CN107674173B - Waterborne polyurethane crosslinking agent and preparation method thereof - Google Patents
Waterborne polyurethane crosslinking agent and preparation method thereof Download PDFInfo
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- CN107674173B CN107674173B CN201710982309.9A CN201710982309A CN107674173B CN 107674173 B CN107674173 B CN 107674173B CN 201710982309 A CN201710982309 A CN 201710982309A CN 107674173 B CN107674173 B CN 107674173B
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Abstract
The invention relates to a waterborne polyurethane crosslinking agent and a preparation method thereof, belonging to the technical field of chemical products. The waterborne polyurethane crosslinking agent is obtained by reacting reaction raw materials including HDI tripolymer, polyethylene glycol, dimethylolpropionic acid and triethylamine at the temperature of 60-80 ℃, and the NCO value of the crosslinking agent obtained through the reaction is 7.5-8.8 wt%. The HDI trimer is prepared by reacting hexamethylene diisocyanate with trimethylolpropane under the protection of an inert gas, and the molar ratio of the hexamethylene diisocyanate to the trimethylolpropane is 3: 1. The waterborne polyurethane crosslinking agent disclosed by the invention is easy to form a waterborne polyurethane crosslinking agent with water dispersion, can be directly added into Waterborne Polyurethane (WPU) to be used as a crosslinking agent of a two-component waterborne adhesive, and can remarkably improve the solvent resistance, impact strength, hardness and peel strength of a waterborne polyurethane coating film.
Description
Technical Field
The invention relates to the technical field of chemical products, in particular to a waterborne polyurethane crosslinking agent and a preparation method thereof.
Background
The Waterborne Polyurethane (WPU) is a new polymer material developed by using a Polyurethane (PU) resin as a base material and water instead of an organic solvent as a dispersant, and may also be referred to as a waterborne polyurethane or a water-based polyurethane. After the successful preparation of polyurethane emulsions in skake in 1943, the development of polyurethane has gone up a new step. Since then, DuPont, Bayer and the like research and develop waterborne polyurethane to prepare industrialized products, the waterborne polyurethane is researched from 1972 in China, and after the 21 st century, the application of the waterborne polyurethane is continuously widened, particularly the increasingly high environmental protection requirement in the world is met, and the industrial development of the waterborne polyurethane is quickened. The waterborne polyurethane not only has the excellent characteristics of high strength, wear resistance and the like of solvent type polyurethane, but also has the characteristics of safe use, no toxicity, convenient operation and processing, non-inflammability, easy storage, no environmental pollution and the like, so that the waterborne polyurethane is widely regarded as a green environment-friendly coating.
Aqueous polyurethanes have been classified into aqueous one-component polyurethanes and two-component aqueous polyurethanes according to the form of use, since the date of birth.
The waterborne single-component polyurethane is an independent substance which takes waterborne polyurethane resin as a base material and water as a dispersion medium, has higher elongation at break and proper strength when being applied earlier, and can be dried at normal temperature, but the waterborne adhesive film has poor water resistance and chemical resistance due to low crosslinking degree, so that the self-thickening property of a simple emulsion, the gloss retention property of the film and a wide application range are poor. To improve the performance, many studies are focused on the modification of the aqueous polyurethane dispersion, which includes the following methods: firstly, selecting multifunctional synthetic raw materials such as polyhydric alcohol, polyamine chain extender and the like; secondly, adding an internal crosslinking agent such as carbodiimide, azomethine and nitrogen heterocyclic compounds, and performing crosslinking reaction in the drying process of the coating; and thirdly, carrying out composite modification on the polyurethane emulsion, including composite modification of epoxy resin, organic silicon and acrylate, such as the appearance of PUA composite emulsion.
The water-based two-component polyurethane consists of a low-viscosity polyisocyanate curing agent (component A) containing-NCO groups and a water-based polyol (component B) containing-OH groups, has low film-forming temperature, excellent mechanical properties (high film hardness, strong adhesive force and good wear resistance), good chemical resistance and weather resistance, combines the advantages of high performance of two-component solvent type polyurethane and low VOC content of water-based paint, and becomes a research hotspot of the paint industry. The water-dispersible polyisocyanate curing agent as an important component of the two-component waterborne polyurethane is an important factor for determining the performance of the coating film. In recent years, the research has entered the key of the substantive stage, and although the corresponding products are available, the application performance is still far from the market requirement.
In the 90 s of the 20 th century, the international green revolution is started, and the paint industry is promoted to greatly advance towards the green direction. With the rapid development of waterborne polyurethanes, waterborne polyurethane crosslinkers are also produced and developed rapidly therewith. The waterborne polyurethane crosslinking agent is applied to the fields of waterborne adhesives, waterborne printing pastes, waterborne printing inks and the like, and can improve the bonding performance and the fastness to washing. The cross-linking agent of the waterborne polyurethane can be used as an external cross-linking agent to be applied to waterborne coatings such as waterborne wood lacquer, waterborne coating and the like, and can keep high gloss, improve hardness, and improve water resistance and solvent resistance. The waterborne polyurethane crosslinking agent is used for a leather finishing agent, so that the leather finishing agent has high gloss, improved hardness and water resistance and strong solvent resistance. The water-based polyurethane cross-linking agent is used as an important component of water-based polyurethane, and the application field of the water-based polyurethane cross-linking agent is expanded along with the expansion of the application range of the water-based polyurethane. The curing agent applied to the two-component waterborne polyurethane is required to have good solubility, miscibility with other resins, enough functionality and reactivity and low toxicity. The curing agent for the two-component waterborne polyurethane can be: unmodified low viscosity polyisocyanates and hydrophilically modified polyisocyanates.
Unmodified polyisocyanates such as HDI biuret, TDI-TMP adducts, can be used directly in solvent borne two-component polyurethane systems. But because they are difficult to mix homogeneously with the hydroxyl component, the possibility of phase separation increases, limiting their use in two-component aqueous systems. To use unmodified polyisocyanates in two-component systems, it is necessary to use isocyanates of low viscosity and reactivity as far as possible, and to dilute the polyisocyanate component with solvents for the purpose of reducing the viscosity, butyl acetate or cyclic carbonates being used, the latter being more capable of imparting small particle sizes and uniform distribution to the dispersion than the former. Fiori et al add a tetramethylphenyl diisocyanate/trimethylolpropane in the ratio of-NCO: -OH 1:1, mixed with a low Tg water dilutable acrylic resin, crosslinkable to film at room temperature. However, this method increases the evaporation of the solvent and does not meet the low VOC requirement. Therefore, unmodified polyisocyanates have great limitations in aqueous polyurethane systems, both from the point of view of environmental protection and also from the point of view of application properties.
The polyisocyanate component can be easily dispersed in the hydroxyl component by an external emulsification method or an internal emulsification method. The external emulsification method is to add an ionic or nonionic emulsifier into a system to wrap the surface of polyisocyanate to realize water dispersibility, but the method has the defects of coarse particles after dispersion, short adaptation period and poor medium resistance of a coating film. At present, an internal emulsification method is mostly adopted, hydrophilic components are used for chemically modifying polyisocyanate, and after the prepared product is mixed with water, a structure with hydrophilic groups facing to a water phase is formed, so that the structure not only protects isocyanate groups, but also ensures that a polyisocyanate dispersed phase is in a stable state due to mutual repulsion of the hydrophilic groups.
Nonionic modification is to introduce hydrophilic groups such as ethylene oxide or propylene oxide into polyisocyanate through chemical reaction to make the polyisocyanate have certain hydrophilicity, usually, polyether polyol is used in many cases, and the modified structure is shown as follows:
hegedus, Renk and the like modify HDI or IPDI isocyanate by using polyethylene glycol monoether, so that the HDI or IPDI isocyanate and polyol can easily form mutually independent heterogeneous disperse systems. Shaffer et al found through studies that the stability of the hydrophilic polyisocyanate increased with increasing polyether length and was also easier to mix with the-OH component. Jacobs et al also found that when using polyethylene glycol monomethyl ether modified HDI isocyanurate, the product produced had good water dispersibility when its relative molecular mass was greater than 120 and less than 1040. Frisch J R et al prepared siloxane-modified water-dispersible polyisocyanates by reacting an amino-containing siloxane compound with a polyisocyanate while introducing a portion of the hydrophilic segment of polyethylene glycol. Compared with common polyisocyanates, the coating film of the formulated coating has faster drying speed, higher hardness and better solvent resistance. However, after the polyisocyanate is modified by the nonionic hydrophilic segment, the hydrophilic segment is introduced, so that on one hand, the-NCO functionality is reduced, and the crosslinking degree of a coating film is reduced; meanwhile, it affects the water resistance of the coating film, so that the application of the coating film in the field with high requirements on the performance of the coating film is limited, and therefore, the research of nonionic modification needs to maintain the water dispersibility of the product on the basis of controlling the introduction of a hydrophilic chain segment. The German Bayer company has a certain breakthrough progress, the waterborne polyisocyanate trimer-second-generation waterborne polyisocyanate is prepared by the reaction of the monohydroxy polyether cyclic polyisocyanate trimer, and compared with the Bayer first-generation waterborne polyisocyanate, the waterborne polyisocyanate reduces the content of hydrophilic groups and increases the number of-NCO functional groups, so that the performance of a coating film basically reaches the level of solvent-based two-component.
The ionic modification is classified into cationic modification and anionic modification. The cation modification is to introduce a substance containing cations into the polyisocyanate and then neutralize the substance to form salt, so that the hydrophilic polyisocyanate can be obtained. The cationic group-containing substances are mainly quaternary ammonium salts, pyridinium salts and imidazolium salts. Such as Schwindt and the like, IPDI tripolymer is reacted with ethoxylated 3-ethyl-3-hydroxymethyl oxetane and N-hydroxyethyl morpholine, and then the obtained product is respectively alkylated and neutralized by dimethyl sulfate and lactic acid to obtain the cationic stable water-based polyisocyanate. However, the method has many steps and high cost, and the presence of the cation can promote the reaction of-NCO and active hydrogen, so that the stability of the system is reduced, and the method is rarely used. Lass et al, which adopts 2-cyclohexylaminoethylsulfonic acid or 3-cyclylaminopropylsulfonic acid to react with polyisocyanate in N, N-dimethylcyclohexylamine as catalyst and neutralizer to obtain sulfonate amine salt modified polyisocyanate, Haeberle et al, which successfully prepares hydrophilic polyisocyanate by reacting isocyanurate (average functional group 3.3) with 2-hydroxyethanesulfonic acid, the reaction route is as follows:
the hydrophilic modification method mainly takes polyether modification as a main method at present, but causes the problem of water resistance and has the tendency of crystallization; while anionic modification has a limitation on pH. Roester et al jointly modify N- (3-trimethoxy silane) diethyl aspartate and polyethylene glycol monomethyl ether to obtain water-dispersible polyisocyanate which can be used in a two-component water-based coating system. Morikawa et al, modify polyisocyanates with hydrophilic polyethylene glycol monoethers and lipophilic alcohols to reduce water sensitivity.
Since the early start of foreign research on waterborne polyurethanes, researchers have made many relevant studies since Jacobs broken the view that polyisocyanates cannot be brought into direct contact with water. Alexander et al prepared water-dispersible polyisocyanates by reacting PAPI with a copolyether of 85 mass percent Ethylene Oxide (EO) and 15 mass percent Propylene Oxide (PO), but the product was poorly water-dispersible and not very stable and precipitated almost immediately upon dispersion in water. On the basis, Rudolf, Jacobs, Lass and the like carry out deep research on the water dispersible polyisocyanate in turn, and lay a foundation for the development of the water dispersible polyisocyanate. H.J. Lars, M. Brahmm, R. Hallparson, etc. modified the polyisocyanate component with monofunctional polyoxyalkylene polyether alcohols to synthesize water-soluble or water-dispersible adhesives. M, Marje, J, Simon and M, Hulman catalyze the reaction of polyisocyanate and polyether alcohol with zinc compound, and synthesize polyisocyanate prepolymer with low viscosity and high NCO content and containing allophanate structure. There are also a number of products on the market today which are water-dispersible polyisocyanate curing agents, such as bayer's hydrophilically modified polyisocyanates containing polyether allophanates (Bayhydur 305) produced by reacting aliphatic polyisocyanates with insufficient quantities of monofunctional polyethylene oxide polyether alcohols, and a series of ionically modified polyisocyanates (Bayhydur 2655) produced by reacting aliphatic polyisocyanates with 3- (cyclohexylamino) -1-propane sulfonic acid (CAPS), and bayer corporation has also gained a Green general public prize in the world (Presidential Green aware) due to its outstanding contribution.
The research in the aspect of China is started late, but a certain achievement is achieved. The water dispersible polyisocyanate is prepared by reacting aliphatic isocyanate with a mixture of polyether monohydric alcohol, dihydric alcohol and trihydric alcohol at 100 ℃. The polyisocyanate tripolymer is modified by polyethylene glycol in consideration of national fragrance and the like, and the polyisocyanate with good water dispersibility is synthesized. Hydrophilic polyether polyol is used for modifying polyisocyanate tripolymer by Von billows, Lu Gulin, Raney and the like to prepare the water dispersible polyisocyanate. Zhangdongyang, Zhou Ming et al grafted with polyethylene glycol monomethyl ether with molecular mass of 400-600-one and aliphatic polyisocyanate to obtain the product with good dispersibility in the coating. Since the last 90 s Jacobs synthesized a water dispersible polyisocyanate, making possible the use of two-component polyurethanes. A lot of research has been conducted by many foreign scientists and the industrialization of the products of the aqueous polyisocyanate curing agents has been achieved. The research of the domestic water-based polyisocyanate curing agent starts at the end of the 90 th generation of the 20 th century, and the preparation of a plurality of water-based polyisocyanate curing agents is also reported after the exploration of the twenty years, and dozens of related scientific and technological documents and patents are published. However, most of them imitate the reports of foreign patents and literatures, and have no innovative method or process. Moreover, the product really forms little scale production, and a nonionic modification method is mostly adopted. However, polyether substances are usually selected for the nonionic modification, and in order to ensure good hydrophilicity, a large amount of polyether substances are often added, which leads to the defects that after hydrophilic modification, the affinity of polyisocyanate with water is improved, the chance of side reaction with water is increased, and the drying time of a coating film is long, the hydrophilicity of the coating film is good, and the water resistance is poor.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention aims to provide a waterborne polyurethane crosslinking agent and a preparation method thereof.
In order to achieve the above object, the first aspect of the present invention employs the following technical solutions:
a preparation method of a waterborne polyurethane crosslinking agent is characterized by comprising the following steps: the HDI/PDI/.
The HDI trimer is prepared by reacting hexamethylene diisocyanate with trimethylolpropane under the protection of an inert gas, and the molar ratio of the hexamethylene diisocyanate to the trimethylolpropane is 3: 1.
Wherein the molecular weight of the polyethylene glycol is 600-1000.
Wherein the addition amount of the polyethylene glycol is 12-30 wt% of trimethylolpropane, preferably 15-25 wt%, and more preferably 19 wt%.
Wherein the addition amount of the dimethylolpropionic acid is 3.2-4.0 wt% of trimethylolpropane, and the molar ratio of triethylamine to dimethylolpropionic acid is 1: 1.
the waterborne polyurethane cross-linking agent is obtained by reacting HDI tripolymer, polyethylene glycol, dimethylolpropionic acid and triethylamine at 60-80 ℃; the molecular weight of the polyethylene glycol is 600-1000, the addition amount of the polyethylene glycol is 12-30 wt% of trimethylolpropane, the addition amount of dimethylolpropionic acid is 3.2-4.0 wt% of trimethylolpropane, and the molar ratio of triethylamine to dimethylolpropionic acid is 1: 1.
the waterborne polyurethane cross-linking agent is obtained by reacting HDI tripolymer, polyethylene glycol, dimethylolpropionic acid, tetramethylguanidine and triethylamine at 60-80 ℃; the molecular weight of the polyethylene glycol is 600-1000, the addition amount of the polyethylene glycol is 12-30 wt% of trimethylolpropane, the addition amount of dimethylolpropionic acid is 3.2-4.0 wt% of trimethylolpropane, the addition amount of tetramethylguanidine is 0.5-1.3 wt% of trimethylolpropane, and the molar ratio of triethylamine to dimethylolpropionic acid is 1: 1.
the second aspect of the invention also relates to an aqueous polyurethane crosslinking agent prepared by the preparation method, wherein the aqueous polyurethane crosslinking agent is a clear and transparent liquid with the appearance, the solid content of 50 +/-2%, the pH value of 6-7 and the viscosity of 300-800 mPa & S.
The invention also relates to a waterborne polyurethane crosslinking agent dispersion liquid which is obtained by stirring and dispersing the waterborne polyurethane crosslinking agent and deionized water, and the stable period of NCO content in the emulsion is 6-8 hours.
Compared with the closest prior art, the waterborne polyurethane crosslinking agent and the preparation method thereof have the following beneficial effects:
the waterborne polyurethane crosslinking agent disclosed by the invention is easy to disperse with water to form a waterborne polyurethane crosslinking agent, can be directly added into Waterborne Polyurethane (WPU) to be used as a crosslinking agent of a two-component waterborne adhesive, can obviously improve the solvent resistance, impact strength and hardness of a waterborne polyurethane coating, has high peel strength, and is close to the performance of a solvent-type two-component polyurethane coating.
Drawings
FIG. 1 is a schematic diagram of a preparation process of the waterborne polyurethane crosslinking agent of the present invention.
FIG. 2 is an infrared spectrum of HDI trimer and HDI trimer modified with PEG 600.
Detailed Description
The aqueous polyurethane crosslinking agent and the preparation method thereof of the present invention will be further described with reference to specific examples, so as to more completely and clearly illustrate the technical scheme of the present invention.
The preparation process of the waterborne polyurethane crosslinking agent is shown in figure 1 and is prepared in a reaction vessel (such as a four-mouth bottle) provided with a thermometer, a reflux condenser and a stirrer. Heating Hexamethylene Diisocyanate (HDI) and acetone in a four-mouth bottle to 30-50 ℃ under the condition of N2Adding metered trimethylolpropane under the protection condition to obtain HDI tripolymer, then dropwise adding PEG, DMPA and TEA, reacting for 3-4 h at the temperature of 60-80 ℃, detecting the NCO value, cooling and discharging after the NCO value is qualified.
The basic preparation route of the waterborne polyurethane crosslinking agent is as follows:
HDI isocyanate and trimethylolpropane react to generate HDI tripolymer A:
② the salifying reaction of dimethylolpropionic acid and triethylamine obtains salified product B:
③ reacting HDI tripolymer A with salifying product B to generate anionic cross-linking agent:
reacting HDI tripolymer A with polyethylene glycol to generate a nonionic cross-linking agent:
the analytical test method adopted in the preparation process of the waterborne polyurethane crosslinking agent mainly comprises the following steps:
infrared Spectroscopy (IR) characterization
The infrared spectrum of the water dispersible polyisocyanate was measured by a Nicolet FTIR-670 type infrared spectrometer, and the change of the functional group was analyzed by the change of the absorption peak.
Determination of the NCO content
Accurately weighing 1.0g of water dispersible polyisocyanate, placing the water dispersible polyisocyanate in a conical flask, transferring into 10mL of di-n-butylamine-n-butyl acetate solution (V (di-n-butylamine): V (n-butyl acetate): 1: 5) by a pipette, slightly shaking to dissolve and mix the polyisocyanate uniformly, standing for 20-30 min, adding 25mL of absolute ethyl alcohol, shaking uniformly, dropping a few drops of bromocresol green indicator with the mass fraction of 0.1%, titrating by using 0.5mol/L of HCl standard solution until the polyisocyanate just turns yellow to be a titration end point, and simultaneously carrying out a blank test.
V0-blank test consumes volume, mL, of HCl standard solution;
V1the volume mL of HCl standard solution consumed by the sample;
CHCl-the concentration of HCl standard solution mol/L;
m-mass of sample, g.
Viscosity measurement
The viscosities of all samples were measured separately using a model NDJ-8S rotational viscometer (Shanghai Seiki Seikagaku Kogyo).
Preparation of the Dispersion
Taking 1g of water dispersible polyisocyanate, adding 10g of deionized water, rapidly stirring for 3min by using a glass rod, standing for 2min to obtain the required dispersion liquid, and observing the dispersion condition in water.
Peeling force
The prepared aqueous polyurethane adhesive was uniformly coated on a polypropylene (CPP) film after corona by using a # 30 wire roller (CPP surface tension 38X 10)-5～40×10-5And N), placing the film in a blast oven at the temperature of 60-80 ℃ for 2-3 min, and compounding the film with another CPP film corona surface under pressure after the water on the film surface is basically completely volatilized. After the compounding is finished, putting the mixture into a 50 ℃ oven for curing for 2 d. Tested on an XLW-1 mental stretcher according to GB/T8808-88, units N/15 mm.
FIG. 2 shows the infrared spectra of HDI trimer prepared by reacting HDI with TMP and HDI trimer modified with PEG 600. As shown in FIG. 2, curve A represents the IR spectrum of the unmodified HDI trimer at 2280cm-1Has obvious characteristic absorption peak belonging to NCO group, which shows that a large amount of NCO groups are arranged in the system, 1690cm-1Is the absorption peak of carbonyl (C ═ O). Curve B is the IR spectrum of the modified HDI trimer. At 2280cm-1The absorption peak belonging to NCO group still exists, but the peak area is obviously reduced, which indicates that a part of NCO groups are reacted and is 3330cm-1And 1550cm-1An absorption peak belonging to N-H appeared, which all indicated that PEG600 had been grafted onto the HDI trimer. At 1110cm-1The peak of (A) is an absorption peak of an ether bond on PEG600, and is 3480cm-1There was no obvious absorption peak, indicating that grafting reaction occurred between PEG600 and HDI trimer.
The water-based polyurethane cross-linking agent molecule mainly comprises polyisocyanate and hydrophilic substance, and the property of the water-based polyurethane cross-linking agent molecule is determined by the property of the polyisocyanate and the kind of the hydrophilic substance. The inventors of the present invention have found that when HDI trimer, PEG and DMPA are selected, the obtained product is clear and transparent in appearance, stable in properties, and good in water dispersibility, and have completed the present invention. The inventor finds that: when PEG600 and PEG2000 are selected as hydrophilic substances, gel appears after the reaction with HDI tripolymer for 2 h; when the DMPA/PEG600 and the DMPA/PEG2000 are selected as the hydrophilic substances, no gel is formed in the experimental process, and the appearance of the product is clear and transparent, which is probably because the PEG600 and the PEG2000 are polyether polyols containing bifunctional hydroxyl groups, when the HDI trimer containing the trifunctional NCO groups is reacted with HDI trimer, because the activities of 3 NCO groups of the HDI trimer molecules are the same, when one NCO group is reacted with an OH group, the activities of the other two NCO groups are slightly reduced due to steric hindrance effect, but the other NCO groups still have higher reactivity and are easy to undergo chain extension reaction with the OH groups on other polyether polyol molecules, and when the 3 NCO groups are reacted with the OH groups, a space network structure with large relative molecular mass is formed, so that the reaction is performed in 2h of gel. DMPA is 2, 2-dimethylolpropionic acid, the molecule of which contains two hydroxyl groups and one carboxyl group, and can be dissolved in water, and can be taken as a hydrophilic substance to be introduced into a molecular system of waterborne polyurethane to greatly improve the water solubility of the waterborne polyurethane. If MPEG (polyethylene glycol monomethyl ether) is selected to replace the PEG of the invention, not only the final product obtained has poor water resistance, but also the reaction product obtained by the MPEG (polyethylene glycol monomethyl ether) and HDI tripolymer, DMPA and the like has partial oil drops in the emulsion when the molecular weight is low, and the emulsion is difficult to disperse because the molecular weight is high and the emulsion is difficult to disperse because the reaction product is agglomerated in the emulsion. If the HDI trimer of the present invention is replaced with the TMP-TDI adduct having the widest application range, a yellow transparent liquid can be obtained by reacting with PEG (PEG600 as an example) and DMPA, but it is not dispersed with water, precipitation is observed at the bottom, and gel generation is observed after leaving for 1 hour. If IPDI trimer is used instead of the HDI trimer according to the invention, a clear and transparent liquid is obtained, but it is not dispersible with water and does not form an aqueous crosslinking agent.
Example 1
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 40 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP (TMP) to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.3 wt%; then heating to 80 deg.C, adding polyethylene glycol 600(PEG600) and dimethylolpropionic acid (DMPA) dropwiseAnd carrying out constant temperature reaction with Triethylamine (TEA) for 3 hours, cooling and discharging, and detecting that the NCO value of the obtained cross-linking agent product is 8.6 wt%, wherein the addition amount of PEG600 is 12 wt% of TMP, the addition amount of DMPA is 3.2 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10 mass ratio into deionized water and dispersed by hand stirring to form a homogeneous white emulsion having an NCO content of about 6 hours.
Example 2
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 42 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 19.6 wt%; and then heating to 75 ℃, dropwise adding polyethylene glycol 600(PEG600), dimethylolpropionic acid (DMPA) and Triethylamine (TEA) to perform constant temperature 3h, cooling and discharging, and detecting that the NCO value of the obtained cross-linking agent product is 8.1 wt%, wherein the addition amount of PEG600 is 15 wt% of TMP, the addition amount of DMPA is 3.6 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10 mass ratio into deionized water and dispersed by hand stirring to form a homogeneous white emulsion having an NCO content of about 6 hours.
Example 3
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 45 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.1 wt%; and then heating to 75 ℃, dropwise adding polyethylene glycol 600(PEG600), dimethylolpropionic acid (DMPA) and Triethylamine (TEA), keeping the temperature constant for 3 hours, cooling and discharging, and detecting that the NCO value of the obtained cross-linking agent product is 8.0 wt%, wherein the addition of the PEG600 is 19 wt% of TMP, the addition of the DMPA is 3.5 wt% of TMP, and the molar ratio of the TEA to the DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10 to addIn ionized water, the emulsion was dispersed by manual stirring into a slightly bluish translucent emulsion having an NCO content of about 6 hours.
Example 4
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 42 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 19.5 wt%; then heating to 70 ℃, dropwise adding polyethylene glycol 600(PEG600), dimethylolpropionic acid (DMPA) and Triethylamine (TEA) to carry out constant temperature 3h, cooling and discharging, and detecting that the NCO value of the obtained cross-linking agent product is 8.0 wt%, wherein the adding amount of PEG600 is 25 wt% of TMP, the adding amount of DMPA is 3.6 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10 mass percent was added to deionized water and the emulsion was dispersed by hand stirring to a light blue clear emulsion having an NCO content stabilization period of about 6 hours.
Example 5
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 42 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 19.5 wt%; then heating to 70 ℃, dropwise adding polyethylene glycol 600(PEG600), dimethylolpropionic acid (DMPA) and Triethylamine (TEA) to carry out constant temperature 3h, cooling and discharging, and detecting that the NCO value of the obtained cross-linking agent product is 8.0 wt%, wherein the adding amount of PEG600 is 30 wt% of TMP, the adding amount of DMPA is 3.6 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10 mass percent, and can be dispersed into a white emulsion by manual stirring, and the NCO content of the emulsion has a stable period of about 5 hours.
Example 6
Preparing waterborne polyurethane cross-linking in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrerAnd (4) a coupling agent. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 45 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.1 wt%; and then heating to 72 ℃, dropwise adding polyethylene glycol 800(PEG800), dimethylolpropionic acid (DMPA) and Triethylamine (TEA), keeping the temperature constant for about 3 hours, cooling and discharging, and detecting that the NCO value of the obtained cross-linking agent product is 8.0 wt%, wherein the adding amount of PEG800 is 19 wt% of TMP, the adding amount of DMPA is 3.9 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10, and can be dispersed into bluish translucent emulsion by manual stirring, wherein the stable period of NCO content in the emulsion is about 6 hours.
Example 7
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 45 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.1 wt%; and then heating to 75 ℃, dropwise adding polyethylene glycol 800(PEG800), dimethylolpropionic acid (DMPA) and Triethylamine (TEA) to perform constant temperature 3h, cooling and discharging, and detecting that the NCO value of the obtained cross-linking agent product is 8.0 wt%, wherein the addition of the PEG800 is 25 wt% of TMP, the addition of the DMPA is 3.9 wt% of TMP, and the molar ratio of the TEA to the DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10, and can be dispersed into bluish translucent emulsion by manual stirring, wherein the stable period of NCO content in the emulsion is about 6 hours.
Example 8
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 45 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.1 wt%;and then heating to 72 ℃, dropwise adding polyethylene glycol 1000(PEG1000), dimethylolpropionic acid (DMPA) and Triethylamine (TEA), keeping the temperature for about 3 hours, cooling and discharging, and detecting that the NCO value of the obtained cross-linking agent product is 7.9 wt%, wherein the addition of the PEG1000 is 19 wt% of TMP, the addition of the DMPA is 4.0 wt% of TMP, and the molar ratio of the TEA to the DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10, and can be dispersed into bluish translucent emulsion by manual stirring, wherein the stable period of NCO content in the emulsion is about 6 hours.
Example 9
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 45 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.1 wt%; then heating to 75 ℃, dropwise adding polyethylene glycol 600(PEG600), dimethylolpropionic acid (DMPA), Tetramethylguanidine (TMG) and Triethylamine (TEA) to perform constant-temperature reaction, cooling and discharging, and controlling the NCO value of the obtained cross-linking agent product to be 8.0 wt%, wherein the adding amount of PEG600 is 19 wt% of TMP, the adding amount of DMPA is 3.5 wt% of TMP, the content of TMG is 0.5 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10, and the emulsion can be dispersed into slightly bluish translucent emulsion by manual stirring, and the stable period of NCO content in the emulsion is about 8 hours.
Example 10
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 42 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 19.5 wt%; then heating to 70 ℃, dropwise adding polyethylene glycol 600(PEG600), dimethylolpropionic acid (DMPA), Tetramethylguanidine (TMG) and Triethylamine (TEA), keeping the temperature for 3 hours, cooling and discharging, and detecting the NCO value of the obtained cross-linking agent product to be 8.0 wt%Wherein the addition amount of PEG600 is 25 wt% of TMP, the addition amount of DMPA is 3.6 wt% of TMP, the content of TMG is 1.3 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10 mass percent was added to deionized water and the emulsion was dispersed by hand stirring to a light blue clear emulsion having an NCO content stabilization period of about 8 hours.
Comparative example 1
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 45 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.1 wt%; then heating to 75 ℃, dropwise adding polyethylene glycol 400(PEG400), dimethylolpropionic acid (DMPA) and Triethylamine (TEA) to perform constant temperature reaction, cooling and discharging, wherein the NCO value of the obtained cross-linking agent product is 8.0 wt%, the adding amount of PEG400 is 19 wt% of TMP, the adding amount of DMPA is 3.5 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10 mass ratio to deionized water, stirring to obtain milky white dispersion liquid with more precipitate at the bottom.
Comparative example 2
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 45 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.1 wt%; then heating to 75 ℃, dropwise adding polyethylene glycol 2000(PEG2000), dimethylolpropionic acid (DMPA) and Triethylamine (TEA) to perform constant temperature reaction, cooling and discharging, wherein the NCO value of the obtained cross-linking agent product is 8.0 wt%, the adding amount of PEG2000 is 19 wt% of TMP, the adding amount of DMPA is 3.5 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10, stirring to obtain milky white dispersion, and standing for 2 hours to form lumps.
Comparative example 3
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 40 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP (TMP) to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.3 wt%; then heating to 80 ℃, dropwise adding polyethylene glycol 600(PEG600), dimethylolpropionic acid (DMPA) and Triethylamine (TEA) to perform constant temperature reaction, cooling and discharging, wherein the NCO value of the cross-linking agent product is controlled to be 8.6 wt%, the adding amount of PEG600 is 10 wt% of TMP, the adding amount of DMPA is 3.2 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10, the emulsion can be dispersed into white emulsion by manual stirring, but oil drops are adsorbed on the cup wall, so that stable emulsion is difficult to form.
Comparative example 4
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 42 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 19.5 wt%; then heating to 70 ℃, dropwise adding polyethylene glycol 600(PEG600), dimethylolpropionic acid (DMPA) and Triethylamine (TEA) to perform constant temperature reaction, cooling and discharging, and controlling the NCO value of the obtained cross-linking agent product to be 8.0 wt%, wherein the addition amount of PEG600 is 32 wt% of TMP, the addition amount of DMPA is 3.6 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10, it is difficult to disperse into a stable emulsion due to the high viscosity of the product.
Comparative example 5
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 45 ℃, and adding N2Adding HDI and TMP in a molar ratio of 3 under the protection conditionAdding Trimethylolpropane (TMP) to react to obtain HDI tripolymer, wherein the NCO value of the HDI tripolymer is 20.1 wt%; then heating to 75 ℃, dropwise adding polyethylene glycol monomethyl ether 800(MPEG800), dimethylolpropionic acid (DMPA) and Triethylamine (TEA) to perform constant temperature reaction, cooling and discharging, wherein the NCO value of the obtained cross-linking agent product is 8.0 wt%, the addition of the MPEG800 is 19 wt% of TMP, the addition of the DMPA is 3.5 wt% of TMP, and the molar ratio of the TEA to the DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10, and stirring the mixture into lumps in the emulsion, so that the mixture is difficult to disperse.
Comparative example 6
The waterborne polyurethane crosslinking agent is prepared in a four-mouth bottle provided with a thermometer, a reflux condenser tube and a stirrer. Adding Hexamethylene Diisocyanate (HDI) and acetone into a four-mouth bottle, heating to 45 ℃, and adding N2Under the protection condition, Trimethylolpropane (TMP) is added according to the molar ratio of HDI to TMP being 3 to react to obtain HDI tripolymer, and the NCO value of the HDI tripolymer is 20.1 wt%; then heating to 75 ℃, dropwise adding polyethylene glycol 600(PEG600), dimethylolpropionic acid (DMPA), caprolactam and Triethylamine (TEA) to perform constant-temperature reaction, cooling and discharging, wherein the NCO value of the obtained cross-linking agent product is controlled to be 8.0 wt%, the adding amount of PEG600 is 19 wt% of TMP, the adding amount of DMPA is 3.5 wt% of TMP, the content of caprolactam is 0.5 wt% of TMP, and the molar ratio of TEA to DMPA is 1: 1. the resulting crosslinker product was prepared according to 1: 10, and can be dispersed into slightly bluish translucent emulsion by manual stirring, wherein the stable period of NCO content in the emulsion is about 6 hours.
The waterborne polyurethane crosslinking agent obtained by the invention is a clear and transparent liquid in appearance, the solid content is 50 +/-2%, the pH value is 6-7, and the viscosity is 300-800 mPa.S. The aqueous polyurethane crosslinking agent aqueous dispersion (aqueous dispersion formed by dispersing the crosslinking agent and deionized water) prepared by the embodiment of the invention is added into the anionic aqueous polyurethane emulsion to form a film, so that the solvent resistance, impact strength, hardness and peel strength of the aqueous polyurethane coating can be obviously improved, and the gloss (60 ℃) is more than 90. Taking a certain aqueous polyurethane emulsion (the raw materials comprise 2072 parts by weight of polyester glycol, 7.8 parts by weight of dibutyltin dilaurate, 702 parts by weight of TDI, 152.7 parts by weight of diethylene glycol, 146.5 parts by weight of tartaric acid, 101.5 parts by weight of triethylamine, and a proper amount of acetone and water, dehydrating the polyester glycol, adding dibutyltin dilaurate and TDI for reaction at 60 ℃ to prepare a polyurethane prepolymer, then adding diethylene glycol, continuing to react at 80 ℃ for 3h, cooling to 50 ℃, adding tartaric acid and an acetone solution for reaction for 1h, diluting with acetone, finally adding triethylamine, stirring uniformly, slowly adding deionized water, distilling under reduced pressure to remove the acetone to form an aqueous polyurethane emulsion), uniformly coating the aqueous polyurethane emulsion on a basement membrane, and measuring the peel strength of the CPP to be 5.7N/15mm, and when the aqueous polyurethane crosslinking agent aqueous dispersion of the embodiment of the invention is added, and when the content of the aqueous polyurethane crosslinking agent accounts for more than 4.0 wt% of the aqueous polyurethane emulsion, the peel strength can be improved to 12.1N/15 mm. In addition, the impact strength, hardness and the like of the coating film are remarkably improved. The above is only an exemplary application description, and the effect of improving the solvent resistance, impact strength, hardness and peel strength of the aqueous polyurethane coating film can be achieved by applying the aqueous polyurethane crosslinking agent of the present invention to the common aqueous polyurethane; in particular, the stripping resistance can be improved by times, so that the waterborne polyurethane crosslinking agent is mainly used as a crosslinking agent of a two-component waterborne adhesive.
It is obvious to those skilled in the art that the present invention is not limited to the above embodiments, and it is within the scope of the present invention to adopt various insubstantial modifications of the method concept and technical scheme of the present invention, or to directly apply the concept and technical scheme of the present invention to other occasions without modification.
Claims (3)
1. A preparation method of aqueous polyurethane cross-linking agent dispersion liquid is characterized by comprising the following steps: the dispersion liquid is obtained by stirring and dispersing a waterborne polyurethane crosslinking agent and deionized water, and the weight ratio of the waterborne polyurethane crosslinking agent to the deionized water is 1: 10, the waterborne polyurethane crosslinking agent is obtained by reacting HDI tripolymer, polyethylene glycol, dimethylolpropionic acid, tetramethylguanidine and triethylamine at 75 ℃, and the NCO value of the crosslinking agent obtained by the reaction is 8.0 wt%;
the HDI trimer is prepared by reacting hexamethylene diisocyanate with trimethylolpropane under the protection of inactive gas at 45 ℃, the NCO value of the obtained trimer is 20.1 wt%, and the molar ratio of the hexamethylene diisocyanate to the trimethylolpropane is 3: 1; the molecular weight of the polyethylene glycol is 600, the addition amount of the polyethylene glycol is 19 wt% of trimethylolpropane, the content of tetramethylguanidine is 0.5 wt% of trimethylolpropane, the addition amount of dimethylolpropionic acid is 3.5 wt% of trimethylolpropane, and the molar ratio of triethylamine to dimethylolpropionic acid is 1: 1.
2. a preparation method of aqueous polyurethane cross-linking agent dispersion liquid is characterized by comprising the following steps: the dispersion liquid is obtained by stirring and dispersing a waterborne polyurethane crosslinking agent and deionized water, and the weight ratio of the waterborne polyurethane crosslinking agent to the deionized water is 1: 10, the waterborne polyurethane crosslinking agent is obtained by reacting HDI tripolymer, polyethylene glycol, dimethylolpropionic acid, tetramethylguanidine and triethylamine at 70 ℃, and the NCO value of the crosslinking agent obtained by the reaction is 8.0 wt%;
the HDI trimer is prepared by reacting hexamethylene diisocyanate with trimethylolpropane at 42 ℃ under the protection of inactive gas, the NCO value of the obtained trimer is 19.5 wt%, and the molar ratio of the hexamethylene diisocyanate to the trimethylolpropane is 3: 1; the molecular weight of the polyethylene glycol is 600, the addition amount of the polyethylene glycol is 25 wt% of trimethylolpropane, the addition amount of the dimethylolpropionic acid is 3.6 wt% of the trimethylolpropane, the addition amount of the tetramethylguanidine is 1.3 wt% of the trimethylolpropane, and the molar ratio of triethylamine to dimethylolpropionic acid is 1: 1.
3. a waterborne polyurethane cross-linking agent dispersion liquid is characterized in that: prepared by the preparation method of claim 1 or 2.
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| CN112250819B (en) * | 2020-10-21 | 2022-05-06 | 江苏海洋大学 | Polyurethane-based multifunctional interpenetrating network polymer and preparation method thereof |
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