High-matte-degree polyester film and preparation method thereof

Abstract

The invention discloses a high-matte polyester film and a preparation method thereof. The high-matte polyester film is composed of a base material layer A, a surface matte layer B and a matte coating C. The base material layer A is composed of polyethylene glycol terephthalate and silicon dioxide nanoparticles; the surface matte layer B is composed of polyethylene glycol terephthalate, polytetrafluoroethylene, polyethylene glycol and polymethyl methacrylate; the matte coating C is prepared from polyurethane acrylate, organic silicon silicon dioxide particles, triethylene glycol tripropoxy acrylate, benzophenone, polyether siloxane and polydimethylsiloxane. According to the high-matte polyester film, through the composite design of the nano filler and the fluorinated polymer, the glossiness is effectively reduced, and the matte effect is improved. The double-layer structure ensures high light transmittance and is suitable for applications with high requirements on visual definition. The film has ultraviolet resistance, wear resistance and electrostatic protection, and is widely applied to polaroid release films and optical protection. The multi-layer structure and the heat setting process ensure the dimensional stability and adapt to complex environments.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of matte film, in particular to a high-matte polyester film and a preparation method thereof. BACKGROUND

[0002] Matte film has a high demand in the fields of packaging, labeling, decoration, printing, etc. Generally, a film surface with a reflectivity lower than 10% is considered matte; a reflectivity between 10% and 30% is considered semi-matte; and a reflectivity higher than 30% is considered glossy. The degree of matte is generally represented by glossiness, which is usually in the range of 0% to 100%. 0% represents complete matte (e.g. matte surface), and 100% represents maximum glossiness (e.g. mirror surface). Glossiness is usually measured by a gloss meter. High-matte film generally refers to a surface with a glossiness lower than 10%, which has almost no gloss. Medium-matte film generally refers to a surface with a glossiness between 10% and 30%, which has a certain gloss but still maintains a relatively low reflectivity. Low-matte film has a glossiness between 30% and 50%, which is relatively smooth and has obvious gloss but does not belong to the high-gloss category.

[0003] CN 114619745 B discloses a multi-layer structure matte polyester film, which comprises a base film and a matte film. The intermediate layer is the base film, and the matte film is on both sides of the base film, obtained by co-extrusion technology. The raw material of the matte film includes a matte additive, which is a polymer grafted modified silica microsphere and a polystyrene microsphere. The polymer grafted modified monomer is (meth) acrylate and isobornyl acrylate.

[0004] The above-mentioned prior art matte film forms scattering of light inside the film layer by adding inorganic solid particles, reduces the direct reflection of the film layer to light of the same angle of incidence, and obtains a certain matte effect. The scattering of light by solid particles also hinders the projection of light, thereby reducing the light transmission performance of the film. At the same time, although there is scattering of light by solid particles inside the film layer, the impact on the surface of the film is limited, and the roughness of the film surface is difficult to effectively reduce, and the smooth surface is difficult to reduce the light reflectivity. In addition, in order to obtain sufficient matte effect, the particle size of the added solid particles needs to reach a certain degree, and the addition amount also needs to be sufficient. The addition of too many large-diameter solid particles will form cavities inside the matte layer during film stretching, reducing the density and strength of the matte layer, thereby causing insufficient tear resistance of the outer matte layer and easy breakage and fragmentation, and the surface texture will quickly decrease due to the pores of the stretched film layer which are easily penetrated by colorants and present patches.

[0005] CN 110157032 A discloses a preparation method of high-matte matte polyester film. First, polyester film is prepared and stretched, then acrylamide is coated on the surface, and the film surface is grafted and copolymerized with acrylamide by ultraviolet irradiation. Then, polyurethane paint and polyacrylate paint are coated on the surface of the matte polyester film, and the refractive index of the double-sided coating layer increases the light transmittance of the matte polyester film.

[0006] However, it is known that acrylamide (Acrylamide, abbreviated as AA) has good hydrophilicity. If acrylamide is polymerized with polyester film under ultraviolet irradiation, the film surface should have better wetting performance, reduce the surface contact angle, make the liquid spread more easily on the film surface, and the film surface should become smoother and more difficult to become rough. In addition, the polymer chain of acrylamide forms a smooth and uniform coating on the surface of the PET film, which can fill the small recesses on the surface, so that the overall surface becomes smoother. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a high-matte polyester film and a preparation method thereof to reduce or avoid the problems mentioned above.

[0008] To solve the above technical problems, the present application provides a high-matte polyester film, which is composed of a substrate layer A, a surface matte layer B and a matte coating layer C sprayed on the outside of the surface matte layer B, wherein the substrate layer A is composed of 79.5-80.5% by mass of polyethylene terephthalate and 19.5-20.5% by mass of silicon dioxide nanoparticles; the surface matte layer B is composed of 78.5-82.5% by mass of polyethylene terephthalate, 2.5-3.5% by mass of polytetrafluoroethylene, 9.5-10.5% by mass of polyethylene glycol and 4.5-8.5% by mass of polymethyl methacrylate; and the matte coating layer C is composed of a coating material cured by ultraviolet light, which is composed of 59.5-60.5% by mass of polyurethane acrylate, 19.5-20.5% by mass of silicone silica particles, 16.5-17.5% by mass of tripropoxy triethylene glycol acrylate, 1.5-2.5% by mass of benzophenone, 0.45-0.55% by mass of polyether siloxane and 0.45-0.55% by mass of polydimethylsiloxane.

[0009] Preferably, the thickness of the substrate layer A is 30-35 μm; the thickness of the surface matte layer B is 12-15 μm; and the thickness of the matte coating layer C is 1-5 μm.

[0010] The application further provides a preparation method of the high-matte polyester film, which comprises the following steps: weighing raw materials for forming the substrate layer A and the surface matte layer B, and respectively feeding the raw materials into respective mixers for melt blending, with a melting temperature controlled at 250-270 DEG C; melt extruding the substrate layer A through a main extruder at 250-260 DEG C, with a cooling roller temperature of 20 DEG C; melt extruding the surface matte layer B through an auxiliary extruder at a temperature of 260-270 DEG C, with a cooling roller temperature of 15 DEG C; making the extruded two-layer film layers enter a cooling system at the same time to form a double-layer thick sheet, with a cooling temperature of the thick sheet set at 15-20 DEG C; longitudinally stretching the double-layer thick sheet at 3 times at an environment of 85-90 DEG C, and then transversely stretching the double-layer thick sheet at 3.5 times at a temperature of 110-120 DEG C; uniformly spraying a coating material for forming the matte coating layer C on the surface of the surface matte layer B, with a coating thickness controlled at 5-10 microns; then performing ultraviolet light initiation treatment, with a wavelength of the ultraviolet light being 365 nm, an irradiation intensity being 300 mW / cm 2 , a time being controlled at 3 minutes, and cooling to room temperature to form the matte coating layer C; and finally, performing heat setting treatment on the film with the matte coating layer.

[0011] Preferably, the preparation method further comprises a step of preparing the matte coating material: mixing the polyurethane acrylate and the tripropoxy triethylene glycol acrylate according to a mass ratio, and stirring at room temperature until completely dissolved to form a uniform solution; adding the silicone silica microparticles into the solution, and stirring for 10-15 minutes to ensure uniform dispersion; adding the benzophenone, the polyether siloxane and the polydimethylsiloxane according to a ratio, and slowly stirring for 5 minutes to completely dissolve the components; and filtering the solution through a 100-mesh filter screen to remove undispersed particles or impurities.

[0012] The high-matte polyester film prepared by the application combines the nano filler, the fluorinated polymer and the surface nano structure, significantly reduces the surface gloss, and improves the matte effect. The A and B double-layer structure design ensures a relatively high light transmittance, and is suitable for application scenarios with high requirements for visual clarity. The high-matte polyester film of the application has the advantages of ultraviolet resistance, antistatic property, wear resistance and excellent matte effect, and is suitable for high-end applications such as polarizing sheet release film and optical device surface protection. The multi-layer structure and the heat setting process ensure the dimensional stability, adapt to high-temperature and high-humidity environments, and prolong the service life. BRIEF DESCRIPTION OF DRAWINGS

[0013] The following drawings are merely intended to schematically illustrate and explain the application, and do not limit the scope of the application.

[0014] Figure 1 A structure schematic diagram of the high-matte polyester film according to one specific embodiment of the application is shown. DETAILED DESCRIPTION

[0015] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described with reference to the drawings. In the drawings, the same components are designated by the same reference numerals.

[0016] As shown in Figure 1 The present application proposes a high-matte polyester film, which is composed of a substrate layer A, a surface matte layer B and a matte coating C sprayed on the outside of the surface matte layer B.

[0017] In one specific embodiment, the thickness of the substrate layer A is 30-35 μm; the thickness of the surface matte layer B is 12-15 μm; and the thickness of the matte coating C is 1-5 μm. When the thickness of the matte coating C is preferably 1-3 μm, the matte effect of the film does not significantly affect the transparency of the film, which is suitable for applications requiring high light transmittance. When the thickness of the matte coating C is preferably 3-5 μm, it is suitable for occasions with high requirements for low gloss, such as anti-glare applications.

[0018] The total thickness of the high-matte polyester film of the present application is preferably designed to be about 40-50 μm, so that the film can meet the mechanical strength while maintaining flexibility and light transmittance. The thickness of the matte coating C is 1-5 μm, which can ensure uniform distribution of the coating while maintaining low gloss and wear resistance, and will not have excessive impact on the mechanical properties of the substrate.

[0019] In another specific embodiment, the substrate layer A is composed of 79.5-80.5% by mass of polyethylene terephthalate (PET) and 19.5-20.5% by mass of silicon dioxide (SiO2) nanoparticles.

[0020] Further, the polyethylene terephthalate preferably uses optical grade PET particles or chips, preferably a raw material product with a melting point of about 255°C, such as high-purity optical grade PET provided by Toray, DuPont, etc., with a light transmittance of more than 90%. The silicon dioxide nanoparticles preferably use products with a particle size of 50-100 nm, such as Aerosil series of Evonik, such as Aerosil 200, or Cab-O-Sil series of Cabot.

[0021] In yet another specific embodiment, the surface matte layer B is composed of 78.5-82.5% by mass of polyethylene terephthalate (PET), 2.5-3.5% by mass of polytetrafluoroethylene (PTFE), 9.5-10.5% by mass of polyethylene glycol (PEG), and 4.5-8.5% by mass of polymethyl methacrylate (PMMA).

[0022] Further, the polyethylene terephthalate preferably adopts optical grade PET particles or chips, preferably the raw material product with a melting point of about 255°C, such as high-purity optical grade PET provided by Toray, DuPont, etc., with a light transmittance of more than 90%. The polytetrafluoroethylene preferably adopts micropowder particles with a particle size of ≤1 μm, such as Dyneon TM PTFE or Solvay's PTFE series. The polyethylene glycol preferably adopts products with a molecular weight range of 2000-6000, such as PEG products produced by Merck or Sigma-Aldrich, etc. The polymethyl methacrylate preferably adopts PMMA series products provided by Evonik (such as ), and PMMA products of LG Chemical can also be used.

[0023] In still another specific embodiment, the matte coating C is formed by ultraviolet curing of a coating formed of raw materials with the following mass fractions: 59.5-60.5% of polyurethane acrylate (PUA), 19.5-20.5% of silicone silica microparticles, 16.5-17.5% of tripropyloxy triethylene glycol acrylate (TMPTA), 1.5-2.5% of benzophenone (BP), 0.45-0.55% of polyether siloxane, and 0.45-0.55% of polydimethyl siloxane.

[0024] Further specifically, the polyurethane acrylate (PUA) preferably adopts products with a viscosity range of 3000-5000 cps, such as polyurethane acrylate resins provided by BASF, Mitsubishi Chemical, etc.; further preferably, PUA suitable for UV-cured coatings, such as the Laromer series of Merck KGaA (Germany). The silicone silica microparticles preferably adopt products with a particle size of 3-5 μm, such as the Sipernat series of Degussa, or the Syloid series of Grace. The tripropyloxy triethylene glycol acrylate preferably adopts products with a purity of greater than or equal to 98%, such as high-purity TMPTA supplied by Sigma-Aldrich or Allnex. The benzophenone preferably has a spectral range of about 365 nm, with a purity of ≥99%. For example, UV-cured series products of IGM Resins or BASF. Both the polyether siloxane and the polydimethyl siloxane can adopt products of BYK Chemicals, such as polyether siloxane BYK-333 and polydimethyl siloxane BYK-016.

[0025] Further specifically, the coating material constituting the matte coating layer C can be prepared by the following process. For example, polyurethane acrylate and TMPTA are mixed in a mass ratio, and stirred at room temperature until completely dissolved to form a uniform solution. Organic silicon silica particles are added to the above solution, and stirred for 10-15 minutes to ensure uniform dispersion. A high-speed stirring device (about 1000 rpm) is used for better effect. Benzophenone, polyether siloxane, and polydimethylsiloxane are added in proportion, and slowly stirred for 5 minutes to completely dissolve the components. The solution is filtered through a 100-mesh filter to remove undispersed particles or impurities, ensuring the uniformity and transparency of the coating layer.

[0026] The matte coating material of the present application significantly reduces the gloss of the coating layer by adding organic silicon silica particles and forming a surface rough structure, achieving a high matte effect. The cross-linked structure of the PUA base resin and TMPTA improves the hardness and wear resistance of the coating layer. The composite structure of organic silicon silica particles and PUA not only reduces the gloss, but also has anti-ultraviolet function, prolonging the service life of the film. The design and process of the coating material help to form a uniform and stable matte layer on the surface, ensuring a low gloss effect, while enhancing the durability of the film.

[0027] Further, the high-matte polyester film of the present application can be prepared by the following process.

[0028] The raw materials constituting the substrate layer A and the surface matte layer B are weighed and fed into the respective mixers for melt blending, with the melt temperature controlled at 250-270°C.

[0029] The substrate layer A is melt-extruded by the main extruder at 250-260°C, and the cooling roll temperature is 20°C. The surface matte layer B is melt-extruded by the auxiliary extruder at a temperature of 260-270°C, and the cooling roll temperature is 15°C. The extruded two-layer film layers are simultaneously fed into the cooling system to form a double-layer thick sheet, with the cooling temperature of the thick sheet set at 15-20°C.

[0030] The double-layer thick sheet is subjected to 3 times longitudinal stretching at 85-90°C, and then subjected to 3.5 times transverse stretching at a temperature of 110-120°C.

[0031] The coating material constituting the matte coating layer C is uniformly sprayed on the surface of the surface matte layer B, with the coating thickness controlled at 5-10 μm. Then, it is treated by ultraviolet light initiation, with the ultraviolet light wavelength being 365 nm, the irradiation intensity being 300 mW / cm 2 , and the time being controlled at 3 minutes, and cooled to room temperature to form the matte coating layer C.

[0032] Finally, the film forming the matte coating is heat set at 200-210°C for 5-10 seconds to ensure the stability of the layered structure and to enhance the dimensional stability and durability of the film.

[0033] The polyester film prepared is tested for performance. The film is tested for gloss, haze, and clarity using a BYK or HunterLab gloss meter and haze meter. The tensile strength and elongation at break are tested using an Instron tensile tester according to ASTM standard specifications. The UV aging performance is tested using a Q-Lab Q-SUN or Atlas UV test chamber set for 500 hours of weathering.

[0034] The relevant performance parameters are measured according to the following standards.

[0035] Gloss test standard: ASTM D523, measured using a 60° gloss meter. Haze test standard: ASTM D1003, measured using a haze meter to test the film's scattering effect and anti-glare performance. Clarity test standard: ASTM D1003, measured using a light transmittance tester to test the film's light transmittance under matte effect. Tensile strength test standard: ASTM D882, tested using a tensile tester in the machine direction (MD) and transverse direction (TD) to test the film's durability. Elongation at break test standard: ASTM D882, to characterize the film's flexibility and durability. Coefficient of friction (COF) test standard: ASTM D1894, measured using a coefficient of friction tester to test the film's surface smoothness. Surface hardness test standard: ASTM D3363, pencil hardness test to evaluate the coating's scratch resistance and test the film's wear resistance during use. UV resistance: maintain at least 90% or more of the transmittance and gloss after 500 hours of exposure to UV light, and test whether the change rate exceeds 10%. Test standard: ASTM G154, UV aging test to simulate the stability under long-term exposure. Chemical resistance: resist wiping with common chemical solvents such as ethanol and isopropanol, and whether there is obvious damage to the surface. Test standard: ASTM D5402, coating chemical resistance test to test the stability of the matte surface layer. Matte coating adhesion test standard: ASTM D3359, using the crosshatch method to test the adhesion of the coating to the substrate and test the stability of the matte coating during use.

[0036] Example 1

[0037] The high-matte polyester film of this example is composed of a 32 μm thick base layer A, a 14 μm thick surface matte layer B, and a 3 μm thick matte coating layer C.

[0038] The base layer A contains 80.0% polyethylene terephthalate and 20.0% silicon dioxide; the surface matte layer B contains 80.0% PET, 3.0% polytetrafluoroethylene, 10.0% polyethylene glycol, and 7.0% polymethyl methacrylate; the matte coating layer C contains 60.0% polyurethane acrylate, 20.0% silicone silica microparticles, 17.0% tripropoxy acrylate, 2.0% benzophenone, 0.5% polyether siloxane, and 0.5% dimethyl polysiloxane.

[0039] The film of Example 1 has a glossiness of 5%, a haze of 28%, a light transmittance of 85%, a tensile strength of 146 MPa, an elongation at break of 128%, a friction coefficient of 0.5, a surface hardness of 2H, a change in light transmittance and glossiness of 5% after ultraviolet light aging for 500 hours, excellent resistance to common chemical solvents, and a matte coating adhesion of 5B.

[0040] Example 2

[0041] The high-matte polyester film of this example is composed of a 30-μm-thick base layer A, a 12-μm-thick surface matte layer B, and a 1-μm-thick matte coating layer C.

[0042] The base layer A contains 79.5% PET and 20.5% SiO2; the surface matte layer B contains 78.5% PET, 2.5% PTFE, 10.5% PEG, and 8.5% PMMA; and the matte coating layer C contains 59.5% PUA, 20.5% silicone silica microparticles, 16.6% TMPTA, 2.5% BP, 0.45% polyether siloxane, and 0.45% dimethyl polysiloxane.

[0043] The film of Example 2 has a glossiness of 4%, a haze of 31%, a light transmittance of 83%, a tensile strength of 152 MPa, an elongation at break of 125%, a friction coefficient of 0.4, a surface hardness of 2H, a change in light transmittance and glossiness of 6% after ultraviolet light aging for 500 hours, excellent resistance to common chemical solvents, and a matte coating adhesion of 5B.

[0044] Example 3

[0045] The high-matte polyester film of this example is composed of a 35-μm-thick base layer A, a 15-μm-thick surface matte layer B, and a 5-μm-thick matte coating layer C.

[0046] The base layer A contains 80.5% PET and 19.5% SiO2; the surface matte layer B contains 82.5% PET, 3.5% PTFE, 9.5% PEG, and 4.5% PMMA; and the matte coating layer C contains 60.5% PUA, 19.5% silicone silica microparticles, 17.4% TMPTA, 1.5% BP, 0.55% polyether siloxane, and 0.55% dimethyl polysiloxane.

[0047] The film of Example 3 has a gloss of 6%, haze of 26%, and light transmission of 84%; tensile strength of 149 MPa, elongation at break of 130%; coefficient of friction of 0.3, surface hardness of H; change in light transmission and gloss of 7% after 500 hours of UV aging; and excellent resistance to common chemical solvents; matte coating adhesion of 5B.

[0048] Comparative Example 1

[0049] Substrate layer A: same as Example 1, containing 80.0% PET and 20.0% SiO2.

[0050] Surface matte layer B: same as Example 1, containing 80.0% PET, 3.0% PTFE, 10.0% PEG, 7.0% PMMA.

[0051] Matte coating C: changed to 60.0% PUA, 20.0% silicone silica microparticles, 17.0% TMPTA, 0.5% polyether siloxane, 0.5% polydimethylsiloxane.

[0052] Performance data: gloss of 8%, haze of 24%, light transmission of 82%; tensile strength of 146 MPa, elongation at break of 128%; coefficient of friction of 0.5, surface hardness of 2H; change in light transmission and gloss of 15% after 500 hours of UV aging; matte coating adhesion of only 3B.

[0053] Comparative Example 1 shows that, in the absence of benzophenone, the coating is not sufficiently cured, and the UV aging performance is significantly reduced, and the adhesion is reduced.

[0054] Comparative Example 2

[0055] Substrate layer A: same as Example 1, containing 80.0% PET and 20.0% SiO2.

[0056] Surface matte layer B: changed to 80.0% PET, 3.0% PTFE, 17.0% PMMA (without PEG).

[0057] Matte coating C: same as Example 1, containing 60.0% PUA, 20.0% silicone silica microparticles, 17.0% TMPTA, 2.0% BP, 0.5% polyether siloxane, 0.5% polydimethylsiloxane.

[0058] Performance data: gloss of 12%, haze of 20%, light transmission of 80%; tensile strength of 140 MPa, elongation at break of 110%; coefficient of friction of 0.6, surface hardness of 2H; change in light transmission and gloss of 10% after 500 hours of UV aging; matte coating adhesion of 5B.

[0059] Comparative Example 2 shows that the removal of PEG, the flexibility of the surface matte layer is weakened, the gloss and friction performance is deteriorated.

[0060] Comparative Example 3

[0061] Substrate layer A: changed to 90.0% PET and 10.0% SiO2.

[0062] Surface matte layer B: same as Example 1, containing 80.0% PET, 3.0% PTFE, 10.0% PEG, 7.0% PMMA.

[0063] Matte coating C: same as Example 1, containing 60.0% PUA, 20.0% silicone silica microparticles, 17.0% TMPTA, 2.0% BP, 0.5% polyether siloxane, 0.5% polydimethylsiloxane.

[0064] Performance data: gloss 10%, haze 18%, light transmittance 88%; tensile strength 144 MPa, elongation at break 120%; friction coefficient 0.5, surface hardness 2H; UV aging for 500 hours, light transmittance and gloss change 7%; matte coating adhesion 5B.

[0065] Comparative Example 3 shows that the insufficient content of silica in the substrate layer leads to the decrease of haze and matte performance, and cannot effectively realize high matte characteristics.

[0066] Comparative Example 4

[0067] Substrate layer A: changed to 85.0% PET and 15.0% SiO2.

[0068] Surface matte layer B: same as Example 2, containing 78.5% PET, 2.5% PTFE, 10.5% PEG, 8.5% PMMA.

[0069] Matte coating C: same as Example 2, containing 59.5% PUA, 20.5% silicone silica microparticles, 16.6% TMPTA, 2.5% BP, 0.45% polyether siloxane, 0.45% polydimethylsiloxane.

[0070] Performance data: gloss 6%, haze 28%, light transmittance 84%; tensile strength 140 MPa, elongation at break 115%; friction coefficient 0.4, surface hardness 2H; UV aging for 500 hours, light transmittance and gloss change 9%; matte coating adhesion 5B.

[0071] Comparative Example 4 shows that the decrease of the content of silica leads to the decrease of mechanical strength and optical effect.

[0072] Comparative Example 5

[0073] Substrate layer A: same as example 2, containing 79.5% PET, 20.5% SiO2.

[0074] Surface matte layer B: changed to 80.5% PET, 5.5% PTFE, 13.0% PEG (PMMA removed).

[0075] Matte coating layer C: same as example 2, containing 59.5% PUA, 20.5% silicone silica micro-particles, 16.6% TMPTA, 2.5% BP, 0.45% polyether siloxane, 0.45% polydimethylsiloxane.

[0076] Performance data: gloss 5%, haze 35%, light transmittance 81%; tensile strength 148 MPa, elongation at break 110%; friction coefficient 0.6, surface hardness 2H; UV aging for 500 hours, light transmittance and gloss change 10%; matte coating adhesion 5B.

[0077] Comparative example 5 shows that removing PMMA and increasing PTFE improves wear resistance, but results in insufficient flexibility and reduces optical effect.

[0078] Comparative example 6

[0079] Substrate layer A: same as example 2, containing 79.5% PET, 20.5% SiO2.

[0080] Surface matte layer B: containing 78.5% PET, 2.5% PTFE, 13.5% PEG, 5.5% PMMA.

[0081] Matte coating layer C: same as example 2, containing 59.5% PUA, 20.5% silicone silica micro-particles, 16.6% TMPTA, 2.5% BP, 0.45% polyether siloxane, 0.45% polydimethylsiloxane.

[0082] Performance data: gloss 7%, haze 30%, light transmittance 82%; tensile strength 140 MPa, elongation at break 120%; friction coefficient 0.5, surface hardness 2H; UV aging for 500 hours, light transmittance and gloss change 8%; matte coating adhesion 5B.

[0083] Comparative example 6: increasing PEG content improves flexibility, but causes compromise in gloss and haze, overall effect is not as good as example 2.

[0084] Comparative example 7

[0085] Substrate layer A: same as example 3, containing 80.5% PET and 19.5% SiO2.

[0086] Surface matte layer B: changed to 80.0% PET, 6.5% PTFE, 9.5% PEG, 4.0% PMMA.

[0087] Matte coating C: same as Example 3, containing 60.5% PUA, 19.5% silicone silica microparticles, 17.4% TMPTA, 1.5% BP, 0.55% polyether siloxane, 0.55% polydimethylsiloxane.

[0088] Performance data: gloss 5%, haze 33%, light transmission 80%; tensile strength 150 MPa, elongation at break 110%; friction coefficient 0.7, surface hardness 3H; change in light transmission and gloss after UV aging for 500 hours 12%; matte coating adhesion 5B.

[0089] Comparative Example 7 shows that increasing PTFE improves hardness and wear resistance, but affects flexibility and optical performance.

[0090] Comparative Example 8

[0091] Substrate layer A: changed to 85.0% PET and 15.0% SiO2.

[0092] Surface matte layer B: same as Example 3, containing 82.5% PET, 3.5% PTFE, 9.5% PEG, 4.5% PMMA.

[0093] Matte coating C: same as Example 3, containing 60.5% PUA, 19.5% silicone silica microparticles, 17.4% TMPTA, 1.5% BP, 0.55% polyether siloxane, 0.55% polydimethylsiloxane.

[0094] Performance data: gloss 6%, haze 28%, light transmission 86%; tensile strength 145 MPa, elongation at break 120%; friction coefficient 0.5, surface hardness 2H; change in light transmission and gloss after UV aging for 500 hours 9%; matte coating adhesion 5B.

[0095] Comparative Example 8 shows that reducing silica increases transparency, but reduces scratch resistance, resulting in a slight decrease in optical effect.

[0096] Comparative Example 9

[0097] Substrate layer A: same as Example 3, containing 80.5% PET and 19.5% SiO2.

[0098] Surface matte layer B: changed to 79.5% PET, 2.5% PTFE, 14.5% PEG, 3.5% PMMA.

[0099] Matte coating C: same as example 3, containing 60.5% PUA, 19.5% silicone silica microparticles, 17.4% TMPTA, 1.5% BP, 0.55% polyether siloxane, 0.55% polydimethylsiloxane.

[0100] Performance data: gloss 8%, haze 25%, light transmittance 82%; tensile strength 145 MPa, elongation at break 125%; friction coefficient 0.4, surface hardness 2H; UV aging for 500 hours, light transmittance and gloss change 10%; matte coating adhesion 5B.

[0101] Comparative example 9 shows that increasing PEG improves flexibility, but the matte effect is weak, affecting the overall performance of the film.

[0102] In the high-matte polyester film of the present application, the SiO2 particles in the substrate layer A can significantly increase the surface roughness of the substrate, form a microstructure, and enhance the mechanical bonding force between the coating and the substrate. The addition of SiO2 not only improves the scratch resistance of the film, but also optimizes the optical properties of the film, effectively prolonging the service life of the film. In addition, the high thermal stability and structural integrity of SiO2 help to improve the thermal stability of the substrate, ensuring the performance stability of the film in high temperature environment. By enhancing the interfacial bonding force between the substrate layer A and the surface matte layer B, a better adhesion foundation can be provided for the matte coating C, thereby improving the wear resistance, stability and service life of the coating.

[0103] The polytetrafluoroethylene (PTFE) in the surface matte layer B has excellent slipperiness and low friction performance, which can significantly reduce the surface friction coefficient of the film, reduce interlayer friction and the accumulation of static electricity between the film layers, thereby protecting the substrate layer A from mechanical damage and environmental impact, and having an antistatic effect. The addition of PTFE not only improves the overall wear resistance of the matte coating C, making the surface more durable, but also improves the stain resistance of the film, reduces the adhesion of pollutants, and keeps the film surface clean for a long time. In this layer, the addition of polyethylene glycol (PEG) helps to improve the flexibility of the film, reduce the surface tension, and maintain excellent performance in low temperature or high humidity environment. PEG can also enhance the water resistance of the coating, reducing the damage of water to the film. The addition of PMMA not only improves the hardness, wear resistance and light scattering property of the film, but also further enhances the ultraviolet resistance and anti-pollution performance of the film. It works together with other ingredients (such as PTFE, PEG and SiO2, etc.) to make the film have high matte effect while still maintaining excellent mechanical properties and environmental stability.

[0104] The polyurethane acrylate (PUA) in the matte coating C has excellent elasticity and adhesion, and can form a dense protective layer after curing, improving the wear resistance and chemical resistance of the surface matte layer B, and providing additional protection against ultraviolet light and solvent erosion. PUA not only enhances the durability of the surface matte layer B, but also protects the substrate layer A from environmental factors. The silicone silica particles in the coating not only improve the matte effect of the film, but also provide additional scratch resistance, enhancing the surface texture of the film. The silicone silica nanoparticles provide high light scattering capability, which helps to enhance the overall matte effect, while their thermal stability and light stability significantly improve the anti-aging performance of the material, reducing the change in gloss over time. Benzophenone (BP) as an ultraviolet light absorber can effectively absorb and shield ultraviolet light, slow down the damage of ultraviolet light to the material, reduce the aging rate, and prolong the service life of the material. Its addition effectively protects the substrate layer A and the surface matte layer B from the physical property changes caused by ultraviolet light, thereby ensuring the long-term stability of the film. The addition of polyether siloxane further improves the flexibility and water resistance of the coating, enhancing the adaptability of the film in extreme environments, especially in high humidity environments. The addition of polydimethylsiloxane helps to improve the surface smoothness of the film, enhance the anti-pollution and self-cleaning ability, and avoid the impact on the appearance caused by dust or dirt adhesion on the surface.

[0105] In summary, the high-matte polyester film of the present application has the following advantages due to its unique multi-layer structure design and precise material ratio.(1) Low gloss and matte effect: Through the composite design of nano-filler (such as silica), fluorinated polymer (such as PTFE) and surface nano-structure, the surface gloss of the film is effectively reduced, ensuring excellent matte effect, suitable for high demand visual effect requirements.(2) High light transmittance: The A, B double-layer structure design enables the film to maintain high light transmittance, while reducing unnecessary light reflection on the basis of ensuring visual clarity, suitable for precision optical equipment or display applications requiring high light transmittance.(3) Excellent UV resistance, wear resistance, anti-static and matte performance: The film has excellent UV resistance, anti-static, wear resistance and outstanding matte effect, suitable for high-end demand scenarios such as polarizer release film and optical device surface protection, effectively protecting the product from external environmental damage and prolonging its service life.(4) Dimensional stability: The combination of multi-layer structure and heat setting process ensures that the film can maintain dimensional stability in complex environments, suitable for extreme environments such as high temperature or high humidity, and can maintain its excellent performance over a long period of use.(5) Enhanced anti-pollution and self-cleaning performance: The addition of polydimethylsiloxane, PTFE and polyether siloxane significantly improves the anti-pollution and self-cleaning ability of the film, keeping the surface clean and avoiding dirt adhesion, especially in complex environments with stronger stain resistance.

[0106] These advantages make high haze polyester films the ideal choice for high-end materials in electronics, optics, automotive and other fields, especially for applications with high requirements for durability, stability, optical effects and environmental resistance.

[0107] Those skilled in the art should understand that, although the present application is described in the manner of multiple embodiments, not every embodiment contains only one independent technical solution. The description is only for the sake of clarity, and those skilled in the art should understand the specification as a whole and understand the technical solutions involved in each embodiment as being combined into different embodiments to understand the scope of protection of the present application.

[0108] The above is only a specific embodiment of the present application, and is not intended to limit the scope of the present application. Any equivalent changes, modifications and combinations made by those skilled in the art without departing from the concept and principles of the present application shall fall within the scope of protection of the present application.

Claims

1. A high-matte polyester film composed of a base layer A, a surface matte layer B, and a matte coating layer C sprayed on the outer side of the surface matte layer B, characterized in that, The substrate layer A is composed of 79.5-80.5% by mass of polyethylene terephthalate and 19.5-20.5% by mass of silica nanoparticles; the surface matte layer B is composed of 78.5-82.5% by mass of polyethylene terephthalate, 2.5-3.5% by mass of polytetrafluoroethylene, 9.5-10.5% by mass of polyethylene glycol and 4.5-8.5% by mass of polymethyl methacrylate; the matte coating layer C is formed by ultraviolet curing of a coating material composed of 59.5-60.5% by mass of polyurethane acrylate, 19.5-20.5% by mass of silicone silica microparticles, 16.5-17.5% by mass of tripropoxy triethylene glycol acrylate, 1.5-2.5% by mass of benzophenone, 0.45-0.55% by mass of polyether siloxane and 0.45-0.55% by mass of polydimethylsiloxane.

2. The polyester film according to claim 1, wherein The thickness of the substrate layer A is 30-35 μm; the thickness of the surface matte layer B is 12-15 μm; the thickness of the matte coating layer C is 1-5 μm.

3. A process for the production of a high-dullness polyester film as claimed in one of claims 1-2, characterized in that, The preparation method comprises the following steps: weighing the raw materials constituting the base material layer A and the surface matte layer B, and respectively feeding into the respective mixing machines for melt blending, with the melt temperature controlled at 250-270 DEG C; the base material layer A is melt extruded by the main extruder at 250-260 DEG C, with the cooling roller temperature being 20 DEG C; the surface matte layer B is melt extruded by the auxiliary extruder at a temperature of 260-270 DEG C, with the cooling roller temperature being 15 DEG C; the extruded two-layer film layers are simultaneously made to enter the cooling system to be laminated to form a double-layer thick sheet, with the cooling temperature of the thick sheet being set at 15-20 DEG C; the double-layer thick sheet is subjected to 3 times longitudinal stretching at 85-90 DEG C, and then subjected to 3.5 times transverse stretching at a temperature of 110-120 DEG C; the paint constituting the matte coating C is uniformly sprayed on the surface of the surface matte layer B, with the coating thickness being controlled at 5-10 microns; then UV light initiation treatment is carried out, with the UV light wavelength being 365 nm, the irradiation intensity being 300 mW / cm 2 , the time being controlled at 3 minutes, and cooling to room temperature to form the matte coating C; finally, the film with the matte coating is subjected to heat setting treatment. The application further discloses a film with a matte coating prepared by the method.

4. The production method according to claim 3, wherein The preparation method further comprises the step of preparing the matte coating material: mixing polyurethane acrylate and tripropoxy triethylene glycol acrylate in a mass ratio, stirring at room temperature until completely dissolved to form a uniform solution; adding silicone silica microparticles to the above solution, stirring for 10-15 minutes to ensure uniform dispersion; adding benzophenone, polyether siloxane and polydimethylsiloxane in a ratio and slowly stirring for 5 minutes to completely dissolve the components; filtering the solution with a 100-mesh filter to remove undispersed particles or impurities.

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