Polypropylene color masterbatch and preparation method thereof

Abstract

The application discloses polypropylene color master batch and a preparation method thereof. The color master batch comprises the following raw materials in parts by mass: 100 parts of carboxyl modified polypropylene, 15-25 parts of phthalocyanine pigments, 2-5 parts of lubricants, 1-2 parts of antioxidants, and 5-8 parts of surface treatment agents. The surface treatment agents are prepared by silicon-hydrogen addition of alpha-olefins, silane coupling agents containing unsaturated bonds, and hydrogen-containing silicone oils with at least two silicon-hydrogen groups. The molar ratio of the alpha-olefins, the silane coupling agents containing unsaturated bonds, and the hydrogen-containing silicone oils with silicon-hydrogen groups is 0.4-0.8:0.3-0.6:1. The application can effectively solve the problems of small molecule hydrophilic auxiliary agent migration and content stability decline caused by the polarity improvement of the carrier resin in the cosmetic packaging container.

Description

Technical Field

[0001] This application relates to the field of polypropylene materials, and in particular to a polypropylene masterbatch and its preparation method. Background Technology

[0002] Polypropylene masterbatch is a functional coloring masterbatch made by uniformly dispersing high-concentration pigments and other additives in polypropylene as a carrier resin through melt blending. Due to its advantages such as high coloring efficiency, ease of use, and low dust pollution, it is widely used in the coloring processing of plastic products, especially in food packaging, daily chemical products, and cosmetic packaging. However, in practical applications, the coloring effect of masterbatch largely depends on the uniformity of pigment dispersion in the carrier resin. Since pigments are mostly polar inorganic or organic compounds, there is a significant polarity difference between them and the non-polar polypropylene matrix, resulting in poor compatibility and difficulty in achieving good wetting and stable dispersion. This uneven dispersion not only affects the color consistency and appearance quality of the product but may also lead to problems such as decreased mechanical properties and deterioration of thermal stability.

[0003] To improve the interfacial compatibility between pigments and polypropylene, existing technologies typically involve chemical modification of polypropylene. This can be achieved through methods such as melt grafting of polar monomers like maleic anhydride and acrylic acid, or by introducing polar compatibilizers and block copolymers into the system. These methods enhance the wetting ability and dispersion stability of the carrier resin for pigments. While these methods improve the processing performance and coloring effect of masterbatches to some extent, they are particularly suitable for general-purpose plastic products. However, while increasing the polarity of the carrier resin is beneficial for pigment dispersion, it also enhances the overall hydrophilicity and polarity of the material. This makes it easier for small molecules to penetrate the packaging bottle when it comes into contact with cosmetic contents containing alcohol solvents or fragrances (often containing small polar molecules such as alcohols and aldehydes). These polar components can penetrate into the bottle, extracting commonly used small-molecule antioxidants (such as hindered phenolic antioxidants 1010, 1076, or phosphite antioxidants), dispersants, and other polar components. This causes polar components to migrate from the polymer matrix into the cosmetic, affecting the stability of the cosmetic. For example, when antioxidants migrate from the bottle into the contents, they are easily oxidized under the catalysis of oxygen and light, generating quinone structures or other colored degradation products. This not only causes cosmetics to turn yellow, but may also produce an odor, seriously affecting the sensory quality of the product and consumer safety. Summary of the Invention

[0004] This application aims to address the problems of antioxidant migration and yellowing of contents in cosmetic packaging caused by the increased polarity of the carrier resin.

[0005] In a first aspect, this application provides a polypropylene masterbatch, which comprises the following raw materials in parts by weight: The mixture comprises 100 parts of carboxyl-modified polypropylene, 15-25 parts of phthalocyanine pigment, 2-5 parts of lubricant, 1-2 parts of antioxidant, and 5-8 parts of surface treatment agent; the surface treatment agent is prepared by hydrosilylation of α-olefin, unsaturated silane coupling agent, and hydrogen-containing silicone oil having at least two silane groups, wherein the molar ratio of silane groups in the α-olefin, unsaturated silane coupling agent, and hydrogen-containing silicone oil is 0.4-0.8:0.3-0.6:1.

[0006] For example, the phthalocyanine pigment is one or more of phthalocyanine blue, phthalocyanine red, and phthalocyanine green.

[0007] It is worth noting that the pigments in this application are not limited to phthalocyanine pigments; other pigments, such as azo pigments and quinacridone pigments, can be added as needed for formulation.

[0008] In any of the above technical solutions, the hydrogen-containing silicone oil having at least two hydroxyl groups refers to the hydrogen-containing silicone oil molecule having at least two Si-H groups. For example, the hydrogen-containing silicone oil having at least two hydroxyl groups is selected from at least one of side-ended hydrogen-containing silicone oil, double-ended hydrogen-containing silicone oil, or end-side hydrogen-containing silicone oil.

[0009] In any of the above technical solutions, the α-olefin has 8 to 16 carbon atoms.

[0010] In any of the above technical solutions, the viscosity of the hydrogen-containing silicone oil is 30-100 mm. 2 / s.

[0011] In any of the above technical solutions, the unsaturated bond-containing silane coupling agent is a methacryloyloxysilane coupling agent and / or a vinyl silane coupling agent; preferably, the methacryloyloxysilane coupling agent is selected from methacryloyloxypropyltrimethoxysilane or methacryloyloxypropyltriethoxysilane; the vinyl silane coupling agent is selected from vinyltrimethoxysilane or vinylpropyltriethoxysilane.

[0012] First, this application selects phthalocyanine pigments with excellent thermal stability, which can maintain melt processing performance under high pigment dosage conditions and reduce extrusion decomposition problems caused by excessive pigment. Second, carboxyl-modified polypropylene is used as the carrier resin, which not only improves the compatibility between the resin and the pigment, but also utilizes the carboxyl groups to form coordination bonds with the metal centers of the phthalocyanine pigments; through this dual effect, the wetting and dispersibility of the pigment in the polypropylene matrix is ​​improved, significantly enhancing color uniformity and ensuring color consistency of the packaging bottles. At the same time, the coordination network between the carboxyl groups and the phthalocyanine pigments helps to regulate the migration rate of the surface treatment agent, achieving a sustained-release effect and extending the anti-yellowing period of cosmetics. This surface treatment agent is prepared by hydrosilylation of α-olefins, unsaturated silane coupling agents, and hydrogen-containing silicone oil under a platinum catalyst. Its polysiloxane segments endow it with low surface energy properties, enabling the surface treatment agent to migrate and precipitate uniformly onto the surface of the packaging bottle. Through hydrolysis and self-condensation of the siloxane groups in the molecule, a dense hydrophobic barrier layer is formed, which effectively blocks the penetration of polar ingredients such as alcohols and fragrances in cosmetics, and prevents polar ingredients such as antioxidants and dispersants from being extracted, migrated, and subsequently oxidized to produce colored substances, precipitation, or odor.

[0013] It should be noted that limiting the carbon chain length of α-olefins and the viscosity of hydrogen-containing silicone oil ensures that the surface treatment agent is uniformly dispersed in the matrix and has a moderate precipitation rate, thereby guaranteeing the long-term sensory stability of the cosmetic contents. Specifically, too short an α-olefin carbon chain leads to poor compatibility, while too long a chain results in slow precipitation; if the viscosity of the hydrogen-containing silicone oil is too low, precipitation is too rapid, reducing its long-lasting effect; if the viscosity is too high, precipitation is hindered, leading to a decrease in film density.

[0014] In any of the above technical solutions, the carboxyl-modified polypropylene is obtained by free radical copolymerization of raw materials containing homopolymer polypropylene and dicarboxylic acid monomer, wherein the mass ratio of homopolymer polypropylene to dicarboxylic acid monomer is 100:1.5 to 3.

[0015] In any of the above technical solutions, the dicarboxylic acid monomer is selected from one or more of maleic acid, itaconic acid, and fumaric acid.

[0016] In any of the above technical solutions, the raw material of the carboxyl-modified polypropylene includes styrene, and the mass ratio of homopolymer polypropylene to styrene is 100:1 to 2.

[0017] This application introduces styrene into the preparation of carboxyl-modified polypropylene. The strong interaction between the π-electron system of the styrene chain segments and the conjugated π-π structure of the phthalocyanine pigment further enhances the interfacial compatibility between the pigment and the carrier resin. This π-π interaction continues during melt processing, effectively inhibiting pigment agglomeration, improving dispersion uniformity, reducing shear stress during extrusion under high pigment loads, minimizing the risk of thermal degradation, and improving the color consistency and appearance quality of cosmetic packaging bottles.

[0018] In any of the above technical solutions, the lubricant is polyethylene wax with a melting point of 100-120°C.

[0019] In any of the above technical solutions, the antioxidant is a combination of hindered phenolic antioxidant and phosphite antioxidant, with a mass ratio of 1:0.5 to 1.5.

[0020] Secondly, this application provides a method for preparing polypropylene masterbatch, wherein carboxyl-modified polypropylene, phthalocyanine pigment, lubricant, antioxidant and surface treatment agent are mixed in proportion and granulated by twin-screw extrusion at 190-230°C to obtain masterbatch.

[0021] In summary, this application has the following beneficial effects: This application significantly improves pigment dispersibility and heat resistance by coordinating carboxyl-modified polypropylene with phthalocyanine pigments, thus preventing thermal decomposition under high pigment loads. The introduced precipitation-type surface treatment agent forms a hydrophobic barrier layer on the packaging bottle surface, effectively inhibiting the penetration of polar components in cosmetics and preventing antioxidants from migrating into the cosmetics and causing oxidative degradation and discoloration. Simultaneously, the enhanced π-π interactions of styrene segments further optimize pigment dispersion, and precise control of the α-olefin carbon chain length and the viscosity of the hydrogen-containing silicone oil ensures uniform precipitation of the surface treatment agent, forming a dense film. Therefore, this application's solution effectively addresses the storage stability issue of cosmetics while ensuring excellent coloring effects, significantly improving the safety of packaging materials and the long-term stability of the product. Detailed Implementation

[0022] Preparation Example Preparation Example 1-1, surface treatment agent, was prepared according to the following procedure: Take hydrogen-containing silicone oil RH-H503 (viscosity 50-70 mm) 2 181.8 g of a 0.55% hydrogen compound (containing approximately 1 mol of silane) was added to a reaction flask. Nitrogen gas was bubbled through the flask three times to purge the air, maintaining a nitrogen protective atmosphere. The reaction system was heated to 80°C. After the temperature stabilized, 100.8 g (0.6 mol) of 1-dodecene and 101.8 g (0.45 mol) of methacryloxypropyltrimethoxysilane were added sequentially. The reaction system was heated to 100°C, and 0.96 g of a chloroplatinic acid-isopropanol solution (Pt content 2000 ppm) was added. The reaction temperature was maintained at 100±5°C, and the mixture was stirred for 8 hours. After the reaction was complete, the reaction system was cooled to 80°C, and low-boiling substances were removed under a vacuum of -0.09 MPa for 30 minutes. The mixture was further cooled to room temperature, and the residue was filtered to remove any trace amounts of insoluble matter, yielding the surface treatment agent.

[0023] Preparation Examples 1-2, surface treatment agents, were prepared according to the following procedures: Take hydrogen-containing silicone oil RH-LHC-3 (viscosity 30-40 mm)2 125g of a 0.8% hydrogen-containing compound (containing approximately 1 mol of silane) was added to a reaction flask. Nitrogen gas was bubbled through the flask three times to purge the air, maintaining a nitrogen protective atmosphere. The reaction system was heated to 75°C. After the temperature stabilized, 44.9g (0.4 mol) of 1-octene and 80.5g (0.6 mol) of vinyltrimethoxysilane were added sequentially. The reaction system was heated to 95°C, and 0.8g of a chloroplatinic acid-isopropanol solution (Pt content 2000 ppm) was added. The reaction temperature was maintained at 95±5°C, and the mixture was stirred for 9 hours. After the reaction was completed, the reaction system was cooled to 70°C, and low-boiling substances were removed under a vacuum of -0.09 MPa for 30 minutes. The mixture was further cooled to room temperature, and the residue was filtered to remove any trace amounts of insoluble matter, yielding the surface treatment agent.

[0024] Preparation Examples 1-3, surface treatment agents, were prepared according to the following procedures: Take hydrogen-containing silicone oil RH-H86 (viscosity 80-100 mm) 2 1110g of a 0.09% hydrogen peroxide (containing approximately 1 mol of hydroxyl groups) was added to a reaction flask. Nitrogen gas was bubbled through the flask three times to purge the air, maintaining a nitrogen protective atmosphere. The reaction system was heated to 80°C. After the temperature stabilized, 179.5g (0.8 mol) of 1-hexadecene and 74.5g (0.3 mol) of methacryloxypropyltrimethoxysilane were added sequentially. The reaction system was heated to 100°C, and 1.0g of a chloroplatinic acid-isopropanol solution (Pt content 2000 ppm) was added. The reaction temperature was maintained at 100±5°C, and the mixture was stirred for 10 hours. After the reaction was complete, the reaction system was cooled to 80°C, and low-boiling substances were removed under a vacuum of -0.09 MPa for 30 minutes. The mixture was further cooled to room temperature, and the residue was filtered to remove any trace amounts of insoluble matter, yielding the surface treatment agent.

[0025] Preparation Examples 1-4, surface treatment agents, differ from Preparation Example 1-1 in that they are prepared using RH-H536 (viscosity 10-20 mm). 2 / s, hydrogen content 0.36%) 277.8 g to replace RH-H503 (viscosity 50-70 mm) 2 / s, containing 0.55% hydrogen) 181.8g.

[0026] Preparation Examples 1-5, surface treatment agents, differ from Preparation Example 1-1 in that they are made with RH-H802 (viscosity 100-120 mm). 2 / s, hydrogen content 0.83%) 120.5g to replace RH-H503 (viscosity 50-70 mm) 2 / s, containing 0.55% hydrogen) 181.8g.

[0027] Preparation Examples 1-6, surface treatment agents, differ from Preparation Example 1-1 in that equimolar 1-dodecene is used instead of methacryloyloxypropyltrimethoxysilane.

[0028] Preparation Examples 1-7, surface treatment agents, differ from Preparation Example 1-1 in that 1-dodecene is replaced with an equimolar amount of methacryloyloxypropyltrimethoxysilane.

[0029] Preparation Example 2-1, carboxyl-modified polypropylene, was prepared according to the following steps: Dissolve 2.0g of dicumyl peroxide in 20mL of acetone to prepare an initiator solution. Mix 22.5g of maleic acid and 15g of styrene to obtain a monomer mixture. Dry 1000g of homopolymer polypropylene (Yanshan Petrochemical K1008) in an 80℃ oven for 2 hours to remove surface moisture. Then, add the dried homopolymer polypropylene granules, monomer mixture, and initiator solution to a high-speed mixer and mix at 800-1000rpm for 3-5 minutes at room temperature. During the mixing process, acetone evaporates, resulting in a premix. The premix is ​​then fed into a twin-screw extruder for melt grafting reaction. The extruder process parameters are set as follows: temperature range 170℃-190℃; screw speed 100±10rpm; feed speed 20±2rpm. After the melt grafting reaction is completed, the mixture is extruded into strips through the die head, cooled in a water bath (water temperature 25-35℃), air-dried, and then pelletized to obtain carboxyl-modified polypropylene granules.

[0030] Preparation Example 2-2, carboxyl-modified polypropylene, was prepared according to the following steps: Dissolve 1.5g of dicumyl peroxide in 15mL of acetone to prepare an initiator solution. Mix 15g of maleic acid and 20g of styrene to obtain a monomer mixture. Dry 1000g of homopolymer polypropylene (Yanshan Petrochemical K1008) in an 80℃ oven for 2 hours to remove surface moisture. Then, add the dried homopolymer polypropylene granules, monomer mixture, and initiator solution to a high-speed mixer and mix at 800-1000rpm for 3-5 minutes at room temperature. During the mixing process, acetone evaporates, resulting in a premix. Then, feed the premix into a twin-screw extruder for melt grafting reaction. The extruder process parameters are set as follows: temperature range 165℃-185℃; screw speed 80±10rpm; feed speed 20±2rpm. After the melt grafting reaction is completed, extrude the mixture into strips through the die head, cool them in a water bath (water temperature 25-35℃), air dry, and then granulate to obtain carboxyl-modified polypropylene granules.

[0031] Preparation Example 2-3, carboxyl-modified polypropylene, was prepared according to the following steps: Dissolve 3.0 g of dicumyl peroxide in 30 mL of acetone to prepare an initiator solution for later use. Mix 30 g of maleic acid and 10 g of styrene evenly to obtain a monomer mixture for later use. Dry 1000 g of homopolymer polypropylene (Yanshan Petrochemical K1008) in an oven at 80℃ for 2 hours to remove surface moisture.

[0032] The following steps are the same as in Preparation Example 2-1.

[0033] Preparation Example 2-4, carboxyl-modified polypropylene, differs from Preparation Example 2-1 in that styrene was not added.

[0034] Preparation Example 2-5, hydroxyl-modified polypropylene, differs from Preparation Example 2-1 in that maleic acid is replaced with an equal amount of hydroxyethyl acrylate.

[0035] Example Example 1: A polypropylene masterbatch was prepared by the following method: 1000g of carboxyl-modified polypropylene (prepared in Preparation Example 2-1), 200g of phthalocyanine blue BGS, 35g of polyethylene wax (melting point 105-110℃), 9g of antioxidant 1010, 9g of antioxidant 168, and 70g of surface treatment agent (prepared in Preparation Example 1-1) were sequentially added to a high-speed mixer. The mixer speed was 800-1000 rpm, and the mixing time was 5-8 minutes. The premixed material was then fed into a twin-screw extruder for melt blending and extrusion. The extruder process parameters were set as follows: temperature range 180℃-200℃; screw speed 300±20 rpm; feed speed 25±2 rpm. After melt mixing, the mixture was extruded into strips through the die head, cooled in a water bath (water temperature 25-35℃), dried by an air knife, and then pelletized by a pelletizer.

[0036] Example 2: A polypropylene masterbatch was prepared by the following method: 1000g of carboxyl-modified polypropylene (prepared in Preparation Example 2-2), 150g of phthalocyanine green G, 23g of polyethylene wax (melting point 105-110℃), 5g of antioxidant 1076, 5g of antioxidant 168, and 53g of surface treatment agent (prepared in Preparation Example 1-2) were sequentially added to a high-speed mixer. The mixer speed was 800-1000 rpm, and the mixing time was 5-8 minutes. The premixed material was then fed into a twin-screw extruder for melt blending and extrusion. The extruder process parameters were set as follows: temperature range 175℃-195℃; screw speed 300±20 rpm; feed speed 25±2 rpm. After melt mixing, the mixture was extruded into strips through the die head, cooled in a water bath (water temperature 25-35℃), dried by an air knife, and then pelletized by a pelletizer.

[0037] Example 3: A polypropylene masterbatch was prepared by the following method: 1000g of carboxyl-modified polypropylene (prepared in Preparation Examples 2-3), 250g of phthalocyanine blue BGS, 45g of polyethylene wax (melting point 105-110℃), 12g of antioxidant 1010, 8g of antioxidant 168, and 80g of surface treatment agent (prepared in Preparation Examples 1-3) were sequentially added to a high-speed mixer. The mixer speed was 800-1000 rpm, and the mixing time was 5-8 minutes. The premixed material was then fed into a twin-screw extruder for melt blending and extrusion. The extruder process parameters were set as follows: temperature range 185℃-205℃; screw speed 350±20 rpm; feed speed 30±2 rpm. After melt mixing, the mixture was extruded into strips through the die head, cooled in a water bath (water temperature 25-35℃), dried by an air knife, and then pelletized by a pelletizer.

[0038] Example 4, a polypropylene masterbatch, differs from Example 1 in that an equal amount of the surface treatment agent prepared in Preparation Examples 1-4 is used to replace the surface treatment agent prepared in Preparation Example 1-1.

[0039] Example 5, a polypropylene masterbatch, differs from Example 1 in that an equal amount of the surface treatment agent prepared in Preparation Examples 1-5 is used to replace the surface treatment agent prepared in Preparation Example 1-1.

[0040] Example 6, a polypropylene masterbatch, differs from Example 1 in that an equal amount of carboxyl-modified polypropylene prepared in Preparation Examples 2-4 is used to replace the carboxyl-modified polypropylene prepared in Preparation Example 2-1.

[0041] Comparative Example Comparative Example 1 is a polypropylene masterbatch, which differs from Example 1 in that an equal amount of the surface treatment agent prepared in Preparation Examples 1-6 is used instead of the surface treatment agent prepared in Preparation Example 1-1.

[0042] Comparative Example 2 is a polypropylene masterbatch, which differs from Example 1 in that an equal amount of the surface treatment agent prepared in Preparation Examples 1-7 is used instead of the surface treatment agent prepared in Preparation Examples 1-1.

[0043] Comparative Example 3 is a polypropylene masterbatch, which differs from Example 1 in that an equal amount of hydroxyl-modified polypropylene prepared in Preparation Examples 2-5 is used instead of the carboxyl-modified polypropylene prepared in Preparation Example 2-1.

[0044] Comparative Example 4 is a polypropylene masterbatch that differs from Example 1 in that an equal amount of Permanent Red F3RK is used instead of Phthalocyanine Blue BGS.

[0045] Performance testing Experiment 1: Determination of dispersibility of polypropylene masterbatch Test subjects: Color masterbatches prepared in the examples and comparative examples, injection molded into 400cm diameter sheets. 2 The color palette.

[0046] Test method: Refer to the provisions of HG / T 4668-2014 "Polypropylene (PP) Masterbatch" and place the color sample under D65 standard light source to observe whether there is color flow, streaks, or color spots. Use a 20x magnifying glass to detect the number of color spots and black spots.

[0047] Experiment 2: Packaging Bottle Color Consistency Test Sample preparation: The color masterbatch prepared in the examples and comparative examples was mixed with PP resin (Yanshan Petrochemical K1008, MFR=10-12g / 10min) at a mass ratio of 1:25, and then injection molded into cosmetic packaging bottles (capacity 50mL, wall thickness 1.5mm) at an injection temperature of 200±5℃.

[0048] Test Method: Color difference was measured using a colorimeter with a D65 light source and a 10° viewing angle. Ten bottles were randomly selected from each group, and measurements were taken at three different locations on each bottle (front, side, and bottom). The values ​​of L, a, and b* were recorded. Referring to ASTM D2244-23, "Standard Practice for Color Tolerance and Color Difference Calculation," the color difference ΔE1 at different locations on a single bottle and the color difference ΔE2 between bottles in the same batch were calculated (based on the average value).

[0049] Table 1. Test results of pigment dispersion performance of masterbatch

[0050] Test 3: Water Contact Angle Test of Packaging Bottle Sample preparation: The color masterbatch prepared in the examples and comparative examples was mixed with PP resin (Yanshan Petrochemical K1008, MFR=10-12g / 10min) at a mass ratio of 1:24, and then injection molded into cosmetic packaging bottles (capacity 50mL, wall thickness 1.5mm) at an injection temperature of 200±5℃. The packaging bottles were then heat-treated in an oven at 50℃ for 24 hours to promote the full migration and film formation of the surface treatment agent. The bottles were longitudinally cut open, and the flat area in the middle of the bottle was taken as the sample.

[0051] Test method: Using a contact angle measuring instrument (test environment 23±2℃, 50%±5%RH), 3μL of deionized water was dropped onto the inner wall of the sample (the surface in contact with the contents). After the liquid stabilized for 30 seconds, the static contact angle was measured using the seat drop method. Five bottles were tested in each group, and three positions were measured for each bottle. The average value was taken.

[0052] Test 4: Stability test of contents of the packaging bottle Sample preparation: The color masterbatch, antioxidant 1010 and PP resin (Yanshan Petrochemical K1008, MFR=10-12g / 10min) prepared in the examples and comparative examples were mixed at a mass ratio of 5:0.2:94.8 and then injection molded into cosmetic packaging bottles (capacity 100mL, wall thickness 1.5mm) at an injection temperature of 200±5℃.

[0053] Test method: A simulated alcohol-containing cosmetic solution was prepared using a mixture of 10% ethanol, 2% Tween-80, 1% citric acid, and 87% deionized water. After cleaning and drying the packaging bottle, the simulated solution was filled, sealed, and placed in an aging test chamber. The chamber was irradiated with ultraviolet light (340nm, irradiance 0.68W / m²) at a temperature of 40±2℃, humidity of 75%±5%RH, and 340nm. 2 The sample was aged for 90 days under a light / dark cycle of 8h / 4h. Samples were taken at 0, 15, 30, 60, and 90 days. 10 mL of the contents were transferred to a colorless, transparent glass tube, and the absorbance was measured using a UV-Vis spectrophotometer (measurement wavelength 420 nm). The color difference was measured using a colorimeter, and the yellowing index (YI) was recorded.

[0054] Table 2 Results of stability test of contents in packaging bottles

[0055] Analysis of experimental results: Compared to Example 1, Example 4 (the surface treatment agent was prepared from low-viscosity hydrogen-containing silicone oil) performed worse in terms of water contact angle and yellowing inhibition index. This indicates that the viscosity (molecular weight) of the polysiloxane segments in the surface treatment agent is a key variable affecting film-forming performance. The reason may be that when the viscosity of the hydrogen-containing silicone oil is too low, the polysiloxane segments are too short, leading to an excessively fast migration rate of the surface treatment agent in the polypropylene matrix, resulting in poor long-term effectiveness. In the later stages of aging, it cannot effectively block the penetration of polar small molecules, significantly increasing oxidative yellowing. Furthermore, the density and hydrophobicity of the precipitated surface barrier layer decrease.

[0056] Example 5 (the surface treatment agent was prepared from high-viscosity hydrogen-containing silicone oil) also showed poor performance in inhibiting yellowing during the early stages of aging. This may be because when the viscosity of the hydrogen-containing silicone oil is too high, the molecular chains of the surface treatment agent become too long, severely hindering its migration and diffusion rate within the polypropylene matrix. This prevents it from fully and uniformly migrating to the surface of the packaging bottle during the early stages of aging, resulting in insufficient coverage or decreased density of the hydrophobic barrier layer, thus affecting its barrier effect.

[0057] Compared to Example 1, Example 6 (carboxyl-modified polypropylene without styrene copolymerization) showed poorer performance in terms of dispersibility and color difference. This indicates that the introduction of styrene segments has a positive effect on improving the overall performance of the system. This may be because styrene segments contain π-electron systems, which can generate π-π interactions with the conjugated structure of phthalocyanine pigments. This interaction effectively inhibits the agglomeration of high-concentration pigments during melt processing, thus improving dispersion uniformity.

[0058] Compared to Example 1, Comparative Example 1 (without unsaturated silane coupling agent in the surface treatment agent) showed deterioration in all indicators, including contact angle and yellowing inhibition. This indicates that the unsaturated silane coupling agent is an indispensable component for the surface treatment agent to exert its barrier effect. This may be because the siloxane groups in the silane coupling agent are key to the surface treatment agent's ability to hydrolyze and self-condense, forming a dense and durable hydrophobic network on the bottle surface. Without this component, the surface treatment agent can only function as an internal lubricant or perform simple physical migration, failing to form a chemically cross-linked stable barrier layer. Therefore, the barrier effect against polar small molecules is essentially lost, leading to significant antioxidant migration and severe yellowing of the contents.

[0059] Comparative Example 2 (without α-olefin in the surface treatment agent) performed poorly in terms of contact angle and yellowing inhibition. This may be because the long-chain alkyl group of the α-olefin imparts good compatibility with the polypropylene matrix, allowing for uniform dispersion and controllable migration. Without the α-olefin, the surface treatment agent, composed of polysiloxane segments and silane coupling agents, has extremely poor compatibility with the PP matrix. During high-temperature processing, phase separation and rapid migration may occur, resulting in an uneven, unstable, and poorly lasting surface film structure. Furthermore, the polarity difference may expose hydrophilic groups, reducing the hydrophobic effect and failing to provide effective barrier properties.

[0060] Comparative Example 3 (using hydroxyl-modified polypropylene instead of carboxyl-modified polypropylene) performed poorly in terms of dispersibility, color difference, and inhibition of late-stage yellowing. This may be because carboxyl groups not only improve the compatibility of PP with phthalocyanine pigments through hydrogen bonding, but also form coordination networks with phthalocyanine pigments (such as copper ions in phthalocyanine blue). This strong interfacial interaction can more effectively anchor the pigment and effectively regulate the migration rate of the surface treatment agent, achieving a certain long-term sustained-release effect. While the polarity of hydroxyl groups can also improve compatibility, they cannot form coordination bonds.

[0061] Comparative Example 4 (using the azo pigment Permanent Red instead of phthalocyanine pigments) showed significant deterioration in dispersibility, color difference, and inhibition of late-stage yellowing. This indicates that the technical solution of this application has specific selectivity for pigment type. This may be because phthalocyanine pigments possess excellent thermal stability and a planar large π-conjugated structure. In this application, the carboxyl-modified polypropylene can coordinate with the pigment center metal through the carboxyl group and also interact with the pigment through π-π interactions via the styrene segments. Azo pigments, however, have a different structure, lacking a metal center capable of forming strong coordination with the carboxyl group, and their π-π interaction with styrene is also weaker. Therefore, their dispersibility in the polypropylene matrix decreases, especially at high pigment loadings, easily leading to aggregation and resulting in color spots and color difference problems. Furthermore, the lack of a coordination network leads to an increased migration rate of the surface treatment agent.

[0062] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A polypropylene masterbatch, characterized in that, The raw materials include the following parts by weight: The mixture comprises 100 parts of carboxyl-modified polypropylene, 15-25 parts of phthalocyanine pigment, 2-5 parts of lubricant, 1-2 parts of antioxidant, and 5-8 parts of surface treatment agent; the surface treatment agent is prepared by hydrosilylation of α-olefin, unsaturated silane coupling agent, and hydrogen-containing silicone oil having at least two silane groups, wherein the molar ratio of silane groups in the α-olefin, unsaturated silane coupling agent, and hydrogen-containing silicone oil is 0.4-0.8:0.3-0.6:

1.

2. The polypropylene masterbatch according to claim 1, characterized in that, The α-olefin has 8 to 16 carbon atoms.

3. The polypropylene masterbatch according to claim 1, characterized in that, The viscosity of the hydrogen-containing silicone oil is 30-100 mm. 2 / s.

4. The polypropylene masterbatch according to claim 1, characterized in that, The unsaturated silane coupling is a methacryloyloxysilane coupling agent and / or a vinylsilane coupling agent.

5. The polypropylene masterbatch according to claim 1, characterized in that, The carboxyl-modified polypropylene is obtained by free radical copolymerization of raw materials containing homopolymer polypropylene and dicarboxylic acid monomer, wherein the mass ratio of homopolymer polypropylene to dicarboxylic acid monomer is 100:1.5-3.

6. The polypropylene masterbatch according to claim 5, characterized in that, The raw material for the carboxyl-modified polypropylene includes styrene, and the mass ratio of homopolymer polypropylene to styrene is 100:1 to 2.

7. The polypropylene masterbatch according to claim 5, characterized in that, The dicarboxylic acid monomer is selected from one or more of maleic acid, itaconic acid, and fumaric acid.

8. The polypropylene masterbatch according to claim 1, characterized in that, The lubricant is polyethylene wax with a melting point of 100-120°C.

9. The polypropylene masterbatch according to claim 1, characterized in that, The antioxidant is a combination of hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of 1:0.5 to 1.

5.

10. The method for preparing polypropylene masterbatch according to any one of claims 1 to 9, characterized in that: Carboxyl-modified polypropylene, phthalocyanine pigment, lubricant, antioxidant, and surface treatment agent are mixed in proportion and granulated by twin-screw extrusion at 190–230°C to obtain color masterbatch.

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