films, formed on polyester sheet substrates from the aqueous polyurethane dispersions disclosed herein can have a CIE whiteness index value of about 50 to about 60. After heat exposure (exposure to heated air at 195°C for five minutes in a hot chamber), the film can have a CIE whiteness index value of about 30 to about 40. That is, the reduction in the CIE whiteness index value is less than about 20 index points, or understood as a whiteness reduction of about 30% to about 40%. After 8 hours of ultraviolet (UV) exposure (using, for example, a xenon arc lamp to simulate sunlight exposure, including UV), the film can have a CIE whiteness index of about 50 to about 60. That is, the CIE whiteness index value does not decrease after UV exposure, i.e., less than about 2% or about 0%. After exposure to NO2 (24 hours), the film can have a CIE whiteness index value of about 48 to about 58, with a CIE whiteness index value reduction of about 0 to 3 index points. That is, the reduction in the CIE whiteness value is less than about 5%, or about 0% to about 4%.

[0088] Furthermore, films formed from the dried aqueous polyurethane dispersions disclosed herein exhibit improved tensile properties compared to films formed from other dispersions. These films can have tensile strengths exceeding about 0.14 g / denier or exceeding about 0.15 g / denier (when the film is stretched in the sixth cycle). The films can have tensile strengths from about 0.14 g / denier to about 0.24 g / denier or from about 0.15 g / denier to about 0.22 g / denier. It has been found that higher tensile strengths are possible when the NCO / OH ratio of the prepolymer or aqueous polyurethane dispersion is between about 1.50 and about 1.90, and the number-average molecular weight of the polymer is greater than 10,000. NCO / OH ratios below about 1.5 produce films with less or insufficient force (stretching / recovery), and NCO / OH ratios above about 1.9 produce brittle films with reduced elongation at break (ELO).

[0089] In an embodiment, a film formed from a dried aqueous polyurethane dispersion having an NCO / OH ratio of about 1.50 to about 1.90 can have a tensile strength of about 0.14 g / denier to about 0.24 g / denier or about 0.15 g / denier to about 0.22 g / denier. The aqueous polyurethane dispersion may also have a milliequivalent carboxylic acid / kg prepolymer of about 150 to about 220, about 155 to about 220, or about 180 to about 190.

[0090] Therefore, the disclosed aqueous polyurethane dispersion can be used to produce molded articles. The aqueous polyurethane dispersion can be applied to a substrate by various processing methods, including but not limited to padding, coating, printing, bonding, or lamination. After application, the aqueous polyurethane dispersion is cured (or otherwise dried) onto the substrate. Curing may include heating the aqueous polyurethane dispersion applied to the substrate to about 150°C to about 170°C for about 30 seconds to about 5 minutes.

[0091] Waterborne polyurethane dispersions can be used alone or in combination with other aqueous dispersions of different polymers. Additionally, waterborne polyurethane dispersions can be crosslinked with selected crosslinking agents, including, for example, polycarbodiimides and polyisocyanates.

[0092] Before being applied to a substrate, the aqueous polyurethane dispersion can be diluted to the desired solids content. The substrate to which the aqueous polyurethane dispersion is applied can be a textile or a nonwoven material.

[0093] Waterborne polyurethane dispersions can be applied directly to substrates and / or as films, tapes, or dried in a variety of selected patterns, such as, but not limited to, dots, shapes like triangles, circles, and rectangles, zigzags, and / or lines, depending on the location requiring stretching and recovery. When applied in a zigzag pattern or in non-parallel or discontinuous lines, the directionality or intensity (or both) of the change in elastic modulus can also be manipulated. Other benefits include improved visual design aesthetics (due to the shape of the applied pattern and the ability to add colorants, reflective agents, or other additives) and the ability to manipulate fabric drape and tactile feel. For example, while solid continuous sheets may produce the greatest increase in modulus, they may feel stiff or papery or noisy when processed. In addition to altering the modulus, using discontinuous, discontinuous, or intermittent patterns can mitigate the stiffness and papery feel.

[0094] Another embodiment is a method for producing molded articles, comprising applying the aqueous polyurethane dispersion disclosed herein to a substrate. The aqueous polyurethane dispersion can be applied to the substrate by padding, coating, printing, bonding, spraying, or laminating. The aqueous polyurethane dispersion can be applied and dried to form a film, band, or dots, shapes, serrations, or lines of a selected pattern on all or part of the substrate where stretching and recovery are required. The method may further include diluting the aqueous polyurethane dispersion prior to application to the substrate, or curing the aqueous polyurethane dispersion onto the substrate.

[0095] Therefore, waterborne polyurethane dispersions and their application methods are particularly suitable for producing items that require all or part of stretching and recovery. These items can provide the added benefits of body shaping and support while offering comfort. These items can be clothing.

[0096] Examples of garments falling within the scope of this disclosure that can be produced using dispersions and methods include, but are not limited to, disposable underwear, bras, bralettes, underwear, swimwear, shaping underwear, vests, hosiery, sleepwear, aprons, wetsuits, ties, scrubs, spacesuits, uniforms, hats, garters, sweatbands, belts, sportswear, coats, raincoats, winter coats, trousers (including jeans), shirts, dresses, crop tops, menswear, and womenswear. Tops, sweaters, corsets, vests, shorts, stockings, knee-high socks, skirts, blouses, aprons, tailcoats, bishats, robes, headscarves, hoods, thoubs, cloaks, garments, wetsuits, kilts, sweatshirts, formal wear, protective clothing, saris, sarongs, skirts, shoe covers, ancient Roman women's coats, suits, tight-fitting jackets, toga, corsets, towels, uniforms, veils, wetsuits, medical compression clothing, bandages, suit linings, belts, and all components thereof. In some embodiments, clothing is bras, corsets, swimwear (for men or women), shaping clothing, or sportswear (including leggings, sports bras, shorts, and tops).

[0097] Aqueous polyurethane dispersions or molded articles can be applied in a predetermined shape to selected areas of a garment. Alternatively, the aqueous polyurethane dispersion or molded article can be applied throughout the garment. The aqueous polyurethane dispersion or molded article can be applied to seams or support areas of a garment according to the following disclosures: U.S. Patent Application No. 12 / 354,030, filed January 15, 2009, entitled Garment With Altered Stress Profile; U.S. Patent Application No. 15 / 161,749, filed May 23, 2016, entitled Garment With Altered Stress Profile; and U.S. Application No. 15 / 496,432, filed on the same date as this application (April 25, 2017), entitled Garment Incorporating Aqueous Polyurethane Dispersions Having Altered Stress Profile, both of which are incorporated herein by reference in their entirety.

[0098] After application of the waterborne polyurethane dispersion or molded article, the garment exhibits improved moisture delivery, comfort, and a lighter weight and feel (e.g., when seam panels are eliminated) compared to conventional garments of the same type that do not contain the waterborne polyurethane dispersion or molded article. Furthermore, unlike some conventional garments with additional seams, stitching, or adhesive panels and / or layers of material to produce improved retention, the waterborne polyurethane dispersion or molded article of this disclosure can be applied directly to the fabric or material of the garment to produce retention, thereby eliminating the need for additional seams, panels, and materials.

[0099] In bras or corsets (wireless bras), waterborne polyurethane dispersions or molded articles may be applied to the lower part of the cups for support and comfort, to the central part for elegance, to the sides for shaping, or any combination thereof.

[0100] In one embodiment, the aqueous polyurethane dispersion or molded article may be applied to the chest, abdomen, thighs, buttocks, or any combination thereof of swimwear, sportswear, or shapewear. In another embodiment, the aqueous polyurethane dispersion or molded article may be applied to the calves, arms, front chest, chest, abdomen, thighs, buttocks, or any combination thereof of sportswear or shapewear. It has been found that selective placement and application of small amounts of the aforementioned aqueous polyurethane dispersion to clothing results in significant effects and outcomes on the human body (e.g., in terms of shape, comfort, and / or support structure) in the areas where the aqueous polyurethane dispersion is applied.

[0101] When aqueous polyurethane dispersions or molded articles are applied to swimwear, the swimwear exhibits improved chlorine resistance. Surprisingly, this improved chlorine resistance is achieved without the incorporation of additives known in the art for improving chlorine resistance, such as mineral additives, like mixtures of orthorhombic marble and hydromagnesite, as disclosed in U.S. Patent 5,626,960, which is incorporated herein by reference in its entirety. Without being theoretically limited, it is believed that the improved chlorine resistance is achieved due to the slow film rupture and abrasion of the present invention. Furthermore, after exposure to a chlorinated environment, the modulus of garments with applied aqueous polyurethane dispersions or molded articles (or the fabric resilience due to the elastic properties of the applied dispersion) remains substantially constant, even after approximately 30, 40, 60, 100, 180, or 200 hours in a chlorinated environment. The chlorinated environment may have a pH of approximately 7.5, a chlorine concentration of approximately 3.5 ppm, and a temperature of approximately 25°C. "Basically constant" means that after the initial descent over the first ten hours to a specified time, the percentage change in modulus of a 40% stretched fabric does not exceed approximately 15% or approximately 10%. Although the absolute value of the force required to stretch the fabric (which may also be referred to as modulus enhancement or retention) decreases over time, its rate of decrease is approximately the same as that of the fabric below. Therefore, retention remains substantially constant.

[0102] Surprisingly, after 220 hours in a chlorinated environment, the retention (or fabric strength in grams) decreased at a rate equal to that of the chlorine-resistant spandex in the underlying fabric. This occurred despite the waterborne polyurethane dispersion containing no additives that provide industrial protection for segmented polyurethanes such as spandex. Of course, those skilled in the art will know that chlorine resistance can be enhanced in other ways by adding known additives that impart the aforementioned properties.

[0103] It should be understood that the swimsuits discussed regarding improved chlorine resistance are made of high-quality fabric that remains intact after 220 hours in a chlorinated environment. Example

[0104] Representative embodiments of this disclosure will be described with reference to the following examples illustrating the principles and practices of this disclosure. The scope of this disclosure is not to be limited in any way to these representative embodiments. In these embodiments, the following materials are used: Table 1 When noted, the following analytical methods are used in the examples below: 1) titration method; 2) microwave method; 3) Brookfield viscosity, RV spool method #3 / 10 rpm @25°C. The titration method for determining the isocyanate percentage (%NCO) of the capped diol prepolymers was performed according to the method described by S. Siggia, “Quantitative Organic Analysis via Functional Group,” 3rd Ed., Wiley & Sons, New York, pp. 559-561 (1963), using potentiometric titration. The concentration of solids in the dispersion was determined using a LABWAVE 9000 microwave solids analyzer. The viscosity of the dispersion was determined using a Brookfield viscometer.

[0105] Example 1: Preparation of prepolymer without 1-hexanol Polyurethane prepolymers were prepared using polytetramethylene ether glycol, aliphatic diisocyanates such as PICM (4,4'-methylenebis(cyclohexyl isocyanate), hydrogenated form of 4,4'-MDI), and diols containing sterically hindered carboxylic acid groups. More specifically, the prepolymers were prepared using the following components and unit quantities: Table 2 The reaction to prepare the prepolymer is carried out in an anhydrous, nitrogen-covered atmosphere to avoid side reactions.

[0106] In this embodiment, a 30-gallon reactor, jacketed with hot water and equipped with a stirrer, is used. The reactor is heated to approximately 55°C. A predetermined weight of molten Terathane® 1800 diol is added to the reactor. Then, under nitrogen cover, DMPA solid powder is added to the reactor with stirring and circulation until the DMPA solid particles are dispersed and dissolved in the diol.

[0107] Molten PICM was then added to the reactor with continuous stirring, and the end-capping reaction was carried out at 90°C for 240 minutes while still being stirred continuously. The resulting viscous prepolymer was then sampled, and the extent of reaction was determined by titration to measure the weight percentage (%NCO) of the isocyanate groups in the prepolymer. Assuming a diol MW of 1800, the theoretical value of %NCO after the reaction was complete was 2.97. If the determined %NCO value was higher than the theoretical value, the reaction should be allowed to continue until the theoretical value was reached or the %NCO value became constant. Once the reaction was determined to be complete, the prepolymer temperature was maintained between 85°C and 90°C.

[0108] Example 2: Preparation of aqueous polyurethane dispersion using the prepolymer of Example 1 The aqueous polyurethane dispersion was prepared using a rotor / stator high-speed disperser by incorporating the prepolymer from Example 1. The prepolymer prepared in Example 1 was directly transferred to the disperser head and dispersed under high shear force in deionized water containing surfactants, neutralizers, antioxidants, and foam control agents. Slightly more prepolymer than required for the dispersion formulation was needed to compensate for losses in the delivery lines and reactor.

[0109] The components used to prepare the dispersion and the composition of the aqueous polyurethane dispersion are shown in Table 3 below.

[0110] Table 3 In preparing a typical batch of 100 kg of aqueous polyurethane dispersion, Dowfax 2A1 surfactant (1.2652 kg), antioxidant Irganox 245 (0.6051 kg), and foam control agent BYK-012 (0.1265 kg) were mixed and dissolved in deionized water (54.8093 kg). Five minutes before adding the prepolymer, a triethylamine neutralizer (0.783 kg) was added to the above water mixture. While maintaining a high-speed dispersion, the prepolymer (41.4109 kg) was added to the water mixture at a temperature between 85 and 90 °C. The rate of prepolymer addition (typically about 1.5 kg / min or about 30 minutes) should be controlled to allow for the formation of a homogeneous dispersion, and the temperature of the dispersion should be maintained between 40 and 45 °C. Once the prepolymer addition was complete, mixing continued for 60 minutes. Next, add the thickener Tafigel PUR 61 (1.00 kg) and mix for another 60 minutes. Stir the resulting dispersion continuously at low speed in a container for 8 hours (or overnight) to remove foam and ensure the reaction is complete. The final dispersion typically contains approximately 42% solids, has a viscosity of approximately 4000 centipoise, and a pH range of 7.0–8.5.

[0111] The dispersion is then filtered through a 100-micron bag filter to remove large particles before being packaged for shipment. It is recommended to use 55-gallon metal drums lined with polyethylene for shipping the dispersion.

[0112] The final product specifications are determined as shown in Table 4.

[0113] Table 4 Example 3: Preparation of prepolymer from 1-hexanol Polyurethane prepolymers were prepared using polytetramethylene ether glycol, 1-hexanol, aliphatic diisocyanates such as PICM (4,4'-methylenebis(cyclohexyl isocyanate), hydrogenated form of 4,4'-MDI), and diols containing sterically hindered carboxylic acid groups. Table 5 lists the components and unit quantities used to prepare the prepolymers.

[0114] Table 5 The reaction to prepare the prepolymer is carried out in an anhydrous, nitrogen-covered atmosphere to avoid side reactions.

[0115] In this embodiment, a 30-gallon reactor, jacketed with hot water and equipped with a stirrer, was used. The reactor was heated to approximately 55°C. A predetermined weight of molten Terathane® 1800 diol was added to the reactor. Next, 1-hexanol was added. Then, under nitrogen cover, DMPA solid powder was added to the reactor with stirring and circulation until the DMPA solid particles were dispersed and dissolved in the diol.

[0116] The molten PICM was then loaded into the reactor with continuous stirring, and the end-capping reaction was carried out at 90°C for 240 minutes while still being stirred continuously. The resulting viscous prepolymer was then sampled, and the extent of reaction was determined by titration to measure the weight percentage (%NCO) of the isocyanate groups in the prepolymer. Assuming a diol MW of 1800, the theoretical value of %NCO after the reaction is complete is 2.80. If the determined %NCO value is higher than the theoretical value, the reaction should be allowed to continue until the theoretical value is reached or the %NCO value becomes constant. Once the reaction is determined to be complete, the prepolymer temperature is maintained between 85°C and 90°C.

[0117] Example 4: Preparation of aqueous polyurethane dispersion using the prepolymer of Example 3 The aqueous polyurethane dispersion was prepared using a rotor / stator high-speed disperser by incorporating the prepolymer from Example 3. The prepolymer prepared in Example 3 was directly transferred to the disperser head and dispersed under high shear force in deionized water containing surfactants, neutralizers, antioxidants, and foam control agents. Slightly more prepolymer than required for the dispersion formulation was needed to compensate for losses in the delivery lines and reactor.

[0118] Table 6 lists the components used to prepare the waterborne polyurethane dispersion and the composition of the waterborne polyurethane dispersion.

[0119] Table 6 In preparing a typical batch of this 100 kg dispersion, Dowfax 2A1 surfactant (1.2652 kg), antioxidant Irganox 245 (0.6051 kg), and foam control agent BYK-012 (0.1265 kg) were mixed and dissolved in deionized water (54.8083 kg). Five minutes before adding the prepolymer, triethylamine neutralizer (0.7866 kg) was added to the above water mixture. While maintaining a high-speed dispersion, the prepolymer (41.4083 kg) was added to the water mixture at a temperature between 85 and 90 °C. The rate of prepolymer addition (typically about 1.5 kg / min or about 30 minutes) should be controlled to allow for the formation of a homogeneous dispersion, and the temperature of the dispersion should be maintained between 40 and 45 °C. Once the prepolymer addition was complete, mixing continued for 60 minutes. Then, thickener Tafigel PUR 61 (1.00 kg) was added and mixing continued for another 60 minutes. The prepared dispersion is continuously stirred at low speed in a container for 8 hours (or overnight) to remove foam and ensure the reaction is complete. The final dispersion typically contains about 42% solids, has a viscosity of about 4000 centipoise, and a pH range of 7.0–8.5.

[0120] The dispersion is then filtered through a 100-micron bag filter to remove large particles before being packaged for shipment. It is recommended to use 55-gallon metal drums with heated lids and polyethylene liners for shipping the dispersion.

[0121] The final product specifications are shown in Table 7.

[0122] Table 7 Example 5: Comparison of Whiteness Retention Rate Experiments were conducted to compare the whiteness retention (or “non-yellowing”) of the aqueous polyurethane dispersions of this disclosure with other dispersions. For each dispersion, samples were prepared by casting a film onto a Mylar sheet using a 10-mil knife and then drying it in a nitrogen oven. The film samples were exposed to different conditions, and whiteness CIE data were collected after each exposure period. The exposure conditions were heat (195°C, 5 minutes), UV (8 hours), fumes (24 hours), and NO2 (24 hours). The heat exposure tests were conducted in heated air in a hot chamber (Werner-Mathis AG, Typ-Nr., LTF 117187). The UV exposure tests were conducted on an Atlas Weather-Ometer® equipped with a xenon arc lamp to simulate sunlight exposure, including ultraviolet light. The NO2 exposure tests were conducted in a nitrogen oxide atmosphere at the Atlas Weather-Ometer®. For each sample, the color of the film before and after exposure was compared; the smaller the decrease in CIE, the better the whiteness retention. Aqueous polyurethane dispersions were prepared according to the compositions shown in Tables 8 and 9, namely Examples 50-59.

[0123] Table 8 Table 9 Comparative dispersions F-70 and F-120 were also prepared according to the compositions shown in Tables 10 to 13. Table 10 Table 11 Note: The amount of Acrysol RM-8W can be adjusted to achieve the desired dispersion viscosity target.

[0124] Table 12 Table 13 Note: The amount of Acrysol RM-8W can be adjusted to achieve the desired dispersion viscosity target.

[0125] The product specifications for these comparative dispersions (F-10 and F-120) are listed in Table 14.

[0126] Table 14 The difference in CIE whiteness index values ​​before and after exposure (i.e., whiteness retention results) is shown in Tables 15 (heat), 16 (UV), and 17 (smog).

[0127] Table 15 Table 16 Table 17 The results of the whiteness retention test are shown in the figure. Figures 1 to 3 The term "invention (average)" refers to the average values ​​of Examples 50-59. For comparison, results were included for TPU films (which are commercially extruded films (Bemis 3410)) and conventionally available Spandex polymer films (LYCRA® T162C), as well as for samples prepared using comparative formulas F-70 and F-120, which are films cast from polyurethane dispersions containing aromatic diisocyanates. Films made from the dispersions of this disclosure (in this invention (average)) exhibit better whiteness retention than films of F-70 and F-120, especially after UV and NO2 exposure. This is expected to be due to the inclusion of an aliphatic diisocyanate (i.e., PICM) in the compositions of this disclosure, rather than the aromatic isocyanate (i.e., Mondur® ML) found in F-70 and F-120.

[0128] Membrane properties are included in Tables 18 and 19.

[0129] Table 18 Table 19 The abbreviations used in Tables 18 and 19 have the following meanings: ●Meq is the milliequivalent of a specific functional group, such as a carboxylic acid or hydroxyl terminal group. For the dispersions of this disclosure, they are expressed as milliequivalents per kilogram of prepolymer or terminal diol (CG).

[0130] ●TP1, TP2, TP301, and TP3 represent the load force. This is the force required to stretch a membrane sample to a certain percentage during a specific stretching cycle (0-300%). TP1 indicates the membrane is stretched to 100%. TP2 indicates the tensile force (also called load force) required to stretch the membrane to 200% in the first 0-300% stretching cycles. TP301 indicates the membrane is stretched to 300% in the first stretching cycle. TP3 indicates the membrane is stretched to 300% in the fifth stretching cycle.

[0131] ●DEC is a pressure decay measurement. This determines the force (5TP300) when the membrane sample is stretched to 300% elongation for the 5th time. When the sample is held at this elongation for 30 seconds, the force will decrease due to stress relaxation. The force data collected after holding for 30 seconds before releasing the tension to recover is 5TM300. DEC = (5TP300 – 5TM300) x 100 / 5TP300 ●TM2 is the recovery force (also known as unloading force) of a membrane sample measured at 200% elongation during the fifth 0 to 300% tensile cycle.

[0132] ●TM1 is the recovery force or unloading force of the membrane sample determined by DEC, measured at 100% elongation during the 5th tensile cycle.

[0133] ●ELO is the elongation at break of the film sample during the sixth cycle.

[0134] ●TEN is the tensile strength or toughness of the film sample during the sixth cycle of stretching.

[0135] ●SET is the unrecovered solidity of the membrane sample after 5 stretching cycles when the recovery force reaches zero.

[0136] ●Because the membrane samples have different thicknesses, the force data are normalized in grams per denier.

[0137] Example 6: Comparison of tensile strength Experiments were conducted to improve the tensile strength of films made from the aqueous polyurethane dispersions of this disclosure, and they were compared with comparative examples F-70 and F-120.

[0138] As shown in Table 20 (which reconfigures the data in Tables 18 and 19 above), under the same composition control parameters, the membranes made from F-70 and F-120 have a better balance of tensile properties (higher load and unload force, higher toughness) than the membranes disclosed herein.

[0139] Table 20 New samples were prepared as shown in Table 21, with variations in the NCO / OH ratio and the amount of monohydric alcohol terminator (Meq monohydric alcohol / kg CG). After testing the tensile strength of these new samples (Examples 60-65), it was found that the tensile properties improved with an NCO / OH ratio exceeding 1.370 and / or a decrease in the amount of terminator (Meq monohydric alcohol / kg CG).

[0140] Table 21 Table 22 Table 23 The Meq acid or monohydric alcohol / kg CG, denier, TP, DEC, TM, ELO, TEN, and SET in Tables 22 and 23 have the same meanings as in Tables 18 and 19 above. Additionally, for example, 1TP100 indicates that the membrane was stretched to 100% or 2 times its original length in the first (0-300%) stretching cycle; 5TP200 indicates that the membrane sample was stretched to 200% or 3 times its original length in the fifth (0-300%) stretching cycle. After five stretching cycles, the membrane sample was stretched again until it ruptured.

[0141] As shown in Tables 22 and 23, the optimal tensile properties of the membranes of this disclosure were found to be achieved by dispersions with an NCO / OH ratio between 1.50 and 1.90, wherein the polymer number-average molecular weight is greater than 10,000. When the NCO / OH ratio is below 1.50, the membrane exhibits insufficient strength (stretching / recovery), and when the NCO / OH ratio is above 1.90, the membrane is brittle and has low elongation.

[0142] Example 7: Improved chlorine resistance Experiments were conducted to evaluate the chlorine resistance of fabrics coated with the aqueous dispersion of this disclosure. The tensile and recovery properties of the fabrics to chlorine exposure were tested according to the following procedure: Chlorinated water conditions (also known as a chlorination environment to simulate a conventional chlorination tank) were created by maintaining a water bath at 25°C, pH 7.5, and an active chlorine level of 3.5 ppm. Fabric samples were then fully immersed in the water bath while being continuously stretched from 0% to 40% at a rate of 24 times per minute for 240 hours. The load (in grams) required to stretch the fabric to 40% was measured and recorded three times per hour. At the end of the 240-hour exposure, the percentage change between the initial load at 0 hours and the loads at other measurement time periods (e.g., after immersion for 180 hours) was calculated. Additionally, after removing the fabrics from the chlorine bath and allowing them to air dry until dry to the touch, the fabrics were visually inspected for damage or the integrity of the coated and dried aqueous dispersion.

[0143] Circular knitted fabric (Fabric A) was produced on a 28GG machine by combining 69% of 40 denier-34 filament nylon 6,6 yarn and 31% of 55 denier spandex (LYCRA® fiber type 275Z). The fabric was made using conventional textile processing. The fabric sample was treated with the aqueous polyurethane dispersion of Example 2 above by conventional screen printing, followed by a curing step in which the fabric was heated to 160°C for 60 seconds.

[0144] The properties and chlorine resistance of the fabrics with and without the application of the aqueous polyurethane dispersion of the present invention are shown in Table 24 below. Specifically, Table 24 shows the loads (or fabric modulus) up to 40% elongation at certain time intervals after immersion in a chlorinated environment. As shown in Table 24, the fabric modulus at 40% elongation increased by 43% (from 505 g to 723 g) after the application and curing of the dispersion. After exposure to chlorine for different test periods, the tensile force in the fabric with the dispersion (“Fabric A PLUS”) was always 30% or higher than that in Fabric A. At 180 hours, the increase in fabric modulus between samples was measured to be 41%, which is almost identical to the initial measurement of 43% at 0 hours. After 180 hours of exposure to chlorination conditions, the modulus of the fabric at 40% elongation increased by 41% (from 320 g to 453 g). This confirms the unexpectedly excellent commercial purpose and use of the waterborne polyurethane dispersion of the present invention in a durable manner to increase modulus in chlorinated environments.

[0145] After 180 hours in a chlorination bath, the absolute values ​​of elongation load for fabric A PLUS and untreated fabric A sample showed the same 63% reduction. This confirms that the fabric properties did not change on a percentage basis between the two samples. In summary, these results are particularly surprising, considering that the dispersion does not contain other techniques, such as those described in U.S. Patent 5,626,960, which are known in the art for improving the resistance of polyurethane-based materials to the degradation of properties upon exposure to activated chlorine. It should be understood that additives, such as those described in U.S. Patent 5,626,960, may also be included if further improvement in performance is desired.

[0146] Table 24: Load for 40% elongation of fabric samples in a chlorinated environment Example 8: Aqueous polyurethane dispersion containing DMAMP Based on the composition shown in Table 25, aqueous polyurethane dispersions were prepared using DMAMP and EDA as neutralizing agents instead of TEA.

[0147] Table 25 The membrane properties of Example 80 were tested. The results are shown in Tables 26 and 27 below, as are the membrane properties of Examples 60, 62, 63, and 64 (which are also shown in Tables 22 and 23 above).

[0148] Table 26 Table 27 As can be clearly seen from the reviews in Tables 26 and 27, membranes prepared using DMAMP have improved tensile properties (higher load and unload forces, and higher toughness) comparable to those prepared using TEA.

[0149] As those skilled in the art will understand, many changes and modifications can be made to the embodiments described herein without departing from the spirit of this disclosure. It is intended that all such changes fall within the scope of this disclosure.

Claims

1. An aqueous polyurethane dispersion comprising: a prepolymer consisting of: a dihydric alcohol; an aliphatic diisocyanate; a monofunctional alcohol; and a diol, wherein the ratio of isocyanate groups in the aliphatic diisocyanate to hydroxyl groups in the dihydric alcohol and diol is 1.50 to 1.90, and the dihydric alcohol is poly(tetramethylene ether) glycol, the aliphatic diisocyanate is 4,4'-methylenebis(cyclohexyl isocyanate), the monofunctional alcohol is 1-hexanol, and the diol is DMPA, and the milliequivalent concentration of carboxylic acid groups per kg of prepolymer (Meq acid / kg CG) ranges from 140 to 250; and a neutralizing agent comprising 2-dimethylamino-2-methyl-1-propanol (DMAMP).

2. The aqueous polyurethane dispersion of claim 1, wherein the dispersion contains less than 0.1% triethylamine (TEA) based on the total weight of the aqueous polyurethane dispersion.

3. The aqueous polyurethane dispersion of claim 1, wherein the milliequivalent concentration of carboxylic acid groups per kg of prepolymer (Meq acid / kg CG) ranges from 140 to 220.

4. The aqueous polyurethane dispersion of claim 3, wherein the milliequivalent concentration of carboxylic acid groups per kg of prepolymer ranges from 150 to 220.

5. A prepolymer consisting of a dihydric alcohol, an aliphatic diisocyanate, a monofunctional alcohol, and a diol, wherein the ratio of isocyanate groups in the aliphatic diisocyanate to hydroxyl groups in the dihydric alcohol and diol is 1.50 to 1.90, and the dihydric alcohol is poly(tetramethylene ether) glycol, the aliphatic diisocyanate is 4,4'-methylenebis(cyclohexyl isocyanate), the monofunctional alcohol is 1-hexanol, and the diol is DMPA, and the milliequivalent concentration of carboxylic acid groups per kg of prepolymer (Meq acid / kg CG) ranges from 140 to 250.

6. The prepolymer of claim 5, wherein the milliequivalent concentration of carboxylic acid groups per kg of prepolymer (Meq acid / kg CG) ranges from 140 to 220.

7. The prepolymer of claim 6, wherein the milliequivalent concentration of carboxylic acid groups per kg of prepolymer ranges from 150 to 220.

8. The prepolymer of claim 7, wherein the milliequivalent concentration of carboxylic acid groups per kg of prepolymer ranges from 155 to 220.

9. The prepolymer of claim 5, comprising at least 60% dihydric alcohol, at least 10% aliphatic diisocyanate, at least 1% diol, and less than 1% 1-hexanol based on the total weight of the prepolymer.

10. The prepolymer of claim 9, comprising at least 70% dihydric alcohol, at least 20% aliphatic diisocyanate, at least 2.2% diol, and less than 0.6% 1-hexanol based on the total weight of the prepolymer.

11. An aqueous polyurethane dispersion comprising the prepolymer of any one of claims 5-10.

12. The aqueous polyurethane dispersion of claim 11, further comprising one or more of water, a neutralizing agent, a surfactant, an antifoam agent, an antioxidant, and a thickening agent.

13. The aqueous polyurethane dispersion of claim 11, further comprising water, a neutralizing agent, a surfactant, an antifoam agent, an antioxidant, and a thickening agent.

14. The aqueous polyurethane dispersion of any one of claims 11-13, containing 30% to 48% of the prepolymer, based on the total weight of the aqueous polyurethane dispersion.

15. The aqueous polyurethane dispersion of any one of claims 11-13, containing 35% to 43% of the prepolymer, based on the total weight of the aqueous polyurethane dispersion.

16. The aqueous polyurethane dispersion of any one of claims 11-13, containing at least 30% of the diol, at least 10% of the isocyanate, and at least 1% of the diol, based on the total weight of the prepolymer.

17. The aqueous polyurethane dispersion of claim 13, containing at least 50% of the water, at least 1% of the surfactant, at least 1% of the thickening agent, less than 1% of the neutralizing agent, less than 1% of the antioxidant, and less than 1% of the antifoam agent, based on the total weight of the aqueous polyurethane dispersion.

18. The aqueous polyurethane dispersion of claim 13 or 17, wherein the neutralizing agent is triethylamine (TEA).

19. A method of producing a shaped article, comprising applying the aqueous polyurethane dispersion of any one of claims 1-4 and 11-18 to a substrate.

20. The method of claim 19, wherein the aqueous polyurethane dispersion is applied to the substrate by padding, coating, printing, bonding, spraying, or laminating.

21. The method of claim 19, further comprising diluting the aqueous polyurethane dispersion before applying to the substrate.

22. The method of claim 19, further comprising curing the aqueous polyurethane dispersion to form a dried aqueous dispersion.

23. The method of claim 19, wherein the dried aqueous dispersion is a film, a tape, or a pattern of dots, shapes, zigzags, or lines.

24. The method of claim 19, wherein the aqueous polyurethane dispersion is applied to the substrate in need of stretching and recovery.

25. The method of claim 19, wherein the substrate is a textile fabric.

26. A shaped article produced by the method of any one of claims 19-25.

27. A shaped article comprising a dried aqueous polyurethane dispersion, the dispersion comprising the prepolymer of any one of claims 5-10.

28. The shaped article of claim 27, wherein the shaped article is a film.

29. The shaped article of claim 28, having a tensile strength of 0.14 to 0.24 grams per denier.

30. The shaped article of claim 29, having a tensile strength of 0.15 to 0.22 grams per denier.

31. The shaped article of claim 29, having a reduction of 30% to 40% in its CIE whiteness index value after exposure to 195°C for five minutes.

32. The shaped article of claim 29 having less than a 2% reduction in its CIE whiteness index value after exposure to UV for 8 hours.

33. The shaped article of claim 29 having less than a 5% reduction in its CIE whiteness index value after exposure to NO2 for 24 hours.

34. An article comprising the shaped article of claim 26.

35. The article of claim 34, wherein the aqueous polyurethane dispersion is applied to a seam or support area of the article.

36. The article of claim 34, wherein the article has improved whiteness retention where the shaped article is applied.

37. The article of claim 34, wherein the article has improved tensile strength where the shaped article is applied.

38. The article of claim 34, wherein the article has improved chlorine resistance where the shaped article is applied.

39. The article of claim 38, wherein the modulus remains substantially constant after exposure to a chlorinating environment for 60 hours.

40. The article of claim 38, wherein the modulus remains substantially constant after exposure to a chlorinating environment for 100 hours.

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