Halogen-free flame-retardant cable sheath material and preparation method thereof

Abstract

The invention discloses a halogen-free flame-retardant cable sheath material and a preparation method thereof. The halogen-free flame-retardant cable sheath material is prepared from the following components in parts by weight: 50-61 parts of TPU resin, 32.5-40 parts of a halogen-free flame retardant, 5-80 parts of a mold flow fusion agent, 1-2 parts of an antioxidant and 0.5-1 part of other auxiliaries. According to the invention, the mold flow fusion agent is introduced in the TPU halogen-free flame-retardant modification mixing process, so that the cable sheath material with mechanical strength, good joint line fusion adhesion and tear resistance is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material modification, in particular to a halogen-free flame-retardant cable sheath material and a preparation method thereof. Background Art

[0002] Thermoplastic polyurethane elastomer (TPU for short) has the functions and properties of traditional thermosetting rubber, such as softness, elasticity, good touch, and wear resistance. It also has the dual advantages of simple and fast processing of general thermoplastics, as well as recyclability. In addition, TPU has excellent tensile strength, wear resistance, low-temperature flexibility, and oil resistance.

[0003] However, TPU resin itself is highly flammable, and a large amount of smoke is easily generated during the combustion process. Therefore, when TPU is used as a cable, it is usually necessary to perform flame retardant modification to meet the flame retardant requirements of the cable. However, a large amount of flame retardant filling will destroy the molecular structure of TPU, reduce the melt index and melt adhesion, and affect the fusion of TPU molecules during extrusion. The cable sheath material needs to undergo a process of diversion, confluence and fusion (commonly referred to as "parting line") inside the extruder. During the diversion process, the TPU material will produce molecular orientation and form a heat conduction path that is conducive to heat dissipation, which hinders the melting adsorption between molecular chains, resulting in poor fusion of TPU at the parting line and "parting line" defects. When the cable is subjected to mechanical stress such as bending, the "parting" line cracks under high and low temperature stress, thereby causing cable molding failure. Chinese patent application CN117844233A improves the fusion strength of the parting line by preparing a molecular weight bimodal distribution TPU. This method has high requirements for extrusion equipment and extrusion process control, and is difficult to achieve with conventional extrusion equipment. Summary of the invention

[0004] In view of this, the present invention provides a halogen-free flame-retardant cable sheath material and a preparation method thereof to solve the problems raised in the above-mentioned background technology. By introducing a mold flow fusion agent into the TPU flame-retardant modified mixing process, a cable sheath material with good mold line melt bonding, mechanical strength and tear resistance is prepared.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention discloses a halogen-free flame-retardant cable sheath material, which is prepared from the following components in parts by weight:

[0007]

[0008] A further solution: the hardness of the TPU resin is 60A-70D, the hard segment is composed of diisocyanate and diol chain extender, and the soft segment is polyether or polyester.

[0009] A further solution: the halogen-free flame retardant is at least one of a phosphorus-based flame retardant, a nitrogen-based flame retardant, a phosphorus-nitrogen composite flame retardant, and an inorganic flame retardant.

[0010] A further solution: the mold flow fusion agent is at least one of ethylene-acrylate-glycidyl methacrylate copolymer and ethylene-acrylate copolymer.

[0011] A further solution: the weight ratio of the ethylene-acrylate-glycidyl methacrylate copolymer to the ethylene-acrylate copolymer is 0.2-5.

[0012] A further solution: the ethylene-acrylate-glycidyl methacrylate copolymer has a glycidyl methacrylate content of 2%-30%.

[0013] A further solution: the antioxidant is at least one of a hindered phenol antioxidant, an amine antioxidant, a phosphite antioxidant, and a thioester antioxidant.

[0014] A further solution: the other auxiliary agent is prepared by compounding an anti-hydrolysis agent and a lubricant in a weight ratio of (1-3): (0.5-2).

[0015] On the other hand, the present invention discloses a method for preparing the above-mentioned halogen-free flame-retardant cable sheath material, comprising the following steps:

[0016] S1. Weigh each component according to weight and put it into a high-speed mixer and stir for 10-20 minutes to obtain a mixed material;

[0017] S2. The mixed material is fed into the main feeding port of the twin-screw extruder. After shearing, melting, extrusion and granulation, a halogen-free flame-retardant cable sheath material with firm melt bonding at the parting line and good tear resistance is obtained.

[0018] A further solution: the screw speed of the twin-screw extruder is 150-300RPM, and the extrusion temperature is 140-180°C.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention introduces a mold flow fusion agent ethylene-acrylate copolymer to connect the TPU molecular chain on the basis of conventional halogen-free flame-retardant modified TPU, which hinders the orientation of the molecular chain during the extrusion process and improves heat retention, so that the cable sheath material is firmly bonded to the melt flow, shunt and confluence at the die head, thereby improving the melt adhesion and tear resistance of the material extrusion processing parting line. It has the following advantages:

[0021] 1. It avoids the degradation of TPU during high-temperature extrusion and improves the mechanical properties of the material;

[0022] 2. The melt bonding at the parting line is more solid, and the tear resistance at the parting line is significantly improved, avoiding the potential risk of cracking of the cable outer sheath caused by poor material flow fusion.

[0023] 3. Compared with conventional high-filling flame-retardant modification, the cable sheath material prepared by the present invention on this basis can still maintain a relatively firm extrusion die line melt bonding. DETAILED DESCRIPTION

[0024] For ease of understanding of the present invention, the present invention will be described more fully below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0026] The specific information of the raw materials used in the following examples and comparative examples is as follows:

[0027] TPU resin: polyether TPU produced by Huntsman, brand 4394;

[0028] Mold flow fusion agent 1: AX8700 and 20MA08 purchased from SK Chemical Company, mixed in a ratio of 1:2;

[0029] Mold flow fusion agent 2: PTW and 34035AC purchased from Dow Chemical Company, mixed in a ratio of 2:1;

[0030] Flame retardant 1: MCA produced by BASF, brand Melapur MC25;

[0031] Flame retardant 2: ADP produced by Clariant, brand Exolit OP 1230;

[0032] Flame retardant 3: BDP produced by ADK, brand name ADK STAB FP-600;

[0033] Antioxidant: a mixture of Irganox 1010 and Irgafos 168 produced by BASF, mass ratio 1:1;

[0034] Other additives: a mixture of lubricant montan wax and anti-hydrolysis agent Stabaxol P100 in a mass ratio of 0.5:2.

[0035] All materials are commercially available common products.

[0036] It is to be understood that the above raw materials and reagents are only examples of some specific embodiments of the present invention, so that the technical solution of the present invention is clearer, and it does not mean that the present invention can only use the above reagents, and the specific scope in the claims shall prevail. In addition, the "parts" described in the examples and comparative examples, unless otherwise specified, refer to parts by weight.

[0037] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0038] The following Table 1 shows the dosage of each component in the examples and comparative examples.

[0039]

[0040]

[0041] Table 1

[0042] The preparation methods of the embodiments and comparative examples are as follows:

[0043] S1: Weigh each component according to the weight portion in Table 1, put it into a high-speed mixer and stir for 10-20 minutes to obtain a mixed material;

[0044] S2: The mixed material is fed into the main feeding port of the twin-screw extruder, and after shearing, melting, extrusion and granulation, a halogen-free flame-retardant cable sheath material with firm melt bonding at the parting line and good tear resistance is obtained.

[0045] Wherein, the screw speed of the twin-screw extruder is 180RPM, and the temperature of the extruder is controlled at 150-180°C.

[0046] After homogenization treatment, the halogen-free flame-retardant cable sheath materials obtained in the embodiment and the comparative example were subjected to performance tests. The test results of the test item set are shown in Table 2.

[0047] Table 2

[0048]

[0049] The test standards for the test items in Table 2 are as follows:

[0050] The obtained particles were pressed into sheets by a flat vulcanizer and used for mechanical property test, hardness test and flame retardant test. The mechanical property test was based on GB / T 528-2009 standard, the hardness test was based on GB / T 531.1-2008 standard, and the flame retardant test was based on UL94 standard.

[0051] Material extrusion appearance evaluation: After extrusion using a Φ90 cable extruder, the tear strength at the die line and low-temperature winding performance were tested. The extrusion temperature was 180℃-200℃, the cable outer diameter was 20mm, and the jacket wall thickness was 1.0mm. The tear strength test at the die line was based on GB / T 529-2008, and the TPU jacket was removed from the cable for testing. The low-temperature winding test was based on GB / T33594-2017, and the test temperature was -55℃.

[0052] From the analysis of Table 2, it can be seen that the materials prepared in all embodiments and comparative examples have achieved a flame retardant grade of V2 or above. The products prepared in each embodiment have achieved a high tear strength at the parting line while ensuring the tensile performance, and have passed the low temperature winding test, demonstrating the effectiveness of the present invention.

[0053] Comparison between Example 1 and Example 1 shows that the tensile strength of the material of Example 1 is significantly reduced, and the tear strength of the parting line is also significantly reduced; compared with Example 5, the tensile strength and tear resistance of the material of Example 2 are significantly reduced, and at the same time, the low-temperature winding of Example 2 cracks. This is because the amount of halogen-free flame retardant used in Example 2 (and Example 5) is more than that in Example 1 (and Example 1), so the low-temperature winding test of Example 2 cracks. The phenomenon that Example 5 does not crack and Example 2 cracks can be explained as follows: the mold flow fusion agent destroys the orientation of the TPU molecular chain during the extrusion diversion and confluence of the cable material and increases the heat retention and the melt adsorption between its own molecular chains. In addition, it improves the compatibility between the flame retardant and the matrix, enhances the interfacial adhesion between different phases, promotes stress transfer between interfaces, and prevents the generation and expansion of cracks.

[0054] Although this specification is described according to implementation modes, not every implementation mode includes only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0055] Therefore, the above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application; that is, all equivalent changes made according to the scope of the claims of the present application are within the protection scope of the claims of the present application.

Claims

1. A halogen-free flame-retardant cable sheath material, characterized in that: It is prepared from the following components in parts by weight:

2. The halogen-free flame-retardant cable sheath material according to claim 1, characterized in that: The hardness of the TPU resin is 60A-70D, the hard segment is composed of diisocyanate and diol chain extender, and the soft segment is polyether or polyester.

3. The halogen-free flame-retardant cable sheath material according to claim 1, characterized in that: The halogen-free flame retardant is at least one of a phosphorus-based flame retardant, a nitrogen-based flame retardant, a phosphorus-nitrogen composite flame retardant, and an inorganic flame retardant.

4. The halogen-free flame-retardant cable sheath material according to claim 1, characterized in that: The mold flow fusion agent is at least one of ethylene-acrylate-glycidyl methacrylate copolymer and ethylene-acrylate copolymer.

5. The halogen-free flame-retardant cable sheath material according to claim 4, characterized in that: The weight ratio of the ethylene-acrylate-glycidyl methacrylate copolymer to the ethylene-acrylate copolymer is 0.2-5.

6. The halogen-free flame-retardant cable sheath material according to claim 4, characterized in that: The ethylene-acrylate-glycidyl methacrylate copolymer has a glycidyl methacrylate content of 2%-30%.

7. The halogen-free flame-retardant cable sheath material according to claim 1, characterized in that: The antioxidant is at least one of a hindered phenol antioxidant, an amine antioxidant, a phosphite antioxidant, and a thioester antioxidant.

8. The halogen-free flame-retardant cable sheath material according to claim 1, characterized in that: The other auxiliary agents are prepared by compounding an anti-hydrolysis agent and a lubricant in a weight ratio of (1-3): (0.5-2).

9. The method for preparing the halogen-free flame-retardant cable sheath material according to any one of claims 1 to 8, characterized in that: include: S1. Weigh each component according to weight and put it into a high-speed mixer and stir for 10-20 minutes to obtain a mixed material; S2. The mixed material is fed into the main feeding port of the twin-screw extruder, and after shearing, melting, extrusion and granulation, a halogen-free flame-retardant cable sheath material with good melt bonding and tear resistance at the parting line is obtained.

10. The preparation method according to claim 9, characterized in that: The screw speed of the twin-screw extruder is 150-300RPM, and the extrusion temperature is 140-180°C.

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