Inorganic filler for blending of pla and pbat degradable plastic bags and preparation method thereof

Abstract

This invention belongs to the field of inorganic filler technology and discloses an inorganic filler for PLA and PBAT blended degradable plastic bags and its preparation method. The invention involves ball milling or grinding calcium carbonate ore, talc, and wollastonite, followed by cyclone classification to obtain calcium carbonate powder, talc powder, and wollastonite powder, respectively. The three powders are then formulated into a slurry, a grafting agent is added, and after a certain reaction time, the mixture is flash-dried. The flash-dried mixed powder is then surface-treated with a compatibilizer to obtain the inorganic filler for PLA and PBAT blended degradable plastic bags. This invention improves upon the fragility of traditional plastic bags by introducing needle-like wollastonite and platy talc powder. Due to their unique high aspect ratio and platy morphology, these materials effectively prevent stress transmission, improving the tear resistance and toughness of the product and enhancing its mechanical properties. The needle-like filler effectively improves the thermal stability of the product and increases the yield of downstream products.

Description

Technical Field

[0001] This invention relates to the field of inorganic filler technology, and in particular to an inorganic filler for PLA and PBAT blended degradable plastic bags and its preparation method. Background Technology

[0002] Since their introduction, plastic bags have been widely accepted due to their light weight, small size, ease of molding, ability to hold both dry and wet waste, airtight sealing, odor blocking, and low price, and are mostly used for single purposes. However, because plastic bags have low recycling value, their disposal is mostly done through landfill or incineration, generating pollutants that cause significant damage to the natural environment. Their very existence also has a substantial impact on the natural ecosystem.

[0003] Currently, biodegradable plastic bags are mostly made by mixing PBAT or PLA resins, adding inorganic fillers and other additives, and then blow molding them. Under the influence of various factors such as microorganisms in nature, these products can decompose into natural substances such as carbon dioxide, methane, water, and inorganic mineral salts, without causing harm to the environment. Compared with traditional PE and other plastic bags, biodegradable plastic bags are more expensive, and their mechanical properties are slightly inferior for the same resin content.

[0004] Traditional fillers used in biodegradable plastic bags are mostly lightweight nano-calcium carbonate or ultrafine heavy calcium carbonate, both of which are inorganic fillers. Surface modification is mostly simple physical coating, resulting in low compatibility with organic resins such as PLA and PBAT as substrates. Their impact on the mechanical properties of the plastic bag is also limited, offering little help in dimensional stability during blow molding, serving only a basic volume-filling effect. Due to manufacturing processes, even slight damage to current plastic bags causes stress concentration, making them easily torn and unusable, leading to waste and environmental harm.

[0005] Therefore, how to enhance the compatibility between inorganic fillers and biodegradable resins is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide an inorganic filler for PLA and PBAT blended degradable plastic bags and its preparation method, thereby solving the above-mentioned problems existing in the inorganic fillers for biodegradable resins.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing inorganic fillers for PLA and PBAT blended degradable plastic bags, comprising the following steps:

[0009] (1) After washing and crushing, calcium carbonate ore is successively ball-milled and cyclone-classified to obtain calcium carbonate powder.

[0010] Talc is washed, crushed, ground and cyclone-classified to obtain talc powder.

[0011] Wollastonite is washed, crushed, and then ground and cyclone-classified to obtain wollastonite powder.

[0012] (2) Calcium carbonate powder, talc powder and wollastonite powder are prepared into a slurry, grafting agent is added and reacted for a certain time, and then flash-dried. The flash-dried mixed powder is added to a compatibilizer for surface treatment to obtain inorganic filler for PLA and PBAT blended degradable plastic bags.

[0013] Preferably, in the above-mentioned method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags, the ball milling in step (1) is wet ball milling, and the ball milling process also includes the addition of a dispersant and a ball milling aid; the grinding is air jet milling.

[0014] Preferably, in the above-mentioned method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags, the particle size of the calcium carbonate ore after cyclone grading in step (1) is: D97 is 3-6 μm, D50 is 1.4-2.5 μm, less than or equal to 2 μm is 35-80%, and the maximum particle size is 7-8 μm.

[0015] Preferably, in the above-mentioned method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags, the specific surface area of ​​the talc after cyclone grading in step (1) is 6-16 m². 2 / g; The specific surface area of ​​wollastonite after cyclone grading is 5-10m². 2 / g.

[0016] Preferably, in the above-mentioned method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags, the mass ratio of calcium carbonate powder, talc powder and wollastonite powder in step (2) is 50-60:1-50:1-25; and the solid content of the slurry is 50-70%.

[0017] Preferably, in the above-mentioned method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags, the grafting agent in step (2) is one or more of tartaric acid, tartaric acid, maleic acid and lactic acid; the mass of the grafting agent is 1 to 5% of the total mass of calcium carbonate powder, talc powder and wollastonite powder.

[0018] Preferably, in the above-mentioned method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags, the compatibilizer in step (2) is one or more of the following: multi-element epoxy chain extender ADR, trimethylsilyl cage polysilsesquioxane, isocyanate, tributyltin, tributyl acetylacetonate, and maleic anhydride; the mass of the compatibilizer is 1-3% of the total mass of calcium carbonate powder, talc powder, and wollastonite powder.

[0019] Preferably, in the above-mentioned method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags, the reaction time in step (2) is 10 to 20 minutes; the reaction process also includes stirring, and the stirring speed is 50 to 80 r / min.

[0020] Preferably, in the above-mentioned method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags, the surface treatment time in step (2) is 10 to 20 minutes; the surface treatment process also includes stirring, and the stirring speed is 1600 to 2500 r / min.

[0021] The present invention also provides a method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags.

[0022] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) This invention solves the shortcomings of traditional fillers, such as poor compatibility with degradable resins and low reinforcing effect. Traditional fillers are not modified after production, or are simply physically coated with stearic acid or coupling agents. This modification method is generally ineffective, as the binding force between the modifier and the inorganic filler is poor, and it is easy to peel off during subsequent processing, thus affecting the performance of downstream products. This invention uses a chemical grafting method, grafting tartaric acid onto the surface of the inorganic filler. With the help of compatibilizers such as epoxy or maleic anhydride, the firmly attached hydroxyl groups can form a strong bond with PLA and PBAT, improving the compatibility of the inorganic filler with PLA and PBAT, thereby increasing the physical properties of the product.

[0024] (2) This invention improves the problem of traditional plastic bags being easily damaged by introducing wollastonite with a needle-like structure and talc powder with a plate-like structure. Due to their unique high aspect ratio and plate-like morphology, they can effectively prevent the transmission of stress, thereby improving the tear resistance and toughness of the product and enhancing its mechanical properties.

[0025] (3) The needle-shaped packing used in this invention can effectively improve the thermal stability of the product and increase the yield of downstream products.

[0026] (4) The present invention is produced by a ceramic-lined ball mill with a closed all-ceramic structure, which can avoid the corrosion of iron products by various additives and prevent the introduction of impurities. Detailed Implementation

[0027] This invention provides a method for preparing inorganic fillers for PLA and PBAT blended degradable plastic bags, comprising the following steps:

[0028] (1) After washing and crushing, calcium carbonate ore is successively ball-milled and cyclone-classified to obtain calcium carbonate powder.

[0029] Talc is washed, crushed, ground and cyclone-classified to obtain talc powder.

[0030] Wollastonite is washed, crushed, and then ground and cyclone-classified to obtain wollastonite powder.

[0031] (2) Calcium carbonate powder, talc powder and wollastonite powder are prepared into a slurry, grafting agent is added and reacted for a certain time, and then flash-dried. The flash-dried mixed powder is added to a compatibilizer for surface treatment to obtain inorganic filler for PLA and PBAT blended degradable plastic bags.

[0032] In this invention, the ball milling in step (1) is wet ball milling, and the ball milling process also includes the addition of a dispersant and a ball milling aid; the mass of the dispersant and the ball milling aid is 1 to 3‰ of the mass of the calcium carbonate ore; the dispersant is sodium polycarboxylate; the ball milling aid is sodium polyacrylate; and the grinding is air jet milling.

[0033] In this invention, the particle size of the calcium carbonate ore after cyclone grading in step (1) is as follows: D97 is preferably 3-6 μm, more preferably 3.4-5.7 μm, and even more preferably 4.6 μm; D50 is preferably 1.4-2.5 μm, more preferably 1.6-2.3 μm, and even more preferably 1.9 μm; less than or equal to 2 μm is preferably 35-80%, more preferably 39-62%, and even more preferably 54%; the maximum particle size is preferably 7-8 μm, more preferably 7.1-7.8 μm, and even more preferably 7.6 μm.

[0034] In this invention, the specific surface area of ​​the talc after cyclone grading in step (1) is preferably 6-16 m². 2 / g, more preferably 8-13m 2 / g, more preferably 11m 2 / g; The preferred specific surface area of ​​wollastonite after cyclone gradation is 5-10m². 2 / g, more preferably 6-9m 2 / g, more preferably 7m 2 / g.

[0035] In this invention, the mass ratio of calcium carbonate powder, talc powder and wollastonite powder in step (2) is preferably 50-60:1-50:1-25, more preferably 52-59:23-45:7-21, and even more preferably 57:33:16; the solid content of the slurry is preferably 50-70%, more preferably 53-67%, and even more preferably 58%.

[0036] In this invention, the grafting agent in step (2) is preferably one or more of tartaric acid, tartaric acid, maleic acid and lactic acid, more preferably one or more of tartaric acid, maleic acid and lactic acid, and even more preferably tartaric acid; the mass of the grafting agent is preferably 1 to 5% of the total mass of calcium carbonate powder, talc powder and wollastonite powder, more preferably 2 to 4%, and even more preferably 3%.

[0037] In this invention, the compatibilizer in step (2) is preferably one or more of the following: a multi-element epoxy chain extender ADR, trimethylsilyl cage polysilsesquioxane (POSS), isocyanate, tributyltin, tributyl acetylacetonate, and maleic anhydride; more preferably, one or more of the following: a multi-element epoxy chain extender ADR, isocyanate, tributyl acetylacetonate, and maleic anhydride; and more preferably, maleic anhydride. The mass of the compatibilizer is preferably 1-3% of the total mass of calcium carbonate powder, talc powder, and wollastonite powder; more preferably, 1.3-2.6%; and more preferably, 2.1%.

[0038] In this invention, the reaction time in step (2) is preferably 10 to 20 minutes, more preferably 12 to 17 minutes, and even more preferably 14 minutes; the reaction process also includes stirring, and the stirring speed is preferably 50 to 80 r / min, more preferably 57 to 73 r / min, and even more preferably 65 r / min.

[0039] In this invention, the surface treatment time in step (2) is preferably 10 to 20 minutes, more preferably 13 to 17 minutes, and even more preferably 14 minutes; the surface treatment process also includes stirring, and the stirring speed is preferably 1600 to 2500 r / min, more preferably 1700 to 2300 r / min, and even more preferably 2100 r / min.

[0040] The present invention also provides a method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags.

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] This embodiment provides a method for preparing inorganic fillers for PLA and PBAT blended degradable plastic bags, including the following steps:

[0044] (1) After washing and sun exposure, the calcium carbonate ore is crushed once to obtain ore with a diameter of 5-10 cm. Then, it is fed into the silo by an automatic feeder for secondary crushing to obtain calcium carbonate material with a diameter of 5-10 mm. The calcium carbonate material is fed into a ceramic-lined ball mill by an elevator for grinding. By controlling the speed of the classifier, calcium carbonate powder with D97 of 3.5 μm, D50 of 1.38 μm, and less than or equal to 2 μm of 78.29% is obtained.

[0045] Talc is washed, sun-dried, and then crushed once to obtain ore with a diameter of 5-10 cm. This ore is then fed into a hopper via an automatic feeder for secondary crushing, yielding talc material with a diameter of 5-10 mm. The talc material is then fed into an air jet mill for grinding, and the classifier speed is controlled to obtain a specific surface area of ​​14.83 m². 2 / g of talc powder;

[0046] Wollastonite is washed, sun-dried, and then crushed once to obtain ore with a diameter of 5-10 cm. This ore is then fed into a hopper via an automatic feeder for secondary crushing, yielding wollastonite material with a diameter of 5-10 mm. The wollastonite material is then fed into an air jet mill for grinding, and the classifier speed is controlled to obtain a specific surface area of ​​9.33 m². 2 / g of wollastonite powder;

[0047] (2) Calcium carbonate powder, talc powder and wollastonite powder were prepared into a slurry with a solid content of 60% by mass ratio of 50:50:25. Grafting agents tartaric acid and maleic acid were added (the mass of tartaric acid and maleic acid is 1.5% of the total mass of calcium carbonate powder, talc powder and wollastonite powder, respectively). The mixture was stirred at 80 r / min for 15 min and then flash-dried. The flash-dried mixed powder was collected and transferred to a high-speed mixer. Compatibilizers ADR and POSS (the mass of ADR and POSS is 0.5% of the total mass of calcium carbonate powder, talc powder and wollastonite powder, respectively) were added. The mixture was dispersed at 2500 r / min for 15 min, cooled naturally, collected and packaged to obtain inorganic filler for PLA and PBAT blended degradable plastic bags.

[0048] Five batches of inorganic fillers were produced according to the above preparation method, and their properties are shown in Table 1.

[0049] Table 1. Performance of the inorganic packing material in Example 1

[0050]

[0051] Example 2

[0052] This embodiment provides a method for preparing inorganic fillers for PLA and PBAT blended degradable plastic bags, including the following steps:

[0053] (1) After washing and sun exposure, the calcium carbonate ore is crushed once to obtain ore with a diameter of 5-10 cm. Then, it is fed into the silo by an automatic feeder for secondary crushing to obtain calcium carbonate material with a diameter of 5-10 mm. The calcium carbonate material is fed into a ceramic-lined ball mill by an elevator for grinding. By controlling the speed of the classifier, calcium carbonate powder with D97 of 4.84 μm, D50 of 2.02 μm, and less than or equal to 2 μm of 58.17% is obtained.

[0054] Talc is washed, sun-dried, and then crushed once to obtain ore with a diameter of 5-10 cm. This ore is then fed into a hopper via an automatic feeder for secondary crushing, yielding talc material with a diameter of 5-10 mm. The talc material is then fed into an air jet mill for grinding, and the classifier speed is controlled to obtain a specific surface area of ​​11.40 m². 2 / g of talc powder;

[0055] Wollastonite is washed, sun-dried, and then crushed once to obtain ore with a diameter of 5-10 cm. This ore is then fed into a hopper via an automatic feeder for secondary crushing, yielding wollastonite material with a diameter of 5-10 mm. The wollastonite material is then fed into an air jet mill for grinding, and the classifier speed is controlled to obtain a specific surface area of ​​8.05 m². 2 / g of wollastonite powder;

[0056] (2) Calcium carbonate powder, talc powder and wollastonite powder were prepared into a slurry with a solid content of 60% by mass ratio of 60:50:15. Maleic acid grafting agent (the mass of maleic acid is 3% of the total mass of calcium carbonate powder, talc powder and wollastonite powder) was added. The mixture was stirred at 70 r / min for 15 min and then flash-dried. The flash-dried mixed powder was collected and transferred to a high-speed mixer. Maleic anhydride and TBT compatibilizers were added (the mass of maleic anhydride and TBT is 0.5% of the total mass of calcium carbonate powder, talc powder and wollastonite powder, respectively). The mixture was dispersed at 2100 r / min for 15 min. After natural cooling, the mixture was collected and packaged to obtain inorganic filler for PLA and PBAT blended degradable plastic bags.

[0057] Five batches of inorganic fillers were produced according to the above preparation method, and their properties are shown in Table 2.

[0058] Table 2 Performance of Inorganic Packing Material in Example 2

[0059]

[0060]

[0061] Example 3

[0062] This embodiment provides a method for preparing inorganic fillers for PLA and PBAT blended degradable plastic bags, including the following steps:

[0063] (1) After washing and sun exposure, the calcium carbonate ore is crushed once to obtain ore with a diameter of 5-10 cm. Then, it is fed into the silo by an automatic feeder for secondary crushing to obtain calcium carbonate material with a diameter of 5-10 mm. The calcium carbonate material is fed into a ceramic-lined ball mill by an elevator for grinding. By controlling the speed of the classifier, calcium carbonate powder with D97 of 5.95 μm, D50 of 2.47 μm, and less than or equal to 2 μm of 47.6% is obtained.

[0064] Talc is washed, sun-dried, and then crushed once to obtain ore with a diameter of 5-10 cm. This ore is then fed into a hopper via an automatic feeder for secondary crushing, yielding talc material with a diameter of 5-10 mm. The talc material is then fed into an air jet mill for grinding, and the classifier speed is controlled to obtain a specific surface area of ​​8.41 m². 2 / g of talc powder;

[0065] Wollastonite is washed, sun-dried, and then crushed once to obtain ore with a diameter of 5-10 cm. This ore is then fed into a hopper via an automatic feeder for secondary crushing, yielding wollastonite material with a diameter of 5-10 mm. The wollastonite material is then fed into an air jet mill for grinding, and the classifier speed is controlled to obtain a specific surface area of ​​6.27 m². 2 / g of wollastonite powder;

[0066] (2) Calcium carbonate powder, talc powder and wollastonite powder were prepared into a slurry with a solid content of 60% by mass ratio of 60:40:25. Tartaric acid and tartaric acid grafting agents (the mass of tartaric acid and tartaric acid is 1.5% of the total mass of calcium carbonate powder, talc powder and wollastonite powder, respectively) were added. The mixture was stirred at 60 r / min for 15 min and then flash-dried. The flash-dried mixed powder was collected and transferred to a high-speed mixer. Compatibilizers ADR and ATBC (the mass of ADR and ATBC is 0.5% of the total mass of calcium carbonate powder, talc powder and wollastonite powder, respectively) were added. The mixture was dispersed at 1800 r / min for 15 min. After natural cooling, the mixture was collected and packaged to obtain the inorganic filler for PLA and PBAT blended degradable plastic bags.

[0067] Five batches of inorganic fillers were produced according to the above preparation method, and their properties are shown in Table 3.

[0068] Table 3. Performance of the inorganic filler in Example 3

[0069]

[0070] Application Example 1

[0071] According to the formula in Table 4, the inorganic filler and other raw materials of Example 1 were mixed evenly and then added to the extruder for granulation. After granulation, the granulation was blown into a plastic film using a blow molding machine. The film was then prepared into a strip with a width of 10 mm, a length of 40 mm, and a thickness of 3 mil. The mechanical properties of the strip were tested and the right-angle tear strength was tested according to QB / T 1130-91. The conventionally used calcium carbonate inorganic filler was used as a comparison. The results are shown in Table 5.

[0072] Table 4 Plastic Film Formulation

[0073]

[0074] Table 5. Results of mechanical properties of plastic film

[0075]

[0076] As can be seen from the above data, the inorganic filler prepared according to the present invention produces films with better tensile strength and elongation at break than commonly used fillers on the market, and also has higher tear strength, which has significant advantages.

[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing inorganic filler for PLA and PBAT blended degradable plastic bag, characterized in that, Includes the following steps: (1) After washing and crushing, calcium carbonate ore is successively ball-milled and cyclone-classified to obtain calcium carbonate powder; Talc is washed, crushed, ground and cyclone-classified to obtain talc powder. Wollastonite is washed, crushed, and then ground and cyclone-classified to obtain wollastonite powder. (2) Calcium carbonate powder, talc powder and wollastonite powder are prepared into a slurry, grafting agent is added and reacted for a certain time, and then flash drying is carried out. The flash-dried mixed powder is added to a compatibilizer for surface treatment to obtain inorganic filler for PLA and PBAT blended degradable plastic bags. In step (2), the mass ratio of calcium carbonate powder, talc powder, and wollastonite powder is 50-60:1-50:1-25; the solid content of the slurry is 50-70%. In step (2), the grafting agent is one or more of tartaric acid, tartaric acid, maleic acid and lactic acid; the mass of the grafting agent is 1 to 5% of the total mass of calcium carbonate powder, talc powder and wollastonite powder.

2. The method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags according to claim 1, characterized in that, In step (1), the ball milling is wet ball milling, and the process of ball milling also includes the addition of dispersant and ball milling aid; the grinding is air jet milling.

3. The method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags according to claim 1 or 2, characterized in that, The particle size of the calcium carbonate ore after cyclone grading in step (1) is as follows: D97 is 3~6μm, D50 is 1.4~2.5μm, less than or equal to 2μm is 35~80%, and the maximum particle size is 7~8μm.

4. The method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags according to claim 3, characterized in that, The specific surface area of the talc after the cyclone classification in step (1) is 6 to 16 m 2 / g; and the specific surface area of the wollastonite after the cyclone classification is 5 to 10 m 2 / g.

5. A method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags according to claim 1 or 2, characterized in that, In step (2), the compatibilizer is one or more of the following: multi-element epoxy chain extender ADR, trimethylsilyl cage polysilsesquioxane, isocyanate, tributyltin, tributyl acetylacetic acid, and maleic anhydride; the mass of the compatibilizer is 1 to 3% of the total mass of calcium carbonate powder, talc powder, and wollastonite powder.

6. The method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags according to claim 5, characterized in that, The reaction time in step (2) is 10-20 min; the reaction process also includes stirring, and the stirring speed is 50-80 r / min.

7. A method for preparing an inorganic filler for PLA and PBAT blended degradable plastic bags according to claim 1 or 6, characterized in that, The surface treatment time in step (2) is 10~20 min; the surface treatment process also includes stirring, and the stirring speed is 1600~2500 r / min.

8. An inorganic filler for PLA and PBAT blended degradable plastic bags prepared by the method described in any one of claims 1 to 7.

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