Polyvinyl butyral composite membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of functional material preparation, in particular to a polyvinyl butyral composite film as well as a preparation method and application thereof. The polyvinyl butyral composite film provided by the invention structurally comprises an X-type resin film and a Y-type resin film which are alternately laminated, and in polyvinyl butyral resin in the X-type resin film, syndiotactic triol type hydroxyl groups are concentrated in the middle section of a molecular chain to provide mechanical support; isotactriol type hydroxyl groups are distributed at two ends of a molecular chain, so that the compatibility with a plasticizer is improved. In the polyvinyl butyral resin in the Y-type resin film, isotactic triol type hydroxyl groups are concentrated in the middle sections of molecular chains, so that the acting force between the molecular chains is enhanced; homotriol hydroxyl groups are distributed at two ends of a molecular chain, so that the interface bonding force between the molecular chain and an adjacent film layer is improved. By means of the multi-layer composite structure, the micro gradient combining hardness and softness is constructed, and the overall mechanical property and interlayer binding force of the material are synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of functional material preparation technology, and in particular to a polyvinyl butyral (PVB) composite film, its preparation method, and its application. Background Technology

[0002] Laminated glass, a common type of safety glass, is widely used in transportation (automobiles or high-speed trains) and construction. This is because the interlayer in laminated glass structure provides the safety characteristic of preventing shards from flying everywhere when broken. As the core functional component of laminated glass, the performance of the interlayer directly determines its safety and durability. Polyvinyl butyral resin, a common material for interlayer glass, is of great significance for modification.

[0003] To improve the performance of polyvinyl butyral resin, some technicians have proposed adjusting the butyl content and the total proportion of triol-type hydroxyl groups to enhance its properties. However, this method only considers the total content of triol-type hydroxyl groups and does not address the impact of their segment distribution on performance. Practical applications show that the segment distribution of triol-type hydroxyl groups directly affects the intermolecular forces, compatibility with plasticizers, and film adhesion of polyvinyl butyral resin. Random distribution leads to fluctuations in the mechanical properties of polyvinyl butyral resin.

[0004] Furthermore, the existing preparation methods for polyvinyl butyral intermediate films are mainly single extrusion molding, which lacks process matching for the directional distribution of chain segments. This results in the inability to accurately control the distribution of triol-type hydroxyl segments, and the processing indicators such as film thickness uniformity and edge smoothness are prone to deviation.

[0005] Therefore, developing a polyvinyl butyral resin intermediate film with synergistic mechanical and processing properties is of great significance and application value. Summary of the Invention

[0006] In view of this, the present invention provides a polyvinyl butyral composite film, its preparation method and application. The polyvinyl butyral composite film provided by the present invention has excellent synergy between mechanical properties and processing properties.

[0007] This invention provides a polyvinyl butyral composite film, comprising alternating layers of an X-type resin film and a Y-type resin film; the X-type resin film comprises a first polyvinyl butyral resin and a first plasticizer; the triol-type hydroxyl segments of the first polyvinyl butyral resin are distributed as follows: syndiotropic triol-type hydroxyl groups are distributed in the middle segment of the molecular chain, accounting for 60-70% of the triol-type hydroxyl groups; isotropic triol-type hydroxyl groups are distributed at both ends of the molecular chain, accounting for 20-30% of the triol-type hydroxyl groups; and atactic triol-type hydroxyl groups account for 10-15% of the triol-type hydroxyl groups; the Y-type resin film comprises a second polyvinyl butyral resin and a second plasticizer; the triol-type hydroxyl segments of the second polyvinyl butyral resin are distributed as follows: isotropic triol-type hydroxyl groups are distributed in the middle segment of the molecular chain, accounting for 50-60% of the triol-type hydroxyl groups; syndiotropic triol-type hydroxyl groups are distributed at both ends of the molecular chain, accounting for 30-40% of the triol-type hydroxyl groups; and atactic triol-type hydroxyl groups account for 10-15% of the triol-type hydroxyl groups.

[0008] Preferably, the butyl content (determined by proton nuclear magnetic resonance spectroscopy) of the first polyvinyl butyral resin is 58-62 mol; the total proportion of triol-type hydroxyl groups in the hydroxyl groups of the first polyvinyl butyral resin is 8-12%; the butyl content (determined by proton nuclear magnetic resonance spectroscopy) of the second polyvinyl butyral resin is 62-68 mol; and the total proportion of triol-type hydroxyl groups in the hydroxyl groups of the second polyvinyl butyral resin is 25-35%.

[0009] Preferably, the thickness of a single layer of the X-type resin film is 0.08~0.3mm; the thickness of a single layer of the Y-type resin film is 0.08~0.3mm; and the total thickness of the polyvinyl butyral composite film is 0.4~1.4mm.

[0010] Preferably, the X-type resin film further includes an antioxidant; the mass ratio of the first polyvinyl butyral resin to the antioxidant is 100:0.05~0.15; the X-type resin film further includes an ultraviolet absorber; the mass ratio of the first polyvinyl butyral resin to the ultraviolet absorber is 100:0.05~0.15.

[0011] Preferably, the Y-type resin film further includes an antioxidant; the Y-type resin film further includes an ultraviolet absorber.

[0012] The present invention also provides a method for preparing the polyvinyl butyral composite film described in the above-mentioned scheme, comprising the following steps: (1) Polyvinyl alcohol, a first composite acid catalyst, water and a portion of n-butyraldehyde are mixed and subjected to a first acetalization reaction, a second acetalization reaction with the remaining n-butyraldehyde and aging to obtain a first polyvinyl alcohol butyraldehyde resin; the first polyvinyl alcohol butyraldehyde resin and a first plasticizer are mixed and subjected to melt extrusion and casting to obtain an X-type resin film. (2) Polyvinyl alcohol, second composite acid catalyst, water and part of n-butyraldehyde are mixed and subjected to a third acetalization reaction, a fourth acetalization reaction with the remaining n-butyraldehyde and aging to obtain a second polyvinyl alcohol butyraldehyde resin; the second polyvinyl alcohol butyraldehyde resin and the second plasticizer are mixed and subjected to melt extrusion and casting to obtain a Y-type resin film. (3) The X-type resin film and the Y-type resin film are compositely extruded to obtain the polyvinyl butyral composite film; There is no requirement for the time order of steps (1) and (2).

[0013] Preferably, in step (1), the first composite acid catalyst comprises hydrochloric acid and phosphoric acid; the mass ratio of hydrochloric acid to phosphoric acid is 2.5~3.5:1; the proportion of partial n-butyraldehyde to all n-butyraldehyde is 35~45%; the proportion of remaining n-butyraldehyde to all n-butyraldehyde is 55~65%; the temperature of the first acetalization reaction is 25~30℃, and the reaction time is 2~3 hours; the temperature of the second acetalization reaction is 40~45℃, and the holding time is 3~4 hours; the aging temperature is 70~75℃, and the holding time is 2~3 hours.

[0014] Preferably, in step (2), the second composite acid catalyst comprises hydrochloric acid and sulfuric acid; the mass ratio of hydrochloric acid to sulfuric acid is 3.5~4.5:1; the proportion of partial n-butyraldehyde to all n-butyraldehyde is 55~65%; the proportion of remaining n-butyraldehyde to all n-butyraldehyde is 35~45%; the temperature of the third acetalization reaction is 35~40℃, and the reaction time is 3~4 hours; the temperature of the fourth acetalization reaction is 50~55℃, and the holding time is 4~5 hours; the aging temperature is 80~85℃, and the holding time is 3~4 hours.

[0015] The present invention also provides the application of the polyvinyl butyral composite film described in the above-described scheme or the polyvinyl butyral composite film obtained by the preparation method described in the above-described scheme as an interlayer film in laminated glass.

[0016] The present invention also provides a laminated glass, comprising an interlayer and glass plates adhered to both sides of the interlayer; the interlayer is a polyvinyl butyral composite film as described in the above-described scheme or a polyvinyl butyral composite film prepared by the above-described scheme.

[0017] This invention provides a polyvinyl butyral composite membrane. The polyvinyl butyral composite membrane provided by this invention structurally comprises two alternating layers of resin membranes (X-type resin membrane and Y-type resin membrane). This invention constructs a molecular structure of "rigid support + flexible compatibility" by directionally controlling the distribution of triol-type hydroxyl segments in the polyvinyl butyral resin of the two resin membranes. This synergistically improves the mechanical properties (e.g., puncture resistance) and processing properties (e.g., processing stability) of the polyvinyl butyral composite membrane, and the synergy between mechanical and processing properties is excellent. Specifically, in the X-type resin membrane, the isomeric triol-type hydroxyl groups (with higher rigidity) are concentrated in the middle segment of the molecular chain, providing mechanical support; the isomeric triol-type hydroxyl groups (with better flexibility) are distributed at both ends of the molecular chain, improving compatibility with plasticizers. In the Y-type resin membrane, the isomeric triol-type hydroxyl groups are concentrated in the middle segment of the molecular chain, enhancing the inter-chain forces; the isomeric triol-type hydroxyl groups are distributed at both ends of the molecular chain, improving its interfacial bonding with adjacent membrane layers. This invention constructs a micro-gradient that combines rigidity and flexibility through the aforementioned multi-layer composite structure, thereby synergistically improving the overall mechanical properties and interlayer bonding force of the material.

[0018] This invention also provides a method for preparing the polyvinyl butyral composite film described in the above-mentioned scheme. The core innovation of the preparation method provided by this invention lies in the directional control of the segmental distribution of isotropic, meta-isotropic, and atactic triol hydroxyl groups in the polyvinyl butyral resin through a segmented condensation reaction, combined with specific butyl content, plasticizer addition amount, and composite molding, enabling the polyvinyl butyral composite film to possess excellent penetration resistance, transparency, and processing stability. The preparation method provided by this invention has high precision and is compatible with existing industrial production equipment.

[0019] The inventors have discovered that the reactivity of segmented condensation reactions is significantly affected by temperature and steric hindrance. At lower temperatures (e.g., 25–40 °C) and with lower catalyst activity, n-butyraldehyde preferentially reacts with hydroxyl groups at the ends of the molecular chain, which are more mobile and have less steric hindrance, readily forming isomeric triol structures. However, at higher temperatures (e.g., 40–55 °C) and with higher catalyst activity, the reaction focuses on hydroxyl groups in the middle of the molecular chain, which have greater steric hindrance, thus favoring the formation of meta-isomeric triol structures. This invention utilizes segmented temperature control ("low temperature first, then high temperature") combined with a segmented dropwise addition method of n-butyraldehyde to guide the preferential generation and enrichment of triol-type hydroxyl groups with specific configurations at predetermined positions (ends or middle segments) of the molecular chain, thereby achieving directional control of chain segment distribution. Subsequent aging further stabilizes this microstructure and prevents chain segment rearrangement at high temperatures.

[0020] This invention also provides the application of the polyvinyl butyral composite film described in the above-described scheme or the polyvinyl butyral composite film prepared by the above-described scheme as an interlayer film in laminated glass. The polyvinyl butyral composite film provided by this invention is suitable for use in laminated glass, especially for the preparation of high-end safety glass in transportation (automobiles, high-speed rail) or construction fields, and has broad application prospects.

[0021] This invention also provides a laminated glass. The laminated glass provided by this invention has good safety and high stability, and is suitable for high-end applications in the construction or transportation sectors. Attached Figure Description

[0022] 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.

[0023] Figure 1 Comparison of the penetration resistance of polyvinyl butyral composite films or intermediate films in Examples 1-5 and Comparative Examples 1-4; Figure 2 The graphs show a comparison of the thickness uniformity of the polyvinyl butyral composite films or intermediate films in Examples 1-5 and Comparative Examples 1-4. Detailed Implementation

[0024] This invention provides a polyvinyl butyral composite film, comprising alternating layers of an X-type resin film and a Y-type resin film; the X-type resin film comprises a first polyvinyl butyral resin and a first plasticizer; the triol-type hydroxyl segments of the first polyvinyl butyral resin are distributed as follows: syndiotropic triol-type hydroxyl groups are distributed in the middle segment of the molecular chain, accounting for 60-70% of the triol-type hydroxyl groups; isotropic triol-type hydroxyl groups are distributed at both ends of the molecular chain, accounting for 20-30% of the triol-type hydroxyl groups; and atactic triol-type hydroxyl groups account for 10-15% of the triol-type hydroxyl groups; the Y-type resin film comprises a second polyvinyl butyral resin and a second plasticizer; the triol-type hydroxyl segments of the second polyvinyl butyral resin are distributed as follows: isotropic triol-type hydroxyl groups are distributed in the middle segment of the molecular chain, accounting for 50-60% of the triol-type hydroxyl groups; syndiotropic triol-type hydroxyl groups are distributed at both ends of the molecular chain, accounting for 30-40% of the triol-type hydroxyl groups; and atactic triol-type hydroxyl groups account for 10-15% of the triol-type hydroxyl groups.

[0025] The polyvinyl butyral composite membrane provided by the present invention includes an X-type resin membrane; the butyl content (determined by proton nuclear magnetic resonance spectroscopy) of the first polyvinyl butyral resin is preferably 58-62 mol%, more preferably 60 mol%; the total proportion of triol-type hydroxyl groups in the hydroxyl groups of the first polyvinyl butyral resin is preferably 8-12%, more preferably 10%.

[0026] In this invention, the first plasticizer preferably includes one or more of triethylene glycol di-2-ethylbutyrate and triethylene glycol di-2-ethylhexanoate.

[0027] In this invention, the mass ratio of the first polyvinyl butyral resin to the first plasticizer is preferably 100:35~45, more preferably 100:38~42, and even more preferably 100:40.

[0028] In this invention, the X-type resin film preferably further includes an antioxidant; the antioxidant preferably includes t-butyl-hydroxytoluene (BHT); the mass ratio of the first polyvinyl butyral resin to the antioxidant is preferably 100:0.05~0.15, more preferably 100:0.08~0.12, and even more preferably 100:0.1.

[0029] In this invention, the X-type resin film preferably further includes an ultraviolet absorber; the ultraviolet absorber preferably includes 2-(2'-hydroxy-5'-methylphenyl)benzotriazole; the mass ratio of the first polyvinyl butyral resin to the ultraviolet absorber is preferably 100:0.05~0.15, more preferably 100:0.08~0.12, and even more preferably 100:0.1.

[0030] In this invention, the thickness of a single layer of the X-type resin film is preferably 0.08~0.3mm, more preferably 0.1~0.2mm.

[0031] In this invention, the X-type resin film preferably has one or more layers, specifically one, two, three, four or five layers.

[0032] The polyvinyl butyral composite membrane provided by the present invention includes a Y-type resin membrane; the butyl content (determined by proton nuclear magnetic resonance spectroscopy) of the second polyvinyl butyral resin is preferably 62-68 mol%, more preferably 64-66 mol%; the total proportion of triol-type hydroxyl groups in the hydroxyl groups of the second polyvinyl butyral resin is preferably 25-35%, more preferably 30%.

[0033] In this invention, the second plasticizer preferably includes one or more of triethylene glycol di-2-ethylbutyrate and triethylene glycol di-2-ethylhexanoate.

[0034] In this invention, the mass ratio of the second polyvinyl butyral resin and the second plasticizer is preferably 100:38~48, more preferably 100:40~45, and even more preferably 100:42~43.

[0035] In this invention, the Y-type resin film preferably further includes an antioxidant; the type and amount of the antioxidant are preferably the same as those of the X-type resin film, and will not be described again here.

[0036] In this invention, the Y-type resin film preferably further includes an ultraviolet absorber; the type and amount of the ultraviolet absorber are preferably the same as those of the X-type resin film, and will not be described again here.

[0037] In this invention, the thickness of a single layer of the Y-type resin film is preferably 0.08~0.3mm, more preferably 0.1~0.2mm.

[0038] In this invention, the Y-type resin film preferably has one or more layers, specifically one, two, three, four, or five layers.

[0039] In this invention, the total thickness of the polyvinyl butyral composite film is preferably 0.4~1.4 mm, more preferably 0.6~1.2 mm, and even more preferably 0.8~1 mm.

[0040] The present invention also provides a method for preparing the polyvinyl butyral composite film described in the above-mentioned scheme, comprising the following steps: (1) Polyvinyl alcohol, a first composite acid catalyst, water and a portion of n-butyraldehyde are mixed and subjected to a first acetalization reaction, a second acetalization reaction with the remaining n-butyraldehyde and aging to obtain a first polyvinyl alcohol butyraldehyde resin; the first polyvinyl alcohol butyraldehyde resin and a first plasticizer are mixed and subjected to melt extrusion and casting to obtain an X-type resin film. (2) Polyvinyl alcohol, second composite acid catalyst, water and part of n-butyraldehyde are mixed and subjected to a third acetalization reaction, a fourth acetalization reaction with the remaining n-butyraldehyde and aging to obtain a second polyvinyl alcohol butyraldehyde resin; the second polyvinyl alcohol butyraldehyde resin and the second plasticizer are mixed and subjected to melt extrusion and casting to obtain a Y-type resin film. (3) The X-type resin film and the Y-type resin film are compositely extruded to obtain the polyvinyl butyral composite film; There is no requirement for the time order of steps (1) and (2).

[0041] This invention involves mixing polyvinyl alcohol, a first composite acid catalyst, water, and a portion of n-butyraldehyde (referred to as the first mixture) and sequentially performing a first acetalization reaction, a second acetalization reaction with the remaining n-butyraldehyde, and aging (referred to as the first aging) to obtain a first polyvinyl alcohol butyraldehyde resin. In this invention, the average degree of polymerization of the polyvinyl alcohol is preferably 1500-2500, and the degree of alcoholysis is preferably not less than 99 mol%.

[0042] In this invention, the first composite acid catalyst preferably comprises hydrochloric acid and phosphoric acid; the mass ratio of hydrochloric acid to phosphoric acid is preferably 2.5~3.5:1, more preferably 3:1.

[0043] In this invention, the total concentration of the first composite acid catalyst (the sum of the concentrations of HCl and phosphoric acid) is preferably 30-32 wt%, more preferably 31 wt%.

[0044] In this invention, the water is preferably deionized water.

[0045] In this invention, the proportion of the n-butyraldehyde to the total n-butyraldehyde is preferably 35-45%, more preferably 40%.

[0046] In this invention, the first mixing preferably includes the following steps: mixing polyvinyl alcohol and water (referred to as mixture A) to obtain a polyvinyl alcohol aqueous solution, then mixing the polyvinyl alcohol aqueous solution with a first composite acid catalyst (referred to as mixture B) to obtain a premixed solution, and then adding (referred to as the first addition) a portion of n-butyraldehyde to the premixed solution.

[0047] In this invention, the mixture A is preferably stirred and mixed; the temperature of the mixture A is preferably 95~98℃, more preferably 96~97℃, and the heat preservation time is preferably 3~4 hours, more preferably 3.5 hours.

[0048] In this invention, the mass concentration of the polyvinyl alcohol aqueous solution is preferably 10-12%, more preferably 11%.

[0049] In this invention, the process of mixing A and mixing B preferably includes cooling; the final temperature of the cooling is preferably 25~30°C, more preferably 27°C.

[0050] In this invention, the mass ratio of the first composite acid catalyst to the polyvinyl alcohol aqueous solution is preferably 2~3:100, more preferably 2.5:100.

[0051] In this invention, the mixture B is preferably stirred and mixed; the temperature of the mixture B is preferably 25~30℃, more preferably 27℃.

[0052] In this invention, the first dripping rate is preferably 3 to 5 minutes, more preferably 4.5 minutes.

[0053] In this invention, the temperature of the first acetalization reaction is preferably 25~30°C, more preferably 27°C, and the reaction time is preferably 2~3 hours, more preferably 2.5 hours.

[0054] In this invention, the proportion of the remaining n-butyraldehyde to the total n-butyraldehyde is preferably 55-65%, more preferably 60%.

[0055] In this invention, the remaining n-butyraldehyde is preferably added to the reaction system of the first acetalization reaction in the form of dropwise addition (denoted as the second dropwise addition); the rate of the second dropwise addition is preferably the same as the rate of the first dropwise addition, which will not be repeated here.

[0056] In this invention, the temperature of the second acetalization reaction is preferably 40~45°C, more preferably 42°C, and the holding time is preferably 3~4 hours, more preferably 3.5 hours.

[0057] In this invention, the temperature of the first curing is preferably 70~75℃, more preferably 72℃, and the heat preservation time is preferably 2~3 hours, more preferably 2.5 hours.

[0058] In this invention, the first curing process preferably further includes a first post-treatment of the resulting reaction system; the first post-treatment preferably includes neutralization to a pH of 6.5-7.5, washing with water, drying, and pulverizing in sequence; the neutralization reagent is preferably an aqueous solution of sodium hydroxide; the mass concentration of the aqueous solution of sodium hydroxide is preferably 5-8%, more preferably 6-7%; the washing is preferably stopped after no chloride ions are detected; the drying temperature is preferably 60-70°C, and the holding time is preferably 8-10 hours; the drying is preferably vacuum drying; the vacuum degree of the vacuum drying is preferably -0.092 to -0.096 MPa, more preferably -0.094 MPa. Through the above drying process, this invention enables the moisture content of the first polyvinyl butyral resin to be below 0.3%.

[0059] After obtaining the first polyvinyl butyral resin, the present invention mixes the first polyvinyl butyral resin and the first plasticizer (denoted as the second mixture) and sequentially performs melt extrusion (denoted as the first melt extrusion) and casting (denoted as the first casting) to obtain an X-type resin film. In the present invention, when the X-type resin film includes an antioxidant and a UV absorber, the raw materials of the second mixture preferably further include an antioxidant and a UV absorber.

[0060] In this invention, the temperature of the second mixture is preferably 80~90°C, more preferably 85°C, and the heat preservation time is preferably 30~40 minutes, more preferably 35 minutes.

[0061] In this invention, the equipment for the first melt extrusion preferably includes a twin-screw extruder; the temperature of the first melt extrusion is preferably 140~160℃, specifically preferably: 140℃ for the feeding section, 150℃ for the compression section and 150℃ for the die head section, or 145℃ for the feeding section, 155℃ for the compression section and 155℃ for the die head section; the screw speed of the first melt extrusion is preferably 30~50 r / min, more preferably 40 r / min.

[0062] In this invention, after the first melt extrusion and before casting, it is preferable to further filter the resulting product; the pore size of the filter screen used for filtration is preferably 50 μm. This invention employs the aforementioned specific temperature and filtration precision to ensure the purity and fluidity of the melt.

[0063] In this invention, the first casting device preferably includes a T-shaped die; the casting is preferably extrusion casting; the parameters of the extrusion casting preferably include: die temperature preferably 145~155℃, more preferably 150℃; die gap preferably 0.1~0.35mm, more preferably 0.2~0.25mm; extrusion rate preferably 0.5~1.5m / min, more preferably 1m / min; melt pressure preferably 5~10MPa, more preferably 6~8MPa. This invention uses the above-mentioned die temperature to match the temperature of the die head section of the first melt extrusion, avoiding melt agglomeration during cooling; the die gap of this invention is adjusted according to the target single-layer thickness of the resin film, reserving a margin for subsequent cooling shrinkage; the extrusion rate of this invention is coordinated with the linear speed of the cooling roller to ensure uniform film thickness of the resin film; this invention ensures stable melt flow out of the die head by adjusting the screw speed.

[0064] In this invention, the first casting process preferably includes cooling the resulting product; the cooling temperature is preferably 25-30°C; the cooling is preferably achieved using a cooling roller; the ratio of the linear speed of the cooling roller to the speed of the extrusion casting is preferably 1-1.2:1, more preferably 1.1:1. This invention eliminates internal stress by controlling the linear speed ratio.

[0065] In this invention, the cooling process preferably further includes sequentially performing online thickness measurement, edge trimming, and winding of the obtained product; the width of the trimmed edge is preferably 5~10mm, more preferably 7~8mm; the winding process preferably uses a tension of 5~8N.

[0066] This invention involves mixing polyvinyl alcohol, a second composite acid catalyst, water, and a portion of n-butyraldehyde (referred to as the third mixture) and sequentially performing a third acetalization reaction, a fourth acetalization reaction with the remaining n-butyraldehyde, and aging (referred to as the second aging) to obtain a second polyvinyl alcohol butyral resin. In this invention, the average degree of polymerization of the polyvinyl alcohol is preferably 1500-2500, and the degree of alcoholysis is preferably not less than 99 mol%.

[0067] In this invention, the second composite acid catalyst preferably comprises hydrochloric acid and sulfuric acid; the mass ratio of hydrochloric acid to sulfuric acid is preferably 3.5~4.5:1, more preferably 4:1.

[0068] In this invention, the total concentration of the second composite acid catalyst (the sum of the concentrations of HCl and sulfuric acid) is preferably 30-32 wt%, more preferably 31 wt%.

[0069] In this invention, the water is preferably deionized water.

[0070] In this invention, the proportion of the n-butyraldehyde to the total n-butyraldehyde is preferably 55-65%, more preferably 60%.

[0071] In this invention, the second mixing preferably includes the following steps: mixing polyvinyl alcohol and water (denoted as mixture C) to obtain a polyvinyl alcohol aqueous solution, then mixing the polyvinyl alcohol aqueous solution with a second composite acid catalyst (denoted as mixture D) to obtain a premixed solution, and then adding (denoted as the third addition) a portion of n-butyraldehyde to the premixed solution.

[0072] In this invention, the mixture C is preferably stirred and mixed; the temperature of the mixture C is preferably 95~98℃, more preferably 96~97℃, and the heat preservation time is preferably 3~4 hours, more preferably 3.5 hours.

[0073] In this invention, the mass concentration of the polyvinyl alcohol aqueous solution is preferably 10-12%, more preferably 11%.

[0074] In this invention, the process of mixing C and mixing D preferably includes cooling; the final temperature of the cooling is preferably 35~40°C, more preferably 38°C.

[0075] In this invention, the mass ratio of the second composite acid catalyst to the polyvinyl alcohol aqueous solution is preferably 2.5~3.5:100, more preferably 3:100.

[0076] In this invention, the mixing D is preferably stirred and mixed; the temperature of the mixing D is preferably 35~40℃, more preferably 38℃.

[0077] In this invention, the rate of the third drop addition is preferably 3 to 5 minutes, more preferably 4.5 minutes.

[0078] In this invention, the temperature of the third acetalization reaction is preferably 35~40°C, more preferably 38°C, and the reaction time is preferably 3~4 hours, more preferably 3.5 hours.

[0079] In this invention, the proportion of the remaining n-butyraldehyde to the total n-butyraldehyde is preferably 35-45%, more preferably 40%.

[0080] In this invention, the remaining n-butyraldehyde is preferably added to the reaction system of the first acetalization reaction in the form of dropwise addition (denoted as the fourth dropwise addition); the rate of the fourth dropwise addition is preferably the same as the rate of the third dropwise addition, which will not be repeated here.

[0081] In this invention, the temperature of the fourth acetalization reaction is preferably 50~55°C, more preferably 52°C, and the holding time is preferably 4~5 hours, more preferably 4.5 hours.

[0082] In this invention, the temperature of the second curing is preferably 80~85°C, more preferably 82°C, and the heat preservation time is preferably 3~4 hours, more preferably 3.5 hours.

[0083] In this invention, the second curing process preferably further includes a second post-treatment of the resulting reaction system; the second post-treatment preferably includes neutralization to a pH of 6.5-7.5, washing with water, drying, and pulverizing in sequence; the neutralization reagent is preferably an aqueous solution of sodium hydroxide; the mass concentration of the aqueous solution of sodium hydroxide is preferably 5-8%, more preferably 6-7%; the washing with water is preferably stopped after the absence of chloride ions; the drying temperature is preferably 60-70°C, and the holding time is preferably 8-10 hours; the drying is preferably vacuum drying; the vacuum degree of the vacuum drying is preferably -0.092 to -0.096 MPa, more preferably -0.094 MPa. Through the above drying process, this invention enables the second polyvinyl butyral resin to have a water content of less than 0.3%.

[0084] This invention targets polyvinyl butyral resins with different chain segment distributions, employing different temperature programs, composite acid catalysts, and n-butyraldehyde addition ratios to ensure the successful preparation of the target polyvinyl butyral resins.

[0085] After obtaining the second polyvinyl butyral resin, the present invention mixes the second polyvinyl butyral resin and the second plasticizer, and sequentially performs melt extrusion and casting to obtain a Y-type resin film. In the present invention, the preparation steps of the Y-type resin film are the same as those of the X-type resin film, and will not be repeated here.

[0086] After obtaining the X-type resin film and the Y-type resin film, the present invention performs composite extrusion of the X-type resin film and the Y-type resin film to obtain the polyvinyl butyral composite film. In the present invention, the composite extrusion process preferably includes stacking the X-type resin film and the Y-type resin film according to a target structure; the target structure preferably includes X-type resin film / Y-type resin film / X-type resin film, Y-type resin film / X-type resin film / Y-type resin film, X-type resin film / Y-type resin film / X-type resin film / Y-type resin film / X-type resin film or Y-type resin film / X-type resin film / Y-type resin film / X-type resin film / Y-type resin film.

[0087] In this invention, the equipment for compound extrusion preferably includes a multi-layer compound extruder; the temperature of the compound extrusion is preferably 130~150℃, specifically preferably 130℃ for the feeding section, 140℃ for the compression section and 140℃ for the die head section; the screw speed of the compound extrusion is preferably 25~40 r / min, more preferably 30~35 r / min.

[0088] In this invention, the composite extrusion process preferably includes cooling the resulting product; the cooling is preferably performed using a gradient cooling roller group; the temperature of the gradient cooling roller group is preferably distributed between 20 and 25°C, specifically: 25°C for the first section, 22°C for the second section, and 20°C for the third section.

[0089] In this invention, the cooling process preferably further includes sequentially performing online thickness measurement, edge trimming, and winding of the resulting product; the winding process preferably uses a tension of 8~12N.

[0090] This invention uses composite extrusion and gradient cooling, combined with online thickness measurement and tension-controlled winding, to ensure that the polyvinyl butyral composite film has uniform thickness, good interface fusion, and no warping or deformation.

[0091] In this invention, the segment distribution ratio of triol-type hydroxyl groups is determined by nuclear magnetic resonance hydrogen spectroscopy (NMR 1H NMR spectroscopy). 1 The determination was performed using 1H NMR combined with selective hydrolysis analysis.

[0092] The present invention also provides the application of the polyvinyl butyral composite film described in the above-described scheme or the polyvinyl butyral composite film obtained by the preparation method described in the above-described scheme as an interlayer film in laminated glass.

[0093] The polyvinyl butyral composite film provided by this invention is suitable for use in laminated glass, especially for the preparation of high-end safety glass in transportation (automobiles, high-speed rail) or construction fields, and has broad application prospects.

[0094] The present invention also provides a laminated glass, comprising an interlayer and glass plates adhered to both sides of the interlayer; the interlayer is a polyvinyl butyral composite film as described in the above-described scheme or a polyvinyl butyral composite film prepared by the above-described scheme.

[0095] 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.

[0096] Example 1 This embodiment prepares a polyvinyl butyral composite membrane with an X-type resin membrane / Y-type resin membrane / X-type resin membrane. The specific steps are as follows: (1) Preparation of the first polyvinyl butyral resin: a. Take 300 parts by mass of polyvinyl alcohol with an average degree of polymerization of 1800 and a degree of alcoholysis of 99 mol%, add 2700 parts by mass of deionized water, put it into a reactor equipped with a stirrer, stir and heat to 96°C, keep warm and dissolve for 3.5 hours to obtain a 10% polyvinyl alcohol aqueous solution. b. Cool the above polyvinyl alcohol aqueous solution to 28°C, add 75 parts by mass of composite acid catalyst (hydrochloric acid and phosphoric acid are mixed in a mass ratio of 3:1, with a total concentration of 31wt%), and stir until uniform; c. First stage reaction: 62 parts by mass of n-butyraldehyde were added dropwise to the above polyvinyl alcohol aqueous solution over 4.5 minutes, and the reaction was carried out at a constant temperature of 28°C for 2.5 hours. d. Second stage reaction: Continue to add 93 parts by mass of n-butyraldehyde, and complete the addition in 4.5 minutes. After the addition is complete, raise the temperature to 42°C and keep the reaction at a constant temperature for 3.5 hours. e. Curing and Post-treatment: The resin was heated to 72℃ and cured for 2.5 hours. Then, it was neutralized to pH 7.0 with a 6% sodium hydroxide aqueous solution, and washed repeatedly with water four times (each time soaked and stirred in deionized water at four times the resin's mass for 12 minutes, filtered, and the washing water was tested) until no white precipitate (no chloride ion residue) was observed when titrated with silver nitrate solution. It was then vacuum dried at 65℃ and -0.094 MPa for 9 hours, and pulverized to a particle size of 80 mesh to obtain the first polyvinyl butyral resin. Testing revealed: butyl content 60 mol%, total triol hydroxyl content 10%, and chain segment distribution: 65% syndiomeric (mid-segment), 25% isomeric (both ends), and 10% atactic.

[0097] (2) Preparation of the second polyvinyl butyral resin: a. Take 300 parts by mass of polyvinyl alcohol with an average degree of polymerization of 2000 and a degree of alcoholysis of 99.5 mol%, add 2700 parts by mass of deionized water, put it into a reaction vessel, stir and heat to 97°C, keep warm and dissolve for 3.5 hours to obtain a 10% polyvinyl alcohol aqueous solution. b. Cool the polyvinyl alcohol aqueous solution to 38°C, add 90 parts by weight of composite acid catalyst (hydrochloric acid and sulfuric acid mixed in a mass ratio of 4:1, with a total concentration of 31wt%), and stir until homogeneous; c. First stage reaction: 96 parts by mass of n-butyraldehyde were added dropwise to the above polyvinyl alcohol aqueous solution over 4.5 minutes, and the reaction was carried out at a constant temperature of 38°C for 3.5 hours. d. Second stage reaction: Continue to add 64 parts by mass of n-butyraldehyde to the polyvinyl alcohol aqueous solution, and complete the addition in 4.5 minutes. After the addition is complete, raise the temperature to 52°C and keep the reaction at a constant temperature for 4.5 hours. e. Curing and Post-treatment: The resin was heated to 82℃ and cured for 3.5 hours; neutralized to pH 7.0 with a 6% sodium hydroxide aqueous solution, and washed repeatedly with water 4 times (testing standards are the same as in step 1). After removing any chloride ion residue, it was vacuum dried at 65℃ and -0.094 MPa for 9 hours, and then pulverized to a particle size of 80 mesh to obtain the second polyvinyl butyral resin. Testing revealed: butyl content 65 mol%, total triol hydroxyl content 30%, and chain segment distribution of 55% isotropic (mid-segment), 35% syndiotropic (ends), and 10% atactic.

[0098] (3) Preparation of X-type resin film: a. Take 100 parts by weight of the first polyvinyl butyral resin, 40 parts by weight of the plasticizer triethylene glycol di-2-ethylbutyrate, 0.1 parts by weight of the antioxidant BHT, and 0.1 parts by weight of the ultraviolet absorber 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, add them to a high-speed mixer, and mix at 85°C for 35 minutes to obtain a uniform premix. b. Add the above premixed material to a twin-screw extruder and set the extrusion temperature as follows: 140°C for the feeding section, 150°C for the compression section, and 150°C for the die head section. The screw speed is 40 r / min. After filtering through a 50 μm filter screen, the material is extruded and cast through a T-die: the die head temperature is 150°C, the die head gap is 0.22 mm, the extrusion rate is 1 m / min, and the melt pressure is 7 MPa. c. The cast film is cooled by a 28°C cooling roller, and the ratio of the cooling roller linear speed to the extrusion speed is controlled to be 1.1; d. After being inspected by an online thickness gauge (accuracy ±0.005mm), the edges of the film were trimmed (trimmed width 8mm), and then wound up under a tension of 6N to obtain an X-type resin film with a thickness of 0.2mm and a width of 1200mm.

[0099] (4) Preparation of Y-type resin membrane: a. Take 100 parts by weight of the second polyvinyl butyral resin, 43 parts by weight of the plasticizer triethylene glycol di-2-ethylhexanoate, 0.1 parts by weight of the antioxidant BHT and 0.1 parts by weight of the ultraviolet absorber 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, add them to a high-speed mixer, and mix at 85°C for 35 minutes to obtain a uniform premix. b. Add the above premixed material to a twin-screw extruder and set the extrusion temperature as follows: feeding section 145℃, compression section 155℃, die head section 155℃, screw speed 40r / min. After filtering through a 50μm filter screen, extrude the material through a T-die: die head temperature 150℃, die head gap 0.22mm, extrusion rate 1m / min, melt pressure 7MPa. c. The cast film is cooled by a 28°C cooling roller, and the ratio of the cooling roller linear speed to the extrusion speed is controlled to be 1.1; d. After being inspected by an online thickness gauge, the edges were trimmed (edge ​​width 8mm), and the film was wound up under a tension of 6N to obtain a Y-shaped resin film with a thickness of 0.2mm and a width of 1200mm.

[0100] (5) Composite molding: a. Stack the prepared resin films in the order of X-type resin film / Y-type resin film / X-type resin film, align the edges, and feed them into the feed port of the multilayer composite extruder; b. Set the compound extrusion temperature: 130℃ for the feeding section, 140℃ for the compression section and 140℃ for the die head section, and the screw speed is 35r / min. After extrusion through the compound die head, the material enters the gradient cooling roller group (first cooling roller 25℃, second cooling roller 22℃, third cooling roller 20℃) for cooling. c. After cooling, the composite film is inspected twice by an online thickness gauge (total thickness 0.6 mm, deviation ±0.008 mm), and the edges are trimmed (trimmed width 10 mm). The film is then wound up under a tension of 10 N to obtain a polyvinyl butyral composite film with directional control of the distribution of triol-type hydroxyl segments.

[0101] (6) Finished product inspection and packaging: The sampling test showed that the total light transmittance was 91.2%, the penetration resistance was 8.2m, the maximum deviation of thickness uniformity was ±0.008mm, and the thermal stability (80℃ / 100h) was normal. The qualified products were cut to standard size and then vacuum-packed and stored.

[0102] Example 2 This embodiment prepared a polyvinyl butyral composite film with a structure of Y-type resin film / X-type resin film / Y-type resin film. The preparation method was the same as in Example 1, except that the thickness of each X-type resin film and Y-type resin film was 0.25 mm. The composite molding was carried out by stacking Y-type resin film / X-type resin film / Y-type resin film in sequence. The composite extrusion temperature was 135°C in the feeding section, 145°C in the compression section, and 145°C in the die head section. The screw speed was 32 r / min, and the winding tension was 11 N, resulting in a polyvinyl butyral composite film with a total thickness of 0.75 mm.

[0103] Example 3 This embodiment prepared a polyvinyl butyral composite membrane with a structure of X-type resin membrane / Y-type resin membrane / X-type resin membrane / Y-type resin membrane / X-type resin membrane. The preparation method is the same as in Example 1, except that: 1. Preparation of the first polyvinyl butyral resin: The curing temperature was adjusted to 70℃ to obtain the first polyvinyl butyral resin with butyl content of 59 mol% and triol hydroxyl content of 9%. The chain segment distribution was: 62% syndioid (middle segment), 28% isomorphic (both ends) and 10% random.

[0104] 2. Preparation of the second polyvinyl butyral resin: The curing temperature was adjusted to 80℃ to obtain a second polyvinyl butyral resin with a butyl content of 63 mol% and a total triol hydroxyl content of 28%. The chain segment distribution was as follows: 52% isotropic (mid segment), 38% synisotropic (both ends), and 10% random.

[0105] 3. Preparation of X-type and Y-type resin membranes: The thickness of each membrane is 0.15 mm.

[0106] 4. Composite molding: The resin film is stacked in the following order: X-type resin film / Y-type resin film / X-type resin film / Y-type resin film / X-type resin film. The composite extrusion temperature is 130℃ in the feeding section, 138℃ in the compression section and 138℃ in the die head section. The screw speed is 30r / min and the winding tension is 9N to obtain a polyvinyl butyral composite film with a total thickness of 0.75mm.

[0107] Example 4 This embodiment prepared a polyvinyl butyral composite membrane with a structure of Y-type resin membrane / X-type resin membrane / Y-type resin membrane / X-type resin membrane / Y-type resin membrane. The preparation method is the same as in Example 1, except that: 1. Preparation of the first polyvinyl butyral resin: The curing temperature was adjusted to 75℃ to obtain the first polyvinyl butyral resin with 61 mol% butyl content and 11% total triol hydroxyl content. The chain segment distribution was: 68% syndioid (middle segment), 22% isomorphic (both ends) and 10% random.

[0108] 2. Preparation of the second polyvinyl butyral resin: The curing temperature was adjusted to 85℃ to obtain a second polyvinyl butyral resin with a butyl content of 67 mol% and a total triol hydroxyl content of 33%. The chain segment distribution was as follows: 58% isotropic (mid segment), 32% syndiotropic (both ends), and 10% random.

[0109] 3. Preparation of X-type and Y-type resin membranes: The thickness of each membrane is 0.12 mm.

[0110] 4. Composite molding: The Y-type resin film / X-type resin film / Y-type resin film / X-type resin film / Y-type resin film are stacked in the following order. The composite extrusion temperature is 130℃ in the feeding section, 142℃ in the compression section and 142℃ in the die head section. The screw speed is 38r / min and the winding tension is 12N to obtain a polyvinyl butyral composite film with a total thickness of 0.6mm.

[0111] Example 5 This embodiment prepares a polyvinyl butyral composite membrane with an X-type resin membrane / Y-type resin membrane structure. The preparation method is the same as in Example 1, except that: 1. The thickness of both the X-type and Y-type resin films is 0.25 mm; 2. Composite molding: The X-type resin film and Y-type resin film are stacked in sequence. The composite extrusion temperature is 130℃ for the feeding section, 135℃ for the compression section and 135℃ for the die head section. The screw speed is 36r / min and the winding tension is 8N to obtain a polyvinyl butyral composite film with a total thickness of 0.5mm.

[0112] Comparative Example 1 This comparative example prepared a polyvinyl butyral composite membrane with undirected regulation of the triol-type hydroxyl segment distribution (random distribution). The preparation method was the same as in Example 1, except that: 1. Preparation of polyvinyl butyral resin (x'): A single-temperature reaction was adopted. Polyvinyl alcohol (degree of polymerization 1800, degree of alcoholysis 99.2 mol%), a single hydrochloric acid catalyst (concentration 35 wt%), and an addition amount of 2.5% were used. All n-butyral was added dropwise at one time, and the reaction was carried out at 35°C for 5 hours. The aging temperature was 65°C. Polyvinyl butyral resin (x') with butyl content of 60 mol% and triol-type hydroxyl content of 10% was obtained. The segment distribution was: 35% syndiomorphic, 30% isomorphic, and 35% random (random distribution).

[0113] 2. Preparation of polyvinyl butyral resin (y'): A single-temperature reaction was adopted. Polyvinyl alcohol (degree of polymerization 2000, degree of alcoholysis 99.5 mol%), a single hydrochloric acid catalyst (concentration 35 wt%), and an addition amount of 3.0% were used. All n-butyral was added dropwise at one time, and the reaction was carried out at 45℃ for 6 hours, with a curing temperature of 75℃. Polyvinyl butyral resin (y') with a butyl content of 65 mol% and a total triol hydroxyl content of 30% was obtained. The chain segment distribution was: 30% isoform, 35% syndioform, and 35% randomized.

[0114] 3. Preparation of polyvinyl butyral composite membrane: The polyvinyl butyral composite membrane with a total thickness of 0.6 mm is obtained by stacking X' type resin membrane / Y' type resin membrane / X' type resin membrane in an X' type resin membrane / Y' type resin membrane structure.

[0115] Comparative Example 2 This comparative example uses the PVB resin parameters from Japanese Patent Application Publication No. 7-330387. The specific steps are as follows: 1. Preparation of resin (a): According to the above patented method, polyvinyl alcohol (degree of polymerization 1720, degree of alcoholysis 99.1 mol%) was reacted with hydrochloric acid catalysis and n-butyraldehyde dropwise to obtain resin (a) with butyl content of 65 mol% and total triol hydroxyl content of 9.8%, with non-directional chain segment distribution design.

[0116] 2. Preparation of resin (b): According to the above patented method, polyvinyl alcohol (degree of polymerization 1500, degree of alcoholysis 99.5 mol%) was reacted with hydrochloric acid catalysis and n-butyraldehyde dropwise to obtain resin (b) with butyl content of 61 mol% and total triol hydroxyl content of 27.8%, with non-directional chain segment distribution design.

[0117] 3. Intermediate membrane preparation: The membrane is stacked in a structure of type A resin membrane / type B resin membrane / type A resin membrane, with a single membrane thickness of 0.3 mm and a total thickness of 0.9 mm. Other preparation processes are the same as those in the above patent.

[0118] Comparative Example 3 This comparative example uses only an X-type resin membrane, and the preparation method is the same as in Example 1, except that the thickness of the single membrane is 0.6 mm.

[0119] Comparative Example 4 This comparative example prepared a polyvinyl butyral composite membrane with a triol-type hydroxyl segment distribution exceeding the specified range. The preparation method was the same as in Example 1, except that: 1. Preparation of polyvinyl butyral resin (x"): The curing temperature was adjusted to 60℃ to obtain polyvinyl butyral resin (x") with 60 mol% butyl content and 10% total triol hydroxyl content. The chain segment distribution was: 55% syndioid (middle segment), 35% isomorphic (both ends) and 10% random (low proportion of syndioid middle segment).

[0120] 2. Preparation of polyvinyl butyral resin (y"): The curing temperature was adjusted to 90℃ to obtain polyvinyl butyral resin (y") with 65 mol% butyl content and 30% total triol hydroxyl content. The segment distribution was: 45% isomorphic (middle segment), 45% synisomorphic (both ends) and 10% random (low proportion of isomorphic middle segment).

[0121] 3. Preparation of polyvinyl butyral composite film: The polyvinyl butyral composite film is prepared by stacking X" type resin film / Y" type resin film / X" type resin film in sequence, with the thickness of each single film being 0.2 mm, to obtain a total thickness of 0.6 mm.

[0122] Test Example 1 The performance of the polyvinyl butyral composite films or intermediate films prepared in Examples 1-5 and Comparative Examples 1-4 was tested according to the following standards: 1) Total light transmittance: According to GB / T2680-2021 "Test Methods for Solar and Optical Performance of Architectural Glass"; 2) Penetration resistance: According to JISR3212 "Test methods for safety glass for automobiles", a 2.26kg steel ball was dropped freely to test and the average penetration resistance height was recorded; 3) Thickness uniformity: Using a high-precision thickness gauge (accuracy ±0.001 mm), 10 test points were randomly selected, and the maximum deviation was calculated; 4) Thermal stability: After being placed in an 80 ℃ oven for 100 hours, observe whether the film layer shows warping, bubbling, or discoloration. The test results are shown in Table 1 and... Figures 1-2 As shown: Table 1 Performance test results of Examples 1-5 and Comparative Examples 1-4

[0123] According to Table 1 and Figures 1-2As can be seen, in terms of penetration resistance, the penetration resistance height of the embodiments of the present invention is 7.5~8.2m, which is significantly higher than that of Comparative Example 1 (random distribution, 6.5m), Comparative Example 2 (existing patent, 7.5m), and Comparative Example 4 (distribution out of range, 6.8m). This indicates that the present invention can effectively improve the mechanical properties of the polyvinyl butyral composite film by directionally regulating the distribution of triol-type hydroxyl segments. Example 5, due to its simple structure (only two layers), has slightly lower penetration resistance, highlighting the importance of optimizing multilayer composite structures.

[0124] Regarding transparency: the total light transmittance of the embodiments of the present invention is 89.8~91.5%, maintaining the inherent high transparency of the polyvinyl butyral composite film, proving that the directional regulation of the chain segment distribution of the present invention does not impair its optical performance.

[0125] Regarding thickness uniformity: the maximum deviation of thickness uniformity in the embodiments of the present invention is ≤ ±0.010 mm, which is better than that of Comparative Example 1 (±0.012 mm) and Comparative Example 2 (±0.015 mm), demonstrating the advantages of the precision molding preparation method of the present invention.

[0126] Regarding thermal stability: the embodiments of the present invention showed no abnormalities after thermal aging, while Comparative Examples 1 and 4 showed slight discoloration, indicating that the chain segment distribution design of the present invention has better compatibility with the plasticizer system and better thermal stability.

[0127] As can be seen from the above embodiments, the present invention achieves the following beneficial effects by directionally controlling the segment distribution of triol-type hydroxyl groups in polyvinyl butyral resin, combined with a precise preparation method: Significantly improved mechanical properties: The directional distribution of triol-type hydroxyl groups forms an intramolecular gradient structure of "rigid mid-section + flexible end" or "flexible mid-section + rigid end", which makes the penetration resistance of the polyvinyl butyral composite film reach 7.5~8.2m, which is better than the comparative example.

[0128] Excellent processing and overall performance: The molecular chain segments are evenly distributed, and it has good compatibility with plasticizers. Polyvinyl butyral composite film has no defects such as warping or bubbles during the molding process, has high thickness uniformity (deviation ≤ ±0.010mm), and strong thermal stability.

[0129] Highly feasible for industrial implementation: The preparation method can be fully utilized with existing polyvinyl butyral intermediate film production equipment, without the need for large-scale equipment modification, and the production cost is controllable, making it easy to scale up and promote.

[0130] 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 polyvinyl butyral composite film, characterized in that, Including alternately stacked X-type resin films and Y-type resin films; The X-type resin film comprises a first polyvinyl butyral resin and a first plasticizer; The triol hydroxyl group distribution of the first polyvinyl butyral resin is as follows: isotropic triol hydroxyl groups are distributed in the middle segment of the molecular chain, accounting for 60-70% of the triol hydroxyl groups; isotropic triol hydroxyl groups are distributed at both ends of the molecular chain, accounting for 20-30% of the triol hydroxyl groups; and atactic triol hydroxyl groups account for 10-15% of the triol hydroxyl groups. The Y-type resin film comprises a second polyvinyl butyral resin and a second plasticizer; The triol hydroxyl group distribution of the second polyvinyl butyral resin is as follows: isotropic triol hydroxyl groups are distributed in the middle segment of the molecular chain, accounting for 50-60% of the triol hydroxyl groups; syndiotropic triol hydroxyl groups are distributed at both ends of the molecular chain, accounting for 30-40% of the triol hydroxyl groups; and atactic triol hydroxyl groups account for 10-15% of the triol hydroxyl groups.

2. The polyvinyl butyral composite film according to claim 1, characterized in that, The butyl content of the first polyvinyl butyral resin is 58-62 mol%; The total proportion of triol-type hydroxyl groups in the hydroxyl groups of the first polyvinyl butyral resin is 8-12%; The second polyvinyl butyral resin has a butyl content of 62-68 mol%; The total proportion of triol-type hydroxyl groups in the second polyvinyl butyral resin is 25-35%.

3. The polyvinyl butyral composite film according to claim 1, characterized in that, The thickness of a single layer of the X-type resin film is 0.08~0.3mm; The thickness of a single layer of the Y-type resin film is 0.08~0.3mm; The total thickness of the polyvinyl butyral composite film is 0.4~1.4 mm.

4. The polyvinyl butyral composite film according to claim 1, characterized in that, The X-type resin film also includes an antioxidant; The mass ratio of the first polyvinyl butyral resin to the antioxidant is 100:0.05~0.15; The X-type resin film also includes an ultraviolet absorber; The mass ratio of the first polyvinyl butyral resin to the ultraviolet absorber is 100:0.05~0.

15.

5. The polyvinyl butyral composite film according to claim 1, characterized in that, The Y-type resin film also includes an antioxidant; The Y-type resin film also includes an ultraviolet absorber.

6. The method for preparing the polyvinyl butyral composite film according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Polyvinyl alcohol, a first composite acid catalyst, water and a portion of n-butyraldehyde are mixed and subjected to a first acetalization reaction, a second acetalization reaction with the remaining n-butyraldehyde and aging to obtain a first polyvinyl alcohol butyraldehyde resin; the first polyvinyl alcohol butyraldehyde resin and a first plasticizer are mixed and subjected to melt extrusion and casting to obtain an X-type resin film. (2) Polyvinyl alcohol, second composite acid catalyst, water and part of n-butyraldehyde are mixed and subjected to a third acetalization reaction, a fourth acetalization reaction with the remaining n-butyraldehyde and aging to obtain a second polyvinyl alcohol butyraldehyde resin; the second polyvinyl alcohol butyraldehyde resin and the second plasticizer are mixed and subjected to melt extrusion and casting to obtain a Y-type resin film. (3) The X-type resin film and the Y-type resin film are compositely extruded to obtain the polyvinyl butyral composite film; There is no requirement for the time order of steps (1) and (2).

7. The preparation method according to claim 6, characterized in that, In step (1), the first composite acid catalyst includes hydrochloric acid and phosphoric acid; The mass ratio of hydrochloric acid to phosphoric acid is 2.5~3.5:1; The proportion of n-butyraldehyde in the total n-butyraldehyde is 35-45%; The remaining n-butyraldehyde accounts for 55-65% of all n-butyraldehyde; The temperature of the first acetalization reaction is 25~30℃, and the reaction time is 2~3 hours; The second acetalization reaction is carried out at a temperature of 40-45°C for 3-4 hours. The ripening temperature is 70~75℃, and the holding time is 2~3 hours.

8. The preparation method according to claim 6, characterized in that, In step (2), the second composite acid catalyst includes hydrochloric acid and sulfuric acid; The mass ratio of hydrochloric acid to sulfuric acid is 3.5~4.5:1; The proportion of n-butyraldehyde in the total n-butyraldehyde is 55-65%; The remaining n-butyraldehyde accounts for 35-45% of all n-butyraldehyde; The temperature of the third acetalization reaction is 35~40℃, and the reaction time is 3~4 hours; The temperature for the fourth acetalization reaction is 50~55℃, and the holding time is 4~5 hours; The ripening temperature is 80~85℃, and the holding time is 3~4 hours.

9. The application of the polyvinyl butyral composite film according to any one of claims 1 to 5 or the polyvinyl butyral composite film obtained by the preparation method according to any one of claims 6 to 8 as an interlayer film in laminated glass.

10. A laminated glass, characterized in that, Includes an intermediate film and glass plates bonded to both sides of the intermediate film; The intermediate membrane is the polyvinyl butyral composite membrane according to any one of claims 1 to 5 or the polyvinyl butyral composite membrane obtained by the preparation method according to any one of claims 6 to 8.

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