Preparation method and application of polypropylene effect master batch

Abstract

The invention relates to a preparation method and application of a polypropylene effect master batch, the polypropylene effect master batch can be used for preparing a spraying-free polypropylene product, a special flow line effect is brought through one-time injection molding, and the appearance effect of the product is improved. The polypropylene effect master batch is prepared through a skin-core co-extrusion process and has a skin-core structure, and the skin-core structure resin raw materials comprise an ethylene-trifluorochlor oethylene copolymer, polypropylene random copolymer, a pigment dispersing aid, a pigment, an antioxidant and a lubricant; the core layer structure resin is prepared from the following raw materials: poly (4-methyl-1-pentene), polypropylene random copolymer, ethylene acrylic acid copolymer, pigment, antioxidant and lubricant. By controlling the skin-core structure of the polypropylene effect master batch, the polypropylene effect master batch and the polypropylene resin are subjected to cold mixing and injection molding in proportion, and the spraying-free polypropylene product with the special flow line effect can be prepared.

Description

Technical Field

[0001] This invention relates to a method for preparing a polypropylene effect masterbatch with a "skin-core" structure. Background Technology

[0002] Polypropylene resin, as one of the five major general-purpose resins, is one of the polymer materials with the largest production, consumption, and application fields in the world today. Polypropylene has advantages such as low density, high strength, heat resistance, good insulation, low dielectric constant, low dielectric loss, low price, and excellent chemical stability, making it highly favored in home appliances, automobiles, electronics, medical devices, and other fields.

[0003] Existing polypropylene materials can be colored with pigments to achieve different appearance colors, but traditional pigment coloring results in products with only a single, uniform color tone, which cannot meet the requirements of personalized appearance design. Therefore, to create rich flow patterns on the surface of the parts and enhance the artistic effect of the products, secondary processing is required, which increases the production cycle and production costs.

[0004] The introduction of paint-free finishes has largely solved the problems of complex processes and environmental pollution associated with traditional painting, while also offering significant cost advantages. The flow texture effect allows for personalized, print-free designs, providing both a glossy surface and varying levels of textural depth, thus enhancing the artistic appeal of the product.

[0005] Traditional polypropylene flow texture effects often use nylon or polyester as carrier resins in masterbatches. However, nylon or polyester resins are polar resins and have poor compatibility with polypropylene resins. This results in poor interfacial forces between the flow texture layer and the matrix resin layer, which affects the performance of the final part. At the same time, nylon or polyester resins have low light transmittance, and when they encapsulate pigments, they can easily block the color of the pigments, thus affecting the color richness of the flow texture.

[0006] Conventional polypropylene flow pattern masterbatches are usually a single color. If two colors of flow pattern are to be prepared, two different colors of flow pattern masterbatches need to be prepared separately and then cold-mixed for injection molding, which makes the preparation process complicated. At the same time, if the two colors of flow pattern masterbatches are not well integrated during injection molding, the color layering of the part will be poor, resulting in some areas of flow pattern being one color and other areas of flow pattern being another color.

[0007] Patent CN112745665B describes the preparation of flow pattern masterbatch for polypropylene materials using PA6, HDPE, styrene-based elastomers, and pigments. However, the PA6 used in this invention has poor compatibility with polypropylene, which affects the final performance of the material. Furthermore, the poor light transmittance of PA6 and HDPE resins can easily mask the pigment colors, thus affecting the final color effect.

[0008] Patent CN103724926A describes the preparation of effect masterbatch by coating effect pigments with thermosetting resin. The preparation method of this masterbatch is complicated, requiring the effect pigments to be cured at high temperature. At the same time, thermosetting resin cannot be plasticized at high temperature, which can easily cause defects such as pitting on the surface of the part during injection molding.

[0009] Patent CN109135061A describes the preparation of polypropylene flow pattern masterbatch using PA66, PP, MAH-g-PP, and inorganic pigments. However, PA66 is a milky white material with poor light transmittance, which can easily cover the pigment color and affect the final color effect.

[0010] The masterbatch for the flow pattern in the above three patents is a single color, which cannot achieve the flow pattern effect of two colors.

[0011] Therefore, it is necessary to develop a polypropylene effect masterbatch with good compatibility with polypropylene and rich flow pattern colors to solve the technical shortcomings of existing materials. Summary of the Invention

[0012] The purpose of this invention is to address the shortcomings of existing technologies by providing a polypropylene effect masterbatch with good compatibility with polypropylene and rich flow pattern colors.

[0013] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0014] A polypropylene effective masterbatch has a "skin-core" double-layer structure, comprising a skin structure resin and a core structure resin. The skin structure resin accounts for 30-50% of the weight of the polypropylene effective masterbatch, and the core structure resin accounts for 50-70% of the weight of the polypropylene effective masterbatch; wherein,

[0015] The skin structure resin comprises the following parts by weight of raw materials:

[0016] Ethylene-chlorotrifluoroethylene copolymer: 50-80 parts;

[0017] Random copolymer polypropylene: 10-20 parts;

[0018] Pigment dispersing agent: 5-10 parts

[0019] Pigment: 2-20 parts;

[0020] Antioxidant: 0.5-1 part;

[0021] Lubricant: 0.5-2 parts;

[0022] The core structure resin comprises the following parts by weight of raw materials:

[0023] Poly(4-methyl-1-pentene): 45-85 parts;

[0024] Random copolymer polypropylene: 10-20 parts;

[0025] Ethylene-acrylic acid copolymer: 5-10 parts;

[0026] Pigment: 2-20 parts;

[0027] Antioxidant: 0.5-1 part;

[0028] Lubricant: 0.5-2 parts.

[0029] In the skin structure resin of this invention, the melting temperature of the ethylene-trifluorochloroethylene copolymer is 240-250℃, its melt index is 5-20g / 10min, and the test conditions are 275℃ / 2.16kg.

[0030] In the skin structure resin of this invention, the random copolymer polypropylene has a melting temperature of 130-155℃, a melt index of 5-20g / 10min, and is tested under the conditions of 230℃ / 2.16kg.

[0031] In the skin-structured resin of this invention, the pigment dispersing aid has the following structure:

[0032]

[0033] In one specific implementation scheme, the preparation method is as follows:

[0034] (1) Dissolve 10g of citric acid in 100g of tetrahydrofuran to prepare solution 1; dissolve 25g of perfluorooctyl ethanol in 100g of tetrahydrofuran to prepare solution 2; dissolve 11g of terephthaloyl chloride in 100g of tetrahydrofuran to prepare solution 3;

[0035] (2) Under stirring at room temperature, solution 1 was added dropwise to solution 3 within 30 min. After stirring and reacting for 2 h, solution 2 was added dropwise to solution 3 within 30 min. The temperature was raised to 60℃ and stirring was continued for 2 h. The solution was then desolventized under vacuum to obtain a biblock pigment dispersing agent.

[0036]

[0037] In the skin structure resin of the present invention, the pigment is any one or more mixtures of inorganic pigments and metallic effect pigments. For example, inorganic pigments include titanium dioxide, zinc sulfide, zinc barium white, carbon black, ultramarine, titanium yellow, iron oxide red and other metal oxide pigments, and metallic effect pigments include aluminum powder, copper powder, gold powder, silver powder, zinc aluminum alloy powder and pearlescent powder.

[0038] In the skin structure resin of the present invention, the antioxidant is any one or more of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants.

[0039] In the skin structure resin of the present invention, the lubricant is any one or more of zinc stearate, ethylene bis-stearamide, and oxidized polyethylene wax.

[0040] In the core layer structure resin of this invention, the melting temperature of poly4-methyl-1-pentene is 230-240℃, its melt index is 5-30g / 10min, and the test conditions are 260℃ / 5kg.

[0041] In the core layer structure resin of this invention, the random copolymer polypropylene has a melting temperature of 130-155℃, a melt index of 5-20g / 10min, and is tested under the conditions of 230℃ / 2.16kg.

[0042] In the core layer structure resin of this invention, the ethylene-acrylic acid copolymer has a melt index of 5-20 g / 10 min (190℃, 2.16 kg) and an acrylic acid content of 9-22%.

[0043] In the core layer structure resin of this invention, the pigment is any one or more mixtures of inorganic pigments and metallic effect pigments. For example, inorganic pigments include titanium dioxide, zinc sulfide, zinc barium white, carbon black, ultramarine, titanium yellow, iron oxide red and other metal oxide pigments, and metallic effect pigments include aluminum powder, copper powder, gold powder, silver powder, zinc aluminum alloy powder and pearlescent powder.

[0044] In the core layer structure resin of the present invention, the antioxidant is any one or more of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants.

[0045] In the core layer structure resin of the present invention, the lubricant is any one or more of zinc stearate, ethylene bis-stearamide, and oxidized polyethylene wax.

[0046] In this invention, the polypropylene masterbatch includes the following steps:

[0047] (1) The raw material of the skin layer is placed in a high-speed mixer and mixed thoroughly for 3-5 minutes. Then, it is subjected to high-temperature melt dispersion, extrusion, and granulation through a twin-screw extruder to obtain the skin layer resin.

[0048] (2) The core layer raw material is placed in a high-speed mixer and mixed thoroughly for 3-5 minutes. Then, it is subjected to high-temperature melt dispersion, extrusion, and granulation through a twin-screw extruder to obtain the core layer resin.

[0049] (3) The skin resin and core resin are plasticized in two single-screw extruders and then granulated through a co-extrusion die to obtain polypropylene effective masterbatch with a skin-core structure. The skin resin accounts for 30-50% of the total mass of the polypropylene effective masterbatch, and the core resin accounts for 50-70% of the total mass of the polypropylene effective masterbatch.

[0050] In this invention, the twin-screw extruder in steps (1) and (2) has a screw length-to-diameter ratio of (40-52):1, a screw speed of 200-400 r / min, and an extrusion temperature of 250-260℃.

[0051] In this invention, the screw length-to-diameter ratio of the single screw extruder in step (3) is (25-35):1, the screw speed is 200-400 r / min, and the extrusion temperature is 250-260℃.

[0052] The technical solution of this invention has the following advantages over existing technical solutions:

[0053] (1) The polypropylene effect masterbatch in this invention adopts a skin-core structure. When the skin resin and the core resin are made of different colored pigments, the flow texture appearance of two colors can be achieved after cold mixing and injection molding with polypropylene.

[0054] (2) The polypropylene effect masterbatch in this invention adopts a core-skin structure. The skin resin is an ethylene-chlorotrifluoroethylene copolymer with a high melting temperature, which has low surface energy and good transparency. During the flow process, it easily flows to the surface of the polypropylene substrate, making the substrate surface better reflect the flow pattern effect. By adding an appropriate amount of random copolymer polypropylene, whose melting temperature is lower than that of ethylene-chlorotrifluoroethylene copolymer, it preferentially melts and plasticizes during injection molding, playing an internal plasticizing role. This avoids the problem of color agglomeration caused by the skin resin not being plasticized due to excessively high melting temperature, thus preventing the flow pattern effect from being achieved. At the same time, random copolymer polypropylene has excellent transparency and will not cover the effect performance of pigments. Meanwhile, due to the low surface polarity caused by fluorine, ethylene-chlorotrifluoroethylene copolymer has poor wetting and dispersion of inorganic pigments. By adding pigment dispersing aids, the polar and non-polar biblock structures contained therein are beneficial to the dispersion of inorganic pigments in ethylene-chlorotrifluoroethylene copolymer, thereby improving the color effect performance of pigments.

[0055] (3) The polypropylene effect masterbatch in this invention adopts a core-skin structure. The core layer uses poly(4-methyl-1-pentene) with a high melting temperature, which has excellent transparency and will not obscure the effect of the pigment. By adding an appropriate amount of random copolymer polypropylene, whose melting temperature is lower than that of poly(4-methyl-1-pentene), it preferentially melts and plasticizes during injection molding, playing an internal plasticizing role. This avoids the problem of color agglomeration caused by the core resin not being able to plasticize due to excessively high melting temperature, thus preventing the flow texture effect from being achieved. At the same time, adding an appropriate amount of ethylene-acrylic acid copolymer is beneficial to the dispersion of inorganic pigments in the matrix resin, thereby improving the color effect of the pigment.

[0056] (4) The polypropylene masterbatch in this invention adopts a skin-core structure. The skin resin and the core resin are two resins with certain differences in polarity, which can avoid the problem of color mixing of the two colors of the flow pattern during the flow process. At the same time, the polarity of the skin resin is different from that of the cold-mixed polypropylene resin, which makes the flow pattern less likely to melt into the base material and avoids the phenomenon of color mixing in the base material. Detailed Implementation

[0057] To better understand the technical solution of the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments. Unless otherwise specified, the raw materials used in the embodiments or comparative examples are commercially available raw materials.

[0058] The apparatus and main raw material sources used in the embodiments and comparative examples of this invention are as follows:

[0059] Twin-screw extruder: Model SK-26, screw length-to-diameter ratio 50:1; Nanjing Keya Chemical Complete Equipment Co., Ltd.

[0060] Single-screw co-extrusion equipment: Model HRJSJ-35, screw length-to-diameter ratio 28:1, Foshan Hairuijia Precision Extrusion Machinery Co., Ltd.;

[0061] Ethylene-chlorotrifluoroethylene copolymer: 930LCW, melting temperature 242℃, melt index 7g / 10min, test method 275℃, 2.16kg, Sowell Group;

[0062] Random copolymer polypropylene: FL7540L, melt temperature 138℃, melt index 7g / 10min, test method 230℃, 2.16kg, Singapore Polyolefins Ltd.;

[0063] Poly(4-methyl-1-pentene): RT31XB, melting temperature 232℃, melt index 21g / 10min, test method 260℃, 5kg;

[0064] Ethylene-acrylic acid copolymer: EAA3004, acrylic acid content 9.7%, melt index 8.5 g / 10 min (190℃, 2.16 kg);

[0065] Inorganic blue pigment: Ultramarine EP-19, Fulu Pigment Co., Ltd.;

[0066] Inorganic red pigment: Iron Red 110M, Bayer GmbH, Germany;

[0067] Main antioxidant: 1010, from a rising star in chemistry;

[0068] Co-antioxidant: 168, a rising star in chemistry;

[0069] Lubricant: Zinc stearate, FARKS GmbH, Italy;

[0070] Polypropylene matrix resin: PP6012, melt temperature 165℃, melt index 12g / 10min, test method 230℃, 2.16kg, China Petroleum & Chemical Corporation;

[0071] All other raw materials were commercially available and of analytical grade.

[0072] The performance characterization method of the polypropylene material of the present invention is as follows:

[0073] Evaluation of flow pattern effect: After cold mixing 5 parts of polypropylene masterbatch with 95 parts of polypropylene matrix resin PP6012, the mixture was placed in an injection molding machine and injection molded at 240℃. The quality of the flow pattern effect was visually confirmed. A good flow pattern effect means that the masterbatch is naturally distributed on the surface of the base material without large particles or agglomerates on the surface, and the masterbatch is not completely melted into the base material, causing a significant change in the base material's base color. A poor flow pattern effect means that the masterbatch consists of relatively large particles or agglomerates on the surface of the base material, or the masterbatch is completely melted into the base material, significantly affecting the base material's base color.

[0074] Example 1

[0075] The preparation method of pigment dispersing aid is as follows:

[0076] (1) Dissolve 10g of citric acid in 100g of tetrahydrofuran to prepare solution 1; dissolve 25g of perfluorooctyl ethanol in 100g of tetrahydrofuran to prepare solution 2; dissolve 11g of terephthaloyl chloride in 100g of tetrahydrofuran to prepare solution 3;

[0077] (2) Under stirring at room temperature, solution 1 was added dropwise to solution 3 within 30 min. After stirring and reacting for 2 h, solution 2 was added dropwise to solution 3 within 30 min. The temperature was raised to 60 °C and stirring was continued for 2 h. The solution was then desolventized under vacuum to obtain a biblock pigment dispersing agent.

[0078] Examples 2-6 and Comparative Examples 1-8

[0079] Examples 2-6 (i.e., S2-6) and Comparative Examples 1-8 (i.e., D1-8) were prepared according to the raw materials and dosages in Table 1 to produce polypropylene masterbatches.

[0080] The preparation method of the cortex resin is as follows: weigh each raw material according to the weight parts in the table, then put them into a high-speed mixer and mix for 3 minutes. Then feed them into the main feed port of a twin-screw extruder. The screw speed is 300 r / min and the extrusion temperature is 250℃. After high-temperature melting and dispersion, the cortex resin is obtained by extrusion granulation.

[0081] The preparation method of the core layer resin is as follows: weigh each raw material according to the weight parts in the table, then put them into a high-speed mixer and mix for 3 minutes. Then feed them from the main feed port of the twin-screw extruder. The screw speed is 300 r / min and the extrusion temperature is 250℃. After high-temperature melting and dispersion, the core layer resin is obtained by extrusion granulation.

[0082] The preparation method of polypropylene effect masterbatch is as follows: According to the proportions in the table, the skin layer resin and the core layer resin are placed in two single-screw extruders for plasticization. The plasticization temperature is 250℃ and the screw speed is 300r / min. The polypropylene effect masterbatch with skin and core structure is obtained by stretching and pelletizing through a co-extrusion die.

[0083] Table 1. Raw material usage and properties of Examples 2-6 and Comparative Examples 1-8

[0084]

[0085]

[0086] Table 1 shows that the polypropylene masterbatches in Examples 2-6 use a core-skin structure. The skin resin consists of ethylene-chlorotrifluoroethylene copolymer, random copolymer polypropylene, pigment dispersant, and inorganic pigments, while the core resin consists of poly(4-methyl-1-pentene), random copolymer polypropylene, ethylene-acrylic acid copolymer, and inorganic pigments. The core and skin resins have differences in polarity and color, which, after cold mixing and injection molding with the matrix resin, form an excellent flow pattern effect.

[0087] Compared to Example 2, Comparative Example 1 has a lower skin mass content than the preferred mass ratio, resulting in an indistinct flow pattern color effect in the skin during injection molding and an inability to form a good two-color flow pattern appearance.

[0088] Compared to Example 2, Comparative Example 2 has a lower core layer mass content than the optimized mass ratio, resulting in an indistinct flow pattern color effect in the core layer during injection molding and an inability to form a good two-color flow pattern appearance.

[0089] Compared to Example 2, Comparative Example 3 did not contain ethylene-chlorotrifluoroethylene copolymer in its skin resin, and during the injection molding process, color bleeding occurred between the skin and the core layer flow lines, and color bleeding occurred between the skin flow lines and the base material.

[0090] Compared to Example 2, Comparative Example 4 did not add random copolymer polypropylene as an internal plasticizer to its skin resin, resulting in excessively high melt strength of the skin resin. During injection molding, the skin resin was not easily plasticized, leading to color agglomeration and large color spots on the substrate surface, resulting in poor flow texture.

[0091] Compared to Example 2, Comparative Example 5 did not have a pigment dispersing agent added to its skin resin, which resulted in poorer dispersion of inorganic pigments in the skin resin and a worse final flow pattern color effect.

[0092] Compared to Example 2, Comparative Example 6 did not contain poly4-methyl-1-pentene in its core resin, resulting in a lower melting temperature and melt strength. This made it prone to color bleeding with the substrate during injection molding, leading to a poor flow pattern effect.

[0093] Compared to Example 2, Comparative Example 7 did not add random copolymer polypropylene as an internal plasticizer to its core layer resin, resulting in excessively high melt strength of the core layer resin. During injection molding, the core layer resin was not easily plasticized, leading to color agglomeration and large color spots on the substrate surface, resulting in poor flow texture effect.

[0094] Compared to Example 2, Comparative Example 8 did not contain ethylene-acrylic acid copolymer in its core resin, resulting in poorer dispersion of inorganic pigments and a deterioration in the final flow pattern color effect.

[0095] The above description of the embodiments is intended to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the embodiments and apply the general principles described herein to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A polypropylene masterbatch, characterized in that: It includes a skin structure resin and a core structure resin. The skin structure resin accounts for 30-50% of the weight of the polypropylene effective masterbatch, and the core structure resin accounts for 50-70% of the weight of the polypropylene effective masterbatch; among which, The skin structure resin comprises the following parts by weight of raw materials: Ethylene-chlorotrifluoroethylene copolymer: 50-80 parts; Random copolymer polypropylene: 10-20 parts; Pigment dispersing agent: 5-10 parts Pigment: 2-20 parts; Antioxidant: 0.5-1 part; Lubricant: 0.5-2 parts; The core structure resin comprises the following parts by weight of raw materials: Poly(4-methyl-1-pentene): 45-85 parts; Random copolymer polypropylene: 10-20 parts; Ethylene-acrylic acid copolymer: 5-10 parts; Pigment: 2-20 parts; Antioxidant: 0.5-1 part; Lubricant: 0.5-2 parts.

2. The polypropylene masterbatch according to claim 1, characterized in that, The ethylene-trifluorochloroethylene copolymer has a melting temperature of 240-250℃, a melt index of 5-20g / 10min, and is tested at 275℃ / 2.16kg.

3. The polypropylene masterbatch according to claim 1, characterized in that, The random copolymer polypropylene has a melting temperature of 130-155℃, a melt index of 5-20 g / 10 min, and is tested at 230℃ / 2.16 kg.

4. The polypropylene masterbatch according to claim 1, characterized in that, The structure of the pigment dispersing agent is as follows:

5. The polypropylene masterbatch according to claim 1, characterized in that, The pigments are any one or more mixtures of inorganic pigments and metallic effect pigments. For example, inorganic pigments include titanium dioxide, zinc sulfide, zinc barium white, carbon black, ultramarine, titanium yellow, iron oxide red, and other metal oxide pigments. Metallic effect pigments include aluminum powder, copper powder, gold powder, silver powder, zinc-aluminum alloy powder, and pearlescent powder.

6. The polypropylene masterbatch according to claim 1, characterized in that, The antioxidant is any one or more of hindered phenolic antioxidants, phosphite antioxidants, and thioester antioxidants.

7. The polypropylene masterbatch according to claim 1, characterized in that, The lubricant is any one or more of zinc stearate, ethylene bis-stearamide, and oxidized polyethylene wax.

8. The polypropylene masterbatch according to claim 1, characterized in that, The melting temperature of the poly(4-methyl-1-pentene) is 230-240℃, the melt index is 5-30 g / 10 min, and the test method is 260℃ / 5 kg.

9. The polypropylene masterbatch according to claim 1, characterized in that, The ethylene-acrylic acid copolymer has a melt index of 5-20 g / 10 min, is tested at 190℃ / 2.16 kg, and has an acrylic acid content of 9-22%.

10. A polypropylene masterbatch according to any one of claims 1-9, the preparation method of which comprises the following steps: (1) Place the raw material of the skin layer in a high-speed mixer, mix thoroughly for 3-5 minutes, and then use a twin-screw extruder for high-temperature melt dispersion, extrusion, and granulation to obtain the skin layer resin; (2) Place the core layer raw material in a high-speed mixer, mix thoroughly for 3-5 minutes, and then use a twin-screw extruder for high-temperature melt dispersion, extrusion, and granulation to obtain the core layer resin. (3) The skin resin and core resin are plasticized in two single-screw extruders and then granulated by co-extrusion die to obtain polypropylene masterbatch with skin and core structure.

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