FR3054167A1 - VISCOELASTIC PLASTIC INTERIOR FOR VIBRO-ACOUSTIC DAMPING AND GLAZING COMPRISING SUCH AN INTERCALAR - Google Patents

Abstract

The invention relates to a viscoelastic plastic interlayer intended to be incorporated between two sheets of glass of a laminated glazing unit, the interlayer comprising: two external layers (4, 5) of standard PVB, with a thickness of between 0.10 mm and 0.40 mm each, - an inner layer (3) of viscoelastic plastic material with improved acoustic properties, disposed between the two outer layers (4, 5), of thickness strictly greater than 0.15 mm and less than or equal to at 1.05 mm, the total thickness of the spacer being between 0.90 mm and 1.25 mm, and the insert being such that the resonant frequency fi of the first resonance mode of a glazing bar laminated between which is incorporated the interlayer, determined by MIM at 20 ° C according to ISO 16940, is between 90 Hz and 115 Hz and that the modal damping η1 of said first resonance mode of said bar, determined by MIM in the same conditions is between 0.20 and 0.35. The invention allows a reduction in the thickness of the glass sheets without degradation of the vibro-acoustic damping properties, in particular in a frequency range between 3150 Hz and 6300 Hz.

Description

® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number: 3,054,167 (to be used only for reproduction orders)

©) National registration number: 16 56860

COURBEVOIE © Int Cl ⁸ : B 32 B 17/10 (2017.01), B 60 J 1/02, 1/08

A1 PATENT APPLICATION

©) Date of filing: 19.07.16. © Applicant (s): SAINT-GOBAIN GLASS FRANCE (© Priority: Public limited company - FR. @ Inventor (s): GILLESSEN STEPHAN, KREBS BENJAMIN, VON DER WEIDEN Ingo and MERCIER (43) Date of public availability of the GERALD. request: 26.01.18 Bulletin 18/04. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): SAINT-GOBAIN GLASS FRANCE related: Anonimous society. ©) Extension request (s): © Agent (s): SAINT GOBAIN RESEARCH Anonimous society.

VISCOELASTIC PLASTIC SPACER FOR VIBROACOUSTIC AND GLAZING DAMPING INCLUDING SUCH A SPACER.

FR 3 054 167 - A1 (3 /) The invention relates to a viscoelastic plastic interlayer intended to be incorporated between two glass sheets of laminated glazing, the interlayer comprising:

- two external layers (4, 5) in standard PVB, of thickness between 0.10 mm and 0.40 mm each,

- an internal layer (3) of viscoelastic plastic material with improved acoustic properties, disposed between the two external layers (4, 5), of thickness strictly greater than 0.15 mm and less than or equal to 1.05 mm, l total thickness of the interlayer being between 0.90 mm and 1.25 mm, and the interlayer being such that the resonance frequency fi of the first resonance mode of a laminated glazing rod between which the interlayer, determined by MIM at 20 ° C according to ISO 16940, is between 90 Hz and 115 Hz and that the modal damping rq of said first resonance mode of said bar, determined by MIM under the same conditions, is between 0 , 20 and 0.35.

The invention allows a reduction in the thickness of the glass sheets without degradation of the vibro-acoustic damping properties, in particular in a range

frequency between 3150 Hz and 6300 Hz.

VISCOELASTIC PLASTIC SPACER FOR VIBROACOUSTIC AND GLAZING DAMPING COMPRISING SUCH A SPACER

The invention relates to a viscoelastic plastic interlayer intended to be incorporated between two sheets of glass to form a laminated glazing having vibro-acoustic damping properties, intended in particular for locomotion vehicles, in particular a motor vehicle.

Among all the qualities contributing to comfort in modern means of transport such as trains and cars, silence has become decisive.

Acoustic comfort has been improved for several years now, by dealing with noises, such as engine, rolling or suspension noises, and this at their origin or during their air propagation or in solids.

Vehicle shapes have also been modified to improve air penetration and reduce turbulence, which is itself a source of noise.

And for a few years now, we have looked at the role that glazing could play in improving acoustic comfort, in particular laminated glazing with plastic interlayer films. Laminated glazing also has other advantages such as eliminating the risk of fragments being thrown in the event of a sudden break, or even constituting a burglary retardant.

It has been shown that the use of standard plastic films in laminated glazing is not suitable for improving acoustic comfort. Specific plastic films were then developed which had damping properties allowing an improvement in acoustic comfort.

Furthermore, in existing windshields, the thickness of the glass sheet intended to be turned towards the outside of the vehicle is generally 2.1 mm and the thickness of the glass sheet intended to be turned towards the interior of the vehicle is generally 1.6 mm. However, the trend is to lighten motor vehicles in order to reduce their consumption and the resulting CO ₂ rejection. One way is to offer lighter automotive glass. One solution to reduce the weight of glazing is to reduce the thickness of the glass sheets.

-2 However, this reduction in thickness leads to a degradation of the acoustic properties of laminated glazing, in particular in a frequency range between 3150 Hz and 6300 Hz, that is to say at the frequencies where the human ear is most sensitive .

There is therefore a need for a viscoelastic plastic interlayer intended to be incorporated between two sheets of glass to form a laminated glazing having vibro-acoustic damping properties, which allows a reduction in the thickness of the glass sheets without degradation of the vibro-acoustic damping properties, in particular in a frequency range between 3150 Hz and 6300 Hz.

For this, the invention provides a viscoelastic plastic interlayer intended to be incorporated between two glass sheets of laminated glazing to give it vibro-acoustic damping properties, the interlayer comprising:

- two external layers in standard PVB, each having a thickness of between 0.10 mm and 0.40 mm,

- an inner layer of viscoelastic plastic material based on polyvinyl acetal, with improved acoustic properties, the inner layer being disposed between the two outer layers and the inner layer having a thickness strictly greater than 0.15 mm and less than or equal at 1.05 mm, the total thickness of the interlayer being between 0.90 mm and 1.25 mm, and the interlayer being such that the resonance frequency T of the first resonance mode of a glazing rod laminated surface 25 mm x 300 mm composed of two glass sheets of respective thicknesses 1.8 mm and 1.4 mm between which the interlayer is incorporated, determined by a measurement of the mechanical impedance (MIM) at 20 ° C according to ISO 16940, is between 90 Hz and 115 Hz and that the modal damping ηι of said first resonance mode of said bar, determined by MIM under the same conditions, is between 0.20 and 0.35.

According to another particularity, the outer layers have a shear modulus G 'greater than or equal to 1.10 ⁸ Pa and a loss factor tan δ less than 0.4, at 20 ° C and for a frequency range between 1 kHz and 10 kHz.

According to another particular feature, the interlayer is such that the resonance frequency fi of the first resonance mode of a laminated glazing rod of sur3054167

-3face 25 mm x 300 mm composed of two glass sheets of respective thicknesses 1.8 mm and 1.4 mm between which the interlayer is incorporated, determined by a measurement of the mechanical impedance (MIM) at 20 ° C according to ISO 16940, is between 95 and 105 Hz and that the modal damping ηι of said first resonance mode of said bar, determined by MIM under the same conditions, is between 0.27 and 0.35.

In another feature, each outer layer has a thickness of about 0.35 mm.

The invention also relates to laminated glazing comprising:

- a glass sheet of thickness between 0.5 mm and 2.1 mm,

- a glass sheet of thickness between 0.5 mm and 2.1 mm,

- an interlayer as described above, the interlayer being between the sheets of glass.

The invention also relates to the use of the above glazing as a glazing for a motor vehicle.

Other characteristics and advantages of the invention will now be described with reference to the drawings in which:

• Figure 1 represents an evaluation of airborne sound insulation (STL - Sound Transmission Loss in English) as a function of frequency, for 4 different laminated glazings;

• Figure 2 shows a sectional view of a glazing according to the invention.

Note that the expression "between ... and ..." includes the bounds in the interval.

The invention relates to a viscoelastic plastic interlayer intended to be incorporated between two glass sheets of laminated glazing to provide it with vibro-acoustic damping properties. The tab includes:

- two external layers in standard PVB, each having a thickness of between 0.10 mm and 0.40 mm,

- an inner layer of viscoelastic plastic material based on polyvinyl acetal, with improved acoustic properties, the inner layer being disposed between the two outer layers and the inner layer having a thickness strictly greater than 0.15 mm and less than or equal at 1.05 mm.

- 4 The total thickness of the interlayer is between 0.90 mm and 1.25 mm.

In addition, the interlayer is such that the resonance frequency fi of the first resonance mode of a laminated glazing rod with a surface 25 mm × 300 mm composed of two glass sheets of thicknesses 1.8 mm and 1 respectively. 4 mm between which the interlayer is incorporated, determined by a measurement of the mechanical impedance (MIM) at 20 ° C according to ISO 16940, is between 90 Hz and 115 Hz and that the modal damping ηι of said first mode resonance of said bar, determined by MIM under the same conditions, is between 0.20 and 0.35.

Thus, the interlayer according to the invention, which comprises at least three layers, at least one internal layer of which has remarkable acoustic damping properties, has a thickness of at least 0.90 mm, ie a thickness greater than the thicknesses usual interlayer, which allows greater damping, especially in a frequency range between 3150 Hz and 6300 Hz.

The inventors have demonstrated, as will be seen below, that a spacer having these characteristics of thickness, resonance frequency and modal damping makes it possible to obtain a thinned laminated glazing with equivalent or even superior acoustic performance, to those of laminated glazing with conventional glass thicknesses incorporating an interlayer with improved acoustic properties known on the desired strip, that is to say between 3150 and 6300 Hz.

The interlayer according to the invention is intended to be incorporated between two sheets of glass to form a laminated glazing. This laminated glazing for example can be used in a motor vehicle.

FIG. 2 represents a sectional view of a glazing according to the invention.

The glazing comprises two sheets of glass 1, 2 between which the interlayer according to the invention is inserted. The interlayer is secured to the glass sheets by known means, for example by stacking the glass sheets and the interlayer and by passing the assembly through an autoclave.

The glass sheet 1 of the glazing is intended to be turned towards the outside of the vehicle while the glass sheet 2 is intended to be turned towards the inside of the vehicle. The glass sheet 1 is for example thicker than the glass sheet 2 so that the glazing allows better protection

-5 against external attacks (bad weather, projection of gravel, etc ...). The thicker the glass, the more it is mechanically resistant. However, the thicker the glass, the heavier it is. A compromise must therefore be found between the mechanical strength and the weight of the glazing. The thickness of each glass sheet 1, 2 is for example between 0.5 mm and 2.1 mm.

In existing automotive glazing, the thickness of the glass sheet 1 is generally 2.1 mm and the thickness of the glass sheet 2 is generally 1.6 mm.

Preferably, according to the invention, the thickness of the glass sheet 1 is 1.8 mm and the thickness of the glass sheet 2 is 1.4 mm in order to limit the weight of the glazing, which allows reduce the fuel consumption of a vehicle fitted with such glazing. This also makes it easier to handle the glazing and to save material.

The glazing according to the invention can also comprise a glass sheet 1 with a thickness of 1.6 mm and a glass sheet 2 with a thickness of 1.2 mm, or a glass sheet 1 with a thickness of 1.4 mm and a glass sheet 2 of thickness 1.1 mm.

The interlayer consists of at least one inner layer 3 of viscoelastic plastic with improved vibro-acoustic damping properties. It is based on polyvinyl acetal and plasticizer. The level and nature of the plasticizer and the degree of acetalization of the polyvinyl butyral make it possible to play in a known manner on the rigidity of a component based on polyvinyl butyral and of plasticizer.

In the example of FIG. 2, the interlayer also comprises two layers 4, 5, called external layers, between which layer 3 is inserted. The two external layers 4, 5 are made of polyvinyl butyral (PVB), called standard PVB by opposition to the material of the inner layer 3 which is based on polyvinyl acetal and plasticizer and which is less rigid and more damping than the so-called standard PVB. The outer layers have a shear modulus G 'greater than or equal to 1.10 ⁸ Pa and a loss factor tan δ less than 0.4, at 20 ° C and for a frequency range between 1 kHz and 10 kHz. The outer layers 4, 5 allow good mechanical strength of the interlayer.

As a variant, the interlayer may include at least two layers of viscoelastic plastic with improved vibro-acoustic damping properties, surrounded or not with layers of standard PVB.

-6The inner layer 3 has a thickness strictly greater than 0.15 mm and less than or equal to 1.05 mm while the outer layers 4, 5 each have a thickness between 0.10 and 0.40 mm, preferably equal about 0.35 mm.

The layer 3 is less rigid than the outer layers 4, 5 in order to provide the interlayer with improved acoustic properties. The increase in the thickness of layer 3 compared to known spacers (in general layer 3 has a thickness of 0.15 mm) allows more damping for the multilayer assembly.

As we will see later, in connection with Figure 1, an increase in the thickness of the interlayer in fact makes it possible to compensate for the loss of acoustic insulation from airborne noise due to the reduction in glass thickness, or even d '' improve the acoustic performance of the glazing although the weight of the glass is lower, in particular between 3150 Hz and 6300 Hz.

The acoustic characteristics of the interlayer are determined by measuring the mechanical impedance (MIM) at 20 ° C according to ISO 16940 of a 25 mm x 300 mm laminated glazing rod composed of two sheets of glass. respective thicknesses 2.1 mm and 1.6 mm (for the standard thickness glass reference sample) or 1.8 mm and 1.4 mm (for the reduced thickness glass samples) (and not 4 mm as recommended in standard ISO 16940) between which is incorporated a spacer according to the invention, that is to say a spacer comprising at least one internal layer of viscoelastic plastic with improved vibro-acoustic damping properties, located between two standard PVB outer layers.

MIM is used to determine resonance frequencies and loss factors for the different mechanical impedance modes of the laminated glazing rod.

The interlayer is according to the invention if the resonance frequency fi of the first resonance mode of a laminated glazing bar with a surface 25 mm × 300 mm composed of two glass sheets of respective thicknesses 1.8 mm and 1, 4 mm between which the interlayer is incorporated, determined by a measurement of the mechanical impedance (MIM) at 20 ° C according to ISO 16940, is between 90 Hz and 115 Hz and that the modal damping ηι of said first mode of

- 7 3054167 resonance of said bar, determined by MIM under the same conditions, is between 0.20 and 0.35.

Preferably, the resonance frequency fi is between 95 Hz and 105 Hz and the loss factor ηι is between 0.27 and 0.35, which makes it possible to have further improved acoustic performance, in particular between 3150 Hz and 6300 Hz.

Figure 1 shows a curve of airborne sound insulation (STL in English) as a function of frequency, evaluated on four laminated glazings.

Thus, a first laminated glazing (2.1 mm / 1.6 mm - total thickness of 0.85 mm) includes:

- two glass sheets of respective thicknesses 2.1 mm and 1.6 mm, and an interlayer comprising two external layers in standard PVB of thickness 0.35 mm and a central layer in viscoelastic plastic with vibro-damping properties- 0.15 mm thick improved acoustics.

The resonance frequency fi is 153 Hz (± 5 Hz) and the loss factor ηι is equal to 0.17 (± 0.05).

The first laminated glazing corresponds to a conventional windshield glass composition with an interlayer with acoustic damping properties, of known thickness. This is the reference laminated glazing.

The airborne sound insulation curve (represented by circles) of the first laminated glazing shows a critical frequency of the glazing around 5000 Hz.

A second laminated glazing (1.8 mm / 1.4 mm - total thickness of 0.85 mm) includes:

- two glass sheets of respective thicknesses 1.8 mm and 1.4 mm, and an interlayer comprising two external layers in standard PVB of thickness 0.35 mm and a central layer in viscoelastic plastic with vibro-damping properties- 0.15 mm thick improved acoustics.

The resonance frequency fi is 127 Hz (± 5 Hz) and the loss factor ηι is equal to 0.16 (± 0.05).

The second laminated glazing corresponds to a thinned laminated glazing with an interlayer with acoustic damping properties, of known thickness.

-8The airborne sound insulation curve (represented by diamonds) of the second laminated glazing shows a degraded behavior compared to that of the first laminated glazing above 5000 Hz, with a critical frequency shifted towards 6300 Hz.

Before 3150 Hz, there is also a decrease in airborne sound insulation. The sound insulation in this frequency range is characteristic of the mass of the glazing. This degradation is therefore explained by the fact that the mass of glass has decreased.

A third laminated glazing (1.8 mm / 1.4 mm - 0.35 mm core - total thickness of 1.05 mm) includes:

- two glass sheets of respective thicknesses 1.8 mm and 1.4 mm, and an interlayer comprising two external layers in standard PVB of thickness 0.35 mm and a central layer in viscoelastic plastic with vibro-damping properties- acoustic thickness 0.35 mm.

The resonance frequency fi is 110 Hz (± 5 Hz) and the loss factor ηι is equal to 0.25 (± 0.05).

The third laminated glazing corresponds to a thinned laminated glazing with an interlayer with thickened acoustic damping properties.

The airborne sound insulation curve (represented by squares) of the third laminated glazing shows a great improvement in the acoustic properties between 3150 Hz and 6500 Hz compared to the first laminated glazing, with a critical frequency around 6300 Hz.

Before 3150 Hz, there is also an improvement in airborne sound insulation.

A fourth laminated glazing (1.8 mm / 1.4 mm - core 0.55 mm - total thickness of 1.25 mm) includes:

- two glass sheets of respective thicknesses 1.8 mm and 1.4 mm, and an interlayer comprising two external layers in standard PVB thickness 0.35 mm and a central layer in viscoelastic plastic with vibro-acoustic damping properties d '' thickness 0.55 mm.

The resonance frequency fi is 102 Hz (± 5 Hz) and the loss factor ηι is equal to 0.29 (± 0.05).

The fourth laminated glazing corresponds to a thinned laminated glazing with a very thickened interlayer.

-9The airborne sound insulation curve (represented by triangles) of the fourth laminated glazing shows an even more significant improvement in the acoustic properties between 3150 Hz and 6500 Hz compared to the third laminated glazing, with a critical frequency which shifts a little towards high frequencies (around 8000 Hz), therefore at frequencies to which the human ear is not very sensitive.

Before 3150 Hz, there is also a further improvement in airborne sound insulation compared to the third laminated glazing, with a level of insulation almost identical to that of the reference laminated glazing. The sound insulation due to the large thickness of interlayer therefore almost compensated for the loss of sound insulation due to the reduction in mass of the glass.

The laminated glazing according to the invention can be used as a motor vehicle windshield. In this case, it naturally meets all the conditions of regulation No. 43 of the United Nations (known as regulation R43) of resistance to hard shocks to ensure its mechanical resistance.

Claims (6)

1. A viscoelastic plastic interlayer intended to be incorporated between two glass sheets of laminated glazing to provide it with vibro-acoustic damping properties, the interlayer comprising: - two external layers (4, 5) in standard PVB, each having a thickness of between 0.10 mm and 0.40 mm, - an inner layer (3) of viscoelastic plastic material based on polyvinyl acetal, with improved acoustic properties, the inner layer (3) being arranged between the two outer layers (4, 5) and the inner layer (3) having a thickness strictly greater than 0.15 mm and less than or equal to 1.05 mm, the total thickness of the interlayer being between 0.90 mm and 1.25 mm, and the interlayer being such that the frequency resonance T of the first resonance mode of a laminated glazing rod with a surface 25 mm x 300 mm composed of two glass sheets of thicknesses 1.8 mm and 1.4 mm respectively, between which the interlayer, determined by measuring the mechanical impedance (MIM) at 20 ° C according to ISO 16940, is between 90 Hz and 115 Hz and that the modal damping ηι of said first resonance mode of said bar, determined by MIM in the same conditions, is between 0 , 20 and 0.35. 2. The interlayer according to claim 1, in which the outer layers (4, 5) have a shear modulus G 'greater than or equal to 1.10 ^{3 * * * * 8} Pa and a loss factor tan δ less than 0.4, at 20 ° C and for a frequency range between 1 kHz and 10 kHz. 3. The interlayer as claimed in claim 1 or 2, in which the interlayer is such that the resonance frequency T of the first resonance mode of a laminated glazing bar with a surface 25 mm x 300 mm composed of two sheets of glass respective thicknesses 1.8 mm and 1.4 mm between which the interlayer is incorporated, determined by a measurement of the mechanical impedance (MIM) at 20 ° C according to ISO 16940, is between 95 and 105 Hz and that the modal damping ηι of said first resonance mode of said bar, determined by MIM under the same conditions, is between 0.27 and 0.35. - 11 3054167 4. The interlayer according to one of claims 1 to 3, wherein each outer layer (4, 5) has a thickness of about 0.35 mm. 5. Laminated glazing comprising: - a glass sheet (1) of thickness between 0.5 mm and 2.1 mm, 5 - a glass sheet (2) of thickness between 0.5 mm and 2.1 mm, - an interlayer according to any one of claims 1 to 4, the interlayer being between the sheets of glass. 6. Use of the glazing according to claim 5 as glazing for a motor vehicle. 1/1 S J <V 1 u not a E E E E m lo CN O -ç— V ” He II - φ φ ro ro - o o P £ - CL CL Φ Φ S! E E E E LO LO LO CO - o 'o IT L D = 3 Φ Φ O O __ o o i i E E E E sr X. V v— - E E E E ~~ co cq ’1 i - 1 i E_E \ V \ 10 m CO "5 O O 11 II \\\ V \ 3. Total 3. Total W % aï φ i: t t E E u \ LO LO He he = 3 Z3 Φ Φ o o o o > i i E E 'Up , 4 m , 6 rr % V “V E E E E k λ 00 V “ v- I 1 ♦ · M \\ ! ο ο ο ο ο ο ο οο ο ο m CD Ο Ο ο ΙΟ Ο Ο ο sr Ο LO CN Ο Ο ο ο ο ο LO σ) NOT o I o ⁸ ™ ^î LO ω CN o vs O ω O o 3 σ CN -φ u. ο ο CD ο CO CD CM B σ> O O LO BBBB U- ο LO LO Μ Ο SILO CD ο C0 LO CN [gp] ueuee) injq ne uoi) e | os | D) CN