A low-temperature high-impact polypropylene alloy and preparation method thereof

Abstract

The present invention discloses a low-temperature high-impact polypropylene alloy and a preparation method thereof, comprising the following components in parts by weight: polypropylene: 50-90 parts by weight; ethylene-propylene rubber: 5-35 parts by weight; thermoplastic elastomer: 5-35 parts by weight; and may contain a small amount of antioxidant. The Mooney viscosity range of ethylene-propylene rubber is ML (1+4) 100℃=40~60. The EPDM rubber with Mooney viscosity in this preferred range has the best low-temperature toughening effect. The present invention selects the Mooney viscosity range of the EPDM rubber with the best low-temperature impact resistance. While keeping the amount of rubber unchanged, the Mooney viscosity of the rubber is changed to reduce the brittle-tough transition temperature of the material from -30℃ to -70℃. The technical solution of the present invention is simple and can significantly improve the low-temperature toughness of the material without increasing the cost.

Description

Technical Field

[0001] The invention relates to a low-temperature high-impact polypropylene alloy and a preparation method thereof. Background Art

[0002] Polypropylene (PP) has the advantages of light weight, environmental protection, non-toxicity, and good comprehensive performance. It is widely used in home appliances, automobiles, daily necessities, chemicals and other fields. However, due to its molecular structure, PP is brittle, especially under low temperature (or high speed) impact conditions, it is prone to brittle failure, which limits its application in certain scenarios. Therefore, PP needs to be toughened and modified. Commonly used toughening methods include: adding elastomer toughening agents, adding inorganic particle toughening agents, β-nucleating agent toughening, dynamic vulcanization toughening, etc. Compared with room temperature toughening, improving the low temperature toughness of PP has greater technical challenges.

[0003] Patents CN104592630A and Polymer 112 (2017) 318-324 disclose a method of using EPDM and SEP to jointly toughen PP. This method uses SEP as a low-temperature toughening agent and combines it with EPDM as a room-temperature toughening agent to perform composite toughening on PP. The results show that the modified PP prepared by this method has a brittle-tough transition temperature as low as -30°C. Compared with other disclosed low-temperature toughening methods, this method significantly improves the low-temperature toughness of PP. However, for applications under extreme conditions, the PP alloy prepared by the above method exhibits a low-temperature toughness of about 20kJ / m at -30°C. 2 The notched impact strength of the material still needs to be improved. To this end, the most direct method is to continue to increase the elastomer content in the material, but this will inevitably lead to a further reduction in the rigidity and strength of the material, which cannot meet the comprehensive requirements of the material use.

[0004] CN116656041A discloses a dynamically vulcanized low-temperature-resistant high-impact polypropylene alloy and its preparation method. SEP and / or SEPS are used with EPDM ternary rubber to toughen PP, and phenolic resin is used to dynamically vulcanize EPDM ternary rubber, which can effectively reduce the amount of elastomer, improve the strength of the material, and balance the low-temperature toughness and strength of the material. However, the addition of phenolic resin will make the material yellow; at the same time, the hygroscopic property of phenolic resin will make it easy to agglomerate on the inner wall, corners, etc. of the production and processing equipment, thereby affecting the feed ratio and ultimately affecting the product performance.

[0005] To this end, if the raw materials, especially the elastomers that directly play a toughening role, can be optimized and screened without changing the material composition, and the physical parameters that control the toughening efficiency of the elastomers can be found, the low-temperature toughness of the material can be further improved without increasing the amount of elastomer used, thereby optimizing the comprehensive performance of the material. Summary of the invention

[0006] Based on the published literature (CN104592630A and Polymer 112 (2017) 318-324), the present invention optimizes and screens the toughening elastomer EPDM used, and provides the Mooney viscosity range of EPDM with the best low-temperature toughening efficiency, ML (1+4) 100℃=40~60. By using EPDM rubber in this Mooney viscosity range, the brittle-tough transition temperature of the material can be reduced from -30℃ to -70℃ without increasing the amount of elastomer used, which significantly improves the comprehensive performance of the material and hardly increases the material cost.

[0007] The technical solution adopted by the present invention is:

[0008] A low-temperature high-impact polypropylene alloy, the material comprising the following components in parts by weight:

[0009] Polypropylene: 50-90 parts by weight

[0010] Ethylene propylene rubber: 5-35 parts by weight

[0011] Thermoplastic elastomer: 5-35 parts by weight;

[0012] The Mooney viscosity of the EPDM rubber is ML (1+4) 100℃=40~60, it can be a mixture of one or several EPDM rubbers.

[0013] Further, the Mooney viscosity ML of the EPDM rubber is preferably (1+4) 100℃=50, which has the best low-temperature toughening efficiency.

[0014] The ethylene-propylene rubber may be ethylene-propylene-diene rubber (EPM) or ethylene-propylene-diene rubber (EPDM), as long as the Mooney viscosity of the ethylene-propylene rubber is within the range defined in the present invention.

[0015] The thermoplastic elastomer is one or both of styrene-hydrogenated isoprene copolymer (SEP) and styrene-hydrogenated isoprene-styrene copolymer (SEPS).

[0016] The polypropylene alloy may also contain a small amount of antioxidant, the amount of antioxidant used is 0-10 parts by weight, wherein 0 represents being infinitely close to 0 but not 0.

[0017] The antioxidant is preferably one of antioxidant 1010 or antioxidant 1076 or a mixture of both.

[0018] Preferably, the low temperature and high impact polypropylene alloy is composed of the following components in parts by weight:

[0019] Polypropylene: 50-70 parts by weight

[0020] Ethylene propylene rubber: 15-30 parts by weight, Mooney viscosity is ML (1+4) 100℃=40~60

[0021] Thermoplastic elastomer: 10-30 parts by weight

[0022] Antioxidant: 0.01-5 parts by weight

[0023] Further, more preferably, the low temperature and high impact polypropylene alloy is composed of the following components in parts by weight:

[0024] Polypropylene: 50-60 parts by weight

[0025] Ethylene propylene rubber: 20-25 parts by weight, Mooney viscosity is ML (1+4) 100℃=40~60

[0026] Thermoplastic elastomer: 15-25 parts by weight

[0027] Antioxidant: 0.01-1 parts by weight.

[0028] The low-temperature high-impact polypropylene alloy provided by the present invention has a brittle-to-tough transition temperature of -70°C and a notched impact strength of more than 70 kJ / m at -40°C. 2 , -50℃ notched impact strength greater than 50kJ / m 2 , -60℃ notched impact strength greater than 20kJ / m 2 , -70℃ notched impact strength greater than 15kJ / m 2 .

[0029] The present invention also provides a method for preparing the low-temperature high-impact polypropylene alloy, which comprises:

[0030] The raw materials are mixed evenly in a high-speed mixer according to the formula ratio and then added to the feeding port of a twin-screw extruder, or a twin-screw extruder with a separate metering system is used to continuously feed the components into the feeding port of the extruder according to the formula ratio, and extruded into granules at a temperature of 90-230°C.

[0031] Furthermore, the preferred typical extrusion process is: conveying section temperature 90-180°C, melting section temperature 140-230°C, homogenizing section temperature 160-230°C, die temperature 160-230°C, and screw speed 200-500rpm.

[0032] The beneficial effects of the present invention are:

[0033] After a large number of screenings, the present invention found that the low-temperature toughness is affected by the Mooney viscosity of the EPDM rubber. The Mooney viscosity of the EPDM rubber used was screened to screen out the Mooney viscosity range of the EPDM rubber with the best low-temperature impact resistance. (1+4)100℃=40~60 EPDM as a toughening agent can show a low-temperature toughening effect far superior to other EPDM with Mooney viscosity. Without changing the composition and keeping the amount of rubber unchanged, changing the Mooney viscosity of the EPDM raw material can reduce the brittle-tough transition temperature of the material from -30℃ to -70℃, significantly improving the comprehensive performance of the material while hardly increasing the material cost. The technical solution of the present invention is simple. Since the amount of elastomer is not increased, the material can maintain rigidity without loss while significantly improving the low-temperature toughness, thus achieving a balance between the strength and toughness of the material. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

[0035] Examples 1 to 5

[0036] The physical properties of the ethylene-propylene rubber used in the following examples are shown in Table 1:

[0037] Table 1

[0038]

[0039]

[0040] The formulations of Examples 1 to 5 are shown in Table 2 below:

[0041] Table 2

[0042] Raw material composition Polypropylene EPDM Thermoplastic elastomer Antioxidant 1010 Example 1 55 parts by weight 25 parts by weight EPM-1 20 parts by weight SEP 0.2 parts by weight Example 2 55 parts by weight 25 parts by weight EPM-2 20 parts by weight SEP 0.2 parts by weight Example 3 55 parts by weight 25 parts by weight EPM-3 20 parts by weight SEP 0.2 parts by weight Example 4 55 parts by weight 25 parts by weight EPM-4 20 parts by weight SEP 0.2 parts by weight Example 5 55 parts by weight 25 parts by weight EPDM-1 20 parts by weight SEP 0.2 parts by weight

[0043] The preparation methods of each embodiment are as follows:

[0044] A twin-screw extruder with separate metering is used, and 55 parts by weight of polypropylene, 25 parts by weight of ethylene-propylene rubber, 20 parts by weight of thermoplastic elastomer and 0.2 parts by weight of antioxidant are fed into the feeding port of the twin-screw extruder according to metering; the extrusion conditions are as follows: a conveying section temperature of 90 to 150° C., a melting section temperature of 160 to 180° C., a homogenizing section temperature of 190 to 200° C., a die temperature of 180° C., and a screw speed of 300 rpm.

[0045] The material properties obtained in the above examples 1 to 5 are shown in Table 3 below:

[0046] Table 3

[0047]

[0048]

[0049] From the test results of each embodiment in Table 3, it can be seen that when the composition remains unchanged, the Mooney viscosity ML (1+4)100℃=50 EPDM has the best low temperature toughening efficiency, which can reduce the brittle-to-ductile transition temperature of the material to -70℃. The material can still maintain 20kJ / m at -70℃ 2 The notched impact strength of the composite material is excellent in low-temperature toughness. At the same time, since the material composition is not changed, the bending strength and bending modulus of the sample are not much different. And from the data in Table 3, it can be seen that the Mooney viscosity and low-temperature toughness are not linearly correlated. From the data in Examples 1 to 3, the Mooney viscosity increases from 8 to 30, and the low-temperature toughness decreases instead. In the range of 40 to 60, it has the best low-temperature toughening effect, and then after the Mooney viscosity is greater than 60, the toughening effect suddenly decreases. In addition, it can be seen from Examples 2 to 4 that the molecular composition of the three raw materials EPM is the same, and the ethylene content is 50%, but the Mooney viscosity is 10, 30, and 50 respectively, but the low-temperature toughness data results are quite different and do not have a linear correlation. Therefore, it is believed that the performance difference of low-temperature toughness is mainly affected by the Mooney viscosity, and has nothing to do with the composition and molecular structure of the EPDM rubber material. Only under a specific Mooney viscosity can the best low-temperature toughening effect be achieved. The reason for this is not clear at present, but it has been verified by a large number of experiments by the inventor.

[0050] Further comparison with CN104592630A and Polymer 112 (2017) 318-324 shows that the material prepared by the technical solution of the present invention can significantly improve the low-temperature toughness of the material without increasing the amount of rubber. Not increasing the amount of rubber means that the rigidity of the material is not lost and the cost of raw materials does not increase, which has a strong positive value for improving the comprehensive competitiveness of the material.

Claims

1. A low temperature and high impact polypropylene alloy, characterized in that The low temperature and high impact polypropylene alloy comprises the following components in parts by weight: Polypropylene: 50-90 parts by weight Ethylene propylene rubber: 5-35 parts by weight Thermoplastic elastomer: 5-35 parts by weight; the thermoplastic elastomer is one or both of styrene-hydrogenated isoprene copolymer and styrene-hydrogenated isoprene-styrene copolymer; The Mooney viscosity of the EPDM rubber is ML (1+4) 100℃=40~60.

2. The low temperature high impact polypropylene alloy according to claim 1, characterized in that The Mooney viscosity ML of the EPDM rubber (1+4) 100℃=50。 3. The low temperature high impact polypropylene alloy according to claim 1, characterized in that The polypropylene alloy includes an antioxidant, and the amount of the antioxidant is 0-10 parts by weight.

4. The low temperature high impact polypropylene alloy according to claim 1, characterized in that The low temperature and high impact resistant polypropylene alloy is composed of the following components in parts by weight: Polypropylene: 50-70 parts by weight Ethylene propylene rubber: 15-30 parts by weight, Mooney viscosity is ML (1+4) 100℃=40~60 Thermoplastic elastomer: 10-30 parts by weight Antioxidant: 0.01-5 parts by weight.

5. The low temperature high impact polypropylene alloy according to claim 1, characterized in that The low temperature and high impact resistant polypropylene alloy is composed of the following components in parts by weight: Polypropylene: 50-60 parts by weight Ethylene propylene rubber: 20-25 parts by weight, Mooney viscosity is ML (1+4) 100℃=40~60 Thermoplastic elastomer: 15-25 parts by weight Antioxidant: 0.01-1 parts by weight.

6. The method for preparing the low temperature high impact polypropylene alloy according to any one of claims 1 to 5, characterized in that The method is: The raw materials are mixed evenly in a high-speed mixer according to the formula ratio and then added to the feeding port of a twin-screw extruder, or a twin-screw extruder with a separate metering system is used to continuously feed the components into the feeding port of the extruder according to the formula ratio, and extruded into granules at a temperature of 90-230°C.

7. The method according to claim 6, characterized in that The extrusion process is as follows: the temperature of the conveying section is 90-180°C, the temperature of the melting section is 140-230°C, the temperature of the homogenizing section is 160-230°C, the temperature of the die is 160-230°C, and the screw speed is 200-500rpm.

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