Preparation Of High Sound Insulation PVB Composite Film And Its Application On Laminated Glass

Polyvinyl alcohol butyraldehyde(PVB)laminated glass,with safety,heat insulation,sound insulation and ultraviolet isolation functions,is widely used in construction,automotive,photovoltaic and other fields.With the rapid development of the city,the sound insulation performance of laminated glass has been demanded,especially at low and medium(LM)frequencies,improving the quality of life and comfort.While increasing the thickness of glass or the number of layers can boost sound insulation,it also raises processing and transportation costs and compromises the lightness of vehicles and safety of buildings.Therefore,improving the sound insulation performance of the PVB interlayer has become an urgent problem for researchers.At present,the sound insulation intermediate layer materials available in the market are mostly supplied by Sekisui,Kurara and Eastman.However,these products typically target noise above 1000 Hz and do not effectively insulate noise at LM frequencies,which are more damaging to human health.In this paper,PVB/PVDF composite film was prepared based on electromechanical coupling effect and applied to laminated glass.The sound insulation performance of the composite film at LM frequencies(64-1600 Hz)was improved through structural design and process regulation.The specific research content is as follows:(1)The PVB/PVDF transparent composite film and laminated glass were successfully prepared.PVDF fiber film was prepared by electrospinning,the results showed that optimizing the spinning conditions can increase the tensile force and promote the transition fromαphase to theβphase,thereby enhancing the piezoelectric performance.Subsequently,transparent composite film was prepared by hot pressing.By the thermoplastic characteristic of PVB elastomer,the transparent PVB/PVDF material was successfully prepared by adjusting the temperature,pressure,and thickness of the fiber film.Further,composite film were made into safety laminated glass,and the results were as follows:compared to pure PVB,the average sound insulation(ATL)of the composite film was increased by 1.3 d B(64-1600 Hz),the tensile strength was 23.4MPa,the elongation at break was 213%,the bonding strength was 5.3MPa,the transmittance of the laminated glass achieved 80%,and the mass breaking rate of glass in the impact resistance test was 1.42%(50 g steel ball was impacted 7 times at 100 cm).This is the first time that fiber film has been used for laminated glass,supplying a reference for its application in the field of transparent film.(2)The PVB/PVDF/inorganic salt sound insulation composite film and its safety laminated glass were prepared.The piezoelectric properties of PVDF were improved by inorganic salt,the influence of inorganic salt type,concentration,and conductivity of the spinning solution on PVDF fiber morphology was explored.The mechanism of increasingβphase content by inorganic salt was revealed.The relationship betweenβphase content,volume resistivity,piezoelectric coefficient and output voltage in PVDF fiber were clarified.The results were as follows:L2 fiber film exhibited the maximum piezoelectric coefficient(25 p C/N)and output voltage(1.21 V).Compared to pure PVB,the PVB/L2composite film demonstrated a 4.1 d B increase in ATL,a tensile strength of 23.2 MPa,an elongation at break of 206%,a transmittance of 80%in laminated glass,and a mass breaking rate of 1.44%in the impact resistance test(50 g steel ball was impacted 7 times at100 cm).The development of piezoelectric sound insulation film has successfully breakthrough the limitations of traditional quality law and provides a novel approach to creating lightweight and transparent sound insulation materials.(3)The PVB/PVDF sound insulation film and its safety laminated glass were successfully prepared by spraying ionic liquid(IL).The effects of IL content on piezoelectricity,output voltage of fiber film,and sound insulation performance of PVB/PVDF were systematically studied.The results showed that the electron transport capacity was effectively enhanced due to the high conductivity of IL,thus allowing a significant reduction in the volume and surface resistivity of the PVDF fibre film,consequently a substantial increase in the output voltage.In addition,the low vapour pressure of IL was used to fill the pores of the fibre film,thus improving the preparation process of the transparent composite film.The results were as follows:When the IL content was 1.5 mg/cm~3,the output voltage of the fiber film was increased by 1.8 times(1.95 V).Compared to pure PVB film,ATL of PVB/PVDF composite film was improved by 4.7 d B(64-1600 Hz).The ATL of the PVB/PVDF/IL/1.5 composite film increased by8.3 d B compared to PVB/L2 due to the increase in thickness of the composite film resulting from the change in the composite method.The bonding strength of PVB/PVDF/IL/1.5 was 5.6 MPa.The transmittance of the laminated glass was 85%,and the mass breaking rate in the impact resistance test was 1.23%(50 g steel ball was impacted 7 times at 100 cm).The preparation method of transparent composite fiber film at normal temperature and pressure significantly reduces raw material waste and provides a new approach for large-scale industrial production.(4)Porous PVB acoustic films and its laminated glass were prepared.Water was introduced as an additive into the PVB extrusion process,using vapor pressure generated by water within PVB molecules,with pore size and type being adjusted based on the water proportion.The results showed that microporous structure has little effect on the tensile strength,but the elongation at break will be significantly increased,due to the porosity disrupting the tensile stress.In addition,the transmission distance of sound waves was increased due to the porous structure,resulting in improved acoustic performance of the film.The results were as follows:when the water added was 4%,the tensile strength was28.1 MPa and the breaking elongation was 140%,the ATL was increased by 5.7 d B(500-1100 Hz).The transmittance of laminated glass was 88%,the mass breaking rate in the impact resistance test was 1.76%(50 g steel ball was impacted 7 times at 100 cm).The innovative approach solves the shortcomings of traditional PVB materials in terms of sound insulation at medium frequencies,mechanical properties and transmittance,offering a promising avenue for the development of porous transparent elastomer materials.(5)PVB/PVDF sound insulation film was successfully prepared and processed into laminated glass at low temperatures.The surface hydroxyl group of PVB was enhanced by corona poling,making it easier to form hydrogen bonds with the glass surface and improving the interface bonding ability between PVB and glass.The results showed that the bonding strength and hydroxyl content on the PVB surface increases with the electric field intensity.The bonding strength between PVB and glass at 80°C reached 3.8 MPa.The mass breaking rate in the impact resistance test of laminated glass with PVB/PVDF composite film was only 1.01%(50 g steel ball was impacted 10 times at 100 cm).The combination of the porous structure and piezoelectric properties results in a 5.1 d B(64-1600 Hz)improvement in the ATL of the PVB/PVDF composite film.Corona poling not only reduces processing temperature,energy consumption and costs,but also prolongs material lifespan,offering promising applications in low temperature bonding.