TWI774915B - Environmentally friendly aqueous polyurethane dispersion and preparing method and uses of the same - Google Patents

Abstract

An environmentally friendly aqueous polyurethane dispersion and preparing method and uses of the same are provided. The aqueous polyurethane dispersion is prepared by a method comprising the following steps: (a) subjecting a polyol, hydrophilic group-containing monomer having at least two reactive functional groups, and an aromatic polyisocyanate to addition polymerization to form a polyurethane prepolymer having a hydroxyl group (-OH) at both terminals; (b) subjecting the polyurethane prepolymer having a hydroxyl group at both terminals and an aliphatic polyisocyanate to addition polymerization to form a polyurethane oligomer having an aliphatic isocyanate group (-NCO) at both terminals; and (c) dispersing the polyurethane oligomer having an aliphatic isocyanate group at both terminals into water at a pH greater than 7.0, to form the aqueous polyurethane dispersion.

Description

Environmentally friendly waterborne polyurethane dispersion and its preparation method and application

The present invention relates to an environment-friendly water-based polyurethane dispersion (PUD), a preparation method and application thereof, and more particularly, to a water-based polyurethane dispersion and a preparation method thereof, and a polyurethane precursor comprising the water-based polyurethane dispersion The composition and the application of the polyurethane precursor composition in the preparation of polyurethane.

Polyurethane (PU) can have rubber-like elasticity and flexibility, as well as plastic-like mechanical strength and hardness. Its diverse properties make it widely used in many fields, such as synthetic leather, shoe soles, Adhesives, caulks, fiber modifiers, etc.

In general, the preparation of polyurethane materials is to first perform addition polymerization of polyisocyanates and polyols to form a prepolymer with isocyanate groups (-NCO) at the end, and disperse them in a dispersing medium to form a prepolymer with a suitable operating viscosity. Polyurethane dispersion type. After the polyurethane dispersion is subsequently mixed with the bridging agent, the bridging reaction is carried out by heating and drying, and the medium is removed to form a polyurethane product. According to the type of dispersion medium, the polyurethane dispersion can be divided into solvent-based polyurethane dispersion and water-based polyurethane dispersion (or non-solvent-based polyurethane dispersion). The solvent-based polyurethane dispersion uses organic solvents, such as methyl ethyl ketone, toluene, Dimethylformamide or the like is used as the dispersion medium, and the aqueous polyurethane dispersion uses pure water as the dispersion medium.

Generally speaking, polyurethane products prepared by using aromatic polyisocyanates and polyols have better physical properties (such as abrasion resistance, hardness, etc.), chemical properties (such as solvent resistance, hydrolysis resistance, etc. ) and mechanical properties (such as tensile strength, toughness, etc.). However, the hydrolysis rate of the isocyanate-terminated prepolymer formed by aromatic polyisocyanates and polyols is extremely high, and it is impossible to use pure water as a dispersion medium to form a stable aqueous polyurethane dispersion. Only an organic solvent is used as a dispersion medium. Solvent-based polyurethane dispersion. However, in order to promote the reaction of the solvent-based polyurethane dispersion, it is necessary to add an organotin catalyst to accelerate the reaction, and in order to provide a suitable operating viscosity, a large amount of organic solvent needs to be used, and the content of the organic solvent can account for 70% of the total volume of the dispersion. %, or even 80%, resulting in the release of a large amount of solvent during subsequent drying, which not only wastes resources, but also causes environmental burdens. What's more, the use of tin catalysts and organic solvents has now been strictly restricted by international regulations, or even banned, making solvent-based polyurethane dispersions face the fate of being eliminated.

Therefore, currently commercially available polyurethane dispersions are aqueous polyurethane dispersions prepared by using aliphatic polyisocyanates and polyols. However, although the quality of the aqueous polyurethane dispersion prepared by using aliphatic polyisocyanates is stable, the physical properties, chemical properties (such as solvent resistance and hydrolysis resistance), mechanical properties (such as tensile strength, toughness, etc.) of the obtained polyurethane products ), and heat resistance (such as thermal stability) can not be compared with the polyurethane products made from aromatic polyisocyanates, and even can not meet the requirements of application specifications.

In addition, in the process of using aqueous polyurethane dispersion to manufacture polyurethane products, hot air convection or infrared radiation ovens are currently used for heating and drying, which has disadvantages such as high energy consumption and long drying time. Furthermore, the above heating method is based on the heat conduction from the outside to the inside through the heat source. After drying, the thermal conductivity of the outer layer resin gradually decreases, so that the external heat conduction inward is slowed down, and the outer layer resin forms a high-density film, which affects the internal water vapor. Due to the difference in moisture content and temperature between the inside and outside of the polyurethane, if the drying time is prolonged or the heating temperature is increased, it will not only consume time and energy, but also may cause thermal decomposition of the resin, which will affect the quality of the final product.

In view of the above technical problems, the present invention provides an environment-friendly water-based polyurethane dispersion, wherein water is used as a dispersion medium, which can meet the current environmental protection requirements, and the obtained polyurethane product has excellent physical properties (such as wear resistance, hardness) , chemical properties (such as solvent resistance, hydrolysis resistance), mechanical properties (such as tensile strength, toughness), and heat resistance, can meet the relevant application specifications. In addition, the environment-friendly water-based polyurethane dispersion can be especially dried by microwave radiation, which provides the advantages of saving energy consumption, shortening drying time, improving heating uniformity and product yield. Therefore, the present invention includes the following objects of the invention.

One object of the present invention is to provide a method for preparing an aqueous polyurethane dispersion, comprising: (a) subjecting a polyol, a hydrophilic group-containing monomer having at least two reactive functional groups, and an aromatic polyisocyanate to an addition polymerization reaction to form a polyurethane prepolymer with a hydroxyl group (-OH) at the end; (b) subjecting the hydroxyl-terminated polyurethane prepolymer to an addition polymerization reaction with an aliphatic polyisocyanate to form an aliphatic isocyanate group (-NCO)-terminated polyurethane oligomer; and (c) under the condition that the pH value is greater than 7.0, disperse the polyurethane oligomer with aliphatic isocyanate group at the end in water to form an aqueous polyurethane dispersion.

In some embodiments of the present invention, the equivalent ratio of aromatic polyisocyanate to aliphatic polyisocyanate is 9:1 to 1:9.

In some embodiments of the present invention, the equivalent ratio of the total amount of aromatic polyisocyanate and aliphatic polyisocyanate to polyol is 1.5:1 to 3:1.

In some embodiments of the present invention, the aromatic polyisocyanates are selected from the group consisting of: methylene diphenyl diisocyanate (MDI), modified methyl diphenyl diisocyanate, and toluene diisocyanates , TDI), and their combinations.

In some embodiments of the present invention, the aliphatic polyvalent isocyanate is selected from the group consisting of: isophorone diisocyanate (IPDI), hexane diisocyanate (HDI), perhydrogenated methyl bisphenyl diisocyanate Isocyanate (fully hydrogenated MDI, H ₁₂ MDI), m-xylylenediisocyanate (m-XDI), and combinations thereof.

In some embodiments of the present invention, the polyol is selected from the group consisting of polyester polyols, polyether polyols, polydimethylsiloxane diols, and the like. combination.

In some embodiments of the present invention, the hydrophilic group-containing monomer system having at least two reactive functional groups is selected from the group consisting of: dimethylolpropionic acid (DMPA), sodium bissulfamate, Dimethylolbutanoic acid (DMBA), and combinations thereof.

In some embodiments of the present invention, the above-mentioned method for preparing an aqueous polyurethane dispersion further comprises step (d): adding a chain extender to the aqueous polyurethane dispersion to conduct a bridging reaction with the polyurethane oligomer.

In some embodiments of the present invention, the chain extender is selected from the group consisting of: ethylenediamine (EDA), diethylenetriamine (DETA), tetraethylenepentamine (TEPA), Isophoronediamine (isophoronediamine), m-xylylenediamine (MXDA), 4,4'-diaminodiphenylmethane (4,4'-methylenedianiline, MDA), 4,4'-diphenylene Amino dicyclohexylmethane (4,4'-diaminodicyclohexylmethane, Hydrogenated MDA), polypropylene ether diamine (polyoxypropylenediamine), trimethylhexamethylenediamine (trimethylhexamethylenediamine, TMD), sodium bisamine sulfonate (sodium diaminoethylene sulfonate), and combinations thereof.

Another object of the present invention is to provide an aqueous polyurethane dispersion, comprising water, and a polyurethane oligomer dispersed in the water, wherein the polyurethane oligomer comprises polymerized units derived from polyols and oligomers derived from aromatic polyisocyanates. A polymerized unit, a polymerized unit derived from an aliphatic isocyanate, and a polymerized unit derived from a hydrophilic group-containing monomer having at least two reactive functional groups, and the terminal thereof is an aliphatic isocyanate group.

In some embodiments of the present invention, the aqueous polyurethane dispersion is prepared by the method for preparing the aqueous polyurethane dispersion as described above.

Another object of the present invention is to provide a polyurethane precursor composition, which comprises the above-mentioned aqueous polyurethane dispersion and a post-bridge agent.

In some embodiments of the present invention, the post-bridging agent is selected from the following group: blocked polyisocyanate, polyaziridine, polycarbodiimide, water-dispersed Type polyisocyanate (water-dispersible polyisocyanate), and combinations thereof.

In some embodiments of the present invention, the polyurethane precursor composition further comprises an additive selected from the group consisting of: thickener, leveling aid, defoamer, wetting agent, foaming agent, foam stabilizer, wood fiber Powder, silica gel, barium sulfate, and combinations thereof.

Another object of the present invention is to provide a method for preparing polyurethane, which comprises heating and drying the above-mentioned polyurethane precursor composition to prepare polyurethane.

In some embodiments of the present invention, the above heating drying is performed by microwave irradiation.

Another object of the present invention is to provide a polyurethane, which is prepared by the method for preparing the polyurethane as described above.

In order to make the above objects, technical features and advantages of the present invention more clearly understood, the following is a detailed description of some specific embodiments.

The following will specifically describe some embodiments of the present invention; however, without departing from the spirit of the present invention, the present invention can still be practiced in many different forms, and the protection scope of the present invention should not be limited to the specific embodiments. Implementation style.

As used in this specification (especially in the scope of the appended patent application), "a," "the," and similar expressions should be understood to include both the singular and the plural unless the context dictates otherwise.

Unless otherwise indicated herein, when describing ingredients contained in a solution, mixture or composition in this specification, it is calculated on a dry weight basis, ie, the weight not including water or other solvents.

1. Method for preparing aqueous polyurethane dispersion

The present invention provides a method for preparing aqueous polyurethane dispersion, comprising the following steps: (a) The polyol, the hydrophilic group-containing monomer having at least two reactive functional groups (herein also referred to as "hydrophilic group-containing monomer"), and the aromatic polyisocyanate are subjected to an addition polymerization reaction to form a main chain Polyurethane prepolymers containing aromatic polyurethane resin tough blocks and terminated by hydroxyl groups (-OH) (herein, the hydroxyl terminated polyurethane prepolymers may also be referred to as "PU-OH") ; (b) Addition polymerization of PU-OH and aliphatic polyisocyanates to form polyurethane oligomers terminated with aliphatic isocyanate groups (-NCO) (herein, the polyurethane oligomers terminated with aliphatic isocyanate groups) may also be denoted "PU-NCO"); and (c) Disperse PU-NCO in water under the condition that the pH value is greater than 7.0 to form an aqueous polyurethane dispersion (in this article, the polyurethane dispersion may also be referred to as "PUD"), (d) Optionally, a chain extender can be added to the aqueous polyurethane dispersion to react with PU-NCO to increase the molecular weight and bridging density of the polyurethane oligomer in the aqueous PUD.

Polyols provide the soft segment properties of polyurethane products. When the average molecular weight of the polyol is higher, such as more than 1000, such as 1000 to 3000, the longer the chain length of the soft (polyol) segment between the rigid urethane blocks of the polyurethane product is, the softer the polyurethane product is. the higher the degree. The types of polyols are not particularly limited, and those with ordinary knowledge in the technical field to which the present invention pertains can select them as needed after viewing the description of the present case. For example, polyols with higher hydrophobicity, such as polycarbonate diols or polycaprolactone diols, can be used to provide better water resistance, or Use polysiloxane diol to provide better softness, touch, and hydrophobicity.

Specific examples of polyols include, but are not limited to, polyester polyols, polyether polyols, and polysiloxane diols. The above-mentioned polyols may be used alone or in any combination. Commercially available polyester polyols include products available from UBE Industries under the model names UH-CARB 100, UH-CARB 200, UH-CARB 300, and Eternacoll UH200; available from BASF ) products of the company's models are Sovermol 920 and Sovermol 1006; products purchased from Asahi Kasei Company with models of Duranol T5652 and Duranol T6002; products of Nipponllan 980 N purchased from Nippon Polyurethane Industry; Models CAPA 2201 and CAPA 2200D from Perstorp; Model Stepanpol PD-195 from Stepan; and Models from Kuraray Polybutylene adipate. Commercially available polyether polyols include model CAPA 7201A from Perstorp; PolyMEG 2000 from Lyondell; Sovermol 1052 from BASF product; and the product of model PEG-2000 purchased from Taijie Chemical Company. Commercially available polysiloxane diols include CoatOSil 2400 and CoatOSil 3505 from Momentive; and KF6001 from Shin-Etsu .

The types of aromatic polyvalent isocyanates are not particularly limited, and those with ordinary knowledge in the technical field to which the present invention pertains can select them as needed after viewing the description of the present case. Specific examples of aromatic polyisocyanates include, but are not limited to, methylbisphenyl diisocyanate, modified methylbisphenyl diisocyanate, and toluene diisocyanate. The above aromatic polyvalent isocyanates may be used alone or in any combination. Commercially available aromatic polyisocyanates include Desmodur 2460M from Bayer and Wannate 69015 from Evonik. In the attached examples, methyl diphenyl diisocyanate or modified methyl diphenyl diisocyanate is used.

The hydrophilic group-containing monomer provides the hydrophilic function of PU-NCO, which is an important factor for stabilizing the dispersion of PU-NCO. The hydrophilic group is, for example, carboxyl group (-COOH) and sulfonic acid group, but not limited thereto. The higher the hydrophilic group content, the smaller the average particle size of PU-NCO in the aqueous polyurethane dispersion, for example, can be less than 80 nanometers, the higher the Zeta potential, the better the stability. However, if the content of the hydrophilic group is too high, the water resistance of the produced polyurethane product will be poor. In some embodiments of the present invention, the amount of the hydrophilic group-containing monomer is based on the solid content of the aqueous polyurethane dispersion (PUD), and is 1 to 5 parts by weight of the hydrophilic group-containing monomer per 100 parts by weight, but this The invention is not limited to this.

The type of the hydrophilic group-containing monomer is not particularly limited. In some embodiments of the present invention, monomers having at least two carboxyl groups, monomers having at least two sulfonate groups, or combinations thereof are used. The carboxyl group of the monomer can subsequently undergo a ring-opening reaction with the post-bridge agent to generate a hydrophobic aminoester chemical bond to increase the bridging network structure of the polyurethane product, and the polarity of the sulfonate can promote the prepared Polyurethane products and materials produce molecular polar physical bonds to increase bonding strength. Monomers with at least two sulfonate groups especially include bisamine groups and sodium diaminoethylene sulfonate monomers with dual functions of hydrophilic groups and chain extenders. In addition to increasing hydrophilicity, the monomers can help In addition to dispersing PU-NCO and increasing the solid content that PUD can contain, the bisamine group it possesses can also react with PU-NCO to form a urea-extending group bond, which increases the bridging density and improves heat resistance, solvent resistance and other properties. In a preferred embodiment of the present invention, a monomer with at least two carboxyl groups and a monomer with at least two sulfonate groups are used in combination to obtain better PUD stability and increase the solid content of PUD (which can be determined by 30% by volume to 45% by volume).

Specific examples of the hydrophilic group-containing monomer include, but are not limited to, dimethanol propionic acid (DMPA), sodium bisaminosulfonate, and dimethanol butyric acid. The above-mentioned hydrophilic group-containing monomers having at least two reactive functional groups can be used alone or in any combination. Commercially available hydrophilic group-containing monomers with at least two reactive functional groups include dimethanol propionic acid (DMPA) purchased from Perstorp Company, and non-ionic hydrophilic group products of type Ymer N120; and the model Vestamin A 95 from Evonik.

The types of aliphatic polyisocyanates are also not particularly limited, and specific examples thereof include but are not limited to: isophorone diisocyanate, hexamethylene diisocyanate, perhydrogenated methyl diphenylene diisocyanate, and isoxylylene diisocyanate. The above-mentioned aliphatic polyvalent isocyanates may be used alone or in any combination. Commercially available aromatic polyisocyanates include those available from Evonik under the model names Vestanat IPDI, Vencorex HDI, Vestanat H ₁₂ MDI. In the accompanying examples, isophorone diisocyanate, hexamethylene diisocyanate, or perhydromethylbisphenyl diisocyanate are used.

According to the method for preparing an aqueous polyurethane dispersion according to the present invention, in step (a), in order to effectively form PU-OH, the amount of polyol, hydrophilic group-containing monomer having at least two reactive functional groups, and aromatic polyisocyanate Preferably, the number of equivalents of isocyanate groups is less than the total number of equivalents of hydroxyl groups. In some embodiments of the present invention, the equivalent ratio of isocyanate groups to hydroxyl groups (-NCO/-OH) in step (a) is not greater than 0.8, such as 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45 , or 0.4.

According to the method for preparing the aqueous polyurethane dispersion of the present invention, the dosage ratio of aromatic polyisocyanate and aliphatic polyisocyanate is not particularly limited. Those with ordinary knowledge in the technical field of the present invention can adjust as necessary after viewing the description of the case. For the toughness requirements of polyurethane products, increase or decrease the proportion of aromatic polyisocyanates to increase or decrease the toughness of polyurethane products. In some embodiments of the present invention, the equivalent ratio of aromatic polyisocyanate to aliphatic polyisocyanate is 9:1 to 1:9, such as 9:1, 8:2, 7:3, 6:4, 5: 5, 4:6, 3:7, 2:8, or 1:9, but the present invention is not limited thereto.

According to the method for preparing the aqueous polyurethane dispersion of the present invention, the molecular weight and viscosity of PU-NCO are affected by the ratio of polyisocyanates (including aromatic polyisocyanates and aliphatic polyisocyanates) to polyols. For example, if the equivalent ratio of polyisocyanate to polyol (-NCO/-OH) is lower than 1.5, the molecular weight and viscosity of the resulting PU-NCO are relatively high, and the physical properties of the polyurethane product obtained from this water-based PUD (such as Abrasion resistance, hardness), chemical properties (such as solvent resistance, hydrolysis resistance), mechanical properties (such as tensile strength, toughness), and heat resistance are better. However, high-viscosity PU-NCO has the disadvantage of increasing the stirring torque required for the reaction, and the phase inversion phenomenon during water dispersion will cause the viscosity of PU-NCO to increase sharply, making it difficult to be stirred and dispersed, and some isocyanates The radical (-NCO) will also be hydrolyzed to form an amino product and carbon dioxide gas, and the amino group will continue to react with the unhydrolyzed isocyanate group to generate a bridging reaction of the urea-extending bond, causing the viscosity to increase again, and carbon dioxide will produce foaming The problem is that it is easy to lead to the gelling phenomenon of PU-NCO. Based on this, in some embodiments of the present invention, the equivalent ratio of polyisocyanate to polyol (-NCO/-OH) is not less than 1.5, such as 1.5:1 to 5:1, such as 1.7:1, 2: 1, 2.5:1, 3:1, 3.5:1, 4:1, or 4.5:1, and it is better to adjust the molecular weight of PU-NCO to be about 1.0 to 20,000 units, and the viscosity to be 2000 to 5000 cP, in order to facilitate Quickly stir and disperse at room temperature to form stable water-based PUD. In the following examples of the present invention, the equivalent ratio of polyisocyanate to polyol (-NCO/-OH) is 1.5:1 to 3:1.

According to the method for preparing an aqueous polyurethane dispersion of the present invention, step (c) is carried out under the condition that the pH value is greater than 7.0, preferably greater than 8.0, so as to form a stable aqueous polyurethane dispersion. Therefore, before step (c), a pH adjuster, such as a tertiary amine neutralizer, can be added to the PU-NCO product of step (b) to adjust pH. The type of tertiary amine neutralizer is not particularly limited, and specific examples thereof include but are not limited to: triethylamine (TEA), dimethylethanolamine (DMEA). The above-mentioned tertiary amine neutralizers can be used alone or in any combination. Commercially available tertiary amine neutralizers include the triethylamine, and dimethylethanolamine products available from Solvay.

The type of chain extender used in step (d) is not particularly limited, for example, it can be aliphatic polyamines, more preferably diamine or triamine chain extenders, but this The invention is not limited to this. Specific examples of chain extenders include, but are not limited to: ethylenediamine, divinyltriamine, tetraethylenepentamine, isophoronediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-Diaminodicyclohexylmethane, polypropylene ether diamine, trimethylhexamethylene diamine, and sodium bisaminosulfonate. The above chain extenders may be used alone or in any combination.

Commercially available chain extenders include ethylenediamine products from Polystar Company; Models Chemcure DETA, Chemcure TEPA, Chemcure IPDA, Chemcure MXDA, Chemcure from Cargill Dow Company MDA, and Chemcure Hydrogenated MDA; products from Huntsman under the model numbers Jeffamine D230 and Jeffamine D400; and products available from Evonik under the model numbers Vestamin IPD, Vestamin TMD, and Vestamin A 95 product.

2. Waterborne polyurethane dispersion

The present invention also provides an aqueous polyurethane dispersion, which comprises water and a polyurethane oligomer with an aliphatic isocyanate group at the end dispersed in the water. The waterborne polyurethane dispersion of the present invention is characterized in that the polyurethane oligomer contains, in addition to polymerized units derived from polyols, polymerized units derived from aliphatic isocyanates, and polymerized units derived from hydrophilic group-containing monomers having at least two reactive functional groups In addition to the polymerized units, it especially contains polymerized units derived from aromatic polyisocyanates, and thus the obtained polyurethane products can have more excellent physical properties (such as abrasion resistance, hardness), chemical properties (such as solvent resistance, hydrolysis resistance), mechanical properties (such as tensile strength, toughness), and heat resistance. The waterborne polyurethane dispersion of the present invention can be prepared by the aforementioned method for preparing the waterborne polyurethane dispersion, and the relevant descriptions are as described above, and will not be repeated here.

3. Polyurethane Precursor Composition

The aqueous polyurethane dispersion of the present invention can be used for the preparation of polyurethane products, therefore, the present invention also provides a polyurethane precursor composition. The polyurethane precursor composition of the present invention comprises, the above-mentioned aqueous polyurethane dispersion, a post-bridging agent, and optional additives, wherein the description of the aqueous polyurethane dispersion has been described above, and will not be repeated here.

The post bridging agent can be any reactive functional group (such as the amine group from the chain extender that is not fully reacted, the aliphatic isocyanate group from the hydrolysis of the aliphatic isocyanate group of the polyurethane oligomer) that can be reacted with the reactive functional group contained in the polyurethane oligomer in the aqueous polyurethane dispersion. The resulting amine group, or the carboxyl group from the hydrophilic group-containing monomer) produces a bridging reaction to form a polyurethane product. The type of post-bridging agent is not particularly limited, and can be selected as needed by those with ordinary knowledge in the technical field to which the present invention pertains after viewing the contents disclosed in the description of the present case. Generally speaking, the post bridging agent can be divided into normal temperature stable post bridging agent and normal temperature reactive post bridging agent according to whether it is stable at room temperature. Room temperature stable post-bridging agent, also known as latent curing agent, does not react with the reactive functional groups contained in the polyurethane oligomer in the aqueous polyurethane dispersion under the condition of normal temperature and pH value greater than 8, so It can be mixed with water-based polyurethane dispersion to form a single-liquid polyurethane precursor composition that is stable at room temperature. The room temperature reactive post-bridging agent can react with the reactive functional groups contained in the polyurethane oligomer in the aqueous polyurethane dispersion at room temperature (such as the amine group from the chain extender that is not completely reacted, the aliphatic group from the polyurethane oligomer). The amine group generated by the hydrolysis of the isocyanate group, or the carboxyl group from the hydrophilic group-containing monomer) reacts, so it can be combined with the aqueous polyurethane dispersion to form a two-liquid polyurethane precursor composition.

Examples of post-bridging agents include, but are not limited to: blocked polyisocyanates, polydiethylimine, polycarboxybisimide, and water-dispersed polyisocyanates, wherein blocked polyisocyanates and polydiethylimine are stable at room temperature Post-bridging agent, multi-carbon-based bis-sulfoxide and water-dispersed polyisocyanate are room-temperature reactive post-bridging agents. The above-mentioned post-bridging agents can be used alone or in any combination. In some embodiments of the present invention, post-bridgers that can be used with different reactive functional groups (such as amine groups or carboxyl groups) are used in combination, for example, blocked polyisocyanates and polydiethylimine (which can be used separately) are used in combination. Reaction with amine group and carboxyl group) or combined use of water-dispersed polyisocyanate and polycarbonyl bis-idene (reactive with amine group and carboxyl group respectively) to enhance the properties of polyurethane products through multiple bridging reactions (such as adding polyurethane bridging nets) structure, improve water resistance and heat resistance, etc.).

Commercially available post-bridging agents include products available from Baxenden Chemicals Ltd. under the model names Trixene BI-200, Trixene BI-201, and Trixene BI-220; from Picassian Polymers Models of Picassian XL-701 and Picassian XL-706; products of model CX-100 from DSM; Zoldine XL- from Angus Chemical 29SE; and Coronate AQ130 from Tosoh Corporation, Japan.

In the polyurethane precursor composition of the present invention, there is no particular limitation on the types of additives that can be selected according to needs, and can be any additives known in the art that can adaptably improve the physicochemical properties of polyurethane products. Examples of additives known in the art include, but are not limited to, thickeners, leveling aids, defoamers, wetting agents, foaming agents, foam stabilizers, lignocellulosic powder, silica gel, barium sulfate, and combinations thereof.

4. Method for preparing polyurethane

The polyurethane precursor composition of the present invention can form a polyurethane product after being heated and dried. Therefore, the present invention also provides a method for preparing polyurethane, wherein the polyurethane precursor composition of the present invention is dried by heating to obtain polyurethane.

In a preferred embodiment of the present invention, the heating and drying are carried out by means of microwave irradiation technology. Ionizing electromagnetic radiation (non-ionization electromagnetic radiation). Different from the conventional technology, which uses an oven to heat and dry the water-based polyurethane dispersion, which has the disadvantages of energy consumption, time-consuming and poor yield, the present invention uses water molecules as polar molecules to absorb microwave radiation with high-efficiency electrical/thermal conversion. The drying mechanism of energy, rapid vibration and heat and vaporization can greatly save energy consumption (up to 70% to 80%) and shorten the drying time, making it possible to continuously produce polyurethane, which can greatly improve the production capacity. Rate. In particular, the microwave drying method can solve the problem of uneven heating inside and outside the object to be dried and poor product yield when the oven is heated and dried, and can effectively improve the yield. In addition, the microwave drying can be performed by installing multiple sets of microwave irradiators and waveguides, so that the output power of the microwave irradiation can be adjusted according to the temperature of the dried synthetic skin under the microwave irradiation, which can effectively improve the drying rate and achieve the energy saving goal.

Figure 1 is a schematic diagram of equipment that can be used to carry out the process of the present invention for preparing polyurethane. As shown in Fig. 1, the water-based polyurethane dispersion is supplied by the feeding unit 11, and the water-based polyurethane dispersion is coated on the surface of the release paper 15 by the coating roller 13, and the coated water-based polyurethane dispersion passes along the advancing direction of the release paper. The microwave irradiator 17 is dried to remove moisture and carry out bridging reaction to form dry polyurethane 19, which can then be aged and embossed through an oven 21 and an embossing roller 23 as needed, and can be coiled and stored after cooling.

5. Polyurethane

The present invention also provides a polyurethane prepared by the above-mentioned method for preparing the polyurethane.

6. Example

6.1. Measurement method description

The present invention is further exemplified by the following specific embodiments.

The measuring instruments and methods used in the test examples of the present invention are as follows: Wear resistance test: according to the durability verification specification FTTS-FP-122 for leather materials for automobile seats. Hydrolysis Resistance Test: According to ASTM D 3690 specification. Flexural Resistance Test: According to ASTM D 2097 specification. Tensile Strength Test: According to ASTM 5034-09 specification. Tear Strength Test: According to D5587 specification. Abrasion Abrasion Test: According to ASTM D 4157 specification. Adhesion Test: According to ASTM D0751-06 specification. Waterproof Test: According to AATCC-22 specification. Water Pressure Test: According to AATCC-127 specification. Water repellency test: According to AATCC-22 specification. Solvent resistance (such as 50% ethanol) friction test: Wipe 10 times with 50% ethanol, and observe whether the surface is damaged. If there is no damage, it will pass the solvent resistance friction test. Heat resistance (145 ^o C / 24 hours, or 70 ^o C / 24 hours) test: two pieces of dry polyurethane film are pasted in an oven at 145 ^o C (or 70 ^o C), after 24 hours, if two pieces of dry polyurethane film If they do not stick to each other, they pass the heat resistance test. Water droplet contact angle test: drop pure water on the surface of dry polyurethane, and use a contact angle meter to measure the water droplet contact angle.

6.2. Preparation of Aqueous Polyurethane Dispersion

With the components and proportions shown in Table 1, the water-based PUDs of Examples 1 to 9 were prepared by the method of the present invention for preparing the aqueous polyurethane dispersion. The description of the specific preparation method is as follows.

Firstly, polyol and a hydrophilic group-containing monomer with at least two reactive functional groups (dimethyl alcohol propionic acid (DMPA) (based on the solid content of the aqueous polyurethane dispersion), use 3 to 5 parts by weight per 100 parts by weight DMPA), placed in a stirring reaction kettle, heated to 120 ^o C under vacuum to dissolve the hydrophilic group-containing monomer with at least two reactive functional groups, and at the same time dry the moisture to less than 0.1%, after cooling to room temperature, Slowly add the formula dose of aromatic polyisocyanate to the reactor which is kept stirring, and then gradually heat it up with a water bath, keeping the temperature at 75 ^o C to 85 ^o C, for about 1 to 2 hours, until the isocyanate group (-NCO) Until the absorption peak at 2200 cm ^-1 in the infrared spectrum disappears, the polyurethane prepolymer with aromatic main chain (PU-OH) is completed.

Next, slowly add the formula dose of aliphatic polyisocyanate to the stirred reactor, continue the reaction, and maintain the temperature at 85 ^o C to 90 ^o C for about 2 to 3 hours, until NCO% (isocyanate group %) Below the theoretically calculated value, urethane oligomers (PU-NCO) terminated with aliphatic isocyanate groups are formed.

Use triethylamine to neutralize the carboxylic acid (amine group/acid = 1.1/1.0) in the polyurethane oligomer (PU-NCO) in the reaction kettle and stir evenly, confirm that the pH value is greater than 8.0, then slowly add pure water and Aqueous polyurethane dispersion (PUD) is formed by stirring rapidly (eg, at 1000 rpm), maintaining the temperature below 30 ^o C.

Select the chain extender shown in Table 1 (the amount of the chain extender is 60% of the equivalent of the isocyanate group (-NCO) of the polyurethane oligomer (PU-NCO) in equivalents), under normal temperature and stirring conditions, slowly Slowly add it into the aqueous polyurethane dispersion and keep the temperature below 60 ^o C to generate chain extension and bridging reaction with the polyurethane oligomer (PU-NCO). The ripening reaction of the liquid.

Table 1: Composition of the aqueous polyurethane dispersions of the examples Example Aliphatic polyisocyanate equivalent / aromatic polyisocyanate equivalent Polyol (equivalent ratio) Total equivalent weight of aromatic polyisocyanate and aliphatic polyisocyanate/polyol equivalent Hydrophilic group-containing monomer chain extender 1 6.0/4.0 (I/M) P1 2.0/1.0 H1 E1+E3 2 5.0/5.0 (H/M) P2 2.0/1.0 H1+H2 E1 3 6.0/4.0 (I/M) P5 2.2/1.0 H1+H2 E1+E4 4 8.0/2.0 (H/M) P8 2.5/1.0 H1 E1+E5 5 7.0/3.0 (I/M) P2 2.5/1.0 H1 E1+E7 6 9.0/1.0 (I/Mx) P7+P10 (1:1) 1.5/1.0 H1 E4+E8 7 3.0/7.0 ( _H12 /M) P5+P8 (1:1) 2.0/1.0 H1+H2 E3+E8 8 3.0/7.0 (I/M) P1+P8 (1:1) 2.0/1.0 H1 E6+E8 9 3.0/7.0 (I/M) P1+P8 (1:1) 2.5/1.0 H1+H2 E1+E8

The raw material code of each component in Table 1 is explained as follows: [polyisocyanate] I : isophorone diisocyanate (IPDI); H : hexamethylene diisocyanate (HDI); H ₁₂ : fully hydrogenated methyl diphenyl diisocyanate (H ₁₂ MDI) ); M : methyl diphenyl diisocyanate (MDI); Mx : modified methyl diphenyl diisocyanate [polyol] P1 : CAPA 7201A; P2 : PolyMEG 2000; P3 : Sovermol 1052; P4 : PEG-2000; P5 : UH-CARB; P6 : Sovermol 920; P7 : Duranol T6002; P8 : CAPA 2201; P9 : Sovermol 1006; P10 : CoatOSil 2400; P11 : KF6001 ; Propionic acid (DMPA); H2 : Vestamin A 95 (sodium bisaminosulfonate); H3 : Ymer N120 (non-ionic hydrophilic monomer) [Chain extender] E1 : Ethylenediamine (EDA); E2 : Chemcure TEPA; E3 : Chemcure IPDA; E4 : Chemcure MDA; E5 : Chemcure Hydrogenated MDA; E6 : Jeffamine D400; E7 : Vestamin IPD; E8 : Vestamin TMD

6.3. Preparation and application of polyurethane

According to the method for preparing polyurethane of the present invention, Test Examples 1 to 7 were prepared with the aqueous polyurethane dispersions of Examples 1, 2, 4 to 6, and 9 in Table 1. The specific preparation methods are described below.

Test example 1 : One-component polyurethane precursor composition coating film application

In the aqueous polyurethane dispersion of Example 1, Trixene BI-200 (blocked polyisocyanate) and Picassian XL-706 (polyethyleneimine) were respectively added as potential post-bridging agents, and the dosages were respectively based on the aqueous polyurethane dispersion. In terms of solid content, 2 parts by weight of each of the post-bridging agents are contained in every 100 parts by weight, and then stirred in a closed reaction tank at room temperature for 1 hour to form a stable single-liquid type polyurethane precursor composition. The single-liquid type polyurethane precursor composition was put into a sealed glass bottle 60 ^o C oven for two weeks, and after observation, it was confirmed that the stability was good (the particle size distribution change was less than 10%).

In addition, adjust the thixotropy of the prepared single-liquid type polyurethane precursor composition, then roll-coat it on the release paper to form a polyurethane coating film (3 to 5 microns thickness), and dry it by microwave (power 800 watts; irradiation for 2 minutes) , and then enter the 150 ^o C oven tunnel for 2 minutes, and after cooling the obtained dry polyurethane film to normal temperature, a transparent polyurethane film is obtained. The obtained polyurethane film is confirmed to pass the test of bending resistance test, solvent resistance (50% alcohol) friction test, and heat resistance (145 ^o C/24 hours) test after testing.

Test example 2 : Two-component polyurethane precursor composition coating film application

In the water-based polyurethane dispersion of Example 2, Picassian XL-701 (multi-carbon-based bis-acetylene) and Coronate AQ130 (water-dispersed poly-isocyanate) were added as post-bridging agents, and after stirring for 1 hour, a two-component polyurethane was formed. The precursor composition is ready for use, wherein the dosage of each post-bridging agent is based on the solid content of the aqueous polyurethane dispersion, and every 100 parts by weight contains 2 parts by weight of each post-bridging agent. Then adjust the thixotropy of the polyurethane precursor composition, then roll-coat on release paper to form a polyurethane coating film (3 to 5 microns thickness), dry with microwave (power 800 watts; irradiate for 2 minutes), and then enter 150 ^o C oven tunnel for 2 minutes, and after cooling the obtained dry polyurethane film to normal temperature, a transparent polyurethane film is obtained. The obtained polyurethane film is confirmed to pass the test of bending resistance test, solvent friction resistance test, and heat resistance test (145 ^o C/24 hours) after testing.

Test example 3 : Polyurethane fabric surface waterproof treatment

In the aqueous polyurethane dispersion of Example 4, Trixene BI-200 (blocked polyisocyanate) and Picassian XL-706 (polyethyleneimine) were added as potential bridging agents, respectively, and stirred in a closed reaction tank at room temperature for 1 hour. , to form a stable single-liquid type polyurethane precursor composition, wherein the dosage of each post-bridging agent is based on the solid content of the aqueous polyurethane dispersion, and every 100 parts by weight contains 2 parts by weight of each post-bridging agent.

A thickener (the amount is based on the solid content of the aqueous polyurethane dispersion, 1 part by weight per 100 parts by weight) is added to the single-liquid polyurethane precursor composition to adjust the thixotropic properties. Next, the one-part polyurethane precursor composition was roll-coated on the polyester fabric surface to form a polyurethane coating film (3 to 5 microns thickness), dried by microwave (power 800 watts; irradiated for 2 minutes), and then heated to 150 ^o C Oven tunnel for 2 minutes to obtain fabric transparent waterproof polyurethane film. After drying, the transparent waterproof polyurethane film of the fabric has been tested and confirmed to pass the test of bending resistance, solvent (ethanol) friction test, heat resistance test (145 ^o C/24 hours), and water pressure resistance test.

Test example 4 : Soft microfiber fabric treatment

In the aqueous polyurethane dispersion of Example 5, Picassian XL-701 (multi-carbon-based bis-acylidene) and Coronate AQ130 (water-dispersed poly-isocyanate) were respectively added as post-bridging agents, and stirred for 1 hour to form a two-liquid type. The polyurethane precursor composition, wherein the dosage of each post-bridge-strengthening agent is based on the solid content of the aqueous polyurethane dispersion, and every 100 parts by weight contains 2 parts by weight of each of the post-bridging agents.

Add thickener, leveling aid, and barium sulfate to the two-component polyurethane precursor composition (the amount is based on the solid content of the aqueous polyurethane dispersion, and every 100 parts by weight contains 1 part by weight of parts by weight of leveling aids, and 1 part by weight of barium sulfate), and then adjust the thixotropy. Next, the two-liquid type polyurethane precursor composition was blade-coated on the surface of the ultra-fine polyester fiber fabric to form a polyurethane coating film (3 to 5 microns thickness), dried by microwave (power 1600 watts; irradiated for 2 minutes) and cooled to room temperature After that, a soft microfiber fabric is obtained. The obtained soft microfiber fabric is confirmed to have improved softness after testing, and can pass tests such as bending resistance test, solvent (ethanol) friction test, and heat resistance test.

Test example 5 : Fabric hydrophobic treatment

In the aqueous polyurethane dispersion of Example 6, Trixene BI-200 (blocked polyisocyanate) and Picassian XL-706 (polyethyleneimine) were respectively added as potential post-bridging agents, and stirred in a closed reaction tank at room temperature for 1 hour. Then, a stable single-liquid type polyurethane precursor composition is formed, wherein the dosage of each post-bridging agent is based on the solid content of the aqueous polyurethane dispersion, and every 100 parts by weight contains 2 parts by weight of each post-bridging agent.

Add thickener, leveling aid, and defoamer to the single-liquid polyurethane precursor composition (the amount is based on the solid content of the aqueous polyurethane dispersion, and every 100 parts by weight contains 1 part by weight of thickener, 0.5 parts by weight of a leveling aid and 0.5 parts by weight of a defoamer), adjust the thixotropy, and then scrape it on the surface of the polyester fabric to form a polyurethane coating film (3 to 5 microns thick), the formed polyurethane coating The film was dried by microwave (power 800W; irradiated for 2 minutes) and then entered into a 150 ^o C oven tunnel for 2 minutes to obtain a fabric transparent hydrophobic polyurethane film. After drying, the transparent hydrophobic polyurethane film of the fabric has been tested and confirmed that it can pass the test of solvent (ethanol) friction, heat resistance (70 ^o C/24 hours), adhesion test, bending resistance test, and water drop contact angle test.

Test example 6 : Dry polyurethane synthetic leather

In the aqueous polyurethane dispersion of Example 9, Trixene BI-200 (blocked polyisocyanate) and Picassian XL-706 (polyethyleneimine) were added as potential post-bridging agents, and stirred in a closed reaction tank at room temperature for 1 hour. , to form a stable single-liquid type polyurethane precursor composition, wherein the dosage of each rear bridging agent is based on the solid content of the aqueous polyurethane dispersion, and each 100 parts by weight contains 3 parts by weight of Trixene BI-200 and 1.5 parts by weight. The Picassian XL-706.

Add defoamer, wetting agent, leveling aid, lignocellulosic powder, barium sulfate, and silica gel to one-component polyurethane precursor composition to adjust thixotropy, and then roll coating (coating thickness: 4 cm) on flat fabric On the surface, a polyurethane coating film (3 to 5 microns thickness) was formed. The formed polyurethane coating film was dried by microwave (power 1600 watts; irradiated for 3 minutes), and then entered into a 130 ^o C oven tunnel for 3 minutes. After cooling to room temperature, it was prepared. Waterproof polyurethane synthetic leather. The prepared waterproof polyurethane synthetic leather is confirmed to pass the solvent resistance (ethanol) friction test, heat resistance (70 ^o C/24 hours) test, bending resistance test, and abrasion resistance test after testing.

Test example 7 : Patterned polyurethane synthetic leather

In the aqueous polyurethane dispersion of Example 9, Trixene BI-200 (blocked polyisocyanate) and Picassian XL-706 (polyethyleneimine) were added as potential post-bridging agents, and stirred in a closed reaction tank at room temperature for 1 hour. , to form a stable single-liquid type polyurethane precursor composition, wherein the dosage of each rear bridging agent is based on the solid content of the aqueous polyurethane dispersion, and each 100 parts by weight contains 3 parts by weight of Trixene BI-200 and 1.5 parts by weight. The Picassian XL-706.

Add thickener, wetting agent, foaming agent (the amount is based on the solid content of the aqueous polyurethane dispersion, and contains 15 parts by weight per 100 parts by weight), foam stabilizer (the amount of Based on the solid content of the aqueous polyurethane dispersion, 1 part by weight per 100 parts by weight), wood fiber powder, barium sulfate, and silica gel, and then blade coating (coating thickness: 3 cm) on the surface of the non-woven fabric to form a polyurethane Coating film (3 to 5 microns thickness), the formed polyurethane coating film is dried by microwave (power 4000 watts; irradiation for 2 to 3 minutes), and then enters the oven tunnel, and is heated and dried from 70 ^o C to 140 ^o C. to a micro-foamed state, and then cooled after being rolled and shaped by an embossed roller to obtain a three-dimensional (3D) patterned polyurethane synthetic skin. The prepared polyurethane synthetic leather can pass the test of solvent resistance (ethanol) friction test, heat resistance test (70 ^o C/24 hours), bending resistance test, and abrasion resistance test.

As shown in Test Examples 1 to 7, the polyurethane products prepared by the present invention have excellent physical properties (such as abrasion resistance, hardness), chemical properties (such as solvent resistance, hydrolysis resistance), mechanical properties (such as tensile strength, toughness), and heat resistance.

The above-mentioned embodiments are only used to illustrate the principles and effects of the present invention, and to illustrate the technical characteristics of the present invention, but are not intended to limit the protection scope of the present invention. Any changes or arrangements that can be easily accomplished by those skilled in the art without departing from the technical principles and spirit of the present invention are within the scope of the present invention. Therefore, the protection scope of the present invention is as listed in the appended patent application scope.

11: Feeding unit 13: Coating roller 15: Release paper 17: Microwave irradiator 19: Dry Polyurethane 21: Oven 23: Embossed roller

Figure 1 is a schematic diagram of equipment that can be used to carry out the process of the present invention for preparing polyurethane.

11: Feeding unit

13: Coating roller

15: Release paper

17: Microwave irradiator

19: Dry Polyurethane

21: Oven

23: Embossed roller

Claims (13)

A method for preparing an aqueous polyurethane dispersion, comprising: (a) conducting an addition polymerization reaction of a polyol, a hydrophilic group-containing monomer having at least two reactive functional groups, and an aromatic polyisocyanate to form a hydroxyl group (- OH) polyurethane prepolymer; (b) make the polyurethane prepolymer with hydroxyl at the end and aliphatic polyisocyanate to carry out addition polymerization to form a polyurethane oligomer with aliphatic isocyanate group (-NCO) at the end; ( c) under the condition that the pH value is greater than 8.0, disperse the polyurethane oligomer with an aliphatic isocyanate group at the end in water to form an aqueous polyurethane dispersion; and (d) add a chain extender to the aqueous polyurethane dispersion, To carry out polyurethane chain extension and bridging reaction, wherein the chain extension agent is selected from the following groups: aliphatic polyamine chain extension agent, m-xylylenediamine (m-xylylenediamine, MXDA), 4,4'-diamine 4,4'-methylenedianiline (MDA), and combinations thereof. The method of claim 1, wherein the equivalent ratio of the aromatic polyvalent isocyanate to the aliphatic polyvalent isocyanate is 9:1 to 1:9. The method of claim 1, wherein the equivalent ratio of the total amount of the aromatic polyisocyanate and the aliphatic polyisocyanate to the polyol is 1.5:1 to 3:1. The method of claim 1, wherein the aromatic polyisocyanate is selected from the group consisting of: methyl diphenyl diisocyanate (MDI), modified methyl diphenyl diisocyanate, toluene diisocyanate (toluene diisocyanate) diisocyanates, TDI), and combinations thereof. The method according to claim 1, wherein the aliphatic polyvalent isocyanate is selected from the group consisting of: isophorone diisocyanate (IPDI), hexane diisocyanate (HDI), perhydrogenated methyl bisphenyl Diisocyanate (fully hydrogenated MDI, H ₁₂ MDI), m-xylylenediisocyanate (m-XDI), and combinations thereof. The method of claim 1, wherein the polyol is selected from the group consisting of polyester polyols, polyether polyols, polysiloxane diols, and combinations thereof. The method of claim 1, wherein the hydrophilic group-containing monomer system having at least two reactive functional groups is selected from the group consisting of: dimethylolpropionic acid (DMPA), sodium bissulfamate , dimethylolbutanoic acid (DMBA), and combinations thereof. An aqueous polyurethane dispersion, prepared by the method described in any one of claims 1 to 7. A polyurethane precursor composition, comprising: the aqueous polyurethane dispersion according to claim 8; and a post-bridging agent. The polyurethane precursor composition of claim 9, wherein the post-bridging agent is selected from the group consisting of blocked polyisocyanate, polydiethylimine, polycarboxybisimide, water-dispersible polyisocyanate, and its combination. The polyurethane precursor composition according to claim 9, further comprising an additive selected from the group consisting of: thickener, leveling aid, defoaming agent, wetting agent, foaming agent, foam stabilizer, wood fiber powder, Silica gel, barium sulfate, and combinations thereof. A method for preparing polyurethane, comprising heating and drying the polyurethane precursor composition as described in claim 9 or 10 to prepare polyurethane. The method of claim 12, wherein the heat drying is performed by microwave irradiation.

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