Aqueous polyurethane dispersions and their preparation

Abstract

This invention provides a method for producing prepolymers using solvents that have a better environmental safety and health profile. [Solution] A method for producing a prepolymer containing an acid group, wherein the method is (i) Diisocyanate and, (ii) Diols containing an acid group, (iii) Polyols that do not have acid groups, The method includes the step of bringing the two substances into contact, wherein the contact step is carried out under reaction conditions in a solvent essentially consisting of dipropylene glycol dimethyl ether.

Description

[Technical Field]

[0001] In various embodiments, the present invention generally relates to a method for producing a prepolymer containing an acid group, and water Method for producing a water-based polyurethane dispersion, and aqueous polyurethane dispersion (water-based polyurethane Regarding thane dispersion (PUD). [Background technology]

[0002] Aqueous polyurethane dispersions (PUDs) are used in various coatings, inks, and adhesives. It is well known as an environmentally friendly resin for various applications. Commercial production of polyurethane dispersions is... There are two different methods: the acetone method and the prepolymer method. Acetone is a flammable solvent. Therefore, the prepolymer method is more widely used. In this method, PUD is ji It is made from socianates and polyols. In this two-step method, the presence of a tin catalyst is eliminated. By reacting diisocyanate and polyol under the influence of water, the prepolymer is first formed. Acid groups are produced, for example, 2,2-dimethylolpropionic acid (2,2-dimethylolpropionic acid Polyols containing onic acid (DMPA) react with diisocyanates to form acidic functional groups. It is used to incorporate into a polyurethane (PU) prepolymer. In the second step, The acid is neutralized with an amine, the neutralized PU polymer is dispersed in water, and a polyol or diamine is added. The chain is extended with mine to obtain PUD. In step 1, N-methyl-2-pyrrolidone ( Solvents such as N-methyl-2-pyrrolidone (NMP) have a good affinity for DMPA. Consequently, it has been used for many years to dissolve DMPA during prepolymer synthesis.

[0003] NMP has low volatility, thermal stability, high polarity, aproticity, non-corrosiveness, and good properties. Due to its excellent solubility, it is a particularly important and versatile solvent, and is preferred for the PUD chemical industry. It is a reaction medium. However, NMP has been shown to exhibit reproductive toxicity in animal studies. As a result, NMP recently focused on the registration, evaluation, authorization, and restriction of chemical substances. Evaluation, Authorization and Restriction of Chemical Substances (REACH) It is classified as a potential reproductive toxic substance under the following laws, and is a matter of global safety and regulatory concern. My resolve is growing stronger.

[0004] Therefore, a better environmental, health and safety (EHS) It is desirable to replace NMP with a solvent having a similar profile and solubility characteristics. It can be found to function particularly well in PUD formulations for coating applications. To develop a new emulsifier packaging solution combined with a harmless and non-flammable solvent. That would be preferable. [Overview of the project]

[0005] In one embodiment, the present invention is a method for producing a prepolymer containing an acid group, The method is, (i) Diisocyanate and, (ii) Diols containing an acid group, (iii) The step of contacting a polyol that does not have an acid group with the other, The contact step involves, under reaction conditions, dipropylene glycol dimethyl ether This is carried out in an essential solvent. In one embodiment, the acid group of the diol containing the acid group is a It is a rubonic acid group. In one embodiment, the diol containing the acid group is 2,2-dimethylol It is butanoic acid (2,2-dimethylolbutanoic acid, "DMBA"). In one embodiment, the acid The contact step for forming a prepolymer having the group further includes a metal salt catalyst. In terms of application, the metal salt catalyst is an organotin salt.

[0006] In one embodiment, the present invention provides a three-step method for producing an aqueous polyurethane dispersion (PUD). This is a stepping stone method, and this method is (1) (i) Diisocyanate and, (ii) Diols containing an acid group, (iii) By contacting a polyol without acid groups with a polyol having acid groups A step of forming a polymer, Contacting the dipropylene glycol dimethyl ether under reaction conditions is essential. The formation step is carried out in the target solvent, (2) A step of neutralizing the acidic group of the prepolymer with a base, (3) The step of dispersing the neutralized prepolymer in water. In one embodiment, the acid group of the diol containing the acid group is a carboxylic acid group. So, the diol containing an acid group is 2,2-dimethylolbutanoic acid ("DMBA"). In one embodiment, the contact step for forming a prepolymer having an acid group is a metal It further contains a salt catalyst. In one embodiment, the metal salt catalyst is an organotin salt. In one embodiment, The method further comprises (4) adding a chain extender to a neutralized prepolymer in water. The chain extender is a polyol or a diamine.

[0007] In some embodiments where the acid group-containing diol is 2,2-dimethylolbutanoic acid, the use of dipropylene glycol dimethyl ether as a solvent can advantageously provide improved solubility (especially for 2,2-dimethylolpropionic acid), which results in a more stable film formed by the PUD without precipitated solids . In addition, in some embodiments, the combination of 2,2-dimethylolbutanoic acid and diprop ylene glycol dimethyl ether can provide a film formed from PUD that has a desired hardness .

[0008] In one embodiment, the present invention provides a polyurethane comprising (i) a chain-extended prepolymer containing neutralized acid groups, (ii ) dipropylene glycol dimethyl ether, and (iii) water dispersion. In one embodiment, the prepolymer constitutes 5 to 60 mass perce nt of the polyurethane dispersion. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] [Figure 1]This is a diagram of a simple reaction mechanism for aqueous PUD. The PU polymer is prepared by reacting a diisocyanate with a polyol in the presence of a tin catalyst. 2,2-dimethylolbutanoic acid is a diol used to incorporate a carboxylic acid functional group into the PU prepolymer. In the second step, the carboxylic acid functional group is neutralized with an amine, the neutralized PU polymer is dispersed in water, and the chain is extended with a polyol or diamine to obtain the PUD. In step 1, a solvent is used to dissolve DMBA during prepolymer synthesis. In commercial implementations, NMP is the most widely used solvent for this purpose. In the present invention, the solvent is dipropylene glycol dimethyl ether ("DPGDME"), which is an aprotic glycol ether. [Modes for carrying out the invention]

[0010] definition For the purposes of U.S. patent practice, the content of any referenced patent, patent application, or publication is as follows: In particular, disclosure of definitions (to the extent that they do not contradict any definitions specifically provided in this disclosure) and And with regard to general knowledge in the relevant technical field, all of it is incorporated by reference. (Or the equivalent US version is incorporated by reference.)

[0011] Unless otherwise stated, implied by the context, or not customary in the relevant technical field All parts and percentages are based on weight, and all test methods are as of the filing date of this disclosure. It is the latest model.

[0012] The numerical ranges disclosed herein include a lower limit and an upper limit, from the lower limit to the upper limit. Includes all values. Explicit values ​​(e.g., 1 or 2, or 3-5, or 6 or 7) The included range includes any subrange between any two explicit values ​​(for example, 1 to 1). This includes sub-ranges such as 2, 2-6, 5-7, 3-7, 5-6, etc.

[0013] The terms "comprising," "including," and "having" , and their derivatives, if any additional components, processes, or procedures are specifically used herein. Whether disclosed or not, this is not intended to exclude their existence. To avoid ambiguity, the patent claim is made through the use of the term "comprising". All compositions, unless otherwise stated, whether polymers or otherwise. Furthermore, it may contain any additional additives, adjuvants, or compounds. In contrast, "essentially" The term "consisting of ~" refers to all subsequent columns except those that are not essential to the feasibility. The scope of the term excludes any other components, processes, or procedures. Terms exclude any components, steps, or procedures not explicitly described or enumerated. The term "or" means, unless otherwise specified, that the listed members individually and optionally It refers to a combination of these forms. The use of the singular form includes the use of the plural form, and vice versa.

[0014] Terms such as "prepolymer" are produced from the reaction of diisocyanate and polyol. It means a compound that combines excess diisocyanate with a polyol. It is formed by the following example, diisocyanate isocyanate One of the nate groups (NCO) is one of the hydroxyl groups (OH) of the polyol. The reaction occurs, and the other end of the polyol reacts with another diisocyanate. The resulting prepoly The polymer has isocyanate groups at both ends. The prepolymer is diisocyanate itself. It reacts like a diisocyanate, but has some important differences. Compared to the original diisocyanate, the prepolymer has a larger molecular weight and higher viscosity. It has a lower isocyanate weight content (%NCO) and a lower vapor pressure. [ka] The prepolymer used in the implementation of this invention is a prepolymer into which a carboxylic acid functional group is introduced. To include it, a diol containing an acid group (for example, DMBA or dimethylolpentanoic acid) is required. ) contains one or more units derived from ).

[0015] Terms such as "acid group" and "acid functional group" refer to groups that provide protons, or hydrogen ions, in aqueous solution. This refers to substituents on the monomer, oligomer, or polymer that contribute to the polymer.

[0016] Terms such as "reaction conditions" generally refer to temperature, pressure, reactant concentration, catalyst concentration, and co-catalyst concentration. , monomer conversion rate, product and by-product (or solid) content of the reaction mixture (or aggregate) Diiso refers to other conditions that, in quantity, and / or affect the properties of the resulting product. The reaction conditions for forming prepolymers from cyanates and polyols are relevant to the technical field. These are well known, and they typically require temperatures of 40°C to 150°C, atmospheric pressure, and a nitrogen atmosphere. and the absence of water.

[0017] Terms such as "solvent" refer to a substance that dissolves another substance (i.e., solute) at a molecular level or in Forming a mixture (i.e., solution) that is essentially uniformly dispersed at the on-size level It refers to the substance that can be produced.

[0018] Terms such as "aprotic" refer to solvents that cannot donate protons, for example, G This represents recall ether. Protic solvents are oxygen (such as in the hydroxyl group) or nitrogen. It is a solvent that has hydrogen atoms bonded to an element (such as in an amine group). Generally, it is unstable. Any solvent containing H+ is a protic solvent. Typical protic solvents include DOWANOL (trademark) DPM (dipropylene glycol methyl ether), DOW ANOL (trademark) TPM (tripropylene glycol methyl ether), DOWANOL (Trademark) DPnP (Dipropylene glycol n-propyl ether), DOWANOL ( Trademark) DPnB (Dipropylene glycol n-butyl ether), and DOWANOL ( One example is the trademark TPnB (tripropylene glycol n-propyl ether). Such solvent molecules readily donate protons (H+) to the reagent. Glycol ethers, for example, PROGLYDE (trademark) DMM (dipropylene glycol The dimethyl ether (or DPGDME) does not contain unstable H+. Commercially available aprotic solvents that can be used in the process are used to produce aprotic solvents. It may contain small amounts of residual protic compounds from the manufacturing process. "Small amounts" means Typically, based on the total weight of the aprotic solvent and the protic compound, the aprotic 1% by weight or less, or 0.5% by weight or less, or 0.1% by weight of the protic compound in the solvent This means less than or equal to 0.05% by weight, or less than or equal to 0.01% by weight.

[0019] Terms like "NEET" mean single or undiluted. A solvent containing pyrene glycol dimethyl ether is dipropylene glycol dimethyl This means that ether is the sole component of the solvent.

[0020] Diisocyanate Diisocyanates are aromatic, aliphatic, or alicyclic diisocyanates, or these It can be a combination of two or more compounds. Diisocyanate (OCN-R-NCO) An unrestricted example of the originating constituent units is expressed by the following equation (I): [ka] In the formula, R is an alkylene, cycloalkylene, or arylene group. Representative examples of socianates are U.S. Patent Nos. 4,012,445 and 4,385,133. This can be found in publications No. 4,522,975 and No. 5,167,899.

[0021] A non-limiting example of a suitable diisocyanate is 4,4'-diisocyanato-dife Nylmethane, p-phenylenediisocyanate, 1,3-bis(isocyanatomethyl)- Cyclohexane, 1,4-diisocyanato-cyclohexane, hexamethylene diisocyana Naphthalene, 1,5-naphthalenediisocyanate-3,3'-dimethyl-4,4'-biphenyl Diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, 2,4- Examples include leuene diisocyanate and 4,4'-diisocyanato-diphenylmethane. ru.

[0022] polyol The polyols used in the implementation of this invention include both those having acidic groups and those not having acidic groups. It has a molecular weight (number average) in the range of 200 to 10,000 g / mol. It does not contain acidic groups. A non-limiting example of a suitable polyol is polyetherdiol ("polyether PU"). (produces "polyester PU"), polyester diol (produces "polyester PU"), hydroxy powder Terminal polycarbonate (producing "polycarbonate PU"), hydroxy-terminated polybutadi Ene, hydroxy-terminated polybutadiene-acrylonitrile copolymer, dialkylsiloxy San and alkylene oxides such as ethylene oxide and propylene oxide are hydroxylated. Examples include C-terminated copolymers, natural oil diols, and any combination thereof. In the application method, a single polyol is used. In one embodiment, two or more polyols are used. A combination is used. In one embodiment, depending on the reaction rate and the desired polymer structure, One or more of the aforementioned polyols are amine-terminated polyethers and / or amino-terminated polyols. It can be mixed with libutadiene-acrylonitrile copolymer. For example, glycerol, Triols and other polypropylenes having three or more hydroxyl groups, such as limethylolpropane Polyols can also be used. Further examples of polyols useful in the implementation of the present invention include, U.S., 4, It is found in publication number 012,445.

[0023] In the present invention, the total hydroxyl group equivalents of the polyol compound are preferably 120 to 3. It is 000. If the number of hydroxyl equivalents is within this range, the polyurethane obtained is... Aqueous resin dispersions containing resin can be easily produced, and offer excellent coating properties in terms of hardness. The film is easily obtained. Storage stability of the obtained aqueous polyurethane resin dispersion, coating From the perspective of hardness, drying characteristics, and viscosity characteristics of the coating film obtained through coating. Therefore, the number of hydroxyl group equivalents is preferably 150 to 3000, or 150 to 800, The range is 200-700, or 300-600.

[0024] The number of hydroxyl equivalents can be calculated using the following formulas (1) and (2). The number of hydroxyl equivalents of each polyol is determined by the molecular weight of each polyol and the hydroxyl group of each polyol. It is equal to the number of (excluding phenolic hydroxyl groups) divided by (1), polyol The total number of hydroxyl group equivalents is equal to the total number of moles of M divided by the polyol (2) In the case of polyurethane resin, M in formula (2) is the hydroxyl equivalent of the polyol compound. [Number × number of moles of polyol compound] + [Number of hydroxyl equivalents × number of moles of acid group-containing polyol] ]] is.

[0025] Polyol reacts with diisocyanate to introduce acid functional groups into the prepolymer. At least a portion of it is a diol containing an acidic group, such as a carboxyl group. Diols contain two hydroxyl groups and one or more acidic groups in one molecule. Diols containing this include those containing two hydroxyl groups and one carboxyl group in one molecule. Diols having a group are preferred. Specifically, embodiments of the present invention use 2,2-dimethylol Rubanoic acid or 2,2-dimethylolpentanoic acid is used. In one embodiment, the acid group is included. The diol present is 2,2-dimethylolbutanoic acid.

[0026] Chain extender Chain extenders are not necessary in the implementation of this invention, but may be used if desired. It can be particularly useful as a polyurethane dispersion to make them more stable. In this case, the chain extender can be added to the neutralized prepolymer in water. In this case, the chain extender is polyfunctional, typically bifunctional, and contains 2 to 10 in the chain. It may be an aliphatic linear or branched polyol or amine having up to 1 carbon atom. Examples of polyols such as ethylene glycol, 1,3-propanediol, 1,4- Butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl Glycols and other diols; 1,4-cyclohexanedimethanol; hydroquinone bis- (Hydroxyethyl) ether; cyclohexylenediol (1,4-, 1,3-, and 1,2-isomers), isopropylidenebis(cyclohexanol); diethylene glyco Dipropylene glycol, ethanolamine, N-methyl-diethanolamine, etc. ; and a mixture of any of the above. An example of such an amine is ethylenediamine. ru.

[0027] The prepolymer contains, for example, 1 to 25 weight percent (wt%) of a chain extender component. It is possible.

[0028] catalyst The reaction between diisocyanates and polyols is accelerated by the use of a catalyst. In this embodiment, the catalyst is a metal salt catalyst. An example of a catalyst is a metal salt catalyst with an organic acid or an inorganic acid. Salts of the genus, for example, tin catalysts (e.g., trimethyltin laurate, dibutyrate dilaurate) (e.g., tin), or lead-based catalysts (e.g., lead octoate), and organometallic derivatives, amine N-type catalysts (for example, triethylamine, N-ethylmorpholine, triethylenediamine, etc.) Examples include, but are not limited to, diazobicycloundecene type catalysts. A tin-based catalyst is preferred.

[0029] solvent The solvent used in this invention is dipropylene glycol dimethyl ether, i.e., DP. The solvent used in this invention is essentially made from DPGDME or D It consists of PGDME. DPGDME is a diol containing an acid group (e.g., DMBA). It has high affinity with respect to solubility. As described herein, DPGDME This is useful for the preparation of PU prepolymers and PUDs. It is used in embodiments of the present invention. An example of commercially available DPGDME that can be used is from The Dow Chemical Company. This is PROGLYDE (trademark) DMM, manufactured by y.

[0030] Ethylene glycol monobutyl ether, ethylene glycol monopropyl ether, Diethylene glycol monoethyl ether, propylene glycol methyl ether, dyp Polypropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether Protic solvents such as tel are used in manufacturing processes in which aprotic components are produced in the solvent system. Only as residues, and in small amounts, for example, aprotic and protic compounds in a solvent system Based on the total weight, only 1% by weight or less is used in the DPGDME used in this invention. They can exist in protic solvents, which react quickly with isocyanates, like water. Therefore, it is undesirable.

[0031] Although not essential for the operability of the solvent system of this invention, optional materials that may be included in the solvent system are available. For example, antioxidants, colorants, moisture scavengers, stabilizers, fillers, diluents (e.g., aromatic carbon Examples include hydrogen, but are not limited to these. These materials are used in the preparation of prepolymers. To provide a reaction medium for production, all important effects on the effectiveness of the solvent system are avoided. No. These optional materials are based on a known amount, for example, the weight of the solvent system, 0.1 Used in amounts of 0-5, or 4, or 3, or 2, or 1 weight percent, they are known It is used in this method.

[0032] Use of solvent The solvent used in this invention (DPGDME) is an eco-solvent, that is, DPGD ME does not have toxicological problems related to NMP, or has them at a reduced level. DPGDME is a medium for the preparation of prepolymers as NMP and other polar solvents. It is used in the same style.

[0033] Polyurethane dispersion A method for producing an aqueous polyurethane dispersion (PUD) is (1) the above prepolymer - to prepare, (2) neutralize the acid functional groups of the prepolymer, and (3) add water to the pre This is a three-step method that includes dispersing the polymer. In some embodiments, ...a chain extender (e.g., the polyol or amine chain extender mentioned above) is added to the neutralized prepolymer. A fourth step may be added. In fact, virtually any base can be used as a neutralizing agent. It can be used. Examples include trimethylamine, triethylamine, and triisopropylamine. N, tributylamine, triethanolamine, N-methyldiethanolamine, N- Dimethyl ethanolamine, N-phenyldiethanolamine, dimethylethanolamine Organic amines such as diethylethanolamine, N-methylmorpholine, and pyridine, hydroxyl Examples include inorganic alkali salts such as sodium hydroxide and potassium hydroxide, as well as ammonia. However, it is not limited to these. Organic amines are preferred for neutralizing carboxyl groups, and tertiary amines are preferred. Amines, particularly triethylamine, are more preferred.

[0034] The step of dispersing a polyurethane prepolymer in an aqueous medium is performed using conventional apparatus and techniques. This can be carried out using the following method: For example, the prepolymer is added to a blender of stirred water. The mixture can be mixed until a substantially homogeneous blend is obtained. Alternatively, the stirred prepoly Water may be added to the blender. Mixing is typically done under ambient conditions (23°C and air). It is carried out under pressure. Various additives, such as stabilizers, antioxidants, surfactants, etc., are known. The amount of prepolymer in the dispersion can be varied and used by known methods. The range can vary, but typically the prepolymer is 5-60 or 15-50 of the dispersion. It constitutes a mass percentage.

[0035] In some embodiments, when formed into a film, DMBA is used as the solvent. Polyurethane dispersions according to several embodiments of the present invention, prepared using DPGDME This can be formed into a film having improved hardness. Hardness is measured using Martens hardness. It can be evaluated.

[0036] The following examples illustrate the present invention in a non-limiting manner. [Examples]

[0037] Example 1 - Solubility Evaluation Dipropylene glycol dimethyl ether (DPGDME) and N-methyl-2-pyro Certain diols containing acid groups in lidon (NMP) (2,2-dimethylolpropion The solubility of acids (DMPA) and 2,2-dimethylolbutanoic acid (DMBA) was measured at different temperatures. Evaluate in degrees. The DPGDME used is PROGLYDE (trademark) DMM (The D (ow Chemical Company) The corresponding amount of DMPA or DMBA The following concentrations are evaluated using the solvent (DPGDME or NMP). [Table 1] Fisher brand 24mm black phenolic resin screwdriver with poly liner. Using a 30 ml glass vial with a cap, apply an emulsifier (DMBA or DMBA). PA) should be added in 5% by weight, 10 times, in the solvent (NMP or DPGDME) as specified in Table 1. Add at % by volume, 15% by weight, 20% by weight, and 25% by weight. Stir with a magnetic stirring rod at 500°C. While mixing at rpm, the sample is heated / mixed on a high-throughput heating / mixing station from 25°C. Heat in 10°C increments up to 100°C. Then, remove the sample and take an image to determine its solubility. Record it.

[0038] Some of the main results are summarized in Table 2. A circle (○) indicates complete dissolution. The "×" indicates that it has not completely dissolved. [Table 2]

[0039] The solubility of DMPA was found to be poor in DPGDME. DMPA is NMP When mixed, it was completely soluble at room temperature (25°C) at all concentrations up to 25% by weight. In contrast, DMPA, even at 5% by weight, completely disintegrates into DPGDGME at a high temperature of 95°C. It did not dissolve. DMBA did not dissolve in both solvents tested (NMP and DPGDME). It was found to be soluble at various temperatures and at all concentrations up to 25% by weight. However, DPGDME showed low solubility towards DMPA, but DMBA was dissolved at 75°C. It was found to dissolve completely.

[0040] Example 2 - Polyurethane dispersion The polyurethane dispersion contains either NMP or DPGDME as a solvent and an emulsifier. It was manufactured using DMPA or DMBA. Table 3 shows that DMPA is an emulsifier and DP Table 4 shows the formulations when GDME or NMP is used as the solvent (Comparative Examples A and B), and DMB The formulation shown is when A is an emulsifier and DPGDME is the solvent (Example 1 of the present invention). [Table 3] [Table 4]

[0041] Preparation of Comparative Example A - Polyurethane dispersion using DMPA in DPGDME The prepolymers for polyurethane dispersions (PUDs) use the formulations provided in Table 3. The following is the composition: Poly(tetrahydrofuran) polyol (M n Approximately 1000 ) and poly(tetrahydrofuran) polyol (M n (approximately 2000) at 50℃ Desp Heat in the oven for 1 hour or until they are liquid, then in a glove box Transfer to a glass. Next, add the poly(tetrahydrofuran) polyol to a 40 ml glass. Add to the vial, then add DMPA and DPGDME. Stir the mixture for approximately 30 seconds. Mix in an inter-vortex mixer. Then, 4,4'-methylenedicyclohexyldi Socianate (H 12 Add MDI to the solution and mix with a Flacktek speed mixer. Mix at 3,000 rpm for 1 minute. Add one drop (0.11 microliters) of catalyst. Finally, add dibutyltin dilaurate (DBTDL) and Flacktek Speed ​​Mill Using a mixer, mix the ingredients again at 3,000 rpm for 1 minute. Next, prepolymer Remove the glove box and place it in an 80°C HTR heating / mixing station for 4 hours. After 4 hours, return the sample to the glove box and add triethylamine (neutralizing agent). The sample is then mixed again using a Flacktek speed mixer at 3,000 rpm for 1 minute. Mix. Then, remove the sample from the glove box and add deionized water in a fume hood. Add the following: Shake the sample vigorously by hand for about 2 minutes, then place it in a Flacktek mixer for 3 minutes. Mix at 000 rpm for 1 minute (on the benchtop), three times, or repeat until the sample is homogenized. Return. Next, in the fume hood, ethylenediamine (chain extender) (30% by weight in deionized water) Add ethylenediamine. Using a Flacktek speed mixer, mix at 3,000°F. Mix the sample again at 0 rpm for 1 minute, or until the sample is homogenized. Bench-tap the sample. Leave it on the surface overnight, and prepare the coating the next day.

[0042] Preparation of Comparative Example B - Polyurethane dispersion using DMPA in NMP The prepolymers for polyurethane dispersions (PUDs) use the formulations provided in Table 3. The following is the composition: Poly(tetrahydrofuran) polyol (M n Approximately 1000 ) and poly(tetrahydrofuran) polyol (Mn (approximately 2000) at 50℃ Desp Heat in the oven for 1 hour or until they are liquid, then in a glove box Transfer to a glass. Next, add the poly(tetrahydrofuran) polyol to a 40 ml glass. Add to the vial, then add DMPA and NMP. Stir the mixture for approximately 30 seconds. Mix in a Tex mixer. Then, 4,4'-methylenedicyclohexyl diisothia Nate (H 12 Add MDI to the solution and mix using a Flacktek speed mixer. Mix at 3,000 rpm for 1 minute. Add one drop (0.11 microliters) of catalyst (dilau). Finally, add dibutyltin phosphate (DBTDL) and mix with a Flacktek speed mixer. Using this method, mix the formulation again at 3,000 rpm for 1 minute. Next, mix the prepolymer with Remove from the lobe box and place in an 80°C HTR heating / mixing station for 4 hours. After 4 hours, return the sample to the glove box and add triethylamine (neutralizing agent). Mix the ingredients again using a Flacktek speed mixer at 3,000 rpm for 1 minute. Next, remove the sample from the glove box and add deionized water in a fume hood. The sample is shaken vigorously by hand for about 2 minutes, then placed in a Flacktek mixer and mixed for 3,000 minutes. Mix at 0 rpm for 1 minute (on the benchtop), repeating this process three times, or until the sample is homogenized. Next, in the fume hood, ethylenediamine (chain extender) (30% by weight ethylenediamine in deionized water) Add diamine. Using a Flacktek speed mixer, mix at 3,000 rp. Mix the sample again at m for 1 minute, or until the sample is homogeneous. Place the sample on the benchtop. Leave it overnight, and prepare the coating the next day.

[0043] Preparation of Example 1 of the Present Invention - Polyurethane Dispersion Using DMBA in DPGDME Prepolymers for polyurethane dispersions (PUD) use the formulations provided in Table 4 and are formulated as follows. Poly(tetrahydrofuran) polyol (M n approximately 1000 ) and poly(tetrahydrofuran) polyol (M n approximately 2000) are heated in a Desp atch oven at 50°C for 1 hour or until they become liquid, then transferred to a glove box . Next, the poly(tetrahydrofuran) polyol is added to a 40 mL glass vial, followed by the addition of DMBA and DPGDME. The formulation is mixed with a vortex mixer for approximately 30 seconds. Then, 4,4'-methylenedicyclohexyl diisocyanate (H 12 MDI) is added, and the solution is mixed using a Flacktek speed mixer at 3,000 rpm for 1 minute. One drop (0.11 microliter) of catalyst ( dibutyltin dilaurate - DBTDL) is added finally, and the formulation is mixed again at 3,000 rpm for 1 minute using the Flacktek speed mixer. Next, the prepolymer is removed from the glove box and placed in an HTR heating / mixing station at 80°C for 4 hours . After 4 hours, the sample is returned to the glove box, and triethylamine (neutralizing agent) is added . The sample is mixed again at 3,000 rpm for 1 minute using the Flacktek speed mixer . Then, the sample is removed from the glove box, and deionized water is added in a fume hood . The sample is shaken vigorously by hand for approximately 2 minutes, then placed in the Flacktek mixer and mixing is repeated three times at 3,000 rpm for 1 minute (on a benchtop) or until the sample becomes uniform Return. Next, in the fume hood, ethylenediamine (chain extender) (30% by weight in deionized water) Add ethylenediamine. Using a Flacktek speed mixer, mix at 3,000°F. Mix the sample again at 0 rpm for 1 minute, or until the sample is homogenized. Bench-tap the sample. Leave it on the surface overnight, and prepare the coating the next day.

[0044] To measure the Martens hardness, the coatings of the comparative examples and examples of the present invention described above were used. Prepare as follows. Coating is done at a semi-automatic reactive coating station (Reac It is fabricated using a tive coating station (RCS). The RCS is 1.15mm = 5. Using a metal doctor blade set to a 9 mil wet thickness gap, the PUD is Aluminum substrate (Q-Lab Corporation (Q-Panel), Stock) #SP-105523-Bare Aluminum.025×3.06”×4.72 Coat the 5" square corner (without holes). Comparative examples and examples of the present invention A total of four coatings will be prepared for each. The coatings will undergo adhesion and hardness testing. Before proceeding, allow the diamond to harden at room temperature in a laboratory with 50% relative humidity for 7 days. Using a dotip, a force of 5,000 mN / 10 seconds (creep = 10 seconds) is applied to the microindicator. Use a center. Measure a total of 5 Martens hardness points for each sample.

[0045] A polyurethane dispersion containing DMPA / DPGDME (Comparative Example A) exhibits dispersion and chain extension. It was found that after prolonged exposure, precipitation occurred, leading to the formation of solid particles. This was observed in aluminum substrates. Filtration was required before coating. In comparison, DPGDME contains DMBA. The polyurethane dispersion (Example 1 of the present invention) was stable without any precipitation, however This meant that the coating could be used for further evaluation without any filtration.

[0046] Regarding Martens hardness, the material produced in Example 1 of the present invention (DMBA / DPGDME) The coating is 22 N / mm 2 It showed an average Martens hardness exceeding that of Comparative Example B, but compared to Comparative Example B, The manufactured coating has a load capacity of 13 N / mm². 2 It exhibited an average Martens hardness of less than ____.

[0047] Additional samples from Example 1 of the present invention and Comparative Examples A and B were used to measure turbidity and particle size. Prepare the mixture as described above. Turbidity is measured using a Hach turbidimeter in the range of 0 to 200 NTU. The measurement is performed at room temperature using an 8-drum sample cell. Instrument calibration is performed at G Confirmation was performed using the Elex turbidity standard. Each sample was checked at least to ensure stable readings. Allow to equilibrium for 15 seconds. The results are shown in Table 5.

[0048] Particle size analysis and distribution measurement are performed using a universal liquid module. Beckman Coulter LS 13 310 laser diffraction with ULM This is done using an analyzer. LS 13 310 shows the polarization effect of light scattering at high angles and wavelength dependence. Combined with this, the size limit can be extended to 40nm, almost reaching the theoretical limit. , Polarization Intensity Differential Light Scattering (PID) S) This is called technology. Using PIDS, with LS 13 310 which has ULM. The measured particle size distribution range was 0.017 to 2000 μm. Deionized water in ULM It is used as a liquid medium. A small portion of each sample is transferred to another vial using a pipette, and then desorbed there. Dilute with water to obtain the appropriate concentration of the substance. Then, turn on the PIDs to turn on these samples. The data was collected by passing it through a monochromatic light source (laser) beam. The results are shown in Table 5.

[0049] Comparative Example B (DMPA as emulsifier and NMP as solvent) was homogeneous at 0.085 μm It exhibits particle size, which is beneficial for providing good coating properties. However, As mentioned earlier, NMP is not very desirable from an EHS perspective and is used in many areas. This is prohibited. Comparative Example A (DMPA as emulsifier and DPGDME as solvent) The particle size distribution showed a bimodal pattern at 0.086 μm and 1.985 μm. Large PUD particles In some cases, filtration may be required before application in the coating process, or this P UD formulations may result in insufficient coating properties. Example 1 of the present invention (emulsification The agent DMBA and the solvent DPGDME exhibit a uniform particle size of 0.104 μm. This is similar to the DMPA / NMP method with a particle size of 0.085 μm. (Uniform particles) It provides good PUD coating properties.

[0050] The turbidity measurement for Comparative Example A (DMPA / DPGDME) was slightly higher (180 NTU). This may have been caused by larger PUD particles of 1.985 μm. Turbidity of Comparative Example B (DMPA / NMP) and Example 1 of the present invention (DMBA / DPGDME) The measured value is lower, at approximately 130 NTU, due to the smaller particle size of the PUD. [Table 5]

Claims

1. A method for producing a prepolymer containing an acid group, wherein the method is (i) Diisocyanate and (ii) Diols containing acid groups, (iii) The step of contacting a polyol that does not have an acid group with the (iii) The aforementioned contact step involves using dipropylene glycol dimethyl ether under reaction conditions. A method carried out in a solvent that is essentially derived from the solvent.

2. A three-step method for producing an aqueous polyurethane dispersion (PUD), the The method is, （１） (i) Diisocyanate and (ii) Diols containing acid groups, (iii) By contacting a polyol without acid groups with a polyol having acid groups A step of forming a polymer, The aforementioned contact is performed under reaction conditions from dipropylene glycol dimethyl ether The formation step is carried out in the solvent, (2) The step of neutralizing the acid group of the prepolymer with a base, (3) A method comprising the step of dispersing the neutralized prepolymer in water.

3. The method according to claim 1 or 2, wherein the acid group is a carboxyl group.

4. The diol containing the aforementioned acid group is 2,2-dimethylolbutanoic acid or 2,2-dimethylol The method according to claim 1 or 2, wherein the acid is olepentanoic acid.

5. (4) Further comprising adding a chain extender to the neutralized prepolymer in water, The method according to claim 2, wherein the chain extender is a polyol or a diamine.

6. The contact step for forming the prepolymer having the acid group further involves further using the metal salt catalyst. The method according to any one of claims 1 to 5, including the method described herein.

7. The method according to claim 6, wherein the metal salt catalyst is an organotin salt catalyst.

8. (i) a chain-extended prepolymer containing neutralized acid groups, and (ii) dipropylene glycol A polyurethane dispersion (PUD) containing dimethyl ether and (iii) water.

9. The prepolymer constitutes 5 to 60 mass percent of the dispersion, as described in claim 8. The PUD.

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