JPH10251077A - Production of sound absorption material and sound absorption material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing method of a sound absorption material and the sound absorption material having high sound absorption property and high strength. SOLUTION: A foamable inorganic composition (A) slurry consisting of an Al2 O3 based inorganic powder, an alkali metal silicate, a foaming agent, water and a polysilloxane-poly-oxyalkylene copolymer and a foamable inorganic composition (B) containing an anionic surfactant except the polysiloxane-poly- oxyalkylene copolymer are laminated and casted. The laminated and casted foamable inorganic composition (A) and (B) are foamed and hardened. The skin layer of the inorganic foamed hardened material of the foamed and hardened foamable inorganic composition (A) is cut off.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sound absorbing material and a sound absorbing material, and more particularly to a method for producing a sound absorbing material having excellent sound absorbing properties and having high strength and useful for non-combustible civil engineering and building materials. About materials.

[0002]

2. Description of the Related Art Conventionally, inorganic foams have been widely used as non-combustible civil engineering and building materials because of their excellent light weight and heat insulation. However, these inorganic foams generally consist of closed cells, and their performance as a sound absorbing material is low and small. As the inorganic sound absorbing material, for example, Japanese Unexamined Patent Publication No. 5-85858 discloses a main material comprising a water-soluble alkali metal silicate, an inorganic solid component, and a filler, and a foaming agent such as an anionic surfactant and hydrogen peroxide. There is disclosed an inorganic foam having open cells which can be foamed and cured using the composition for an inorganic foam to be used for a sound absorbing material, a filter and the like.

However, the sound-absorbing material disclosed in Japanese Patent Application Laid-Open No. 5-85858 has a low density and a high air permeability of the foam in order to obtain high sound absorbing properties. There was a problem of doing it. For example, it is used for a large-area wall such as a soundproof wall of a highway or the like, and is generally washed with high-pressure washing water when removing dirt from the sound-absorbing material. When hitting the sound-absorbing material, the surface of the sound-absorbing material is ragged, so that there is a problem of tradeoff between sound absorbing property and strength.

In an attempt to achieve both the mechanical strength of the lightweight cellular concrete plate surface and various properties such as heat insulation and light weight, a lightweight cellular concrete plate having a specific gravity gradient in the thickness direction of the plate has been proposed. Manufacturing methods have been proposed. For example, Japanese Patent Application Laid-Open No. 8-208345 discloses a method for producing a lightweight cellular concrete plate having a specific gravity gradient by injecting a low specific gravity mortar slurry and a high specific gravity mortar slurry and performing form vibration.

[0005] However, in the method disclosed in Japanese Patent Application Laid-Open No. 8-208345, bubbles generated during foaming are partially crushed by the vibration of the mold, so that the specific gravity of the high specific gravity layer is 0.7 to 0.7.
Adjusted to about 1.3, the resulting lightweight cellular concrete board has low sound absorption characteristics, and it is not possible to manufacture a sound absorbing material by such a method.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and an object of the present invention is to provide a method of manufacturing a sound absorbing material having both high sound absorbing properties and strength, and a sound absorbing material. To provide.

[0007]

According to the first aspect of the present invention,
Al ₂ O ₃ -SiO ₂ system inorganic powders, alkali metal silicate, blowing agent, water and polysiloxane - effervescent mineral composition consisting of polyoxyalkylene copolymers (A) slurry and polysiloxane - polyoxyalkylene copolymer First step of laminating and casting a foamable inorganic composition (B) slurry containing an anionic surfactant other than a polymer, the above-described foamed inorganic compositions (A) and (B) laminated and cast ), And a third step of cutting off the skin layer of the foamed and cured foamed inorganic composition (A) of the inorganic foamed and cured foamed inorganic composition (A). Is the gist.

The curable inorganic material used in the present invention
The product (A) is (A) Al_TwoO_Three-SiO_TwoBased inorganic powder
Body, (a) alkali metal silicate, (c) blowing agent and
(D) a curable inorganic composition mainly composed of water,
(E) Polysiloxane-polyoxyalkylene copolymer
A surfactant for forming open cells is used. the above
(A) Al_TwoO_Three-SiO_TwoAs the inorganic powder,
l_TwoO_Three90 to 10% by weight, SiO_Two10-90% by weight
A powder having a composition consisting of Al of the above composition_TwoO
_Three-SiO_TwoAs the inorganic powder, for example, alumina
Dust, fly ash, and flour when producing abrasives
Classified and crushed products of iash, metakaolin, flyer
Powder obtained by melting and spraying air into the air, Al _TwoO
_Three-SiO_TwoMelt clay made of powder and spray it into the air
Powder obtained by_TwoO_Three-SiO_TwoMechanical to powder
50 to powder and clay mineral obtained by applying energy
Mechanical energy is applied to the powder obtained by heating at 0-900 ° C.
Can be used, but the composition and composition
If the particle size is selected, it is not limited to these.

The above (a) alkali metal silicates include:
General formula M ₂ O.nSiO ₂ (M = Li, K, Na or a mixture thereof, the value of n is preferably n = 0.05 to
8, more preferably n = 0.1 to 3). When the value of n of the alkali metal silicate exceeds 8, the alkali metal silicate aqueous solution is apt to gel,
Immediately the viscosity sharply rises, making it difficult to mix with other powders. If it is less than 0.05, the strength of the obtained open-cell foam decreases, so that the alkali metal silicate in the above range is used.

When the alkali metal silicate is mixed with other powder components to prepare a curable inorganic composition, it is preferable that the alkali metal silicate is added and mixed as an aqueous solution. The aqueous solution concentration of the alkali metal silicate is not particularly limited, but if the concentration is high, a viscosity suitable for foaming cannot be obtained,
If the concentration is low, the curing shrinkage of the obtained open-cell foam may increase or the strength may decrease.
60% by weight is preferred.

The amount of the alkali metal silicate to be added depends on the amount of the hydraulic inorganic substance 1 such as the Al ₂ O ₃ —SiO ₂ inorganic powder.
The amount is preferably 0.2 to 450 parts by weight, more preferably 10 to 350 parts by weight, per 100 parts by weight. When the addition amount of the alkali metal silicate is less than 0.2 parts by weight,
The resulting open-cell foam is poorly cured, and conversely, 45
If the amount exceeds 0 parts by weight, the water resistance of the obtained open-cell foam may be reduced.

The (c) foaming agent is not particularly limited, and examples thereof include peroxides and metal powders.

Examples of the peroxide-based foaming agent include:
Examples include hydrogen peroxide, sodium peroxide, potassium peroxide, sodium perborate and the like. The amount of the foaming agent composed of these peroxides is preferably 0.01 to 1 part by weight per 100 parts by weight of the hydraulic inorganic substance of the curable inorganic composition.
0 parts by weight. If the addition amount is less than 0.01 part by weight, bubbles are not sufficiently formed, and it is difficult to obtain a desired foam. There is.

When hydrogen peroxide is used as a foaming agent, it is preferable to use hydrogen peroxide in an aqueous solution. If the concentration of the aqueous solution is too high, foaming is severe and dangerous, and stable foaming becomes difficult. The viscosity is preferably 0.5 to 35% by weight, more preferably 1 to 25% by weight, since the viscosity of the curable inorganic composition decreases and stable foaming becomes difficult.

[0015] Examples of the metal powder-based foaming agent include:
Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Z
n, Al, Ga, Sn, Si, ferrosilicon and the like. If the average particle size of these metal powder-based foaming agents is too small, the dispersibility in the curable inorganic composition may be reduced, and if the dispersibility is good, the reactivity becomes high, and foaming may occur. Vigorous and stable foaming becomes difficult, and if it is too large, the reactivity decreases, and it may become difficult to obtain a desired foam.
It is. The addition amount of these metal powder-based foaming agents is based on 100 parts by weight of the hydraulic inorganic substance of the curable inorganic composition.
Preferably it is 0.01 to 5 parts by weight. If the addition amount is less than 0.01 part by weight, bubbles are not sufficiently formed, it is difficult to obtain a desired foam, and if it exceeds 5 parts by weight,
The foaming gas becomes excessive, and there is a possibility that a lot of foam breakage is generated.

The type and amount of these foaming agents are appropriately selected and set based on the specifications of the target product. However, cost, safety during use, easy availability, easy handling, and the like are comprehensive. In particular, hydrogen peroxide and aluminum powder are preferably used.

The water (d) contained in the curable inorganic composition includes a water-soluble inorganic material such as the Al ₂ O ₃ —SiO ₂ -based inorganic powder, including the water component in the aqueous alkali metal silicate solution. 35 to 1 parts by weight, preferably
500 parts by weight, more preferably 45 to 1000 parts by weight. When the water content increases, the viscosity of the curable inorganic composition decreases, the foaming process becomes unstable, and the strength of the obtained open-cell foam also decreases. Conversely, when the water content is low, the viscosity of the curable inorganic composition becomes too high, the foaming process becomes unstable, and high-magnification foaming,
A low-density open-cell foam cannot be obtained.

Furthermore, (e) a polysiloxane-polyoxyalkylene copolymer is added to the foamable inorganic composition (A) in the present invention. The above-mentioned polysiloxane-polyoxyalkylene copolymer is used for foaming the curable inorganic composition (A) to increase the cell diameter and to form a continuous-porous foam.
It is preferably 0.1 to 5 parts by weight based on 100 parts by weight of the hydraulic inorganic substance of the curable inorganic composition. When the addition amount is less than 0.1 part by weight, the cell diameter becomes small, the number of closed cells increases, and the airflow resistance increases, and when it exceeds 5 parts by weight, the strength of the obtained foam decreases. Since there is a possibility of being added, it is added in the above range, more preferably in the range of 1 to 3 parts by weight.

The foamable inorganic composition (B) containing an anionic surfactant other than the polysiloxane-polyoxyalkylene copolymer is a polysiloxane-polyoxyalkylene copolymer of the foamable inorganic composition (A). This is a foamable inorganic composition in which components other than coalescing are commonly used and an anionic surfactant is added thereto. Examples of the anionic surfactant include, but are not particularly limited to, alkali metal salts of fatty acids, alkyl sulfate salts, and alkylaryl sulfonate salts.

If the amount of the above-mentioned anionic surfactant is too large, the foaming power is increased, and the mechanical strength of the obtained open-cell foam is reduced. Since it is difficult to obtain a curable inorganic composition, the amount of the curable inorganic composition is preferably 0.1 to 100 parts by weight.
It is 0.5 to 5 parts by weight.

The curable inorganic composition may optionally contain an inorganic filler, a reinforcing fiber, a foaming aid, an inorganic foam, and the like. The inorganic filler is added for the purpose of improving the fluidity of the curable inorganic composition slurry, stabilizing bubbles during and after foaming, reducing shrinkage during curing of the obtained open-cell foam, and densifying cells. Is done.

Examples of the inorganic filler include porous inorganic materials such as silica sand, silica powder, fly ash, slag, silica fume, mica, talc, wollastonite, calcium carbonate, aerosil, silica gel, alumina gel, zeolite, and activated carbon. Powder.

The average particle size of the inorganic filler is preferably 0.01 μm to 1 mm. The average particle size is 0.0
If it is less than 1 μm, the viscosity of the curable inorganic composition increases due to an increase in the amount of adsorbed water, and there is a possibility that mixing workability may decrease or foaming may not be sufficiently performed. If it exceeds 1 mm, the stability of foaming will be impaired.

The amount of the inorganic filler to be added is preferably 20 to 600 parts by weight, more preferably 40 to 40 parts by weight, per 100 parts by weight of the hydraulic inorganic substance of the curable inorganic composition.
0 parts by weight. If the amount is less than 20 parts by weight, a sufficient effect cannot be obtained. If the amount exceeds 600 parts by weight, the strength of the obtained open-cell foam may be reduced.

The reinforcing fibers are added for the purpose of improving the strength of the obtained open-cell foam and preventing cracks. Examples of the reinforcing fibers include vinylon fiber, polypropylene fiber, aramid fiber, acrylic fiber, rayon fiber,
Examples include carbon fiber, glass fiber, potassium titanate whisker, alumina fiber, steel wool, and slag wool.

The reinforcing fiber preferably has a fiber length of 1
１５15 mm. When the fiber length is less than 1 mm, the fibers are re-agglomerated at the time of mixing to form fiber balls, and the fiber length is 15 m.
If it exceeds m, the dispersibility will be reduced, and none of them may exhibit a sufficient reinforcing effect. The fiber diameter of the reinforcing fibers is preferably 1 to 500 μm. If the fiber diameter is out of the above range, there is a possibility that no sufficient reinforcing effect is exhibited.

The amount of the reinforcing fiber to be added is preferably 10 parts by weight or less based on 100 parts by weight of the hydraulic inorganic substance of the curable inorganic composition. If the addition amount exceeds 10 parts by weight, the dispersibility of the fiber is reduced, and the reinforcing effect may be impaired.

The foaming aid is added for the purpose of stabilizing bubbles during foaming. Examples of the foaming auxiliary include, for example, a porous inorganic powder such as silica gel, alumina gel, zeolite, and activated carbon, and a surfactant composed of a fatty acid metal salt such as a metal stearate, a metal oleate, and a metal palmitate. Is mentioned. Among the foaming aids comprising the above surfactants, among others, zinc stearate, calcium stearate, aluminum stearate, sodium oleate, potassium oleate, sodium palmitate,
Potassium palmitate, sodium laurylbenzenesulfonate, and sodium lauryl sulfate can be suitably used.

The amount of the foaming aid composed of the porous inorganic powder is determined by the amount of the hydraulic inorganic material 100 in the curable inorganic composition.
It is preferably 5 parts by weight or less based on parts by weight. If the amount exceeds 5 parts by weight, the occurrence of foam breakage increases,
Foaming stability is impaired. The addition amount of the foaming aid composed of the surfactant is preferably 0.05 to 5 parts by weight, more preferably 0.3 to 3 parts by weight, based on 100 parts by weight of the hydraulic inorganic substance of the curable inorganic composition. Department. When the addition amount is less than 0.05 part by weight, the effect of adding the foaming aid does not appear, the occurrence of foam breakage increases, and the stability of foaming may be impaired. If the amount exceeds the above range, the viscosity of the curable inorganic composition may increase, which may adversely affect the foaming of the curable inorganic composition.

The inorganic foam is added for the purpose of reducing the weight of the obtained open-cell foam. Examples of the inorganic foam include a glass balloon, a shirasu balloon, a fly ash balloon, a silica balloon, a pearlite,
Hill stone, granular expanded silica, and the like. These may be used alone or in combination of two or more. When the apparent density of the inorganic foam is less than 0.01 g / cc, the mechanical strength of the obtained open-cell foam is reduced. When the apparent density is more than 1 g / cc, the purpose of reducing the weight is sufficiently achieved. Therefore, preferably 0.01 to 1 g / c
c, more preferably 0.03 to 0.7 g / cc.
The amount of the inorganic foam added is preferably 10 to 10 parts by weight of the hydraulic inorganic substance of the curable inorganic composition.
100 parts by weight, more preferably 30 to 80 parts by weight. If the amount is less than 10 parts by weight, the purpose of reducing the weight cannot be sufficiently achieved, and if it exceeds 100 parts by weight, the mechanical strength of the obtained open-cell foam may be reduced.

In the present invention, the continuous pores of the inorganic foam are in contact with the individual cells in the closed cell foam in which small cells (cells) are gathered adjacent to each other in the longitudinal direction of the closed cell foam. Refers to thin and long bubbles as if the open cells were broken one after another, and the continuous pore diameter indicates the diameter of the continuous pore. The average of the continuous pore diameter is preferably 10 to 5000 μm, more preferably 50 to 10 μm.
00 μm. The average value of the continuous pore diameter is 10 to 500.
When the thickness is outside the range of 0 μm, the sound absorbing property is reduced.

The open cell foam has an air permeability of 1 cm.
^Three・ Cm / cm^Two・ Sec ・ cmH _TwoIf less than O,
Decreased sound absorption, 40cm^Three・ Cm / cm^Two・ Sec ・
cmH_TwoIf it exceeds O, in addition to the decrease in sound absorption, open cells
Since the mechanical strength of the foam itself decreases,
The air permeability of the foam is preferably 1 to 40 cm^Three・ Cm /
cm^Two・ Sec ・ cmH_TwoO, more preferably 3-20
cm^Three・ Cm / cm^Two・ Sec ・ cmH_TwoO, most preferred
Or 5-10cm^Three・ Cm / cm^Two・ Sec ・ cmH
_TwoO.

In the first step of the present invention, Al ₂ O ₃ —Si
Excluding the O ₂ -based inorganic powder, the alkali metal silicate, the foaming agent, water and the foamable inorganic composition (A) slurry comprising the polysiloxane-polyoxyalkylene copolymer and the polysiloxane-polyoxyalkylene copolymer. The foamable inorganic composition (B) slurry for forming an open-celled inorganic foam is laminated and cast.

The foamable inorganic compositions (A) and (B)
When the specific gravity after foaming is different between the two when the slurry of the above is laminated and cast, a foamable inorganic composition which can obtain a foam having a small specific gravity is cast later.

In the second step, the foamable inorganic compositions (A) and (B) cast and laminated are foamed and cured.
By injecting the foamable inorganic composition from which a foam having a small specific gravity as described above is obtained in the first step, the boundary portion between the high specific gravity layer and the low specific gravity layer has a structure having a specific gravity gradient. Does not mix to form a beautiful laminated structure of a high specific gravity layer and a low specific gravity layer. The foamable inorganic composition (A)
After the laminate of (B) and (B) are foamed, the temperature at which the foam is cured may be room temperature,
By heating to a certain degree, the curing reaction can be accelerated, and the mechanical strength of the obtained sound absorbing material can be enhanced.

The foamed layer formed from the foamable inorganic composition (A) containing the polysiloxane-polyoxyalkylene copolymer obtained in the second step has an anionic interface other than the polysiloxane-polyoxyalkylene copolymer. Since the cell diameter is larger than that of the foamed layer formed from the foamable inorganic composition (B) containing the activator, and thus the cell wall thickness between cells becomes a continuous pore foam structure, the surface strength is increased. Shows high performance, low airflow resistance (in spite of such performance), and low sound reflection.

The density of the foam layer formed from the foamable inorganic composition (A) and the foamable inorganic composition (B) is preferably 0.15 to 0.4 g / cm ³ . When the density of the obtained foam layer is less than 0.15 g / cm ³ , the mechanical strength is low, handling is difficult, and there is a possibility that the foam layer cannot withstand washing with high-pressure washing water. If it exceeds cm ³ , the sound absorption may be reduced.

The skin layer of the inorganic foamed cured product of the foamable inorganic composition (A) refers to a gas generated by a foaming agent at the time of foaming. It means the outer shell that volatilizes from some cells to the outside of the system, crushes some cells in the surface layer part, and has a very low degree of non-foaming or foaming formed in this part.

In the third step, the skin layer of the foamed and cured inorganic foamed and hardened material of the foamable inorganic composition (A) is cut off. This is a portion which is in contact with the surface of the molding frame. In the case of ordinary foam molding, approximately 1 mm may be cut off from the surface layer.

[0040] The invention according to claim 2 provides the suction device according to claim 1.
Sound material, Al_TwoO_Three-SiO _TwoInorganic powder,
Lucali metal silicate, blowing agent, water and polysiloxane
Foamable inorganic composition comprising a loxyalkylene copolymer
The thickness of the foam layer of the product (A) is 0.5 to 15 mm.
The gist is a sound absorbing material characterized by the following.

In the sound-absorbing material according to claim 2, the foam layer of the foamable inorganic composition (A) has a thickness of 0.5.
If it is less than 15 mm, the ability to protect against high-pressure washing water will decrease. If it exceeds 15 mm, the resulting sound-absorbing material will have poor sound absorption, so that it is limited to the above range of 0.5 to 15 mm.

As described above, the detailed function of the sound absorbing material according to the first aspect of the present invention is sufficiently clarified by using a foamable inorganic composition containing a polysiloxane-polyoxyalkylene copolymer. Not open cell foam is a low-density open-cell foam having a low-density open-cell foam at the surface layer, and has a large open-pore diameter. Can be formed integrally with the high-strength open-cell foam layer
The obtained sound absorbing material enables washing with high-pressure washing water without deteriorating the sound absorbing properties of the open-cell foam.

The sound absorbing material according to the second aspect of the present invention is the first aspect.
The thickness of the foam layer formed from the foamable inorganic composition containing the polysiloxane-polyoxyalkylene copolymer in the sound-absorbing material of the invention described above, and from which the skin layer has been cut, is reduced to an optimal range of 0.5 to 15 mm. By setting, it is possible to provide a non-combustible sound absorbing material exhibiting higher strength together with higher sound absorbing properties. In particular, according to the present invention, the foam layer containing the polysiloxane-polyoxyalkylene copolymer, which is also a low-density open-cell foam, is extremely thin on the surface layer of the low-density open-cell foam. The presence as a protective film enables cleaning with high-pressure cleaning water without deteriorating the sound absorption characteristics of the open-cell foam, so that it can be applied to a wide range of soundproofing facilities for various types of civil engineering and buildings. Becomes possible.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

[Inorganic curable powder] Fly ash (manufactured by Kanden Kako Co., Ltd., average particle size 20 μm, JIS A6201)
Was classified using a classifier (Model: TC-15, manufactured by Nisshin Engineering Co., Ltd.) to obtain inorganic curable powder-1 having a particle size of 10 μm or less.

(Examples 1 to 4) [Preparation of foamable inorganic composition (A)] 100 parts by weight of the above-mentioned inorganic curable powder and a 40% by weight aqueous solution of sodium silicate (the molar ratio of SiO ₂ / Na ₂ O is 1) .5) 125
The parts by weight were stirred and mixed with a hand mixer to obtain a uniform paste. Subsequently, 15 parts by weight of a 10% by weight aqueous solution of hydrogen peroxide (diluted with a 35% by weight aqueous solution manufactured by Mitsubishi Gas Chemical Company) and talc (manufactured by Sanyo Clay Industry Co., Ltd., average particle size: 5 μm) were added to the above mixture.
30 parts by weight, vinylon fiber (Kuraray Co., Ltd., trade name "RM 1
82-3 ", a fiber length of 3 mm) 1 part by weight, 1.5 parts by weight of a polysiloxane-polyoxyalkylene copolymer (trade name" F342 "manufactured by Shin-Etsu Chemical Co., Ltd.) and 25 parts by weight of viscosity-adjusted water In addition to the inorganic composition paste, about 10 more
The mixture was stirred and mixed for 2 seconds to obtain a foamable curable inorganic composition (A).

[Preparation of foamable inorganic composition (B)] Sodium oleate (manufactured by Wako Pure Chemical Industries, Ltd.) was used in place of the polysiloxane-polyoxyalkylene copolymer used in the foamable inorganic composition (A). ) An expandable inorganic composition (B) was prepared in the same manner as the expandable inorganic composition (A) except that 1.5 parts by weight were used.

The obtained foamable curable inorganic composition (B)
As shown in FIG. 1- (a),
g, immediately after that, as shown in FIG. 1- (b), 1.5 kg (or 4.5 kg) of the expandable inorganic composition (A) was similarly poured into the molding form from above. Thereafter, as shown in FIG.
Then, when heated at 85 ° C. for 3 minutes, the foamed product expands to a predetermined magnification. The obtained foam is cured by heating at the same temperature for another 10 hours, and the surface is cured as shown in FIG. 1- (d). The foam layer 4 of the foamable inorganic composition (A) and the foam layer 5 of the foamable inorganic composition (B) having the skin layer 3
Were laminated to produce an inorganic cured foam.

The skin layer of the foam layer 4 (hereinafter, abbreviated as A layer) of the obtained inorganic cured foam was cut off to produce a sound absorbing material having A layers of each thickness shown in Table 1. . still,
The size of the mold cavity of the molding mold used was (width) 500 m.
m × (length) 600 mm × (height) 90 mm, and the sound-absorbing materials of Examples 1 to 3 were obtained from an inorganic cured foam in which 1.5 kg of the foamable curable inorganic composition (A) was cast.
The sound-absorbing material of Example 4 was cut from an inorganic cured foam in which 4.5 kg of the foamable curable inorganic composition (A) was cast as shown in parentheses above. It was produced.

The obtained sound absorbing material was dried in a desiccator, and the thickness and the bulk density (g / cm ³ ) were measured according to a conventional method. The measurement results show that the bulk density of both the A layer 4 and the B layer 5 is
0.3 g / cm ³ .

Comparative Example 1 A skin layer of an inorganic cured foam consisting of only the foam layer of the foamable inorganic composition (B) of the sound absorbing material of Example 1 was cut and removed in the same manner as in Example 1. ,
A sound absorbing material having the specifications shown in Table 1 was produced.

(Comparative Example 2) The foamable inorganic compositions (A) and (B) of Example 1 were prepared in different molding molds, respectively, and both were laminated with a urethane-based adhesive. An attempt was made to produce a sound absorbing material similar to the sound absorbing material, but it was impossible to slice a 1 mm thick foam layer from the foam of the foamable inorganic composition (A), and the sound absorbing material could not be produced. .

(Comparative Example 3) The foamable inorganic compositions (A) and (B) of Example 2 were prepared in different molding molds, and a skin layer was formed from the foam of the foamable inorganic composition (A). Was cut out, and a foam having a thickness of 5 mm was sliced to produce a sound-absorbing material, which was then bonded with a urethane-based adhesive to produce a sound-absorbing material similar to the sound-absorbing material of Example 2. In the above-mentioned manufacturing method, not only the number of steps was doubled or more (5 → 12) than in the examples, but a lot of waiting time was generated, and the productivity was extremely low as compared with the examples.

In order to evaluate the performance of the sound absorbing materials of Examples 1 to 3 and Comparative Examples 1 to 3, the average incidence sound absorption coefficient at normal incidence and the high-pressure washing water test were tested by the following methods, and the production cost was also included. The productivity of the sound absorbing material was evaluated. The test and evaluation results are shown in Table 1.

1. Normal incidence average sound absorption coefficient: JIS A1
According to 405, the normal incidence sound absorption coefficient (aj) was measured.
In addition, the size of the test piece was 100 mm in diameter, and the surface of the foam 4 containing the polysiloxane-polyoxyalkylene copolymer was the sound source side of each sound absorbing material of the examples. The back surface of the test piece was measured in a state in which an iron plate having a thickness of 25 mm was in close contact with the test piece and there was no air layer. The measurement of the normal incidence sound absorption coefficient (aj) is performed in the frequency range of 400 to 4000 Hz, and the measured value for each frequency is weighted using the weight Kj defined in the Road Traffic Noise Measurement Guideline of the Ministry of Construction, and the normal incidence average is measured. The sound absorption coefficient Σaj · Kj / ΣKj was calculated. The normal incidence average sound absorption coefficient was shown as a real number, but as the evaluation in the present invention, 0.9 or more was treated as good.

2. High pressure wash water test: Area obtained 500
A water-absorbing material having a size of 600 mm × 600 mm was used as a test piece, and water was discharged from a position 15 cm above the test piece at a water discharge angle of about 60 ° and a nozzle discharge pressure of 60 kg / cm ² for 15 seconds with a water amount normally used for washing, and the surface of the foam Was observed, and evaluated in two stages: ：: no damage was observed, ×: damage was found such as surface scraping.

3. Productivity: Comprehensive evaluation of the performance of the obtained sound-absorbing material, the value of the manufacturing facility, the number of manufacturing steps, the working environment, etc., ○: good, Δ: good quality, but poor productivity, × : Unmanufacturable: three levels.

[0058]

[Table 1]

[0059]

Since the sound absorbing material of the present invention is constituted as described above, it has both high sound absorbing properties and high strength.

[0060]

[Brief description of the drawings]

FIG. 1 is an explanatory view of a method for producing a sound absorbing material of the present invention.

[Description of Signs] 1 Mold frame 2 Lid 3 Skin layer 4, 5 Foam layer A Foamable inorganic composition (A) B Foamable inorganic composition (B)

Continued on the front page (51) Int.Cl. ⁶ Identification code FI E04B 1/86 E04B 1/86 A

Claims (2)

[Claims] 1. A foamable inorganic composition (A) slurry and polysiloxane comprising an Al ₂ O ₃ —SiO ₂ inorganic powder, an alkali metal silicate, a foaming agent, water and a polysiloxane-polyoxyalkylene copolymer. A first step of laminating and casting the foamable inorganic composition (B) slurry containing an anionic surfactant other than the polyoxyalkylene copolymer, and the above-described foamed inorganic composition laminated and cast ( A second step of foaming and curing A) and (B) and a third step of cutting off the skin layer of the foamed and cured foamable inorganic composition (A) of inorganic foam. Manufacturing method of sound absorbing material. 2. A sound-absorbing material obtained by the method for producing a sound-absorbing material according to claim 1, comprising an Al ₂ O ₃ —SiO ₂ -based inorganic powder, an alkali metal silicate, a foaming agent, water and polysiloxane. The thickness of the foam layer of the foamable inorganic composition (A) comprising a polyoxyalkylene copolymer is 0.5 to 15
mm.