Long glass fiber reinforced flame-retardant ceramic polypropylene material and preparation method thereof

Abstract

The invention provides a long glass fiber reinforced flame-retardant ceramic polypropylene material and a preparation method thereof. Comprising the following components in parts by weight: 0-20 parts of polypropylene, 30-60 parts of flame-retardant long glass fiber master batch and 40-70 parts of ceramic master batch. According to the invention, the multi-gradient melting point glass powder, the phosphorus flame retardant, the tetrapod-like zinc oxide whisker, the long glass fiber and the ceramic forming filler are matched, so that a carbon layer can be kept compact in structure and high in structural strength during combustion, resists flame pressure and is not damaged; an interlayer structure blocks a heat conduction path, the back surface temperature is obviously reduced, and the material is prevented from softening and collapsing. The obvious effects of ablation resistance, good processing, high strength, good flame retardance, low cost and light weight are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a high-strength, ablation-resistant long glass fiber reinforced flame-retardant ceramic polypropylene material and a preparation method thereof. Background Art

[0002] As a new type of high-efficiency fireproof material, ablative-resistant polymer materials have gradually come into everyone's view. When encountering open flames, the surface of this composite material can be transformed into a self-supporting ablative-resistant body, preventing the flame from spreading into the interior of the material, thereby achieving the purpose of high-efficiency flame retardancy.

[0003] The existing technologies of ablation-resistant materials are mostly concentrated on thermosetting plastics as the matrix or additives. They are resistant to high temperatures, do not soften, and have excellent combustion performance, but the materials have the disadvantage of being difficult to recycle. Among thermoplastics, PPS and PPO currently have better ablation resistance. They have excellent flame retardancy and high softening points, but they have problems such as high cost and insufficient production capacity, making them difficult to apply on a large scale. Polypropylene has a low density and high output, and is a very practical general-purpose resin. The application research of ceramicized polypropylene modified by ablation resistance has more and more economic and social value.

[0004] As a material for the battery pack cover, it needs to have good formability for large parts, excellent mechanical strength, dimensional stability, flame retardancy, and ablation resistance. Its ablation resistance performance includes the ability to resist open flames, temperature (500-1200°C), pressure (air pressure, particle impact), etc. To resist open flames, the material needs to have a flame retardancy level of V0 or above. To resist temperature and pressure, the material needs to be burned at 1000-1200°C for more than 10 minutes without burning through.

[0005] On the one hand, the material needs to have sufficient carbon layer strength to resist the direct impact of flame pressure and particles. On the other hand, in many cases, due to the softening and deformation of polypropylene materials and the collapse of the structure, the flame ablation point position is expanded, the heat and force area of ​​the material is expanded, and it is not enough to support itself and is pulled and burned through. Therefore, the back temperature needs to be as low as possible to keep the material structure from collapsing.

[0006] Patent CN115322477B discloses a lightweight ablation-resistant polypropylene material and a preparation method thereof. The use of a ceramic filler masterbatch effectively reduces the volume fraction of inorganic powder filler added, but the low-melting point hollow flux has a larger volume fraction, which affects the processability, and the material is easily broken during the processing, and the expected effect cannot be achieved.

[0007] The inorganic flame retardant used in patent CN115322477B, the foaming agent used in patent CN112745549B, and the inorganic magnesium compound solution used in patent CN112745571B will release a large amount of water vapor and carbon dioxide, resulting in a fluffy carbon layer and low strength.

[0008] Patent CN112745573B adopts an alloy solution of polypropylene resin and polyamide resin. Due to the intermolecular hydrogen bonding of the PA phase, the core layer provides the alloy material with overall excellent mechanical properties. However, the phosphorus and nitrogen flame retardants used cause uncontrollable carbon layer pore quantity and pore size, affecting the strength of the carbon layer.

[0009] Patent CN103865154B discloses an anti-drip ceramic polyolefin composite material and its preparation method, wherein EVA, high and low softening point glass powder, organic montmorillonite, silane coupling agent, and MAH-g-PP are mixed in a double-roll mill to obtain a sheet, and the surface can be quickly transformed into a dense ceramic residue at high temperature. However, no flame retardant is added, and the material is drip-free only by relying on the dispersion of fillers in the matrix and the fireproof performance after ceramicization, and the flame retardant performance is unstable.

[0010] In addition, some research focuses on filler solutions such as boron nitride and silicon nitride whiskers, but they are expensive and difficult to apply on a large scale. Summary of the invention

[0011] To solve the above problems, the present invention provides a long glass fiber reinforced flame retardant ceramic polypropylene material, which can have high ablation resistance without affecting the processing performance, and maintain excellent mechanical strength, flame retardant properties and low cost.

[0012] To achieve the above object, the present invention adopts the following technical solution:

[0013] A long glass fiber reinforced flame retardant ceramic polypropylene material and a preparation method thereof, characterized in that it comprises the following components in parts by weight:

[0014] Polypropylene 0-20 parts

[0015] Flame retardant long glass fiber masterbatch 30-60 parts

[0016] Ceramic masterbatch 40-70 parts

[0017] The flame retardant long glass fiber masterbatch comprises the following components in parts by weight: 20-40 parts of polypropylene, 50-60 parts of long glass fiber, 10-15 parts of phosphorus flame retardant, and 1-5 parts of other additives. The polypropylene is homopolymer polypropylene; the phosphorus flame retardant is at least one of red phosphorus, BDP, RDP, TPP, and ADP; the other additives include compatibilizers, dispersants, antioxidants, lubricants, toners, etc.

[0018] The ceramic masterbatch comprises the following components in parts by weight: 30 parts of polypropylene, 25-55 parts of ceramic filler, 2-6 parts of four-needle zinc oxide whisker, 15-30 parts of glass powder, and 1-5 parts of other additives. The ceramic filler is one or more of kaolin, talc, mica, and wollastonite; the glass powder is a multi-gradient melting point glass powder, which is compounded by glass powder A, glass powder B, and glass powder C; wherein the softening point of glass powder A is 350-400°C, the softening point of glass powder B is 500-600°C, and the softening point of glass powder C is 700-800°C; the ratio of glass powder A: glass powder B: glass powder C is 1: (0.1-0.5): (0.8-2); the other additives include compatibilizers, dispersants, antioxidants, lubricants, color powders, etc.

[0019] The long glass fiber reinforced flame retardant ceramic polypropylene material is prepared by the following method:

[0020] (1) Weighing polypropylene resin, flame retardant, and other additives, stirring and mixing them evenly in a high-speed machine, and then passing through a twin-screw extruder into an impregnation tank, wherein the temperature of the impregnation tank is set at 240-280° C., and after the long glass fibers according to the weight ratio pass through the impregnation tank, they are stretched, cooled, pelletized, and dried to obtain flame-retardant long glass fiber masterbatch;

[0021] (2) Weighing polypropylene resin, ceramic filler, four-needle zinc oxide whisker, glass powder, and other additives, stirring and mixing in a high-speed machine, and then feeding into a twin-screw extruder for granulation at a temperature of 200-240° C. and a rotation speed of 480 rpm, cooling, pelletizing, and drying to obtain a ceramic masterbatch;

[0022] (3) Weighing polypropylene resin, flame retardant long glass fiber masterbatch, and ceramic masterbatch, stirring and mixing them evenly in a high-speed machine to obtain a long glass fiber reinforced flame retardant ceramic polypropylene material.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention achieves remarkable effects of ablation resistance (no burn-through or collapse at 1200°C / 10min), good processing, high strength (specific strength>50), good flame retardancy (V0), low cost and light weight by selecting a combination of multi-gradient melting point glass powder, phosphorus flame retardant, four-needle zinc oxide whisker, long glass fiber and porcelain filler.

[0025] 2. The three groups of low-melting-point glass powders that have been regulated and matched in proportion are conducive to the transformation of solid glass powder into liquid phase layers under different temperature gradients. They have excellent flow and diffusion capabilities, and are bonded with ceramic fillers to form a eutectic reaction to form a "sandwich" structure of a ceramic-like carbon layer. The process of building a multi-layer structure can fill gaps and make up for defects, making the carbon layer strong and resistant to flame pressure without damage; the interlayer structure can block the heat conduction path, exponentially reduce the heat transfer rate, significantly reduce the back temperature, keep the material from softening, and keep the structure from collapsing.

[0026] 3. The four-needle zinc oxide whiskers that have been screened and proportioned can be fully enriched around the lamellar structure of the ceramic filler during the sintering process due to their unique nano-tip effect and large specific surface area, and connect with the capillary of the molten glass liquid phase layer. As a bridge, they bond with the ceramic filler and long glass fiber to form a self-supporting structure, forming a eutectic mixture at high temperature to form a stable and reliable ceramic-like layer.

[0027] 4. The flame-retardant long glass fiber masterbatch adopts phosphorus flame retardant, which has small addition amount, low density and high strength. The phosphorus flame retardant mechanism is to terminate the free radical chain reaction and promote carbonization, without producing gas, which can keep the carbon layer structure dense and with high structural strength.

[0028] 5. Long glass fiber reinforced polypropylene has higher initial performance, and the glass fiber retention length is longer, which is more conducive to the interlacing in the XYZ three-dimensional direction of the ceramic carbon layer "sandwich" structure, together forming a stable self-supporting structure.

[0029] 6. Prepare flame-retardant long glass fiber masterbatch and ceramic masterbatch first, and then mix them externally. On the one hand, it avoids excessive shear collision of multi-component raw materials with different characteristics in the extruder at the same time, and the performance loss is small; on the other hand, different glass fiber contents such as G15~G36 can be flexibly selected and mixed according to the actual part formability and strength performance requirements, which has free design and convenient back-end application. DETAILED DESCRIPTION

[0030] To make the technical solution of the present invention clearer, the present invention is further described below, and any equivalent replacement of the technical features of the technical solution of the present invention and any solution derived by conventional reasoning fall within the protection scope of the present invention. The materials used in the present invention are all conventionally commercially available.

[0031] The materials used in the present invention are as follows:

[0032] Polypropylene: Homopolymer polypropylene resin, melt index 90g / 10min, tensile strength 45MPa

[0033] Long glass fiber: TCR738, linear density 2400tex

[0034] Short glass fiber: T5380D, diameter 13μm, length 4.5mm

[0035] Glass powder A: softening point is 380℃

[0036] Glass powder B: softening point is 550℃

[0037] Glass powder C: softening point is 780℃

[0038] Four-needle zinc oxide whisker: diameter 1μm, length 50μm

[0039] Phosphorus flame retardant: microcapsule-coated red phosphorus

[0040] Nitrogen-phosphorus flame retardant: ammonium polyphosphate APP

[0041] Kaolin: 1000 mesh

[0042] Compatibilizer: Maleic anhydride grafted polypropylene, grafting rate 1.5%

[0043] Antioxidant: Compound of 1010 and 168

[0044] Dispersants: Dendrimers

[0045] Lubricant: Ultra-high molecular weight silicone masterbatch

[0046] Example 1

[0047] Weigh 32 parts of polypropylene resin, 14 parts of red phosphorus flame retardant, 3 parts of compatibilizer, 0.5 parts of dispersant, and 0.5 parts of antioxidant, stir and mix them evenly in a high-speed machine, and then pass through a twin-screw extruder into an impregnation tank. The set temperature of the impregnation tank is 260°C. After 50 parts of long glass fiber by weight pass through the impregnation tank, they are stretched, cooled, pelletized, and dried to obtain flame-retardant long glass fiber masterbatch;

[0048] Weigh 30 parts of polypropylene resin, 40 parts of kaolin, 10 parts of glass powder A, 4 parts of glass powder B, 10 parts of glass powder C, 3 parts of tetrapod-shaped zinc oxide whiskers, 2 parts of compatibilizer, 0.7 parts of dispersant, and 0.3 parts of antioxidant, stir and mix in a high-speed machine, and then feed into a twin-screw extruder for granulation at a temperature of 220° C. and a rotation speed of 480 rpm. After cooling, pelletizing, and drying, ceramic masterbatch is obtained;

[0049] Weigh 40 parts of flame-retardant long glass fiber masterbatch and 60 parts of ceramic masterbatch, stir and mix them evenly in a high-speed machine to obtain a long glass fiber reinforced flame-retardant ceramic polypropylene material.

[0050] Example 2

[0051] Weigh 26 parts of polypropylene resin, 10 parts of red phosphorus flame retardant, 3 parts of compatibilizer, 0.5 parts of dispersant, and 0.5 parts of antioxidant, stir and mix them evenly in a high-speed machine, and then pass through a twin-screw extruder into an impregnation tank. The set temperature of the impregnation tank is 260°C. After 60 parts of long glass fiber by weight pass through the impregnation tank, they are stretched, cooled, pelletized, and dried to obtain flame-retardant long glass fiber masterbatch;

[0052] Weigh 30 parts of polypropylene resin, 40 parts of kaolin, 10 parts of glass powder A, 4 parts of glass powder B, 10 parts of glass powder C, 3 parts of tetrapod-shaped zinc oxide whiskers, 2 parts of compatibilizer, 0.7 parts of dispersant, and 0.3 parts of antioxidant, stir and mix in a high-speed machine, and then feed into a twin-screw extruder for granulation at a temperature of 220° C. and a rotation speed of 480 rpm. After cooling, pelletizing, and drying, ceramic masterbatch is obtained;

[0053] Weigh 10 parts of polypropylene, 50 parts of flame-retardant long glass fiber masterbatch, and 40 parts of ceramic masterbatch, stir and mix them evenly in a high-speed machine to obtain a long glass fiber reinforced flame-retardant ceramic polypropylene material.

[0054] Example 3

[0055] The difference from Example 1 is the ceramic masterbatch: 30 parts of polypropylene resin, 35 parts of talc, 11 parts of glass powder A, 4 parts of glass powder B, 15 parts of glass powder C, 2 parts of tetrapod-shaped zinc oxide whiskers, 2 parts of compatibilizer, 0.7 parts of dispersant, and 0.3 parts of antioxidant.

[0056] Example 4

[0057] The difference from Example 1 is that the ceramic masterbatch includes: 30 parts of polypropylene resin, 46 parts of kaolin, 6 parts of glass powder A, 2 parts of glass powder B, 8 parts of glass powder C, 5 parts of tetrapod-shaped zinc oxide whiskers, 2 parts of compatibilizer, 0.7 parts of dispersant and 0.3 parts of antioxidant.

[0058] Example 5

[0059] The difference from Example 1 is that 15 parts of polypropylene, 30 parts of flame-retardant long glass fiber masterbatch, and 55 parts of ceramic masterbatch are weighed, stirred and mixed evenly in a high-speed machine to obtain a long glass fiber reinforced flame-retardant ceramic polypropylene material.

[0060] Example 6

[0061] The difference from Example 2 is that 60 parts of flame-retardant long glass fiber masterbatch and 40 parts of ceramic masterbatch are weighed, stirred and mixed evenly in a high-speed machine to obtain a long glass fiber reinforced flame-retardant ceramic polypropylene material.

[0062] Comparative Example 1

[0063] The difference from Example 1 is that there is no glass powder and the kaolin content is increased accordingly.

[0064] Comparative Example 2

[0065] The difference from Example 1 is that there is no tetrapod-shaped zinc oxide whisker, and the kaolin content is increased accordingly.

[0066] Comparative Example 3

[0067] The difference from Example 1 is that the red phosphorus flame retardant is replaced by a nitrogen-phosphorus flame retardant.

[0068] Comparative Example 4

[0069] The difference from Example 1 is that the long glass fiber is replaced by the short glass fiber. There is no dipping tank process, and the pelletization is carried out by a twin-screw extruder of Cai Yungong.

[0070] Comparative Example 5

[0071] The difference from Example 1 is that 50 parts of polypropylene, 20 parts of flame-retardant long glass fiber masterbatch, and 30 parts of ceramic masterbatch are weighed, stirred and mixed evenly in a high-speed machine to obtain a long glass fiber reinforced flame-retardant ceramic polypropylene material.

[0072] Comparative Example 6

[0073] The difference from Example 4 is that there are 53 parts of kaolin, 4 parts of glass powder A, 2 parts of glass powder B, and 4 parts of glass powder C.

[0074] Comparative Example 7

[0075] The difference from Example 1 is that there are 28 parts of kaolin, 12 parts of glass powder A, 12 parts of glass powder B, and 12 parts of glass powder C.

[0076] Comparative Example 8

[0077] The difference from Example 1 is that there are 12 parts of glass powder A, 12 parts of glass powder C, and no glass powder B.

[0078] Comparative Example 9

[0079] The difference from Example 1 is that there are 42 parts of kaolin, 5 parts of glass powder A, 12 parts of glass powder B and 5 parts of glass powder C.

[0080] Comparative Example 10

[0081] The difference from Example 2 is that 70 parts of flame-retardant long glass fiber masterbatch and 30 parts of ceramic masterbatch are weighed, stirred and mixed evenly in a high-speed machine to obtain a long glass fiber reinforced flame-retardant ceramic polypropylene material.

[0082] Product performance test method:

[0083] The particles obtained in the examples and comparative examples were injection molded at a temperature of 230-260° C., the mold temperature was controlled at about 60° C., and relevant performance tests were performed according to the following test methods.

[0084] (1) Density: According to ISO 1183-1 method, the sample size is 20*10*4mm;

[0085] (2) Tensile strength: according to ISO 527 method, specimen size 170*10*4mm, test speed 5mm / min;

[0086] (3) Specific strength: ratio of tensile strength to density;

[0087] (4) Flame retardant grade: The sample size is 125×13×1.6 mm, and the test is carried out according to the UL-94 standard;

[0088] (5) Back-fire surface temperature: a butane high-speed flame spray gun is used with a pressure of 0.5 MPa and an outer flame temperature of 1200°C. The flame is applied to the center of a vertically placed 150 mm x 100 mm x 2 mm plate sample for 10 minutes. The back-fire surface temperature is measured online in real time using a φ30 mm patch thermocouple sensor temperature meter. The test is stopped when the monitored temperature is greater than 1000°C. The unit is °C.

[0089] Table 1 Performance test results of the embodiments

[0090]

[0091]

[0092] Table 2 Comparative Examples Performance Test Results

[0093]

[0094] From the performance test results of Examples 1 to 6 in Table 1 and Comparative Examples 1 to 9 in Table 2, it can be clearly seen that the present invention has a significant ablation resistance effect, no burn-through, no collapse at 1200°C / 10min, high initial performance, and specific strength>50. No glass powder was added in Comparative Example 1, and no four-needle zinc oxide whiskers were added in Comparative Example 2, so it was difficult to quickly construct a ceramic layer, and it burned through and collapsed after burning for 2min. The nitrogen-phosphorus flame retardant in Comparative Example 3 produced random bubbles, short glass fibers in Comparative Example 4, and the masterbatch ratio in Comparative Example 10 was improperly matched. Although it can withstand burning for 2min, as time goes on, the continuous heat and pressure of the flame breaks through the carbon layer, resulting in burn-through. Comparative Example 5 caught fire as a whole. Comparative Examples 6 to 9 cannot meet the burn-through and collapse after the flame severity is upgraded.

Claims

1. A long glass fiber reinforced flame retardant ceramic polypropylene material, characterized in that: The composition comprises the following components in parts by weight: Polypropylene 0-20 parts; 30-60 parts of flame retardant long glass fiber masterbatch; Ceramic masterbatch 40-70 parts.

2. The long glass fiber reinforced flame retardant ceramic polypropylene material according to claim 1, characterized in that: The flame retardant long glass fiber masterbatch comprises the following components in parts by weight: 20-40 parts of polypropylene, 50-60 parts of long glass fiber, 10-15 parts of phosphorus flame retardant, and 1-5 parts of other additives.

3. The long glass fiber reinforced flame retardant ceramic polypropylene material according to claim 2, characterized in that: The polypropylene is homopolymer polypropylene.

4. The long glass fiber reinforced flame retardant ceramic polypropylene material according to claim 2, characterized in that: The phosphorus-based flame retardant is at least one of red phosphorus, BDP, RDP, TPP, and ADP.

5. The long glass fiber reinforced flame retardant ceramic polypropylene material according to claim 2, characterized in that: The other auxiliary agents include compatibilizers, dispersants, antioxidants, lubricants, and toners.

6. The long glass fiber reinforced flame retardant ceramic polypropylene material according to claim 1, characterized in that: The ceramic masterbatch comprises the following components in parts by weight: 30 parts of polypropylene, 25-55 parts of ceramic filler, 2-6 parts of tetrapod-shaped zinc oxide whiskers, 15-30 parts of glass powder, and 1-5 parts of other additives.

7. The long glass fiber reinforced flame retardant ceramic polypropylene material according to claim 6, characterized in that: The porcelain-forming filler is one or more of kaolin, talc, mica and wollastonite.

8. The long glass fiber reinforced flame retardant ceramic polypropylene material according to claim 6, characterized in that: The glass powder is a multi-gradient melting point glass powder, which is compounded by glass powder A, glass powder B, and glass powder C; the softening point of glass powder A is 350-400°C, the softening point of glass powder B is 500-600°C, and the softening point of glass powder C is 700-800°C; the ratio of glass powder A: glass powder B: glass powder C is 1: (0.1-0.5): (0.8-2).

9. The long glass fiber reinforced flame retardant ceramic polypropylene material according to claim 6, characterized in that: The other auxiliary agents include compatibilizers, dispersants, antioxidants, lubricants, and toners.

10. The method for preparing the long glass fiber reinforced flame retardant ceramic polypropylene material according to any one of claims 1 to 9, characterized in that: The steps are: (1) Weighing polypropylene resin, flame retardant, and other additives, stirring and mixing them evenly in a high-speed machine, and then passing through a twin-screw extruder into an impregnation tank, wherein the temperature of the impregnation tank is set at 240-280° C., and after the long glass fibers according to the weight ratio pass through the impregnation tank, they are stretched, cooled, pelletized, and dried to obtain flame-retardant long glass fiber masterbatch; (2) Weighing polypropylene resin, ceramic filler, four-needle zinc oxide whisker, glass powder, and other additives, stirring and mixing in a high-speed machine, and then feeding into a twin-screw extruder for granulation at a temperature of 200-240° C. and a rotation speed of 480 rpm, cooling, pelletizing, and drying to obtain a ceramic masterbatch; (3) Weighing polypropylene resin, flame retardant long glass fiber masterbatch, and ceramic masterbatch, stirring and mixing them evenly in a high-speed machine to obtain a long glass fiber reinforced flame retardant ceramic polypropylene material.

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