Full-mold-opening self-leveling polyurethane composition and application thereof

Abstract

The invention relates to the technical field of polyurethane microporous elastomers, and provides a full-mold-opening self-leveling polyurethane composition and application thereof. The full-mold-opening self-leveling polyurethane composition provided by the invention not only can be subjected to full-mold-opening injection molding, but also has relatively high raw material flowability, compatibility and reaction uniformity, and the prepared polyurethane material can have good size regularity and performance uniformity at the same time. The composition is prepared from an isocyanate reactive component and an isocyanate prepolymer, the isocyanate reactive component comprises polyether polyol I, polyether polyol II, polyether polyol III, a foaming agent, a compatibilizer and a surfactant; the average molecular weight of the polyether polyol I is 2000 to 6000 g / mol; the polyether polyol II is polytetrahydrofuran polyol, and the average molecular weight of the polyether polyol II is 1000 to 3000g / mol; and the average molecular weight of the polyether polyol III is 200 to 1000 g / mol.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane microporous elastomer technology, specifically relating to fully open-mold self-leveling polyurethane compositions and their applications. Background Technology

[0002] Polyurethane materials come in a variety of forms, mainly including foam plastics, elastomers, synthetic leather, adhesives, waterproofing materials, and coatings, and are widely used in home furnishings, textiles and apparel, transportation, construction, printing, sports, and medical fields. Polyurethane elastomers, in particular, possess properties such as corrosion resistance, high elasticity, shock resistance, oxygen resistance, ozone resistance, oil resistance, strong chemical resistance, and abrasion resistance. Compared to common metal materials, polyurethane elastomers are lighter; compared to rubber, they exhibit superior wear resistance, corrosion resistance, and ozone resistance, and are less prone to damage and more durable. These excellent properties have led to their widespread application in many fields, with a wide variety of types, offering numerous advantages compared to other materials.

[0003] Depending on the processing technology, polyurethane elastomers can be divided into thermoplastic, compounded, and cast types. Cast polyurethane elastomers (CPU) use polyols, isocyanates, and chain extenders as raw materials, all of which are viscous liquids, hence their nickname "liquid rubber." They are prepared using a liquid molding casting method, which is simple and convenient, easily automated and continuously produced. Furthermore, they can be cast into molds of different structures to obtain products with different shapes, smooth surfaces, and uniform internal structures.

[0004] Railway transportation plays a significant role in promoting national economic development and is currently the main mode of passenger and freight transport in my country. High-speed railways, with their advantages of speed, convenience, and comfort, have become the preferred mode of transportation for modern people. Under-sleeper shock-absorbing elastic pads are an important component of high-speed railway tracks, primarily serving to buffer the impact of the high-speed rails on the track slab. However, during prolonged use, the pads may shift from the concrete sleepers. To increase the friction between the pads and the concrete, other materials need to be laminated onto the upper layer of the pads, with one half embedded within the pad and the other half increasing friction with the sleepers. This necessitates that the pads be cast in open molds, maintaining the same dimensional stability as those cast in closed molds, to avoid dimensional defects during production.

[0005] However, due to the poor compatibility and inconsistent reactivity of the various raw material components of polyurethane elastomers, and the large amount of heat released during the reaction process which accelerates the reaction, the non-uniformity of the reaction is amplified. It is difficult to ensure the smoothness of the surface and the stability of the dimensions in the state of free foaming in open mold. Therefore, how to develop a fully open mold self-leveling high regularity polyurethane composition is one of the technical problems that urgently need to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a fully open-mold self-leveling polyurethane composition and its applications. The fully open-mold self-leveling polyurethane composition provided by this invention not only allows for fully open-mold injection molding but also possesses high raw material flowability, compatibility, and reaction uniformity. The resulting polyurethane material exhibits good dimensional regularity and performance uniformity, while also possessing advantages such as high stiffness and high elongation. Using the polyurethane composition of this invention to prepare polyurethane materials through open-mold casting helps overcome problems such as complex processes and large dimensional deviations in products encountered when polyurethane materials are combined with other materials.

[0007] To achieve its objective, the present invention provides the following technical solution:

[0008] This invention provides a fully open-mold self-leveling polyurethane composition, the composition comprising an isocyanate reactive component and an isocyanate prepolymer;

[0009] Based on the total mass of the isocyanate reactive component, the isocyanate reactive component is a mixture comprising the following raw materials in the following mass percentages:

[0010] Polyether polyol I, 58%–70%;

[0011] Polyether polyol II, 6%–16%;

[0012] Polyether polyol III, 1%–7%;

[0013] Foaming agent, 0.1%–0.4%;

[0014] Compatibilizer, 0.1%–0.6%;

[0015] Surfactant, 0.3-1.2%;

[0016] The polyether polyol I has an average molecular weight of 2000-6000 g / mol, and based on the total mass of ethylene oxide and propylene oxide as 100%, the ethylene oxide content is 10-20 wt% and the propylene oxide content is 80-90 wt%.

[0017] Polyether polyol II is a polytetrahydrofuran polyol with an average molecular weight of 1000-3000 g / mol;

[0018] The average molecular weight of polyether polyol III is 200-1000 g / mol. Based on the total mass of ethylene oxide and propylene oxide as 100%, the ethylene oxide content is 90-100 wt% and the propylene oxide content is 0-10 wt%.

[0019] The compatibilizer is one or more of polysiloxane, modified polysiloxane, and fluorinated acrylate copolymer;

[0020] The surfactant is a polyether-modified organosilicon surfactant.

[0021] Preferably, the surfactant comprises surfactant I and surfactant II; based on the total mass of the isocyanate reactive component, the mass percentages of surfactant I and surfactant II are 0.1% to 0.6%, respectively.

[0022] The surfactant I is a polyether-modified organosilicon surfactant derived from the block copolymerization of polysiloxane and olefin oxide;

[0023] Surfactant II is a polyether-modified organosilicon surfactant derived from the graft copolymerization of polysiloxane and olefin oxide.

[0024] Preferably, surfactant I has an AB-type linear block structure, and surfactant II has a multi-branched chain structure.

[0025] Preferably, the compatibilizer is an organosilicon-modified polysiloxane;

[0026] And / or, the average molecular weight of the polyether polyol I is 4000-6000 g / mol;

[0027] And / or, the average molecular weight of the polyether polyol II is 1500-3000 g / mol;

[0028] And / or, the average molecular weight of the polyether polyol III is 250-600 g / mol;

[0029] And / or, the average functionality of the polyether polyol I, the polyether polyol II, and the polyether polyol III is independently 2-4;

[0030] And / or, in the polyether polyol III, the ethylene oxide content is 95-100 wt%, based on the total mass of ethylene oxide and propylene oxide as 100%.

[0031] Preferably, the average functionality of polyether polyol I and polyether polyol III is independently 2.5-3.5, and the average functionality of polyether polyol II is 2-3.

[0032] Furthermore, the raw materials for the isocyanate reactive component also include a catalyst and a chain extender.

[0033] Furthermore, the chain extender includes chain extender I and chain extender II, and the catalyst includes catalyst I and catalyst II;

[0034] Wherein, the chain extender I is selected from one or more of 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, and dodecanediol;

[0035] The chain extender II is one or more of ethylene glycol, diethylene glycol, triethylene glycol, methylpropanediol, and trimethylpentanediol;

[0036] The catalyst I is one or more of the following: triethylenediamine ethylene glycol solution, triethylenediamine butylene glycol solution, triethylenediamine propylene glycol solution, bis(dimethylaminoethyl) ether-dipropylene glycol solution, bis(dimethylaminoethyl) ethylene glycol ether, pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, dibutyltin dilaurate, stannous octanoate, dibutyltin diacetate, bismuth isooctanoate, and zinc isooctanoate;

[0037] The catalyst II is one or more of dimethylethanolamine, tetramethyldipropylenetriamine, N-(dimethylaminopropyl)diisopropanolamine, trimethylhydroxyethylpropanediamine, and trimethylhydroxyethylethylenediamine.

[0038] Preferably, based on the total mass of the isocyanate reactive components, the amount of chain extender I is 5.93% to 14%, the amount of chain extender II is 0.5% to 3%, the amount of catalyst I is 0.05% to 0.3%, and the amount of catalyst II is 0.02% to 0.1%.

[0039] In some embodiments, the molar ratio of isocyanate groups in the isocyanate prepolymer to active hydrogen atoms in the isocyanate reactive component is 90–120:100.

[0040] In some embodiments, the isocyanate prepolymer is prepared by reacting raw materials comprising the following mass percentages, based on the total mass of the isocyanate prepolymer:

[0041] Diisocyanate monomer, 65%–85%;

[0042] Diisocyanate derivatives, 8%–14%;

[0043] Small molecule diols, 7%–13%;

[0044] Polysiloxane, 0%–8%.

[0045] Preferably, the polysiloxane has a mass percentage of 0.5-8%;

[0046] And / or, the diisocyanate monomer is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, naphthalene diisocyanate, terephthalic diisocyanate, 1,4-cyclohexane diisocyanate, phenylenediamine diisocyanate, cyclohexane diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, tetramethyl-isophthalic acid diisocyanate, norbornane diisocyanate, dimethyl biphenyl diisocyanate, and methylcyclohexyl diisocyanate;

[0047] And / or, the diisocyanate derivative is selected from one or more of carbodiimide-modified MDI, carbodiimide-urea-ketimide-modified MDI, and urethane-modified MDI;

[0048] And / or, the small molecule diol is selected from one or more of dipropylene glycol, diethylene glycol, 1,3-propanediol, and 1,4-butanediol;

[0049] And / or, the polysiloxane is selected from one or more of vinyl silicone oil, hydroxyl silicone oil, and amino silicone oil.

[0050] The present invention also provides a method for preparing polyurethane materials using the fully open-mold self-leveling polyurethane composition described above, comprising the following steps:

[0051] S1. Mix and stir the raw materials of the isocyanate reactive component evenly to obtain the isocyanate reactive component;

[0052] S2. The isocyanate prepolymer at a temperature of 30-55℃ and the isocyanate reactive component at a temperature of 30-55℃ are mixed evenly and then injected into an open mold at a temperature of 30-55℃ to foam and solidify.

[0053] Preferably, step S1 is performed at 20–50°C;

[0054] And / or, the raw materials for preparing the isocyanate prepolymer are stirred and reacted at 60-90°C under a nitrogen atmosphere to obtain the isocyanate prepolymer;

[0055] And / or, in step S2, after the isocyanate prepolymer and the isocyanate reactive component are mixed evenly, they are injected into the mold at a casting flow rate of 50-300 g / s.

[0056] The present invention also provides the application of the fully open-mold self-leveling polyurethane composition described above or the polyurethane material prepared by the method described above in shock-absorbing pads.

[0057] The technical solution provided by this invention has the following beneficial effects:

[0058] The polyurethane composition provided by this invention exhibits excellent raw material flowability, compatibility, and reaction uniformity during the preparation of polyurethane materials through open-mold injection molding. The resulting polyurethane material possesses dimensional regularity and performance uniformity comparable to closed-mold injection molded materials, and also features high stiffness and high elongation, meeting the technical requirements for polyurethane elastic pads under pillows. Furthermore, the polyurethane composition provided by this invention, when used for open-mold injection molding to prepare polyurethane materials, effectively overcomes the problems of complex processes, low product uniformity, and large dimensional deviations encountered when polyurethane materials are combined with other materials. Detailed Implementation

[0059] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" may be used herein to include any and all combinations of one or more of the associated listed items.

[0061] In one aspect, the present invention provides a fully open-mold self-leveling polyurethane composition, the composition comprising an isocyanate reactive component and an isocyanate prepolymer;

[0062] Based on the total mass of the isocyanate reactive component, the isocyanate reactive component is a mixture comprising the following raw materials in the following mass percentages:

[0063] Polyether polyol I, 58%–70%;

[0064] Polyether polyol II, 6%–16%;

[0065] Polyether polyol III, 1%–7%;

[0066] Foaming agent, 0.1%–0.4%;

[0067] Compatibilizer, 0.1%–0.6%;

[0068] Surfactant, 0.3-1.2%;

[0069] The polyether polyol I has an average molecular weight of 2000-6000 g / mol, and based on the total mass of ethylene oxide (EO) and propylene oxide (PO) as 100%, the ethylene oxide content is 10-20 wt% and the propylene oxide content is 80-90 wt%.

[0070] Polyether polyol II is a polytetrahydrofuran polyol with an average molecular weight of 1000-3000 g / mol;

[0071] The average molecular weight of polyether polyol III is 200-1000 g / mol. Based on the total mass of ethylene oxide and propylene oxide as 100%, the ethylene oxide content is 90-100 wt% and the propylene oxide content is 0-10 wt%.

[0072] The compatibilizer is one or more of polysiloxane, modified polysiloxane, and fluorinated acrylate copolymer;

[0073] The surfactant is a polyether-modified organosilicon surfactant.

[0074] The polyurethane composition provided by this invention uses polyether polyols I, II, and III of the above-mentioned type as the isocyanate reactive component, combined with solubilizers and surfactants of the above-mentioned type according to the above-mentioned dosage range. Based on this isocyanate reactive component, the polyurethane composition exhibits good raw material flowability, compatibility, and reaction uniformity during the preparation of polyurethane materials by open-mold injection molding. The resulting polyurethane material has dimensional regularity and performance uniformity comparable to closed-mold injection materials, and the obtained material has characteristics such as low density, high stiffness, and high elongation, which can meet the technical requirements of polyurethane elastic pads under pillows. The polyurethane composition provided by this invention can effectively overcome the problems of complex processes, low product uniformity, large dimensional deviations, and poor surface quality encountered when polyurethane materials are compounded with other materials by open-mold injection molding to prepare polyurethane materials.

[0075] In a preferred embodiment, the surfactant comprises surfactant I and surfactant II; based on the total mass of the isocyanate reactive component, the mass percentages of surfactant I and surfactant II are 0.1% to 0.6%, respectively; surfactant I is a polyether-modified silicone surfactant derived from the block copolymerization of polysiloxane and olefin oxide, preferably an AB-type linear block structure, such as one or more selected from, but not limited to, Evonik's B4900, B8002, B8285, B8408, B8484, B8681, B86890, B8233, and B8242; surfactant II is a polyether-modified silicone surfactant derived from the graft copolymerization of polysiloxane and olefin oxide, preferably a multi-branched structure, such as one or more selected from, but not limited to, Air Products' DC193, DC198, DC3042, DC3043, DC5043, DC4020, DC5098, LK-221E, and LK-443E. The inventors have discovered that, in the formulation system of this invention, the use of surfactant I and surfactant II of the above type in combination according to the above dosage, and their organic integration and mutual matching with other components in the formulation system of this invention, can effectively reduce the surface tension of the system, form more nucleation sites, thereby facilitating the obtaining of a uniform and fine cell structure, further improving the surface smoothness of the product, and resulting in a product with smaller dimensional deviations.

[0076] In the polyurethane composition of the present invention, the compatibilizer used in the isocyanate reactive component is one or more selected from polysiloxanes, modified polysiloxanes, and fluorinated acrylate copolymers. In a preferred embodiment, a silicone-modified polysiloxane is more preferred, for example, selected from, but not limited to, BYK-S706, BUK-038, BYK-375, BYK-220S, BYK-300, BYK-033, BYK-9909, BYK-359, BYK-P105, and BYK-085 from BYK Chemicals GmbH, Germany. Using the above-mentioned preferred types of solubilizers in the isocyanate reactive component of the present invention, in combination with other components in the formulation system, results in better compatibility among various raw materials in the reaction system, leading to a more homogeneous system.

[0077] In this invention, the average molecular weight of the polyether polyol I in the isocyanate reactive component is 2000-6000 g / mol, preferably 4000-6000 g / mol; preferably, the average functionality is independently 2-4, more preferably 2.5-3.5. Specifically, the polyether polyol I is, for example, a compound polymerized from ethylene oxide and propylene oxide using a small molecule polyol as an initiator, wherein the ethylene oxide content is 10-20 wt%, preferably 13-18 wt%, and the propylene oxide content is 80-90 wt%, based on the total mass of propylene oxide and ethylene oxide being 100%. The small molecule polyol initiator used includes, but is not limited to, one or more of the following: ethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, hexanediol, propylene glycol, pentanediol, diethylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethylolpropane, and glycerol. The epoxide monomer can be obtained through block addition or random addition, preferably block addition, and more preferably through propylene oxide polymerization followed by ethylene oxide block addition at the end.

[0078] In this invention, the polyether polyol II in the isocyanate reactive component is a polytetrahydrofuran polyol with an average molecular weight of 1000-3000 g / mol, preferably 1500-3000 g / mol; preferably with an average functionality of 2-4, more preferably 2-3; specifically, the polyether polyol II is, for example, formed by ring-opening polymerization of tetrahydrofuran, copolymerized with a small amount of propylene oxide and ethylene oxide, preferably by ring-opening polymerization of pure tetrahydrofuran. Adding the above-mentioned polyether polyol II to the formulation system of this invention, used in combination with other components, interacts with each other, and can significantly improve the toughness, tensile strength, and other properties of the product without affecting the system compatibility.

[0079] In this invention, the average molecular weight of the polyether polyol III in the isocyanate reactive component is 200-1000 g / mol, preferably 250-600 g / mol; the average functionality is preferably 2-4, more preferably 2.5-3.5; specifically, the polyether polyol III is, for example, a compound polymerized from ethylene oxide and propylene oxide using a small molecule polyol as an initiator, with an ethylene oxide content of 90-100 wt%, preferably 95-100 wt%, and a propylene oxide content of 0-10 wt%, based on the total mass of propylene oxide and ethylene oxide as 100%. The small molecule polyol initiator used includes, but is not limited to, one or more of ethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, hexanediol, propylene glycol, pentanediol, diethylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, trimethylolpropane, glycerol, etc. The epoxide monomer can be obtained through block addition or random addition, with block addition being preferred, and ethylene oxide polymerization being even more preferred. Adding the above-mentioned polyether polyol III to the formulation system of this invention, and using it in combination with other components, allows for interaction and can significantly improve the reactivity and properties of the product, such as rigidity and surface smoothness.

[0080] In a preferred embodiment, the average functionality of polyether polyol I, polyether polyol II, and polyether polyol III is independently 2-4; more preferably, the average functionality of polyether polyol I and polyether polyol III is independently 2.5-3.5, and the average functionality of polyether polyol II is 2-3.

[0081] In a preferred embodiment, the polyether polyol III contains 95-100 wt% ethylene oxide, based on the total mass of ethylene oxide and propylene oxide.

[0082] Furthermore, the raw materials for the isocyanate reactive component also include a catalyst and a chain extender, which can be of types commonly used in the art.

[0083] In a preferred embodiment, the chain extender includes chain extender I and chain extender II, and the catalyst includes catalyst I and catalyst II; wherein, chain extender I is selected from one or more of 1,2-propanediol, 1,3-propanediol, 1,4-butanediol (BDO), 1,3-butanediol, neopentyl glycol, and dodecanediol; chain extender II is one or more of ethylene glycol (EG), diethylene glycol, triethylene glycol, methylpropanediol, and trimethylpentanediol; and catalyst I is a compound with catalytic activity towards isocyanates and active hydrogen atoms, such as one or more of amine catalysts and organometallic catalysts. Preferably, it is one or more of the following: triethylenediamine ethylene glycol solution, triethylenediamine butylene glycol solution, triethylenediamine propylene glycol solution, bis(dimethylaminoethyl) ether-dipropylene glycol solution, bis(dimethylaminoethyl) ethylene glycol ether, pentamethyldiethylenetriamine, pentamethyldipropylenetriamine, dibutyltin dilaurate, stannous octoate, dibutyltin diacetate, bismuth isooctanoate, and zinc isooctanoate; the catalyst II is a reactive, low-odor, low-atomization amine catalyst, preferably one or more of dimethylethanolamine, tetramethyldipropylenetriamine, N-(dimethylaminopropyl)diisopropanolamine, trimethylhydroxyethylpropanediamine, and trimethylhydroxyethylethylenediamine.

[0084] In a preferred embodiment, based on the total mass of the isocyanate reactive components, the amount of chain extender I is 5.93% to 14%, the amount of chain extender II is 0.5% to 3%, the amount of catalyst I is 0.05% to 0.3%, and the amount of catalyst II is 0.02% to 0.1%.

[0085] The foaming agent used is one commonly used in the art, such as water.

[0086] In a preferred embodiment, the molar ratio of isocyanate groups in the isocyanate prepolymer to active hydrogen atoms in the isocyanate reactive component is 90–120:100.

[0087] In some embodiments, the isocyanate prepolymer is prepared by reacting raw materials comprising the following mass percentages, based on the total mass of the isocyanate prepolymer:

[0088] Diisocyanate monomer, 65%–85%;

[0089] Diisocyanate derivatives, 8%–14%;

[0090] Small molecule diols, 7%–13%;

[0091] Polysiloxane, 0%–8%.

[0092] In a preferred embodiment, the polysiloxane has a mass percentage of 0.5-8%. In the formulation system of the above-mentioned combination of isocyanate reactive component and isocyanate prepolymer of the present invention, the addition of polysiloxane to the isocyanate prepolymer is beneficial to further reduce surface tension, improve the compatibility between components, further improve the flatness of the product, further reduce the dimensional deviation of the obtained product, and obtain a product with better quality.

[0093] In a preferred embodiment, the diisocyanate monomer is selected, for example, but not limited to, one or more of the following: toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), naphthalene diisocyanate (NDI), terephthalic diisocyanate (PPDI), 1,4-cyclohexane diisocyanate (CHDI), phenylenediamine diisocyanate (XDI), cyclohexane diisocyanate (HXDI), trimethyl-1,6-hexamethylene diisocyanate (TMHDI), tetramethyl-isophthalic diisocyanate (TMXDI), norbornane diisocyanate (NBDI), dimethylbiphenyl diisocyanate (TODI), and methylcyclohexyl diisocyanate (HTDI).

[0094] In a preferred embodiment, the diisocyanate derivative is selected, for example, but not limited to, one or more of carbodiimide-modified MDI, carbodiimide-urea-ketimide-modified MDI, and urethane-modified MDI;

[0095] Small molecule diols refer to diols with a molecular weight of less than 250. In a preferred embodiment, the small molecule diol is selected, for example, from, but not limited to, one or more of dipropylene glycol, diethylene glycol, 1,3-propanediol, and 1,4-butanediol.

[0096] The polysiloxane is one or more of the following: vinyl silicone oil, hydroxyl silicone oil, and amino silicone oil.

[0097] In a preferred embodiment, based on the total mass of the isocyanate reactive component, the mass percentage of polyether polyol I used to prepare the isocyanate reactive component is preferably 58-68%, the mass percentage of polyether polyol II is preferably 8-16%, and the mass percentage of polyether polyol III is preferably 2-5%; the polyurethane material prepared in this preferred manner has better elongation at break.

[0098] In a preferred embodiment, based on the total mass of the isocyanate reactive component, the raw materials used to prepare the isocyanate reactive component contain 58-68% polyether polyol I, 8-16% polyether polyol II, and 2-5% polyether polyol III by mass; the surface activity is a combination of surfactant I and surfactant II; and based on the total mass of the isocyanate prepolymer, the isocyanate prepolymer is prepared using 0.5-8% polysiloxane by mass. The polyurethane material obtained by casting using this preferred method better balances tensile strength, elongation at break, and relatively low dimensional deviation.

[0099] The present invention also provides a method for preparing polyurethane materials using the fully open-mold self-leveling polyurethane composition described above, comprising the following steps:

[0100] S1. Mix and stir the raw materials of the isocyanate reactive component evenly to obtain the isocyanate reactive component;

[0101] S2. The isocyanate prepolymer at a temperature of 30-55℃ and the isocyanate reactive component at a temperature of 30-55℃ are mixed evenly and then injected into an open mold at a temperature of 30-55℃ to foam and solidify.

[0102] The polyurethane composition formulation system of this invention, through precise compounding of each raw material in the isocyanate reactive component, and by preparing the polyurethane material at the aforementioned material temperatures and mold temperatures, not only allows for fully open-mold injection molding, but also exhibits high raw material flowability, compatibility, and reaction uniformity. It achieves the same dimensional regularity and performance uniformity as other closed-mold injection molding materials, overcoming problems such as overly complex processes, low product uniformity, and large dimensional deviations encountered when polyurethane materials are compounded with other materials. Furthermore, the resulting product has excellent surface quality, low density, high stiffness, and high elongation, meeting the technical requirements for polyurethane elastic pads under pillows. In a more preferred embodiment, adding an appropriate amount of polysiloxane to the isocyanate prepolymer further improves the compatibility between the components and further improves the smoothness and other properties of the product.

[0103] Preferably, step S1 is performed at 20–50°C.

[0104] The isocyanate prepolymer used can be obtained by reacting the raw materials for preparing the isocyanate prepolymer under a nitrogen atmosphere at 60-90°C with stirring, for example, for 2-4 hours. Preferably, based on the total mass of the isocyanate prepolymer, it is prepared by reacting raw materials comprising the following mass percentages: diisocyanate monomer, 65%-85%; diisocyanate derivative, 8%-14%; small molecule diol, 7%-13%; polysiloxane, 0%-8%, preferably 0.5-8%. The descriptions of the raw materials for preparing the isocyanate prepolymer are as described above and will not be repeated here.

[0105] Preferably, in step S2, after the isocyanate prepolymer and the isocyanate reactive component are mixed evenly, they are injected into the mold at a casting flow rate of 50-300 g / s.

[0106] Using the preparation method of this invention, a density of 350-650 kg / m³ can be obtained. 3 Hardness: 65-95 Asker A; Tensile strength: 4.0-7.0 MPa; Elongation at break: 165-235%; Static modulus: 30-50 N / mm² 3 Polyurethane microporous elastomer.

[0107] The present invention also provides the application of the fully open-mold self-leveling polyurethane composition described above or the polyurethane material prepared by the method described above in shock-absorbing pads.

[0108] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the following embodiments are merely illustrative and should not be construed as limiting the present invention to these embodiments.

[0109] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in this technical field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0110] The descriptions of some of the raw materials involved in the following embodiments or comparative examples are shown in Table 1 below:

[0111] Table 1

[0112]

[0113] The preparation steps for each embodiment and comparative example are as follows:

[0114] Step 1: Mix and stir the isocyanate reactive components at 20-50℃ (see Tables 2-1 and 2-2 for specific temperatures, "Mixing Temperature of Reactive Components") to obtain the isocyanate reactive components for later use; see Tables 2-1 and 2-2 for the raw materials and their mass percentages in the isocyanate reactive components in each example and comparative example.

[0115] Step 2: At 60–90℃ (specific temperatures are shown in Tables 2-1 and 2-2 under “Isocyanate Prepolymer Mixing Temperature”), all raw materials required for preparing the isocyanate prepolymer are stirred in a nitrogen atmosphere for 2–4 hours (specific times are shown in Tables 2-1 and 2-2 under “Isocyanate Prepolymer Mixing Time”) to obtain the isocyanate prepolymer for later use; in each example and comparative example, based on the total mass of the isocyanate prepolymer, the raw materials and their mass percentages are shown in Tables 2-1 and 2-2.

[0116] Step 3: Mix the isocyanate prepolymer and the isocyanate reactive component evenly. The molar ratio of isocyanate groups in the isocyanate prepolymer to active hydrogen atoms in the isocyanate reactive component is shown in Tables 2-1 and 2-2. Then, pour the mixture into the mold (pouring flow rate is 50-300 g / s, see Table 2 for details) and allow it to foam and cure. Remove the mixture from the mold after 6-10 minutes (see "Mold Opening Time" in Table 2 for specific time).

[0117] The material temperature of the isocyanate prepolymer mentioned in step 3 is shown in Tables 2-1 and 2-2, the material temperature of the isocyanate reactive component is shown in Tables 2-1 and 2-2, and the temperature of the mold is shown in Tables 2-1 and 2-2.

[0118] The raw materials and their mass fractions used in each embodiment and comparative example are shown in Tables 2-1 and 2-2:

[0119] The percentages in Tables 2-1 and 2-2 are all mass percentages.

[0120] Table 2-1

[0121]

[0122]

[0123] Table 2-2

[0124]

[0125]

[0126]

[0127] The performance of the polyurethane microporous elastomers prepared in each embodiment and comparative example was tested, and the testing methods are described below:

[0128] Tensile strength and elongation at break: Tested according to the test methods provided in GB / T2568-1995;

[0129] Dimensional deviation: According to the railway industry standard TBT 2629-2023, the dimensions of the polyurethane microporous elastomer are measured 7 days after demolding. The length and width of the polyurethane microporous elastomer are compared with the length and width of the mold, and the length and width differences are calculated as the length and width dimensional deviations. The thickness is determined according to the thickness difference between the thickest and thinnest parts of the polyurethane microporous elastomer.

[0130] Appearance Quality: After demolding, confirm the dimensions of the polyurethane microporous elastomer and check for any missing corners. The sum of the length, width, and thickness of the missing part should not exceed 6mm; otherwise, it is considered to have a missing corner. Check for any pits. The length of a single pit should not exceed 15mm, the width should not exceed 5mm, and the depth should not exceed 0.5mm. Each piece should not have more than 3 pits. If all the above conditions are met, it is considered to be "pit-free." If at least one condition is not met, it is considered to have a pit. Check for any rough surfaces. There should not be more than 2 rough surfaces on the working surface with a diameter greater than 3mm; otherwise, it is considered to have rough surfaces.

[0131] Static modulus: Measured in accordance with railway industry standard TBT 2629-2023.

[0132] Table 3

[0133]

[0134]

[0135] As shown in Table 3, the polyurethane composition of this invention, through precise compounding of isocyanate reactive components and combination with isocyanate prepolymer, can be injection molded in a fully open mold. It exhibits high raw material flowability, compatibility, and reaction uniformity, achieving dimensional regularity and performance uniformity comparable to other closed-mold injection molding materials. By employing an optimized preparation process temperature, it is beneficial to achieve better surface quality of the open-mold casting material. The prepared polyurethane microporous elastomer has high surface quality, free from defects, pits, and roughness. Simultaneously, it can comprehensively consider relatively small dimensional deviations in length, width, and thickness, and also achieve good tensile strength (4.0-7.0 MPa), elongation at break (155-235%), and static modulus (30-50 N / mm²). 3 ).

[0136] As can be seen from the comparison of the embodiments and the comparative examples, the polyurethane microporous elastomer prepared by mold casting in the comparative examples is difficult to balance with small dimensional deviations, good elongation at break and static modulus, and it also has no advantage in appearance quality.

[0137] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A fully open mold self-leveling polyurethane composition characterized in that, The composition comprises an isocyanate-reactive component and an isocyanate prepolymer; The isocyanate-reactive component is a mixture comprising the following mass percentages of raw materials, based on the total mass of the isocyanate-reactive component: Polyether polyol I, 58% to 70%; Polyether polyol II, 6% to 16%; Polyether polyol III, 1% to 7%; Foaming agent, 0.1% to 0.4%; Compatibilizer, 0.1% to 0.6%; Surfactant, 0.3-1.2%; The average molecular weight of the polyether polyol I is 2000-6000 g / mol, the ethylene oxide content is 10-20 wt%, and the propylene oxide content is 80-90 wt%, based on the total mass of ethylene oxide and propylene oxide being 100%; The polyether polyol II is a polytetrahydrofuran polyol, and the average molecular weight is 1000-3000 g / mol; The average molecular weight of the polyether polyol III is 200-1000 g / mol, the ethylene oxide content is 90-100 wt%, and the propylene oxide content is 0-10 wt%, based on the total mass of ethylene oxide and propylene oxide being 100%; The compatibilizer is one or more of polysiloxane, modified polysiloxane, and fluorine-modified acrylate copolymer; The surfactant is a polyether-modified organosilicon surfactant.

2. The fully open mold self-leveling polyurethane composition according to claim 1, wherein, The surfactant comprises surfactant I and surfactant II, and the mass percentages of the surfactant I and the surfactant II are 0.1% to 0.6%, respectively, based on the total mass of the isocyanate-reactive component; The surfactant I is a polyether-modified organosilicon surfactant of polysiloxane and oxyalkylene block copolymer; The surfactant II is a polyether-modified organosilicon surfactant of polysiloxane and oxyalkylene graft copolymer.

3. The fully open mold self-leveling polyurethane composition according to claim 2, wherein, The surfactant I has an AB type linear block structure, and the surfactant II has a multi-branched type structure; And / or, the compatibilizer is organosilicon-modified polysiloxane; And / or, the average molecular weight of the polyether polyol I is 4000-6000 g / mol; And / or, the average molecular weight of the polyether polyol II is 1500-3000 g / mol; And / or, the average molecular weight of the polyether polyol III is 250-600 g / mol; And / or, the average functionality of the polyether polyol I, the polyether polyol II, and the polyether polyol III is independently 2-4, respectively; And / or, the polyether polyol III has an ethylene oxide content of 95-100 wt%, based on the total mass of ethylene oxide and propylene oxide being 100%; And / or, the molar ratio of isocyanate groups in the isocyanate prepolymer to active hydrogen atoms in the isocyanate-reactive component is 90-120:

100.

4. The fully open mold self-leveling polyurethane composition according to any one of claims 1 to 3, characterized in that, The raw materials of the isocyanate-reactive component further comprise a catalyst and a chain extender; The chain extender comprises chain extender I and chain extender II, and the catalyst comprises catalyst I and catalyst II; The chain extender I is selected from one or more of 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, neopentyl glycol, dodecanediol; The chain extender II is one or more of ethylene glycol, diethylene glycol, triethylene glycol, methylpropanediol, trimethylpentanediol; The catalyst I is one or more of triethylenediamine glycol solution, triethylenediamine butanediol solution, triethylenediamine propanediol solution, bis(dimethylaminoethyl) ether-dipropanediol solution, bis(dimethylaminoethyl) glycol ether, pentamethyldiethylenetriamine, pentamethyldipropylene triamine, dibutyl tin dilaurate, stannous octoate, dibutyl tin diacetate, bismuth iso-octoate, zinc iso-octoate; The catalyst II is one or more of dimethyl ethanolamine, tetramethyl dipropylene triamine, N-(dimethylaminopropyl) diisopropanolamine, trimethyl hydroxyethyl propanediamine, trimethyl hydroxyethyl ethylenediamine.

5. The fully open mold self-leveling polyurethane composition according to claim 4, wherein, Based on the total mass of the isocyanate reactive component, the amount of chain extender I is 5.93% to 14%, the amount of chain extender II is 0.5% to 3%, the amount of catalyst I is 0.05% to 0.3%, and the amount of catalyst II is 0.02% to 0.1%.

6. The fully open mold self-leveling polyurethane composition according to any one of claims 1-3, characterized in that, Based on the total mass of the isocyanate prepolymer, the isocyanate prepolymer is prepared by reacting raw materials including the following mass percentages: Diisocyanate monomer, 65% to 85%; Diisocyanate derivative, 8% to 14%; Small molecule diol, 7% to 13%; Polysiloxane, 0% to 8%.

7. The fully open mold self-leveling polyurethane composition according to claim 6, wherein, The mass percentage of the polysiloxane is 0.5-8%; And / or, the diisocyanate monomer is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate, 1,4-cyclohexane diisocyanate, xylylene diisocyanate, cyclohexane dimethylene diisocyanate, trimethyl-1,6-hexamethylene diisocyanate, tetramethyl m-xylylene diisocyanate, norbornane diisocyanate, dimethyl diphenyl diisocyanate, methylcyclohexyl diisocyanate; And / or, the diisocyanate derivative is selected from one or more of carbodiimide modified MDI, carbodiimide-uretonimine modified MDI, urethane modified MDI; And / or, the small molecule diol is selected from one or more of dipropylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol; And / or, the polysiloxane is selected from one or more of vinyl silicone oil, hydroxyl silicone oil, amino silicone oil.

8. A method of making a polyurethane material using the fully open mold self-levelling polyurethane composition according to any one of claims 1 to 7, characterized in that, The steps include: S1, mixing and stirring the raw materials of the isocyanate reactive component uniformly to obtain the isocyanate reactive component; S2, mixing the isocyanate prepolymer at a temperature of 30-55℃ and the isocyanate reactive component at a temperature of 30-55℃ uniformly, then injecting into an open mold at a temperature of 30-55℃ to foam and solidify.

9. The method of claim 8, wherein, Step S1 is carried out at 20-50℃. and / or, the raw materials for preparing the isocyanate prepolymer are stirred and reacted at 60-90°C under nitrogen atmosphere to obtain the isocyanate prepolymer; and / or, in step S2, after the isocyanate prepolymer and the isocyanate reactive component are mixed uniformly, the opening mold is injected at a pouring flow rate of 50-300 g / s.

10. Use of the full-opening mold self-leveling polyurethane composition according to any one of claims 1-7 or the polyurethane material prepared by the method according to any one of claims 8-9 in shock pads.

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