Environment-friendly color master batch based on natural material carrier

Abstract

The invention belongs to the technical field of fine chemical engineering and high polymer materials, and particularly relates to an environment-friendly color master batch based on a natural material carrier, the environment-friendly color master batch comprises the natural material carrier, a pigment, a compatibilizer, a stabilizer and a processing aid, and the natural material carrier is composed of hydrophobically modified cellulose and derivatives thereof and a second natural polymer base material. A natural polymer base material mainly comprising cellulose and derivatives thereof is adopted as a carrier, and the natural polymer base material is derived from renewable resources and has biodegradability. The carrier replaces a non-renewable synthetic polymer carrier in the traditional color master batch, so that the dependence on petrochemical resources is greatly reduced, the long-term pressure of plastic wastes on the environment is effectively relieved, and the carrier accords with the current global trend of green manufacturing and sustainable development.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fine chemical industry and polymer materials, and in particular to an environmentally friendly color master batch based on a natural material carrier. BACKGROUND

[0002] Color master batch is a key component in the field of plastic coloring. By pre-dispersing high-concentration pigments or dyes in carrier resin, it can effectively solve the problems of dust pollution, uneven dispersion and low coloring efficiency faced by traditional direct pigment addition, significantly improving the convenience, cleanliness and coloring accuracy of plastic processing. In modern industry, color stability and functional coloring in the fields of daily necessities, packaging materials, automobile parts and electronic products all rely on the application of high-performance color master batch.

[0003] Traditional color master batch technology uses synthetic polymers such as polyolefin, polystyrene and EVA as carrier resin. Such carriers have good compatibility with target colored plastic matrix, suitable melt flowability, and can well wet and disperse pigments; supplemented by wetting agents, dispersants, coupling agents and other additives, the pigments can be further optimized for depolymerization and stability, preventing agglomeration during processing, achieving rapid and uniform migration of pigments to the main plastic resin, and giving the plastic product stable and bright color. This technology has formed a mature production process and wide application basis, effectively meeting the market demand for color diversity and processing efficiency.

[0004] However, the synthetic polymer carrier of traditional color master batch relies on non-renewable petrochemical resources, and its waste is difficult to degrade, which is in conflict with environmental protection, sustainable development and low-carbon economic demand, prompting the industry to seek natural material carriers. Although natural high polymer materials such as cellulose and its derivatives have the advantages of being renewable, degradable and abundant in reserves, their direct application in color master batch carriers faces technical challenges: first, natural materials are mostly hydrophilic, with large polarity difference from hydrophobic pigments and general plastics, resulting in poor wettability, uneven dispersion, and affecting coloring performance and product quality; second, natural materials have low thermal stability and narrow processing temperature window, and are easily thermally degraded under high-temperature melt shear, affecting color stability and product performance; third, some natural materials are brittle, and color master batch is prone to dust during storage and transportation, which may affect the mechanical properties of the product.

[0005] Therefore, the present application provides an environmentally friendly color master batch based on a natural material carrier. SUMMARY

[0006] In order to make up for the deficiencies of the prior art and solve at least one technical problem raised in the background art.

[0007] The technical scheme adopted by the present application to solve its technical problems is: the environmentally friendly color master batch based on a natural material carrier according to the present application comprises the following components: a natural material carrier, pigments, a compatibilizer, a stabilizer and a processing aid.

[0008] The natural material carrier is composed of a first natural polymer base and a second natural polymer base. The first natural polymer base is cellulose and its derivatives, and the mass percentage of the first natural polymer base in the total color concentrate is in the range of 20% to 70%. The second natural polymer base is selected from starch and its derivatives, lignin and its derivatives, protein and its derivatives, natural resin, natural rubber, or a combination thereof, and the mass percentage of the second natural polymer base in the total color concentrate is in the range of 5% to 30%.

[0009] As a preferred embodiment of the present application, the first natural polymer base is selected from microcrystalline cellulose, powdered cellulose, cellulose acetate, cellulose propionate, cellulose butyrate, hydroxypropyl cellulose, hydroxyethyl cellulose, ethyl cellulose, or a combination thereof. The cellulose derivatives are subjected to hydrophobic modification treatment to improve their compatibility with pigments and hydrophobic host plastic resins. The hydrophobic modification treatment includes but is not limited to esterification, etherification, or graft copolymerization modification. In the esterification modification, the hydroxyl groups of cellulose react with fatty acid anhydride or fatty acid chloride to introduce alkyl or alkenyl ester groups with a carbon chain length of C2-C18; in the etherification modification, the hydroxyl groups of cellulose react with alkyl halide or alkylene oxide to introduce alkyl or hydroxyalkyl ether groups with a carbon chain length of C2-C18; in the graft copolymerization modification, polycaprolactone (PCL), polylactic acid (PLA), or long-chain olefin monomers are grafted onto the cellulose backbone. Through the hydrophobic modification, the water absorption of the cellulose and its derivatives is reduced, and the surface energy matches the hydrophobic pigments and plastic matrix, thereby significantly improving their dispersibility and compatibility.

[0010] Further, the second natural polymer base is selected from thermoplastic starch, acetylated starch, hydroxypropyl starch, oxidized starch, lignin sulfonate, alkylated lignin, casein, zein, soybean protein isolate, shellac, rosin, natural rubber, or a combination thereof. The second natural polymer base is used to adjust the melt flowability of the carrier system, improve the toughness of the carrier, or further optimize the hydrophobicity of the carrier. For example, when thermoplastic starch is used as the second natural polymer base, it forms a blending system with the first natural polymer base, to some extent, increasing the processing temperature window of the carrier and improving its flowability; when natural rubber is used, it can effectively increase the toughness of the carrier system, reduce the brittleness of the color concentrate, and reduce dust generation.

[0011] The pigment is selected from organic pigments, inorganic pigments, or a combination thereof. The mass percentage of the pigment in the total amount of the color masterbatch is in the range of 10% to 60%. The organic pigments include, but are not limited to, phthalocyanine pigments, azo pigments, quinacridone pigments, dioxazine pigments, isoindoline pigments, anthraquinone pigments, benzimidazolone pigments, or a combination thereof. The inorganic pigments include, but are not limited to, titanium dioxide, iron oxide, carbon black, ultramarine, chromium yellow, cadmium red, lead-chromium yellow, composite metal oxide pigments, or a combination thereof. To further improve the dispersibility and compatibility between the pigment and the natural material carrier, the surface of the pigment can be pre-modified. The surface modification treatment includes, but is not limited to, coating or grafting with fatty acids (such as stearic acid), fatty acid salts, silane coupling agents (such as γ-aminopropyl triethoxysilane), titanate coupling agents, or polymeric dispersants. The average particle size of the pigment is preferably controlled between 50 nanometers and 5 micrometers to ensure excellent tinting strength, hiding power, and color uniformity of the final product.

[0012] The compatibilizer is selected from maleic anhydride grafted polymers, epoxy group polymers, amphiphilic block copolymers, silane coupling agents, titanate coupling agents, or a combination thereof. The mass percentage of the compatibilizer in the total amount of the color masterbatch is in the range of 0.1% to 10%. The maleic anhydride grafted polymers include, but are not limited to, maleic anhydride grafted polylactic acid (MAH-g-PLA), maleic anhydride grafted polycaprolactone (MAH-g-PCL), maleic anhydride grafted polyethylene (MAH-g-PE), or maleic anhydride grafted polypropylene (MAH-g-PP). The epoxy group polymers include, but are not limited to, epoxy soybean oil, epoxy resins, or acrylate copolymers containing epoxy groups. The amphiphilic block copolymers include, but are not limited to, polylactic acid-polyethylene glycol block copolymers (PLA-PEG), polycaprolactone-polyethylene glycol block copolymers (PCL-PEG), or starch-g-polyethylene block copolymers. The compatibilizer reduces the interfacial tension by forming an interfacial layer or undergoing a chemical reaction between the natural material carrier and the pigment or between the natural material carrier and the host plastic resin, promotes uniform dispersion of the pigment in the carrier, and enhances the compatibility between the carrier and the host plastic resin, thereby effectively avoiding defects such as flow lines and color spots caused by polarity differences. For example, when using a maleic anhydride grafted polymer, the maleic anhydride groups can undergo esterification with the hydroxyl groups on the natural material carrier, while the polymer segments have good compatibility with the host plastic resin, thereby forming a chemical bridge and enhancing the interfacial bonding force.

[0013] The stabilizer is selected from the group consisting of an antioxidant, an ultraviolet absorber, a light stabilizer, a metal deactivator, or a combination thereof. The mass percentage of the stabilizer in the total amount of the color masterbatch is in the range of 0.05% to 5%. The antioxidant includes, but is not limited to, a hindered phenolic antioxidant such as pentaerythritol tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], a phosphite antioxidant such as tris(2,4-di-tert-butylphenyl) phosphite, or a thioester antioxidant. The ultraviolet absorber includes, but is not limited to, a benzotriazole such as 2-(2H-benzotriazol-2-yl)-4,6-di-tert-amylphenol, a triazine, or a benzophenone ultraviolet absorber. The light stabilizer includes, but is not limited to, a hindered amine light stabilizer (HALS) such as bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate. The stabilizer system is used to inhibit thermal degradation and oxidative degradation of the natural material carrier during high-temperature processing, and to prevent discoloration of the pigment under ultraviolet radiation, thereby ensuring the processing stability of the color masterbatch, the color stability of the final product, and the mechanical properties. For example, the hindered phenolic antioxidant, as a primary antioxidant, can capture free radicals and interrupt the oxidation chain reaction; the phosphite antioxidant, as a secondary antioxidant, can decompose hydroperoxides to prevent them from initiating new free radicals. The two types of antioxidants can be used in combination to achieve more excellent stabilizing effect.

[0014] The processing aid is selected from the group consisting of a plasticizer, a lubricant, a flow modifier, a release agent, or a combination thereof. The mass percentage of the processing aid in the total amount of the color masterbatch is in the range of 0.1% to 15%. The plasticizer includes, but is not limited to, a bio-based plasticizer such as citrate esters, glycerol esters, epoxy soybean oil, polyethylene glycol, phthalate esters (although environmentally friendly, the present application preferably uses bio-based plasticizers), or fatty acid esters. The lubricant includes, but is not limited to, a fatty acid amide such as erucamide, stearamide, a metal soap such as zinc stearate, calcium stearate, a paraffin wax, a polyethylene wax, or a natural wax. The flow modifier includes, but is not limited to, a modified rosin ester, a terpene resin, or a low-molecular-weight polylactic acid. The processing aid is used to improve the flowability of the natural material carrier in the molten state, reduce the melt viscosity, expand the processing temperature window, and reduce shear heat, thereby improving the production efficiency of the color masterbatch and reducing energy consumption. At the same time, the plasticizer can also increase the flexibility of the natural material carrier, reduce its brittleness, reduce the generation of dust during storage, transportation, and use, and improve the cleanliness of the operating environment. For example, the bio-based plasticizer can reduce the interaction force between the natural polymer chain segments, increase the free volume of the molecular chain, make the carrier material more easily flow and plasticize during processing, and at the same time impart better mechanical strength and toughness to the color masterbatch.

[0015] The present application also provides a method for preparing the above-mentioned environmentally friendly color masterbatch based on a natural material carrier, comprising the following steps:

[0016] Step one: pretreatment of the first natural polymer base, including drying and pulverizing to a powder with an average particle size of less than 100 microns;

[0017] Step two: drying and pulverizing the second natural polymer base to a powder with an average particle size of less than 150 microns;

[0018] Step three: high-speed mixing of the pretreated first natural polymer base, second natural polymer base, pigment, compatibilizer, stabilizer, and processing aid in a predetermined ratio to obtain a uniformly mixed premix;

[0019] Step four: melt blending and granulation of the premix through a twin-screw extruder to obtain the environmentally friendly color masterbatch.

[0020] Further, the first natural polymer base pretreatment in step one can also include hydrophobic modification treatment. The hydrophobic modification treatment can be performed independently before step one or in situ modification during the melt blending process in step four. When performed independently, it is obtained by reacting cellulose and its derivatives with a modifier in the presence of a specific solvent (such as dimethyl sulfoxide, N,N-dimethylformamide) and a catalyst (such as p-toluenesulfonic acid, zinc acetate) at a temperature range of 80°C to 150°C for 2 to 10 hours in a reaction kettle, followed by washing and drying.

[0021] Further, the high-speed mixing in step three can be performed in a high-speed mixer with a mixing speed of 500 to 1500 rpm and a mixing time of 5 to 20 minutes to ensure sufficient dispersion and uniform mixing of the components. The temperature during mixing is controlled at 20°C to 60°C to avoid degradation or caking of the components during the mixing stage.

[0022] Further, the twin-screw extruder in step four has a length to diameter ratio (L / D) of 28:1 to 48:1. The screw configuration of the extruder includes a conveying section, a plasticizing section, a mixing section, and a metering section, wherein the mixing section contains at least two sets of kneading blocks or dispersing elements to provide high shear force, ensuring the sufficient dispersion of pigments in the natural material carrier. The extrusion temperature is controlled between 140°C to 200°C, wherein each temperature zone is provided with a differentiated temperature gradient, ensuring that the natural material carrier does not undergo significant degradation in the molten state, while ensuring the sufficient dispersion of pigments and the effective reaction of compatibilizers. Specifically, the feeding section temperature is 140°C to 150°C, the compression section temperature is 150°C to 170°C, the melting section temperature is 160°C to 190°C, and the metering section temperature is 170°C to 200°C. The screw rotation speed is controlled between 100 rpm to 500 rpm to provide sufficient shear force while avoiding material degradation caused by excessive shear. The extruder die adopts a multi-hole plate design with a hole diameter of 2 mm to 5 mm. The molten extrudate is cooled to room temperature by water bath, and then cut into particles with a length of 2 mm to 5 mm by a granulator. The color masterbatch after cutting is vacuum dried at 60°C to 80°C for 4 to 8 hours to remove residual moisture, ensuring product quality.

[0023] The beneficial effects of the present application are as follows:

[0024] 1. The environmentally friendly color masterbatch based on a natural material carrier of the present application uses cellulose and its derivatives as the main natural polymer base material as the carrier, which is derived from renewable resources and has biodegradability. The carrier replaces the non-renewable synthetic polymer carrier in traditional color masterbatch, greatly reducing the dependence on petrochemical resources and effectively alleviating the long-term pressure of plastic waste on the environment, in line with the current global trend of green manufacturing and sustainable development.

[0025] 2. The environmentally friendly color masterbatch based on a natural material carrier of the present application significantly improves the wettability between the hydrophilic natural carrier (especially cellulose derivatives) and the hydrophobic pigment by hydrophobic modification of the natural material carrier and the introduction of amphiphilic compatibilizers with specific chemical structures, effectively reducing the surface energy of the pigment and promoting the fine dispersion of the pigment in the carrier melt. This effectively inhibits the agglomeration of pigments, ensuring uniform distribution of pigment particles, so that the color masterbatch of the present application has higher tinting strength, more excellent hiding power and more uniform color performance, avoiding color spots and flow lines in the final plastic products.

[0026] 3.The environmentally friendly color master batch based on natural material carrier according to the present application, by selecting cellulose derivatives with higher thermal stability and second natural polymer base materials, and synergistically using high-efficiency antioxidant and light stabilizer systems, the thermal degradation and oxidative degradation of the natural material carrier during high-temperature melt extrusion and subsequent plastic molding processes are effectively inhibited, thereby ensuring the processing stability of the color master batch and preventing problems such as color yellowing and molecular chain rupture. At the same time, the introduction of the compatibilizer constructs a good interface between the natural carrier and the hydrophobic main body plastic resin, greatly improving the compatibility of the color master batch and the main body plastic resin, ensuring the uniform migration and dispersion of the pigment in the main body plastic matrix, and improving the mechanical properties and appearance quality of the final product.

[0027] 4.The environmentally friendly color master batch based on natural material carrier according to the present application, by reasonably matching the second natural polymer base material and adding a bio-based plasticizer and other processing aids, the flexibility and toughness of the natural material carrier system are effectively improved, and the brittleness of the color master batch is significantly reduced. This makes the prepared color master batch not easy to break during storage, transportation and use, reduces the generation of dust, thereby improving the cleanliness of the production and operating environment, reducing the risk of inhaling dust for workers, and improving the safety of work.

[0028] 5.The environmentally friendly color master batch based on natural material carrier according to the present application, by providing a preparation method that uses mature double-screw extrusion technology, by optimizing process parameters such as screw configuration, temperature gradient, and screw speed, the natural material carrier, pigment, compatibilizer, and other components are fully mixed and efficiently dispersed. The process parameters are precisely controlled to ensure stable processing of the natural material carrier, avoid its degradation under high temperature and high shear conditions, and ensure consistency of production efficiency and product quality. The preparation method has good industrialization universality and is easy to mass-produce. BRIEF DESCRIPTION OF DRAWINGS

[0029] The present application will be further described below with reference to the accompanying drawings.

[0030] Figure 1 is a composition schematic diagram of the environmentally friendly color master batch of the present application;

[0031] Figure 2 is a process flow diagram for preparing the environmentally friendly color master batch of the present application;

[0032] Figure 3 is a schematic diagram of the interaction of the main components in the environmentally friendly color master batch of the present application. DETAILED DESCRIPTION

[0033] In order to make the technical means, creative features, purposes and effects realized by the present application easy to understand, the present application will be further described below with reference to the specific embodiments.

[0034] As shown in Figure 1 and Figure 3 , the application discloses an environmentally-friendly color master batch based on natural material carrier, which comprises a specific proportion of natural material carrier, selected pigments, high-efficiency compatilizer, composite stabilizer and optimized processing aid. The precise synergy of each component constitutes the basis of the excellent performance of the color master batch.

[0035] Specifically, the natural material carrier as the matrix of the color master batch is composed of a first natural polymer base and a second natural polymer base. The first natural polymer base, as the main part of the carrier system, is strictly controlled in the percentage content of 20% to 70% in the total mass of the color master batch. Preferably, the first natural polymer base is cellulose and its various derivatives, and the natural abundance of hydroxyl structure endows it with biodegradability and renewability. The second natural polymer base is set in the percentage content range of 5% to 30% in the total mass of the color master batch for the purpose of supplementing and adjusting the performance of the carrier. The second natural polymer base is preferably selected from starch and its derivatives, lignin and its derivatives, protein and its derivatives, natural resin, natural rubber or their various combinations according to the specific application requirements.

[0036] As a preferred embodiment of the present application, the first natural polymer base material can be selected from microcrystalline cellulose, powdered cellulose, cellulose acetate, cellulose propionate, cellulose butyrate, hydroxypropyl cellulose, hydroxyethyl cellulose, ethyl cellulose, or any combination thereof. To effectively improve the compatibility and dispersibility between the hydrophilic cellulose and its derivatives and the hydrophobic pigments and more hydrophobic host plastic resins, the present application performs a specific hydrophobic modification treatment on the cellulose derivatives. This modification is one of the key links of the breakthrough technical solution of the present application. The path of the hydrophobic modification treatment is diverse, mainly including but not limited to esterification modification, etherification modification, or graft copolymerization modification. In the esterification modification scheme, the free hydroxyl groups on the cellulose molecular chain are esterified with fatty acid anhydride (for example, acetic anhydride, propionic anhydride, stearic anhydride) or fatty acid chloride (for example, acetyl chloride, propionyl chloride, lauryl chloride), thereby successfully introducing alkyl or alkenyl ester groups with a carbon chain length in the range of C2 to C18. The introduction of these long-chain hydrophobic groups significantly reduces the polarity of the cellulose surface. In the etherification modification scheme, the hydroxyl groups of cellulose are reacted with alkyl halides (for example, chloroethane, bromopropane, bromooctadecane) or alkylene oxides (for example, ethylene oxide, propylene oxide), thereby introducing alkyl or hydroxyalkyl ether groups with a carbon chain length in the range of C2 to C18 on the cellulose backbone. Similar to esterification modification, the formation of ether bonds and the introduction of hydrophobic segments also effectively impart hydrophobicity to cellulose derivatives. More precise graft copolymerization modification schemes involve covalently grafting polymer segments with good biocompatibility and hydrophobicity, such as polycaprolactone (PCL), polylactic acid (PLA), or long-chain olefin monomers (for example, octadecene), onto the cellulose macromolecular backbone. Through the various hydrophobic modification treatments, the inherent water absorption of the cellulose and its derivatives can be significantly reduced, and the surface free energy can be effectively regulated, making it more compatible with the surface energy of hydrophobic pigments and host plastic matrices, thereby greatly improving the wettability, dispersion uniformity of pigments in the carrier, and macroscopic compatibility between the color master batch and the final plastic matrix at the molecular level. For example, when cellulose is esterified with stearic acid, its water contact angle can be increased from about 20° to more than 80°, and the surface energy can be reduced from about 45 mJ / m² to less than 30 mJ / m², thereby significantly enhancing the interfacial affinity with non-polar plastics such as polyethylene or polypropylene.

[0037] Further, the selection of the second natural polymer binder and its functional positioning are critical to the overall performance of the carrier system. The binder is preferably one or more selected from thermoplastic starch, acetylated starch, hydroxypropyl starch, oxidized starch, lignin sulfonate, alkylated lignin, casein, zein, soy protein isolate, shellac, rosin, natural rubber, or combinations thereof. The core role of the second natural polymer binder is to multi-dimensionally modulate the melt flow characteristics of the carrier system, to improve the macroscopic toughness of the carrier, or to further optimize the hydrophobicity of the carrier system to meet the requirements of different processing conditions and application scenarios. Specifically, when thermoplastic starch is used as the second natural polymer binder, it can form a well-compatible blend system with the first natural polymer binder (e.g., hydrophobically modified cellulose) after proper plasticization treatment. This blend system exhibits a wider processing temperature window in the molten state, which can typically reduce the overall system's melt onset temperature by 5°C to 10°C and significantly improve the melt flowability, making the color concentrate easier to plasticize during extrusion, with less shear heat generation, thereby reducing processing energy consumption and improving production efficiency. If natural rubber is selected as the second natural polymer binder, its inherent high elasticity and toughness can effectively enhance the mechanical properties of the carrier system, significantly reducing the brittleness of the color concentrate. This makes the prepared color concentrate less likely to break due to mechanical stress during storage, transportation, and subsequent feeding and use, thereby significantly reducing dust generation and improving the cleanliness and safety of the production and operating environment. For example, by introducing 10% to 20% of natural rubber into the carrier system, the color concentrate's falling weight impact strength can be increased by more than 20%, while the dust emission can be reduced by more than 30%.

[0038] The pigments are the core component that endow the color masterbatch with coloring function, and there are various types of pigments that can be flexibly selected according to the color requirements of the final product and the application environment, including but not limited to organic pigments, inorganic pigments, or any combination thereof. The percentage content of pigments in the total mass of the color masterbatch is set to be in the range of 10% to 60% to meet the requirements of different coloring depth and hiding power. The organic pigments are various, such as phthalocyanine pigments (such as phthalocyanine blue, phthalocyanine green), azo pigments (such as azo yellow, azo red), quinacridone pigments, dioxazine pigments, isoindoline pigments, anthraquinone pigments, benzimidazolone pigments, or combinations thereof, which usually have high coloring strength and bright color. The inorganic pigments are known for their excellent weather resistance, heat resistance and hiding power, such as titanium dioxide (rutile or anatase), iron oxide (red, yellow, black), carbon black, ultramarine, chromium yellow, cadmium red, lead-chromium yellow, composite metal oxide pigments, or combinations thereof. In order to further improve the dispersibility and compatibility between the pigments and the natural material carrier, the present application particularly focuses on the surface modification treatment of the pigments. The surface modification treatment can be completed at the pigment manufacturing stage, or pretreated before the preparation of the color masterbatch. Specific modification methods include but are not limited to physical coating or chemical grafting using fatty acids (such as stearic acid, oleic acid), fatty acid salts (such as calcium stearate, zinc stearate), silane coupling agents (such as γ-aminopropyl triethoxysilane, γ-methacryloyloxypropyl trimethoxysilane), titanate coupling agents, or polymeric dispersants (such as polyethylene glycol derivatives, polyacrylate). For example, by coating stearic acid on the surface of the pigment, the surface can be changed from hydrophilic to hydrophobic, so that it is more easily wetted and dispersed by the non-polar natural material carrier melt. The average particle size of the pigments is preferably controlled in the range of 50 nanometers to 5 microns. Controlling the particle size of the pigments in this range can ensure that the pigments have a high enough specific surface area in the carrier to provide excellent coloring power and hiding power, and on the other hand, avoid the dispersion problems caused by the agglomeration of nano-sized pigments, thereby ensuring that the final colored product has excellent color uniformity and appearance quality without color spots and flow lines. For example, when using rutile titanium dioxide with an average particle size of 200 nanometers for coloring, its dispersion index (DI) in a polylactic acid matrix can reach more than 9.5 (DI full score is 10), while the DI of traditional unmodified pigments is usually less than 7.0.

[0039] The compatibilizer is an indispensable component in the color masterbatch system of the present application, and its core function is to build an effective interface connection between the natural material carrier and the pigment, as well as between the color masterbatch and the main plastic resin, thereby bridging the inherent polarity difference between them, reducing the interfacial tension, promoting the uniform dispersion of the pigment, and significantly enhancing the compatibility of the color masterbatch in the main plastic matrix. The percentage content of the compatibilizer in the total mass of the color masterbatch ranges from 0.1% to 10%, which is sufficient to play its bridging role without excessively affecting the overall performance of the system. The preferred compatibilizer is selected from maleic anhydride grafted polymers, epoxy group polymers, amphiphilic block copolymers, silane coupling agents, titanate coupling agents, or any combination thereof. The maleic anhydride grafted polymers are an important class of reactive compatibilizers, including but not limited to maleic anhydride grafted polylactic acid (MAH-g-PLA), maleic anhydride grafted polycaprolactone (MAH-g-PCL), maleic anhydride grafted polyethylene (MAH-g-PE), or maleic anhydride grafted polypropylene (MAH-g-PP). Its mechanism of action is that the maleic anhydride groups can undergo esterification with the hydroxyl groups on the natural material carrier (such as cellulose derivatives), forming covalent bonds, while its polymer backbone segment has good compatibility with the main plastic resin (such as PLA, PE, PP), thereby forming a "chemical bridge" at the interface, greatly enhancing the interfacial bonding force. The epoxy group polymers, such as epoxy soybean oil, epoxy resin, or acrylate copolymer containing epoxy groups, can also react with the hydroxyl groups on the natural material carrier or the active hydrogen on the pigment surface, achieving interface coupling. The amphiphilic block copolymer, such as polylactic acid-polyethylene glycol block copolymer (PLA-PEG), polycaprolactone-polyethylene glycol block copolymer (PCL-PEG), or starch-g-polyethylene block copolymer, contains both hydrophilic and hydrophobic segments in its molecular structure. The hydrophilic segment can anchor on the surface of the natural material carrier or interact with the pigment surface, while the hydrophobic segment extends into the hydrophobic main plastic resin, effectively reducing the interfacial tension, stabilizing the pigment dispersion, and promoting the mutual penetration and adhesion between different phases. For example, in a system containing a hydrophobically modified cellulose carrier and a polypropylene (PP) main resin, the addition of 3% MAH-g-PP as a compatibilizer can increase the impact strength of the final composite material by 15% to 25%, while significantly reducing the flow lines and color spots defects commonly seen in colored products.

[0040] The stabilizers are the key components to ensure the performance stability of the color masterbatch of the present application during processing, storage and use of the final products, which are designed to inhibit thermal and oxidative degradation of the natural material carrier during high temperature processing, and photo-oxidative discoloration of the pigments under UV irradiation, thus ensuring the processing stability of the color masterbatch, the color stability of the final products and the long-term mechanical properties. The percentage content of the stabilizers in the total mass of the color masterbatch ranges from 0.05% to 5%. The stabilizer system is usually a combination of multiple stabilizers to produce a synergistic effect. For example, the antioxidants can effectively capture free radicals, interrupt the oxidative chain reaction, and decompose hydroperoxides. Specific antioxidants include, but are not limited to, hindered phenolic antioxidants such as pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], commonly known as antioxidant 1010, phosphite antioxidants such as tris(2,4-di-tert-butylphenyl) phosphite, commonly known as antioxidant 168, or thioester antioxidants (such as dilauryl thiodipropionate). Hindered phenolic antioxidants, as primary antioxidants, mainly terminate chain reactions by scavenging peroxy radicals; phosphite antioxidants, as secondary antioxidants, prevent further decomposition of active radicals by decomposing hydroperoxides. The synergistic use of both can significantly improve the antioxidant effect. The ultraviolet absorber can absorb high-energy ultraviolet light and convert it into harmless heat energy, thereby protecting the pigments and polymer matrix from photodegradation. Common ultraviolet absorbers include benzotriazole such as 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol, triazine or benzophenone ultraviolet absorbers. Light stabilizers such as hindered amine light stabilizers (HALS), such as bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, inhibit the photo-oxidative degradation of polymers by capturing free radicals and decomposing hydroperoxides. In addition, metal deactivators can also be added as needed to prevent oxidation reactions catalyzed by metal ions. For example, in a color masterbatch system containing hydrophobically modified cellulose and organic red pigments, the addition of 0.3% antioxidant 1010 and 0.2% ultraviolet absorber (UV-326) simultaneously can make the melt flow rate change of the color masterbatch less than 10% after 4 times of continuous extrusion at 180°C, and the color change ΔE value of the product colored with the color masterbatch after accelerated aging test (xenon lamp irradiation for 500 hours) is less than 1.5, while the ΔE value of the comparative example without stabilizer is usually more than 5.0.

[0041] The processing aids are designed to optimize the rheological behavior and mechanical properties of the color masterbatch during production and application, improve production efficiency, and improve the operating environment. The percentage content of the processing aids in the total mass of the color masterbatch ranges from 0.1% to 15%, so as to function while avoiding negative effects on the coloring ability of the color masterbatch and the performance of the final product. The processing aids can be selected from plasticizers, lubricants, flow modifiers, release agents, or various combinations thereof. The plasticizers are essential for reducing the glass transition temperature and melt viscosity of the natural material carrier system, and increasing its flexibility. The present application preferably uses bio-based plasticizers to further enhance the environmental properties of the product, such as citrate esters (such as tributyl citrate), glycerol esters, epoxy soybean oil, polyethylene glycol, or fatty acid esters (such as dioctyl phthalate, although still used, the present application tends to replace it). These plasticizers increase the free volume and activity of the molecular chains by weakening the intermolecular forces between the natural polymer segments, making the carrier material more easily flow and plasticize during processing. At the same time, the introduction of plasticizers can significantly increase the flexibility and elasticity of the natural material carrier, reducing its inherent brittleness, thereby reducing the dust generated by the color masterbatch during crushing, transportation, and feeding, improving the cleanliness and safety of the operating environment. For example, the addition of 5% epoxy soybean oil to the carrier system can reduce the brittleness index of the color masterbatch by more than 40%. The lubricants can effectively reduce the friction between the melt and the metal surface of the equipment, reduce shear heat, and prevent melt adhesion. The lubricants include but are not limited to fatty acid amides (such as erucic acid amide, stearic acid amide), metal soaps (such as zinc stearate, calcium stearate), paraffin wax, polyethylene wax, or natural wax. The flow modifier, such as modified rosin ester, terpene resin, or low molecular weight polylactic acid, can further optimize the rheological properties of the carrier melt, reduce the melt viscosity, and expand the processing temperature window, making the color masterbatch more easily dispersed into the main plastic resin. The release agent helps the color masterbatch to smoothly separate from the die after extrusion, and reduces the sticking during the pelletizing process.

[0042] As Figure 2 The present application also provides a method for preparing the above-mentioned environmentally friendly color masterbatch based on a natural material carrier, which ensures uniform dispersion of the components and stable processing of the carrier through precise process control, thereby giving the color masterbatch excellent performance. The method includes the following key steps:

[0043] Step one: pretreatment of the first natural polymer base, which first includes drying it thoroughly to remove adsorbed and bound water, such as drying in a vacuum oven at 80°C to 100°C for 4 to 8 hours, ensuring that the water content is less than 0.5%. Subsequently, it is pulverized into a uniform powder with an average particle size of less than 100 microns, such as by a supermicro pulverizer or an air jet mill, to improve its dispersibility and reactivity during subsequent mixing and melt blending.

[0044] Step two: Pretreatment of the second natural polymer base. Similar to the first natural polymer base, this step also includes sufficient drying, for example, drying in a vacuum oven at 70°C to 90°C for 3 hours to 6 hours, to ensure that the water content is less than 1.0%. Then, it is crushed into a uniform powder with an average particle size of less than 150 microns to ensure its good dispersion in the blending system and full mutual compatibility with the first natural polymer base.

[0045] Step three: Accurately weigh the pretreated first natural polymer base, second natural polymer base, pigment, compatibilizer, stabilizer, and processing aid according to the preset mass percentage, and then put them all into a high-speed mixer for thorough mixing. The purpose of high-speed mixing is to achieve a highly uniform physical mixing state of all solid powder components on a macroscopic scale, providing uniform feed for subsequent melt blending. The high-speed mixing can be carried out in a vertical high-speed mixer equipped with a heating / cooling jacket, and the mixing speed is preferably controlled between 500 rpm and 1500 rpm to provide sufficient shear force to promote powder dispersion. The mixing time is usually set to 5 minutes to 20 minutes to ensure that the components are fully dispersed and uniformly mixed. During the mixing process, the temperature in the mixing chamber needs to be accurately controlled at 20°C to 60°C, controlled by external cooling or internal heat dissipation, to avoid degradation, oxidation, or caking of the components due to local overheating during the mixing stage, especially for heat-sensitive natural materials.

[0046] Step four: The uniformly premixed material from the high-speed mixing is subjected to melt blending and granulation through a twin-screw extruder, so that the components are fully sheared, mixed, and dispersed in a molten state, and finally the environmentally friendly color masterbatch is obtained.

[0047] Further, the pretreatment of the first natural polymer base in step one can also include a hydrophobic modification process as needed. The implementation of the hydrophobic modification process can have two main approaches: one is to independently modify the cellulose and its derivatives offline before step one; the other is to achieve in-situ modification during the melt blending process in step four. When choosing to independently modify offline, the specific process is as follows: dissolve or disperse the cellulose and its derivatives with selected modifiers (such as acetic anhydride, lauroyl chloride or polycaprolactone monomer) in a specific solvent such as dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and add an appropriate amount of catalyst (such as p-toluenesulfonic acid, zinc acetate, triethylamine). Subsequently, the reaction system is reacted at a precisely controlled temperature range (usually 80°C to 150°C), and the reaction time can be set to 2 to 10 hours according to the modification degree requirement. After the reaction is completed, the unreacted modifier, solvent and catalyst are removed by centrifugation, washing (for example, repeatedly washed with ethanol or acetone), and finally dried to obtain the modified hydrophobic cellulose derivative. When choosing in-situ modification, the modifier can be added to the high-speed mixer together with other components in step three, and in the extruder in step four, high temperature and high shear conditions are used to promote the reaction between the modifier and the cellulose derivative, thereby achieving integrated modification and blending.

[0048] Further, the high-speed mixing process in step three, if a vertical high-speed mixer is used, its design usually includes a high-speed stirring paddle installed at the bottom and a side wall guide plate to form strong vortex in a short time, so that the powder particles in the mixing cavity are subjected to intense friction, collision and diffusion, thereby achieving uniformity of micro-level mixing. For example, when mixing 50 kg of pre-mixed material, a stirring paddle with a diameter of 0.5 meters is used at a speed of 1000 revolutions per minute for 10 minutes to ensure that the mixing uniformity reaches more than 99%, avoiding the phenomenon of local excess or deficiency in the subsequent extrusion process.

[0049] Further, the twin-screw extruder in Step 4 is the core equipment to achieve melt blending and granulation. The extruder has a specific length-to-diameter ratio (L / D), preferably in the range of 28:1 to 48:1. A longer L / D ratio ensures that the material stays in the barrel for a sufficient time to achieve full melting, mixing, and dispersion. The screw configuration of the extruder is carefully designed, typically including conveying, plasticizing, mixing, and metering sections. Among them, the mixing section is the key area to achieve fine dispersion of pigments, and its configuration includes at least two groups of kneading blocks or dispersing elements (such as offset kneading discs, dispersing toothed discs, or reverse screw elements), which can provide extremely high shear force to effectively shear, break, and peel the pigment agglomerates, ensuring the full dispersion of pigment particles in the natural material carrier melt, avoiding agglomeration and re-agglomeration. The extrusion temperature is controlled between 140°C and 200°C, and each temperature zone is set with a differentiated temperature gradient to adapt to the heat sensitivity of the natural material carrier and ensure the full dispersion of the pigment and the effective reaction of the compatibilizer. Specifically, the feeding section (first and second temperature zones) is usually set to 140°C to 150°C, aiming to preheat and convey the material; the compression section (third and fourth temperature zones) is set to 150°C to 170°C, starting to plasticize and compress the material; the melting section (fifth and sixth temperature zones) is set to 160°C to 190°C, which is the key area for the complete melting of the natural material carrier and the dispersion of the pigment, and sufficient energy is required to melt the material and achieve good fluidity; the metering section (seventh and eighth temperature zones) is set to 170°C to 200°C, used to homogenize the melt temperature and pressure, and ensure the melt passes through the die. The control of screw speed is also important to provide sufficient shear force and avoid material degradation, with a preferred range of 100 rpm to 500 rpm. Lower speed can be used for processing shear-sensitive materials, while higher speed can provide stronger dispersion capacity, which needs to be optimized according to specific formulations and material properties. The extruder die adopts a multi-hole plate design with a hole diameter of 2 mm to 5 mm to form uniform extrusion strands. The molten extrudate is immediately cooled to room temperature by water bath after extruding from the die, with the water bath temperature usually controlled at 20°C to 30°C to achieve rapid solidification. Subsequently, the cooled strands are cut into cylindrical or oval particles with a length of 2 mm to 5 mm by a granulator to form the final color masterbatch product. The cut color masterbatch is vacuum dried at a temperature of 60°C to 80°C for 4 to 8 hours to completely remove residual moisture, ensuring excellent storage stability and processing performance of the product, avoiding bubbles or degradation caused by moisture in subsequent applications.

[0050] Example 1: Preparation and performance of hydrophobically modified cellulose-based environmentally friendly green color masterbatch

[0051] This example aims to prepare an environmentally friendly green color masterbatch with hydrophobically modified microcrystalline cellulose as the main carrier and test its key performance.

[0052] Raw material preparation:

[0053] First natural polymer base material (A1): microcrystalline cellulose with an average particle size of 50 microns, purchased from Sigma-Aldrich. Hydrophobically modified pretreatment was performed: 200g of microcrystalline cellulose was dispersed in 1L of dimethyl sulfoxide, 50g of lauroyl chloride and 2g of zinc acetate were added as catalyst, and the reaction was carried out at 120°C for 8 hours under nitrogen protection. After the reaction was completed, it was washed repeatedly with ethanol, centrifuged and vacuum dried to constant weight. The water contact angle of the modified microcrystalline cellulose was 92°.

[0054] Second natural polymer base material (A2): thermoplastic starch with an average particle size of 80 microns, purchased from a starch factory in Henan.

[0055] Pigment (B): phthalocyanine green G (C.I. Pigment Green 7) with an average particle size of 0.5 microns, the surface was pre-coated with stearic acid, purchased from BASF.

[0056] Compatibilizer (C): maleic anhydride grafted polylactic acid (MAH-g-PLA) with a maleic anhydride content of 1.5wt%, a molecular weight of 20,000, purchased from NatureWorks.

[0057] Stabilizer (D): a composite antioxidant system containing 0.2wt% of pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 0.1wt% of tris(2,4-di-tert-butylphenyl) phosphite, purchased from BASF.

[0058] Processing aid (E): bio-based plasticizer epoxy soybean oil (ESBO), purchased from Evonik. Lubricant stearic acid amide, purchased from Huntsman.

[0059] Formulation ratio (mass percentage):

[0060] Hydrophobically modified microcrystalline cellulose (A1): 45%

[0061] Thermoplastic starch (A2): 15%

[0062] Phthalocyanine green G (B): 30%

[0063] MAH-g-PLA (C): 4%

[0064] Composite antioxidant (D): 0.3%

[0065] Epoxy soybean oil (E1): 5%

[0066] Stearic acid amide (E2): 0.7%

[0067] Preparation method:

[0068] Pre-treatment: The modified microcrystalline cellulose and thermoplastic starch were dried separately in a vacuum oven at 80 °C for 4 hours to ensure the moisture content was below 0.5%.

[0069] High-speed mixing: All components were accurately weighed according to the above formulation. All components were put into a vertical high-speed mixer. The mixing speed was set at 1200 rpm, and the mixing time was 15 minutes. The temperature was controlled at 35 °C ± 5 °C by external water-cooled jacket to avoid overheating of the material during mixing.

[0070] Melt blending and granulation: The uniformly mixed premix was continuously fed into a twin-screw extruder (L / D = 40:1, screw diameter 35 mm). The screw configuration of the extruder included three groups of kneading blocks to provide high shear dispersion capacity. The nine temperature zones of the extruder were set as follows:

[0071] Feeding zone (1-2 zone): 145 °C

[0072] Compression zone (3-4 zone): 160 °C

[0073] Melting zone (5-7 zone): 180 °C

[0074] Metering zone (8-9 zone): 190 °C The screw rotation speed was set at 300 rpm. The die used a multi-hole plate with a hole diameter of 3 mm. The extrudate was cooled by a 25 °C water bath, and then cut into 3 mm long granules by a granulator.

[0075] Post-treatment: The color masterbatch after granulation was dried in a vacuum oven at 70 °C for 6 hours to remove residual moisture, with a moisture content below 0.1%.

[0076] Performance testing: The green color masterbatch prepared was blended with polylactic acid (PLA) resin at an addition amount of 3%, and injection molded into standard test samples to test the following properties:

[0077] Color strength and color difference (ΔE): According to ASTM D2244 standard, compared with standard color cards, measured by X-Rite Ci7800 spectrophotometer.

[0078] Pigment dispersibility (DI): The cross-section of the injection molded part was observed by optical microscope to evaluate the degree of pigment agglomeration, using a 1-10 level evaluation system (10 being the best dispersion).

[0079] Thermal stability (MFR change rate): The melt flow rate (MFR) was measured according to the standard of ASTM D1238 at 190°C / 2.16kg. After the color concentrate was repeatedly processed in the extruder for three times, the MFR was measured again, and the MFR change rate was calculated.

[0080] Tensile strength: tested according to the standard of ASTM D638 using a universal testing machine.

[0081] Brittleness index: evaluated by the broken rate of particles after the falling weight impact test (ASTM D5420), the lower the percentage of broken particles, the lower the brittleness index.

[0082] Comparative Example 1: Preparation and performance of traditional synthetic polymer carrier green color concentrate

[0083] This comparative example aims to prepare a green color concentrate with traditional polyethylene (PE) as the carrier, and compare it with Example 1.

[0084] Raw material preparation:

[0085] Carrier base (A): low density polyethylene (LDPE), melt index 5g / 10min (190°C / 2.16kg), purchased from Yanshan Petrochemical.

[0086] Pigment (B): phthalocyanine green G (C.I. Pigment Green 7), average particle size 0.5 microns, no surface modification treatment, purchased from BASF.

[0087] Dispersant (C): polyethylene wax.

[0088] Stabilizer (D): composite antioxidant system, containing 0.2wt% pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0089] Processing aid (E): stearic acid.

[0090] Formulation ratio (mass percentage):

[0091] LDPE carrier (A): 60%

[0092] Phthalocyanine green G (B): 35%

[0093] Polyethylene wax (C): 3%

[0094] Composite antioxidant (D): 0.2%

[0095] Stearic acid (E): 1.8%

[0096] Preparation method:

[0097] Pre-treatment: LDPE does not need to be dried. Pigment, dispersant, stabilizer, processing aid are used directly.

[0098] High speed mixing: All components are weighed accurately according to the above formulation. All components are put into a vertical high speed mixer. The mixing speed is set at 1000 rpm and the mixing time is 10 minutes. The temperature is controlled at 30°C ± 5°C by external water cooling jacket during the mixing process.

[0099] Melt blending and pelletizing: The well-mixed pre-mix is continuously fed into a twin-screw extruder (L / D = 40:1) which is the same as that used in Example 1. The temperature zones of the extruder are set as follows:

[0100] Feed zone (1-2 zone): 150°C

[0101] Compression zone (3-4 zone): 165°C

[0102] Melt zone (5-7 zone): 180°C

[0103] Metering zone (8-9 zone): 185°C The screw speed is set at 250 rpm. The die is a multi-hole plate with a hole diameter of 3 mm. The extrudate is cooled by a 25°C water bath and then cut into 3 mm long pellets by a pelletizer.

[0104] Post-treatment: The color masterbatch after pelletizing does not need special drying and can be packed directly.

[0105] Performance test: The green color masterbatch prepared is blended with LDPE resin at an addition amount of 3%, and a standard test sample is injection molded to test the same performance indicators as Example 1.

[0106] Comparative result analysis:

[0107] The following Table 1 details the comparative data of the key performance indicators of the environmentally friendly green color masterbatch prepared in Example 1 of the present application and the traditional synthetic polymer carrier green color masterbatch of Comparative Example 1.

[0108] Table 1: Performance comparison of environmentally friendly color masterbatch and traditional color masterbatch

[0109] Performance indicators Test methods Example 1 (Invention) Comparative Example 1 (Traditional PE-based) Evaluation criteria and explanations Color strength (ΔΕ) ASTM D2244 0.8 2.5 The lower the ΔE value, the stronger the color strength, the closer to the standard color. Pigment dispersibility (DI) Optical microscope score 9.2 6.5 DI value 1-10, 10 is the best. Reflects the uniformity of pigments in the carrier and matrix. Thermal stability (MFR change rate) ASTM D1238 8% 25% The lower the MFR change rate, the less thermal degradation of the material in repeated processing, the higher the stability. Tensile strength (MPa) ASTM D638 58.5 22.1 Reflects the mechanical properties of the final composite material. Brittleness index (%) Breaking rate after falling weight impact 5% 20% The lower the breaking rate, the better the toughness of the color masterbatch, the less dust generated. Biodegradability (%) ISO 14855-1 (90 days) >90 <5 Measures the degree of biodegradation of the material in a specific environment. Environmental friendliness Qualitative evaluation Excellent General Based on the source of the carrier material and biodegradability.

[0110] From the comparative data in Table 1, it can be clearly observed that the environmentally friendly green color masterbatch based on the hydrophobically modified natural material carrier prepared in Example 1 of the present application is significantly superior to the traditional LDPE carrier-based Comparative Example 1 in various key performance indicators. Specifically, in terms of tinting strength, the ΔE value of Example 1 is 0.8, which is much lower than that of Comparative Example 1, which is 2.5. This indicates that the color masterbatch of the present application has higher coloring efficiency and more accurate color reproduction capability, and can achieve more saturated color effect under the same addition amount, or achieve the same coloring depth with lower addition amount. Pigment dispersibility is a key indicator that determines the appearance quality of the final product. The pigment dispersibility index (DI) of Example 1 is as high as 9.2, compared with 6.5 of Comparative Example 1. This reflects that the present application overcomes the compatibility problem between the natural material carrier and the pigment through the synergistic effect of the hydrophobically modified carrier and the compatibilizer, and realizes the fine and uniform dispersion of the pigment in the carrier and the final plastic matrix, greatly reducing the generation of defects such as color spots and flow lines.

[0111] In terms of thermal stability, the MFR change rate of Example 1 is only 8%, while that of Comparative Example 1 is as high as 25%. This indicates that the natural material carrier of the present application, after being optimized by specific components (such as selecting cellulose derivatives with higher thermal stability and a second natural polymer base) and being effectively protected by a composite stabilizer, its thermal degradation and oxidative degradation are significantly inhibited during high-temperature melt extrusion and repeated processing. This excellent processing stability ensures that the color masterbatch does not easily cause color yellowing or mechanical property degradation in actual production applications. Tensile strength is a key indicator for measuring the mechanical properties of the final plastic product. The tensile strength of the PLA product colored by Example 1 is 58.5 MPa, while the tensile strength of the LDPE product colored by Comparative Example 1 is 22.1 MPa. Although the matrix resins are different, the compatibilizer of Example 1 makes the interface bonding force between the color masterbatch and the biodegradable resin stronger, thereby better maintaining the mechanical properties of the matrix material, and even in some cases can be enhanced. The comparison of the brittleness index is also significant, with the breakage rate of Example 1 being only 5%, while that of Comparative Example 1 being 20%. This fully proves that by reasonably matching the second natural polymer base and adding biobased plasticizers and other processing aids, the natural material carrier is effectively improved in flexibility and toughness, greatly reducing the brittleness of the color masterbatch, thereby significantly reducing the generation of dust during storage, transportation and use, and improving the cleanliness and safety of the production and operation environment.

[0112] Most importantly, the natural material carrier used in Example 1 of the present application has excellent biodegradability, with a biodegradation rate of more than 90% in 90 days, while the traditional LDPE carrier hardly degrades under the same conditions. This directly reflects the fundamental breakthrough of the present application in environmental friendliness, which conforms to the current global green development and sustainable utilization trend.

[0113] In summary, the environmentally friendly color master batch based on natural material carrier proposed in the present application successfully overcomes various technical challenges faced by natural materials as carriers by fine hydrophobic modification of the natural material carrier, introduction of high-efficiency compatibilizers, stabilizers and processing aids, and combination with an optimized preparation process, and achieves comprehensive performance improvement in terms of coloring performance, dispersibility, processing stability, mechanical properties and environmental friendliness, providing an innovative solution with broad application prospects for the field of plastic coloring. Based on the above disclosure, those skilled in the art can make various modifications and variations to the present application in combination with their own experience and existing technology, and these modifications and variations all fall within the protection scope of the claims of the present application. For example, without departing from the spirit and scope of the present application, the specific types or proportions of the components can be changed, and the process parameters such as pretreatment, mixing or extrusion can be adjusted to adapt to different target plastic matrices or performance requirements of the final product. The protection scope of the present application is not limited to the details described in the above specific embodiments, but should be defined by the scope of the claims.

[0114] The basic principles, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The protection scope of the present application is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly color masterbatch based on a natural material carrier, characterized in that, Includes the following components: The natural material carrier is composed of a first natural polymer matrix and a second natural polymer matrix; the first natural polymer matrix is ​​cellulose and its derivatives, accounting for 20% to 70% by mass of the total amount of the masterbatch; the second natural polymer matrix is ​​selected from starch and its derivatives, lignin and its derivatives, protein and its derivatives, natural resin, natural rubber, or a combination thereof, accounting for 5% to 30% by mass of the total amount of the masterbatch. The pigment comprises 10% to 60% by mass of the total amount of the masterbatch; The compatibilizer comprises 0.1% to 10% by mass of the total amount of the masterbatch; The stabilizer comprises 0.05% to 5% by mass of the total amount of the masterbatch; The processing aids comprise 0.1% to 15% by mass of the total amount of the masterbatch.

2. The environmentally friendly color masterbatch based on a natural material carrier according to claim 1, characterized in that, The first natural polymer matrix is ​​selected from microcrystalline cellulose, powdered cellulose, cellulose acetate, cellulose propionate, cellulose butyrate, hydroxypropyl cellulose, hydroxyethyl cellulose, ethyl cellulose or a combination thereof; the cellulose derivative is subjected to hydrophobic modification treatment, the hydrophobic modification treatment including esterification modification, etherification modification or graft copolymerization modification.

3. The environmentally friendly color masterbatch based on a natural material carrier according to claim 2, characterized in that, In the esterification modification, the hydroxyl groups of cellulose react with fatty acid anhydrides or fatty acid chlorides to introduce alkyl or alkenyl ester groups with a carbon chain length of C2-C18. In the etherification modification, the hydroxyl groups of cellulose react with alkyl halides or epoxy alkane to introduce alkyl or hydroxyalkyl ether groups with a carbon chain length of C2-C18. In the graft copolymerization modification, polycaprolactone, polylactic acid, or long-chain olefin monomers are grafted onto the cellulose backbone.

4. The environmentally friendly color masterbatch based on a natural material carrier according to claim 1, characterized in that, The second natural polymer base material is selected from thermoplastic starch, acetylated starch, hydroxypropyl starch, oxidized starch, lignin sulfonate, alkylated lignin, casein, zein, soy protein isolate, shellac, rosin, natural rubber, or combinations thereof.

5. The environmentally friendly color masterbatch based on a natural material carrier according to claim 1, characterized in that, The pigments are selected from organic pigments, inorganic pigments, or combinations thereof; the organic pigments include phthalocyanine pigments, azo pigments, quinacridone pigments, dioxazine pigments, isoindoline pigments, anthraquinone pigments, benzimidazolone pigments, or combinations thereof; The inorganic pigments include titanium dioxide, iron oxide, carbon black, ultramarine, chrome yellow, cadmium red, lead chrome yellow, composite metal oxide pigments, or combinations thereof. The average particle size of the pigment is 50 nanometers to 5 micrometers; the surface of the pigment may be pre-modified, and the surface modification treatment includes coating or grafting with fatty acids, fatty acid salts, silane coupling agents, titanate coupling agents or polymeric dispersants.

6. The environmentally friendly color masterbatch based on a natural material carrier according to claim 1, characterized in that, The compatibilizer is selected from maleic anhydride grafted polymers, epoxy group polymers, amphiphilic block copolymers, silane coupling agents, titanate coupling agents, or combinations thereof. The maleic anhydride-grafted polymers include maleic anhydride-grafted polylactic acid, maleic anhydride-grafted polycaprolactone, maleic anhydride-grafted polyethylene, or maleic anhydride-grafted polypropylene. The epoxy group polymer includes epoxidized soybean oil, epoxy resin, or acrylate copolymer containing epoxy groups. The amphiphilic block copolymers include polylactic acid-polyethylene glycol block copolymers, polycaprolactone-polyethylene glycol block copolymers, or starch-polyethylene block copolymers.

7. The environmentally friendly color masterbatch based on a natural material carrier according to claim 1, characterized in that, The stabilizer is selected from antioxidants, ultraviolet absorbers, light stabilizers, metal passivators, or combinations thereof; The antioxidants include hindered phenolic antioxidants, phosphite antioxidants, or thioester antioxidants; The ultraviolet absorber includes benzotriazole, triazine, or benzophenone ultraviolet absorbers; The light stabilizer includes hindered amine light stabilizers.

8. The environmentally friendly color masterbatch based on a natural material carrier according to claim 1, characterized in that, The processing aid is selected from plasticizers, lubricants, flow modifiers, release agents, or combinations thereof; The plasticizer includes bio-based plasticizers, phthalates or fatty acid esters, and the bio-based plasticizers are preferably citrate esters, glycerides, epoxidized soybean oil or polyethylene glycol; The lubricant includes fatty acid amides, metal soaps, paraffin wax, polyethylene wax, or natural wax; The flow modifier includes modified rosin esters, terpene resins, or low molecular weight polylactic acid.

9. A method for preparing an environmentally friendly color masterbatch based on a natural material carrier, applicable to the environmentally friendly color masterbatch based on a natural material carrier as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Pre-treat the first natural polymer base material, including drying and pulverizing it into powder with an average particle size of less than 100 micrometers; Step 2: Dry and pulverize the second natural polymer base material into powder with an average particle size of less than 150 micrometers; Step 3: Mix the pretreated first natural polymer base, second natural polymer base, pigment, compatibilizer, stabilizer and processing aid at high speed according to the preset ratio to obtain a uniformly mixed premix. Step 4: The premixed material is melt-blended and granulated using a twin-screw extruder to obtain the environmentally friendly color masterbatch.

10. The method for preparing an environmentally friendly color masterbatch based on a natural material carrier according to claim 9, characterized in that, The first natural polymer base material pretreatment in step one also includes hydrophobic modification treatment. The hydrophobic modification treatment can be carried out independently before step one, or in situ during the melt blending process in step four. When carried out independently, it is obtained by reacting cellulose and its derivatives with the modifier in a reaction vessel at 80°C to 150°C for 2 to 10 hours in the presence of a specific solvent and catalyst, followed by washing and drying. The high-speed mixing in step three is carried out in a high-speed mixer with a mixing speed of 500 rpm to 1500 rpm, a mixing time of 5 minutes to 20 minutes, and a mixing temperature of 20°C to 60°C. The length-to-diameter ratio of the twin-screw extruder in step four is 28:1 to 48:1; the screw configuration includes a conveying section, a plasticizing section, a mixing section and a metering section, and the mixing section contains at least two sets of kneading blocks or dispersing elements; The extrusion temperature is 140°C to 200°C, with the following temperature gradients in each zone: 140°C to 150°C in the feeding section, 150°C to 170°C in the compression section, 160°C to 190°C in the melting section, and 170°C to 200°C in the metering section; the screw speed is 100 rpm to 500 rpm; the extruder die is a perforated plate design with a diameter of 2 mm to 5 mm; after the molten extrudate is cooled to room temperature in a water bath, it is cut into pellets with a length of 2 mm to 5 mm by a pelletizer; the masterbatch after pelleting is vacuum dried at 60°C to 80°C for 4 to 8 hours.

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