Polypropylene composite material with multi-scale structure dispersed phase and preparation method of polypropylene composite material

Abstract

The invention belongs to the technical field of high polymer materials, and particularly discloses a polypropylene composite material with a multi-scale structure dispersed phase and a preparation method of the polypropylene composite material, the dispersed phase of the polypropylene composite material is a composite dispersed phase and is in a submicron or micron scale, and the polypropylene composite material has a polystyrene nanophase region and a nanoscale silicon dioxide phase region at the same time; comprising the following components in parts by weight: 60-80 parts of polypropylene; 5 to 15 parts of a block copolymer elastomer; 15 to 30 parts of ethylene propylene rubber; 5 to 15 parts of nano rigid particles; and 1-2 parts of an antioxidant. According to the polypropylene composite material with the multi-scale structure dispersed phase and the preparation method of the polypropylene composite material, the problem of poor low-temperature toughness of a general polypropylene composite material is solved by using a simple physical blending method, so that the current industry requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a polypropylene composite material with a multi-scale structure dispersed phase and a preparation method thereof. Background Art

[0002] Polypropylene is widely used in daily life because of its inert molecular chain structure and semi-crystalline properties, excellent mechanical properties, heat resistance and chemical corrosion resistance. However, although in theory the yield process of polypropylene materials precedes fracture, the toughness of polypropylene parts of a certain size is poor due to the poor resistance to crack propagation of polypropylene materials, which limits the application of polypropylene materials under a wider range of conditions. Especially in low-temperature or high-speed scenarios, the toughness of polypropylene materials decreases significantly because the movement of molecular chains is further restricted. How to efficiently improve the low-temperature toughness of polypropylene materials while taking into account the strength of the material is an urgent problem that researchers need to solve.

[0003] Physical blending is the simplest and most effective method for modifying polypropylene materials. Traditional physical toughening methods generally use the addition of rubber, inorganic particles, β-nucleating agents or multiple combinations of these methods. However, the effects obtained by these methods are relatively simple and often depend on the content of toughening agents added. At the same time, toughening is accompanied by serious performance losses (such as modulus, strength, etc.). Superimposing these methods can obtain better room temperature toughening effects, but the effect of improving low temperature toughness is not significant.

[0004] Some emerging physical methods can effectively toughen polypropylene at low temperatures by designing the structure of the dispersed phase. For example, the invention patent with patent number CN113912948A reports a polypropylene nanocomposite material containing a synergistic effect of an elastomer and nanoparticles. This type of polypropylene composite material is designed to disperse nano rigid particles around the dispersed phase in a directional manner to form a shell layer, effectively increase interface loss, absorb energy, and thus achieve low temperature toughening. The invention patent with patent number CN116355312A innovatively reports a polypropylene composite material with added plastic (high-density polyethylene) and combined with a composite rubber strategy. The high-density polyethylene (HDPE) is directional distributed around the rubber phase to form a shell layer, which effectively improves the low-temperature toughness of the polypropylene material. In addition, in related studies, creating a "soft shell-hard shell" structure Polymer65 (2015) 81-92 or a "multi-hard core structure" RSC Advances 5 (2015) 14592-14602 both promote the toughness of the material.

[0005] In summary, by constructing a special dispersed phase structure, such as creating a "core-shell" dispersed phase structure, the low-temperature impact resistance of polypropylene materials can be effectively improved. However, to construct this special dispersed phase, it is necessary to screen the materials used so that they have matching interface properties in order to form an ordered and stable dispersed phase structure. Therefore, the progress of related research is still slow, and the improvement of toughening theory awaits more reports on new structures or methods that are conducive to low-temperature toughening. Summary of the invention

[0006] The purpose of the present invention is to provide a polypropylene composite material with a multi-scale structure dispersed phase and a preparation method thereof, which solves the problem of poor low-temperature toughness of general polypropylene composite materials by a simple physical blending method, in order to meet the current industry needs.

[0007] To achieve the above object, the present invention provides a polypropylene composite material with a multi-scale structure dispersed phase, wherein the dispersed phase of the polypropylene composite material is a composite dispersed phase and is of submicron or micron scale, and has a polystyrene nanophase region and a nanoscale silica phase region, and comprises the following components in parts by weight:

[0008] Polypropylene: 60-80 parts;

[0009] Block copolymer elastomer: 5-15 parts;

[0010] EPDM rubber: 15-30 parts;

[0011] Nano rigid particles: 5-15 parts;

[0012] Antioxidant: 1-2 parts.

[0013] Preferably, the block copolymer elastomer is a styrene-ethylene-propylene-styrene copolymer or a styrene-ethylene-propylene copolymer, and the styrene content is 30%.

[0014] Preferably, the antioxidant is one or more of antioxidant 1010, antioxidant 168, and antioxidant 1076.

[0015] Preferably, the nano-rigid particles are nano-sized fumed silica with a size of 10-15 nm.

[0016] A method for preparing a polypropylene composite material with a multi-scale structure dispersed phase comprises the following steps:

[0017] S1: firstly, the block copolymer elastomer, EPDM rubber, nano rigid particles and part of the antioxidant are added into an internal mixer and mixed for 10-20 minutes at a temperature of 160°C and a rotation speed of 50 rpm to obtain a composite rubber with a multi-scale nano-scale microstructure;

[0018] S2: Then, polypropylene, the composite rubber obtained in step S1, and the remaining antioxidant are added into an internal mixer and mixed for 10-15 minutes at a temperature of 180-200° C. and a rotation speed of 50-80 rpm to obtain a masterbatch;

[0019] S3: granulating the masterbatch obtained in step S2;

[0020] S4: adding the pellets in step S3 into an injection molding machine for injection molding, wherein the temperature of the injection molding machine is set as follows: first stage 190-210°C; second stage 190-210°C; third stage 190-210°C; and head 190-210°C; obtaining a polypropylene composite material with a multi-scale structure dispersed phase.

[0021] Preferably, in step S1, the composite rubber has the following nanoscale microstructure: a polystyrene nanophase region formed by phase separation of the block copolymer elastomer itself, with a size of 30-50 nm, and a nanoscale silica phase region formed by uniform dispersion of nano rigid particles, with a size of 10-15 nm.

[0022] The advantages and beneficial effects of the polypropylene composite material with a multi-scale structure dispersed phase and the preparation method thereof of the present invention are:

[0023] 1. The present invention utilizes a simple physical blending method, utilizes the microphase separation of the block copolymer elastomer itself and its excellent compatibility with EPDM, and regulates the block copolymer elastomer to form a uniform polystyrene phase region in EPDM. At the same time, in the process of preparing the composite rubber by the blending process, the above-mentioned polystyrene phase region promotes the uniform dispersion of nano-silicon dioxide, forming a multi-scale "double network" structure of a polystyrene microphase network and a nano-silicon dioxide particle network, which has a unique stability. Therefore, after the subsequent secondary blending of the composite rubber and polypropylene, the dispersed phase has a multi-scale phase structure. During the impact process, this dispersed phase structure can effectively cavitate and produce microcracks due to the presence of EPDM molecular chains, but the cross-scale development of microcracks is subject to multiple restrictions of the multi-scale structure. This process ensures the absorption of a large amount of energy and more effectively induces the shear yield of the polypropylene matrix, greatly improving the low-temperature toughness of the polypropylene composite material.

[0024] 2. The present invention makes silica uniformly dispersed in the composite rubber phase, anchors it in the dispersed phase region through a multi-scale "double network" structure, and limits the aggregation of nano silica at the phase interface, achieving a similar "chemical cross-linking" effect by physical means. The uniformly distributed silica nanoparticles can better inhibit the expansion of microcracks and disperse stress. In addition, compared with the same type of polypropylene nanocomposite prepared by physical blending, the present invention has a higher toughening efficiency, and the amount of nano silica used to achieve effective low-temperature toughening is lower.

[0025] 3. The dispersed phase structure proposed in the present invention has good stability and the advantage of repeatable processing.

[0026] 4. The present invention can achieve the regulation of low-temperature toughness of polypropylene composite materials without increasing the rubber content, and can achieve low-temperature toughening of polypropylene composite materials at lower rubber component content and lower nanoparticle content.

[0027] 5. The present invention can maintain the tensile strength of the polypropylene composite material at about 20 MPa.

[0028] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a microscopic observation picture of the dispersed phase of the polypropylene composite material of the present invention by transmission electron microscope (TEM); wherein A is comparative example 1, B is example 2, C is example 3, and D is example 3 dyeing;

[0030] Figure 2 It is a microscopic observation picture of the dispersed phase of the composite rubber by transmission electron microscope (TEM) of the present invention; wherein A is comparative example 1, B is example 3, and C is example 3 dyed. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0032] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0033] Example 1

[0034] A polypropylene composite material with a multi-scale structure dispersed phase, wherein the dispersed phase of the polypropylene composite material is a composite dispersed phase and is of submicron or micron scale, and has a polystyrene nanophase region and a nano-scale silicon dioxide phase region, and is composed of the following materials in parts by weight:

[0035] Polypropylene: 70 parts by weight;

[0036] Block copolymer elastomer (SEPS): 5 parts by weight, the block copolymer elastomer is styrene-ethylene-propylene-styrene copolymer, and the styrene content is 30%;

[0037] EPDM rubber: 25 parts by weight;

[0038] Nano rigid particles: 10 parts by weight, the nano rigid particles are nano-grade fumed silica with a size of 10-15 nm;

[0039] Antioxidant: 2 parts, the antioxidant is antioxidant 1010.

[0040] A method for preparing a polypropylene composite material with a multi-scale structure dispersed phase comprises the following steps:

[0041] S1: firstly, block copolymer elastomer, EPDM rubber, nano rigid particles, and part of antioxidant were added into an internal mixer and mixed for 15 minutes at a temperature of 160°C and a rotation speed of 50 rpm to obtain a composite rubber with a multi-scale nano-scale microstructure;

[0042] S2: Then, polypropylene, the composite rubber obtained in step S1, and the remaining antioxidant are added to an internal mixer and mixed for 10 minutes at a temperature of 180° C. and a rotation speed of 50 rpm to obtain a masterbatch;

[0043] S3: Granulating the mixed material obtained in step S2;

[0044] S4: adding the pellets in step S3 into an injection molding machine for injection molding, wherein the temperature of the injection molding machine is set to: 190°C for the first stage, 190°C for the second stage, 190°C for the third stage, and 190°C for the head; and obtaining a polypropylene composite material with a multi-scale structure dispersed phase.

[0045] Example 2

[0046] A polypropylene composite material with a multi-scale structure dispersed phase, comprising the following materials in parts by weight:

[0047] Polypropylene: 70 parts by weight;

[0048] Block copolymer elastomer (SEPS): 10 parts by weight, the block copolymer elastomer is a styrene-ethylene-propylene copolymer, and the styrene content is 30%;

[0049] EPDM rubber: 20 parts by weight;

[0050] Nano rigid particles: 10 parts by weight, the nano rigid particles are nano-grade fumed silica with a size of 10-15 nanometers;

[0051] Antioxidant: 2 parts, the antioxidant is antioxidant 168.

[0052] A method for preparing a polypropylene composite material with a multi-scale structure dispersed phase comprises the following steps:

[0053] S1: firstly, block copolymer elastomer, EPDM rubber, nano-fumed silica, and part of antioxidant were added into an internal mixer and mixed for 15 minutes at a temperature of 160°C and a rotation speed of 50 rpm to obtain a composite rubber with a multi-scale nano-scale microstructure;

[0054] S2: Then, polypropylene, the composite rubber obtained in step S1, and the remaining antioxidant are added into an internal mixer and mixed for 10 minutes at a temperature of 180° C. and a rotation speed of 50 to obtain a masterbatch;

[0055] S3: Granulating the mixed material obtained in step S2;

[0056] S4: adding the pellets in step S3 into an injection molding machine for injection molding, wherein the temperature of the injection molding machine is set as follows: 200°C for the first stage, 200°C for the second stage, 200°C for the third stage, and 200°C for the head; obtaining a polypropylene composite material with a multi-scale structure dispersed phase.

[0057] Example 3

[0058] A polypropylene composite material with a multi-scale structure dispersed phase, comprising the following materials in parts by weight:

[0059] Polypropylene: 70 parts by weight;

[0060] Block copolymer elastomer (SEPS): 15 parts by weight, the block copolymer elastomer is styrene-ethylene-propylene-styrene copolymer, and the styrene content is 30%;

[0061] EPDM rubber: 15 parts by weight;

[0062] Nano rigid particles: 10 parts by weight, the nano rigid particles are nano-grade fumed silica with a size of 10-15 nm;

[0063] Antioxidant: 2 parts, the antioxidant is antioxidant 1076.

[0064] A method for preparing a polypropylene composite material with a multi-scale structure dispersed phase comprises the following steps:

[0065] S1: firstly, block copolymer elastomer, EPDM rubber, nano-fumed silica, and part of antioxidant were added into an internal mixer and mixed for 15 minutes at a temperature of 160°C and a rotation speed of 50 rpm to obtain a composite rubber with a multi-scale nano-scale microstructure;

[0066] S2: Then, polypropylene, the composite rubber obtained in step S1, and the remaining antioxidant are added into an internal mixer and mixed for 10 minutes at a temperature of 180° C. and a rotation speed of 50 to obtain a masterbatch;

[0067] S3: Granulating the mixed material obtained in step S2;

[0068] S4: adding the pellets in step S3 into an injection molding machine for injection molding, wherein the temperature of the injection molding machine is set as follows: first stage 190°C; second stage 190°C; third stage 190°C; and head 190°C; obtaining a polypropylene composite material with a multi-scale structure dispersed phase.

[0069] The present invention utilizes simple physical blending method, utilizes the microphase separation of block copolymer elastomer itself and its excellent compatibility with EPDM, and regulates block copolymer elastomer to form uniform polystyrene phase region in EPDM. Meanwhile, in the process of preparing composite rubber by blending process, the above-mentioned polystyrene phase region promotes the uniform dispersion of nano silicon dioxide, and forms the multi-scale "double network" structure of polystyrene microphase network and nano silicon dioxide particle network. This structure has unique stability, and thus after the secondary blending of subsequent composite rubber and polypropylene, the dispersed phase has multi-scale phase structure (wherein the dispersed phase is submicron or micron-scale, the size of polystyrene nanophase region is 30-50nm, and the size of silicon dioxide nano-scale phase region is 10-15nm). In the impact process, this dispersed phase structure can effectively cavitate and produce microcracks due to the presence of EPDM molecular chain, but the cross-scale development of microcracks is subject to the multiple restrictions of multi-scale structure. This process ensures the absorption of a large amount of energy and more effectively induces the shear yield of polypropylene matrix, greatly improving the low-temperature toughness of polypropylene composite material.

[0070] Silica is evenly dispersed in the composite rubber phase, anchored in the dispersed phase region through a multi-scale "double network" structure, and the aggregation of nano-silica at the phase interface is limited, achieving a similar "chemical cross-linking" effect by physical means. The evenly distributed silicon dioxide nanoparticles can better inhibit the expansion of microcracks and disperse stress. In addition, compared with the same type of polypropylene nanocomposite prepared by physical blending, the present invention has a higher toughening efficiency, and the amount of nano-silica used to achieve effective low-temperature toughening is lower.

[0071] The present invention can achieve the regulation of low-temperature toughness of the polypropylene composite material without increasing the rubber content, and can achieve low-temperature toughening of the polypropylene composite material under low rubber component content and low nanoparticle content.

[0072] Comparative Example 1

[0073] A polypropylene composite material, consisting of the following materials in parts by weight:

[0074] Polypropylene: 70 parts by weight;

[0075] EPDM rubber: 30 parts by weight;

[0076] Nano-scale fumed silica: 10 parts by weight, size 10-15 nm;

[0077] Antioxidant 1010: 2 parts.

[0078] A method for preparing a polypropylene composite material comprises the following steps:

[0079] S1: First, EPDM rubber, nano-fumed silica, and part of the antioxidant were added into an internal mixer and mixed for 15 minutes at a temperature of 160°C and a rotation speed of 50 rpm to obtain a composite rubber with a multi-scale nanoscale microstructure;

[0080] S2: Then, polypropylene, the composite rubber obtained in step S1, and the remaining antioxidant are added into an internal mixer and mixed for 10 minutes at a temperature of 180° C. and a rotation speed of 50 to obtain a masterbatch;

[0081] S3: Granulating the mixed material obtained in step S2;

[0082] S4: adding the pellets in step S3 into an injection molding machine for injection molding, wherein the temperature of the injection molding machine is set to: 190° C. for the first stage, 190° C. for the second stage, 190° C. for the third stage, and 190° C. for the head; and obtaining a polypropylene composite material.

[0083] Comparative Example 2

[0084] A polypropylene composite material, consisting of the following materials in parts by weight:

[0085] Polypropylene: 70 parts by weight;

[0086] Block copolymer elastomer SEPS: 15 parts by weight, the block copolymer elastomer is styrene-ethylene-propylene-styrene copolymer, and the styrene content is 30%;

[0087] EPDM rubber: 15 parts by weight;

[0088] Antioxidant 1010: 2 parts.

[0089] A method for preparing a polypropylene composite material comprises the following steps:

[0090] S1: first, the block copolymer elastomer, EPDM rubber and part of the antioxidant were added into an internal mixer and mixed for 15 minutes at a temperature of 160°C and a rotation speed of 50 rpm to obtain a composite rubber with a multi-scale nanoscale microstructure;

[0091] S2: Then, polypropylene, the composite rubber obtained in step S1, and the remaining antioxidant are added into an internal mixer and mixed for 10 minutes at a temperature of 180° C. and a rotation speed of 50 to obtain a masterbatch;

[0092] S3: Granulating the mixed material obtained in step S2;

[0093] S4: adding the pellets in step S3 into an injection molding machine for injection molding, wherein the temperature of the injection molding machine is set as follows: 190° C. for the first stage, 200° C. for the second stage, 200° C. for the third stage, and 200° C. for the head; and obtaining a polypropylene composite material.

[0094] The performance of the polypropylene composite materials prepared in Examples 1-3 and Comparative Examples 1-2 was tested. The test results are shown in Table 1.

[0095] Table 1 Test performance results

[0096]

[0097] As shown in Table 1, by comparing Example 3 with Comparative Example 2, it can be seen that the addition of nano-silicon dioxide plays an important role in improving the low-temperature toughness. The notched impact strength at -30°C is increased from 25.1 kJ / m 2 Increased to 53.8 kJ / m 2 , and the room temperature tensile properties of the composites are less affected.

[0098] By comparing Example 1, Example 3 and Comparative Example 1, it can be seen that under the premise of keeping the total mass content of rubber unchanged, increasing the content of block copolymer elastomer is beneficial to the low-temperature toughness, and the -30℃ notched impact strength increases from 7.7 kJ / m 2 Increased to 53.8 kJ / m 2 However, when the block copolymer content is high, nano-silica cannot be effectively blended with the rubber and cannot form a dispersed phase with stable properties. Therefore, the ratio shown in Example 3 is the optimal ratio for a total rubber content of 30 parts by weight.

[0099] like Figure 1 As shown, the dispersed phase of the polypropylene composite material of Example 2, Example 3, and Comparative Example 1 was observed microscopically by transmission electron microscopy (TEM), and it was found that the dark color (nano-silicon dioxide phase region) gradually tended to be evenly distributed; in addition, the polystyrene nano-phase region can be further dyed for further observation, and compared with the undyed photos, it can be proved that the polystyrene nano-phase region is also evenly distributed in the dispersed phase region, forming a multi-scale structure dispersed phase, including nano-silicon dioxide phase region (10-15nm), polystyrene phase region (30-50nm), and composite dispersed phase region (about 500nm). Therefore, the formation of this new structure greatly improves the toughening effect of the composite rubber.

[0100] like Figure 2 As shown, further, the composite rubber with multi-scale nano-scale microstructures in Example 3 and the ratio shown in Comparative Example 1 was observed by transmission electron microscope (TEM), and the results showed that the microphase structure of the composite dispersed phase in Example 3 was consistent with the corresponding composite rubber; while obvious nano-silicon dioxide aggregation areas were observed in the dispersed phase microphase structure corresponding to Comparative Example 1. This shows that the microphase of the block copolymer elastomer plays an important role in the uniform dispersion of nano-fumed silica in the dispersed phase.

[0101] contrast Figure 1 and Figure 2 The results in the figure show that the microphase structure of the composite dispersed phase in Example 3 is consistent with the corresponding composite rubber, that is, the structure of the composite rubber corresponding to Example 3 is still well maintained during the process of transformation into the dispersed phase. However, obvious nano-silicon dioxide aggregation areas are observed in the dispersed phase microphase structure corresponding to Comparative Example 1, which shows that silicon dioxide has a natural tendency to aggregate in the dispersed phase.

[0102] Therefore, the present invention adopts the above-mentioned multi-scale structure dispersed phase polypropylene composite material and its preparation method, and uses a simple physical blending method to solve the problem of poor low-temperature toughness of general polypropylene composite materials, in order to meet the current industry needs.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A polypropylene composite material with a multi-scale structure dispersed phase, characterized in that: The dispersed phase of the polypropylene composite material is a composite dispersed phase, and is of submicron or micron scale, and has a polystyrene nanophase region and a nanoscale silicon dioxide phase region, and includes the following components in parts by weight: Polypropylene: 60-80 parts; Block copolymer elastomer: 5-15 parts; EPDM rubber: 15-30 parts; Nano rigid particles: 5-15 parts; Antioxidant: 1-2 parts.

2. The polypropylene composite material with a multi-scale structure dispersed phase according to claim 1, characterized in that: The block copolymer elastomer is a styrene-ethylene-propylene-styrene copolymer or a styrene-ethylene-propylene copolymer, and the styrene content is 30%.

3. The polypropylene composite material with a multi-scale structure dispersed phase according to claim 1, characterized in that: The antioxidant is one or more of antioxidant 1010, antioxidant 168, and antioxidant 1076.

4. The polypropylene composite material with a multi-scale structure dispersed phase according to claim 1, characterized in that: The nano rigid particles are nano-scale fumed silica with a size of 10-15 nm.

5. The method for preparing a polypropylene composite material with a multi-scale structure dispersed phase according to any one of claims 1 to 4, characterized in that: The steps include: S1: firstly, the block copolymer elastomer, EPDM rubber, nano rigid particles and part of the antioxidant are added into an internal mixer and mixed for 10-20 minutes at a temperature of 160°C and a rotation speed of 50 rpm to obtain a composite rubber with a multi-scale nano-scale microstructure; S2: Then, polypropylene, the composite rubber obtained in step S1, and the remaining antioxidant are added into an internal mixer and mixed for 10-15 minutes at a temperature of 180-200° C. and a rotation speed of 50-80 rpm to obtain a masterbatch; S3: granulating the masterbatch obtained in step S2; S4: adding the pellets in step S3 into an injection molding machine for injection molding, wherein the temperature of the injection molding machine is set as follows: first stage 190-210°C; second stage 190-210°C; third stage 190-210°C; and head 190-210°C; obtaining a polypropylene composite material with a multi-scale structure dispersed phase.

6. The method for preparing a polypropylene composite material with a multi-scale structure dispersed phase according to claim 5, characterized in that: In step S1, the composite rubber has the following nanoscale microstructure: a polystyrene nanophase region formed by phase separation of the block copolymer elastomer itself, with a size of 30-50 nm, and a nanoscale silicon dioxide phase region formed by uniform dispersion of nano rigid particles, with a size of 10-15 nm.

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