CN111303348A - Photocuring waterborne polyurethane emulsion and preparation method and application thereof - Google Patents

Abstract

The invention provides a photocurable water-based polyurethane emulsion, which is prepared from raw materials including the following components: 25-35 parts by weight of isophorone diisocyanate; 40-60 parts by weight of polytetrahydrofuran diol; dibutyltin dilaurate 0.05-0.15 parts by weight; 4-6 parts by weight of dimethylolpropionic acid; 3-5 parts by weight of triethylamine; 0.5-2 parts by weight of anhydrous ethylenediamine; 0.5-10 parts by weight of photocurable monomers; self-healing 3 to 8 parts by weight of monomer; 0.001 to 0.01 part by weight of p-hydroxyanisole; water, the amount of water used is the amount when the solid content of the emulsion is 25wt.% to 35wt.%; the self-healing monomer is 2-amino-4-hydroxy-6-methylpyrimidine. Compared with the prior art, the light-cured water-based polyurethane emulsion provided by the present invention adopts a specific content of components, polymerizes according to the molecular structure design, and realizes good interaction, so that the cured film obtained from the light-cured water-based polyurethane emulsion has excellent performance. Its mechanical properties and excellent self-healing properties have broad application prospects in the field of flexible sensors.

Description

A kind of photocurable water-based polyurethane emulsion and its preparation method and application

technical field

The invention relates to the technical field of water-based polyurethane, and more particularly, to a light-cured water-based polyurethane emulsion and a preparation method and application thereof.

Background technique

In daily life and industrial applications, prolonging the service life of products is one of the main points of concern. However, with the increase of use time, the polymer is damaged and destroyed due to the influence of external conditions such as chemical, heat, and external force during use, which will lead to serious consequences in subsequent use, and even endanger the safety of users. Intrinsic self-healing materials do not require external embedding of repair agents, and can achieve self-healing of materials spontaneously or under certain external stimuli by utilizing reversible dynamic chemical interactions or supramolecular interactions in molecular networks. Among them, hydrogen bonding is a kind of supramolecular chemical force that has been extensively studied, and it is ubiquitous in natural biomolecules. Structure-specific physiological or biochemical functions such as DNA replication, protein folding, and molecular recognition are all related to reversible hydrogen bonding. . The original purpose of studying hydrogen-bonded polymers was to improve the mechanical properties of materials, but due to the advantages of directionality, reversibility, and sensitivity of hydrogen bonds, people have gradually used them in the research of self-healing materials. There are potential applications in many different fields.

As a kind of polymer material with good comprehensive properties and green environmental protection, light-curable waterborne polyurethane can flexibly adjust its molecular structure according to its physical and chemical properties, so it has become a focus of attention in the development of green and environmentally friendly resins. Among them, UV-curing technology was first proposed in the early 20th century, and its "5E" characteristics (Economy, Enabling, Efficiency, Environmental friendly and Energy saving) have attracted widespread attention from academia and industry in recent years. Generally speaking, there are two ways of crosslinking for photocurable waterborne polyurethane, namely irreversible covalent chemical crosslinking and reversible non-covalent physical crosslinking (hydrogen bond crosslinking). Chemically cross-linked waterborne polyurethanes are mainly thermosetting polymers with good mechanical properties such as excellent elasticity, high strength, excellent chemical resistance, etc. The limitation is mainly manifested in that after being damaged by the outside world, its mechanical strength and other properties are basically difficult to restore to the original state, thus causing difficulties for subsequent repeated applications. Because of this, the reversible physical crosslinking modification of photocurable water-based polyurethane by reversible non-covalent bonds has become a research hotspot of researchers in this field, and more importantly, it can impart self-healing properties to photocurable water-based polyurethane.

At present, most of the self-healing polyurethanes are oil-based resins (solvent-based polyurethanes), and the preparation process requires the use of a large amount of organic solvents, which is harmful to the human environment. Hydrogen-bonded self-healing waterborne polyurethane with excellent mechanical properties and repairing properties. This is because although there are a large number of hydrogen bonds in the light-cured water-based polyurethane itself, its hydrogen bonds are basically single hydrogen bonds, and the force is weak. In addition, the chemical cross-linking structure after light curing makes its self-healing performance very good. Difference. Therefore, how to introduce more hydrogen bonds and multiple hydrogen bonds into the photocurable waterborne polyurethane, so that the environment-friendly photocurable waterborne polyurethane has both excellent mechanical properties and excellent self-healing properties has become a technical problem to be solved urgently by those skilled in the art .

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a photocurable waterborne polyurethane emulsion and a preparation method and application thereof. The cured film obtained from the photocurable waterborne polyurethane emulsion provided by the present invention has both excellent mechanical properties and excellent self-healing properties.

The invention provides a light-cured water-based polyurethane emulsion, which is prepared from raw materials comprising the following components:

25-35 parts by weight of isophorone diisocyanate;

40-60 parts by weight of polytetrahydrofuran diol;

0.05-0.15 parts by weight of dibutyltin dilaurate;

4 to 6 parts by weight of dimethylolpropionic acid;

3 to 5 parts by weight of triethylamine;

0.5-2 parts by weight of anhydrous ethylenediamine;

0.5-10 parts by weight of photocurable monomer;

3 to 8 parts by weight of self-healing monomer;

0.001-0.01 parts by weight of p-hydroxyanisole;

water, the amount of water used is the amount when the solid content of the emulsion is 25wt.% to 35wt.%;

The self-healing monomer is 2-amino-4-hydroxy-6-methylpyrimidine.

Preferably, the photocurable monomer is hydroxyethyl methacrylate.

The present invention also provides a preparation method of the photocurable water-based polyurethane emulsion described in the above technical solution, comprising the following steps:

a) after isophorone diisocyanate and dibutyltin dilaurate are mixed, polytetrahydrofuran diol is added dropwise, and then the first reaction is carried out to obtain a reaction mixture;

b) adding dimethylolpropionic acid to the reaction mixture obtained in step a) to carry out the second reaction, then adding triethylamine to form salt, adding anhydrous ethylenediamine to carry out chain extension, adding self-repairing monohydrate body, photocurable monomer and p-hydroxyanisole, carry out the third reaction, and finally add water for emulsification to obtain photocurable waterborne polyurethane emulsion;

The self-healing monomer is 2-amino-4-hydroxy-6-methylpyrimidine.

Preferably, the temperature of the dropwise addition in step a) is 65°C to 85°C, and the time is 10 min to 25 min.

Preferably, the temperature of the first reaction in step a) is 75°C to 90°C, and the time is 1.5h to 3.5h.

Preferably, the temperature of the second reaction in step b) is 65°C to 85°C, and the time is 1.5h to 3.5h.

Preferably, the temperature of the salt formation in step b) is 40°C～55°C, and the time is 25min～65min;

The chain extension time is 10min-35min.

Preferably, the temperature of the third reaction in step b) is 55°C to 75°C, and the time is 2.5h to 4.5h.

Preferably, described step b) also comprises:

In the third reaction process, acetone was added to adjust the viscosity of the reaction system; and after the emulsification process, the acetone was distilled off under reduced pressure.

The present invention also provides a cured film, which is prepared by photocuring the photocurable water-based polyurethane emulsion described in the above technical solution.

The invention provides a photocurable water-based polyurethane emulsion, which is prepared from raw materials including the following components: 25-35 parts by weight of isophorone diisocyanate; 40-60 parts by weight of polytetrahydrofuran diol; dibutyltin dilaurate 0.05-0.15 parts by weight; 4-6 parts by weight of dimethylolpropionic acid; 3-5 parts by weight of triethylamine; 0.5-2 parts by weight of anhydrous ethylenediamine; 0.5-10 parts by weight of photocurable monomers; self-healing 3 to 8 parts by weight of monomer; 0.001 to 0.01 part by weight of p-hydroxyanisole; water, the amount of water used is the amount when the solid content of the emulsion is 25wt.% to 35wt.%; the self-healing monomer is 2-Amino-4-hydroxy-6-methylpyrimidine. Compared with the prior art, the light-cured water-based polyurethane emulsion provided by the present invention adopts a specific content of components, polymerizes according to the molecular structure design, and realizes good interaction, so that the cured film obtained from the light-cured water-based polyurethane emulsion has excellent performance. Its mechanical properties (flexibility and mechanical toughness) and excellent self-healing properties have broad application prospects in the field of flexible sensors.

In addition, the preparation method provided by the present invention has simple process and mild conditions, and can realize cost optimization by adjusting the specific dosage of the formula, and has huge application potential.

Description of drawings

Fig. 1 is the FT-IR spectrum before and after curing of the light-cured water-based polyurethane emulsion provided in Example 2 of the present invention;

Fig. 2 is the self-healing effect of the cured film scratch prepared by the light-cured water-based polyurethane emulsion provided in Examples 1-4 of the present invention;

Fig. 3 is the change curve of the tensile strength and elongation at break repair efficiency of the cured films prepared by the photocurable waterborne polyurethane emulsion provided in Examples 1-4 of the present invention under different repair conditions.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The invention provides a light-cured water-based polyurethane emulsion, which is prepared from raw materials comprising the following components:

25-35 parts by weight of isophorone diisocyanate;

40-60 parts by weight of polytetrahydrofuran diol;

0.05-0.15 parts by weight of dibutyltin dilaurate;

4 to 6 parts by weight of dimethylolpropionic acid;

3 to 5 parts by weight of triethylamine;

0.5-2 parts by weight of anhydrous ethylenediamine;

0.5-10 parts by weight of photocurable monomer;

3 to 8 parts by weight of self-healing monomer;

0.001-0.01 parts by weight of p-hydroxyanisole;

water, the amount of water used is the amount when the solid content of the emulsion is 25wt.% to 35wt.%;

The self-healing monomer is 2-amino-4-hydroxy-6-methylpyrimidine.

The present invention is suitable for the isophorone diisocyanate (IPDI), polytetrahydrofuran diol (PTMG-1000), dibutyltin dilaurate (DBDTL), dimethylolpropionic acid (DMPA), triethylamine (TEA) The sources of ethylenediamine anhydrous (EDA) and p-hydroxyanisole (MEHQ) are not particularly limited, and commercially available products well known to those skilled in the art can be used.

In the present invention, the photocurable water-based polyurethane emulsion includes 25-35 parts by weight of isophorone diisocyanate, preferably 30 parts by weight; the photo-curable water-based polyurethane emulsion includes 40-60 parts by weight of polytetrahydrofuran diol , preferably 45 parts by weight; the light-curable water-based polyurethane emulsion comprises 0.05-0.15 parts by weight of dibutyltin dilaurate, preferably 0.08 parts by weight; the light-curing water-based polyurethane emulsion comprises 4-6 parts by weight of dimethylol base propionic acid, preferably 5.5 parts by weight; the photocurable water-based polyurethane emulsion includes 3-5 parts by weight of triethylamine, preferably 4.15 parts by weight; the photo-curable water-based polyurethane emulsion includes 0.5-2 parts by weight anhydrous Ethylenediamine is preferably 0.78 parts by weight; the photocurable waterborne polyurethane emulsion includes 0.001-0.01 parts by weight of p-hydroxyanisole, preferably 0.001-0.004 parts by weight, more preferably 0.003 parts by weight.

In the present invention, the photocurable monomer is preferably hydroxyethyl methacrylate (HEMA); its structural formula is:

The source of the photocurable monomer is not particularly limited in the present invention, and the commercially available products of the above-mentioned hydroxyethyl methacrylate well known to those skilled in the art can be used. In the present invention, the photocurable aqueous polyurethane emulsion includes 0.5-10 parts by weight of a photo-curable monomer, preferably 0.65-2.6 parts by weight.

In the present invention, the self-healing monomer is 2-amino-4-hydroxy-6-methylpyrimidine (UPy); its structural formula is:

The source of the self-healing monomer is not particularly limited in the present invention, and the commercial product of the above-mentioned multiple hydrogen bond monomer 2-amino-4-hydroxy-6-methylpyrimidine well known to those skilled in the art can be used.

The present invention adopts the above-mentioned ureidopyrimidinone (2-amino-4-hydroxy-6-methylpyrimidine), which is a monomer that can self-assemble to form a stable dimer through quadruple hydrogen bonding. When the heavy hydrogen bond cross-linking works, it can produce greater binding energy and stability, and can be reversibly broken and bonded under the stimulation of external factors such as temperature, pH value, pressure, etc.; the present invention uses 2-amino-4 -Reversible quadruple hydrogen bonding and high dimer constant of hydroxy-6-methylpyrimidine to prepare self-healing waterborne photocurable polyurethane with high strength and high toughness.

In the present invention, the photocurable aqueous polyurethane emulsion includes 3-8 parts by weight of self-healing monomer, preferably 3.75-5.63 parts by weight.

In the present invention, the water can be deionized water well known to those skilled in the art; the dosage of the water is the amount when the solid content of the emulsion is 25wt.% to 35wt.%, preferably the solid content of the emulsion is The dosage at 30wt.%.

Generally, materials with excellent self-healing properties often have poor mechanical properties. Therefore, it is a major challenge to develop self-healing polyurethanes with both repairing and mechanical properties. The light-cured water-based polyurethane emulsion provided by the present invention adopts specific content of components, is polymerized according to the molecular structure design, and realizes good interaction, so that the cured film obtained from the light-cured water-based polyurethane emulsion has both excellent mechanical properties (flexibility and Mechanical toughness) and excellent self-healing performance, it has broad application prospects in the field of flexible sensors. Compared with oily polyurethane, the present invention is inspired by traditional emulsion polymerization, and the nanometer waterborne polyurethane emulsion obtained by emulsification shows a wide range of applications due to its nanometer size. In principle, nanometer latex particles with controllable size can be prepared by emulsification; these Supramolecular polymer-based nanomaterials, as the coupling of covalent and non-covalent bonds, can exhibit various unique properties, such as well-defined composition, high stability, and easy degradation; they may have great potential in many fields. potential for applications such as controlled release, nanoreactors, sensing and imaging.

In the present invention, the interaction of quadruple hydrogen bonds is selected as the main driving force of self-repairing photocurable water-based polyurethane, dimethylolpropionic acid (DMPA) is used as hydrophilic monomer, 2-amino-4-hydroxy-6-methyl Pyrimidine (UPy) is used as a quadruple hydrogen bond monomer, and hydroxyethyl methacrylate (HEMA) is used as a photocurable monomer. The UV curing technology is combined with the self-healing concept to develop a self-healing, photocurable and Aqueous polyurethane emulsion of components without additional surfactants. The search results show that self-healing photocurable waterborne polyurethanes with polyurethane as the main chain and modified UPy units and photocurable units at the ends have not been reported yet; The simple hydrogen bonds formed by the urethane, urea groups and other units of TiO also increase the hydrogen bond density in the system; the hydrogen bonds of the multi-level structure are more conducive to the formation of self-healing polyurethane under the mutual cooperation. In addition, in a preferred embodiment of the present invention, the low HEMA content endows the system with a relatively loose chemically cross-linked network structure, which can provide a large elastic frame, maintain the elasticity of the cured film, and enable the cured film to quickly return to its original state after being stretched. , which helps to promote the effective and rapid rearrangement of hydrogen bonds after breaking, which enhances the recovery ability of the material; at the same time, UPy monomer and polar groups such as urethane groups and urea groups in polyurethane can form hydrogen bonds to construct The physical cross-linking network, through the synergy between the chemical cross-linking network formed by double bond curing and the physical cross-linking network formed by hydrogen bonding, constructs a high-strength, high-toughness self-healing light-curing waterborne polyurethane.

The present invention also provides a preparation method of the photocurable water-based polyurethane emulsion described in the above technical solution, comprising the following steps:

a) after isophorone diisocyanate and dibutyltin dilaurate are mixed, polytetrahydrofuran diol is added dropwise, and then the first reaction is carried out to obtain a reaction mixture;

b) adding dimethylolpropionic acid to the reaction mixture obtained in step a) to carry out the second reaction, then adding triethylamine to form salt, adding anhydrous ethylenediamine to carry out chain extension, adding self-repairing monohydrate body, photocurable monomer and p-hydroxyanisole, carry out the third reaction, and finally add water for emulsification to obtain photocurable waterborne polyurethane emulsion;

The self-healing monomer is 2-amino-4-hydroxy-6-methylpyrimidine.

In the present invention, the preparation method is preferably carried out under nitrogen protection; a four-necked flask equipped with a stirring paddle, a thermometer and a condenser well known to those skilled in the art is used as the device of the preparation method, and the present invention has no special restrictions on this. .

In the present invention, after mixing isophorone diisocyanate and dibutyltin dilaurate, polytetrahydrofuran diol is added dropwise, and then the first reaction is performed to obtain a reaction mixture. In the present invention, the isophorone diisocyanate, dibutyltin dilaurate and polytetrahydrofurandiol are the same as those in the above technical solutions, and will not be repeated here.

In the present invention, the temperature of the dropwise addition is preferably 65°C to 85°C, more preferably 70°C to 80°C; the time of the dropwise addition is preferably 10min to 25min, more preferably 15min to 20min.

In the present invention, the temperature of the first reaction is continued after the dropwise addition is completed; the temperature of the first reaction is preferably 75°C to 90°C, more preferably 80°C to 85°C; the time of the first reaction is preferably 1.5h～3.5h, more preferably 2h～3h.

After obtaining the reaction mixture, the present invention adds dimethylolpropionic acid to the obtained reaction mixture to carry out the second reaction, and then sequentially adds triethylamine to form a salt, and adds anhydrous ethylenediamine to carry out chain extension, A self-healing monomer, a light-curing monomer and p-hydroxyanisole are added to carry out the third reaction, and finally water is added to emulsify to obtain a light-curing waterborne polyurethane emulsion. In the present invention, the dimethylolpropionic acid, triethylamine, anhydrous ethylenediamine, self-repairing monomer, light-curing monomer and p-hydroxyanisole are the same as those in the above technical solutions, and will not be repeated here. .

The present invention preferably also includes:

The resulting reaction mixture was cooled to below 55°C, and then dimethylolpropionic acid was added.

In the present invention, the temperature of the second reaction is preferably 65°C to 85°C, more preferably 70°C to 80°C; the time of the second reaction is preferably 1.5h to 3.5h, more preferably 2h ~3h.

In the present invention, the temperature of the salt formation is preferably 40°C to 55°C, more preferably 45°C to 50°C; the salt formation time is preferably 25min to 65min, more preferably 30min to 60min. In the present invention, the chain extension time is preferably 10 min to 35 min, more preferably 15 min to 30 min; the chain extension process continues the temperature of the previous salt formation.

In the present invention, the temperature of the third reaction is preferably 55°C to 75°C, more preferably 60°C to 70°C; the time of the third reaction is preferably 2.5h to 4.5h, more preferably 3h ~4h. In the present invention, the process of the third reaction is preferably followed by a toluene-di-n-butylamine titration method.

In the present invention, described step b) preferably also comprises:

In the third reaction process, acetone was added to adjust the viscosity of the reaction system; and after the emulsification process, the acetone was distilled off under reduced pressure.

In the present invention, the amount of the added water is the amount when the solid content of the emulsion is 25wt.% to 35wt.%, preferably the amount when the solid content of the emulsion is 30wt.%.

In the present invention, the emulsification method is preferably high-speed stirring, in order to disperse the emulsion uniformly; the emulsification time is preferably 0.5h-2.5h, more preferably 1h-2h.

The preparation method provided by the invention has simple process, mild conditions, and can realize cost optimization by adjusting the specific dosage of the formula, and has huge application potential.

The present invention also provides a cured film, which is prepared by photocuring the photocurable water-based polyurethane emulsion described in the above technical solution. In the present invention, the preparation process of the cured film is specifically:

A photoinitiator is added to the photocurable water-based polyurethane emulsion described in the above technical solution, and ultrasonically oscillated for 25 to 35 minutes to make it evenly dissolved in the emulsion, and then the emulsion containing the photoinitiator is poured into a polytetrafluoroethylene mold and placed in Dry in a blast drying oven at 75℃～85℃ for 22h～26h, and after the moisture in the coating film evaporates slowly, perform light curing for 4min～6min in a UV curing machine to obtain a cured film;

More preferably:

Add a photoinitiator to the photocurable waterborne polyurethane emulsion described in the above technical solution, ultrasonically vibrate for 30 minutes to make it evenly dissolved in the emulsion, then pour the emulsion containing the photoinitiator into a polytetrafluoroethylene mold, and place it at 80 ° C Dry in a blast drying oven for 24 hours, and after the moisture in the coating film evaporates slowly, perform photo-curing for 5 minutes in a UV curing machine to obtain a cured film.

The present invention does not specifically limit the specific type and source of the photoinitiator, and a commercially available photoinitiator known to those skilled in the art for UV curing can be used.

In the present invention, the photo-curing process preferably adopts UV curing. Compared with the traditional thermal curing that needs to be carried out at high temperature (>120°C), UV curing is an environmentally friendly, energy-saving and efficient green solution. The curing technology avoids the defect that some heat-sensitive substrates are easily damaged under high temperature heat curing, which is conducive to the curing and molding of the resin under mild conditions; and the relatively loose chemical cross-linked network structure formed by UV curing can provide a The large elastic frame maintains the elasticity of the cured film, so that the cured film can quickly return to its original state after being stretched, which helps to promote the effective and rapid rearrangement of hydrogen bonds after breaking, and enhances the recovery ability of the material.

The invention prepares a self-repairable light-curable water-based polyurethane, and compared with solvent-based polyurethane, water replaces the organic solvent, is an environment-friendly resin, has better biocompatibility, and can be used for medical equipment or supplies. Surface finishing and human skin. At the same time, the nano-aqueous polyurethane emulsion obtained by emulsification shows a wide range of applications due to its nano-size; in principle, nano-latex particles with controllable size can be prepared by emulsification; these supramolecular polymer-based nanomaterials, as covalent bonds with The coupling of non-covalent bonds can show various unique properties, such as well-defined composition, high stability and easy degradation; they may have great application potential in many fields, such as controlled release, nanoreactors, transmission sense and imaging.

In addition, in a preferred embodiment of the present invention, the double bond-containing monomer hydroxyethyl methacrylate (HEMA) and the quadruple hydrogen bond monomer 2-amino-4-hydroxy-6-methylpyrimidine (UPy) are used , by adjusting the ratio of the two to maximize the synergistic effect of the two, a self-healing light-curable waterborne polyurethane is prepared; the relatively loose chemically cross-linked network structure formed by HEMA through UV curing can provide a large elastic framework to maintain It improves the elasticity of the cured film, so that the cured film can quickly return to its original state after being stretched, which helps to promote the effective and rapid rearrangement of hydrogen bonds after breaking, so that the self-healing ability of the material is enhanced; on the other hand, UPy monomer and polyurethane The polar groups such as carbamate groups and urea groups in the PU can form hydrogen bonds to build a physical cross-linked network. With the increase of UPy monomers, the density of hydrogen bonds in the system is increased, and the hydrogen bonds are more likely to be broken. -Rearrangement, which is beneficial to the self-healing behavior of the cured film when it is damaged by the outside world; therefore, the synergy between the chemical cross-linked network formed by double bond curing and the physical cross-linked network formed by hydrogen bonding, A high-strength, high-toughness self-healing light-curable waterborne polyurethane is constructed; taking into account its properties, the resin's good stretchability and flexibility make it potential for application in flexible sensors.

The invention provides a photocurable water-based polyurethane emulsion, which is prepared from raw materials including the following components: 25-35 parts by weight of isophorone diisocyanate; 40-60 parts by weight of polytetrahydrofuran diol; dibutyltin dilaurate 0.05-0.15 parts by weight; 4-6 parts by weight of dimethylolpropionic acid; 3-5 parts by weight of triethylamine; 0.5-2 parts by weight of anhydrous ethylenediamine; 0.5-10 parts by weight of photocurable monomers; self-healing 3 to 8 parts by weight of monomer; 0.001 to 0.01 part by weight of p-hydroxyanisole; water, the amount of water used is the amount when the solid content of the emulsion is 25wt.% to 35wt.%; the self-healing monomer is 2-Amino-4-hydroxy-6-methylpyrimidine. Compared with the prior art, the light-cured water-based polyurethane emulsion provided by the present invention adopts a specific content of components, polymerizes according to the molecular structure design, and realizes good interaction, so that the cured film obtained from the light-cured water-based polyurethane emulsion has excellent performance. Its mechanical properties (flexibility and mechanical toughness) and excellent self-healing properties have broad application prospects in the field of flexible sensors.

In addition, the preparation method provided by the present invention has simple process and mild conditions, and can realize cost optimization by adjusting the specific dosage of the formula, and has huge application potential.

In order to further illustrate the present invention, the following examples are used for detailed description. The raw materials used in the following examples of the present invention are all commercially available commodities.

Example 1

(1) Raw material ratio:

Isophorone diisocyanate (IPDI) 30g;

Polytetrahydrofurandiol (PTMG-1000) 45g;

Dibutyltin dilaurate (DBDTL) 0.08g;

Dimethylolpropionic acid (DMPA) 5.5g;

Triethylamine (TEA) 4.15g;

Anhydrous ethylenediamine (EDA) 0.78g;

Hydroxyethyl methacrylate (HEMA) 2.60g;

2-Amino-4-hydroxy-6-methylpyrimidine (UPy) 3.75g;

p-Hydroxyanisole (MEHQ, the amount added is 0.15wt.% of HEMA monomer) 0.004g;

appropriate amount of acetone;

Deionized water was metered into the emulsion at a solids content of 30%.

(2) Preparation method:

Under nitrogen protection, add 30g IPDI and 0.08g DBDTL to a four-necked flask equipped with a stirring paddle, a thermometer and a condenser, and add 45g PTMG-1000 dropwise when the temperature is raised to 70°C to 80°C for 15min to 20min. After the dropwise addition, continue to heat up to 80℃～85℃, and react for 2h～3h; then cool down to 40℃～50℃, add 5.5g DMPA, then heat up to 70℃～80℃ again, and react for 2h～3h; Cool to 45℃～50℃, add 4.15g TEA and react for 30min～60min to form a salt; then add 0.78g EDA for 15min～30min chain extension; after the chain extension is completed, add 3.75g UPy, 2.60g HEMA and 0.004g MEHQ, and heat up After reaching 60℃～70℃, react for 3h～4h. During the reaction process, an appropriate amount of acetone can be added to reduce the viscosity; the above process is followed by toluene-di-n-butylamine titration method, and finally quantitative deionized water is added to control the solid content of the system to 30% , and high-speed stirring for 1h to 2h to emulsify, the emulsion is dispersed evenly, and then acetone is evaporated under reduced pressure to obtain a light-cured water-based polyurethane emulsion.

Example 2

(1) Raw material ratio:

Isophorone diisocyanate (IPDI) 30g;

Polytetrahydrofurandiol (PTMG-1000) 45g;

Dibutyltin dilaurate (DBDTL) 0.08g;

Dimethylolpropionic acid (DMPA) 5.5g;

Triethylamine (TEA) 4.15g;

Anhydrous ethylenediamine (EDA) 0.78g;

Hydroxyethyl methacrylate (HEMA) 1.95g;

2-Amino-4-hydroxy-6-methylpyrimidine (UPy) 4.38g;

p-Hydroxyanisole (MEHQ, the amount added is 0.15wt.% of HEMA monomer) 0.003g;

appropriate amount of acetone;

Deionized water was metered into the emulsion at a solids content of 30%.

(2) Preparation method:

Under nitrogen protection, add 30g IPDI and 0.08g DBDTL to a four-necked flask equipped with a stirring paddle, a thermometer and a condenser, and add 45g PTMG-1000 dropwise when the temperature is raised to 70°C to 80°C for 15min to 20min. After the dropwise addition, continue to heat up to 80℃～85℃, and react for 2h～3h; then cool down to 40℃～50℃, add 5.5g DMPA, then heat up to 70℃～80℃ again, and react for 2h～3h; Cool to 45℃～50℃, add 4.15g TEA and react for 30min～60min to form a salt; then add 0.78g EDA for 15min～30min chain extension; after chain extension, add 4.38g UPy, 1.95g HEMA and 0.003g MEHQ, heat up After the reaction reaches 60℃～70℃ for 3h～4h, an appropriate amount of acetone can be added to adjust the viscosity of the reaction system; the above process is followed by toluene-di-n-butylamine titration method, and finally quantitative deionized water is added to control the solid content of the system to 30% , and high-speed stirring for 1h to 2h to emulsify, the emulsion is dispersed evenly, and then acetone is evaporated under reduced pressure to obtain a light-cured water-based polyurethane emulsion.

Example 3

(1) Raw material ratio:

Isophorone diisocyanate (IPDI) 30g;

Polytetrahydrofurandiol (PTMG-1000) 45g;

Dibutyltin dilaurate (DBDTL) 0.08g;

Dimethylolpropionic acid (DMPA) 5.5g;

Triethylamine (TEA) 4.15g;

Anhydrous ethylenediamine (EDA) 0.78g;

Hydroxyethyl methacrylate (HEMA) 1.30g;

2-Amino-4-hydroxy-6-methylpyrimidine (UPy) 5.01g;

p-Hydroxyanisole (MEHQ, the amount added is 0.15wt.% of HEMA monomer) 0.002g;

appropriate amount of acetone;

Deionized water was metered into the emulsion at a solids content of 30%.

(2) Preparation method:

Under nitrogen protection, add 30g IPDI and 0.08g DBDTL to a four-necked flask equipped with a stirring paddle, a thermometer and a condenser, and add 45g PTMG-1000 dropwise when the temperature is raised to 70°C to 80°C for 15min to 20min. After the dropwise addition, continue to heat up to 80℃～85℃, and react for 2h～3h; then cool down to 40℃～50℃, add 5.5g DMPA, then heat up to 70℃～80℃ again, and react for 2h～3h; Cool to 45℃～50℃, add 4.15g TEA and react for 30min～60min to form a salt; then add 0.78g EDA for 15min～30min chain extension; after chain extension, add 5.01g UPy, 1.30g HEMA and 0.002g MEHQ, heat up After the reaction reaches 60℃～70℃ for 3h～4h, an appropriate amount of acetone can be added to adjust the viscosity of the reaction system; the above process is followed by toluene-di-n-butylamine titration method, and finally quantitative deionized water is added to control the solid content of the system to 30% , and high-speed stirring for 1h to 2h to emulsify, the emulsion is dispersed evenly, and then acetone is evaporated under reduced pressure to obtain a light-cured water-based polyurethane emulsion.

Example 4

(1) Raw material ratio:

Isophorone diisocyanate (IPDI) 30g;

Polytetrahydrofurandiol (PTMG-1000) 45g;

Dibutyltin dilaurate (DBDTL) 0.08g;

Dimethylolpropionic acid (DMPA) 5.5g;

Triethylamine (TEA) 4.15g;

Anhydrous ethylenediamine (EDA) 0.78g;

Hydroxyethyl methacrylate (HEMA) 0.65g;

2-Amino-4-hydroxy-6-methylpyrimidine (UPy) 5.63g;

p-Hydroxyanisole (MEHQ, the amount added is 0.15wt.% of HEMA monomer) 0.001g;

appropriate amount of acetone;

Deionized water was metered into the emulsion at a solids content of 30%.

(2) Preparation method:

Under nitrogen protection, add 30g IPDI and 0.08g DBDTL to a four-necked flask equipped with a stirring paddle, a thermometer and a condenser, and add 45g PTMG-1000 dropwise when the temperature is raised to 70°C to 80°C for 15min to 20min. After the dropwise addition, continue to heat up to 80℃～85℃, and react for 2h～3h; then cool down to 40℃～50℃, add 5.5g DMPA, then heat up to 70℃～80℃ again, and react for 2h～3h; Cool to 45℃～50℃, add 4.15g TEA and react for 30min～60min to form a salt; then add 0.78g EDA for 15min～30min chain extension; after the chain extension is completed, add 5.63g UPy, 0.65g HEMA and 0.001g MEHQ, and heat up After the reaction reaches 60℃～70℃ for 3h～4h, an appropriate amount of acetone can be added to adjust the viscosity of the reaction system; the above process is followed by toluene-di-n-butylamine titration method, and finally quantitative deionized water is added to control the solid content of the system to 30% , and high-speed stirring for 1h to 2h to emulsify, the emulsion is dispersed evenly, and then acetone is evaporated under reduced pressure to obtain a light-cured water-based polyurethane emulsion.

Comparative Example 1

(1) Raw material ratio:

Isophorone diisocyanate (IPDI) 30g;

Polytetrahydrofurandiol (PTMG-1000) 45g;

Dibutyltin dilaurate (DBDTL) 0.08g;

Dimethylolpropionic acid (DMPA) 5.5g;

Triethylamine (TEA) 4.15g;

Anhydrous ethylenediamine (EDA) 0.78g;

Hydroxyethyl methacrylate (HEMA) 6.51g;

p-Hydroxyanisole (MEHQ, the amount added is 0.15wt.% of HEMA monomer) 0.01g;

appropriate amount of acetone;

Deionized water was metered into the emulsion at a solids content of 30%.

(2) Preparation method:

Under nitrogen protection, add 30g IPDI and 0.08g DBDTL to a four-necked flask equipped with a stirring paddle, a thermometer and a condenser, and add 45g PTMG-1000 dropwise when the temperature is raised to 70°C to 80°C for 15min to 20min. After the dropwise addition, continue to heat up to 80℃～85℃, and react for 2h～3h; then cool down to 40℃～50℃, add 5.5g DMPA, then heat up to 70℃～80℃ again, and react for 2h～3h; Cool to 45℃～50℃, add 4.15g TEA and react for 30min～60min to form a salt; then add 0.78g EDA for 15min～30min chain extension; after chain extension, add 6.51g HEMA and 0.01g MEHQ, and heat up to 60℃～ After the reaction at 70°C for 3h to 4h, an appropriate amount of acetone can be added to adjust the viscosity of the reaction system; the above process is followed by the toluene-di-n-butylamine titration method, and finally quantitative deionized water is added to control the solid content of the system to 30%, and high-speed stirring After 1 hour to 2 hours of emulsification, the emulsion is dispersed evenly, and then the acetone is evaporated under reduced pressure to obtain a light-curable water-based polyurethane emulsion.

Application example:

The photoinitiator Darocur1173, 3wt.% (based on the resin content) was added to the photocurable water-based polyurethane emulsions provided in Examples 1 to 4 and Comparative Example 1, respectively, and ultrasonically oscillated for 30 minutes to make it evenly dissolved in the emulsion. The emulsion of the photoinitiator was poured into a polytetrafluoroethylene mold, placed in a blast drying oven at 80 °C for 24 hours, and after the moisture in the coating film evaporated slowly, it was placed in a UV curing machine (RX300-1, Ergu, Dongguan City). Photoelectric Technology Co., Ltd.) for 5min photocuring to obtain the corresponding cured film.

Performance Testing:

(1) Particle size analysis: The emulsion was diluted to 1 vol.% with deionized water, and after ultrasonic oscillation, the particle size and its distribution were measured with a Zeta-type nanoparticle size analyzer from Beckman Coulter, USA, and the number of scans was 70 times.

(2) Mechanical stability of the emulsion: Take an appropriate amount of the emulsion in a centrifuge test tube, centrifuge it at 3000r/min for 30min using a centrifuge TG1650-WS from Shanghai Luxiangyi Company, take out the centrifuge tube and place it vertically for 48h at room temperature to observe the state of the emulsion.

(3) Infrared spectral analysis: The test uses the ^{Magna360 Fourier} transform infrared spectrometer manufactured by Nicolet Company in the United States, and the ATR method is used to characterize the cured film. The order is 32 and the wavenumber resolution is 4 cm ^-1 .

(4) Analysis of coating performance:

①The flexibility is tested according to the GB/T 1731-93 standard, and the flexibility of the cured film is characterized by the bending test. With steel rods of different diameters as the axis, the coating film covered on the tinplate is folded in half, and the coating film is not caused to cause paint. The diameter of the smallest mandrel of film failure indicates the film flexibility.

②Shore hardness According to GB/T6031-1998 standard, LX-A Shore hardness tester is used to test the hardness of the cured film, and the average value is taken after testing at three points.

③The gel ratio is tested according to ASTM D2765-84 standard. The cured film is placed in chloroform to soak for 24h at room temperature, and its weight loss ratio is calculated.

(5) Determination of self-healing performance: (1) After making a scratch about 0.2 mm deep on the cured film with a thickness of 0.5 mm by a blade, place the cured film with scratches in a blast at the test temperature Heating repair in a drying oven; observation of the degree of repair before and after scratches on the cured film by a polarizing microscope (BKPOL, Chongqing, China); (2) Repair analysis of the tensile properties of the cured film: The dumbbell-shaped cured film sample was cut with a blade The two fractured sections of the cured film are then placed in close contact with each other and placed at the test temperature (under a pressure of 0.2 MPa) for 24 hours of self-repair. 50mm/min, and the average value of the tensile properties of each sample is taken three times. Finally, calculate the Healing Efficiency (HE%) of the sample according to the formula (1-1);

where δ _repaired represents the tensile strength or elongation at break of the repaired sample, and δ _origin represents the tensile strength or elongation at break of the original sample.

Test Results:

(1) The result analysis of emulsion and latex film performance is shown in Table 1;

Table 1 Analysis of latex and latex film properties

It can be seen from Table 1 that the content of the quadruple hydrogen bond monomer UPy and the photocurable acrylate monomer HEMA has little effect on the properties of the emulsion, and the emulsions have good stability and small particle size; this shows that UPy and HEMA Polymers well.

When the content of HEMA gradually increased, the Shore hardness and gel fraction of the latex film gradually increased, and the flexibility remained basically unchanged. This is because the higher double bond content leads to a higher crosslinking density of the coating, which in turn has a key influence on the improvement of the hardness of the coating; at the same time, the gel fraction is also related to the crosslinking density, from Example 4 to implementation In Example 1, due to the increase of double bonds, the gel fraction increased from 16.30% to 70.81%; when the HEMA content was the highest (Comparative Example 1), the latex film gel fraction was 85.43%.

In addition, the flexibility of the coating characterizes the ability of the coating to adapt to the deformation movement of its carrier, sometimes referred to as "elasticity" or "ductility"; the flexibility of the coating is mainly determined by the flexibility of the resin, and when applied to all The coating is folded in half, and it can be found that the coating does not crack or break at the folded position, indicating that the coating has good flexibility; this is because the soft segment of the polyurethane is PTMG-1000 with ether bonds (C-O-C), Its molecular chain structure is regular and has excellent flexibility, which can significantly improve the flexibility of the resin.

(2) The infrared analysis of the cured film is shown in Figure 1; Figure 1 is the FT-IR spectrum before and after curing of the photocurable water-based polyurethane emulsion provided in Example 2 of the present invention, wherein (a) is before curing, (b) is After curing; before and after UV light curing, the infrared characteristic peak of carbamate (-NHCO) appeared at 3320cm ^-1 , and the infrared characteristic peak of -NCO did not appear at 2270cm ^-1 ; before UV light irradiation, The samples have absorption peaks at 1660cm ^-1 (C=C stretching vibration) and 810cm ^-1 (=CH out-of-plane bending vibration), indicating that HEMA was successfully polymerized onto the polyurethane structure; but after UV irradiation , the characteristic peaks of double bonds at 1660cm ^-1 and 810cm ^-1 disappeared, indicating that the sample was successfully cured by UV light, that is, the FT-IR spectrum can further illustrate the successful synthesis of self-healing photocurable waterborne polyurethane.

(3) Analysis of self-healing performance of cured film:

The self-healing performance of the cured film can be observed by optical microscope to the degree of repair of scratches, and the results are shown in Figure 2; Repair effect, wherein, (a) is Example 1, (b) is Example 2, (c) is Example 3, and (d) is Example 4. The observation results show that the change of the ratio of UPy and HEMA and the temperature have an important influence on the self-healing performance of the samples; when the temperature is 80 °C, the scratch depths of Examples 1 and 2 are slightly reduced after repairing for 24 hours, but they can still be repaired. Observe obvious defects, but the scratches of Example 3 are basically healed; the temperature is raised to 100 ° C, and after 90 minutes of repair, it can be seen that the scratches of Example 1 are slightly closed, and the depth of the scratches is reduced, but there are still obvious traces on the surface of the cured film , the scratches of Example 2 are basically closed, but there are still slight traces on the surface of the cured film, while Example 3 has been completely healed; continue to heat up to 120 ° C, after repairing for 15min, except for the sample of Example 1, it can still be observed obviously scratches, while almost no scratches were seen in the other three samples.

The above results show that the content of UPy is beneficial to improve the self-healing efficiency of the spline, while too much HEMA will make the material lose the repairing performance, and increasing the temperature can reduce the repairing time of the spline and help improve the self-repairing efficiency. This is because the cured film achieves self-healing through the mobility of polymer chains throughout the fractured surface and the destruction and reconstruction of multiple hydrogen bond networks; as the content of HEMA is relatively reduced, the chemical crosslinking density in the cured film decreases, Molecular chains are easier to move, and the relatively high concentration of UPy dimer increases the density of quadruple hydrogen bonds, giving the cured film better self-healing properties; it can be seen that the reversibility of hydrogen bonds is a self-healing photocurable water-based solution. The key to the entire self-healing process of the polyurethane cured film.

Fig. 3 is the change curve of the tensile strength and elongation at break repair efficiency of the cured films prepared by the photocurable water-based polyurethane emulsions provided in Examples 1 to 4 of the present invention under different repair conditions, wherein, Figs. (3a) and (3b) ) are the stress and strain repair efficiencies of the cured films at different temperatures (24h), respectively. The results show that with the increase of temperature, the tensile strength-elongation at break efficiency of the cured film is significantly improved, indicating that the mechanical tensile properties of the cured film are effectively recovered; this is because the increase of temperature does promote The hydrogen bond dissociates, the molecular segment has better mobility, and can move at the cross-section through molecular chain diffusion, and the dynamic hydrogen bond at the cross-section promotes the formation of a new physical cross-linked network through dissociation-rearrangement. Therefore, Greatly improves the tensile mechanical repair performance of splines.

Figures (3c) and (3d) show the tensile strength and elongation at break repair efficiency of the cured films at different repair times (100°C), respectively. The results show that with the increase of the repair time, the repair efficiency of the tensile mechanical properties of the specimens is significantly improved; this is because the increase of the repair time increases the effective contact time of the hydrogen bonds at the fracture surface, and the UPy II in the polymer network increases. Polymers and other hydrogen bonds can form multi-level reversible hydrogen bonds through hydrogen donor-acceptor interactions; with the extension of repair time, the hydrogen bond rearrangement is connected more tightly and firmly, and the hydrogen bond rearrangement forms dense physical The network has an important influence, which in turn improves the self-healing ability of the specimen. It is worth noting that after the repair time was increased to 36h, the tensile strength of the sample of Example 4 increased, and the repair efficiency of the tensile strength at 36h and 48h was 119.84% and 192.39%; In the case of low network density, long-term high temperature state can promote the re-exposing of the initiating radicals embedded in the molecular segments, and trigger the post-curing of the residual double bonds in the splines, resulting in a denser chemically cross-linked network, and then The tensile strength of the sample is improved.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A photocurable water-based polyurethane emulsion prepared from the raw materials comprising the following components: 25-35 parts by weight of isophorone diisocyanate; 40-60 parts by weight of polytetrahydrofuran diol; 0.05-0.15 parts by weight of dibutyltin dilaurate; 4 to 6 parts by weight of dimethylolpropionic acid; 3 to 5 parts by weight of triethylamine; 0.5-2 parts by weight of anhydrous ethylenediamine; 0.5-10 parts by weight of photocurable monomer; 3 to 8 parts by weight of self-healing monomer; 0.001-0.01 parts by weight of p-hydroxyanisole; water, the amount of water used is the amount when the solid content of the emulsion is 25wt.% to 35wt.%; The self-healing monomer is 2-amino-4-hydroxy-6-methylpyrimidine. 2 . The photocurable waterborne polyurethane emulsion according to claim 1 , wherein the photocurable monomer is hydroxyethyl methacrylate. 3 . 3. the preparation method of the photocurable water-based polyurethane emulsion described in any one of claim 1～2, comprises the following steps: a) after isophorone diisocyanate and dibutyltin dilaurate are mixed, polytetrahydrofuran diol is added dropwise, and then the first reaction is carried out to obtain a reaction mixture; b) adding dimethylolpropionic acid to the reaction mixture obtained in step a) to carry out the second reaction, then adding triethylamine to form salt, adding anhydrous ethylenediamine to carry out chain extension, adding self-repairing monohydrate body, photocurable monomer and p-hydroxyanisole, carry out the third reaction, and finally add water for emulsification to obtain photocurable waterborne polyurethane emulsion; The self-healing monomer is 2-amino-4-hydroxy-6-methylpyrimidine. 4 . The preparation method according to claim 3 , wherein the temperature of the dropwise addition in step a) is 65° C. to 85° C. and the time is 10 min to 25 min. 5 . 5 . The preparation method according to claim 3 , wherein the temperature of the first reaction in step a) is 75° C. to 90° C. and the time is 1.5 h to 3.5 h. 6 . 6 . The preparation method according to claim 3 , wherein the temperature of the second reaction in step b) is 65° C. to 85° C. and the time is 1.5 h to 3.5 h. 7 . 7. The preparation method according to claim 3, wherein the temperature of the salt formation in step b) is 40°C to 55°C, and the time is 25min to 65min; The chain extension time is 10min-35min. 8 . The preparation method according to claim 3 , wherein the temperature of the third reaction in step b) is 55° C. to 75° C. and the time is 2.5 h to 4.5 h. 9 . 9. The preparation method according to any one of claims 3 to 8, wherein the step b) further comprises: In the third reaction process, acetone was added to adjust the viscosity of the reaction system; and after the emulsification process, the acetone was distilled off under reduced pressure. 10 . A cured film, characterized in that, it is prepared from the photocurable water-based polyurethane emulsion according to any one of claims 1 to 2 by photocuring.

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