A high-strength matte polyester film for car covers and its preparation method

Abstract

This invention discloses a high-strength matte polyester film for car covers and its preparation method, belonging to the field of polyester film technology. It comprises the following raw materials in parts by weight: 7-8 parts PET polyester chips, 50-80 parts matte masterbatch, 10-30 parts white non-fluorescent polyester chips, and 0.8-1 parts nano-reinforcing agent. The preparation method includes the following steps: Step S1: The raw materials in the specified parts by weight are stirred and mixed, pre-crystallized and dried, then transferred to an extruder, filtered through a filter, and extruded through a die to form a melt film, which is then cooled by a cold drum to form a film casting. Step S2: The film casting is transferred to a biaxial stretching machine, passing through a longitudinal stretching preheating section, a longitudinal stretching shaping section, and a transverse stretching shaping section, and then stretched to obtain a high-strength matte polyester film for car covers. The production process of this invention is simple and easy to operate, with relatively low cost. The resulting polyester film has the characteristics of high haze, high abrasion resistance, and good mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of polyester film technology, specifically relating to a high-strength matte polyester film for car covers and its preparation method. Background Technology

[0002] A car cover is a thin film adhered to the surface of a car. It is widely used for exterior decoration and protection, providing excellent protection against common scratches, abrasions from hard objects like metal, and paint aging. Matte car covers, in particular, are popular with consumers for their subtle, hazy finish, and have a promising market prospect. Polyethylene terephthalate film (polyester film) possesses excellent mechanical properties, thermal properties, and superior chemical resistance, and has been widely used in the car cover industry.

[0003] Existing matte polyester films for car covers generally employ melt blending, adding silica to polyester chips to achieve a matte film effect. When the requirements for haze and gloss of the matte polyester film are low, adding a small amount (3wt%) of silica can achieve good results. However, if the haze and gloss standards are to be further improved, adding a large amount of silica will highlight the problems of uneven dispersion and interfacial compatibility, resulting in a serious reduction in the strength of the matte polyester film. Although the copolymerization modification method can meet the requirements of high haze and mechanical properties of matte polyester films, its process is complex and the preparation cost is high.

[0004] Therefore, how to produce a matte polyester film for car wraps with high strength and good mechanical properties is a technical problem that needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength matte polyester film for car covers and its preparation method, so as to solve the problems in the background art.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A high-strength matte polyester film for car covers comprises the following raw materials in parts by weight:

[0008] The composition includes 7-8 parts PET polyester chips, 50-80 parts matte masterbatch, 10-30 parts white non-fluorescent polyester chips, and 0.8-1 parts nano-reinforcing agent; the nano-reinforcing agent is prepared through the following steps:

[0009] Zirconium tetrachloride and terephthalic acid were added to N,N-dimethylformamide and stirred until homogeneous at room temperature. The mixture was then stirred and reacted at 110-130℃ for 24 h. After cooling to room temperature, the mixture was washed with N,N-dimethylformamide and ethanol, centrifuged, and dried under vacuum at 100℃ for 10 h to obtain the nano-reinforcing agent.

[0010] Furthermore, the ratio of zirconium tetrachloride, terephthalic acid, and N,N-dimethylformamide is 0.94-1.17 g : 0.67-0.83 g : 60-80 mL.

[0011] Furthermore, the matte masterbatch is prepared through the following steps:

[0012] Step A1: Add the coupling agent to an ethanol aqueous solution, stir and dissolve at 60°C, then add silica with a particle size of 3-5μm and keep it at the temperature for 3-5 hours. Filter, wash, and dry in an oven at 100°C for 2 hours to obtain modified silica.

[0013] Step A2: Add modified silica and PET polyester chips into a twin-screw extruder, melt mix at 270-280℃, extrude, cool, and pelletize to obtain matte masterbatch.

[0014] This invention improves the dispersibility and compatibility of silica in polyester matrix under conventional dosage by modifying silica with a particle size of 3-5 μm, and also avoids the adsorption effect of silica on nano-reinforcing agents and titanium dioxide.

[0015] Furthermore, the ratio of the coupling agent, silica, and ethanol aqueous solution is 1.5-2 g: 8 g: 100 mL; the concentration of the ethanol aqueous solution is 75 wt%.

[0016] Furthermore, the coupling agent is KH570; KH570 can not only react with the hydroxyl groups on the surface of silica, reducing the hydroxyl content on the surface of silica and effectively preventing the aggregation of silica, thus promoting the dispersion of silica in the matte polyester film; it can also react with the polyester matrix, improving the interfacial interaction and interaction force between the modified silica and the polyester matrix.

[0017] Furthermore, the mass ratio of modified silica to PET polyester chips is 3-4:100. When using modified silica to melt-blend modify PET polyester chips, the content of modified silica should not be too high; otherwise, even after modification, the silica will still exhibit negative effects.

[0018] Furthermore, the white, non-fluorescent polyester chips are prepared by melt-mixing titanium dioxide with a particle size of 1.5 μm and PET polyester chips, wherein the titanium dioxide content is 60 wt%. Titanium dioxide not only enhances the weather resistance and abrasion resistance of the polyester chips, making them more durable when applied to automotive paint surfaces, but also has good hiding power and light reflectivity, which can improve the haze of the polyester film.

[0019] A method for preparing a high-strength matte polyester film for car covers includes the following steps:

[0020] Step S1: Mix the PET polyester chips, matte masterbatch, white non-fluorescent polyester chips and nano-reinforcing agent according to the formula weight parts, pre-crystallize at 170-175℃, dry at 155℃ for 4 hours, then transfer to an extruder, filter through a filter and extrude through the die head to form a melt film, and cool through a cold drum to form a thin film casting.

[0021] Step S2: Transfer the film casting into the biaxial stretching machine. After passing through the longitudinal stretching preheating section, the longitudinal stretching shaping section, and the transverse stretching shaping section, stretching is used to obtain a high-strength matte polyester film for car wraps with a thickness of 50 μm.

[0022] Furthermore, in step S1, the filter temperature is 275°C, the head temperature is 270-275°C, the cooling drum rotation speed is 43 m / min, and the cooling drum temperature is 25-27°C.

[0023] Furthermore, in step S2, the temperature of the longitudinal stretching preheating section is 70-89℃, the temperature of the longitudinal stretching and shaping section is 27-35℃, and the temperature of the transverse stretching and shaping section is 235-240℃.

[0024] The beneficial effects of this invention are:

[0025] This invention uses zirconium salt and terephthalic acid as raw materials to prepare an organometallic framework-structured nano-reinforcing agent through a coordination reaction. This nano-reinforcing agent is then introduced into a matte polyester film. On one hand, the nano-reinforcing agent acts as a nucleating agent, with terephthalic acid as a ligand. Its large specific surface area allows for sufficient contact with the polyester substrate, making the heterogeneous nucleation effect more pronounced and significantly improving the crystallization rate and crystallinity of the polyester substrate. On the other hand, the nano-reinforcing agent itself possesses flexibility, overcoming the deformation limitations of silica and titanium dioxide, and can be used as a toughening agent. Furthermore, the high specific surface area and porous structure of the nano-reinforcing agent increase light scattering in the polyester film, thereby improving haze. Therefore, a small amount of nano-reinforcing agent can bring improvements in both haze and mechanical strength to the matte polyester film.

[0026] This invention uses PET polyester chips as the substrate. By controlling the amounts of matte masterbatch, white non-fluorescent polyester chips, and nano-reinforcing agents, and by melt-blending these raw materials, it achieves the gradation effect of modified silica, titanium dioxide, and nano-reinforcing agents at different scales. Micron-sized silica and titanium dioxide are commonly used fillers in matte polyester films. The unique optical properties of silica and titanium dioxide can increase the scattering of light in the polyester film, thereby improving the haze of the polyester film. Due to its structural characteristics, the nano-reinforcing agent can further improve the haze of the polyester film at the nanoscale. As rigid particles, silica and titanium dioxide can significantly improve the strength and wear resistance of the polyester film while maintaining good processing performance. The nano-reinforcing agent, as a complementary material, utilizes its role as both a nucleating agent and a toughening agent to further improve the strength and toughness of the polyester film. During the melt blending process, modified silica, titanium dioxide, and nano-reinforcing agents can be well dispersed in the polyester matrix, reducing agglomeration. Through their respective characteristics and functions, they synergistically improve the haze and mechanical properties of the matte polyester film.

[0027] The present invention produces a matte polyester film through melt blending modification and biaxial stretching. The production process is simple and easy to operate, with low cost. The resulting polyester film has the characteristics of high haze, high wear resistance and good mechanical properties. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] This embodiment provides a matte masterbatch, which is prepared through the following steps:

[0031] Step A1: Add 1.5g KH570 to 100mL of 75wt% ethanol aqueous solution, stir and dissolve at 60℃, then add 8g of silica with a central particle size of 3μm and keep the reaction at the temperature for 5h, filter, wash, and dry in an oven at 100℃ for 2h to obtain modified silica.

[0032] Step A2: Add 3g of modified silica and 100g of PET polyester chips to a twin-screw extruder, melt mix at 270℃, extrude, cool, and pelletize to obtain matte masterbatch.

[0033] Example 2

[0034] This embodiment provides a matte masterbatch, which is prepared through the following steps:

[0035] Step A1: Add 1.8g KH570 to 100mL of 75wt% ethanol aqueous solution, stir and dissolve at 60℃, then add 8g of silica with a central particle size of 4μm and keep the reaction at the temperature for 4h, filter, wash, and dry in an oven at 100℃ for 2h to obtain modified silica.

[0036] Step A2: Add 3.5g of modified silica and 100g of PET polyester chips to a twin-screw extruder, melt mix at 275℃, extrude, cool, and pelletize to obtain matte masterbatch.

[0037] Example 3

[0038] This embodiment provides a matte masterbatch, which is prepared through the following steps:

[0039] Step A1: Add 2g of KH570 to 100mL of 75wt% ethanol aqueous solution, stir and dissolve at 60℃, then add 8g of silica with a particle size of 5μm and keep the reaction at the temperature for 3h, filter, wash, and dry in an oven at 100℃ for 2h to obtain modified silica.

[0040] Step A2: Add 4g of modified silica and 100g of PET polyester chips to a twin-screw extruder, melt mix at 280℃, extrude, cool, and pelletize to obtain matte masterbatch.

[0041] Comparative Example 1

[0042] The difference between this comparative example and Example 2 is that in step A2, silicon dioxide with a particle size of 4μm is used to replace the modified silicon dioxide in an equal amount, that is, the modification operation in step A1 is not performed, while the other raw materials and steps are the same.

[0043] Comparative Example 2

[0044] The difference between this comparative example and Example 2 is that in step A2, the amount of modified silica is increased from 3.5g to 5g, that is, the modification operation in step A1 is not performed, and the other raw materials and steps are the same.

[0045] Example 4

[0046] This embodiment provides a nano-reinforcing agent, which is prepared through the following steps:

[0047] 0.94 g of zirconium tetrachloride and 0.67 g of terephthalic acid were added to 60 mL of N,N-dimethylformamide and stirred until homogeneous at room temperature. The mixture was then stirred at 110 °C for 24 h. After cooling to room temperature, the mixture was washed with 70 mL of N,N-dimethylformamide and 70 mL of ethanol, centrifuged, and dried under vacuum at 100 °C for 10 h to obtain the nano-reinforcing agent.

[0048] Example 5

[0049] This embodiment provides a nano-reinforcing agent, which is prepared through the following steps:

[0050] 1.06 g of zirconium tetrachloride and 0.76 g of terephthalic acid were added to 70 mL of N,N-dimethylformamide and stirred until homogeneous at room temperature. The mixture was then stirred at 120 °C for 24 h. After cooling to room temperature, the mixture was washed with 70 mL of N,N-dimethylformamide and 70 mL of ethanol, centrifuged, and vacuum dried at 100 °C for 10 h to obtain the nano-reinforcing agent.

[0051] Example 6

[0052] This embodiment provides a nano-reinforcing agent, which is prepared through the following steps:

[0053] 1.17 g of zirconium tetrachloride and 0.83 g of terephthalic acid were added to 80 mL of N,N-dimethylformamide and stirred until homogeneous at room temperature. The mixture was then stirred at 130 °C for 24 h. After cooling to room temperature, the mixture was washed with 70 mL of N,N-dimethylformamide and 70 mL of ethanol, centrifuged, and dried under vacuum at 100 °C for 10 h to obtain the nano-reinforcing agent.

[0054] Example 7

[0055] This embodiment provides a high-strength matte polyester film for car covers, which is prepared by the following method:

[0056] Step S1: 7 parts by weight of PET polyester chips, 50 parts by weight of matte masterbatch prepared in Example 1, 10 parts by weight of white non-fluorescent polyester chips containing 60 wt% titanium dioxide with a particle size of 1.5 μm, and 0.8 parts by weight of nano-reinforcing agent prepared in Example 4 are stirred and mixed, pre-crystallized at 170°C, and dried at 155°C for 4 hours. Then, the mixture is transferred to an extruder, filtered through a 275°C filter, and extruded through a 270°C die head to form a melt film. The melt film is cooled on a cold drum at a temperature of 25°C and a rotation speed of 43 m / min to form a thin film casting.

[0057] Step S2: Transfer the film casting into a biaxial stretching machine. After passing through a longitudinal stretching preheating section at 70°C, a longitudinal stretching shaping section at 27°C, and a transverse stretching shaping section at 235°C, stretching yields a high-strength matte polyester film for car wraps with a thickness of 50µm.

[0058] Example 8

[0059] This embodiment provides a high-strength matte polyester film for car covers, which is prepared by the following method:

[0060] Step S1: 7.5 parts by weight of PET polyester chips, 65 parts by weight of matte masterbatch prepared in Example 2, 20 parts by weight of white non-fluorescent polyester chips containing 60 wt% titanium dioxide with a particle size of 1.5 μm, and 0.9 parts by weight of nano-reinforcing agent prepared in Example 5 are stirred and mixed, pre-crystallized at 172°C, and dried at 155°C for 4 hours. Then, the mixture is transferred to an extruder, filtered through a 275°C filter, and extruded through a 275°C die head to form a melt film. The melt film is cooled on a cold drum at a temperature of 26°C and a rotation speed of 43 m / min to form a thin film casting.

[0061] Step S2: Transfer the film casting into a biaxial stretching machine. After passing through a longitudinal stretching preheating section at 80°C, a longitudinal stretching and shaping section at 30°C, and a transverse stretching and shaping section at 238°C, stretching yields a high-strength matte polyester film for car wraps with a thickness of 50µm.

[0062] Example 9

[0063] This embodiment provides a high-strength matte polyester film for car covers, which is prepared by the following method:

[0064] Step S1: Mix 8 parts by weight of PET polyester chips, 80 parts by weight of matte masterbatch prepared in Example 3, 30 parts by weight of white non-fluorescent polyester chips containing 60 wt% titanium dioxide with a particle size of 1.5 μm, and 1 part by weight of nano-reinforcing agent prepared in Example 6. Pre-crystallize at 175°C and dry at 155°C for 4 hours. Then transfer to an extruder, filter through a 275°C filter to a 275°C die head, and extrude to form a melt film. Cool the melt film on a cold drum at 27°C and 43 m / min to form a thin film casting.

[0065] Step S2: Transfer the film casting into a biaxial stretching machine. After passing through a longitudinal stretching preheating section at 89°C, a longitudinal stretching and shaping section at 35°C, and a transverse stretching and shaping section at 240°C, stretching yields a high-strength matte polyester film for car wraps with a thickness of 50µm.

[0066] Comparative Example 3

[0067] The difference between this comparative example and Example 8 is that the matte masterbatch prepared in Comparative Example 1 is used to replace the matte masterbatch prepared in Example 2 in an equal amount, while the other raw materials and steps are the same.

[0068] Comparative Example 4

[0069] The difference between this comparative example and Example 8 is that the matte masterbatch prepared in Comparative Example 2 is used to replace the matte masterbatch prepared in Example 2 in an equal amount, while the other raw materials and steps are the same.

[0070] Comparative Example 5

[0071] The difference between this comparative example and Example 8 is that PET polyester chips were used to replace the white non-fluorescent polyester chips containing 60 wt% titanium dioxide with a particle size of 1.5 μm in an equal amount; all other raw materials and steps were the same.

[0072] Comparative Example 6

[0073] The difference between this comparative example and Example 8 is that white non-fluorescent polyester chips containing 60 wt% titanium dioxide with a particle size of 1.5 μm were used in an equal amount to replace the white non-fluorescent polyester chips containing 60 wt% titanium dioxide with a particle size of 3 μm. All other raw materials and steps are the same.

[0074] Comparative Example 7

[0075] The difference between this comparative example and Example 8 is that the amount of nano-reinforcing agent prepared in Example 5 was adjusted from 0.9 parts by weight to 0 parts by weight, that is, no nano-reinforcing agent was added. All other raw materials and steps are the same.

[0076] Comparative Example 8

[0077] The difference between this comparative example and Example 8 is that the amount of the nano-reinforcing agent prepared in Example 5 was increased from 0.9 parts by weight to 1.5 parts by weight, while the other raw materials and steps were the same.

[0078] Performance tests were conducted on Examples 7-9 and Comparative Examples 3-8. The tensile strength, elastic modulus, and elongation at break of the matte polyester film were tested according to GB / T1040.3 standard; the haze of the matte polyester film was tested according to GB / T2410 standard; and the gloss of the matte polyester film was tested according to GB / T 8807 standard. The results are shown in Table 1.

[0079] Table 1

[0080]

[0081] As can be seen from the data in Table 1, the matte polyester films prepared in Examples 7-9 have higher tensile strength and elongation at break, as well as higher haze and lower gloss. The matte polyester films prepared in Comparative Examples 3-8 are inferior to those in Examples 7-9 in all aspects, indicating that the matte polyester films prepared according to the formulation and preparation method of the present invention improve both mechanical properties and haze.

[0082] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0083] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-strength, matte polyester film for use in vehicle wraps, characterized in that, The following raw materials are included by weight parts: 7-8 parts of PET polyester chips, 50-80 parts of matt masterbatch, 10-30 parts of white non-fluorescent polyester chips and 0.8-1 part of nano-enhancing agent; The matt masterbatch is prepared by the following steps: Step A1, coupling agent is added to an aqueous ethanol solution, stirred and dissolved at 60°C, then 3-5 μm particle size silica is added and reacted for 3-5 h, filtered, washed and dried to obtain modified silica; Step A2, the modified silica and PET polyester chips are added to a twin-screw extruder for melt mixing, extruded, cooled, and pelletized to obtain a matt masterbatch; The white non-fluorescent polyester chips are prepared by melt mixing 1.5 μm particle size titanium white powder and PET polyester chips, and the content of the titanium white powder is 60 wt%; The nano-enhancing agent is prepared by the following steps: Zirconium tetrachloride and terephthalic acid are added to N,N-dimethylformamide, stirred and mixed uniformly at room temperature, then stirred and reacted for 24 h at 110-130°C, washed, centrifuged and vacuum dried after cooling to room temperature to obtain the nano-enhancing agent.

2. The high-strength matte polyester film for car covers according to claim 1, characterized by The amount ratio of the zirconium tetrachloride, terephthalic acid and N,N-dimethylformamide is 0.94-1.17 g: 0.67-0.83 g: 60-80 mL.

3. The high-strength matte polyester film for car covers according to claim 1, characterized by The amount ratio of the coupling agent, silica and aqueous ethanol solution is 1.5-2 g: 8 g: 100 mL; and the concentration of the aqueous ethanol solution is 75 wt%.

4. The high-strength matte polyester film for car covers according to claim 1, characterized by The coupling agent is KH570.

5. The high-strength matte polyester film for car covers according to claim 1, characterized by The mass ratio of the modified silica and PET polyester chips is 3-4:

100.

6. The method for preparing a high-strength matte polyester film for car covers according to claim 1, characterized in that, The following steps are included: Step S1, the formula weight parts of PET polyester chips, matt masterbatch, white non-fluorescent polyester chips and nano-enhancing agent are stirred and mixed, pre-crystallized at 170-175°C, dried and then transferred to an extruder, filtered through a filter to the head of the extruder to form a melt film, and cooled into a film casting piece through a cold drum; Step S2, the film casting piece is transferred to a two-way stretching machine, stretched after passing through a longitudinal stretching preheating section, a longitudinal stretching setting section and a transverse stretching setting section to obtain a high-strength matt polyester film for car covers.

7. The method for preparing a high-strength matte polyester film for car covers according to claim 6, characterized in that, The filter temperature is 275°C, and the head temperature is 270-275°C; the cold drum rotation speed is 43 m / min, and the cold drum temperature is 25-27°C.

8. The method for preparing a high-strength matte polyester film for car covers according to claim 6, characterized in that, The temperature of the longitudinal stretching preheating section is 70-89°C, the temperature of the longitudinal stretching setting section is 27-35°C, and the temperature of the transverse stretching setting section is 235-240°C.

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