A pure polyurea elastomer, its preparation method and use

Abstract

This invention discloses a pure polyurea elastomer, its preparation method, and its applications. In the field of polyurea elastomers, the pure polyurea elastomer of this invention comprises structural units derived from a polyurea prepolymer and structural units derived from a chain extender. The polyurea prepolymer is prepared by reacting raw materials including isocyanate and diamine. This invention uses amino-terminated polyethers to synthesize the polyurea prepolymer, crosslinks it with difunctional isocyanate, and extends the chain with an amino chain extender. The product after the reaction of isocyanate and chain extender is still a urea group, thus synthesizing a pure polyurea elastomer with excellent heat resistance and physical properties. This invention provides a pure polyurea elastomer without urethane groups, exhibiting superior heat resistance, wear resistance, and other physical properties compared to traditional polyurethane elastomers.

Description

Technical Field

[0001] This invention relates to the field of polyurea elastomers, and more specifically, to a pure polyurea elastomer, its preparation method, and its applications. Background Technology

[0002] Currently, engineering vehicles mainly come in two forms: wheeled and tracked. Different vehicle operation methods are required for different terrains. Wheeled vehicles are suitable for relatively flat and hard ground. Tracked vehicles are suitable for softer and more challenging terrain. Tracked wheels are a special type of walking device that combines the characteristics of tires and tracks. They mainly solve the problem of poor vehicle mobility in complex and harsh terrains such as mudflats, swamps, deserts, fields, snow, and gravel. Tracked wheels have the advantages of a larger ground contact area and lower ground pressure, and significantly improve traction, mobility, smoothness, stability, and traction.

[0003] The earliest tracked vehicle road wheels were made entirely of steel without rubber rims. While this method was simple and had a long service life, the lack of rubber rims caused significant resonance, potentially damaging internal vehicle components. Therefore, high-speed tracked vehicle road wheels are constructed by coating a certain thickness of rubber onto a metal rim, serving functions such as load bearing, support, transmission, and cushioning, making them a crucial component of tracked vehicles. Tracked vehicle road wheels operate under harsh conditions, requiring them to withstand high loads, cyclic stress and strain, and complex operating environments. Their performance directly impacts the tracked vehicle's mobility, speed, and durability. The rubber coating on tracked vehicle road wheels must possess excellent resistance to high and low temperatures, weathering, ozone aging, flexural fatigue, and excellent adhesion between the metal wheel body and the outer tire material.

[0004] Currently, tracked vehicles primarily use rubber and cast polyurethane elastomers (CPUE) for tire coating. CPUE materials possess excellent mechanical properties, with tensile strength generally 2-3 times that of natural rubber and load-bearing capacity 6 times that of rubber. Low-speed solid tires widely utilize polyurethane instead of rubber. However, due to the relatively low heat resistance of polyurethane elastomers, thermal damage may occur under high-speed, heavy-load conditions. Therefore, reducing internal heat generation and improving the heat resistance of polyurethane elastomers are key research directions for heavy-duty road wheel polyurethane elastomers.

[0005] Polyurea elastomers are elastomeric materials produced by the reaction of isocyanate components and amino compound components. The isocyanate component is usually a prepolymer or semi-prepolymer, and the amino compound is usually a small-molecule terminal amino compound, such as MOCA (4,4'-methylenedi(2-chloroaniline)), DETDA (diethyltoluenediamine), DMTDA (dimethylthiotoluenediamine), etc., or a large-molecule terminal amino polyether, terminal amino polytetrahydrofuran, etc.

[0006] Isocyanate-containing prepolymers are synthesized by reacting isocyanates with hydroxyl-terminated polyethers / polyesters via heating. Depending on the reactivity of the isocyanate and hydroxyl groups, as well as the reaction temperature and time, aromatic isocyanates generally exhibit higher reactivity, while aliphatic isocyanates have relatively lower reactivity. Adding an appropriate catalyst during the synthesis of aliphatic isocyanate prepolymers can shorten the reaction time. The prepolymer structure synthesized through formulation design is as follows:

[0007] NCO-R-NCO+HO-R′-OH→NCO-R-NH-CO-OR′-O-CO-NH-R-NCO

[0008] Reaction formula for synthesizing elastomers from prepolymers and terminal amino compounds:

[0009] NCO-R-NH-CO-OR′-O-CO-NH-R-NCO+NH2-R"-NH2→

[0010] ~R"-NH-CO-NH-R-NH-CO-OR′-O-CO-NH-R-NH-CO-NH-R"~

[0011] As can be seen from the above structural formula, the elastomer contains two hard segment groups: urea (-NH-CO-NH-) and urethane (-NH-CO-O-). The heat resistance of polyurethane / polyurea elastomer is mainly related to the soft and hard segment structure of polyurethane, and depends on the thermal decomposition temperature of the groups in the elastomer. The thermal decomposition temperature of urea is 260℃, that of urethane is 241℃, that of urethane is 146℃, and that of biuret is 144℃. Uramate groups are mainly formed during the prepolymer synthesis stage and during the chain extension reaction of the prepolymer with alcohol chain extenders. Urea groups are mainly generated when amine chain extenders are used. Urea and biuret groups are mainly formed during the high-temperature crosslinking and curing stage. Therefore, to synthesize polyurethane / urea elastomers with high heat resistance and high performance, it is necessary to reduce the generation of biuret and urethane groups, and at the same time, try to use isocyanates and terminal amino polymers when synthesizing prepolymers.

[0012] Currently, the synthesis of prepolymers all uses the reaction of isocyanate and hydroxyl groups. This reaction condition is mature, and performance improvement is mainly achieved by adjusting the isocyanate structure and polyol structure. Extensive literature and experimental results have demonstrated that polyester-type polyurethanes have better heat resistance than polyether-type polyurethanes, and PTMEG (polytetrahydrofuran diol) has significantly better performance than PEG (polyethylene glycol) and PPG (polypropylene glycol). If amino-terminated polymers are used to synthesize prepolymers, there are two technical problems. First, the amino groups are extremely reactive, and the mixture of amino-terminated polyethers and isocyanates will quickly gel and solidify. The other problem is that amino-terminated polyethers are synthesized through the ammoniation reaction of polyethers and are mainly used as raw materials for the production of sprayed polyurea elastomers. However, there are no such raw materials on the market for amino-terminated polyester polyols with better performance. Summary of the Invention

[0013] To address the problems existing in the prior art, this invention provides a pure polyurea elastomer, its preparation method, and its applications. This invention uses amino-terminated polyethers to synthesize polyurea prepolymers, crosslinks them with difunctional isocyanates, and extends the chain using amino chain extenders. The product after the reaction of isocyanate and chain extenders remains urea groups, thus synthesizing a pure polyurea elastomer with excellent heat resistance and physical properties. This invention provides a pure polyurea elastomer without urethane groups, exhibiting superior heat resistance, wear resistance, and other physical properties compared to traditional polyurethane elastomers.

[0014] One of the objectives of this invention is to provide a pure polyurea elastomer.

[0015] The pure polyurea elastomer of the present invention comprises structural units derived from polyurea prepolymers and structural units derived from chain extenders.

[0016] The polyurea prepolymer is prepared by reacting raw materials including isocyanate and diamine.

[0017] In a preferred embodiment of the present invention:

[0018] The chain extender is an amino chain extender; and / or,

[0019] The isocyanate is a difunctional isocyanate.

[0020] In a preferred embodiment of the present invention, the pure polyurea elastomer comprises the following vulcanized components:

[0021] Polyurea prepolymer, chain extender, and optionally crosslinking agent; preferably,

[0022] The polyurea prepolymer is prepared from raw materials comprising the following components:

[0023] Isocyanates, diamines, and solvents.

[0024] In a preferred embodiment of the present invention:

[0025] The crosslinking agent is 0-5 wt% of the weight of the polyurea prepolymer, preferably 1-1.5 wt%; and / or,

[0026] The molar ratio (f-value) of the chain extender to the total molar ratio of the polyurea prepolymer and optionally the crosslinking agent is (0.5–1):1, preferably (0.90–1):1; and / or,

[0027] The molar ratio (R value) of the isocyanate to the diamine is (1.2–2):1, preferably (1.5–2):1; and / or,

[0028] The solvent is 20-100 wt% of the total weight of isocyanate and diamine, preferably 35-60 wt%.

[0029] In a preferred embodiment of the present invention:

[0030] The isocyanate group content of the polyurea prepolymer is 0-6.5 wt%, preferably 4.5-5.5 wt%; and / or,

[0031] The chain extender is an amino chain extender, preferably at least one of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4,4'-methylene-bis(3-chloro-2,6-diethylaniline) (MCDEA), 4,4'-bis(sec-butylamino)-diphenylmethane, diethyltoluenediamine (DETDA), and 2,4-diamino-3,5-dimethylthiotoluene, more preferably at least one of 3,3'-dichloro-4,4'-diaminodiphenylmethane and 4,4'-methylene-bis(3-chloro-2,6-diethylaniline); and / or,

[0032] The isocyanate is a difunctional isocyanate, preferably at least one of trans-1,4-cyclohexyl diisocyanate (CHDI), isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and terephthalic diisocyanate (PPDI); and / or,

[0033] The diamine is an amino-terminated polyether, preferably at least one of the following: amino-terminated polyethylene glycol-polytetrahydrofuran diol copolymer (PEG-PTMG-PEG) (such as Jeffamine THF100, etc.) and polytetrahydrofuran diamine (such as Jeffamine THF170, Jeffamine THF140, etc.); and / or,

[0034] The crosslinking agent can be any commonly used crosslinking agent in the art, such as... N3300, Desmoud N3400 N3200, etc.; and / or,

[0035] The solvent is a low-boiling-point solvent that does not contain hydroxyl and / or amino groups, preferably at least one of ethyl acetate, acetone, and dichloromethane.

[0036] A second objective of this invention is to provide a method for preparing pure polyurea elastomer as described in one objective of this invention.

[0037] The method for preparing pure polyurea elastomer according to the present invention includes:

[0038] The pure polyurea elastomer is prepared by vulcanizing raw materials including a polyurea prepolymer, a chain extender, and optionally a crosslinking agent; preferably,

[0039] The polyurea prepolymer is prepared by polymerizing raw materials including isocyanate, diamine and solvent.

[0040] In a preferred embodiment of the present invention, the method includes:

[0041] (1) Dissolve the isocyanate in part of the solvent to obtain an isocyanate solution, and dissolve the diamine in the remaining solvent to obtain a diamine solution;

[0042] (2) Under stirring, the diamine solution is slowly added dropwise to the isocyanate solution to carry out the polymerization reaction. After the reaction, the solvent is removed by vacuum to obtain the polyurea prepolymer. After the polyurea prepolymer is synthesized, the NCO% content is determined by titration. The degree of reaction completion is determined based on the deviation between the measured NCO% content and the theoretical NCO% content.

[0043] (3) The polyurea prepolymer and optionally the crosslinking agent are heated and then mixed evenly with the molten chain extender to carry out a vulcanization reaction to obtain the pure polyurea elastomer. Specifically, the following steps can be taken: the polyurea prepolymer and optionally the crosslinking agent are mixed evenly and heated to 70-100°C. Heating can reduce the viscosity and mix evenly with the molten chain extender, avoiding the problem of instantaneous solid precipitation due to excessive temperature difference during mixing; the chain extender is heated to a liquid state; the two components are mixed evenly and poured into a mold, the air bubbles are removed using a vacuum oven, a pressure plate is covered, and the temperature is maintained at 80-120°C on a flat vulcanizing apparatus for 30-60 minutes; the mold is removed and kept at 100°C in an oven for 16-24 hours.

[0044] In a preferred embodiment of the present invention:

[0045] In step (1):

[0046] The solvent is 20-100 wt% of the weight of the isocyanate, preferably 35-60 wt%.

[0047] In a preferred embodiment of the present invention:

[0048] In step (2):

[0049] The stirring speed is 220 r / min or higher, preferably 300-400 r / min; and / or,

[0050] The slow dripping rate is below 8 ml / min, preferably 1-8 ml / min; and / or,

[0051] The polymerization reaction temperature is 20–40°C, preferably 25–30°C, and / or the reaction time is 1–5 h, preferably 2–3 h; and / or,

[0052] In step (3):

[0053] The heating temperature is 70–100°C, preferably 70–80°C; and / or,

[0054] The temperature of the molten chain extender can be determined based on its melting point and viscosity, such as heating MOCA to approximately 120°C; and / or,

[0055] The vulcanization temperature of the vulcanization reaction is 80–120°C, preferably 90–110°C, and / or the vulcanization time is 30–60 min, preferably 40–50 min.

[0056] A third objective of this invention is to provide an application of pure polyurea elastomer as described in one objective of this invention or pure polyurea elastomer prepared by the method described in another objective of this invention in the field of high heat resistance and / or high mechanical properties materials, preferably in the field of rubber coating for heavy-duty wheels.

[0057] This invention utilizes amino-terminated polyethers to synthesize polyurea prepolymers, which are then crosslinked with difunctional isocyanates and extended using amino chain extenders. The product after the reaction of isocyanate and chain extender remains a urea group, resulting in the synthesis of a pure polyurea elastomer with excellent heat resistance and physical properties. This invention provides a pure polyurea elastomer without urethane groups, exhibiting superior heat resistance, wear resistance, and other physical properties compared to traditional polyurethane elastomers.

[0058] The prepolymer synthesis method of this invention first dilutes the isocyanate with a solvent and then titrates it into a diamine solution. The purpose is to slow the reaction rate and synthesize a prepolymer containing urea groups. After prepolymer synthesis, the solvent is removed, ultimately yielding a solvent-free prepolymer. The prepolymer synthesized by this invention contains urea bonds, which have higher bond energies and higher thermal decomposition temperatures. Polyurea elastomers synthesized using this prepolymer exhibit better physical properties and heat resistance. This method reduces the biuret structure produced by the reaction of excess isocyanate with urea, avoiding the problem of poor heat resistance in elastomers due to the low thermal decomposition temperature of biuret. Detailed Implementation

[0059] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0060] In the embodiments of the present invention, unless otherwise specified, all raw materials used are commercially available products well known to those skilled in the art.

[0061]

Example 1

[0062] Prepolymer synthesis: 111.01 g of isophorone diisocyanate (IPDI) and 55.5 g of ethyl acetate were added to a three-necked flask and stirred at 400 r / min. A mixture of 250 g of amino-terminated polyethylene glycol and polytetrahydrofuran glycol copolymer THF100 and 125 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 2 ml / min. The temperature was slowly raised to 35℃ and maintained at 35±2℃ using a water bath. Ice was added to lower the temperature if it became too high. After 2.5 h of reaction, the NCO% content was determined to be 3.88±0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while simultaneously evacuating to remove the solvent. After 3 h of evacuation, the NCO% content was determined again. When the content was within the range of 5.82±0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45℃. The mixture was then discharged, sealed, and stored for later use.

[0063] Elastomer preparation: Heat 100g of prepolymer to 70℃. Heat 10.8g of MOCA to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 24 hours.

[0064] The molar ratio R of IPDI to THF100 is 2:1.

[0065] The amount of crosslinking agent added is 0 wt% of the prepolymer weight.

[0066] The molar ratio f of MOCA to the molar ratio of the prepolymer is 0.95:1.

[0067]

Example 2

[0068] Prepolymer synthesis: 131.17 g of dicyclohexylmethane-4,4'-diisocyanate (HMDI) and 65.6 g of ethyl acetate were added to a three-necked flask and stirred at 400 r / min. A mixture of 250 g of amino-terminated polyethylene glycol and polytetrahydrofuran glycol copolymer THF100 and 125 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 2 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. After reacting for 2.5 h, the NCO% content was determined to be 3.67 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while simultaneously evacuating to remove the solvent. After evacuating for 3 h, the NCO% content was determined again. When the content was within the range of 5.51 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0069] Elastomer preparation: Heat 100g of prepolymer to 70℃. Heat 16.6g of MOCA to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 24 hours.

[0070] The molar ratio R of HMDI to THF100 is 2:1.

[0071] The amount of crosslinking agent added is 0 wt% of the prepolymer weight.

[0072] The molar ratio f of MOCA to the molar ratio of the prepolymer is 0.95:1.

[0073]

Example 3

[0074] Prepolymer synthesis: 83.09 g of trans-1,4-cyclohexyl diisocyanate (CHDI) and 41.95 g of ethyl acetate were added to a three-necked flask and stirred at 400 r / min. A mixture of 250 g of amino-terminated polyethylene glycol and polytetrahydrofuran glycol copolymer THF100 and 125 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 2 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. After reacting for 2.5 h, the NCO% content was determined to be 4.2 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while simultaneously evacuating to remove the solvent. After evacuating for 3 h, the NCO% content was determined again. When the content was within the range of 6.30 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0075] Elastomer preparation: Heat 100g of prepolymer to 70℃. Heat 19.0g of MOCA to 110℃ until it reaches a liquid state. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 24 hours.

[0076] The molar ratio R of CHDI to THF100 is 2:1.

[0077] The amount of crosslinking agent added is 0 wt% of the prepolymer weight.

[0078] The molar ratio f of MOCA to the molar ratio of the prepolymer is 0.95:1.

[0079]

Example 4

[0080] Prepolymer synthesis: 83.09 g of trans-1,4-cyclohexyl diisocyanate (CHDI) and 41.95 g of ethyl acetate were added to a three-necked flask and stirred at 200 r / min. A mixture of 350 g of polytetrahydrofuran diamine (THF140) and 50 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 8 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. After reacting for 2.5 h, the NCO% content was determined to be 4.04 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while simultaneously evacuating to remove the solvent. After evacuating for 3 h, the NCO% content was determined again. When the content was within the range of 4.85 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0081] Elastomer preparation: Heat 100g of prepolymer to 70℃. Heat 14.7g of MOCA to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 30 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 16 hours.

[0082] The molar ratio R of CHDI to THF140 is 2:1.

[0083] The amount of crosslinking agent added is 0 wt% of the prepolymer weight.

[0084] The molar ratio f of MOCA to the molar ratio of the prepolymer is 0.95:1.

[0085]

Example 5

[0086] Prepolymer synthesis: 83.09 g of trans-1,4-cyclohexyl diisocyanate (CHDI) and 41.95 g of ethyl acetate were added to a three-necked flask and stirred at 200 r / min. A mixture of 350 g of polytetrahydrofuran diamine (THF140) and 50 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 8 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. After reacting for 2.5 h, the NCO% content was determined to be 4.04 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while simultaneously evacuating to remove the solvent. After evacuating for 3 h, the NCO% content was determined again. When the content was within the range of 4.85 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0087] Elastomer preparation: Mix 100g of prepolymer and crosslinking agent and heat to 70℃. Heat 15.67g of MOC A to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 30 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 16 hours.

[0088] The molar ratio R of CHDI to THF140 is 2:1.

[0089] Crosslinking agent is The amount of N3300 added is 0.5 wt% of the prepolymer weight.

[0090] The molar amount of MOCA and the prepolymer and The ratio f of the total molar amount of N3300 is 1:1.

[0091]

Example 6

[0092] Prepolymer synthesis: 83.09 g of trans-1,4-cyclohexyl diisocyanate (CHDI) and 41.95 g of ethyl acetate were added to a three-necked flask and stirred at 200 r / min. A mixture of 350 g of polytetrahydrofuran diamine (THF140) and 50 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a rate of 8 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. Ice was added to lower the temperature if it became too high. After 2.5 h of reaction, the NCO% content was determined to be 4.04 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating, while a vacuum was applied to remove the solvent. After 3 h of vacuuming, the NCO% content was determined again. When the content was within the range of 4.85 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0093] Elastomer preparation: Mix 100g of prepolymer and crosslinking agent and heat to 70℃. Heat 17.60g of MOC A to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 30 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 16 hours.

[0094] The molar ratio R of CHDI to THF140 is 2:1.

[0095] Crosslinking agent is The amount of N3300 added is 4.5 wt% of the prepolymer weight.

[0096] The molar amount of MOCA and the prepolymer and The ratio f of the total molar amount of N3300 is 1:1.

[0097]

Example 7

[0098] Prepolymer synthesis: 83.09 g of trans-1,4-cyclohexyl diisocyanate (CHDI) and 41.95 g of ethyl acetate were added to a three-necked flask and stirred at 200 r / min. A mixture of 350 g of polytetrahydrofuran diamine (THF140) and 50 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 8 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. After reacting for 2.5 h, the NCO% content was determined to be 4.04 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while simultaneously evacuating to remove the solvent. After evacuating for 3 h, the NCO% content was determined again. When the content was within the range of 4.85 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0099] Elastomer preparation: Mix 100g of prepolymer and crosslinking agent and heat to 70℃. Heat 17.07g of MOC A to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 120℃ for 30 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 16 hours.

[0100] The molar ratio R of CHDI to THF140 is 2:1.

[0101] Crosslinking agent is The amount of N3400 added is 3 wt% of the prepolymer weight.

[0102] The molar amount of MOCA and the prepolymer and The ratio f of the total molar amount of N3400 is 1:1.

[0103]

Example 8

[0104] Prepolymer synthesis: 83.09 g of trans-1,4-cyclohexyl diisocyanate (CHDI) and 41.95 g of ethyl acetate were added to a three-necked flask and stirred at 200 r / min. A mixture of 350 g of polytetrahydrofuran diamine (THF140) and 50 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 8 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. After reacting for 2.5 h, the NCO% content was determined to be 4.04 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while simultaneously evacuating to remove the solvent. After evacuating for 3 h, the NCO% content was determined again. When the content was within the range of 4.85 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0105] Elastomer preparation: Mix 100g of prepolymer and crosslinking agent and heat to 70℃. Heat 10.91g of diethyltoluene diamine (DETDA) to 110℃ until it reaches a liquid state. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 80℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 16 hours.

[0106] The molar ratio R of CHDI to THF140 is 2:1.

[0107] Crosslinking agent is The amount of N3300 added is 2 wt% of the prepolymer weight.

[0108] The molar amount of DETDA is related to the prepolymer and The ratio f of the total molar amount of N3300 is 1:1.

[0109]

Example 9

[0110] Prepolymer synthesis: 83.09 g of trans-1,4-cyclohexyl diisocyanate (CHDI) and 41.95 g of acetone were added to a three-necked flask and stirred at 200 r / min. A mixture of 350 g of polytetrahydrofuran diamine (THF140) and 50 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 8 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. The reaction was carried out for 2.5 h, and the NCO% content was determined to be 4.04 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while a vacuum was applied to remove the solvent. After 3 h of vacuuming, the NCO% content was determined again. When the content was within the range of 4.85 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0111] Elastomer preparation: 100g of prepolymer and crosslinking agent were mixed and heated to 70℃. 23.28g of 4,4'-methylene-bis(3-chloro-2,6-diethylaniline) (MCDEA) was heated to 110℃ until it reached a liquid state. The two components were mixed evenly and poured into a mold. Air bubbles were removed using a vacuum oven. The mold was covered with a pressure plate and vulcanized at 80℃ for 60 minutes using a flat vulcanizing apparatus. The mold was then removed and cured at 100℃ for 16 hours.

[0112] The molar ratio R of CHDI to THF140 is 2:1.

[0113] Crosslinking agent is The amount of N3300 added is 2 wt% of the prepolymer weight.

[0114] The molar amount of MCDEA and the prepolymer and The ratio f of the total molar amount of N3300 is 1:1.

[0115]

Example 10

[0116] Prepolymer synthesis: 83.09 g of trans-1,4-cyclohexyl diisocyanate (CHDI) and 41.95 g of acetone were added to a three-necked flask and stirred at 400 r / min. A mixture of 333 g of amino-terminated polyethylene glycol and polytetrahydrofuran glycol copolymer THF100 and 166.5 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 2 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. The reaction was carried out for 2.5 h, and the NCO% content was determined to be 2.24 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while a vacuum was applied to remove the solvent. After 3 h of vacuuming, the NCO% content was determined again. When the content was within the range of 3.36 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0117] Elastomer preparation: Heat 100g of prepolymer to 70℃. Heat 10.2g of MOCA to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 24 hours.

[0118] The molar ratio R of CHDI to THF100 is 1.5:1.

[0119] The amount of crosslinking agent added is 0 wt% of the prepolymer weight.

[0120] The molar ratio f of MOCA to the molar ratio of the prepolymer is 0.95:1.

[0121]

Example 11

[0122] Prepolymer synthesis: 83.09 g of trans-1,4-cyclohexyl diisocyanate (CHDI) and 41.95 g of acetone were added to a three-necked flask and stirred at 400 r / min. A mixture of 286 g of amino-terminated polyethylene glycol and polytetrahydrofuran glycol copolymer THF100 and 143 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 2 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. The reaction was carried out for 2.5 h, and the NCO% content was determined to be 3.25 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while a vacuum was applied to remove the solvent. After 3 h of vacuuming, the NCO% content was determined again. When the content was within the range of 4.88 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0123] Elastomer preparation: Heat 100g of prepolymer to 70℃. Heat 14.7g of MOCA to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 24 hours.

[0124] The molar ratio R of CHDI to THF100 is 1.75:1.

[0125] The amount of crosslinking agent added is 0 wt% of the prepolymer weight.

[0126] The molar ratio f of MOCA to the molar ratio of the prepolymer is 0.95:1.

[0127]

Example 12

[0128] Prepolymer synthesis: 83.09 g of cyclohexane-1,4-diisocyanate (CHDI) and 41.95 g of acetone were added to a three-necked flask and stirred at 400 r / min. A mixture of 286 g of amino-terminated polyethylene glycol and polytetrahydrofuran glycol copolymer THF100 and 143.5 g of ethyl acetate was slowly added dropwise using a constant pressure funnel at a titration rate of 2 ml / min. The temperature was slowly raised to 35 °C and maintained at 35 ± 2 °C using a water bath. If the temperature was too high, ice was added to cool it down. The reaction was carried out for 2.5 h, and the NCO% content was determined to be 3.25 ± 0.2 wt%. The three-necked flask was then placed in a heating mantle for stirring and heating while a vacuum was applied to remove the solvent. After 3 h of vacuuming, the NCO% content was determined again. When the content was within the range of 4.88 ± 0.2 wt%, the vacuum pump was stopped, and the temperature was lowered to below 45 °C. The mixture was then discharged, sealed, and stored for later use.

[0129] Elastomer preparation: Mix 100g of prepolymer and crosslinking agent and heat to 70℃. Heat 16.24g of MOC A to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 24 hours.

[0130] The molar ratio R of CHDI to THF100 is 1.75:1.

[0131] Crosslinking agent The amount of N3300 added is 1.5 wt% of the prepolymer weight.

[0132] The molar amount of MOCA and the prepolymer and The ratio f of the total molar amount of N3300 is 1:1.

[0133] Comparative Example 1

[0134] Prepolymer synthesis: 250g of polytetrahydrofuran diol (PTMG1000) was added to a three-necked flask and stirred and heated to 65°C. 111.01g of isophorone diisocyanate (IPDI) was added and the temperature was slowly raised to 85°C and maintained at 85±2°C for 5 hours. The NCO% content was measured to be 5.82±0.2wt%. The mixture was then cooled to below 45°C, discharged, sealed and stored for later use.

[0135] Elastomer preparation: Heat 100g of prepolymer to 70℃. Heat 17.6g of MOCA to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 24 hours.

[0136] The molar ratio R of IPDI to PTMG1000 is 2:1.

[0137] The amount of crosslinking agent added is 0 wt% of the prepolymer weight.

[0138] The molar ratio f of MOCA to the molar ratio of the prepolymer is 0.95:1.

[0139] Comparative Example 2

[0140] Prepolymer synthesis: 250g of polytetrahydrofuran diol (PTMG1000) was added to a three-necked flask and stirred and heated to 65°C. 131.17g of dicyclohexylmethane-4,4'-diisocyanate (HMDI) was added and the temperature was slowly raised to 85°C and maintained at 85±2°C for 5 hours. The NCO% content was determined to be 5.51±0.2wt%. The mixture was then cooled to below 45°C, discharged, sealed, and stored for later use.

[0141] Elastomer preparation: Heat 100g of prepolymer to 70℃. Heat 16.6g of MOCA to 110℃ until completely liquid. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 24 hours.

[0142] The molar ratio R of HMDI to polyether PTMG1000 is 2:1.

[0143] The amount of crosslinking agent added is 0 wt% of the prepolymer weight.

[0144] The molar ratio f of MOCA to the molar ratio of the prepolymer is 0.95:1.

[0145] Comparative Example 3

[0146] Prepolymer synthesis: 250g of polytetrahydrofuran diol (PTMG1000) was added to a three-necked flask and stirred and heated to 65°C. 83.09g of trans-1,4-cyclohexyl diisocyanate (CHDI) was added and the temperature was slowly raised to 85°C and maintained at 85±2°C for 5 hours. The NCO% content was measured to be 6.3±0.2wt%. The mixture was then cooled to below 45°C, discharged, sealed, and stored for later use.

[0147] Elastomer preparation: Heat 100g of prepolymer to 70℃. Heat 19.0g of MOCA to 110℃ until it reaches a liquid state. Mix the two components thoroughly and pour into a mold. Remove air bubbles using a vacuum oven. Cover with a pressure plate and vulcanize at 100℃ for 60 minutes using a flat vulcanizing apparatus. Remove the mold and cure at 100℃ for 24 hours.

[0148] The molar ratio R of CHDI to polyether PTMG1000 is 2:1.

[0149] The amount of crosslinking agent added is 0 wt% of the prepolymer weight.

[0150] The molar ratio f of MOCA to the molar ratio of the prepolymer is 0.95:1.

[0151] The elastomers prepared in the above embodiments and comparative examples were subjected to tensile performance tests according to the method of GB16777-2008. The test results are shown in Table 1 below:

[0152] Table 1

[0153]

[0154] The tensile property test results of Examples 1-3 and Comparative Examples 1-3 show that the prepolymers synthesized using PEG-PTMG-PEG diamine in the examples and PTMG diol in the comparative examples are both 2:1 in terms of the isocyanate to diol (ammonia) molar ratio R. MOCA was used as the chain extender in both examples and the comparative examples, and the chain extension coefficient f was 0.95:1 in both examples. The polyurea elastomers with pure polyurea structural hard segments in Examples 1-3 have better physical properties and heat resistance than the polyurethane elastomers containing urethane bonds in Comparative Examples 1-3.

[0155] Example 4 uses the same isocyanate CHDI as in Example 3, but uses THF140, which has a larger molecular weight than THF100. The pure polyurea elastomer prepared has a lower content of hard segments (chain extender, urea bond, urethane bond), lower tensile strength, higher elongation, and slightly lower heat resistance than in Example 3.

[0156] Examples 5, 6, and 7 are based on Example 4 with the addition of a crosslinking agent. The addition of the crosslinking agent helps to improve tensile strength and heat resistance, while the corresponding elongation will be slightly reduced.

[0157] Examples 10, 11, and 12 used the same raw materials as Example 3, but the R values ​​were adjusted to 1.5, 1.75, and 1.75, respectively, and a crosslinking agent was added. The results showed that a lower R value resulted in a lower hard segment content in the polyurea elastomer, as well as lower tensile strength and heat resistance; however, adding a crosslinking agent improved tensile strength and heat resistance.

Claims

1. A pure polyurea elastomer, characterized in that... The structural formula of the pure polyurea elastomer includes structural units derived from polyurea prepolymers and structural units derived from chain extenders; The polyurea prepolymer is prepared by reacting raw materials including isocyanate and diamine.

2. The pure polyurea elastomer according to claim 1, characterized in that: The chain extender is an amino chain extender; and / or, The isocyanate is a difunctional isocyanate.

3. The pure polyurea elastomer according to claim 1 or 2, characterized in that... The pure polyurea elastomer comprises the following vulcanized components: Polyurea prepolymer, chain extender, and optionally crosslinking agent; preferably, The polyurea prepolymer is prepared from raw materials comprising the following components: Isocyanates, diamines, and solvents.

4. The pure polyurea elastomer according to claim 3, characterized in that: The crosslinking agent is 0-5 wt% of the weight of the polyurea prepolymer, preferably 1-1.5 wt%; and / or, The molar ratio of the chain extender to the total molar ratio of the polyurea prepolymer and optionally the crosslinking agent is (0.5–1):1, preferably (0.9–1):1; and / or, The molar ratio of the isocyanate to the diamine is (1.2–2):1, preferably (1.5–2):1; and / or, The solvent is 20-100 wt% of the total weight of isocyanate and diamine, preferably 35-60 wt%.

5. The pure polyurea elastomer according to claim 3, characterized in that: The isocyanate group content of the polyurea prepolymer is 0-6.5 wt%, preferably 4.5-5.5 wt%; and / or, The chain extender is an amino chain extender, preferably at least one selected from 3,3'-dichloro-4,4'-diaminodiphenylmethane, 4,4'-methylene-bis(3-chloro-2,6-diethylaniline), 4,4'-bis(sec-butylamino)-diphenylmethane, diethyltoluenediamine, and 2,4-diamino-3,5-dimethylthiotoluene, more preferably at least one selected from 3,3'-dichloro-4,4'-diaminodiphenylmethane and 4,4'-methylene-bis(3-chloro-2,6-diethylaniline); and / or, The isocyanate is a difunctional isocyanate, preferably at least one of trans-1,4-cyclohexyl diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, hexamethylene diisocyanate, and terephthalic diisocyanate; and / or, The diamine is an amino-terminated polyether, preferably at least one of an amino-terminated polyethylene glycol-polytetrahydrofuran glycol copolymer or an amino-terminated polytetrahydrofuran; and / or The solvent is at least one of ethyl acetate, acetone, and dichloromethane.

6. A method for preparing a pure polyurea elastomer as described in any one of claims 1-5, characterized in that... The method includes: The pure polyurea elastomer is prepared by vulcanizing raw materials including a polyurea prepolymer, a chain extender, and optionally a crosslinking agent; preferably, The polyurea prepolymer is prepared by polymerizing raw materials including isocyanate, diamine and solvent.

7. The method according to claim 6, characterized in that... The method includes: (1) Dissolve the isocyanate in part of the solvent to obtain an isocyanate solution, and dissolve the diamine in the remaining solvent to obtain a diamine solution; (2) Under stirring, the diamine solution is slowly added dropwise to the isocyanate solution to carry out the polymerization reaction. After the reaction, the solvent is removed by vacuum to obtain the polyurea prepolymer. (3) The polyurea prepolymer and optionally the crosslinking agent are heated and then mixed evenly with the molten chain extender to carry out a vulcanization reaction to obtain the pure polyurea elastomer.

8. The method according to claim 7, characterized in that: In step (1): The solvent is 20-100 wt% of the weight of the isocyanate, preferably 35-60 wt%.

9. The method according to claim 7, characterized in that: In step (2): The stirring speed is 220 r / min or higher, preferably 300-400 r / min; and / or, The slow dripping rate is below 8 ml / min, preferably 1-8 ml / min; and / or, The polymerization reaction temperature is 20–40°C, preferably 25–30°C, and / or the reaction time is 1–5 h, preferably 2–3 h; and / or, In step (3): The heating temperature is 70–100°C, preferably 70–80°C; and / or, The vulcanization temperature of the vulcanization reaction is 80–120°C, preferably 90–110°C, and / or the vulcanization time is 30–60 min, preferably 40–50 min.

10. The application of a pure polyurea elastomer as described in any one of claims 1-5 or a pure polyurea elastomer prepared by the method as described in any one of claims 6-9 in the field of high heat resistance and / or high mechanical properties materials, preferably in the field of rubber coating for heavy-duty wheels.

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