Sound absorption material for vehicle

Abstract

To provide a sound absorption material for vehicles and a foamed laminate having a thin base material thickness and high performance over a wide frequency range when used as a sound absorption material, and its manufacturing method.SOLUTION: A sound absorption material for vehicles comprises a flexible polyurethane foam composed of a polyol component and a polyisocyanate component as composing components, in which the polyol component contains a catalyst, a foam arranging agent and a foaming agent, at least one of the polyol component or the polyisocyanate component contains a defoaming agent. Surface tension of the foam arranging agent is 22 to 28 mN / m at 23°C, and content of the defoaming agent is 0.1 to 7.5% by mass of the total amount of the polyol component and the polyisocyanate component.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a sound absorbing material for vehicles. [Background technology]

[0002] Noise has a long history in people's lives, and in Japan, noise has been one of the major sources of trouble since the past, including noise problems around airports and military bases. In addition, the Basic Law for the Environment stipulates that noise pollution is one of the seven typical types of pollution, along with air pollution, water pollution, soil pollution, vibration, land subsidence, and bad odors. In this context, for example, in the automobile industry, the demand for low noise levels in vehicle components is very high, coupled with the fact that the tightening of regulations on noise levels outside the vehicle and the fact that quieting down interior noise is directly linked to the value of the vehicle. For this reason, further noise reduction by improving the performance of soundproofing materials such as sound-absorbing materials is essential. In particular, reducing engine transmission sound and tire radiation sound is an urgent issue, and there is a growing need for sound-absorbing materials that can meet this demand. In response to these demands, it is relatively easy to increase the sound absorption and vibration absorption performance by increasing the thickness of the base material, but there is a concern that if the base material is thick, sufficient space cannot be secured inside the vehicle. Therefore, it is necessary to improve the sound absorption performance and reduce the thickness of the base material.

[0003] Various efforts have been made to improve this sound absorption performance. For example, Patent Document 1 describes a method of increasing the cell diameter of a rigid foam as a soundproofing material for a dash panel to improve sound absorption at 1000 Hz to 2000 Hz. However, since the base material is a rigid foam, there is a problem that the use location is limited due to the characteristics that it is difficult to follow the shape when installed in a vehicle and difficult to restore the shape when compressed. In addition, since the average sound absorption coefficient at 1000 to 2000 Hz when the thickness of the base material is 15 mm is 45% or more, it cannot be said that the thinning of the base material and the sound absorption performance are sufficient. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-017983 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above-mentioned background technology, and has an object to provide a sound-absorbing material for vehicles which has a thin substrate thickness and high performance over a wide frequency range when used as a sound-absorbing material. [Means for solving the problem]

[0006] That is, the present invention includes the embodiments shown below.

[0007] [1] A vehicle sound-absorbing material made of a flexible polyurethane foam having as its constituent components a polyol component (A) and a polyisocyanate component (B), characterized in that the polyol component (A) contains a catalyst (C), a foam stabilizer (D), and a blowing agent (E), and at least one of the polyol component (A) and the polyisocyanate component (B) contains a foam opener (F), the foam stabilizer (D) has a surface tension of 22 to 28 mN / m@23°C, and the content of the foam opener (F) is 0.1 to 7.5 mass% based on the total amount of the polyol component (A) and the polyisocyanate component (B).

[0008] [2] The vehicle sound-absorbing material according to the above [1], characterized in that the cell opener (F) is a silicone-based oil, and the number average molecular weight of a polysiloxane component contained in the silicone-based oil is 10,000 to 50,000.

[0009] [3] The sound-absorbing material for vehicles according to the above [1] or [2], characterized in that the cell opener (F) is contained in the polyol component (A).

[0010] [4] The vehicle sound-absorbing material according to any one of the above [1] to [3], characterized in that the polyisocyanate component (B) contains diphenylmethane diisocyanate in the range of 50 to 85 mass%, and the total amount of 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate contained in the diphenylmethane diisocyanate is 10 to 50 mass% based on the total amount of the diphenylmethane diisocyanate.

[0011] [5] Density is 25 to 200 kg / m 3 The Asker C hardness measured according to JIS K7312 is 20 to 100 points, and the air permeability is 0.1 to 100 cm 3 / cm 2 / sec.

[0012] [6] A sound-absorbing material for vehicles according to any one of [1] to [5] above, characterized in that the average cell diameter is 2000 μm or more and the area ratio of cells having a diameter of 5000 μm or more is 20% or more.

[0013] [7] The sound-absorbing material for vehicles according to any one of the above [1] to [6], characterized in that the thickness of the thinnest part is 5.0 to 50 mm.

[0014] [8] A foam laminate comprising a vehicle sound-absorbing material according to any one of [1] to [7] above and a film, wherein at least one film is arranged relative to a sound source in the following order: film, vehicle sound-absorbing material.

[0015] [9] The foam laminate according to [8] above, wherein the film is coated on a surface of a sound-absorbing material for vehicles.

[0016]

[10] The foam laminate according to [8] or [9] above, wherein the film is a polyurethane resin film.

[0017]

[11] The foam laminate according to

[10] above, wherein the polyurethane resin film is made of an aqueous polyurethane resin emulsion.

[0018]

[12] The foamed laminate according to

[11] above, characterized in that a polyol component used as a raw material for the aqueous polyurethane resin emulsion has a carbonate skeleton.

[0019]

[13] The foamed laminate according to

[12] above, wherein the average functionality of the polyol component having a carbonate skeleton is 2.1 or more.

[0020]

[14] The foamed laminate according to any one of the above [8] to

[13] , characterized in that the film has a thickness of 0.1 to 250 μm, an opening rate of 0 to 2.0%, and an average opening diameter of 300 μm to 1000 μm when the opening rate exceeds 0%.

[0021]

[15] A method for producing a foam laminate, characterized in that the film is covered on a surface of the sound-absorbing material for vehicles described in [1] above by integral molding. Effect of the Invention

[0022] By using the vehicle sound-absorbing material of the present invention, it is possible to achieve a thin substrate and high sound-absorbing performance over a wide frequency range. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will now be described in further detail.

[0024] The vehicle sound-absorbing material of the present invention comprises a flexible polyurethane foam obtained from the polyol component (A), polyisocyanate component (B), catalyst (C), foam stabilizer (D), blowing agent (E), and foam opener (F) shown below.

[0025] The polyol component (A) forms a polyurethane by polyaddition with the polyisocyanate component (B), and in the present invention, it is preferably at least one selected from the group consisting of polyether polyols and polyester polyols. Furthermore, the number average molecular weight is preferably 1,000 to 10,000, more preferably 3,000 to 8,000, and most preferably 4,000 to 8,000. Moreover, those having a nominal functionality of 2 or more are more preferable. If the number average molecular weight is less than the lower limit, the flexibility of the obtained foam is likely to be insufficient, and if it exceeds the upper limit, the hardness of the foam is likely to decrease. Furthermore, if the nominal functionality is less than 2, the rebound resilience of the foam is significantly reduced, and problems occur such as the foam not being able to restore to its original shape when compressed. Note. The nominal functionality refers to the theoretical average functionality (the number of active hydrogen atoms per molecule) assuming that no side reactions occur during the polymerization reaction of the polyol.

[0026] Examples of polyether polyols that can be used include polypropylene ether polyol, polyethylene polypropylene ether polyol (hereinafter referred to as PPG), and polytetramethylene ether glycol (hereinafter referred to as PTG). Examples of polyester polyols that can be used include polyester polyols made of adipic acid and a diol, which are polycondensation type polyester polyols, and polycaprolactone polyols, which are lactone type polyester polyols.

[0027] In the present invention, from the viewpoint of improving the heat resistance of the foam, at least one polyol selected from the group consisting of castor oil and castor oil-modified polyols can be used in combination in the polyol component (A). Examples of the at least one polyol selected from the group consisting of castor oil and castor oil-modified polyols include derivatives of castor oil such as refined castor oil, semi-refined castor oil, unrefined castor oil, and hydrogenated castor oil.

[0028] In the present invention, it is preferable that the polyol component (A) contains a polyether polyol having a polyoxyalkylene chain composed of a copolymer of oxyethylene and oxypropylene for the purpose of promoting the interconnection of the flexible polyurethane foam. The number average molecular weight is preferably 3,000 to 8,000, and the nominal number of functional groups is preferably 2 to 4. Furthermore, the content of oxyethylene units in the polyether polyol is preferably 60 to 90 mass%, more preferably 60 to 80 mass%. By making the content of oxyethylene units 60 to 90 mass%, the durability of the foam can be improved. In addition, from the viewpoint of storage stability at low temperatures, it is preferable that the copolymer composed of oxyethylene and oxypropylene is a random copolymer.

[0029] The amount of the polyether polyol added is preferably 0.5 to 5.0% by mass based on the polyol component (A). If the amount is less than the lower limit, the moldability of the foam may deteriorate, and if the amount is more than the upper limit, the elongation of the foam may decrease.

[0030] The polyol component (A) of the present invention can be used in combination with a polymer polyol obtained by polymerizing a vinyl monomer in a polyol by a normal method for the purpose of adjusting hardness. Such a polymer polyol can be, for example, a polymer obtained by polymerizing a vinyl monomer in a polyalkylene polyol such as the above-mentioned PPG in the presence of a radical initiator and stably dispersing it. In addition, examples of the vinyl monomer include acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl methacrylate, and alkyl methacrylate, and among these, acrylonitrile and styrene are preferred. Examples of such a polymer polyol include EL-910 and EL-923 manufactured by AGC Co., Ltd., and FA-728R manufactured by Sanyo Chemical Industries Co., Ltd.

[0031] The polyisocyanate component (B) in the present invention preferably uses diphenylmethane diisocyanates (hereinafter, MDI), such as 4,4'-diphenylmethane diisocyanate (hereinafter, 4,4'-MDI), 2,4'-diphenylmethane diisocyanate (hereinafter, 2,4'-MDI), 2,2'-diphenylmethane diisocyanate (hereinafter, 2,2'-MDI), and polyphenylene polymethylene polyisocyanate (hereinafter, P-MDI) as an isocyanate source. In the present invention, various modified products such as the above-mentioned MDI, a mixture of MDI and P-MDI, a urethane modified product, a urea modified product, an allophanate modified product, a nurate modified product, and a biuret modified product may also be used.

[0032] The MDI content of the polyisocyanate component (B) according to the present invention is preferably in the range of 50 to 85% by mass. If the MDI content exceeds 85% by mass, the storage stability at low temperatures of the resulting polyisocyanate composition and the durability of the resulting flexible foam may be reduced, while if it is less than 50% by mass, the crosslink density increases, resulting in reduced elongation of the flexible polyurethane foam, making it difficult to obtain sufficient foam strength.

[0033] Furthermore, the sum of the content of 2,2'-MDI and the content of 2,4'-MDI relative to the total amount of MDI (hereinafter referred to as isomer content) is preferably 10 to 50% by mass.

[0034] If the content of 2,2'-MDI and 2,4'-MDI relative to the total amount of MDI according to the present invention is less than 10% by mass, the storage stability of the resulting polyisocyanate composition at low temperatures may be impaired, and the isocyanate storage location, piping, and foam molding machine may require constant heating. In addition, the molding stability of the flexible polyurethane foam may be impaired, and foam collapse may occur during foaming. On the other hand, if the content exceeds 50% by mass, reactivity may decrease, and problems such as an extension of the molding cycle and a high closed cell ratio of the foam may occur, causing shrinkage after molding.

[0035] As the catalyst (C), various urethanization catalysts known in the art can be used, such as triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N,N',N',N''-pentamethyldiethylenetriamine, bis-(2-dimethylaminoethyl)ether, triethylenediamine, 1,8-diaza-bicyclo[5.4.0]undecene-7, 1,2-dimethylimidazole, dimethylethanolamine, N,N-dimethyl-N-hexanolamine, and further, organic acid salts of these, stannous octoate, zinc naphthenate, and other organometallic compounds. Also preferred are amine catalysts having active hydrogen, such as N,N-dimethylethanolamine and N,N-diethylethanolamine.

[0036] The amount of catalyst added is preferably 0.01 to 10% by mass based on the polyol component (A). If the amount is less than the lower limit, curing is likely to be insufficient, whereas if the amount is more than the upper limit, moldability may deteriorate.

[0037] As the foam stabilizer (D), a normal surfactant is used, and a silicone surfactant is preferably used. The surface tension of the foam stabilizer is preferably 22 to 28 mN / m@23°C, more preferably 23 to 27 mN / m@23°C. Examples of the foam stabilizer include Y-10366J, L-3646J, L-5309J, and L-3639LF manufactured by Momentive Corporation, and B-4113LF and B-8715LF2 manufactured by Evonik. The amount of these foam stabilizers to be added is preferably 0.1 to 3.0% by mass relative to the polyol component (A).

[0038] Water is mainly used as the blowing agent (E). Water reacts with isocyanate groups to form high-hardness urea groups and generate carbon dioxide gas, which can cause foaming. Any blowing agent may be used in addition to water. For example, a small amount of a low-boiling organic compound such as cyclopentane or isopentane may be used in combination, or a gas loading device may be used to mix and dissolve air, nitrogen gas, or liquefied carbon dioxide in the original solution to cause foaming. The amount of blowing agent added is usually 0.5 to 10% by mass based on the polyol composition, but if the apparent density is 25 kg / m 3 When obtaining a low-density flexible polyurethane foam, the content is preferably 4.0 to 7.0 mass%, and more preferably 4.0 to 6.5 mass%. If the content exceeds the upper limit, foaming may become difficult to stabilize, and if it is less than the lower limit, the density of the foam may not be sufficiently reduced.

[0039] The cell breaker (F) in the present invention is used for the purpose of coarsening the cells of the flexible polyurethane foam. By coarsening the cells, a resonator-type sound absorbing mechanism is developed in the flexible polyurethane foam, and it is possible to enhance the sound absorbing effect at a specific frequency. Examples of the components of the cell breaker (F) include silicone-based, oil-based, fatty acid-based, fatty acid ester-based, and phosphate-based cell breakers, and those in which the structure of these cell breakers is partially modified. These may be contained alone or in combination of two or more. In addition, when two or more types are contained, the combination may be any combination of silicone-based, alcohol-based, ether-based, polyol-based, metal soap-based, nonionic surfactant-based, oil-based, fatty acid-based, fatty acid ester-based, and phosphate-based cell breakers. In addition, it is particularly preferable that the cell breaker component is a silicone-based cell breaker. Examples of the silicone-based cell breakers include oil-based, oil compound-based, solution-based, emulsion-based, self-emulsifying, and powder-based cell breakers, and all of these cell breakers can be suitably used. Silicone-based foam openers have a polysiloxane structure similar to the silicone-based foam stabilizers, but differ in that the polysiloxane chain is relatively long to exhibit foam-opening properties and is insoluble in the polyol component (A) or the polyisocyanate component (B). The number-average molecular weight of the polysiloxane component is preferably 10,000 to 50,000, and more preferably 10,000 to 30,000. If the number-average molecular weight is less than 10,000, it may be difficult to obtain a foam-opening effect, and if the number-average molecular weight exceeds the upper limit, the dispersibility of the foam opener may decrease, causing separation.

[0040] Examples of silicone-based foam breakers include dimethyl silicone oil [(CH 3 ) 3 Si-〔OSi(CH 3 ) 2 〕nO-Si(CH 3 ) 3 ], methylphenyl silicone oil [(CH 3 ) 3 Si-〔OSi(CH 3 ) 2 〕m-〔OSi(CH 3 )(C 6H 5 )〕nO-Si(CH 3 ) 3 , (CH 3 ) 3 Si-〔OSi(CH 3 ) 2 〕m-〔OSi(C 6 H 5 ) 2 〕nO-Si(CH 3 ) 3 etc.], methyl hydrogen silicone oil [(CH 3 ) 3 Si-〔OSi(CH 3 ) 2 〕m-〔OSi(CH 3 )(H)〕nO-Si(CH 3 ) 3 etc.]

[0041] The content of the cell opener (F) is preferably 0.1 to 7.5% by mass, more preferably 0.1 to 7.0% by mass, based on the total amount of the polyol component (A) and the polyisocyanate component (B). If the content is less than 0.1% by mass, the cells may not be sufficiently coarsened, and sufficient sound absorbing performance may not be obtained, whereas if the content exceeds 7.5% by mass, the foaming may become unstable.

[0042] The vehicle sound-absorbing material made of the flexible polyurethane foam of the present invention can contain fillers such as calcium carbonate and barium sulfate, as well as various known additives and auxiliaries such as flame retardants, plasticizers, colorants, and anti-fungal agents, as necessary.

[0043] According to the present invention, the thickness of the thinnest part is 5.0 to 50 mm, and the density is 25 to 200 kg / m 3 The foam test piece has a C hardness of 20 to 100 points, a simple average sound absorption coefficient (hereinafter referred to as the average sound absorption coefficient) of 0.6 or more from 1000 Hz to 3500 Hz, an average sound absorption coefficient of 0.5 or more from 1000 Hz to 2000 Hz, and an air permeability of 0.1 to 100 cm 3 / cm 2 / sec. of soft polyurethane foam can be suitably obtained.

[0044] Here, sound absorption means preventing sound reflection, and is a completely different concept from sound insulation, which blocks transmitted sound with a wall or roof. The average sound absorption coefficient of 1000Hz to 3500Hz means the simple average value of normal incident sound absorption coefficients at 1000Hz, 1250Hz, 1600Hz, 2000Hz, 2500Hz, 3150Hz, and 3500Hz measured according to the method described in JIS A1405-2:2007. A sound absorption coefficient of 0.6 or more means that 60% or more of sound is absorbed. The average sound absorption coefficient of 1000Hz to 2000Hz means the simple average value of normal incident sound absorption coefficients at 1000Hz, 1250Hz, 1600Hz, and 2000Hz measured according to the method described in JIS A1405-2:2007.

[0045] The vehicle sound-absorbing material of the present invention can be suitably used for engine room interior components (hood liner, dash outer, oil pan, engine head cover, engine capsule, intake duct, air conditioner compressor cover), engine under-cover, floor under-cover, floor carpet, dash inner, front fender liner, rear fender liner, pillar, console door panel, instrument panel, headliner, trunk liner, inside of air cleaner system, inside of tire, etc.

[0046] Next, the method for producing the flexible polyurethane foam of the present invention will be described.

[0047] The flexible polyurethane foam of the present invention can be produced by reactively foaming a mixed liquid of a polyol component (A), a polyisocyanate component (B), a catalyst (C), a foam stabilizer (D), a blowing agent (E), and a cell opener (F). From the viewpoint of ensuring dispersion stability, the cell opener (F) is preferably added to the polyol component (A).

[0048] The NCO INDEX (the molar ratio of NCO to active hydrogen multiplied by 100) during mixing and foaming of all isocyanate groups in the polyisocyanate composition of the present invention and all active hydrogen groups in the active hydrogen group-containing compound containing water is preferably 70 to 140, and more preferably 70 to 120 as a range for a good molding cycle.

[0049] If the NCO index is less than 70, the closed cell foam will be too high. If it is more than 120, the unreacted isocyanate will remain for a long time, which may result in an extension of the molding cycle, or the foam may collapse during foaming due to a delay in the polymerization.

[0050] Examples of methods for producing flexible polyurethane foams that can be used include a method for producing flexible polyurethane molded foams (hereinafter referred to as flexible molded foams) in which a foaming concentrate, which is a mixture of the polyol component (A), polyisocyanate component (B), catalyst (C), foam stabilizer (D), blowing agent (E), and cell breaker (F), is injected into a mold and then foamed and cured; and a method for producing flexible polyurethane slab foams (hereinafter referred to as flexible slab foams) in which the mixture is supplied to a foaming container or continuously onto a belt conveyor and foamed.

[0051] In the production of flexible molded foams, the mold temperature when the foaming liquid is injected into the mold is usually 30 to 80° C., and preferably 45 to 70° C. If the mold temperature when the foaming liquid is injected into the mold is less than 30° C., the reaction rate may decrease, leading to an extension of the production cycle, while if the mold temperature is higher than 80° C., the reaction between water and isocyanate may be excessively promoted relative to the reaction between polyol and isocyanate, causing the foam to collapse during foaming.

[0052] The curing time for foaming and curing the foaming liquid is preferably 10 minutes or less, more preferably 7 minutes or less, in consideration of a typical production cycle of flexible molded foam.

[0053] When producing a flexible molded foam, the above-mentioned components can be mixed using a high-pressure or low-pressure foaming machine, as in the case of ordinary flexible molded foams.

[0054] It is preferable to mix the isocyanate component and the polyol component immediately before foaming. Other components can be mixed in advance with the isocyanate component or the polyol component to the extent that they do not affect the storage stability of the raw materials or the change over time in reactivity. The mixture can be used immediately after mixing, or it can be stored and then used as needed. In the case of a foaming device capable of simultaneously introducing more than two components into the mixing section, the polyol, foaming agent, isocyanate, catalyst, foam stabilizer, foam breaker, etc. can also be introduced into the mixing section individually.

[0055] The mixing method may be either dynamic mixing, in which mixing is performed in the machine head mixing chamber of the foaming machine, or static mixing, in which mixing is performed in the liquid delivery pipe, or both may be used in combination. Static mixing is often used to mix a gaseous component such as a physical foaming agent with a liquid component, while dynamic mixing is often used to mix components that can be stably stored as liquids. The foaming device used in the present invention is preferably a high-pressure foaming device that does not require solvent cleaning of the mixing section.

[0056] The mixture obtained by such mixing is poured into a metal mold, foamed and cured, and then demolded. In order to facilitate the above-mentioned demolding, it is also preferable to apply a release agent to the metal mold in advance. The release agent to be used may be any release agent commonly used in the molding and processing field.

[0057] In the production of soft molded foam, a film can be coated on the foam surface by integral molding in order to enhance the sound absorbing effect at a specific frequency. The sound absorbing film according to the present invention absorbs sound that tries to pass through the film from the outside by converting relatively low frequency sound of 1000 to 2000 Hz into vibration energy.

[0058] Integral molding is a method in which a film is placed in advance in at least one of the upper and lower halves of a mold in a shape that conforms to the shape of the inner surface, the mixed liquid is injected into the mold, and the mold is demolded after foaming and hardening. At least one film is placed in the order of film and soft polyurethane foam against the sound source, but in order to increase the sound absorption coefficient, another film may be placed on the opposite side of the sound source.

[0059] The film to be laminated on the flexible polyurethane foam is preferably a non-breathable resin film, such as polyurethane resin, acrylic resin, polyethylene resin, polypropylene resin, vinyl chloride resin, EVA resin, PBT resin, silicone rubber, and polyamide resins such as 6-nylon, 6,6-nylon, 11-nylon, and 12-nylon.

[0060] The thickness of the film is preferably 0.1 to 250 μm. If the thickness of the film is less than 0.1 μm, the moldability during molding may deteriorate, and if the thickness exceeds 250 μm, the sound absorbing performance may decrease. The density of the film is preferably 0.8 to 1.8 g / cm. 3 The film density is preferably 0.8 g / cm 3 If the thickness is less than this, there is a risk that sufficient sound absorption effect will not be obtained in the low frequency range, and if the thickness exceeds the upper limit, the weight of the sound absorbing material will become too heavy.

[0061] As a method for forming a film layer on the surface of a flexible polyurethane foam, in-mold coating molding can be performed in which an in-mold coating paint is applied in advance to at least one of the lower and upper parts of a mold, and then the polyurethane foam is molded.

[0062] The in-mold coating paint can be suitably used in both water-based and solvent-based paints, and may be one-component curing type or two-component curing type. Resins for in-mold coating paints include known paints such as polyurethane resins, acrylic resins, and polyester resins, among which polyurethane resins are preferred, and aqueous polyurethane resin emulsions using polyol components having a carbonate skeleton are preferred from the viewpoint of increasing the softening temperature. The polyol component having a carbonate skeleton may contain ester groups other than the carbonate skeleton, and may be a mixture of an aqueous polyurethane resin emulsion using a polyol component having a carbonate skeleton and an aqueous polyurethane resin emulsion using a polyol component having an ester group. The average functional group number of the polyol component having a carbonate skeleton is preferably 2.1 or more. If the average functional group number is less than 2.1, the heat resistance of the resulting film layer is easily impaired.

[0063] The product after demolding can be used as it is, but it is preferable to destroy the cell membrane of the foam under compression or reduced pressure by a known method to stabilize the subsequent appearance and dimensions of the product.

[0064] The hardness of the flexible polyurethane foam obtained by the above-mentioned production method is preferably 20 to 100 points, more preferably 40 to 100 points, in terms of C hardness measured using a rubber hardness tester (Asker C type) in accordance with JIS K7312. If the C hardness is less than 20 points, sufficient sound absorption properties may not be obtained. In addition, the air permeability of the flexible polyurethane foam obtained by the above-mentioned production method measured in accordance with JIS K6400 is 0.1 to 100 cm 3 / cm 2 / sec is preferably 0 to 80 cm 3 / cm 2 If the air permeability exceeds the upper limit, there is a risk that sufficient sound absorption properties may not be obtained.

[0065] The thickness of the thinnest part of the flexible polyurethane foam obtained by the above production method is preferably 5.0 to 50 mm, more preferably 5.0 to 30 mm. If the thickness of the thinnest part is less than 5.0 mm, a sufficient sound absorbing effect may not be obtained in the low to medium frequency range, and if the thickness exceeds the upper limit, there is a risk that a sufficient space cannot be secured in the vehicle interior.

[0066] The soft molded foam after demolding can be used by subjecting the surface skin layer or laminated film portion to a hole-opening treatment such as needle punching, hot needle processing, laser irradiation processing, etc., in order to effectively allow sound wave energy to enter the internal porous layer and to enhance the sound absorption effect on the high frequency side. The hole ratio is preferably 0 to 2.0%. If the hole ratio exceeds 2.0%, the sound absorption effect on the low frequency side may decrease. In addition, when the hole ratio exceeds 0%, the average hole diameter is preferably 300 μm to 1000 μm, and more preferably 300 μm to 900 μm. If the average hole diameter is less than 300 μm, the holes may be blocked by burrs generated during punching, and if it exceeds 1000 μm, the sound absorption effect on the low frequency side may decrease.

[0067] According to the above-mentioned method for producing a flexible polyurethane foam, a thickness of 5.0 to 50 mm and a density of 25 to 200 kg / m 3 The foam test piece has a C hardness of 20 to 100 points, an average sound absorption coefficient of 0.6 or more at 1000 Hz to 3500 Hz, an average sound absorption coefficient of 0.5 or more at 1000 Hz to 2000 Hz, and an air permeability of 0.1 to 100 cm 3 / cm 2 / sec of flexible polyurethane foam can be obtained.

[0068] [Mechanism by which large cells achieve high sound absorption effect] The flexible polyurethane foam of the present invention has a high sound absorbing effect due to the cell coarsening caused by the cell breaker. This is believed to be because the cell coarsening causes a Helmholtz resonator type sound absorbing mechanism to appear in the flexible polyurethane foam, enhancing the sound absorbing effect at a specific frequency. In a Helmholtz resonator, the air inside a container with an opening acts as a spring and resonates with vibrations at a specific frequency determined by the internal volume of the container and the area of ​​the opening. The above-mentioned resonance phenomenon causes the air introduced into the container to vibrate violently, and the noise energy is lost through friction loss, absorbing the sound.

[0069] In the present invention, it is believed that a high sound absorption effect can be achieved by considering the coarse cells as the container and the relatively small cells other than the coarse cells, the holes in the foam skin layer formed during production, or the openings in the film as the container openings, and adjusting the coarse cell size (internal volume of the container) so that the resonance frequency of the Helmholtz resonator is 1000 Hz to 3500 Hz.

[0070] In addition, in the present invention, a flexible polyurethane foam is used, but if a rigid polyurethane foam is used, it may be difficult to obtain a high sound absorption coefficient in the high frequency range of 3000 Hz or more. In addition, rigid polyurethane foam is difficult to conform to the shape when installed in a vehicle, and difficult to restore the shape when compressed, so that the places where it can be used are limited. EXAMPLES

[0071] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In addition, unless otherwise specified, "parts" and "%" in the text are based on mass.

[0072] (Examples 1 to 10, Comparative Examples 1 to 3) [Preparation of polyol composition] After replacing the reactor equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer with nitrogen, 50 g of polyol 1, 50 g of polyol 2, 2.5 g of crosslinking agent 1, 3.0 g of crosslinking agent 2, 0.4 g of catalyst 1, 0.06 g of catalyst 2, 1.0 g of foam stabilizer 1, 2.5 g of foam breaker 1, and 3.0 g of water were charged and stirred at 23 ° C. for 0.5 hours to obtain a polyol composition (P-1). As shown in Table 1, other polyol compositions (P-2 to P-9) were also prepared in the same manner as P-1.

[0073] [Preparation of isocyanate composition] After a reactor equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer was replaced with nitrogen, 100 g of isocyanate 1 and 2.8 g of cell breaker 1 were charged and stirred at 23°C for 0.5 hours to obtain an isocyanate composition (I-2).

[0074] [Synthesis of polycarbonate polyol] 31.3g of trimethylolpropane, 413.8g of 1,6-hexanediol, 454.9g of diethyl carbonate, and 0.045g of lithium acetylacetonate were mixed in a 1L two-neck glass reactor equipped with a stirrer, thermometer, heating device, and cooler, and reacted at 100-150°C for 8 hours under normal pressure while removing low boiling point components. The reaction temperature was then increased to 150°C, the pressure in the flask was reduced to 1kPa, and the reaction was continued for another 8 hours to obtain polycarbonate polyol (PCP-1) with a number average molecular weight of 1790g / mol and a hydroxyl value of 90.7mgKOH / g.

[0075] [Preparation of aqueous polyurethane resin emulsion] PUD-1 In a 1L reactor equipped with a stirrer, a thermometer, a nitrogen seal tube, and a cooler, 77.6g of N-980N (manufactured by Tosoh Corporation: number average molecular weight 2000; hydroxyl value 56.11mgKOH / g; 1,6-hexanediol-based polycarbonate diol), 3.04g of 1,6-hexanediol, 26.9g of PCP-1, 75g of acetone, 5.29g of 2,2-dimethylolpropanoic acid, and 31.2g of isophorone diisocyanate were charged, heated to 60°C, stirred at the same temperature for 30 minutes, and then 0.12g of Neostan U-600 was added and reacted for 5 hours. Next, 3.99g of triethylamine was charged to neutralize the carboxyl group, and 320g of water was charged while stirring to emulsify. After emulsification, 0.18 g of KL-245 was added, and within 30 minutes, amine water (30 g of water and 1.99 g of isophorone diamine) was added, and the amine chain extension reaction was carried out at 40°C for 12 hours. When the presence of isocyanate groups was no longer confirmed by FT-IR, stirring was stopped. The reaction solution was then transferred to a 2L eggplant flask and distilled under reduced pressure to remove 75 g of acetone and 50 g of water, obtaining an aqueous polyurethane resin emulsion composition (PUD-1).

[0076] PUD-2 In a 1L reactor equipped with a stirrer, a thermometer, a nitrogen seal tube, and a cooler, 51.8g of N-980N (manufactured by Tosoh Corporation: number average molecular weight 2000; hydroxyl value 56.11mgKOH / g; 1,6-hexanediol-based polycarbonate diol), 1.99g of 1,6-hexanediol, 53.8g of PCP-1, 75g of acetone, 5.29g of 2,2-dimethylolpropanoic acid, and 31.2g of isophorone diisocyanate were charged, heated to 60°C, stirred at the same temperature for 30 minutes, and then 0.12g of U-600 was added and reacted for 5 hours. Next, 3.99g of triethylamine was charged to neutralize the carboxyl group, and 320g of water was charged while stirring to emulsify. After emulsification, 0.18 g of KL-245 was added, and within 30 minutes, amine water (30 g of water and 1.99 g of isophorone diamine) was added, and the amine chain extension reaction was carried out at 40°C for 12 hours. When the presence of isocyanate groups was no longer confirmed by FT-IR, stirring was stopped. The reaction solution was then transferred to a 2L eggplant flask and distilled under reduced pressure to remove 75 g of acetone and 50 g of water, obtaining an aqueous polyurethane resin emulsion composition (PUD-2).

[0077] The raw materials used to obtain PUD-1 and PUD-2 are as follows: Trimethylolpropane: Sigma-Aldrich 1,6-Hexanediol: BASF JAPAN 2,2-Dimethylolpropionic acid: Tokyo Chemical Industry Co., Ltd. Isophorone diisocyanate: Evonik Acetone: KH Neochem Triethylamine: Kishida Chemical Co., Ltd. Isophoronediamine: manufactured by Tokyo Chemical Industry Co., Ltd. Neostan U-600: Manufactured by Nitto Kasei Co., Ltd. KL-245: Evonik ·Water: City water.

[0078] Of the raw materials shown in Table 1, the liquid temperature of the isocyanate composition and the mixture of all raw materials other than the isocyanate composition (polyol composition) were adjusted to 24°C to 26°C. A predetermined amount of polyisocyanate component was added to the polyol composition and mixed with a mixer (7000 rpm) for 7 seconds, then injected into a mold to foam a flexible polyurethane foam. The mixture was then removed from the mold and the physical properties of the resulting flexible polyurethane foam were measured.

[0079] [Foaming conditions] Mold temperature: 60~70℃ Mold shape: 200mm x 200mm x 10mm (Example 8 is 200 x 200 x 30mm) Mold material: Aluminum Cure time: 5 minutes Integrated molding: Film placed on the lower die of the mold (Examples 2, 3, and 6) : Spray in-mold coating paint onto the lower die of the mold (Examples 9 and 10)

[0080] [Table 1]

[0081] [Raw materials used] Polyol 1: Polyoxyethylene polyoxypropylene polyol having an average functionality of 3.0 and a hydroxyl value of 33 (mgKOH / g), EXENOL 823 (product name) manufactured by AGC Corporation Polyol 2: Polymer polyol having an average functionality of 3.0 and a hydroxyl value of 24 (mgKOH / g), EXENOL 923 (product name) manufactured by AGC Corporation Polyol 3: Unrefined castor oil with an average functionality of 2.7 and a hydroxyl value of 160 (mgKOH / g), URIC H-24 (product name) manufactured by Ito Oil Mills Polyol 4: polyoxyethylene polyoxypropylene polyol having an average functionality of 4.0, a hydroxyl value of 28 (mgKOH / g), and an oxyethylene unit content of 80% by mass in the polyether polyol, NEF-024 (product name) manufactured by Tosoh Corporation Crosslinker 1: Diethanolamine (Mitsui Chemicals) Crosslinker 2: Triethanolamine (Mitsui Chemicals) Catalyst 1: 33% dipropylene glycol solution of triethylenediamine (manufactured by Tosoh Corporation, product name: TEDA L-33) Catalyst 2: 70% dipropylene glycol solution of bis(2-dimethylaminoethyl) ether (manufactured by Tosoh Corporation, product name: TOYOCAT ET) Foam stabilizer 1: Silicone foam stabilizer (manufactured by Momentive, product name: L-5309J) Foam stabilizer 2: Silicone foam stabilizer (manufactured by Momentive, product name: L-3639LF) Foam stabilizer 3: Silicone foam stabilizer (manufactured by Momentive, product name: L-3646J) Foam stabilizer 4: Silicone foam stabilizer (Dow Toray, product name: SRX-280A) Foam opener 1: GC-302SS (product name) Silicone-based foam opener manufactured by Nisshin Chemical Laboratory Isocyanate 1: Polyphenylene polymethylene polyisocyanate with an MDI content of 70% by mass and an isomer content of 17.7% by mass (manufactured by Tosoh Corporation, product name: CEF-507) Film: Thermoplastic polyurethane elastomer film with a thickness of 30 μm (manufactured by Okura Kogyo Co., Ltd., product name Silkron ET85) ·PUD-1, PUD-2: In-mold coated paint.

[0082] [Formability evaluation] In Table 1, a moldability rating of "○" means that a flexible polyurethane foam was able to be molded without any collapse (the polyurethane foam sinking significantly after reaching its maximum height) or shrinkage of the generated polyurethane foam immediately after foaming or after curing, and a rating of "×" means that the polyurethane foam collapsed, shrank, or otherwise collapsed.

[0083] [Apparent Density] It was determined according to the method described in JIS K6400.

[0084] [C hardness] The hardness was measured using a rubber hardness tester (Asker C type) in accordance with JIS K7312.

[0085] [Breathability] The measurement was performed according to the method described in JIS K6400.

[0086] [Sound absorption coefficient] Based on the method described in JIS A1405-2:2007, the normal incidence sound absorption coefficient was measured at 500 to 6400 Hz using a Brüel & Kjær Japan 4206 type sound tube. The sound absorption coefficient was measured under the condition that a urethane foam with a diameter of 28.8 mm and a thickness of 10 mm was placed so that the lower mold surface of the mold faced the sound source, and no air space was provided behind the urethane foam.

[0087] [Average cell diameter] The average cell diameter of each polyurethane foam molding was determined by cutting out a disk of 28.8 mm in diameter from a 10 mm thick molded molding, taking an image of the side of the foam with a field of view of 10 mm vertical and 16.3 mm horizontal using a microscope equipped with a Moritex Corporation MTL5518C-034-01 lens, measuring the cell diameters of a specified number of cells present in the field of view, and then calculating the simple average of the cell diameters.

[0088] [Area ratio of cells with diameters of 5000 μm or more] The area percentage of cells with a diameter of 5000 μm or more in each polyurethane foam molding was calculated by cutting a 10 mm thick molded molding into a disk shape with a diameter of 28.8 mm, taking an image of the cross section of the foam with a field of view of 10 mm vertical and 16.3 mm horizontal using a microscope equipped with a Moritex Corporation MTL5518C-034-01 lens, measuring the area of ​​cells with a diameter of 5000 μm or more in the field of view, and calculating using the following formula. Area ratio of cells with diameters of 5000 μm or more = (Sum of the area of ​​cells with a diameter of 5000 μm or more / field of view area) × 100... (formula).

[0089] As shown in Comparative Example 1 of Table 1, when no cell opener was used, the average sound absorption coefficients at 1000 to 3500 Hz and 1000 to 2000 Hz were extremely small. In this case, the average cell diameter was smaller than in the Examples. As shown in Comparative Example 2, even when a cell opener was used, if the amount used was too large compared to the specified amount, the molding stability of the foam was significantly reduced and it was not possible to mold a foam. As shown in Comparative Example 3, when the surface tension of the foam stabilizer was smaller than the specified value and no cell opener was used, the molded foam shrunk.

[0090] By comparing the above examples and comparative examples, it is clear that in the present invention, when used as a sound-absorbing material for vehicles, a molded body is obtained which has a thin substrate thickness and high sound-absorbing performance over a wide frequency range, and the significance and outstanding excellence of the configuration of the present invention can be understood.

Claims

1. A vehicle sound-absorbing material comprising a flexible polyurethane foam having as its constituent components a polyol component (A) and a polyisocyanate component (B), wherein the polyol component (A) contains a catalyst (C), a foam stabilizer (D), and a blowing agent (E), and at least one of the polyol component (A) and the polyisocyanate component (B) contains a cell breaker (F), the cell breaker (D) having a surface tension of 22 to 28 mN / m@23°C, and the content of the cell breaker (F) is 0.1 to 7.5 mass% relative to the total amount of the polyol component (A) and the polyisocyanate component (B).

2. 2. The vehicle sound-absorbing material according to claim 1, wherein the cell opener (F) is a silicone-based oil, and the number average molecular weight of a polysiloxane component contained in the silicone-based oil is 10,000 to 50,000.

3. 3. The sound-absorbing material for vehicles according to claim 1, wherein the cell opener (F) is contained in the polyol component (A).

4. 2. The vehicle sound-absorbing material according to claim 1, wherein the polyisocyanate component (B) contains diphenylmethane diisocyanate in a range of 50 to 85% by mass, and the total amount of 2,2'-diphenylmethane diisocyanate and 2,4'-diphenylmethane diisocyanate contained in the diphenylmethane diisocyanate is 10 to 50% by mass relative to the total amount of the diphenylmethane diisocyanate.

5. Density: 25 to 200 kg / m ３ The Asker C hardness measured in accordance with JIS K7312 is 20 to 100 points, and the air permeability is 0.1 to 100 cm ３ / cm ２ 2. The sound-absorbing material for vehicles according to claim 1, wherein the sound-absorbing material has a vibration damping ratio of 1 / sec.

6. 2. The sound-absorbing material for vehicles according to claim 1, wherein the average cell diameter is 2000 μm or more, and the area ratio of cells having a diameter of 5000 μm or more is 20% or more.

7. 2. The sound-absorbing material for vehicles according to claim 1, wherein the thickness of the thinnest part is 5.0 to 50 mm.

8. A foam laminate comprising the vehicle sound-absorbing material according to claim 1 and a film, wherein at least one film is disposed in the order of film and vehicle sound-absorbing material relative to a sound source.

9. The foam laminate according to claim 8 , wherein the film is applied to a surface of a sound-absorbing material for a vehicle.

10. 9. The foam laminate according to claim 8, wherein the film is a polyurethane resin film.

11. 11. The foam laminate according to claim 10, wherein the polyurethane resin film is made of an aqueous polyurethane resin emulsion.

12. The foam laminate according to claim 11, wherein a polyol component used as a raw material for the aqueous polyurethane resin emulsion has a carbonate skeleton.

13. The foam laminate according to claim 12, wherein the average functionality of the polyol component having a carbonate skeleton is 2.1 or more.

14. The foam laminate according to any one of claims 8 to 13, characterized in that the thickness of the film is 0.1 to 250 μm, the porosity is 0 to 2.0%, and when the porosity exceeds 0%, the average pore diameter is 300 μm to 1000 μm.

15. 2. A method for producing a foam laminate, wherein the film is coated on the surface of the sound-absorbing material by integral molding with the sound-absorbing material for vehicles according to claim 1.

16. A composition comprising a polyol component (A) and a polyisocyanate component (B) as constituent components, wherein the polyol component (A) contains a catalyst (C), a foam stabilizer (D), and a blowing agent (E), and at least one of the polyol component (A) and the polyisocyanate component (B) contains a cell opener (F), the cell opener (D) having a surface tension of 22 to 28 mN / m@23°C, and the content of the cell opener (F) is 0.1 to 7.5% by mass relative to the total amount of the polyol component (A) and the polyisocyanate component (B).

17. A flexible polyurethane foam comprising a polyol component (A) and a polyisocyanate component (B) as constituent components, wherein the polyol component (A) contains a catalyst (C), a foam stabilizer (D), and a blowing agent (E), and at least one of the polyol component (A) and the polyisocyanate component (B) contains a cell opener (F), the cell opener (D) having a surface tension of 22 to 28 mN / m@23°C, and the content of the cell opener (F) is 0.1 to 7.5% by mass relative to the total amount of the polyol component (A) and the polyisocyanate component (B).