A recyclable transparent colored composite film and preparation method thereof

Abstract

The present invention provides a recyclable transparent colored composite film and a preparation method thereof, which comprises the following raw materials, by weight: 85-115 parts of a composite polyester polymer, 0.5-3 parts of a nucleating agent, 0.1-1.5 parts of a chain transfer agent, 0.1-0.4 parts of a pigment, and 0.5-2 parts of a stabilizer. The composite film of the present invention has excellent heat resistance, UV aging resistance, recyclability, and mechanical properties, and can maintain bright colors for a long time, and has good application value.

Description

Technical Field

[0001] The invention relates to the field of film materials, and in particular to a recyclable transparent colored composite film and a preparation method thereof. Background Art

[0002] Transparent film is an optical film with high transmittance in the visible light range. With the improvement of people's living standards and the progress of scientific and technological development, the demand for transparent film in many fields is increasing. At present, transparent composite film has been widely used in many fields, mainly used in packaging, optical devices, flexible electronic products, solar cells and other fields, with the advantages of good transparency, good flexibility, strong wear resistance, good antioxidant performance, etc. In the field of packaging, transparent composite film can maintain the freshness of food, extend the shelf life, and improve the competitiveness of products. In the field of optical devices, transparent composite film can improve the transmittance and weather resistance of optical devices. In the field of solar cells, transparent composite film can increase the conversion efficiency of solar cells. However, transparent composite film also has some disadvantages, such as high cost, complex preparation process, and high requirements for materials. In addition, due to the large amount of plastics and other chemical materials used in transparent composite films, there are problems of environmental pollution and waste of resources.

[0003] The patent with application number 202020667629.2 discloses a recyclable high-barrier transparent composite film, including a polyethylene terephthalate layer, a transparent high-barrier polyethylene terephthalate layer and a heat-sealable polyethylene terephthalate layer arranged in sequence from the outside to the inside. The transparent high-barrier polyethylene terephthalate layer is a transparent aluminum oxide layer plated on the polyethylene terephthalate layer. Since the three layers of materials are all of the same material, the above structure can be directly recycled and reused, with almost no pollution to nature, adapting to the inevitable trend of social development. However, the composite film only uses polyethylene terephthalate as the single main material, which makes its crystallization rate slow, the molding process difficult, the molding temperature high, the production cycle long, and the impact performance poor.

[0004] The patent with application number 202111639261.4 discloses a high-toughness, environmentally friendly transparent composite film material and its preparation method, which includes, by weight: 71-138 parts of polyester polymers, 0.1-5 parts of crystallization aids, 0.1-1.5 parts of chain extenders, and 0.1-5 parts of stabilizers. The present invention improves the tear resistance and tensile properties of the composite film, improves the transparency of the composite film and its ability to combine with paper products, and uses hindered phenol antioxidants and phosphite antioxidants to synergistically improve the aging resistance of the composite film and extend the service life of the composite film. However, the temperature resistance of this composite film is poor and it has no color, which limits its use scenarios.

[0005] Therefore, it is particularly important to invent a composite film that is recyclable, heat-resistant, colored and transparent. Summary of the invention

[0006] In view of the existing technical problems, the purpose of the present invention is to provide a recyclable transparent colored composite film and a preparation method thereof, which can effectively improve the mechanical properties of the composite film, and at the same time make the composite film have excellent heat resistance, UV aging resistance and recyclability, so that it can maintain bright colors and smooth surface for a long time, and has good application value.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On one hand, the present invention provides a recyclable transparent colored composite film, which comprises the following raw materials, measured in parts by weight: 85-115 parts of composite polyester polymer, 0.5-3 parts of nucleating agent, 0.1-0.5 parts of pigment and 0.5-2 parts of stabilizer.

[0009] The reaction mechanism and effects of the present invention are as follows:

[0010] 1. The present invention modifies polyvinyl acetate by using trifluoromethylstyrene to introduce fluorine atoms into its structure, thereby avoiding the migration and leakage of ultraviolet absorbers while ensuring high transparency, and having a long-lasting ultraviolet shielding performance, thereby obtaining better heat resistance and ultraviolet aging resistance.

[0011] 2. The composite polyester polymer of the present invention is composed of a mixture of modified polyvinyl acetate, polyethylene terephthalate and polyalkyl terephthalate, which is recyclable, and the prepared composite film can be biodegraded under certain conditions, so that its production is free of environmental protection and sustainable development pressure. However, due to the presence of a thermal degradation process in the preparation process, the molecular weight of the polymer is reduced, the number of terminal carboxyl groups is increased, and the terminal carboxyl groups can form hydrogen bonds in a low-polarity medium, resulting in a reduced crystallization rate, and the generated polymer melt is easy to break, and the film formation is difficult, and the generated film material has high brittleness, low tear strength, and poor mechanical properties. Therefore, the mechanical properties of the polymer melt can be improved by introducing a chain transfer agent and modified polyvinyl acetate. This may be because the introduction of the two can cause the terminal carboxyl groups, hydroxyl groups, and amino groups to react, and the thermally decomposed low molecular weight polymers are repolymerized, forming a "bridging" effect between each small component polymer, thereby increasing the molecular weight of the polymer, thereby increasing the viscosity of the polymer system, improving the melt strength, and improving the tensile properties and tear resistance.

[0012] 3. The present invention adopts 1,5-hexadiene-3,4-diol and sodium bisulfite to synthesize a new type of nucleating agent. After the nucleating agent is copolymerized into a polyester polymer, it exhibits a high degree of heterogeneous nucleation ability in the polyester polymer matrix. Ion aggregation causes more nucleation points, which increases the crystallization rate, thereby increasing the heat deformation temperature and dimensional stability of the composite film.

[0013] 4. The stabilizer used in the present invention is a hindered amine stabilizer, which can make the composite film have better anti-aging performance, effectively resist the damage of ultraviolet rays, and maintain bright colors and smooth surface for a long time. In addition, it also has better anti-fouling performance, can effectively resist the erosion of various stains and pollutants, and further improve the stability of the composite film.

[0014] In some embodiments, the composite polyester polymer is composed of a mixture of modified polyvinyl acetate, polyethylene terephthalate and polyalkylene terephthalate.

[0015] In some embodiments, the mass ratio of the modified polyvinyl acetate, polyethylene terephthalate and polyalkylene terephthalate is (2-10):(70-86):(12-28).

[0016] In some embodiments, the method for preparing the modified polyvinyl acetate comprises the following steps:

[0017] 1. Dissolve polyvinyl acetate in an organic solvent, introduce an inert gas, and heat to 70-80° C. to obtain solution A;

[0018] 2. Add p-trifluoromethylstyrene to solution A, then add initiator and chain transfer agent, introduce inert gas, keep warm at 100-300 kPa and continue the reaction for 2-3 hours to obtain solution B;

[0019] 3. When the temperature of solution B system is lowered to 30-40° C., the pH value is adjusted to neutral with an acid-base regulator to obtain modified polyvinyl acetate.

[0020] In some embodiments, the molar ratio of polyvinyl acetate to p-trifluoromethylstyrene is 1:(1.05-1.2).

[0021] In some embodiments, the initiator is ammonium persulfate, and the molar amount of ammonium persulfate is 5-8% of the total molar amount of polyvinyl acetate and p-trifluoromethylstyrene.

[0022] In some embodiments, the polyalkylene terephthalate is polybutylene adipate terephthalate and / or polybutylene azelaate terephthalate.

[0023] In some embodiments, the preparation method of the nucleating agent is as follows:

[0024] (1) adding 1,5-hexadiene-3,4-diol into a reaction kettle, dissolving sodium bisulfite in deionized water and adding the solution dropwise into the reaction kettle, heating and condensing under reflux to obtain a solution;

[0025] (2) After the solution is cooled to room temperature, a solvent is used to precipitate the solution, and a solid product is obtained by suction filtration. The solid product is washed and dried to obtain a nucleating agent.

[0026] In some embodiments, the molar ratio of 1,5-hexadiene-3,4-diol to sodium bisulfite is 1:(2.05-2.25); the structural formula of the nucleating agent is as follows:

[0027]

[0028] In some embodiments, the chain transfer agent is any one of n-dodecyl mercaptan, n-octyl mercaptan and tert-dodecyl mercaptan; the pigment is any one of golden red, permanent yellow, phthalocyanine blue and phthalocyanine green; and the stabilizer is a hindered amine stabilizer.

[0029] Another aspect of the present invention provides a method for preparing a recyclable transparent colored composite film, comprising the following steps:

[0030] S1. Weigh the composite polyester polymer, nucleating agent, pigment and stabilizer in parts by weight and mix them using a high-speed mixer to obtain a mixture;

[0031] S2. Add the mixture into a twin-screw extruder for shear dispersion, extrusion granulation, and injection molding to form a composite film.

[0032] Preferably, the method for preparing the recyclable transparent colored composite film comprises the following steps:

[0033] S1. Weigh the composite polyester polymer, nucleating agent, pigment and stabilizer in parts by weight and mix them at 500-1500rpm for 5-20min using a high-speed mixer to obtain a mixture;

[0034] S2. The mixture is added to a twin-screw extruder for shear dispersion. The temperature of the twin-screw extruder is 140-240°C, the rotation speed is 200-500rpm, the screw length to diameter ratio is (35-55): 1, extrusion granulation is performed, and injection molding is performed to form a composite film.

[0035] Preferably, the mixing speed of the high-speed mixer is 600-1200 rpm, the mixing time is 6-18 min, the temperature of the twin-screw extruder is 180-220° C., the speed of the twin-screw extruder is 250-400 rpm, and the ratio of screw length to diameter is (38-52):1.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The composite polyester polymer of the present invention is composed of a mixture of modified polyvinyl acetate, polyethylene terephthalate and polyalkyl acid butylene terephthalate, so that the formed film is recyclable.

[0038] (2) The present invention uses trifluoromethylstyrene to modify polyvinyl acetate, and cooperates with stabilizers to make the composite film more heat-resistant and UV-resistant, thereby maintaining bright colors and a smooth surface for a long time.

[0039] (3) The present invention can improve the molecular weight of the composite polyester polymer by introducing a chain transfer agent and modified polyvinyl acetate, thereby increasing the viscosity of the polymer system, improving the melt strength, and improving the tensile properties and tear resistance.

[0040] (4) The present invention uses 1,5-hexadiene-3,4-diol and sodium bisulfite to synthesize a new type of nucleating agent, which accelerates the crystallization rate and further improves the thermal deformation temperature and dimensional stability of the composite film. DETAILED DESCRIPTION

[0041] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, rather than to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0042] The composite films were prepared according to the ratios of the raw materials and the preparation methods specified in the following examples and comparative examples.

[0043] In order to facilitate those skilled in the art to implement the present invention, some raw material manufacturers of the embodiments and comparative examples are described as follows:

[0044] Polyvinyl acetate: purchased from Hubei Xinghengye Technology Co., Ltd.;

[0045] Polyethylene terephthalate: purchased from Shanghai Tingyuan Plastic Technology Co., Ltd.;

[0046] Polybutylene adipate terephthalate: purchased from Guangdong Fangxin Biotechnology Co., Ltd.;

[0047] Light stabilizer: purchased from Nanjing Milan New Materials Co., Ltd., model 292;

[0048] Other raw materials are not specially specified and can be purchased from the market.

[0049] Preparation Example 1

[0050] The preparation steps of modified polyvinyl acetate are as follows:

[0051] 1. Dissolve 10 mol of polyvinyl acetate in 20 ml of methanol, introduce nitrogen, and heat to 80°C to obtain solution A;

[0052] 2. Add 11 mol of p-trifluoromethylstyrene to solution A, then add 1.2 mol of ammonium persulfate, introduce nitrogen, and keep the reaction at 200 kPa for 3 hours to obtain solution B;

[0053] 3. After the solution B system is cooled to 35° C., the pH value is adjusted to 7 with aqueous ammonia to obtain modified polyvinyl acetate.

[0054] Preparation Example 2

[0055] The preparation steps of nucleating agent A are as follows:

[0056] (1) 5 mol of 1,5-hexadiene-3,4-diol was added to a reaction kettle, 10.5 mol of sodium bisulfite was dissolved in 60 ml of deionized water and slowly added dropwise to the reaction kettle, heated to 80° C. and condensed and refluxed for 8 hours to obtain a solution;

[0057] (2) After the solution is cooled to room temperature, methanol is added until no more material precipitates, and a solid product is obtained by filtration. The solid product is then washed with methanol three times and dried under vacuum at 60° C. for 24 h to obtain a nucleating agent A.

[0058] Preparation Example 3

[0059] The preparation steps of nucleating agent B are the same as those of Preparation Example 2, except that 5.25 mol of sodium bisulfite and 40 ml of deionized water are added.

[0060] Example 1

[0061] A recyclable transparent colored composite film comprises the following raw materials, measured in parts by weight: 6 parts of modified polyvinyl acetate, 74 parts of polyethylene terephthalate, 20 parts of polybutylene adipate terephthalate, 1.8 parts of nucleating agent A, 0.8 parts of n-dodecyl mercaptan, 0.3 parts of phthalocyanine blue and 2921.2 parts of light stabilizer.

[0062] The method for preparing a recyclable transparent colored composite film comprises the following steps:

[0063] S1. Weigh modified polyvinyl acetate, polyethylene terephthalate, polybutylene adipate terephthalate, nucleating agent A, n-dodecyl mercaptan, phthalocyanine blue and light stabilizer 292 in parts by weight, and mix them at 1000 rpm for 10 min using a high-speed mixer to obtain a mixture;

[0064] S2. The mixture is added into a twin-screw extruder for shear dispersion. The temperature of the twin-screw extruder is 200°C, the rotation speed is 320 rpm, the ratio of screw length to diameter is 45:1, and the composite film is formed by extrusion granulation and injection molding.

[0065] Example 2

[0066] A recyclable transparent colored composite film comprises the following raw materials, measured in parts by weight: 2 parts of modified polyvinyl acetate, 70 parts of polyethylene terephthalate, 13 parts of polybutylene azelaic terephthalate, 0.5 parts of nucleating agent A, 0.1 parts of n-dodecyl mercaptan, 0.1 parts of phthalocyanine blue and 2920.5 parts of light stabilizer.

[0067] The method for preparing a recyclable transparent colored composite film comprises the following steps:

[0068] S1. Weigh modified polyvinyl acetate, polyethylene terephthalate, polybutylene azelaic acid terephthalate, nucleating agent A, n-dodecyl mercaptan, phthalocyanine blue and light stabilizer 292 in parts by weight, and mix them at 500 rpm for 20 min using a high-speed mixer to obtain a mixture;

[0069] S2. The mixture is added into a twin-screw extruder for shear dispersion. The temperature of the twin-screw extruder is 240°C, the rotation speed is 250rpm, the ratio of screw length to diameter is 55:1, and the mixture is extruded into granules and injection molded into a composite film.

[0070] Example 3

[0071] A recyclable transparent colored composite film comprises the following raw materials, measured in parts by weight: 10 parts of modified polyvinyl acetate, 85 parts of polyethylene terephthalate, 10 parts of polybutylene adipate terephthalate, 10 parts of polybutylene azelaic terephthalate, 3 parts of a nucleating agent, 1.5 parts of n-dodecyl mercaptan, 0.4 parts of phthalocyanine blue and 2922 parts of a light stabilizer.

[0072] The method for preparing a recyclable transparent colored composite film comprises the following steps:

[0073] S1. Weigh modified polyvinyl acetate, polyethylene terephthalate, polybutylene azelaic acid terephthalate, nucleating agent A, n-dodecyl mercaptan, phthalocyanine blue and light stabilizer 292 in parts by weight, and mix them at 1500 rpm for 5 min using a high-speed mixer to obtain a mixture;

[0074] S2. The mixture is added to a twin-screw extruder for shear dispersion. The temperature of the twin-screw extruder is 140°C, the rotation speed is 500 rpm, the ratio of screw length to diameter is 35:1, and the composite film is formed by extrusion granulation and injection molding.

[0075] Example 4

[0076] A recyclable transparent colored composite film and a preparation method thereof, wherein the raw materials and the specific preparation method thereof are the same as those in Example 1, except that the modified polyvinyl acetate is replaced by polyvinyl acetate in equal parts by mass.

[0077] Example 5

[0078] A recyclable transparent colored composite film and a preparation method thereof, wherein the raw materials and the specific preparation method thereof are the same as those in Example 1, except that modified polyvinyl acetate is not added.

[0079] Example 6

[0080] A recyclable transparent colored composite film and a preparation method thereof, wherein the raw materials and the specific preparation method thereof are the same as those in Example 1, except that 15 parts of modified polyvinyl acetate, 55 parts of polyethylene terephthalate, and 30 parts of polybutylene adipate terephthalate are added.

[0081] Example 7

[0082] A recyclable transparent colored composite film and a preparation method thereof, wherein the raw materials and the specific preparation method thereof are the same as those in Example 1, except that a nucleating agent B is added.

[0083] Comparative Example 1

[0084] A recyclable transparent colored composite film and a preparation method thereof, wherein the raw materials and the preparation method thereof are the same as those in Example 1, except that a single polyester compound is used, specifically commercially available polyethylene terephthalate.

[0085] Effect evaluation:

[0086] The composite films were prepared according to the above-mentioned proportions in Examples 1-7 and Comparative Example 1, and the film properties were tested and analyzed. The test and analysis results are shown in Table 1.

[0087] Performance Test:

[0088] 1. Light transmittance test:

[0089] The transmittance of the prepared composite film was tested using a WGT-S transmittance / haze meter (Shanghai Precision Scientific Instrument Co., Ltd.).

[0090] 2. Heat resistance test:

[0091] The Vicat softening temperature of the material was measured using a Vicat softening point temperature tester (XRW-300UB). The measurement was carried out in accordance with GB / T1633-2000 (IDT ISO306:1994), with a load of 10 N, a deformation of 1.00 mm, and a VST test heating rate of 120°C / h.

[0092] 3. Tensile strength test:

[0093] The tensile strength of the prepared transparent composite film was tested according to GB / T 13022 standard.

[0094] Table 1 Performance test of composite film

[0095] Light transmittance / % Heat resistance / ℃ Tensile strength / MPa Example 1 92.8 129.8 59.8 Example 2 91.6 125.2 59.2 Example 3 93.1 132.5 62.5 Example 4 90.3 110.2 55.6 Example 5 89.2 105.2 48.7 Example 6 82.4 118.2 64.6 Example 7 94.5 115.9 56.8 Comparative Example 1 96.4 65.0 38.9

[0096] Examples 1-3 of the present invention all have good light transmittance, heat resistance and tensile strength.

[0097] Example 4 uses an equal mass portion of polyvinyl acetate to replace modified polyvinyl acetate, which significantly reduces the heat resistance of the film. Example 5 does not add modified polyvinyl acetate, so that the terminal carboxyl groups in polyethylene terephthalate and polyalkyl acid butylene terephthalate can form hydrogen bonds in a low-polarity medium, which increases the difficulty of film formation, thereby greatly reducing the tensile strength and heat resistance. Example 6 changes the mass ratio of modified polyvinyl acetate, polyethylene terephthalate and polyalkyl acid butylene terephthalate to 15:55:30, and the polyethylene terephthalate content is reduced, so that its transparency is reduced, but due to the increase in the polyalkyl acid butylene terephthalate content, the overall crystallization rate is improved, making it less likely to cause bending deformation due to uneven cooling, thereby improving the tensile strength. Example 7 uses nucleating agent B to reduce the crystallization rate of the composite film and affect the tensile strength.

[0098] Comparative Example 1 uses a single polyester compound (polyethylene terephthalate), which has high transparency, but affects its crystallization rate, reduces the tensile strength of the composite film, and due to the lack of polyalkylene terephthalate, the heat resistance is reduced.

[0099] The above is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present application. Although the present application is disclosed as above in the preferred embodiment, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases. However, 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 content of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A recyclable transparent colored composite film, characterized in that: The invention comprises the following raw materials in parts by weight: 85-115 parts of a composite polyester polymer, 0.5-3 parts of a nucleating agent, 0.1-1.5 parts of a chain transfer agent, 0.1-0.4 parts of a pigment and 0.5-2 parts of a stabilizer; wherein the composite polyester polymer is a mixture of modified polyvinyl acetate, polyethylene terephthalate and polyalkylene terephthalate, and the mass ratio of the three is (2-10): (70-86): (12-28); The preparation method of the modified polyvinyl acetate comprises the following steps:

1. Dissolve polyvinyl acetate in an organic solvent, introduce an inert gas, and heat to 70-80° C. to obtain solution A; 2. Add p-trifluoromethylstyrene to solution A, then add initiator, introduce inert gas, keep warm at 100-300 kPa and continue the reaction for 2-3 hours to obtain solution B; 3. After the solution B system is cooled to 30-40°C, the pH is adjusted to neutral with an acid-base regulator to obtain modified polyvinyl acetate; The preparation method of the nucleating agent comprises the following steps: (1) adding 1,5-hexadiene-3,4-diol into a reaction kettle, dissolving sodium bisulfite in deionized water and adding the solution dropwise into the reaction kettle, heating and condensing under reflux to obtain a solution; (2) After the solution is cooled to room temperature, a solvent is used to precipitate it, and a solid product is obtained by suction filtration, and the solid product is washed and dried to obtain a nucleating agent; wherein the molar ratio of the 1,5-hexadiene-3,4-diol to the sodium bisulfite is 1:(2.05-2.25); The structural formula of the nucleating agent is as follows: 。 2. The recyclable transparent colored composite film according to claim 1, characterized in that: The molar ratio of the polyvinyl acetate to trifluoromethylstyrene is 1:(1.05-1.2).

3. The recyclable transparent colored composite film according to claim 1, characterized in that: The polyalkylene terephthalate is polybutylene adipate terephthalate and / or polybutylene azelaic terephthalate.

4. The recyclable transparent colored composite film according to claim 1, characterized in that: The chain transfer agent is any one of n-dodecyl mercaptan, n-octyl mercaptan and tert-dodecyl mercaptan; the pigment is any one of golden red, permanent yellow, phthalocyanine blue and phthalocyanine green; and the stabilizer is a hindered amine stabilizer.

5. A method for preparing a recyclable transparent colored composite film according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Weigh the composite polyester polymer, nucleating agent, pigment and stabilizer in parts by weight and mix them using a high-speed mixer to obtain a mixture; S2. Add the mixture into a twin-screw extruder for shear dispersion, extrusion granulation, and injection molding to form a composite film.

Images