A cast polyurethane damping material and preparation method thereof

Abstract

The application provides a cast polyurethane damping material and a preparation method thereof. The cast polyurethane damping material is prepared by mixing A component and B component uniformly, casting after defoaming and curing. The mass ratio of the A component to the B component is 1:0.9-1:1.1. The A component includes 100 parts by weight of polyol, 0.8-5 parts by weight of chain extender, 0.6-1.2 parts by weight of antioxidant and 0.3-0.9 parts by weight of catalyst, based on 100 parts by weight of polyol. The B component includes 58-76 parts by weight of polyether polyol and 24-42 parts by weight of 4,4'-diphenyl methane diisocyanate. The application uses 4,4'-diphenyl methane diisocyanate and a large amount of polyol with multiple functionalities as raw materials, and the cross-linking degree of the prepared polyurethane is very high, the damping performance is better, and the cast forming method is adopted, so that the processing is convenient and the product precision is high.

Description

Technical Field

[0001] The present invention relates to the field of polyurethane materials, and more particularly to a cast polyurethane damping material and a preparation method thereof. Background Art

[0002] Polyurethane is a block polymer composed of polyol soft segments and isocyanate, chain extender, and cross-linker hard segments. A large number of hydrogen bonds will form between polyurethane molecular chains. At the same time, due to the thermodynamic incompatibility between the soft and hard segments, a phase separation structure will spontaneously form. According to the processing method, polyurethane materials can be divided into three categories: cast polyurethane, thermoplastic polyurethane, and mixed polyurethane: Cast polyurethane is liquid before processing and molding. It is a liquid mixed casting processing method using oligomer polyols, isocyanates and small molecule chain extenders. It is solidified after chain extension and cross-linking reaction. It is the polyurethane elastomer with the largest output and the widest application range among polyurethanes; thermoplastic polyurethane is usually produced by a one-step process. The raw materials such as oligomer polyols, isocyanates and small molecule chain extenders are mixed and reacted in a twin-screw extruder. After drying and granulation, pellets are obtained. Its molecular chain structure is linear and can be re-molded after heating. The pellet molding process can be achieved by molding, extrusion and other processing methods; the first step in the synthesis of mixed polyurethane is to synthesize high viscosity, unsaturated, The mixed polyurethane raw rubber is stored stably, then mixed evenly with vulcanizers, accelerators and other additives in an open mixer or internal mixer, and then vulcanized and formed to obtain the mixed polyurethane. The processing process is the same as the mixing process of rubber. Overall, the performance of the mixed polyurethane is the worst.

[0003] Damping materials dissipate the mechanical vibrations of solids by converting them into heat. Polymer damping materials dissipate energy in the form of heat through friction between molecular chains, thereby achieving a damping effect. While commonly used polyurethanes contain a large number of hydrogen bonds, due to the crystallization of the soft segments, which are partially crystalline at room temperature, and the strong interaction between the hard segments, polyurethane generally has poor damping properties. Rubber's molecular chains are more flexible, generating more friction during movement, converting more energy into internal energy and exhibiting better damping properties. However, rubber materials are generally manufactured using a molding-before-vulcanization process. When preparing high-precision components with complex structures, defects such as bubbles often occur. Polyurethane casting can overcome the problems of bubbles and defects that can occur during rubber processing.

[0004] The crosslink density of a polymer significantly influences its damping properties. Damping performance is primarily determined by the strength of interactions between molecular chains. When the hard segment content of a polyurethane elastomer remains constant, its damping performance is primarily influenced by the interactions within and between the soft and hard segments. Polyurethane chains with linear molecular structures are densely packed due to hydrogen bonding, resulting in low interchain friction and poor damping performance. A high crosslink density reduces the molecular weight between crosslinks, resulting in a more complete polymer network and weaker soft segment mobility, leading to poorer damping performance. When the crosslink density is moderate, the interactions between polyurethane molecular chains are weak. During molecular chain movement, friction, and the continuous destruction and rearrangement of weak bonds (hydrogen bonds) between macromolecules, friction consumes more energy, leading to better damping performance. Therefore, for polyurethanes made from the same raw material, moderate crosslink density results in the best damping performance.

[0005] Therefore, it is necessary to design a polyurethane damping material that can be molded by casting, is easy to process, has high product precision, and has a suitable cross-linking density and better damping performance. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a cast polyurethane damping material and a preparation method thereof.

[0007] The present invention adopts a two-component system with 4,4'-diphenylmethane diisocyanate and polyol as the main raw materials. Diisocyanate with aromatic groups is used in the formula, and a large amount of trihydroxy polyoxypropylene ether is used at the same time to prepare a polyurethane damping material. The prepared polyurethane damping material has a high degree of cross-linking and good damping performance. It can be molded by casting, which is more convenient to mold, and the product has higher precision and more stable performance.

[0008] One of the purposes of the present invention is to provide a cast polyurethane damping material.

[0009] The cast polyurethane damping material is prepared from raw materials including the following components:

[0010] Component A and component B;

[0011] The A component includes a polyol, a chain extender, an antioxidant and a catalyst;

[0012] Based on 100 parts by weight of polyol,

[0013]

[0014] The raw materials of component A are mixed evenly to obtain the component A; preferably, the raw materials of component A are mixed at 90° C. to 110° C. and kept warm for 1 to 3 hours to obtain the component A;

[0015] The water content of component A is less than 0.03%;

[0016] Mixing at 90℃~110℃ can promote the dissolution of antioxidants. If the water content is high, water can be removed by heating and vacuuming.

[0017] The B component includes polyether polyol and 4,4'-diphenylmethane diisocyanate;

[0018] Based on 100 parts by weight of polyol,

[0019] 58 to 76 parts by weight of polyether polyol; preferably 66 to 75 parts by weight;

[0020] 24 to 42 parts by weight of 4,4'-diphenylmethane diisocyanate; preferably 25 to 34 parts by weight;

[0021] The water content of the polyether polyol is less than 0.03%;

[0022] After mixing the raw materials of component B, react at 80°C to 90°C for 1 to 3 hours to obtain the component B;

[0023] The mass ratio of component A to component B is 1:0.9 to 1:1.1.

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

[0025] The polyol is at least one of polyether polyol and polyester polyol; preferably a mixture of at least one of polyhexamethylene adipate, polycaprolactone diol, polytetrahydrofuran and trihydroxy polyoxypropylene ether, or trihydroxy polyoxypropylene ether; more preferably trihydroxy polyoxypropylene ether;

[0026] The mass ratio of trihydroxy polyoxypropylene ether to the total mass ratio of polyol is not less than 50%, preferably not less than 80%.

[0027] In a preferred embodiment of the present invention,

[0028] The chain extender is at least one of ethylenediamine, ethylene glycol, butanediamine, butanediol, hexamethylenediamine, resorcinol diamine, and isophorone diamine; more preferably, it is butanediamine, butanediol, and hexamethylenediamine.

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

[0030] The antioxidant is a hindered phenol antioxidant; preferably antioxidant 1010.

[0031] In a preferred embodiment of the present invention,

[0032] The catalyst is one of dibutyltin dilaurate, stannous octoate, and dibutyltin diacetate; more preferably dibutyltin dilaurate.

[0033] In a preferred embodiment of the present invention,

[0034] The polyether polyol is at least one of trihydroxy polyoxypropylene ether, polyethylene glycol, polypropylene glycol, and polytetrahydrofuran; preferably a mixture of at least one of polyethylene glycol, polypropylene glycol, and polytetrahydrofuran and trihydroxy polyoxypropylene ether; more preferably a mixture of trihydroxy polyoxypropylene ether, polyethylene glycol, and polytetrahydrofuran;

[0035] In component B, the mass of trihydroxy polyoxypropylene ether does not exceed 74% of the total mass of the polyether polyol; preferably, it accounts for 54% to 74% of the total mass of the polyether polyol.

[0036] The objectives of the present invention can be achieved without adding trihydroxy polyoxypropylene ether to component B. However, adding trihydroxy polyoxypropylene ether to component B and adopting a two-step process of prepolymerization followed by chain extension can make the polyurethane molecular structure more regular and the performance better. In theory, the more trihydroxy polyoxypropylene ether in component B, the better the performance. However, a very high content can lead to severe gelation, which is not conducive to continuous production. Therefore, the content of trihydroxy polyoxypropylene ether in component B needs to be limited.

[0037] A second object of the present invention is to provide a method for preparing a cast polyurethane damping material, comprising:

[0038] The component A and the component B are mixed uniformly according to the mass ratio, degassed, poured, and cured to obtain the cast polyurethane damping material.

[0039] The present invention can specifically adopt the following technical solutions:

[0040] Components A and B are prepared according to the above ratios, mixed uniformly at a mass ratio of 1:0.9 to 1:1.1 at room temperature under mechanical stirring, and then degassed at low pressure to obtain a mixture of components A and B. The mixture of components A and B is poured into a mold, cured, and cooled after curing. The resulting solid material is peeled from the mold to obtain a polyurethane damping material.

[0041] Preferably, component A and component B are stirred at 500-1000 rpm for 10-15 minutes to be uniformly mixed, and degassed at low pressure to obtain a mixture of component A and component B.

[0042] The mixture of component A and component B is preferably poured into a mold and cured at 100-120°C; more preferably 100-110°C;

[0043] The curing time is 1.5 to 4 hours. After curing, the material is cooled and the obtained solid material is peeled off from the mold to obtain a polyurethane damping material.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The present invention adopts a large amount of multifunctional polyols to prepare a polyurethane damping material with a high degree of cross-linking and better damping performance; the two-component method overcomes the problem of premature cross-linking caused by the use of a large amount of multifunctional polyols and can be stored for a long time.

[0046] 2. The present invention uses 4,4'-diphenylmethane diisocyanate with an aromatic group as a raw material, which has greater interaction between chain segments, greater loss, and better damping performance.

[0047] 3. The polyurethane damping material of the present invention is in an amorphous liquid state when not solidified. It can be prepared into materials with different shapes according to actual needs to meet the needs of various situations. At the same time, the liquid can fully fill the mold cavity, making molding more convenient and the product precision higher.

[0048] 4. The polyurethane damping material of the present invention adopts a method of mixing the main material component A and component B. The production of the main material and the molding of the polyurethane damping material can be carried out in stages and discontinuously. For example, the polyurethane damping material can undergo a curing reaction at the construction site, which reduces costs and improves production efficiency.

[0049] 5. The curing rate and curing temperature of the polyurethane damping material of the present invention are controllable. After component A and component B are mixed uniformly according to the proportion, the curing rate can be adjusted by adjusting the curing temperature and the amount of catalyst.

[0050] 6. The polyurethane damping material of the present invention has certain bonding properties with metal materials and can be matched with metal materials as needed to prepare a composite material with high damping performance.

[0051] 7. The polyurethane damping material of the present invention can be added with different additives as auxiliary materials according to the material's actual working conditions, such as anti-aging properties, fluidity, and temperature resistance, to meet different requirements.

[0052] 8. After the polyurethane damping material casting product of the present invention is cured, the elongation at break of the material can exceed 500%, and can be applied to non-structural components. DETAILED DESCRIPTION

[0053] The present invention will be described in detail below with reference to specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0054] The raw materials used in the examples and comparative examples are all conventional commercially available raw materials.

[0055] GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber;

[0056] Dynamic mechanical analysis (DMA) test conditions: frequency 1 Hz, strain 0.1%, temperature change rate 3 ° C min -1 , the test temperature range is -100 ~ 80 ℃ tensile mode.

[0057] Example 1

[0058] Raw material composition of component A:

[0059]

[0060] Raw material composition of component B:

[0061] 20 parts by weight of polytetrahydrofuran;

[0062] 55 parts by weight of trihydroxy polyoxypropylene ether;

[0063] 25 parts by weight of 4,4'-diphenylmethane diisocyanate;

[0064] The raw materials of component A are weighed by mass, added into the reactor and stirred evenly, and the water content in the mixture is controlled to be less than 0.03% to obtain component A, which is then packaged and stored.

[0065] The raw materials of component B are weighed by mass and added into the reactor. The water content of polytetrahydrofuran and trihydroxy polyoxypropylene ether used in component B is less than 0.03%. The raw materials are mixed evenly at 90° C. and reacted for 2 hours to obtain component B, which is then packaged and stored.

[0066] Component A and component B were stirred at 600 rpm for 10 minutes in a mass ratio of A / B = 1 / 1 to be uniformly mixed, and degassed at low pressure to obtain a mixture of component A and component B.

[0067] The mixture of component A and component B was poured into a mold and cured at 100° C. for 4 hours. After curing, the mixture was cooled and the obtained solid material was peeled off from the mold to obtain a polyurethane damping material.

[0068] Example 2

[0069] Raw material composition of component A:

[0070]

[0071] Raw material composition of component B:

[0072] 33 parts by weight of polytetrahydrofuran;

[0073] 39.4 parts by weight of trihydroxy polyoxypropylene ether;

[0074] 27.6 parts by weight of 4,4'-diphenylmethane diisocyanate;

[0075] The raw materials of component A are weighed by mass, added into the reactor and stirred evenly, and the water content in the mixture is controlled to be less than 0.03% to obtain component A, which is then packaged and stored.

[0076] The raw materials of component B are weighed by mass and added into the reactor. The water content of polytetrahydrofuran and trihydroxy polyoxypropylene ether used in component B is less than 0.03%. The raw materials are mixed evenly at 80° C. and reacted for 3 hours to obtain component B, which is then packaged and stored.

[0077] Component A and component B were stirred at 600 rpm for 10 minutes in a mass ratio of A / B = 1 / 1 to be uniformly mixed, and degassed at low pressure to obtain a mixture of component A and component B.

[0078] The mixture of component A and component B was poured into a mold and cured at 120° C. for 1.5 hours. After curing, the mixture was cooled and the obtained solid material was peeled off from the mold to obtain a polyurethane damping material.

[0079] Example 3

[0080] Raw material composition of component A:

[0081]

[0082] Raw material composition of component B:

[0083] 25 parts by weight of polytetrahydrofuran;

[0084] 41.6 parts by weight of trihydroxy polyoxypropylene ether;

[0085] 33.4 parts by weight of 4,4'-diphenylmethane diisocyanate;

[0086] The raw materials of component A are weighed by mass, added into the reactor and stirred evenly, and the water content in the mixture is controlled to be less than 0.03% to obtain component A, which is then packaged and stored.

[0087] The raw materials of the B component were weighed and added into the reactor, the water content of the polytetrahydrofuran and the trihydroxy polyoxypropylene ether used in the B component was less than 0.03%, and the mixture was uniformly mixed and reacted at 80°C for 1 hour to obtain the B component, which was stored in a sealed package.

[0088] The A component and the B component were uniformly mixed at an A / B mass ratio of 1 / 1.1 under stirring at 600 rpm for 10 min, and then degassed under low pressure to obtain a mixture of the A component and the B component.

[0089] The mixture of the A component and the B component was poured into a mold and cured at 110°C for 2 hours, and then cooled after curing, and the obtained solid material was peeled off from the mold to obtain a polyurethane damping material.

[0090] Example 4

[0091] The raw material composition of the A component was as follows:

[0092]

[0093]

[0094] The raw material composition of the B component was as follows:

[0095] Polytetrahydrofuran 35 parts by weight;

[0096] Polypropylene glycol 25 parts by weight;

[0097] 4,4'-diphenyl methane diisocyanate 40 parts by weight;

[0098] The raw materials of the A component were weighed and added into the reactor, and the water content in the mixture was controlled to be less than 0.03% to obtain the A component, which was stored in a sealed package.

[0099] The raw materials of the B component were weighed and added into the reactor, the water content of the polytetrahydrofuran and the polypropylene glycol used in the B component was less than 0.03%, and the mixture was uniformly mixed and reacted at 85°C for 1 hour to obtain the B component, which was stored in a sealed package.

[0100] The A component and the B component were uniformly mixed at an A / B mass ratio of 1 / 1.05 under stirring at 600 rpm for 10 min, and then degassed under low pressure to obtain a mixture of the A component and the B component.

[0101] The mixture of the A component and the B component was poured into a mold and cured at 110°C for 3 hours, and then cooled after curing, and the obtained solid material was peeled off from the mold to obtain a polyurethane damping material.

[0102] Comparative Example 1

[0103] The raw material composition of the A component was as follows:

[0104]

[0105] Raw material composition of component B:

[0106] 55 parts by weight of polytetrahydrofuran;

[0107] 45 parts by weight of 4,4'-diphenylmethane diisocyanate;

[0108] The raw materials of component A are weighed by mass, added into the reactor and stirred evenly, and the water content in the mixture is controlled to be less than 0.03% to obtain component A, which is then packaged and stored.

[0109] The raw materials of component B are weighed by mass and added into the reactor. The water content of the polytetrahydrofuran used in component B is less than 0.03%. The raw materials are mixed evenly at 90° C. and reacted for 2 hours to obtain component B, which is then packaged and stored.

[0110] Component A and component B were stirred at 600 rpm for 10 minutes in a mass ratio of A / B = 1 / 1 to be uniformly mixed, and degassed at low pressure to obtain a mixture of component A and component B.

[0111] The mixture of component A and component B was poured into a mold and cured at 100° C. for 2 hours. After curing, the mixture was cooled and the obtained solid material was peeled off from the mold to obtain a polyurethane damping material.

[0112] Comparative Example 2

[0113] Comparative Example 1 uses a TPU sample of German BASF, brand C85AHPM, and puts its pellets into a preheated 190°C mold, hot-presses at 190°C for 25 minutes, takes it out and cold-presses it for 5 minutes, and peels it from the mold to obtain a sample of Comparative Example 1.

[0114] The mechanical properties of the cast polyurethane damping materials obtained in Examples 1 to 4 were tested, and the results are shown in Table 1.

[0115] Table 1 Elongation at break of Examples 1 to 4

[0116] Elongation at break (%) Example 1 788±31 Example 2 650±22 Example 3 583±19 Example 4 612±18

[0117] The elongation at break is mainly determined by the crosslinking density and hard segment content in the system. The elongation at break of Examples 1 to 4 is all above 500%, which indicates that the compositions have certain mechanical properties and can be applied to non-structural components.

[0118] The cast polyurethane damping materials obtained in Examples 1 to 4 were subjected to dynamic mechanical property tests under the test conditions of 1 Hz, 0.1% deformation, and 3° C. / min heating rate. The results are shown in Table 2.

[0119] Table 2 Dynamic mechanical properties of Examples 1 to 4

[0120] Loss peak (℃) 0℃ loss factor Dissipation factor at 20℃ Example 1 -45.5 0.31 0.32 Example 2 -39.2 0.26 0.24 Example 3 -39.7 0.24 0.22 Example 4 -43.5 0.18 0.16 Comparative Example 1 -39.1 0.12 0.08 Comparative Example 2 -35.2 0.08 0.06

[0121] The loss peak in the DMA test is the glass transition temperature of the tested material. As shown in Table 2, the glass transition temperatures of Examples 1-4 are significantly higher than those of Comparative Examples 1 and 2. This is because Examples 1-4 contain a higher content of trihydroxy polyoxypropylene ether and the highest content of random structures, resulting in a lower glass transition temperature. The use of 4,4'-diphenylmethane diisocyanate as the hard segment and polyether and a small amount of polyester as the soft segment, with a low hard segment content, also reduces the glass transition temperature of the cast polyurethane damping material, maintaining a certain degree of flexibility under low-temperature conditions.

[0122] Compared with Example 4, Examples 1 to 3 have higher loss factors at different temperatures and better damping performance. Examples 1 to 3 use a large amount of trihydroxy polyoxypropylene ether. The trifunctional trihydroxy polyoxypropylene ether acts as a crosslinking point in the polyurethane damping material. Compared with linear polyurethane, it has a higher crosslinking density, stronger friction between molecular chains, and better damping performance. At the same time, Examples 1 to 3 have a lower hard segment content, lower interaction between soft segments and hard segments, and stronger mobility of the soft segment molecular chain. The molecular chain has greater friction and loss during movement, and better damping performance. In Example 4, the amount of trihydroxy polyoxypropylene ether is relatively low, and the molecular chain has a linear structure. Compared with the polymer network with a higher crosslinking density, the friction between the molecular chains is relatively weak, the loss capacity is lower, and the damping performance is lower.

[0123] Examples 1-4 exhibit significantly higher loss factors at 0°C and 20°C than Comparative Examples 1-2, demonstrating superior damping performance. Comparative Example 1, due to the relatively low amount of trihydroxy polyoxypropylene ether components and the high hard segment content, exhibits poor polyurethane molecular chain mobility and less interchain friction compared to the examples, resulting in poor damping performance. Comparative Example 2, a commercially available thermoplastic polyurethane formed by hot pressing, features a regular polyurethane molecular chain structure, strong interchain interactions, poor molecular chain mobility, minimal interchain friction, and very low loss performance, resulting in poor damping performance.

[0124] Comparison between the examples and the comparative examples further illustrates that in the damping material of the present invention, only when the amount of trihydroxy polyoxypropylene ether reaches a certain amount and the polyurethane has a suitable network structure, the polyurethane will have better damping performance.

[0125] The cast polyurethane damping materials prepared in Examples 1 to 4 have a high degree of cross-linking and good damping performance. They can be molded by a casting method, which is more convenient to mold, and the products have higher precision and more stable performance.

Claims

1. A cast polyurethane damping material, characterized in that: The cast polyurethane damping material is prepared from raw materials including the following components: Component A and component B; The A component includes a polyol, a chain extender, an antioxidant and a catalyst; The polyol is a mixture of at least one of poly(hexamethylene adipate), poly(caprolactone diol), and polytetrahydrofuran and trihydroxy polyoxypropylene ether, or trihydroxy polyoxypropylene ether; Based on 100 parts by weight of polyol, The mass ratio of trihydroxy polyoxypropylene ether to the total mass of polyol is not less than 50%; The raw materials of component A are mixed evenly to obtain the component A; The water content of component A is less than 0.03%; The B component includes polyether polyol and 4,4'-diphenylmethane diisocyanate; The polyether polyol is at least one of trihydroxy polyoxypropylene ether, polyethylene glycol, polypropylene glycol, and polytetrahydrofuran; Based on 100 parts by weight of polyol, 58-76 parts by weight of polyether polyol; 24 to 42 parts by weight of 4,4'-diphenylmethane diisocyanate; The water content of the polyether polyol is less than 0.03%; After mixing the raw materials of component B, react at 80°C to 90°C for 1 to 3 hours to obtain the component B; The mass ratio of component A to component B is 1:0.9 to 1:1.

1.

2. The cast polyurethane damping material according to claim 1, wherein: The component A is calculated based on 100 parts by weight of the polyol. The B component is calculated based on 100 parts by weight of the polyol. 66-75 parts by weight of polyether polyol; 25-34 parts by weight of 4,4'-diphenylmethane diisocyanate 3. The cast polyurethane damping material according to claim 1, wherein: The ratio of the mass of trihydroxy polyoxypropylene ether to the total mass of the polyol is not less than 80%.

4. The cast polyurethane damping material according to claim 1, wherein: The chain extender is at least one of ethylenediamine, ethylene glycol, butanediamine, butanediol, hexamethylenediamine, resorcinol diamine, and isophorone diamine.

5. The cast polyurethane damping material according to claim 1, wherein: The antioxidant is a hindered phenol antioxidant.

6. The cast polyurethane damping material according to claim 1, wherein: The catalyst is one of dibutyltin dilaurate, stannous octoate and dibutyltin diacetate.

7. The cast polyurethane damping material according to claim 1, wherein: The polyether polyol is a mixture of at least one of polyethylene glycol, polypropylene glycol, and polytetrahydrofuran and trihydroxy polyoxypropylene ether.

8. The cast polyurethane damping material according to claim 7, wherein: The mass of the trihydroxy polyoxypropylene ether does not exceed 74% of the total mass of the polyether polyol.

9. The cast polyurethane damping material according to claim 8, wherein: The mass of the trihydroxy polyoxypropylene ether is 54% to 74% of the total mass of the polyether polyol.

10. A method for preparing a cast polyurethane damping material according to any one of claims 1 to 9, characterized in that The method comprises: The component A and the component B are mixed uniformly according to the mass ratio, degassed, poured, and cured to obtain the cast polyurethane damping material.

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