Flame-retardant polypropylene composition with good appearance as well as preparation method and application thereof

Abstract

The invention relates to a polypropylene composition as well as a preparation method and application thereof. The flame-retardant polypropylene composition with good appearance is prepared from the following components in parts by weight: 55 to 80 parts of PP (Polypropylene) resin, 5 to 35 parts of PE (Polyethylene) resin, 2 to 20 parts of PA (Polyamide) resin, 21 to 31 parts of piperazine pyrophosphate and 0.2 to 2.1 parts of N, N '-ethylene bis stearamide. Piperazine pyrophosphate and a small amount of N, N-dimethyl formamide are added into a resin system composed of PP resin, PE resin and PA resin. According to the polypropylene composition, piperazine pyrophosphate is added into a resin system, N, N '-ethylene bis stearamide is added into the resin system, piperazine pyrophosphate can be well dispersed in the resin system through N, N'-ethylene bis stearamide, and the obtained polypropylene composition also has good flame retardance and good appearance under the condition that good plastic uptake performance is kept.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more specifically to a good-appearance, flame-retardant polypropylene composition, a preparation method and application thereof. Background Art

[0002] Halogen-free flame retardant PP has the advantages of high cost performance, low smoke, low halogen, low specific gravity, etc., and has little impact on the environment. With the increasing awareness of environmental protection, international organizations and governments are promoting the development of halogen-free.

[0003] When PP materials are made into products such as electrical appliances and electronic product shells, due to the large size of these products, they are mainly processed and formed by extrusion board blister process, which has high requirements on the melt strength of PP materials. In addition, the extrusion board blister process also requires PP materials to have good heat resistance.

[0004] Piperazine pyrophosphate is a new type of halogen-free flame retardant. One of its main advantages is good heat resistance, so flame-retardant PP with piperazine pyrophosphate is undoubtedly a good choice for extruded board blister materials. However, piperazine pyrophosphate has poor compatibility with PP resin, and it is difficult for it to play its good flame retardant role in PP resin, and it will have a certain negative impact on the appearance of PP materials.

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

[0006] The primary purpose of the present invention is to overcome the technical problems existing in the current technology and provide a good-looking, flame-retardant polypropylene composition.

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

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

[0009] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0010] A flame-retardant polypropylene composition with good appearance comprises the following components in parts by weight:

[0011]

[0012]

[0013] The melt flow rate of the PP resin measured at 230° C. and 2.16 kg is 0.2 to 10 g / 10 min;

[0014] The melt flow rate of the PE resin measured at 190° C. and 2.16 kg is 0.2 to 10 g / 10 min;

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

[0016] The existing patent CN114957851A improves the blister performance of polypropylene materials by adding PE resin and PA resin. This solution is to improve the compatibility of the three resins by regulating the melt flow rate or number average molecular weight of the three resins, thereby making different types of molecular chains entangled with each other, hindering the orderly arrangement of the molecular chains, greatly reducing the crystallinity of the polypropylene material, and thus improving the melt strength of the polypropylene composite material. Among them, due to the significant decrease in the crystallinity of the material, it is difficult to improve the flame retardant performance of the material; and due to the high melt strength of the material and poor fluidity during processing, it is difficult for the flame retardant to be well dispersed in the material, so the flame retardant performance of the material is difficult to improve to the level of 5VA (2.5mm), and the appearance is also poor.

[0017] In order to solve the problem that the flame retardant properties of the above-mentioned specific resin system are difficult to improve and the appearance is poor, the present invention adds piperazine pyrophosphate and a small amount of N, N'-ethylene bisstearamide. N, N'-ethylene bisstearamide can make piperazine pyrophosphate well dispersed in the above-mentioned specific resin system. The obtained polypropylene composition has good flame retardant properties and good appearance while maintaining good suction molding properties (high melt strength).

[0018] If other dispersants or lubricants are used instead of N,N'-ethylene bisstearamide, the problem of difficulty in improving the flame retardant performance and poor appearance of the specific resin system cannot be effectively improved, and the blister performance of the specific resin system may be significantly deteriorated.

[0019] In the present invention, the PP resin is used as the main resin, and preferably, its content accounts for 35wt% of the good-appearance, flame-retardant polypropylene composition.

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

[0021] In the present invention, the amount of PP resin can be 55, 58, 60, 62, 65, 68, 70, 72, 75, 78 or 80 parts by weight. The amount of PE resin can be 5, 7, 9, 11, 13, 15, 18, 20, 23, 25, 28, 30, 32 or 35 parts by weight. The amount of PA resin can be 2, 5, 8, 10, 12, 15, 18 or 20 parts by weight. The amount of piperazine pyrophosphate can be 21, 23, 25, 27, 29 or 31 parts by weight; the amount of N, N'-ethylene bis stearamide 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 the PP resin measured at 230°C and 2.16 kg may be 0.2, 0.5, 1, 3, 5, 7, 9 or 10 g / 10 min. The melt flow rate of the PE resin measured at 190°C and 2.16 kg may be 0.2, 0.5, 1, 3, 5, 7, 9 or 10 g / 10 min. The number average molecular weight of the PA resin may be 10,000, 12,000, 15,000, 18,000, 20,000, 23,000, 25,000, 28,000 or 30,000.

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

[0023]

[0024] By adjusting the weight proportions of the components, the obtained good-appearance and flame-retardant polypropylene composition has a better appearance and better blister performance.

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

[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 of N,N'-ethylene bisstearamide in the good appearance and flame retardant polypropylene composition is 0.1-2.5wt% (specifically 0.1wt%, 0.4wt%, 0.6wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2.0wt%, 2.2wt%, 2.5wt%).

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

[0030] More preferably, the other auxiliary agent is at least one of an antioxidant or a colorant.

[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 method for preparing the above-mentioned good-appearance, flame-retardant polypropylene composition comprises the following steps: mixing the components, melt-extruding, and granulating to obtain the good-appearance, flame-retardant polypropylene composition.

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

[0035] The use of the good appearance and flame retardant polypropylene composition in the preparation of household items, electronic components, household appliances, gardening equipment, medical technology equipment, motor vehicle parts or body parts is also within the protection scope of the present invention.

[0036] In particular, the good appearance and flame retardant polypropylene composition can be used to prepare parts with good blister performance, flame retardant performance and appearance, such as battery cover plates and power battery bottom plates of new energy vehicles, transfer pallets in transportation and packaging industries, etc.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention adds piperazine pyrophosphate and a small amount of N, N'-ethylene bisstearamide to a resin system composed of PP resin, PE resin and PA resin. The N, N'-ethylene bisstearamide can make the piperazine pyrophosphate well dispersed in the resin system. The obtained polypropylene composition has good flame retardant performance and good appearance while maintaining good suction plastic performance (high melt strength). DETAILED DESCRIPTION

[0039] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0040] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows:

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

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

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

[0044] PE resin 2#: HDPE DMDA8008, Sinopec, high-density polyethylene, melt flow rate 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'-ethylene bisstearamide: commercially available;

[0049] Erucic acid amide: commercially available;

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

[0051] Calcium stearate: commercially available;

[0052] Pentaerythritol stearate: commercially available;

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

[0054] Unless otherwise specified, the components (eg, piperazine pyrophosphate, other auxiliary agent 1#) selected in each parallel example and comparative example are the same commercially available products.

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

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

[0057] (2) The mixture is fed into a twin-screw extruder, and the temperature of the extruder is set to 190° C., 180° C., 170° C., 160° C., 160° C., 160° C., 230° C., 230° C., 230° C., 230° C., 230° C., the rotation speed is 500 r / min, and the aspect ratio of the screw is 35:1; the polypropylene composition is obtained by mixing, melting, homogenizing, and then extruding and granulating.

[0058] The properties of the polypropylene compositions provided in the embodiments and comparative examples of the present invention were measured according to the following test methods:

[0059] 1) Flame retardant performance: According to the standard requirements, a 125mm*13.0mm*2.5mm burning strip and a 150mm*150mm*2.5mm square plate are prepared. According to UL94, if both the burning strip and the square plate can reach 5VA, the test result is recorded as 5VA; if one of the burning strip and the square plate cannot reach 5VA, the test result is recorded as NG:

[0060] 2) Appearance: First prepare a 2.0mm*60mm*60mm color plate and observe the pitting on the surface of the color plate. The pitting is judged according to the following standards:

[0061] Table 1

[0062]

[0063]

[0064] Among them, 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: The Gottfert "Rheotens" melt strength tester is used for testing. Under the condition of setting the temperature at 180°C, the polymer melt is first extruded downward from the extruder die equipped with a capillary, and at the same time, it is pulled by two rollers with opposite movement directions installed on the balance beam. The force on the melt when it is stretched is a function of the speed and time of the rollers. The rollers rotate evenly and accelerate until the melt breaks. At this time, the force on the melt when it breaks is defined as the melt strength.

[0066] Examples 1 to 8

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

[0068] Table 2 Formulas of Examples 1 to 8 (parts by weight)

[0069]

[0070] Comparative Examples 1 to 5

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

[0072] Table 3 Formulas of Comparative Examples 1 to 5 (parts by weight)

[0073]

[0074] The properties of the polypropylene compositions of the embodiments and comparative examples were measured according to the above-mentioned test methods. The test results are shown in Table 4.

[0075] Table 4 Performance test results of polypropylene compositions of various embodiments and comparative examples

[0076]

[0077]

[0078] From Table 4, we can see that:

[0079] The flame retardant grade of the polypropylene compositions of Examples 1 to 8 all reaches 5VA, the appearance is all above level 3, and the melt strength is all above 43Pa.S, indicating that in the present invention, piperazine pyrophosphate and a small amount of N,N'-ethylene bisstearamide are added to the resin system composed of PP resin, PE resin and PA resin. N,N'-ethylene bisstearamide can make piperazine pyrophosphate well dispersed in the resin system. The obtained polypropylene composition has good flame retardant properties and good appearance while maintaining good suction molding properties.

[0080] Comparative Example 1 does not add N,N'-ethylene bisstearamide, and the flame retardant grade of the obtained polypropylene composition cannot reach 5VA, and the appearance is poor. Comparative Examples 2 to 5 add inappropriate lubricants or dispersants, and the flame retardant grade of the obtained polypropylene composition cannot reach 5VA, the appearance is poor, and the melt strength is low, especially the melt strength of 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 embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope 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 melt flow rate of the PP resin measured at 230° C. and 2.16 kg is 0.2 to 10 g / 10 min; The melt flow rate of the PE resin measured at 190° C. and 2.16 kg is 0.2 to 10 g / 10 min; The number average molecular weight of the PA resin is 10,000 to 30,000.

2. The good appearance and 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 and flame retardant polypropylene composition according to claim 1, characterized in that: The PP resin is at least one of copolymer polypropylene or homopolymer polypropylene.

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

7. The good appearance and flame retardant polypropylene composition according to claim 1, characterized in that: The good-appearance, flame-retardant polypropylene composition also includes 0.1 to 2 parts of other additives.

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

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

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

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