A Novel Strategy for Preparation of Solvent-Free High-Solid Content Water-Based Polyurethane

doi:10.21203/rs.3.rs-2830065/v1

Download PDF

Research Article

A Novel Strategy for Preparation of Solvent-Free High-Solid Content Water-Based Polyurethane

https://doi.org/10.21203/rs.3.rs-2830065/v1

This work is licensed under a CC BY 4.0 License

Journal Publication

published 13 Jun, 2023

Read the published version in Journal of Polymer Research →

You are reading this latest preprint version

Eethylenediamine (EDA), isophorone diamine (IPDA), diethylenetriamine (DETA), N- β- (aminoethyl)- γ- aminopropylmethyl dimethoxysilane (KH602) and polyether amine (D-230) were used as post chain extenders, a series of solvent-free high-solid content water-based polyurethanes (WPU) were prepared. The reactivity of different post chain extenders and the effects of different R values (mole ratio of –NCO/-OH) on solid content as well as the effects of chain extension degree on properties of WPU were investigated in detail. Among of water, small molecule diamine and diol, diamine with higher activity is preferred to water to complete the post chain extension reaction and improves the mechanical properties of WPU. When the R value is higher than 1.7 and the post chain extension degree is controlled at 70%, the viscosity of the solvent-free prepolymer is small enough to be emulsified, and the as-prepared WPUs show more excellent thermodynamic properties. In comparison, the cyclic chain extender such as IPDA can improve the mechanical properties and heat resistance of WPU, crosslinking type chain extenders involving DETA and KH602 can improve the heat resistance and anti-sticking of WPU coating. Whilst the WPU prepared by the chain extender containing flexible space, such as D-230, has a very low modulus and is suitable for preparing soft–type WPU.

Post chain extender

Solvent-free

High solid content

Waterborne polyurethane

Waterborne polyurethane (WPU) has found extensive commercial applications in various substrates such as genuine leather finishing, artificial leather coating, textile lamination, plastics, wood as well as ceramics coating by virtue of their environment-friendly characteristics, outstanding performances and remarkable versatility [1]. However, due to the larger latent heat of vaporization of water (40.8 KJ/mol) and higher saturated vapor pressure, the drying speed of WPU coating is slower than that of solvent-based polyurethane coating, which leads to high energy consumption and low drying efficiency, so developing high-solid content WPU is suggested to be an efficient way to solve this problem [2]. Based on this, the preparation of high-solid content WPU has become a research hotspot in recent years. At present, most works were focused on the preparation of WPU with bimodal particle size distribution, and the closest stacking effect can be achieved by adjusting the particle size ratio of large particle size latex particles to small particle size emulsion particles [3, 4]. Chai et al. [5] prepared small particle size WPU₁ firstly, then designed a large particle size WPU₂, and emulsified the prepolymer of WPU₂ with WPU₁. It was found that when the mass ratio of WPU₁ to WPU₂ was 1: 5 and the particle size ratio was 1: 8.6, the solid content of WPU reached 66.07% and the viscosity was 285 mPa.s. Hou et al. [6] employed the same method to prepare WPU with high solid content. Through building the corresponding three-dimensional stacking model and regulating the weight ratio of small particle size WPU to large particle size WPU to 1: 7, 1: 4.75 or 1: 2.87, a series high solid content WPU can be obtained. These methods are beneficial for the improvement of solid content, but they all need solvents to reduce the viscosity of prepolymer so as to enhance the dispersibility of prepolymer in water. Up to now, the high solid content WPU used in the market is also basically prepared by so-called acetone method. Water-soluble solvents such as acetone or butanone are used to reduce the viscosity of prepolymer, and then the solvent is distilled to recover. This method belongs to labor and time consuming type and the additional equipment investment is needed. Therefore, how to develop solvent-free WPU with high solid content has become a challenge for the WPU industry.

As well known that the viscosity of the prepolymer for WPU is closely related to R value (mole ratio of –NCO/-OH). The larger the value of R, the lower the viscosity of prepolymer and the easier of their emulsification [7, 8, 9]. On the contrary, the prepolymer with high viscosity is hard to be emulsified in water. However, when the R value of the prepolymer itself is too high, the molecular weight (M_w) of the prepolymer will be decreased, undoubtedly, the thermodynamic properties of resultant WPU will also be reduced. Therefore, a post chain extender method must be employed to improve the M_w and the thermodynamic properties of WPU as shown in Fig. 1(a) [10, 11, 12]. In the post-chain extension reaction in aqueous system, -NCO group will inevitably react with water to form urea bond, releasing CO_2, which reduces the atomic utilization of diisocyanate, so this kind of side-reaction should be avoided as far as possible. For this reason, the selected post chain extender must have high reaction activity, which is superior to water. Besides, the amount and type of post-chain extender also have great influence on the properties of the final polymer. The addition of excessive chain extender often plays the role of end capping rather than chain extension, and decreases the thermodynamic properties of WPU. Furthermore, DETA and KH602 have double chain extension and cross-linking effect, in Kim et al’s [13] work, they found that with the increase of cross-linking degree, the modulus of WPU increased and the elongation at break decreased greatly, so too high cross-linking introduced in the process of chain extension will change the properties of resultant WPU.

Based on the above analysis, in this paper, the reactivity of different post chain extenders and the effects of different R values on solid content as well as the effects of chain extension degree on properties of WPUs were investigated in detail firstly, then isophorone diamine (IPDA), ethylenediamine (EDA) and polyether amine (D-230), diethylenetriamine (DETA), N- β- (aminoethyl)- γ- Aminopropyl methyldimethoxysilane (KH602) were used as post chain extenders, a series of solvent-free WPU with high solid content were prepared. Meanwhile, the contributions of different post chain extenders to the properties of WPU, involving emulsion properties, film-forming properties were clarified. The aim of this work is to provide a new approach for the preparation of solvent-free WPU with high solid content.

2.1 Materials

Isophorone diisocyanate (IPDI) was procured from Bayer Co. Polypropylene glycol (PPG, molecular weight of 2.0 × 10³ Da), Polytetrahydrofuran glycol (PTMG, molecular weight of 1.0 × 10³ Da) were provided from Mitsubishi Chemical Industrie Co., Ltd. Dimethylol butyric acid (DMBA), Bismuth Octoate (DY-20), Triethylamine (TEA), ethylenediamine (EDA), Isophorone diamine (IPDA), Diethylenetriamine (DETA), N- β- (aminoethyl)- γ- Aminopropyl methyl dimethoxysilane (KH602), O,O'-Bis(2-aminopropyl) polypropyleneglycol (D-230), N,N- dimethylformamide (DMF) were purchased from Aladdin. Alcohol ether carboxylate (AEC) was supplied from Shanghai Fine Chemical Co., Ltd. The structural formula of the post chain extenders selected in this paper are shown in Fig. 1(b).

2.2 Preparation of WPU

PPG and PTMG were added into the three-port flask equipped with thermometer and stirrer, and dehydrated in vacuum at 120 ℃ for 2 h. After cooled to 40 ℃, IPDI and a certain amount of organic bismuth catalyst (DY-20) were introduced, the reaction was carried out at 80 ℃ for about 1 h, followed by a chain extension reaction with DMBA and metered TEA at 60 ℃ for 3 h. When the content of -NCO reached the theoretical value (Determined by di-n-butylamine method [14]), deionized water and AEC were added for high shear emulsification, and then different post chain extenders were added for post chain extension respectively, hence a series of WPU emulsions with above 52 wt% were obtained.

2.3 Preparation of WPU film

The WPU emulsion were turned in a 3000 rpm centrifuge for 30 min, then an appropriate amount of lotions was coated to the tetrafluoroethylene film-forming plate. Semi-dried at room temperature and completely dried in 80 ℃ oven.

2.4 Characterization

At room temperature, Fourier transform infrared (FTIR) spectra of the coating in the wavenumber range of 4000 ~ 700 cm^− 1 were recorded using a Nicolet Nexus 470 (Thermo Fisher). To eliminate the influence of trace levels of moisture on the results, the samples were dried to a consistent weight prior to testing.

The viscosity of the emulsion at different rotation rates was tested by MCR rotary rheometer under dry condition.

The average particle size and zeta potential of latex particles were characterized by Dynamic Light Scattering Particle Size Analyzer. The samples were diluted 500 times before testing.

Molecular weight of WPU film was measured by Viscotek TDA305-GPC max multi-detection gel chromatography system.

Glass transition temperature (T_g) of WPU film was measured by DSC-200PC differential scanning calorimeter, and the heating rate was 10 ℃ /min. Under N₂ atmosphere, the tested temperature range was − 150 ~ 25 ℃.

Thermal decomposition temperature test was performed by using thermogravimetric analyzer TG209F3, the heating rate was fixed to 10 ℃/min, and the temperature range was 50 ~ 500 ℃ in N₂ atmosphere.

Mechanical property was examined according to QB/T 528–2009. The sample was pressed to 50 × 10 mm dumbbell shape, using the Electronic Universal Testing Machine to test at the tensile rate of 50 mm / min at room temperature. Each sample was tested for 5 times to take the average value, and recorded the tensile strength and elongation when the film broke.

Anti-sticking property of WPU film was tested according to GB/T 34445 − 2017. The sample was cut to 60 × 60 mm, folding two samples in half, and placing in a constant-temperature oven of 100°C under 5 kg pressure. After 60 min, took out and cooled to room temperature. The peeling of samples was carried out on tensile machine at 10 mm/min and the peeling load were recorded.

3.1 FTIR spectrum of prepolymer and WPU

The infrared spectrum of prepolymer before and after emulsification are shown in Fig. 2. The characteristic peaks at 3322 cm^− 1 and 1532 cm^− 1 belong to N-H stretching vibration and bending vibration peaks respectively. The peak at 1731 cm^− 1 is ascribed to the -C = O characteristic peak of carbamate, the peaks at 2917 cm^− 1 and 2865 cm^− 1 represent the absorption peaks of -CH₃ and -CH₂- respectively. The bending vibration absorption peak of C-H in methylene group and the irregular stretching vibration absorption peak of C-O-C occur at 1597 cm^− 1 and 1097 cm^− 1. The peak at 2250–2270 cm^− 1 falls within the absorption peak of isocyanate group. It can be seen that this absorption peak disappears after emulsification, which reveals that the isocyanate groups can fully react with water in the process of emulsification

3.2 Effect of R values on solid content of WPU

As well known that the viscosity of prepolymer is closely associated with the R value (mole ratio of –NCO/-OH) of bulk polymerization system, which determines the viscosity and solid content of WPU products [15]. Herein, a series of R values (1.4, 1.5, 1.6, 1.7 and 1.8) were designed and the influence of different R values on the viscosity of prepolymer and the viscosity and solid content of WPU products were investigated. As shown in Fig. 3(a)-(b), with the increase of R value, the viscosity of prepolymer decrease rapidly, which is mainly due to the decrease of molecular weight (M_w) of prepolymer. When the R value is above 1.7, the prepolymer can be easily dispersed into water and ≥ 52 wt% solid content of WPU can be achieved. When the R values varied from 1.7 to 1.4, the viscosity of prepolymer increased rapidly, in the case of solvent-free, the emulsification of prepolymer become difficult and more water must be added to dilute the viscosity of WPU products, as a results, similar viscosity and high solid content WPUs are hard to be obtained.

3.3 Comparison of reaction activity of post chain extenders

When higher R value was employed to prepare solvent-free and high solid content WPU, large amount of -NCO groups will react with water and release CO₂ in process of emulsification, which leads to the problem of low atomic utilization of diisocyanate. Therefore, higher reactive post chain extender must be added to reduce this kind of side reaction. Small molecule diols and diamines are common chain extenders for polyurethane, herein, as a representative of diols and diamines, BDO and EDA were selected for post-chain extenders, and the R value was maintained to 1.7, the changes in mechanical properties of resultant WPUs were compared and the results were shown in Fig. 4(a), it can be seen that the tensile strength and broken elongation of EDA based WPU film are much higher than that of blank sample, which reveals that EDA is preferred to water to complete the post chain extension reaction and improves the mechanical properties of WPU. For BDO based WPU film, lower tensile strength and higher broken elongation were observed, this should be attributed to the plasticization of BDO rather than the post chain extension. In order to verify the above deduction, the same concentration of BDO was mixed with the blank sample (named WPU-BDO) and its mechanical properties was measured after film formation. It was found that two samples shown similar mechanical property, which indicates that the reaction activity of diols is lower than that of water, and the post chain extension reaction cannot be completed in the aqueous phase. Another evidence comes from the infrared spectrum analysis of BDO based WPU, as shown in Fig. 4(b), the peak at 3437 cm^-1 is the absorption peak of -OH, which overlaps with the peak of amino group (3322 cm^-1) and forms a larger peak, proving that BDO does not react with -NCO group. From above discussion, it can be sure that small molecule diamines are more suitable for the post chain extender of WPU.

3.4 Determination of amount of post chain extender

In order to determine the influence of the degree of post chain extension on properties on WPU, EDA was selected as chain extende, the influence of different post chain extension degrees of 0%, 30%, 50%, 70% and 100% on the particle size, zeta potential and mechanical properties of resultant WPUs were investigated.

As shown in Fig. 5(a), the blank sample (0%) shows the lowest particle size, and other samples show a tendency of increasing firstly then decreasing when the chain extension degree surpasses 70%. This is because chain extender molecules have two or more amino groups and can react with -NCO groups located both on the two amino groups on the surfaces of single particles or different particles [15]. Therefore, due to the bridging effect of multifunctional chain extenders, the size of individual particles may increase, and the particles may also aggregate together. However, when the chain extension is above 70%, too high chain extension degree will end-cap the -NCO groups of prepolymer and reduce the molecular weight of WPU. The difference in mechanical properties of WPU with different chain extension degree are shown in Fig. 5(b). With the increase of chain extension degree from 0–70%, the tensile strength and elongation at break of WPU increase gradually. The reason is that high polar diamine EDA was conducive to forming more hydrogen bonds in hard segments and forming a stronger inter-chain cohesive force after post-chain extension [16]. But when the chain extension degree reaches 100%, both the strain and stress decrease, which also results from the decrease of WPU molecular weight [17].

3.5 Effect of different post chain extenders on property of WPU emulsion

The particle sizes of different WPU emulsions are shown in Fig. 6(a). It can be seen that the particle sizes show an order of D-230 based WPU > IPDA and EDA based WPU > blank sample. As shown above, due to the bridging effect of post-chain extender, the particle size of latex particles enlarges with the increase of post-chain extension. Among them, D-230 based WPU has the largest particle size, this is because D-230 sample contains a longer hydrophobic chain links, in order to maintain the stability, latex particles have to absorb more water molecules to form a thicker hydration layer, thus increasing the particle size of latex.

The stability of emulsion can be evaluated by zeta potential. Generally, the emulsion is stable when the absolute value of zeta potential is more than 30 mV [18]. As shown in Fig. 6(b), the absolute value of zeta potential for blank, EDA and D-230 based WPU are above 40 mV, showing good stability. This value for IPDA based WPU decreases to 30 mV and shows a wide distribution, which indicates that this type of emulsion is in unstable state, in fact, a small amount of precipitates occurred 40 days later while the other groups remained stable after 6 months. Compared with other post chain extenders, IPDA has a 6 membered ring, which has strong rigidity and hydrophobicity, both enhanced the degree of microphase separation [19], thus decreased the stability of emulsion.

The viscosity of WPU emulsion is related to solid content, hydrophilic group content, hydrophilicity of macromolecular chain, latex particle size, et al. [20, 21]. Generally, the higher the solid content, the tighter the arrangement of latex particles, which improves the interaction between latex particles and increases the viscosity of emulsion. However, the viscosity of the emulsion is not completely determined by the solid content. When the solid content and hydrophilic group content are the same, the viscosity of WPU emulsion prepared from different chain extenders are shown in Fig. 6(c). It can be seen that the viscosity of WPU prepared by D-230 is much higher than that of others. This is because D-230 is a type of polyether amine, higher proportion of ether bonds in the molecular (as shown in Fig. 1(b)) decreases the physical cross-linking between hard segments. In this case, the molecules exist in a low-energy state of free elongation, and the long flexible chains make the molecules spiral and conclude with each other, resulting in the close connection between particles and molecules, leading to the viscosity of WPU increase [22]. Compared with D-230 based WPU, other WPUs showed lower viscosity at high shear rate, indicating that there was no difficulty in preparing WPU with high solid content by post chain extension method.

The difference in mechanical properties is shown in Fig. 6(d). IPDA, EDA, blank and D-230 based WPUs show high broken elongation, but different tensile strength. IPDA based WPU has the highest tensile strength due to its high rigidity. Compared to IPDA, EDA based WPU shows a relative higher tensile strength, this is because the macromolecular chain is more regular after chain extension, which enhances the degree of regularity and the force of hydrogen bond between macromolecules, as a result, increasing the mechanical strength. D-230 contains flexible ether bonds, the low barrier energy imparts the resultant WPU the lowest tensile strength and the highest broken elongation [23]. From above discussion we found that the mechanical properties of WPU can be regulated by adding different post chain extenders, even if every chain extender has different effects on the mechanical properties.

Post-crosslinking agent can enhance the mechanical properties and thermal stability of WPUs, but too much post-crosslinking degree will lead to the decline of elongation at break seriously [13]. Herein, a small amount of post-crosslinking type chain extenders (DETA and KH602) combined with EDA were used as post-chain extender to further enhance the performance of polyurethane. Figure 7(a) list the particle sizes of EDA, EDA-DETA and EDA-KH602 based WPUs, it can be seen that the particle sizes of the three samples are small and similar, which reveals that post-crosslinking has little effect on the particle size of WPUs. However, the zeta potential of EDA-KH602 sample is lower than that of the other samples. Because KH602 is a silane coupling agent, it will hydrolyze first when encounter water (As described in Fig. 1(c)), then expand and crosslink with prepolymer, thereby enhance the microphase separation. Meanwhile, Si-O-Si is hydrophobic, all decreases the emulsion stability. DETA contains three amine groups, in chain extension process, more hydrophilic urea bonds were introduced, which increase the hydrophilibility and improve the stability of emulsion, so the zeta potential is greater for EDA-DETA based WPU than for EDA-KH602 based WPU.

Multifunctional post chain extender has great influence on mechanical properties, as shown in Fig. 7(b). The stress and strain of EDA-DETA and EDA-KH602 based WPU are obviously higher than that of EDA based WPU, chain extension and crosslinking both contribute the WPU higher the mechanical properties [24]. Compared with EDA-DETA based sample, EDA-KH602 based WPU has higher elongation at break and lower modulus, which should be ascribed to the softness of Si-O-Si and less hydrogen bonds in hard segments.

The thermal stability of WPU was evaluated by TG analysis and the results were shown in Fig. 7(c)-(d). According to the slope of the curve, the thermal decomposition of WPU can be divided into three stages. The first stage of weight loss is in a range of 200 ~ 250 ℃, which corresponds to the fracture of carbamate groups. The second stage of weight loss section is in 280 ~ 350 ℃, which corresponds to the fracture of urea bond, and the third stage of weight loss is about in 350 ~ 430 ℃, which corresponds to the fracture of soft segments in WPU [25]. As shown in Fig. 7(c), the 5% weight loss temperature of all WPUs are above 260 ℃, indicating that the different post chain extenders have little effect on the thermal stability of carbamate bonds. In the second stage, the weight loss of EDA-KH602 based WPU is lower than that of other WPUs, this is because the content of urea bond is lower for the EDA-KH602 based WPU than for others. With the increasing degree of thermal degradation, EDA-KH602 based WPU exhibits higher thermal stability, the reason comes from the difference in bond energy of Si-O-Si bond (452 kJ/mol), C-O bond (351 kJ/mol) and C-C bond (347 kJ/mol), higher bond energy of Si-O-Si endows WPU higher thermal degradation stability [26].

The cold resistance of WPUs, evacuated by the glass transition temperature (T_g), are characterized by DSC analysis. The results are shown in Fig. 7(e). It can be seen that the T_g of WPUs show an order of EDA-KH602 (-50.8 ℃) > EDA-DETA (-53.1 ℃) > EDA (-55.3 ℃) ༞Blank (-55.9 ℃) ༞IPDA (-56.6 ℃) ༞D-230 (-57.4 ℃). After the post chain extension of D-230, the molecular chain become more softer, so D-230 based WPU shows the lowest T_g. Obviously, cross-linking type post chain extenders such as KH 602 and DETA, all reduces the cold resistance of WPU, and the T_g tend to increase. Although there is a certain difference, the T_g of WPU prepared by different post chain extenders are between − 58~-50 ℃, still showing good cold resistance.

Another important performance for WPU film or coating is the heat resistance or anti-sticky when the film or coating undergo a hot pressure (at 100 ℃ and 5 Kg pressure). Generally, high temperature can activate the movement of polymer units, the volume of polymer expands and provides more free space for the movement of polymer unit, thus producing heat-sticky phonomenno. It can be seen from Fig. 7(f) that the peeling load is greater for EDA based WPU than for EDA-DETA and EDA-KH602 based WPU when the films are separated, which means the anti-sticky of WPU film or coating follows the order of EDA-DETA based WPU > EDA-KH602 based WPU > EDA based WPU. This is because DETA and KH602 can provide a certain degree of crosslinking and prevents the chain segments from movement. Compared with EDA-DETA based WPU, the peeling load is slightly higher for EDA-KH602 based WPU film, this should be attributed to the softness of polymer chains. The peeling strength of IPDA based WPU is similar to that of EDA-KH602 based WPU, this is because the 6 membered ring in IPDA gives the macromolecular chain rigidity and improves the anti-sticky performance of the coating. The peeling strength of D-230 based WPU is the largest, indicating that the thermal viscosity is the strongest. This is precisely because the flexible main chain of D-230 based WPU intensifies the rotation and movement of polymer chains at high temperature, leading the adhesion of the two coatings layers.

A novel strategy for preparing solvent-free WPU with high solid content was put foreword and identified in valid, the choice of higher R value (mole ratio of -NCO/-OH) and higher activity diamine (post chain extender) is the key issue for preparing this type of WPU. When the R value is above 1.7, the viscosity of the prepolymer without any solvent is small enough to be emulsified, and ≥ 52 wt% solid content WPUs can be obtained. In comparison with water, small molecule diamine and diol, diamine with higher activity is preferred to water to complete the post chain extension reaction and significantly improves the thermodynamic and mechanical properties of WPUs, especially, when the degree of post chain extension was controlled at 70%. Among of diamine type post chain extenders, straight chain type post chain extender such as EDA and D-230 can improve the cold resistance (evaluated by glass transmutation temperature) and extensibility of WPU (broken elongation), and ring chain type post chain extender such as IPDA can enhance the mechanical properties and heat resistance of WPU, while crosslinking type post chain extenders involving DETA and KH602 can efficiently improve the heat resistance and anti-sticking of WPU.

Acknowledgements

The authors gratefully acknowledge the financial support from the National Key Research and Development Program of China (Project No: 2021YFC2101900), the Pioneers & Leader Research and Development Program of Zhejiang Province (Project No: 2022C01190), the Synthetic Leather and High-Performance Fibers Innovation Team (2020SCUNG122), and the Fundamental Research Funds for the Central Universities (YJ201940). The authors also appreciate Wang Zhonghui (College of Biomass Science and Engineering, Sichuan University) for her great help in FTIR, DSC and mechanical properties characterization.

Competing interest The authors have no relevant financial or non-financial interests to disclose.

Wang D, Li JY, Wang YK, et al. Water-based polyurethane adhesive films with enhanced bonding strength capable of in situ and high-efficient deposition on metal surface[J]. Chemical Engineering Journal, 2021, 431, 3:134055.
Bao L, Fan HJ, Chen Y, et al. Synthesis of 1,4-Butanediol di(3‐Diethylamino‐2‐Hydroxylpropyl Alcohol) Ether and Cationic Waterborne Polyurethane with High Solids Content[J]. Advances in Polymer Technology, 2016, 37, 3:21736.
V García-Pacios, Iwata Y, Colera M, et al. Influence of the solids content on the properties of waterborne polyurethane dispersions obtained with polycarbonate of hexanediol[J]. International Journal of Adhesion & Adhesives, 2011, 31(8):787–794.
Hou J, Ma Y, Zhang Z, et al. The Relationship between Solid Content and Particle Size Ratio of Waterborne Polyurethane[J]. Coatings, 2019, 9(6):401.
Chai CP, Ma YF, Li GP, et al. The preparation of high solid content waterborne polyurethane by special physical blending[J]. Progress in Organic Coatings, 2018, 115:79–85.
Hou J, Ma Y, Zhang Z, et al. The Relationship between Solid Content and Particle Size Ratio of Waterborne Polyurethane[J]. Coatings, 2019, 9(6):401.
Wang K, Peng Y, Tong RB, et al. The effects of isocyanate index on the properties of aliphatic waterborne polyurethaneureas[J]. Journal of Applied Polymer Science, 2010, 118(2): 920–927.
Jang J Y, Jhon Y K, Cheong I W, et al. Effect of process variables on molecular weight and mechanical properties of water-based polyurethane dispersion[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2002, 196(2–3): 135–143.
Xiao Li Wei, Fa Xing Zhang. Study on Polyurethane Dispersions with PES/PPG and High-Solid Content[J]. Advanced Materials Research, 2013, 864–867:588–591.
Su Yu-Miao, Wang Ting, Ding Yu-Lin, et al. Preparation Technology of Solvent-free Polyurethane: A Mini-Review[J]. Chinese J Struct Chem, 2020, 39(12):2057–2067.
Bernardini J, Cinelli P, Anguillesi I, et al. Flexible polyurethane foams green production employing lignin or oxypropylated lignin[J]. European Polymer Journal, 2015, 64:147–156.
Man, Dai, Ziyue, et al. Effects of soft segments on the waterproof of anionic waterborne polyurethane[J]. Colloid and polymer science, 2015, 293(3):879–881.
Kim H, Lee K J. Post-crosslinkable thermoplastic polyurethane for control of mechanical properties after processes[J], Polymer, 2021, 236:124350.
Qian L, Xiang-Mei W. Synthesis of a water polyurethane emulsion with high solid content, low viscosity via core-shell method[J]. Progress in Organic Coatings, 2019, 131:435–440.
Lei L, Zhong L, Lin XQ, et al. Synthesis and characterization of waterborne polyurethane dispersions with different chain extenders for potential application in waterborne ink[J]. Chemical Engineering Journal, 2014, 253, 1:518–525.
Wu G, Li JQ, Chai CP, et al. Synthesis and characterization of novel post-chain extension flame retardant waterborne polyurethane[J]. RSC Advances, 2015, 5:97710.
Peng X, Wang W, Ma N, et al. Research on the post-chain extension of aqueous polyurethane dispersions[J]. RSC Advances, 2016, 6, 43:36510–36515.
Nurdin N S, Saalah S, Lim A T, et al. Effect of DMPA Content on Colloidal Stability of Jatropha Oil-based waterborne Polyurethane Dispersion[J]. IOP Conference Series Materials Science and Engineering, 2020, 778:012107.
Sultan M, Atta S, Bhatti H N, et al. Synthesis, Characterization, and Application Studies of Polyurethane Acrylate Thermoset Coatings: Effect of Hard Segment[J]. Polymer Plastics Technology & Engineering, 2017:1–11.
Song S, Peng C, Gonzalez-Olivares M A, et al. Study on hydration layers near nanoscale silica dispersed in aqueous solutions through viscosity measurement[J]. Journal of Colloid & Interface Science, 2005, 287(1):114–120.
Ninham B W, Duignan T T, Parsons D F. Approaches to hydration, old and new: Insights through Hofmeister effects[J]. Current Opinion in Colloid & Interface Science, 2011, 16(6):612–617.
Schfer K, Nestler D, Trltzsch J, et al. Numerical Studies of the Viscosity of Reacting Polyurethane Foam with Experimental Validation[J]. Polymers, 2020, 12(1):105.
Lei L, Xia Z, Ou C, et al. Effects of crosslinking on adhesion behavior of waterborne polyurethane ink binder[J]. Progress in Organic Coatings, 2015, 88:155–163.
Lei, L, Zhong, et al. Synthesis and characterization of waterborne polyurethane dispersions with different chain extenders for potential application in waterborne ink[J]. Chemical Engineering Journal, 2014, 253:518–525.
Cl A, Kx B, Ys A, et al. Fire-safe, mechanically strong and tough thermoplastic Polyurethane/MXene nanocomposites with exceptional smoke suppression[J]. Materials Today Physics, 2022, 22:100607.
Fei C A, Yf A, Na H A, et al. Castor oil based high transparent UV cured silicone modified polyurethane acrylate coatings with outstanding tensile strength and good chemical resistance [J]. Progress in Organic Coatings, 2022,163:106624.

Download PDF

Journal Publication

published 13 Jun, 2023

Read the published version in Journal of Polymer Research →

Reviewers agreed at journal
27 Apr, 2023
Reviewers invited by journal
26 Apr, 2023
Editor invited by journal
21 Apr, 2023
Editor assigned by journal
19 Apr, 2023
First submitted to journal
18 Apr, 2023

You are reading this latest preprint version

A Novel Strategy for Preparation of Solvent-Free High-Solid Content Water-Based Polyurethane

Status:

Journal Publication

Version 1

Abstract

Figures

1. Introduction

2. Experimental

2.1 Materials

2.2 Preparation of WPU

2.3 Preparation of WPU film

2.4 Characterization

3. Results and discussion

3.1 FTIR spectrum of prepolymer and WPU

3.2 Effect of R values on solid content of WPU

3.3 Comparison of reaction activity of post chain extenders

3.4 Determination of amount of post chain extender

3.5 Effect of different post chain extenders on property of WPU emulsion

4. Conclusion

Declarations

Acknowledgements

References

Status:

Journal Publication

Version 1