Colored wrapping film and preparation method thereof
By using the melt co-extrusion technology of ethylene-vinyl acetate copolymer, stearate and non-ionic surfactant with polypropylene masterbatch in colored stretch film, the problems of reduced strength of dark stretch film and low classification and marking efficiency are solved, and the high strength and uniformity of colored stretch film are achieved.
Patent Information
- Application Number
- CN202511084041.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-04
- Publication Date
- 2025-09-19
AI Technical Summary
The inorganic pigments in the existing colored stretch films are easily agglomerated in dark stretch films, resulting in reduced strength, and there is a lack of effective classification and identification, resulting in low efficiency.
The masterbatch mixture is prepared by melt co-extrusion of ethylene-vinyl acetate copolymer, stearate and non-ionic surfactant with polypropylene masterbatch, and the surface porosity is formed by adding a pore-forming agent. The masterbatch mixture and the mixture of ethylene-vinyl acetate copolymer, stearate, non-ionic surfactant and pore-forming agent improve the dispersibility and compatibility of inorganic pigments in the homogeneous system to form a uniform colored stretch film.
The prepared colored stretch film significantly improves strength and dispersibility while maintaining excellent coloring effect, and is suitable for large-scale production.
Smart Images
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of stretch films, and more specifically, to a colored stretch film and a preparation method thereof. Background Art
[0002] Stretch film is a thin film made primarily from linear low-density polyethylene (LLDPE) through a three-layer co-extrusion cast film process. This material features high transparency, high longitudinal elongation, a high yield point, high transverse tear strength, and excellent puncture resistance. Therefore, it is widely used in pallet packaging and group packaging. This packaging method effectively protects against moisture and dust, reduces manual labor, improves efficiency, and reduces packaging costs. Whether used for food, electronic devices, or other sensitive goods, stretch film provides reliable protection.
[0003] However, early stretch films were mostly transparent and lacked classification markings. Warehousing and logistics relied on manual labeling to distinguish products, which was inefficient and prone to errors. Although stretch films are now colored by adding masterbatches, they facilitate quick identification of product categories or delivery areas. However, dark-colored stretch films, such as black stretch films, have a high carbon black content and are prone to agglomeration in linear low-density polyethylene, which can reduce the film's strength. Summary of the Invention
[0004] In order to improve the strength of a colored stretch film, the present application provides a colored stretch film and a preparation method thereof.
[0005] In a first aspect, the present application provides a colored stretch film, which adopts the following technical solution: A colored stretch film comprising the following components in parts by weight: 100 parts of mixed material; 40-50 parts of tackifier; 9-20 parts of masterbatch mixture; The preparation method of the masterbatch mixture comprises the following steps: mixing the masterbatch, ethylene-vinyl acetate copolymer, stearate and nonionic surfactant, melt-coextruding and granulating to obtain the masterbatch mixture.
[0006] The masterbatch is mainly composed of inorganic pigments and carrier resin. In this application, the carrier resin is polypropylene, that is, polypropylene masterbatch.
[0007] By employing the above technical solution, when the masterbatch mixture is melt-coextruded with the mixed material and tackifying resin, the masterbatch mixture, the mixed material, and the tackifying resin form a homogeneous system due to the good compatibility of the ethylene-vinyl acetate copolymer and the polypropylene masterbatch. This facilitates the stearate and nonionic surfactant to promote the uniform dispersion of the inorganic pigment in the masterbatch within the homogeneous system, reducing the surface tension of the inorganic pigment in the homogeneous system and improving the stability of the inorganic pigment in the linear low-density polyethylene, thereby achieving a colored stretch film with both color and strength.
[0008] Preferably, the weight ratio of the masterbatch, ethylene-vinyl acetate copolymer, stearate and nonionic surfactant is 1:(0.5-1):(0.16-0.2):(0.06-0.1).
[0009] By adopting the above technical solution, the raw materials are mixed according to the above weight proportions to prepare a masterbatch mixture, which has both excellent coloring effect and compatibility, good coloring and dispersibility in the mixture and tackifying resin, and the prepared colored stretch film has uniform color and excellent strength.
[0010] Preferably, the stearate is magnesium stearate.
[0011] By adopting the above technical solution, magnesium stearate has good dispersibility, which can improve the dispersibility and fluidity of inorganic pigments in masterbatch. The final colored stretch film is not only uniform in color but also high in strength.
[0012] Preferably, the nonionic surfactant is polyoxyethylene fatty acid ester.
[0013] By adopting the above technical solution, fatty acid polyoxyethylene ester has good dispersibility, lubrication and compatibilization properties in the masterbatch and ethylene-vinyl acetate copolymer blending system. Through interface modification, processing optimization and compatibility adjustment, the dispersibility, compatibility and processing properties of inorganic pigments in the homogeneous system can be improved to obtain a color masterbatch with higher strength.
[0014] Preferably, the masterbatch mixture is prepared by mixing the masterbatch, ethylene-vinyl acetate copolymer, stearate, nonionic surfactant and pore-forming agent, melt-coextruding and granulating to obtain the masterbatch mixture; The pore-forming agent is composed of a mixture of n-hexane and / or ethanol.
[0015] By adopting the above technical solution, n-hexane and / or ethanol will evaporate due to heat during the extrusion process, leaving pores on the surface of the masterbatch mixture, which can increase the contact area between the masterbatch mixture and the mixed material and the tackifying resin, thereby facilitating the dispersion of the masterbatch mixture in the mixed material and the tackifying resin, and further improving the strength of the color masterbatch.
[0016] Preferably, the weight ratio of the masterbatch, ethylene-vinyl acetate copolymer, stearate, nonionic surfactant and pore-forming agent is 1:(0.5-1):(0.16-0.2):(0.06-0.1):(0.03-0.05).
[0017] By adopting the above technical solution and adding the pore-forming agent according to the above weight ratio, the porosity of the masterbatch mixture surface can be adjusted, so that the masterbatch mixture has both strength and dispersibility, and can have good processing performance in the preparation of stretch film.
[0018] Preferably, the pore-forming agent is composed of a mixture of n-hexane and ethanol.
[0019] By adopting this technical solution, n-hexane exhibits good compatibility with polyethylene, while ethanol, due to its high polarity, exhibits excellent compatibility with ethylene-vinyl acetate copolymer. Therefore, using n-hexane and ethanol as pore-forming agents facilitates the formation of uniform micropores on the surface of the masterbatch mixture, increasing the contact area between the mixture and the mixed material and the tackifying resin, further improving the strength of the masterbatch.
[0020] Preferably, the mixture comprises metallocene low-density polyethylene, polyolefin elastomer and linear low-density polyethylene; the density of the linear low-density polyethylene is 0.916-0.920 g / cm 3 , the melt flow rate at 190℃ / 2.16kg is 1.0~2.3g / 10min.
[0021] By adopting the above technical solution, the linear structure of the above linear low-density polyethylene makes its molecular chain arrangement more regular, the intermolecular force is stronger, it has higher tensile strength, and the processing performance of the mixture with the masterbatch is better. The resulting colored stretch film has both excellent color and strength.
[0022] In a second aspect, the present application provides a method for preparing a colored stretch film, which adopts the following technical solution: A method for preparing a colored stretch film comprises the following steps: S1: mixing metallocene low-density polyethylene, polyolefin elastomer and linear low-density polyethylene to obtain a mixture; S2: After the mixed material, tackifier and modified masterbatch are plasticized and mixed, the mixed material is cast into a film, cooled and wound to obtain a colored stretch film.
[0023] By employing this technical solution, the mixture, tackifier, and modified masterbatch are plasticized and mixed to form a homogeneous melt with uniformity and fluidity, which facilitates the dispersion of inorganic pigments. This melt is then tape-cast to produce a stretch film with both excellent color and strength.
[0024] In summary, this application has the following beneficial effects: 1. Since the present application uses ethylene-vinyl acetate copolymer, stearate, nonionic surfactant and polypropylene masterbatch to melt-blend the masterbatch mixture to prepare the masterbatch mixture, the compatibility of the masterbatch mixture in the mixture and the tackifying resin can be improved, and the inorganic pigment can be evenly dispersed in the homogeneous system, thereby obtaining a colored stretch film with both color and strength; 2. In the masterbatch mixture of the present application, by adding a pore-forming agent, a masterbatch mixture with pores on the surface is obtained, which has a wide contact area with the mixture and the tackifying resin, facilitates the dispersion of the masterbatch mixture in the mixture and the tackifying resin, and further improves the strength of the masterbatch; 3. The method of the present application is simple in preparation and suitable for large-scale production. DETAILED DESCRIPTION
[0025] The present application is further described in detail below with reference to the embodiments.
[0026] Preparation Example Preparation Example 1 A masterbatch mixture, the components and their corresponding weight (kg) are shown in the following table.
[0027] The masterbatch mixture is prepared by mixing the masterbatch, ethylene vinyl acetate copolymer, stearate and nonionic surfactant, melt-coextruding at 120° C., granulating and cooling to obtain the masterbatch mixture.
[0028] In the preparation example of this application, the masterbatch is a polypropylene masterbatch, which is black, brand 1, and purchased from Hebei Xiong'an Xinyu Technology Co., Ltd. Ethylene vinyl acetate copolymer, brand ARLANXEO, grade 400, purchased from Shanghai Oushuo Plastics Co., Ltd. Stearate is magnesium stearate; The nonionic surfactant is fatty acid polyoxyethylene ester, the brand is Chenrun Chemical, and the grade is A-115.
[0029] Preparation Examples 2-3 A masterbatch mixture is different from that of Preparation Example 1 in that the components and their corresponding weights (kg) are shown in the following table.
[0030] Preparation Example 4 A masterbatch mixture is provided, which is different from the one prepared in Preparation Example 1 in that the nonionic surfactant is lauric acid diethanolamide.
[0031] Preparation Examples 5 to 7 A masterbatch mixture is different from that of Preparation Example 1 in that the components and their corresponding weights (kg) are shown in the following table.
[0032] The preparation method of the masterbatch mixture is as follows: after mixing the masterbatch, ethylene vinyl acetate copolymer, stearate, nonionic surfactant and pore-forming agent, melt co-extrude at 120° C., granulate and cool to obtain the masterbatch mixture.
[0033] In the preparation example of the present application, the pore-forming agent is composed of a mixture of n-hexane and ethanol in a weight ratio of 1:2.
[0034] Preparation Example 8 A masterbatch mixture is different from that of Preparation Example 4 in that the pore-forming agent is n-hexane.
[0035] Preparation Example 9 A masterbatch mixture is different from that of Preparation Example 4 in that the pore-forming agent is ethanol.
[0036] Preparation Example 10 A masterbatch mixture is different from that of Preparation Example 4 in that the pore-forming agent is sodium bicarbonate.
[0037] Preparation Example 11 A masterbatch mixture is prepared, which differs from Preparation Example 1 in that an equal weight of polyethylene wax-9038A is used instead of stearate.
[0038] Preparation Example 12 A masterbatch mixture is prepared, which differs from Preparation Example 1 in that an equal amount of anionic surfactant Mersolat H95 from Lanxess is used in place of the nonionic surfactant.
[0039] The tensile strength and elongation at break of the colored stretch films prepared in the examples and comparative examples of the present application were tested using the following methods: Tensile strength: Tested in accordance with GB / T1040.3.
[0040] Elongation at break: Tested in accordance with BB / T0024-2004. Example
[0041] Example 1 A kind of colored stretch film, the components and their corresponding weight (kg) are shown in the following table.
[0042] The method for preparing the above-mentioned colored stretch film includes the following steps S1: adding metallocene low-density polyethylene, polyolefin elastomer and linear low-density polyethylene into a screw extruder B and stirring and mixing them to obtain a mixture; adding the masterbatch mixture into the screw extruder B and stirring and mixing them to obtain a mixture containing the masterbatch mixture.
[0043] The stirring speed of screw extruder B is 50 r / min; In the embodiment of the present application, the metallocene low-density polyethylene brand is ExxonMobil 3518CB; the polyolefin elastomer brand is ExxonMobil 6102FL; the linear low-density polyethylene brand is Zhenhai 7042DFDA; The weight ratio of the metallocene low-density polyethylene, the polyolefin elastomer and the linear low-density polyethylene is 1:0.048:1.
[0044] The masterbatch mixture adopts the masterbatch mixture prepared in Preparation Example 1.
[0045] S2: S21: half the weight of the tackifier is added to the screw extruder A for plasticization and melting, then extruded to the distributor, and finally extruded to the left die to obtain the tackifier melt on the left; First, add the remaining tackifier into the screw extruder C for plasticization and melting, then extrude it into the distributor, and finally extrude it into the right die head to obtain the right tackifier melt; In the examples of the present application, the brand of the tackifier is Zeheng ZH101.
[0046] The screw extruder B plasticizes and melts the mixture containing the masterbatch mixture, extrude it to the distributor, and then extrude it to the middle die to obtain the mixture melt; S22: The tackifier melt on the left, the mixed material melt, and the tackifier melt on the right pass through corresponding dies and enter a casting machine at the same time for mixing. The film is then cast into a film, cooled and shaped, and wound to obtain a colored stretch film.
[0047] In the embodiment of the present application, the extrusion speed of the screw extruder A for plasticizing and melting is 60 r / min, and the extrusion temperature is divided into six zones, zone I is 180°C, zone II is 205°C, zone III is 225°C, zone IV is 235°C, zone V is 240°C, and zone VI is 250°C; The screw extruder B has an extrusion speed of 56 r / min for plasticizing and melting, and the extrusion temperature is divided into six zones: zone I is 180°C, zone II is 205°C, zone III is 225°C, zone IV is 235°C, zone V is 240°C, and zone VI is 250°C. The extrusion speed of screw extruder C for plasticizing and melting is 56 r / min, and the extrusion temperature is divided into six zones, zone I is 180°C, zone II is 205°C, zone III is 225°C, zone IV is 235°C, zone V is 240°C, and zone VI is 250°C.
[0048] The temperature of the distributors was 255°C.
[0049] The temperature of the die heads was 255°C.
[0050] The line speed of the casting machine is 28HZ.
[0051] The cooling method is water cooling, and the water temperature is in the range of 25 to 35°C.
[0052] Examples 2 to 10 A colored stretch film, which is different from Example 1 in that the masterbatch mixture is prepared using the preparation example in the following table.
[0053] The tensile strength and elongation at break of the colored stretch films prepared in Examples 1 to 10 of the present application were tested, and the test results are shown in the following table.
[0054] Analysis of the data in the table above shows that the colored stretch films prepared in Examples 1-3 exhibited transverse tensile strengths of 65.1-66.7 MPa, longitudinal tensile strengths of 66.0-67.3 MPa, transverse elongation at break of 760-780%, and longitudinal elongation at break of 659-680%, demonstrating both high tensile strength and elongation. This demonstrates that the masterbatch mixture, comprising masterbatch, ethylene-vinyl acetate copolymer, stearate, and nonionic surfactant in a weight ratio of 1:(2-5):(0.16-0.2):(0.06-0.1), exhibits high strength.
[0055] Compared to the colored stretch film prepared in Example 4, the colored stretch film prepared in Example 1 exhibited significantly higher transverse tensile strength, longitudinal tensile strength, transverse elongation at break, and longitudinal elongation at break than those in Example 4. This indicates that the nonionic surfactant in the masterbatch mixture, which is a fatty acid polyoxyethylene ester, can improve the strength of the colored stretch film, as determined by the total raw materials used in preparing the colored stretch film of the present application.
[0056] The colored stretch films prepared in Examples 5-7 exhibited transverse tensile strengths of 68.8-69.7 MPa, longitudinal tensile strengths of 69.5-70.6 MPa, transverse elongation at break of 800-820%, and longitudinal elongation at break of 698-725%. Compared to the colored stretch films prepared in Examples 1-3, the colored stretch films prepared in Examples 5-7 exhibited significantly higher transverse tensile strength, longitudinal tensile strength, transverse elongation at break, and longitudinal elongation at break than those in Examples 1-3. This demonstrates that the masterbatch mixture, in the raw materials used to prepare the colored stretch films of this application, contains pores on its surface, which improves the strength of the films.
[0057] Compared to the color stretch film prepared in Example 5, the color stretch films prepared in Examples 8, 9, and 10 all showed decreased transverse tensile strength, longitudinal tensile strength, transverse elongation at break, and longitudinal elongation at break. This indicates that, in the preparation of the color stretch film of the present application, the pore-forming agent is a mixture of n-hexane and / or ethanol, and in particular, a mixture of n-hexane and ethanol can improve the strength of the color stretch film.
[0058] Examples 11-12 A colored stretch film, which is different from Example 1 in that the components and their corresponding weights (kg) are shown in the following table.
[0059] The tensile strength and elongation at break of the colored stretch films prepared in Examples 11 and 12 of the present application were tested, and the test results are shown in the following table.
[0060] Analysis of the data in the table above shows that the colored wrapping films prepared in Examples 1-3 exhibited transverse tensile strengths of 65.1-66.7 MPa, longitudinal tensile strengths of 66.0-67.3 MPa, transverse elongation at break of 760-780%, and longitudinal elongation at break of 659-680%, demonstrating both high tensile strength and elongation. This demonstrates that, among the total raw materials used in preparing the colored wrapping films of this application, a colored wrapping film made from a mixture of 100 parts mixed material, 40-50 parts tackifier, and 9-20 parts masterbatch exhibits high strength.
[0061] Comparative Example Comparative Examples 1-2 A colored stretch film, which is different from Example 1 in that the masterbatch mixture is prepared using the preparation example in the following table. Group Preparation example of masterbatch mixture Example 1 Preparation Example 1 Comparative Example 1 Preparation Example 11 Comparative Example 2 Preparation Example 12
[0062] The tensile strength and elongation at break of the colored stretch films prepared in Comparative Examples 1 and 2 of the present application were tested, and the test results are shown in the following table.
[0063] Analysis of the data in the table above reveals that the transverse tensile strength, longitudinal tensile strength, transverse elongation at break, and longitudinal elongation at break of the color stretch film prepared in Comparative Examples 1 and 2 are significantly lower than those of the color stretch film prepared in Example 1. This demonstrates that, among the total raw materials used in preparing the color stretch film of the present application, a masterbatch mixture comprising a masterbatch, ethylene-vinyl acetate copolymer, stearate, and a nonionic surfactant can improve the strength of the color stretch film.
[0064] Visual inspection of the colored stretch films prepared in this embodiment and the comparative example revealed that the colored stretch films had uniform colors and good light-shielding properties.
[0065] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.
Claims
1. A colored stretch film, characterized in that: The composition comprises the following components in parts by weight: 100 parts of mixed material; 40-50 parts of tackifier; 9-20 parts of masterbatch mixture; The preparation method of the masterbatch mixture comprises the following steps: mixing the masterbatch, ethylene vinyl acetate copolymer, stearate and nonionic surfactant, melt co-extruding and granulating to obtain the masterbatch mixture.
2. The color stretch film according to claim 1, characterized in that: The weight ratio of the masterbatch, ethylene vinyl acetate copolymer, stearate and nonionic surfactant is 1:(0.5-1):(0.16-0.2):(0.06-0.1).
3. The color stretch film according to claim 2, characterized in that: The stearate is magnesium stearate.
4. The color stretch film according to claim 2, characterized in that: The nonionic surfactant is polyoxyethylene fatty acid ester.
5. The color stretch film according to claim 1, characterized in that: The preparation method of the masterbatch mixture is as follows: mixing the masterbatch, ethylene vinyl acetate copolymer, stearate, nonionic surfactant and pore-forming agent, melt co-extruding, and granulating to obtain the masterbatch mixture; The pore-forming agent is composed of a mixture of n-hexane and / or ethanol.
6. The color stretch film according to claim 5, characterized in that: The weight ratio of the masterbatch, ethylene vinyl acetate copolymer, stearate, nonionic surfactant and organic solvent is 1:(0.5-1):(0.16-0.2):(0.06-0.1):(0.03-0.05).
7. The color stretch film according to claim 6, characterized in that: The pore-forming agent is composed of a mixture of normal hexane and ethanol.
8. The colored stretch film according to claim 1, characterized in that: The mixture comprises metallocene low-density polyethylene, polyolefin elastomer and linear low-density polyethylene; the linear low-density polyethylene has a density of 0.916 to 0.920 g / cm³ and a melt flow rate of 1.0 to 2.3 g / 10 min at 190°C / 2.16 kg.
9. The method for preparing the colored stretch film according to any one of claims 1 to 8, characterized in that: The following steps are included The mixed material, tackifier and masterbatch mixture are plasticized and mixed, cast into a film, cooled and rolled up to obtain a colored stretch film.