Polypropylene composite material, film and blister part

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a polypropylene composite material, a film and a blister part. The polypropylene composite material comprises the following components in percentage by mass: 45%-63% of PP resin; 9%-25% of a modified inorganic filler; 0.45%-1% of a nucleating agent; 4%-10% of a compatilizer; 5%-15% of a flame retardant; the melt mass flow rate of the PP resin under the test conditions of 230 DEG C and 2.16 kg is 0.2 g / 10 min to 5 g / 10 min; the modified inorganic filler comprises an inorganic filler and a coupling agent combined on the surface of the inorganic filler; the flame retardant comprises an intumescent flame retardant. The forming shrinkage rate of the polypropylene composite material can be effectively reduced, the rigidity of the polypropylene composite material is improved, the flatness of a thin-wall blister product made of the polypropylene composite material is improved, and the thin-wall blister product is smooth and free of wrinkles.

Description

Technical Field

[0001] This application belongs to the technical field of polymer materials, and particularly relates to polypropylene composites, films, and plastic suction products. Background Art

[0002] Polymer thin film materials are widely used in the field of new energy power batteries. For example, through the thermoforming process, polymer thin film materials are made into various shaped thermoformed products such as the upper cover of the battery module and the wire harness separator. Polypropylene (PP) materials have excellent chemical resistance, hydrolysis resistance, fold resistance, formability, electrical insulation, extremely low water absorption, low density, and low price, and have received attention in the field of new energy power batteries.

[0003] However, PP itself has poor rigidity. After thermoforming, the product has insufficient stiffness and poor flatness. Moreover, the thermoformed PP is prone to post-shrinkage due to crystallization, resulting in deformation of the thermoformed product, making it difficult to be used to produce flat and highly stiff thermoformed products with a thickness of less than 1 mm. Summary of the Invention

[0004] In view of the above problems, this application provides a PP composite material, film, and thermoformed product, which can solve the problems of poor flatness and stiffness of PP materials when producing thermoformed products with a thickness of less than 1 mm.

[0005] In a first aspect, this application provides a PP composite material, which includes the following components by mass percentage:

[0006] PP resin: 45% - 63%;

[0007] Modified inorganic filler: 9% - 25%;

[0008] Nucleating agent: 0.45% - 1%;

[0009] Compatibilizer: 4% - 10%;

[0010] Flame retardant: 5% - 15%;

[0011] The melt mass flow rate of the PP resin under the test conditions of 230°C and 2.16 kg is 0.2 g / 10 min - 5 g / 10 min; the modified inorganic filler includes an inorganic filler and a coupling agent bonded to the surface of the inorganic filler; the flame retardant includes an intumescent flame retardant.

[0012] The PP resin used in the embodiments of this application has a relatively low melt mass flow rate and belongs to high melt strength PP resin (generally, a low melt flow rate corresponds to high melt strength). Using high melt strength PP resin as the base resin, there will be no phenomenon of overly thin material during the process of processing the PP composite material into a film, and it can improve the problems of collapse and holes when the PP composite material is applied to produce films.

[0013] Meanwhile, by adding modified inorganic fillers, compatibilizers, nucleating agents, and intumescent flame retardants to the PP composite material, the components can interact synergistically to effectively reduce the molding shrinkage rate of the PP composite material and improve the rigidity of the PP composite material, thereby improving the flatness of the thin-walled thermoformed products made of the PP composite material and making them flat and wrinkle-free.

[0014] Specifically, a coupling agent is bonded to the surface of the inorganic filler. The coupling agent is a substance containing an inorganic-philic group and an organic-philic group. The inorganic-philic group contained in the coupling agent has a strong affinity with the molecules or atoms on the surface of the inorganic filler and can bind to the molecules or atoms on the surface of the inorganic filler, so that the coupling agent is bonded to the surface of the inorganic filler. After the coupling agent is bonded to the surface of the inorganic filler, the organic-philic group of the coupling agent is exposed. This organic-philic group can bind to the PP resin. Therefore, the coupling agent can act as a bridge between the inorganic filler and the PP resin, increasing the adhesion between the PP resin and the inorganic filler. However, the interaction force between the organic-philic group of the coupling agent and the PP resin is limited and it is difficult to have a strong interaction. Therefore, in the embodiments of the present application, a compatibilizer is also used for compounding. The polar groups contained in the compatibilizer can have an affinity for the exposed organic-philic groups on the surface of the modified inorganic filler, improving the interfacial adhesion between the PP resin and the modified inorganic filler, so that there is good interfacial compatibility between the inorganic filler and the PP resin, and the inorganic filler and the PP resin can be uniformly mixed, enabling the inorganic filler to play a good role in reducing the molding shrinkage rate of the PP composite material. Specifically, 1) the inorganic filler itself has no shrinkage property, and by adding the inorganic filler, the molding shrinkage rate of the PP composite material can be reduced as a whole; 2) the inorganic filler has a synergistic nucleating effect, promoting the crystallization of the PP resin, changing the structural state of the PP resin, preventing the formation of large spherulites, and thus reducing the molding shrinkage rate of the PP composite material.

[0015] Moreover, the high-rigidity characteristic of the inorganic filler itself can improve the rigidity of the PP composite material and increase the stiffness of the thermoformed product.

[0016] The nucleating agent has the effect of refining the crystal grains of the PP composite material, reducing the spherulite size of the PP composite material, and accelerating the crystallization rate of the PP resin, which is also beneficial to reducing the molding shrinkage rate of the PP composite material. The effect of the nucleating agent in accelerating the crystallization rate of the PP resin can also improve the rigidity of the PP composite material.

[0017] The dosage and type of the flame retardant have an impact on the properties of the material. The intumescent flame retardant has good thermal stability. By adding a certain amount of the intumescent flame retardant to the PP composite material, it can have a certain impact on the melt fluidity of the PP composite material and reduce the thermal shrinkage rate of the PP composite material.

[0018] Therefore, under the combined action of high melt strength PP resin, modified inorganic filler, compatibilizer, nucleating agent and intumescent flame retardant, the shrinkage rate of the PP composite material can be effectively reduced and the rigidity of the PP composite material can be improved, thereby improving the flatness of the thin-walled thermoformed product made of the PP composite material, so that when it is applied to the preparation of thin-walled thermoformed products with a thickness of 1 mm or less, a flat and wrinkle-free effect can also be achieved.

[0019] In some embodiments, by mass percentage, the PP composite material comprises the following components:

[0020] PP resin 49% - 57%;

[0021] Modified inorganic filler 14% - 25%;

[0022] Nucleating agent 0.5% - 1%;

[0023] Compatibilizer 5% - 8%;

[0024] Flame retardant 9% - 15%.

[0025] Matching according to a suitable ratio can give full play to the synergistic effect between the components, reduce the shrinkage rate of the PP composite material and improve the rigidity of the PP composite material, thereby improving the flatness of the thin-walled thermoformed product made of the PP composite material.

[0026] In some embodiments, the melt mass flow rate of the PP resin under the test conditions of 230 °C and 2.16 kg is 1 g / 10 min - 5 g / 10 min.

[0027] Using a PP resin with a relatively high melt strength as the base resin, the phenomenon of too thin material will not occur during the process of processing the PP composite material into a film, improving the problems of collapse and holes when the PP composite material is applied to make a film, and improving the toughness of the material.

[0028] In some embodiments, the inorganic filler includes a first inorganic filler and a second inorganic filler. The first inorganic filler has a particle size passing through a sieve with a mesh size of less than 1000 mesh, and the second inorganic filler has a particle size passing through a sieve with a mesh size of more than 3000 mesh. Optionally, the first inorganic filler has a particle size passing through a sieve with a mesh size of 800 - 1000 mesh, and the second inorganic filler has a particle size passing through a sieve with a mesh size of 3000 - 3500 mesh.

[0029] The larger the mesh number of the sieve, the smaller the particle size of the inorganic filler; the smaller the mesh number of the sieve, the larger the particle size of the inorganic filler. The first inorganic filler has a particle size passing through a sieve with a mesh number below 1000, and the second inorganic filler has a particle size passing through a sieve with a mesh number above 3000, that is, the first inorganic filler has a large particle size and the second inorganic filler has a small particle size. In the examples of this application, it was found in the experiment that there is a certain correlation between the particle size of the inorganic filler and the shrinkage of the PP composite material. By compounding inorganic fillers with different particle sizes, the shrinkage rate of the PP composite material can be effectively reduced, and the shrinkage rate of the PP composite material can have good uniformity.

[0030] In some embodiments, the mass ratio of the first inorganic filler to the second inorganic filler is (0.5 - 3):1, optionally (1 - 2):1.

[0031] By compounding inorganic fillers with different particle sizes in a suitable proportion, the shrinkage rate of the PP composite material can be effectively reduced, and the shrinkage rate of the PP composite material can have good uniformity.

[0032] In some embodiments, in the modified inorganic filler, the mass of the coupling agent is 0.5% - 1.5% of the inorganic filler, optionally 1% - 1.5%.

[0033] Using a suitable amount of coupling agent to modify the inorganic filler can form a modified inorganic filler with organic - affinity groups exposed on the surface, so as to utilize these organic - affinity groups to be affinity with the compatibilizer, and the compatibilizer can be affinity with the PP resin, thereby improving the compatibility between the inorganic filler and the PP resin.

[0034] In some embodiments, the compatibilizer includes one or more of polyvinyl alcohol, maleic anhydride - grafted PP, acrylic acid - grafted PP, methacrylic acid - grafted PP, maleic anhydride - grafted PE, acrylic - butadiene copolymer, ethylene - vinyl acetate, dodecyl sulfonate, dodecyl phosphate, octadecyl sulfonate, octadecyl phosphate, fatty acid, silicone.

[0035] Such compatibilizers have polar groups, which can have an affinity for the organic - affinity groups exposed on the surface of the modified inorganic filler, improving the interfacial adhesion between the PP resin and the modified inorganic filler, enhancing the mixing uniformity of the PP resin and the modified inorganic filler, and thus being beneficial to improving the flatness and stiffness of the thin - wall thermoformed product.

[0036] In some embodiments, the nucleating agent includes β - crystal nucleating agent. Optionally, the nucleating agent can include one or more of amide - type nucleating agents and rare - earth - type nucleating agents.

[0037] Such nucleating agents can accelerate the crystallization rate of PP composites, form fine and dense spherulite particles, have a fast crystallization speed and crystallinity, making the PP molecular chains denser, with good regularity, and increased modulus and hardness.

[0038] In some embodiments, the intumescent flame retardant includes an acid source, a gas source, and a carbon source; the acid source includes one or more of ammonium polyphosphate, aluminum tripolyphosphate, tris(2-chloropropyl) phosphate, triphenyl phosphate, dimethyl methylphosphonate, coated red phosphorus, boric acid; the gas source includes one or more of melamine cyanurate, tris(2,3-dibromopropyl) isocyanurate, piperazine pyrophosphate, polyamide, dicyandiamide; the carbon source includes one or more of polyols, phenolic resins.

[0039] When heated, the carbon source undergoes an esterification reaction under the action of the acid source, dehydrates and crosslinks to form carbonized substances. At the same time, the gas (nitrogen) generated by the gas source acts on these carbonized substances, causing them to expand. The expanded carbonized substances can cover the flame, prevent the development of combustion, and improve the flame retardancy of the PP composite.

[0040] In some embodiments, the mass ratio of the acid source, the gas source, and the carbon source is (6 - 10):(3 - 7):1, optionally (7 - 9):(4 - 6):1.

[0041] Combining the acid source, the gas source, and the carbon source in a certain proportion can not only improve the thermal shrinkage rate of the PP composite, but also make the PP composite have good flame retardancy.

[0042] In some embodiments, the flame retardant further includes a brominated flame retardant. Optionally, the brominated flame retardant includes one or more of octabromoether, hexabromocyclododecane, decabromodiphenylethane, brominated polystyrene, poly(pentabromophenol) acrylate, tris(2,3-dibromopropyl) isocyanurate (TBC).

[0043] In some embodiments, the mass ratio of the intumescent flame retardant to the brominated flame retardant is (5 - 10):1, optionally (6 - 8):1.

[0044] Compound the intumescent flame retardant with the brominated flame retardant can further improve the flame retardancy of the PP composite. And compounding in a suitable proportion can make these flame retardants play a better role.

[0045] In a second aspect, the present application provides a film, which includes the above-mentioned PP composite.

[0046] The PP composite material uses high melt strength PP resin and contains modified inorganic fillers, compatibilizers, nucleating agents, and intumescent flame retardants. Under the synergistic effect of each component, the film containing the PP composite material will have good flatness and stiffness, and can achieve a flat and wrinkle-free effect even when preparing thin-walled thermoformed products with a thickness of 1 mm or less.

[0047] In some embodiments, the thickness of the film is ≤ 1 mm, and optionally 0.25 mm to 1 mm.

[0048] The PP composite material of the present application can be used to make ultra-thin films with a thickness of 1 mm or less, and has good flatness and stiffness.

[0049] In a third aspect, the present application provides a thermoformed product, which includes the above-mentioned film.

[0050] The film containing the PP composite material will have good flatness and stiffness. After being made into a thermoformed product, the surface of the thermoformed product is flat and wrinkle-free. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0052] Figure 1 It is a schematic structural diagram of the upper cover of the battery module in an embodiment of the present application;

[0053] Figure 2 It is a picture of the upper cover of the battery module in Example 1(a) and Example 11(b) of the present application;

[0054] Figure 3 It is a picture of the upper cover of the battery module in Comparative Example 1(a) and Comparative Example 2(b) of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0055] The following will describe in detail the embodiments of the technical solutions of the present application with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, so they are only examples and cannot be used to limit the protection scope of the present application.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above description of the drawings are intended to cover non-exclusive inclusion.

[0057] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0058] Reference to "embodiment" herein means that a particular feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase does not necessarily refer to the same embodiment at every occurrence in the specification, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0059] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0060] In the description of the embodiments of this application, the term "at least one" means one or more, and "a plurality" means two or more. "At least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0061] It should be understood that in various embodiments of this application, the magnitude of the serial numbers of the above processes does not mean the order of execution is prior or posterior. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0062] In the description of the embodiments of the present application, the mass of the relevant components mentioned not only can refer to the specific content of each component, but also can represent the proportional relationship of the masses between the components. Therefore, as long as the content of the relevant components in the description of the embodiments of the present application is scaled up or down proportionally, it is within the scope disclosed in the description of the embodiments of the present application. Specifically, the mass described in the description of the embodiments of the present application can be mass units well-known in the chemical industry such as μg, mg, g, kg, etc.

[0063] Polymer thin film materials have a wide range of applications in the field of new energy power batteries. For example, through the thermoforming process, polymer thin film materials are made into various shaped thermoformed products such as the upper cover of the battery module and the wire harness separator. Currently, the polymer thin film materials applied in the field of new energy power batteries are mainly polyethylene terephthalate (PET) and polycarbonate (PC). However, PET has poor flame retardancy and it is difficult to achieve UL-94V0 flame retardancy; while PC cannot well meet the market demand due to the high price of raw materials and high density (it is not easy to achieve lightweight). Therefore, it is necessary to develop new polymer thin film materials. PP materials have excellent chemical resistance, hydrolysis resistance, fold resistance, formability, electrical insulation, and extremely low water absorption (electrical insulation is not affected by humidity), and low density (0.89 g / cm 3 ~0.91 g / cm 3 , and it is easy to achieve lightweight), and low price, and have received attention in the field of new energy power batteries.

[0064] However, PP itself has poor rigidity, and the stiffness of the thermoformed product is insufficient. Moreover, due to the requirement of the product for flame retardancy, a flame retardant usually needs to be added to PP, and the addition of the flame retardant will exacerbate the reduction of the melt strength of PP, and it is easy to produce a melt collapse phenomenon when the PP composite material is heated. In addition, the PP after thermoforming is prone to post-shrinkage due to crystallization, which causes deformation of the thermoformed product. Therefore, in order to solve the problem of deformation of the thermoformed product caused by PP crystallization, it is necessary to strictly control the processing temperature during thermoforming, and the structure requirements of the thermoformed product are extremely high, that is, it can only be used to manufacture thermoformed products with a specific structure, which limits the application of PP and is not conducive to cost reduction.

[0065] To address the above problems, the related art uses PP in combination with other polymer resins. For example, PP is combined with polyethylene (PE) in order to improve the high-temperature melt strength and stiffness of the PP material and improve the appearance of the PP thermoformed product. However, in fact, the material after the combination of PP and PE still has problems such as low modulus, poor stiffness, poor heat resistance, low melt strength, and large shrinkage rate, and cannot be used to manufacture thin-walled thermoformed products with a thickness of less than 1 mm.

[0066] To enable PP to be used in the production of thin-walled thermoformed products with a thickness of 1 mm or less, good flatness, and no wrinkles, the embodiments of the present application use high melt strength PP resin as the matrix resin in the PP composite material, and adopt the compounding of modified inorganic fillers with compatibilizers, nucleating agents, and intumescent flame retardants. The combined action of the modified inorganic fillers, compatibilizers, nucleating agents, and intumescent flame retardants can adjust the crystallization rate of PP, thereby reducing the shrinkage rate of PP, solving the problem of deformation of thermoformed products caused by PP crystallization, improving the flatness of thermoformed products, and improving the appearance quality of thermoformed products. At the same time, the modified inorganic fillers and nucleating agents can also improve the stiffness of the PP material, which is also beneficial to improving the flatness of thin-walled thermoformed products.

[0067] The PP composite material of the embodiments of the present application can be applied to the production of thin-walled thermoformed products with a thickness of 1 mm or less, such as thin-walled components such as the thermoformed upper cover of a module with a thickness of 0.25 mm to 1 mm for a battery, a wire harness separator component, etc., as well as packaging materials and battery cell transfer packaging materials with a thickness of 1 mm or less.

[0068] The following further elaborates on the present application in conjunction with embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application.

[0069]

PP Composite Material

[0070] The first aspect of the embodiments of the present application provides a PP composite material, which includes the following components by mass percentage:

[0071] PP resin: 45% - 63%;

[0072] Modified inorganic filler: 9% - 25%;

[0073] Nucleating agent: 0.45% - 1%;

[0074] Compatibilizer: 4% - 10%;

[0075] Flame retardant: 5% - 15%;

[0076] The melt mass flow rate of the PP resin under the test conditions of 230°C and 2.16 kg is 0.2 g / 10 min - 5 g / 10 min; the modified inorganic filler includes an inorganic filler and a coupling agent bonded to the surface of the inorganic filler; the flame retardant includes an intumescent flame retardant.

[0077] The melt mass flow rate, also known as the melt index, is the number of grams of melt flowing through a standard orifice every 10 minutes under specified temperature and pressure (load) conditions, and can reflect the flow performance and melt strength of the melt (generally, a low melt flow rate corresponds to high melt strength). The melt mass flow rate can be measured using a melt flow rate instrument with reference to GB / T3682 - 2000.

[0078] Coupling agents are a type of surfactant that can improve the interfacial properties between resins and inorganic materials, usually containing both inorganic - affinity groups and organic - affinity groups. Compatibilizers, also known as compatibilizing agents, are a type of additive that can promote the combination of two incompatible polymers by means of intermolecular bonding forces and usually have polar groups. Nucleating agents are a type of additive that can provide the required crystal nuclei for polymer crystallization and change the crystallization behavior of polymers.

[0079] Intumescent flame retardants are flame retardants that foam and expand at high temperatures, form a porous structure in the polymer matrix, and generate a fluffy carbonaceous foam layer on the surface. Generally, intumescent flame retardants include a carbon source (carbonizing agent), an acid source (carbonization catalyst), and a gas source (expanding agent). When heated, the carbon source dehydrates to form carbide under the action of the acid source, and the carbide forms a fluffy, porous, and closed - structured carbonaceous foam layer under the action of the gas generated by the gas source.

[0080] The types and amounts of each component in the PP composite material can be determined by one or more of infrared spectroscopy, X - ray diffraction spectroscopy, muffle furnace, melt indexer, and chromatography. Specifically, different chemical bond types and functional groups have different infrared absorption capabilities and appear as different characteristic waves in the infrared spectrum. Therefore, the types of organic and inorganic substances in the PP composite material can be identified and quantitatively determined by infrared spectroscopy. At the same time, X - ray diffraction spectroscopy can reflect information such as the structure and crystal form of inorganic materials, and thus can be used to identify the inorganic materials in the PP composite material. The muffle furnace also plays an important role in the determination of mineral component content. In the muffle furnace, by pyrolyzing and calcining the sample at high temperature, the organic and inorganic substances in it can be decomposed into gases or ash residues, which is convenient for further analysis and detection. Therefore, the muffle furnace can be used for further composition analysis and detection of the PP composite material. The melt indexer can be used to measure the melt index (melt mass flow rate) of a substance. In addition, for the compatibilizer and nucleating agent in the PP composite material, qualitative and quantitative analysis can also be carried out in combination with a chromatograph.

[0081] The PP resin used in the embodiments of this application has a low melt mass flow rate and belongs to high - melt - strength PP resin. Using high - melt - strength PP resin as the base resin, there will be no phenomenon of overly dilute material during the process of processing the PP composite material into a film, and it can improve the problems of collapse and hole formation when the PP composite material is applied to make films.

[0082] At the same time, by adding modified inorganic fillers, compatibilizers, nucleating agents, and intumescent flame retardants to the PP composite material, the components interact synergistically to effectively reduce the molding shrinkage rate of the PP composite material and improve the rigidity of the PP composite material, thereby improving the flatness of the thin - walled thermoformed products made of the PP composite material and making them flat and wrinkle - free.

[0083] Specifically, a coupling agent is bonded to the surface of the inorganic filler. The coupling agent is a substance containing an inorganic-philic group and an organic-philic group. The inorganic-philic group contained in the coupling agent has a strong affinity for the molecules or atoms on the surface of the inorganic filler and can bind to the molecules or atoms on the surface of the inorganic filler, thereby binding the coupling agent to the surface of the inorganic filler. After the coupling agent is bonded to the surface of the inorganic filler, the organic-philic group of the coupling agent is exposed. This organic-philic group can bind to the PP resin. Therefore, the coupling agent can serve as a bridge between the inorganic filler and the PP resin, increasing the adhesion between the PP resin and the inorganic filler. However, the interaction between the organic-philic group of the coupling agent and the PP resin is limited and it is difficult to have a strong interaction. Therefore, a compatibilizer is also used for compounding in the embodiments of the present application. The polar group contained in the compatibilizer can have an affinity for the exposed organic-philic group on the surface of the modified inorganic filler, improving the interfacial adhesion between the PP resin and the modified inorganic filler, so that there is good interfacial compatibility between the inorganic filler and the PP resin, and the inorganic filler and the PP resin can be uniformly mixed, enabling the inorganic filler to well play the role of reducing the molding shrinkage rate of the PP composite material. Specifically, 1) The inorganic filler itself has no shrinkage property, and adding the inorganic filler can overall reduce the molding shrinkage rate of the PP composite material; 2) The inorganic filler has a synergistic nucleation effect, promoting the crystallization of the PP resin, changing the structural state of the PP resin, preventing the formation of large spherulites, and thus reducing the molding shrinkage rate of the PP composite material.

[0084] Moreover, the high-rigidity characteristic of the inorganic filler itself can improve the rigidity of the PP composite material and increase the stiffness of the blister product.

[0085] The nucleating agent has the effect of refining the crystal grains of the PP composite material, reducing the spherulite size of the PP composite material, and accelerating the crystallization rate of the PP resin, which is also beneficial to reducing the molding shrinkage rate of the PP composite material. The effect of the nucleating agent in accelerating the crystallization rate of the PP resin can also improve the rigidity of the PP composite material.

[0086] The dosage and type of the flame retardant affect the properties of the material. The intumescent flame retardant has good thermal stability. Adding a certain amount of the intumescent flame retardant to the PP composite material can have a certain impact on the melt flowability of the PP composite material and reduce the thermal shrinkage rate of the PP composite material.

[0087] Therefore, under the combined action of high melt strength PP resin, modified inorganic filler, compatibilizer, nucleating agent and intumescent flame retardant, the shrinkage rate of the PP composite material can be effectively reduced and the rigidity of the PP composite material can be improved, thereby improving the flatness of the thin-walled thermoformed product made of the PP composite material, so that it can also achieve a flat and wrinkle-free effect when applied to the preparation of thin-walled thermoformed products with a thickness of 1 mm or less.

[0088] In some embodiments, by mass percentage, the PP composite material comprises the following components:

[0089] PP resin 49% - 57%;

[0090] Modified inorganic filler 14% - 25%;

[0091] Nucleating agent 0.5% - 1%;

[0092] Compatibilizer 5% - 8%;

[0093] Flame retardant 9% - 15%.

[0094] Mixing in appropriate proportions can give full play to the synergistic effect between the components, reduce the shrinkage rate of the PP composite material and improve the rigidity of the PP composite material, thereby improving the flatness of the thin-walled thermoformed product made of the PP composite material.

[0095] In some embodiments, the mass percentage of the PP resin in the PP composite material can be any point value among 45%, 46%, 48%, 49%, 50%, 52%, 54%, 56%, 57%, 58%, 60%, 62%, 63% or the range value between any two of them.

[0096] The mass percentage of the modified inorganic filler in the PP composite material can be any point value among 9%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25% or the range value between any two of them.

[0097] The mass percentage of the nucleating agent in the PP composite material can be any point value among 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1% or the range value between any two of them.

[0098] The mass percentage of the compatibilizer in the PP composite material can be any point value among 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10% or the range value between any two of them.

[0099] The mass percentage of the flame retardant in the PP composite can be any one of 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15% or a range value between any two of them.

[0100] In some embodiments, the melt mass flow rate of the PP resin under the test conditions of 230 °C and 2.16 kg is 0.2 g / 10 min to 5 g / 10 min, optionally 1 g / 10 min to 5 g / 10 min. For example, it can be any one of 0.2 g / 10 min, 0.5 g / 10 min, 1 g / 10 min, 1.5 g / 10 min, 2 g / 10 min, 2.5 g / 10 min, 3 g / 10 min, 3.5 g / 10 min, 4 g / 10 min, 4.5 g / 10 min, 5 g / 10 min or a range value between any two of them.

[0101] The PP resin has a low melt mass flow rate and belongs to a high melt strength PP resin. Using a high melt strength PP resin as the base resin, there will be no phenomenon of too thin material during the process of processing the PP composite into a film, which can improve the problems of film collapse and holes, and improve the toughness of the material.

[0102] In some embodiments, the weight average molecular weight of the PP resin is (10 - 15)×10 4 , for example, it can be any one of 10×10 4 , 11×10 4 , 12×10 4 , 13×10 4 , 14×10 4 , 15×10 4 or a range value between any two of them.

[0103] The weight average molecular weight is the statistical average molecular weight obtained by averaging the molecular weights of different molecular weights of a polymer. The weight average molecular weight of a polymer can be measured by methods such as light scattering method, ultracentrifugation sedimentation velocity method, and gel chromatography method. The molecular weight of the PP resin is one of the important factors affecting the melt mass flow rate. At this weight average molecular weight, the PP resin has a low melt mass flow rate.

[0104] In some embodiments, the PP resin includes one or more of homopolymer PP and terpolymer PP. Optionally, the PP resin includes homopolymer PP and terpolymer PP. The terpolymer PP can include ethylene-propylene-butene terpolymer PP.

[0105] Optionally, the PP resin includes one or more of T28F, S28F, S38FA, S38CA, and H5300.

[0106] Homopolymer PP and terpolymer PP are PP resins with different structural types, and the type of PP resin can be tested by nuclear magnetic resonance spectroscopy. Homopolymer PP is polymerized from a single propylene monomer, and the regularity of its molecular chain is very high. Therefore, the material has a high crystallinity, which is beneficial to improving the uniformity of the film during the processing of PP composites into films, thereby improving the shrinkage rate and rigidity of the film. Terpolymer PP usually exhibits a high melt strength, which can improve the viscosity of PP composites during processing, improve problems such as film collapse and holes, and improve the toughness of the material. When homopolymer PP and terpolymer PP are compounded and used, both high melt strength and good crystallization ability can be achieved.

[0107] In some embodiments, the inorganic filler includes a first inorganic filler and a second inorganic filler, wherein the first inorganic filler has a particle size passing through a sieve with a mesh size of 1000 mesh or less, and the second inorganic filler has a particle size passing through a sieve with a mesh size of 3000 mesh or more. Optionally, the first inorganic filler has a particle size passing through a sieve with a mesh size of 800 - 1000 mesh, and the second inorganic filler has a particle size passing through a sieve with a mesh size of 3000 - 3500 mesh.

[0108] For example, the first inorganic filler has a particle size passing through any one of the sieve meshes of 200 mesh, 300 mesh, 400 mesh, 500 mesh, 600 mesh, 700 mesh, 800 mesh, 900 mesh, 1000 mesh or a range value between any two of them. The second inorganic filler has a particle size passing through any one of the sieve meshes of 3000 mesh, 3500 mesh, 4000 mesh, 4500 mesh, 5000 mesh or a range value between any two of them.

[0109] Generally, the method of sieving can be used to select inorganic fillers with the desired particle size. The larger the mesh number of the sieve, the smaller the particle size of the inorganic filler; the smaller the mesh number of the sieve, the larger the particle size of the inorganic filler. The first inorganic filler has a particle size passing through a sieve with a mesh size of 1000 mesh or less, and the second inorganic filler has a particle size passing through a sieve with a mesh size of 3000 mesh or more, that is, the first inorganic filler has a large particle size and the second inorganic filler has a small particle size. In the experiments of the embodiments of the present application, it is found that there is a certain correlation between the particle size of the inorganic filler and the shrinkage of the PP composite material. By compounding inorganic fillers with different particle sizes, the shrinkage rate of the PP composite material can be effectively reduced, and the shrinkage rate of the PP composite material can have good uniformity.

[0110] In some embodiments, the mass ratio of the first inorganic filler to the second inorganic filler is (0.5 to 3):1, optionally (1 to 2):1. For example, it can be any one of the point values such as 0.5:1, 0.6:1, 0.8:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1 or the range value between any two of them.

[0111] By compounding inorganic fillers with different particle sizes in a suitable proportion, the shrinkage rate of the PP composite can be effectively reduced, and the shrinkage rate of the PP composite can have good uniformity.

[0112] In some embodiments, the inorganic filler includes one or more of aluminum hydroxide, magnesium hydroxide, boehmite, zinc borate, silica, wollastonite, metal nitrate, calcium carbonate, talc powder, quartz powder, silica powder, antimony trioxide, fluoroborate.

[0113] These materials have non-shrinkage properties, act as fillers in the PP composite and do not crystallize themselves, have a synergistic nucleation effect, and have high rigidity, which can well reduce the shrinkage rate of the PP composite and improve the rigidity of the PP composite.

[0114] In some embodiments, in the modified inorganic filler, the mass of the coupling agent is 0.5% to 1.5% of the inorganic filler, optionally 1% to 1.5%. For example, any one of the point values such as 0.5%, 0.7%, 1%, 1.2%, 1.4%, 1.5% or the range value between any two of them.

[0115] The dosage of the coupling agent is related to the variety of the coupling agent and the specific surface area of the inorganic filler. Calculated according to monolayer adsorption, the dosage can be calculated by the following formula:

[0116] Coupling agent dosage = (mass of inorganic filler g × specific surface area of inorganic filler m 2 / g) / minimum wetting area of coupling agent m 2 / g. Generally speaking, the actual dosage should be less than the dosage calculated by the above formula. The following Table 1 shows the minimum wetting areas of several coupling agents.

[0117] [Table 1]

[0118] Coupling agent grade KH560 KH570 A151 KH550 <![CDATA[Minimum wetting area m 2 / g]]> 322 316 411 351

[0119] When the specific surface area of the inorganic filler or the minimum wetting area of the coupling agent cannot be determined, the dosage of the coupling agent can be selected as 0.5% to 1.5% of the mass of the inorganic filler, optionally 1% to 1.5%.

[0120] For inorganic fillers without internal pores and without strong adsorption properties, the empirical data in the following table can be used:

[0121] [Table 2]

[0122] Particle size of inorganic filler (μm) Coupling agent dosage (mass percentage of inorganic filler) ≤1 1.5％ 1～10 1.0％ 10～20 0.75％ Particle size is similar to or coarser than that of sea sand ≤0.1％

[0123] Using an appropriate amount of coupling agent to modify the inorganic filler can form a modified inorganic filler with a certain amount of organophilic groups exposed on the surface, so as to utilize these organophilic groups to affinity with the compatibilizer, thereby improving the compatibility between the inorganic filler and the PP resin.

[0124] In some embodiments, the coupling agent includes one or more of silane coupling agents and titanate coupling agents. For example, silane coupling agents can include KH550, KH560, KH570, A151, etc.

[0125] When using a silane coupling agent to modify the inorganic filler, the -RO (R represents an alkyl group) group (inorganic-philic group) of the silane coupling agent can hydrolyze in water (including the free water adsorbed on the surface of the inorganic filler) to generate silanol groups. The silanol groups can chemically combine with the molecules or atoms (such as oxygen atoms) on the surface of the inorganic filler to form siloxane bonds, and the siloxane bonds can also combine with the silanol groups generated by the hydrolysis of the silane coupling agent. Thus, under the action of these chemical bonds, the silane coupling agent can be firmly bonded to the surface of the inorganic filler, and the moisture on the surface of the inorganic filler can be removed, reducing the adverse effects of moisture on the PP composite. After the silane coupling agent is bonded to the surface of the inorganic filler through the inorganic-philic group, the organic groups contained therein are exposed on the surface of the modified inorganic filler, forming a coating film with reactive activity.

[0126] In some embodiments, the compatibilizer includes one or more of polyvinyl alcohol, maleic anhydride grafted PP (PP-g-MAH), acrylic acid grafted PP (PP-g-AA), methacrylic acid grafted PP (PP-g-MAA), maleic anhydride grafted PE, acrylic acid-butadiene copolymer, ethylene vinyl acetate, dodecyl sulfonate, dodecyl phosphate, octadecyl sulfonate, octadecyl phosphate, fatty acids (such as stearic acid), and silicone.

[0127] For example, the compatibilizer can include one or more of CMG9801, CMG5701, and CMG5001-T.

[0128] Such compatibilizers have polar groups and can have an affinity for the organophilic groups exposed on the surface of the modified inorganic filler, improving the interfacial adhesion between the PP resin and the modified inorganic filler, enhancing the mixing uniformity of the PP resin and the modified inorganic filler, and thus being beneficial to improving the flatness and stiffness of the thin-wall thermoformed product.

[0129] In some embodiments, the nucleating agent includes a β-form nucleating agent. Optionally, the nucleating agent may include one or more of amide nucleating agents and rare earth nucleating agents. For example, it may include one or more of sorbitol acetal 3988, NX8000, oxamide, xylitol acetal, ADK STAB NA-11, TMB4, and TMY4.

[0130] Such nucleating agents can accelerate the crystallization rate of the PP composite material, form fine and dense spherulite particles, have a fast crystallization rate and crystallinity, make the PP molecular chains more dense, have good regularity, and improve the modulus and hardness.

[0131] In some embodiments, the intumescent flame retardant includes an acid source, a gas source, and a carbon source; the acid source includes one or more of ammonium polyphosphate (APP), aluminum tripolyphosphate, tris(2-chloropropyl) phosphate, triphenyl phosphate, dimethyl methylphosphonate, coated red phosphorus, and boric acid; the gas source includes one or more of melamine cyanurate (MCA), tris(2,3-dibromopropyl) isocyanurate, piperazine pyrophosphate, polyamide, and dicyandiamide; the carbon source includes one or more of polyols and phenolic resins. Among them, the polyols may include one or more of pentaerythritol and ethylene glycol.

[0132] The acid source, gas source, and carbon source form a ternary intumescent flame retardant. When heated, the carbon source undergoes an esterification reaction under the action of the acid source, dehydrates and crosslinks to form carbonized substances. At the same time, the gas (nitrogen) generated by the gas source acts on these carbonized substances, causing them to expand. The expanded carbonized substances can cover the flame, prevent the development of combustion, and improve the flame retardant performance of the PP composite material.

[0133] In some embodiments, in the intumescent flame retardant, the mass ratio of the acid source, gas source, and carbon source is (6-10):(3-7):1, optionally (7-9):(4-6):1. For example, it can be any one of 6:3:1, 6:5:1, 6:7:1, 7:3:1, 7:5:1, 7:7:1, 8:3:1, 8:5:1, 8:7:1, 9:3:1, 9:5:1, 9:7:1, 10:3:1, 10:5:1, 10:7:1 or the range value between any two of them.

[0134] Combining the acid source, gas source, and carbon source in a certain proportion can enable the PP composite material to have good flame retardant performance. Moreover, the compounding of the three can also improve the thermal shrinkage rate of the PP composite material.

[0135] In some embodiments, the flame retardant further includes a brominated flame retardant. Optionally, the brominated flame retardant includes one or more of octabromoether, hexabromocyclododecane, decabromodiphenylethane, brominated polystyrene, poly(pentabromophenol) acrylate, and tris(2,3-dibromopropyl) isocyanurate (TBC).

[0136] Brominated flame retardants begin to decompose above 280°C and capture free radicals decomposed from the PP composite material, thereby delaying and inhibiting the combustion chain reaction. At the same time, non-combustible gases are released, and the flame-retardant gases can further cover and self-extinguish, achieving the purpose of preventing the material from burning. Combining intumescent flame retardants with brominated flame retardants can enhance the flame retardancy of the PP composite material, enabling the PP composite material to reach the VTM-0 flame retardancy level even at a thickness of 1 mm or less.

[0137] In some embodiments, the mass ratio of the intumescent flame retardant to the brominated flame retardant is (5-10):1, optionally (6-8):1. For example, it can be any one of the point values of 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or the range value between any two of them.

[0138] Compound the intumescent flame retardant with the brominated flame retardant, which can further improve the flame retardancy of the PP composite material. And compounding in a suitable proportion can enable these flame retardants to play a better role.

[0139] In some embodiments, the flame retardant further includes one or more of tris(1,3-dichloropropyl) phosphate (TDCPP), silicon-based compounds, melamine polyphosphate (MPP), zinc borate, diisopropylbenzene phosphate, and phosphorus-containing polyols.

[0140] These flame retardants also have good flame retardant effects. Adding these flame retardants to the PP composite material can improve the flame retardancy of the PP composite material.

[0141] In some embodiments, the PP composite material further includes other coupling agents, that is, coupling agents that do not form modified inorganic fillers with inorganic fillers. Optionally, the mass percentage of the coupling agent in the PP composite material is 0.1% - 1%. For example, it can be any one of the point values of 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1% or the range value between any two of them.

[0142] Optionally, the coupling agent includes one or more of vinyl silane coupling agents, amino silane coupling agents, titanate coupling agents, and aluminum-titanium composite coupling agents.

[0143] In the embodiments of the present application, a coupling agent (the first coupling agent) is bound to the surface of the inorganic filler to form a modified inorganic filler, which has good compatibility with the PP resin. By additionally adding a coupling agent (the second coupling agent) to the PP composite material, the second coupling agent can also serve as a bridge between the modified inorganic filler and the PP resin, and can better enhance the binding ability between the modified inorganic filler and the PP resin.

[0144] Understandably, in the embodiments of the present application, the PP composite material may include the second coupling agent or may not include the second coupling agent.

[0145] In some embodiments, the PP composite material further includes an antioxidant. Optionally, the mass percentage of the antioxidant in the PP composite material is 0.1% - 1%, for example, it can be any one of the point values of 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1% or the range value between any two of them.

[0146] Optionally, the antioxidant includes one or more of antioxidant 1010 and antioxidant 168. When multiple antioxidants are used in combination, they can be combined in any proportion. Exemplarily, antioxidant 168 and antioxidant 1010 can be combined and used in a mass ratio of (1 - 3):1, for example, 1:1, 2:2, 3:1, any one of the point values or the range value between any two of them.

[0147] Adding an antioxidant to the PP composite material can prevent the attack of water molecules and light in the air on the molecular chain segments of the material during the processing and later use processes, and improve the material degradation problem.

[0148] In some embodiments, the PP composite material further includes a lubricant. Optionally, the mass percentage of the lubricant in the PP composite material is 0.1% - 1%, for example, it can be any one of the point values of 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1% or the range value between any two of them.

[0149] Optionally, the lubricant includes one or more of amide lubricants, polyethylene wax, and stearate lubricants. The amide lubricants include one or more of erucamide, oleamide, and ethylene bisstearamide (EBS).

[0150] Under the action of the lubricant, during the processing of the PP composite material, the lubricant can improve the lubricity between the material and the equipment, promote demolding, prevent the material from sticking to the mold, and is beneficial to material processing.

[0151] In some embodiments, the PP composite material further includes a masterbatch. Optionally, the mass percentage of the masterbatch in the PP composite material is 0.1% - 5%, for example, it can be any one of the point values of 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or the range value between any two of them.

[0152] Optionally, the masterbatch includes black Cabot 6269, carbon black, etc.

[0153] By adding color masterbatch, the PP composite material can exhibit the desired color, meeting the color requirements of the PP composite material under different application scenarios.

[0154] In some embodiments, by mass percentage, the PP composite material comprises the following components:

[0155] PP resin 45% - 63%;

[0156] Modified inorganic filler 9% - 25%;

[0157] Nucleating agent 0.45% - 1%;

[0158] Compatibilizer 4% - 10%;

[0159] Flame retardant 5% - 15%;

[0160] Coupling agent 0.1% - 1%;

[0161] Antioxidant 0.1% - 1%;

[0162] Lubricant 0.1% - 1%;

[0163] Color masterbatch 0.1% - 5%.

[0164]

Preparation of PP Composite Material

[0165] The PP composite material of the embodiments of the present application can be obtained by the following method.

[0166] In the embodiments of the present application, the preparation method of the PP composite material comprises:

[0167] Melting and kneading the PP resin with the modified inorganic filler, compatibilizer, nucleating agent, and flame retardant to obtain the PP composite material.

[0168] Melting and kneading is a polymer processing technology that melts the polymer components in the material to form a flowable state and uniformly mixes them with other components to form a homogeneous mixture.

[0169] After the PP resin is melted and kneaded with the modified inorganic filler, compatibilizer, nucleating agent, and flame retardant, the components such as the modified inorganic filler, compatibilizer, nucleating agent, and flame retardant can be uniformly dispersed in the PP resin, forming a homogeneous whole, thereby exerting the synergistic effect of the modified inorganic filler, compatibilizer, nucleating agent, and flame retardant, improving the flatness of the thin-walled thermoformed product made of the PP composite material, and enabling it to achieve a flat and wrinkle-free effect when applied to the preparation of thin-walled thermoformed products with a thickness of 1 mm or less.

[0170] In some embodiments, the modified inorganic filler can be prepared by the following method: mixing the inorganic filler with a coupling agent and performing a heat treatment to obtain the modified inorganic filler. Optionally, the heating temperature is 110°C to 130°C, for example, it can be any one of 110°C, 115°C, 120°C, 125°C, 130°C or the range value between any two of them; the heating time is 2h to 5h, for example, it can be any one of 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h or the range value between any two of them.

[0171] Under heating conditions, the molecules or atoms on the surface of the inorganic filler chemically combine with the polar groups of the coupling agent, forming a coupling agent coating film on the surface of the inorganic filler, and the coating film exposes non-polar groups that have good affinity with the PP resin, making the coating film have reactive activity and capable of binding with the PP resin during the processing.

[0172] In some embodiments, the melt mixing treatment is carried out in a twin-screw extruder, and the twin-screw extruder includes a toothed disk provided on the screw.

[0173] The toothed disk is a shearing and dispersing element in the screw, usually provided at the tail of the screw. Its toothed structure can be used to shear and disperse the material, improving the mixing uniformity of the material, so that components such as the modified inorganic filler, nucleating agent, compatibilizer, and flame retardant are uniformly mixed with the PP resin, and improving the stiffness and flatness of the PP composite material.

[0174] In some embodiments, the screws of the twin-screw extruder are sequentially provided with engagement blocks, dispersion disks, and toothed mixing elements along the axial direction; the screw combination of the twin-screw extruder includes any one or more of the following 1) to 4):

[0175] 1) The length-diameter ratio of the screw is greater than or equal to 48:1, for example, (48 - 55):1, more specifically, such as any one of 48:1, 50:1, 52:1, 55:1 or the range value between any two of them;

[0176] 2) It includes at least one engagement block, optionally including 2 to 5 engagement blocks; optionally, the stagger angle between adjacent teeth of the engagement block is 30° to 60°, optionally 40° to 45°, such as any one of 30°, 40°, 45°, 60° or the range value between any two of them; optionally, the length of any one engagement block is 50mm to 60mm, for example, any one of 50mm, 52mm, 54mm, 56mm, 58mm, 60mm or the range value between any two of them;

[0177] 3) It includes more than 2 dispersion disks, optionally including 2 to 5 dispersion disks, such as any one of 2, 3, 4, 5 or the range value between any two of them;

[0178] 4) It includes at least 2 sets of tooth-shaped mixing elements, optionally including 2 to 5 sets of tooth-shaped mixing elements, such as any one of 2, 3, 4, 5 or the range value between any two of them.

[0179] The melting and mixing treatment is carried out in a twin-screw extruder, and the materials pass through the kneading blocks, dispersion disks, and tooth-shaped mixing elements in sequence.

[0180] The kneading blocks can perform distributive mixing and dispersive mixing on each material, improving the compatibility between the modified inorganic filler and the PP resin. Generally, the kneading blocks include several sections of teeth, such as 5 sections of teeth, and the adjacent sections of teeth are arranged according to a certain stagger angle. The size of the stagger angle between adjacent sections of teeth is related to the material conveying capacity, which in turn affects the material residence time, that is, affects the mixing time of the material, and has a regulating effect on the mixing effect. That is to say, the distributive mixing and dispersive mixing are affected by the stagger angle between adjacent sections of teeth in the kneading blocks, and at a certain stagger angle, the distributive mixing and dispersive mixing of the materials can be well achieved.

[0181] The dispersion disks fully disperse each material, such as components like the modified inorganic filler and flame retardant, which is beneficial to improving the material flow splitting and the interfacial compatibility between the PP resin and components such as the modified inorganic filler and flame retardant. The tooth-shaped mixing elements mix the materials using their tooth-shaped structures, which can strengthen the dispersive mixing of the PP resin with components such as the modified inorganic filler and flame retardant.

[0182] Under a special screw combination, the dispersibility of the materials can be fully improved, making the PP composite material have excellent flatness after being processed into a film.

[0183] In some embodiments, the temperature of the melting and mixing treatment is 180°C to 220°C, optionally 200°C to 220°C, such as any one of 180°C, 190°C, 200°C, 210°C, 220°C or the range value between any two of them. Within this temperature range, the materials can be well mixed and melted.

[0184] Specifically, the melting and mixing treatment is carried out in a twin-screw extruder, and the temperatures of each section of the twin-screw extruder can be set as follows: Zone 1: 180°C to 200°C; Zone 2: 200°C to 220°C; Zone 3: 200°C to 220°C; Zone 4: 200°C to 220°C; Zone 5: 190°C to 210°C; Zone 6: 190°C to 210°C; Zone 7: 190°C to 210°C; Zone 8: 180°C to 200°C; Zone 9: 180°C to 200°C; Head zone: 200°C to 220°C.

[0185] In a twin-screw extruder, each material is processed in the barrel (screw bore). In the barrel, starting from the material inlet of the barrel, it is zone 1, and then towards the discharge port, it is zone 2, zone 3, and so on in sequence. That is, for a ten-zone twin-screw extruder, after zone 1 and towards the discharge port, they are zone 2, zone 3, zone 4, zone 5, zone 6, zone 7, zone 8, zone 9 in sequence. After the material comes out of the barrel, the die that shapes the material is the head, and the corresponding zone is the head zone. For a ten-zone twin-screw extruder, usually, the material is fed in zone 1, melted and plasticized in zones 2, 3, and 4, mixed in zones 5, 6, and 7, homogenized in zones 8 and 9, and extruded and formed in the head zone.

[0186] The process parameters of the twin-screw extruder can also include: the main machine speed is 200 rpm to 400 rpm (such as any one of the point values of 200 rpm, 300 rpm, 400 rpm or the range value between any two of them); the vacuum degree in the head vacuum chamber is less than -0.06 Mpa (such as any one of the point values of -0.04 MPa, -0.045 MPa, -0.05 MPa, -0.055 MPa or the range value between any two of them); the water passing distance of the material strip is 3 m to 4 m (such as any one of the point values of 3 m, 3.2 m, 3.4 m, 3.6 m, 3.8 m, 4 m or the range value between any two of them); the frequency of the pelletizer is 800 rpm to 1100 rpm (such as any one of the point values of 800 rpm, 900 rpm, 1000 rpm, 1100 rpm or the range value between any two of them).

[0187] In some embodiments, the melt mixing treatment includes a first melt mixing treatment and a second melt mixing treatment. The PP resin is subjected to the first melt mixing treatment with the modified inorganic filler, flame retardant, and compatibilizer to obtain masterbatch; the masterbatch is subjected to the second melt mixing treatment with the nucleating agent to obtain the PP composite material.

[0188] By sequentially performing the two melt mixing treatments, the materials can be mixed more evenly, which is beneficial for the PP composite material to nucleate and crystallize in a uniform state, and improves the flatness of the PP composite material when made into a film. The first melt mixing treatment and the second melt mixing treatment can adopt the same screw combination.

[0189] In some embodiments, the PP composite material further includes one or more of a coupling agent, antioxidant, lubricant, and color masterbatch. The preparation method of the PP composite material includes: mixing the masterbatch with the nucleating agent and one or more of the coupling agent, antioxidant, lubricant, and color masterbatch, and performing the second melt mixing treatment to obtain the PP composite material.

[0190] Among them, the rotation speed for mixing the masterbatch with a nucleating agent and one or more of a coupling agent, an antioxidant, a lubricant, and a color masterbatch is 200 rpm to 400 rpm, such as any one of 200 rpm, 300 rpm, and 400 rpm or a range value between any two of them, and the mixing time is 100 s to 120 s, such as any one of 100 s, 105 s, 110 s, 115 s, and 120 s or a range value between any two of them.

[0191] Among them, the coupling agent can act as a bridge between the inorganic filler and the PP resin, and can better enhance the binding ability between the inorganic filler and the PP resin. The antioxidant can prevent the attack of water molecules and light in the air on the molecular chain segments of the material during the processing process and the later use process, and improve the material degradation problem. Under the action of the lubricant, during the processing of the PP composite material, the lubricant can improve the lubricity between the material and the equipment, promote demolding, prevent the material from sticking to the mold, and is beneficial to material processing. By adding the color masterbatch, the PP composite material can show the required color and meet the color requirements of the PP composite material in different application scenarios.

[0192]

Film

[0193] In the second aspect of the embodiments of the present application, a film is provided, and the film includes the above-mentioned PP composite material.

[0194] The PP composite material uses a high melt strength PP resin and includes a modified inorganic filler, a compatibilizer, a nucleating agent, and a flame retardant with a specific composition. Under the synergistic action of each component, the film containing the PP composite material will have good flatness and stiffness, and can achieve a flat and wrinkle-free effect even when preparing thin-walled thermoformed products with a thickness of 1 mm or less.

[0195] In some embodiments, the thickness of the film ≤ 1 mm, optionally 0.25 mm to 1 mm, such as any one of 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm or a range value between any two of them.

[0196] The PP composite material of the present application can be used to make ultra-thin films with a thickness of 1 mm or less, and has good flatness and stiffness.

[0197]

Preparation of Film

[0198] The film of the embodiments of the present application can be prepared by the following method.

[0199] In the embodiments of the present application, the method for preparing the thin film includes:

[0200] Heat-melt the PP composite material and perform film-forming treatment to obtain a thin film.

[0201] By heating and melting the PP composite material and performing film-forming processing, a thin film can be formed. The PP composite material uses a high melt strength PP resin and contains a modified inorganic filler, a compatibilizer, a nucleating agent, and a flame retardant with a specific composition. Under the synergistic effect of each component, the thin film made of the PP composite material will have very good flatness, and even when preparing thin-walled thermoformed products with a thickness of 1 mm or less, a flat and wrinkle-free effect can be achieved.

[0202] In some embodiments, the temperature for heat-melting is 190°C to 210°C, for example, any one of the point values of 190°C, 195°C, 200°C, 205°C, 210°C or the range value between any two of them.

[0203] At high temperature, the PP composite material melts and can be used for film-forming processing.

[0204] In some embodiments, the method for film-forming treatment includes one or more of cast stretching and blown film stretching.

[0205] In the molten state, the PP composite material can be formed into a thin film by different methods. The stretching step in cast stretching and blown film stretching can adopt unidirectional cast stretching. Under unidirectional cast stretching, the PP composite material can be subjected to unidirectional stress, which is beneficial to improving the uniformity of the PP composite material during the stretching process, making the formed thin film uniform and not easily generating holes, collapse and tearing.

[0206] In some embodiments, the film-forming treatment includes cast stretching, and the cast stretching includes: using a casting roller to stretch and form a film on the heat-melted material. Among them, there are at least 2 casting rollers. The temperature of the first casting roller through which the heat-melted material passes can be set to 120°C to 160°C (for example, any one of the point values of 120°C, 130°C, 140°C, 150°C, 160°C or the range value between any two of them), and the temperature of the other casting rollers after the first casting roller can be set to 15°C to 30°C (for example, any one of the point values of 15°C, 20°C, 25°C, 30°C or the range value between any two of them. For the convenience of operation, the other casting rollers after the first casting roller can be at ambient temperature).

[0207] During the cast stretching process, the temperature of the casting rollers contacted by the molten material decreases in sequence, which can gradually cool the material and form a thin film under the stretching action of the casting rollers, making the thin film have very good flatness.

[0208] In some embodiments, the linear velocity of any one casting roll can be set to 15 m / min to 22 m / min, for example, any one of the point values such as 15 m / min, 16 m / min, 18 m / min, 20 m / min, 22 m / min or the range value between any two of them. By adjusting the linear velocity of the casting roll, the thickness of the film can be adjusted.

[0209] In some embodiments, the distance between two adjacent casting rolls is ≤ 1 mm, optionally 0.25 mm to 1 mm, for example, any one of the point values such as 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm or the range value between any two of them. By adjusting the gap between the casting rolls, the thickness of the film can be adjusted.

[0210]

Blister

[0211] The third aspect of the embodiments of the present application provides a blister, which includes the above-mentioned film.

[0212] The film containing the PP composite material will have good flatness and stiffness. After being made into a blister, the surface of the blister is flat and free of wrinkles.

[0213] In some embodiments, the area of the blister ≥ 1.5 m 2 . The film of the present application can be used to prepare large-area blisters and keep the surface flat and free of wrinkles.

[0214] In some embodiments, the blister includes one or more of a battery module upper cover, a wire harness separator, an end insulation cover, and a packaging material. Optionally, the battery module upper cover has a bending structure; the wire harness separator has a large plane, for example, an area ≥ 1.5 m 2 ; the packaging material may include a battery cell transfer packaging material.

[0215] Among them, the battery module upper cover can refer to Figure 1 . The battery module upper cover, that is, the upper cover of the battery module, is a component in the battery module used to protect the battery cells from being contaminated and damaged by external objects and having insulation properties. The film of the present application can be used to make battery module upper covers of various shapes. Even if the battery module upper cover has a bending structure, the surface can still be kept flat and free of wrinkles.

[0216] The wire harness separator is an electrical component used to separate and isolate wire harnesses to ensure that wires do not cross or contact each other, thereby avoiding short circuits, and has wide applications in various fields.

[0217] The plastic suction parts can be obtained by thermoforming a film.

[0218] Among them, the thermoforming can be carried out under high-temperature and negative-pressure conditions. For example, under the conditions of a high temperature of 400°C to 500°C (such as any one of the point values of 400°C, 420°C, 440°C, 460°C, 480°C, 500°C or the range value between any two of them), and a pressure of -0.04 to 0.1 MPa (such as any one of the point values of -0.04 MPa, -0.06 MPa, -0.08 MPa, -0.09 MPa, -0.1 MPa or the range value between any two of them), the thermoforming is carried out.

[0219] According to needs, after thermoforming, treatments such as blanking can also be carried out.

[0220] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those without specific technologies or conditions noted in the embodiments, the technologies or conditions described in the literature in the field or according to the product specifications are followed. For the reagents or instruments without the manufacturer noted, they are all conventional products that can be obtained through commercial purchases.

[0221] [PP composite material, film]

[0222] Example 1

[0223] This embodiment provides a PP composite material and also provides a film formed by casting and stretching of the PP composite material.

[0224] (1) PP composite material

[0225] The PP composite material includes components with the mass percentages shown in Table 3-1; for the convenience of actual operation, the mass parts of the corresponding components are also given in Table 3-2.

[0226] Among them, the PP resin is a homopolymer PP with a weight-average molecular weight of 10W, and the melt mass flow rate under the test conditions of 230°C and 2.16 kg is about 3 g / 10 min, and the product grade is T28F.

[0227] The modified inorganic filler includes talcum powder and the silane coupling agent KH550 combined on the surface of the talcum powder. The talcum powder includes the first talcum powder passing through an 800-mesh sieve and the second talcum powder passing through a 3500-mesh sieve, and the mass ratio of the first talcum powder to the second talcum powder is 2:1; the mass of KH550 is 1% of the talcum powder. The preparation method of the modified inorganic filler is: in a high-speed disperser, the talcum powder and KH550 are mixed at 110°C for 3 h to obtain the modified inorganic filler.

[0228] The nucleating agent is sorbitol acetal 3988.

[0229] The compatibilizer is CMG9801 (Jiayirong).

[0230] The flame retardants include a ternary intumescent flame retardant (hereinafter referred to as ternary flame retardant) and a brominated flame retardant, decabromodiphenylethane. The mass ratio of the ternary flame retardant to the brominated flame retardant is 7:1; among them, the ternary flame retardant includes ammonium polyphosphate (APP), melamine cyanurate (MCA) and pentaerythritol with a mass ratio of 8:5:1.

[0231] The coupling agent is KH550.

[0232] The antioxidant is a compound of antioxidant 168 and antioxidant 1010 compounded according to a mass ratio of 2:1.

[0233] The lubricant is erucamide.

[0234] The masterbatch is black Cabot 6269.

[0235] The PP composite material can be prepared by the following method:

[0236] S1. Prepare a masterbatch from the modified inorganic filler, flame retardant, PP resin and toughening agent through a twin-screw extruder.

[0237] S2. Mix the remaining other materials and the masterbatch in a mixer at 200 rpm for 120 s.

[0238] S3. Use a twin-screw extruder to melt-blend and pelletize the materials in step S2 to obtain the PP composite material.

[0239] Among them, the screws in the twin-screw extruders in step S1 and step S3 are successively provided with kneading blocks, dispersion disks, tooth-shaped mixing elements and tooth-shaped disks along the axial direction. The length-diameter ratio of the screw is greater than or equal to 48:1; the number of kneading blocks is 5, the stagger angle of the kneading blocks is 45°, and the length of the kneading blocks is 56 mm; the dispersion disks include more than 2 places; the tooth-shaped dispersion elements include 2 groups.

[0240] Each material is fed from the main feeding loss weight scale of the twin-screw extruder and enters the first zone of the screw bore. The working conditions of the twin-screw extruder are: zone 1 180°C - 200°C; zone 2 200°C - 220°C; zone 3 200°C - 220°C; zone 4 200°C - 220°C; zone 5 190°C - 210°C; zone 6 190°C - 210°C; zone 7 190°C - 210°C; zone 8 180°C - 200°C; zone 9 180°C - 200°C; the head zone 200°C - 220°C. The main machine speed is 300 rpm, and the vacuum degree of the head vacuum chamber is less than -0.06 Mpa. The distance of the material strip passing through water is 4 m, and the frequency of the granulator is 1100 rpm.

[0241] (2) Film

[0242] The PP composite material particles are heated and melted (at 200 °C), then formed into a film through casting and stretching, and a film with a thickness of 0.5 mm is obtained after gradient cooling. During the casting and stretching process, the temperature of the casting rollers through which the heated and melted material passes is as follows: the temperature of the first casting roller is 120 °C, and the temperatures of the subsequent other casting rollers are at room temperature (25 °C); the gap between adjacent casting rollers is 0.5 mm, and the linear velocity (stretching rate) of each casting roller is 8 m / min.

[0243] Examples 2 to 5

[0244] Examples 2 to 5 respectively provide a PP composite material and also provide a film formed by casting and stretching of this PP composite material. Among them, the PP composite material includes components with the mass percentages shown in Table 3-1.

[0245] The specific types of each component selected, as well as the preparation method of the PP composite material, the film, and its preparation method, are the same as those in Example 1.

[0246] Example 6

[0247] The difference between this example and Example 1 lies in: different PP resins.

[0248] Specifically, in this example, the PP resin has a melt mass flow rate of 3.5 g / 10 min under the test conditions of 230 °C and 2.16 kg, and the product grade is Lotte Chemical H5300.

[0249] The specific types of other components selected, as well as the preparation method of the PP composite material, the film, and its preparation method, are the same as those in Example 1.

[0250] Example 7

[0251] This comparative example provides a PP composite material. The difference from Example 1 is that the PP resin is D60P (with a melt mass flow rate of about 0.3 g / 10 min at 230 °C and 2.16 kg).

[0252] The specific types of other components selected, as well as the preparation method of the PP composite material, the film, and its preparation method, are the same as those in Example 1.

[0253] Example 8

[0254] The difference between this example and Example 1 lies in: different particle size distributions of talc powder. Specifically, the first talc powder passing through a 1000-mesh sieve and the second talc powder passing through a 3000-mesh sieve are compounded in a mass ratio of 2:1.

[0255] The specific types of other components selected, as well as the preparation method of the PP composite material, the film, and its preparation method, are the same as those in Example 1.

[0256] Example 9

[0257] The difference between this example and Example 1 is that the nucleating agent is NX8000.

[0258] The specific types of other components selected, the preparation method of the PP composite material, the film and its preparation method are the same as those in Example 1.

[0259] Example 10

[0260] The difference between this example and Example 1 is that the flame retardant is different.

[0261] Specifically, the flame retardant used in this example includes a ternary flame retardant and does not contain the brominated flame retardant decabromodiphenylethane. The ternary flame retardant includes ammonium polyphosphate (APP), melamine cyanurate (MCA) and pentaerythritol with a mass ratio of 8:5:1.

[0262] Example 11

[0263] The difference between this example and Example 1 is that in the film preparation method, the gap of the casting roll is adjusted to 0.4 mm, and the stretching rate is reduced by 20%, that is, the stretching rate is 16 m / min, so that the film thickness is 0.4 mm.

[0264] Example 12

[0265] The difference between this example and Example 1 is that in the film preparation method, the gap of the casting roll is adjusted to 0.6 mm, and the stretching rate is increased by 20%, that is, the stretching rate is 24 m / min, so that the film thickness is 0.6 mm.

[0266] Comparative Example 1

[0267] This comparative example provides a PP composite material, including components with the mass percentages shown in Table 4-1 (and the mass parts of each component are given in Table 4-2 for easy operation). The difference between it and Example 1 is that it does not contain modified inorganic fillers.

[0268] Comparative Example 2

[0269] This comparative example provides a PP composite material, including components with the mass percentages shown in Table 4-1. The difference between it and Example 1 is that its inorganic filler (talc powder) is not modified with KH550.

[0270] Comparative Example 3

[0271] This comparative example provides a PP composite material, including components with the mass percentages shown in Table 4-1. The difference between it and Example 1 is that it does not contain a nucleating agent.

[0272] Comparative Example 4

[0273] This comparative example provides a PP composite material, including components with the mass percentages shown in Table 4-1. The difference from Example 1 is that it does not contain a compatibilizer.

[0274] Comparative Examples 5 to 11

[0275] This comparative example provides a PP composite material, including components with the mass percentages shown in Table 4-1. The difference from Example 1 is that the dosages of each component are adjusted.

[0276] Comparative Example 12

[0277] This comparative example provides a PP composite material, including components with the mass percentages shown in Table 4-1. The difference from Example 1 is that the PP resin is C30S (the melt mass flow rate at 230°C and 2.16 kg is about 6 g / 10 min).

[0278] Comparative Example 13

[0279] The difference between this example and Example 1 is that the flame retardants are different.

[0280] Specifically, the flame retardant used in this comparative example is tris(1,3-dichloropropyl) phosphate (TDCPP).

[0281] [Table 3-1]

[0282]

[0283] [Table 3-2]

[0284]

[0285] [Table 4-1]

[0286]

[0287] [Table 4-2]

[0288]

[0289] The performance of the films of each example and comparative example was tested, and the results are shown in the following tables.

[0290] [Table 5]

[0291]

[0292] [Table 6]

[0293]

[0294] [Table 7]

[0295]

[0296] [Table 8]

[0297]

[0298] [Table 9]

[0299]

[0300] [Table 10]

[0301]

[0302] The test results show that:

[0303] 1) In Table 5, in Examples 1 to 5, PP resin, modified inorganic filler, nucleating agent, compatibilizer, flame retardant, and other components are combined in a certain proportion to make a PP composite material. After the PP composite material is made into a 0.5-mm-thick film, the film has a flat appearance and high stiffness. The flat appearance and high stiffness are related to its low shrinkage rate and high flexural modulus; at the same time, the films of Examples 1 to 5 also have good flame retardant properties and can reach the VTM-0 level.

[0304] In contrast, in the PP composite material of Comparative Example 1, there is no modified inorganic filler, and in Comparative Example 2, the inorganic filler is not modified with a coupling agent. The corresponding film has wrinkles and collapses, particulate matter, poor flatness, reduced stiffness of the film, and reduced flexibility.

[0305] In the PP composite material of Comparative Example 3, there is no nucleating agent, and the corresponding film has an increased shrinkage rate and reduced flexibility, resulting in poor flatness and reduced stiffness of the film.

[0306] In the PP composite material of Comparative Example 4, there is no compatibilizer, and the corresponding film has wrinkles and collapses, particulate matter, poor flatness, and reduced stiffness.

[0307] In Comparative Examples 5 to 11, the components are combined in inappropriate proportions. For example, in Comparative Example 5, the flame retardant is too little, in Comparative Example 6, the PP resin is too much and the nucleating agent is too little, in Comparative Example 7, the modified inorganic filler is too little and the flame retardant is too much, in Comparative Example 8, the nucleating agent is too little, in Comparative Example 9, the compatibilizer is too little and the flame retardant is too much, in Comparative Example 10, the compatibilizer is too much, and in Comparative Example 11, the PP resin is too much, the modified inorganic filler is too little, and the compatibilizer is too little. The corresponding films have low flatness and reduced stiffness.

[0308] 2) In Table 6, for Examples 1 and 6 - 7, PP resins with a certain melt flow rate were used as the matrix resin, and films with low shrinkage rate and high flexural modulus could be obtained, resulting in films with a flat appearance, high stiffness, and excellent flame retardancy. In contrast, in Comparative Example 12, when a PP resin with too high a melt flow rate was used, the shrinkage rate of the film increased and the flexural modulus decreased, resulting in problems such as poor flatness and reduced stiffness.

[0309] 3) Table 7 shows that by using a ternary flame retardant or combining a ternary flame retardant with other flame retardants (such as brominated flame retardants), films with flatness and high stiffness can be prepared. If the flame retardant does not contain a ternary flame retardant, the film will have wrinkles and reduced stiffness, which may be related to the fact that the type of flame retardant affects the shrinkage rate of the material. With an inappropriate flame retardant, the shrinkage rate of the film increases, resulting in wrinkles in the film.

[0310] 4) Tables 8 - 10 show that the modified inorganic fillers of the PP composite material can include inorganic fillers with different particle sizes and are applicable to different β - crystal form nucleating agents. After combining PP resin, modified inorganic filler, nucleating agent, compatibilizer, flame retardant, and other components according to a certain mass fraction to form a PP composite material, it can be used to prepare films with a thickness of 0.4 - 0.6 mm or less than 1 mm. Even at a very low thickness, the film still has high stiffness and good flatness.

[0311] Therefore, by combining a PP resin with a certain melt index, modified inorganic filler, nucleating agent, compatibilizer, and ternary flame retardant, and other components in a certain proportion to form a PP composite material, this PP composite material can be used to prepare films with a very low thickness, and the films have high stiffness, a flat appearance, and at the same time have a low shrinkage rate, good flexibility, and flame retardancy.

[0312] [Plastic - suction parts]

[0313] The films of each example and comparative example were plastic - suction molded into plastic - suction parts, specifically the upper cover of the battery module. The specific plastic - suction method was: using a BKT - M type sealed full - automatic vacuum plastic - suction molding machine for plastic - suction, with the temperature set at 495 °C and the plastic - suction vacuum degree at - 0.09 Mpa.

[0314] The results showed that the upper covers of the battery modules corresponding to Examples 1 - 12 had a flat appearance and no wrinkling on the surface, and could be referred to Figure 2 ( Figure 2 in which, Figure a corresponds to Example 1 and Figure b corresponds to Example 11). In contrast, the upper covers of the battery modules corresponding to Comparative Examples 1 - 13 had an uneven appearance and wrinkling on the surface, and could be referred to Figure 3 ( Figure 3 in which, Figure a corresponds to Comparative Example 1 and Figure b corresponds to Comparative Example 2).

[0315] [Performance Test Method]

[0316] (1) Heat Shrinkage Rate

[0317] The heat shrinkage rate in the embodiments of the present application refers to the longitudinal shrinkage rate of the film, i.e., the stretching direction when the film is prepared.

[0318] Test the heat shrinkage rate of the film according to the method in ASTM D1204 standard. Cut the specimen size into 100mm×100mm size, keep it in an oven at 135℃ for 30 minutes, and measure the change of the longitudinal size after cooling.

[0319] Calculate the shrinkage rate according to the formula, and the result is the arithmetic mean of 3 specimens.

[0320] S=(L 0 —L) / L 0 ×100%;

[0321] S—Shrinkage rate, %;

[0322] L 0 —Length of the specimen before heating, in millimeters (mm);

[0323] L—Length of the specimen after heat shrinkage, in millimeters (mm).

[0324] (2) Stiffness

[0325] At room temperature (23±2℃), according to the stiffness test standard GB / T 22364-2018, use a stiffness tester to test the stiffness, the test angle is 90°, and the sample size is 38mm×70mm to obtain the 90° stiffness, with the unit of mN.

[0326] (3) Flexural Modulus

[0327] At room temperature (23±2℃), test according to the method in ASTM D882 / GBT 1040 standard, and the test speed is 50mm / min.

[0328] (4) Flame Retardant Performance

[0329] Test according to the method in UL94 standard, and the specimen size of the film material is 125mm×13mm.

[0330] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered within the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A polypropylene composite material, characterized in that: Calculated by mass percentage, it includes the following components: Polypropylene resin 45% to 63%; Modified inorganic filler 9% to 25%; Nucleating agent 0.45% to 1%; Compatibilizer 4% to 10%; Flame retardant 5% to 15%; The melt mass flow rate of the polypropylene resin under the test conditions of 230° C. and 2.16 kg is 0.2 g / 10 min to 5 g / 10 min; the modified inorganic filler includes an inorganic filler and a coupling agent bonded to the surface of the inorganic filler; and the flame retardant includes an intumescent flame retardant.

2. The polypropylene composite material according to claim 1, characterized in that: Calculated by mass percentage, it includes the following components: Polypropylene resin 49%~57%; Modified inorganic filler 14% to 25%; Nucleating agent 0.5% to 1%; Compatibilizer 5% to 8%; Flame retardant 9%~15%.

3. The polypropylene composite material according to claim 1 or 2, characterized in that: The melt mass flow rate of the polypropylene resin under the test conditions of 230° C. and 2.16 kg is 1 g / 10 min to 5 g / 10 min.

4. The polypropylene composite material according to any one of claims 1 to 3, characterized in that: The inorganic filler comprises a first inorganic filler and a second inorganic filler, wherein the first inorganic filler has a particle size passing through a sieve of less than 1000 meshes, and the second inorganic filler has a particle size passing through a sieve of more than 3000 meshes; Optionally, the first inorganic filler has a particle size passing through a 800-1000 mesh sieve, and the second inorganic filler has a particle size passing through a 3000-3500 mesh sieve.

5. The polypropylene composite material according to claim 4, characterized in that: The mass ratio of the first inorganic filler to the second inorganic filler is (0.5-3):1, and optionally (1-2):

1.

6. The polypropylene composite material according to any one of claims 1 to 5, characterized in that: In the modified inorganic filler, the mass of the coupling agent is 0.5% to 1.5% of the inorganic filler, and optionally 1% to 1.5%.

7. The polypropylene composite material according to any one of claims 1 to 6, characterized in that: The compatibilizer includes one or more of polyvinyl alcohol, maleic anhydride grafted polypropylene, acrylic acid grafted polypropylene, methacrylic acid grafted polypropylene, maleic anhydride grafted polyethylene, acrylic acid-butadiene copolymer, ethylene vinyl acetate, dodecyl sulfonate, dodecyl phosphate, octadecyl sulfonate, octadecyl phosphate, stearic acid, fatty acid, and organic silicone.

8. The polypropylene composite material according to any one of claims 1 to 7, characterized in that: The nucleating agent includes a β-crystal nucleating agent.

9. The polypropylene composite material according to any one of claims 1 to 8, characterized in that: The nucleating agent includes one or more of an amide nucleating agent and a rare earth nucleating agent.

10. The polypropylene composite material according to any one of claims 1 to 9, characterized in that: The intumescent flame retardant comprises an acid source, a gas source and a carbon source; the acid source comprises one or more of ammonium polyphosphate, aluminum tripolyphosphate, tris(2-chloropropyl) phosphate, triphenyl phosphate, dimethyl methylphosphonate, coated red phosphorus and boric acid; the gas source comprises one or more of melamine cyanurate, tris(2,3-dibromopropyl) isocyanurate, piperazine pyrophosphate, polyamide and dicyandiamide; the carbon source comprises one or more of polyol and phenolic resin.

11. The polypropylene composite material according to claim 10, characterized in that: The mass ratio of the acid source, the gas source and the carbon source is (6-10):(3-7):1, and optionally (7-9):(4-6):

1.

12. The polypropylene composite material according to any one of claims 1 to 11, characterized in that: The flame retardant further comprises a brominated flame retardant. Optionally, the brominated flame retardant comprises one or more of octabromoether, hexabromocyclododecane, decabromodiphenylethane, brominated polystyrene, polypentabromophenol acrylate, and tris(2,3-dibromopropyl)isocyanurate.

13. The polypropylene composite material according to claim 12, characterized in that: The mass ratio of the intumescent flame retardant to the brominated flame retardant is (5-10):1, and optionally (6-8):

1.

14. A film, characterized in that: The film comprises the polypropylene composite material according to any one of claims 1 to 13.

15. The film according to claim 14, characterized in that: The thickness of the film is ≤1 mm, and can be optionally 0.25 mm to 1 mm.

16. A blister, characterized in that: The blister comprises the film according to claim 14 or 15.

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