A preparation method of high wear-resistant polyurethane elastomer

Abstract

The present invention relates to the technical field of polyurethane synthesis, and specifically to a method for preparing a highly wear-resistant polyurethane elastomer, comprising the following steps: placing porous particles in an oily liquid of dibutyltin dilaurate, heating and stirring, filtering, dispersing the filtered porous particles, cooling and storing; stirring a hydroxyl-terminated polyurethane prepolymer, a diisocyanate, a chain extender, porous particles, a stabilizer, carbon black, and a coupling agent at low temperature, uniformly pouring the mixture into a mold, subjecting the mold to microwave treatment, placing the mold in a constant temperature chamber for reaction, and demolding the resulting product. The present invention solidifies the dibutyltin dilaurate catalyst in the porous particles, heats the porous particles during microwave treatment, causing them to melt and diffuse into the raw material mixture, and catalytic polymerization occurs under heating in the constant temperature chamber. The resulting polyurethane product exhibits significantly improved properties such as wear resistance, high temperature resistance, and impact resistance.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane synthesis, and in particular to a method for preparing a highly wear-resistant polyurethane elastomer. Background Art

[0002] As a high-performance elastic material, polyurethane (PU) has demonstrated broad application potential in multiple fields. Its unique molecular structure endows PU with excellent mechanical properties such as wear resistance, impact resistance, and elastic recovery, as well as resistance to corrosion, oil stains, and high temperatures. Depending on the specific raw materials, the degree of crystallinity of PU ranges from 0 to 13%. Increasing the degree of crystallinity can significantly improve the mechanical and resistance properties of PU. Besides the regularity of the PU molecular chain itself, factors that determine the degree of PU crystallinity include the control of factors during the polymerization process, such as reaction temperature, reaction time, and the type and amount of catalyst. Precise control of these factors can promote the orderly arrangement of PU molecular chains during polymerization, thereby improving the degree of crystallinity.

[0003] Chinese patent application CN108102340A discloses a highly crystalline thermoplastic polyurethane elastomer composition and its preparation method. The polyurethane elastomer and a layered inorganic compound are mixed, melt blended, and then extruded. The patent application states that the layered inorganic compound can induce TPU crystallization, increasing the crystallinity by more than 10%. The patent application describes a method for increasing crystallinity by inducing polyurethane recrystallization with an inorganic compound. This method involves physical post-processing of the finished polyurethane product. While this method significantly increases the crystallinity of the TPU, the added layered inorganic compound is prone to agglomeration and other uneven dispersion, resulting in uneven crystallization of the TPU.

[0004] Chinese patent CN114479742A discloses a bio-based, highly crystalline, water-based polyurethane adhesive for footwear and its preparation process. This patent utilizes a special process sequence to produce a highly crystalline, high-viscosity polyurethane adhesive. The patent application's technical solution for increasing polyurethane crystallinity involves a stepwise catalytic increase in molecular weight, thereby enhancing crystallinity and bond strength. In this patent application, as the molecular weight increases, the viscosity of the reaction system gradually increases. This results in uneven molecular weight increases, leading to variations in crystallinity and uneven performance across the polyurethane adhesive.

[0005] Although the above two existing patent applications can improve the crystallinity of polyurethane products, and the corresponding polyurethane products also demonstrate the expected performance after the crystallinity is improved, the technical solutions of the above two existing patent applications have uneven crystallization while improving the crystallinity of polyurethane, which reduces the stability of the performance of the polyurethane finished product. Summary of the Invention

[0006] In order to solve the problem that the existing process of increasing the crystallinity of polyurethane leads to a decrease in the performance stability of polyurethane products, the present invention provides a method for preparing a highly wear-resistant polyurethane elastomer, comprising the following steps:

[0007] 1. Place the porous particles in an oily liquid of dibutyltin dilaurate, heat and stir, and then filter. Disperse the filtered porous particles and cool and store them.

[0008] 2. Weigh the following components in parts by weight: 50-100 parts of hydroxyl-terminated polyurethane prepolymer, 20-40 parts of diisocyanate, 30-50 parts of chain extender, 15-40 parts of porous particles from step 1, 5-15 parts of stabilizer, 1-5 parts of carbon black, and 1-3 parts of coupling agent. Stir well at low temperature and pour into a mold.

[0009] 3. The mold is microwave-treated and then placed in a constant temperature box for reaction;

[0010] 4. After the reaction is completed, demoulding is carried out to obtain a highly wear-resistant polyurethane elastomer.

[0011] According to the present invention, a dibutyltin dilaurate catalyst is solidified in porous particles, and then the porous particles and a raw material mixture of polyurethane are mixed at low temperature. The mixture is poured into a mold and then subjected to microwave treatment. The porous particles are heated under the microwave to melt the dibutyltin dilaurate catalyst and diffuse into the raw material mixture. The hydroxyl-terminated polyurethane prepolymer, diisocyanate and a chain extender are polymerized by catalysis under heating in a constant temperature box. The polymerization rate decreases outward from a single porous particle as a center. The polymerization rate is low, and molecular chain segments have sufficient time to stack, thereby increasing crystallinity. Meanwhile, the porous particles serve as crystal nuclei to form large polyurethane grains with the porous particles as cores. The large grains are simultaneously formed and uniformly dispersed in the entire polyurethane system, so that the prepared polyurethane finished product has greatly improved properties such as wear resistance, high temperature resistance and impact resistance.

[0012] Specifically, the porous particles are selected from one or more of porous silicon carbide particles, porous titanium dioxide particles, or porous aluminum oxide particles. The porous particles serve as catalyst carriers before polymerization and as seed crystals during polymerization. They also enhance the wear, corrosion, and impact resistance of the finished polyurethane, making them a core component of the present invention's method.

[0013] In the preparation method of the present invention, since the polyurethane raw material is first mixed and cast before polymerization in a static state, it is necessary to have a certain viscosity and stability to ensure uniform distribution of the porous particles throughout the process. The polyurethane raw material of the present invention uses a hydroxyl-terminated polyurethane prepolymer with a certain viscosity. The mass ratio of polyester polyol to isocyanate is controlled to be 2:1 to obtain a hydroxyl-terminated polyurethane prepolymer with moderate viscosity. Then, appropriate amounts of stabilizer and coupling agent are added to ensure uniform dispersion of the porous particles without agglomeration.

[0014] Specifically, the diisocyanate is selected from one of MDI, TDI or HDI; the chain extender is selected from one of 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, diethanolamine, neopentanediamine, trimethylhexanediamine or methyldiethanolamine; the stabilizer is selected from tristearate or vinyl bisstearamide; the coupling agent is selected from one of KH550, KH560, KH570, KH580 or KH590.

[0015] The present invention ensures uniform dispersion of the porous particles by selecting polyurethane materials. It also ensures that the dibutyltin dilaurate in the porous particles melts and disperses into the raw material mixture of the polyurethane during polymerization. The melting point of dibutyltin dilaurate is 22-24°C. Therefore, the porous particles filled with dibutyltin dilaurate in step 1 are stored at a temperature of 0-10°C. At relatively low temperatures, the dibutyltin dilaurate can stably solidify in the porous particles. The stirring temperature in step 2 is 10-20°C. A slightly higher stirring temperature allows a small amount of dibutyltin dilaurate to be dispersed in the mixture, making the polymerization reaction more uniform. The constant temperature in step 3 is 75-90°C. At this temperature, the reaction rate of the polyurethane catalyzed by dibutyltin dilaurate is moderate, preventing uneven reaction due to an overly rapid polymerization reaction. DETAILED DESCRIPTION

[0016] The present invention is described below with reference to examples, which are only used to explain the present invention and are not used to limit the scope of the present invention. Example 1

[0017] A method for preparing a highly wear-resistant polyurethane elastomer comprises the following steps:

[0018] 1. Place the porous silicon carbide particles in the oily liquid of dibutyltin dilaurate, stir at 40°C and filter, disperse the filtered porous silicon carbide particles and cool to 5°C for storage;

[0019] 2. Weigh the following components in parts by weight: 80 parts of hydroxyl-terminated polyurethane prepolymer, 30 parts of MDI, 40 parts of diethanolamine, 25 parts of porous silicon carbide particles obtained in step 1, 10 parts of tristearate, 3 parts of carbon black, and 2 parts of KH550. Stir well at 15°C and pour into a mold.

[0020] 3. After the mold is microwave-treated for 1.5 hours, it is placed in a constant temperature box at 80°C for reaction for 3 hours and demolded to obtain the product. Example 2

[0021] A method for preparing a highly wear-resistant polyurethane elastomer comprises the following steps:

[0022] 1. Place the porous titanium dioxide particles in the oily liquid of dibutyltin dilaurate, stir at 40°C and filter, disperse the filtered porous titanium dioxide particles and cool to 0°C for storage;

[0023] 2. Weigh the following components in parts by weight: 100 parts of hydroxyl-terminated polyurethane prepolymer, 20 parts of TDI, 30 parts of 1,5-pentanediamine, 15 parts of porous titanium dioxide particles obtained in step 1, 5 parts of vinyl bisstearamide, 1 part of carbon black, and 1 part of KH570. Stir well at 20°C and pour into a mold.

[0024] 3. After the mold is microwave-treated for 2 hours, it is placed in a constant temperature box at 90°C for 2 hours and demolded. Example 3

[0025] A method for preparing a highly wear-resistant polyurethane elastomer comprises the following steps:

[0026] 1. Place the porous alumina particles in the oily liquid of dibutyltin dilaurate, stir at 40°C and filter, disperse the filtered porous alumina particles and cool to 10°C for storage;

[0027] 2. Weigh the following components in parts by weight: 50 parts of hydroxyl-terminated polyurethane prepolymer, 40 parts of HDI, 50 parts of trimethylhexamethylenediamine, 40 parts of porous alumina particles obtained in step 1, 15 parts of tristearate, 5 parts of carbon black, and 3 parts of KH580. Stir well at 10°C and pour into a mold.

[0028] 3. After microwave treatment for 1 hour, the mold was placed in a 75°C constant temperature box for 2.5 hours and demolded.

[0029] Comparative Examples 1 to 3 are respectively the same as Examples 1 to 3 in which the porous particles are not added, dibutyltin dilaurate and other components are mixed and cast, and then directly heated and catalyzed to prepare polyurethane elastomers without microwave treatment.

[0030] Table 1 shows the properties of the polyurethane elastomers obtained in Examples 1-3 and Comparative Examples 1-3, respectively. As can be seen from the test data in Table 1, the highly wear-resistant polyurethane elastomers obtained in Examples 1-3 exhibit significantly improved crystallinity and fracture strength compared to the polyurethane elastomers prepared by direct catalytic polymerization in Comparative Examples 1-3, due to the addition of porous particles and the pre-encapsulation of the catalyst within the porous particles. The inorganic porous particles and polyurethane crystals exhibit good resistance to black marker ink infiltration, resulting in significantly improved stain resistance in the highly wear-resistant polyurethane elastomers obtained in Examples 1-3.

[0031] Table 1. Properties of polyurethane elastomers obtained in Examples 1 to 3 and Comparative Examples 1 to 3

[0032]

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a highly wear-resistant polyurethane elastomer, characterized in that: The following steps are involved:

1. Place the porous particles in an oily liquid of dibutyltin dilaurate, heat and stir, then filter. Disperse the filtered porous particles and cool to 0-10°C for storage. The porous particles are selected from a combination of one or more of porous silicon carbide particles, porous titanium dioxide particles, or porous aluminum oxide particles; 2. Weigh the following components in parts by weight: 50-100 parts of hydroxyl-terminated polyurethane prepolymer, 20-40 parts of diisocyanate, 30-50 parts of chain extender, 15-40 parts of porous particles from step 1, 5-15 parts of stabilizer, 1-5 parts of carbon black, and 1-3 parts of coupling agent. Stir well at 10-20°C and pour into a mold. The hydroxyl-terminated polyurethane prepolymer controls the mass ratio of polyester polyol to isocyanate to be 2:1; 3. After microwave treatment, the mold is placed in a constant temperature box at 75-90°C for reaction; 4. After the reaction is completed, demoulding is carried out to obtain the highly wear-resistant polyurethane elastomer.

2. The preparation method according to claim 1, characterized in that In step 2, the diisocyanate is selected from one of MDI, TDI or HDI.

3. The preparation method according to claim 1, characterized in that In step 2, the chain extender is selected from one or more combinations of 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, diethanolamine, neopentyldiamine, trimethylhexanediamine or methyldiethanolamine.

4. The preparation method according to claim 1, characterized in that In step 2, the stabilizer is selected from glyceryl tristearate or vinyl bisstearamide.

5. The preparation method according to claim 1, characterized in that In step 2, the coupling agent is selected from one of KH550, KH560, KH570, KH580 or KH590.

Images