JPH04232735A - Sound-absorbing material and preparation thereof - Google Patents

Abstract

PURPOSE:To prevent the entry of noise into a room from an apparatus or the outside and to easily arrange a sound-absorbing material in a narrow passage by preparing said material by forming an air permeable elastic film to the surface of block-shape soft foamed polyurethane. CONSTITUTION:An air permeable elastic film 2 composed of a thermal adhesive resin is formed to the surface of block-shape soft foamed polyurethane 1. Foamed polyurethane is cut into a predetermined shape, for example, a trigonal prism shape with a dimension of a=b=15cm, c=20cm and d=23cm as shown by a drawing and the elastic film composed of a film forming material such as natural rubber, synthetic rubber or a thermoplastic elastomer is formed to the surface of said polyurethane. The 100% modulus of the elastic film is pref. 10-200kg/cm<2> and the thickness thereof is pref. 10-120mum.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound absorbing material, and more particularly to a sound absorbing material suitable for preventing noise from equipment or the outside world from entering a room through various ventilation channels.

0002

[Prior Art] Conventionally, various types of passenger cars have interior openings for the purpose of indoor heating, cooling, ventilation, etc., and various ventilation paths or pipes are formed that are connected to the outside world or various devices. . There is a problem in that noise from various devices or the outside world enters the room through these pipes. In recent years, as passenger cars have become significantly more luxurious, the above-mentioned noise problem has become an even more important problem. A common method to solve the above noise problem is to fill the air passages with blocks of foamed polyurethane, but such foamed polyurethane is very soft and has many pores on its surface, so There is a problem that the strength is low and broken pieces can enter the room. Furthermore, if such a polyurethane block is filled into a pipe, it may become misaligned due to vibrations when a car is running.
In order to suppress this positional shift, it is conceivable to fix the block with adhesive or the like, but it is not acceptable in terms of workability to actually carry out such an operation inside the pipe.

0003

[Problems to be Solved by the Invention] Therefore, it is an object of the present invention to be suitable for preventing equipment or external noise from entering a room through various ventilation ducts, It is an object of the present invention to provide a sound absorbing material that is easy to install.

0004

[Means for Solving the Problems] The above object is achieved by the following present invention. That is, the present invention provides a sound absorbing material characterized by comprising a block-shaped soft polyurethane foam and a breathable elastic coating provided on the surface thereof, an elastic coating is formed on the surface of a releasable base material, and the elastic coating is blocked. A method of manufacturing a sound absorbing material is characterized in that the sound absorbing material is transferred onto the surface of a soft foamed polyurethane, and a sound absorbing material is characterized in that the sound absorbing material is compressed and reduced and the reduced body is housed in a container.

[0005]

[Operation] A block-shaped flexible polyurethane foam with a breathable elastic coating formed on its surface can easily reduce its volume by compression. Of course, bare polyurethane foam without a breathable coating will shrink as well. If the reduced body according to the present invention is left to stand, it will restore its original volume in several tens of seconds to several minutes. In contrast, bare polyurethane foam instantly restores its original volume. In the present invention, the time required for the restoration can be used for the work of installing the sound absorbing material in a narrow space. According to the invention, therefore:
By forming a flexible, breathable elastic coating on the surface of a polyurethane foam, the strength of the polyurethane foam can be improved and the brittleness of the surface can be eliminated. In addition, by adjusting the air permeability of the above-mentioned air-permeable film to an appropriate range,
By adjusting the time for the reduced body to restore its original volume, the reduced body can be easily loaded into a predetermined narrow area, and the reduced body will restore its volume by simply leaving it as is. At this time, by designing the diameter of the completely restored body to be several percent to several tens of percent larger than the diameter of the pipe into which it is to be charged, the foam that has been restored by the pressure of the restoring force will be firmly fixed in place, and the No displacement occurs due to vibrations, etc.

[0006]

[Preferred Embodiments] Next, the present invention will be explained in more detail by citing preferred embodiments. The sound absorbing material of the present invention is a block of any shape as shown in FIG. 1, and its A-
As shown in cross section A, a breathable elastic coating 2 is formed on the surface of a block-shaped flexible polyurethane foam 1. Another sound absorbing material of the present invention is obtained by compressing and reducing the above sound absorbing material and housing the reduced body 3 in a container 4, as shown in FIG. The foamed polyurethane used in the present invention is a flexible foamed polyurethane that has been widely used in cushioning materials, mattresses, heat insulation materials, soundproofing materials, etc. In the present invention, any of these known foamed polyurethanes can be used.

In the present invention, foamed polyurethane, which is easily available on the market, is cut into a predetermined shape. The example shown in FIG. 1 is cut into a triangular prism shape with a = b = 15 cm, c = 20 cm, and d = 12 cm, and a breathable elastic coating 2 is formed on the surface of the triangular prism. The elastic coating may be formed from any elastic material that can be formed into a coating, such as natural rubber, synthetic rubber, thermoplastic elastomer, thermosetting elastomer, etc. However, from the viewpoint of various physical properties of the coating, polyurethane, polyurea, or Poly(urethane-urea) thermoplastic or thermosetting elastomers are preferred. In addition, the elastic coating formed above has a
% modulus is preferably in the range of 10 to 200 Kg/cm2; if this value is too high, the softness will be insufficient and the sound absorption will deteriorate.
Workability, feel, etc. are unsatisfactory, and on the other hand, if it is too low, the strength of the film is unsatisfactory and it becomes sticky, which is undesirable.

A preferred method for forming an elastic coating on the surface of a block-shaped flexible polyurethane foam from the above-mentioned elastic material includes, for example, (a) forming a separate appropriate coating from the elastic material and bonding this coating to the block surface; (b) forming a film by coating or spraying a solution or emulsion of an elastic material on the surface of the block, and later applying needles as needed; An example of this method is to provide ventilation holes. The method (a) above is useful when the block-shaped flexible polyurethane foam has a polygonal shape consisting of planes as shown in FIG.
The above method (b) is useful when the block-shaped flexible polyurethane foam has a curved shape such as a sphere or a donut shape.

To explain the above method (a) in more detail, as a method for forming an elastic film, as schematically shown in FIG. Apply to form a film (epidermis) 2,
Furthermore, an adhesive layer (or adhesive layer) 6 is formed on the surface. The releasable base material 5 is polyester film, polypropylene film, release paper, etc. If the surface of these releasable base materials is smooth, a glossy elastic film will be formed, but on the other hand, a matte film will be formed. If desired, a matte releasable base material may be used. The thickness of the epidermis is 5-40μ
About m is preferable. The adhesive layer may be a known heat-sealable adhesive such as acrylic, polyester, polyvinyl acetate, polyurethane, or polyamide, or a one-component or two-component adhesive such as acrylic, epoxy, or urethane. Adhesives such as acrylic, silicone, etc. can be arbitrarily used, and polyurethane-based heat-sealable adhesives are preferred in view of workability, elastic coating, adhesion to foamed polyurethane blocks, flexibility, etc. The thickness of these adhesive layers is 5
The thickness is about 80 μm, and the thickness of the entire elastic coating (skin + adhesive layer) is preferably about 10 to 120 μm. If the thickness of the elastic coating is less than 10 μm, the strength of the coating will be insufficient, while if it exceeds 120 μm, it will be uneconomical.

[0010] When the adhesive layer is a heat-sealable adhesive, the softening temperature of the adhesive layer is 100 to 150°C.
In this case, the skin preferably has a softening point that is 10°C or more higher than the softening point of the adhesive layer.
If the softening points of the adhesive layer and the skin are too close to each other, it is not preferable because workability decreases when an elastic coating is thermally bonded to a block-shaped flexible polyurethane foam. Note that the formation of the adhesive layer 6 is not essential in the above, and if the elastic coating 2 is thermally adhesive, the elastic coating can be directly transferred to the block-shaped urethane foam using the thermal adhesiveness. .

As described above, the elastic coating attached to the surface of the block-shaped flexible polyurethane foam is required to be breathable. Air permeability can be determined by punching or using a needle to provide a large number of holes in the coating before it is transferred to the surface of the block-shaped soft polyurethane foam, or by punching as many holes as necessary with a needle after transferring the coating to the block-shaped flexible polyurethane foam surface. It may be provided with holes or may be made breathable by other methods. The degree of air permeability can be arbitrarily adjusted by the size and number of holes, and in the present invention, preferable air permeability is in the range of 10 to 400 seconds when expressed in terms of recovery time (defined later). If the restoration time exceeds the above range, it will take time to compress and reduce the sound absorbing material, and it will also take too much time to restore it. On the other hand, if the restoration time is too short, reduction is easy, but restoration is too quick and workability is insufficient.

The elastic coating may be transferred to the foamed polyurethane block by any conventional method. For example, when transferring an elastic coating to the surface of the foamed polyurethane block shown in Figure 1,
As shown in FIG. 4, the releasable base material on which the elastic coating is formed is cut, preferably to a size somewhat larger than one plane of the block 1, and the back side of the releasable base material is placed on a hot plate or the like. are layered and heated to activate the adhesive layer, press-bond the surface of the foamed polyurethane block on that surface, and then peel off the releasable base material. By repeating this operation, the elastic coating can be transferred to the entire surface of the polygonal polyurethane foam block.

In another embodiment of the present invention, the sound absorbing material obtained above is compressed and reduced and stored in a container having a certain degree of strength. Then, if necessary, take out the reduced body,
This is inserted into a predetermined position within a narrow tube, and after a while the reduced body returns to its original volume, so that the restored body is fixed at a desired position within the tube. In this case, by designing the size of the restoration body to be several percent to several tens of percent larger than the space in which it is fixed, the foam can be firmly placed inside the pipe because a restoring force is always acting at the installation location. It is fixed and will not shift.

[0014]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples. It should be noted that unless otherwise specified, the terms in the text or % are based on weight.

Example 1 Polyurethane resin solution (Lethermin ME-3612LP,
100% modulus 60Kg/cm2, softening temperature 140
50 parts of methyl ethyl ketone was added to 100 parts (solid content: 30%, manufactured by Dainichiseika Chemical Industry Co., Ltd.) and mixed uniformly with a mixer to obtain a polyurethane paint. Apply this paint to release paper (EV13)
0TA-7, made by Lintec) as a paint on the surface.
g/m2 for 5 minutes at 60°C and 130°C.
The film was dried for 20 minutes to form a film with a thickness of 50 μm. This film was placed on a hot plate (not shown) whose temperature was adjusted to 150°C as shown in Figure 4, one side of the foamed polyurethane block in the shape of Figure 1 was adhered, and the foamed polyurethane block was lightly pressed for 30 seconds. It was taken out and the release paper 5 was peeled off. This operation was repeated a total of five times to transfer the polyurethane film to the entire surface of the block. Next, use 2 needles with a sharp tip and a diameter of 1 mm in the center.
Ventilation holes were formed at various ratios on five sides using a device in which four holes were fixed at cm intervals to obtain the sound absorbing material of the present invention as shown in Table 1 below. The restoring time was defined as the time required to manually compress the sound absorbing material to 1/3 of its volume, leave it to stand, and restore it to 90% or more of its volume (the same applies hereinafter).

Table 1 Sample restoration time A
Approximately 1 secondB
Approximately 7 seconds C
Approximately 31 seconds D Approximately 7
8 seconds E approximately 100 seconds F
Approximately 126 seconds G
Approximately 250 seconds H
The blocks of samples A to B, which lasted approximately 500 seconds, were easy to reduce, but were restored too quickly, resulting in insufficient workability. On the other hand, the block of sample H took too much time to reduce and restore, and the workability was similarly insufficient. In addition, the blocks of Examples C to G above were compressed and reduced to 1/4 and filled into a steel container (the internal volume is the same as the compressed and reduced body), and after 3 days, the blocks were taken out from the container and placed in a container with a side of 10 cm. When the block was manually inserted into the corner of a rectangular pipe made of vinyl chloride, the block was completely fixed to the corner of the pipe after 5 minutes and did not shift even when subjected to strong vibrations.

Example 2 Polyurethane urea resin solution (Lethermin NE-5904
, 100% modulus 95Kg/cm2, softening temperature 17
0°C, Dainichiseika Kogyo Co., Ltd., solid content 25%) to 100 parts, add 10 parts of isopropyl alcohol and 15 parts of toluene,
A polyurethane urea paint was obtained by uniformly mixing with a mixer. This paint was applied as a paint on the surface of release paper (EV130TP (R2), manufactured by Lintec) at a rate of 100 g/m2, dried at 60°C for 3 minutes and at 120°C for 5 minutes,
A film with a thickness of 20 μm was formed. Furthermore, on top of that, a polyurethane resin heat sealing agent solution (LEZAMIN ME88N
Add 20 parts of methyl ethyl ketone to 100 parts of FLP, 100% modulus 30Kg/cm2, softening temperature 115℃, manufactured by Dainichiseika Chemical Industry, solid content 30%), mix uniformly with a mixer to create a polyurethane paint, and add this paint. 2 as a paint on the surface of the above polyurethane polyurea film.
00 g/m2 and heated at 60°C for 3 minutes and 12
It was dried at 0° C. for 10 minutes to form a heat sealant film with a thickness of 50 μm. This film was placed on a hot plate whose temperature was adjusted to 135°C, and the curved surface of a cylindrical polyurethane foam (diameter 60 mm x height 200 mm) was rolled slowly while being lightly pressed to adhere it, and then removed from the hot plate. The release paper was peeled off. Furthermore, in the same manner as in Example 1, a film was transferred to the bottom and top surfaces, and a polyurethane coating was transferred to the entire surface of the block. Next, use a 2cm needle with a sharp tip and a 1mm thick center.
Ventilation holes were formed at various ratios on three sides using a device in which four holes were fixed at intervals to obtain the sound absorbing material of the present invention as shown in Table 2 below.

Table 2 Sample restoration time A
Approximately 1 secondB
Approximately 8 seconds C
Approximately 35 seconds D
Approximately 69 seconds E approximately 130
Second F Approximately 120 seconds G
Approximately 300 seconds H
Approximately 480 seconds

Although the blocks of samples A to B were easy to reduce, they were restored too quickly and had insufficient workability. On the other hand, the block of sample H took too much time to reduce and restore, and the workability was similarly insufficient. In addition, the blocks of Examples C to G above were compressed and reduced to 1/4 and filled into a steel container (the internal volume is the same as the compressed and reduced body), and after 7 days, the blocks were taken out from the container and chlorinated with a diameter of 50 mm. When the block was inserted into a vinyl tube using a rod, it was completely fixed inside the tube after 6 minutes and did not shift even when subjected to strong vibrations. In the above, 100% modulus is determined by cutting a film formed to a thickness of 30 to 50 μm into 6 cm long and 1.5 cm wide, peeling the film from release paper, and using Shimadzu Autograph AG.
- Using 500A, crosshead speed 200mm
/min. , chart speed 100mm/min. ,
Measurement was performed using a tensile strength/elongation curve at a measurement temperature of 25°C. To measure the softening temperature, the same film as above was prepared, one side of the film was fixed, and 450 g/g was added to the other side.
A load of cm2 was applied, the temperature was set in a gear oven, and the temperature was increased at a rate of 2°C/min. The temperature at which the film was cut was taken as the softening point. Further, in the above embodiments, the shape of the foamed polyurethane block may be any shape such as a columnar shape, a spherical shape, an ellipsoidal shape, a rectangular parallelepiped, etc., and is not particularly limited as long as it matches the shape of the place where it is filled.

[0020]

[Effects] According to the present invention as described above, it is suitable for preventing equipment or external noise from entering a room through various ventilation channels, etc., and can be easily installed in narrow ventilation channels. It is possible to provide a sound absorbing material that is

[0021]

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the sound absorbing material of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG. 1;

FIG. 3 is a diagram showing an example of the sound absorbing material of the present invention in a contracted state.

FIG. 4 is a diagram schematically explaining the method of the present invention.

[Explanation of symbols]

1: Polyurethane block 2: Elastic coating 3: Reduced field 4: Container 5: Releaseable base material 6: Adhesive layer

Claims (11)

[Claims] 1. A sound absorbing material comprising a block-shaped flexible polyurethane foam and a breathable elastic coating provided on its surface. 2. The sound absorbing material according to claim 1, wherein the elastic coating is made of polyurethane, polyurea or poly(urethane-urea). 3. The sound absorbing material according to claim 1, wherein the elastic coating is made of a thermoadhesive resin. 4. The sound absorbing material according to claim 1, wherein the elastic coating has a multilayer structure including a skin and an adhesive layer. 5. The sound absorbing material according to claim 4, wherein the adhesive layer is a heat-sealable adhesive, and the difference in softening point between the skin and the adhesive layer is 10° C. or more. 6. The sound absorbing material according to claim 1, wherein the elastic coating has a thickness of 10 to 120 μm. Claim 7: The 100% modulus of the elastic coating is 10.
The sound absorbing material according to claim 1, wherein the sound absorbing material has a weight of 200 Kg/cm2. 8. The sound absorbing material according to claim 1, wherein the restoration time is in the range of 10 to 400 seconds. 9. Forming an elastic coating on the surface of the releasable base material,
A method for producing a sound absorbing material, which comprises transferring the elastic coating onto the surface of a block-shaped soft polyurethane foam. 10. The method for producing a sound absorbing material according to claim 9, wherein vent holes are provided in the elastic coating before or after the transfer. 11. A sound absorbing material, characterized in that the sound absorbing material according to claim 1 is compressed and reduced, and the reduced body is housed in a container.