JP2015102593A - Sound absorption material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sound absorption material capable of exhibiting sufficient sound absorption performance even with light-weight and small thickness, and requiring no complex configuration or no complex manufacturing process.SOLUTION: A thermoplastic resin film, an adhesive agent layer, and nonwoven cloth are laminated in this order to obtain sound absorption material.

Description

  The present invention relates to a sound absorbing material.

  In living environments such as houses and offices and transportation means such as airplanes and automobiles, it is desired to provide a quiet internal environment that blocks external noise. For this reason, sound-absorbing materials made of foams such as polyurethane foam and polyethylene foam containing an air layer, and fibrous materials such as felt and nonwoven fabric are widely used. In particular, transportation means such as automobiles are required to have a sound absorbing material that is lighter in weight and excellent in sound absorbing performance.

Conventionally, the use of a melt-blown nonwoven fabric, a needle punched nonwoven fabric, or the like has been studied as a sound-absorbing material using a nonwoven fabric. Further, it has been proposed to further improve sound absorbing performance by laminating non-woven fabrics having different densities and structures using these non-woven fabrics, or laminating with a skin material. For example, in Patent Document 1, the air flow rate measured based on JIS L-1096 is 50 cc / cm with a nonwoven fabric having a basis weight of 150 to 800 g / m ² and a bulk density of 0.01 to 0.2 g / cm ^3. There has been proposed a sound absorbing material having a configuration in which a skin material (specifically, a spunbonded nonwoven fabric) of ² / sec or less is laminated. According to the technique described in Patent Document 1, characteristics suitable for use in vehicles such as automobiles in particular, that is, good sound absorption, and good flame retardancy without containing a flame retardant are obtained. It is said that there is no dripping of the liquid melt at the time of melting the constituent fibers, low shrinkage, and excellent safety, economy and recyclability.

International Publication No. 2005/019783 Pamphlet

  However, when trying to exhibit high sound absorption performance using the technique described in Patent Document 1, a certain amount of weight and thickness are required. As described above, there is still a strong demand for further reducing the weight and volume of the sound-absorbing material, especially considering the case where it is used for a vehicle such as an automobile.

  The present invention has been made in view of the above-described state of the art in the prior art, and is capable of exhibiting sufficient sound absorbing performance even with a light weight and a small thickness, and does not require a complicated configuration or a complicated manufacturing process. The purpose is to provide materials.

  The present inventor has intensively studied to solve the above problems. As a result, it has been found that the above problems can be solved by a laminate constituted by arranging a thermoplastic resin film and a nonwoven fabric via an adhesive layer, and has completed the present invention.

  That is, according to one aspect of the present invention, there is provided a sound absorbing material in which a thermoplastic resin film, an adhesive layer, and a nonwoven fabric are laminated in this order.

  ADVANTAGE OF THE INVENTION According to this invention, the sound-absorbing material which can exhibit sufficient sound-absorbing performance with a light weight and small thickness, and does not require a complicated structure or a complicated manufacturing process can be provided.

It is sectional drawing of the sound-absorbing material which concerns on one Embodiment of this invention. It is a top view of the sound-absorbing material which concerns on one Embodiment of this invention. It is an enlarged plan view of a sound absorbing material according to an embodiment of the present invention. It is a graph which shows the result of having measured the normal incidence sound absorption coefficient about the sound-absorbing material of Examples 1-3 and the comparative example 1. FIG. It is a graph which shows the result of having measured normal incidence sound absorption rate about the sound-absorbing material of Examples 4-7 and Comparative Example 1. FIG. It is a graph which shows the result of having measured normal incidence sound absorption coefficient about the sound-absorbing material of Examples 8-9 and Example 6. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the dimension ratio of drawing is exaggerated on account of description, and may differ from an actual ratio.

  According to one aspect of the present invention, there is provided a sound absorbing material in which a thermoplastic resin film, an adhesive layer, and a nonwoven fabric are laminated in this order.

  FIG. 1 is a cross-sectional view of a sound absorbing material according to an embodiment of the present invention. As shown in FIG. 1, the sound absorbing material 10 first has a thermoplastic resin film 11. An adhesive layer 12 is laminated on the thermoplastic resin film 11. And in the sound-absorbing material 10 of this embodiment, the nonwoven fabric 13 is further laminated | stacked on the surface on the opposite side to the thermoplastic resin film 11 of the adhesive bond layer 12. FIG.

[Thermoplastic resin film]
In the form shown in FIG. 1, the thermoplastic resin film 11 functions as a skin material of the sound absorbing material 10. However, in some cases, another layer may be further disposed on the surface of the thermoplastic resin film 11 opposite to the adhesive layer 12.

  The constituent material of the thermoplastic resin film 11 is not particularly limited. For example, low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolymer. Polyolefin such as polypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, Polyolefin resins such as ethylene-butene copolymer and ethylene-hexene copolymer; Polyester resins such as polyurethane, polyethylene terephthalate, and polyethylene naphthalate; (Meth) acrylic polymers, polystyrene, polycarbonate Over DOO, polyimide, polyamide, polyamideimide, polyetherimide, polysulfone, polyether sulfone, polyvinyl chloride, polyvinylidene chloride, fluorine resins, films made of cellulose resins and thermoplastic resins such as a cross-linked product thereof. These thermoplastic resins may be used by blending several kinds as required. Of these, polyethylene terephthalate or polypropylene is preferable from the viewpoint of sound absorption, and polyethylene terephthalate is more preferable.

  Although there is no restriction | limiting in particular also about the thickness of the thermoplastic resin film 11, Preferably it is 5-100 micrometers, More preferably, it is 5-25 micrometers, More preferably, it is 5-15 micrometers. If the thickness of the thermoplastic resin film 11 is within such a range, it is possible to exhibit at least a sound absorbing performance equivalent to this even with a sound absorbing material having a smaller thickness compared to the prior art. There is an advantage.

  In addition, the thermoplastic resin film 11 can contain various additives in addition to the thermoplastic resin. Examples of the additive include a plasticizer as a softening component. In addition to the plasticizer, a flame retardant, a colorant, an antistatic agent, and an ultraviolet ray collecting agent can be used.

[Adhesive layer]
(adhesive)
The adhesive layer 12 includes an adhesive (not shown). In the present specification, the term “adhesive” includes a pressure-sensitive adhesive.

  Specific examples of the adhesive contained in the adhesive layer 12 include an acrylic adhesive, a silicone adhesive, a rubber adhesive, a vinyl ether adhesive, and a polyurethane adhesive. These adhesives may be either solvent type or emulsion type. Among these, acrylic adhesives include n-butyl (meth) acrylate, hexyl (meth) acrylate, isooctyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, (meth) acrylic acid 2 -Copolymerization with one or more of (meth) acrylates such as ethylhexyl, decyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, and such (meth) acrylates Possible (meth) acrylic acid, itaconic acid, maleic acid, maleic anhydride, hydroxyethyl acrylate, hydroxypropyl acrylate, acrylamide, dimethylacrylamide, methylaminoethyl methacrylate, methoxyethyl (meth) acrylate, etc. Examples include copolymers with monomers. Specific examples of the silicone-based adhesive include those composed of a mixture and / or polymer of dimethylsiloxane gum and dimethylsiloxane resin. Specific examples of the rubber-based adhesive include synthetic rubbers such as styrene-isoprene-styrene block copolymer rubber, styrene-butadiene rubber, polybutene rubber, butyl rubber, and natural rubber as main components. Specific examples of the vinyl ether adhesive include ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether and the like. Specific examples of polyurethane adhesives include polyester polyols, polycarbonate polyols, polyether polyols, acrylic polyols, and polyurethane polyols as main components and polyfunctional polyisocyanates as crosslinking agents.

  Among these adhesives, acrylic pressure-sensitive adhesives are preferable in that they can be bonded to a non-woven fabric having a small bonding area and difficult to apply pressure at a low pressure and without requiring heat curing. .

  These adhesives need to be a thin and uniform layer, and are formed by diluting with water or an organic solvent, coating and drying.

  The thickness of the adhesive layer 12 is usually in the range of 1 to 100 μm, and preferably in the range of 5 to 30 μm.

[Nonwoven fabric]
As the nonwoven fabric 13 used in this embodiment, a nonwoven fabric conventionally used as a constituent material of a sound absorbing material can be used as appropriate. For example, the nonwoven fabric may be either a nonwoven fabric composed of short fibers or a nonwoven fabric composed of long fibers. Specifically, a needle punch nonwoven fabric, a water jet punch nonwoven fabric, a melt blown nonwoven fabric, a spunbond nonwoven fabric, a stitch bond nonwoven fabric, or the like is used. Especially, a needle punch nonwoven fabric or a water jet punch nonwoven fabric is preferable, and a needle punch nonwoven fabric is especially preferable. Miscellaneous felts can also be used as the nonwoven fabric.

  In the present invention, the fibers constituting the nonwoven fabric may be natural fibers or synthetic fibers, but synthetic fibers are preferably used from the viewpoint of durability. Examples of such fibers include thermoplastic fibers such as polyester fibers, polyamide fibers (for example, nylon fibers), acrylic fibers, polyolefin fibers (for example, polypropylene fibers, polyethylene fibers, etc.). Those produced according to a known method such as dry spinning or melt spinning can be used. Among these, polyester fiber, polypropylene fiber, and nylon fiber are preferable from the viewpoint of excellent durability and wear resistance. In particular, polyester fibers are most preferable because the raw material polyester can be easily recycled by heat melting of the used nonwoven fabric, is excellent in economic efficiency, has a good texture of the nonwoven fabric, and is excellent in moldability. Some or all of these thermoplastic fibers may be bristles (collected recycled fibers). In particular, recycled fibers that have been collected and recycled once used in the vehicle can be suitably used.

  In the present embodiment, the thicker the nonwoven fabric 13 is, the thicker the sound absorbing property is. However, from the viewpoints of economy, ease of handling, space securing as a sound absorbing material, etc., the thickness is preferably 1 to 50 mm, more preferably 2 to 2. It is 20 mm, More preferably, it is 2-10 mm.

Moreover, although there is no restriction | limiting in particular about the fabric weight of the nonwoven fabric 13, From a viewpoint that thickness is small, Preferably it is 80-1000 g / m < ² >, More preferably, it is 100-600 g / m < ² >, More preferably, it is 100. ˜300 g / m ² .

[Method for producing sound absorbing material]
There is no restriction | limiting in particular about the manufacturing method of the sound-absorbing material 10 which concerns on this form, A conventionally well-known knowledge can be referred suitably. For example, a technique in which a sheet in which the adhesive layer 12 is disposed on one surface of the thermoplastic resin film 11 and a nonwoven fabric are continuously bonded via a pressure roll or the like can be used.

  The operational effects achieved by the configuration according to the present embodiment provide a sound-absorbing material that can exhibit sufficient sound-absorbing performance even with a light and small thickness, and does not require a complicated configuration or a complicated manufacturing process. It is to be done. Here, although the mechanism in which such an effect is exhibited by the configuration according to this embodiment is not completely clear, a part of the sound wave incident from the thermoplastic resin film 11 side is reflected and partly Is attenuated by the vibration of the thermoplastic resin film 11, and the rest is propagated to the nonwoven fabric through the adhesive layer and is considered to be attenuated as the vibration of the nonwoven fabric. However, the technical scope of the present invention is not limited by such a mechanism.

[Preferred embodiment]
FIG. 2 is a plan view (a plan view corresponding to FIG. 1) of the sound absorbing material according to the embodiment of the present invention. As shown in FIGS. 1 and 2, the sound absorbing material 10 according to the present embodiment is provided with an opening 14 that penetrates the thermoplastic resin film 11 and the adhesive layer 12. And this opening hole 14 is a hole provided so that the thermoplastic resin film 11 and the adhesive bond layer 12 may be penetrated, and as long as the said definition is satisfy | filled, there is no restriction | limiting especially about the specific structure of the opening hole 14. Absent.

  By providing the opening hole 14 in the thermoplastic resin film 11 and the adhesive layer 12, the incident sound wave passes through the opening hole 14 and is absorbed by the nonwoven fabric 13. Of the sound waves that have passed through the opening hole 14, the sound that has not been absorbed by the nonwoven fabric 13 is reflected by the portion of the adhesive layer 12 where the opening hole 14 is not provided, and is again absorbed by the nonwoven fabric 13. When the opening 14 is not provided in the adhesive layer 12, the sound absorption effect by the nonwoven fabric 13 cannot be obtained.

  FIG. 3 is an enlarged plan view enlarging the plan view of the sound absorbing material 10 according to the embodiment of the present invention shown in FIG. As shown in FIGS. 2 and 3, the opening holes 14 are preferably provided regularly and periodically. According to such a form, productivity at the time of mass production can be remarkably improved. Although there is no restriction | limiting in particular also about the size and arrangement | positioning form of the opening hole 14, For example, the opening diameter (diameter; "D" shown in FIG. 3) of the opening hole 14 becomes like this. Preferably it is 100-700 micrometers, More preferably, 150 It is -500 micrometers, More preferably, it is 200-300 micrometers. If the opening diameter (diameter D) of the opening hole 14 is less than 100 μm, the incident sound wave cannot pass through the thermoplastic resin film 11, and if it exceeds 700 μm, the sound wave passing through the nonwoven fabric 13 is trapped and absorbed. Cannot be obtained. The opening diameter (diameter D) of the opening hole 14 is defined as the maximum of the distances between any two points on the contour line of the opening hole 14. When the diameters of the respective opening holes 14 are not the same, the opening diameter (diameter D) is calculated as an average value of the opening diameters (diameter D) of several tens of opening holes 14.

  Further, the distance between the centers of the opening holes 14 (pitch; “P” shown in FIG. 3) is preferably 2 to 20 mm, more preferably 2 to 10 mm, and further preferably 3 to 5 mm. If the distance (pitch P) between the opening holes 14 is less than 2 mm, the attenuation due to vibration of the thermoplastic resin film 11 decreases, and if it exceeds 20 mm, sound waves cannot pass through the nonwoven fabric 13 and a sufficient sound absorbing effect cannot be obtained. . The distance (pitch P) between the opening holes 14 is defined as the distance between the centers of two adjacent opening holes 14. When the distance between the centers (pitch P) is not the same due to the combination of two adjacent apertures 14, the distance (pitch P) between the centers of the apertures 14 is several tens of apertures 14. It is calculated as an average value of the distance between the centers (pitch P).

  In addition, as a method of forming an opening hole, a laser, a hot needle, a press, a drill, or electric discharge is mentioned.

  As mentioned above, although preferable embodiment of the sound-absorbing material which concerns on this invention was described, the sound-absorbing material which concerns on this invention is not necessarily limited only to embodiment mentioned above and illustrated embodiment, For example, it describes in patent document 1 Needless to say, modification by a conventionally known configuration may be added.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the technical scope of the present invention should be determined based on the description of the scope of claims, and should not be limited only to the following examples.

[Evaluation of sound absorption performance]
In the following examples and comparative examples, the sound absorbing performance of the sound absorbing material is evaluated according to JIS A1405-2: 2007 “Measurement of sound absorption coefficient and impedance by an acoustic tube—Part 2: Transfer function method” (ISO 10534-2: 1998). ) By measuring the normal incident sound absorption coefficient.

[Production of sound absorbing material]
Example 1
As a thermoplastic resin film, a polyethylene terephthalate (PET) film (thickness 6 μm) was prepared. On the other hand, a polyester needle punched nonwoven fabric having a basis weight of 100 g / m ² and a thickness of 2 mm was prepared.

  An acrylic adhesive as an adhesive was applied to one surface of the PET film prepared above to form an adhesive layer having a thickness of 20 μm. Next, the exposed surface of the adhesive layer was bonded to one surface of the nonwoven fabric prepared above. In this way, the sound absorbing material of this example was produced.

(Example 2)
A sound absorbing material of this example was produced by the same method as in Example 1 except that a PET film having a thickness of 12 μm was used.

(Example 3)
A sound absorbing material of this example was produced by the same method as in Example 1 except that a PET film having a thickness of 16 μm was used.

(Comparative Example 1)
A needle punched nonwoven fabric having a basis weight of 220 g / m ² and a thickness of 10 mm was prepared and used as a sound absorbing material of this comparative example as it was.

(Comparison between Examples 1 to 3 and Comparative Example 1)
The graph of FIG. 4 shows the results of measuring the normal incidence sound absorption coefficient for the sound absorbing materials of Examples 1 to 3 and Comparative Example 1 produced above.

  As shown in FIG. 4, it can be seen that the sound absorbing material of Examples 1 to 3 has an improved sound absorption rate with respect to a frequency of 2000 to 5000 Hz as compared with the sound absorbing material of Comparative Example 1.

Example 4
The sound-absorbing material of this example was produced by the same method as in Example 1 described above except that a needle punched nonwoven fabric having a basis weight of 200 g / m ² and a thickness of 10 mm was used as the nonwoven fabric.

(Example 5)
A sound absorbing material of this example was produced by the same method as in Example 4 described above except that a PET film having a thickness of 12 μm was used.

(Example 6)
A sound-absorbing material of this example was produced by the same method as in Example 4 described above except that a PET film having a thickness of 16 μm was used.

(Example 7)
A sound-absorbing material of this example was produced by the same method as in Example 4 described above, except that a PET film having a thickness of 25 μm was used.

(Contrast with Examples 4 to 7 and Comparative Example 1)
The graph of FIG. 5 shows the results of measuring the normal incidence sound absorption coefficient of the sound absorbing materials of Examples 4 to 7 and Comparative Example 1 produced above.

  As shown in FIG. 5, it can be seen that the sound absorbing materials of Examples 4 to 7 have an improved sound absorption rate with respect to a frequency of 1000 to 5000 Hz as compared with the sound absorbing material of Comparative Example 1. Moreover, it turns out that the dependence of the sound absorption performance with respect to the thickness of a thermoplastic resin film (PET film) lose | disappears by using the nonwoven fabric with a larger basis weight than Examples 1-3.

(Example 8)
With respect to the laminate after forming the adhesive layer on the surface of the PET film, an opening hole penetrating the laminate was formed by laser perforation. At this time, the opening diameter (diameter) of the opening holes was 300 μm, and the distance (pitch) between the centers of the opening holes was 3 mm.

  A sound-absorbing material of this example was produced by the same method as in Example 6 described above, except that the laminate having the opening holes formed as described above was bonded to the nonwoven fabric.

Example 9
A sound-absorbing material of this example was produced by the same method as in Example 8 except that the distance (pitch) between the centers of the opening holes was 5 mm.

(Comparison between Examples 8 to 9 and Example 6)
The graph of FIG. 6 shows the results of measuring the normal incidence sound absorption coefficient of the sound absorbing materials of Examples 8 to 9 and Example 6 produced above.

  As shown in FIG. 6, compared with the sound absorbing material of Example 6, in the sound absorbing materials of Examples 8 to 9, the peak of the sound absorption coefficient is shifted to the high frequency side, and particularly the sound absorbing performance at a frequency of 3000 Hz or more is remarkably increased. It turns out that it improves.

  From the results shown in the above Examples and Comparative Examples, according to the sound absorbing material according to the present invention, the conventional sound absorbing material can be obtained by a very simple method of attaching a thermoplastic resin film to the nonwoven fabric through an adhesive layer. It was shown that it is possible to achieve equivalent sound absorption performance despite being lighter in weight and smaller in thickness. In addition, as a preferred embodiment, it was also shown that the sound absorbing performance in a higher frequency region is further improved by providing (preferably, providing a large number of openings) through the thermoplastic resin film and the adhesive layer.

10 Sound absorbing material,
11 thermoplastic resin film,
12 Adhesive layer,
13 Nonwoven fabric,
14 opening hole,
D Opening diameter (diameter) of the opening hole,
P Distance (pitch) between the centers of the opening holes.

Claims (7)

A thermoplastic resin film;
An adhesive layer;
Non-woven fabric,
A sound-absorbing material that is laminated in this order.   The sound-absorbing material according to claim 1, wherein the thickness is 2 to 20 mm.   The sound-absorbing material according to claim 1 or 2, wherein an opening hole penetrating the thermoplastic resin film and the adhesive layer is formed.   The sound absorbing material according to claim 3, wherein the opening holes are regularly and periodically formed.   The sound-absorbing material according to claim 3 or 4, wherein an opening diameter (diameter) of the opening hole is 100 to 700 µm.   The sound-absorbing material according to any one of claims 3 to 5, wherein a distance (pitch) between the centers of the opening holes is 2 to 10 mm.   The sound-absorbing material according to any one of claims 1 to 6, wherein the thermoplastic resin constituting the thermoplastic resin film is polyethylene terephthalate or polypropylene.