JP3296984B2 - Automotive sound insulation sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention has an object to shield and reduce unpleasant vibrations and noises transmitted to a passenger compartment from an engine, a tire, and the like, and to improve comfort in the passenger compartment. To a sound insulating sheet for automobiles.

[0002]

2. Description of the Related Art Improvements in the structural design of an automobile body, such as measures to increase the rigidity of the body, have been made in order to improve the livability in the passenger compartment of the automobile. On the other hand, in order to further improve comfort, sound-absorbing materials and vibration-damping materials have been used, and sound insulation sheets for shielding and reducing vibration and noise have been used. In particular, in recent years, the quietness of the passenger compartment has been greatly emphasized as part of the improvement in the performance of automobiles, and the use site of the sound insulation sheet and the amount of use per vehicle have been greatly increased.

As shown in FIG. 2, the sound insulating sheet 9 is provided in a dash panel 53 between the engine room 51 and the front of the passenger compartment 52, a passenger compartment floor 54 and a ceiling, a room partition between the trunk room and the rear of the passenger compartment, and the like. It is attached. In addition, the sound insulation sheet 9 can be used alone or as shown in FIG.
As shown in the figure, there is a case where the laminated body with the felt 95 is attached on the vehicle body steel plate 96. In addition, felt 95
Instead, non-woven fabric, foam, carpet, etc. may be used. In any case, the sound insulation sheet
Pressing under heating or drawing by vacuum is performed in advance in order to closely adhere to the shape of the attachment portion.

Conventionally, as such a sound insulating sheet 9,
A PVC-based sound insulating sheet having a composition in which a soft vinyl chloride resin (PVC) and an inorganic filler such as calcium carbonate or barium sulfate are combined has been used. This PVC-based sound insulating sheet is obtained by forming a mixture of the above composition into a sheet by a method such as a calender roll molding method or a T-die extrusion molding method.

[0005]

However, the above-mentioned conventional sound insulating sheets for automobiles have the following problems. That is, the function of the sound insulation sheet is to block sound waves in the propagation path, and a sheet having a large transmission loss is preferable.
The transmission loss is largely governed by the areal density (mass of the material), and the greater the areal density, the better the sound insulation. Further, the reduction in sound insulation due to the resonance phenomenon occurring in the high frequency range is related to the rigidity of the material, and a material having a low elastic modulus, that is, a material having a high flexibility is preferable.

On the other hand, in the conventional PVC-based sound insulating sheet, PVC (including a plasticizer) is added in an amount of 30% by weight or more due to the limit of formability such as drawing aptitude to a shape suitable for the above-mentioned attachment portion. There is a need. That is, the addition amount of the inorganic filler is 70% by weight or less. Therefore, the specific gravity of the PVC sound insulating sheet is as low as 2.5 g / cm ³ or less. Therefore, in order to increase the surface density, it is necessary to increase the thickness of the sheet, which leads to a decrease in moldability and an increase in molding cost.

In order to increase the areal density, it is effective to use metal powder having a large true specific gravity as an inorganic filler. However, in the case of a PVC sound insulation sheet,
At the time of kneading at a high temperature in the production process, there is a problem that hydrogen chloride generated by partial thermal decomposition of PVC and a metal powder in the inorganic filler cause a chemical reaction to generate gas.

Further, the PVC-based sound insulating sheet has a problem that a large amount of harmful and corrosive hydrogen chloride gas is generated at the time of disposal and incineration, which leads to environmental pollution. In addition, even during recycling, there is a problem that compatibility with a large amount of olefin-based resin generated from various kinds of automobile parts is poor, and it is difficult to recycle.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a sound insulating sheet for automobiles having high surface density, high flexibility, excellent sound insulation, and excellent moldability and recyclability. It is something to offer.

[0010]

A first aspect of the present invention is an amorphous poly-α.
2 to 20% by weight of olefin and 0 to
20% by weight and a high specific gravity filler of 60 to 98% by weight . The ethylene resin is a binary random copolymer of ethylene and propylene, butene-1, hexane-1 or octene-1. Or a ternary random copolymer containing ethylene, propylene and a diene compound , and
The content of ethylene is 50 to 90 wt%, the specific gravity of the high specific gravity filler Ri der 5.0 g / cm ³ or more, the non
The crystalline poly-α-olefins are 60-99% by weight propylene.
1 to 40% by weight of ethylene and / or butene
-1 is copolymerized at random in a sound insulating sheet for automobiles.

The above-mentioned amorphous poly-α-olefin is prepared by, for example, subjecting ethylene or butene-1 to liquefied propylene under a hydrogen atmosphere in the presence of a catalyst comprising a titanium-supported catalyst supported on magnesium chloride and triethylaluminum. It can be produced by a polymerization method such as introduction of propylene, and is obtained by randomly copolymerizing 60 to 99% by weight of propylene and 1 to 40% by weight of ethylene and / or butene-1. The polymer has a degree of 10% or less in the DSC method and is very low in crystallinity as compared with a normal olefin resin. This amorphous poly-α ole
As the fin, for example, UT3 manufactured by Ube Lexen described later
385 etc. This amorphous poly-α-olefin has a melt viscosity at a temperature of 190 ° C. of 300 to 30,0.
It is in the range of 00 centipoise.

When the content of ethylene and / or butene-1 contained in the amorphous poly-α-olefin exceeds 40% by weight, the surface tackiness of the amorphous poly-α-olefin increases. However, there is a problem that blocking of the sound insulation sheet becomes remarkable. On the other hand, ethylene and / or
Or, when the content of butene-1 is less than 1% by weight,
There is a problem that the flexibility and elasticity of the sound insulation sheet are reduced.

The compounding ratio of the amorphous poly-α-olefin is 2 to 20% by weight as described above. When the amount is less than 2% by weight, there is a problem that the kneading work of the compound or the sheet forming becomes difficult and the flexibility of the sound insulating sheet is reduced, and preferably 3% by weight or more. on the other hand,
When the content exceeds 20% by weight, the mechanical properties of the sound insulating sheet are not adversely affected at all, but there is a problem that the specific gravity of the sound insulating sheet cannot be increased, and preferably 10% by weight or less.

The above-mentioned ethylene resin is a binary random copolymer of ethylene and propylene, butene-1, hexane-1 or octene-1, or a ternary random copolymer containing ethylene, propylene and a diene compound. And the ethylene content is 50-90% by weight. Also,
This ethylene resin has a temperature of 190 ° C. and 2.16 K
The melt index (MI) under a load of g is
It is in the range of 0.1 to 10.

The mixing ratio of the ethylene resin is, as described above, from 0 to 20% by weight. That is, the above-mentioned ethylene resin is not added, or is added in a range of 20% by weight or less. On the other hand, when the content exceeds 20% by weight, there is a problem that the melt viscosity of the compound is extremely increased and the moldability is reduced, and preferably 10% by weight or less.

Next, the high specific gravity filler has a higher specific gravity than a normal inorganic filler such as calcium carbonate, and more specifically, has a true specific gravity of 5.0 g / cm ³ or more. Metal powders such as iron, copper or lead, oxide powders such as zinc, antimony, iron or zirconium, and titanium or tungsten carbide powders. Among them, iron powder containing iron oxide produced especially from steelmaking slag has a true specific gravity of about 6.5 g / cm ^3, which is preferable from the viewpoint of increasing the specific gravity and economical efficiency.

The average particle size of the high specific gravity filler is 5 to 50.
It is preferably in the range of 0 μm. If it is less than 5 μm, there is a problem that the melt viscosity of the compound increases and molding processing becomes difficult, and more preferably 10 μm or more. On the other hand, when the thickness exceeds 500 μm, there is a problem that skin roughness occurs on the surface of the sound insulating sheet and the appearance becomes poor, and more preferably 100 μm or less.

The compounding ratio of the high specific gravity filler is 60 to 98% by weight as described above. When the amount is less than 60% by weight, the mechanical properties of the sound insulating sheet are not adversely affected at all, but there is a problem that it is difficult to achieve a high specific gravity, and preferably 80% by weight or more. On the other hand, 98
If it exceeds 10% by weight, the melt viscosity of the compound increases,
There is a problem that the forming process becomes difficult and the flexibility and strength of the sound insulating sheet are reduced.
The following is good.

In the present invention, a crystalline olefin resin may be added to the composition. The crystalline olefin resin referred to here is the melt index (MI)
Is in the range of 0.1 to 100, for example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) or high density polyethylene (HDP).
E) or a homo, block or random type polypropylene.

The compounding ratio of the crystalline olefin resin is 0.1.
2-5% by weight is preferred. If it is less than 0.2% by weight, there is a problem that the strength of the sound insulating sheet is reduced, and more preferably 0.5% by weight or more. On the other hand, if it exceeds 5% by weight, there is a problem that the flexibility of the sound insulating sheet is inferior, and more preferably 2.5% by weight or less.

Further, in the present invention, additives such as an antiblocking agent and a coloring agent may be appropriately added to the composition.
The anti-adhesive agent reduces the blocking property of the surface of the sound insulating sheet, and silicone oil, stearic acid and derivatives thereof can be used. As a coloring agent, any coloring pigment and dye can be used directly or as a master batch. A general sound insulating sheet is black, and in this case, carbon black is used in the form of a master batch.

Next, a procedure for manufacturing a sound insulating sheet using the above resins and a high specific gravity filler will be briefly described. First, the amorphous poly-α-olefin, ethylene resin,
And a high specific gravity filler, and additives such as an antiblocking agent and a coloring agent, which are added as necessary, are uniformly mixed by a mixer to obtain a molten compound. The mixer in this case includes a Henschen mixer, a Banbury mixer and the like.

Next, the above-mentioned molten compound is formed into a sheet by a calender roll method or a T-die extrusion method to obtain a sound insulating sheet. In addition, the obtained sound insulation sheet is formed into a desired shape suitable for the place where the sound insulation sheet is provided, for example, by drawing under heating or by forming by a stamping mold method.

Next, the operation of the present invention will be described. As described above, the sound insulating sheet of the present invention contains the amorphous poly-α-olefin, the ethylene-based resin, and the high specific gravity filler in the above specific ratio. Therefore, it is possible to improve the sound insulation by improving the surface density and the flexibility while maintaining excellent moldability. That is, since the high specific gravity filler is contained in the above specific ratio, the specific gravity of the sound insulating sheet can be made sufficiently higher than before. Therefore, the surface density can be increased without increasing the thickness of the sound insulation sheet as compared with the conventional case, and the sound insulation can be improved.

As the resins, amorphous poly-α-olefin and ethylene resin are used in the above-mentioned specific ratio. Therefore, even when the high specific gravity filler is added in a relatively large amount in the above ratio, excellent flexibility and moldability can be maintained. Further, the sound insulating sheet of the present invention generates less harmful gas when incinerated for disposal and is effective in preventing environmental destruction. Further, even during recycling, it has excellent compatibility with a large amount of olefin-based resin generated from various automobile parts and the like, and can be easily recycled.

Next, it is preferable that the high-specific-gravity filler is iron powder containing iron oxide. The iron powder in this case is produced, for example, from steelmaking slag, as described above, and has a true specific gravity of about 6.5 g / cm ³ and is relatively inexpensive. Therefore, the specific gravity of the sound insulating sheet can be easily increased, and the economy is excellent.

Further, as in the third aspect of the present invention, it is preferable that the sound insulating sheet for an automobile has a specific gravity of 3 g / cm ³ or more. That is, the specific gravity of the sound insulating sheet is adjusted to 3 g / cm ³ by adjusting the type and amount of the high specific gravity filler.
It is preferable to make the above. Thereby, the areal density can be easily further increased. The upper limit of the specific gravity of the sound insulating sheet is 5.8 g / cm ³ when the above-mentioned iron powder having a true specific gravity of 6.5 g / cm ³ is used.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 An automotive sound insulating sheet according to an embodiment of the present invention will be described with reference to Table 1 and FIG. In this example,
As shown in Table 1, the amorphous poly-α-olefins
A sound insulating sheet (E1 to E3) of the present invention containing 0% by weight, 0 to 20% by weight of an ethylene-based resin, and 60 to 98% by weight of a high specific gravity filler, exceeding the above mixing range. Comparative sound insulation sheets (C1 to C3) were prepared and various performances were compared. As shown in FIG. 1, the sound insulating sheet 1 of this embodiment is used, for example, as a laminate with a felt 95, and is attached to a vehicle body steel plate 96.

First, the production of the sound insulation sheet was performed as follows. Amorphous poly-α-olefin ( UT3 Lexen UT3
385 or less, APAO), ethylene-based resin (ethylene-propylene rubber EP931 manufactured by Japan Synthetic Rubber)
Table 1 shows PR), crystalline olefin-based resin (random polypropylene B221 or less made by Grand Polymer, PP), and high specific gravity filler (iron powder containing iron oxide "BUS" or less made by Kokuyo Sangyo). The mixture was blended at a predetermined ratio, and the mixture was stirred and mixed at a temperature of 200 ° C. for 15 minutes using a kneader to obtain a mixed blend. Next, the mixed compound was formed into a sheet having a thickness of 2 mm by hot pressing at 200 ° C.

Next, as shown in Table 1, performance evaluation items related to evaluation of physical properties such as melt viscosity (MFR at 230 ° C.), tensile strength, specific gravity, surface hardness, and sound insulation performance. Sound insulation performance, - sound source side of the reverberation box at the sound insulation box of "reverberation box anechoic box method", as the sound receiving side the anechoic box, the felt side between the two sound source, the sound barrier sheet to the sound receiving side So that the sound pressure level difference is measured and the "high pressure level-1/3 octave frequency" is output by the frequency analyzer.
The average sound pressure level between 250 Hz and 2000 Hz was evaluated as a sound insulation volume.

Table 1 shows the performance evaluation results. As can be seen from Table 1, the products of the present invention (E1 to E3) exhibited stable and good MFR regardless of the amount of iron powder. The tensile strength, specific gravity, and surface hardness slightly changed in proportion to the amount of the iron powder, but all were within a good range and were good.

On the other hand, the comparative product C1 has EPR and P
Since P was not contained at all, the MFR was extremely large, and it was difficult to form a sheet into a sound insulating sheet. In addition, since the comparative product C2 does not contain APAO, the tensile strength becomes extremely high, and the melt viscosity (MF
R) was very small, and it was difficult to form a sound insulating sheet. The comparative product C3 is E
Since it did not contain PR, it exhibited the drawback that, similarly to C2, the tensile strength was extremely high, the elastic modulus was very large, and the flexibility required for a sound insulating sheet was lacking.

As shown in Table 1, the products of the present invention (E1 to E3) were all excellent in sound insulation performance due to the difference in the above physical properties.

[0034]

[Table 1]

[0035]

As described above, according to the present invention, it is possible to provide a sound insulating sheet for automobiles which is excellent in sound insulating property and excellent in workability and recyclability.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a usage mode of an automotive sound insulating sheet according to a first embodiment.

FIG. 2 is an explanatory view showing a place where a sound insulating sheet for automobiles is attached in a conventional example.

FIG. 3 is an explanatory view showing a usage form of a conventional sound insulating sheet for automobiles.

[Explanation of symbols]

 1. . . Automotive sound insulation sheet, 95. . . Felt, 96. . . Car body steel plate,

Continuation of the front page (56) References JP-A-8-208900 (JP, A) JP-A-57-135861 (JP, A) JP-A-53-1273 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) C08L 23/00-23/36 C08K 3/00-13/08 B60R 13/08

Claims (3)

(57) [Claims] An amorphous poly-α-olefin is used in an amount of 2 to 20 weights.
%, And 0 to 20% by weight of ethylene resin.
60-98% by weight filler,  The above ethylene resins are ethylene and propylene, butene
-1, binary random of hexane-1 or octene-1
Copolymer, or ethylene, propylene and diene compound
Is a ternary random copolymer containingContaining ethylene
The weight is 50-90% by weight,  The specific gravity of the high specific gravity filler is 5.0 g / cm.^ThreeIs over
, The amorphous poly-α-olefin comprises 60-99% by weight.
Propylene with 1 to 40% by weight ethylene and / or
Butene-1 randomly copolymerized That is
Characteristic sound insulation sheet for automobiles. 2. The sound insulating sheet according to claim 1, wherein the high specific gravity filler is iron powder containing iron oxide. 3. The sound insulating sheet for an automobile according to claim 1, wherein the specific gravity of the sound insulating sheet for an automobile is 3 g / cm ³ or more.