Gradient-transmittance double-shielding low-reflection film material and preparation method and application thereof

Abstract

The invention relates to the technical field of automobile glass intermediate films, in particular to a gradient transmissivity double-shielding low-reflection film material and a preparation method and application thereof. The invention provides a gradient transmissivity double-shielding low-reflection film material. The gradient transmissivity double-shielding low-reflection film material comprises a modified polyvinyl acetal resin film and a gradient coloring belt connected with the edge of one side of the modified polyvinyl acetal resin film, from the edge end to the connecting end, the visible light transmittance of the gradient coloring belt is increased from 15-20% to 25-30%; and micro-nano textures are arranged on the surface of one side of the gradient coloring belt. On the basis of guaranteeing the anti-dazzling performance, through structure and function combination, infrared and ultraviolet double shielding, visual balance and good weather resistance and adhesiveness are synchronously achieved, the problems of visual fault, interface reflection interference and the like of existing automobile front windshield laminated glass are systematically solved, and the performance requirement of the automobile front windshield laminated glass is met.

Description

Technical Field

[0001] This invention relates to the field of automotive glass interlayer film technology, and in particular to a gradient transmittance double-shielded low-reflection film material, its preparation method, and its application. Background Technology

[0002] Laminated glass, a common type of safety glass, contains a polyvinyl butyral (PVB) interlayer. The PVB interlayer's adhesive properties prevent fragments from scattering easily when the laminated glass breaks, making it widely used in automotive windshields. However, while existing laminated glass offers significant safety benefits, it also has some notable drawbacks, such as glare during driving.

[0003] To address the aforementioned glare problem, Japanese Patent JP2004-123424A discloses an interlayer film for automotive windshield laminated glass. This interlayer film has a colored strip with a visible light transmittance of less than 30% at its lower edge, achieving functions such as preventing glare from road surface reflections and concealing objects inside the vehicle, thereby improving driving safety and aesthetics to a certain extent.

[0004] However, the above-mentioned technologies still have the following shortcomings: First, the coloring strip adopts a uniform and fixed transmittance design, and there is a significant visual discontinuity at the interface between the lower strong light-blocking area and the upper transparent area, which can easily interfere with the continuity of the driver's vision and cause driver visual fatigue with long-term use; Second, the coloring strip relies solely on coloring pigments to achieve basic light and heat shielding, and its shielding efficiency for the infrared band in the solar spectrum is limited. Under strong sunlight in summer, it can still easily lead to excessively high temperatures inside the vehicle, which not only affects driving comfort but also accelerates the photoaging of the interior and dashboard; Third, the coloring strip has a high reflectivity at the interface with air and glass, which can easily generate secondary reflection interference, especially at night or in backlight conditions, which may affect driving safety; Fourth, there is still room for improvement in the weather resistance and adhesion of the substrate. Long-term exposure to outdoor environments may cause problems such as fading of the coloring strip and peeling from the glass, affecting the product's service life. Summary of the Invention

[0005] In view of this, the present invention provides a graded transmittance double-shielded low-reflection film material, its preparation method and application. The graded transmittance double-shielded low-reflection film material provided by the present invention has the advantages of anti-glare, infrared and ultraviolet double shielding, visual balance, good weather resistance and adhesion, and excellent comprehensive performance.

[0006] This invention provides a gradient transmittance dual-shielding low-reflection film material, comprising a modified polyvinyl acetal resin film and a gradient-colored strip connected to one edge of the modified polyvinyl acetal resin film; the modified polyvinyl acetal resin film comprises polyvinyl acetal resin, a coupling agent, and an antioxidant; the gradient-colored strip comprises polyvinyl acetal resin, a coupling agent, an antioxidant, an infrared absorber, an ultraviolet absorber, and a compound coloring pigment; from the edge end to the connection end, the visible light transmittance of the gradient-colored strip increases from 15~20% to 25~30%; one side surface of the gradient-colored strip is provided with micro-nano textures.

[0007] Preferably, the polyvinyl acetal resin includes polyvinyl butyral (PVB); the average degree of polymerization of the polyvinyl butyral is 500-3000, the degree of acetylation is 50-75 mol%, and the residual acetyl content is 0.5-24 mol%.

[0008] Preferably, the coupling agent is a silane coupling agent.

[0009] Preferably, the antioxidant is a hindered phenolic antioxidant.

[0010] Preferably, the infrared absorber accounts for 3-8% of the total mass of the gradient coloring strip; the ultraviolet absorber accounts for 0.5-1% of the total mass of the gradient coloring strip; the compound coloring pigment includes phthalocyanine blue and titanium dioxide; the mass ratio of phthalocyanine blue to titanium dioxide is 0.9-1.1:2; and the mass of the compound coloring pigment accounts for 0.4-10% of the total mass of the gradient coloring strip.

[0011] Preferably, the micro-nano texture includes a periodic concave-convex structure; the texture depth of the micro-nano texture is 80~150 nanometers, and the period is 150~250 nanometers; the surface reflectivity of the micro-nano texture is not higher than 2%; the gradient of the visible light transmittance of the gradient coloring band is 0.5~2% / cm.

[0012] The present invention also provides a method for preparing the graded transmittance double-shielded low-reflection film material described above, comprising the following steps: (1) Mix polyvinyl acetal resin, coupling agent and antioxidant to obtain modified polyvinyl acetal resin film mixture; (2) Mix polyvinyl alcohol acetal resin, coupling agent, antioxidant, infrared absorber, ultraviolet absorber and compound coloring pigment to obtain gradient coloring band mixture; (3) The modified polyvinyl alcohol acetal resin film mixture and the gradient coloring tape mixture are melted and extruded separately and then fed into a composite die head with a gradient flow channel and a micro-nano textured pressure roller for composite and molding to obtain the gradient transmittance double shielding low reflection film material. There is no requirement for the time order of steps (1) and (2).

[0013] The present invention also provides the application of the graded transmittance double-shielded low-reflection film material described in the above-described scheme or the graded transmittance double-shielded low-reflection film material obtained by the preparation method described in the above-described scheme in the field of laminated glass.

[0014] The present invention also provides a laminated windshield glass for automobiles, comprising an interlayer film and glass plates bonded to both sides of the interlayer film; the interlayer film comprises the gradient transmittance double-shielded low-reflection film material described in the above-described scheme or the gradient transmittance double-shielded low-reflection film material obtained by the preparation method described in the above-described scheme; the gradient coloring band of the gradient transmittance double-shielded low-reflection film material is located at the lower end of the laminated windshield glass for automobiles.

[0015] The present invention also provides a method for preparing the automotive windshield laminated glass described above, comprising the following steps: The interlayer film is placed between two glass plates and pre-pressed and then pressed in sequence to obtain the automotive windshield laminated glass.

[0016] This invention provides a graded transmittance double-shielded low-reflection film material. While ensuring anti-glare performance, this invention achieves simultaneous infrared and ultraviolet double shielding, visual balance, good weather resistance, and adhesion through structural and functional integration. It systematically solves the problems of visual distortion and interface reflection interference in existing automotive windshield laminated glass, meeting the performance requirements of automotive windshield laminated glass. Specifically: 1) This invention solves the visual discontinuity problem between the colored strip and the transparent area by using a gradient transmittance. The low transmittance (15~20%) on the lower side can effectively ensure the concealment of the dashboard and the anti-road reflection effect. The upper side gradually transitions to a high transmittance (25~30%), which is naturally connected with the transparent area, significantly improving the continuity of the driver's vision and reducing driver visual fatigue. 2) This invention achieves infrared-ultraviolet dual shielding function through the synergistic effect of composite functional additives. The infrared absorption rate is not less than 85%, which can reduce the temperature inside the car by 3-5 degrees Celsius in summer, reduce air conditioning energy consumption, and improve driving comfort. The ultraviolet absorption rate is not less than 99%, which can effectively block ultraviolet rays, delay the photoaging of the interior and dashboard, and extend the service life of the car interior. 3) This invention uses a micro-nano texture structure to control the surface reflectivity of the colored strip to below 2%, which can effectively eliminate secondary reflection interference at the interface. Especially in nighttime or backlighting environments, it can significantly improve the clarity of the driver's field of vision by 15-20%, ensuring driving safety. 4) This invention modifies polyvinyl acetal resin with coupling agents and antioxidants, which not only significantly improves its adhesion to glass (peel strength to glass not less than 18 N / cm), ensuring a firm bond with glass and preventing peeling during use, but also enhances weather resistance (color difference ΔE not higher than 2 after 1500 hours of xenon lamp aging), avoiding problems such as peeling or fading after long-term use, and extending the product's service life.

[0017] This invention also provides a method for preparing the gradient transmittance double-shielded low-reflection film material described in the above-mentioned scheme. The preparation method provided by this invention has simple steps, is easy to operate, has stable processes, and is compatible with existing production processes. It does not require new special equipment, can be directly adapted to industrial production, meets the windshield requirements of different vehicle models, and has broad application prospects.

[0018] This invention also provides the application of the graded transmittance double-shielded low-reflection film material described in the above-described scheme or the graded transmittance double-shielded low-reflection film material prepared by the above-described scheme in the field of laminated glass. The graded transmittance double-shielded low-reflection film material provided by this invention has functions such as anti-glare, infrared and ultraviolet double shielding, visual balance, weather resistance and good adhesion. It has excellent comprehensive performance and is suitable as an interlayer film for laminated glass, especially for applications such as automotive windshields.

[0019] This invention also provides a laminated windshield glass for automobiles, wherein the interlayer film is made of the gradient transmittance double-shielded low-reflection film material described in the above-described scheme or the gradient transmittance double-shielded low-reflection film material prepared by the above-described scheme. The laminated windshield glass for automobiles provided by this invention has an anti-glare function, achieves infrared and ultraviolet double shielding and visual balance effects, has good weather resistance and adhesion, demonstrates significant overall performance, and is cost-effective.

[0020] This invention also provides a method for preparing the laminated windshield glass for automobiles described above. The preparation method provided by this invention is convenient to operate, safe, reliable, and cost-effective. Detailed Implementation

[0021] This invention provides a gradient transmittance dual-shielding low-reflection film material, comprising a modified polyvinyl acetal resin film and a gradient-colored strip connected to one edge of the modified polyvinyl acetal resin film; the modified polyvinyl acetal resin film comprises polyvinyl acetal resin, a coupling agent, and an antioxidant; the gradient-colored strip comprises polyvinyl acetal resin, a coupling agent, an antioxidant, an infrared absorber, an ultraviolet absorber, and a compound coloring pigment; from the edge end to the connection end, the visible light transmittance of the gradient-colored strip increases from 15~20% to 25~30%; one side surface of the gradient-colored strip is provided with micro-nano textures.

[0022] The gradient transmittance dual-shielding low-reflection film material provided by this invention comprises a modified polyvinyl acetal resin film; the polyvinyl acetal resin preferably comprises polyvinyl butyral (PVB); the average degree of polymerization of the polyvinyl butyral is preferably 500-3000, the degree of acetylation is preferably 50-75 mol%, and the residual acetyl group content is preferably 0.5-24 mol%. The polyvinyl acetal resin using the above parameters in this invention ensures that the material possesses both good processability and mechanical properties.

[0023] In this invention, the coupling agent is preferably a silane coupling agent; the silane coupling agent preferably includes γ-aminopropyltriethoxysilane.

[0024] In this invention, the antioxidant is preferably a hindered phenolic antioxidant; the hindered phenolic antioxidant preferably includes one or more of type 1010 antioxidants and type 1076 antioxidants.

[0025] In this invention, the modified polyvinyl acetal resin film preferably comprises 100 parts of polyvinyl acetal resin, 0.8 to 1.5 parts of coupling agent, more preferably 1 to 1.2 parts of antioxidant, and 1 to 3 parts of antioxidant, more preferably 1.5 to 1.8 parts of antioxidant.

[0026] In this invention, the thickness of the modified polyvinyl acetal resin film is preferably 0.3 to 1.6 mm, more preferably 0.6 to 1.2 mm, and even more preferably 1 mm.

[0027] In this invention, the types and mass fractions of polyvinyl acetal resin, coupling agent and antioxidant in the gradient coloring strip are the same as those in the modified polyvinyl acetal resin film, and will not be repeated here.

[0028] In this invention, the infrared absorber preferably comprises antimony-doped tin oxide (ATO) powder; the particle size of the infrared absorber is preferably 1-5 micrometers, more preferably 2-4 micrometers.

[0029] In this invention, the infrared absorber preferably accounts for 3 to 8% of the total mass of the gradient coloring strip, more preferably 4 to 7%, and even more preferably 5 to 6%.

[0030] In this invention, the ultraviolet absorber preferably includes 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

[0031] In this invention, the mass of the ultraviolet absorber preferably accounts for 0.5 to 1% of the total mass of the gradient coloring band, more preferably 0.6 to 0.9%, and even more preferably 0.7 to 0.8%.

[0032] In this invention, the compound coloring pigment preferably includes phthalocyanine blue and titanium dioxide; the mass ratio of phthalocyanine blue to titanium dioxide is preferably 0.9~1.1:2, more preferably 1:2.

[0033] In this invention, the mass of the compound coloring pigment preferably accounts for 0.4 to 10% of the total mass of the gradient coloring band, more preferably 1 to 8%, and even more preferably 3 to 5%.

[0034] In this invention, the gradient coloring strip is preferably connected to the lower edge of the modified polyvinyl acetal resin film, and the visible light transmittance of the gradient coloring strip increases continuously from bottom to top in the vertical direction; the gradient of the visible light transmittance of the gradient coloring strip is preferably 0.5~2% / cm.

[0035] In this invention, the color of the gradient coloring band is preferably dark gray, and the color coordinates preferably satisfy: L =20~30, a =-2~2 and b =-3~3. The above colors are used in this invention to better match the interior styles of different car models and enhance the decorative effect.

[0036] In this invention, the micro-nano texture preferably includes a periodic concave-convex structure; the texture depth of the micro-nano texture is preferably 80~150 nanometers, the period is preferably 150~250 nanometers; and the surface reflectivity of the micro-nano texture is preferably not higher than 2%.

[0037] In this invention, the length and thickness of the gradient coloring strip are the same as those of the modified polyvinyl acetal resin film; the width of the gradient coloring strip is preferably 8 to 12 cm, more preferably 10 cm.

[0038] The present invention also provides a method for preparing the graded transmittance double-shielded low-reflection film material described above, comprising the following steps: (1) Mix polyvinyl acetal resin, coupling agent and antioxidant to obtain modified polyvinyl acetal resin film mixture; (2) Mix polyvinyl alcohol acetal resin, coupling agent, antioxidant, infrared absorber, ultraviolet absorber and compound coloring pigment to obtain gradient coloring band mixture; (3) The modified polyvinyl alcohol acetal resin film mixture and the gradient coloring tape mixture are melted and extruded separately and then fed into a composite die head with a gradient flow channel and a micro-nano textured pressure roller for composite and molding to obtain the gradient transmittance double shielding low reflection film material. There is no requirement for the time order of steps (1) and (2).

[0039] This invention involves mixing polyvinyl acetal resin, a coupling agent, and an antioxidant (referred to as the first mixture) to obtain a modified polyvinyl acetal resin film mixture. In this invention, the equipment used for the first mixing is preferably a high-speed mixer; the temperature of the first mixing is preferably 75-80 degrees Celsius, and the mixing time is preferably 30-40 minutes.

[0040] This invention involves mixing polyvinyl acetal resin, coupling agent, antioxidant, infrared absorber, ultraviolet absorber, and compound coloring pigment (referred to as the second mixture) to obtain a gradient coloring ribbon mixture. In this invention, the equipment for the second mixing preferably includes a twin-screw extruder; the second mixing is preferably melt blending; the melt blending temperature is preferably 145-150 degrees Celsius, and the mixing time is preferably 15-45 minutes, more preferably 20-30 minutes.

[0041] After obtaining the modified polyvinyl acetal resin film mixture and the gradient coloring tape mixture, the present invention melts and extrudes the modified polyvinyl acetal resin film mixture and the gradient coloring tape mixture separately and then passes them into a composite die head with a gradient flow channel and a micro-nano textured pressure roller for composite and molding to obtain the gradient transmittance double shielding low reflection film material.

[0042] In this invention, the melt extrusion equipment preferably includes a single-screw extruder; the melt extrusion temperature is preferably 155~165 degrees Celsius, more preferably 160 degrees Celsius; and the melt extrusion screw speed is preferably 50~200 rpm, more preferably 80~150 rpm.

[0043] In this invention, the surface of the micro-nano textured roller is engraved with a periodic concave-convex structure.

[0044] In this invention, the molding temperature is preferably 120-150 degrees Celsius, more preferably 125-130 degrees Celsius; the pressure is preferably 0.5-1 MPa, more preferably 0.6-0.8 MPa; and the holding time is preferably 30-300 seconds, more preferably 90-120 seconds, and even more preferably 100-110 seconds. This invention, through the above molding process, can achieve precise forming of micro-nano textures without requiring additional processing steps.

[0045] In this invention, the molding process preferably includes cooling and shaping the resulting product; the cooling and shaping equipment preferably includes cooling rollers.

[0046] The present invention also provides the application of the graded transmittance double-shielded low-reflection film material described in the above-described scheme or the graded transmittance double-shielded low-reflection film material obtained by the preparation method described in the above-described scheme in the field of laminated glass.

[0047] The present invention also provides a laminated windshield glass for automobiles, comprising an interlayer film and glass plates bonded to both sides of the interlayer film; the interlayer film comprises the gradient transmittance double-shielded low-reflection film material described in the above-described scheme or the gradient transmittance double-shielded low-reflection film material obtained by the preparation method described in the above-described scheme; the gradient coloring band of the gradient transmittance double-shielded low-reflection film material is located at the lower end of the laminated windshield glass for automobiles.

[0048] In this invention, the glass plate is preferably an inorganic transparent glass plate or an organic transparent glass plate; the inorganic transparent glass plate preferably includes soda-lime silicate glass, aluminosilicate glass, or borosilicate glass; the organic transparent glass plate preferably includes polycarbonate (PC) sheet, polymethyl methacrylate (PMMA, commonly known as acrylic) sheet, or cyclic olefin polymer (COP) sheet. This invention does not impose any special limitations on the specific chemical composition of the glass plate; any glass plate suitable for automotive laminated glass and capable of firmly bonding with the interlayer film is applicable to this invention. The glass plate used in this invention meets the necessary requirements for transparency, mechanical strength, and adhesive compatibility with the interlayer film.

[0049] In this invention, the glass plate is preferably flat glass or curved glass; the radius of curvature of the curved glass is preferably 800-1500 mm. The gradient transmittance double-shielding low-reflection film material provided by this invention has a gradient coloring strip that adapts to the curvature of the curved glass without bubbles or wrinkles, and is compatible with the curvature of the windshields of existing mainstream vehicle models.

[0050] In this invention, the thickness of the glass plate is preferably 2 to 4 mm, more preferably 3 mm.

[0051] The automotive windshield laminated glass provided by this invention features a gradient tint strip corresponding to the lower edge area of ​​the windshield, which can be well adapted to the instrument panel mounting position and the wiper movement area, respectively. The area corresponding to the gradient tint strip of the automotive windshield laminated glass provided by this invention exhibits an absorption rate of no less than 85% in the 800-1200 nm infrared band, an absorption rate of no less than 99% in the 280-400 nm ultraviolet band, and a visible light transmittance of 10-25%. After 1500 hours of xenon lamp aging, the color difference ΔE of the gradient tint strip is no higher than 2, and the change in visible light transmittance does not exceed 5%, ensuring stable performance during long-term outdoor use.

[0052] The present invention also provides a method for preparing the automotive windshield laminated glass described above, comprising the following steps: The interlayer film is placed between two glass plates and pre-pressed and then pressed in sequence to obtain the automotive windshield laminated glass.

[0053] In this invention, the pre-compression device preferably includes a vacuum bag; the pre-compression temperature is preferably 78~82 degrees Celsius, more preferably 80 degrees Celsius, the vacuum degree is preferably -88~-92 kPa, more preferably -90 kPa, and the pre-compression time is preferably 28~32 minutes, more preferably 30 minutes.

[0054] In this invention, the pressing equipment preferably includes an autoclave; the pressing temperature is preferably 133~137 degrees Celsius, more preferably 135 degrees Celsius, the pressure is preferably 1.1~1.3 MPa, more preferably 1.2 MPa, and the holding time is preferably 55~65 minutes, more preferably 60 minutes.

[0055] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments.

[0056] Example 1 (1) Preparation of modified polyvinyl alcohol acetal resin film mixture: 100 parts by weight of polyvinyl alcohol butyral resin with an average degree of polymerization of 2000, degree of acetylation of 65 mol%, and residual acetyl content of 15 mol%, 1.2 parts by weight of γ-aminopropyltriethoxysilane and 2 parts by weight of type 1010 antioxidant were selected and mixed in a high-speed mixer at 80°C for 30 minutes to obtain a uniform modified polyvinyl alcohol acetal resin film mixture; (2) Preparation of gradient coloring tape mixture: 100 parts by weight of polyvinyl butyral resin with an average degree of polymerization of 2000, degree of acetylation of 65 mol%, and residual acetyl content of 15 mol%, 1.2 parts by weight of γ-aminopropyltriethoxysilane and 2 parts by weight of type 1010 antioxidant were selected and mixed in a high-speed mixer at 80 degrees Celsius for 30 minutes. Then, 5 parts by weight of ATO powder (particle size of 3 micrometers), 0.8 parts by weight of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 5 parts by weight of phthalocyanine blue and titanium dioxide compound coloring pigment (the mass ratio of phthalocyanine blue and titanium dioxide is 1:2) were added to the mixture and melt-blended at 150 degrees Celsius for 20 minutes through a twin-screw extruder to obtain a gradient coloring tape mixture. (3) Preparation of the intermediate film: The prepared modified polyvinyl acetal resin film mixture and the gradient coloring tape mixture were respectively added to two single-screw extruders. After melting and plasticizing at 160 degrees Celsius, they were passed into a composite die head with a gradient flow channel and micro-nano textured pressure roller. The screw speed was 100 rpm, so that the gradient coloring tape mixture formed a gradient coloring tape at the lower edge of the substrate (the transmittance was measured to be 18% at 1 cm from the lower edge and 28% at 1 cm from the upper edge, with a gradient gradient of 1.25%). / cm), while simultaneously being pressed onto the surface of the colored strip at 130 degrees Celsius and 0.8 MPa for 120 seconds by a micro-nano textured roller (with a periodic concave-convex structure engraved on the surface) inside the composite die head, to obtain a micro-nano texture (depth 120 nanometers, period 200 nanometers). After extrusion, it is cooled and shaped by a cooling roller to obtain an intermediate film with a total thickness of 0.76 mm and a gradient colored strip width of 10 cm (based on test results, the lower edge transmittance is estimated to be 16.75%, and the upper edge transmittance is 29.25%). (4) Preparation of laminated glass: Select two sodium calcium silicate curved glass plates with a thickness of 3 mm and a curvature radius of 1200 mm. Place the obtained intermediate film between the two sodium calcium silicate curved glass plates, put them in a vacuum bag, and pre-press them for 30 minutes at 80 degrees Celsius and -90 kPa. Then transfer them to an autoclave and press them for 60 minutes at 135 degrees Celsius and 1.2 MPa to obtain laminated glass.

[0057] Example 2 (1) Preparation of modified polyvinyl alcohol acetal resin film mixture: 100 parts by weight of polyvinyl alcohol butyral resin with an average degree of polymerization of 1500, degree of acetylation of 60 mol%, and residual acetyl group of 10 mol%, 1.0 parts by weight of γ-aminopropyltriethoxysilane and 1.5 parts by weight of type 1076 antioxidant were selected and mixed in a high-speed mixer at 75 degrees Celsius for 40 minutes to obtain a uniform modified polyvinyl alcohol acetal resin film mixture; (2) Preparation of gradient coloring tape mixture: 100 parts by weight of polyvinyl butyral resin with an average degree of polymerization of 1500, degree of acetylation of 60 mol%, and residual acetyl content of 10 mol%, 1.0 parts by weight of γ-aminopropyltriethoxysilane and 1.5 parts by weight of type 1076 antioxidant were added. The mixture was mixed in a high-speed mixer at 75 degrees Celsius for 40 minutes. 4 parts by weight of ATO powder (particle size 2 micrometers), 0.6 parts by weight of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 4 parts by weight of phthalocyanine blue and titanium dioxide compound coloring pigment (the mass ratio of phthalocyanine blue to titanium dioxide is 1:3) were added to the mixture. The mixture was melt-blended in a twin-screw extruder at 145 degrees Celsius for 40 minutes and dispersed evenly to obtain the gradient coloring tape mixture. (3) Preparation of intermediate film: The same composite mold and preparation method as in Example 1 were used. The difference was that the molding conditions were 125 degrees Celsius and 0.6 MPa for 90 seconds. The transmittance of the gradient coloring strip was 16% at 1 cm from the lower edge and 26% at 1 cm from the upper edge. The gradient gradient was 1.43% / cm. The micro-nano texture depth was 100 nm and the period was 180 nm. An intermediate film with a total thickness of 0.5 mm and a gradient coloring strip width of 9 cm was obtained (based on the test results, the transmittance at the lower edge was 14.57% and the transmittance at the upper edge was 27.43%). (4) Preparation of laminated glass: The preparation method is the same as in Example 1, except that the glass is two polycarbonate plates with a thickness of 2.5 mm, thus obtaining laminated glass.

[0058] Comparative Example 1 (1) Preparation of polyvinyl alcohol acetal resin film mixture: 100 parts by weight of polyvinyl alcohol butyral resin with an average degree of polymerization of 2000, a degree of acetylation of 65 mol%, and a residual acetyl group content of 15 mol% were selected and used directly as polyvinyl alcohol acetal resin film mixture without adding coupling agent and antioxidant. (2) Preparation of colored ribbon mixture: Select 100 parts by weight of polyvinyl butyral resin with an average degree of polymerization of 2000, degree of acetylation of 65 mol%, and residual acetyl content of 15 mol%, add 5 parts by weight of phthalocyanine blue pigment, mix evenly to obtain colored ribbon mixture (visible light transmittance of 30%). (3) Preparation of intermediate film: Using a conventional composite die head, the colored strip mixture is used to form a colored strip with a fixed transmittance (10 cm wide, 30% transmittance) on the lower edge of the substrate obtained by the polyvinyl acetal resin film mixture. The surface has no micro-nano texture. After molding, an intermediate film with a total thickness of 0.76 mm is obtained. (4) Preparation of laminated glass: The preparation method is the same as in Example 1, and laminated glass is obtained.

[0059] Comparative Example 2 (1) Preparation of polyvinyl alcohol acetal resin film mixture: 100 parts by weight of polyvinyl alcohol butyral resin with an average degree of polymerization of 2000, a degree of acetylation of 65 mol%, and a residual acetyl group content of 15 mol% were selected and used directly as polyvinyl alcohol acetal resin film mixture without adding coupling agent and antioxidant. (2) Preparation of colored ribbon mixture: 100 parts by mass of polyvinyl butyral resin with an average degree of polymerization of 2000, degree of acetylation of 65 mol%, and residual acetyl content of 15 mol%, and 4 parts by mass of phthalocyanine blue pigment were added to obtain colored ribbon mixture (visible light transmittance of 35%). (3) Preparation of intermediate film: The preparation method is the same as that of comparative example 1, forming a fixed transmittance colored band (width 10 cm, transmittance 35%), with no micro-nano texture on the surface, and obtaining an intermediate film with a total thickness of 0.76 mm; (4) Preparation of laminated glass: The preparation method is the same as in Example 1, and laminated glass is obtained.

[0060] Test Example 1 The performance of the laminated glasses prepared in Examples 1-2 and Comparative Examples 1-2 was tested: (a) Visible light transmittance test (including the upper and lower sides of the gradient coloring band): (1) Sample preparation: In Examples 1 and 2, samples were cut from the lower side (1 cm from the lower edge of the gradient coloring strip) and the upper side (1 cm from the upper edge of the gradient coloring strip) of the laminated glass, respectively, with a size of 50 mm × 50 mm, ensuring that the samples were free of scratches and bubbles; in Comparative Examples 1 and 2, samples were cut from the central area of ​​the coloring strip (50 mm × 50 mm).

[0061] (2) Testing instrument: UV-Vis spectrophotometer (model: UV-3600, Shimadzu).

[0062] (3) Test conditions: In accordance with JIS R-3212 standard, a standard light source D65 was used with a wavelength range of 380~780 nanometers and a scanning interval of 1 nanometer, with air as a reference.

[0063] (4) Test steps: Fix the sample on the sample holder and test the transmittance of the lower side and the upper side (or fixed area) respectively. Repeat the test 3 times for each test point and take the arithmetic mean as the final result.

[0064] (II) Infrared Absorption Rate (800~1200 nm) Test: (1) Sample preparation: The colored area of ​​the laminated glass was cut as a sample, with a size of 50 mm × 50 mm, free of scratches and bubbles.

[0065] (2) Testing instrument: Ultraviolet-visible-near-infrared spectrophotometer (model: Lambda 950, PerkinElmer).

[0066] (3) Test conditions: in accordance with GB / T 2680 standard, wavelength range 800~1200 nm, scanning interval 2 nm, with air as reference.

[0067] (4) Test steps: Test the transmittance (T) and reflectance (R) of the sample, calculate the average absorptivity using the formula “absorbance (A) = 1 - TR”, repeat the test 3 times and take the average value.

[0068] (III) Ultraviolet Absorption Rate (280~400 nm) Test: (1) Sample preparation: consistent with the sample used for infrared absorption rate testing.

[0069] (2) Testing instrument: UV-Vis spectrophotometer (model: UV-3600, Shimadzu).

[0070] (3) Test conditions: in accordance with GB / T 2680 standard, wavelength range 280~400 nm, scanning interval 1 nm, with air as reference.

[0071] (4) Test procedure: Same as infrared absorption rate test, calculate the average absorption rate by formula "A=1-TR", repeat 3 times and take the average value.

[0072] (iv) Surface reflectance test of colored strips: (1) Sample preparation: The central area of ​​the colored band of the laminated glass is cut as a sample, with a size of 50 mm × 50 mm and a clean surface free of impurities.

[0073] (2) Test instrument: Spectrophotometer (with 5° incident angle reflection accessory, model CM-700d, Konica Minolta).

[0074] (3) Test conditions: According to GB / T 2680 standard, light source D65, viewing angle 10°, test the reflectivity at an incident angle of 5°.

[0075] (4) Test steps: Select three evenly distributed test points on the sample surface, test the reflectance respectively, and take the average value as the final result.

[0076] (v) Interlayer film to glass peel strength test: (1) Sample preparation: According to GB / T 14683 standard, the laminated glass is cut into strips with a width of 25 mm and a length of 150 mm. One end is peeled off 50 mm with a blade (exposing the interface between the interlayer film and the glass) to ensure that the peeling surface is undamaged.

[0077] (2) Testing instrument: Universal tensile testing machine (model WDW-50, Jinan Shijin).

[0078] (3) Test conditions: room temperature 23 degrees Celsius, relative humidity 50%, tensile speed 50 mm / min, the peeled end of the sample is clamped in the upper and lower clamps of the testing machine and stretched along the peeling direction.

[0079] (4) Test steps: Record the force-displacement curve during the stretching process, take the average force of the stable segment of the curve, divide it by the sample width (25 mm) to obtain the peel strength, test each sample 5 times and take the average value.

[0080] (vi) Performance testing of xenon lamps after aging (color difference ΔE, change in transmittance): (1) Aging treatment: In accordance with GB / T 16422.2 standard, a xenon lamp aging test chamber (model Xenotest440, Atlas Copco) was used. The aging conditions were: xenon lamp power 600W, irradiance 1000W / m 2 The blackboard temperature was 63 degrees Celsius, the relative humidity was 50%, and it was continuously aged for 1500 hours.

[0081] (2) Color difference ΔE test: Test instrument: Colorimeter (model CR-400, Konica Minolta).

[0082] Test conditions: CIE Lab color space, standard light source D65, viewing angle 10°, with the sample before aging as a reference.

[0083] Test procedure: Before and after aging, select 3 test points in the center area of ​​the colored band on the sample and test L. a The value of b is obtained through the formula "ΔE=√[(ΔL)". 2 +(Δa ) 2 +(Δb ) 2 ]"Calculate the color difference and take the average value of the three measurement points.

[0084] (3) Transmittance change test: Test instruments and conditions: Same as "Visible light transmittance test".

[0085] Test procedure: Test the visible light transmittance of the central area of ​​the colored band of the sample before and after aging, calculate "transmittance change = |transmittance after aging - transmittance before aging|", and take the average value of 3 tests.

[0086] (vii) Visual tomography evaluation test: (1) Test environment: simulated cockpit (equipped with adjustable angle seat, steering wheel, windshield mounting bracket), natural lighting conditions (indoor window, illuminance 5000~6000 lux).

[0087] (2) Evaluators: 10 professional drivers with more than 5 years of driving experience (aged 25-45, with corrected vision of not less than 1.0).

[0088] (3) Test procedure: Install the laminated glass on the windshield frame of the simulated cockpit. The evaluator sits in the driver's seat (adjusted to the normal driving posture), observes the transition between the colored strip and the transparent area, and scores according to the scoring criteria (8~10 points indicate no obvious discontinuity; 6~7 points indicate slight discontinuity; ≤5 points indicate obvious discontinuity). The average score of 10 evaluators is taken as the final result.

[0089] (viii) Vehicle interior cooling effect test: (1) Test apparatus: a sealed simulated car body (size: 1m×1m×1m, inner wall is made of plastic material commonly used in automotive interiors), and a high-intensity light source (xenon lamp, irradiance 1000W / m). 2 Temperature sensor (accuracy ±0.1 degrees Celsius).

[0090] (2) Test conditions: ambient temperature 25 degrees Celsius, relative humidity 50%, light source vertically illuminating the outer surface of the laminated glass, and the distance between the light source and the glass is 50 cm.

[0091] (3) Test steps: Blank control group: Uncolored laminated glass was installed in the window of the simulated carriage, the carriage was closed, the initial temperature (25 degrees Celsius) was recorded, the light source was turned on for 3 hours, and the final temperature T0 was recorded; Sample group: Replace the laminated glass of Examples 1-2 and Comparative Examples 1-2 with the glass to be tested, repeat the above operation, and record the final temperature T1; Cooling effect = T0 - T1. Each sample was tested 3 times and the average value was taken.

[0092] The test results of the above 8 groups are shown in Table 1: Table 1. Performance test results of laminated glass in Examples 1-2 and Comparative Examples 1-2

[0093] Note: The cooling effect inside the vehicle is the temperature reduction compared to laminated glass without gradient tint; a negative value indicates a cooling effect.

[0094] As shown in Table 1, in terms of visual balance, the visual tomography scores of Examples 1-2 are all no lower than 8.9 points, indicating "no obvious tomography," while the scores of Comparative Examples 1-2 are no higher than 4.2 points, indicating "obvious tomography." This is because the present invention uses a gradient coloring strip, where the visible light transmittance gradually transitions from 15-20% at the bottom to 25-30%, creating a smooth difference in transmittance with the transparent area. This eliminates the visual discontinuity caused by abrupt interface changes, better aligns with the driver's visual habits, and can effectively reduce visual fatigue during long-term driving.

[0095] Regarding dual-shielding performance, Examples 1-2 achieved infrared absorption rates of 86-88% and ultraviolet absorption rates of 99.2-99.5%, significantly higher than Comparative Examples 1-2 (infrared absorption rate 42-45%, ultraviolet absorption rate 58-60%). The core reason is that this invention adds both an infrared absorber and a dedicated ultraviolet absorber to the gradient coloring strip. These two absorbers work synergistically to specifically shield infrared thermal radiation and ultraviolet light in the solar spectrum, while Comparative Examples 1-2 rely solely on the physical light-blocking effect of the coloring pigments, failing to achieve efficient dual shielding. In practical applications, Examples 1-2 achieved a vehicle interior cooling effect of 3.8-4.2 degrees Celsius, significantly improving driving comfort and delaying interior aging.

[0096] Regarding low reflectivity, the surface reflectivity of the gradient coloring strips in Examples 1-2 is only 1.5-1.8%, far lower than the 8.2-8.5% of Comparative Examples 1-2. This is due to the micro-nano textured structure on the surface of the gradient coloring strip of the present invention. Its periodic concave-convex structure can scatter incident light, reduce secondary glare caused by interface reflection, and improve visual clarity, especially when meeting oncoming traffic at night or driving against the light, thus reducing safety hazards.

[0097] Regarding adhesion and weather resistance, the peel strength between the interlayer film and glass in Examples 1-2 was above 19 N / cm, and after 1500 hours of xenon lamp aging, the color difference ΔE was no higher than 1.8 and the change in transmittance was no higher than 3.2%. In contrast, the peel strength of Comparative Examples 1-2 was only 11-12 N / cm, and the changes in color difference and transmittance after aging were significantly larger (ΔE not lower than 4.5, and the change in transmittance not lower than 12.5%). This is because the examples added γ-aminopropyltriethoxysilane, which can enhance the interfacial bonding between the interlayer film and the glass; the hindered phenolic antioxidant can inhibit the degradation of the interlayer film under ultraviolet and high-temperature environments, thereby improving the durability and service life of the product.

[0098] This invention solves several performance defects of existing intermediate films, such as visual distortion, low shielding efficiency, reflection interference, and poor weather resistance, through the synergistic combination of "gradient coloring tape + composite absorbent + coupling agent and antioxidant modified resin". The product has significantly superior comprehensive performance, is compatible with existing industrial production processes, and has good market application prospects.

[0099] The embodiments of the present invention have been described above; however, these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the above embodiments of the present invention without inventive effort are within the protection scope of the present invention.

Claims

1. A graded transmittance double-shielded low-reflection film material, characterized in that, It includes a modified polyvinyl acetal resin film and a gradient coloring strip connected to one edge of the modified polyvinyl acetal resin film. The modified polyvinyl acetal resin film includes polyvinyl acetal resin, coupling agent, and antioxidant; The gradient coloring strip includes polyvinyl acetal resin, coupling agent, antioxidant, infrared absorber, ultraviolet absorber, and compound coloring pigment; From the edge to the connection end, the visible light transmittance of the gradient coloring strip increases from 15-20% to 25-30%; The gradient coloring strip has a micro-nano texture on one side surface.

2. The graded transmittance double-shielded low-reflection film material according to claim 1, characterized in that, The polyvinyl acetal resin includes polyvinyl butyral; The polyvinyl butyral has an average degree of polymerization of 500-3000, a degree of acetylation of 50-75 mol%, and a residual acetyl content of 0.5-24 mol.

3. The graded transmittance double-shielded low-reflection film material according to claim 1, characterized in that, The coupling agent is a silane coupling agent.

4. The graded transmittance double-shielded low-reflection film material according to claim 1 or 3, characterized in that, The antioxidant is a hindered phenolic antioxidant.

5. The graded transmittance double-shielded low-reflection film material according to claim 1, characterized in that, The infrared absorber accounts for 3-8% of the total mass of the gradient coloring ribbon; The mass of the ultraviolet absorber accounts for 0.5% to 1% of the total mass of the gradient coloring ribbon; The compound coloring pigment includes phthalocyanine blue and titanium dioxide; The mass ratio of phthalocyanine blue to titanium oxide is 0.9~1.1:2; The mass of the compound coloring pigment accounts for 0.4 to 10% of the total mass of the gradient coloring band.

6. The graded transmittance double-shielded low-reflection film material according to claim 1, characterized in that, The micro / nano texture includes a periodic concave-convex structure; The texture depth of the micro-nano texture is 80~150 nanometers, and the period is 150~250 nanometers; The surface reflectivity of the micro / nano texture is no higher than 2%; The gradient of visible light transmittance of the gradient coloring strip is 0.5~2% / cm.

7. A method for preparing the graded transmittance double-shielded low-reflection film material according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Mix polyvinyl acetal resin, coupling agent and antioxidant to obtain modified polyvinyl acetal resin film mixture; (2) Mix polyvinyl alcohol acetal resin, coupling agent, antioxidant, infrared absorber, ultraviolet absorber and compound coloring pigment to obtain gradient coloring band mixture; (3) The modified polyvinyl alcohol acetal resin film mixture and the gradient coloring tape mixture are melted and extruded separately and then fed into a composite die head with a gradient flow channel and a micro-nano textured pressure roller for composite and molding to obtain the gradient transmittance double shielding low reflection film material. There is no requirement for the time order of steps (1) and (2).

8. The application of the graded transmittance double-shielded low-reflection film material according to any one of claims 1 to 6 or the graded transmittance double-shielded low-reflection film material obtained by the preparation method according to claim 7 in the field of laminated glass.

9. A laminated windshield glass for automobiles, characterized in that, Includes an intermediate film and glass plates bonded to both sides of the intermediate film; The intermediate film includes the graded transmittance double-shielded low-reflection film material according to any one of claims 1 to 6 or the graded transmittance double-shielded low-reflection film material obtained by the preparation method according to claim 7; The gradient coloring band of the gradient transmittance double-shielded low-reflection film material is located at the lower end of the automotive windshield laminated glass.

10. The method for preparing the laminated windshield glass of an automobile according to claim 9, characterized in that, Includes the following steps: The interlayer film is placed between two glass plates and pre-pressed and then pressed in sequence to obtain the automotive windshield laminated glass.

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