JPH04136015A - Sound insulating material - Google Patents

Abstract

PURPOSE:To provide a sound insulating material excellent in sound insulating properties, moldability, etc., by using, as the main material, a polyurethane elastomer obtd. by the polyaddition reaction of a specific polyol with an arom. polyisocyanate. CONSTITUTION:A polyurethane elastomer is prepd. by the polyaddition reaction of a polyol comprising a copolymer of polypropylene glycol and polyethylene glycol and having a functionality of 2-3 and an OH value of 100mgKOH/g or lower with an arom. polyisocyanate having a functionality of 2 or higher (e.g. diphenylmethane diisocyanate) in a mold. The elastomer, if necessary having beer compounded with fillers, plasticizers, etc., is used as the main material for the title material having a Young's modulus lower than 1.5X10<6>N/m<2> (20 deg.C). The material having a complicated shape can be prepd. in a short time by reaction injection molding.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to all fields including building materials, including veneer sound insulating materials or sandwich structure sound insulating materials, which are acoustically called mass pack restraint systems. , high weight layer (
This relates to sound insulating materials used in parts called "Heavy 1 ayer". A particularly good example is one used in the heavy layer of sandwich structure soundproofing materials used in the interiors of vehicles, aircraft, ships, etc., mainly to insulate sound from power engines, motors, etc. be.

[Prior Art] Conventionally, the material used for these heavy layers is EPDM.
%EVA%PVC, rarely polyurethane elastomer, etc., filled with barium sulfate, calcium carbonate, etc. in an amount of about 80% by weight or less is used. These are first formed into a sheet shape, then heated and vacuum- or pressure-formed into a shape that can be attached to a vehicle body or the like.

[Problems to be Solved by the Invention] Conventional sound insulation materials are relatively inexpensive and have been widely used for sound insulation in automobiles and the like. However, in recent years, with the increasing trend toward luxury cars, there has been a demand for quieter interiors than ever before, leading to a demand for sound insulation materials with higher performance.

Therefore, in order to develop sound insulation materials with higher performance, the present inventors investigated the various properties of conventional sound insulation materials and found that, in general, the sound insulation properties of sound insulation materials are better when the Young's modulus of the material is lower. did. The reason for this is expected to be related to the fact that the sound speed C is expressed by the following equation and is a function of the elastic modulus of the propagating material.

K: Modulus of elasticity of the propagating substance ρ: Density of the propagating substance ρ Also, the resonant frequency f where the sound waves and the vibration of the sound insulating material itself resonate and the sound insulating effect decreases. is expressed as (t: thickness of sound insulation material), but by lowering Young's modulus, the resonance frequency f. This seems to be related to the fact that it can be made higher than the practical range of several kilohertz or less. In response to this phenomenon, the sound insulation materials actually used, for example, heavy layers of sandwich structures, are non-foamed or non-porous.
Even a soft elastomer has a Young's modulus of 1.5
At present, it is 106 N/m2 (20° C.) or more, and it has been difficult to reduce it to less than this. In other words, the Young's modulus of the material conventionally used for the heavy layer is 1.5X106N/m2.
(20° C.) or lower is that a material with a low Young's modulus, inexpensive, easy to mold, and excellent in performance other than soundproofing could not be obtained.

Furthermore, in vehicles, aircraft, ships, etc., the Young's modulus of the heavy layer of soundproofing material installed near the power engines and motors has to be increased to an even higher level because of the heat generated by these power sources. This is because the heavy weight layer softens or melts, causing various problems. For example, the Young's modulus of common elastomers such as nitrile rubber (NBR), butadiene rubber (BR), and ethylene propylene rubber (EPDM) is approximately 3 x 106 N/m2 (at 20°C).
This level is higher than that of the present invention.

Silicone rubber can achieve a Young's modulus of 105 N/m2 (20°C) and does not significantly soften or melt at temperatures below 100°C, but it is very expensive and is a material with somewhat inferior soundproofing effects. Polynorbornene bum, which is difficult to replace even if it is inexpensive and has a high areal density, has a Young's modulus of 1.5 x 106 N/m2 (20°C) or less by blending a large amount of oil. Although this can be achieved, it is not preferable because it requires a lot of processing energy for vulcanization and molding at 160° C. for 10 minutes or more.

In addition, soundproofing materials for vehicle engine noise must be heat resistant to approximately 90°C, even inside the vehicle interior near the engine, but the EPDM that is currently widely used tends to soften and change its shape, causing various problems. Since this easily occurs, it is not possible to further lower the elastic modulus by adding a plasticizer or the like. The melting point of polyvinyl chloride is as high as 200 to 210°C, and by adding several tens of percent of a plasticizer such as dioctyl phthalate, a Young's modulus of 107 N/m2 (20°C) can be obtained.
Problems such as plasticizer migration may occur.

Therefore, the present invention makes it possible to obtain a molded product with a low Young's modulus without worrying about softening due to heat or migration of plasticizer,
Another object of the present invention is to propose a sound insulating material that has a much higher sound insulating effect than those of the prior art and is easy to form acid.

[Means for Solving Problem S] The feature of the present invention for achieving the above-mentioned object is that it is a copolymer of polypropylene glycol and polyethylene creel, has a functional group number of 2 to 3, and an OH value of 100 mg.
A polyurethane elastomer whose main constituent material is a polyurethane elastomer obtained by polyaddition reaction of a polyol of KOH/g or less and an aromatic polyisocyanate having a functional group number of 2 or more in a mold, and whose Young's modulus is less than 1°5 × 106 N/m2 (20°C). The feature lies in the sound insulation material. As the aromatic polyisocyanate, polyphenylene polymethyl isocyanate, diphenylmethane diisocyanate, carbonimide-modified diphenylmethane diisocyanate, and tolylene diisocyanate may be used alone or in an appropriate mixture thereof. Further, it is preferable to use a tertiary amine catalyst for the polyaddition reaction.

The sound insulation material of the present invention has an ether bond C<-C-O-C-) bond in its main chain, which has a low rotational barrier energy (-C-C-C-) bond in a polymer as a polyol. A copolymer of polypropylene glycol and polyethylene glycol having an OH value of 100 mgKOH/g or less and having 2 to 3 functional groups is used. In addition, without using the chain extender used in boat fishing polyurethane elastomer or Ft1M polyurethane, it is possible to use a chemical equivalent of polyphenylene polymethyl isocyanate or aromatic polyester such as diphenylmethane diisocyanate in the vicinity of NC01ndexlQQ by the action of a tertiary amine catalyst. By performing a polyaddition reaction with isocyanate at room temperature in the mold,
105N/m2 (2
An ultra-soft polyurethane elastomer sound insulation material with a Young's modulus of 0°C) can be obtained. Of course, after making a prepolymer by adding a part of it in advance, in-mold hevoriol,
It is also possible to adopt a method of injecting polyisocyanate.

Incidentally, the polyurethane elastomer may contain various fillers as extenders, plasticizers for adjusting hardness, and the like. The sound transmission loss of the polyurethane elastomer is approximately 2 to 3 dB higher over the entire frequency range of 200 to 6000 Hz than the conventional product when the areal density is the same.

Furthermore, by optimizing the type and amount of the tertiary amine catalyst, the polyurethane elastomer can be demolded from the mold within about a few minutes at around room temperature using a reaction injection molding machine.

Note that this polyurethane elastomer is different from polyurethane elastomers currently used. That is, polyurethane elastomers currently in use generally require a temperature of about 100° C. and a curing time of 3 to 24 hours for molding.

Further, the Young's modulus is generally 107 N/m2 (20° C.), which is higher than that of the present invention.

This is because the applications for which polyurethane elastomers are currently being used require the high abrasion resistance that is characteristic of polyurethane. Unlike those of the present invention, these polyurethane elastomers also commonly use chain extenders such as 1,4-butadiol, 3,3°-dichloro-4,4°cyamodiphenylmethane, and prepolymers.

It should be noted that the polyurethane elastomers according to the invention also differ from those of the type currently commonly made by reaction injection molding (RIM). These current RIM polyurethanes generally have a Young's modulus of 3 x 108 N/m2 (20°C)
It is a hard material with the above level and is generally used in automobile bumpers, but it also belongs to the category of rigid polyurethane foam.

Hereinafter, specific examples and comparative examples of the present invention will be described.

[Example] Copolymer of polypropylene glycol and polyethylene glycol (number of functional groups = 2, OH value: 28 mgkOH/
g Asahi Glass Exceltor 510)
63 parts by weight, 20 parts by weight of calcium carbonate, 2 parts by weight of triethylene diamine (Sankyo Products), polyphenylene polymethyl diisocyanate (viscosity:
200eps; 20℃, N00%: 31 MD Kasei)
By subjecting 5 parts by weight to a polyaddition reaction in a mold at 23°C, the area density was 3.8 kg/m2 and the thickness was 4.5 kg/m2. (
lnmc7) A Boliu 1/Tan elastomer sheet was obtained. The Young's modulus of the obtained polyurethane elastomer is shown in Table 1.
It was like that. Further, when the sound transmission loss of the Otoso intensity was measured by a method similar to JIS-A-1416, the results shown in FIG. 1 were obtained.

[Comparative Example] - 11 parts by weight of ethylene propylene, 7 parts by weight of ethylene vinegar and rubber, 78 parts by weight of calcium carbonate, 7 parts by weight of oil, and 2 parts by weight of adhesive were mixed and molded using a calendar molding machine to give an areal density of 3° 8 kg.
A sheet having a thickness of 20 mm and a thickness of 20 mm was obtained. The Young's modulus of the obtained rubber was as shown in Table 1. Further, when the sound transmission loss was measured using the same method as in the example, the results were as shown in FIG. 1.

This result shows that the general noise range is from several tens of Hz to several kHz.
It is understood that the sound insulation material of the present invention has a better sound insulation effect than the comparative example in most of z.

According to the graph in Fig. 1, the sound insulation material of this example has a sound insulation effect inferior to that of the conventional technology in the sound range exceeding 3 kHz, but when the sound insulation material of the present invention is used as a sound insulation material for the engine room of an automobile, The @ sound of the ζ engine is tkt (
Since the range is below z, there is no problem at all.

Table [Effects] The sound insulation material of the present invention has a Young's modulus of 1.5×10”N/m
2, and the sound insulation effect is excellent in most of the noise range of boat fishing. In addition, complex shapes that can be molded by reaction injection molding can be molded in a short time, resulting in high mass productivity.

[Brief explanation of drawings]

FIG. 1 is a graph showing the effect of a sound insulation material according to a specific example of the present invention. Patent applicant Mitsuboshi Belting Co., Ltd.

Claims (1)

[Claims] 1. A copolymer of polypropylene glycol and polyethylene glycol, having a functional group number of 2 to 3 and an OH value of 100.
The main constituent material is a polyurethane elastomer obtained by polyaddition reaction of a polyol of mgKOH/g or less and an aromatic polyisocyanate with a functional group number of 2 or more in a mold, and the Young's modulus is 1.5 × 10^6 N/m^2 ( 20°C) or less. 2. The sound insulation material according to claim 1, wherein a part of the polyol and the aromatic polyisocyanate are subjected to a polyaddition reaction to form a prepolymer before being injected into the mold. 3. The sound insulation material according to claim 1 or 2, wherein the aromatic polyisocyanate is a single substance selected from polyphenylene polymethyl isocyanate, diphenylmethane diisocyanate, carbonimide-modified diphenylmethane diisocyanate, and tolylene diisocyanate, or a mixture thereof.