Composition for preparing polyurethane elastomer, preparation method and polyurethane elastomer

Abstract

The invention provides a composition for preparing a polyurethane elastomer, a preparation method of the composition and the polyurethane elastomer. The composition comprises the following components in percentage by mass: 65-75% of the polyurethane elastomer; 10%-20% of metal ion modified piperazine polyphosphate; 3%-7% of a phosphorus-based synergistic flame retardant; 1%-5% of a nanofiller; 0.5%-1.5% of a surface treating agent; 0.5%-1.5% of an ultraviolet light absorber; and 0.5%-1.5% of a light stabilizer. The preparation method comprises the following steps: drying 65%-75% of polyurethane elastomer at 100-110 DEG C for 3-5 hours to remove moisture, and then adding the dried polyurethane elastomer, 10%-20% of metal ion modified piperazine polyphosphate, 3%-7% of phosphorus synergistic flame retardant, 1%-5% of nano filler, 0.5%-1.5% of surface treating agent, 0.5%-1.5% of ultraviolet light absorber and 0.5%-1.5% of light stabilizer into a high-speed stirrer for uniform mixing. And adding the uniformly mixed material into a twin-screw extruder, setting the temperature at 140-200 DEG C, and carrying out underwater pelletizing to obtain the ultraviolet-yellowing-resistant halogen-free flame-retardant polyurethane elastomer material.

Description

Technical Field

[0001] This invention relates to the field of halogen-free flame-retardant polyurethane elastomer technology, specifically to a composition, preparation method, and halogen-free flame-retardant polyurethane elastomer resistant to ultraviolet yellowing. Background Technology

[0002] Polyurethane (TPU) is an important polymer material widely used in industry and daily life, possessing excellent elasticity, abrasion resistance, and chemical corrosion resistance. It is widely used in wires and cables, footwear materials, furniture, and other fields. However, during long-term use, especially outdoors, polyurethane materials are susceptible to ultraviolet (UV) radiation, which causes changes in the molecular structure, leading to yellowing of the material surface and severely affecting its lifespan and aesthetics. Furthermore, as an organic polymer, polyurethane is easily ignited and burns rapidly when exposed to a fire source, posing a certain safety hazard. Therefore, flame retardants need to be added to improve its flame-retardant properties and reduce the risk of fire, especially in applications requiring flame retardancy, such as cables and building materials, where the flammability of polyurethane is a significant concern.

[0003] To address the two issues mentioned above, several improvement methods exist in the market. For example, adding UV absorbers and light stabilizers can improve the UV resistance of polyurethane and reduce yellowing; simultaneously, adding flame retardants can improve its flame retardancy and reduce fire risk. Chinese patent CN 104725833A discloses a yellowing-resistant halogen-free flame-retardant thermoplastic polyurethane elastomer cable compound, which adds anti-yellowing agents and flame retardants to polyether-type polyurethane elastomers, giving the material good yellowing resistance and flame retardancy. Chinese patent CN113234315B discloses a flame-retardant and yellowing-resistant TPU cable material, its preparation method, and its application, which adds a large amount of metal oxides and phosphate esters as anti-yellowing agents and flame retardants, resulting in a TPU cable material with good flame retardancy and yellowing resistance. Chinese patent CN101977995A discloses a polyurethane formulation agent, including halogenated flame retardants and antimony oxides, which can impart highly efficient flame retardancy to polyurethane materials. However, these methods have some limitations. For example, the addition of large amounts of additives can affect the mechanical properties of the product; halogenated flame retardants produce a large amount of toxic substances during combustion, polluting the environment; and the difference in the types of polyurethane raw materials has a significant impact on the product's resistance to yellowing. Polyurethanes with MDI as the hard segment contain a large number of benzene ring structures, which are prone to photo-oxidation under ultraviolet (UV) irradiation. The conjugated system on the benzene ring absorbs ultraviolet light, leading to molecular chain breakage or the formation of quinones, which are usually colored (yellow or brown), thus causing yellowing. These factors limit the promotion of related polyurethane products in practical applications. Summary of the Invention

[0004] The purpose of this invention is to solve at least one of the problems mentioned in the background art above, and to provide a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material. This invention also provides a method for preparing the above material.

[0005] To achieve at least one of the above objectives, the present invention provides a composition for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following components by mass percentage:

[0006] Polyurethane elastomer 65%~75%;

[0007] Metal ion modified piperazine polyphosphate 10%~20%;

[0008] Phosphorus-based synergistic flame retardants: 3%~7%;

[0009] Nanofillers 1%~5%;

[0010] Surface treatment agent 0.5%~1.5%;

[0011] Ultraviolet absorber 0.5%~1.5%;

[0012] Light stabilizer 0.5%~1.5%.

[0013] Optionally, the polyurethane elastomer includes one or more combinations of aliphatic polyether type polyurethane elastomer or polyester type polyurethane elastomer. Further, the hard segment in the polyurethane elastomer used is hexamethylene diisocyanate (HDI) or isophorone diisocyanate (IPDI).

[0014] Optionally, the polyurethane elastomer has a Shore hardness of 70 A to 90 A, an elongation at break of ≥500%, and a tensile strength of ≥30 MPa, or even ≥40 MPa.

[0015] Optionally, the preparation method of metal ion modified piperazine polyphosphate is as follows: piperazine and polyphosphoric acid are mixed, and then a metal oxide is added. The mixture is heated to carry out a dehydration condensation reaction to obtain metal ion modified piperazine polyphosphate. For detailed preparation process, please refer to patent CN112898231B (A preparation method of metal ion modified piperazine polyphosphate and its application).

[0016] Optionally, the metal ion-modified piperazine polyphosphate is the polymer described in formula (I):

[0017] (I) Wherein, n is the average degree of polymerization, n is 2~4, M is selected from Mg, Ca, Al, Zn, Fe, Ba, Cu; x corresponds to the valence state of metal ion M, selected from 1, 2 or 3; the molar ratio of phosphorus atoms, piperazine and metal ions in the metal ion modified polyphosphate piperazine is (2~3):1:(0.05~0.1).

[0018] Optionally, the phosphorus-based synergistic flame retardant includes one or more combinations of melamine polyphosphate (MPP), aluminum diethylphosphite (ADP), melamine cyanurate (MC), triphenyl phosphate, and triphenylphosphine oxide. For example, it can be a combination of triphenyl phosphate and triphenylphosphine oxide.

[0019] Optionally, the nanofiller includes one or more combinations of titanium dioxide, zinc oxide, and cerium oxide. Further, the diameter of the nanofiller used is between 20 nm and 200 nm. For example, it can be a combination of titanium dioxide and zinc oxide, or a combination of zinc oxide and cerium oxide.

[0020] Optionally, the surface treatment agent includes one or more combinations of γ-glycidoxypropyltrimethoxysilane (KH-560), isopropyltris(isostearoyl)titanate (KR-TTS), or (3,4-epoxycyclohexyl)-ethyltriethoxysilane (KH-1770).

[0021] Optionally, the UV absorber is one or a combination of Chimassorb® 81, Tinuvin® 326, Tinuvin® 328 or Tinuvin® 1600.

[0022] Optionally, the light stabilizer is a hindered amine light stabilizer, such as one or more combinations of UV-123, UV-292, UV-622 or UV-770.

[0023] This invention also provides a method for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following steps:

[0024] S1: Remove moisture by drying 65%~75% polyurethane elastomer at 100℃~110℃ for 3h~5h.

[0025] S2: Then, it is mixed with 10%~20% metal ion modified polyphosphate piperazine, 3%~7% phosphorus-based synergistic flame retardant, 1%~5% nanofiller, 0.5%~1.5% surface treatment agent, 0.5%~1.5% ultraviolet absorber and 0.5%~1.5% light stabilizer in a high-speed mixer until homogeneous.

[0026] S3: Add the mixed material to a twin-screw extruder, set the temperature to 140℃~200℃, and pelletize underwater to obtain a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material.

[0027] The present invention also provides a UV-resistant, halogen-free, flame-retardant polyurethane elastomer prepared by the above preparation method.

[0028] This UV-resistant, halogen-free, flame-retardant polyurethane elastomer exhibits excellent UV resistance and flame retardancy. After 240 hours of xenon lamp testing, ΔE < 3 and oxygen index > 28. It passed the VW-1 test and achieved a UL 94-V0 flame retardancy rating of 3.0 mm. At the same time, it maintains the excellent mechanical properties of polyurethane materials, with tensile strength ≥ 20 MPa and elongation at break ≥ 400%.

[0029] Compared with existing technologies, the advantages of this invention are as follows: Compared with traditional flame-retardant polyurethane materials, the metal ion-modified piperazine polyphosphate and synergistic flame retardant added to the product of this invention have advantages such as low smoke, low toxicity, and environmental friendliness. At the same time, suitable nanofillers are added. On the one hand, there is a flame-retardant synergistic effect between the selected halogen-free flame retardant and the nanofiller, which increases the density and stability of the char layer and makes up for the defect of insufficient char formation caused by the decrease in benzene ring content in aliphatic polyurethane matrix, thereby improving the flame-retardant efficiency of the material. It can impart good flame retardancy to the material with a low amount of flame retardant added. On the other hand, the added nanofiller has good interfacial scattering ability and can act as an ultraviolet shielding agent. It also works synergistically with the anti-ultraviolet agent to further improve the product's resistance to ultraviolet yellowing. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in further detail below with reference to examples. These examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0031] In this invention, unless otherwise specified, all equipment and raw materials are available from the market or commonly used in the industry. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0032] Example 1

[0033] A composition or formulation for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following components in parts by weight: 75% polyether-type polyurethane elastomer (HDI hard segment), 15% metal ion-modified piperazine polyphosphate, 5% melamine polyphosphate (MPP), 2% titanium dioxide, 1% KH-560, 1% Chimassorb® 81, and 1% UV-292.

[0034] The first step is to thoroughly dry the polyether-type polyurethane elastomer in a 105℃ oven for 5 hours to remove moisture. Then, the materials in the above composition are added to a high-speed mixer in proportion and mixed evenly. The mixed material is then fed into a twin-screw extruder, and the temperature is set at 140℃~200℃. After underwater pelletizing, a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material is obtained.

[0035] Example 2

[0036] A composition or formulation for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following components in parts by weight: 70% polyether-type polyurethane elastomer (hard segment is IPDI), 17% metal ion-modified piperazine polyphosphate, 3% triphenyl phosphate, 2% triphenylphosphine oxide, 3% titanium dioxide, 2% zinc oxide, 1% KR-TTS, 1% Tinuvin® 326, and 1% UV-123.

[0037] The first step is to thoroughly dry the polyether-type polyurethane elastomer in a 110℃ oven for 3 hours to remove moisture. Then, the materials in the above composition are added to a high-speed mixer in proportion and mixed evenly. The mixed material is then fed into a twin-screw extruder, and the temperature is set at 140℃~200℃. After underwater pelletizing, a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material is obtained.

[0038] Example 3

[0039] A composition or formulation for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following components in parts by weight: 67% polyester-type polyurethane elastomer (HDI hard segment), 20% metal ion-modified piperazine polyphosphate, 7% melamine cyanurate (MC), 3% cerium oxide, 1% KH-1770, 1% Tinuvin® 328, and 1% UV-622.

[0040] The first step is to thoroughly dry the polyester-type polyurethane elastomer in a 105℃ oven for 4 hours to remove moisture. Then, the materials in the above composition are added to a high-speed mixer in proportion and mixed evenly. The mixed material is then fed into a twin-screw extruder, and the temperature is set at 140℃~200℃. After underwater pelletizing, a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material is obtained.

[0041] Example 4

[0042] A composition or formulation for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following components in parts by weight: polyester-type polyurethane elastomer (HDI hard segment) 73%, metal ion-modified piperazine polyphosphate 17%, aluminum diethylphosphite (ADP) 3%, cerium oxide 2%, zinc oxide 2%, KH-560 1%, Tinuvin® 1600 1.5%, and UV-770 0.5%.

[0043] The first step is to thoroughly dry the polyester-type polyurethane elastomer in a 105℃ oven for 4 hours to remove moisture. Then, the materials in the above composition are added to a high-speed mixer in proportion and mixed evenly. The mixed material is then fed into a twin-screw extruder, and the temperature is set at 140℃~200℃. After underwater pelletizing, a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material is obtained.

[0044] Comparative Example 1

[0045] A composition or formulation for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following components in parts by weight: 75% polyether-type polyurethane elastomer (hard segment is IPDI), 17% metal ion-modified piperazine polyphosphate, 3% triphenyl phosphate, 2% triphenylphosphine oxide, 1% KR-TTS, 1% Tinuvin® 326, and 1% UV-123.

[0046] The first step is to thoroughly dry the polyether-type polyurethane elastomer in a 110℃ oven for 3 hours to remove moisture. Then, the materials in the above composition are added to a high-speed mixer in proportion and mixed evenly. The mixed material is then fed into a twin-screw extruder, and the temperature is set at 140℃~200℃. After underwater pelletizing, a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material is obtained.

[0047] Comparative Example 2

[0048] A composition or formulation for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following components in parts by weight: 75% polyether-type polyurethane elastomer (HDI hard segment), 20% metal ion-modified piperazine polyphosphate, 2% titanium dioxide, 1% KH-560, 1% Chimassorb® 81, and 1% UV-292.

[0049] The first step is to thoroughly dry the polyether-type polyurethane elastomer in a 105℃ oven for 5 hours to remove moisture. Then, the materials in the above composition are added to a high-speed mixer in proportion and mixed evenly. The mixed material is then fed into a twin-screw extruder, and the temperature is set at 140℃~200℃. After underwater pelletizing, a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material is obtained.

[0050] Comparative Example 3

[0051] A composition or formulation for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following components in parts by weight: 75% polyether-type polyurethane elastomer (HDI hard segment), 20% melamine polyphosphate (MPP), 2% titanium dioxide, 1% KH-560, 1% Chimassorb® 81, and 1% UV-292.

[0052] The first step is to thoroughly dry the polyether-type polyurethane elastomer in a 105℃ oven for 5 hours to remove moisture. Then, the materials in the above composition are added to a high-speed mixer in proportion and mixed evenly. The mixed material is then fed into a twin-screw extruder, and the temperature is set at 140℃~200℃. After underwater pelletizing, a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material is obtained.

[0053] Comparative Example 4

[0054] A composition or formulation for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, comprising the following components in parts by weight: 75% polyether-type polyurethane elastomer (HDI hard segment), 15% piperazine polyphosphate, 5% melamine polyphosphate (MPP), 2% titanium dioxide, 1% KH-560, 1% Chimassorb® 81, and 1% UV-292.

[0055] The first step is to thoroughly dry the polyether-type polyurethane elastomer in a 105℃ oven for 5 hours to remove moisture. Then, the materials in the above composition are added to a high-speed mixer in proportion and mixed evenly. The mixed material is then fed into a twin-screw extruder, and the temperature is set at 140℃~200℃. After underwater pelletizing, a UV-resistant, halogen-free, flame-retardant polyurethane elastomer material is obtained.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Other modified bodies and technical formulations may be developed without departing from the technical solutions described in the claims.

[0057] The materials prepared in Examples 1-4 and Comparative Examples 1-4 were subjected to performance tests. Mechanical properties were tested according to the method in GB / T 528-2009, oxygen index was tested according to the method in GB / T 2406-2009, flame retardancy was tested according to the method specified in UL94, flame resistance was tested according to the method specified in UL1581 after the material was extruded into a single-core cable sheath, and UV resistance was tested according to the method specified in GB / T 16422-2014. The relevant physical properties are shown in Table 1 below.

[0058] Table 1 Performance of each embodiment and comparative example

[0059]

[0060] The performance results of the above examples and comparative examples demonstrate that the polyurethane elastomer prepared using the present invention not only exhibits excellent flame retardant properties and UV yellowing resistance, but also retains the high mechanical properties of TPU. Examples 1-4 each have their own focus, and the optimal solution can be selected based on mechanical properties, oxygen index, UV yellowing resistance, etc. As can be seen from Comparative Examples 1 and 2, the addition of nanofillers helps improve flame retardancy and UV yellowing resistance. On the one hand, they can synergistically interact with phosphorus-based flame retardants to form a dense physical barrier, improving the stability of the char layer and thus reducing the combustion rate and improving flame retardancy. On the other hand, the small particle size and mesoporous structure of the nanoparticles give them good interfacial scattering properties, allowing them to scatter ultraviolet light in all directions. They can also utilize the semiconductor band structure to convert ultraviolet photon energy into heat energy, greatly reducing the intensity of ultraviolet light and thus reducing the damage to the material from ultraviolet light. As can be seen from Comparative Examples 1 and 4, the metal ion-modified polypiperazine phosphate exhibits better self-extinguishing combustion and anti-dripping effects in this formulation system compared to ordinary piperazine pyrophosphate, which helps the material pass the VW-1 and V0 tests.

[0061] Although the present invention has been disclosed above by way of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of protection claimed in the claims.

Claims

1. A composition for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer, characterized in that, Included by mass percentage: Polyurethane elastomer 65%~75%; Metal ion modified piperazine polyphosphate 10%~20%; Phosphorus-based synergistic flame retardants: 3%~7%; Nanofillers 1%~5%; Surface treatment agent 0.5%~1.5%; Ultraviolet absorber 0.5%~1.5%; Light stabilizer 0.5%~1.5%.

2. The composition according to claim 1, characterized in that, The polyurethane elastomer includes one or more combinations of polyether-type polyurethane elastomers or polyester-type polyurethane elastomers, wherein the hard segment in the polyurethane elastomer is hexamethylene diisocyanate or isophorone diisocyanate.

3. The composition according to claim 1, characterized in that, The phosphorus-based synergistic flame retardant is selected from any one or more combinations of melamine polyphosphate, aluminum diethylphosphite, melamine cyanurate, triphenyl phosphate, and triphenylphosphine oxide.

4. The composition according to claim 1, characterized in that, The nanofiller is selected from one or more combinations of titanium dioxide, zinc oxide, and cerium oxide, and the diameter of the nanofiller ranges from 20 nm to 200 nm.

5. The composition according to claim 1, characterized in that, The surface treatment agent is selected from one or more combinations of γ-glycidoxypropyltrimethoxysilane, isopropyltris(isostearoyl)titanate, or (3,4-epoxycyclohexyl)-ethyltriethoxysilane; the ultraviolet absorber is selected from one or more combinations of Chimassorb® 81, Tinuvin® 326, Tinuvin® 328, or Tinuvin® 1600; the light stabilizer includes a hindered amine light stabilizer, which is selected from one or more of UV-123, UV-292, UV-622, or UV-770.

6. The composition according to claim 1, characterized in that, The metal ion-modified piperazine polyphosphate is the polymer described in formula (I): (I), where n is the average degree of polymerization, n is 2~4, M is selected from Mg, Ca, Al, Zn, Fe, Ba, Cu; x corresponds to the valence state of metal ion M, selected from 1, 2 or 3; the molar ratio of phosphorus atoms, piperazine and metal ions in the metal ion modified polyphosphate piperazine is (2~3):1:( 0.05~0.1).

7. The composition according to claim 4, characterized in that, The nanofiller is a combination of titanium dioxide and zinc oxide, or a combination of zinc oxide and cerium oxide.

8. A method for preparing a UV-resistant, halogen-free, flame-retardant polyurethane elastomer as described in any one of claims 1-7, characterized in that, include: S1: Dry 65%~75% of the polyurethane elastomer at 100℃~110℃ for 3h~5h to remove moisture; S2: Add the dried polyurethane elastomer, 10%~20% metal ion modified polyphosphate piperazine, 3%~7% phosphorus-based synergistic flame retardant, 1%~5% nanofiller, 0.5%~1.5% surface treatment agent, 0.5%~1.5% ultraviolet absorber and 0.5%~1.5% light stabilizer into a mixer and mix evenly; S3: Add the mixed material to a twin-screw extruder, set the temperature to 140℃~200℃, and pelletize underwater to obtain a UV-resistant, halogen-free, flame-retardant polyurethane elastomer.

9. A UV-resistant, halogen-free, flame-retardant polyurethane elastomer, characterized in that, It is prepared by the preparation method described in claim 8.

10. The UV-resistant, yellowing-resistant, halogen-free, flame-retardant polyurethane elastomer as described in claim 9, characterized in that, The polyurethane elastomer, after 240 hours of xenon lamp testing, exhibits ΔE < 3, oxygen index > 28%, reaches a UL 94-V0 flame retardancy rating of 3.0 mm, tensile strength ≥ 20 MPa, and elongation at break ≥ 400%.

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