Multi-layer structure high-impact TPU glass interlayer film and preparation method thereof

Abstract

The invention belongs to the technical field of TPU glass interlayer films, and discloses a high-impact TPU glass interlayer film with a multi-layer structure and a preparation method of the high-impact TPU glass interlayer film. The composite material is of a symmetrical three-layer structure and comprises a core layer and a core layer, wherein the core layer is composed of aliphatic polyether type thermoplastic polyurethane; the two skin layers are composed of aliphatic polycaprolactone type thermoplastic polyurethane, and the hardness of the skin layers is higher than that of the core layer; wherein the thickness ratio of the core layer to the skin layer is (1.50-4): 1, the total light transmittance of the interlayer film is greater than or equal to 91%, and the haze is less than or equal to 1.0%. The multilayer-structure high-impact-resistance TPU glass interlayer film provided by the invention can meet the lamination requirements of interlayers such as glass, PC (Polycarbonate), PMMA (Polymethyl Methacrylate) and the like. And the TPU interlayer film has high tensile resistance and puncture resistance, so that laminated glass, laminated explosion-proof glass and the like are endowed with excellent impact resistance and explosion resistance. Meanwhile, the optical light transmittance and the long-term aging resistance are relatively good.

Description

Technical Field

[0001] This invention belongs to the field of TPU glass interlayer film technology, specifically a multi-layer high-impact TPU glass interlayer film and its preparation method. Background Technology

[0002] High-performance interlayer films for laminated glass are developing towards a combination of ultra-high-definition optical performance, long-term weather resistance, excellent safety, and environmental adaptability. Traditional PVB films have shortcomings in weather resistance (yellowing), tear resistance, and wide-temperature-range mechanical property stability. While single TPU films have advantages in toughness and temperature resistance, they are difficult to balance the following contradictions simultaneously: the contradiction between high light transmittance and impact resistance (improving impact resistance often requires the introduction of phase separation structures or additives, which may impair optical uniformity and increase haze); the contradiction between hydrolysis resistance and UV aging resistance (polyether-based TPU has excellent hydrolysis resistance, but its ether bonds are easily oxidized under UV light, leading to yellowing; polyester-based TPU (such as polycaprolactone-based) has high mechanical strength and relatively good UV resistance, but its ester bonds are easily hydrolyzed); and the contradiction between the cohesive strength of the film layer and the bonding strength of the glass interface (a single formulation cannot simultaneously optimize both bulk and interfacial properties). Summary of the Invention

[0003] The purpose of this invention is to overcome the aforementioned deficiencies in the prior art by providing a multi-layered, high-impact TPU glass interlayer film and its preparation method through the design of material component hardness during the TPU synthesis stage. Through polymer molecular design, aliphatic polyether-type TPU (core layer A) and aliphatic polycaprolactone-type TPU (skin layer B) with specific chemical structures are synthesized separately. These are then compounded through a co-extrusion process to achieve the characteristics of "high elasticity and resistance to hydrolysis in the core layer, and high strength, strong adhesion, and weather resistance in the skin layer." The specific technical solution is as follows:

[0004] A multi-layered, high-impact TPU glass interlayer film has a symmetrical three-layer structure, comprising a core layer made of aliphatic polyether thermoplastic polyurethane; two skin layers made of aliphatic polycaprolactone thermoplastic polyurethane, wherein the skin layers have a higher hardness than the core layer; wherein the thickness ratio of the core layer to the skin layers is 1.50-4:1, and the total light transmittance of the interlayer film is ≥91%, and the haze is ≤1.0%.

[0005] Furthermore, the core layer composition by mass ratio is as follows: 40-80 parts of polytetrahydrofuran ether diol, 20-40 parts of aliphatic diisocyanate, 5-15 parts of diol chain extender, 0.1-0.5 parts of stannous octoate as the main catalyst, and 0.05-0.25 parts of dibutyltin dilaurate.

[0006] Furthermore, the Mn of the polytetrahydrofuran ether diol is 1000-3000; the diol chain extender is one or more of 1,4-butanediol, ethylene glycol, 1,6-hexanediol, and silane chain extenders.

[0007] Furthermore, the R value of the core layer (1) is controlled at 0.95-1.05, and the hard segment content is controlled at 20%-35%.

[0008] Furthermore, the composition of the skin layer (2) is as follows by mass ratio: 30-65 parts of poly(ε-caprolactone diol), 30-45 parts of hexamethylene diisocyanate, 5-15 parts of 1,4-butanediol, 0.5-3 parts of silane coupling agent; 0.1-0.5 parts of UV622 additive, 0.1-0.5 parts of UV329 additive; 0.1-0.5 parts of stannous octoate as the main catalyst, and 0.1-0.5 parts of dibutyltin dilaurate.

[0009] Furthermore, the Mn of the poly(ε-caprolactone diol) is 1500-2000.

[0010] Furthermore, the aliphatic diisocyanate includes hexamethylene diisocyanate and isophorone diisocyanate.

[0011] Furthermore, the silane coupling agent is bis-(γ-hydroxypropyl)dimethylsilane.

[0012] Furthermore, the R value of the cortex (2) is controlled at 1.02-1.10, and the hard segment content is controlled at 30%-45%.

[0013] A method for preparing the multilayer high-impact TPU glass interlayer film includes the following steps:

[0014] Synthetic core and skin TPU granules: Core and skin TPU are synthesized under inert gas protection using either bulk prepolymerization-chain extension or one-step method; after underwater pelletizing and drying, transparent TPU granules are obtained; the core and skin TPU granules are dried at 80-100℃ for 4-6 hours respectively.

[0015] The core layer granules are fed into the main extruder, while the skin layer granules are fed into two auxiliary extruders. The temperature of each extruder is precisely controlled between 150-190℃. The melt is pumped and metered, and then compounded within a three-layer co-extrusion die. The co-extruded three-layer melt is then cast through a T-die onto a mirror cooling roller with a surface temperature controlled at 10-30℃ for rapid cooling and shaping. The film surface undergoes online corona treatment to further activate the surface, and then it is wound up with a release liner.

[0016] The multi-layered, high-impact TPU glass interlayer film of this invention can meet the lamination requirements of glass, PC, and PMMA. The high tensile and puncture resistance of the TPU interlayer film itself endows laminated glass and laminated explosion-proof glass with excellent impact and shatter resistance. It also possesses good optical transmittance and long-term aging resistance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the multi-layer high-impact TPU glass interlayer film of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the embodiments.

[0019] The multilayer high-impact TPU glass interlayer film of the present invention has a symmetrical three-layer structure. It includes: a core layer 1 (layer A): composed of aliphatic polyether thermoplastic polyurethane with a Shore A hardness of 75-80A; and two skin layers 2 (layer B): composed of aliphatic polycaprolactone thermoplastic polyurethane with a Shore A hardness of 80-88A, and a hardness higher than that of the core layer 1; wherein the thickness ratio of the core layer 1 to the skin layer 2 is 1.50-4:1, and the total light transmittance of the interlayer film is ≥91%, and the haze is ≤1.0%.

[0020] Specifically, the core layer 1 (layer A) is made of aliphatic polyether TPU, which gives the core layer 1 extremely high resilience, low temperature toughness and excellent hydrolysis resistance, so as to absorb and disperse impact energy.

[0021] Specifically, the core layer 1 (layer A) uses polytetrahydrofuran ether diol with a number average molecular weight (Mn) of 1000-3000. Its long-chain ether structure has good flexibility and a low glass transition temperature, giving TPU excellent low-temperature flexibility and fatigue resistance, while also providing good long-term resistance to water vapor aging.

[0022] Aliphatic diisocyanates are used, including but not limited to hexamethylene diisocyanate and isophorone diisocyanate. The urethane bonds formed by the reaction with the polyether soft segments are colorless and transparent, and resistant to ultraviolet light, thus meeting the long-term aging and yellowing resistance issues of TPU.

[0023] Diol chain extenders are used, including but not limited to 1,4-butanediol, ethylene glycol, 1,6-hexanediol, and silane chain extenders. These are used to form regular hard segment microdomains, providing appropriate physical crosslinking points and balancing elasticity and strength.

[0024] Specifically, the NCO / OH molar ratio (R value) is controlled between 0.95 and 1.05, and the hard segment content is controlled between 20% and 35%. This design ensures that the TPU has moderate modulus, high elongation, and low permanent deformation, and a certain proportion of catalyst is added to control the catalytic reaction.

[0025] The core layer 1 is composed of the following components by mass ratio: 40-80 parts of polytetrahydrofuran ether diol, 20-40 parts of aliphatic diisocyanate, 5-15 parts of diol chain extender, 0.1-0.5 parts of stannous octoate as the main catalyst, and 0.05-0.25 parts of dibutyltin dilaurate.

[0026] Specifically, the skin layer 2 (layer B) is made of aliphatic polycaprolactone-type TPU, which gives the skin layer high modulus, high strength, excellent UV aging resistance, and extremely strong chemical adhesion to the glass substrate.

[0027] Specifically, poly(ε-caprolactone diol) with a number-average molecular weight (Mn) of 1500-2000 is used as the soft segment. Its ester bonds are regular, it has a strong tendency to crystallize, and it has good compatibility with the hard segment, which can form a stronger phase separation structure, thereby giving TPU higher tensile strength, modulus and wear resistance. Polycaprolactone has better UV aging resistance than polyether.

[0028] Aliphatic diisocyanates, including but not limited to hexamethylene diisocyanate and isophorone diisocyanate, are also used to ensure chemical compatibility with the core material and to form interpenetration or eutectic at the co-extrusion interface, achieving a seamless and strong bond between layers.

[0029] Chain extenders are introduced from diols containing silane coupling groups, such as bis-(γ-hydroxypropyl)dimethylsilane. These chain extenders can be chemically integrated into the TPU molecular chain. During laminated glass forming (autoclave treatment), the silane groups can undergo hydrolytic condensation with the silanol groups on the glass surface, forming strong Si-O-Si chemical bonds, which greatly improves adhesive strength and water resistance.

[0030] The NCO / OH molar ratio (R value) is 1.02-1.10, slightly higher than that of the core layer, and the hard segment content is controlled at 30%-45%. This gives the skin layer higher hardness, strength, and heat resistance.

[0031] The skin layer 2 is composed of the following components by mass ratio: 30-65 parts of poly(ε-caprolactone diol), 30-45 parts of hexamethylene diisocyanate, 5-15 parts of 1,4-butanediol, 0.5-3 parts of silane coupling agent; 0.1-0.5 parts of UV622 additive and 0.1-0.5 parts of UV329 additive; 0.1-0.5 parts of stannous octoate as the main catalyst and 0.1-0.5 parts of dibutyltin dilaurate.

[0032] The method for preparing the multilayer high-impact TPU glass interlayer film of the present invention includes the following steps:

[0033] Synthesize A-layer and B-layer TPU granules separately: Core layer (A-layer) and skin layer (B-layer) TPU are synthesized under inert gas protection using either bulk prepolymerization-chain extension or a one-step method. After underwater pelletizing and drying, transparent TPU granules are obtained. The A-layer and B-layer TPU granules are then dried at 80-100℃ for 4-6 hours respectively. An additional 0.1%-0.2% of UV absorber (such as benzotriazole) and light stabilizer (such as HALS) can be dry-mixed into the skin layer granules.

[0034] The casting unit is equipped with three single-screw extruders and a three-layer co-extrusion die. Layer A granules are fed into the main extruder (corresponding to the core layer), and layer B granules are fed into two auxiliary extruders (corresponding to the upper and lower skin layers). The temperature of each extruder is precisely controlled between 150-190℃ (layer A slightly lower, layer B slightly higher). The melt is pumped and metered, and then compounded within the three-layer co-extrusion die. The co-extruded three-layer melt is cast through a T-die onto a mirror-finish cooling roller with a surface temperature controlled at 10-30℃ for rapid cooling and shaping. The film surface undergoes online corona treatment to further activate the surface, and then it is wound up with a release liner.

[0035] The skin structure, through the cooling roller texture structure, is bonded and hot-pressed to form regular patterns, which facilitates the subsequent lamination and degassing of multi-layer sandwich films and improves lamination abnormalities.

[0036] Example 1

[0037] The core layer (A layer) structure polymerization formulation is as follows: 68 parts polytetrahydrofuran ether diol (Mn=2000); 35 parts hexamethylene diisocyanate; 8 parts 1,4-butanediol; 0.2 parts stannous octoate; and 0.05 parts dibutyltin dilaurate. Granulation is performed by extrusion polymerization followed by drying.

[0038] The skin (B layer) structure polymerization formulation is as follows: 54 parts poly(ε-caprolactone diol) (Mn=1500); 40 parts hexamethylene diisocyanate; 7 parts 1,4-butanediol; 3 parts bis-(γ-hydroxypropyl)dimethylsilane; 0.25 parts stannous octoate; 0.1 parts dibutyltin dilaurate; 0.2 parts UV622 additive; 0.2 parts UV329 additive. After extrusion polymerization and granulation, the mixture is dried.

[0039] The dried material was produced using three single-screw extruders and a casting unit with a three-layer co-extrusion die. Layer A granules were fed into the main extruder (corresponding to the core layer), and layer B granules were fed into two auxiliary extruders (corresponding to the upper and lower skin layers). Extrusion was controlled at a thickness ratio of 1:3:1, and the sandwich film performance was tested.

[0040] Example 2

[0041] The core layer 1 (layer A) structure polymerization formulation is as follows: 62 parts polytetrahydrofuran ether diol (Mn=1500); 30 parts hexamethylene diisocyanate; 8 parts ethylene glycol; 0.4 parts stannous octoate; and 0.1 parts dibutyltin dilaurate. After extrusion polymerization and granulation, the mixture is dried.

[0042] The polymerization formulation for the skin layer 2 (B layer) structure is as follows: 60 parts of poly(ε-caprolactone diol) (Mn=1800); 34 parts of hexamethylene diisocyanate; 8 parts of 1,4-butanediol; 1 part of bis-(γ-hydroxypropyl)dimethylsilane; 0.35 parts of stannous octoate; 0.4 parts of dibutyltin dilaurate; 0.1 parts of UV622 additive; and 0.5 parts of UV329 additive. The mixture is granulated by extrusion polymerization and then dried.

[0043] The dried material was produced using three single-screw extruders and a casting unit with a three-layer co-extrusion die. Layer A granules were fed into the main extruder (corresponding to the core layer), and layer B granules were fed into two auxiliary extruders (corresponding to the upper and lower skin layers). Extrusion was controlled at a thickness ratio of 1:4:1, and the sandwich film performance was tested.

[0044] Table 1 shows a comparison of the performance of each embodiment and commercially available product:

[0045]

[0046] Table 1. Performance comparison of various embodiments and commercially available products.

Claims

1. A multi-layered, high-impact TPU glass interlayer film, comprising a symmetrical three-layer structure, characterized in that: The membrane comprises a core layer (1) made of aliphatic polyether thermoplastic polyurethane; two skin layers (2) made of aliphatic polycaprolactone thermoplastic polyurethane, wherein the skin layer (2) has a higher hardness than the core layer (1); wherein the thickness ratio of the core layer (1) to the skin layer (2) is 1.50-4:1, the total light transmittance of the membrane is ≥91%, and the haze is ≤1.0%.

2. The multi-layer high-impact TPU glass interlayer film as described in claim 1, characterized in that: The core layer (1) consists of the following components in the following mass ratio: 40-80 parts of polytetrahydrofuran ether diol, 20-40 parts of aliphatic diisocyanate, 5-15 parts of diol chain extender, 0.1-0.5 parts of stannous octoate as the main catalyst, and 0.05-0.25 parts of dibutyltin dilaurate.

3. The multi-layer high-impact TPU glass interlayer film as described in claim 2, characterized in that: The Mn of the polytetrahydrofuran ether diol is 1000-3000; the diol chain extender is one or more of 1,4-butanediol, ethylene glycol, 1,6-hexanediol, and silane chain extenders.

4. The multi-layer high-impact TPU glass interlayer film as described in claim 2, characterized in that: The R value of the core layer (1) is controlled between 0.95 and 1.05, and the hard segment content is controlled between 20% and 35%.

5. The multi-layer high-impact TPU glass interlayer film as described in claim 1, characterized in that: The skin layer (2) consists of the following components in the following mass ratio: 30-65 parts of poly(ε-caprolactone diol), 30-45 parts of hexamethylene diisocyanate, 5-15 parts of 1,4-butanediol, 0.5-3 parts of silane coupling agent, 0.1-0.5 parts of UV622 additive, 0.1-0.5 parts of UV329 additive, 0.1-0.5 parts of stannous octoate as the main catalyst, and 0.1-0.5 parts of dibutyltin dilaurate.

6. The multi-layer high-impact TPU glass interlayer film as described in claim 5, characterized in that: The Mn of the poly(ε-caprolactone diol) is 1500-2000.

7. The multi-layer high-impact TPU glass interlayer film as described in claim 2 or 5, characterized in that: The aliphatic diisocyanate includes hexamethylene diisocyanate and isophorone diisocyanate.

8. The multi-layer high-impact TPU glass interlayer film as described in claim 5, characterized in that: The silane coupling agent is bis-(γ-hydroxypropyl)dimethylsilane.

9. The multi-layer high-impact TPU glass interlayer film as described in claim 5, characterized in that: The R value of the cortex (2) is controlled at 1.02-1.10, and the hard segment content is controlled at 30%-45%.

10. A method for preparing a multilayer high-impact TPU glass interlayer film as described in any one of claims 1-9, characterized in that... Includes the following steps: Synthetic core and skin TPU granules: Core and skin TPU are synthesized under inert gas protection using either bulk prepolymerization-chain extension or one-step method; after underwater pelletizing and drying, transparent TPU granules are obtained; the core and skin TPU granules are dried at 80-100℃ for 4-6 hours respectively. The core layer granules are fed into the main extruder, while the skin layer granules are fed into two auxiliary extruders. The temperature of each extruder is precisely controlled between 150-190℃. The melt is pumped and metered, and then compounded within a three-layer co-extrusion die. The co-extruded three-layer melt is then cast through a T-die onto a mirror cooling roller with a surface temperature controlled at 10-30℃ for rapid cooling and shaping. The film surface undergoes online corona treatment to further activate the surface, and then it is wound up with a release liner.

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