A low-gloss, high-weatherability fluoropolymer film

Abstract

The application discloses a kind of low gloss, high weatherability fluorine-containing polymer film, the fluorine-containing polymer film includes extinction layer and matrix layer, by double-layer co-extrusion preparation fluorine-containing polymer film, extinction layer component includes 75~90 portions PVDF, 10~25 portions PMMA, 0.5~2 portions organic ultraviolet absorber, 1~5 portions acrylic ester microspheres with reactive group by mass fraction;Matrix layer component includes 65~80 portions PVDF, 20~35 portions PMMA by mass fraction.The fluorine-containing polymer film of the application has the characteristics of low gloss, high weatherability, etc., solves the shortcomings of previous extinction film or extinction coating processing difficulty, poor mechanical properties and weather resistance, etc.The fluorine-containing polymer film of the application is especially suitable for building exterior wall, car film as persistent protective film.

Description

Technical Field

[0001] This invention relates to the field of fluoropolymer films, and particularly to a low-gloss, high-weather-resistant fluoropolymer film. Background Technology

[0002] Fluoropolymers, such as polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), and ethylene-chlorotrifluoroethylene 1:1 alternating copolymer (ECTFE), have been widely used in coatings and protective films due to their excellent protective properties. While simple fluoropolymer coatings / films offer good transparency and weather resistance, their high gloss results in a noticeable reflective effect. With societal progress, the low-gloss visual effect caused by image degradation seems to be more aesthetically pleasing.

[0003] Conventional matting techniques are used by adding matting agents to fluoropolymer resins. Patent document CN108026389A discloses a radiation-curable composition for use in low-gloss coatings, comprising composition I and composition II. Composition I consists of 20–95 wt% of one or more (meth)acrylated compounds a, 5–80 wt% of one or more metal salts of C10–C22 fatty acids b, and 0–10 wt% of one or more compounds c. Compound a is selected from polyester (meth)acrylates, epoxy (meth)acrylates, polyether (meth)acrylates, amine-modified polyether (meth)acrylates, acrylic (meth)acrylates, and / or urethane (meth)acrylates. Compound b is selected from zinc stearate and / or calcium stearate, and the fatty acid is selected from C16–C18 fatty acids. Composition II consists of 2–40 wt% of composition I and 0–20 wt% of one or more matting agents d, different from compound b. After radiation curing, the matting composition II yields a matte coating with a gloss level of up to 15 GU at a 60° angle and up to 50 GU at an 85° angle, at a cured film thickness of 12 μm. This low-gloss coating after radiation curing can be applied to almost any substrate material requiring matting, and requires only a small amount of inorganic matting agents (SiO2 and / or waxes, etc.), resulting in a low overall viscosity of the composition and no increase in application difficulty. However, the matting effect of this low-gloss coating is not significant, and its mechanical properties are poor after radiation curing, failing to provide adequate protection for the substrate.

[0004] Simple matting agents, such as silica and wax, often require an addition of 5–10 wt%, or even 15 wt%, to achieve the desired matting effect due to polarity and compatibility issues. This results in high system viscosity, making it difficult to mix evenly and negatively impacting the mechanical, optical, and weather-resistant properties of the final product. Consequently, they fail to protect the substrate material.

[0005] Using a solvent-resin system to reduce the overall viscosity can effectively solve the problem of excessively high viscosity in polymer-resin mixtures after adding matting agents. However, the need to completely remove the solvent after processing and molding is a difficult problem to solve, and solvent systems often cause unnecessary environmental pollution.

[0006] Patent document JP60094413A discloses a crosslinked acrylic copolymer with a matting effect. This crosslinked acrylic copolymer is obtained by dispersing alkyl acrylates, alkyl methacrylates, copolymerizable olefin monomers, and copolymerizable monomers with at least two intramolecular double bonds (such as ethylene glycol dimethacrylate) in water, adding an initiator and a surfactant, and then polymerizing. Because the crosslinked structure of the acrylic copolymer presents a micro-wrinkled state on the surface, it has a self-matting effect, eliminating the need to add any matting agent. However, the gloss of this copolymer coating is 25 GU under a 60° light source, indicating a poor matting effect that fails to meet most matting requirements.

[0007] Patent document CN111072853A discloses a method for preparing a self-matting waterborne acrylic resin. First, acrylates are modified with long-chain alkylsilanes. Then, 20-30 parts of deionized water, 2.5-7.5 parts of emulsifier, 8-20 parts of long-chain alkylsilane-modified acrylates, 8-20 parts of acrylates, 0.3-2 parts of hydroxyl-containing acrylics, 5-15 parts of styrene, and 0.5-1.8 parts of acrylic monomers are added to a reactor. After polymerization, the self-matting waterborne acrylic resin is obtained. This resin exhibits low gloss (11.2 GU at 60° light source) and high toughness after film formation. However, the modified waterborne acrylic resin has poor weather resistance after film formation and cannot adapt to harsh environments.

[0008] Acrylic (ester) resin molecules contain certain functional groups, making them easy to crosslink; therefore, self-matting technology is mostly applicable to acrylic (ester) resins. However, fluoropolymers are mostly linear or branched structures, making it difficult to perform multi-component crosslinking with a wide molecular weight; so far, they have not been used in the field of self-matting.

[0009] Currently available matte coatings and protective films are mostly used indoors. Due to their lack of good weather resistance and mechanical properties, they cannot meet the requirements of outdoor environments. Therefore, there is a need to develop a protective film with low gloss, high weather resistance, and good mechanical properties. Summary of the Invention

[0010] To solve the above-mentioned technical problems, the present invention prepares modified acrylate microspheres with ultraviolet absorption by grafting organic ultraviolet absorbers onto acrylate microspheres with reactive groups. The microspheres are located on the surface of the matting layer that does not contact the substrate layer, which is equivalent to forming an ultraviolet absorber layer on the film surface, thus preventing ultraviolet rays from being absorbed by the film and affecting its weather resistance.

[0011] This invention provides a low-gloss, high-weather-resistant fluoropolymer film, comprising a matte layer and a substrate layer.

[0012] The matte layer components, by mass parts, include:

[0013] 75-90 PVDF samples

[0014] PMMA 10-25 parts,

[0015] 0.5–2 parts of organic ultraviolet absorber,

[0016] Acrylic microspheres with reactive groups, D50 of 3–4.5 μm, refractive index of 1.4–1.5, 1–5 parts.

[0017] The organic UV absorber and acrylate microspheres with reactive groups are bonded together to form modified acrylate microspheres with UV absorption properties.

[0018] The matrix layer components, by mass parts, include:

[0019] 65-80 parts of PVDF

[0020] PMMA 20-35 copies.

[0021] The surface roughness of the matting layer on the side not in contact with the substrate layer, as described in this invention, has an Ra (arithmetic profile mean deviation) of 0.5–0.95 μm and an Rz (maximum profile height) of 1.19–1.42 μm. When the surface roughness is too low, the matting performance is poor; when the surface roughness is too high, the film surface has a poor tactile feel and poor mechanical properties.

[0022] The surface roughness testing method described in this invention is as follows: Testing is performed using a Beijing Times TR210 high-precision roughness meter. Each thin film sample is tested five times, and the average value is calculated based on all measured values. The testing conditions are: test temperature 25℃, test humidity 55-65% RH, filter type: RC, sensor type: inductive, tip radius / angle: 5μm / 90°, tip material: diamond, sampling length L: 0.25mm, evaluation length 4L. Note that the sampling length should be sufficiently short when measuring the surface roughness profile to limit or reduce waviness and eliminate the influence of shape errors on the surface roughness profile measurement.

[0023] The modified acrylate microspheres with UV absorption properties described in this invention are prepared by grafting an organic UV absorber onto acrylate microspheres containing reactive groups. The bonding of the organic UV absorber and the acrylate microspheres with reactive groups is completed in a twin-screw extruder at a processing temperature of 230–250°C. The modified acrylate microspheres with UV absorption properties can be uniformly dispersed under the high pressure and high shear of the twin-screw extruder. The cross-linked structure of the acrylate microspheres prevents them from melting during film processing.

[0024] The organic ultraviolet absorber of the present invention can be grafted onto acrylate microspheres. Preferably, the organic ultraviolet absorber is selected from at least one of 2-[2-hydroxy-4-[3-(2-ethylhexyloxy)-2-hydroxypropoxy]phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[2-hydroxy-3-tetrazoloxypropyl]oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, [4-[3-(decoxy)-2-hydroxypropoxy]-2-hydroxyphenyl]phenyl ketone, and [2'-hydroxy-5'-methacryloyloxy]ethylphenyl]-2H-benzotriazole.

[0025] The acrylate microspheres with reactive groups described in this invention are selected from at least one of acrylate carboxyl microspheres, acrylate amino microspheres, and acrylate epoxy microspheres.

[0026] The PVDF described in this invention is a homopolymer of vinylidene fluoride, or a copolymer of vinylidene fluoride and a fluorinated monomer. The fluorinated monomer is selected from at least one of vinyl fluoride, trifluoroethylene, tetrafluoroethylene, hexafluoropropylene, and trifluorochloroethylene.

[0027] The PMMA described in this invention has a melt flow rate of 0.5 to 25 g / 10 min at 230°C and a load of 5 kg, preferably 2 to 10 g / 10 min.

[0028] The matting layer of the present invention provides matting and ultraviolet absorption effects for the film, and its thickness is greater than or equal to the diameter of the modified acrylate microspheres with ultraviolet absorption. Preferably, the thickness of the matting layer is 3 to 5 μm.

[0029] The substrate layer of the present invention provides mechanical strength, water vapor barrier properties and aging resistance to the thin film, and its thickness should meet the application requirements of the thin film. Preferably, the thickness of the substrate layer is 10-15 μm.

[0030] The average particle size d of the modified acrylate microspheres with UV absorption properties described in this invention satisfies the following relationship with the fluoropolymer film t: Under certain conditions, the film thickness must be within this range to ensure both the extinction performance and the mechanical properties of the film.

[0031] The organic ultraviolet absorber described in this invention can absorb ultraviolet light of a specific wavelength and dissipate the ultraviolet energy in the form of heat. Through grafting with acrylate microspheres containing reactive groups, it is uniformly distributed in the matting layer, giving the matting layer ultraviolet absorption properties. This protects the substrate material from aging and damage caused by ultraviolet radiation, while also solving the problem of easy migration and precipitation of the ultraviolet absorber, ensuring its long-term effectiveness.

[0032] The modified acrylate microspheres with UV absorption properties described in this invention are uniformly distributed on the surface of the matting layer. The microspheres floating on the surface cause the surface of the matting layer to bulge, forming a surface roughness and providing a matting effect.

[0033] The acrylate microspheres with reactive groups described in this invention, after being grafted with an organic ultraviolet absorber, retain a refractive index of approximately 1.4 to 1.5, which is similar to that of PVDF resin, and therefore does not affect the transparency of the film.

[0034] This invention also provides a method for preparing a low-gloss, high-weather-resistant fluoropolymer film, comprising the following steps:

[0035] (1) After premixing acrylate microspheres with active reactive groups and organic UV absorbers, PVDF and PMMA are added and mixed.

[0036] (2) A mixed matrix layer of PVDF and PMMA

[0037] (3) The mixed materials are co-extruded in two layers to produce a film. The extruder processing temperature is 230-250℃ and the co-extrusion die temperature is 240-260℃.

[0038] Furthermore, the film thickness is controlled by adjusting the feeding speed of the upper and lower extruders and the rotation speed of the casting rollers.

[0039] In step (1), the premixing speed is 20-40 r / min and the time is 5-15 min; the mixing speed after adding PVDF and PMMA is 20-40 r / min and the mixing time is 10-25 min.

[0040] In step (2), the mixing speed of the matrix layer is 20-40 r / min and the time is 10-25 min.

[0041] In step (3), the feeding speed of the upper extruder in the double-layer co-extrusion is 1-5 r / min and the temperature is 230-250℃; the feeding speed of the lower extruder is 5-25 r / min and the temperature is 235-255℃; the speed of the casting roll is 1-10 r / min.

[0042] This invention also provides an application of a low-gloss, high-weather-resistant fluoropolymer film, which serves as a durable protective film for building exteriors and automotive window tinting. As a durable protective film for building exteriors, it is used in awnings, bridges, etc., and can be exposed to harsh weather environments for extended periods, including extremely hot and humid summers and cold, rainy, and snowy winters. The film provided by this invention not only provides a low-gloss visual aesthetic but also reduces "light pollution" caused by severe light reflection in cities to a certain extent.

[0043] Compared with existing technologies, the present invention has the following advantages: by using modified acrylate microspheres with UV absorption properties in the matting layer, not only does the film have good matting properties, but the UV absorber is also grafted onto the surface of the acrylate microspheres, which is equivalent to covering the surface of the matting layer with a layer of UV absorber, thus improving weather resistance while preventing the migration of UV absorber. Furthermore, the refractive index of the modified acrylate microspheres is similar to that of fluoropolymers, ensuring the light transmittance of the film. Attached Figure Description

[0044] Figure 1 This is a cross-sectional view of the fluoropolymer film obtained in Example 1. 1 is the substrate layer, 2 is the matting layer, and 3 is the modified acrylate microsphere with ultraviolet absorption. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternatives, improvements, and equivalents that may be included within the scope of the claims.

[0046] The raw materials used in the embodiments of this invention are sourced as follows: PVDF (polyvinylidene fluoride): Solef PVDF 6010; PMMA (polymethyl methacrylate): Dow Paraaloid B64; organic ultraviolet absorbers: BASF UV-405, UV-400, UV-950, RUVA-93; acrylate microspheres with reactive groups: SRSH-CPMA-30-10 series acrylate microspheres; silica matting agent: GRACE C803.

[0047] Example 1

[0048] Matting layer composition: 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.5 μm, refractive index 1.45), 1.5 parts UV-405 ultraviolet absorber;

[0049] Matrix layer composition: 75 parts PVDF resin, 25 parts PMMA resin;

[0050] Film preparation process: Each layer component was formulated separately. When formulating the matte layer component, acrylate carboxyl microspheres and UV-405 ultraviolet absorber were premixed at 30 rpm for 10 minutes. This mixture was then added to a kneader along with PVDF and PMMA resins and thoroughly mixed at 30 rpm for 15 minutes. After both the matte layer and matrix layer formulations were prepared, they were fed to the feed ports of the two extruders in the double-layer co-extrusion unit via a feeder. The matte layer formulation was fed into the upper extruder, and the matrix layer formulation into the lower extruder. The upper extruder was set with a feeding speed of 2 rpm and a processing temperature of 230°C; the lower extruder was set with a feeding speed of 10 rpm and a processing temperature of 235°C. The co-extrusion die temperature was 240°C, and the casting roll speed was 3.5 rpm, resulting in a double-layer co-extruded fluoropolymer film with a total thickness of 15.2 μm.

[0051] Example 2

[0052] Same as Example 1, except that the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate amino microspheres (D50 = 3.7 μm, refractive index 1.47), and 1.5 parts RUVA-93 UV absorber. The casting roller speed is 3.4 r / min, and the total thickness of the fluoropolymer film is 17.4 μm.

[0053] Example 3

[0054] Same as Example 1, except that the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate epoxy microspheres (D50 = 3.6 μm, refractive index 1.48), and 1.5 parts UV-400 ultraviolet absorber. The casting roller speed is 3.3 r / min, and the total thickness of the fluoropolymer film is 18.8 μm.

[0055] Example 4

[0056] Same as Example 1, except that the matte layer composition consists of 75 parts PVDF resin, 25 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.4 μm, refractive index 1.45), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.6 r / min, and the total thickness of the fluoropolymer film is 13.9 μm.

[0057] Example 5

[0058] Same as Example 1, except that the matte layer composition consists of 90 parts PVDF resin, 10 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.5 μm, refractive index 1.45), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.5 r / min, and the total thickness of the fluoropolymer film is 15.3 μm.

[0059] Example 6

[0060] Same as Example 1, except that the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.4 μm, refractive index 1.45), and 0.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.4 r / min, and the total thickness of the fluoropolymer film is 17.8 μm.

[0061] Example 7

[0062] Same as Example 1, except that the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.4 μm, refractive index 1.45), and 2 parts UV-405 ultraviolet absorber. The casting roller speed is 3.5 r / min, and the total thickness of the fluoropolymer film is 15.9 μm.

[0063] Example 8

[0064] Same as Example 1, except that the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 1 part acrylate carboxyl microspheres (D50 = 3.5 μm, refractive index 1.45), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.3 r / min, and the total thickness of the fluoropolymer film is 19.2 μm.

[0065] Example 9

[0066] Same as Example 1, except that the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 5 parts acrylate carboxyl microspheres (D50 = 3.5 μm, refractive index 1.45), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.3 r / min, and the total thickness of the fluoropolymer film is 18.5 μm.

[0067] Example 10

[0068] Same as Example 1, except that the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.4 μm, refractive index 1.45), 0.75 parts UV-405 ultraviolet absorber, and 0.75 parts UV-400 ultraviolet absorber. The casting roller speed is 3.6 r / min, and the total thickness of the fluoropolymer film is 13.3 μm.

[0069] Example 11

[0070] Same as Example 1, except that the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 1.5 parts acrylate carboxyl microspheres (D50 = 3.5 μm, refractive index 1.45), 1.5 parts acrylate epoxy microspheres (D50 = 3.6 μm, refractive index 1.48), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.5 r / min, and the total thickness of the fluoropolymer film is 14.6 μm.

[0071] Comparative Example 1

[0072] Matting layer composition: 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate microspheres (without reactive groups, D50 = 3.3 μm, refractive index 1.47), 1.5 parts UV-405 ultraviolet absorber;

[0073] Matrix layer composition: 75 parts PVDF resin, 25 parts PMMA resin;

[0074] The specific film preparation process is as follows: Each component is formulated separately and thoroughly mixed using a kneader (30 rpm for 15 minutes). After mixing, the two formulations are fed into the feed inlets of the two extruders in a double-layer co-extrusion unit via a feeder. The matte layer formulation is fed into the upper extruder feed inlet, and the matrix layer formulation is fed into the lower extruder feed inlet. The upper extruder feed rate is set to 2 rpm, and the processing temperature to 230℃; the lower extruder feed rate is set to 10 rpm, and the processing temperature to 235℃. The co-extrusion die temperature is 240℃, and the casting roll speed is 3.6 rpm, resulting in a double-layer co-extruded fluoropolymer film with a total thickness of 13.8 μm.

[0075] Comparative Example 2

[0076] Similar to Comparative Example 1, but with the following differences: the matting layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 3 parts silica matting agent (D50 = 3.7 μm, oil absorption 320 g / 100 g, pore volume 2 ml / g), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.4 r / min, and the total thickness of the fluoropolymer film is 17.1 μm.

[0077] Comparative Example 3

[0078] The complete formulation consists of: 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.5 μm, refractive index 1.45), and 1.5 parts UV-405 ultraviolet absorber.

[0079] The specific film preparation process is as follows: The film is formulated according to the component recipe and thoroughly mixed using a kneader (30 rpm for 20 minutes). After mixing, the formula components are transported to the feed inlet of a twin-screw extruder via a feeder for extrusion film formation. The feeding speed is set to 12 rpm, the processing temperature to 235℃, the die temperature to 240℃, and the casting roller speed to 3.5 rpm, resulting in a fluoropolymer film with a total thickness of 15.0 μm.

[0080] Comparative Example 4

[0081] Similar to Comparative Example 1, but with the following differences: the matte layer composition consists of 70 parts PVDF resin, 30 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.5 μm, refractive index 1.45), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.3 r / min, and the total thickness of the fluoropolymer film is 17.7 μm.

[0082] In this comparative example, the fluoropolymer film exhibited surface cracking of the matte layer during mechanical property testing.

[0083] Comparative Example 5

[0084] Similar to Comparative Example 1, but with the following differences: the matte layer composition consists of 95 parts PVDF resin, 5 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.5 μm, refractive index 1.45), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.4 r / min, and the total thickness of the fluoropolymer film is 16.8 μm.

[0085] Comparative Example 6

[0086] Similar to Comparative Example 1, but with the following differences: the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.4 μm, refractive index 1.47), and 0.3 parts UV-405 ultraviolet absorber. The casting roller speed is 3.4 r / min, and the total thickness of the fluoropolymer film is 16.2 μm.

[0087] Comparative Example 7

[0088] Similar to Comparative Example 1, but with the following differences: the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 3 parts acrylate carboxyl microspheres (D50 = 3.6 μm, refractive index 1.45), and 3 parts UV-405 ultraviolet absorber. The casting roller speed is 3.4 r / min, and the total thickness of the fluoropolymer film is 16.5 μm.

[0089] Comparative Example 8

[0090] Similar to Comparative Example 1, but with the following difference: the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 0.5 parts acrylate carboxyl microspheres (D50 = 3.6 μm, refractive index 1.44), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.5 r / min, and the total thickness of the fluoropolymer film is 15.5 μm.

[0091] Comparative Example 9

[0092] Similar to Comparative Example 1, but with the following difference: the matte layer composition consists of 80 parts PVDF resin, 20 parts PMMA resin, 6 parts acrylate carboxyl microspheres (D50 = 3.5 μm, refractive index 1.46), and 1.5 parts UV-405 ultraviolet absorber. The casting roller speed is 3.5 r / min, and the total thickness of the fluoropolymer film is 15.8 μm.

[0093] In this comparative example, the surface of the fluoropolymer film is rough and not smooth, and cracks appeared on the surface of the matte layer during mechanical property testing.

[0094] The formulations of the fluoropolymer films in the examples and comparative examples are shown in Table 1, and the surface roughness and thickness of the fluoropolymer films in the examples and comparative examples are shown in Table 2.

[0095] Table 1. Formulations of fluoropolymer films in the examples and comparative examples.

[0096]

[0097]

[0098] Table 2. Surface roughness and thickness of fluoropolymers in the examples and comparative examples.

[0099] Thickness t / μm d / t Ra / μm Rz / μm Example 1 15.2 0.23 0.84 1.35 Example 2 17.4 0.21 0.62 1.25 Example 3 18.8 0.19 0.54 1.2 Example 4 13.9 0.24 0.9 1.39 Example 5 15.3 0.23 0.84 1.34 Example 6 17.8 0.19 0.59 1.24 Example 7 15.9 0.21 0.75 1.3 Example 8 19.2 0.18 0.5 1.19 Example 9 18.5 0.19 0.56 1.23 Example 10 13.3 0.26 0.95 1.42 Example 11 14.6 0.24 0.87 1.37 Comparative Example 1 13.8 0.24 0.91 1.4 Comparative Example 2 17.1 0.22 0.71 1.26 Comparative Example 3 15 0.23 0.85 1.35 Comparative Example 4 17.7 0.2 0.6 1.24 Comparative Example 5 16.8 0.21 0.66 1.27 Comparative Example 6 16.2 0.21 0.72 1.29 Comparative Example 7 16.5 0.22 0.7 1.29 Comparative Example 8 15.5 0.23 0.81 1.32 Comparative Example 9 15.8 0.22 0.77 1.3

[0100] Test case

[0101] The performance of the fluoropolymer films in the test examples and comparative examples is detailed in Table 3.

[0102] Table 3 Performance test data of fluoropolymer films in the examples and comparative examples

[0103]

[0104]

[0105] Note: PCT conditions: 121℃, 2 atms, 48h.

[0106] Ultraviolet irradiation conditions: Total ultraviolet irradiation is 150 kWh / m 2 .

[0107] Gloss was tested according to ASTM D2457-2013; transmittance was tested according to GB / T 2410-2008; ultraviolet transmittance was tested according to GB / T 2680-2021; water vapor transmittance was tested according to the cup weight reduction method in GB / T 1037-2021; tensile strength and elongation at break were tested according to ASTM D882-2018.

[0108] The data in the table show that Comparative Example 1, which added acrylate microspheres without reactive groups, could not bond with the UV absorber. The UV absorber easily migrated from the film surface after environmental testing, leading to a deterioration in UV transmittance after PCT. Comparative Example 2 added silica matting agent, which provided good matting effect; however, because silica cannot bond with the UV absorber, the deterioration in UV transmittance after PCT was not improved. Furthermore, the addition of silica caused the film surface to become hazy and white, significantly impacting transmittance. Comparative Example 3 added acrylate microspheres modified with a UV absorber to the complete formulation, improving the film's matting and UV resistance. However, due to the lack of a matrix layer, the overall transmittance and mechanical properties of the film were significantly lower than in the examples.

[0109] In Comparative Example 4, the addition of excessive PMMA to the matting layer increased the stiffness of the matting layer, but degraded its mechanical properties. In Comparative Example 5, the addition of excessive PVDF to the matting layer degraded the compatibility of the UV absorber-modified acrylate microspheres. In Comparative Examples 6 and 7, the amounts of UV absorber added were 0.3 parts and 3 parts, respectively. In Comparative Example 6, the film's UV resistance was insufficient, and in Comparative Example 7, the addition of excessive UV absorber caused film discoloration and degraded light transmittance. In Comparative Examples 8 and 9, the amounts of acrylate microspheres added were 0.5 parts and 6 parts, respectively. In Comparative Example 8, the matting properties were insufficient and the retention rate of mechanical properties after UV irradiation decreased significantly. In Comparative Example 9, the addition of excessive acrylate microspheres caused the film surface to be prone to cracking and to have a rough and uneven surface.

Claims

1. A low-gloss, high-weatherability fluorine-containing polymer film comprising a matte layer and a base layer, characterized in that: The extinction layer component comprises, by mass fraction: PVDF 75-90 parts, PMMA 10-25 parts, organic ultraviolet absorber 0.5-2 parts, acrylic ester microspheres with reactive groups, D50 3-4.5 μm, refractive index 1.4-1.5, 1-5 parts, the organic ultraviolet absorber and the acrylic ester microspheres with reactive groups are bonded to form modified acrylic ester microspheres with ultraviolet absorption, and the refractive index is still 1.4-1.5, the matrix layer component comprises, by mass fraction: PVDF 65-80 parts, PMMA 20-35 parts; The average particle diameter d of the modified acrylate microspheres having ultraviolet absorbability and the thickness t of the fluorine-containing polymer film satisfy provided that, The acrylic ester microspheres with reactive groups are selected from at least one of acrylic ester carboxyl microspheres, acrylic ester amino microspheres, and acrylic ester epoxy microspheres.

2. The low-gloss, high-weatherability fluoropolymer film according to claim 1, wherein: The surface roughness Ra of the non-contact surface of the extinction layer with the matrix layer is 0.5-0.95 μm, and the Rz is 1.19-1.42 μm.

3. The low-gloss, high-weatherability fluoropolymer film according to claim 1, wherein: The thickness of the extinction layer is 3-5 μm, and the thickness of the matrix layer is 10-15 μm.

4. The low-gloss, high-weatherability fluoropolymer film of claim 1, wherein: The bonding of the organic ultraviolet absorber and the acrylic ester microspheres with reactive groups is completed in a twin-screw extruder, and the processing temperature of the twin-screw extruder is 230-250 °C.

5. The low-gloss, high-weatherability fluoropolymer film of claim 1, wherein: The organic ultraviolet absorber is selected from at least one of 2-[2-hydroxy-4-[3-(2-ethylhexyloxy)-2-hydroxypropoxy]phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[2-hydroxy-3-tridecyloxypropyl]oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, and [4-[3-(decyloxy)-2-hydroxypropoxy]-2-hydroxyphenyl]phenyl ketone.

6. The low-gloss, high-weatherability fluoropolymer film of claim 1, wherein: The PVDF is a homopolymer of vinylidene fluoride or a copolymer of vinylidene fluoride and a fluorine-containing monomer.

7. The low-gloss, high-weatherability fluoropolymer film according to claim 6, wherein: The fluorine-containing monomer is selected from at least one of vinyl fluoride, trifluoroethylene, tetrafluoroethylene, hexafluoropropylene, and chlorotrifluoroethylene.

8. The low-gloss, high-weather-resistant fluoropolymer film according to any one of claims 1-7, characterized in that: The low-gloss, high-weather-resistant fluoropolymer film is applied as a durable protective film to building exterior walls and car stickers.

Images