Low-density, high-flame-retardant and high-temperature-boiling-resistant polypropylene insulation material for automobile wire and preparation method thereof

Abstract

The invention discloses a low-density, high-flame-retardant and high-temperature-boiling-resistant polypropylene insulating material for an automobile wire and a preparation method of the low-density, high-flame-retardant and high-temperature-boiling-resistant polypropylene insulating material. 5-40 parts of elastomer resin; 5-10 parts of a functional auxiliary agent; 0.5 to 1.5 parts of an antioxidant; 0.5 to 1.5 parts of an anti-copper agent; and 20-150 parts of a flame retardant. The preparation method mainly comprises two working procedures: firstly, carrying out first-time processing through a reciprocating machine, and carrying out first-time dispersion on components such as the flame retardant by utilizing the relatively soft shearing characteristic of the reciprocating machine; and secondly, secondary processing is carried out on the product in the previous procedure through the double-screw extruder, so that the dispersion uniformity of the flame retardant is ensured, and the flame-retardant uniformity of the product is improved. In addition, the product can also be produced in a processing mode of'flame-retardant master batch + secondary processing extrusion ', but the principle is similar to that of the processing mode, and the effect consistency is achieved. Through system compounding, the problems that a flame-retardant polypropylene insulating material is large in density and not resistant to hydrolysis are successfully solved, and meanwhile, the flame-retardant polypropylene insulating material has the efficient flame-retardant characteristic, so that the flame-retardant polypropylene insulating material is more suitable for use requirements of flame-retardant insulating materials for automobile wires.

Description

Technical Field

[0001] The invention relates to the field of insulating materials for electric wires and cables, and in particular to a low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulating material for automobile wires and a preparation method thereof. Background Art

[0002] In recent years, cross-linked flame-retardant polyolefin insulation materials have been widely developed and applied in the fields of automotive electronic wires, in-vehicle high-voltage wires, etc. However, such materials need to go through cross-linking processes such as boiling and irradiation before use, which not only significantly increases the production time and cost of cables, but also the small molecules produced during the cross-linking process will affect the electrical properties of the insulation materials to a certain extent.

[0003] In contrast, polypropylene, as an insulating material, has excellent insulation properties, high temperature resistance, and recyclability. When used as an insulating material, polypropylene can simplify processing, reduce costs, increase production rates, and significantly increase cable length, making it far superior to cross-linked polyethylene.

[0004] In addition, according to the newly revised standard requirements, the flame retardancy time of cables has been shortened to 30 seconds, which poses new challenges to the flame retardancy of materials. However, the flame retardants used in conventional cables, such as magnesium hydroxide, aluminum hydroxide, and halogen-containing flame retardants, will cause the hydrolysis resistance of thermoplastic cables to deteriorate and the insulation volume resistivity to decrease when the flame retardant content is further increased. At the same time, the increase in material density has further pushed up the cost of cables.

[0005] Therefore, in view of the problems of ordinary flame-retardant polyolefin materials for automotive wires, such as non-recyclability, high density and possible halogen content, the present invention develops a low-density and hot water hydrolysis-resistant thermoplastic flame-retardant polypropylene cable insulation material, while further improving the flame retardancy of the product in order to meet customer requirements. Summary of the invention

[0006] The purpose of the present invention is to provide a low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulating material for automobile wires and a preparation method thereof.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires, the raw materials of which include the following components in parts by weight:

[0009]

[0010]

[0011] According to a further technical solution, the polypropylene resin is a copolymer polypropylene with a melt index of 0.1 to 10 g / 10 min (preferably 2 to 4 g / 10 min), a melting point greater than or equal to 160°C, and only one melting peak; a crystallization peak temperature greater than or equal to 110°C, and only one cooling crystallization peak; and a flexural modulus less than or equal to 1500 MPa.

[0012] In a further technical solution, the elastomer is an olefin block copolymer or / and hydrogenated butadiene styrene; wherein,

[0013] The melting temperature of the olefin block copolymer is greater than or equal to 120° C., and the room temperature compression permanent deformation is less than or equal to 50%, preferably the compression permanent deformation is 20 to 30%;

[0014] The hydrogenated butylbenzene is a hydrogenated butylbenzene with a star structure or a long carbon chain branched structure, and its solubility parameter is 7 to 9;

[0015] When the elastomer is a mixture of an olefin block copolymer and hydrogenated butadiene styrene, the mass ratio of the olefin block copolymer to the hydrogenated butadiene styrene is 100:0 to 0:100, preferably 50:50 to 20:80.

[0016] According to a further technical solution, the functional auxiliary agent is a β-type nucleating agent with toughening function.

[0017] A further technical solution is that the functional additive is a mixture of one or more of maleic anhydride grafted hydrogenated butadiene styrene, maleic anhydride grafted vinyl polyolefin elastomer, maleic anhydride grafted propylene polyolefin elastomer, maleic anhydride grafted EPDM, maleic anhydride grafted EVA or EBA, and maleic anhydride grafted EVM; the maleic anhydride content in the functional additive is greater than or equal to 5‰, preferably 5‰ to 1.5%; the melt index is less than or equal to 8g / 10min, preferably 3 to 5g / 10min.

[0018] In a further technical solution, the functional auxiliary agent is a macromolecular carbon-forming agent having a hyperbranched structure and / or a silicon-oxygen structure.

[0019] According to a further technical solution, the flame retardant is one or more of a flame retardant with a zine ring structure, a phosphazene flame retardant, a phosphorus-nitrogen flame retardant, a silicon flame retardant, a flame retardant synergist, a carbon former, and an intumescent flame retardant, wherein the phosphorus content is greater than or equal to 20%, the nitrogen content is greater than or equal to 40%, and the melting temperature is greater than or equal to 100°C.

[0020] Among them, the flame retardants containing phosphorus and nitrogen elements are all modified by containing silicone, alkyl, alkoxy, amino and / or tetrabutyl titanate, isopropyl titanate, stearoyl isopropyl titanate, chelated titanate molecules, and the flame retardant is modified or coated more than or equal to once.

[0021] The silicon-based flame retardant is modified by alkyl, alkenyl, amino and isocyanate groups to improve the compatibility with other substrates.

[0022] Furthermore, the present invention also discloses a method for preparing a low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires, comprising:

[0023] Step 1: Add polypropylene resin, elastomer resin, functional additives, flame retardants, antioxidants, and anti-copper agents into a BUSS machine in proportion, use a pellet weight loss scale, a powder weight loss scale, and an additive scale to feed the materials in a predetermined proportion, and obtain the first product by melt extrusion, cooling, granulation, and drying; wherein the temperature of the melt extruded gel mass is between 190 and 210° C.;

[0024] Step 2: Add the first product into a twin-screw extruder for secondary processing to ensure the uniformity of flame retardant dispersion; finally, through melt extrusion, cooling, granulation and drying, the low-density, high-flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires is obtained; wherein the extrusion processing temperature is 130-190°C.

[0025] According to a further technical solution, in step one, the moisture content of the first product after drying is less than 200 ppm.

[0026] According to a further technical solution, in step 2, during the extrusion process, the processing temperature of the twin-screw extruder in the initial stage is 130°C, and the processing temperature of the latter stage is 170-190°C.

[0027] A further technical solution is that the configuration of the twin-screw extruder is based on the following: the shear block angles are 45°, 60°, and 90° for use in combination, and a large-lead conveying block and a counter-rotation module are arranged in the middle and rear sections of the screw.

[0028] The words “include,” “including,” and “have” used in this document are open-ended terms, meaning including but not limited to.

[0029] The terms used herein generally have the ordinary meanings of each term used in the art, in the context of the present invention, and in the specific context, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art regarding the description of the present invention.

[0030] The working principle and advantages of the present invention are as follows:

[0031] (1) The present invention solves the problems that the existing flame-retardant polyolefin insulating materials are non-recyclable, have high density, have poor flame retardancy and are not environmentally friendly.

[0032] (2) The present invention solves the problem of poor temperature resistance caused by the low melting point of polyethylene by using polypropylene resin with a higher temperature resistance. It is known that polyethylene used for insulating materials with the same function is low-density polyethylene or linear low-density polyethylene, whose melting point is generally below 120°C. The temperature resistance can only be improved by cross-linking; but after cross-linking, the material cannot be melted and plasticized, and cannot be recycled. It can only be disposed of by burning, burying, etc., which is extremely harmful; the polypropylene resin used in the technical solution of the present invention can avoid the above situation.

[0033] (3) Ordinary halogen-free inorganic flame retardants, such as magnesium hydroxide and aluminum hydroxide, have good flame retardant effects only when the addition amount exceeds 150 parts. However, the specific addition amount not only reduces the mechanical properties, electrical properties, and high-temperature boiling resistance of the material, but also further increases the density of the material. Although halogen flame retardants have good flame retardant effects, the hydrogen halide gas generated during combustion is extremely harmful, and the harm to people and objects is far greater than the harm of fire. Therefore, based on the above problems, the technical solution of the present invention adopts a coated phosphorus-nitrogen flame retardant, which can isolate the erosion of moisture to a small extent and improve the hydrolysis resistance of the material; at the same time, the organic phosphorus-nitrogen flame retardant has both physical isolation (the generated gas dilutes or isolates oxygen), decomposition and heat absorption (the small molecules generated when the flame retardant is violently decomposed can take away a lot of heat, thereby reducing the combustion temperature), and promote carbonization (the generated carbonized layer further isolates the polymer from the fire source, thereby inhibiting combustion). The above flame retardant effects can only be achieved when magnesium hydroxide and aluminum hydroxide are compounded with synergistic flame retardants. More importantly, due to its high flame retardant efficiency, the amount of organic phosphorus nitrogen flame retardant added is only 1 / 4 to 1 / 5 of the amount of magnesium hydroxide and aluminum hydroxide flame retardants, which significantly reduces the material density.

[0034] In summary, the present invention successfully solves the problems of high density and poor hydrolysis resistance of flame-retardant polypropylene insulating materials through system compounding, while also having efficient flame-retardant properties, making it more suitable for the use requirements of flame-retardant insulating materials for automotive lines. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with embodiments:

[0036] Embodiment: The present invention will be described in detail below. After understanding the embodiments of the present invention, any person skilled in the art can make changes and modifications based on the techniques taught by the present invention without departing from the spirit and scope of the present invention.

[0037] The terms used herein are only for describing specific embodiments and are not intended to be limiting of the present invention. Singular forms such as "a", "this", "here", "this" and "the" as used herein also include plural forms.

[0038] Table 1: Insulation material components of Examples 1-6

[0039]

[0040]

[0041] According to the component formula in Table 1, the preparation methods of the embodiments and comparative examples are described as follows:

[0042] The preparation method of embodiment 1:

[0043] First, 80 parts of polypropylene resin (K8003), 20 parts of olefin block copolymer (OBC 9000), and 5 parts of maleic anhydride grafted EVA (VA 1801) are shaken in a low mixer and then added to the pellets to measure the weight loss; 30 parts of compound phosphorus-nitrogen flame retardant (melamine cyanurate / modified aluminum hypophosphite=1 / 5) and 5 parts of carbon forming agent (hyperbranched resin) are shaken and then added to the powder to measure the weight loss; 1.5 parts of antioxidant (1010+DSTP+1024) and 0.2 parts of β-nucleating agent are shaken and then added to the auxiliary agent to measure; then the first product is obtained by melt extrusion, cooling, granulation and drying; in addition, during the processing, it is ensured that the temperature of the melt-extruded micelles is between 190 and 210°C to avoid the micelles from being scorched due to excessive temperature.

[0044] Secondly, the first product is added again into the twin-screw extruder loss-in-weight scale for secondary processing to ensure the uniformity of flame retardant dispersion.

[0045] The temperature of the secondary processing is 130-170-175-175-175-175-180-180-190-190° C., and finally a low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires is obtained through melt extrusion, cooling, granulation and drying.

[0046] The preparation method of embodiment 2:

[0047] First, 60 parts of polypropylene resin (K8003), 20 parts of olefin block copolymer (OBC 9000), 20 parts of branched SEBS, and 5 parts of maleic anhydride grafted SEBS (FG1901) are shaken in a low mixer and then added to the pellets to measure the weight loss; 40 parts of compound phosphorus-nitrogen flame retardant (melamine cyanurate / modified aluminum hypophosphite=1 / 5) and 5 parts of carbon forming agent (hyperbranched resin) are shaken and then added to the powder to measure the weight loss; 1.5 parts of antioxidant (1010+DSTP+1024) and 0.2 parts of β-nucleating agent are shaken and then added to the auxiliary agent to measure; then the first product is obtained by melt extrusion, cooling, granulation and drying; in addition, during the processing, it is ensured that the temperature of the melt-extruded micelles is between 190 and 210°C to avoid the micelles from being scorched due to excessive temperature.

[0048] Secondly, the first product is added again into the twin-screw extruder loss-in-weight scale for secondary processing to ensure the uniformity of flame retardant dispersion.

[0049] The temperature of the secondary processing is 130-170-175-175-175-175-180-180-190-190° C., and finally a low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires is obtained through melt extrusion, cooling, granulation and drying.

[0050] The preparation method of embodiment 3:

[0051] First, 40 parts of polypropylene resin (K8003), 20 parts of olefin block copolymer (OBC 9000), 40 parts of branched SEBS, and 5 parts of maleic anhydride grafted SEBS (FG1901) are shaken in a low mixer and then added to the pellets to measure the weight loss; 50 parts of compound phosphorus-nitrogen flame retardant (melamine cyanurate / modified aluminum hypophosphite=1 / 5) and 5 parts of carbon forming agent (hyperbranched resin) are shaken and then added to the powder to measure the weight loss; 1.5 parts of antioxidant (1010+DSTP+1024) and 0.2 parts of β-nucleating agent are shaken and then added to the auxiliary agent to measure; then the first product is obtained by melt extrusion, cooling, granulation and drying; in addition, during the processing, it is ensured that the temperature of the melt-extruded micelles is between 190 and 210°C to avoid the micelles from being scorched due to excessive temperature.

[0052] Secondly, the first product is added again into the twin-screw extruder loss-in-weight scale for secondary processing to ensure the uniformity of flame retardant dispersion.

[0053] The temperature of the secondary processing is 130-170-175-175-175-175-180-180-190-190° C., and finally a low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires is obtained through melt extrusion, cooling, granulation and drying.

[0054] The preparation method of embodiment 4:

[0055] First, 20 parts of polypropylene resin (K8003), 30 parts of olefin block copolymer (OBC 9000), 50 parts of branched SEBS, and 5 parts of maleic anhydride grafted EVA (VA 1801) are shaken in a low mixer and then added to the pellets to measure the weight loss; 30 parts of compound phosphorus-nitrogen flame retardant (melamine cyanurate / modified aluminum hypophosphite=1 / 5) and 5 parts of carbon forming agent (hyperbranched resin) are shaken and then added to the powder to measure the weight loss; 1.5 parts of antioxidant (1010+DSTP+1024) and 0.2 parts of β-nucleating agent are shaken and then added to the auxiliary agent to measure; then the first product is obtained by melt extrusion, cooling, granulation and drying; in addition, during the processing, it is ensured that the temperature of the melt-extruded micelles is between 190 and 210°C to avoid the micelles from being scorched due to excessive temperature.

[0056] Secondly, the first product is added again into the twin-screw extruder loss-in-weight scale for secondary processing to ensure the uniformity of flame retardant dispersion.

[0057] The temperature of the secondary processing is 130-170-175-175-175-175-180-180-190-190° C., and finally a low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires is obtained through melt extrusion, cooling, granulation and drying.

[0058] Preparation method of comparative example 1:

[0059] First, 80 parts of polypropylene resin (K8003), 20 parts of olefin block copolymer (OBC 9000), and 5 parts of maleic anhydride grafted EVA (VA 1801) are shaken in a low mixer and then added to the pellets to measure the weight loss; 130 parts of compound phosphorus-nitrogen flame retardant (melamine cyanurate / modified aluminum hypophosphite=1 / 5) and 5 parts of carbon forming agent (hyperbranched resin) are shaken and then added to the powder to measure the weight loss; 1.5 parts of antioxidant (1010+DSTP+1024) and 0.2 parts of β-nucleating agent are shaken and then added to the auxiliary agent to measure; then the first product is obtained by melt extrusion, cooling, granulation and drying; in addition, during the processing, it is ensured that the temperature of the melt-extruded micelles is between 190 and 210°C to avoid the micelles from being scorched due to excessive temperature.

[0060] Secondly, the first product is added again into the twin-screw extruder loss-in-weight scale for secondary processing to ensure the uniformity of flame retardant dispersion.

[0061] The temperature of the secondary processing is 130-170-175-175-175-175-180-180-190-190° C., and finally a low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires is obtained through melt extrusion, cooling, granulation and drying.

[0062] Table 2: Performance summary of Examples 1-6:

[0063]

[0064] From the above material performance results, it can be found that after adding specially treated phosphorus-nitrogen flame retardants and functional performance additives, the automotive wire can pass the 35-day 85°C boiling test to ensure that its volume resistivity is not less than 108Ω·cm; at the same time, the anti-flammability time of the cable is within 20s, which meets the requirements of the standard. In addition, compared with the case of adding inorganic flame retardants such as magnesium hydroxide, its density is reduced by at least 25%. After testing, other properties of the material can meet other requirements of the standard. However, due to the large filling amount of magnesium hydroxide flame retardant in the comparative example, the compatibility between the resin and the flame retardant is poor, so that the electrical properties, density, hydrolysis resistance, mechanical properties, etc. are not as good as the embodiments of the present invention. On the whole, the present invention has successfully developed a low-density, high-flame-retardant, hydrolysis-resistant thermoplastic polypropylene insulation material that can be used in the production and use of automotive wiring harnesses.

[0065] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires, characterized by: The raw materials include the following components in parts by weight: 40-70 parts of polypropylene resin; 5-40 parts of elastomer resin; 5~10 parts of functional additives; 0.5~1.5 parts of antioxidant; 0.5~1.5 parts of anti-copper agent; Flame retardant 20~150 parts.

2. The low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires according to claim 1, characterized in that: The polypropylene resin is copolymer polypropylene, with a melt index of 0.1-10 g / 10 min, a melting point greater than or equal to 160° C., and only one melting peak; a crystallization peak temperature greater than or equal to 110° C., and only one cooling crystallization peak; and a flexural modulus less than or equal to 1500 MPa.

3. The low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires according to claim 1, characterized in that: The elastomer is an olefin block copolymer or / and hydrogenated butadiene styrene; The melting temperature of the olefin block copolymer is greater than or equal to 120° C., and the room temperature compression permanent deformation is less than or equal to 50%; The hydrogenated butylbenzene is a hydrogenated butylbenzene with a star structure or a long carbon chain branched structure, and its solubility parameter is 7 to 9; When the elastomer is a mixture of an olefin block copolymer and hydrogenated butadiene styrene, the mass ratio of the olefin block copolymer to the hydrogenated butadiene styrene is 100:0 to 0:

100.

4. The low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires according to claim 1, characterized in that: The functional auxiliary agent is a β-type nucleating agent with toughening function.

5. The low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires according to claim 1, characterized in that: The functional additive is one or a mixture of maleic anhydride grafted hydrogenated butadiene styrene, maleic anhydride grafted vinyl polyolefin elastomer, maleic anhydride grafted propylene polyolefin elastomer, maleic anhydride grafted EPDM, maleic anhydride grafted EVA or EBA, and maleic anhydride grafted EVM; the maleic anhydride content in the functional additive is greater than or equal to 5‰, preferably 5‰~1.5%; the melt index is less than or equal to 8g / 10min, preferably 3~5g / 10min.

6. The low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires according to claim 1, characterized in that: The functional auxiliary agent is a macromolecular carbon-forming agent having a hyperbranched structure and / or a silicon-oxygen structure.

7. The low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires according to claim 1, characterized in that: The flame retardant is one or more of a flame retardant having a zine ring structure, a phosphazene flame retardant, a phosphorus nitrogen flame retardant, a silicon flame retardant, a flame retardant synergist, a carbon former, and an intumescent flame retardant, wherein the phosphorus content is greater than or equal to 20%, the nitrogen content is greater than or equal to 40%, and the melting temperature is greater than or equal to 100°C; Among them, the flame retardants containing phosphorus and nitrogen elements are modified by containing silicone, alkyl, alkoxy, amino and / or tetrabutyl titanate, isopropyl titanate, stearoyl isopropyl titanate, chelate titanate molecules, and the flame retardant is modified or coated more than or equal to once; Wherein, the silicon flame retardant is modified by alkyl, alkenyl, amino and isocyanate groups.

8. A method for preparing a low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires, characterized in that: Used to prepare the low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires as described in any one of claims 1 to 7, the preparation method comprising: Step 1: Add polypropylene resin, elastomer resin, functional additives, flame retardants, antioxidants, and anti-copper agents into a BUSS machine in proportion, use a pellet weight loss scale, a powder weight loss scale, and an additive scale to feed the materials in a predetermined proportion, and obtain the first product by melt extrusion, cooling, granulation, and drying; wherein the temperature of the melt extruded gel mass is between 190 and 210°C; Step 2: Add the first product into a twin-screw extruder for secondary processing, and obtain the low-density, highly flame-retardant, high-temperature boiling-resistant polypropylene insulation material for automotive wires through melt extrusion, cooling, granulation and drying; wherein the extrusion processing temperature is 130~190℃.

9. The preparation method according to claim 8, characterized in that: In step 1, the moisture content of the first product after drying is less than 200 ppm.

10. The preparation method according to claim 8, characterized in that: In step 2, during the extrusion process, the processing temperature of the twin-screw extruder in the initial stage is 130°C, and the processing temperature in the latter stage is 170-190°C.

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