JP7545458B2 - Sound absorbing and insulating materials and structures - Google Patents

Description

The present invention relates to a sound absorbing and insulating material with sound absorbing and insulating properties and a method for manufacturing the same.

For example, in a vehicle, in order to reduce the noise generated by the engine, it has been proposed to place an engine cover 80 on the outer peripheral surface of the engine E as shown in FIG. 6 (Patent Document 1).

The engine cover 80 has a two-layer structure consisting of a urethane foam resin layer 81 that faces the outer circumferential surface of the engine E (sound source), and an injection-molded resin cover 83 on the opposite side. The urethane foam resin layer 81 that faces the outer circumferential surface of the engine E functions as a sound absorbing layer, absorbing the sound generated by the engine E. On the other hand, the resin cover 83 on the opposite side to the outer circumferential surface of the engine E functions as a sound insulation layer, reflecting the sound that has passed through the urethane foam resin layer 81, thereby reducing noise that leaks to the outside.
Furthermore, a fibrous material is sometimes used as the sound absorbing layer, and the engine cover 3 in Patent Document 2 has a two-layer structure of a polypropylene-based resin sheet 2 and a polypropylene nonwoven fabric 1 .
In both cases, the resin cover member and the sound absorbing member are separate bodies, and a process is required to integrate them, which has the problem of complicating the manufacturing process and increasing costs.

JP 2003-27958 A JP 2000-351161 A

However, in the conventional engine cover 80, when sound leaking from the engine cover 80 itself and its surroundings is reflected in the engine room and returns to the engine cover 80, it is reflected by the outer resin cover 83. As a result, the leaking sound cannot reach the urethane foam resin layer 81, which is the inner sound-absorbing layer, and the sound-absorbing effect is particularly insufficient. In addition, the manufacturing process is complicated.

The present invention has been made in consideration of the above points, and aims to provide a sound absorbing and insulating material that exhibits good sound absorbing and insulating effects for both sound from the sound source side and sound from the opposite side to the sound source side, and a method for manufacturing the same.

A first aspect of the invention is a sound-absorbing and insulating material consisting of polyurethane foam placed on all or part of the outer surface of a sound source, the polyurethane foam having a skin layer on its surface, one surface of the polyurethane foam facing the outer surface of the sound source consisting of a skin layer in a closed cell state, and the other surface of the polyurethane foam consisting of a skin layer at least partially in an open cell state, and the outer surface of the sound source and at least the outer peripheral edge of the end of the closed cell state skin layer on one surface of the polyurethane foam are in close contact with each other, thereby forming an airtight space between the outer surface of the sound source and the closed cell state skin layer on one surface of the polyurethane foam.

A second aspect of the invention is characterized in that, in the first aspect of the invention , the outer surface of the sound source and the entire surface of the closed-cell skin layer on one surface of the polyurethane foam are in close contact with each other, thereby forming an enclosed space between the outer surface of the sound source and the closed-cell skin layer on one surface of the polyurethane foam.

A third aspect of the present invention is characterized in that, in the first or second aspect of the present invention , the average thickness of the skin layer in the closed cell state is 5 μm or more.

A fourth aspect of the invention is characterized in that, in any one of the first to third aspects of the invention , the air permeability of the skin layer in the closed cell state (based on JIS K6400-7 Method B: 2012/ISO 7231: 2010) is less than 3 ml/cm ² /s, and the air permeability of the skin layer in the open cell state (based on JIS K6400-7 Method B: 2012/ISO 7231: 2010) is 3 to 50 ml/cm ² /s.

A fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects of the present invention , the polyurethane foam has an overall density (based on JIS K7222:2005/ISO 845:1988) of 70 to 250 kg/ ^m3 .

A sixth aspect of the invention is characterized in that, in any one of the first to fifth aspects of the invention , the normal incidence sound transmission loss (based on ASTM E2611-09 (2009)) at 1600 Hz for sound incident from the surface side consisting of the skin layer in a closed cell state is 20 dB or more, and the normal incidence sound absorption coefficient (based on JIS A1405-2:2007/ISO 10534-2:1998) at 1600 Hz for sound incident from the surface side consisting of at least a portion of the skin layer in an open cell state is 45% or more.

A seventh aspect of the invention is a method for producing a sound absorbing and insulating material consisting of polyurethane foam to be placed on all or part of the outer surface of a sound source, by applying a release agent to the mold surfaces of a mold, injecting polyurethane foam raw material into the mold and foaming it, characterized in that a release agent containing a branched-chain hydrocarbon wax is applied to the mold surface that forms one surface of the polyurethane foam facing the outer surface of the sound source, and a release agent containing at least a linear hydrocarbon wax is applied to the mold surface that forms the other surface of the polyurethane foam, a skin layer in a closed cell state is formed over the entire one surface of the polyurethane foam on the mold surface that has been applied with the release agent containing the branched-chain carbonized wax, and a skin layer at least partially in an open cell state is formed on the other surface of the polyurethane foam on the mold surface that has been applied with the release agent containing the linear hydrocarbon wax.

The skin layer on the surface of a polyurethane foam is a layered portion that is denser than the core (inside).
A skin layer in a closed cell state has few penetrating air bubbles (cells), and therefore has a soundproofing effect of reflecting sound or preventing sound from entering. On the other hand, a skin layer in an open cell state has many penetrating air bubbles (cells), and therefore sound is more easily entered into the skin layer than in a closed cell state, and thus has a sound absorbing effect together with the core portion located inside the skin layer.

The sound absorbing and insulating material of the invention of claims 1 to 6 has a sound insulating effect because one surface of the polyurethane foam facing the outer surface of the sound source is made of a skin layer in a closed cell state, while the other surface of the polyurethane foam is made of at least a part of a skin layer in an open cell state, so that sound can easily penetrate into the core part, and has a sound absorbing effect together with the core part inside the polyurethane foam.

According to the sound absorbing and insulating material of the invention of claims 1 to 6, the sound directly incident from the sound source on one side surface facing the outer surface of the sound source can be partially blocked by the closed cell skin layer on the one side surface facing the outer surface of the sound source. Also, the sound that passes through the closed cell skin layer and enters the core part can be partially absorbed by the core part. On the other hand, the sound from the sound source that passes through the closed cell skin layer, the core part, and the open cell skin layer, is reflected by the surrounding wall surfaces, etc., and returns to the sound absorbing and insulating material, enters the core part through the open cell skin layer formed on at least a part of the other side surface different from the one side facing the sound source in the sound absorbing and insulating material, so the sound can be absorbed again by the core part, and a particularly good sound insulating effect can be obtained.

The manufacturing method for the sound absorbing and insulating material of the invention of claim 7 makes it possible to easily manufacture a sound absorbing and insulating material that has good sound absorbing and insulating properties for both sounds that are directly incident from the sound source and sounds that are incident from around the sound source.

FIG. 2 is a cross-sectional view of one embodiment of a sound absorbing and insulating material. FIG. 2 is a cross-sectional view showing a step of applying a release agent in an example of a method for producing a sound absorbing and insulating material. FIG. 2 is a cross-sectional view showing a step of injecting polyurethane foam raw material in an example of a method for producing a sound absorbing and insulating material. FIG. 2 is a cross-sectional view showing a foaming step in an example of a method for producing a sound absorbing and insulating material. 1 is a table showing the compositions and measurement results of Examples and Comparative Examples. FIG. 1 is a cross-sectional view showing an example of a conventional engine cover.

An embodiment of the sound absorbing and insulating material of the present invention will be described with reference to the drawings. The sound absorbing and insulating material 10 shown in Fig. 1 is made of polyurethane foam 11 arranged on a part or the whole of the outer surface S1 of a sound source S. The sound source S is not particularly limited. For example, when the sound source S is a vehicle engine, the sound absorbing and insulating material 10 constitutes an engine cover.
It is preferable that the sound absorbing and insulating material 10 is arranged so as to cover the parts of the outer surface S1 of the sound source S where sound is particularly loud, and by arranging it so as to cover the entire surface, the sound absorbing and insulating properties can be further improved.

The polyurethane foam 11 constituting the sound absorbing and insulating material 10 is formed by molding, and has a skin layer 12 formed by molding on its surface. The skin layer 12 has one surface facing the outer surface S1 of the sound source S (i.e., the sound source side surface) made of a skin layer 12A in a closed cell state, and at least a portion of the other surface (i.e., the non-sound source side surface) made of a skin layer 12B in an open cell state.
Here, the one side surface refers to a region of the polyurethane foam 11 constituting the sound absorbing and insulating material 10 that faces the outer surface S1 of the sound source S.

The skin layer 12 on the surface of the polyurethane foam (including the skin layer 12A in a closed cell state and the skin layer 12B in an open cell state) is a layered portion formed with a higher density than the core portion (inside) 11a, and is the portion formed by contacting the mold surface during foam molding by molding.

The average thickness of the skin layer 12A in the closed cell state is 5 μm or more, and more preferably 10 μm or more. By making the thickness of the skin layer 12A in the closed cell state 5 μm or more, a higher sound insulation effect can be obtained. The thickness of the skin layer can be controlled by the mold temperature and the amount of filling into the mold (pack rate) during foam molding of the polyurethane foam. The lower the mold temperature and the higher the pack rate into the mold, the thicker the skin layer will be.

The air permeability of the polyurethane foam 11 (based on JIS K6400-7 Method B: 2012/ISO 7231: 2010) is 3 ml/cm ² /s or less, more preferably 1.5 ml/cm ² /s or less, for the closed-cell skin layer 12A, 3 to 50 ml/cm ² /s for the open-cell skin layer 12B, and 3 to 50 ml/cm ² /s for the core portion 11a. The relationship in magnitude of air permeability of each portion is [core portion > open-cell skin layer >> closed-cell skin layer].

The air permeability of the skin layer 12A in the closed cell state is preferably small in order to block sound as much as possible (to increase the reflection amount of incident sound). On the other hand, the air permeability of the skin layer 12B in the open cell state and the air permeability of the core portion 11a are preferably such that the value of [air permeability of the skin layer in the open cell state/air permeability of the core portion] is 0.3 to 1.0, more preferably 0.4 to 1.0. It is preferable to ensure that the air permeability of the skin layer 12B in the open cell state is at least a certain level relative to the air permeability of the core portion 11a, to facilitate the entrance of sound.

The polyurethane foam 11 preferably has an overall density (based on JIS K7222:2005/ISO 845:1988) of 70 to 250 kg/m ³ , more preferably 80 to 200 kg/m ^3. If the overall density is 70 kg/m ³ or less, there is a risk of deterioration in sound insulation, and if it is 250 kg/m ³ or more, it is not preferable for applications such as automobiles that require weight reduction.

The relationship between the densities of the various parts of the polyurethane foam 11 (based on JIS K7222:2005/ISO 845:1988) is [skin layer in a closed cell state>skin layer in an open cell state≧core part].
The relationship between the density of the open-cell skin layer 12B and the density of the core portion 11a is preferably such that the value of [density of the open-cell skin layer/density of the core portion] is 1.00 to 1.03. It is preferable that the increase in density of the open-cell skin layer 12B with respect to the density of the core portion 11a is 3% or less to ensure light weight.

The thickness of the polyurethane foam 11 is determined appropriately, but an example would be approximately 2 to 100 mm.

The sound absorbing and insulating material 10 is in close contact with the outer surface S1 of the sound source S and at least the outer peripheral edge 121A of the end of the closed cell skin layer 12A on one side surface of the polyurethane foam 11 facing the outer surface S1, and forms an enclosed space surrounded by the close contact portion between the outer surface S1 of the sound source S and the closed cell skin layer 12A on one side surface of the polyurethane foam 11 facing the outer surface S1. This reduces the leakage of sound from the sound source S that enters the closed cell skin layer 12A on one side surface of the polyurethane foam 11 facing the outer surface S1 of the sound source S to the outside from between the outer surface S1 of the sound source S and the end of the closed cell skin layer 12A on one side surface of the polyurethane foam 11, thereby improving sound insulation.

The sound absorbing and insulating material 10 preferably forms an enclosed space so as to reduce the space (gap) between the outer surface S1 of the sound source S and the closed-cell skin layer 12A of one side surface of the polyurethane foam 11 facing the outer surface S1 by bringing the outer surface S1 of the sound source S into close contact with substantially the entire surface of the skin layer 12A. In the case of full contact, leakage of sound from the sound source S to the outside can be further reduced, and sound insulation can be improved, compared to the case in which only the outer peripheral edge 121A of the end of the closed-cell skin layer 12A is in close contact.
Here, the term "fully attached" refers not only to a state in which the shapes of the outer surface S1 of the sound source S and the skin layer 12A in the closed cell state on one surface of the polyurethane foam 11 facing the outer surface S1 completely match and are in close contact with no gaps, but also to a state in which the shapes of the outer surface S1 and the skin layer 12A in the closed cell state roughly match and are in close contact with a small gap. However, the outer peripheral edge 121A at the end of the skin layer 12A in the closed cell state is in close contact with the outer surface S1 of the sound source S with no gaps.

In addition, the sound absorbing and insulating material 10 can absorb the sound that penetrates the closed-cell skin layer 12A and enters the core portion 11a in the core portion 11a. On the other hand, the sound that penetrates the closed-cell skin layer 12A, the core portion 11a, and the open-cell skin layer 12B, is reflected by the wall surfaces surrounding the sound source S, and returns to the surface of the sound absorbing and insulating material 10, enters the core portion 11a from the open-cell skin layer 12B on the surface of the sound absorbing and insulating material 10, and can be absorbed again by the core portion 11a.

The side surface 11b of the edge of the polyurethane foam 11 that constitutes the sound absorbing and insulating material 10 may be either a closed cell skin layer 12A or an open cell skin layer 12B.

In addition, by removing part of the open-cell skin layer 12B on the other surface of the polyurethane foam 11 opposite the sound source S and at least part of the side surface 11b of the edge of the polyurethane foam 11 by cutting, grinding, or the like to expose the core portion 11a, sound reflected and returned by the walls surrounding the sound source S can be more easily introduced into the core portion 11a, improving sound absorption.

The manufacturing method of the sound absorbing and insulating material 10 is carried out by using a known molding method in which polyurethane foam raw material is injected into a mold and foamed. The manufacturing method of the sound absorbing and insulating material 10 will be explained using Figures 2 to 4.

The mold 60 shown in Figures 2 to 4 is composed of a lower mold 61 and an upper mold 65. In this embodiment, the mold surface 62 of the lower mold 61 is a mold surface that forms the other side surface (non-sound source side surface) of the polyurethane foam 11 that constitutes the sound absorbing and insulating material 10, which does not face the outer peripheral surface of the sound source. On the other hand, the mold surface 66 of the upper mold 65 is a mold surface that forms one side surface (sound source side surface) of the polyurethane foam 11 that constitutes the sound absorbing and insulating material 10, which faces the outer surface S1 of the sound source S. The mold 60 is heated to 40 to 80°C by a known heating method, and it is more preferable to heat it to 50 to 80°C in consideration of moldability. The heating method is not limited to a method in which the mold 60 is placed in a heating furnace or a method in which piping through which a heating medium circulates is provided on the outer surfaces and inside of the lower mold 61 and the upper mold 65.

As shown in FIG. 2, a release agent W1 containing a linear hydrocarbon wax is applied to a mold surface 62 of a lower mold 61 which forms the surface of the polyurethane foam on the side opposite to the sound source, while a release agent W2 containing a branched chain hydrocarbon wax is applied to a mold surface 66 of an upper mold 65 which forms the surface of the polyurethane foam on the side opposite to the sound source.
Examples of the linear hydrocarbon wax include paraffin wax, Fischer-Tropsch wax, and Sasol wax. Solvent-based release agents dispersed in an organic solvent, and water-based release agents dispersed in water using an emulsifier can be used.
Examples of the branched chain hydrocarbon wax include microcrystalline wax and modified polyethylene wax, and solvent-based release agents and water-based release agents can be used.

Since linear hydrocarbon waxes are composed mainly of linear hydrocarbon main chains, they tend to have a lower ratio of terminal methyl groups and stronger polarity than branched-chain hydrocarbon waxes. On the other hand, since branched-chain hydrocarbon waxes are composed mainly of branched-chain hydrocarbons, they tend to have a higher ratio of terminal methyl groups and weaker polarity.
For this reason, the difference in polarity (solubility) between the polyurethane foam raw material and the linear hydrocarbon wax is relatively smaller than the difference in polarity (solubility) between the polyurethane foam raw material and the branched hydrocarbon wax, and when the release agent W1 containing the linear hydrocarbon wax is used, a skin layer is less likely to be formed on the polyurethane foam surface, and the skin layer that is formed is thin and tends to be in an open-cell state, compared to when the release agent W2 containing the branched hydrocarbon wax is used. On the other hand, when the release agent W2 containing the branched hydrocarbon wax is used, a skin layer is more likely to be formed on the polyurethane foam surface, and the skin layer that is formed is thick and tends to be in a closed-cell state.
The release agent is applied by a known method such as spraying or brushing, and the amount of the release agent applied is 10 to 300 g/ ^m2 .

After the mold surface 62 of the lower mold 61 and the mold surface 66 of the upper mold 65 are coated with the mold release agent, polyurethane foam raw material F is poured into the mold 60 as shown in FIG.
The polyurethane foam raw material F contains a polyol, an isocyanate, a blowing agent, a catalyst, and appropriate additives.

The polyol may be any of the known ether polyols, ester polyols, ether ester polyols, polymer polyols, etc., used in the production of polyurethane foams, either alone or in combination.

The ether polyols include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sucrose, or polyether polyols obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to the polyhydric alcohols. The ester polyols include polyester polyols obtained by polycondensation of aliphatic carboxylic acids such as malonic acid, succinic acid, and adipic acid, or aromatic carboxylic acids such as phthalic acid, and aliphatic glycols such as ethylene glycol, diethylene glycol, and propylene glycol. Furthermore, ether ester polyols containing both ether groups and ester groups in the polyol, and polymer polyols obtained by polymerizing ethylenically unsaturated compounds in ether polyols can also be used.

The isocyanate may be aromatic, alicyclic, or aliphatic, and may be a bifunctional isocyanate having two isocyanate groups in one molecule, or a trifunctional or higher isocyanate having three or more isocyanate groups in one molecule, and these may be used alone or in combination.

For example, bifunctional isocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, xylylene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4 Examples of such diisocyanates include aromatic diisocyanates such as 1,4-biphenylene diisocyanate, alicyclic diisocyanates such as cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, and methylcyclohexane diisocyanate, and aliphatic diisocyanates such as butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, and lysine diisocyanate.

Examples of trifunctional or higher isocyanates include 1-methylbenzene-2,4,6-triisocyanate, 1,3,5-trimethylbenzene-2,4,6-triisocyanate, biphenyl-2,4,4'-triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2',5,5'tetraisocyanate, triphenylmethane-4,4',4"-triisocyanate, and polymeric MDI. Other examples include urethane prepolymers. can also be used. The isocyanate is not limited to one type, and may be one or more types. For example, one type of aliphatic isocyanate and two types of aromatic isocyanate may be used in combination. The isocyanate index is preferably 90 to 115, more preferably 95 to 110. The isocyanate index is an index used in the polyurethane field, and is a numerical value that represents the equivalent ratio of the isocyanate groups of the isocyanate to the active hydrogen groups in the raw material (for example, the active hydrogen groups contained in the hydroxyl groups of polyols and the active hydrogen groups of water as a blowing agent, etc.) expressed as a percentage.

The blowing agent is not particularly limited, but water is preferred. Carbon dioxide gas, pentane, hydrofluoroolefin (HFO), etc. may also be used as a blowing assistant in combination with the blowing agent water. HFO is a compound with an ozone depletion potential (ODP) of 0 and a low global warming potential (GWP). The amount of water used as a blowing agent is preferably 0.3 to 3 parts by weight per 100 parts by weight of polyol.

Catalysts that are known for use in polyurethane foams can be used. Examples include amine catalysts such as triethylamine, triethylenediamine, diethanolamine, bis(2-dimethylamino-ethyl)ether, tetramethylguanidine, and imidazole-based compounds, tin catalysts such as stannous octoate, and metal catalysts (also called organometallic catalysts) such as phenylmercury propionate or lead octenate. A typical amount of catalyst is preferably 0.2 to 6 parts by weight per 100 parts by weight of polyol.

Additives that are appropriately mixed include foam stabilizers, colorants, crosslinking agents, fillers, flame retardants, antioxidants, and other synthetic resin stabilizers. The foam stabilizer may be any foam stabilizer that is used in polyurethane foams, and examples of such foam stabilizers include silicone foam stabilizers, fluorine-containing compound foam stabilizers, and known surfactants. Colorants that are used include pigments, dyes, and other agents that correspond to the desired color.

After the polyurethane foam raw material F is injected into the mold 60, it is closed as shown in FIG. 4, and the foaming reaction of the polyurethane foam raw material F is carried out. Note that in the illustrated example, the mold 60 is injected with the mold 60 open, but an injection port (not shown) may be provided in the upper mold 65, and the polyurethane foam raw material F may be injected into the mold 60 through the injection port with the mold 60 closed.

The sound absorbing and insulating material 10 made of the polyurethane foam 11 is formed in the mold 60 by the foaming reaction of the polyurethane foam raw material F. The polyurethane foam 11 has a skin layer 12 formed on the surface by the mold surface 62 of the lower mold 61 and the mold surface 66 of the upper mold 65. The skin layer 12A on the surface formed by the mold surface 66 of the upper mold 65 during foaming molding, that is, the skin layer 12A formed on one surface facing the outer surface S1 of the sound source S, becomes a closed-cell skin layer 12A by the mold release agent W2 containing branched-chain hydrocarbon wax applied to the mold surface 66 of the upper mold 65. On the other hand, the skin layer 12B on the surface formed by the mold surface 62 of the lower mold 61 during foaming molding, that is, the skin layer 12B formed on the surface opposite the sound source, becomes an open-cell skin layer 12B by the mold release agent W1 containing linear hydrocarbon wax applied to the mold surface 62 of the lower mold 61.

Then, the mold 60 is opened, and the sound absorbing and insulating material 10 made of the polyurethane foam 11 is removed. As shown in FIG. 1, the sound absorbing and insulating material 10 removed from the mold 60 has a closed cell skin layer 12A on one surface of the polyurethane foam 11, which is the surface facing the outer surface S1 of the sound source S, and an open cell skin layer 12B on the opposite surface.

In addition, after removing the sound absorbing and insulating material 10 from the mold 60, a part of the open-cell skin layer 12B on the other surface of the polyurethane foam 11 opposite the sound source S and at least a part of the side surface 11b of the edge of the polyurethane foam 11 may be removed by cutting, grinding, or the like to expose the core portion 11a.

Below, examples and comparative examples of the present invention are described. Using the polyurethane foam raw material with the composition shown in Figure 5, test pieces of sound absorbing and insulating material made of polyurethane foam, 500 mm square x 30 mm thick and 500 mm square x 10 mm thick, were produced by a molding method. The composition was the same for each example and each comparative example. The numerical values of each component in the composition in Figure 5 indicate parts by weight. The mold used was the type that was opened and injected, and the temperature was adjusted with warm water.

Polyol: Polyether polyol, functional group number 3, weight average molecular weight 5000, hydroxyl value 35 mgKOH/g
Blowing agent: Water Amine catalyst 1: "DABCO33LSI" manufactured by Air Products Japan Amine catalyst 2: "DABCOBL-19" manufactured by Air Products Japan
Foam stabilizer: Toray Dow Corning Co., Ltd., "SZ-1346E", silicone foam stabilizer Isocyanate: Polymeric MDI, isocyanate group content (NCO%) 31.5%
Release agent W1: Konishi Co., Ltd., "URM-520", linear hydrocarbon wax Release agent W2: Chukyo Yushi Co., Ltd., "N-915", branched hydrocarbon wax

For each of the obtained examples and comparative examples, the surface condition of the skin layer was judged, and the sound absorption coefficient, sound transmission loss, air permeability, and density were measured.

The surface state was judged visually whether the skin layer was in a closed cell state or an open cell state for the sound source side surface (surface formed with the surface forming mold surface on the sound source side) and the non-sound source side surface (surface formed with the surface forming mold surface on the non-sound source side), and the average thickness was also measured. The average thickness of the skin layer was measured using a scanning electron microscope (JSM-IT100 manufactured by JEOL Ltd.). Specifically, platinum was evaporated onto a polyurethane foam having a skin layer cut into a predetermined shape using a platinum evaporation device (JEC-3000FC manufactured by JEOL Ltd.) to make it easier to observe with a scanning electron microscope, and then a photograph was taken at a magnification of 300 times near the skin layer, and the distance between the surface (outermost surface) of the skin layer and the top of the cell was measured. The thickness of the skin layer was measured at six points, the first to third thickest points and the first to third thinnest points in the photograph, and the average value was taken as the average thickness of the skin layer.

The sound absorption coefficient was measured by punching out a 29φ x 10 mm thick sample (with skin layers on the top and bottom) from a 500 mm square x 10 mm thick test piece, and measuring the sound absorption coefficient on the non-sound source side by irradiating sound from the non-sound source side in accordance with JIS A1405-2:2007/ISO 10534-2:1998.

The sound transmission loss was measured by punching out a 29φ x 10 mm thick sample (with skin layers on the top and bottom surfaces) from a 500 mm square x 10 mm thick test piece, and measuring the sound transmission loss on the non-sound source side in accordance with ASTM E2611-09 (2009).

The breathability was measured by slicing a 500 mm square x 30 mm thick test piece into 200 mm square x 10 mm pieces so that the thickness was divided into three parts, and producing samples on the sound source side (with skin layer), non-sound source side (with skin layer), and core part (without skin layer) based on JIS K6400-7 Method B: 2012/ISO 7231: 2010.

The density was measured based on JIS K7222:2005/ISO 845:1988 by slicing a 500 mm square x 30 mm thick test piece into 400 mm square x 10 mm pieces so that the thickness was divided into three parts, and producing samples on the sound source side (with skin layer), non-sound source side (with skin layer), and core part (without skin layer). In addition, the overall density of the 400 mm square x 30 mm thick test piece (with skin layer on top and bottom) was measured based on JIS K7222:2005/ISO 845:1988.

In Examples 1 to 3, release agent W1 (straight-chain) is applied to the surface forming mold surface on the non-sound source side (mold surface 62 of lower mold 61), release agent W2 (branched-chain) is applied to the surface forming mold surface on the sound source side (mold surface 66 of upper mold 65), the pack rate is kept constant (100%), and the mold temperature is changed to change the thickness of the polyurethane foam skin layer.

Example 1 is an example where the mold temperature was 70°C, the surface state was a closed-cell skin layer on the sound source side with an average thickness of 12 μm, and an open-cell skin layer on the non-sound source side with the average thickness not measurable, the sound absorption coefficient was 56%, the sound transmission loss was 23.4 dB, the air permeability was 1.2 ml/cm ² /s for the sound source side skin layer, 26.3 ml/cm ² /s for the core portion, and 15.3 ml/cm ² /s for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 0.58, the density was 131 kg/m ³ for the sound source side skin layer, 130 kg/m ³ for the core portion, and 130 kg/m ³ for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 1.00, and the overall density was 130 kg/m ³ . Example 1 has a large sound absorption coefficient and a large sound transmission loss, and has high sound absorption and sound insulation properties.

Example 2 is an example where the mold temperature was 60°C, and the surface state was a closed-cell skin layer on the sound source side with an average thickness of 14 μm, and an open-cell skin layer on the non-sound source side with the average thickness not measurable, the sound absorption coefficient was 55%, the sound transmission loss was 24.8 dB, the air permeability was 0.8 ml/cm ² /s for the sound source side skin layer, 24.1 ml/cm ² /s for the core portion, and 14.6 ml/cm ² /s for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 0.61, the density was 131 kg/m ³ for the sound source side skin layer, 130 kg/m ³ for the core portion, and 130 kg/m ³ for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 1.00, and the overall density was 130 kg/m ³ . In Example 2, the mold temperature was lower than in Example 1, so the average thickness of the skin layer in the closed cell state on the sound source side was larger, and the sound absorption coefficient was slightly reduced, but the sound transmission loss was larger.

Example 3 is an example where the mold temperature was 45°C, and the surface state was a closed-cell skin layer on the sound source side with an average thickness of 18 μm, and an open-cell skin layer on the non-sound source side with the average thickness not measurable, the sound absorption coefficient was 51%, the sound transmission loss was 27.9 dB, the air permeability was 0.5 ml/cm ² /s for the sound source side skin layer, 20.9 ml/cm ² /s for the core portion, and 8.7 ml/cm ² /s for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 0.42, the density was 132 kg/m ³ for the sound source side skin layer, 130 kg/m ³ for the core portion, and 130 kg/m ³ for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 1.00, and the overall density was 131 kg/m ³ . In Example 3, the mold temperature was lower than in Example 2, so the average thickness of the skin layer in the closed cell state on the sound source side was larger, and the sound absorption coefficient was slightly reduced, but the sound transmission loss was larger.

In Examples 4 to 6, release agent W1 (straight-chain) is applied to the surface forming mold surface on the sound source side (mold surface 62 of lower mold 61), release agent W2 (branched-chain) is applied to the surface forming mold surface on the non-sound source side (mold surface 66 of upper mold 65), the mold temperature is kept constant (60°C), and the pack rate is changed to change the density of the polyurethane foam.

Example 4 is an example with a pack rate of 62%, and the surface state was a closed-cell skin layer on the sound source side with an average thickness of 7 μm, and an open-cell skin layer on the non-sound source side with the average thickness not measurable. The sound absorption coefficient was 58%, the sound transmission loss was 21.0 dB, the breathability was 2.9 ml/cm ² /s for the sound source side skin layer, 30.3 ml/cm ² /s for the core, and 28.5 ml/cm ² /s for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 0.94, the density was 81 kg/m ³ for the sound source side skin layer, 80 kg/m ³ for the core, and 80 kg/m ³ for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 1.00, and the overall density was 80 kg/m ³ . In Example 4, the packing rate was smaller than in Example 2, resulting in a smaller density and a smaller average thickness of the skin layer in the closed cell state on the sound source side. As a result, the sound absorption coefficient was increased, but the sound transmission loss was slightly reduced.

Example 5 is an example with a pack rate of 115%, and the surface state was a closed-cell skin layer on the sound source side with an average thickness of 17 μm, and an open-cell skin layer on the non-sound source side with the average thickness not measurable. The sound absorption coefficient was 53%, the sound transmission loss was 25.9 dB, the breathability was 0.6 ml/cm ² /s for the sound source side skin layer, 21.7 ml/cm ² /s for the core, and 11.5 ml/cm ² /s for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 0.53, the density was 152 kg/m ³ for the sound source side skin layer, 150 kg/m ³ for the core, and 150 kg/m ³ for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 1.00, and the overall density was 151 kg/m ³ . In Example 5, the packing rate was increased compared to Example 2, resulting in a higher density and a larger average thickness of the skin layer in the closed cell state on the sound source side. As a result, the sound absorption coefficient was slightly reduced, but the sound transmission loss was increased.

Example 6 is an example with a pack rate of 154%, and the surface state was a closed-cell skin layer on the sound source side with an average thickness of 22 μm, and an open-cell skin layer on the non-sound source side with the average thickness not measurable. The sound absorption coefficient was 48%, the sound transmission loss was 29.5 dB, the breathability was 0.2 ml/cm ² /s for the sound source side skin layer, 8.1 ml/cm ² /s for the core, and 3.1 ml/cm ² /s for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 0.38, the density was 202 kg/m ³ for the sound source side skin layer, 200 kg/m ³ for the core, and 200 kg/m ³ for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 1.00, and the overall density was 201 kg/m ³ . In Example 6, the packing rate was increased compared to Example 2, resulting in a higher density and a larger average thickness of the skin layer in the closed cell state on the sound source side. As a result, the sound absorption coefficient was slightly reduced, but the sound transmission loss was increased.

In Examples 1 to 6, the sound absorbing and insulating material 10 was produced using the release agent W1 (straight-chain) on the entire surface of the mold surface 62 of the lower mold 61 and the release agent W2 (branched-chain) on the entire surface of the mold surface 66 of the upper mold 65, but it is also possible to use the release agent W2 on the entire surface of the mold surface 62 of the lower mold 61 and the release agent W1 on the entire surface of the mold surface 66 of the upper mold 65. Even in this case, by using the sound absorbing and insulating material 10 in such a way that the skin layer 12A (one side surface of the polyurethane foam 11) in a closed cell state formed by using the release agent W2 is in close contact with the outer surface S1 of the sound source S, a suitable sound absorbing and insulating effect can be obtained.

The sound absorbing and insulating material 10 may also be produced by using the release agent W2 on the entire surface of the mold surface 66 of the upper mold 65, and using the release agent W1 and the release agent W2 together on the entire surface of the mold surface 62 of the lower mold 61. In either case, the sound absorbing and insulating material 10 is used such that the skin layer 12A in a closed cell state formed by using the release agent W2 is in close contact with the outer surface S1 of the sound source, and the skin layer 12B (the other surface of the polyurethane foam 11) in an open cell state formed by using the release agent W1 faces away from the sound source, thereby providing a suitable sound absorbing and insulating effect.

Comparative Example 1 is an example in which the release agent W2 (branched) is applied to both the surface forming mold surface on the non-sound source side and the surface forming mold surface on the sound source side, and other requirements are the same as in Example 2. In Comparative Example 1, the surface state was a closed-cell skin layer on the sound source side with an average thickness of 15 μm, and a closed-cell skin layer on the non-sound source side with an average thickness of 14 μm, the sound absorption coefficient was 16%, the sound transmission loss was 25.2 dB, the breathability was 0.7 ml/cm ² /s for the sound source side skin layer, 21.4 ml/cm ² /s for the core portion, and 0.8 ml/cm ² /s for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 0.04, the densities were 131 kg/m ³ for the sound source side skin layer, 130 kg/m ³ for the core portion, and 131 kg/m ³ for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 1.01, and the overall density was 131 kg/m ³ . In Comparative Example 1, both the sound source side and the non-sound source side had skin layers in a closed cell state, and therefore the sound absorption coefficient was extremely low.

Comparative Example 2 is an example in which the release agent W1 (straight-chain) is applied to both the surface forming mold surface on the non-sound source side and the surface forming mold surface on the sound source side, and other requirements are the same as in Example 2. In comparative example 2, the surface state was an open-cell skin layer on the sound source side, the average thickness could not be measured, and the non-sound source side was an open-cell skin layer, the average thickness could not be measured, the sound absorption coefficient was 57%, the sound transmission loss was 13.2 dB, the breathability was 14.4 ml/ ^cm2 /s for the sound source side skin layer, 23.6 ml/ ^cm2 /s for the core, and 15.2 ml/ ^cm2 /s for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 0.64, the density was 130 kg/ ^m3 for the sound source side skin layer, 130 kg/ ^m3 for the core, and 130 kg/ ^m3 for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 1.00, and the overall density was 130 kg/ ^m3 . In Comparative Example 2, since the skin layers on both the sound source side and the non-sound source side were in an open cell state, the sound transmission loss was extremely low.

Comparative Example 3 is an example in which the release agent W2 (branched) is applied to the surface of the mold for surface formation on the non-sound source side, the release agent W1 (straight-chain) is applied to the surface of the mold for surface formation on the sound source side, and other requirements are the same as those of Example 2. In Comparative Example 3, the surface state was an open-cell skin layer on the sound source side, the average thickness could not be measured, and the non-sound source side was a closed-cell skin layer, the average thickness was 14 μm, the sound absorption coefficient was 17%, the sound transmission loss was 24.7 dB, the breathability was 15.1 ml/cm ² /s for the sound source side skin layer, 22.3 ml/cm ² /s for the core portion, and 0.7 ml/cm ² /s for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 0.03, the density was 130 kg/m ³ for the sound source side skin layer, 130 kg/m ³ for the core portion, and 131 kg/m ³ for the non-sound source side skin layer, the ratio of [non-sound source side skin layer/core portion] was 1.01, and the overall density was 130 kg/m ³ . In Comparative Example 3, the sound absorption coefficient was extremely low because, unlike Example 2, the sound source side had a skin layer in an open cell state and the non-sound source side had a skin layer in a closed cell state.

Comparative Example 4 is an example in which a polypropylene resin plate (thickness 1 mm) was used alone. Comparative Example 4 had a sound absorption coefficient of 3%, a sound transmission loss of 19.8 dB, air permeability of 0 ml/cm ² /s, and an overall density of 900 kg/m ^3. Comparative Example 4 had an extremely poor sound absorption coefficient compared to Examples 1 to 6.

Comparative Example 5 is an example in which miscellaneous felt (basis weight 1000 g/ ^m2 , thickness approximately 15 mm) was used alone. Comparative Example 5 had a sound absorption coefficient of 44%, a sound transmission loss of 6.8 dB, air permeability of 39.5 ml/ ^cm2 /s, and an overall density of 70 kg/ ^m3 . Comparative Example 5 had an extremely poor sound transmission loss compared to Examples 1 to 6.

When Comparative Examples 1 to 5 were used alone, the sound transmission loss or sound absorption rate was extremely poor compared to Examples 1 to 6, and in order to achieve both sound transmission loss and sound absorption rate, it was necessary to use them in combination with another material. On the other hand, Examples 1 to 6 were excellent in sound transmission loss and sound absorption rate even when used alone. The sound transmission loss of Examples 1 to 6 was superior to 19.8 dB of the polypropylene resin board of Comparative Example 4, and the sound absorption rate of Examples 1 to 6 was superior to 44% of the miscellaneous felt of Comparative Example 5.
The sound absorbing and insulating material of the present invention has a sound transmission loss at 1600 Hz (based on ASTM E2611-09 (2009)) of 20 dB or more, and a normal incidence sound absorption coefficient at 1600 Hz (based on JIS A1405-2:2007/ISO 10534-2:1998) of 45% or more, and has good sound absorbing and insulating properties. In addition, the manufacturing method of the sound absorbing and insulating material of the present invention is easy to manufacture because it consists only of molding.

In this way, the sound absorbing and insulating material of the present invention can provide good sound absorbing and insulating effects (especially sound absorbing effects) for both sounds from the sound source side and sounds from the opposite side of the sound source, making it suitable for engine covers, etc.

10: Sound absorbing and insulating material 11: Polyurethane foam 11a: Core 12: Skin layer 12A: Skin layer in closed cell state 12B: Skin layer in open cell state 60: Mold 61: Lower mold 62: Mold surface of lower mold 65: Upper mold 66: Mold surface of upper mold S: Sound source W1: Mold release agent containing linear hydrocarbon wax W2: Mold release agent containing branched chain hydrocarbon wax

Claims (3)

A sound absorbing and insulating material having a polyurethane foam disposed on a part or all of the outer surface of a sound source,
The polyurethane foam has a skin layer on a surface thereof,
One surface of the polyurethane foam facing the outer surface of the sound source has a skin layer in a closed cell state,
The other surface of the polyurethane foam is provided with a skin layer having at least a portion in an open cell state ;
13. A sound absorbing and insulating material, wherein the polyurethane foam constituting the sound absorbing and insulating material is a single polyurethane foam . A sound absorbing and insulating material having a polyurethane foam disposed on a part or all of the outer surface of a sound source,
The polyurethane foam has a skin layer on a surface thereof,
One surface of the polyurethane foam facing the outer surface of the sound source has a skin layer in a closed cell state,
The other surface of the polyurethane foam is provided with a skin layer having at least a portion in an open cell state;
The total density of the polyurethane foam is 130 to 250 kg/m ³ A sound absorbing and insulating material characterized by: A sound absorbing and insulating material having a polyurethane foam disposed on a part or all of the outer surface of a sound source,
The polyurethane foam has a skin layer on a surface thereof,
One surface of the polyurethane foam facing the outer surface of the sound source has a skin layer in a closed cell state,
The other surface of the polyurethane foam is characterized by having a skin layer, at least a portion of which is in an open cell state, and the sound absorbing and insulating material is arranged so that the closed cell state skin layer is in close contact with part or all of the outer surface of the sound source.

Images