Degradable environment-friendly whitening master batch and preparation method thereof

Abstract

This invention belongs to the field of functional masterbatch technology, specifically providing a biodegradable and environmentally friendly whitening masterbatch and its preparation method. By mass percentage, the whitening masterbatch comprises the following raw materials: 30-40% matrix resin, 3-5% plasticizer, 1-5% fluorescent whitening agent, 25-30% inorganic whitening agent, 1-3% functional dispersant, 0.5-3% antioxidant, 0.5-1% ultramarine pigment, and the balance calcium carbonate. The whitening masterbatch provided by this invention has excellent applicability, high dispersibility, good whitening effect, and is environmentally friendly and reliable.

Description

Technical Field

[0001] This invention belongs to the field of functional masterbatch technology, specifically relating to a biodegradable and environmentally friendly whitening masterbatch and its preparation method. Background Technology

[0002] In the processing and application of plastic products, improving the appearance and physical and mechanical properties of products has always been the core driving force for technological innovation. Especially in the recycling process of post-consumer recycled plastics, the raw materials undergo varying degrees of aging, degradation, and pollution, resulting in yellowing, reduced transparency, poor gloss, and severely deteriorated mechanical properties. To meet the downstream market's dual demands for material appearance (high whiteness, high brightness) and internal quality (strength, toughness), effective modification and brightening treatments are necessary for these recycled plastics. Currently, the commonly used technical approach in industry is to achieve whitening and brightening of materials by adding inorganic whitening agents and fluorescent whitening agents.

[0003] Inorganic brighteners (such as titanium dioxide) primarily rely on their high refractive index and strong hiding power to physically scatter light, visually masking impurities and yellowness in the resin matrix, thereby enhancing the material's whiteness. Fluorescent brighteners, on the other hand, are optical brightening materials. They absorb ultraviolet light in the 300-400nm wavelength range and convert the energy into blue-violet visible light in the 400-500nm wavelength range. This emitted fluorescence complements and superimposes with the original yellow light of the matrix, producing whitening, brightening, and increased gloss effects. In actual production, operators typically mechanically blend these two powder additives with the resin matrix using a high-speed mixer, and then feed them into extrusion granulation or injection molding equipment for processing.

[0004] However, this traditional physical mixing and addition technology has revealed many insurmountable technical defects in practical applications, severely restricting the quality improvement and functional development of high-end plastic products. Firstly, the problem of uniformity in mixing and dispersion is particularly prominent. Both inorganic whitening agent powders and fluorescent whitening agents exist in the form of micron- or even nano-sized solid powders. When mixed with molten resins of high viscosity and different polarities, simple mechanical shearing force alone is often insufficient to achieve ideal distribution within the matrix. Due to the agglomeration effect between powders and the differences in the affinity of the resin matrix for different additives, it is easy for localized areas to become enriched in additives while other areas are lacking, resulting in color differences, spots, or flow marks. This directly leads to unstable whitening and brightening effects and poor product appearance consistency.

[0005] Secondly, the molecular structure of optical brighteners is mostly composed of small organic molecules, lacking strong chemical bonds with the polymer resin matrix. This physical blending system is thermodynamically in a non-equilibrium state, making the optical brightener molecules highly mobile. During subsequent use of the product, especially in humid environments, solvent contact, or high-temperature conditions, these small molecules easily migrate to the product surface, seep out, or are even wiped off or evaporated. This migration not only leads to a rapid decrease in the whiteness and loss of gloss of the product surface but may also contaminate other items in contact with the plastic. In addition, optical brighteners generally have poor lightfastness. Under long-term outdoor sunlight or ultraviolet light irradiation, their molecular structure is prone to photodegradation, leading to attenuation or even disappearance of the fluorescence effect, i.e., "yellowing," which seriously affects the service life of the product. At the same time, inorganic brightener powders are inorganic rigid particles, and their surface properties are fundamentally different from most organic polymer resins (such as polyolefins and polyesters), resulting in poor interfacial compatibility between the two. This incompatibility creates stress concentration points at the interface between the two phases. When the product is subjected to external forces, microcracks are easily induced at the interface and propagate rapidly. At the same time, due to poor compatibility, inorganic powders are also prone to migrate from the interior of the product to the surface during long-term storage or use, resulting in "frost" or "powdering" on the surface of the product. This not only damages the smoothness of the appearance but also further exacerbates the degradation of the product's performance.

[0006] Invention patent CN102199332A discloses a method for preparing a chemically composite polymeric toughening and whitening additive for plastics, and the resulting product. The method involves spraying 0.5-8% by mass of a coupling agent (as part of an inorganic whitening agent) onto 20-60 parts of an inorganic whitening agent powder while stirring, maintaining the mixture for a certain period to create an inorganic whitening agent anchored with the coupling agent. The anchored inorganic whitening agent is then mixed with 20-80 parts of a thermoplastic elastomer, 0.5-5 parts of a polymeric fluorescent whitening agent, 0.2-1.0 parts of a peroxide initiator, 0.1-0.2 parts of an antioxidant, and 0.3-1.5 parts of a lubricant in a high-speed mixer. The resulting mixture is then added to a compounding twin-screw extruder, and after compounding, extrusion, pelletizing, and cooling, a polymeric toughening and whitening additive is obtained. This additive is a functional chemically composite polymeric toughening and whitening additive for plastics that integrates toughening, whitening, brightening, and environmental friendliness. However, there is still room for improvement in its stability, especially since it is prone to yellowing and aging due to failure and decreased whiteness under long-term outdoor use. Summary of the Invention

[0007] To address the existing technical problems, the present invention aims to provide a biodegradable and environmentally friendly whitening masterbatch and its preparation method. The whitening masterbatch provided by the present invention has excellent applicability, high dispersibility, good whitening effect, and is environmentally friendly and reliable.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides a biodegradable and environmentally friendly whitening masterbatch, which, by weight percentage (100%), comprises the following raw materials: 30-40% matrix resin, 3-5% plasticizer, 1-5% fluorescent whitening agent, 25-30% inorganic whitening agent, 1-3% functional dispersant, 0.5-3% antioxidant, 0.5-1% ultramarine pigment, and the balance calcium carbonate.

[0009] In some embodiments of the present invention, the matrix resin is polylactic acid with a number average molecular weight of 50,000-200,000.

[0010] In some embodiments of the present invention, the plasticizer is an acetylated fatty acid ester.

[0011] In some embodiments of the present invention, the fluorescent whitening agent is fluorescent whitening agent OB or fluorescent whitening agent OB-1.

[0012] In some embodiments of the present invention, the inorganic brightener is titanium dioxide.

[0013] In some embodiments of the present invention, the preparation steps of the functional dispersant are as follows: (1) Mix divinylbenzene and 3-mercaptopropyltrimethoxysilane, add triethylamine, and react at 60-70℃ for 2-4 hours under an inert atmosphere to obtain the functional monomer; (2) Add acrylic acid, methoxylated polyethylene glycol monomer and functional monomer to isopropanol, stir and heat to 60-70°C under an inert atmosphere, then slowly add benzoyl peroxide dropwise, continue to heat to 70-85°C, react for 5-6 hours, cool to room temperature after the reaction, adjust the pH to neutral, and obtain the functional dispersant by rotary evaporation.

[0014] In some embodiments of the present invention, in step (1), the mass ratio of the divinylbenzene and 3-mercaptopropyltrimethoxysilane is 1:(1.2-1.5).

[0015] In some embodiments of the present invention, in step (2), the mass ratio of the acrylic acid, the methoxylated polyethylene glycol monomer and the functional monomer is 1:(2-3):(1.5-2).

[0016] In some embodiments of the present invention, in step (2), the methoxy-grafted polyethylene glycol monomer is methoxy polyethylene glycol methacrylate.

[0017] This invention prepares a novel polymeric dispersant as a functional dispersant. When added to a whitening masterbatch system, it effectively improves the compatibility and dispersion uniformity of the components through the synergistic effect of hydrophobic and hydrophilic segments, thereby achieving excellent whitening effects. Specifically, this invention optimizes the ratio of benzene ring structure to adsorption groups in the hydrophobic segments, as well as the length and density of polyethylene glycol segments in the hydrophilic segments, to maximize the adsorption anchoring ability and steric stabilization effect of the dispersant in the system, ensuring that it maintains excellent dispersion stability during high-shear processing or long-term storage. Furthermore, the presence of benzene rings not only enhances the rigidity of the main chain and helps improve the steric hindrance effect, effectively preventing the re-aggregation between filler or pigment particles, but also enhances the affinity with organic components through π-π stacking. The presence of adsorption groups further improves the weather resistance stability of the dispersant by forming multi-point strong adsorption with the particle surface, effectively avoiding dispersion failure and whitening performance degradation caused by migration or desorption. Thus, the material can maintain high whiteness and color uniformity even under long-term use or high temperature and humidity environments, achieving sustained performance of high-performance whitening and ensuring the long-term stability of functional dispersants in complex multiphase systems.

[0018] In some embodiments of the present invention, the antioxidant is one or more of antioxidant 1076, antioxidant 164 and antioxidant 168.

[0019] A second aspect of the present invention also provides a method for preparing a biodegradable and environmentally friendly whitening masterbatch, comprising the following steps: The matrix resin, plasticizer, fluorescent whitening agent, inorganic whitening agent, functional dispersant, antioxidant, ultramarine blue pigment and calcium carbonate are mixed in proportion until uniform, and then added to a compounding twin-screw extruder. After compounding, plasticizing, extrusion, pelletizing and cooling, the biodegradable and environmentally friendly whitening masterbatch is obtained.

[0020] Preferably, the temperature is controlled at 160-200℃ and the screw speed is 200-300r / min during the mixing and extrusion.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The whitening masterbatch provided by this invention has excellent applicability, high dispersibility, good whitening effect, and is environmentally friendly and reliable.

[0022] 2. This invention prepares a functional dispersant, optimizes the distribution of benzene rings and adsorption groups in the hydrophobic segments, and hydrophilic segments, synergistically improving the dispersibility and stability of the whitening masterbatch, significantly enhancing weather resistance, ensuring that it can maintain high whiteness and color uniformity even under outdoor or long-term use, and achieving a lasting whitening effect. Detailed Implementation

[0023] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0024] To facilitate implementation of this invention by those skilled in the art, the sources of some raw materials in the specific embodiments are described below: The EO=15 of the methoxy polyethylene glycol methacrylate used; the matrix resin used was polylactic acid with a number average molecular weight of 119,000, grade 4060D, purchased from Natureworks; the plasticizer used was diacetylepoxy glyceryl vegetable oil, model HM-828, purchased from Guangzhou Haierma Vegetable Oil Co., Ltd.; the fluorescent whitening agent used was fluorescent whitening agent OB-1; the inorganic whitening agent used was titanium dioxide; the antioxidant used was antioxidant 1076 and antioxidant 168 mixed at a mass ratio of 1:0.5.

[0025] Unless otherwise specified, all other raw materials can be purchased from the market.

[0026] Unless otherwise specified, the post-processing steps such as "rotary steaming", "mixing", "plasticizing", "extrusion", and "granulation" in the following specific embodiments are routine operations for those skilled in the art, and can be selected according to actual operation.

[0027] Preparation Example 1 The preparation steps of the functional dispersant are as follows: (1) Mix 10g of divinylbenzene and 13g of 3-mercaptopropyltrimethoxysilane, add 0.35g of triethylamine, and react at 65°C for 3h under a nitrogen atmosphere to obtain a functional monomer; (2) Add 2g of acrylic acid, 5g of methoxy polyethylene glycol methacrylate and 3.4g of the functional monomer from step (1) to 20mL of isopropanol. Stir and heat to 65°C under a nitrogen atmosphere, then slowly add 0.2g of benzoyl peroxide, continue heating to 80°C, react for 5.5h, cool to room temperature after the reaction, adjust the pH to 7, and obtain the functional dispersant by rotary evaporation.

[0028] Preparation Example 2 The specific preparation steps of the functional dispersant are the same as those in Preparation Example 1, except that the amount of methoxy polyethylene glycol methacrylate added in step (2) is 7g.

[0029] Preparation Example 3 The specific preparation steps of the functional dispersant are the same as those in Preparation Example 1, except that the amount of functional monomer added in step (2) is 5g.

[0030] Preparation Example 4 The preparation steps of the functional dispersant are as follows: 2g of acrylic acid, 5g of methoxy polyethylene glycol methacrylate and 3.4g of styrene were added to 20mL of isopropanol. Under a nitrogen atmosphere, the mixture was stirred and heated to 65°C. Then, 0.2g of benzoyl peroxide was slowly added dropwise, and the temperature was further increased to 80°C. The reaction was carried out for 5.5h. After the reaction was completed, the mixture was cooled to room temperature, and the pH was adjusted to 7. The functional dispersant was obtained by rotary evaporation.

[0031] Example 1 A biodegradable and environmentally friendly whitening masterbatch, by weight percentage, contains the following raw materials: 35% matrix resin, 4% plasticizer, 3% fluorescent whitening agent, 27% inorganic whitening agent, 2% functional dispersant, 1.5% antioxidant, 0.7% ultramarine pigment, and the balance calcium carbonate.

[0032] The method for preparing the biodegradable and environmentally friendly whitening masterbatch in this embodiment includes the following steps: The matrix resin, plasticizer, fluorescent whitening agent, inorganic whitening agent, functional dispersant, antioxidant, ultramarine blue pigment and calcium carbonate are mixed in proportion until uniform, and then added to a compounding twin-screw extruder. After compounding, plasticizing, extrusion, pelletizing and cooling, the biodegradable and environmentally friendly whitening masterbatch is obtained.

[0033] The mixing and extrusion processes are controlled at 180°C, with the screw speed at 250 r / min.

[0034] The functional dispersant used in this embodiment was obtained from Preparation Example 1.

[0035] Example 2 A biodegradable and environmentally friendly whitening masterbatch, by weight percentage, contains the following raw materials: 30% matrix resin, 3% plasticizer, 1% fluorescent whitening agent, 25% inorganic whitening agent, 1% functional dispersant, 0.5% antioxidant, 0.5% ultramarine pigment, and the balance calcium carbonate.

[0036] The method for preparing the biodegradable and environmentally friendly whitening masterbatch in this embodiment includes the following steps: The matrix resin, plasticizer, fluorescent whitening agent, inorganic whitening agent, functional dispersant, antioxidant, ultramarine blue pigment and calcium carbonate are mixed in proportion until uniform, and then added to a compounding twin-screw extruder. After compounding, plasticizing, extrusion, pelletizing and cooling, the biodegradable and environmentally friendly whitening masterbatch is obtained.

[0037] The mixing, plasticizing, and extrusion processes are controlled at 180°C, with the screw speed at 250 r / min.

[0038] The functional dispersant used in this embodiment was obtained from Preparation Example 1.

[0039] Example 3 A biodegradable and environmentally friendly whitening masterbatch, by weight percentage, contains the following raw materials: 40% matrix resin, 5% plasticizer, 5% fluorescent whitening agent, 30% inorganic whitening agent, 3% functional dispersant, 3% antioxidant, 1% ultramarine pigment, and the balance calcium carbonate.

[0040] The method for preparing the biodegradable and environmentally friendly whitening masterbatch in this embodiment includes the following steps: The matrix resin, plasticizer, fluorescent whitening agent, inorganic whitening agent, functional dispersant, antioxidant, ultramarine blue pigment and calcium carbonate are mixed in proportion until uniform, and then added to a compounding twin-screw extruder. After compounding, plasticizing, extrusion, pelletizing and cooling, the biodegradable and environmentally friendly whitening masterbatch is obtained.

[0041] The mixing, plasticizing, and extrusion processes are controlled at 180°C, with the screw speed at 250 r / min.

[0042] The functional dispersant used in this embodiment was obtained from Preparation Example 1.

[0043] Example 4 A biodegradable and environmentally friendly whitening masterbatch and its preparation method are described. The specific implementation method is the same as that in Example 1, except that the functional dispersant used in this example is obtained from Preparation Example 2.

[0044] Example 5 A biodegradable and environmentally friendly whitening masterbatch and its preparation method are described. The specific implementation method is the same as that in Example 1, except that the functional dispersant used in this example is obtained from Preparation Example 3.

[0045] Example 6 A biodegradable and environmentally friendly whitening masterbatch and its preparation method are described. The specific implementation method is the same as that in Example 1, except that the functional dispersant used in this example is obtained from Preparation Example 4.

[0046] Example 7 A biodegradable and environmentally friendly whitening masterbatch and its preparation method are described. The specific implementation method is the same as that in Example 1, except that the functional dispersant used in this example is low molecular weight polyethylene wax AC 6A.

[0047] Performance testing The whitening masterbatch prepared in Examples 1-7 above was mixed with PVC base material at a ratio of 20 mg / 100 g and then injected into plastic sheets as samples using a plastic injection molding machine. The aging whiteness of the PVC plastic sheets before and after aging was tested according to the oven aging test in GB / T 15595-2008. The specific test results are shown in Table 1. Table 1

[0048] As shown in Table 1, the whitening masterbatches prepared in Examples 1-3 have high whitening effect and stability.

[0049] Comparing Examples 4 and 5 with Example 1, it can be seen that when the amounts of methoxy polyethylene glycol methacrylate and functional monomers added are changed during the preparation of the functional dispersant, the former disrupts the hydrophilic-hydrophobic balance, reduces the compatibility and stability of the system, and decreases the whiteness and stability of the sample; the latter may be affected by excessive winding, failing to play an effective encapsulation and stabilizing role, resulting in varying degrees of decrease in the whiteness and stability of the sample. Comparing Example 6 with Example 1, it can be seen that when styrene is used to replace the functional monomer in an equal amount during the preparation of the functional dispersant, the whitening effect may be significantly reduced due to the decreased stability of the functional dispersant and its easy migration. Comparing Example 7 with Comparative Example 1, it can be seen that when the functional dispersant used is low molecular weight polyethylene wax AC 6A, it cannot stabilize the whitening component in the system for a long time, resulting in insufficient whitening performance.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present application in any way. Although the present application discloses the preferred embodiment as described above, it is not intended to limit the present application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A biodegradable and environmentally friendly whitening masterbatch, characterized in that, The whitening masterbatch comprises the following raw materials in 100% by weight: 30-40% matrix resin, 3-5% plasticizer, 1-5% fluorescent whitening agent, 25-30% inorganic whitening agent, 1-3% functional dispersant, 0.5-3% antioxidant, 0.5-1% ultramarine pigment, and the balance calcium carbonate.

2. The biodegradable and environmentally friendly whitening masterbatch according to claim 1, characterized in that, The matrix resin is polylactic acid with a number average molecular weight of 50,000-200,000.

3. The biodegradable and environmentally friendly whitening masterbatch according to claim 1, characterized in that, The fluorescent whitening agent is fluorescent whitening agent OB or fluorescent whitening agent OB-1.

4. The biodegradable and environmentally friendly whitening masterbatch according to claim 1, characterized in that, The inorganic brightener is titanium dioxide.

5. The biodegradable and environmentally friendly whitening masterbatch according to claim 1, characterized in that, The preparation steps of the functional dispersant are as follows: (1) Mix divinylbenzene and 3-mercaptopropyltrimethoxysilane, add triethylamine, and react at 60-70℃ for 2-4 hours under an inert atmosphere to obtain the functional monomer; (2) Add acrylic acid, methoxylated polyethylene glycol monomer and functional monomer to isopropanol, stir and heat to 60-70°C under an inert atmosphere, then slowly add benzoyl peroxide dropwise, continue to heat to 70-85°C, react for 5-6 hours, cool to room temperature after the reaction, adjust the pH to neutral, and obtain the functional dispersant by rotary evaporation.

6. The biodegradable and environmentally friendly whitening masterbatch according to claim 5, characterized in that, In step (1), the mass ratio of the divinylbenzene and 3-mercaptopropyltrimethoxysilane is 1:(1.2-1.5).

7. The biodegradable and environmentally friendly whitening masterbatch according to claim 5, characterized in that, In step (2), the mass ratio of acrylic acid, methoxylated polyethylene glycol monomer and functional monomer is 1:(2-3):(1.5-2).

8. The biodegradable and environmentally friendly whitening masterbatch according to claim 5, characterized in that, In step (2), the methoxy-grafted polyethylene glycol monomer is methoxy polyethylene glycol methacrylate.

9. The biodegradable and environmentally friendly whitening masterbatch according to claim 1, characterized in that, The antioxidant is one or more of antioxidant 1076, antioxidant 164 and antioxidant 168.

10. A method for preparing the biodegradable and environmentally friendly whitening masterbatch according to any one of claims 1-9, characterized in that, It includes the following steps: The matrix resin, plasticizer, fluorescent whitening agent, inorganic whitening agent, functional dispersant, antioxidant, ultramarine blue pigment and calcium carbonate are mixed in proportion until uniform, and then added to a compounding twin-screw extruder. After compounding, extrusion, pelletizing and cooling, the biodegradable and environmentally friendly whitening masterbatch is obtained.

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