A flame-retardant silane self-crosslinking insulating material and its preparation method and application

Abstract

The present invention discloses a flame retardant silane self-crosslinking insulating material and its preparation method and application. The flame retardant silane self-crosslinking insulating material, in parts by weight, includes material A and material B, and the weight ratio of material A to material B is (50-70): (20-40), wherein material A includes the following components in parts by weight: 5-10 parts of a compatibilizer, 20-40 parts of a toughening agent, 30-60 parts of an inorganic filler powder, 20-30 parts of a brominated flame retardant, 20-30 parts of ceramic microbeads, 1-3 parts of a catalyst co-agent, and 4-8 parts of an antioxidant; material B includes the following components in parts by weight: 30-50 parts of polyethylene, 10-30 parts of a toughening agent, 1-5 parts of a silane coupling agent, and 1-5 parts of an initiator. The flame retardant silane self-crosslinking insulating material of the present invention has good mechanical properties, flame retardancy can reach VW-1, and reaches 150°C temperature resistance performance requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a flame-retardant silane self-crosslinking insulating material, a preparation method thereof, and an application thereof. Background Art

[0002] With the development of industry, the demand for wires and cables is increasing. The insulation and sheathing materials used in wires and cables are mostly organic polymers. These wires and cables are prone to combustion under conditions such as high voltage and heat sources. Therefore, improving the flame retardancy of cable materials is very important. UL (Underwriters Laboratories, Inc.) standards are used to evaluate the flame retardancy and heat aging resistance of wires. Flame retardancy meets the vertical specimen combustion test (VW-1), and heat aging resistance is 125°C heat aging resistance and 150°C heat aging resistance.

[0003] Traditional high-flame-retardant insulation materials, using hypophosphite-compounded inorganic flame-retardant powders, can meet the VW-1 flame-retardancy requirements of the UL1581 standard. However, due to the performance limitations of the flame-retardant system, these materials cannot meet the 125°C heat resistance requirements. Furthermore, these cable insulation materials require outsourcing for electron beam cross-linking, resulting in relatively low production efficiency and high costs, making them difficult to effectively apply in large-scale construction and rail transit applications.

[0004] Prior art discloses a silane self-crosslinking wire insulation material that meets the V-1 UL94 vertical flame test and is suitable for use in many electronic and electrical devices. However, it cannot meet the specific flame retardancy requirements of electrical equipment such as cables and wires. Therefore, there is an urgent need for a silane self-crosslinking insulation material that meets the VW-1 flame retardancy requirements of the UL1581 standard, can achieve crosslinking by naturally aging at room temperature for 5-7 days without external irradiation, and can meet the temperature resistance requirements of 125°C and above, so as to meet the practical application of internal connecting wires in electrical equipment. Summary of the Invention

[0005] In view of the defects in the prior art, the present invention proposes a flame-retardant silane self-crosslinking insulating material and a preparation method and application thereof.

[0006] The present invention provides a flame-retardant silane self-crosslinking insulating material, which comprises, in parts by weight, a material A and a material B, wherein the weight ratio of the material A to the material B is (50-70):(20-40), such as (50:40), (60:30), and (70:20), wherein the material A comprises, in parts by weight, the following components:

[0007] 5 to 10 parts of compatibilizer, such as 5, 6, 7, 8, 9, 10 parts;

[0008] 20-40 parts of toughening agent, such as 20, 25, 30, 35, 40 parts;

[0009] 30-60 parts of inorganic filler powder, such as 30, 40, 50, 60 parts;

[0010] 20-30 parts of brominated flame retardant, such as 20, 25, 30 parts;

[0011] 20-30 parts of ceramic microbeads, such as 20, 25, 30 parts;

[0012] 1 to 3 parts of catalyst promoter, such as 1, 2, or 3 parts;

[0013] 4 to 8 parts of antioxidant, such as 4, 5, 6, 7, or 8 parts;

[0014] Material B includes the following components in parts by weight:

[0015] 30-50 parts of polyethylene, such as 30, 35, 40, 45, 50 parts;

[0016] 10 to 30 parts of toughening agent, such as 10, 15, 20, 25, 30 parts;

[0017] 1 to 5 parts of silane coupling agent, such as 1, 2, 3, 4, or 5 parts;

[0018] 1 to 5 parts of initiator, such as 1, 2, 3, 4, or 5 parts.

[0019] In the material A, the toughening agent accounts for a minimum content of not less than 15% of the material A;

[0020] In the material B, the minimum content of polyethylene is not less than 45%.

[0021] The flame-retardant silane self-crosslinking insulating material of the present invention is prepared by mixing material A and material B according to a proportion. The self-crosslinking polyolefin material does not need to be irradiated. After being extruded by a downstream cable factory and left for a period of time, water molecules in the air enter the material to generate -Si-OH. Then, the -Si-OH and -Si-OH are dehydrated to form a crosslinking network, thereby achieving self-crosslinking to prepare a B1-level silane self-crosslinking low-smoke halogen-free insulating material.

[0022] Furthermore, the mass ratio of the inorganic filler powder, the brominated flame retardant and the ceramic microbeads is (2-2.5): (1-1.5): (1-1.5).

[0023] Furthermore, in the material A and the material B, the toughening agent is one or more of POE, EVA, EEA, EMA, and EBA;

[0024] The melt index of the toughening agent is 0.5 to 25 g / 10 min, preferably 0.5 to 10 g / 10 min; under the test conditions of 190° C. and 2.16 kg, the test standard is GB / T 3682-2000.

[0025] Furthermore, the brominated flame retardant is one or more of brominated triazine, tetrabromobisphenol A, decabromodiphenylethane, and polybrominated styrene.

[0026] Furthermore, the D50 particle size of the ceramic microbeads is preferably 10 to 90 μm.

[0027] Furthermore, the inorganic filler powder is one or more of magnesium hydroxide and aluminum hydroxide, and the particle size D50 of the inorganic filler powder is 1 to 15 μm, preferably 1 to 8 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, and 8 μm; an efficient flame retardant system is formed by compounding the inorganic filler powder, brominated flame retardant and ceramic microbeads, while making the material less likely to produce gel during processing and having excellent mechanical properties.

[0028] The particle size was measured using a Malvern laser particle size analyzer, model MS3000. Before testing, the sample was mechanically stirred to disperse it evenly, and then ultrasonic high-frequency vibration was used to fully disperse the agglomerated particles in deionized water before testing.

[0029] Furthermore, the compatibilizer is one or more of POE-g-MAH, LLDPE-g-MAH, EVA-g-MAH, and EXA-g-MAH.

[0030] Furthermore, the polyethylene is any one of linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE); the melt index of the polyethylene is preferably 2 to 6 g / 10 min, under the test conditions of 190° C. and 2.16 kg, and the test standard is GB / T 3682-2000.

[0031] Furthermore, the initiator is one or more of di-tert-butyl peroxide, 2,3-dimethyl-2,3-diphenylbutane, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

[0032] Furthermore, the silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltri(2-methoxyethoxy)silane.

[0033] Furthermore, the catalyst aid is one or more of dibutyltin dilaurate, dioctyltin dilaurate or di(dodecylthio)dibutyltin.

[0034] Furthermore, the antioxidant is selected from one or more of antioxidants 1010, 168, and RIANOX DSTDP.

[0035] Furthermore, the silane self-crosslinking insulating material also includes a processing aid, which is selected from one or more of fluorine-based substances, PE wax, silicone masterbatch or stearic acid; the weight portion of the processing aid is 1 to 3 parts.

[0036] The present invention also provides a method for preparing the flame-retardant silane self-crosslinking insulating material, comprising the following steps:

[0037] (1) Weigh material A by weight and mix them evenly, mix them by reciprocating machine, plasticize and granulate them, and then vacuum pack them;

[0038] (2) Weigh material B by weight and mix them evenly, extrude them through a twin-screw extruder, granulate them, dry them, and then vacuum pack them;

[0039] (3) Extrusion molding material A and material B to obtain the flame-retardant silane self-crosslinking insulating material.

[0040] The present invention also provides application of the flame-retardant silane self-crosslinking insulation material in the fields of engineering construction and rail transportation.

[0041] In summary, compared with the prior art, the present invention achieves the following technical effects:

[0042] (1) The present invention uses a compound of inorganic filler powder, brominated flame retardant and ceramic microbeads to make the flame retardant silane self-crosslinking insulation material capable of achieving an outer diameter of the connecting wire of 0.1 mm to 10 mm and a flame retardant performance of VW-1.

[0043] (2) The flame-retardant silane self-crosslinking insulating material of the present invention meets the flame-retardant performance while complying with the 150°C temperature resistance performance grade requirement and has excellent processing performance and mechanical properties. DETAILED DESCRIPTION

[0044] In order to help those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts should fall within the scope of protection of the present invention.

[0045] Example

[0046] The present invention is further described below with reference to specific examples and comparative examples. The following specific examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following examples, and are particularly not limited to the types of the various component raw materials used in the following specific examples.

[0047] 1. The sources of raw materials for the embodiments and comparative examples are as follows:

[0048] Toughener #1: EVA, brand 7350M, melt index 4g / 10min, Yangzi Petrochemical;

[0049] Toughener #2: POE, brand POE 7467, melt index 1.2 g / 10 min, Dow Chemical Company;

[0050] Toughener #3: POE, brand POE 8200, melt index 5 g / 10 min, Dow Chemical Company;

[0051] Toughener #4: EVA, brand EVA 28025, melt index 25 g / 10 min, LG Chem;

[0052] Compatibilizer: LLDPE-g-MAH, brand YBL-G73B, Kingfa Science & Technology Co., Ltd.

[0053] Brominated flame retardant #1: Decabromodiphenylethane, brand H-02NF, Shandong Xiucheng Chemical;

[0054] Brominated flame retardant #2: Tetrabromobisphenol A, brand name Tetrabromobisphenol A, Tianjin Changlu Hangu Saltworks Co., Ltd.

[0055] Nitrogen flame retardant: melamine cyanurate MCA, Xingbeida (Beijing) Chemical Materials Co., Ltd.

[0056] Inorganic filler powder #1: magnesium hydroxide, brand MDH F5, D50 1.1 μm, Yantai Aiful Company;

[0057] Inorganic filler powder #2: magnesium hydroxide, brand ZH-H2-1, D50 6 μm, Wuxi Zehui Chemical Company;

[0058] Inorganic filler powder #3: magnesium hydroxide, brand JS-MDH 02, D50 15 μm, Jiangsu Magnesium Aluminum Chemical;

[0059] Inorganic filler powder #4: aluminum hydroxide, brand OL-104LEO, D50 2.1 μm, Albemarle Corporation;

[0060] Initiator: di-tert-butyl peroxide, brand DTBP, Shaanxi Didu Pharmaceutical Chemical Co., Ltd.

[0061] Ceramic microspheres: GR-10, Shanghai Gerunya Nanomaterials Co., Ltd.

[0062] SiO2: Parallel experiments used the same substance;

[0063] Antioxidant: DSTDP, the same substance was used in parallel experiments;

[0064] Catalytic coagent: di(dodecylthio)dibutyltin, an organotin catalyst. The same substance was used in parallel experiments.

[0065] Processing aid: silicone masterbatch lubricant, the same substance was used in parallel experiments;

[0066] Polyethylene: linear low-density polyethylene (LLDPE), LLDPE 7042, Sinopec;

[0067] Silane coupling agent: vinyltrimethoxysilane, GX-172, Sibao Technology.

[0068] The preparation method of the flame-retardant silane self-crosslinking insulating material of the embodiment of the present invention and the comparative example comprises the following steps:

[0069] (1) Weighing material A by weight and mixing evenly, mixing and plasticizing by a reciprocating machine at 100-200°C to form granules, and vacuum packaging after granulation;

[0070] (2) Weighing material B by weight and mixing them evenly, extruding and granulating them through a twin-screw extruder at 90-200°C, drying them, and vacuum packaging them;

[0071] (3) Material A and material B are mixed according to a ratio, and extrusion molding is performed at 90-180° C. to obtain a self-crosslinking polyolefin material.

[0072] 2. Various performance test methods

[0073] (1) Processing performance test method:

[0074] Thermal extension performance test method:

[0075] The test standard is GB / T 2951.21-2008, which stipulates that a thermal elongation of ≤175% meets the requirements. The lower the thermal elongation, the higher the degree of cross-linking. If the thermal elongation of the finished cable is too large or even breaks, it means that the cross-linking is insufficient or has not occurred.

[0076] (2) Mechanical properties test method:

[0077] The test standard is GB / T 1040.3-2006, and the initial tensile strength is ≥13.79MPa and the initial elongation at break is ≥300% to meet the standards.

[0078] (3) Flame retardant performance test method:

[0079] After the material is processed into thin-walled wire by downstream cable customers, it is tested according to the combustion test method specified in UL1581.

[0080] Table 1 Example technical solutions and effects (units are weight parts; A material: B material = 60:30)

[0081]

[0082]

[0083] Table 2 Technical solutions and effects of the embodiments (units are parts by weight) (the ratio of A to B is adjusted based on Example 1)

[0084]

[0085] Table 3 Comparative Examples Technical Scheme and Effects (Units are parts by weight)

[0086]

[0087]

[0088] In Tables 1 to 3, "-" indicates that when the material is not cross-linked or fails the flame retardant test, there is no corresponding test data. The comparative examples are all single variables with Example 1. In comparative example 1, too much magnesium hydroxide was added, resulting in unqualified mechanical properties, and the frictional heat generated by the screw during processing was too large, which easily produced moisture and thus easily produced a gel point; in comparative example 2, too little brominated flame retardant was added, and the extruded appearance was smooth, but the flame retardant performance was too poor, not meeting the VW-1 flame retardant requirements; in comparative example 3, too little ceramic microbeads were added, and the extruded appearance was smooth, but the flame retardant performance was too poor, not meeting the VW-1 flame retardant requirements; in comparative example 4, too little magnesium hydroxide was added, and the extruded appearance was smooth, but the flame retardant performance was too poor, not meeting the VW-1 flame retardant requirements; in comparative example 5, no silane coupling agent was added; in comparative example 6, too much silane coupling agent was added; in comparative example 7, no initiator was added, and complete crosslinking could not be achieved; in comparative example 8, too much initiator was used, and over-crosslinking occurred; in comparative example 9, a non-brominated flame retardant was used, and the extruded appearance was not smooth; in comparative example 10, SiO2 was used instead of ceramic microbeads, and the extruded appearance was not smooth. The above comparative examples are unable to present good appearance and processing performance in the finished product while taking into account both flame retardant properties and mechanical properties.

[0089] Based on the test data of processing performance, mechanical properties and flame retardant properties in Tables 1 to 3, the insulating material prepared by the embodiment has a smooth surface of the finished cable after extrusion, no gel point appears, the thermal elongation of the finished cable is not higher than 85%, and the processing performance is good; the initial elongation at break is higher than 300%, and the flame retardancy reaches VW-1, which has obvious advantages over the comparative example and can effectively meet the high standards of customers and the market.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flame retardant silane self-crosslinking insulating material, characterized in that: Calculated by weight, it includes material A and material B, and the weight ratio of material A to material B is (50-70): (20-40), wherein material A, calculated by weight, includes the following components: Material B includes the following components in parts by weight: The inorganic filler powder is one or more of magnesium hydroxide and aluminum hydroxide.

2. The flame-retardant silane self-crosslinking insulating material according to claim 1, characterized in that: The mass ratio of the inorganic filler powder, the brominated flame retardant and the ceramic microbeads is (2-2.5): (1-1.5): (1-1.5).

3. The flame-retardant silane self-crosslinking insulating material according to claim 1, characterized in that: In the material A and the material B, the toughening agent is one or more of POE, EVA, EEA, EMA, and EBA.

4. The flame-retardant silane self-crosslinking insulating material according to claim 1, characterized in that: The brominated flame retardant is one or more of brominated triazine, tetrabromobisphenol A, decabromodiphenylethane, and polybrominated styrene.

5. The flame-retardant silane self-crosslinking insulating material according to claim 1, characterized in that: The particle size D50 of the inorganic filler powder is 1 to 15 μm.

6. The flame-retardant silane self-crosslinking insulating material according to claim 1, characterized in that: The compatibilizer is one or more of POE-g-MAH, LLDPE-g-MAH, EVA-g-MAH, and EXA-g-MAH.

7. The flame-retardant silane self-crosslinking insulating material according to claim 1, characterized in that: The initiator is one or more of di-tert-butyl peroxide, 2,3-dimethyl-2,3-diphenylbutane, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane.

8. The flame-retardant silane self-crosslinking insulating material according to claim 1, characterized in that: The silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltri(2-methoxyethoxy)silane.

9. The method for preparing the flame-retardant silane self-crosslinking insulating material according to any one of claims 1 to 8, characterized in that: The steps include: (1) Weigh material A by weight and mix them evenly, mix them by reciprocating machine, plasticize and granulate them, and then vacuum pack them; (2) Weigh material B by weight and mix them evenly, extrude them through a twin-screw extruder, granulate them, dry them, and then vacuum pack them; (3) Extrusion molding material A and material B to obtain the flame-retardant silane self-crosslinking insulating material.

10. Use of the flame-retardant silane self-crosslinking insulation material according to any one of claims 1 to 8 in the fields of engineering construction and rail transportation.

Images