CN115873208A - Low-modulus high-resilience waterborne polyurethane and preparation method thereof - Google Patents

Abstract

The invention discloses low-modulus high-resilience waterborne polyurethane and a preparation method thereof. According to the invention, through molecular structure design, cross-linking structures are respectively introduced into a soft segment region and a hard segment region of polyurethane, so that cross-linking points are uniformly distributed on a polyurethane molecular chain. The existence of the cross-linking structure not only destroys the structural regularity of the polyurethane molecular chain to hinder the crystallization of a hard section region and reduce the modulus of the polyurethane material, but also can prevent the polyurethane molecular chain from generating mass center slippage under the action of external force and reduce the permanent deformation. Therefore, the problems of large permanent deformation, low rebound speed and high modulus of the polyurethane material can be solved.

Description

A kind of waterborne polyurethane with low modulus and high resilience performance and preparation method thereof

technical field

The invention relates to the technical field of water-based polyurethane preparation, in particular to a water-based polyurethane with low modulus and high resilience performance and a preparation method thereof.

Background technique

The full name of polyurethane is polyurethane, which refers to a class of polymer compounds containing carbamate groups in the molecular chain. Water-based polyurethane is a new type of polyurethane system that uses water instead of organic solvents as the dispersion medium. Its molecular structure contains carbamate groups, urea bonds and ionic bonds. It has high cohesive energy and strong adhesion. The proportion of polyurethane can adjust the performance of polyurethane, and it has a wide range of applications in the field of medical devices such as artificial heart vessels, artificial skin, and stents. In addition, water-based polyurethane does not contain or contain a small amount of organic solvents, and has the characteristics of non-combustibility, energy saving, green environmental protection, etc., which meets the current environmental protection requirements for energy saving and emission reduction.

The molecular chain of water-based polyurethane has a linear structure. After being subjected to external force, the center of mass of the polyurethane molecular chain slips, which makes it have a large permanent deformation (permanent deformation>30%) and a slow rebound speed (deformation recovery time>5min) during use. . In addition, waterborne polyurethane has a typical microphase separation structure, in which the hard segment region acts as a physical crosslinking point to provide excellent strength for polyurethane materials, which also leads to high modulus of polyurethane materials. Therefore, water-based polyurethane has low tensile permanent deformation (permanent deformation <5%), fast rebound speed (95% deformation recovery time <0.5min), low modulus requirements (<10MPa) and other low modulus and high resilience performance requirements. The application of high balloon catheter, disposable gloves, condoms and other fields is limited.

In order to solve the problems of large permanent deformation, slow recovery speed and high modulus of water-based polyurethane materials, common strategies include using low-modulus raw materials or introducing cross-linked structures in the hard segment of water-based polyurethane. For example, U.S. Patent US20120121902A1 uses low-modulus polytetramethylene glycol and polyether polyol as the main raw materials to prepare water-based polyurethane. The water-based polyurethane obtained by this scheme is soft and has good resilience, but the resin still has a rebound speed. slow problem. Commonly used methods for introducing cross-linking structures into the hard segment of polyurethane mainly include metal ion cross-linking, organic compound cross-linking, carboxyl cross-linking, etc. The cross-linking structure of the hard segment destroys the regularity of the chain structure of the hard segment to a certain extent. Weaken the degree of microphase separation of waterborne polyurethane, reduce the amount of hard segment region as a physical crosslinking point, and reduce the modulus of waterborne polyurethane material; in addition, changing part of the linear structure of waterborne polyurethane into a body structure also improves The rebound performance of waterborne polyurethane materials. However, although the cross-linking method in which the cross-linking structure is mainly distributed in the hard segment region has improved the resilience performance of polyurethane, it still has the problem of large permanent deformation (>15%) and rapid recovery.

Therefore, it is of great significance to develop a waterborne polyurethane with small permanent deformation, fast rebound speed and low modulus.

Contents of the invention

Aiming at the above-mentioned problems in the prior art, the present invention provides a low-modulus, high-resilience water-based polyurethane and a preparation method thereof, which solve the problems of slow rebound and large permanent deformation of existing water-based polyurethane materials. The method of the invention introduces cross-linking structures into the soft segment region and the hard segment region of the polyurethane through molecular structure design, so that the cross-linking points are uniformly distributed on the polyurethane molecular chain. The existence of the cross-linked structure not only destroys the structural regularity of the polyurethane molecular chain, hinders the crystallization of the hard segment region, reduces the modulus of the polyurethane material, but also prevents the center of mass of the polyurethane molecular chain from slipping, reducing the permanent deformation of stretching. Therefore, the introduction of cross-linked structures in the soft segment region and hard segment region of waterborne polyurethane can solve the problems of large permanent deformation, slow rebound speed and high modulus of polyurethane materials.

To achieve the above object, the present invention provides the following technical solutions:

A water-based polyurethane with low modulus and high resilience performance. The water-based polyurethane introduces cross-linking points in the soft segment region and the hard segment region respectively to form a cross-linked network structure.

Preferably, the waterborne polyurethane is polymerized by macromolecular polyols and diisocyanates under the action of small molecule chain extenders; the molecular weight of the macromolecular polyols is 600-5000, including polybutadiene polyols, polyisobutylene polyols At least one of alcohol, polybutadiene-acrylonitrile copolymerized glycol, and castor oil. More preferably, the macromolecular polyol also includes polyether polyol, adipic acid type polyester polyol, polytetramethyl ether glycol, phthalic anhydride type polyester polyol, polycarbonate polyol, polyethylene glycol One or more of lactone polyols and dimer acid polyester polyols.

Preferably, the molar ratio of diisocyanate to macromolecular polyol is 1-10:1, and the molar ratio of diisocyanate to small molecule chain extender is 1-10:1.

Preferably, the small molecule chain extender includes at least one of a carboxyl-containing chain extender and a double bond chain extender. More preferably, the small molecule chain extender also includes 1,3-propanediol, pentaerythritol, ethylene glycol, glycerol, methyldiethanolamine, 1,4-butanediol, 1,2-dibromobutyl Diol, 2,3-dibromobutanediol, sodium 1,2-dihydroxy-3-propanesulfonate, ethylenediaminoethanesulfonate, ethylenedihydroxyethanesulfonate, 2,4-diamino One or more of sodium benzenesulfonate and 2,2-dimethyl-1-propanesulfonate.

Preferably, the carboxyl-containing chain extender includes [carboxymethyl-(2,4-dihydroxybenzyl)amino]acetic acid, hydroxycitric acid, 3,5 diaminobenzoic acid, 2,2-hydroxymethylbutyl One or more of acid, 2,2-hydroxymethyl propionic acid, N,N-dihydroxy monomaleamic acid.

Preferably, the double bond-containing chain extender includes kelpene diol, hexene 5-1,2-diol, 3-hexene-1,6-diol, 3-hexene-2,5 -One or more of diol, ethylene glycol, butylene glycol.

Preferably, the diisocyanate includes isophorone diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, polyether modified toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, trimethylhexane One or more of diisocyanate, tetramethylxylylene diisocyanate, and lysine diisocyanate.

In addition, the present invention also provides a method for preparing the water-based polyurethane with low modulus and high resilience performance as described above, comprising the following steps:

(1) Prepolymerization reaction: After adding diisocyanate, small molecule chain extender and catalyst in sequence to the macromolecular polyol for prepolymerization reaction, a polyurethane prepolymer is obtained;

(2) Emulsification process: Add the polyurethane prepolymer into an emulsifier equipped with a crosslinking agent and water for emulsification. The specific conditions for emulsification are: first pre-emulsify for 5-15min under the condition of 6000-20000r/min, and then Stirring is continued for 1-3 hours under the condition of 1000-2000r/min to obtain a water-based polyurethane emulsion.

Preferably, the above-mentioned preparation method is specifically:

(1) Prepolymerization reaction: Add macromolecular polyols into the reaction kettle, heat and dehydrate under vacuum conditions, and after cooling down to 50-70°C, pass nitrogen protection into the reaction kettle, remove the vacuum equipment at the same time, and add two Isocyanate, small molecule chain extender, catalyst, stirred and heated to 60-80°C, and then kept at this temperature and under protective gas for 1-6h to obtain a polyurethane prepolymer;

(2) Emulsification process: Add the polyurethane prepolymer obtained in step (1) into an emulsifier equipped with a crosslinking agent and water for emulsification. The specific steps of emulsification are: emulsify for 20-60min under the condition of 8000-20000r/min , to obtain aqueous polyurethane emulsion.

The components of the water-based polyurethane emulsion are calculated by mass percentage, the polyurethane prepolymer accounts for 10-50%, and the rest is water.

Preferably, the catalyst in step (1) is stannous octoate.

Preferably, the crosslinking agent in step (2) includes at least one of a carboxyl crosslinking agent and a double bond crosslinking agent, and the amount thereof is 0.05%-10% of the amount of the polyurethane resin.

Preferably, the carboxyl crosslinking agent includes one or more of methylaziridine, aziridine, polycarbodiimide, metal ion crosslinking agent, and epoxysilane agent. More preferably, the metal ion crosslinking agent includes one or more of Ca ²⁺ , Cu ²⁺ , Fe ³⁺ , Fe ²⁺ , Zn ²⁺ ; the double bond crosslinking agent includes sulfur, ammonium persulfate, One or more of potassium persulfate, sodium persulfate, and hydrogen peroxide.

The beneficial effects of the present invention are as follows:

1. The introduction of cross-linked structures in the soft segment and hard segment of waterborne polyurethane can destroy the structural regularity of the polyurethane molecular chain, hinder the crystallization of the hard segment, and reduce the modulus of the waterborne polyurethane material.

2. The introduction of cross-linked structures in the soft and hard segments of water-based polyurethane can prevent the center of molecular chains in the soft and hard segments of the polyurethane material from slipping under external force, and reduce tensile permanent deformation. And after the external force is removed, under the action of the crosslinking point, the stretched molecular chain recovers quickly, accelerating the deformation recovery speed.

3. Based on the traditional polyurethane synthesis process, the present invention introduces cross-linking sites into the soft segment and hard segment of the polyurethane to obtain water-based polyurethane with uniform distribution of cross-linking points. The method is simple and easy.

Description of drawings

Figure 1 is a comparison chart of the tensile properties of water-based polyurethane obtained in Example 1, Comparative Example 1 and Comparative Example 2.

Fig. 2 is a comparison chart of the resilience properties of water-based polyurethane obtained in Example 1, Comparative Example 1 and Comparative Example 2.

Detailed ways

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the embodiments in this application, those of ordinary skill in the art will Other similar embodiments obtained without creative work shall all fall within the scope of protection of this application.

Example 1:

A kind of preparation method of the waterborne polyurethane of low modulus high resilience performance, comprises the steps:

(1) Prepolymerization reaction: Add 81g (40.5mmol) of polytetrahydrofuran ether diol with a molecular weight of 2000 and 27g (13.5mmol) of polybutadiene diol with a molecular weight of 2000 into the reactor, and heat it to 90°C under vacuum After dehydration for 2 hours, the temperature of the reactor was lowered to 60°C, and the vacuum equipment was removed while passing nitrogen into the reactor, and 56.76g (255.3mmol) of isophorone diisocyanate, 13.32g (90mmol) of 2,2-diisocyanate were Methylolbutyric acid and 0.1 g of stannous octoate catalyst were sequentially added into the above reactor, and reacted at 75° C. for 3 hours to obtain a prepolymer.

(2) Emulsification process: pour the prepolymer obtained in step (1) into an emulsifier equipped with 0.2g aziridine, 0.5g ammonium persulfate, and deionized water, and emulsify for 25min at a speed of 15000rpm to obtain a stable Uniform water-based polyurethane emulsion.

The aqueous polyurethane emulsion prepared in this example was formed into a film, and the elastic modulus of the film was measured to be 4 MPa, the tensile permanent deformation was 2.5%, and the deformation recovery time was 0.2 min.

Example 2:

A kind of preparation method of the waterborne polyurethane of low modulus high resilience performance, comprises the steps:

(1) Prepolymerization reaction: Add 81g (40.5mmol) of polybutadiene-acrylonitrile copolymerized glycol with a molecular weight of 2000 to the reactor, heat to 90°C for 2 hours in a vacuum state, and then cool the reactor to 50 ℃, remove the vacuum equipment while blowing nitrogen into the reaction kettle, mix 34.83g (200mmol) toluene diisocyanate, 25.44g (205mmol) hexamethylene diisocyanate, 2.28g (30mmol) 1,3-propanediol, 1.60g (10.5 mmol) 3,5 diaminobenzoic acid and 0.1 g of stannous octoate catalyst were sequentially added into the above reaction kettle, and reacted at 80° C. for 3 h to obtain a prepolymer.

(2) Emulsification process: pour the prepolymer obtained in step (1) into an emulsifier equipped with 0.2g copper chloride, 0.5g sulfur, and deionized water, and emulsify for 20min at a speed of 20000rpm to obtain a stable and uniform Water-based polyurethane emulsion.

The water-based polyurethane emulsion prepared in this example was formed into a film, and the elastic modulus of the film was measured to be 6 MPa, the tensile permanent deformation was 3%, and the deformation recovery time was 0.4 min.

Example 3:

A kind of preparation method of the waterborne polyurethane of low modulus high resilience performance, comprises the steps:

(1) Prepolymerization reaction: Add 93g (100mmol) of castor oil with a molecular weight of 930 and 100g (100mmol) of polyneopentyl adipate with a molecular weight of 1000 into the reactor, and heat it to 90°C for 2 hours under vacuum. , then the reactor was cooled to 60°C, and the vacuum equipment was removed while nitrogen was passed into the reactor, and 52.47g (200mmol) dicyclohexylmethane diisocyanate, 44.27g (100mmol) kelp-alene diol, 15.22 g (100 mmol) of 3,5-diaminobenzoic acid and 0.1 g of stannous octoate catalyst were sequentially added into the above reactor, and reacted at 60° C. for 3 h to obtain a prepolymer.

(2) Emulsification process: pour the prepolymer obtained in step (1) into an emulsifier equipped with 0.2g polycarbodiimide, 0.5g epoxysilane, and deionized water, and emulsify for 20min at a speed of 8000rpm. Obtain a stable and uniform water-based polyurethane emulsion.

The water-based polyurethane emulsion prepared in this example was used to form a film, and the elastic modulus of the film was measured to be 7 MPa, the tensile set was 4%, and the deformation recovery time was 0.3 min.

Example 4:

A kind of preparation method of the waterborne polyurethane of low modulus high resilience performance, comprises the steps:

(1) Prepolymerization reaction: Add 60g (30mmol) of polyisobutylene diol with a molecular weight of 2000 and 91g (40.5mmol) of polytetrahydrofuran ether diol with a molecular weight of 2000 into the reactor, and heat it to 90°C for 2 hours under vacuum. , then the reactor was cooled to 60°C, and the vacuum equipment was removed while passing nitrogen in the reactor, and 33.35g (150mmol) isophorone diisocyanate, 21.27g (100mmol) trimethylhexane diisocyanate, 1.16g (10mmol) hexene 5-1,2-diol, 1.2g (20mmol) ethylene glycol, 3.70g (20mmol) 2,2-dimethyl-1-propanesulfonate, 0.1g stannous octoate Catalysts were sequentially added to the above reactor, and reacted at 60°C for 5 hours to obtain a prepolymer.

(2) Emulsification process: Pour the prepolymer obtained in step (1) into an emulsifier equipped with 0.7 g of sodium persulfate and deionized water, and emulsify at a speed of 13000 rpm for 50 min to obtain a stable and uniform water-based polyurethane emulsion.

The water-based polyurethane emulsion prepared in this example was used to form a film, and the elastic modulus of the film was measured to be 4 MPa, the tensile set was 4%, and the deformation recovery time was 0.2 min.

Example 5:

A kind of preparation method of the waterborne polyurethane of low modulus high resilience performance, comprises the steps:

(1) Prepolymerization reaction: Add 81g (40.5mmol) of polybutadiene diol with a molecular weight of 2000 and 100g (50mmol) of polycarbonate diol with a molecular weight of 2000 into the reactor, and heat it to 90°C under vacuum After dehydration for 2 hours, the temperature of the reactor was lowered to 60°C, and the vacuum equipment was removed while passing nitrogen into the reactor, and 48.86g (200mmol) of tetramethylxylylene diisocyanate, 3.15g (15mmol) of 2,4- Sodium diaminobenzenesulfonate, 1.32g (15mmol) butylene glycol, and 0.1g stannous octoate catalyst were successively added into the above reactor, and reacted at 60°C for 5h to obtain a prepolymer.

(2) Emulsification process: pour the prepolymer obtained in step (1) into an emulsifier equipped with 0.7 g of sodium persulfate and deionized water, and emulsify at a speed of 15000 rpm for 50 min to obtain a stable and uniform water-based polyurethane emulsion.

The water-based polyurethane emulsion prepared in this example was used to form a film, and the elastic modulus of the film was measured to be 3 MPa, the tensile set was 4%, and the deformation recovery time was 0.2 min.

Comparative example 1

Operate according to the method of Example 1, the difference is that only the water-based polyurethane hard segment area is cross-linked, that is: when emulsifying, the prepolymer obtained in step (1) is poured into an emulsifying emulsion containing 0.2g aziridine and deionized water In the device, all the other conditions (such as: raw material type, consumption and technological process etc.) are all identical with embodiment 1, obtain stable and uniform aqueous polyurethane emulsion.

The water-based polyurethane emulsion prepared in this comparative example was formed into a film, and the elastic modulus of the film was measured to be 15 MPa, the tensile set was 20%, and the deformation recovery time was 5 minutes.

Comparative example 2

According to the method operation of embodiment 1, difference is not cross-linked to aqueous polyurethane, that is: during emulsification, the prepolymer that step (1) obtains is poured in the emulsifier that only deionized water is housed, and all the other conditions (such as : raw material type, consumption and technological process etc.) are all identical with embodiment 1, obtain stable and uniform aqueous polyurethane emulsion.

The aqueous polyurethane emulsion prepared in this comparative example was formed into a film, and the measured elastic modulus of the film was 26 MPa, the tensile set was 23.4%, and the deformation recovery time was 8 minutes.

It can be seen from Fig. 1 that the tensile strength of the waterborne polyurethane obtained in Example 1 is the lowest (the tensile strength is 5.1 MPa), and the elongation at break is the highest (the elongation at break is 922%). This is mainly due to the introduction of cross-linked structures in the soft segment and hard segment of waterborne polyurethane, which destroys the structural regularity of the polyurethane molecular chain, hinders the crystallization of the hard segment, and reduces the modulus of the waterborne polyurethane material, so the tensile strength is low. High elongation at break. In addition, based on the double cross-linking structure of polyurethane soft segment region and hard segment region, the network cross-linking structure formed by moderate chemical bonds between molecular chains can prevent the center of mass between molecular chains from slipping, so the recovery of waterborne polyurethane obtained by this system The elastic performance is the best, and the deformation can reach a deformation recovery rate of 97.5% in 0.2 minutes, and the tensile permanent deformation is small, which is 2.5% (as shown in Figure 2). By comparison of Fig. 1, it can be known that the tensile strength of comparative example 1 gained water-based polyurethane is higher than that of Example 1 (the tensile strength is 14.6MPa), and the elongation at break is smaller than that of Example 1 (the elongation at break is 584%). Mainly because the cross-linking structure is only introduced into the hard segment region of water-based polyurethane, although the structural regularity of the hard segment region is destroyed to a certain extent, the degree of crystallization of the hard segment region of water-based polyurethane is reduced, and the hard segment as a physical cross-linking point is reduced. The amount of the segment area reduces the modulus of the water-based polyurethane material, but this regional cross-linking structure limited to the hard segment area cannot fundamentally solve the problems of high modulus and poor rebound of the water-based polyurethane material, so the water-based polyurethane material obtained by this system The resilience performance of polyurethane is worse than that of Example 1, the deformation recovery rate is 89% in 5 minutes, and the tensile permanent deformation is relatively large, which is 44% (as shown in Figure 2). The corresponding tensile strength of the water-based polyurethane prepared in comparative example 2 without chemical crosslinking structure is the largest (the tensile strength is 26.7MPa), and the elongation at break is the lowest (the elongation at break is 425%), and this is mainly because the obtained The molecular chain structure of water-based polyurethane is well-regulated, and the molecular chains in the hard segment can be regularly arranged under the action of hydrogen bonds to form regions with higher crystallinity as physical strengthening points. In addition, when the material is subjected to external force, the center of mass of the molecular chain slips, so the deformation recovery speed is the slowest, the deformation recovers 80.5% in 8 minutes, and the tensile permanent deformation is the largest, 78%.

In addition, it should be understood that although this specification is described according to implementation modes, not each implementation mode only contains an independent technical solution, and this description in the specification is only for clarity, and those skilled in the art should take the specification as a whole , the technical solutions in the various embodiments can also be properly combined to form other implementations that can be understood by those skilled in the art.

Claims (10)

1. The waterborne polyurethane with low modulus and high resilience is characterized in that crosslinking points are respectively introduced into a soft segment region and a hard segment region of the waterborne polyurethane to form a crosslinked network structure.

2. The waterborne polyurethane of claim 1, wherein the waterborne polyurethane is prepared by polymerizing macromolecular polyol and diisocyanate under the action of a micromolecular chain extender and a catalyst; the macromolecular polyol comprises at least one of polybutadiene polyol, polyisobutylene polyol, polybutadiene-acrylonitrile copolymer glycol and castor oil.

3. The aqueous polyurethane of claim 2, wherein the molar ratio of diisocyanate to macropolyol is 1 to 10, and the molar ratio of diisocyanate to small chain extender is 1 to 10.

4. The aqueous polyurethane of claim 2, wherein the macropolyol further comprises one or more of polyether polyol, adipic acid type polyester polyol, polytetramethylene ether glycol, phthalic anhydride type polyester polyol, polycarbonate polyol, polycaprolactone polyol, and dimer acid polyester polyol.

5. The aqueous polyurethane of claim 2, wherein the small molecule chain extender comprises at least one of a carboxyl group-containing chain extender and a double bond chain extender.

6. The aqueous polyurethane of claim 5, wherein the small molecule chain extender further comprises one or more of 1, 3-propanediol, pentaerythritol, ethylene glycol, glycerol, methyldiethanolamine, 1, 4-butanediol, 1, 2-dibromobutanediol, 2, 3-dibromobutanediol, sodium 1, 2-dihydroxy-3-propanesulfonate, ethylenediamine ethanesulfonate, ethylene dihydroxy ethanesulfonate, sodium 2, 4-diaminobenzenesulfonate, and 2, 2-dimethyl-1-propylaminesulfonate.

7. The aqueous polyurethane of claim 5, wherein the carboxyl-containing chain extender comprises one or more of [ carboxymethyl- (2, 4-dihydroxybenzyl) amino ] acetic acid, hydroxycitric acid, 3,5 diaminobenzoic acid, 2-hydroxymethylbutyric acid, 2-hydroxymethylpropionic acid, N-dihydroxymonomaleamic acid.

8. The waterborne polyurethane of claim 5, wherein the chain extender containing double bonds comprises one or more of huperzine diol, hexene 5-1, 2-diol, 3-hexene-1, 6-diol, 3-hexene-2, 5-diol, ethylene diol, and butene diol.

9. The aqueous polyurethane of claim 5, wherein the diisocyanate comprises one or more of isophorone diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, polyether-modified toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, trimethylhexane diisocyanate, tetramethylxylene diisocyanate, and lysine diisocyanate.

10. A process for preparing the low modulus, high resilience aqueous polyurethane of any of claims 1 to 9 comprising the steps of:

(1) Prepolymerization reaction: sequentially adding diisocyanate, a micromolecular chain extender and a catalyst into the macromolecular polyol to carry out prepolymerization reaction to obtain a polyurethane prepolymer;

(2) And (3) an emulsification process: adding the polyurethane prepolymer into an emulsifier filled with a cross-linking agent and water for emulsification, wherein the specific emulsification conditions are as follows: pre-emulsifying for 5-15min under the condition of 6000-20000r/min, and then continuously stirring for 1-3h under the condition of 1000-2000r/min to obtain the waterborne polyurethane emulsion.

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