PVB composite film and application thereof

Abstract

The invention relates to a PVB (polyvinyl butyral) composite film and application thereof, and belongs to the technical field of PVB composite films for laminated glass. The PVB composite film comprises a first PVB film, a second PVB film and a functional film arranged between the first PVB film and the second PVB film, the first PVB film and the second PVB film are each provided with a plurality of air holes penetrating through film bodies of the first PVB film and the second PVB film. In order to solve the problem of bubble defects caused by gas retention in the traditional process, through air holes which are regularly arranged are formed in the middle area of the PVB film, and an efficient gas discharge channel is provided for the lamination process. By means of the design, the gas exhaust efficiency is greatly improved, meanwhile, interface defects caused by bubble residues in a traditional technology are avoided, the bubble defect rate of a final finished product is remarkably reduced, and the overall structural integrity and optical uniformity of the laminated glass are fundamentally guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to a PVB composite film and its application, belonging to the technical field of PVB composite film for laminated glass. BACKGROUND

[0002] As the core material of safety glass, PVB composite film for laminated glass has formed a relatively complete industrial chain in China. At present, the PVB composite film produced in China has certain gap with the international advanced level in terms of weather resistance, optical performance and other aspects, especially in the adaptability of the lamination process. Taking the traditional three-layer PVB composite film as an example, its typical structure is PVB / functional film / PVB, wherein the functional film is mostly made of PET and other materials, which is used to improve the rigidity or thermal insulation performance of laminated glass. The composite film of this structure needs to be subjected to high temperature of 120-150℃ and pressure of 0.8-1.5MPa to make PVB melt and bond glass during actual lamination process, but air bubbles are easily generated between the interfaces in actual production process, which seriously affects the product quality.

[0003] The air bubble problem mainly comes from three aspects. First, the air remaining between the PVB film and the glass or the functional film when they are bonded, even under standard vacuum conditions, the gas cannot be completely removed. Second, the hygroscopic property of PVB film itself, although the water content is strictly controlled according to the requirements, but the vapor pressure generated by the vaporization of residual moisture in the hot pressing process is still an important cause of micro-bubbles. Third, the difference in thermodynamic properties between the functional film and PVB, for example, the thermal expansion coefficient of PET functional film is 2-3 times different from that of PVB, which will produce a size mismatch of 0.5-1.2% at a lamination temperature of 120-150℃, resulting in interface peeling and bubble nucleation.

[0004] At present, the industry mainly reduces air bubbles through vacuum pre-pressing, autoclave post-treatment and surface modification methods. Vacuum pre-pressing can remove part of the interlayer air before lamination through negative pressure, but it has limited effect on micron-sized bubbles; autoclave treatment can further improve the bonding quality, but it will significantly increase the production energy consumption and time cost; surface modification technology can improve the interface compatibility, but the process is complex and the effect is unstable. These traditional methods are difficult to fundamentally solve the air bubble problem in the lamination process of PVB composite film. Especially under the premise of ensuring that the water content of PVB film meets the standard, it is still impossible to completely avoid the generation of air bubble defects, which seriously restricts the product yield and performance improvement of laminated glass.

[0005] In view of the technical challenge in the industry, it is urgent to explore a new design scheme of PVB composite film. Research shows that the effect of traditional process parameter control method on solving the bubble problem has reached the limit, and a new material system design idea needs to be established. The key is to build an innovative structure that can maintain the core characteristics of PVB film and improve the process adaptability. Through systematic material design, the optimization and control of gas behavior are realized, while the mechanical performance and optical quality of the product are strictly guaranteed. This innovative direction will open up a new technical path for the manufacturing process of laminated glass, and has important significance for improving product yield and process stability. SUMMARY

[0006] The present application solves the above problems and provides a PVB composite film.

[0007] The technical scheme for solving the above problems is as follows:

[0008] A PVB composite film, comprising a first PVB film, a second PVB film and a functional film arranged between the first PVB film and the second PVB film; the first PVB film and the second PVB film are each provided with a plurality of air holes penetrating through the film body.

[0009] As a preferred embodiment of the above technical scheme, the functional film is selected from one of PMMA film, PC film, PET film, reflective HUD film, transparent PHUD film, PDLC film, EC film, SPD film and LC film.

[0010] As a preferred embodiment of the above technical scheme, the thickness of the first PVB film and the second PVB film is 0.1-1.6mm; the pore size of the air hole is 1 / 12-1.2 of the thickness.

[0011] As a preferred embodiment of the above technical scheme, the distance between adjacent air holes is 2-50mm.

[0012] As a preferred embodiment of the above technical scheme, the first PVB film and the second PVB film each include a middle zone and an edge zone, and the air hole is arranged in the middle zone.

[0013] As a preferred embodiment of the above technical scheme, the area of the middle zone accounts for 20-80% of the area of the film body.

[0014] As a preferred embodiment of the above technical scheme, the width of the edge zone is 20-120mm.

[0015] In the structural design of the PVB composite film, the functional division and parameter design of the edge zone and the middle zone are the key innovative points for solving the bubble problem. The specific definition and technical basis are as follows:

[0016] Peripheral Zone, refers to the annular area of the PVB film close to the outer contour. The width range is 20~120mm (preferably 30~80mm), which needs to cover the cutting tolerance of the glass edge and the clamping area of the laminating equipment; the functional requirements are to provide sufficient bonding strength and inhibit water vapor penetration.

[0017] Central Zone, refers to the core area of the PVB film except the Peripheral Zone, which undertakes the dual functions of gas discharge and mechanical support. The area ratio is 20~80% (preferably 50~70%), which balances the gas discharge efficiency and the structural strength of the film; the pore size is 1 / 12~1.2 of the film thickness (for example, 8~120μm for 0.1mm film), which avoids optical distortion caused by too large pore size; the spacing is 2~50mm (preferably 5~20mm), which optimizes the gas diffusion path. The functional requirements are to form directional microchannels during the hot pressing process, allowing bubbles to escape quickly through the gas holes, while maintaining the mechanical properties of the PVB film.

[0018] As a preferred embodiment of the above technical solution, a first adhesive layer is arranged between the first PVB film and the functional film; and a second adhesive layer is arranged between the second PVB film and the functional film.

[0019] As a preferred embodiment of the above technical solution, the first adhesive layer and the second adhesive layer are formed by at least one of PVB glue, polyurethane glue or acrylate glue after curing.

[0020] Another object of the present application is to provide the application of the above-mentioned PVB composite film.

[0021] The application of a PVB composite film in the preparation of laminated glass.

[0022] In summary, the present application has the following advantages:

[0023] 1、The present application aims at the problem of bubble defects caused by gas retention in traditional process, by arranging regular arranged through gas holes (dense structure reserved at the edge) in the middle area of the PVB film, providing an efficient gas discharge channel for the splicing process. This design greatly improves the gas discharge efficiency, while avoiding the interface defects caused by bubble retention in traditional process, finally significantly reducing the bubble defect rate of the finished product, and fundamentally guaranteeing the overall structural integrity and optical uniformity of the laminated glass.

[0024] 2, The application utilizes the heat flow characteristics of PVB material to realize the self-closing function of air holes - at the conventional lamination temperature range of 120-150 DEG C, the molten PVB material flows naturally and completely closes the air holes, forming a defect-free dense structure. This dynamic process not only ensures the effective discharge of gas during the lamination stage, but also avoids the influence of hole residues in the finished product on the mechanical properties, so that the key mechanical indicators such as tensile strength and interfacial bonding strength of the final product are equivalent to those of traditional PVB film, while maintaining excellent sealing performance and optical transparency (both light transmittance and haze indicators meet the requirements of high-end laminated glass);

[0025] 3, The regular arrangement structure of the intermediate air hole area significantly improves the interfacial bonding state of the PVB film and the glass substrate during lamination. The existence of air holes reduces the local stress concentration at the initial contact between the PVB film and the glass, and the molten PVB material can more fully penetrate into the micro concave-convex area of the glass surface during the flow filling process, forming a mechanical interlocking effect; at the same time, the gas discharged from the air holes forms a micro-negative pressure environment at the interface, enhancing the physical adsorption effect of PVB and glass. The synergistic effect of the multiple mechanisms of "stress optimization + physical interlocking + adsorption enhancement" significantly improves the interfacial bonding strength of the composite film and the glass, effectively reduces the risk of interlayer peeling, and further ensures the overall structural stability of the laminated glass;

[0026] 4, The technical scheme of the application solves the problem of air bubbles while significantly improving the process adaptability and functional expandability of the composite film through partition structure design (coordination of the intermediate air hole area and the edge non-hole area) and material parameter optimization. On the one hand, the strict restrictions on lamination temperature, pressure and other process parameters are relaxed (temperature window is widened, pressure range is increased), which improves the production stability and efficiency; on the other hand, by adapting to different functional film layers (such as PET, PMMA, PDLC, reflective HUD, transparent PHUD, etc.), it can flexibly meet the needs of various scenarios such as architectural glass, dimming glass, automotive HUD display, etc.

[0027] 5, In summary, the application systematically solves the problems of air bubble defects, interfacial bonding and process compatibility on the basis of maintaining the inherent advantages of PVB material (such as ultraviolet blocking, sound insulation and other characteristics), providing a reliable technical scheme for the large-scale production of high-performance laminated glass. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a structural schematic diagram of the PVB composite film in Example 1;

[0029] Figure 2 is a partial enlarged view of Figure 1 ;

[0030] Figure 3 is a structural schematic diagram of the first PVB film and the second PVB film in Example 1;

[0031] In the figure, the names of the components represented by the reference numbers are as follows:

[0032] 1- First PVB film,

[0033] 2- first adhesive layer,

[0034] 3- Functional membrane,

[0035] 4- Second adhesive layer,

[0036] 5- second PVB film;

[0037] 11- Middle Zone,

[0038] 12-Fringe Zone,

[0039] 51- Middle District,

[0040] 52-Fringe Zone. DETAILED DESCRIPTION

[0041] The present invention is further explained below with reference to the accompanying drawings.

[0042] This specific embodiment is only an explanation of the present invention and is not intended to limit the present invention. Any changes made by those skilled in the art after reading the description of the present invention will be protected by patent law as long as they are within the scope of the claims.

[0043] Example 1

[0044] A PVB composite film, such as Figures 1-2 As shown, it includes a first PVB film 1, a first adhesive layer 2, a functional film 3, a second adhesive layer 4 and a second PVB film 5. The first PVB film 1 and the second PVB film 5 are both provided with a plurality of pores penetrating the film body. Figure 3 As shown, the first PVB film 1 includes a middle area 11 and an edge area 12 , and the second PVB film 5 includes a middle area 51 and an edge area 52 . The pores are provided in the middle areas 11 and 51 .

[0045] Preparation method of PVB composite film (including HUD function) for automobile windshield

[0046] 1. Material preparation

[0047] (1) PVB film pretreatment:

[0048] The PVB film produced by our company (PVB_1818, hydroxyl content of about 18%, polymerization degree of about 1800; PVB resin content of about 70%, plasticizer triethylene glycol diethyl octanoate of about 30%; cast extrusion) was selected with a thickness of 0.8±0.05mm;

[0049] Equilibrium in constant temperature and humidity room (23±2℃, humidity 30±5%) for 48 hours, control moisture content 0.5±0.1%;

[0050] Laser drilling system is used to process air holes in the middle area of the film surface:

[0051] Pore size 100±2μm (1 / 8 of the film thickness);

[0052] Pore spacing 10±0.1mm, arranged in a matrix;

[0053] Effective drilling area accounts for about 65% of the film area, and the four edges are reserved for 45mm.

[0054] (2) PVB adhesive:

[0055] PVB (hydroxyl content around 15%, degree of polymerization in the interval of 499~1799) 10%, PGDB (propylene glycol dibenzoate, CAS number: 19224-26-1) 25%, silane coupling agent (diethylenetriamine propyl trimethoxysilane, CAS number 35141-30-1) 2.5%, the rest is solvent propylene glycol methyl ether.

[0056] (3) Functional film selection:

[0057] Reflective HUD film: Fuyao purple film is used, reflectivity ≥75%.

[0058] 2. Composite film lamination process

[0059] (1) Laminated assembly:

[0060] According to the order of "glass outer layer (2.0mm tempered glass) / PVB film / functional film (Fuyao purple film) / PVB film / glass inner layer (2.0mm tempered glass)", the layers are overlapped.

[0061] Spray the PVB adhesive between the two PVB films (with holes) and the functional film (Fuyao purple film), control the thickness to about 10μm.

[0062] (2) Pre-pressing treatment

[0063] Three-stage temperature control is used:

[0064] First stage: 80℃ preheating for 3 minutes, pressure 0.3MPa;

[0065] Second stage: 120℃ pre-pressing for 5 minutes, pressure 0.8MPa, simultaneous vacuum extraction to-0.09MPa;

[0066] Third stage: 135℃ final pressing for 2 minutes, pressure 1.2MPa.

[0067] (3) Autoclave molding

[0068] Temperature curve: 25℃→135℃ (heating rate 3℃ / min)→isothermal and pressure maintaining (135±2℃, 1.4±0.1MPa) for 40 minutes→cooling to 50℃ (cooling rate 2℃ / min);

[0069] Special treatment: keep 10 minutes in 80~120℃ temperature zone to ensure PVB fully melt and close pores.

[0070] 3. HUD function debugging

[0071] (1) Optical parameter calibration

[0072] Reflective HUD film:

[0073] Virtual image distance is set to 2.5±0.2m;

[0074] (2) Performance verification:

[0075] Ghost rate detection: ≤0.5%.

[0076] 4. Finished product performance detection

[0077] (1) Basic performance:

[0078] Bubble defect rate: ≤0.15%;

[0079] Transmittance: ≥70% (380~780nm, including HUD film influence);

[0080] (2) HUD special:

[0081] Reflective type: virtual image brightness ≥12,000cd / m 2 ;

[0082] Temperature stability: no image deviation after-30℃~85℃ cycle;

[0083] (3) Durability:

[0084] Hygrothermal aging (85℃ / 85%RH, 1000h):

[0085] Adhesion strength retention rate ≥95%;

[0086] HUD reflectivity attenuation ≤3%;

[0087] No delamination, yellowing phenomenon.

[0088] 5. Matters needing attention

[0089] Environmental control:

[0090] Humidity fluctuation is controlled within ±3%.

[0091] Material matching:

[0092] The fluidity (MFR) of PVB is controlled at 180~200 (tested at 125℃), which is roughly equivalent to PVB_1818 (polymerization degree of about 1800, hydroxyl content of about 18%) containing about 30wt% plasticizer PGDB.

[0093] Example 2

[0094] A PVB composite film, having the same structure as that of Example 1.

[0095] Preparation method of PVB composite film for architectural glass

[0096] 1. Material selection and processing

[0097] (1) PVB substrate

[0098] The PVB film produced by our company was selected (same as in Example 1, except for thickness), with a thickness of 1.5±0.05mm;

[0099] The moisture content is controlled at 0.5±0.1%, and the equilibrium treatment temperature is 25±1℃;

[0100] Use laser drilling system to process pores in the middle area of ​​the membrane surface:

[0101] Pore ​​diameter 150±2μm (1 / 10 of the membrane thickness);

[0102] Use gradient density punching: the hole spacing in the center area is 8mm, the hole spacing in the transition area is 12mm, arranged in a matrix; the width of the transition area is 20cm;

[0103] The effective perforation area accounts for about 75% of the membrane area, and 25mm is retained on all sides.

[0104] (2) Functional membrane configuration

[0105] Reinforcement layer: Torayfan ® PET film.

[0106] 2. Composite process optimization

[0107] (1) Multi-layer assembly structure:

[0108] Glass (6mm semi-tempered) / PVB / PET / PVB / Glass (6mm semi-tempered);

[0109] Spray 10 μm thick polyurethane adhesive (Henkel Loctite) between two PVB films (with holes) and functional film (PET film) ® 3321).

[0110] (2) Key process parameters:

[0111] Pre-press stage: 130℃ / 1.2MPa / 10min, vacuum degree-0.098MPa;

[0112] Autoclave procedure:

[0113] Ramp stage: 2℃ / min to 140℃;

[0114] Soak stage: 140±1℃ / 1.6MPa for 50min;

[0115] Cooling stage: 1.5℃ / min gradient to below 60℃.

[0116] 3. Performance verification

[0117] Hygrothermal aging (85℃ / 85%RH, 1000h):

[0118] Adhesion strength retention rate≥95%;

[0119] 4. Key points of engineering application

[0120] Installation adaptability:

[0121] Compatible with structural adhesive construction (silicone adhesive).

[0122] Example 3

[0123] A PVB composite film with the same structure as Example 1.

[0124] Preparation method of PVB composite film for PDLC dimming glass

[0125] 1. Material selection and treatment

[0126] (1) PVB film

[0127] Select PVB film produced by our company (same as Example 1, except thickness), thickness 0.38±0.02mm;

[0128] The moisture content is controlled at 0.5±0.1%, and the equilibrium treatment temperature is 25±1℃;

[0129] Use a laser drilling system to process air holes in the middle area of the film:

[0130] Pore size 40±2μm (1 / 10 of film thickness);

[0131] Pore spacing 5mm, arranged in a matrix;

[0132] The effective punching area accounts for about 60% of the film area, and the four edges are reserved for 50mm.

[0133] (2) Functional film configuration 2, composite process

[0134] Transparent PDLC light control film: Sunnex Technology;

[0135] 2. Composite process

[0136] (1) Laminated architecture:

[0137] Ultra-white glass (3mm) / PVB film / PDLC film / PVB film / ultra-white glass (3mm);

[0138] Spray 10μm thick polyurethane adhesive (Henggao Lohtai 3321) between two PVB films (with holes) and functional film (PDLC film). ® 3321).

[0139] (2) Curing process:

[0140] Pre-pressing conditions: 95℃ / 0.8MPa / 8 minutes;

[0141] Final curing: 135℃ / 1.0MPa for 25 minutes.

[0142] 3. Functional test

[0143] (1) Photoelectric performance:

[0144] Transmittance adjustment range: 15% (fog state) ~ 78% (transparent state);

[0145] (2) Environmental adaptability:

[0146] Operating temperature range: -40℃ ~ 85℃;

[0147] Humidity effect: resistance change <5% under 95%RH environment;

[0148] 4. Technical key

[0149] Quality control:

[0150] Transmittance uniformity deviation <5%.

[0151] To verify the technical effect of the PVB composite film hole structure, the invention designs a multi-dimensional test scheme based on three typical examples (HUD composite film for automobile windshield, composite film for building glass, and PDLC light control glass), focusing on quantitative analysis of air hole state, optical performance, mechanical performance, functional characteristics and environmental durability, as follows.

[0152] I. Air hole sealing test and microstructure analysis

[0153] Test method: Prepare the laminated glass according to Example 1 (omit the adhesive layer), disassemble the prepared laminated glass, take out two PVB films, and make slice samples in the punched area and the non-punched area respectively, and observe the morphological changes of the pores after the lamination forming by optical microscope (500x); use helium mass spectrometer leak detector to test the difference of gas leakage rate between punched sample and non-punched sample.

[0154] Data collection (take the automobile HUD composite film of Example 1 as an example):

[0155] Pore closure morphology: Microscope observation shows that the PVB material completely melts and fills the pore space, and 99.2% of the pores are completely closed (residual micropore diameter ≤0.5 μm, accounting for 0.8%); the edge dense area without punching has no structural change.

[0156] Gas leakage rate: Helium mass spectrometry shows that the helium leakage rate of the punched sample (after high-temperature melting and sealing) is 0.02 mL / s·cm 2 , which is ≤5% (acceptance standard ≤5%) different from that of the non-punched sample (0.019 mL / s·cm 2 ), which proves that the gas tightness of the sealed structure is equivalent to that of the original dense PVB film.

[0157] Analysis conclusion: The regularly arranged pores are completely closed by PVB melting and flowing in a specific temperature range (130-140℃), and the sealing property of the overall structure is not affected after sealing, which provides a controllable process window for solving the bubble defect (in Example 1, by controlling the 80-135℃ step temperature zone and keeping warm respectively, to ensure sufficient melting and sealing).

[0158] II. Appearance and optical performance test

[0159] Surface defects: Automatic optical detection equipment (AOI) is used to scan the surface of the composite glass, and the number of bubble defects (unit: pieces / m 2 ) is counted.

[0160] Transmittance and haze: Use spectrophotometer to measure the visible light transmittance and haze value in the wavelength range of 380-780 nm (for punched area and non-punched area respectively).

[0161] Imaging distortion (HUD special): Project a standard 5mm pitch grid pattern, capture the virtual image by high-resolution CCD camera, and analyze the ghosting rate (ghosting area ratio) and virtual image offset (Δx, Δy, unit: mm).

[0162] Data collection:

[0163] Example 1 (automobile HUD composite film): Surface defects ≤3 pieces / m 2 (Traditional process non-porous composite film about 5-8 pieces / m2 The transmittance of the composite glass containing the HUD film is 72.3% (380~780nm), the haze is 0.8% (the haze in the non-perforated area is 0.6%, the difference is ≤0.2%); the ghosting rate is 0.4% (acceptance standard ≤0.5%), and the virtual image offset Δx≤0.1mm, Δy≤0.1mm.

[0164] Example 2 (Architectural Glass Composite Film): Surface defects ≤ 5 / m 2 ; Transmittance 95.5%, haze 0.9% (the difference between the perforated area and the non-perforated area ≤ 0.3%); no additional optical distortion after 3000 temperature cycles.

[0165] Example 3 (PDLC dimming glass composite film): surface defects ≤ 2 / m 2 ; The transmittance uniformity deviation is <5% (acceptance standard ≤5%), and there is no local uneven brightness when switching between the foggy state (15% transmittance) and the transparent state (78% transmittance).

[0166] Analysis Conclusion: The perforated structure does not introduce additional surface defects, and the regular arrangement design (such as 10mm hole spacing in Example 1 and gradient density in Example 2) effectively controls optical uniformity, meeting the high requirements for light transmittance and imaging quality in high-end applications (such as HUD and dimming glass).

[0167] 3. Mechanical properties test

[0168] Adhesion Strength: Peel tests were conducted according to ASTM D903 to test the PVB-glass interface bonding strength in both perforated and unperforated areas. Simultaneously, strength retention tests were conducted after damp heat aging (85°C / 85% RH, 1000 hours) and high-temperature and high-humidity cycling (-30°C to 85°C, 3000 cycles).

[0169] Data collection:

[0170] Example 1 (Automotive HUD composite film): The PVB-glass interface peel strength in the perforated area is 3.6 N / mm (3.2 N / mm in the unperforated area), and the strength retention rate after wet heat aging is 96% (acceptance standard ≥95%).

[0171] Example 2 (Architectural Glass Composite Film):

[0172] The PVB-glass interface peel strength in the perforated area is 3.2N / mm (2.8N / mm in the non-perforated area), and the strength retention rate after wet-heat aging is 96% (acceptance standard ≥95%).

[0173] Example 3 (PDLC dimming glass composite film): PVB-PDLC interface peeling strength 2.5 N / mm (satisfies the long-term fitting requirements of dimming film), strength retention rate after hygrothermal aging 97% (acceptance standard ≥ 95%).

[0174] Analysis conclusion: The punching structure optimizes the interface bonding mechanism (such as mechanical interlocking and micro-negative pressure adsorption), so that the bonding strength of PVB-glass / function film is equivalent to or even better than that of traditional composite film, while the basic mechanical properties such as impact resistance and bending resistance are maintained, meeting the safety requirements of different scenes.

[0175] Summary

[0176] From the above multi-dimensional test data, it can be known that the punching structure design (pore diameter, pore spacing, effective area ratio) and process parameters (hot pressing temperature, sealing time) of the PVB composite film in the application synergistically act in the aspects of bubble defect control (surface defect ≤ 5 / m 2 ), interface bonding strength improvement (≥ 95% retention rate), optical performance guarantee (haze ≤ 1.0%, light transmission uniformity deviation < 5%), functional characteristic stability (HUD / dimming function has no attenuation), and environmental durability (no failure after hygrothermal aging / high-low temperature cycle), etc. all show significant advantages, providing a reliable technical verification basis for the industrialization of high-performance laminated glass.

Claims

1. A PVB composite film, comprising a first PVB film (1), a second PVB film (5), and a functional film (3) arranged between the first PVB film and the second PVB film, characterized in that: The first PVB film and the second PVB film are both provided with a plurality of air holes penetrating through the film bodies.

2. A PVB composite film according to claim 1, characterized in that: The functional film (3) is selected from one of PMMA film, PC film, PET film, reflective HUD film, transparent PHUD film, PDLC film, EC film, SPD film, and LC film.

3. A PVB composite film according to claim 1, characterized in that: The thickness of the first PVB film (1) and the second PVB film (5) is 0.1-1.6 mm; the diameter of the pores is 1 / 12-1.2 of the thickness.

4. A PVB composite film according to claim 1 or 3, characterized in that: The distance between adjacent pores is 2~50mm.

5. A PVB composite film according to claim 1 or 3, characterized in that: The first PVB film (1) and the second PVB film (5) both comprise a middle region (11, 51) and an edge region (12, 52), and the pores are provided in the middle region (11, 51).

6. A PVB composite film according to claim 5, characterized in that: The area of ​​the middle zone (11, 51) accounts for 20-80% of the membrane area.

7. The PVB composite film according to claim 5, characterized in that: The width of the edge area (12, 52) is 20-120 mm.

8. A PVB composite film according to claim 1 or 3, characterized in that: A first adhesive layer (2) is provided between the first PVB film (1) and the functional film (3); and a second adhesive layer (4) is provided between the second PVB film (5) and the functional film (3).

9. The PVB composite film according to claim 8, characterized in that: The first adhesive layer (2) and the second adhesive layer (4) are formed by curing at least one of PVB adhesive, polyurethane adhesive or acrylate adhesive.

10. Use of the PVB composite film according to any one of claims 1 to 9 in preparing laminated glass.

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