Low density solvent resistant, shrink resistant polyurethane microcellular elastomers, methods of making and use thereof
By forming a covalent graft of silica and polyester polyol in the all-water foamed polyurethane sole and the synergistic effect of the leveling agent, the dispersion and interfacial compatibility problems of nano-silica in the polyurethane matrix are solved, and the solvent resistance and dimensional stability of the low-density polyurethane sole are achieved, making it suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG INOV POLYURETHANE
- Filing Date
- 2026-03-09
- Publication Date
- 2026-06-05
AI Technical Summary
Existing all-water foamed polyurethane shoe soles have difficulty controlling the cell structure under low-density conditions, resulting in insufficient surface density, easy corrosion, and easy shrinkage at high temperatures. The poor interfacial compatibility between nano-silica and organic polyurethane matrix leads to paint erosion and paint pitting.
The covalent grafting of silica and polyester polyol is formed through amino-hydroxy condensation reaction. Combined with leveling agent, a "core-shell" structure is constructed to improve the dispersion and interfacial compatibility of nanoparticles and synergistically form a dense skin layer to block solvent penetration.
In the low-density range, polyurethane soles exhibit excellent resistance to paint corrosion and dimensional stability. They show no pitting or pores after multiple paint applications, do not shrink after high-temperature heating, and withstand more than 100,000 folds. The manufacturing process is simple and controllable.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polyurethane elastomer technology, specifically relating to low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomers, their preparation methods, and applications. Background Technology
[0002] With increasingly stringent environmental protection requirements, the use of physical foaming agent 141B has been banned. Water-foamed polyurethane soles, due to their environmental friendliness and low cost, have gained widespread attention in the low-density footwear manufacturing sector. However, in low-density (≤300kg / m³) applications… 3 Under these conditions, the all-water foaming system still faces multiple technical challenges: high water volume leads to the generation of a large amount of CO2, making it difficult to control the cell structure, balance the cell diameter and foaming rate, and easily result in an excessively thin and poorly dense outer layer. On the one hand, during the sole painting process, paint solvents can easily penetrate and erode the porous core layer, causing surface corrosion pitting; on the other hand, during high-temperature heat treatment after painting, the sole is prone to shrinkage and deformation, seriously affecting the product qualification rate.
[0003] Compared to polyurethane soles prepared with physical foaming agents, all-water-foamed products have insufficient surface density, thinner thickness, and poorer corrosion resistance. After paint penetration, moisture can easily seep into the material, causing hydrolytic aging and shortening the sole's lifespan. To improve product performance, the industry often uses the addition of nano-silica. However, inorganic silica has extremely poor interfacial compatibility with the organic polyurethane matrix, easily leading to agglomeration and further increasing surface porosity. During painting, organic solvents such as toluene and ethyl acetate can easily penetrate the pores into the surface, triggering ester bond hydrolysis and nucleophilic attack reactions, forming corrosion pits.
[0004] To address the poor interfacial compatibility and agglomeration issues between inorganic silica and organic polyurethane matrices, existing technologies typically modify silica. There are two main silica modification processes: one involves isocyanate (such as IPDI and MDI) modification, and the other uses special functional monomers like hyperbranched polyesters to form a network structure. Patent CN117089035A discloses a method for isocyanate-modified nano-silica, employing a two-step wet modification process: first, nano-silica reacts with polyisocyanates in an organic solvent; after separation, the intermediate product is transferred to water for a secondary reaction, and finally dried to obtain the modified product. This patent relies excessively on isocyanate modification, leading to a complex system composition, increased side reactions, and the high reactivity of isocyanates with water, increasing the stability risk of the all-water foaming process. On the other hand, using special functional monomers like hyperbranched polyesters to form a network structure presents problems such as high raw material costs, complex processes, and significant degradation of mechanical properties due to higher functionality, making industrial-scale production difficult.
[0005] Therefore, there is an urgent need for a technical solution that uses readily available raw materials, has a simple process, and can fundamentally solve the interfacial compatibility problem, thereby addressing the core pain points of low-density polyurethane shoe soles being susceptible to paint corrosion and shrinking easily at high temperatures. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the present invention aims to provide a low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer. This is achieved through covalent grafting via an amino-hydroxyl condensation reaction, fundamentally solving the dispersion and interfacial compatibility issues of nano-silica in the polyurethane matrix. Simultaneously, it works synergistically with leveling agents and other components to achieve a density of 220-300 kg / m³. 3 Within the low-density range, it imparts excellent resistance to paint corrosion and dimensional stability to the sole surface.
[0007] This invention also provides its preparation method and application, which are simple, highly controllable, and suitable for industrial production.
[0008] The low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer of this invention is composed of component A and component B in a mass ratio of 100:(75-85), wherein component A comprises the following raw materials in parts by mass:
[0009] Polyester polyol P1: 60-90 parts;
[0010] Polyester polymer polyol P2: 10-40 parts;
[0011] Polyester polyol grafted with silica: 2-5 parts;
[0012] Chain extender: 4-8 parts;
[0013] Leveling agent: 1-3 parts;
[0014] Foaming agent: 0.5-1 part;
[0015] Foaming agent: 1-2 parts;
[0016] Catalyst: 1-2 parts;
[0017] The sum of the mass fractions of polyester polyol P1 and polyester polymer polyol P2 in component A is 100 parts.
[0018] Component B is composed of the following raw materials in parts by mass:
[0019] Polyester polyol P1: 10-20 parts;
[0020] Polyether polyol: 5-15 parts;
[0021] Isocyanate: 65-85 parts;
[0022] The polyester polyol P1 is prepared by alkyd condensation reaction of small molecule polyol and adipic acid, with a number average molecular weight of 1000-2000 g / mol; preferably, it is one or two of PE-2410, PE-2515, PE-4020 and PE-2325 produced by Shandong Yinuowei Polyurethane Co., Ltd.
[0023] The polyester polymer polyol P2 is a polyester polymer polyol containing benzene rings. It is prepared by esterification of a small molecule polyol with adipic acid to obtain a base polyester with a molecular weight of 2000 g / mol, and then by graft copolymerization of the base polyester with styrene. P-245T produced by Shandong Yinuowei Polyurethane Co., Ltd. is preferred.
[0024] The polyether polyol is a polyether diol copolymerized from ethylene oxide and propylene oxide, with a number average molecular weight of 4000-5000 g / mol, preferably one or two of EP-330NG and ED-28 produced by Shandong Lanxing Dongda Chemical Co., Ltd., and Donol 820 produced by Shanghai Dongda Chemical Co., Ltd.
[0025] The preparation method of the polyester polyol grafted modified silica includes the following steps:
[0026] The product is obtained by reacting polyester polyol with amino-modified silica under the action of a catalyst and heating the mixture to remove water.
[0027] Specifically:
[0028] A. Preparation of amino-terminated modified silica:
[0029] Nano-silica was dispersed in anhydrous toluene, an amino-containing silane coupling agent was added and the temperature was raised to react. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain amino-terminated modified silica.
[0030] B. Preparation of polyester polyol grafted modified silica
[0031] Amino-terminated modified silica, polyester polyol, and catalyst were added to a reaction vessel, heated to a high temperature, and the generated water was removed to obtain viscous polyester polyol-grafted modified silica.
[0032] Further:
[0033] A. Preparation of amino-terminated modified silica:
[0034] Nano-silica was dispersed in anhydrous toluene and sonicated for 30-50 minutes. Under a nitrogen atmosphere, an amino-containing silane coupling agent KH-550 was slowly added while stirring. The mass ratio of the amino-containing silane coupling agent to silica was 1:10. The temperature was raised to 80°C and refluxed for 6 hours. After the reaction was completed, the mixture was centrifuged, washed three times each with toluene and anhydrous ethanol, and dried under vacuum at 80°C to obtain amino-terminated modified silica.
[0035] B. Preparation of polyester polyol grafted modified silica
[0036] Amino-terminated modified silica, polyester polyol P1, and dibutyltin dilaurate catalyst were added to a reaction vessel, with the mass ratio of amino-modified silica to polyester polyol P1 being 1:5. Under nitrogen protection, the mixture was heated to 150°C and reacted for 4 hours under a vacuum of -0.09 MPa. The generated water was removed to obtain viscous polyester polyol-grafted modified silica.
[0037] The leveling agent is a polyether-modified organosilicon compound. LP-310 from Hangzhou Jessica Chemical Co., Ltd. is preferred.
[0038] The small molecule polyol is one or more of ethylene glycol, diethylene glycol, 1,4-butanediol and trimethylolpropane.
[0039] The chain extender is one or two of ethylene glycol, diethylene glycol, and 1,4-butanediol.
[0040] The foaming agent is a polysiloxane-olefin oxide block copolymer, preferably one or both of Evonik Specialty Chemicals B 8960 or Dow Chemical Company TF-3607.
[0041] The foaming agent is water.
[0042] The catalyst is an amine catalyst, preferably one of DXD01C, DXD 04C or DXD-07C produced by Shandong Yinuowei Polyurethane Co., Ltd.
[0043] The isocyanate is one or both of 4,4-diphenylmethane diisocyanate and carbodiimide-modified isocyanate. Preferably, it is MDI-100 or CDMDI-100L produced by Wanhua Chemical Group Co., Ltd., or CD-C produced by Covestro AG.
[0044] The -NCO content of component B is 19-26 wt.%.
[0045] The method for preparing the low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer of the present invention comprises the following steps:
[0046] (1) Add polyester polyol P1, polyester polymer polyol P2, polyester polyol grafted modified silica, chain extender, leveling agent, foaming agent, foaming agent and catalyst into a reaction vessel and mix evenly. Stir at atmospheric pressure and 50-70℃ for 2-4 hours to obtain component A.
[0047] (2) Add polyester polyol P1 and polyether polyol into the reaction vessel, control the material temperature at 60-70℃, add isocyanate, and react at 70-80℃ for 1-3 hours to obtain component B.
[0048] (3) Inject component A and component B into the material tank of the casting machine respectively. The mold temperature is controlled within 50-70℃. Inject into the mold according to the set mass ratio. After placing for 5-8 minutes, open the mold to obtain low-density solvent-resistant and shrinkage-resistant polyurethane microporous elastomer.
[0049] The application of the low-density solvent-resistant and shrinkage-resistant polyurethane microporous elastomer described in this invention is applied to polyurethane shoe sole products. Specifically, the microporous elastomer product after mold opening is subjected to 2-4 spray painting treatments and heated in a drying tunnel at 120-150℃ for 5-10 minutes to obtain a low-density solvent-resistant and shrinkage-resistant polyurethane shoe sole.
[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0051] 1. By condensing an amino-containing silane coupling agent with the hydroxyl groups of polyester polyol P1, covalent grafting of silica and polyester polyol is achieved, forming a stable "core-shell" structure. This fundamentally solves the problems of nanoparticle aggregation and interfacial compatibility. Modified silica fills the gaps in the foam cells generated during full-water foaming, fundamentally solving the problems of nanoparticle aggregation and weak interfacial bonding. It effectively blocks the contact reaction between paint solvents and polyester segments, completely avoiding the formation of paint pitting.
[0052] 2. The leveling agent and modified silica work synergistically to improve wettability during the foaming process, preventing cell agglomeration and rupture. During foaming, they migrate together to the mold interface, forming a "dispersion-leveling-densification-reinforcement" system. This collectively constructs a thick, strong, and dense outer layer, effectively blocking solvent penetration, resulting in a paint finish free of pitting and pores. The high-strength outer layer also inhibits internal shrinkage stress, preventing the shoes from shrinking after high-temperature heating.
[0053] 3. The polyurethane shoe sole obtained by this invention has a density of 220-300 kg / m³. 3 After multiple painting processes and high-temperature heating, the surface is bright, intact, and free of defects. It can withstand more than 100,000 folds and has excellent overall performance. The preparation process is simple and controllable, the raw material cost is moderate, the product yield is high, and it is suitable for continuous industrial production, giving it significant market competitiveness. Detailed Implementation
[0054] The present invention will be further described below with reference to the embodiments.
[0055] Unless otherwise specified, all raw materials used in the examples were commercially available.
[0056] The raw materials used in the following examples and comparative examples are as follows:
[0057] Polyester polyols P1: PE-2410 (number average molecular weight 1000 g / mol), PE-2515 (number average molecular weight 1500 g / mol), PE-4020 (number average molecular weight 2000 g / mol), and PE-2325 (number average molecular weight 2000 g / mol) were all purchased from Shandong Yinuowei Polyurethane Co., Ltd.
[0058] Polyester polymer polyol P2: P-245T, purchased from Shandong Yinuowei Polyurethane Co., Ltd.;
[0059] Polyether polyols: EP-330NG (number average molecular weight 5000 g / mol) and ED-28 (number average molecular weight 4000 g / mol) were purchased from Shandong Lanxing Dongda Chemical Co., Ltd.; Donol 820 (number average molecular weight 4000 g / mol) was purchased from Shanghai Dongda Chemical Co., Ltd.
[0060] Coupling agent: KH-550, purchased from Hangzhou Jessica Chemical Co., Ltd.;
[0061] Polyester polyol grafted silica: PG-410, PG-515, Shandong Yinuowei Polyurethane Co., Ltd., self-made.
[0062] Preparation method of PG-410:
[0063] (1) 50g of dry nano-silica was dispersed in 500ml of anhydrous toluene and sonicated for 30 minutes. Under a nitrogen atmosphere, 5g of KH-550 was slowly added while stirring. The temperature was raised to 80℃ and the reaction was refluxed for 6 hours. After the reaction was completed, the solid product was collected by centrifugation, washed three times each with toluene and anhydrous ethanol, and dried under vacuum at 80℃ to obtain amino-terminated modified silica.
[0064] (2) 20 g of amino-modified silica, 100 g of PE-2410, and 0.36 g of dibutyltin dilaurate catalyst were added to a reaction flask. Under nitrogen protection, the temperature was raised to 150 °C and reacted for 4 hours under a vacuum of -0.09 MPa. The generated water was then removed. After the reaction was completed, viscous polyester polyol grafted silica PG-410 was obtained.
[0065] Preparation method of PG-515:
[0066] (1) 100g of dry nano-silica was dispersed in 1000ml of anhydrous toluene and sonicated for 50 minutes. Under a nitrogen atmosphere, 10g of KH-550 was slowly added while stirring. The temperature was raised to 80℃ and the reaction was refluxed for 6 hours. After the reaction was completed, the solid product was collected by centrifugation, washed three times each with toluene and anhydrous ethanol, and dried under vacuum at 80℃ to obtain amino-terminated modified silica.
[0067] (2) 30 g of amino-modified silica, 150 g of PE-2515, and 0.54 g of dibutyltin dilaurate catalyst were added to a reaction flask. Under nitrogen protection, the temperature was raised to 150 °C and reacted for 4 hours under a vacuum of -0.09 MPa. The generated water was then removed. After the reaction was completed, viscous polyester polyol grafted silica PG-515 was obtained.
[0068] Leveling agent: LP-310, purchased from Hangzhou Jessica Chemical Co., Ltd.;
[0069] Foaming agent: B 8960, purchased from Evonik Specialty Chemicals Ltd.; TF-3607, purchased from Dow Chemical Company.
[0070] Catalysts: DXD-01C, DXD-04C, and DXD-07C were all purchased from Shandong Yinuowei Polyurethane Co., Ltd.
[0071] Isocyanates: MDI-100 and CDMDI-100L were purchased from Wanhua Chemical Group Co., Ltd.; CD-C was purchased from Covestro AG.
[0072] Example 1
[0073] The method for preparing the low-density, solvent-resistant, and shrinkage-resistant polyurethane shoe sole comprises the following steps:
[0074] (1) Preparation of component A: According to the mass fraction, turn on the stirring speed to 30Hz, and put 600g of PE-2410, 400g of P-245T, 30g of PG-515, 40g of ethylene glycol, 10g of LP-310, 5g of B 8960, 10g of water and 10g of DXD-01C into the reaction flask in sequence. After stirring at 50℃ under normal pressure for 2h, component A is obtained.
[0075] (2) Preparation of component B: According to the mass parts, 200g of PE-2410, 100g of Donol 820 and 50g of EP-330NG were added into the reaction flask in sequence, the stirring was turned on, and then the temperature was lowered to 60℃. 650g of isocyanate MDI-100 was added, and after reacting at 80℃ for 1h, component B with -NCO content of 19wt.% was obtained.
[0076] (3) The method for preparing low-density solvent-resistant and shrinkage-resistant polyurethane shoe soles using the above components A and B is as follows: Inject components A and B into the material tank of a low-pressure casting machine respectively. After rapidly mixing components A and B at a mass ratio of 100:85, inject the mixture into a mold at 70°C and open the mold after 5 minutes to obtain the low-density polyurethane shoe sole.
[0077] The obtained shoe sole is treated with two oil-based paint sprayings and heated in a 120℃ drying oven for 10 minutes to obtain a low-density, solvent-resistant, and shrinkage-resistant polyurethane shoe sole.
[0078] Example 2
[0079] The method for preparing the low-density, solvent-resistant, and shrinkage-resistant polyurethane shoe sole comprises the following steps:
[0080] (1) Preparation of component A: According to the mass parts, turn on the stirring speed to 30Hz, and put 400g of PE-2515, 500g of PE-4020, 100g of P-245T, 20g of PG-410, 80g of diethylene glycol, 30g of LP-310, 10g of TF-3607, 20g of water and 20g of DXD-04C into the reaction flask in sequence. After stirring at 70℃ under normal pressure for 4h, component A is obtained.
[0081] (2) Preparation of component B: According to the mass parts, 100g of PE-4020 and 50g of ED-28 were added into the reaction flask in sequence, the stirring was turned on, and then the temperature was lowered to 70℃. 450g of isocyanate MDI-100 and 400g of isocyanate CDMDI-100L were added. After reacting at 70℃ for 3h, component B with -NCO content of 26wt.% was obtained.
[0082] (3) The method for preparing low-density solvent-resistant and shrinkage-resistant polyurethane shoe soles using the above components A and B is as follows: Components A and B are injected separately into the material tank of a low-pressure casting machine. Components A and B are rapidly mixed at a mass ratio of 100:75 and then injected into a mold at 50°C. The mold is opened after 8 minutes to obtain the low-density polyurethane shoe sole. The obtained shoe sole is then subjected to four oil-based paint spraying treatments and heated in a 150°C drying oven for 5 minutes to obtain the low-density solvent-resistant and shrinkage-resistant polyurethane shoe sole.
[0083] Example 3
[0084] The method for preparing the low-density, solvent-resistant, and shrinkage-resistant polyurethane shoe sole comprises the following steps:
[0085] (1) Preparation of component A: According to the mass parts, turn on the stirring speed to 30Hz, and put 600g of PE-4020, 150g of PE-2325, 250g of P-245T, 20g of PG-410, 30g of PG-515, 50g of ethylene glycol, 10g of 1,4-butanediol, 20g of LP-310, 4g of B 8960, 3g of TF-3607, 15g of water and 15g of DXD-07C into the reaction flask in sequence. After stirring at 60℃ under normal pressure for 3h, component A is obtained.
[0086] (2) Preparation of component B: According to the mass parts, 100g of PE-2515, 50g of PE-2325 and 100g of Donol 820 were added to the reaction flask in sequence, the stirring was turned on, and then the temperature was lowered to 65℃. 550g of isocyanate MDI-100 and 200g of isocyanate CD-C were added. After reacting at 75℃ for 2h, component B with -NCO content of 23wt.% was obtained.
[0087] (3) The method for preparing low-density solvent-resistant and shrinkage-resistant polyurethane shoe soles using the above components A and B is as follows: Components A and B are injected into the material tank of a low-pressure casting machine, and components A and B are rapidly mixed at a mass ratio of 100:81. The mixture is then poured into a mold at 60°C, and the mold is opened after 7 minutes to obtain the low-density polyurethane shoe sole. The obtained shoe sole is then subjected to three oil-based paint spraying treatments and heated in a 135°C drying oven for 7 minutes to obtain the low-density solvent-resistant and shrinkage-resistant polyurethane shoe sole.
[0088] Comparative Example 1
[0089] Same as Example 1, except that: no polyester polyol grafted silica PG-515 is added to component A.
[0090] Comparative Example 2
[0091] Same as Example 1, except that: no leveling agent LP-310 is added to component A.
[0092] Comparative Example 3
[0093] Same as Example 1, except that the amount of polyester polyol grafted with silica PG-515 in component A is increased to 100g.
[0094] The performance of the polyurethane microporous elastomers prepared in Examples 1-3 and Comparative Examples 1-3 was tested using the following methods:
[0095] Density (kg / m³) 3 (The test shall be conducted in accordance with GB / T 6343-2009;)
[0096] Hardness (C): Tested according to GB / T 2411-2008;
[0097] Bending resistance (10,000 cycles): Tested according to SATRA TM 92;
[0098] Appearance after painting: Visually inspect the surface for pits and air bubbles;
[0099] Shrinkage: After painting, the product is heated at high temperature, and the dimensional stability is tested (no obvious dimensional change is considered as no shrinkage).
[0100] The test results are shown in Table 1:
[0101] Table 1. Performance test results of products from Examples 1-3 and Comparative Examples 1-3
[0102]
[0103] The density of the products in Examples 1-3 of this invention is 220-300 kg / m³. 3 With a hardness of 48-60C, after multiple paint treatments, the surface is glossy, free of pitting and pores, does not shrink when heated to high temperatures, and withstands more than 100,000 folds, fully meeting the technical requirements for shoe materials and demonstrating the superiority of the technical solution of this invention. By using a stable core-shell structure with silica as the "core" and polyester polyol long chains as the "shell," molecular-level dispersion of silica nanoparticles and covalent bonding with the polyurethane matrix are achieved. The modified silica fills the gaps in the cells generated by all-water foaming, fundamentally solving the problems of agglomeration and weak interfaces, preventing the reaction between the solvent and polyester segments, and avoiding paint pitting at the source. Simultaneously, it works synergistically with leveling agents to improve wettability during the foaming process, preventing cell agglomeration and rupture. During the foaming process, it migrates to the mold interface to form a "dispersion-leveling-densification-reinforcement" system, which together constructs a thick, tough, and dense outer skin layer and a well-supported outer skin. This effectively blocks solvent penetration, resulting in paint without pitting or pores. The high-strength outer skin also suppresses internal shrinkage stress, thus effectively solving the problems of paint pitting and pores caused by thin outer skin in low-density soles, as well as high-temperature heating shrinkage.
[0104] In Comparative Example 1, without the addition of polyester polyol grafted modified silica to component A, the thickness of the sole surface decreased significantly. After multiple paint sprayings, obvious pitting and a small number of air holes appeared on the surface, and the sole shrank rapidly at high temperatures. Due to the core performance defects, it was judged to be unqualified, proving that modified silica is the key to solving the problems of paint corrosion and shrinkage.
[0105] In Comparative Example 2, no leveling agent was added to component A. After multiple painting processes, obvious pitting and corrosion pores appeared on the surface of the sole. Although the sole did not shrink and the number of folding cycles met the standard, it was judged as a substandard product due to the serious defects in the sole surface. This proves that the synergistic effect of leveling agent and modified silica is crucial to the density of the surface.
[0106] In Comparative Example 3, the amount of polyester polyol grafted with silica was increased to an excessive level. After multiple painting and high-temperature heating, although the sole had no pitting, no air holes and did not shrink, the number of flexural cycles of the sole dropped to 60,000, which means that the service life of the shoe was reduced and could not meet the quality requirements. It was judged as unqualified. This proves that the amount of polyester polyol grafted with modified silica should be controlled within a reasonable range of 2-5 parts. Excessive amount will lead to a decrease in the toughness of the material.
[0107] In summary, the low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer shoe resin prepared using this invention achieves a density of 220-300 kg / m³. 3 Polyurethane soles with a hardness of 48-60C, after multiple spray painting treatments, have no defects, pits, or air holes on the surface of the shoes. They do not shrink after high-temperature heating. The products have excellent comprehensive performance, controllable production costs, and significant competitiveness, making them suitable for industrial promotion and application.
Claims
1. A low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer, characterized in that, It is composed of component A and component B in a mass ratio of 100:(75-85), wherein component A comprises the following raw materials in parts by mass: Polyester polyol P1: 60-90 parts; Polyester polymer polyol P2: 10-40 parts; Polyester polyol grafted with silica: 2-5 parts; Chain extender: 4-8 parts; Leveling agent: 1-3 parts; Foaming agent: 0.5-1 part; Foaming agent: 1-2 parts; Catalyst: 1-2 parts; The sum of the mass fractions of polyester polyol P1 and polyester polymer polyol P2 in component A is 100 parts. Component B is composed of the following raw materials in parts by mass: Polyester polyol P1: 10-20 parts; Polyether polyol: 5-15 parts; Isocyanate: 65-85 parts; The polyester polyol P1 is prepared by alkyd condensation reaction of small molecule polyol and adipic acid, and has a number average molecular weight of 1000-2000 g / mol. The polyester polymer polyol P2 is a basic polyester with a molecular weight of 2000 g / mol obtained by esterification reaction of small molecule polyol and adipic acid, and then obtained by graft copolymerization of the basic polyester with styrene. The polyether polyol is a polyether diol copolymerized from ethylene oxide and propylene oxide, with a number average molecular weight of 4000-5000 g / mol. The foaming agent is water; The leveling agent is a polyether-modified organosilicon compound.
2. The low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer according to claim 1, characterized in that, The preparation method of the polyester polyol grafted modified silica includes the following steps: The product is obtained by reacting polyester polyol with amino-modified silica under the action of a catalyst and heating the mixture to remove water.
3. The low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer according to claim 1, characterized in that, The small molecule polyol is one or more selected from ethylene glycol, diethylene glycol, 1,4-butanediol and trimethylolpropane.
4. The low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer according to claim 1, characterized in that, The chain extender is one or two of ethylene glycol, diethylene glycol, and 1,4-butanediol.
5. The low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer according to claim 1, characterized in that, The foaming agent is a polysiloxane-olefin oxide block copolymer, and the catalyst is an amine catalyst.
6. The low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer according to claim 1, characterized in that, The isocyanate is one or both of 4,4-diphenylmethane diisocyanate and carbodiimide-modified isocyanate.
7. The low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer according to claim 1, characterized in that, The -NCO content of component B is 19-26 wt.%.
8. A method for preparing a low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer according to any one of claims 1 to 7, characterized in that, It is prepared by the following steps: (1) Add polyester polyol P1, polyester polymer polyol P2, polyester polyol grafted modified silica, chain extender, leveling agent, foaming agent, foaming agent and catalyst into a reaction vessel and mix evenly to obtain component A. (2) Add polyester polyol P1 and polyether polyol into the reaction vessel, then add isocyanate, heat and react to obtain component B; (3) Inject components A and B into the material tank of the casting machine, then into the preheated mold. After standing, open the mold to obtain low-density solvent-resistant and shrinkage-resistant polyurethane microporous elastomer.
9. The application of the low-density, solvent-resistant, and shrinkage-resistant polyurethane microporous elastomer according to any one of claims 1 to 7, characterized in that, Specifically, this method is applied to polyurethane shoe sole products: after the microporous elastomer product is molded, it is sprayed with paint, dried and heated to obtain a low-density, solvent-resistant, and shrinkage-resistant polyurethane shoe sole.