Preparation method of polypropylene material for cold-resistant chain, polypropylene material and application of polypropylene material

Abstract

The invention belongs to the technical field of high polymer materials, and relates to a preparation method of a polypropylene material for a cold-resistant chain, the polypropylene material and application of the polypropylene material. The preparation method of the polypropylene material comprises the following steps: (1) adding polypropylene, graft modified polypropylene, a styrene-butadiene-styrene block copolymer, cold-resistant PE and a silane coupling agent into a high-speed stirrer, and uniformly mixing to obtain a mixture 1; (2) adding wollastonite or modified wollastonite, a flame retardant, an antioxidant and a filler into a high-speed stirrer, and uniformly mixing with the mixture 1 to obtain a mixture 2; and (3) introducing the mixture 2 into a double-screw extruder for plasticizing, extruding and granulating to obtain the composite material. The polypropylene material prepared by the invention has relatively high low-temperature toughness and strength and excellent comprehensive performance, and is widely applied to products for cold-chain-resistant packaging, transportation and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and relates to a preparation method of a cold chain resistant polypropylene material, the polypropylene material and application thereof. Background Art

[0002] Polypropylene (PP) material is a thermoplastic resin made by propylene polymerization. It is non-toxic, odorless, and has low density. Its strength, rigidity, hardness, and heat resistance are better than low-pressure polyethylene, and it can be used at around 100°C. It has good dielectric properties and high-frequency insulation and is not affected by humidity, but it becomes brittle at low temperatures, is not wear-resistant, and is prone to aging.

[0003] In order to improve the cold resistance of polypropylene materials, many studies have focused on the performance improvement of cold-resistant additives. For example, Chinese invention patent application CN103772812A discloses the use of a sorbitol compound as a polypropylene cold-resistant agent and cold-resistant polypropylene containing a sorbitol compound. The use of the cold-resistant agent has a significant effect on the maintenance of the low-temperature toughness of polypropylene. Chinese invention patent CN105646947B discloses the use of a basic magnesium sulfate whisker as a polypropylene cold-resistant agent. The basic magnesium sulfate whisker has a diameter D < 1.0 micron, a length L of 10-60 microns, an aspect ratio L / D > 30, and a surface treated with an aluminum-titanium composite coupling agent. Adding it to polypropylene resin can significantly improve the low-temperature toughness retention rate of polypropylene materials. Chinese invention patent CN104086882B discloses the use of a needle-shaped wollastonite as a polypropylene cold-resistant agent and a cold-resistant polypropylene material containing the needle-shaped wollastonite. The needle-shaped wollastonite can significantly improve the low-temperature toughness retention rate of polypropylene materials, and can make the -30°C low-temperature toughness retention rate of polypropylene materials above 50%.

[0004] The use of the above-mentioned cold-resistant agents effectively improves the low-temperature toughness of polypropylene materials, but there is a common problem of relatively low mechanical strength and heat resistance, which cannot meet the use requirements when there are high requirements for material strength. The existing technology mostly uses the use of reinforcing agents and modifiers to make up for this defect. For example, Chinese invention patent CN105131496B discloses a cold-resistant glass fiber reinforced polypropylene and its preparation method, including the following components in mass percentage: 59-73.1% copolymer PP, 6-12% maleic anhydride grafted POE, 2-5% compatibilizer, 18-22% glass fiber, 0.4-1.0% antioxidant, 0.5-1.0% cold-resistant agent, and the obtained polypropylene material has the properties of light weight, easy molding, good toughness, good cold resistance, strong pressure bearing capacity, etc.

[0005] At present, there is still a lack of research on improving the low-temperature toughness and strength of polypropylene materials from the perspective of preparation technology. Through process improvement, not only can the use of modifying additives such as cold-resistant agents, toughening agents, and reinforcing agents be reduced to save costs; it can also avoid the addition of additives affecting its own low density, high heat resistance and other properties. Summary of the invention

[0006] The present invention aims at the problems existing in the prior art and provides a preparation method of a cold chain resistant polypropylene material, a polypropylene material and its application. The recycled materials of paint barrels containing PP and recycled inner film are used as the basic materials, and the materials are modified with grafted modified polypropylene, styrene-butadiene-styrene block copolymer and cold resistant PE under the action of a specific coupling agent, and modified wollastonite is added at the same time, which not only retains the original excellent heat resistance, mechanical properties and low density of polypropylene, but also effectively improves the cold resistance, low temperature toughness and strength, and has excellent comprehensive performance.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] The present invention provides a method for preparing a cold chain resistant polypropylene material, comprising the following steps:

[0009] (1) adding polypropylene, graft modified polypropylene, styrene-butadiene-styrene block copolymer, cold-resistant PE and silane coupling agent into a high-speed mixer and mixing them uniformly to obtain a mixture 1;

[0010] (2) adding wollastonite or modified wollastonite, flame retardant, antioxidant and filler into a high-speed mixer and mixing them with mixture 1 to obtain mixture 2;

[0011] (3) The mixture 2 is introduced into a twin-screw extruder for plasticization, extrusion and granulation to obtain a product.

[0012] Furthermore, the mass ratio of the polypropylene, graft modified polypropylene, styrene-butadiene-styrene block copolymer, cold-resistant PE and silane coupling agent is 80-100: 1-5: 1-5: 5-10: 0.5-3.

[0013] Furthermore, in step (2), the mass ratio of the wollastonite or modified wollastonite to the mixture 1 is 0.02-0.2:1.

[0014] Furthermore, the polypropylene comes from paint barrel recycle and recycled inner film recycle.

[0015] Furthermore, the mass ratio of the paint barrel recycled material, the recycled inner film recycled material and the cold-resistant PE is 7-8:1-2:1.

[0016] Furthermore, the graft-modified polypropylene is selected from one or more of maleic anhydride grafted polypropylene, acrylic acid grafted polypropylene or methyl methacrylate grafted polypropylene.

[0017] Furthermore, the model of the cold-resistant PE is 8018Y and / or 1C7A.

[0018] Furthermore, the silane coupling agent includes but is not limited to one or more of 3-aminopropyltriethoxysilane (KH550), γ-glycidyloxypropyltrimethoxysilane (KH560) or γ-methacryloxypropyltrimethoxysilane (KH570), N-(β-aminoethyl)-γ-aminopropyltrimethoxy(ethyl)silane (KH-792), n-octyltriethoxysilane (GR-SI351), vinyltriethoxysilane (GR-SI151), vinyltrimethoxysilane (GR-SI171) and vinyl-tri(2-methoxyethoxy)silane (GR-SI172).

[0019] Furthermore, the modified wollastonite is obtained by mixing and stirring wollastonite powder, chitosan and a coupling agent.

[0020] Furthermore, the mass ratio of the wollastonite powder, chitosan and coupling agent is 1:0.1-1:0.05-0.3.

[0021] Furthermore, the mixing temperature is 80-100°C.

[0022] Furthermore, the coupling agent is a titanate coupling agent and / or an aluminate coupling agent.

[0023] Furthermore, the titanate coupling agent includes, but is not limited to, n-butyl titanate, isopropyl titanate, isopropyl triisostearate titanate (GR-300), isopropyl dioleyl (dioctyl phosphate) titanate (GR-101), isopropyl dioleyl (dioctyl phosphate) titanate (GR-102), isopropyl trioleyl titanate (GR-105), isopropoxy tri(dodecylbenzenesulfonyl) titanate (GR-109), isopropoxy tri(dioctyl pyrophosphate) titanate (GR-201), bis(dioctyl pyrophosphate) ethylene titanate (GR-311), tetraisopropyl di(dioctyl phosphite) titanate (GR-401) and isopropyl tristearate titanate (GR-110).

[0024] Furthermore, the aluminate coupling agent is selected from one or more of n-butyl aluminate and isopropyl distearate acyloxyaluminate (GR-AL18).

[0025] Furthermore, the flame retardant is selected from organosilicon flame retardants or organophosphorus flame retardants; the antioxidant is selected from phosphite antioxidants and / or hindered phenol antioxidants; and the filler is selected from one or more of calcium carbonate, alumina and kaolin.

[0026] Furthermore, in step (1) and step (2), the mixing temperature is 100-150° C. and the rotation speed is 4000-8000 rpm.

[0027] Furthermore, in step (3), the plasticizing temperature is 300-450°C.

[0028] Furthermore, in step (3), the temperature of each section of the twin-screw extruder during the extrusion process is: 180-185°C in the first section, 190-195°C in the second section, 195-205°C in the third section, and 205-215°C in the fourth section; the screw speed is 150-200rpm.

[0029] The invention also relates to the polypropylene material prepared by the above preparation method.

[0030] The present invention also relates to the application of the polypropylene material in cold chain resistant packaging or transportation products.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention firstly blends PP with grafted polypropylene, SBS and cold-resistant PE under the action of a silane coupling agent, thereby providing a basis for the low-temperature toughness of polypropylene plastics, and SBS and cold-resistant PE have a significant synergistic effect in improving the low-temperature toughness; further, by blending and modifying wollastonite powder, or first modifying wollastonite powder and then blending and filling, the material is endowed with better low-temperature performance, and the impact resistance of the plastic is also improved; compared with one-step blending and modification, the dispersion of each component is better, and each component can be more fully exerted.

[0033] Wollastonite powder is modified by using an amphiphilic polymer surfactant - chitosan in combination with a titanate coupling agent and an aluminate coupling agent. It has good compatibility with the components of polymer blends, flame retardants, antioxidants, fillers and other auxiliary agents. Through extrusion molding, the cold resistance of the material is further improved.

[0034] The present invention adopts the basic material PP from the recycled materials of paint barrels and recycled inner film, thus realizing the recycling of materials; it cooperates with various additives to have excellent mechanical properties, high toughness and high strength; the raw materials do not need to be additionally added with reinforcing and toughening additives, effectively maintaining the low density and high heat resistance characteristics of polypropylene itself, and has potential applications in cold chain packaging and transportation materials. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It is worth noting that the raw materials used in the present invention are all common commercial products, and their sources are not specifically limited. The following materials are only exemplary:

[0036] The melt index of the paint bucket recycle is 3g / 10min, and the tensile strength is 18MPa;

[0037] The melt index of the recycled inner film is 1.2g / 10min, the tensile strength is 30MPa, and the impact toughness is 60kJ / m 2 ;

[0038] Cold-resistant PE, model 8018Y;

[0039] Cold-resistant PE, model 1C7A;

[0040] Acrylic acid grafted polypropylene, model polybond 1103;

[0041] Acrylic acid grafted polypropylene, model polybond 3150;

[0042] Styrene-butadiene-styrene block copolymer SBS, model LG501;

[0043] Organic silicon coupling agent, model MR-01;

[0044] Modified wollastonite: According to weight proportions, take 10 parts of wollastonite powder, 1 part of chitosan and 0.5 parts of n-butyl titanate, mix them evenly, and stir them at 100° C. for 30 minutes to obtain the modified wollastonite.

[0045] Example

[0046] The raw materials and amounts used in the preparation of polypropylene materials in Examples 1-6 are shown in Table 1.

[0047] The preparation method is as follows:

[0048] (1) Add polypropylene, graft modified polypropylene, SBS, cold-resistant PE and coupling agent into a high-speed mixer according to the amounts in the table, and mix at 120° C. and 5000 rpm for 30 min to obtain a mixture A;

[0049] (2) Add wollastonite or modified wollastonite, flame retardant, antioxidant and filler into the high-speed mixer according to the amounts in the table, and continue mixing with mixture A for 30 minutes at the same temperature and speed conditions;

[0050] (3) After being uniformly mixed, the mixture was introduced into a twin-screw extruder, plasticized at 400°C for 1 hour, and then extruded and granulated to obtain a polypropylene material (the temperatures of each section of the twin-screw extruder during the extrusion process were: 180°C for the first section, 190°C for the second section, 195°C for the third section, and 205°C for the fourth section; the screw speed was 200 rpm).

[0051] Table 1 Raw material dosage table of Examples 1-9 (unit: weight parts)

[0052]

[0053]

[0054] Comparative Example

[0055] The raw materials and amounts used in the preparation of the polypropylene materials of Comparative Examples 1-6 are shown in Table 1.

[0056] The order of feeding and process parameters in the preparation process were the same as those in Example 1, except that components not mentioned in Table 1 were not added.

[0057] Table 2 Comparative Examples 1-6 Raw Materials Usage Table (Unit: Weight Parts)

[0058]

[0059]

[0060] The polypropylene materials prepared in the comparative examples of the above embodiments are injection molded into standard test specimens by a single screw injection molding machine, and after being placed at 23±2°C, RH50±5% for at least 24 hours, the performance of the standard test specimens is tested at room temperature and low temperature (after being placed at -30°C for 24 hours). The specific test items and test conditions are as follows:

[0061] (1) Tensile performance test: According to GB / T1040, the tensile speed is 5 mm / min;

[0062] (2) Bending performance test: According to GB / T9341-2008, the bending speed is 2 mm / min and the span is 64 mm;

[0063] (3) Notched impact strength test: carried out in accordance with GB / T1843-2008; wherein, low temperature toughness retention rate = low temperature notched impact strength / room temperature notched impact strength × 100%.

[0064] (4) Drop test: After the injection molded sample is left at -30°C for 24 h, it is naturally dropped from a height of 1.5 m above the ground to observe whether the sample is damaged (1. intact; 2. damaged: cracks appear; 3. broken: fragments of varying sizes fall off).

[0065] The tensile and bending performance test results are shown in Table 3, the notched impact performance test results are shown in Table 4, and the drop test results are shown in Table 5.

[0066] Table 3 Tensile and bending properties test results

[0067]

[0068]

[0069] It can be seen from the above table that the room temperature mechanical properties of the polypropylene materials prepared in Examples 1-6 of the present invention are better than those of pure polypropylene materials. Although the room temperature mechanical properties of the polypropylene materials of Comparative Examples 1-7 are comparable to those of Examples 1-6, their low temperature mechanical properties are poor. Compared with Example 2, the tensile strength, elongation at break and bending strength of the polypropylene materials of Comparative Examples 1 and 2 are all poor, which shows that there is a certain synergistic effect between the raw materials cold-resistant PE and SBS; Compared with Example 2, Comparative Examples 3 and 4 lack grafted polypropylene, and the amount of SBS or cold-resistant PE is increased accordingly, but it still cannot make up for the decrease in mechanical properties caused by the lack of grafted polypropylene. It can be seen that grafted polypropylene is also one of the indispensable raw materials; The present invention significantly improves the mechanical properties of polypropylene materials through the synergistic coordination of multiple polymers. At the same time, Comparative Examples 5 and 6 lack wollastonite and use talcum powder to replace wollastonite, and their low temperature mechanical properties also decrease significantly. It can be seen that the modification of wollastonite is also a key factor in improving the low temperature mechanical properties of polypropylene materials. Comparative Example 7 uses a titanate coupling agent instead of a silane coupling agent, and its low-temperature mechanical properties also decrease significantly. This shows that the type of coupling agent also has a great influence on the mechanical properties of polypropylene materials.

[0070] Table 4 Notched impact strength test results

[0071]

[0072]

[0073] Table 5 Drop test results

[0074] Is it damaged? Example 1 whole Example 2 whole Example 3 whole Example 4 whole Example 5 whole Example 6 whole Example 7 whole Comparative Example 1 whole Comparative Example 2 damaged Comparative Example 3 damaged Comparative Example 4 whole Comparative Example 5 damaged Comparative Example 6 broken Comparative Example 7 broken

[0075] It can be seen from the above table that the room temperature impact strength of the polypropylene materials prepared in Examples 1-6 of the present invention and Comparative Examples 1-7 can all reach 40 kJ / m 2As shown above, the difference in toughness is small; compared with pure polypropylene materials, the impact toughness and low-temperature toughness retention rate are significantly improved, whether at room temperature or low temperature. Compared with Example 2, there are large differences in the low-temperature toughness of Examples 1-7, especially for Examples 5, 6, and 7, the low-temperature toughness retention rate at -30°C is only more than 20%, and it is even worse at -50°C, indicating that the presence of wollastonite or modified wollastonite contributes greatly to the improvement of low-temperature toughness; and secondly, cold-resistant PE and SBS also have more significant synergistic effects in improving the low-temperature toughness of polypropylene materials; and grafted polypropylene is also indispensable in improving the toughness of polypropylene materials. In addition, when the raw materials lack cold-resistant PE and grafted polypropylene, the obtained polypropylene material is damaged in the drop test. When modified wollastonite is missing or replaced with talcum powder, the obtained polypropylene material is broken in the drop test. Comparative Example 7 uses a coupling agent type different from that of Example 1 (Example 1 uses a silane coupling agent, and Comparative Example 7 uses a titanate coupling agent). Its room temperature mechanical strength and toughness both decrease to a certain extent, and the decrease is more obvious at low temperatures.

[0076] In addition, the low-temperature mechanical properties and low-temperature toughness of the polypropylene materials prepared in various embodiments of the present invention also differ to varying degrees. Regardless of room temperature or low temperature, the mechanical strength and toughness of Example 2 are the best. Compared with Example 2, the ratios of the base PP material paint bucket recycled material, recycled inner film recycled material and cold-resistant PE in Examples 1 and 3 are different, and the performance in various aspects is slightly reduced. Therefore, the mass ratio of the paint bucket recycled material, recycled inner film recycled material and cold-resistant PE is preferably 7-8:1-2:1. In Example 6, the amount of modified wollastonite is relatively low. Although the amount of cold-resistant PE is increased, the low-temperature performance is also reduced. Therefore, further optimizing the amount of wollastonite and modified wollastonite can also improve the low-temperature mechanical strength and toughness of the polypropylene material to a certain extent.

[0077] In summary, the present invention uses paint barrel recycled materials and recycled inner film recycled materials as PP basic materials, and cooperates with flexible polymers, cold-resistant polymers, silane coupling agents, and wollastonite (modified wollastonite) to obtain a cold-resistant polypropylene material with excellent mechanical properties, especially low-temperature toughness.

[0078] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a cold chain resistant polypropylene material, characterized in that: The following steps are involved: (1) adding polypropylene, graft modified polypropylene, styrene-butadiene-styrene block copolymer, cold-resistant PE and silane coupling agent into a high-speed mixer and mixing them uniformly to obtain a mixture 1; (2) adding wollastonite or modified wollastonite, a flame retardant, an antioxidant and a filler into a high-speed mixer and mixing them evenly with the mixture 1 to obtain a mixture 2; (3) The mixture 2 is introduced into a twin-screw extruder for plasticization, extrusion and granulation to obtain a product.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the polypropylene, graft modified polypropylene, styrene-butadiene-styrene block copolymer, cold-resistant PE and silane coupling agent is 80-100:1-5:1-5:5-10:0.5-3; the mass ratio of the wollastonite or modified wollastonite to the mixture 1 is 0.02-0.2:

1.

3. The preparation method according to claim 1, characterized in that: The polypropylene comes from recycled paint buckets and recycled inner film; the recycled paint bucket has a melting index of ≥3g / 10min and a tensile strength of 10-20MPa; the recycled inner film has a melting index of 1-1.5g / 10min, a tensile strength of ≥30MPa, and an impact toughness of 50-60kJ / m 2 ; The mass ratio of the paint barrel recycled material, the recycled inner film recycled material and the cold-resistant PE is 7-8:1-2:

1.

4. The preparation method according to claim 1, characterized in that: The grafted modified polypropylene is selected from one or more of maleic anhydride grafted polypropylene, acrylic acid grafted polypropylene or methyl methacrylate grafted polypropylene; the model of the cold-resistant PE is 8018Y and / or 1C7A; the silane coupling agent is selected from one or more of 3-aminopropyl triethoxysilane, γ-glycidyloxypropyl trimethoxysilane or γ-methacryloxypropyl trimethoxysilane, N-(β-aminoethyl)-γ-aminopropyl trimethoxy(ethyl)silane, n-octyl triethoxysilane, vinyl triethoxysilane, vinyl trimethoxysilane and vinyl-tri(2-methoxyethoxy)silane.

5. The preparation method according to claim 1, characterized in that: The modified wollastonite is obtained by mixing and stirring wollastonite powder, chitosan and a coupling agent; the mass ratio of the wollastonite powder, chitosan and the coupling agent is 1:0.1-0.4:0.05-0.

3.

6. The preparation method according to claim 5, characterized in that: The coupling agent is a titanate coupling agent and / or an aluminate coupling agent; The titanate coupling agent is selected from one or more of n-butyl titanate, isopropyl titanate, isopropyl triisostearate titanate, isopropyl dioleyloxy (dioctyl phosphate acyloxy), isopropyl dioleyloxy (dioctyl phosphate acyloxy) titanate, isopropyl trioleyloxy titanate, isopropoxy tri(dodecylbenzenesulfonyloxy) titanate, isopropoxy tri(dioctyl pyrophosphate acyloxy) titanate, bis(dioctyl pyrophosphate acyloxy) ethylene titanate, tetraisopropyl di(dioctyl phosphite) titanate and isopropyl tristearate titanate; The aluminate coupling agent is selected from one or more of n-butyl aluminate and isopropyl distearate acyloxy aluminate.

7. The preparation method according to claim 1, characterized in that: The flame retardant is selected from organosilicon flame retardant or organophosphorus flame retardant; the antioxidant is selected from phosphite antioxidant and / or hindered phenol antioxidant; the filler is selected from one or more of calcium carbonate, alumina and kaolin.

8. The preparation method according to claim 1, characterized in that: In step (1) and step (2), the mixing temperature is 100-150° C. and the rotation speed is 4000-8000 rpm; in step (3), the plasticizing temperature is 300-450° C.; during the extrusion process, the temperatures of each section of the twin-screw extruder are: 180-185° C. in the first section, 190-195° C. in the second section, 195-205° C. in the third section, and 205-215° C. in the fourth section; and the screw speed is 150-200 rpm.

9. The polypropylene material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the polypropylene material according to claim 9 in cold chain packaging or transportation products.

Images