Method for producing modified biaxially stretched polyethylene terephthalate film

Abstract

The application discloses a preparation method of a modified biaxially oriented polyethylene terephthalate film; the method comprises the following steps: adding an opening agent in the form of a master batch into a polyethylene terephthalate matrix; adding a polyester imide oligomer in the form of a powder or a master batch into the polyethylene terephthalate matrix; uniformly blending the opening agent, the polyester imide oligomer and the polyethylene terephthalate through a screw extruder; and cooling a rotary drum, longitudinally stretching, transversely stretching and winding to obtain the film. The modified biaxially oriented polyethylene terephthalate (BOPET) film can reduce processing energy consumption, and meanwhile, the mechanical, optical and surface properties of the BOPET film are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of plastic film, and relates to a preparation method of modified biaxially oriented polyethylene terephthalate film. BACKGROUND

[0002] The biaxially oriented polyethylene terephthalate film has important application in the packaging field due to excellent mechanical properties and high heat resistance. However, PET is a non-polar polymer, and the surface energy is low, so the printing performance of the BOPET film is poor.

[0003] In order to improve the printing performance of the BET film, currently, corona and coating are the two most commonly used methods. Corona treatment is an electric shock treatment, which can make the surface of the BOPET film have higher adhesion, but this method has the disadvantage of time effect, and the surface energy decays over time. The coating technology is also an effective way to improve the surface performance of the BOPET film, but the increase of the coating process leads to the rise of the cost.

[0004] In the process of double-screw blending, the polar polyester imide is added to the PET melt, the polarity of the prepared film is improved, and the printing performance is improved, and the preparation process of the film is not affected, and the other performances of the film are not reduced. SUMMARY

[0005] The application aims to provide a preparation method of modified biaxially oriented polyethylene terephthalate film. Through the method, the printing performance of the BOPET film can be improved, and the preparation process of the film is not affected, and the other performances of the film are not reduced.

[0006] The application is achieved by the following technical scheme:

[0007] The application relates to a preparation method of modified biaxially oriented polyethylene terephthalate film (modified BOPET film), and the method comprises the following steps:

[0008] S1, an opening agent is added to a polyethylene terephthalate (PET) base in the form of a master batch (online through a metering pump);

[0009] S2, a polyester imide oligomer is added to the PET base in the form of a powder or a master batch (online through a metering pump);

[0010] S3, the opening agent, the polyester imide oligomer and the PET are uniformly blended through a screw extruder, a cooling drum is used for cooling, longitudinal stretching, transverse stretching and winding to prepare the BOPET film.

[0011] As an embodiment of the present application, in step S1, the opening agent can be silica microspheres, calcium carbonate particles, barium sulfate particles, alumina particles, kaolin particles, polymethyl methacrylate microparticles, polystyrene microspheres. Preferably, silica microspheres.

[0012] As an embodiment of the present application, in step S1, the opening agent is added in an amount of 0.05-0.2 parts based on 100 parts of the polyethylene terephthalate matrix. Preferably, 0.17 parts.

[0013] As an embodiment of the present application, in step S2, the polyester imide oligomer is added in an amount of 0.1-2.5 parts based on 100 parts of the polyethylene terephthalate matrix. Preferably, 0.5-1.5 parts. When the polyester imide is added in a lower amount, the surface polarity is not significantly improved; when the polyester imide is added in a higher amount, the mechanical properties of the material are reduced.

[0014] As an embodiment of the present application, the decomposition temperature of the polyester imide oligomer is 350-400℃.

[0015] As an embodiment of the present application, the molecular weight of the polyester imide oligomer is 400-20000 g / mol.

[0016] As an embodiment of the present application, the structure of the polyester imide oligomer is shown in the following formula (I):

[0017] n = 1-100.

[0018] As an embodiment of the present application, the polyester imide oligomer is prepared by a method comprising the following steps: A1, first stirring and pre-mixing trimellitic anhydride and ethanolamine under a low oxygen or inert gas atmosphere to carry out amidation reaction; A2, increasing the temperature to carry out melt polyester reaction and imidization reaction simultaneously at a preset temperature and pressure, and obtaining the polyester imide oligomer after the reaction is completed.

[0019] Further, in step A1, the molar ratio of trimellitic anhydride to ethanolamine is 0.5-2:1, and the temperature of the feed liquid is controlled between 50-200℃, and the amidation reaction is carried out until the material state is a slurry or solid state of solid-liquid mixture.

[0020] Further, in step A2, the preset temperature is 220-280℃, and the preset pressure is 0-20 MPa, and the reaction progress is judged according to the water output; when the water output is 2%-15% based on the percentage of the total feed mass, the reaction is completed.

[0021] As an embodiment of the present application, the temperature of the feeding section of the twin-screw extruder is 150-220 DEG C, the temperature of the melt plasticizing section is 260-280 DEG C, the temperature of the die is 250-270 DEG C, the temperature of the longitudinal stretching is 60-80 DEG C, and the temperature of the transverse stretching is 85-110 DEG C.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1) The polyester imide oligomer selected in the present application has good thermal stability, no volatile matter is generated in the processing process, has good compatibility when blended with polyethylene terephthalate, reduces the viscosity of the polymer melt, and is beneficial to processing.

[0024] 2) The polyester imide oligomer selected in the present application can improve the optical and surface properties of polyethylene terephthalate, and improve the printing performance of the film.

[0025] 3) The method of the present application improves the printing performance of the BOPET film without affecting the preparation process of the film and without reducing other properties of the film. BRIEF DESCRIPTION OF DRAWINGS

[0026] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, made with reference to the following drawings:

[0027] Figure 1 Surface property diagram of BOPET film with different amounts of polyester imide added;

[0028] Figure 2 NMR hydrogen spectrum of polyester imide oligomer;

[0029] Figure 3 Is the infrared spectrum of polyester imide oligomer. DETAILED DESCRIPTION

[0030] The present application will be described in detail below with reference to the embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present application. These are within the scope of protection of the present application.

[0031] The polyester-imide oligomer is prepared by the following steps: first, the molar ratio of trimellitic anhydride and ethanolamine is 0.5-2:1, and the pre-mixed stirring is carried out under low oxygen or inert gas atmosphere, the amidation reaction is carried out at 50-200℃, and the amidation reaction is carried out until the material state is slurry or solid; second, the temperature is increased, and the melt polyester reaction and imidization reaction are carried out at 220-280℃ and 0-20MPa, the reaction progress is judged according to the water output, and when the water output is 2%-15% based on the total mass of the material, the reaction is completed; the polyester-imide polymer is obtained after the reaction is completed.

[0032] Example 1

[0033] The present embodiment relates to the preparation of modified BOPET film, and the preparation specifically includes the following steps: PET, opening agent are added into the double screw extruder in the proportion of 100:0.17 to blend uniformly; BOPET film is prepared through the steps of cooling the drum, longitudinal stretching, transverse stretching, winding and the like. The temperature of the feeding section of the double screw extruder is 180℃, the temperature of the melt plasticizing section is 260℃, the die temperature is 260℃, the transverse stretching temperature is 80℃, and the longitudinal stretching temperature is 100℃. Then the tensile properties of the film are tested for mechanical property testing, and the test results are shown in Table 1. The optical properties are shown in Table 2. The surface properties are shown in Table 3. Figure 1

[0034] Example 2

[0035] The present embodiment relates to the preparation of modified BOPET film, and the preparation specifically includes the following steps: PET, opening agent, polyester-imide oligomer are added into the double screw extruder in the proportion of 100:0.17:0.1 to blend uniformly; BOPET film is prepared through the steps of cooling the drum, longitudinal stretching, transverse stretching, winding and the like. The polyester-imide oligomer selected in the present embodiment has a molecular weight of 5000g / mol and a decomposition temperature of 400℃, and the opening agent is silica microspheres. The temperature of the feeding section of the double screw extruder is 180℃, the temperature of the melt plasticizing section is 260℃, the die temperature is 260℃, the transverse stretching temperature is 80℃, and the longitudinal stretching temperature is 100℃. Then the tensile properties of the film are tested for mechanical property testing, and the test results are shown in Table 1. The optical properties are shown in Table 2. The surface properties are shown in Table 3. Figure 1

[0036] ​​The polyesterimide oligomer used in this embodiment and the following embodiments was prepared as follows: Step 1: 19.06 g of ethanolamine was added to a three-necked flask equipped with a mechanical stirrer, and the mixture was purged with nitrogen three times. Stirring was started, and 60.00 g of trimellitic anhydride was added under a nitrogen atmosphere. The heating mantle was turned on to ensure the reaction system temperature was 50°C, and the mixture was stirred at this temperature for 120 min. Step 2: The heating mantle was raised to 220°C, and the reaction was carried out under normal pressure for 30 min, while collecting the byproduct water. After the reaction was complete, 71.15 g of the final polyesterimide polymer was obtained, with a yield of approximately 90%, and 7.90 g of byproduct water, representing a water yield of 10%. Step 3: The obtained polyesterimide polymer was ground into powder with a size of 400 mesh.

[0037] 1H NMR (1H NMR) spectrum Figure 2 The infrared spectrum shows that the peaks at 3.60 ppm and 3.66 ppm are characteristic proton peaks of the terminal methylene group, while the peaks around 4.00 ppm and 4.50 ppm are characteristic proton peaks of the methylene group on the main chain; Figure 3 The display shows 713cm. -1 1078cm -1 1365cm -1 The peak at wavenumber 1720 cm⁻¹ is a characteristic peak of the imide ring. -1 The nearby peaks are characteristic peaks of the stretching vibrations of the ester group and the carbonyl group on the imide. Both test results indicate that the target polymer is composed of alternating imide and ester bonds. MALDI-TOF testing shows that the molecular weight of the repeating unit of the target polymer is 217, which matches the molecular weight of the repeating unit obtained by the condensation of trimellitic anhydride and ethanolamine after removing two molecules of water. Furthermore, its number-average molecular weight, mass-average molecular weight, and molecular weight distribution can be calculated based on the test data distribution. All the above results demonstrate that the polyester imide polymer has the structural formula shown in formula (Ⅰ). DSC determined the polymer's Tg to be 105℃, TGA determined its decomposition temperature to be 440℃, and MALDI-TOF determined its number-average molecular weight to be 1500, with a molecular weight distribution of 1.13.

[0038] Example 3

[0039] The present embodiment relates to the preparation of modified BOPET film, the specific preparation includes the following steps: PET, opening agent, polyester imide oligomer) is added to the twin screw extruder in the proportion of 100:0.17:0.25, and is uniformly blended; cooling drum, longitudinal stretching, transverse stretching, winding and other steps are prepared BOPET film. The polyester imide oligomer selected in this embodiment has a molecular weight of 5000 g / mol and a decomposition temperature of 400℃, and the opening agent is silica microspheres. The temperature of the feeding section of the twin screw extruder is 180℃, the temperature of the melting plasticizing section is 260℃, the die temperature is 260℃, the transverse stretching temperature is 80℃, and the longitudinal stretching temperature is 100℃. Then the tensile properties of the film are tested for mechanical properties, and the test results are shown in Table 1. The optical properties are shown in Table 2. The surface properties are shown in Figure 1 .

[0040] Example 4

[0041] The present embodiment relates to the preparation of modified BOPET film, the specific preparation includes the following steps: PET, opening agent, polyester imide oligomer) is added to the twin screw extruder in the proportion of 100:0.17:0.5, and is uniformly blended; cooling drum, longitudinal stretching, transverse stretching, winding and other steps are prepared BOPET film. The polyester imide oligomer selected in this embodiment has a molecular weight of 5000 g / mol and a decomposition temperature of 400℃, and the opening agent is silica microspheres. The temperature of the feeding section of the twin screw extruder is 180℃, the temperature of the melting plasticizing section is 260℃, the die temperature is 260℃, the transverse stretching temperature is 80℃, and the longitudinal stretching temperature is 100℃. Then the tensile properties of the film are tested for mechanical properties, and the test results are shown in Table 1. The optical properties are shown in Table 2. The surface properties are shown in Figure 1 .

[0042] Example 5

[0043] The present embodiment relates to the preparation of modified BOPET film, the specific preparation includes the following steps: PET, opening agent, polyester imide oligomer) is added to the twin screw extruder in the proportion of 100:0.17:1, and is uniformly blended; cooling drum, longitudinal stretching, transverse stretching, winding and other steps are prepared BOPET film. The polyester imide oligomer selected in this embodiment has a molecular weight of 5000 g / mol and a decomposition temperature of 400℃, and the opening agent is silica microspheres. The temperature of the feeding section of the twin screw extruder is 180℃, the temperature of the melting plasticizing section is 260℃, the die temperature is 260℃, the transverse stretching temperature is 80℃, and the longitudinal stretching temperature is 100℃. Then the tensile properties of the film are tested for mechanical properties, and the test results are shown in Table 1. The optical properties are shown in Table 2. The surface properties are shown in Figure 1 .

[0044] Example 6

[0045] The present example relates to the preparation of modified BOPET film, and the specific preparation comprises the following steps: PET, opening agent, polyester imide oligomer are added into the twin-screw extruder in the ratio of 100:0.17:1.5, and are uniformly blended; and the BOPET film is prepared through the steps of cooling the drum, longitudinal stretching, transverse stretching, winding, and the like. The polyester imide oligomer selected in the present example has a molecular weight of 5000 g / mol and a decomposition temperature of 400℃, and the opening agent is silica microspheres. The temperature of the feeding section of the twin-screw extruder is 180℃, the temperature of the melt plasticizing section is 260℃, the die temperature is 260℃, the transverse stretching temperature is 80℃, and the longitudinal stretching temperature is 100℃. Then the tensile properties of the film are tested for mechanical properties, and the test results are shown in Table 1. The optical properties are shown in Table 2. The surface properties are shown in Table 3. Figure 1

[0046] Example 7

[0047] The present example relates to the preparation of modified BOPET film, and the specific preparation comprises the following steps: PET, opening agent, polyester imide oligomer are added into the twin-screw extruder in the ratio of 100:0.17:1.5, and are uniformly blended; and the BOPET film is prepared through the steps of cooling the drum, longitudinal stretching, transverse stretching, winding, and the like. The polyester imide oligomer selected in the present example has a molecular weight of 5000 g / mol and a decomposition temperature of 400℃, and the opening agent is silica microspheres. The temperature of the feeding section of the twin-screw extruder is 180℃, the temperature of the melt plasticizing section is 260℃, the die temperature is 260℃, the transverse stretching temperature is 80℃, and the longitudinal stretching temperature is 100℃. Then the tensile properties of the film are tested for mechanical properties, and the test results are shown in Table 1. The optical properties are shown in Table 2. The surface properties are shown in Table 3. Figure 1

[0048] Example 8

[0049] ​​The embodiment relates to preparation of modified BOPET film, and the preparation specifically comprises the following steps: adding PET, an opening agent and a polyester imide oligomer into a double-screw extruder according to a ratio of 100:0.17:2.5 to uniformly blend; and preparing the BOPET film through the steps of cooling a rotary drum, longitudinal stretching, transverse stretching, winding and the like. The polyester imide oligomer selected in the embodiment has a molecular weight of 5000 g / mol and a decomposition temperature of 400 DEG C, and the opening agent is silica microspheres. The temperature of a feeding section of the double-screw extruder is 180 DEG C, the temperature of a melting plasticizing section is 260 DEG C, the temperature of a die head is 260 DEG C, the temperature of transverse stretching is 80 DEG C, and the temperature of longitudinal stretching is 100 DEG C. Then, the tensile properties of the film are tested, and the test results are shown in Table 1. The optical properties are shown in Table 2. The surface properties are shown in Table 3. Figure 1

[0050] Table 1 Mechanical properties of BOPET films with different amounts of polyester imide

[0051]

[0052] Table 2 Optical properties of BOPET films with different amounts of polyester imide

[0053]

[0054]

[0055] As shown in Table 1, the tensile strength and the tensile modulus of the film are increased to a certain extent, but the elongation at break changes little. As shown in Table 2, the light transmittance, the haze, the clarity and the gloss of the film are improved by adding the polyester imide oligomer with different contents. Figure 1 As shown in Table 3, the surface energy and the surface polarity of the film are increased by adding the polyester imide oligomer with different contents.

[0056] The specific embodiments of the application are described above. It should be understood that the application is not limited to the specific embodiments described above, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which do not affect the essential content of the application.​

Claims

1. A method for producing a modified biaxially-stretched polyethylene terephthalate film, characterized by, The method consists of the following steps: S1, adding an opening agent in the form of a master batch to a polyethylene terephthalate matrix; the opening agent is added in an amount of 0.05-0.2 parts per 100 parts of the polyethylene terephthalate matrix; S2, adding a polyester-imide oligomer in the form of a powder or a master batch to the polyethylene terephthalate matrix; the polyester-imide oligomer is added in an amount of 0.05-5 parts per 100 parts of the polyethylene terephthalate matrix; The polyester-imide oligomer has the following structural formula (I): n＝1-100； DSC measurement of the polymer Tg is 105℃, TGA measurement of the decomposition temperature is 440℃, MALDI-TOF measurement of the number average molecular weight is 1500, and the molecular weight distribution is 1.13; S3, blending the opening agent, the polyester-imide oligomer and the polyethylene terephthalate uniformly through a screw extruder, cooling a drum, longitudinal stretching, transverse stretching, and winding to obtain the film.

2. The production method according to claim 1, characterized by, The opening agent can be silica microspheres, calcium carbonate particles, barium sulfate particles, aluminum oxide particles, kaolin particles, polymethyl methacrylate microparticles, and polystyrene microspheres.

3. The preparation method according to claim 1, characterized in that, The polyester-imide oligomer is prepared by a method comprising the following steps: A1, first stirring and pre-mixing trimellitic anhydride and ethanolamine under a low-oxygen or inert gas atmosphere to perform an amidation reaction; A2, increasing the temperature to simultaneously perform a melt polyester reaction and an imidization reaction under a preset temperature and pressure, and obtaining the polyester-imide oligomer after the reaction is completed.

4. The production method according to claim 3, characterized by, In step A1, the molar ratio of trimellitic anhydride to ethanolamine is 0.5-2:1, the temperature of the feed liquid is controlled between 50℃-200℃, and the amidation reaction is performed until the material state is a slurry or a solid; in step A2, the preset temperature is 220℃-280℃, the preset pressure is 0-20MPa, and the reaction progress is judged according to the water output; when the water output is 2%-15% based on the total feed mass, the reaction is completed.

5. The method of claim 1, wherein, The temperature of the feeding section of the twin-screw extruder is 150℃-220℃, the temperature of the melt plasticizing section is 260℃-280℃, the die temperature is 250℃-270℃, the longitudinal stretching temperature is 60℃-80℃, and the transverse stretching temperature is 85℃-110℃.

Images