A pp matrix ultrahigh melt mass-flow rate standard sample and a preparation method thereof

Abstract

The application discloses a PP matrix ultrahigh melt mass flow rate standard sample and a preparation method thereof, and belongs to the technical field of thermal standard samples; the PP matrix ultrahigh melt mass flow rate standard sample comprises the following components in parts by mass: 98-99.8 parts of polypropylene resin, 0.1-0.3 parts of a free radical initiator and 0.1-0.3 parts of inorganic fillers; the melt mass flow rate of the PP matrix ultrahigh melt mass flow rate standard sample provided by the application is above 1400 g / 10 min, and there is no significant difference between samples and among samples of the obtained standard sample, namely, the uniformity and stability are excellent; the application provides a standard sample of an ultrahigh melt mass flow rate test system for third-party detection institutions and enterprise laboratories engaged in plastic detection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thermal standard samples, and particularly relates to a PP matrix ultrahigh melt mass flow rate standard sample and a preparation method thereof. BACKGROUND

[0002] Melt mass flow rate is used to evaluate the flowability of a material. The performance represents that the material melts and extrudes through a specified length and diameter of a die under a specified temperature and load, so as to calculate the melt mass flow rate and the melt volume flow rate. The higher the calculated melt mass flow rate is, the better the processing performance of the material is, and vice versa. A melt flow rate instrument is used to evaluate the melt mass flow rate of a material. In order to obtain accurate test results, it is crucial to ensure the test accuracy of the testing machine. This not only needs to periodically calibrate the testing machine, but also needs to supervise and evaluate the state of the detection equipment in real time. The most effective means of real-time evaluation of the state of the equipment is to use standard samples for confirmation. The standard sample can not only evaluate the running state of the equipment, but also help to supervise the testing skills of the testing personnel. At present, there are countless CNAS-recognized laboratories or third-party detection institutions of metrological certification and internal laboratories of enterprises related to materials. If these detection institutions or laboratories want to accurately test the melt mass flow rate, they need corresponding standard samples for effective value and quality monitoring.

[0003] At present, commercially available melt mass flow rate standard samples include PE material (applicable to 190 DEG C), PS material (applicable to 200 DEG C) and PP material (applicable to 230 DEG C). However, the melt mass flow rate standard samples of the PP material mostly concentrate on the melt mass flow rate of 1-10 g / 10 min, and are not suitable for the high melt mass flow rate sample of the PP melt-blown material with a melt mass flow rate of more than 1000 g / 10 min. Therefore, it is urgent to develop a standard substance suitable for high melt mass flow rate.

[0004] There are two common processes for producing ultra-high melt flow rate polypropylene in the prior art, one is to use metallocene catalyst to directly synthesize ultra-high melt flow rate polypropylene material, and the other is to use polypropylene synthesized by conventional Ziegler Natta catalyst as the matrix, add peroxide to degrade, and obtain ultra-high melt flow rate polypropylene by initiating free radical chain scission method; but the metallocene catalyst is expensive and unstable, and the molecular weight is not uniform and the odor is large when the Ziegler Natta catalyst is used. Patent CN1314745C obtains high melt flow rate polypropylene by adding powdered polypropylene and peroxide type degrading agent into a reaction kettle with stirring function to carry out solid phase degradation reaction. But the polypropylene prepared by this method has the disadvantages of unstable melt flow rate of 40-3000g / 10min, wide molecular weight distribution, and more residual degradation agent. Patent CN109503935A obtains a low odor high transparency ultra-high melt flow rate polypropylene by blending extruding polypropylene, peroxide degrading agent and compounded transparent nucleating agent. Patent CN111533999A obtains by adding mixed material 1 including polypropylene particle material, polypropylene powder material, peroxide 1, inorganic powder and antioxidant and mixed material 2 including polypropylene powder material and peroxide through main feeding port and side feeding port into a twin screw extruder for melt blending, which can maintain the reactivity of the whole reaction system and reduce the residual peroxide. But the addition of inorganic powder increases the risk of uneven mixing, and also increases the pre-work, which reduces the production rhythm. The above formulations only prepare high melt flow rate PP resin, but cannot guarantee the stability of high melt flow rate value of the resin for a long time, so it is urgent to develop a process simple and long-term storage stable PP matrix high melt flow rate standard sample. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a PP matrix ultra-high melt flow rate standard sample with excellent stability and a preparation method thereof.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows: a PP matrix ultra-high melt flow rate standard sample, the PP matrix ultra-high melt flow rate standard sample comprises the following components by mass fraction: polypropylene (PP) resin 98-99.8 parts, free radical initiator 0.1-0.3 parts, inorganic filler 0.1-0.3 parts.

[0007] The polypropylene resin is homopolymer isotactic polypropylene resin, the average molecular weight is 0.8x10 5 -8x10 5 g / mol, and the molecular weight distribution coefficient is 3-4.

[0008] The 10h half-life temperature of the free radical initiator is above 80℃.

[0009] The inorganic filler is at least one of nano-aluminum nitride, boron nitride, silicon carbide, and silicon nitride.

[0010] The PP matrix ultrahigh melt mass flow rate standard sample provided by the application selects homopolymer isotactic polypropylene resin with certain average molecular weight and molecular weight distribution coefficient as the matrix, and cooperates with free radical initiators with 10h half-life temperature above 80 DEG C and inorganic fillers, so that the stability of the melt mass flow rate can be maintained on the basis of obtaining ultrahigh melt mass flow rate, and the melt mass flow rate of the obtained standard sample is above 1400 g / 10 min, and there is no significant difference between the samples. Specifically, the homopolymer isotactic polypropylene resin selected by the application has low flow and uniform molecular chain length due to the certain average molecular weight and molecular weight distribution coefficient, so that the relative molecular mass distribution after degradation is narrow, which is helpful for the attack of free radicals; in addition, the free radical initiators selected by the application have high thermal stability and chemical stability due to the 10h half-life temperature above 80 DEG C, so that the stability of the melt mass flow rate of the product can be ensured under long-term storage; at the same time, the inorganic fillers added by the application have high thermal conductivity and strong inertness, so that the product can be uniformly heated, and then the free radical initiators can be uniformly reacted, so that the stability of the melt mass flow rate of the product can be ensured, and the requirements of the standard sample can be met.

[0011] The test method of the average molecular weight and the molecular weight distribution coefficient of the polypropylene resin is to determine the molecular weight distribution and average molecular weight of polyolefin by high-temperature gel permeation chromatography according to the standard ASTM D6474-2012. As a preferred embodiment of the PP matrix ultrahigh melt mass flow rate standard sample, the free radical initiator is at least one of di-t-butyl peroxide, dicumyl peroxide and bis-dipentyl disulfide.

[0012] The 10h half-life temperature of the above-mentioned free radical initiator is above 80 DEG C, specifically, the 10h half-life temperature of di-t-butyl peroxide is 126 DEG C, the 10h half-life temperature of dicumyl peroxide is 117 DEG C, and the 10h half-life temperature of bis-dipentyl disulfide is 115 DEG C.

[0013] As a preferred embodiment of the PP matrix ultrahigh melt mass flow rate standard sample, the PP matrix ultrahigh melt mass flow rate standard sample further comprises the following components in mass fraction: antioxidant 0.0001-0.05 parts, transparent nucleating agent 0.0001-0.15 parts.

[0014] The inventors have found that the addition of antioxidants and transparent nucleating agents can achieve more excellent effects to some extent; wherein the addition of transparent nucleating agents can improve the crystallinity of the matrix, increase the compactness between the molecular chains of the substrate, and further make the performance of the material more stable.

[0015] As a preferred embodiment of the PP matrix ultrahigh melt mass flow rate standard sample of the present application, the antioxidant is a mixture of primary antioxidants and secondary antioxidants in a mass ratio of primary antioxidant: secondary antioxidant = 1: (0.5-2).

[0016] As a preferred embodiment of the PP matrix ultrahigh melt mass flow rate standard sample of the present application, the primary antioxidant is a hindered phenolic antioxidant, and the secondary antioxidant is a phosphite antioxidant.

[0017] As a preferred embodiment of the PP matrix ultrahigh melt mass flow rate standard sample of the present application, the hindered phenolic antioxidant is antioxidant 1010 and / or antioxidant 1076, and the phosphite antioxidant is antioxidant 168 and / or antioxidant 627AV; specifically, antioxidant 1010 is tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, antioxidant 1076 is 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid n-octadecyl ester, antioxidant 168 is tris(2,4-di-tert-butyl) phenyl phosphite, and antioxidant 627AV is a solid organic phosphite antioxidant.

[0018] The inventors have found that when the antioxidant is further preferably the above components and ratios, the stability of the obtained product is more excellent.

[0019] As a preferred embodiment of the PP matrix ultrahigh melt mass flow rate standard sample of the present application, the transparent nucleating agent is a mixture of sorbitol transparent nucleating agents and aryl phosphate transparent nucleating agents in a mass ratio of sorbitol transparent nucleating agent: aryl phosphate transparent nucleating agent = 1: (1-2).

[0020] As a preferred embodiment of the PP matrix ultrahigh melt mass flow rate standard sample of the present application, the sorbitol transparent nucleating agent is 1,3,2,4-dibenzylidene sorbitol, and the aryl phosphate transparent nucleating agent is NA-21 [methylenebis(2,4-di-tert-butylphenyl)] aluminum phosphate.

[0021] In addition, the application further provides a preparation method of the PP matrix ultra-high melt mass flow rate standard sample, which comprises the following steps: uniformly mixing polypropylene resin, transparent nucleating agent and inorganic filler through a high-speed mixer, then feeding the mixed material into a double-screw extruder through a first main feeding, feeding a free radical initiator through a first side feeding, performing double vacuumizing at the sixth section of the double-screw extruder, feeding an antioxidant through a seventh side feeding, and then performing melt extrusion, underwater cutting and air drying to obtain the PP matrix ultra-high melt mass flow rate standard sample.

[0022] As a preferred embodiment of the preparation method, the extrusion parameters are as follows: the length-diameter ratio of the screw is (40-80):1, the extrusion temperature is 80-140 DEG C, the pressure is 12-18 MPa, and the screw rotation speed is 200-800 rpm.

[0023] As a preferred embodiment of the preparation method, the air drying is as follows: first, hot air blowing at 45-55 DEG C for 5.5-6.5 h, and then cold air blowing at 10-20 DEG C for 5.5-6.5 h.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] The PP matrix ultra-high melt mass flow rate standard sample provided by the application selects homopolymer isotactic polypropylene resin with a certain average molecular weight and molecular weight distribution coefficient as the matrix, and further adds a free radical initiator with a 10h half-life temperature of 80 DEG C or above and inorganic filler, and further adds an antioxidant and a transparent nucleating agent, so that the stability of the melt mass flow rate can be maintained on the basis of obtaining an ultra-high melt mass flow rate, the melt mass flow rate of the obtained standard sample is 1400 g / 10 min or above, and there is no significant difference between the samples and between the samples. That is, the application provides a standard sample of an ultra-high melt mass flow rate test system for third-party testing institutions and enterprise laboratories engaged in plastic testing, so that the equipment state, personnel testing level and the like can be accurately confirmed. In addition, in the preparation process, the addition positions of different components are optimized, so that a standard sample with high melt mass flow rate and excellent stability can be obtained through a simple process under the addition of a lower peroxide. DETAILED DESCRIPTION

[0026] For the purpose, technical scheme and advantages of the application, the application will be further described below in combination with specific examples.

[0027] The reagents, methods and equipment used in the application are all conventional reagents, methods and equipment in the field unless otherwise specified; and the components used in the examples and comparative examples are consistent unless otherwise specified.

[0028] The PP resins 1-6 provided by the present application are commercially available, wherein the average molecular weight and the molecular weight distribution coefficient are measured by high temperature gel permeation chromatography according to the standard ASTM D6474-2012.

[0029] PP resin 1: average molecular weight of 3 x 10 5 g / mol, molecular weight distribution coefficient of 3.2, commercially available;

[0030] PP resin 2: average molecular weight of 1 x 10 5 g / mol, molecular weight distribution coefficient of 3.9, commercially available;

[0031] PP resin 3: average molecular weight of 8 x 10 5 g / mol, molecular weight distribution coefficient of 3.5, commercially available;

[0032] PP resin 4: average molecular weight of 10 x 10 5 g / mol, molecular weight distribution coefficient of 3.2, commercially available;

[0033] PP resin 5: average molecular weight of 0.5 x 10 5 g / mol, molecular weight distribution coefficient of 3.2, commercially available;

[0034] PP resin 6: average molecular weight of 3.9 x 10 5 g / mol, molecular weight distribution coefficient of 4.6, commercially available;

[0035] Radical initiator 1: bis-dipentyl sulfide, commercially available;

[0036] Radical initiator 2: di-tert-butyl peroxide, commercially available;

[0037] Radical initiator 3: dicumyl peroxide, commercially available;

[0038] Radical initiator 4: azobis-isobutyronitrile, commercially available;

[0039] Inorganic filler 1: nano-aluminum nitride, commercially available;

[0040] Inorganic filler 2: boron nitride, commercially available;

[0041] Inorganic filler 3: silicon carbide, commercially available;

[0042] Inorganic filler 4: silicon nitride, commercially available;

[0043] Inorganic filler 5: calcium carbonate, commercially available;

[0044] Nucleating agent 1: 1,3,2,4-dibenzylidene sorbitol, commercially available;

[0045] Nucleating agent 2: NA-21 [methylenebis(2,4-di-tert-butylphenyl)] aluminum phosphate, commercially available;

[0046] Antioxidant 1: antioxidant 1010, commercially available;

[0047] Antioxidant 2: antioxidant 1076, commercially available;

[0048] Antioxidant 3: antioxidant 168, commercially available;

[0049] Antioxidant 4: antioxidant 627AV, commercially available.

[0050] Examples 1-6 and Comparative Examples 1-10

[0051] The examples 1-6 and comparative examples 1-10 of the present application provide a PP matrix ultra-high melt mass flow rate standard sample, the component content of which is shown in Table 1-2;

[0052] Table 1

[0053]

[0054] Table 2

[0055]

[0056]

[0057] The preparation method of the PP matrix ultra-high melt mass flow rate standard sample in examples 1-6 and comparative examples 1-10 is as follows: the polypropylene resin is dried at 80℃ for 3h, then the dried polypropylene resin, transparent nucleating agent and inorganic filler are uniformly mixed by a high-speed mixer, and then the mixed material is added into a twin-screw extruder through a first main feeding, and a free radical initiator is added through a first side feeding, double vacuum is performed at the sixth stage of the twin-screw extruder, an antioxidant is added through a seventh side feeding, and then melt extrusion is performed (the process parameters of extrusion are: the length-diameter ratio of the screw is 60:1, the extrusion temperature is 110℃, the pressure is 16MPa, and the screw rotation speed is 500rpm), underwater cutting is performed, and after water cutting, hot air blowing at 50℃ is performed for 6h, and then cold air blowing at 15℃ is performed for 6h, to obtain the PP matrix ultra-high melt mass flow rate standard sample (if there is no relevant component, it is not added).

[0058] Example 7

[0059] The only difference between this embodiment and embodiment 1 is the difference in the preparation method. The preparation process of this embodiment is as follows: the polypropylene resin is dried at 80℃ for 3h, then the dried polypropylene resin, transparent nucleating agent, inorganic filler, free radical initiator and antioxidant are uniformly mixed and then added into a twin-screw extruder, followed by melt extrusion (the process parameters of extrusion are: the length-diameter ratio of the screw is 60:1, the extrusion temperature is 110℃, the pressure is 16MPa, and the screw rotation speed is 500rpm), underwater cutting, and then the cut sample is first blown by hot air at 50℃ for 6h and then blown by cold air at 15℃ for 6h to obtain the PP matrix ultrahigh melt mass flow rate standard sample.

[0060] Effect example

[0061] The performance of the PP matrix ultrahigh melt mass flow rate standard sample prepared in embodiments 1-7 and comparative examples 1-10 is tested for uniformity and stability.

[0062] (1) Uniformity test: the prepared sample is randomly divided into 10 bags, and 1 group of sample is randomly taken from each bag, a total of 10 groups, and each group of sample is repeatedly tested twice, and the uniformity is verified according to the above method. According to CNAS-GL003 “Guidelines for Evaluation of Uniformity and Stability of Proficiency Testing Samples”, the uniformity between samples is tested by single factor variance analysis. If the F value is less than the specified limit value, it indicates that there is no significant difference between the samples and the samples are uniform;

[0063] (2) Stability test: the uniformity test data is taken as one of the average values, and the prepared sample is sealed and stored for 6 months. Then, 10 groups of samples are randomly taken from the sample, and each group of sample is tested twice. The melt mass flow rate of each group of sample is tested, and the average value of the test data is taken as another average value. According to CNAS-GL003 “Guidelines for Evaluation of Uniformity and Stability of Proficiency Testing Samples”, the stability of the sample is tested by the consistency test between the two average values in the t test method. If the t value is less than the specified limit value, it proves that the standard substance has not changed significantly;

[0064] The test method of the above uniformity test and stability test is as follows: the sample is tested according to the requirements of GB / T30923-2014 “Polypropylene (PP) melt blown special material”, and the test conditions are temperature 230℃, load 2.16kg, and melt density value 0.7386g / cm 3 During the test, the material cylinder is purged with nitrogen for 5s-10s before the sample is loaded, and the nitrogen pressure is 0.05MPa. The melt volume flow rate is first tested, and then the melt mass flow rate is calculated using the melt density value. During the test, a half die plug should be used;

[0065] The test results are as follows:

[0066] 1. The homogeneity test results of the PP matrix ultrahigh melt flow rate standard sample prepared in Example 1 are shown in Table 3, the stability test results are shown in Table 4, and the overall evaluation results are shown in Table 5;

[0067] Table 3

[0068]

[0069] Table 4

[0070]

[0071] Table 5

[0072] Stability test total average (g / 10 min) 1498 Homogeneity test total average (g / 10 min) 1497 t-value 1.09 t 0.05 (20+20-2) 1.686

[0073] From Table 3, it can be seen that F < F 0.05 (9,10) = 3.02, indicating that there is no significant difference within and between the samples of Example 1, and the samples are homogeneous. From Tables 4 and 5, it can be seen that t < t 0.05 (20+20-2), indicating that there is no significant difference between the two average values, and the PP matrix ultrahigh melt flow rate standard sample prepared in Example 1 has good stability.

[0074] 2. The F value, overall average value of stability test, overall average value of homogeneity test, and t value of the PP matrix ultrahigh melt flow rate standard sample prepared in Examples 2-7 and Comparative Examples 1-10 are shown in Table 6;

[0075] Table 6

[0076]

[0077]

[0078] From Table 6, it can be seen that when the technical solution of the present application is used, the melt flow rate of the PP matrix ultrahigh melt flow rate standard sample obtained is above 1400 g / 10 min, and the test F < F 0.05 (9,10) = 3.02, t < t 0.05 (20+20-2), indicating that there is no significant difference within and between the PP matrix ultrahigh melt flow rate standard samples prepared by the preparation method of the present application, and the samples are uniform and have good stability;

[0079] In Comparative Examples 1-3, F > F 0.05 (9,10), indicating that there is a significant difference within and between the samples of Comparative Examples 1-3, and t < t 0.05(20+20-2), indicating that the sample stability of Comparative Example 1-3 is good, but the uniformity is poor, indicating that the average molecular weight and molecular weight distribution coefficient of the polypropylene resin will have a significant impact on the uniformity of the product. The reason for the above phenomenon of Comparative Example 3 is that the molecular weight distribution coefficient is large, the relative molecular mass distribution after degradation is wide, and the free radicals will selectively attack, resulting in poor sample uniformity;

[0080] F < F of Comparative Example 4 0.05 (9,10) = 3.02, indicating that there is no significant difference between the samples and between the samples of Comparative Example 4, and the sample is uniform, t < t of Comparative Example 4 0.05 (20+20-2), indicating that there is a significant difference between the two average values of Comparative Example 4, and the standard sample of Comparative Example 4 has poor stability; the reason for the above phenomenon is that the 10h half-life temperature of the free radical initiator selected in Comparative Example 4 is 65℃, and the thermal stability of the material is poor, resulting in unstable melt mass flow rate of the resin;

[0081] F > F of Comparative Examples 6-7 0.05 (9,10), indicating that there is a significant difference between the samples and between the samples of Comparative Examples 6-7, and the melt mass flow rate of the sample in Comparative Example 6 is lower than that of the embodiment, less than 900g / 10min, which is because the amount of free radical initiator added in Comparative Example 6 is too much, resulting in too intense resin degradation reaction, causing the resin degradation product to crosslink with the excess free radical initiator, resulting in low melt flow rate of the resin. At the same time, because this process is difficult to control, the uniformity of the melt mass flow rate of the resin is poor; similarly, if the amount of free radical initiator is too small in Comparative Example 7, the number of free radicals produced is small, which cannot uniformly cover and attack the macromolecules of the resin molecular chain, resulting in poor uniformity of the melt mass flow rate of the resin;

[0082] F > F of Comparative Example 8 0.05 (9,10) = 3.02, indicating that there is a significant difference between the samples and between the samples of Comparative Example 8, and the sample uniformity is poor, t > t of Comparative Example 8 0.05 (20+20-2), indicating that there is a significant difference between the two average values of Comparative Example 8, and the product obtained by Comparative Example 8 has poor stability; the reason for the above phenomenon is that the amount of antioxidant added is too much, and the excess antioxidant captures the free radicals generated by the free radical initiator, resulting in a decrease in the number of free radicals, the number of free radicals attacking the macromolecules of the resin molecular chain decreases, and the melt mass flow rate of the resin is low and unstable;

[0083] F > F of Comparative Examples 5 and 9-10 0.05 (9,10) = 3.02, indicating that there is a significant difference between the samples and between the samples of Comparative Examples 5 and 9-10, and the sample is not uniform, t > t of Comparative Examples 5 and 9-100.05 (20+20-2), which indicates that there is a significant difference between the two average values of Comparative Example 5 and Comparative Examples 9-10, and the standard sample stability of Comparative Example 5 and Comparative Examples 9-10 is poor; the reason for the above phenomenon is that calcium carbonate inorganic filler is added in Comparative Example 5, which cannot achieve the purpose of effective dispersion and uniformity, resulting in no improvement in dispersibility and uneven heating; no inorganic filler is added in Comparative Example 9, which can cause the reaction degree to be different due to uneven heating of the free radical initiator, and the uniformity of the material is poor; and an excessive amount of inorganic filler is added in Comparative Example 10, which can cause uneven dispersion, resulting in uneven reaction of the free radical initiator, and thus the melt flow rate of the material is uneven.

[0084] Finally, it should be noted that the above examples are intended to illustrate the technical solutions of the present application rather than limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A PP matrix ultrahigh melt mass-flow rate standard sample, characterized in that, The PP matrix ultrahigh melt mass flow rate standard sample comprises the following components by mass fraction: polypropylene resin 98-99.8 parts, free radical initiator 0.1-0.3 parts, inorganic filler 0.1-0.3 parts, antioxidant 0.0001-0.05 parts; The polypropylene resin is a homopolymer isotactic polypropylene resin having an average molecular weight of 0.8 x 10 5 -8 x 10 5 g / mol and a molecular weight distribution coefficient of 3-4. The 10h half-life temperature of the free radical initiator is above 80℃. The inorganic filler is at least one of nano-aluminum nitride, boron nitride, silicon carbide, and silicon nitride.

2. The PP matrix ultrahigh melt mass-flow rate standard sample of claim 1, wherein, The free radical initiator is at least one of di-t-butyl peroxide, dicumyl peroxide, and bis-dipentyl sulfide.

3. The PP matrix ultrahigh melt mass-flow rate standard sample of claim 1, wherein, The PP matrix ultrahigh melt mass flow rate standard sample further comprises the following components by mass fraction: transparent nucleating agent 0.0001-0.15 parts.

4. The PP matrix ultrahigh melt mass-flow rate standard sample of claim 3, wherein, The antioxidant is a mixture of primary antioxidant and secondary antioxidant in a mass ratio of primary antioxidant:secondary antioxidant=1:(0.5-2).

5. The PP matrix ultrahigh melt mass-flow rate standard sample of claim 4, wherein, The primary antioxidant is a hindered phenolic antioxidant, and the secondary antioxidant is a phosphite antioxidant.

6. The PP matrix ultrahigh melt mass-flow rate standard sample of claim 5, wherein, The hindered phenolic antioxidant is antioxidant 1010 and / or antioxidant 1076, and the phosphite antioxidant is antioxidant 168 and / or antioxidant 627AV.

7. The PP matrix ultrahigh melt mass-flow rate standard sample of claim 3, wherein, The transparent nucleating agent is a mixture of sorbitol transparent nucleating agent and aryl phosphate transparent nucleating agent in a mass ratio of sorbitol transparent nucleating agent:aryl phosphate transparent nucleating agent=1:(1-2).

8. The PP matrix ultrahigh melt mass-flow rate standard sample of claim 7, wherein, The sorbitol transparent nucleating agent is 1,3,2,4-dibenzyliden sorbitol, and the aryl phosphate transparent nucleating agent is NA-21 [methylenebis(2,4-di-t-butylphenyl)] aluminum phosphate.

9. The method for preparing a PP matrix ultrahigh melt mass-flow rate standard sample according to any one of claims 1-8, wherein, The preparation method comprises the following steps: uniformly mixing polypropylene resin, optional transparent nucleating agent, and inorganic filler by a high-speed mixer, then feeding the mixture into a twin-screw extruder by a first main feeder, feeding the free radical initiator by a first side feeder, performing double vacuuming at the sixth section of the twin-screw extruder, feeding the antioxidant by a seventh side feeder, and then melt extruding, underwater cutting, air drying after water cutting, to obtain the PP matrix ultrahigh melt mass flow rate standard sample.

10. The method of claim 9, wherein, The extrusion parameters are: length-diameter ratio of the screw is (40-80):1, extrusion temperature is 80-140℃, pressure is 12-18 MPa, and screw rotation speed is 200-800 rpm.

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