A good appearance, flame-retardant polypropylene composition and its preparation method and application

Abstract

The present application relates to a kind of polypropylene composition and its preparation method and application.The good appearance, flame-retardant polypropylene composition includes the following weight parts of component:PP resin 55~80 parts, PE resin 5~35 parts, PA resin 2~20 parts, pyrophosphoric acid piperazine 21~31 parts, N,N'-ethylene bis stearamide 0.2~2.1 parts.The present application adds pyrophosphoric acid piperazine and a small amount of N,N'-ethylene bis stearamide in the resin system of PP resin, PE resin and PA resin, N,N'-ethylene bis stearamide can make pyrophosphoric acid piperazine well dispersed in resin system, and the obtained polypropylene composition also has good flame-retardant performance and good appearance in the case of keeping good plasticizing performance.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a good-looking, flame-retardant polypropylene composition, its preparation method, and its application. Background Technology

[0002] Halogen-free flame-retardant PP has advantages such as high cost-effectiveness, low smoke, low halogen content, and low specific gravity, resulting in minimal environmental impact. With increasing environmental awareness, international organizations and governments are promoting the development of halogen-free technologies.

[0003] When PP material is used to make casings for electrical appliances and electronic products, the extrusion forming process is mainly used because these products are relatively large. This process requires high melt strength from the PP material. Furthermore, the extrusion forming process also requires the PP material to have good heat resistance.

[0004] Piperazine pyrophosphate is a novel halogen-free flame retardant. Due to its excellent heat resistance, flame-retardant PP with added piperazine pyrophosphate is undoubtedly a good choice for extruded and thermoformed materials. However, piperazine pyrophosphate has poor compatibility with PP resin, making it difficult for it to exert its good flame-retardant effect in PP resin and negatively impacting the appearance of the PP material.

[0005] Therefore, it is necessary to develop halogen-free flame-retardant PP with high melt strength, suitable for extrusion thermoforming, good appearance, and good flame-retardant properties. Summary of the Invention

[0006] The primary objective of this invention is to overcome the technical problems existing in the current technology and to provide a polypropylene composition with good appearance and flame retardancy.

[0007] A further object of the present invention is to provide a method for preparing the above-described polypropylene composition.

[0008] A further object of the present invention is to provide the use of the above-described polypropylene composition in the preparation of household goods, electronic components, household appliances, gardening equipment, medical technology devices, motor vehicle parts or body parts.

[0009] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0010] A good-looking, flame-retardant polypropylene composition comprising the following components in parts by weight:

[0011]

[0012]

[0013] The melt flow rate of the PP resin measured at 230℃ and 2.16 kg was 0.2–10 g / 10 min;

[0014] The melt flow rate of the PE resin measured at 190℃ and 2.16 kg was 0.2–10 g / 10 min;

[0015] The number-average molecular weight of the PA resin is 10,000 to 30,000.

[0016] Existing patent CN114957851A improves the thermoforming properties of polypropylene materials by adding PE and PA resins. This method improves the compatibility of the three resins by controlling their melt flow rate or number-average molecular weight, causing different types of molecular chains to entangle and hindering their orderly arrangement. This significantly reduces the crystallinity of the polypropylene material, thereby increasing the melt strength of the composite material. However, the significant decrease in crystallinity makes it difficult to improve the flame retardant properties. Furthermore, due to the high melt strength and poor flowability during processing, flame retardants are difficult to disperse effectively, thus limiting the flame retardant performance to 5VA (2.5mm) and resulting in a poor appearance.

[0017] To address the issues of poor flame retardancy and unattractive appearance in the aforementioned specific resin systems, this invention incorporates piperazine pyrophosphate and a small amount of N,N'-ethylene bis-stearamide. The N,N'-ethylene bis-stearamide enables piperazine pyrophosphate to be well dispersed in the aforementioned specific resin system, resulting in a polypropylene composition that maintains good thermoforming properties (high melt strength) while also exhibiting good flame retardancy and a good appearance.

[0018] If N,N'-ethylene bis-stearamide is not used, and other dispersants or lubricants are used instead, the problem of poor flame retardancy and appearance of this particular resin system cannot be effectively improved, and the thermoforming performance of this particular resin system may be significantly deteriorated.

[0019] In this invention, PP resin is used as the main resin, preferably accounting for 35 wt% of the good-looking and flame-retardant polypropylene composition.

[0020] In this invention, the melt flow rate of PP resin can be measured according to ISO 1133-1:2022; the melt flow rate of PE resin can be measured according to ISO 1133-1:2022; and the number-average molecular weight of PA resin can be measured according to ISO 307-2019.

[0021] In this invention, the specific amount of PP resin used can be 55, 58, 60, 62, 65, 68, 70, 72, 75, 78, or 80 parts by weight. The specific amount of PE resin used can be 5, 7, 9, 11, 13, 15, 18, 20, 23, 25, 28, 30, 32, or 35 parts by weight. The specific amount of PA resin used can be 2, 5, 8, 10, 12, 15, 18, or 20 parts by weight. The specific amount of piperazine pyrophosphate used can be 21, 23, 25, 27, 29, or 31 parts by weight; and the specific amount of N,N'-ethylenebisstearamide used can be 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0, or 2.1 parts by weight. The melt flow rate of PP resin measured at 230℃ and 2.16 kg can be 0.2, 0.5, 1, 3, 5, 7, 9, or 10 g / 10 min. The melt flow rate of PE resin measured at 190℃ and 2.16 kg can be 0.2, 0.5, 1, 3, 5, 7, 9, or 10 g / 10 min. The number average molecular weight of PA resin can be 10000, 12000, 15000, 18000, 20000, 23000, 25000, 28000, or 30000.

[0022] Preferably, the good-looking, flame-retardant polypropylene composition comprises the following components in parts by weight:

[0023]

[0024] By controlling the weight ratio of the components, a better-looking and flame-retardant polypropylene composition was obtained, which also had better vacuum forming performance.

[0025] Preferably, the PP resin is at least one of copolymer polypropylene or homopolymer polypropylene.

[0026] Preferably, the PE resin is at least one of high-density polyethylene or low-density polyethylene.

[0027] Preferably, the PA resin is at least one of PA6, PA66, PA11, PA12, PA610, or PA612.

[0028] Preferably, the percentage content of N,N'-ethylene bis-stearamide in the good-looking, flame-retardant polypropylene composition is 0.1-2.5 wt% (specifically, it can be 0.1 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, 2.0 wt%, 2.2 wt%, or 2.5 wt%).

[0029] Preferably, the good-looking, flame-retardant polypropylene composition further includes 0.1 to 2 parts of other additives.

[0030] More preferably, the other additives are at least one of antioxidants or colorants.

[0031] Optionally, the antioxidant includes, but is not limited to, at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] or tris[2,4-di-tert-butylphenyl] phosphite.

[0032] Optionally, the colorant includes, but is not limited to, carbon black.

[0033] The preparation method of the above-mentioned good-looking and flame-retardant polypropylene composition includes the following steps: mixing the components, melt extruding, and granulating to obtain the good-looking and flame-retardant polypropylene composition.

[0034] Preferably, the temperature of the melt extrusion is 150–260°C; the screw length-to-diameter ratio of the extruder for the melt extrusion is 35–62:1, and the screw speed is 300–400 r / min.

[0035] The application of the above-mentioned good-looking and flame-retardant polypropylene composition in the preparation of household goods, electronic components, household appliances, gardening equipment, medical technology equipment, motor vehicle parts or body parts is also within the scope of protection of this invention.

[0036] In particular, the above-mentioned good-looking and flame-retardant polypropylene composition can be used to prepare parts with good thermoforming properties, flame retardant properties and appearance, such as battery top covers and power battery base plates for new energy vehicles, and transfer pallets in the transportation and packaging industries.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] This invention adds piperazine pyrophosphate and a small amount of N,N'-ethylene bis-stearamide to a resin system composed of PP resin, PE resin and PA resin. N,N'-ethylene bis-stearamide can make piperazine pyrophosphate well dispersed in the resin system. The resulting polypropylene composition has good flame retardant properties and good appearance while maintaining good thermoforming properties (high melt strength). Detailed Implementation

[0039] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0040] The reagents used in the various embodiments and comparative examples of this invention are described below:

[0041] PP resin #1: PP B1101, homopolymer polypropylene, Sinopec; melt flow rate is 0.5 g / 10 min;

[0042] PP resin #2: PP M09, copolymer polypropylene, Sinopec, melt flow rate is 9g / 10min;

[0043] PE resin 1#: PE 3518CB; Exxon; low-density polyethylene, melt flow rate of 2.5 g / 10 min;

[0044] PE resin #2: HDPE DMDA8008, Sinopec, high-density polyethylene, melt flow rate is 8g / 10min;

[0045] PA resin 1#: LX245, Luxi Chemical, PA6, number average molecular weight is 16000;

[0046] PA resin 2#: BL3280, Baling Petrochemical, PA6, number average molecular weight is 24000;

[0047] Piperazine pyrophosphate: Commercially available;

[0048] N,N'-Ethylenebis-stearamide: Commercially available;

[0049] Erucamide: Commercially available;

[0050] Polyethylene wax: A-C560A, Honeywell;

[0051] Calcium stearate: Commercially available;

[0052] Pentaerythritol stearate: Commercially available;

[0053] Other adjuvants #1: Antioxidant, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], commercially available;

[0054] Unless otherwise specified, all components used in the parallel examples and comparative examples (e.g., piperazine pyrophosphate, other adjuvants 1#) are the same commercially available products.

[0055] The polypropylene compositions of the embodiments and comparative examples of the present invention were prepared by the following preparation method:

[0056] (1) Weigh each component according to the proportion, put each component into a high-speed mixer, mix them evenly to obtain a mixture.

[0057] (2) The mixture is fed into a twin-screw extruder. The extruder temperature is set sequentially as follows: 190℃, 180℃, 170℃, 160℃, 160℃, 160℃, 230℃, 230℃, 230℃, 230℃, 230℃. The rotation speed is 500 r / min and the screw length-to-diameter ratio is 35:1. After mixing, melting, homogenizing, and extrusion granulation, a polypropylene composition is obtained.

[0058] The polypropylene compositions provided in the embodiments and comparative examples of this invention were subjected to performance testing according to the following test methods:

[0059] 1) Flame retardant performance: Prepare 125mm*13.0mm*2.5mm flame strips and 150mm*150mm*2.5mm square plates according to standard requirements. Test according to UL94. If both the flame strip and the square plate achieve 5VA, the test result is recorded as 5VA; if either the flame strip or the square plate fails to reach 5VA, the test result is recorded as NG.

[0060] 2) Appearance: First, prepare a 2.0mm*60mm*60mm color sample and observe the surface pitting. The pitting should be judged according to the following standards:

[0061] Table 1

[0062]

[0063]

[0064] When the appearance is rated as 1 to 3, the product appearance is considered to be good or above; when the appearance is rated as 4 to 5, the product appearance is considered to be poor.

[0065] 3) Melt strength: A Gottfert "Rheotens" melt strength tester was used. At a set temperature of 180℃, the polymer melt was first extruded downwards from an extruder die equipped with a capillary tube, and simultaneously pulled by two pressure rollers moving in opposite directions on a balance beam. The force exerted on the melt during stretching is a function of the roller speed and time. The rollers rotated at a uniformly accelerated speed until the melt fractured; the force exerted on the melt at this point is defined as the melt strength.

[0066] Examples 1-8

[0067] Examples 1-8 provide a series of polypropylene compositions, the formulations of which are shown in Table 2.

[0068] Table 2. Formulations (parts by weight) for Examples 1-8

[0069]

[0070] Comparative Examples 1-5

[0071] Comparative Examples 1-5 provide a series of polypropylene compositions, the formulations of which are shown in Table 3.

[0072] Table 3 shows the formulations (parts by weight) for Comparative Examples 1–5.

[0073]

[0074] The properties of the polypropylene compositions of each embodiment and comparative example were determined according to the test methods mentioned above, and the test results are shown in Table 4.

[0075] Table 4. Performance test results of the polypropylene compositions in each example and comparative example.

[0076]

[0077]

[0078] As can be seen from Table 4:

[0079] The polypropylene compositions in Examples 1-8 all achieved a flame retardancy rating of 5VA, an appearance rating of 3 or higher, and a melt strength of 43 Pa·s or higher. This indicates that the addition of piperazine pyrophosphate and a small amount of N,N'-ethylene bis-stearamide to the resin system composed of PP, PE, and PA resins in this invention allows piperazine pyrophosphate to be well dispersed in the resin system. The resulting polypropylene compositions maintain good thermoforming properties while also exhibiting good flame retardancy and a good appearance.

[0080] In Comparative Example 1, without the addition of N,N'-ethylenebisstearamide, the resulting polypropylene composition could not achieve a flame retardancy rating of 5VA and had a poor appearance. In Comparative Examples 2-5, the added lubricants or dispersants were unsuitable, resulting in polypropylene compositions that could not achieve a flame retardancy rating of 5VA, had a poor appearance, and low melt strength, especially in Comparative Examples 3 and 5.

[0081] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A good appearance, flame-retardant polypropylene composition, characterized in that, The composition comprises the following components in parts by weight: The measured melt flow rate of the PP resin is 0.2-10 g / 10 min at 230℃ under 2.16 kg. The measured melt flow rate of the PE resin is 0.2-10 g / 10 min at 190℃ under 2.16 kg. The number average molecular weight of the PA resin is 10000-30000.

2. The good appearance, flame-retardant polypropylene composition according to claim 1, characterized in that, The composition comprises the following components in parts by weight:

3. The good appearance, flame-retardant polypropylene composition according to claim 1, characterized in that, The PP resin is at least one of copolymerized polypropylene or homopolymerized polypropylene.

4. The good appearance, flame-retardant polypropylene composition according to claim 1, characterized in that, The PE resin is at least one of high density polyethylene or low density polyethylene.

5. The good appearance, flame-retardant polypropylene composition according to claim 1, characterized in that, The PA resin is at least one of PA6, PA66, PA11, PA12, PA610 or PA612.

6. The good appearance, flame-retardant polypropylene composition according to claim 1, characterized in that, The percentage content of N,N'-ethylene bis-stearamide in the good appearance and flame-retardant polypropylene composition is 0.1-2.5 wt%.

7. The good appearance, flame-retardant polypropylene composition according to claim 1, characterized in that, The good appearance and flame-retardant polypropylene composition further comprises other auxiliary agent 0.1-2 parts.

8. The good appearance, flame-retardant polypropylene composition according to claim 7, characterized in that The other auxiliary agent is at least one of antioxidant or colorant.

9. Process for the preparation of a flame-retardant polypropylene composition with good appearance according to any one of claims 1 to 8, characterized in that, The composition comprises the following steps: mixing the components, melt extruding, granulating, and obtaining the good appearance and flame-retardant polypropylene composition.

10. The use of the good appearance and flame-retardant polypropylene composition according to any one of claims 1-8 in the preparation of household articles, electronic components, household appliances, gardening appliances, medical technology appliances, motor vehicle parts or vehicle body parts.

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