Preparation system for medium-matte polyester film

Abstract

The utility model discloses a preparation system for a medium-matt polyester film. The medium-matt polyester film is composed of a base material layer A, a surface matt layer B and a matt coating C sprayed on the outer side of the surface matt layer B. The preparation system can be used for efficiently and continuously preparing the low-matte polyester film and comprises a first mixer, a second mixer, a PET raw material tank, a silicon dioxide raw material tank, a polytetrafluoroethylene raw material tank and a polyethylene glycol raw material tank, the first mixer is respectively connected with the PET raw material tank and the silicon dioxide raw material tank, and the second mixer is respectively connected with the PET raw material tank, the polytetrafluoroethylene raw material tank and the polyethylene glycol raw material tank; the first mixer is connected with the main extruder, the second mixer is connected with the auxiliary extruder, the main extruder and the auxiliary extruder are connected with the thick sheet cooling mechanism, and the thick sheet cooling mechanism is connected with the longitudinal stretching mechanism and the transverse stretching mechanism; and a spraying mechanism, an ultraviolet irradiation mechanism, a heat setting mechanism and a winding mechanism are arranged at the downstream of the transverse stretching mechanism.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of preparation system for middle matte polyester film. BACKGROUND

[0002] Matte film has great demand in packaging, label, decoration, printing and other fields. Generally, the reflectivity of film surface below 10% is considered to be matte; the reflectivity between 10% and 30% is considered to be semi-matte; and the reflectivity above 30% is considered to be glossy. The degree of matte is generally represented by glossiness, which is usually between 0% and 100%. 0% represents no glossiness (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 the surface glossiness below 10%, which has almost no glossiness. Middle-matte film generally refers to the surface glossiness between 10% and 30%, which has certain glossiness but still maintains relatively low reflectivity. Low-matte film has surface glossiness between 30% and 50%, which is relatively smooth and has obvious glossiness but does not belong to high-gloss category.

[0003] CN 106739367 B discloses a single-sided matte polyester film having a co-extruded double-layer structure composed of a matte film layer and a base film layer. The matte film layer is composed of a polyester masterbatch containing an additive and a balance of polyester base material. The additive in the polyester masterbatch is composed of silicon dioxide and an auxiliary filler selected from at least one of calcium carbonate, hollow glass microbeads, aluminum oxide, kaolin and titanium dioxide.

[0004] The above-mentioned prior art matte film forms scattering effect of light in the film layer by adding inorganic solid particles, reduces direct reflection of light of the same angle of incidence on the film layer, and obtains 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 the scattering effect of solid particles exists in the film layer, the influence 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 in the interior of the matte layer during film stretching, thereby reducing the density and strength of the matte layer, resulting in insufficient tear resistance of the outer matte layer and easy breakage and fragmentation. In addition, the film layer after stretching has pores, which is easy to be penetrated by colorants and present patches, and the texture of the outer surface will quickly decrease.

[0005] In addition, the prior art also lacks a special device or system for preparing middle-matte polyester film, and cannot efficiently and continuously prepare low-matte polyester film. SUMMARY

[0006] The technical problem to be solved by the utility model is to provide a preparation system for medium-matt polyester film to reduce or avoid the problems mentioned above.

[0007] To solve the above technical problem, the utility model provides a preparation system for medium-matt polyester film, the medium-matt polyester film is composed of base material layer A, surface matt layer B and matt coating C sprayed on the outside of surface matt layer B, the preparation system includes first mixer corresponding to base material layer A and second mixer corresponding to surface matt layer B, the first mixer and the second mixer have a shared PET raw material tank; the inlet of the first mixer is connected with the PET raw material tank and a silicon dioxide raw material tank respectively, the inlet of the second mixer is connected with the PET raw material tank, a polytetrafluoroethylene raw material tank and a polyethylene glycol raw material tank respectively; the outlet of the first mixer is connected with main extruder, the outlet of the second mixer is connected with auxiliary extruder, the outlet of main extruder and auxiliary extruder is connected with thick sheet cooling mechanism, the outlet of thick sheet cooling mechanism is connected with longitudinal stretching mechanism, the outlet of longitudinal stretching mechanism is connected with transverse stretching mechanism; the downstream of transverse stretching mechanism is provided with spraying mechanism and ultraviolet light irradiation mechanism; the downstream of ultraviolet light irradiation mechanism is provided with heat setting mechanism, and the downstream of heat setting mechanism is provided with winding mechanism.

[0008] Preferably, the inlet of the spraying mechanism is connected with a matt coating tank.

[0009] The utility model discloses a medium-matt polyester film, which balances good mechanical strength, wear resistance and matt effect by optimizing the ratio of PET, SiO2, PTFE and PEG, has excellent light transmittance and ultraviolet resistance. The film not only has low gloss and high haze, but also has excellent chemical resistance, scratch resistance and long-term stability, and is suitable for polarizing sheet release film and optical devices and other high-end applications. In addition, the utility model also provides a special system for preparing the medium-matt polyester film, which can efficiently and continuously prepare low-matt polyester film. BRIEF DESCRIPTION OF DRAWINGS

[0010] The following drawings are only intended to illustrate and explain the application, and do not limit the scope of the utility model.

[0011] Figure 1 The structure diagram of the medium-matt polyester film according to one embodiment of the utility model is shown.

[0012] Figure 2 The structure diagram of the preparation system for medium-matt polyester film according to one embodiment of the utility model is shown. DETAILED DESCRIPTION

[0013] In order to have a clearer understanding of the technical features, objects and effects of the present application, the specific embodiments of the present application will be described with reference to the drawings. Identical components are denoted by identical reference numerals.

[0014] As shown in Figure 1 The present application provides a medium-matte polyester film, which is composed of a base material layer A, a surface matte layer B and a matte coating C sprayed on the outer side of the surface matte layer B.

[0015] In one embodiment, the thickness of the base material layer A is 30-35 μm; the thickness of the surface matte layer B is 8-10 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, and the film is suitable for applications requiring high light transmittance. When the thickness of the matte coating C is preferably 3-5 μm, the film is suitable for applications requiring low gloss, such as anti-glare applications.

[0016] The total thickness of the medium-matte polyester film of the present application is preferably designed to be about 40 μm, so that the film maintains flexibility and light transmittance while meeting mechanical strength. 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 significantly affect the mechanical properties of the base material.

[0017] In another embodiment, the base material layer A is composed of 85-90% by mass of polyethylene terephthalate (PET) and 10-15% by mass of silicon dioxide (SiO2) nanoparticles.

[0018] 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 a product with a particle size of 50-100 nm, such as Aerosil series from Evonik, such as Aerosil 200, or Cab-O-Sil series from Cabot.

[0019] In yet another embodiment, the surface matte layer B is composed of 80-85% by mass of polyethylene terephthalate (PET), 5-7% by mass of polytetrafluoroethylene (PTFE), and 10-13% by mass of polyethylene glycol (PEG) nanoparticles.

[0020] 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 micro-powder particles with a particle size of ≤1 μm, such as Dyneon TM PTFE or Solvay's PTFE series. The polyethylene glycol preferably adopts a product with a molecular weight range of 2000-6000, such as PEG produced by Merck or Sigma-Aldrich, etc.

[0021] 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: 60-65% of polyurethane acrylate (PUA), 15-20% of silicone silica microparticles, 15-20% of tripropyloxy triethylene glycol acrylate (TMPTA), 1.5-3% of benzophenone (BP), 0.5% of polyether siloxane, and 0.5% of polydimethyl siloxane.

[0022] Further specifically, the polyurethane acrylate (PUA) preferably adopts a product with a viscosity range of 3000-5000 cps, such as polyurethane acrylate resin provided by BASF, Mitsubishi Chemical, etc.; further preferably, a PUA suitable for UV-cured coating, such as the Laromer series of Merck KGaA (Germany). The silicone silica microparticles preferably adopt a product 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 a product with a purity of ≥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%, such as the UV-cured series of 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.

[0023] Further specifically, the coating material constituting the matte coating 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.

[0024] The matte coating of the utility model adds organic silicon silica particles and forms a rough surface structure, so that the gloss of the coating is significantly reduced to achieve a medium matte effect. The cross-linked structure of the PUA base resin and TMPTA improves the hardness and wear resistance of the coating. The composite structure of the organic silicon silica particles and PUA not only reduces the gloss, but also has the function of resisting ultraviolet rays, 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, ensure the low gloss effect, and at the same time enhance the durability of the film.

[0025] Further, the medium matte polyester film of the utility model can be prepared by the following process.

[0026] The raw materials constituting the base material layer A and the surface matte layer B are weighed and put into the respective mixing machines for melt blending, and the melt temperature is controlled at 250-270 DEG C.

[0027] The base material layer A is melt extruded by the main extruder at 250-260 DEG C, and the cooling roller temperature is 20 DEG C. The surface matte layer B is melt extruded by the auxiliary extruder at a temperature of 260-270 DEG C, and the cooling roller temperature is 15 DEG C. The extruded two film layers are simultaneously introduced into the cooling system to form a double-layer thick sheet, and the cooling temperature of the thick sheet is set at 15-20 DEG C.

[0028] The double-layer thick sheet is longitudinally stretched by 3 times at 85-90 DEG C, and then transversely stretched by 3.5 times at a temperature of 110-120 DEG C.

[0029] The coating material constituting the matte coating C is uniformly sprayed on the surface of the surface matte layer B, and the coating thickness is controlled at 5-10 microns. Then, it is treated by ultraviolet light initiation, the wavelength of the ultraviolet light is 365 nm, the irradiation intensity is 300 mW / cm 2 , the time is controlled at 3 minutes, and it is cooled to room temperature to form the matte coating C.

[0030] Finally, the film forming the matte coating is heat set at 200-210 DEG C for 5-10 seconds to ensure the stability of the layered structure and to enhance the dimensional stability and durability of the film.

[0031] Corresponding to the above preparation process, the utility model also proposes a preparation system for preparing the above-mentioned matte polyester film, as shown in Figure 2

[0032] The preparation system comprises a first mixer 100 corresponding to the base material layer A and a second mixer 200 corresponding to the surface matte layer B, and the first mixer 100 and the second mixer 200 have a shared PET raw material tank 10; the inlet of the first mixer 100 is connected to the PET raw material tank 10 and a silicon dioxide raw material tank 11 respectively, and the inlet of the second mixer 200 is connected to the PET raw material tank 10, a polytetrafluoroethylene raw material tank 12 and a polyethylene glycol raw material tank 13 respectively. By sharing the PET raw material tank 10, the number of equipment and the types of raw materials can be significantly reduced, which is beneficial to obtaining a film layer with uniform quality.

[0033] The first mixer 100 corresponding to the base material layer A and the second mixer 200 corresponding to the surface matte layer B melt and blend the input raw materials; and then are extruded respectively.

[0034] Further, the outlet of the first mixer 100 is connected to a main extruder 101, the outlet of the second mixer 200 is connected to an auxiliary extruder 201, and the outlets of the main extruder 101 and the auxiliary extruder 201 are connected to a thick sheet cooling mechanism 300. The base material layer A is extruded by the main extruder 101, the surface matte layer B is extruded by the auxiliary extruder 201, and then enters the thick sheet cooling mechanism 300 for cooling. The cooled thick sheet is then sequentially subjected to longitudinal stretching and transverse stretching.

[0035] The outlet of the thick sheet cooling mechanism 300 is connected to a longitudinal stretching mechanism 400, the outlet of the longitudinal stretching mechanism 400 is connected to a transverse stretching mechanism 500, and a spraying mechanism 601 and an ultraviolet light irradiation mechanism 602 are arranged downstream of the transverse stretching mechanism 500.

[0036] The spraying mechanism 601 sprays matte paint on the surface of the surface matte layer B, and then the ultraviolet light irradiation mechanism 602 is used for irradiation treatment.

[0037] Further, the inlet of the spraying mechanism 601 can also be connected to a matte paint tank 600, which is used to continuously supply matte paint to the spraying mechanism 601 through the matte paint tank 600, so as to obtain the effect of continuous production with high quality.

[0038] A heat setting mechanism 701 is arranged downstream of the ultraviolet light irradiation mechanism 602, and a winding mechanism 700 is arranged downstream of the heat setting mechanism 701.​

[0039] The polyester film prepared was subjected to performance testing. Among them, the gloss, haze, and light transmittance of the film were tested using a BYK or HunterLab gloss meter and haze meter. The tensile strength and elongation at break were tested according to the ASTM standard specification using an Instron tensile testing machine. The ultraviolet aging performance was tested for 500 hours of weather resistance using a Q-Lab Q-SUN or Atlas UV test box.

[0040] The relevant performance parameter measurement standards are shown below.

[0041] Gloss test standard: ASTM D523, measured with a 60° gloss meter. Haze test standard: ASTM D1003, measured using a haze meter, to test the scattering effect and anti-glare performance of the film. Light transmittance test standard: ASTM D1003, using a light transmittance tester, to test the light transmittance of the film under the matte effect. Tensile strength test standard: ASTM D882, using a tensile tester, tested in the machine direction (MD) and transverse direction (TD), to test the durability of the film. Elongation at break test standard: ASTM D882, to characterize the flexibility and durability of the film. Coefficient of friction (COF) test standard: ASTM D1894, measured by a coefficient of friction tester, to test the surface smoothness of the film. Surface hardness test standard: ASTM D3363, pencil hardness test, to evaluate the scratch resistance of the coating and test the wear resistance of the film during use. UV resistance: After exposure to ultraviolet light for 500 hours, maintain at least 90% or more of the light transmittance and gloss, and test whether the change rate exceeds 10%. Test standard: ASTM G154, ultraviolet aging test, to simulate the stability under long-term exposure. Chemical resistance: resistant to 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 surface matte layer. Matt coating adhesion test standard: ASTM D3359, using crosshatch method to test the adhesion of the coating to the substrate, to test the stability of the matte coating during use.

[0042] Example 1

[0043] The matte polyester film of this example is composed of a 33 μm thick substrate layer A, a 9 μm thick surface matte layer B, and a 3 μm thick matte coating C.

[0044] The base layer A contains 87% polyethylene terephthalate (PET), 13% silicon dioxide (SiO2); the surface matte layer B contains 83% PET, 6% polytetrafluoroethylene (PTFE), 11% polyethylene glycol (PEG) nanoparticles; the matte coating layer C is composed of 63% polyurethane acrylate (PUA), 17% silicone silica microparticles, 16.5% tripropoxy triethylene glycol acrylate (TMPTA), 2.5% benzophenone (BP), 0.5% polyether siloxane and 0.5% dimethicone.

[0045] The film of Example 1 has a glossiness of 16%, a haze of 18%, a light transmittance of 89%, a tensile strength of 131 MPa, an elongation at break of 115%, a friction coefficient of 0.4, a surface hardness of 2H, a change in light transmittance and glossiness of 8% after ultraviolet light aging for 500 hours, excellent resistance to common chemical solvents, and a matte coating adhesion of 5B.

[0046] Example 2

[0047] The matte polyester film of this example is composed of a 30 μm-thick base layer A, an 8 μm-thick surface matte layer B, and a 1 μm-thick matte coating layer C.

[0048] The base layer A contains 85% PET, 15% SiO2; the surface matte layer B contains 80% PET, 7% PTFE, 13% PEG; and the matte coating layer C contains 60% PUA, 16% silicone silica microparticles, 20% TMPTA, 3% BP, 0.5% polyether siloxane and 0.5% dimethicone.

[0049] The film of Example 2 has a glossiness of 18%, a haze of 21%, a light transmittance of 87%, a tensile strength of 135 MPa, an elongation at break of 121%, a friction coefficient of 0.4, a surface hardness of 2H, a change in light transmittance and glossiness of 7% after ultraviolet light aging for 500 hours, excellent resistance to common chemical solvents, and a matte coating adhesion of 5B.

[0050] Example 3

[0051] The matte polyester film of this example is composed of a 35 μm-thick base layer A, an 10 μm-thick surface matte layer B, and a 5 μm-thick matte coating layer C.

[0052] The base layer A contains 90% PET, 10% SiO2; the surface matte layer B contains 85% PET, 5% PTFE, 10% PEG; and the matte coating layer C contains 65% PUA, 15% silicone silica microparticles, 17.5% TMPTA, 1.5% BP, 0.5% polyether siloxane and 0.5% dimethicone.

[0053] The film of Example 3 has a glossiness of 19%, haze of 20%, light transmission of 88%, tensile strength of 133 MPa, elongation at break of 122%, friction coefficient of 0.4, surface hardness of 2H, UV aging for 500 hours, light transmission and glossiness change of 6%, excellent resistance to common chemical solvents, and matte coating adhesion of 5B.

[0054] Comparative Example 1

[0055] On the basis of Example 1, polytetrafluoroethylene (PTFE) in the surface matte layer B is removed.

[0056] That is, the surface matte layer B: 85% PET, 15% PEG.

[0057] Performance parameter changes: the friction coefficient rises to 0.6, the wear resistance decreases, and the matte coating adhesion decreases to 4B, indicating the importance of PTFE in reducing the friction coefficient and improving the wear resistance.

[0058] Comparative Example 2

[0059] On the basis of Example 1, benzophenone (BP) is missing in the matte coating C.

[0060] That is, the matte coating C: 63% PUA, 17% silicone silica particles, 18% TMPTA, 0.5% polyether siloxane, 0.5% polydimethylsiloxane.

[0061] Performance parameter changes: light transmission changes by 12% and glossiness changes by 15% after UV aging for 500 hours, indicating the key role of BP in resisting UV performance.

[0062] Comparative Example 3

[0063] On the basis of Example 1, the content of SiO2 in the substrate layer A is reduced to 8%.

[0064] That is, the substrate layer A: 92% PET, 8% SiO2.

[0065] Performance parameter changes: the glossiness rises to 22% and the haze decreases to 15%, the matte effect is poor, indicating the contribution of SiO2 particles to the matte effect and light scattering performance.

[0066] Comparative Example 4

[0067] On the basis of Example 2, PEG in the surface matte layer B is replaced with PMMA.

[0068] That is, the surface matte layer B: 80% PET, 7% PTFE, 13% PMMA.

[0069] Performance parameter changes: transmittance dropped to 82%, surface hardness rose to 3H, but glossiness rose to 22%, indicating the advantage of PEG in improving matte effect.

[0070] Comparative Example 5

[0071] On the basis of Example 2, the content of silicone silica particles in matte coating C was reduced to 10%.

[0072] That is, matte coating C: 60% PUA, 10% silicone silica particles, 24% TMPTA, 3% BP, 0.5% polyether siloxane, 0.5% polydimethylsiloxane.

[0073] Performance parameter changes: glossiness rose to 20%, haze dropped to 17%, and wear resistance decreased significantly, indicating the reinforcing effect of silica particles.

[0074] Comparative Example 6

[0075] On the basis of Example 2, the SiO2 particles in substrate layer A were replaced with aluminum oxide (Al2O3).

[0076] That is, substrate layer A: 85% PET, 15% Al2O3.

[0077] Performance parameter changes: transmittance dropped to 84%, haze rose to 25%, but glossiness dropped to 16%, indicating the advantage of SiO2 in comprehensive optical performance and matte effect.

[0078] Comparative Example 7

[0079] On the basis of Example 3, the content of PTFE in surface matte layer B was reduced to 3%.

[0080] That is, surface matte layer B: 87% PET, 3% PTFE, 10% PEG.

[0081] Performance parameter changes: friction coefficient rose to 0.5, and wear resistance decreased, indicating the contribution of PTFE content to surface slipperiness and wear resistance.

[0082] Comparative Example 8

[0083] On the basis of Example 3, PUA in matte coating C was replaced with epoxy acrylate (EA).

[0084] That is, matte coating C: 65% EA, 15% silicone silica particles, 17.5% TMPTA, 1.5% BP, 0.5% polyether siloxane, 0.5% polydimethylsiloxane.

[0085] Performance parameter changes: surface hardness increased to 3H, but flexibility decreased, and UV aging performance changed significantly, indicating the advantage of PUA in balancing hardness and flexibility.

[0086] Comparative Example 9

[0087] Based on Example 3, the PET content in substrate layer A was reduced to 80%.

[0088] That is, substrate layer A: 80% PET, 20% SiO2.

[0089] Performance parameter changes: film mechanical properties decreased, tensile strength decreased to 120 MPa, and elongation at break decreased to 110%, indicating the importance of PET to the mechanical properties of the substrate layer.

[0090] The performance comparison results are shown in the following table.

[0091]

[0092]

[0093] According to the comparison results of Examples 1-3 and Comparative Examples 1-9, from the functional role of each component, it is shown that in substrate layer A, polyethylene terephthalate as a substrate provides the mechanical strength, flexibility and stability of the film. In the examples, the content of PET is relatively high (85%-90%), which helps to maintain the optical clarity and durability of the film. In the comparative examples, the reduction of PET content (for example, 80% in comparative example 9) will significantly reduce the mechanical properties and durability of the film, resulting in a decrease in tensile strength. Silicon dioxide nanoparticles help to improve the surface roughness of the substrate, provide microstructure, enhance the mechanical bonding force of the coating, and improve the matte effect. In Example 1, 13% SiO2 is contained, which helps to optimize the surface optical effect and wear resistance. While in comparative example 3, the SiO2 is reduced to 8%, resulting in an increase in film surface gloss and a decrease in haze, indicating that the reduction of SiO2 will have a negative impact on the matte effect.

[0094] In the matte layer B, the high content of PET, similar to that in the substrate layer, provides the stability and mechanical properties of the film. As the main component of the matte layer, it can effectively support the adhesion of the coating. The addition of PTFE significantly improves the friction performance of the film, reduces the friction coefficient, and helps to improve the wear resistance and smoothness. In Example 2 and Example 3, the PTFE content is 5%-7%, and in Comparative Example 1, which lacks PTFE (Comparative Example 1), the friction coefficient rises to 0.6, indicating that PTFE plays an important role in reducing the friction coefficient and enhancing wear resistance. PEG can enhance the lubricity and wear resistance of the coating, and help to improve the antistatic performance of the film. In the examples, the PEG content is 10%-13%, which not only improves the friction coefficient, but also enhances the chemical stability and environmental adaptability of the film to some extent. In Comparative Example 4, PEG is replaced by PMMA, resulting in a decrease in the light transmittance and an increase in the gloss of the film, indicating that PEG plays an important role in optical performance and matte effect.

[0095] In the matte coating C, PUA is the main component of the coating, with excellent adhesion, elasticity and durability. It helps the coating to solidify into a dense protective layer, enhancing the wear resistance, UV resistance and chemical resistance of the film. In Comparative Example 8, PUA is replaced by epoxy acrylate (EA), resulting in an increase in the surface hardness of the coating but a decrease in flexibility, indicating that PUA plays a key role in balancing hardness and toughness. Silicone silica particles make important contributions to the wear resistance, scratch resistance and matte effect of the coating. It forms a uniform microstructure in the coating, enhancing the surface texture and light scattering ability of the coating. In the examples, 15%-20% of silicone silica particles are included, providing excellent wear resistance and good matte effect. Reducing this component (such as 10% in Comparative Example 5) will significantly affect the wear resistance and matte effect of the coating, resulting in an increase in gloss and a decrease in haze. TMPTA as a crosslinking agent enhances the hardness and stability of the coating. Its content in the coating is 15%-20%, which has a positive effect on the stability and chemical resistance of the coating. BP is a UV absorber that can improve the UV resistance of the coating and delay the aging of the coating. In the examples, the BP content is 2%-3%, and its absence or reduction (such as absence in Comparative Example 2) will significantly affect the UV aging performance, causing the changes in light transmittance and gloss to intensify.

[0096] The matte polyester film has the following advantages: (1) excellent mechanical properties and stability: by optimizing the PET and SiO2 content of the base material layer A, the film has excellent tensile strength, elongation at break and surface hardness, ensuring its stability and long service life in various application environments. (2) Good matte effect and optical performance: PTFE and PEG in the surface matte layer B help to improve the friction coefficient, wear resistance and lubricity of the film, and the introduction of SiO2 further enhances the matte effect. Adjusting the proportion of these components can accurately control the gloss, haze and light transmittance, ensuring the balance between low gloss and high light transmittance of the film. (3) UV and chemical resistance: the optimized combination of silicone silica particles, PUA, BP and other components in the matte coating C effectively improves the UV resistance and chemical solvent resistance of the film. Even under long-term ultraviolet light irradiation, the changes in light transmittance and gloss of the film are controlled at a low level. (4) Enhanced wear resistance and scratch resistance: by selecting appropriate silicone particles and other fillers, the coating enhances the scratch resistance, wear resistance and stain resistance of the film, ensuring that the film maintains excellent appearance and function for a long time in high-end applications. (5) Environmental protection and sustainability: the matte polyester film optimizes the components and uses environmentally friendly materials, which can meet the high performance requirements and have low environmental impact, meeting the requirements of modern industry for material sustainability.

[0097] Those skilled in the art should understand that although the present application is described in the form of multiple embodiments, not every embodiment contains only one independent technical solution. The description is only for clarity, those skilled in the art should understand the specification as a whole and understand the technical solutions involved in each embodiment as a way to combine different embodiments to understand the protection scope of the present application.

[0098] 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 production system for a medium-matt polyester film, the medium-matt polyester film being composed of a base material layer A, a surface-matt layer B, and a matt coating layer C sprayed on the outside of the surface-matt layer B; the thickness of the base material layer A is 30-35 μm; the thickness of the surface-matt layer B is 8-10 μm; the thickness of the matt coating layer C is 1-5 μm; characterized in that, The preparation system comprises a first mixer (100) corresponding to the base material layer A and a second mixer (200) corresponding to the surface matte layer B, the first mixer (100) and the second mixer (200) have a shared PET raw material tank (10); the inlet of the first mixer (100) is connected with the PET raw material tank (10) and a silica raw material tank (11) respectively, the inlet of the second mixer (200) is connected with the PET raw material tank (10), a polytetrafluoroethylene raw material tank (12) and a polyethylene glycol raw material tank (13) respectively; the outlet of the first mixer (100) is connected with a main extruder (101), the outlet of the second mixer (200) is connected with an auxiliary extruder (201), the outlets of the main extruder (101) and the auxiliary extruder (201) are connected with a thick sheet cooling mechanism (300), the outlet of the thick sheet cooling mechanism (300) is connected with a longitudinal stretching mechanism (400), the outlet of the longitudinal stretching mechanism (400) is connected with a transverse stretching mechanism (500); a spraying mechanism (601) and an ultraviolet light irradiation mechanism (602) are arranged downstream of the transverse stretching mechanism (500); a heat setting mechanism (701) is arranged downstream of the ultraviolet light irradiation mechanism (602), and a winding mechanism (700) is arranged downstream of the heat setting mechanism (701).

2. The preparation system of claim 1, wherein, The inlet of the spraying mechanism (601) is connected with a matte coating tank (600).

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