Self-reinforced halogen-free flame-retardant polyurethane composite material under wet heat environment and preparation method and application thereof
By compounding silane-terminated modified polyurethane with polyurethane elastomer to form a micro-crosslinked network structure and adding compounded flame retardants, the flame retardancy and hydrolysis resistance problems of polyurethane materials in humid and hot environments are solved, enabling its good application in the cable field.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 宁波聚泰新材料科技有限公司
- Filing Date
- 2023-06-12
- Publication Date
- 2026-07-21
AI Technical Summary
Existing polyurethane materials exhibit poor flame retardancy and hydrolysis resistance in humid and hot environments, leading to a decline in mechanical properties and limiting their application in the cable industry.
Silane-terminated modified polyurethane is compounded with polyurethane elastomer to form a micro-crosslinked interpenetrating network structure, and a small amount of compounded flame retardant is added to achieve a synergistic flame retardant effect.
Maintaining good mechanical and flame-retardant properties in humid and hot environments expands the application range of polyurethane composites, especially in the field of cables.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of polyurethane composite material technology, and relates to a self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments, its preparation method and application. Background Technology
[0002] Currently, the most commonly used material is thermoplastic polyurethane elastomer (TPU), which has good mechanical properties, excellent wear resistance, and maintains good mechanical properties even under high and low temperature environments. However, its high hardness, poor flame retardancy, and poor water resistance limit its application range. In the new national standard GB / T33594-2017 "Cables for Electric Vehicle Charging," the hydrolysis resistance requirement for polyurethane composite cable materials is that they can withstand boiling in water at 80℃ for 168 hours with a change in tensile strength and elongation at break within ±30%. Polyester-type polyurethane is not hydrolyzable, and when used as cable material, carbodiimide-based chain repair agents are often added. However, under long-term exposure to hot water, polyester-type polyurethane will still rapidly degrade as the chain repair agents are consumed. Polyether-type polyurethane has good hydrolysis resistance, but when used in cables, it often requires the addition of large amounts of flame retardants. The interface created by the flame retardant accelerates the penetration of moisture into the polyurethane, causing the polyurethane material to soften. Simultaneously, moisture replaces the hydrogen bonds within and between polyurethane molecules, weakening the microphase separation of the polyurethane and significantly reducing its mechanical properties. Summary of the Invention
[0003] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments. This material maintains good mechanical properties in humid and hot environments and achieves flame retardancy with a small amount of flame retardant, thus expanding the application of polyurethane composite materials.
[0004] The objective of this invention can be achieved through the following technical solutions:
[0005] A self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments, the components of which, by weight, include:
[0006] 70-90 parts polyurethane elastomer, 10-30 parts silane-terminated modified polyurethane, 15-30 parts compounded high-efficiency flame retardant, 0.5-2 parts lubricant, and 0.5-2 parts antioxidant.
[0007] Existing polyurethane materials typically require the addition of large amounts of flame retardants to achieve flame retardancy. However, the addition of large amounts of flame retardants leads to softening of the polyurethane material in humid and hot environments, reducing the hydrolysis resistance of polyether-type polyurethane and significantly decreasing its mechanical properties. In contrast, the raw material system of this invention uses a silane-terminated modified polyurethane and a polyurethane elastomer as the matrix. The alkoxy groups in the system gradually crosslink and solidify in a high-temperature and high-humidity environment, forming a micro-crosslinked interpenetrating network structure. This compensates for the reduction in mechanical properties caused by the softening of polyurethane by water and the disruption of intermolecular hydrogen bonds by water. In this system, only a small amount of flame retardant is needed to meet the flame retardant performance requirements and improve the reduction in mechanical property retention caused by the addition of flame retardants. This allows the polyurethane composite material to meet flame retardant performance requirements while also possessing good mechanical properties.
[0008] Preferably, the amount of silane-modified polyurethane added to the raw material system is 5-20%.
[0009] As a preferred option, the amount of compound high-efficiency flame retardant added to the raw material system is 10-20%.
[0010] Further preferably, the mass ratio of the silane-modified polyurethane to the compounded high-efficiency flame retardant is (0.5-1.2):1.
[0011] Preferably, silane-modified polyurethane is prepared by modifying isocyanate-terminated polyurethane prepolymer with a silane modifier.
[0012] Isocyanate-terminated polyurethane prepolymers are intermediate reactants in the synthesis of silane-terminated polyurethanes. Isocyanates are highly reactive and can react with amino-containing silane coupling agents. Compared with other reactions, this reaction process is simple and the raw material cost is low.
[0013] Further preferred, the molar ratio of silane modifier to isocyanate-terminated polyurethane prepolymer is (1.01-1.2):1.
[0014] Preferably, the isocyanate-terminated polyurethane prepolymer is obtained by heating and mixing polyether polyol with diisocyanate.
[0015] Further preferred, the ratio of NCO / OH in the polyether polyol and diisocyanate is (1.1-1.8):1.
[0016] Further optimization involves heating at a temperature of 60–80°C for 1–8 hours.
[0017] Preferably, the silane modifier is one or more of amino-containing silane coupling agents such as KH550, KH792, and KH-602.
[0018] Preferably, the polyether polyol has a molecular weight of 1000-8000; the diisocyanate is one or more of MDI, TDI, and HDI.
[0019] As a preferred option, the high-efficiency compound flame retardant is aluminum diethylphosphonate (ADP), piperazine pyrophosphate (PAPP), and melamine cyanurate (MCA) in a mass ratio of (2-6):(1-3):1.
[0020] Preferably, the polyurethane resin is a polyether-type polyurethane elastomer.
[0021] Preferably, the lubricant is a low-molecular-weight wax or a silicone powder dispersant.
[0022] Preferably, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168, and / or a mixture of antioxidant 1076 and antioxidant 168.
[0023] This invention also discloses a method for preparing a self-reinforced halogen-free flame-retardant polyurethane composite material under humid and hot conditions, the preparation method comprising:
[0024] S1. Preparation of silane-modified polyurethane: After heating and mixing polyether polyol and diisocyanate, silane modifier is added dropwise until there are no isocyanate ions in the system, and the product is obtained.
[0025] S2. After mixing all the raw materials, feed them into a twin-screw extruder. After extrusion, granulation, and drying, the composite material is obtained.
[0026] Preferably, in step S1, the content of isocyanate in the isocyanate-terminated polyurethane prepolymer is determined by di-n-butylamine back titration.
[0027] Further optimization is achieved by setting the temperature of the twin-screw compounding extruder to 180–210°C.
[0028] This invention also discloses the application of self-reinforced halogen-free flame-retardant polyurethane composite materials in the field of cables under humid and hot conditions.
[0029] Preferably, the mechanical properties of the composite material under humid and hot conditions are 80 to 105% of those under normal temperature conditions.
[0030] Compared with the prior art, the present invention has the following beneficial effects:
[0031] 1. This invention uses silane-terminated modified polyurethane blended with polyurethane as the resin system matrix. In the system, the alkoxy groups on the silane-terminated polyurethane end groups gradually crosslink and solidify in a high temperature and high humidity environment, forming a micro-crosslinked interpenetrating network structure. This compensates for the reduction in mechanical properties caused by the softening of polyurethane by water and the destruction of hydrogen bonds between polyurethane molecules by water. In other words, a humid and hot environment can provide good conditions for the crosslinking and curing of silane, so that the polyurethane composite material can maintain good mechanical properties in a humid and hot environment.
[0032] 2. The addition of silane-modified polyurethane to the self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments in this invention can also improve the flexibility of the polyurethane composite material, making up for the problem of high hardness and poor flexibility of polyurethane material as a cable material.
[0033] 3. The flame retardant added to the self-reinforced halogen-free flame-retardant polyurethane composite material in the humid and hot environment of the present invention is a flame retardant compounded with piperazine pyrophosphate, aluminum diethylphosphite and melamine cyanurate. The three have a good synergistic flame retardant effect. With a small total addition amount, the flame retardant performance can pass the GB / T2408 V-0 vertical burning test.
[0034] 4. In the self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments of the present invention, a small amount of compound flame retardant is added to the polyurethane elastomer and silane-modified polyurethane compound system, so that the polyurethane composite material has good mechanical properties while meeting the flame retardant performance requirements.
[0035] 5. The self-reinforced halogen-free flame-retardant polyurethane composite material of the present invention has good environmental adaptability when applied in the field of cables under humid and hot conditions, effectively expanding the application range. Detailed Implementation
[0036] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.
[0037] Unless otherwise specified, the raw materials used in this invention are all commercially available products, and the methods used are all technical means well known to those skilled in the art.
[0038] The preparation method of silane-modified polyurethane of the present invention includes:
[0039] (1) Under N2 protection, polyether polyol and diisocyanate are heated and mixed, and the ratio of NCO / OH added is (1.1~1.8):1. Stir until the hydroxyl groups are completely reacted.
[0040] (2) Add silane modifier dropwise to the above mixture, determine the isocyanate content in the isocyanate-terminated polyurethane prepolymer by di-n-butylamine back titration, stir until there is no isocyanate in the system, and obtain silane-modified polyurethane.
[0041] The raw materials of the self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments of the present invention include: 70-90 parts of polyurethane elastomer, 10-30 parts of silane-modified polyurethane, 15-30 parts of compounded high-efficiency flame retardant, 0.5-2 parts of lubricant, and 0.5-2 parts of antioxidant.
[0042] The raw materials are mixed and fed into a twin-screw extruder. After extrusion, granulation, and drying, a composite material is obtained.
[0043] The polyurethane resin is a polyether-type polyurethane elastomer;
[0044] The lubricant is a low-molecular-weight wax and a silicone powder dispersant;
[0045] The antioxidant is a mixture of antioxidant 1010 and antioxidant 168, and / or a mixture of antioxidant 1076 and antioxidant 168;
[0046] The high-efficiency compound flame retardant is aluminum diethylphosphonate (ADP), piperazine pyrophosphate (PAPP), and melamine cyanurate (MCA) in a mass ratio of (2-6):(1-3):1.
[0047] The molecular weight of polyether polyols is 1000-8000;
[0048] Diisocyanate is one or more of MDI, TDI, and HDI.
[0049] The silane modifier is one or more of the amino-containing silane coupling agents such as KH550, KH792, and KH-602.
[0050] Example 1
[0051] Preparation of silane-modified polyurethane in this embodiment:
[0052] (1) The polyether polyol (PTMEG, molecular weight 3000) was dried under reduced pressure at 110℃ for 3 hours to remove moisture, and then cooled to the reaction temperature (80℃); diisocyanate (MDI) was added, and the mixture was stirred at 80℃ for 3 hours under N2 protection. The ratio of NCO / OH added was 1.5:1; polyurethane prepolymer with isocyanate end-capping was synthesized.
[0053] (2) Add silane modifier KH550 dropwise to the above mixture. The molar ratio of KH550 to isocyanate in the mixture is 1:1.05. After the addition is completed, stir the mixture at room temperature for 3 hours. The content of isocyanate in the isocyanate-terminated polyurethane prepolymer is determined by di-n-butylamine back titration. The reaction is carried out until there is no isocyanate in the system, and silane-modified polyurethane is obtained.
[0054] The raw materials for the self-reinforced halogen-free flame-retardant polyurethane composite material in this embodiment under humid and hot conditions include: 80 parts polyurethane elastomer, 20 parts silane-modified polyurethane, 22 parts compounded high-efficiency flame retardant (12 parts ADP, 7 parts PAPP, 3 parts MCA), 1.5 parts lubricant (polyethylene wax), and 1.5 parts antioxidant (1 part antioxidant 1010, 0.5 parts antioxidant 168).
[0055] The raw materials are mixed at low speed at 110℃ for 5 minutes, then fed into a twin-screw extruder. After extrusion, granulation, and drying, the composite material is obtained. The temperature zones 1 to 10 of the twin-screw extruder are set as follows: 150℃, 160℃, 165℃, 175℃, 185℃, 185℃, 185℃, 180℃, 175℃, 170℃.
[0056] The properties of the self-reinforced halogen-free flame-retardant polyurethane composite material prepared under humid and hot conditions are shown in Table 1.
[0057] Example 2
[0058] Compared with Example 1, the difference lies in the raw materials of the self-reinforced halogen-free flame-retardant polyurethane composite material under humid and hot conditions in this example, which include:
[0059] 78 parts polyurethane elastomer, 23 parts silane-modified polyurethane, 20 parts compounded high-efficiency flame retardant (10 parts ADP, 6 parts PAPP, 4 parts MCA), 1 part lubricant (polyethylene wax), 2 parts antioxidant (1 part antioxidant 1076, 1 part antioxidant 168).
[0060] The properties of the self-reinforced halogen-free flame-retardant polyurethane composite material prepared under humid and hot conditions are shown in Table 1.
[0061] Example 3
[0062] Compared with Example 1, the difference lies in the raw materials of the self-reinforced halogen-free flame-retardant polyurethane composite material under humid and hot conditions in this example, which include:
[0063] 90 parts polyurethane elastomer, 10 parts silane-modified polyurethane, 22 parts compounded high-efficiency flame retardant (12 parts ADP, 7 parts PAPP, 3 parts MCA), 1.5 parts lubricant (polyethylene wax), 1.5 parts antioxidant (1 part antioxidant 1010, 0.5 parts antioxidant 168).
[0064] The properties of the self-reinforced halogen-free flame-retardant polyurethane composite material prepared under humid and hot conditions are shown in Table 1.
[0065] Example 4
[0066] Compared with Example 1, the difference lies in the raw materials of the self-reinforced halogen-free flame-retardant polyurethane composite material under humid and hot conditions in this example, which include:
[0067] 70 parts polyurethane elastomer, 30 parts silane-modified polyurethane, 22 parts compounded high-efficiency flame retardant (12 parts ADP, 7 parts PAPP, 3 parts MCA), 1.5 parts lubricant (polyethylene wax), 1.5 parts antioxidant (1 part antioxidant 1010, 0.5 parts antioxidant 168).
[0068] The properties of the self-reinforced halogen-free flame-retardant polyurethane composite material prepared under humid and hot conditions are shown in Table 1.
[0069] Example 5
[0070] Compared with Example 1, the difference lies in the raw materials of the self-reinforced halogen-free flame-retardant polyurethane composite material under humid and hot conditions in this example, which include:
[0071] 95 parts polyurethane elastomer, 5 parts silane-modified polyurethane, 22 parts compounded high-efficiency flame retardant (12 parts ADP, 7 parts PAPP, 3 parts MCA), 1.5 parts lubricant (polyethylene wax), 1.5 parts antioxidant (1 part antioxidant 1010, 0.5 parts antioxidant 168).
[0072] The properties of the self-reinforced halogen-free flame-retardant polyurethane composite material prepared under humid and hot conditions are shown in Table 1.
[0073] Example 6
[0074] The difference compared to Example 1 is that the NCO / OH feed ratio is 2:1 in the preparation of silane-modified polyurethane.
[0075] Example 7
[0076] Compared with Example 1, the difference is that the NCO / OH feed ratio is 1.1:1 in the preparation of silane-modified polyurethane.
[0077] Example 8
[0078] The difference from Example 1 is that the molecular weight of the polyether diol PTMEG in the preparation of silane-modified polyurethane is 5000.
[0079] Comparative Example 1
[0080] Compared with Example 1, the difference is that silane-modified polyurethane is not added, while the proportions of the remaining components in the system remain unchanged.
[0081] The properties of the obtained polyurethane composite material are shown in Table 1.
[0082] Comparative Example 2
[0083] The difference from Example 1 is that the flame retardant is only ADP.
[0084] The properties of the obtained polyurethane composite material are shown in Table 1.
[0085] Comparative Example 3
[0086] Compared with Example 1, the difference is that no flame retardant is added, while the proportions of the remaining components in the system remain unchanged.
[0087] Table 1. Performance of Polyurethane Composites
[0088]
[0089] As shown in the table above, the self-reinforced halogen-free flame-retardant polyurethane composite material of the present invention has good mechanical properties and flame-retardant properties under humid and hot conditions. Furthermore, it can retain 80-105% of its mechanical properties under humid and hot conditions, which makes the material have a good service life when used in the cable field and can adapt to more scenarios.
[0090] In Example 4, the content of silane-modified polyurethane was too high (24%). Since the molecular weight of silane-modified polyurethane is relatively low compared to commercial polyurethane, the mechanical properties decreased. At the same time, due to the relatively small molecular weight, molten droplets were present in the vertical burning test, resulting in the vertical burning performance only reaching V-2. In Example 5, the content of silane-modified polyurethane was too low (4%), which prevented the silane-modified polyurethane from crosslinking in the system to form a cured network, resulting in a decrease in mechanical properties after hygrothermal aging.
[0091] In Example 6, the NCO / OH feed ratio in the preparation of silane-modified polyurethane was 2:1. The synthesized low molecular weight silane-modified polyurethane under humid and hot conditions underwent hydrolysis and cross-linking of the terminal alkoxy groups to form a network, which reinforced the mechanical properties caused by the destruction of polyurethane hydrogen bonds by moisture. If the NCO / OH feed ratio continued to increase, the isocyanate content gradually increased, and the diisocyanate ester existed in the system in the form of small molecules, playing a plasticizing effect and further reducing the mechanical properties. In Example 7, the NCO / OH feed ratio was 1.1:1, which led to an increase in the reaction time of the preparation process, but the performance change was not obvious.
[0092] In Comparative Example 1, the lack of silane-modified polyurethane softening and disruption of inter-polyurethane hydrogen bonds resulted in a significant decrease in mechanical properties due to the absence of silane crosslinking reinforcement. In Comparative Example 2, no compounded flame retardant was added; only ADP was used as the flame retardant, achieving a flame retardant effect of only V-2, with a slight decrease in mechanical properties. To achieve a V-0 flame retardant effect, more ADP would need to be added, which would have a significant impact on mechanical properties. In Comparative Example 3, no flame retardant was added, reducing the presence of interfaces in the system and decreasing the channels for moisture penetration, thus improving mechanical properties after hygrothermal aging. However, the highly efficient flame retardant performance required by this invention could not be achieved.
[0093] In summary, this invention uses silane-modified polyurethane blended with polyurethane as the resin system matrix. The alkoxy groups in the system gradually crosslink and solidify in a high-temperature and high-humidity environment, forming a micro-crosslinked interpenetrating network structure. This compensates for the reduced mechanical properties caused by the softening of polyurethane by water and the disruption of intermolecular hydrogen bonds by water. Furthermore, only a small amount of compounded flame retardant needs to be added to the system of this invention, so that the polyurethane composite material can meet the flame retardant performance while avoiding the impact of hydrolysis on mechanical properties.
[0094] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.
Claims
1. A self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments, characterized in that, The components of this composite material, by weight, include: 70-90 parts polyurethane elastomer, 10-30 parts silane-modified polyurethane, 15-30 parts compounded high-efficiency flame retardant, 0.5-2 parts lubricant, 0.5-2 parts antioxidant; The high-efficiency compound flame retardant is aluminum diethylphosphonate, piperazine pyrophosphate, and melamine cyanurate in a mass ratio of (2~6):(1~3):
1. The silane-modified polyurethane is prepared by modifying isocyanate-terminated polyurethane prepolymer with a silane modifier; the molar ratio of the two is (1.01~1.2):
1. The silane modifier is an amino-containing silane coupling agent.
2. The self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments according to claim 1, characterized in that, The amount of silane-modified polyurethane added to the raw material system is 5-20%.
3. The self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments according to claim 1, characterized in that, The amount of compound high-efficiency flame retardant added to the raw material system is 10-20%.
4. The self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments according to claim 1, characterized in that, The isocyanate-terminated polyurethane prepolymer is obtained by heating and mixing polyether polyol with diisocyanate.
5. The self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments according to claim 4, characterized in that, The NCO / OH ratio in polyether polyols and diisocyanates is (1.1~1.8):
1.
6. The self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments according to claim 5, characterized in that, The molecular weight of the polyether polyol is 1000~8000; the diisocyanate is one or more of MDI, TDI and HDI.
7. A method for preparing a self-reinforced halogen-free flame-retardant polyurethane composite material under humid and hot conditions as described in claim 1, characterized in that, Preparation methods include: S1. Preparation of silane-modified polyurethane: After heating and mixing polyether polyol and diisocyanate, silane modifier is added dropwise until there are no isocyanate ions in the system, and the product is obtained. S2. After mixing all the raw materials, feed them into a twin-screw extruder. After extrusion, granulation, and drying, the composite material is obtained.
8. The application of a self-reinforced halogen-free flame-retardant polyurethane composite material for humid and hot environments as described in claim 1 in the field of cables.