WO2025192376A1 - Laminated glass - Google Patents

Abstract

The present disclosure provides a laminated glass having a different-thickness configuration and satisfactory in terms of sound-insulating properties, vibration-damping properties, and rigidity.　This laminated glass (1) has a structure in which a first glass plate (11) that is relatively thick is laminated to a second glass plate (12) that is relatively thin, with an interlayer film (20) interposed therebetween. When the ratio of the thickness of the first glass plate to the thickness of the second glass plate is defined as a plate thickness ratio (T_R) and when the secondary-mode resonant frequency of the laminated glass and the secondary-mode dissipation factor thereof, both determined by a mechanical impedance method according to ISO/PAS 16940:2008, are respectively expressed by f₂ and η₂, then f₂/T_R is 350-1,500 Hz, η₂ is 0.10 or greater, and 1.0<T_R<3.0. The interlayer film is a multilayer film composed of a pair of surface layers (21, 22) each having a Tg of 15°C or higher and an interlayer (23) having a Tg lower than 15°C, wherein the pair of surface layers have a storage modulus (E'), as determined under the conditions of 23°C and a frequency of 1 Hz, of 100 MPa or greater.

Description

Laminated glass

This disclosure relates to laminated glass.

Laminated glass, which consists of a pair of glass sheets bonded together via an interlayer film, is highly resistant to breakage, and even if it does break, glass shards do not scatter, providing excellent security and safety. It is therefore used in a variety of applications, including vehicles and buildings. Thin, lightweight window glass is preferred for applications such as electric vehicles, which require both thinness and lightness and rigidity. In recent years, frameless structures have been developed for vehicle door window glass, etc., from the perspective of improving design. In particular, frameless structures require greater rigidity because the window glass is not supported by a frame.

Traditionally, laminated glass has typically been constructed with two glass sheets designed to be the same thickness. In general, the rigidity of a given glass sheet tends to be proportional to approximately the cube of the thickness of that glass sheet. When two glass sheets are designed to be unequal in thickness while maintaining the same total thickness, the rigidity of the thicker glass sheet is proportional to approximately the cube of its thickness, effectively increasing the rigidity of the entire laminated glass. Therefore, a unequal thickness construction, in which the two glass sheets are designed to be unequal in thickness, can achieve both thinness, light weight, and rigidity.

For example, Patent Document 1 discloses laminated glass suitable for use as automotive window glass (particularly for frameless window glass), which has a structure in which two panes of glass of different thicknesses are bonded together via an interlayer film, with the thick pane V1 having a thickness E1 of 1.4 to 3.9 mm, the thin pane V2 having a thickness E2 of 1.1 to 2.6 mm, the interlayer film having a thickness E3 of 0.3 to 1.2 mm, a total glass thickness EV of 2.5 to 5.7 mm, and a thickness ratio E2/E1 of the two panes of glass of 0.34 to 0.9 (claims 1 and 11).

International Publication No. 2021/180828

Compared to gasoline-powered vehicles, vehicles such as electric vehicles have quieter engine noise and more noticeable noises such as external environmental noise, wind noise, and vibration noise, so they require higher levels of sound insulation and vibration damping.
Generally, the greater the mass per unit area of a window glass, the greater the sound transmission loss (STL) tends to be.
When the frequency of the vibration of window glass matches the frequency of the incident sound wave, the vibration of the window glass increases due to resonance, and the transmitted sound tends to increase. This phenomenon, called coincidence, can occur especially when the incident sound is in the high frequency range, such as wind noise.

Thin and lightweight window glass cannot have a large mass per unit area. In this case, the use of a sound-insulating interlayer film can increase the sound transmission loss (STL) of the laminated glass and provide sound insulation. A sound-insulating interlayer film can also convert vibration energy into thermal energy to attenuate the vibration, providing vibration-damping properties.
However, in a configuration in which the thicknesses of the two glass plates are designed to be unequal, the sound insulation and/or vibration damping properties tend to be lower than in a configuration in which the thicknesses are the same.
Laminated glass with a unequal thickness structure is thought to be prone to vibration due to poor weight balance caused by the difference in thickness between the two glass sheets. Furthermore, the thinner glass sheet reduces the restraining force of the interlayer, which is thought to prevent the interlayer from effectively damping vibrations. For these reasons, a unequal thickness structure tends to have lower vibration-damping properties than a uniform thickness structure. Therefore, there is a risk of noise being generated from the glass due to vibrations of the glass caused by pressure fluctuations due to the shape of the vehicle body, which is equipped with various components such as door mirrors, and vibrations transmitted from the vehicle body. In particular, in frameless structures, the window glass is not supported by a frame, so vibration-damping properties are likely to be reduced.

Patent Document 1 discloses the use of sound-insulating polymers such as PVB as the material for the interlayer film, and provides sound transmission loss (STL) data as evaluation data for sound insulation (Figure 4). However, this document does not describe the evaluation of vibration-damping properties or means for improving them.

This disclosure has been made in light of the above circumstances, and aims to provide laminated glass that has a unequal thickness structure in which the two glass sheets are not the same thickness, and that has good sound insulation, vibration damping, and rigidity.

The present disclosure provides the following laminated glass:
[1] A laminated glass in which a relatively thick first glass plate and a relatively thin second glass plate are bonded together via an interlayer film,
where the ratio of the thickness of the first glass sheet to the thickness of the second glass sheet is defined as the sheet thickness ratio (T _R ), and the second-order mode resonance frequency and second-order mode loss factor of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 are f _{2 and} η ₂ , respectively, the ratio of the second-order mode resonance frequency of the laminated glass to the sheet thickness ratio (f ₂ /T _R ) is 350 to 1500 Hz, η ₂ is 0.10 or more, and 1.0<T _R <3.0;
The interlayer film is a laminated film including a pair of surface layers each having a glass transition temperature (Tg) of 15°C or higher and an intermediate layer sandwiched between the pair of surface layers and having a glass transition temperature (Tg) of lower than 15°C, and the pair of surface layers have a storage modulus (E') of 100 MPa or higher as measured at 23°C and a frequency of 1 Hz.

[2] When the resonance frequency of the first mode of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 is _f1 ,
The laminated glass according to [1], wherein the ratio (f ₁ /T _R ) of the resonance frequency of the first mode of the laminated glass to the plate thickness ratio is 60 to 300 Hz.
[3] When the resonance frequency of the third mode of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 is _f3 ,
The laminated glass according to [1] or [2], wherein the ratio (f ₃ /T _R ) of the resonance frequency of the third mode of the laminated glass to the plate thickness ratio is 900 to 3500 Hz.

[4] When the resonance frequency of the fourth mode of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 is _f4 ,
The laminated glass according to any one of [1] to [3], wherein the ratio (f ₄ /T _R ) of the fourth-order mode resonance frequency of the laminated glass to the plate thickness ratio is 1650 to 6500 Hz.
[5] When the resonance frequency of the fifth mode of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 is _f5 ,
The laminated glass according to any one of [1] to [4], wherein the ratio (f ₅ /T _R ) of the fifth mode resonance frequency of the laminated glass to the plate thickness ratio is 2600 to 9000 Hz.

[6] The laminated glass according to any one of [1] to [5], wherein, when the loss factor of the first mode, the loss factor of the third mode, the loss factor of the fourth mode, and the loss factor of the _fifth mode of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 are _η1 , _η3 , _η4 , and _η5 , respectively, one or more of _η1 , _η3 , _η4 , and η5 is 0.10 or more.
[7] The laminated glass according to any one of [1] to [6], wherein the second glass plate has a thickness of 0.3 to 3.0 mm.
[8] The laminated glass according to any one of [1] to [7], wherein the total thickness of the first glass plate and the second glass plate is 4.0 to 6.0 mm.
[9] The laminated glass according to any one of [1] to [8], wherein 1.30≦T _R ≦2.50.

[10] The laminated glass according to any one of [1] to [9], wherein the interlayer film contains one or more thermoplastic resins selected from the group consisting of polyvinyl acetal, ionomer, ethylene-vinyl acetate copolymer, cycloolefin polymer, polymethyl methacrylate, and polyurethane.
[11] The laminated glass according to any one of [1] to [10], wherein the pair of surface layers have a glass transition temperature (Tg) of 30°C or higher.
[12] The laminated glass according to any one of [1] to [11], wherein the pair of surface layers have a glass transition temperature (Tg) of 35°C or higher.
[13] The laminated glass according to any one of [1] to [12], wherein the pair of surface layers have a storage modulus (E') of 150 MPa or more, measured at 23°C and a frequency of 1 Hz.

This disclosure makes it possible to provide laminated glass with a different thickness configuration in which the two glass sheets are not the same thickness, and which has excellent sound insulation, vibration damping, and rigidity.

1 is a schematic cross-sectional view of a laminated glass according to an embodiment of the present invention. 1 is a graph showing data on the temperature dependence of the loss tangent (tan δ) of the surface layer of each PVB film used in the [Examples] section. 1 is a graph showing data on the temperature dependence of the storage modulus (E′) of the surface layer of each PVB film used in the [Examples] section. 1 is a graph showing the relationship between f ₂ / _TR and inertance for the laminated glasses obtained in the examples in the section [Examples]. 1 is a graph showing the relationship between f ₁ / _TR and inertance for the laminated glasses obtained in the examples in the section [Examples]. 1 is a graph showing the relationship between f ₃ / _TR and inertance for the laminated glasses obtained in the examples in the section [Examples]. 1 is a graph showing the relationship between f ₄ / _TR and inertance for the laminated glasses obtained in the examples in the section [Examples]. 1 is a graph showing the relationship between f ₅ / _TR and inertance for the laminated glasses obtained in the examples in the section [Examples]. FIG. 1 is a schematic plan view for explaining a hammering test method.

Generally, thin film structures are referred to as "films" or "sheets" depending on their thickness. In this specification, no clear distinction is made between these terms. Therefore, in this specification, "films" may include "sheets."
In this specification, unless otherwise specified, the "surface of a glass plate" refers to the main surface having the largest area, excluding the end faces (also called side faces) of the glass plate.
In this specification, unless otherwise specified, the terms "up and down,""left and right,""vertical and horizontal," and "inside and outside" refer to the terms when the laminated glass is fitted into a vehicle, building, etc. (actual use state) and viewed from the inside (inside the vehicle or inside the room, etc.).
In this specification, unless otherwise specified, the term "to" indicating a range of values is used to mean that the range includes the values before and after it as the lower and upper limits.
Hereinafter, an embodiment of the present invention will be described.

[Laminated glass]
The present disclosure relates to a laminated glass in which a relatively thick first glass sheet and a relatively thin second glass sheet are bonded together via an interlayer film.
The use of the laminated glass of the present disclosure is not particularly limited, and it is suitable as window glass for vehicles, buildings, etc., and is particularly suitable as window glass for vehicles such as electric vehicles.
Of the first glass sheet and the second glass sheet, one glass sheet may be an outer (e.g., vehicle exterior) glass sheet (also referred to as an outer glass sheet), and the other glass sheet may be an inner (e.g., vehicle interior) glass sheet (also referred to as an inner glass sheet). Preferably, the relatively thick first glass sheet is the outer glass sheet, and the relatively thin second glass sheet is the inner glass sheet.
The types of the first glass plate and the second glass plate are not particularly limited, and examples thereof include soda lime glass, borosilicate glass, aluminosilicate glass, lithium silicate glass, quartz glass, sapphire glass, and alkali-free glass.
The first glass sheet and/or the second glass sheet may be tempered glass, in which case the surface stress is, for example, 10 to 9100 MPa.

Laminated glass for vehicle windows may have a curved shape that is convex on the outside of the vehicle when installed in the vehicle. The laminated glass may have a curved shape that is convex on the outside of the vehicle. The laminated glass may have a single curved shape that is curved in only one direction, either left-right or up-down, or a compound curved shape that is curved in both left-right and up-down directions. The radius of curvature of the laminated glass may be 2000 to 11000 mm. The radii of curvature of the laminated glass in the left-right and up-down directions may or may not be the same. Gravity forming, press forming, roller forming, etc. are used to bend and form laminated glass.

The first glass plate and/or the second glass plate may have a light-shielding layer on the peripheral portion of at least one surface, as necessary. In this specification, the outer periphery of the glass plate is referred to as the "periphery," and the region having a width inscribed in the "periphery" (the peripheral edge and its neighboring region) is referred to as the "periphery portion." The peripheral portion may be, for example, a region within 30 mm from the outer periphery.
The light-shielding layer can be formed by a known method, for example, by applying a ceramic paste containing a black pigment and glass frit to a predetermined region on the surface of the glass plate and firing the paste. The thickness of the light-shielding layer is not particularly limited and is, for example, 5 to 20 μm.
Known glass frits can be used for the conductor and the light-shielding layer, and those containing metal elements such as Na, Al, Si, P, Zn, Ba, and Bi can be used.

The laminated glass may have, in at least a partial region of at least one surface, a functional film having functions such as water repellency, low reflectivity, low emissivity, ultraviolet shielding, infrared shielding, visible light absorption, light scattering, dimming, decoration, and coloring.
The laminated glass may have, in at least a partial region inside thereof, a functional film having functions such as low reflectivity, low emissivity, ultraviolet shielding, infrared shielding, visible light absorption, light scattering, dimming, decoration, and coloring.
At least a portion of the interlayer film of the laminated glass may have functions such as ultraviolet shielding, infrared shielding, visible light absorption, light scattering, dimming, decoration, and coloring.
The laminated glass may have an electrical functional part such as an electric heating wire, an electric heating layer, a power generating layer, an antenna, a light control layer, or a light emitting element on the surface and/or inside.

The structure of a laminated glass according to one embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of the laminated glass of this embodiment.
The laminated glass 1 of this embodiment is formed by bonding together a relatively thick first glass plate 11 (preferably an outer glass plate) and a relatively thin second glass plate 12 (preferably an inner glass plate) with an interlayer film 20 interposed therebetween.
The intermediate film 20 is preferably an intermediate film having sound insulation properties.
Generally, the greater the mass per unit area of window glass, the greater the sound transmission loss (STL). However, thin and lightweight window glass is generally preferred for use in electric vehicles and the like. Thin and lightweight window glass cannot have a large mass per unit area. In this case, by using an interlayer film with sound insulation properties, the sound transmission loss (STL) of the laminated glass can be increased and sound insulation can be achieved. An interlayer film with sound insulation properties can also convert vibration energy into thermal energy to attenuate vibration, and can therefore have vibration-damping properties.

Generally, the rigidity of a given glass sheet tends to be proportional to approximately the cube of the thickness of that glass sheet. When two glass sheets are designed to have unequal thicknesses while maintaining the same total thickness, the rigidity of the thicker glass sheet is proportional to approximately the cube of its thickness, effectively increasing the rigidity of the entire laminated glass. Therefore, the different thickness configuration of the present disclosure, in which the two glass sheets are designed to have unequal thicknesses, can achieve both thinness and light weight and rigidity.

As explained in the section [Problem to be Solved by the Invention], in general, in a unequal thickness configuration in which the thicknesses of two glass plates are designed to be unequal, sound insulation and/or vibration damping properties tend to be reduced compared to a same-thickness configuration.
It is believed that laminated glass with a unequal thickness structure has poor weight balance and is prone to vibration due to the difference in thickness between the two glass sheets. It is also believed that the thinner glass sheet reduces the binding force of the interlayer film, preventing the interlayer film from effectively damping vibrations. For these reasons, a unequal thickness structure is more likely to have poor vibration-damping properties than a uniform thickness structure, particularly with respect to high-frequency sounds such as wind noise, which are prone to coincidence phenomena. In particular, in a frameless structure, the window glass is not supported by a frame, so vibration-damping properties are more likely to be poor.

In this specification, when the thickness of the relatively thick first glass plate is T ₁ [mm] and the thickness of the relatively thin second glass plate is T ₂ [mm], the ratio of the thickness of the first glass plate to the thickness of the second glass plate (T ₁ /T ₂ ) is defined as the "plate thickness ratio (T _R )."

In this specification, the resonance frequencies of the first, second, third, fourth, and fifth modes of the laminated glass measured by the mechanical impedance method in accordance with ISO/PAS 16940:2008 are designated as _f1 , _f2 , _f3 , _f4 , and _f5 , respectively.
In this specification, the first-order mode loss factor, second-order mode loss factor, third-order mode loss factor, fourth-order mode loss factor and fifth-order mode loss factor of laminated glass measured by the mechanical impedance method in accordance with ISO/PAS 16940:2008 are defined as _η1 , _η2 , _η3 , η4 and _{η5 ,} respectively.
In this specification, unless otherwise specified, in the mechanical impedance method conforming to ISO/PAS 16940:2008, a central excitation method is adopted as a sample excitation method in which the central portion of the sample is supported and both ends of the sample are used as free ends to vibrate the central portion (supported portion), and the loss factor (η) is obtained from the obtained frequency response function by the half-width method.

The present inventors have conducted extensive research and have found the following.
It is believed that if the thickness ratio ( _TR ) of the two glass sheets of laminated glass is too large, the weight balance will be poor and the glass will be prone to vibration. Also, if the thickness ratio ( _TR ) of the two glass sheets is too large, the binding force of the thinner glass sheet on the interlayer will be reduced, and the interlayer will not be able to effectively damp vibrations.
It is believed that the coincidence phenomenon can occur at one or more of the resonance frequencies of the first to fifth modes, and in particular at one or more resonance frequencies including the resonance frequency of the second mode.

The vibration damping property can be measured by a hammering test using inertance as an index.
The present inventors have found that there is a correlation between the ratio (f _N /T _R ) [Hz] of the resonance frequency (f _N ) of each vibration mode of the laminated glass to the plate thickness ratio (T _R ) and the inertance.
Specifically, when the ratio (f _N /T _R ) [Hz] of the resonance frequency (f _N ) of each vibration mode of the laminated glass to the plate thickness ratio (T _R ) is taken as the x-axis parameter and the inertance [dB] is taken as the y-axis parameter, it was found that f _N /T _R and inertance are in a proportional relationship or a relationship close to that expressed by y = -ax (where x is f _N /T _R , y is inertance, and a is a positive constant).
Here, N represents the order of the vibration mode and is an integer between 1 and 5. For example, _f2 is the resonance frequency of the second mode.

For the laminated glasses obtained in each example in the section [Examples] below, the relationships between f ₂ /T _R and inertance, the relationship between f ₁ /T _R and inertance, the relationship between f ₃ /T _R and inertance, the relationship between f ₄ /T _R and inertance, and the relationship between f ₅ /T _R and inertance are shown in Figures 4 to 8.

In the laminated glass of the present disclosure, f ₂ /T _R is 350 to 1500 Hz. As shown in Figure 4, if f ₂ /T _R is within this range, the inertance can be reduced to 4.0 dB or less.
The lower limit is more preferably 360 Hz, even more preferably 370 Hz, even more preferably 400 Hz, particularly preferably 450 Hz, and most preferably 500 Hz. If _{f 2} /T _R is 400 to 1500 Hz, the inertance can be reduced to 3.0 dB or less.
The upper limit is preferably 1200 Hz, more preferably 1000 Hz, particularly preferably 900 Hz, and most preferably 800 Hz.

In the laminated glass of the present disclosure, there are no particular limitations on f ₁ /T _R , but it is preferably 60 to 300 Hz. As shown in Figure 5, if f ₁ /T _R is within this range, the inertance can be reduced to 5.0 dB or less.
The lower limit is more preferably 70 Hz, even more preferably 80 Hz, particularly preferably 90 Hz, and most preferably 100 Hz. If _{f 1} /T _R is 70 to 300 Hz, the inertance can be reduced to 4.0 dB or less.
The upper limit is more preferably 250 Hz, even more preferably 200 Hz, particularly preferably 180 Hz, and most preferably 150 Hz.

In the laminated glass of the present disclosure, f ₃ /T _R is not particularly limited, but is preferably 900 to 3500 Hz. As shown in Fig. 6, if f ₃ /T _R is within this range, the inertance can be reduced to 5.0 dB or less.
The lower limit is more preferably 1000 Hz, even more preferably 1100 Hz, particularly preferably 1200 Hz, and most preferably 1500 Hz. If _{f 3} / _TR is 1000 to 3500 Hz, the inertance can be reduced to 4.0 dB or less.
The upper limit is more preferably 3200 Hz, even more preferably 3000 Hz, still more preferably 2800 Hz, particularly preferably 2500 Hz, and most preferably 2200 Hz.

In the laminated glass of the present disclosure, f ₄ /T _R is not particularly limited, but is preferably 1650 to 6500 Hz. As shown in Figure 7, if f ₄ /T _R is within this range, the inertance can be reduced to 4.0 dB or less.
The lower limit is more preferably 1900 Hz, particularly preferably 2000 Hz, and most preferably 2500 Hz. If _{f 4} /T _R is 1900 to 6500 Hz, the inertance can be reduced to 3.0 dB or less.
The upper limit is more preferably 6000 Hz, even more preferably 5500 Hz, still more preferably 5000 Hz, particularly preferably 4500 Hz, and most preferably 4000 Hz.

In the laminated glass of the present disclosure, f ₅ /T _R is not particularly limited, but is preferably 2600 to 9000 Hz. As shown in Fig. 8, if f ₅ /T _R is within this range, the inertance can be reduced to 5.0 dB or less.
The lower limit is more preferably 2800 Hz, even more preferably 3000 Hz, still more preferably 3200 Hz, particularly preferably 3500 Hz, and most preferably 4000 Hz. If _{f 5} / _TR is 2800 to 9000 Hz, the inertance can be reduced to 3.0 dB or less.
The upper limit is more preferably 8500 Hz, even more preferably 8000 Hz, even more preferably 7500 Hz, still more preferably 7000 Hz, particularly preferably 6500 Hz, and most preferably 6000 Hz.

In this specification, unless otherwise specified, sound insulation refers to sound transmission loss (STL), and the loss factor (η) can be used as an index.
In the laminated glass of the present disclosure, the loss coefficient (η ₂ ) of the second mode is 0.10 or more, for example, 0.10 to 0.50, because this provides good sound insulation.
In the laminated glass of the present disclosure, the loss coefficient (η ₁ ) of the first mode is not particularly limited, and is preferably 0.10 or more, for example, 0.10 to 0.50, since this provides good sound insulation.
In the laminated glass of the present disclosure, the third-order mode loss coefficient (η ₃ ) is not particularly limited, and is preferably 0.10 or more, for example, 0.10 to 0.50, since this provides good sound insulation.
In the laminated glass of the present disclosure, the fourth-order mode loss coefficient (η ₄ ) is not particularly limited, and is preferably 0.10 or more, for example, 0.10 to 0.50, since this provides good sound insulation.
In the laminated glass of the present disclosure, the fifth-order mode loss coefficient (η ₅ ) is not particularly limited, and is preferably 0.10 or more, for example, 0.10 to 0.50, since this provides good sound insulation.
In the laminated glass of the present disclosure, it is preferred that _η2 is 0.10 or more, and one or more of _η1 , _η3 , _η4 , and _η5 are 0.10 or more. It is preferred that all of _η1 to _η5 are 0.10 or more.
The lower limit of η ₁ to η ₅ is more preferably 0.12, further preferably 0.13, particularly preferably 0.14, and most preferably 0.15. The upper limit can be 0.40.

The greater the plate thickness ratio ( _TR ), the more rigid the laminated glass can be, but the greater the weight balance between the two glass plates, which tends to reduce vibration-damping properties.
In the laminated glass of the present disclosure, from the viewpoint of the balance between rigidity and vibration damping properties, the plate thickness ratio (T _R ) satisfies 1.0<T _R <3.0.
The thickness ratio ( _TR ) preferably satisfies 1.05 ≦ _TR ≦ 2.95. The lower limit is more preferably 1.10, even more preferably 1.15, even more preferably 1.20, even more preferably 1.25, particularly preferably 1.30, and most preferably 1.50. The upper limit is more preferably 2.90, even more preferably 2.80, even more preferably 2.70, particularly preferably 2.60, and most preferably 2.50.

In the laminated glass of the present disclosure, the total thickness (T _T ) of the relatively thick first glass plate and the relatively thin second glass plate (also referred to as total glass thickness) is not particularly limited, and from the viewpoint of a balance between rigidity and thinness and weight reduction, it is preferably 2.0 to 7.0 mm. The lower limit is more preferably 2.5 mm, even more preferably 3.0 mm, particularly preferably 3.5 mm, and most preferably 4.0 mm. The upper limit is more preferably 6.5 mm, even more preferably 6.0 mm, particularly preferably 5.5 mm, and most preferably 5.0 mm. _{T T} is particularly preferably 4.0 to 6.0 mm.

The thickness (T ₁ ) of the relatively thick first glass plate is not particularly limited, and from the viewpoint of the balance between the rigidity of the laminated glass and thin and lightweight design, it is preferably 1.3 to 4.0 mm. The lower limit is more preferably 1.5 mm, even more preferably 1.8 mm, even more preferably 2.0 mm, particularly preferably 2.2 mm, and most preferably 2.5 mm. The upper limit is more preferably 3.8 mm, even more preferably 3.5 mm, particularly preferably 3.2 mm, and most preferably 3.1 mm.
The thickness (T ₂ ) of the relatively thin second glass plate is not particularly limited, and from the viewpoints of the rigidity, thinness, and lightness of the laminated glass, as well as the handleability of the second glass plate, it is preferably 0.3 to 3.0 mm. The lower limit is more preferably 0.5 mm, even more preferably 0.8 mm, particularly preferably 1.0 mm, and most preferably 1.2 mm. The upper limit is more preferably 2.8 mm, even more preferably 2.5 mm, even more preferably 2.2 mm, particularly preferably 2.0 mm, and most preferably 1.7 mm.

It is preferable that the sheet thickness ratio ( _TR ), the total thickness of the first glass sheet and the second glass sheet (total glass thickness) ( _TT ), the thickness of the first glass sheet ( _T1 ), and the thickness of the second glass sheet ( _T2 ) are within the above ranges, because a good balance of rigidity, thinness, lightness, and vibration damping properties can be achieved for the laminated glass.

In the laminated glass of the present disclosure, the interlayer film 20 contains one or more thermoplastic resins, and preferably contains one or more thermoplastic resins selected from the group consisting of polyvinyl acetal, ionomer, ethylene vinyl acetate copolymer (EVA), cycloolefin polymer (COP), polymethyl methacrylate (PMMA), and polyurethane (PU).
The material of the intermediate film 20 is preferably a resin film containing the thermoplastic resin exemplified above.
The interlayer film 20 may contain one or more known plasticizers as needed to improve the film formability of the resin film that is the material of the interlayer film.
The interlayer film 20 may contain one or more additives other than those described above, as needed. Examples of the additives include an ultraviolet shielding agent, an infrared shielding agent, a visible light absorbing agent, a light scattering agent, a light control material, and a colorant (e.g., a pigment).

There are no particular restrictions on the contents of the thermoplastic resin and plasticizer in the interlayer film 20. The content of the thermoplastic resin (total amount if multiple types are used) in the interlayer film 20 is preferably 80 to 100 mass %, and the content of the plasticizer (total amount if multiple types are used) is preferably 20 to 0 mass %.
The lower limit of the thermoplastic resin content is preferably 85% by mass, more preferably 90% by mass. The upper limit of the plasticizer content is preferably 15% by mass, more preferably 10% by mass. The upper limit of the thermoplastic resin content is preferably 99% by mass, more preferably 98% by mass. The lower limit of the plasticizer content is preferably 1% by mass, more preferably 2% by mass.
For example, when the thermoplastic resin in the intermediate film 20 is an ionomer, an ethylene vinyl acetate copolymer (EVA), a cycloolefin polymer (COP), a polymethyl methacrylate (PMMA), a polyurethane (PU), or the like, the plasticizer content may be 0% by mass.

The intermediate film 20 may have a single layer structure or a laminated structure.
As shown in FIG. 1 , the sound-insulating interlayer film 20 is preferably a laminated film including a pair of surface layers (also referred to as skin layers) 21, 22 each having a relatively high glass transition temperature (Tg), and an intermediate layer (also referred to as core layer) 23 sandwiched between the pair of surface layers 21, 22 and having a relatively low glass transition temperature (Tg).
The pair of surface layers 21, 22 have a relatively high glass transition temperature (Tg), preferably 15° C. or higher, for example, 15 to 50° C. The lower limit is more preferably 20° C., even more preferably 25° C., even more preferably 27° C., particularly preferably 30° C., even more preferably 32° C., even more preferably 35° C., particularly preferably 37° C., and most preferably 38° C. The upper limit can be 45° C. or 40° C.
The glass transition temperature (Tg) of the intermediate layer 23 is relatively low, preferably less than 15° C., more preferably 14° C. or less, for example, −10 to 14° C. The upper limit is more preferably 13° C., particularly preferably 12° C., and most preferably 10° C.

In this specification, unless otherwise specified, the glass transition temperature (Tg) is the peak temperature of the loss tangent (tan δ) (the temperature at which the loss tangent (tan δ) is maximum) determined by performing dynamic viscoelasticity measurement under conditions of a frequency of 1 Hz and a temperature increase rate of 3°C/min.
The loss tangent (tan δ) is a parameter expressed by the following formula.
[Loss tangent (tan δ)] = [loss modulus] / [storage modulus]

The pair of surface layers 21, 22 have a relatively high glass transition temperature (Tg) and are relatively hard under normal usage conditions. The pair of surface layers 21, 22 have a storage modulus (E') measured at 23°C and a frequency of 1 Hz of 100 MPa or higher, for example, 100 MPa to 500 MPa. The lower limit is more preferably 120 MPa, even more preferably 150 MPa, even more preferably 170 MPa, even more preferably 200 MPa, particularly preferably 250 MPa, and most preferably 300 MPa. The upper limit can be 450 MPa or 400 MPa.
The storage modulus (E') of the surface layers 21, 22 is determined by carrying out dynamic viscoelasticity measurement under conditions of a frequency of 1 Hz and a temperature increase rate of 3°C/min.

The intermediate layer 23 has a relatively low glass transition temperature (Tg) and is relatively soft under normal use conditions. The storage modulus (G') of the intermediate layer 23 measured at 23°C and a frequency of 1 Hz is not particularly limited and is, for example, 0.05 MPa to 1 MPa.
The storage modulus (G') of the intermediate layer 23 is determined by carrying out dynamic viscoelasticity measurement under conditions of a frequency of 1 Hz and a temperature increase rate of 3°C/min.

In the intermediate film 20 having the above-described laminated structure, the relatively soft intermediate layer 23 sandwiched between a pair of relatively hard surface layers 21, 22 is easily deformed (e.g., shear deformation), effectively converting vibration energy into thermal energy and damping the vibration, thereby effectively improving sound insulation and vibration damping.

The thermoplastic resin contained in the intermediate film 20 is preferably polyvinyl acetal or the like. Among polyvinyl acetals, polyvinyl butyral (PVB) or the like is preferable.
Polyvinyl acetal is a resin produced by acetalization of polyvinyl alcohol or a polyvinyl alcohol-based resin such as an ethylene-vinyl alcohol copolymer.
The polyvinyl acetal-containing interlayer film or layer (surface layer and/or intermediate layer) may contain two or more types of polyvinyl acetal that differ in one or more properties selected from the group consisting of viscosity-average degree of polymerization, degree of acetalization, vinyl acetate unit content, vinyl alcohol unit content, ethylene unit content, molecular weight of the aldehyde used for acetalization, and chain length.

The glass transition temperature (Tg) and storage modulus (E′) or (G′) of the layer (surface layer and/or intermediate layer) containing polyvinyl acetal can be adjusted within a preferred range by adjusting the properties of the polyvinyl acetal, such as the viscosity-average degree of polymerization, the degree of acetalization, the vinyl acetate unit content, the vinyl alcohol unit content, the ethylene unit content, the molecular weight and chain length of the aldehyde used for acetalization, and/or the content of the plasticizer.
For example, when polyvinyl butyral (PVB) is used as the thermoplastic resin, the content of the plasticizer in the surface layers 21, 22 is preferably 15 to 30% by mass. The lower limit is more preferably 16% by mass. The upper limit is more preferably 27% by mass, particularly preferably 25% by mass, and most preferably 23% by mass.
When polyvinyl butyral (PVB) is used as the thermoplastic resin, the content of the plasticizer in the intermediate layer 23 is preferably 20 to 45% by mass. The lower limit is more preferably 25% by mass, and particularly preferably 27% by mass. The upper limit is more preferably 42% by mass, particularly preferably 40% by mass, and most preferably 38% by mass.

The thickness (T _M ) of the interlayer film 20 is not particularly limited, and from the viewpoints of adhesion, penetration resistance, and thinness and weight reduction, it is preferably 100 μm to 3 mm. The lower limit is more preferably 150 μm, particularly preferably 200 μm, even more preferably 250 μm, even more preferably 300 μm, even more preferably 350 μm, even more preferably 400 μm, even more preferably 450 μm, and most preferably 500 μm. The upper limit is more preferably 2.5 mm, even more preferably 2 mm, even more preferably 1.5 mm, particularly preferably 1 mm, and most preferably 800 μm.
The thickness of the resin film material for the interlayer 20 is preferably 110 μm to 3 mm. The lower limit is more preferably 160 μm, particularly preferably 210 μm, even more preferably 260 μm, even more preferably 310 μm, even more preferably 360 μm, even more preferably 410 μm, even more preferably 460 μm, and most preferably 510 μm. The upper limit is more preferably 2.5 mm, even more preferably 2 mm, even more preferably 1.5 mm, especially preferably 1 mm, and most preferably 800 μm.
The intermediate film 20 having the above-described laminated structure can be produced by a known method such as co-extrusion molding.

[Method of manufacturing laminated glass]
The laminated glass of the present disclosure can be produced by known methods.
First, if necessary, a relatively thick first glass sheet 11 (preferably an outer glass sheet) and a relatively thin second glass sheet 12 (preferably an inner glass sheet) are heated simultaneously or individually to a temperature above their softening points (e.g., 700 to 800°C) and bent. After firing, the glass sheets are slowly cooled.

Next, a relatively thick first glass sheet 11 (preferably an outer glass sheet) and a relatively thin second glass sheet 12 (preferably an inner glass sheet) are bonded together via a resin film made of the material for the interlayer 20 (preferably a laminate film including a pair of surface layers with a relatively high glass transition temperature (Tg) and an intermediate layer sandwiched between the pair of surface layers and with a relatively low glass transition temperature (Tg)).

The lamination can be performed by thermocompression bonding. Examples of thermocompression bonding methods include a method in which a relatively thick first glass plate 11, a resin film that is the material for the interlayer 20, and a relatively thin second glass plate 12 are stacked together, and the resulting temporary laminate is placed in a vacuum bag and heated in a vacuum; a method in which the temporary laminate is pressurized and heated using an automatic pressure and heat treatment device, an autoclave, or the like; and a combination of these methods.
The thermocompression bonding conditions, including temperature, pressure, and time, are not particularly limited and are designed depending on the type and temperature of the resin film. The thermocompression bonding conditions may be any conditions that allow the resin film to soften, sufficient pressure to be applied, and sufficient adhesion between the relatively thick first glass plate 11 and the relatively thin second glass plate 12 via the resin. Thermocompression bonding may be performed in multiple stages using different methods or conditions.
The resin constituting the resin film softens and spreads to fill the space between the relatively thick first glass plate 11 and the relatively thin second glass plate 12 .

The thermocompression bonding step preferably includes a preliminary compression bonding step and a main compression bonding step.
In the preliminary pressure-bonding step, for example, the temporary laminate is placed in a vacuum bag and heated under reduced pressure at a pressure inside the bag of approximately -65 to -100 kPa (absolute pressure of approximately 36 to 1 kPa) at a temperature in the range of 60 to 110°C, which is lower than the heating temperature in the subsequent main pressure-bonding step. The heating temperature is preferably 60 to 100°C, more preferably 60 to 90°C. The heating time is preferably 5 to 30 minutes.
In the main pressure bonding step, for example, the pre-press bonded body obtained can be placed in an autoclave and heated under pressure at a pressure of about 0.6 to 1.3 MPa and a temperature of 100 to 150° C. The heating temperature is preferably 110 to 150° C., more preferably 120 to 150° C. The heating time is preferably 20 to 40 minutes.
In this manner, the laminated glass of the present disclosure is produced.

There are no particular restrictions on the timing of bending the two glass sheets. Instead of bending two glass sheets in advance, a cold bending method may be used in which only one of the glass sheets is bent in advance, and the resin film material for the interlayer and the other glass sheet are curved along this shape while being bonded together.

As described above, the present disclosure can provide laminated glass having a different thickness configuration in which the thicknesses of the two glass sheets are not the same, and having excellent sound insulation, vibration damping, and rigidity.
The laminated glass of the present disclosure can have good vibration damping properties against sounds in a wide frequency range from 25 Hz to 10 kHz.
The laminated glass of the present disclosure can have good vibration damping properties even against high-frequency sounds such as wind noise, which are prone to coincidence phenomena.
The laminated glass of the present disclosure can have good vibration-damping properties even in a frameless structure where vibration-damping properties tend to decrease due to the lack of support from a frame.

[Application]
The laminated glass of the present disclosure is suitable for use as window glass in moving bodies such as automobiles, trains, aircraft, and ships; and window glass in buildings.
The laminated glass of the present disclosure is suitable for use as window glass for vehicles such as automobiles, including windshields, rear windows, side windows, and roof glass.
The laminated glass of the present disclosure is suitable for use as window glass for vehicles such as electric vehicles, and is particularly suitable for use as window glass for vehicles that are thin, lightweight, and have a frameless structure.

The present invention will be described below based on examples, but the present invention is not limited to these. Examples 11, 12, 21, and 22 are examples, and Examples 101, 102, and 111 are comparative examples.

[Evaluation items and evaluation methods]
The evaluation items and evaluation methods are as follows:
(Dynamic viscoelastic properties and glass transition temperature (Tg))
The dynamic viscoelasticity of the surface layer (skin layer) of the resin film used as the interlayer material was measured using a Rheovibron dynamic viscoelasticity automatic measuring instrument manufactured by A&D Co., Ltd. The measurement conditions were as follows:
Sample size: 5mm x 12mm
Measurement mode: tension mode,
Frequency: 1Hz,
Measurement temperature range: 23°C to 114°C or 129°C,
Temperature rise rate: 3 ° C./min
Measurement temperature increments: 3°C,
Static tension: 5gf,
Amplitude: ±10 μm.
From the data on the temperature dependency of the loss tangent (tan δ), the peak temperature of the loss tangent (tan δ) (the temperature at which the loss tangent (tan δ) is maximum) was determined as the glass transition temperature (Tg).
The storage modulus (E') at 23°C was determined from the data on the temperature dependency of the storage modulus (E').

(Resonant frequency (f) and loss factor (η))
For the laminated glass (25 mm long × 300 mm wide) obtained in each example, the resonance frequencies (f) (f ₁ to f ₅ ) and loss factors (η) (η 1 to η 5 ) of each vibration mode (1st to 5th) were measured by the mechanical impedance method in accordance with ISO/PAS 16940:2008 using a loss factor measurement system (" _AS - _14PA5 " manufactured by Rion Co., Ltd.).
The sample was subjected to central excitation, in which the center of the sample was supported and both ends of the sample were treated as free ends (supported portion) and vibrated. The loss factor (η) was calculated from the frequency response function obtained using the half-width method. The loss factor (η) is an index of sound insulation.

(Vibration damping)
As shown in FIG. 9, the laminated glass (LG) (300 mm long x 500 mm wide) obtained in each example was hung and freely supported, and a hammering test was carried out.
On the central axis CA parallel to the top and bottom sides of the figure, point P1, located 50 mm from the right side of the figure, was the impact point, and point P2, located 50 mm from the left side of the figure, was the measurement point. An impact hammer was struck against impact point P1 to generate vibration. At measurement point P2, the vibration resulting from the excitation was detected by an acceleration sensor, and inertance [m/s ² /N] in the frequency range of 25 Hz to 10 kHz was determined by 1/3 octave band analysis and converted to inertance [dB] using common logarithms. The average value of the obtained inertance [dB] in the 25 Hz to 10 kHz range was calculated. The inertance [dB] measured by the hammering test is one indicator of vibration damping performance.

(bending rigidity)
A sample measuring 100 mm long x 300 mm wide was cut out from the laminated glass (300 mm long x 500 mm wide) obtained in each example. A three-point bending test was performed using a compression and tension testing machine. A load was applied to the sample under conditions of a temperature of 23°C and a span of 200 mm. The load was continuously increased so that the rate of increase in the amount of displacement was 1 mm/min. A graph showing the relationship between displacement and load was obtained with displacement as the horizontal axis parameter and load as the vertical axis parameter, and the slope of the graph (load/displacement) [N/mm] in the load range of 20 to 100 N was calculated as the bending rigidity.

[Resin film]
As materials for the interlayer film, three types of polyvinyl butyral (PVB) films (PVBF1) to (PVBF3) (each with a thickness of 760 μm) were prepared, each consisting of a laminate film made of a pair of surface layers each having a glass transition temperature (Tg) of 15°C or higher and an intermediate layer sandwiched between the pair of surface layers and having a glass transition temperature (Tg) of less than 15°C.
The three types of PVB films (PVBF1) to (PVBF3) were prepared by adjusting the properties of polyvinyl butyral, such as the viscosity-average degree of polymerization, the degree of acetalization, the vinyl acetate unit content, the vinyl alcohol unit content, the ethylene unit content, the molecular weight and chain length of the aldehyde used for acetalization, and/or the plasticizer content, so that the glass transition temperatures (Tg) of the surface layers were different.

Dynamic viscoelasticity measurements were performed on the surface layer of each PVB film. Data on the temperature dependence of the loss tangent (tan δ) of the surface layer of each PVB film are shown in Figure 2. Data on the temperature dependence of the storage modulus (E') of the surface layer of each PVB film are shown in Figure 3.
For each PVB film, the glass transition temperature (Tg) (peak temperature of loss tangent (tan δ)) and storage modulus (E′) at 23° C. were determined. The evaluation results are shown in Table 1.
The intermediate layer of each PVB film was also subjected to dynamic viscoelasticity measurement, and it was confirmed that the glass transition temperature (Tg) was less than 15°C.

[Examples 11, 12, 21, 22, 101, 102, 111]
In each example, soda-lime glasses having different thicknesses were prepared as the first and second glass sheets. The thicknesses ( _T1 ) of the first glass sheet were 2.64 mm, 2.85 mm, 3.07 mm, and 3.39 mm. The thicknesses ( _T2 ) of the second glass sheet were 1.12 mm, 1.25 mm, 1.81 mm, and 2.00 mm.

In each example, a relatively thick first glass plate, a resin film made from the interlayer material, and a relatively thin second glass plate were stacked together, and the resulting pre-laminate was placed in a vacuum bag. The pre-laminate placed in the vacuum bag was pre-pressed at 120°C for 30 minutes while being degassed under a reduced pressure of -60 kPa or less absolute, and then final pressing was performed for 30 minutes at a temperature of 140°C and a pressure of 1.3 MPa.

In this manner, two laminated glasses having different planar sizes were obtained in each example.
The laminated glass used to measure the resonant frequency (f) and loss factor (η) had a size of 25 mm length x 300 mm width for the first glass plate, the resin film as the interlayer material, and the second glass plate.
The laminated glass for the hammering test had a size of 300 mm length x 500 mm width for the first glass plate, the resin film as the material for the interlayer, and the second glass plate.

[Summary of results]
The main production conditions and evaluation results are shown in Tables 1 and 2. In these tables, conditions not listed in the tables were common conditions.

For the laminated glass obtained in each example, the relationship between f ₂ /T _R and inertance, the relationship between f ₁ /T _R and inertance, the relationship between f ₃ /T _R and inertance, the relationship between f ₄ /T _R and inertance, and the relationship between f ₅ /T _R and inertance are shown in Figures 4 to 8.
As shown in these figures, when the ratio (f _N /T _R ) [Hz] of the resonance frequency (f _N ) of each vibration mode of the laminated glass to the plate thickness ratio (T _R ) is taken as the x-axis parameter and the inertance [dB] is taken as the y-axis parameter, it was found that f _N /T _R and inertance are in a proportional relationship or a relationship close to that expressed by y = -ax (where x is f _N /T _R , y is inertance, and a is a positive constant).
Here, N represents the order of the vibration mode and is an integer from 1 to 5.

As shown in FIG. 4, in the second mode, the inertance could be reduced to 4.0 dB or less when f ₂ /T _R was in the range of 350 to 1500 Hz, and the inertance could be further reduced to 3.0 dB or less when f ₂ /T _R was in the range of 400 to 1500 Hz.

As shown in FIG. 5, in the first mode, the inertance could be reduced to 5.0 dB or less when f ₁ /T _R was in the range of 60 to 300 Hz, and the inertance could be further reduced to 4.0 dB or less when f ₁ /T _R was in the range of 70 to 300 Hz.

As shown in FIG. 6, in the third mode, the inertance could be reduced to 5.0 dB or less when f ₃ /T _R was in the range of 900 to 3500 Hz, and the inertance could be further reduced to 4.0 dB or less when f ₃ /T _R was in the range of 1000 to 3500 Hz.

As shown in FIG. 7, in the fourth mode, the inertance could be reduced to 4.0 dB or less when f ₄ /T _R was in the range of 1650 to 6500 Hz, and the inertance could be further reduced to 3.0 dB or less when f ₄ /T _R was in the range of 1900 to 6500 Hz.

As shown in FIG. 8, in the fifth mode, the inertance could be reduced to 5.0 dB or less when f ₅ /T _R was in the range of 2600 to 9000 Hz, and the inertance could be further reduced to 3.0 dB or less when f ₅ /T _R was in the range of 2800 to 9000 Hz.

The laminated glasses obtained in Examples 11, 12, 21, and 22 all had a bending rigidity of 130 N/mm or more, and thus had good rigidity. It was confirmed that a configuration in which the thicknesses of the two glass sheets are designed to be unequal can achieve both a thin, lightweight structure and rigidity.
In all of the laminated glasses obtained in these examples, the interlayer film was a laminated film including a pair of surface layers each having a glass transition temperature (Tg) of 15° C. or higher and an interlayer sandwiched between the pair of surface layers and having a glass transition temperature (Tg) of less than 15° C. The glass transition temperature (Tg) of the pair of surface layers was high, at 30° C. or higher (35° C. or higher), and the storage modulus (E′) of the pair of surface layers measured at 23° C. and a frequency of 1 Hz was high, at 100 MPa or higher (150 MPa or higher).
The laminated glasses obtained in these examples all had a loss coefficient (η ₁ to η ₅ ) of 0.10 or more in each vibration mode, a large sound transmission loss (STL), and good sound insulation.
The laminated glasses obtained in these examples all had f ₂ /T _R of 350 to 1500 Hz, f ₁ /T _R of 60 to 300 Hz, f 3 /T _R of 900 to 3500 Hz, f ₄ /T _R of 1650 to 6500 Hz, and f _{5 /} T _R of 2600 to 9000 Hz, and had small inertance of 4.0 dB or less, and had good vibration damping properties.

The laminated glasses obtained in Examples 101, 102, and 111 all had a bending rigidity of 130 N/mm or more, and had good rigidity.
In all of the laminated glasses obtained in these examples, the interlayer film was a laminated film including a pair of surface layers each having a glass transition temperature (Tg) of 15°C or higher and an interlayer sandwiched between the pair of surface layers and having a glass transition temperature (Tg) of less than 15°C.
The laminated glasses obtained in these examples all had a loss coefficient (η ₁ to η ₅ ) of 0.10 or more in each vibration mode, a large sound transmission loss (STL), and good sound insulation.
However, the laminated glasses obtained in these examples all had f ₂ / _TR of less than 350 Hz, and had larger inertance than Examples 11, 12, 21, and 22, and were inferior in vibration damping properties.
It is believed that the laminated glasses obtained in Examples 101 and 111 were prone to vibration due to a large sheet thickness ratio ( _TR ) and poor weight balance, and therefore did not provide sufficient vibration damping properties.
In the laminated glasses obtained in Examples 101 and 102, the pair of surface layers had a glass transition temperature (Tg) of less than 30° C., and the pair of surface layers had a storage modulus (E′) of less than 100 MPa when measured at 23° C. and a frequency of 1 Hz. Therefore, it is thought that the restraining force of the surface layer of the intermediate layer was low, the effect of damping vibration of the intermediate layer was not effectively obtained, and sufficient vibration-damping properties were not obtained.

The present invention is not limited to the above-described embodiments and examples, and design modifications can be made as appropriate without departing from the spirit of the present invention.

This application claims priority based on Japanese Patent Application No. 2024-38171, filed March 12, 2024, the disclosure of which is incorporated herein in its entirety.

1: Laminated glass, 11: First glass sheet, 12: Second glass sheet, 20: Interlayer film, 21, 22: Surface layers, 23: Interlayer.

Claims (13)

A laminated glass in which a relatively thick first glass plate and a relatively thin second glass plate are bonded together via an interlayer film,
where the ratio of the thickness of the first glass sheet to the thickness of the second glass sheet is defined as the sheet thickness ratio (T _R ), and the second-order mode resonance frequency and second-order mode loss factor of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 are f _{2 and} η ₂ , respectively, the ratio of the second-order mode resonance frequency of the laminated glass to the sheet thickness ratio (f ₂ /T _R ) is 350 to 1500 Hz, η ₂ is 0.10 or more, and 1.0<T _R <3.0;
The interlayer film is a laminated film including a pair of surface layers each having a glass transition temperature (Tg) of 15°C or higher and an intermediate layer sandwiched between the pair of surface layers and having a glass transition temperature (Tg) of lower than 15°C, and the pair of surface layers have a storage modulus (E') of 100 MPa or higher as measured at 23°C and a frequency of 1 Hz. When the resonance frequency of the first mode of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 is defined as _f1 ,
2. The laminated glass according to claim 1, wherein the ratio (f ₁ /T _R ) of the resonance frequency of the first mode of the laminated glass to the plate thickness ratio is 60 to 300 Hz. When the resonance frequency of the third mode of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 is defined as _f3 ,
2. The laminated glass according to claim 1, wherein a ratio (f ₃ /T _R ) of the third-order mode resonance frequency of the laminated glass to the sheet thickness ratio is 900 to 3500 Hz. When the fourth-order mode resonance frequency of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 is defined as _f4 ,
2. The laminated glass according to claim 1, wherein the ratio (f ₄ /T _R ) of the fourth-order mode resonance frequency of the laminated glass to the plate thickness ratio is 1650 to 6500 Hz. When the resonance frequency of the fifth mode of the laminated glass measured by a mechanical impedance method in accordance with ISO/PAS 16940:2008 is defined as _f5 ,
2. The laminated glass according to claim 1, wherein a ratio (f ₅ /T _R ) of the fifth mode resonance frequency of the laminated glass to the sheet thickness ratio is 2600 to 9000 Hz. 2. The laminated glass according to claim 1, wherein η1, η3, η4, and η5 are the first-order mode loss factor, third-order mode loss factor, fourth-order mode loss factor, and fifth-order mode loss factor of the laminated glass measured by _{a mechanical} impedance method in accordance with ISO/PAS 16940: ₂₀₀₈ , respectively, and at least one of _η1 , _η3 , _η4 , and _η5 is _0.10 or greater. The laminated glass of claim 1, wherein the second glass sheet has a thickness of 0.3 to 3.0 mm. The laminated glass according to claim 1, wherein the total thickness of the first glass sheet and the second glass sheet is 4.0 to 6.0 mm. The laminated glass according to claim 1, wherein 1.30≦T _R ≦2.50. The laminated glass according to claim 1, wherein the interlayer film contains one or more thermoplastic resins selected from the group consisting of polyvinyl acetal, ionomer, ethylene-vinyl acetate copolymer, cycloolefin polymer, polymethyl methacrylate, and polyurethane. The laminated glass according to claim 1, wherein the glass transition temperature (Tg) of the pair of surface layers is 30°C or higher. The laminated glass according to claim 1, wherein the pair of surface layers have a glass transition temperature (Tg) of 35°C or higher. The laminated glass according to claim 1, wherein the pair of surface layers have a storage modulus (E') of 150 MPa or more, measured at 23°C and a frequency of 1 Hz.