A method for preparing a special masterbatch for polypropylene hollow boards using dolomite composite modification

Abstract

This invention discloses a method for preparing a special masterbatch for polypropylene hollow boards using dolomite composite modification. The masterbatch is composed of the following components in parts by weight: 8-58 parts dolomite, 8-58 parts calcium carbonate, 30-60 parts polypropylene, 0.2-1.0 parts coupling agent, and 0.2-1.0 parts lubricant; wherein the polypropylene is copolymer polypropylene and homopolymer polypropylene. The method provided by this invention reduces the production cost of polypropylene hollow boards while improving their elongation at break and aging resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer material processing technology and polypropylene hollow board preparation technology, specifically to a method for preparing polypropylene hollow board special masterbatch using dolomite composite modification. Background Technology

[0002] This section provides only background information relevant to this disclosure and is not necessarily prior art.

[0003] Polypropylene (PP) is the most widely used polyolefin and one of the fastest-growing commercial plastics. PP possesses good chemical resistance, heat resistance, and fatigue resistance, as well as semi-rigidity, translucency, toughness, and integral hinge properties. However, the application range of PP in engineering thermoplastics is severely limited by its high flammability, low-temperature brittleness, and low stiffness at low temperatures. Furthermore, PP is non-polar, making it incompatible with almost all polar fillers and reinforcing materials used in the polymer industry.

[0004] One of the key challenges in producing high-performance inorganic / organic composite materials is overcoming the agglomeration of mineral filler particles in the polypropylene matrix. Traditional polypropylene hollow board manufacturing processes include the preparation of filler masterbatch, mixing the masterbatch with polypropylene resin and then stretching the boards, and cutting the boards. Currently, the inorganic filler in the masterbatch is mostly unmodified calcium carbonate powder, which significantly reduces the toughness of the hollow board. Compared to calcium carbonate, dolomite has good toughness and thermal stability, but its stiffness is inferior. However, filling only with dolomite or calcium carbonate powder does not allow for good bonding with polypropylene, resulting in polypropylene hollow boards prepared using only mineral powder as filler with weak performance, making them unsuitable for the rapidly developing logistics packaging industry. Polypropylene hollow boards with good anti-aging properties and long cycle life will be more favored in the market. Furthermore, the production process of first preparing the filler masterbatch and then mixing it with resin to prepare the hollow board is cumbersome, and too many production steps result in increased energy consumption and waste emissions, exacerbating environmental damage. Therefore, this invention proposes a method for preparing a special masterbatch containing composite modified powder, which directly produces hollow boards by using the special masterbatch, reducing production steps and carbon energy consumption, enhancing environmental protection while improving industrial efficiency. Summary of the Invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a polypropylene hollow board or a special masterbatch for preparing polypropylene hollow boards, as well as a method for preparing the aforementioned hollow board and special masterbatch.

[0006] To solve the above-mentioned technical problems, the present invention discloses the following technical solution:

[0007] In a first aspect, the present invention discloses a polypropylene hollow board and a special masterbatch for preparing polypropylene hollow boards.

[0008] The polypropylene hollow board and the special masterbatch for preparing the polypropylene hollow board are made from components containing the following parts by weight:

[0009] Dolomite 8-58 parts

[0010] Calcium carbonate 8-58 parts

[0011] 30-60 parts of polypropylene

[0012] 0.2-1.0 parts of coupling agent

[0013] Lubricant 0.2-1.0 parts

[0014] The polypropylene is a combination of copolymer polypropylene and homopolymer polypropylene.

[0015] Secondly, this invention discloses a method for preparing a polypropylene hollow board and a special masterbatch for preparing polypropylene hollow boards.

[0016] The polypropylene hollow board and the special masterbatch for preparing the polypropylene hollow board are made from components containing the following parts by weight:

[0017] Dolomite 8-58 parts

[0018] Calcium carbonate 8-58 parts

[0019] 30-60 parts of polypropylene

[0020] 0.2-1.0 parts of coupling agent

[0021] Lubricant 0.2-1.0 parts

[0022] The polypropylene is a combination of copolymer polypropylene and homopolymer polypropylene.

[0023] In the first and second aspects mentioned above,

[0024] The copolymer polypropylene described in this invention has a molecular weight of 50,000 to 500,000, such as 80,000 to 150,000, and a melt index of 1.8-2.7 g / 10 min, such as 2-2.5 g / 10 min; for example, the copolymer polypropylene of China Petroleum & Chemical Corporation (model: K8003, molecular weight: 50,000 to 500,000, melt index: 2.5 g / 10 min) and the copolymer polypropylene of China Petroleum & Chemical Corporation Maoming Branch (model: M02D, molecular weight: 80,000 to 150,000, melt index: 1.8 g / 10 min).

[0025] The homopolymer polypropylene described in this invention has a molecular weight of 80,000 to 150,000 and a melt index of 0.5-4 g / 10 min, such as 3.0 g / 10 min; for example, the homopolymer polypropylene of the State Power Investment Corporation (model: 1102K, molecular weight: 80,000 to 150,000, melt index: 3.0 g / 10 min) and the homopolymer polypropylene of Taiwan Plastics Industry Co., Ltd. (model: 1005N, molecular weight: 80,000 to 150,000, melt index: 0.5 g / 10 min).

[0026] In some embodiments, the weight parts of each component are as follows:

[0027] 10-53 parts of dolomite

[0028] Calcium carbonate 10-53 parts

[0029] 35-50 parts of polypropylene

[0030] 0.4-0.8 parts of coupling agent

[0031] Lubricant 0.4-0.8 parts.

[0032] In some embodiments, the weight parts of each component are as follows:

[0033] Dolomite 12-48 parts

[0034] Calcium carbonate 12-48 parts

[0035] 40 parts of polypropylene

[0036] 0.6 parts coupling agent

[0037] 0.6 parts of lubricant.

[0038] In some embodiments, the mass ratio of copolymer polypropylene to homopolymer polypropylene is 0.1-5.2:1, in some embodiments it is 0.2-4.7:1, and in some embodiments it is 7:33, 13:27, 20:20, 27:13 or 33:7.

[0039] In some embodiments, the dolomite and calcium carbonate are fine powders passing through 800-1500 mesh. If they pass through 1250 mesh, the dolomite and calcium carbonate can be pulverized by air jet milling.

[0040] In some embodiments, the coupling agent is an aluminate coupling agent and / or a titanate coupling agent; in some embodiments, the aluminate coupling agent is aluminate coupling agent DL-411, and the titanate coupling agent is titanate coupling agent NDZ-201.

[0041] In some embodiments, the lubricant is stearic acid and / or zinc stearate.

[0042] In some embodiments, the preparation method includes the following steps:

[0043] (1) Premix dolomite and calcium carbonate, add coupling agent, lubricant and polypropylene to mix, and obtain a mixture;

[0044] (2) The resulting mixture is plasticized in an internal mixer to obtain a mixture melt;

[0045] (3) The resulting mixture melt is plasticized and granulated in a twin-screw extruder to obtain a special masterbatch for polypropylene hollow boards;

[0046] (4) Press the polypropylene hollow board special masterbatch into a board using a hot press and place it in a cool place to obtain a polypropylene hollow board with excellent anti-aging properties prepared from dolomite composite modified powder raw material; or feed the polypropylene hollow board special masterbatch into a hollow board pulling machine to obtain a polypropylene hollow board with excellent anti-aging properties prepared from dolomite composite modified powder raw material.

[0047] In step (1), dolomite and calcium carbonate are put into a high-speed mixer, the speed is adjusted to 600-800 r / min, and premixed at 115-135℃ for 10-20 min. First, coupling agent is added and premixed for 2-10 min, then lubricant is added and premixed for 2-8 min, and then polypropylene is added and mixed for 4-12 min to obtain a mixture.

[0048] In step (2), the plasticizing temperature is 180-220℃, preferably 190-210℃; in some embodiments, plasticizing is performed at a rotation speed of 400-600 r / min.

[0049] In step (3), the temperature range of the twin-screw extruder is 180-190℃, 185-195℃, 190-200℃, 195-205℃, 200-210℃, 205-215℃, 210-220℃, 210-220℃, 205-215℃, preferably 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 215℃, 210℃; in some embodiments, the speed of the twin-screw extruder is 150-170rpm, the melt flow rate is 50-60L / min, and the air-cooled hot shear is 4-6Hz.

[0050] Modifying calcium carbonate and dolomite powder alone is insufficient to fully utilize their unique advantages. This invention addresses the composite modification of dolomite and calcium carbonate powders, leveraging the excellent heat resistance and high toughness of dolomite to propose a method for preparing polypropylene hollow boards from modified dolomite raw materials. This method involves different pretreatments based on structure, morphology, and ultrafine processing to create a specialized material, replacing the conventional method of first preparing a filler masterbatch from untreated calcium carbonate powder before adding it to polypropylene to produce polypropylene hollow boards.

[0051] The method provided by this invention improves the poor aging resistance of traditional polypropylene hollow boards, reduces processing steps, increases the added value of dolomite, and lowers the production cost of polypropylene hollow boards. When using only small amounts of polypropylene, dolomite, and calcium carbonate as composite modifier fillers, the results show that the composite modification of dolomite, polypropylene, and calcium carbonate successfully achieves a synergistic hybridization effect. Mechanical properties exhibit higher tensile strength and elongation at break, while significantly improving the toughness and aging resistance of polypropylene hollow boards, achieving a toughening and strengthening effect, thus enabling the long-term use of polypropylene hollow boards.

[0052] The key advantages of this invention are: ① Based on the properties and characteristics of dolomite, dolomite partially replaces calcium carbonate inorganic filler, and after mixing and modification, a composite modified inorganic powder raw material is obtained, which is then used to prepare polypropylene hollow boards that can be used in building materials. The preparation of this special material effectively reduces processing steps, improves production efficiency, and lowers the manufacturing cost of polypropylene hollow boards. ② Under low filler conditions, the dispersibility of the modified dolomite particles is better. On the one hand, the ultrafine dolomite powder, as a solid solution, can toughen and strengthen the modified composite powder; on the other hand, dolomite and calcium carbonate have similar structures and compositions, and after blending, due to the principle of like dissolves like, the intermolecular bonding force between the two remains strong, which is macroscopically reflected in the composite powder still maintaining excellent mechanical properties. ③ With optimized formulation, when dolomite and calcium carbonate powder are mixed and modified, the anti-aging performance of the resulting polypropylene hollow board is significantly improved. Elongation at break is one of the important indicators for measuring the ductility or toughness of materials. Polypropylene hollow boards prepared with dolomite composite modified powder have better elongation at break than those prepared with traditional single calcium carbonate powder. Using only small amounts of dolomite and calcium carbonate as fillers for composite material modification, the results showed that the dolomite composite modified powder successfully achieved a synergistic hybridization effect.

[0053] Beneficial effects:

[0054] This invention fully utilizes the advantages of dolomite's good heat resistance and high toughness, replacing part of the calcium carbonate with it and blending it with calcium carbonate for composite modification before preparing polypropylene hollow boards, thereby reducing the preparation cost and effectively improving the service life and added value of polypropylene hollow boards.

[0055] The method provided by this invention reduces the production cost of polypropylene hollow boards while increasing their elongation at break and improving their anti-aging properties after blending.

[0056] The method provided by this invention prepares hollow boards using dolomite-modified powdered polypropylene special material, which improves upon the current domestic method of first preparing filler masterbatch and then adding polypropylene, thus reducing production steps. Detailed Implementation

[0057] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0058] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0059] In the following examples, the raw material suppliers for the copolymer polypropylene (models: K8003 and M02D) were China Petroleum & Chemical Corporation, the raw material suppliers for the homopolymer polypropylene (models: 1102K and 1005N) were China Energy Investment Corporation and Taiwan Plastics Industry Co., Ltd., and the raw material suppliers for stearic acid (model: 1840), zinc stearate (CAS No.: 557-05-1), and coupling agent (model: DL-411) were Dongguan Dinghai Plastics & Chemical Co., Ltd.

[0060] In the following embodiments, the mechanical properties were tested using standard specimen strips according to national standards. The tensile and bending properties of the composite material specimen strips were tested using an electronic universal testing machine, and the impact properties were tested using a cantilever beam impact testing machine.

[0061] Tensile property test: According to GB / T 1040.2-2006 standard, the specimen is a dumbbell-shaped specimen with a diameter of 170mm × 20mm × 4mm, a narrow section width of 10mm, and a preferred thickness of 4mm. The gauge length is 50mm, and the test speed is 50mm / min.

[0062] Bending performance test: According to GB / T 9341-2008 standard, the specimen size is 80mm×10mm×4mm, the test span is 64mm, and the test speed is 2mm / min.

[0063] Impact performance test: According to GB / T 1843-2008 standard, notched impact mode was adopted, the specimen size was 80mm×10mm×4mm, the impact energy was 5.5J, and the impact velocity was 2.9m / s.

[0064] Aging performance test: According to GB / T 16422.3-2022 standard, the specimen size was 80mm×10mm×4mm, and a UVA-351 (Type 1B) test chamber was used, with a uniform irradiance of 0.76W / (m²) at 340nm. 2 (nm), aged at 50℃ for 28 days.

[0065] Unless otherwise specified, all quantities mentioned in the following embodiments are by weight.

[0066] Example 1: Preparation of Polypropylene Hollow Boards from Dolomite-Containing Composite Modified Raw Materials

[0067] (1) First, dolomite and calcium carbonate were pulverized to 1250 mesh ultrafine powder using an air jet mill. 48 parts of the 1250 mesh ultrafine calcium carbonate powder and 12 parts of the 1250 mesh ultrafine dolomite powder were added together to a high-speed mixer. The speed was adjusted to 700 r / min for high-speed premixing, and the mixture was pretreated at a constant temperature of 125℃ for 15 minutes. Next, 0.6 parts of aluminate coupling agent (model DL-411) were added and premixed for 5 minutes, followed by 0.3 parts of stearic acid and 0.3 parts of zinc stearate, which were then premixed for 5 minutes. Subsequently, 7 parts of copolymer polypropylene (K8003) and 33 parts of homopolymer polypropylene (1102K) were added and mixed for 8 minutes to obtain a uniform mixture.

[0068] (2) The resulting mixture is transferred to a low-temperature mixer and fed into a continuous internal mixer at a feed rate of 8 r / min. Plasticization is carried out at a melting temperature of 200℃ and a rotation speed of 500 r / min to obtain the mixture melt.

[0069] (3) The obtained mixture melt is fed into a twin-screw extruder for plasticizing and granulation again. The extrusion conditions are: temperature range: 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 215℃, 210℃; extrusion speed: 160rpm, melt flow rate: 55L / min, air cooling and hot cutting: 5.0Hz. The resulting hollow board special masterbatch is dried and then injection molded into standard test strips.

[0070] Example 2

[0071] Same as Example 1, except that the copolymer polypropylene (K8003) and homopolymer polypropylene (1102K) are replaced with copolymer polypropylene (MO2D) and homopolymer polypropylene (1005N).

[0072] Comparative Example

[0073] Same as Example 1, except that the amount of component used in step (1) is different, as follows:

[0074] Table 1

[0075]

[0076] The polypropylene hollow boards produced by the above method were tested, and the results are as follows:

[0077] Table 2

[0078]

[0079] The polypropylene hollow boards produced by the above method were tested after aging, and the results are as follows:

[0080] Aging conditions: UV aging at 50℃ for 28 days.

[0081] Table 3

[0082]

[0083] It is evident that the present invention, by combining two inorganic mineral powders with similar compositions and using dolomite as a reinforcing aggregate, improves the bonding performance between polypropylene and fillers to a certain extent, and can further improve the aging resistance of polypropylene hollow boards.

[0084] Example 3

[0085] Same as Example 1, except that the amounts of copolymer polypropylene and homopolymer polypropylene are changed as follows:

[0086] Table 4

[0087]

[0088] Example 4

[0089] Same as Example 1, except that the amounts of calcium carbonate and dolomite were changed as follows:

[0090] Table 5

[0091]

[0092] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing polypropylene hollow board or a special masterbatch for polypropylene hollow board, characterized in that, It is made from the following components in parts by weight: Dolomite, 8-58 parts Calcium carbonate 8-58 parts 30-60 parts of polypropylene 0.2-1.0 parts of coupling agent, Lubricant 0.2-1.0 parts; Wherein, the polypropylene is a combination of copolymer polypropylene and homopolymer polypropylene; the molecular weight of the copolymer polypropylene is 50,000-500,000 and the melt index is 1.8-2.7 g / 10 min; the molecular weight of the homopolymer polypropylene is 80,000-150,000 and the melt index is 0.5-4 g / 10 min. The dolomite and calcium carbonate are fine powders passing through a mesh of 800-1500.

2. The preparation method according to claim 1, characterized in that, The weight proportions of each component are as follows: Dolomite, 10-53 parts Calcium carbonate 10-53 parts 35-50 parts of polypropylene 0.4-0.8 parts of coupling agent, Lubricant 0.4-0.8 parts.

3. The preparation method according to claim 1, characterized in that, The weight proportions of each component are as follows: Dolomite, 12-48 parts Calcium carbonate 12-48 parts 40 parts of polypropylene 0.6 parts coupling agent, 0.6 parts of lubricant.

4. The preparation method according to any one of claims 1-3, characterized in that, The mass ratio of copolymer polypropylene to homopolymer polypropylene is 0.1-5.2:

1.

5. The preparation method according to any one of claims 1-3, characterized in that, The mass ratio of copolymer polypropylene to homopolymer polypropylene is 0.2-4.7:

1.

6. The preparation method according to any one of claims 1-3, characterized in that, The mass ratio of copolymer polypropylene to homopolymer polypropylene is 7:33, 13:27, 20:20, 27:13 or 33:

7.

7. The preparation method according to any one of claims 1-3, characterized in that, The coupling agent is an aluminate coupling agent and / or a titanate coupling agent; the lubricant is stearic acid and / or zinc stearate.

8. The preparation method according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Premix dolomite and calcium carbonate, add coupling agent, lubricant and polypropylene to obtain a mixture; (2) The resulting mixture is plasticized in an internal mixer to obtain a mixture melt; (3) The resulting mixture melt is plasticized and granulated in a twin-screw extruder to obtain a special masterbatch for polypropylene hollow boards.

9. The preparation method according to claim 8, characterized in that, In step (1), dolomite and calcium carbonate are premixed for 10-20 minutes, coupling agent is added and premixed for 2-8 minutes, lubricant is added and premixed for 2-8 minutes, and polypropylene is added and mixed for 4-12 minutes to obtain a mixture.

10. The preparation method according to claim 8, characterized in that, In step (2), the plasticizing temperature is 180-220℃; in step (3), the temperature range of the twin-screw extruder is 180-190℃, 185-195℃, 190-200℃, 195-205℃, 200-210℃, 205-215℃, 210-220℃, 210-220℃, 205-215℃.

11. The preparation method according to claim 8, characterized in that, In step (2), the plasticizing temperature is 190-210℃; in step (3), the temperature range of the twin-screw extruder is 185℃, 190℃, 195℃, 200℃, 205℃, 210℃, 215℃, 215℃, 210℃.

12. Polypropylene hollow board masterbatch or polypropylene hollow board prepared by the method according to any one of claims 1-11.

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