Gradient functional composite membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of polymer composite materials and safety glass, in particular to a gradient functional composite film as well as a preparation method and application thereof. Starting from the stereoregularity of polyvinyl alcohol, polyvinyl alcohol with different stereoregularity control is utilized to construct polyvinyl butyral resin with different residual hydroxyl stereoregularity: high syndiotacticity polyvinyl alcohol is used as the first polyvinyl butyral resin, and the first polyvinyl butyral resin shows strong adhesion with glass; the second polyvinyl butyral resin uses polyvinyl alcohol with high random degree, and shows high damping property. According to the invention, resin films of two kinds of polyvinyl butyral resin are laminated according to a specific sequence, and are further compounded with a damping sound insulation layer containing inorganic nanoparticles, so that a multifunctional gradient structure of'rigid bonding-damping dissipation-sound insulation attenuation 'is constructed; therefore, the high-speed fragment protection performance and the broadband sound insulation performance far better than those of the traditional polyvinyl butyral intermediate film are synergistically realized.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials and safety glass technology, and in particular to a gradient functional composite film, its preparation method and application. Background Technology

[0002] Laminated glass, a common safety component in the automotive and construction industries, is frequently used in applications such as car windshields and building curtain walls. However, as the application scenarios for laminated glass become increasingly demanding, such as in safety vehicles, high-speed trains, or luxury cars, it is required that laminated glass not only withstand the impact of low-speed, high-mass objects (such as falling rocks), but also effectively withstand the impact of high-speed, low-mass fragments (such as explosive fragments or flying sand and gravel). The energy transfer and failure modes of high-speed impacts are drastically different from those of low-speed impacts, placing greater emphasis on the material's instantaneous energy absorption (high loss factor) and stress wave attenuation capabilities. Furthermore, the noise, vibration, and harshness (NVH) performance requirements of modern transportation vehicles have made broadband, high-efficiency sound insulation an essential function of high-end laminated glass.

[0003] As a key component affecting the performance of laminated glass, the interlayer is currently made of plasticized modified polyvinyl butyral (PVB) resin. To improve the performance of laminated glass, engineers have chosen to modify the interlayer. For example, Japanese Patent JP Hei 7-330387 discloses a method that balances transparency and puncture resistance by controlling the degree of butyralization of the PVB resin and the proportion of triads in the residual hydroxyl groups, and by alternately layering two PVB resin films with different parameters.

[0004] However, due to the physical limits of the damping performance (tan δ) and sound insulation performance of polyvinyl butyral resin, even with adjustments to the degree of acetalization and the ratio of the three-unit group in the residual hydroxyl group and optimization of the stacking, the effect on improving the energy dissipation efficiency of laminated glass under high-speed impact and its acoustic loss capacity in the mid-to-high frequency range is still limited, and it is not yet possible to simultaneously achieve high-speed impact absorption and sound insulation. Summary of the Invention

[0005] In view of this, the present invention provides a gradient functional composite film, its preparation method and application. The gradient functional composite film provided by the present invention can be used as an interlayer film in laminated glass, while giving laminated glass high-speed impact absorption and sound insulation properties.

[0006] This invention provides a gradient functional composite membrane, comprising alternating layers of syndiotactic resin and atactic resin; the syndiotactic resin layer comprises a first polyvinyl butyral resin and a first plasticizer; the first polyvinyl butyral resin has a degree of butyralization of 65-75 mol%, and the proportion of isotactic triunits (mm) in the residual hydroxyl groups is not higher than 10%; the atactic resin layer comprises a second polyvinyl butyral resin and a second plasticizer; the second polyvinyl butyral resin has a degree of butyralization of 55-70 mol%, and the proportion of isotactic triunits (rr) in the residual hydroxyl groups is not higher than 15%; a damping sound insulation layer is disposed between the syndiotactic resin layer and the atactic resin layer.

[0007] Preferably, the mass ratio of the first polyvinyl butyral resin to the first plasticizer is 100:35~40; and the mass ratio of the second polyvinyl butyral resin to the second plasticizer is 100:40~45.

[0008] Preferably, the damping sound insulation layer comprises thermoplastic polyurethane elastomer, a third plasticizer, and inorganic nanosheets; the mass ratio of the thermoplastic polyurethane elastomer to the third plasticizer is 83~87:13~17; and the inorganic nanosheets account for 0.5~5% of the mass of the damping sound insulation layer.

[0009] Preferably, the inorganic nanosheets include one or more of modified montmorillonite, magnesium aluminum hydroxide hydrotalcite, and graphene; the inorganic nanosheets have an aspect ratio greater than 50 and a thickness of 1~1.2 nm.

[0010] Preferably, the layered structure of the gradient functional composite membrane is syndiotactic resin layer / damping sound insulation layer / random resin layer / damping sound insulation layer / syndiotactic resin layer (denoted as X / Z / Y / Z / X) or random resin layer / damping sound insulation layer / syndiotactic resin layer / damping sound insulation layer / random resin layer (denoted as Y / Z / X / Z / Y).

[0011] Preferably, the thickness ratio of the syndiotactic resin layer to the random resin layer is 1~8:1~8; the thickness ratio of the syndiotactic resin layer to the damping sound insulation layer is 1~8:1; the thickness of the syndiotactic resin layer is 0.1~0.8mm; the thickness of the damping sound insulation layer is 0.02~0.2mm; and the total thickness of the gradient functional composite membrane is 0.3~2mm.

[0012] The present invention also provides a method for preparing the gradient functional composite membrane described above, comprising the following steps: (1) Vinyl acetate and a first solvent are mixed and subjected to radiation polymerization and alcoholysis reaction in sequence to obtain syndiotactic polyvinyl alcohol; then the syndiotactic polyvinyl alcohol is mixed with n-butyraldehyde, an acid catalyst and water to carry out a first acetalization reaction to obtain syndiotactic polyvinyl butyral resin; then the syndiotactic polyvinyl butyral resin is mixed with a first plasticizer and melt-pressed to obtain a syndiotactic resin layer. (2) Mix vinyl acetate, initiator and second solvent to carry out free radical polymerization reaction to obtain random polyvinyl alcohol; then mix the random polyvinyl alcohol with n-butyraldehyde, acid catalyst and water to carry out second acetalization reaction to obtain random polyvinyl butyral resin; then mix the random polyvinyl butyral resin and second plasticizer and melt press to obtain random resin layer. (3) A portion of thermoplastic polyurethane elastomer, a third plasticizer and inorganic nanosheets are melt-blended and extruded and granulated in sequence to obtain a composite masterbatch; then the composite masterbatch and the remaining thermoplastic polyurethane elastomer are mixed and film-formed to obtain a damping sound insulation layer. (4) The anachronous resin layer, random resin layer and damping sound insulation layer are stacked and compounded in the target order to obtain the gradient functional composite film; There is no requirement for the time order of steps (1) to (3).

[0013] Preferably, the radiation polymerization uses a cobalt-60 source for gamma-ray radiation; the radiation dose rate of the radiation polymerization is 0.4~0.6 kGy / h, and the total absorbed dose is 14~16 kGy; the radiation polymerization is carried out under isothermal conditions and a nitrogen atmosphere; the temperature of the radiation polymerization is -20~0℃.

[0014] The present invention also provides the application of the gradient functional composite film described in the above-described scheme or the gradient functional composite film obtained by the preparation method described in the above-described scheme as an interlayer film of sandwich glass.

[0015] The present invention also provides a laminated glass comprising a first glass plate, an intermediate film, and a second glass plate stacked sequentially; wherein the intermediate film is a gradient functional composite film as described in the above scheme or a gradient functional composite film obtained by the preparation method described in the above scheme.

[0016] This invention provides a gradient functional composite film. The gradient functional composite film provided by this invention can be used as an interlayer in laminated glass, simultaneously imparting high-speed impact absorption and sound insulation properties to the laminated glass. Specifically, this invention starts with the more fundamental structural parameter of the stereoregularity of polyvinyl alcohol (PVA), utilizing PVA with different stereoregularities to construct two types of PVA butyral resins with different residual hydroxyl stereoregularities. These two resins have fundamental differences in chain segment mobility and intermolecular forces: the first PVA butyral resin uses highly syndiotactic PVA, exhibiting strong adhesion to glass; the second PVA butyral resin uses highly random PVA, exhibiting high damping properties. This invention stacks the resin films of the two PVA butyral resins in a specific order and further composites them with a damping sound insulation layer containing inorganic nanoparticles, constructing a multifunctional gradient structure of "rigid adhesion - damping dissipation - sound insulation attenuation," thereby synergistically achieving high-speed fragmentation protection and broadband sound insulation performance far exceeding that of traditional PVA interlayer films.

[0017] This invention also provides a method for preparing the gradient functional composite membrane described above. The preparation method provided by this invention is simple in steps, convenient in operation, safe, and suitable for industrial production.

[0018] This invention also provides the application of the gradient functional composite film described in the above-described scheme or the gradient functional composite film prepared by the above-described scheme as an interlayer film in laminated glass. The gradient functional composite film provided by this invention endows laminated glass with high-speed impact absorption and sound insulation properties, meeting the performance requirements of interlayer films in laminated glass, and has broad application prospects.

[0019] The present invention also provides a laminated glass. The laminated glass provided by the present invention has good high-speed impact absorption and sound insulation properties, making it suitable as safety glass, especially for applications requiring resistance to high-speed flying object impacts and excellent sound insulation performance, such as high-end safety glass for automobiles, high-speed trains, aircraft, or buildings. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of this invention, the accompanying drawings used in the embodiments of this invention or in the prior art are briefly described below. For those skilled in the art, other drawings can be derived from the following drawings without creative effort, and all such drawings are within the protection scope of this invention.

[0021] Figure 1 This is a comparison chart of the visible light transmittance of Example 1 and Comparative Examples 1-3; Figure 2 The haze comparison charts are for Example 1 and Comparative Examples 1-3. Detailed Implementation

[0022] This invention provides a gradient functional composite membrane, comprising alternating layers of syndiotactic resin and atactic resin; the syndiotactic resin layer comprises a first polyvinyl butyral resin and a first plasticizer; the first polyvinyl butyral resin has a degree of butyralization of 65-75 mol%, and the proportion of isotactic triunits in the residual hydroxyl groups is not higher than 10%; the atactic resin layer comprises a second polyvinyl butyral resin and a second plasticizer; the second polyvinyl butyral resin has a degree of butyralization of 55-70 mol%, and the proportion of isotactic triunits in the residual hydroxyl groups is not higher than 15%; a damping sound insulation layer is disposed between the syndiotactic resin layer and the atactic resin layer.

[0023] The gradient functional composite membrane provided by the present invention includes a syndiotactic resin layer; the syndiotactic resin layer includes a first polyvinyl butyral resin and a first plasticizer; the degree of butyralization of the first polyvinyl butyral resin is 65~75 mol%, preferably 70 mol%, and the proportion of isotactic triunits in the residual hydroxyl groups is not higher than 10%, preferably 2~8%.

[0024] In this invention, the first plasticizer preferably comprises triethylene glycol di-2-ethylhexanoate (3GO).

[0025] In this invention, the mass ratio of the first polyvinyl butyral resin to the first plasticizer is preferably 100:35~40, more preferably 100:38.

[0026] The gradient functional composite membrane provided by the present invention includes a random resin layer; the random resin layer includes a second polyvinyl butyral resin and a second plasticizer; the degree of butyralization of the second polyvinyl butyral resin is 55~70 mol%, preferably 60~65 mol%, and the proportion of residual hydroxyl intermediate isotactic triunit group is not higher than 15%, preferably 2~12%, and more preferably 5~8%.

[0027] In this invention, the second plasticizer preferably comprises triethylene glycol di-2-ethylhexanoate.

[0028] In this invention, the mass ratio of the second polyvinyl butyral resin and the second plasticizer is preferably 100:40~45, more preferably 100:41~43, and even more preferably 100:42.

[0029] In this invention, the damping sound insulation layer preferably comprises thermoplastic polyurethane elastomer (TPU), a third plasticizer, and inorganic nanosheets.

[0030] In this invention, the thermoplastic polyurethane elastomer is preferably a high-damping thermoplastic polyurethane elastomer; the high-damping thermoplastic polyurethane elastomer has a loss factor (tan δ) of not less than 0.35 at a frequency of 0.1 Hz and a temperature of 0°C, preferably 0.35 to 0.60. The key characteristic of the high-damping thermoplastic polyurethane elastomer is its high damping loss factor; any thermoplastic polyurethane elastomer that meets the above performance requirements can be used in this invention.

[0031] As a specific and preferred embodiment, the thermoplastic polyurethane elastomer may be Elastollan® 1185A material manufactured by BASF. Testing has shown that this material has a loss factor of approximately 0.40 at 0.1 Hz and 0°C, meeting the damping performance requirements of this invention. Those skilled in the art will understand that other thermoplastic polyurethane elastomers with similar or superior damping performance are also suitable for this invention.

[0032] In this invention, the third plasticizer preferably includes di(butoxyethoxyethyl) adipic acid (DBEEA).

[0033] In this invention, the mass ratio of the thermoplastic polyurethane elastomer to the third plasticizer is preferably 83~87:13~17, more preferably 85:15.

[0034] In this invention, the inorganic nanosheets preferably include one or more of modified montmorillonite, magnesium aluminum hydroxide hydrotalcite, and graphene; the modified montmorillonite is preferably organically modified montmorillonite (OMMT).

[0035] As a specific and preferred embodiment, the organically modified montmorillonite can be the commercially available product Cloisite® 15A (Southern Clay Products), with a layer spacing of 3.2 nm, a thickness of 1 nm, a planar dimension of 100~300 nm, and an aspect ratio >50.

[0036] In this invention, the aspect ratio of the inorganic nanosheet is preferably greater than 50, more preferably 50~70, and the thickness is preferably 1~1.2 nm.

[0037] In this invention, the inorganic nanosheets account for 0.5-5% of the mass of the damping sound insulation layer, more preferably 1-4%, and even more preferably 2-3%.

[0038] When sound waves pass through the damping sound insulation layer, they are subjected to damping loss by the thermoplastic polyurethane elastomer on the one hand, and are repeatedly reflected, scattered and rubbed by a large number of inorganic nanosheet interfaces on the other hand, which significantly enhances the transmission loss (STL) of mid-to-high frequency sound waves.

[0039] In this invention, the stacked structure of the gradient functional composite membrane is preferably syndiotactic resin layer / damping sound insulation layer / random resin layer / damping sound insulation layer / syndiotactic resin layer (syndiotactic resin layer, damping sound insulation layer, random resin layer, damping sound insulation layer and syndiotactic resin layer stacked sequentially) or random resin layer / damping sound insulation layer / syndiotactic resin layer / damping sound insulation layer / random resin layer (random resin layer, damping sound insulation layer, syndiotactic resin layer, damping sound insulation layer and random resin layer stacked sequentially).

[0040] In this invention, the thickness ratio of the single layer of the syndiotactic resin layer to the random resin layer is preferably 1~8:1~8, more preferably 4~6:4~6, and even more preferably 5:5; the thickness ratio of the single layer of the syndiotactic resin layer to the damping sound insulation layer is preferably 1~8:1, more preferably 4~6:1, and even more preferably 5:1.

[0041] In this invention, the thickness of the single layer of the syndiotactic resin layer is preferably 0.1~0.8 mm, more preferably 0.3~0.6 mm.

[0042] In this invention, the thickness of a single layer of the damping sound insulation layer is preferably 0.02~0.2mm, more preferably 0.05~0.15mm, and even more preferably 0.1mm.

[0043] In this invention, the total thickness of the gradient functional composite film is preferably 0.3~2mm, more preferably 0.8~0.9mm, and even more preferably 0.85mm.

[0044] The present invention also provides a method for preparing the gradient functional composite membrane described above, comprising the following steps: (1) Vinyl acetate and a first solvent are mixed and subjected to radiation polymerization and alcoholysis reaction in sequence to obtain syndiotactic polyvinyl alcohol; then the syndiotactic polyvinyl alcohol is mixed with n-butyraldehyde, an acid catalyst and water to carry out a first acetalization reaction to obtain syndiotactic polyvinyl butyral resin; then the syndiotactic polyvinyl butyral resin is mixed with a first plasticizer and melt-pressed to obtain a syndiotactic resin layer. (2) Mix vinyl acetate, initiator and second solvent to carry out free radical polymerization reaction to obtain random polyvinyl alcohol; then mix the random polyvinyl alcohol with n-butyraldehyde, acid catalyst and water to carry out second acetalization reaction to obtain random polyvinyl butyral resin; then mix the random polyvinyl butyral resin and second plasticizer and melt press to obtain random resin layer. (3) A portion of thermoplastic polyurethane elastomer, a third plasticizer and inorganic nanosheets are melt-blended and extruded and granulated in sequence to obtain a composite masterbatch; then the composite masterbatch and the remaining thermoplastic polyurethane elastomer are mixed and film-formed to obtain a damping sound insulation layer. (4) The anachronous resin layer, random resin layer and damping sound insulation layer are stacked and compounded in the target order to obtain the gradient functional composite film; There is no requirement for the time order of steps (1) to (3).

[0045] In this invention, vinyl acetate and a first solvent are mixed and subjected to radiation polymerization and alcoholysis reactions sequentially to obtain syndiotactic polyvinyl alcohol. In this invention, the first solvent is preferably an alcohol; the alcohol is preferably tert-butanol.

[0046] In this invention, the mass ratio of vinyl acetate to the first solvent is preferably 200:95~105, more preferably 200:100.

[0047] In this invention, the equipment for radiation polymerization preferably includes a low-temperature radiation polymerization apparatus; the radiation polymerization preferably uses a cobalt-60 source for gamma-ray radiation; the radiation dose rate of the radiation polymerization is preferably 0.4~0.6 kGy / h, more preferably 0.5 kGy / h, and the total absorbed dose is preferably 14~16 kGy, more preferably 15 kGy; the radiation polymerization is preferably carried out under isothermal conditions and a nitrogen atmosphere; the temperature of the radiation polymerization is preferably -20~0℃, more preferably -10℃. This invention, by controlling the conditions of radiation polymerization and the type of solvent, obtains polyvinyl acetate with a target proportion (more than 55%) of isotactic triunit and a target molecular weight (e.g., degree of polymerization 1650).

[0048] In this invention, the alcoholysis reaction is preferably carried out in an alkaline solution; the alkaline solution is preferably a sodium hydroxide methanol solution; the concentration of the alkaline solution is preferably 0.9~1.1 mol / L, more preferably 1 mol / L.

[0049] In this invention, the molar ratio of alkali in the alkaline solution to acetate groups in polyvinyl acetate is preferably 0.01 to 0.02:1, more preferably 0.01:1. By controlling the above ratio, this invention can ensure efficient alcoholysis to obtain syndiotactic polyvinyl alcohol with a high degree of saponification (e.g., 99.5%).

[0050] In this invention, the degree of polymerization of the syndiotactic polyvinyl alcohol is preferably 1600-1700, more preferably 1650, and the proportion of the syndiotactic triunit group is preferably not less than 55%.

[0051] After obtaining syndiotactic polyvinyl alcohol (PVA), the present invention mixes the PVA with n-butyraldehyde, an acid catalyst, and water to carry out a first acetalization reaction to obtain syndiotactic polyvinyl butyral resin. In the present invention, the mass ratio of syndiotactic polyvinyl alcohol to water is preferably 10~12:88~90, more preferably 10:90. Using the above ratio in the present invention facilitates the full expansion of the syndiotactic polyvinyl alcohol molecular chain in the solution system, ensuring a homogeneous reaction with n-butyraldehyde, thereby controlling the degree of acetalization and sequence distribution of the syndiotactic polyvinyl butyral resin.

[0052] In this invention, the mass ratio of syndiotactic polyvinyl alcohol to n-butyraldehyde is preferably 100:30~50, more preferably 100:40.

[0053] In this invention, the acid catalyst is preferably hydrochloric acid; the concentration of the hydrochloric acid is preferably 10-15 wt%, more preferably 12 wt%.

[0054] In this invention, the mass ratio of the acid (calculated as pure HCl) in the syndiotactic polyvinyl alcohol and the acid catalyst is preferably 100:0.5~2, more preferably 100:1.

[0055] In this invention, the temperature of the first acetalization reaction is preferably 38-42°C, more preferably 40°C, and the holding time is preferably 4-6 hours, more preferably 5 hours. This invention ensures the acquisition of syndiotactic polyvinyl butyral resin with the target degree of butyralization by controlling the above reaction conditions, raw material dosage, and acid catalyst conditions.

[0056] The hydroxyl groups on the syndiotactic polyvinyl alcohol (PVA) molecular chain are arranged regularly. After acetalization, the molecular chain is rigid and has a high tendency to crystallize, providing extremely high initial modulus and strong polar adhesion to glass. To maintain processability, the degree of butyralization is controlled at 65-75 mol%, and the proportion of isotactic triunits in the residual hydroxyl groups is not higher than 10%, in order to avoid excessive regularity that leads to over-crystallization and decreased transparency.

[0057] After obtaining syndiotactic polyvinyl butyral resin, the present invention mixes the syndiotactic polyvinyl butyral resin with a first plasticizer and then melt-presses the mixture to obtain a syndiotactic resin layer. In the present invention, the melt-pressing temperature is preferably 150-180°C, more preferably 160°C; the pressure is preferably 5-15 MPa, more preferably 8-12 MPa; and the holding time is preferably 3-10 minutes, more preferably 5-8 minutes. Syndiotactic resin molecules have a regular arrangement and a high tendency to crystallize. The above conditions, especially the above temperature, are beneficial for complete melting, eliminating internal stress, and ensuring the transparency of the syndiotactic resin layer.

[0058] This invention involves mixing vinyl acetate, an initiator, and a second solvent to conduct a free radical polymerization reaction to obtain atactic polyvinyl alcohol. In this invention, the initiator is preferably benzoyl peroxide.

[0059] In this invention, the mass ratio of vinyl acetate to initiator is preferably 300:0.5~2, more preferably 300:1.

[0060] In this invention, the second solvent is preferably an alcohol; the alcohol is preferably methanol.

[0061] In this invention, the mass ratio of vinyl acetate to the second solvent is preferably 300:95-105, more preferably 300:100. This ratio facilitates the acquisition of atactic polyvinyl alcohol with a target degree of polymerization (e.g., 1500) and randomness.

[0062] In this invention, the temperature of the free radical polymerization reaction is preferably not lower than 60°C, more preferably 60-70°C, and even more preferably 65°C. The holding time is preferably 4-8 hours, more preferably 6-7 hours. The above-mentioned temperature facilitates the decomposition of benzoyl peroxide to generate free radicals. These free radicals attack the vinyl acetate monomer, initiating a chain reaction to form polyvinyl acetate. Through the above reaction, this invention obtains atactic polyvinyl alcohol with the target degree of polymerization and saponification.

[0063] In this invention, the random stereoregularity of the random polyvinyl alcohol is preferably not less than 60% (mm+rr not more than 40%), and more preferably 60~70%.

[0064] After obtaining atactic polyvinyl alcohol, the present invention mixes the atactic polyvinyl alcohol with n-butyraldehyde, an acid catalyst, and water to carry out a second acetalization reaction to obtain atactic polyvinyl butyral resin. In the present invention, the parameters for preparing atactic polyvinyl butyral resin are preferably the same as those for syndiotactic polyvinyl butyral resin, except that the holding time for the second acetalization reaction is preferably 3-4 hours. The above conditions adopted in the present invention are more suitable for atactic polyvinyl alcohol, whose molecular chains are flexible and disordered, with high hydroxyl accessibility, high reactivity, and a low target degree of acetalization.

[0065] Random polyvinyl alcohol has flexible molecular chains, and after acetalization, the chain segments have strong mobility and large free volume. Under dynamic loads (such as high-speed impact or sound waves), the internal friction generated by the chain segment movement is large, exhibiting high damping (high tan δ value). Controlling the degree of butyralization to 55~70 mol% and the proportion of syndiotactic ternary units not exceeding 15% can ensure sufficient flexibility and damping performance.

[0066] After obtaining random polyvinyl butyral resin, the present invention mixes the random polyvinyl butyral resin and a second plasticizer, and then melt-presses the mixture to obtain a random resin layer. In the present invention, the melt-pressing temperature is preferably 150~170℃, more preferably 160℃; the pressure is preferably 6~10MPa, more preferably 7~9MPa; and the holding time is preferably 3~6 minutes, more preferably 4~5 minutes. Random resin chains are flexible, have a large free volume, and exhibit good melt flowability. The present invention employs the above conditions, especially the above temperature, to avoid excessive heat history affecting the damping performance.

[0067] This invention involves sequentially melt-blending and extruding / granulating a portion of thermoplastic polyurethane elastomer, a third plasticizer, and inorganic nanosheets to obtain a composite masterbatch. In this invention, the mass ratio of the thermoplastic polyurethane elastomer to the third plasticizer is preferably 100:23~27, more preferably 100:25. Using this ratio, the invention ensures the viscoelasticity and processability of the damping sound insulation layer while preventing plasticizer precipitation.

[0068] In this invention, the inorganic nanosheets account for 14-16 wt% of the composite masterbatch, more preferably 15 wt%.

[0069] In this invention, the melt blending equipment preferably includes a twin-screw extruder; the melt blending temperature is preferably 175~200℃, more preferably including four temperature zones from the feed inlet to the die head: a feed section, a melt mixing section, a homogenization section, and a die head section; the temperature of the feed section is preferably 175~180℃, more preferably 178~179℃; the temperature of the melt mixing section is preferably 185~195℃, more preferably 188~190℃; the temperature of the homogenization section is preferably 190~195℃, more preferably 192~193℃; the temperature of the die head section is preferably 185~190℃, more preferably 187~188℃; the screw speed of the melt blending is preferably 100~300 rpm, more preferably 200 rpm.

[0070] In this invention, the target diameter of the extrusion granulation is preferably 2.7~3.2 mm, more preferably 3 mm, and the length is preferably 3.7~4.2 mm, more preferably 4 mm.

[0071] After obtaining the composite masterbatch, the present invention mixes the composite masterbatch with the remaining thermoplastic polyurethane elastomer and forms a film to obtain a damping sound insulation layer. In the present invention, the mass ratio of the composite masterbatch to the remaining thermoplastic polyurethane elastomer is preferably 0.9~1.1:3, more preferably 1:3.

[0072] In this invention, the film formation is preferably achieved by pressing; the pressing temperature is preferably 170~190℃, more preferably 175~185℃, the pressure is preferably 5~15MPa, more preferably 8~12MPa, and the holding time is preferably 3~10 minutes, more preferably 4~6 minutes.

[0073] After obtaining the syndiotactic resin layer, the random resin layer, and the damping sound insulation layer, the present invention laminates the syndiotactic resin layer, the random resin layer, and the damping sound insulation layer in a target sequence to obtain the gradient functional composite membrane. In the present invention, the target sequence preferably includes syndiotactic resin layer / damping sound insulation layer / random resin layer / damping sound insulation layer / syndiotactic resin layer or random resin layer / damping sound insulation layer / syndiotactic resin layer / damping sound insulation layer / random resin layer.

[0074] In this invention, the composite is preferably hot-pressed; the equipment for hot pressing preferably includes a hot roller laminator; the temperature of hot pressing is preferably 118~122℃, more preferably 120℃, the pressure is preferably 0.78~0.82MPa, more preferably 0.8MPa, and the holding time of hot pressing is preferably 10~30 minutes, more preferably 20 minutes.

[0075] The present invention also provides the application of the gradient functional composite film described in the above-described scheme or the gradient functional composite film obtained by the preparation method described in the above-described scheme as an interlayer film of sandwich glass.

[0076] The gradient functional composite film provided by this invention endows laminated glass with high-speed impact absorption and sound insulation properties, which meets the performance requirements of the interlayer film in laminated glass and has broad application prospects.

[0077] The present invention also provides a laminated glass comprising a first glass plate, an intermediate film, and a second glass plate stacked sequentially; wherein the intermediate film is a gradient functional composite film as described in the above scheme or a gradient functional composite film obtained by the preparation method described in the above scheme.

[0078] In this invention, the first glass plate or the second glass plate is preferably float glass.

[0079] In this invention, the stereoregularity of polyvinyl alcohol (the ratio of the three units mm, mr, and rr) is determined by its precursor, polyvinyl acetate. 13 C-NMR determination (refer to "Handbook of Polymer Analysis"); the degree of butyralization and residual hydroxyl sequence distribution of polyvinyl butyral resin were determined by... 1 H-NMR determination.

[0080] The innovation of this invention lies in: Original innovation (stereoregularity control): This invention is the first to introduce the syndiotacticity and randomness of polyvinyl alcohol as core control parameters into the construction of polyvinyl butyral intermediate film, replacing the traditional approach of only focusing on the ratio of three units. It constructs two polyvinyl butyral resins with very different properties from the stereochemical nature of the polymer chain.

[0081] Structural Innovation (Graded Functional Composite): This invention constructs a gradient structure consisting of an isochronous resin layer, a damping and sound-insulating layer, and a random resin layer. The isochronous resin layer (denoted as X) is responsible for rigid support and bonding; the random resin layer (denoted as Y) acts as the main damping layer, absorbing energy; and the intermediate damping and sound-insulating layer (denoted as Z) specializes in sound insulation and auxiliary damping. Through gradient functional composite (e.g., X / Y / X or Y / X / Y), each layer has a clear division of labor and synergistic effects.

[0082] Performance Innovation (Dual High Performance): This invention further extends the basic properties such as transparency and puncture resistance to high-speed impact protection and broadband sound insulation, and provides corresponding material structures and evaluation systems.

[0083] 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.

[0084] Example 1 (1) Preparation of syndiotactic polyvinyl alcohol and syndiotactic polyvinyl butyral resins: In a low-temperature radiation polymerization apparatus, 100 parts by mass of tert-butanol solvent and 200 parts by mass of vinyl acetate monomer were added. High-purity nitrogen was introduced to purge oxygen, and the system was cooled to -10°C. Gamma-ray radiation polymerization was performed using a cobalt-60 source at a dose rate of 0.5 kGy / h and a total absorbed dose of 15 kGy. The temperature was kept constant during the radiation process to obtain polyvinyl acetate. The prepared polyvinyl acetate was then subjected to… 13 C-NMR analysis showed that the proportion of isotactic triunits was 59%. The prepared polyvinyl acetate was alcoholyzed in a sodium hydroxide methanol solution (sodium hydroxide concentration was 1 mol / L) with a molar ratio of sodium hydroxide to acetate groups in polyvinyl acetate of 0.01:1, to obtain syndiotactic polyvinyl alcohol with a degree of polymerization of 1650 and a degree of saponification of 99.5%.

[0085] The prepared syndiotactic polyvinyl alcohol was prepared into a 10 wt% aqueous solution and then subjected to an acetalization reaction at 40°C with n-butyraldehyde (40% of the mass of syndiotactic polyvinyl alcohol) and hydrochloric acid (12 wt% concentration, HCl 1% of the mass of syndiotactic polyvinyl alcohol) for 5 hours to obtain a syndiotactic polyvinyl butyral resin with a butyralization degree of 70 mol%. 1 H-NMR analysis showed that the proportion of isotactic triunits in the residual hydroxyl groups was 8%.

[0086] (2) Preparation of random polyvinyl alcohol and random polyvinyl butyral resin: In 100 parts by mass of methanol solvent, benzoyl peroxide (the mass ratio of vinyl acetate to benzoyl peroxide is 300:1) was added as an initiator at 65°C, and 300 parts by mass of vinyl acetate were added. Free radical polymerization was carried out at 65°C for 7 hours to obtain polyvinyl acetate. The prepared polyvinyl acetate had a high degree of randomness (rr+mm=35%). Polyvinyl acetate was then alcoholyzed under the same conditions as in step (1) to obtain atactic polyvinyl alcohol with a degree of polymerization of 1500 and a degree of saponification of 99.2%.

[0087] Random polyvinyl alcohol was prepared into a 10 wt% aqueous solution and then subjected to an acetalization reaction at 40 °C with n-butyraldehyde (40% of the mass of random polyvinyl alcohol) and hydrochloric acid (12 wt% concentration, HCl 1% of the mass of syndiotactic polyvinyl alcohol) for 3 hours to obtain a random polyvinyl alcohol butyral resin with a butyralization degree of 62 mol% and a syndiotactic triunit ratio of 10% in its residual hydroxyl groups.

[0088] (3) Preparation of composite masterbatch for damping sound insulation layer: 100 parts by weight of thermoplastic polyurethane (BASF Elastollan 1185A), organically modified montmorillonite (OMMT, Cloisite® 15A, with an original sheet thickness of 1 nm, a planar size of 100~300 nm, and an addition amount of 15 wt% of the composite masterbatch) and 25 parts by weight of plasticizer di(butoxyethoxyethyl) adipic acid were melt-blended in a twin-screw extruder. The temperature gradient of the extruder from the feed inlet to the die head was set as follows: 178℃ (feed section), 190℃ (melt mixing section), 195℃ (homogenization section), and 188℃ (die head section). The screw speed was 200 rpm. The extrusion granulation yielded composite masterbatch with a particle size of 3 mm in diameter and 4 mm in length.

[0089] (4) Preparation of gradient functional composite membranes: 100 parts by weight of syndiotactic polyvinyl butyral resin were mixed with 38 parts by weight of triethylene glycol di-2-ethylhexanoate, and then melt-pressed at 160°C and 10 MPa for 5 minutes to obtain a syndiotactic resin layer with a thickness of 0.25 mm.

[0090] 100 parts by weight of random polyvinyl butyral resin and 42 parts by weight of triethylene glycol di-2-ethylhexanoate were mixed and melt-pressed at 160°C and 10 MPa for 5 minutes to obtain a random resin layer with a thickness of 0.25 mm.

[0091] The composite masterbatch prepared in step (3) was mixed with thermoplastic polyurethane particles at a mass ratio of 1:3 and pressed at 185℃ and 12MPa for 6 minutes to obtain a damping sound insulation layer with a thickness of 0.05mm.

[0092] The prepared syndiotactic resin layer, random resin layer, and damping sound insulation layer were stacked in the following order: syndiotactic resin layer / damping sound insulation layer / random resin layer / damping sound insulation layer / syndiotactic resin layer, with a total thickness of 0.85 mm. The composite was then hot-pressed at 120°C and 0.8 MPa for 20 minutes using a hot roller laminator to obtain a gradient functional composite film.

[0093] (5) Performance testing: The gradient functional composite membrane prepared in this embodiment was used with two pieces of float glass with a thickness of 3 mm to form a standard laminated glass specimen in an autoclave.

[0094] Optical performance: Visible light transmittance 88.5%, haze 0.5%.

[0095] High-speed impact test: A 1g steel ball was fired from an air gun and impacted vertically at a speed of 180m / s. The results showed that the steel ball embedded itself in the gradient functional composite film but did not penetrate it, and the float glass on the back showed no cracks or peeling. The height of the bulge on the back of the impact point was less than 3mm.

[0096] Sound insulation test: Sound transmission loss (STL) was measured according to ASTM E90 standard. At a frequency of 2000 Hz, the STL value was 41 dB.

[0097] Comparative Example 1 The preparation and testing methods of this comparative example are the same as those of Example 1, except that only one layer of random resin with a thickness of 0.85 mm is used as an interlayer to make laminated glass.

[0098] Optical performance: Visible light transmittance 89.0%, haze 0.3%.

[0099] High-speed impact test: Large-area radial cracks appeared in the float glass on the back.

[0100] Sound insulation test: STL value is 33dB.

[0101] Comparative Example 2 The preparation and testing methods of this comparative example are the same as those of Example 1, except that the damping sound insulation layer is omitted, and it is prepared by stacking syndiotactic resin layer / random resin layer / syndiotactic resin layer in the order of syndiotactic resin layer / random resin layer (total thickness is 0.75 mm), which is used as an interlayer to make laminated glass.

[0102] Optical performance: Visible light transmittance 88.8%, haze 0.4%.

[0103] High-speed impact test: Star-shaped cracks appeared in the float glass on the back.

[0104] Sound insulation test: STL value is 35dB.

[0105] Comparative Example 3 The preparation and testing methods of this comparative example are the same as those of comparative example 1, except that commercially available polyvinyl butyral resin (the ratio of the three units was not specifically controlled) was used instead of random polyvinyl butyral resin, and one layer with a thickness of 0.85 mm was used as an interlayer to make laminated glass.

[0106] Optical performance: Visible light transmittance 88.2%, haze 0.4%.

[0107] High-speed impact test: The interlayer was punctured, and the laminated glass shattered.

[0108] Sound insulation test: STL value is 31dB.

[0109] The performance of Example 1 and Comparative Examples 1-3 is summarized in Table 1 and... Figures 1-2 As shown: Table 1. Performance Summary of Example 1 and Comparative Examples 1-3

[0110] According to Table 1 and Figures 1-2 As can be seen, this invention innovatively constructs a gradient functional composite film by starting from the stereoregularity of polyvinyl alcohol (PVA), using radiation polymerization to prepare syndiotactic PVA butyral resin, and then combining it with atactic PVA butyral resin and a damping sound insulation layer in a gradient structure. This successfully produces a film that simultaneously possesses excellent high-speed impact protection and superior broadband sound insulation performance. Its comprehensive performance far surpasses that of traditional single-layer PVA butyral films, traditional laminated PVA butyral films, and single-stereotype PVA butyral films, meeting the multifunctional needs of high-end safety glass applications.

[0111] 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 present 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 gradient functional composite membrane, characterized in that, It includes alternating layers of syndiotactic and atactic resins; The syndiotactic resin layer comprises a first polyvinyl butyral resin and a first plasticizer; The degree of butyralization of the first polyvinyl butyral resin is 65-75 mol%, and the proportion of isotactic triunits in the residual hydroxyl groups is not higher than 10%. The random resin layer comprises a second polyvinyl butyral resin and a second plasticizer; The degree of butyralization of the second polyvinyl butyral resin is 55-70 mol%, and the proportion of residual hydroxyl intermediate isotactic triunits is not higher than 15%. A damping sound insulation layer is provided between the anachronous resin layer and the random resin layer.

2. The gradient functional composite membrane according to claim 1, characterized in that, The mass ratio of the first polyvinyl butyral resin to the first plasticizer is 100:35~40; The mass ratio of the second polyvinyl butyral resin to the second plasticizer is 100:40~45.

3. The gradient functional composite membrane according to claim 1, characterized in that, The damping and sound insulation layer comprises thermoplastic polyurethane elastomer, a third plasticizer, and inorganic nanosheets; The mass ratio of the thermoplastic polyurethane elastomer to the third plasticizer is 83~87:13~17; The inorganic nanosheets account for 0.5-5% of the mass of the damping sound insulation layer.

4. The gradient functional composite membrane according to claim 3, characterized in that, The inorganic nanosheets include one or more of modified montmorillonite, magnesium aluminum hydroxide hydrotalcite, and graphene. The inorganic nanosheets have an aspect ratio greater than 50 and a thickness of 1~1.2 nm.

5. The gradient functional composite membrane according to claim 1, characterized in that, The layered structure of the gradient functional composite membrane is either syndiotactic resin layer / damping sound insulation layer / random resin layer / damping sound insulation layer / syndiotactic resin layer or random resin layer / damping sound insulation layer / syndiotactic resin layer / damping sound insulation layer / random resin layer.

6. The gradient functional composite membrane according to claim 1, characterized in that, The thickness ratio of the syndiotactic resin layer to the atactic resin layer is 1~8:1~8; The thickness ratio of the single layer of the syndiotactic resin layer to the damping sound insulation layer is 1~8:1; The thickness of a single layer of the syndiotactic resin layer is 0.1~0.8 mm; The thickness of a single layer of the damping sound insulation layer is 0.02~0.2mm; The total thickness of the gradient functional composite membrane is 0.3~2mm.

7. The method for preparing the gradient functional composite membrane according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Vinyl acetate and a first solvent are mixed and subjected to radiation polymerization and alcoholysis reaction in sequence to obtain syndiotactic polyvinyl alcohol; then the syndiotactic polyvinyl alcohol is mixed with n-butyraldehyde, an acid catalyst and water to carry out a first acetalization reaction to obtain syndiotactic polyvinyl butyral resin; then the syndiotactic polyvinyl butyral resin is mixed with a first plasticizer and melt-pressed to obtain a syndiotactic resin layer. (2) Mix vinyl acetate, initiator and second solvent to carry out free radical polymerization reaction to obtain random polyvinyl alcohol; then mix the random polyvinyl alcohol with n-butyraldehyde, acid catalyst and water to carry out second acetalization reaction to obtain random polyvinyl butyral resin; then mix the random polyvinyl butyral resin and second plasticizer and melt press to obtain random resin layer. (3) A portion of thermoplastic polyurethane elastomer, a third plasticizer and inorganic nanosheets are melt-blended and extruded and granulated in sequence to obtain a composite masterbatch; then the composite masterbatch and the remaining thermoplastic polyurethane elastomer are mixed and film-formed to obtain a damping sound insulation layer. (4) The anachronous resin layer, random resin layer and damping sound insulation layer are stacked and compounded in the target order to obtain the gradient functional composite film; There is no requirement for the time order of steps (1) to (3).

8. The preparation method according to claim 7, characterized in that, In step (1), the radiation polymerization is performed using a cobalt-60 source for gamma-ray irradiation; The radiation dose rate of the radiation polymerization is 0.4~0.6 kGy / h, and the total absorbed dose is 14~16 kGy; The radiation polymerization was carried out under isothermal conditions and a nitrogen atmosphere; The temperature for radiation polymerization is -20~0℃.

9. The application of the gradient functional composite film according to any one of claims 1 to 6 or the gradient functional composite film obtained by the preparation method according to any one of claims 7 to 8 as an interlayer film of sandwich glass.

10. A laminated glass, characterized in that, It includes a first glass plate, an intermediate film, and a second glass plate stacked sequentially; the intermediate film is the gradient functional composite film according to any one of claims 1 to 6 or the gradient functional composite film obtained by the preparation method according to any one of claims 7 to 8.

Images