JP7724085B2 - Soundproofing sheet, method for manufacturing soundproofing sheet, and vehicle dash silencer - Google Patents

Description

The present invention relates to a soundproofing sheet and a vehicle dash silencer that uses the soundproofing sheet.

Patent Document 1 is an invention related to a sheet-shaped low-frequency sound-absorbing material that has an absorption peak in the frequency range of 1000 to 2000 Hz. Patent Document 1 discloses a sheet-shaped low-frequency sound-absorbing material in which a sound-absorbing layer made of fiber or porous material and a meltable thin film layer are laminated in the following order: sound-absorbing layer/thin film layer/sound-absorbing layer (Patent Document 1 [Claim 1]). The thin film layer in Patent Document 1 is fused to the fiber, and it is thought that the vibration of the thin film layer and friction between the fibers are converted into thermal energy, thereby achieving sound absorption (Patent Document 1 [0018]). However, Patent Document 1 does not disclose any sound absorption properties at frequencies below 1000 Hz or above 2000 Hz.

Patent Document 2 is an invention related to an ultra-lightweight soundproofing material. Patent Document 2 focuses on the adhesive state at the interface between a sound absorbing layer and an air-impermeable resonance layer (corresponding to the sound insulating layer of the present invention), and discloses that the air-impermeable resonance layer is made extremely lightweight, and the sound absorbing layer has a two-layer structure of a high-density sound absorbing material and a low-density sound absorbing material, or a sound absorbing layer is provided on the interior side, thereby controlling the transmission loss and sound absorption coefficient at frequencies, thereby insulating noise from outside the vehicle while ensuring sound absorption inside the vehicle cabin and improving quietness inside the vehicle cabin (Patent Document 2 [0010]).
Specifically, it has been disclosed that in a soundproofing material in which a sound absorbing layer and a resonance layer are laminated via an adhesive layer (common form: sound absorbing layer/resonance layer), the transmission loss (sound insulation) and sound absorption coefficient vary depending on the difference in the adhesive area at the interface between the sound absorbing layer and the breathable resonance layer (Patent Document 2, [0061] to [0063]). Furthermore, in the soundproofing material of Example 3-3, which has a second sound absorbing layer on the indoor side (Embodiment 3: sound absorbing layer/resonance layer/sound absorbing layer) and in which the resonance layer is a film body made of an olefin resin, the larger the adhesive area with the second sound absorbing layer, the more the transmission loss improves, and the smaller the adhesive area, the more the sound absorption coefficient improves (Patent Document 2, [0082] to [0088]).

Japanese Patent Application Laid-Open No. 2019-2996 Japanese Patent Application Laid-Open No. 2005-227747

Patent Document 2 discloses that soundproofing performance changes depending on the adhesive area between the non-breathable resonance layer and the sound absorbing layer, but only discloses the adhesive method, such as the amount of adhesive applied, compression pressure, and time. However, it is extremely difficult to control the adhesive area by adjusting the amount of adhesive applied, compression pressure, and time. Whenever the thickness, density, material, ambient temperature, etc. of the resonance layer and sound absorbing layer change, it is necessary to derive the optimal adhesive conditions through trial and error.
The present invention aims to provide a soundproof sheet that includes a sound-insulating layer made of a thermoplastic resin sheet and a sound-absorbing layer made of a fiber sheet and/or a porous material, and that is partially bonded in an extremely simple manner as designed. It also aims to provide a method for manufacturing the soundproof sheet that does not require detailed control of the amount of adhesive applied, compression pressure, time, etc.

After extensive research to solve the above problems, the inventors came up with the idea of using a release agent in combination. Controlling the adhesive area by the amount of adhesive applied, compression pressure, time, etc. requires strict management of these factors, but by applying a release agent in advance to areas where adhesion is not desired, it is possible to adhere the desired area even if manufacturing conditions change slightly.

That is, in order to solve the above problems, the present invention proposes the following means.
[1] A soundproof sheet comprising a sound-insulating layer made of a thermoplastic resin sheet and a sound-absorbing layer made of a fiber sheet and/or a porous material, characterized in that a release agent is partially applied to the surface of the thermoplastic resin sheet that is bonded to the sound-absorbing layer, and the sound-insulating layer is fused to the sound-absorbing layer on the surface that is coated with the release agent, except for the portion that is coated with the release agent.
[2] A soundproof sheet in which a sound-insulating layer made of a thermoplastic resin sheet and a sound-absorbing layer made of a fiber sheet and/or a porous material are laminated in the order of sound-absorbing layer/sound-insulating layer/sound-absorbing layer, wherein a release agent is partially applied to at least one surface of the thermoplastic resin sheet, and the sound-insulating layer is fused to the sound-absorbing layer except for the portion coated with the release agent.
[3] The soundproof sheet according to [1] or [2], wherein the release agent is made of a silicone resin and/or a silicone-modified resin.
[4] The soundproof sheet according to any one of [1] to [3], characterized in that the thermoplastic resin sheet is a multilayer sheet having a low melting point resin layer/a high melting point resin layer/a low melting point resin layer in this order.

[5] A method for producing a soundproof sheet according to any one of [1] to [4], characterized by comprising: a coating step of partially coating a release agent on at least one surface of a thermoplastic resin sheet; and a lamination step of overlaying a fiber sheet and/or a porous material on the coated surface of the thermoplastic resin sheet, melting the surface of the thermoplastic resin sheet, and fusing the thermoplastic resin sheet to the fiber sheet and/or the porous material.
[6] A vehicle dash silencer, characterized by using the soundproof sheet according to any one of [1] to [4].

In the soundproof sheet of the present invention, a release agent is partially coated on at least one surface of the thermoplastic resin sheet that forms the sound-insulating layer. This makes it easy to control the adhesion area between the sound-insulating layer and the sound-absorbing layer. By coating the release agent on the parts of the sound-insulating layer that you do not want to bond, and then fusing the sound-insulating layer to the sound-absorbing layer under conditions that allow the sound-insulating layer to be sufficiently heat-sealed, you can obtain a soundproof sheet in which the sound-insulating layer and the sound-absorbing layer are bonded only in the desired areas.
In particular, when the release agent is made of a silicone adhesive and/or a silicone-modified resin, the surface to which the release agent is applied will be a portion that is not adhered very precisely.

Furthermore, when the sound-insulating layer is a multi-layer sheet having a low-melting-point resin layer/a high-melting-point resin layer/a low-melting-point resin layer in this order, the sound-insulating layer has both very good fusion bonding and sound-insulating properties.
Furthermore, the manufacturing method of the present invention makes it possible to stably obtain a desired soundproof sheet even if the adhesion pressure, time, etc. are slightly changed.
Furthermore, since the contact area between the sound-insulating layer and the sound-absorbing layer of the soundproof sheet of the present invention can be easily controlled, it is possible to particularly reduce the noise level in the frequency band related to human conversation, and the soundproof sheet can be suitably used as a vehicle dash silencer.

1 is a schematic cross-sectional view showing one embodiment of a soundproof sheet of the present invention. 1 is a schematic cross-sectional view illustrating one embodiment of a soundproof sheet of the present invention. 1 is a schematic cross-sectional view showing one embodiment of a soundproof sheet of the present invention. FIG. 1 is a schematic cross-sectional view illustrating one embodiment of a thermoplastic resin sheet. FIG. 2 is a schematic plan view of a sound-insulating layer coated with a release agent.

The present invention will be described in detail below with reference to the drawings, but the present invention is not limited to these. Needless to say, various embodiments are possible within the scope of achieving similar effects.

<Soundproofing layer>
1 is a schematic cross-sectional view showing an embodiment of a soundproof sheet 1 of the present invention. The soundproof sheet 1 in FIG.
The sound-insulating layer itself deforms to attenuate sound vibrations. Therefore, it is desirable for the sound-insulating layer to be flexible enough to be deformed by sound vibrations. It is preferable for the base material to be a thermoplastic resin sheet 21 having a thickness of 10 to 150 μm, preferably 20 to 100 μm, and even more preferably 25 to 50 μm. The tensile modulus of the sheet 21 (based on JIS K7161-2014) is desirably 100 to 1000 MPa, particularly 200 to 700 MPa, and even more desirably 300 to 500 MPa. Thermoplastic resin sheets conventionally used in sound-insulating sheets, such as polyethylene, polypropylene, polyamide, polyester, and polystyrene, can be used as appropriate.

Furthermore, in the soundproof sheet of the present invention, the sound-insulating layer is fused to the sound-absorbing layer, thereby bonding the sound-insulating layer and the sound-absorbing layer together. In other words, at the adhesive joint α between the sound-insulating layer and the sound-absorbing layer, the outermost surface of the sound-absorbing layer 3, made of a fiber sheet or porous material, is embedded in the thermoplastic resin that forms the thermoplastic resin sheet 21. Therefore, it is desirable that the surface of the thermoplastic resin sheet 21 be made of a resin with a relatively low melting point. However, if the thermoplastic resin sheet 21 were made solely of a low-melting-point resin, the sound-insulating layer 2 would be entirely absorbed between the sound-absorbing layers 1 and would no longer exist as a layer. Without the sound-insulating layer 2 as a layer, sound insulation properties cannot be achieved. Therefore, the thermoplastic resin sheet 21 of the present invention is preferably a multilayer sheet having, in order, a low-melting-point resin layer 21L, a high-melting-point resin layer 21H, and a low-melting-point resin layer 21L, as shown in FIG. 4. The difference in melting point between the resin used in the low-melting-point resin layer 21L and the resin used in the high-melting-point resin layer 21H is preferably 15°C or more, particularly 30°C or more, and even more preferably 50°C or more. Olefin-based resins are preferably used for the low-melting-point resin layer 21L, and polyethylene-based resins are particularly suitable. Polyamide-based resins and polyester-based resins are preferably used for the high-melting-point resin layer 21H, and polyamide-based resins are particularly suitable. Because polyethylene and polyamide have low adhesive properties, an adhesive resin layer or adhesive layer such as modified polyethylene may be provided between the layers, resulting in a polyethylene-based resin layer/adhesive resin layer (adhesive layer)/polyamide layer/adhesive resin layer (adhesive layer)/polyethylene-based resin layer structure.

The greatest feature of the soundproofing sheet of the present invention is that a release agent is partially applied to the surface of the above-mentioned thermoplastic resin sheet that will be bonded to the sound-absorbing layer. In the soundproofing sheet 1 of Figure 1, a release agent 22 is partially applied to the surface of the thermoplastic resin sheet 21 that faces the sound-absorbing layer 3. On the surface β of the release agent 22, the sound-insulating layer 2 and the sound-absorbing layer 3 are not fused together but are separated. In the present invention, the area to which the release agent 22 is applied is controlled, and the area of the adhesive portion α is controlled. The relationship between the adhesive area (fused area) between the sound-insulating layer 2 and the sound-absorbing layer 3 and sound-proofing properties (transmission loss and sound absorption coefficient) is as explained in detail in Patent Document 2.

As the release agent, for example, in addition to a silicone resin-based release agent, a non-silicone resin-based release agent such as an alkyd resin-based, olefin resin-based, acrylic-based, long-chain alkyl group-containing compound-based, or rubber-based release agent can be used. However, in order to reliably prevent the sound-insulating layer from fusing to the sound-absorbing layer, a release agent made of a silicone resin and/or a silicone-modified resin is particularly preferred.
Silicone resin-based release agents have a polysiloxane structure as their basic structure, and can be silicone resins or modified silicone resins in which organic groups have been introduced into at least one of their side chains and terminals. Silicone-modified resins are resins whose basic structure is a structure other than the polysiloxane structure and have polysiloxane groups in part of their molecules. Examples of thermoplastic resins that constitute silicone-modified resins include acrylic resins, polyurethane resins, polyester resins, epoxy resins, polyacetal resins, polycarbonate resins, and polyimide resins. Among these, acrylic resins, polyurethane resins, polyester resins, and polyacetal resins, with acrylic resins being particularly preferred.

<Sound absorbing layer>
The sound absorbing layer of the present invention comprises a fiber sheet and/or a porous material.
Examples of materials for the fiber sheet include glass wool, rock wool, polypropylene fiber, polyester fiber, and fiber waste. High-density polyester fiber is more preferred. The fibers preferably have a diameter of 1 mm or less. More preferably, they have a diameter of 25 μm or less. In the case of ultrafine fibers, the number of fibers per unit volume increases, thereby improving sound absorption performance. The meltblown manufacturing method, in which molten resin is extruded through pores under pressure to form fibers, produces ultrafine fibers on the order of several microns, resulting in a fibrous body with high sound absorption performance. Furthermore, one type of fiber diameter may be used alone, or two or more types may be used in combination. Furthermore, one type of fiber material may be used alone, or two or more types may be mixed and used in combination.

Examples of porous materials include polyurethane foam, polyethylene propylene diene rubber foam, polystyrene foam, polyethylene foam, polyimide foam, phenol foam, and melamine foam. Melamine foam is more preferred. The density of the foam is preferably 0.5 g/ ^cm3 or less, and more preferably 0.01 g/ ^cm3 or less. A single material of these materials may be used as the sound absorbing layer, or two or more types may be laminated or mixed together. When melamine foam and polyethylene propylene diene rubber foam are laminated together, the sound absorption characteristics are improved due to the significant differences in the densities and elastic moduli of the two materials.

The soundproof sheet 1 in Figure 1 has a two-layer structure consisting of a sound-insulating layer 2 and a sound-absorbing layer 3. However, the soundproof sheet of the present invention may also be formed by laminating a sound-insulating layer 2' on top of the soundproof sheet 1, as shown in Figure 2. In this case, the position and area of the release agent 22 on one sound-insulating layer 2 do not have to match the position and area of the release agent 22' on the other sound-insulating layer 2'. Because the sound-insulating layer itself deforms to attenuate sound vibrations, the presence of multiple sound-insulating layers can more reliably attenuate sound vibrations. The soundproof sheet of the present invention may also have three or more sound-insulating layers.

Figure 3 is a schematic cross-sectional view showing another embodiment of the soundproof sheet of the present invention. While the soundproof sheet 1 of Figure 1 has a sound-absorbing layer on only one side of the sound-insulating layer 2, the soundproof sheet of the present invention may also have a three-layer structure of sound-absorbing layer 13/sound-insulating layer 12/sound-absorbing layer 13', as shown in Figure 3. The soundproof sheet 11, which has a three-layer structure of sound-absorbing layer 13/sound-insulating layer 12/sound-absorbing layer 13', has better soundproofing performance than the soundproof sheet 1, which has a two-layer structure.

<Method of manufacturing soundproof sheet>
The soundproof sheet of the present invention is characterized by comprising: (1) a coating step of partially coating a release agent on at least one surface of a thermoplastic resin sheet; and (2) a lamination step of overlaying a fiber sheet and/or a porous material on the coated surface of the thermoplastic resin sheet, melting the surface of the thermoplastic resin sheet, and fusing the thermoplastic resin sheet to the fiber sheet and/or the porous material.

(1) Coating Step Prior to the coating step, a thermoplastic resin sheet is prepared. The method for producing the sheet is not particularly limited, and a conventionally known method can be appropriately adopted. For example, in the case of a three-layer thermoplastic resin sheet having the above-mentioned low-melting-point resin layer/high-melting-point resin layer/low-melting-point resin layer in this order, the low-melting-point resin and the high-melting-point resin can be supplied to separate extruders and produced using an inflation co-extrusion method, a T-die co-extrusion method, or the like.
In the coating process of the present invention, a release agent is applied to the surface of a thermoplastic resin sheet. This application can be performed using, for example, a flexographic printer or a gravure printer. While the amount of release agent applied is not particularly limited, it is desirable to apply the release agent so that the film thickness after drying is approximately 0.1 to 10 μm, particularly 0.5 to 5 μm, and even more particularly 1.25 to 3 μm. The size and shape of the release agent can be appropriately determined so that the adhesive area is the desired ratio, such as in a mesh pattern (A), dot pattern (B), or square pattern (C), as shown in FIG. 5 . It is preferable to apply the release agent so that the non-adhesive portion β is not concentrated in one area. The width x of the release agent-coated portion (non-adhesive portions β1 to β3) can be appropriately determined taking into account sound insulation properties, and can be, for example, 1 cm to 10 cm.

(2) Lamination Step Next, a sound-absorbing layer made of a fiber sheet and/or a porous material is integrated with the thermoplastic resin sheet (sound-insulating layer) partially coated with a release agent produced in the coating step. Specifically, the thermoplastic resin sheet (sound-insulating layer) and the sound-absorbing layer made of a fiber sheet and/or a porous material are preheated and then integrated by cold press molding. By performing cold press molding after preheating, the surface of the thermoplastic resin sheet melts, and the release agent penetrates into the voids in the sound-absorbing layer except in the areas coated with the release agent, thereby completing the soundproof sheet of the present invention. The preheating temperature condition may be set to a temperature sufficient to melt the surface of the thermoplastic resin sheet, and the surface may be set to about 90 to 180°C, particularly about 100 to 160°C.

<Dash silencer>
The soundproof sheet of the present invention can be used as a dash silencer that is disposed along the dash panel that separates the engine compartment from the passenger compartment in an automobile, etc. Noise propagating from the engine compartment passes through the dash panel, is absorbed by the sound-absorbing material, and is insulated by the sound-insulating layer, thereby suppressing its propagation into the passenger compartment.
From the standpoint of soundproofing, it is desirable that a two-layer soundproof sheet, such as soundproof sheet 1 shown in Fig. 1, consisting of sound-insulating layer 2 and sound-absorbing layer 3, be disposed so that sound-absorbing layer 3 faces the dash panel side and sound-insulating layer 2 faces the passenger compartment side. Also, it is desirable that a three-layer soundproof sheet 11, consisting of sound-absorbing layer 13, sound-insulating layer 12 and sound-absorbing layer 13', as shown in Fig. 3, be disposed so that the side of sound-insulating layer 12 printed with release agent 122 (the sound-absorbing layer 13' side) faces the passenger compartment side, and the side not printed with release agent 122 (the sound-absorbing layer 13 side) faces the engine compartment side.
Furthermore, the soundproof sheet of the present invention can be used as a dash silencer for automobiles, and can also be laid on the floor (floor mat), ceiling, etc. of a vehicle interior to absorb noise and make the interior of the vehicle quieter.

[Example 1]
A release agent (DYPC S-110) made of a silicone-modified acrylic resin manufactured by Toyo Ink Co., Ltd. is applied to a 460 mm wide area on the central surface of a three-layer thermoplastic resin sheet (width 1000 mm, thickness 50 μm) made of a polyethylene resin layer/polyamide resin layer/polyethylene resin layer to obtain a sound-insulating layer.
Next, two sound absorbing layers (10 mm thick) made of felt were prepared, and the sound insulating layer and the two sound absorbing layers were preheated to 110°C with hot air, and then cold pressed to form a soundproof sheet consisting of a sound absorbing layer/sound insulating layer/sound absorbing layer.
The obtained soundproof sheet was cut and the cross section was examined. It was found that the soundproof layer was fused to the sound absorbing layer except for the area where the release agent was applied.

[Example 2]
A sound-insulating layer was formed by applying a release agent made of an acrylic resin to the central surface of a thermoplastic resin sheet similar to that of Example 1 so that the average film thickness after drying would be 1.29 μm. Subsequently, a soundproof sheet consisting of a sound-absorbing layer/sound-insulating layer/sound-absorbing layer was formed in the same manner as in Example 1.
The obtained soundproof sheet was cut and the cross section was examined. It was found that the soundproof layer was fused to the sound absorbing layer except for the area where the release agent was applied.

[Example 3]
A soundproof sheet was formed in the same manner as in Example 2, except that the release agent was applied so that the average film thickness after drying would be 1.04 μm.
The obtained soundproof sheet was cut and the cross section was examined. A few areas were found where the release agent coated area and the sound absorbing layer were slightly fused together, but in most areas where the release agent was coated the sound insulating layer and the sound absorbing layer were not fused together, and in other areas the sound insulating layer was fused to the sound absorbing layer.

1, 11 Soundproof sheet 2, 12 Sound insulating layer 21, 121 Thermoplastic resin sheet 22, 122 Release agent 3, 13, 13' Sound absorbing layer α Adhesion portion β Non-adhesion portion

Claims (5)

A soundproof sheet comprising a sound-insulating layer made of a thermoplastic resin sheet and a sound-absorbing layer made of a fiber sheet and/or a porous material,
the thermoplastic sheet has a surface that is bonded to the sound absorbing layer and is made of an olefin resin;
a surface of the thermoplastic resin sheet to be bonded to the sound absorbing layer side is partially coated with a release agent made of a silicone resin and/or a silicone-modified resin ;
the sound-insulating layer is fused to the sound-absorbing layer on the surface on which the release agent is applied, except for the portion on which the release agent is applied ,
A soundproof sheet characterized in that the film thickness after drying of the release agent is 1.04 μm or more and 10 μm or less . A soundproof sheet in which a sound-insulating layer made of a thermoplastic resin sheet and a sound-absorbing layer made of a fiber sheet and/or a porous material are laminated in the order of sound-absorbing layer/sound-insulating layer/sound-absorbing layer,
the thermoplastic resin sheet has a surface that is bonded to the sound absorbing layer and is made of an olefin resin;
a release agent made of a silicone resin and/or a silicone-modified resin is partially coated on at least one surface of the thermoplastic resin sheet;
the sound-insulating layer is fused to the sound-absorbing layer except for the portion coated with the release agent ,
A soundproof sheet characterized in that the film thickness after drying of the release agent is 1.04 μm or more and 10 μm or less . 3. The soundproof sheet according to claim 1 , wherein the thermoplastic resin sheet is a multi-layer sheet having a low-melting point resin layer, a high-melting point resin layer and a low-melting point resin layer in this order. a coating step of partially coating a release agent on at least one surface of the thermoplastic resin sheet;
a lamination step of overlaying a fiber sheet and/or a porous material on the coated surface of the thermoplastic resin sheet and melting the surface of the thermoplastic resin sheet to fuse the thermoplastic resin sheet to the fiber sheet and/or the porous material;
4. The method for manufacturing a soundproof sheet according to claim 1 , further comprising: A vehicle dash silencer, comprising the soundproof sheet according to any one of claims 1 to 3 .