JP2006265467A - Flame-retardant sound-proof/vibration-proof material for vehicles and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame-retardant sound-proof/vibration-proof material for vehicles, which realizes both excellent flame retardance and excellent thermal deterioration resistance, has improved sound-absorbing characteristics in a high frequency region, and lowers the cost. <P>SOLUTION: This flame-retardant sound-proof/vibration-proof material for vehicles, formed from a polyurethane foam produced from an organic polyisocyanate component and a polyol component, is characterized in that the organic polyisocyanate component comprises (A) 75 to 90 wt.% of monomeric MDI comprising 2,4'-diphenylmethanediisocyanate and 4,4'-diphenylmethanediisocyanate, (B) 8 to 24.9 wt.% of a polynuclear isocyanate, and (C) 0.1 to 2 wt.% of a prepolymerized isocyanate, wherein the 2,4'-diphenylmethanediisocyanate is contained in the monomeric MDI in an amount of 28 to 36 wt.%, and the polyol component contains a polyol having two to eight functional groups and a mol.wt. of 1,000 to 10,000 in an amount of ≥50 wt.%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flame-retardant soundproofing / vibration-proof material for a vehicle and a method for producing the same, and in particular, the soundproofing / proofing comprising a flexible polyurethane foam having excellent heat resistance and flame retardancy and excellent sound absorption characteristics. The present invention relates to a vibration material and a technique that can advantageously manufacture such a soundproof / vibration-proof material.

  Conventionally, various types of soundproofing materials have been used in vehicles such as automobiles in order to reduce noise leaking outside the vehicle or in the passenger compartment. For example, in the engine room of a vehicle, the engine that is the source of the noise is used. Around the engine cover, side cover, oil pan cover, under cover, etc., to fix the foam sound such as foamed rubber or urethane foam to rigid members such as metal plates, etc. It is provided in a structure that is damped (see FIG. 1 of Patent Document 1). In addition, since various accessory devices and parts are arranged close to the periphery of the engine body of the vehicle, there is inevitably a gap between the engine body and these devices and parts. However, in such a structure, when the engine is operated, a standing wave is generated in the gap, and this standing wave causes a problem that the engine noise is increased. For this reason, in order to suppress such standing waves and reduce the radiated sound from the engine, in Patent Document 2 and the like, a gap (space) between the engine body and the surrounding devices and parts is used. It has been proposed that a cushioning material made of a foamed material such as foamed rubber or urethane foam is filled as a spacer.

  By the way, the material such as foamed rubber and foamed urethane used as a soundproofing material or a cushioning material as described above has a heat resistance deterioration property and a flame resistance property due to a special condition that it is disposed close to the engine body. Although it is desired to be excellent in both, the EPDM foam conventionally used as foamed rubber has good heat resistance, but has insufficient flame retardancy In addition, in the foam of epichlorohydrin rubber, which is another foam rubber, the flame retardancy is good but the heat deterioration resistance is insufficient.

  As foamed urethane (polyurethane foam) used in the same manner as such foamed rubber, asphalt-impregnated polyurethane foam foamed with asphalt is known as disclosed in Patent Document 3, Patent Document 4, and the like. . Specifically, this asphalt-impregnated polyurethane foam is produced by injecting a composition comprising a polyol, a polyisocyanate, a foaming agent, an amine catalyst, a flame retardant, and asphalt into a predetermined mold and foam-molding the composition. The asphalt-impregnated polyurethane foam thus obtained has a feature of being reasonably inexpensive and excellent in heat resistance, but has a problem of insufficient flame retardancy. However, if the content of the flame retardant in the polyurethane foam is increased, the flame retardancy is improved, but in addition to the inevitable increase in raw material costs, the heat deterioration resistance is reduced and the foam is reduced. Therefore, it is difficult to adopt an embodiment in which the content of the flame retardant is increased.

  Furthermore, in Patent Document 5, a flame retardant-containing flame retardant urethane foam containing a flame retardant obtained using a styrene polymer polyol as a polyol component is clarified, but in combination with a flame retardant, Since it is intended to achieve both the flame retardancy and heat resistance deterioration property of polyurethane foam, its cost reduction has been difficult, and its heat deterioration resistance is evaluated at a temperature of 120 ° C. Therefore, if such a temperature is exceeded, the flame retardant contained in the foam will be scattered, and the flame retardancy will be impaired, and the heat-resistant deterioration characteristics of the polyurethane foam will deteriorate. Was inherent.

  Furthermore, in Patent Document 6, a vehicle vibration-absorbing and sound-absorbing member having excellent vibration damping and sound absorbing properties and water-stopping properties is used, and a polyolefin polyol having a saturated hydrocarbon resin skeleton as a polyol component is used. It has been clarified that it is constituted by a foam (polyurethane foam) obtained by reacting with an organic polyisocyanate component in the presence of a surfactant having a group-containing fatty acid ester skeleton. It has not been clarified as to what means should be adopted for simultaneously imparting excellent flame retardancy and heat deterioration resistance to the foam.

  Under such circumstances, the present inventors, together with other inventors, previously described in Patent Document 7 by using a specific organic polyisocyanate component and a specific polyol component, specifically, organic polyisocyanate. The main component is a monomeric MDI having an NCO content of 29 to 33%, which includes diphenylmethane diisocyanate and its carbodiimide modified product and / or its uretonimine modified product, and contains 1 to 1 in the monomeric MDI. While using 45% by weight of 2,4′-diphenylmethane diisocyanate as a monomer and / or modified component, the polyol component has a functional group number of 2 to 8 and a molecular weight: What contains 1000-10000 polyol in the ratio of 50 weight% or more By there, without using a flame retardant, and maintain excellent physical properties before and after heat aging test, and non-flammable, flexible polyurethane foams having excellent moldability revealed that the obtained.

  Thus, in the soundproofing / vibration-proofing material composed of the flexible polyurethane foam as described above, a carbodiimide-modified product of diphenylmethane diisocyanate and / or a uretonimine-modified product (hereinafter referred to as a carbodiimide-modified product) is used as a raw material. ) Can be effectively imparted with flame retardancy, and the cost can be advantageously reduced as compared with the case where a large amount of a conventional flame retardant is blended. Such a modified body such as a carbodiimide modified body still has a higher raw material cost than other polyisocyanate compounds, and therefore further cost reduction has been demanded.

JP 2000-220467 A Japanese Utility Model Publication No.59-7545 Japanese Examined Patent Publication No. 57-22051 Japanese Patent Publication No. 61-50965 JP-A-7-233236 JP-A-10-81142 JP 2003-97645 A

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is to realize both excellent flame retardancy and excellent heat deterioration resistance, and in the high frequency region. It is intended to provide a flame retardant soundproofing / vibration-proof material for vehicles that has improved sound absorption characteristics and further reduced costs, and is advantageous for soundproofing / vibration-proofing materials having such excellent characteristics. It is to provide a method that can be manufactured.

  And, as a result of intensive studies to solve such problems, the present inventors, as a result, the specific polyisocyanate component and the specific polyol component filed earlier without using a carbodiimide-modified product having a high raw material cost. In particular, it has been found that the sound absorption characteristics in the high frequency region can be advantageously improved by replacing the constituent components of the polyisocyanate component.

Accordingly, the present invention has been completed based on such knowledge, and the first aspect thereof is a flexible polyurethane foam obtained by reacting and foaming an organic polyisocyanate component and a polyol component. And (A) 75 to 90% by weight of a monomeric MDI containing 2,4′-diphenylmethane diisocyanate and 4,4′-diphenylmethane diisocyanate. (B) 8 to 24.9% by weight of the polynuclear isocyanate and (C) 0.1 to 2% by weight of the prepolymerized isocyanate, and 28% in the monomeric MDI, Containing 2,4′-diphenylmethane diisocyanate in a proportion of ˜36% by weight, while the polyol component is a functional group : 2-8, the molecular weight: 1,000 to 10,000 of polyol contains at a rate of more than 50 wt%, are used, further the polyurethane foam, the density of 30~70kg / m ^3, 50% compressive load value (5-60) × 10 ⁻² N / mm ² , tensile strength is 120 kPa or more, elongation is 100% or more, and FMVSS-302 flammability test method before and after heat aging test at 160 ° C. × 72 hours It is a flame retardant soundproofing / vibration-proof material for vehicles characterized by exhibiting nonflammability.

  In addition, in the desirable second aspect relating to the flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention, the NCO content of the organic polyisocyanate component is adjusted to 31.0-33.5%. It will be.

  Moreover, in the third aspect of the flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention, the polyurethane foam has a tensile strength and elongation rate after a heat aging test of 160 ° C. × 72 hours, It has the characteristic which is 50% or more of the value before this test.

  Furthermore, in the fourth aspect of the flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention, the polynuclear isocyanate is polymeric MDI composed of crude MDI having three or more benzene rings in the molecule, The configuration in which the polynuclear isocyanate is used in the organic polyisocyanate component in a proportion of 8.5 to 19.5% by weight is suitably employed.

By the way, the present invention is also directed to a method for producing a flame-retardant soundproofing / vibration-proof material for vehicles, and is a soft polyurethane obtained by reacting and foaming an organic polyisocyanate component and a polyol component. When producing the desired soundproofing / vibration-proof material in the form of foam, a monomeric MDI containing (A) 2,4′-diphenylmethane diisocyanate and 4,4′-diphenylmethane diisocyanate as the organic polyisocyanate component 90% by weight, (B) 8 to 24.9% by weight of the polynuclear isocyanate, and (C) 0.1 to 2% by weight of the prepolymerized isocyanate, and in the monomeric MDI, While using a composition containing 2,4'-diphenylmethane diisocyanate in a proportion of 36% by weight, As the real component, a component comprising a polyol having a functional group number of 2 to 8 and a molecular weight of 1000 to 10000 in a proportion of 50% by weight or more is used. The organic polyisocyanate component and the polyol component have an NCO / OH index of 0. The density is 30 to 70 kg / m ³ , the 50% compression load value is (5 to 60) × 10 ⁻² N / mm ² , and the tensile strength is 120 kPa. As described above, the flexible polyurethane foam having an elongation of 100% or more and showing nonflammability by the FMVSS-302 flammability test method before and after the heat aging test at 160 ° C. for 72 hours is formed. The first aspect is a characteristic method for producing a flame-retardant soundproofing / vibration-proof material for vehicles.

  In the second preferred embodiment of the method for producing a flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention, the reaction between the organic polyisocyanate component and the polyol component is performed in the presence of a foaming agent. The polyurethane foam will be formed.

  And according to the first aspect described above in the flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention, the polyurethane foam that provides the flame-retardant soundproofing / vibration-proofing material for vehicles has a specific organic polyisocyanate component and It has a great feature in that it is formed by using specific polyol components and reacting them, where the activity and crosslinking properties of organic polyisocyanate components and the activity and crosslinking properties of polyol components With the effective balance, the flexible polyurethane foam that maintains excellent physical properties before and after the heat deterioration test, has good nonflammability (combustion resistance), and excellent sound absorption characteristics. It was possible to get.

  In particular, in the present invention, as the organic polyisocyanate component, (A) monomeric MDI containing 2,4′-form and 4,4′-form of diphenylmethane diisocyanate (MDI) in a specific ratio, B) A polynuclear isocyanate having three or more aromatic rings (nuclei) in the molecule and (C) a prepolymerized isocyanate are used in combination at a specific blending ratio. As a result, the sound absorption characteristics in the high-frequency region, particularly in the region of 1000 Hz or higher, can be advantageously improved. In addition, the heat-resistant deterioration characteristics of the foam are effectively improved, and even if the flame comes into contact with the foam, the foam melts away by heat, and the non-flammable characteristics that prevent the flame from propagating are flame retardants. And carbodiimide modified products can be effectively imparted without requiring blending.

  Therefore, in the present invention, in order to make the target vehicle soundproofing / vibration-proof material nonflammable, it is not necessary to include any flame retardant in the foam to which it is provided, and further, a modified carbodiimide, etc. Since various problems caused by the incorporation of a large amount of flame retardant as in the prior art can be advantageously eliminated, and the cost of the product can be extremely effectively reduced. is there.

  In addition, according to the above-mentioned 2nd aspect of the flame-retardant soundproofing / vibration-proof material for vehicles according to this invention, the characteristic of this invention will be exhibited more advantageously.

  Further, in the third aspect of the vehicle flame-retardant soundproofing / vibration-proof material according to the present invention, very excellent heat aging resistance is imparted.

  In addition, according to the above-described fourth aspect of the flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention, a polynuclear isocyanate adopting a crude MDI having three or more benzene rings in the molecule, such a polynuclear If the content of the isocyanate is adjusted, the object of the present invention will be realized more advantageously.

  Further, according to the method for manufacturing a flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention, the flame-retardant soundproofing / vibration-proofing material for vehicles having the excellent characteristics as described above can be formed with good moldability. In addition, it is easy to manufacture, and it is possible to form a soundproof / vibration-proof material at low cost.

  Furthermore, in the second method for producing a flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention, the reaction of polyurethane formation and foaming can be realized at the same time, and the soundproofing / vibration-proofing material comprising the desired polyurethane foam However, it can be effectively molded.

  By the way, in this invention, as an organic polyisocyanate component which is one of the reaction components for forming the flexible polyurethane foam which gives the target flame-retardant soundproofing and vibration-proof material for vehicles, as (A) 2,4 75-90% by weight of monomeric MDI containing '-MDI and 4,4'-MDI, (B) 8-24.9% by weight of polynuclear isocyanate, and (C) 0.1% of prepolymerized isocyanate. And 2% by weight of 2,4′-MDI contained in the monomeric MDI in a proportion of 28 to 36% by weight.

  Here, the monomeric MDI (component A) constituting the organic polyisocyanate component is a combination of MDI isomers 2,4′-form and 4,4′-form, In the present invention, it is necessary that 2,4′-MDI is contained in such a monomeric MDI in a proportion of 28 to 36% by weight. When the content of 2,4′-MDI in the monomeric MDI exceeds 36% by weight, the sound absorption characteristics in the high frequency region are deteriorated and the moldability and other characteristics are also deteriorated. In addition, when the content of 2,4′-MDI in the monomeric MDI is less than 28% by weight, the physical properties are deteriorated and the moldability is also deteriorated.

  In the present invention, the monomeric MDI containing the 2,4′-form and the 4,4′-form as described above is 75 to 90 wt%, preferably 80 to 90 wt% in the organic polyisocyanate component. It is made to contain in the ratio of%. In addition, if the content of the monomeric MDI in the organic polyisocyanate component is too small, the resulting foam tends to burn easily, and if too much, the combustion resistance is ensured well, Practical normal physical properties are difficult to obtain.

  As the polynuclear isocyanate (B component) constituting the organic polyisocyanate component, various known polyisocyanate compounds having three or more aromatic rings (nuclei) in the molecule are appropriately selected and used. In particular, in the present invention, polymeric MDI composed of crude MDI having 3 or more benzene rings (and thus having 3 or more NCO groups) among them is preferably used. Become. The upper limit of the number of nuclei (number of benzene rings) in the crude MDI molecule is not particularly limited, but is generally about 6, and in the present invention, such number of nuclei (3-6) ) Is advantageously employed. Then, by utilizing the cross-linking characteristics of such polynuclear isocyanate, a foaming reaction is performed to form a target polyurethane foam.

  In the present invention, such a polynuclear isocyanate is contained in the organic polyisocyanate component in an amount of 8 to 24.9% by weight, preferably 8.5 to 19.5% by weight. . When the content of the polynuclear isocyanate in the organic polyisocyanate component is less than 8% by weight, it becomes difficult to improve the properties such as heat aging resistance of the polyurethane foam, whereas 24.9% by weight. If it exceeds the range, the combustion resistance is lowered and it becomes easy to burn.

  Furthermore, the prepolymerized isocyanate (C component) constituting the organic polyisocyanate component is obtained by reacting a polyisocyanate compound with a polyol according to a conventionally known method, and has two or more, preferably three NCO groups. Examples thereof include the prepolymerized isocyanate having three urethane bonds obtained by reacting the above-mentioned MDI with a trifunctional polyol. In particular, in the present invention, an isocyanate-terminated prepolymer formed by reacting a trifunctional ether-based polyol with MDI is suitably employed. Here, the trifunctional ether-based polyol is not particularly limited, and for example, a molecular weight of about 6000, which is formed by bonding three polyether groups (having an OH group at the end) having a molecular weight of about 2000. These polyols can be mentioned. By including such prepolymerized isocyanate, the crosslinked form of the foam is improved, and properties such as heat aging resistance are improved.

  In the present invention, such prepolymerized isocyanate is contained in the organic polyisocyanate component in a proportion of 0.1 to 2% by weight, preferably 0.5 to 1.5% by weight. . When the content of the prepolymerized isocyanate in the organic polyisocyanate component is less than 0.1% by weight, the resulting polyurethane foam tends to sag. When the weight percentage is exceeded, deterioration of combustion resistance is caused.

  Thus, the organic polyisocyanate component contains the components A, B and C as described above in the proportions of 75 to 90% by weight, 8 to 24.9% by weight and 0.1 to 2% by weight, respectively. What has been done will be used. In the present invention, those composed only of these A component, B component and C component can be advantageously employed as the organic polyisocyanate component. However, the useful action and effect of the present invention are adversely affected. As long as there is no limit, those obtained by further blending other known polyisocyanate compounds other than the A component, B component and C component can be used.

  In the present invention, the NCO content of the organic polyisocyanate component composed of such various polyisocyanate compounds is within the range of 31.0 to 33.5% on a weight basis. It has been prepared. This is because if the NCO content of such an organic polyisocyanate component is lower than 31.0%, the foam may easily burn, and the realization of a ratio exceeding 33.5% When adopting the above-mentioned blending ratio, it is difficult.

  As described above, in the present invention, the resin (polyurethane foam) obtained by using the organic polyisocyanate component containing the components A to C as described above in a special blending ratio is excellent. In addition to realizing heat-resistant deterioration characteristics, it exhibits the feature that it does not burn before and after the heat-resistant deterioration test without using a flame retardant or a modified carbodiimide. Here, the fact that it does not burn is a judgment result based on the FMVSS (Federal Motor Vehicle Safety Standards) -302 test standard. Is melted away by heat, and the flame does not propagate, so the determination is “non-combustible”. That is, since the speed at which the foam melts is faster than the speed at which the flame propagates, the polyurethane foam obtained according to the present invention has the property of not burning. Moreover, in the polyurethane foam according to the present invention thus obtained, good sound absorption characteristics in the high frequency region, specifically, the sound absorption rate in the region of 1000 Hz or more is 0.9 or more. , There is a big feature.

  On the other hand, in the present invention, as a polyol component that reacts with such an organic polyisocyanate component to form a target polyurethane foam, a polyol having a functional group number of 2 to 8 and a molecular weight of 1000 to 10,000 is a ratio of 50% by weight or more. In this way, the polyurethane-forming reaction with the organic polyisocyanate component described above can be effectively carried out, and a nonflammable flexible polyurethane foam can be advantageously formed. In addition, when the number of functional groups of such a polyol is less than 2, chain reaction with the organic polyisocyanate component is interrupted, resulting in problems such as difficulty in forming a polymer and impossible to form a foam, On the other hand, when the number of functional groups exceeds 8, problems such as extremely reduced elongation of the resulting foam are caused. If a polyol having a molecular weight of less than 1000 is used, the foam becomes hard and loses elasticity, making it difficult to obtain the properties of a flexible foam. If a polyol having a molecular weight exceeding 10,000 is used, the viscosity increases, and It makes the reaction with the isocyanate component and the foaming process difficult. Then, by making the polyol having the number of functional groups and molecular weight occupy a ratio of 50% by weight or more of the polyol component, the reaction with the organic polyisocyanate component that gives the target polyurethane foam is advantageously advanced. To get.

  In addition, as such a polyol having the number of functional groups and molecular weight, those conventionally known can be appropriately selected and used. For example, polyhydric hydroxy compounds, polyether polyols, polyester polyols, polymer polyols can be used. , Polyether ester polyols, polyether polyamines, polyester polyamines, alkylene polyols, urea dispersed polyols, melamine modified polyols, polycarbonate polyols, acrylic polyols, polybutadiene polyols, phenol modified polyols, etc. It is selected from various known polyols and used alone or in combination.

And the flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention is a flexible polyurethane foam obtained by reacting and foaming a specific organic polyisocyanate component and a specific polyol component as described above. In particular, the flexible polyurethane foam has a density of 30 to 70 kg / m ³ and a 50% compression load value (at the time of 50% compression) in order to be advantageously used as a soundproof / vibration-proof material for vehicles. The load per unit area: ASTM-D-3574) is (5-60) × 10 ⁻² N / mm ² , the tensile strength is 120 kPa or more, and the elongation is 100% or more. Become.

In such a flexible polyurethane foam, if the foam density is less than 30 kg / m ³ , the physical properties, in particular, the strength is insufficient, and it becomes unsuitable for the use of the present invention, and if it exceeds 70 kg / m ³ , This causes a problem that the sound absorption characteristics in the region deteriorate. Further, the 50% compressive load value indirectly indicates the hardness of the polyurethane foam, and when it becomes lower than 5 × 10 ⁻² N / mm ² , such foam is used as a gap filling member. At this time, there is a problem that it is difficult to fit into such a gap, or the drop-out from the gap is likely to occur, and in the case of hardness exceeding 60 × 10 ⁻² N / mm ^2. However, it becomes too hard and it becomes difficult to fill the gap, and the problem of not being able to sufficiently exhibit the soundproofing effect is caused. Furthermore, if the tensile strength or elongation rate is too low, the product may be destroyed when it is installed as a product in a predetermined place, and the shape cannot be maintained until the end of the vehicle life. From the point of causing problems, the tensile strength and elongation must be equal to or greater than the specified values described above.

  In addition, such polyurethane foam has excellent characteristics as described above by an appropriate balance between the activity and crosslinking characteristics of the specific organic polyisocyanate component as described above and the activity and crosslinking characteristics of the polyol component described above. It will be a thing.

  Further, such a polyurethane foam advantageously has a characteristic that the tensile strength and elongation after the heat aging test at 160 ° C. for 72 hours are both 50% or more of the values before the test. It is desirable to be prepared. As described above, by maintaining excellent physical properties before and after the heat resistance deterioration test, the function as a vehicle soundproofing / vibrationproofing material can be exhibited for a longer period of time.

  Further, when producing the flame-retardant soundproofing / vibration-proof material for vehicles according to the present invention, the specific organic polyisocyanate component and the specific polyol component described above are reacted and foamed in a suitable foaming mold. Thus, a soundproofing / vibration-proofing material comprising a polyurethane foam (foam) having a desired shape can be formed. In this case, a known catalyst is used for the organic polyisocyanate component or polyol component as in the conventional case. In addition, a crosslinking agent, a foaming agent, a foam stabilizer, a chain extender, a viscosity reducing agent, and the like can be appropriately added as additives.

  As the catalyst, known amine catalysts, organometallic catalysts, and the like are used. Specifically, bis (dimethylaminoethyl) ether, pentamethyldiethylenetriamine, N, N-dimethylcyclohexylamine, N, N— Dimethylethanolamine, N, N, N ′, N′-tetramethylhexamethylenediamine, N, N, N ′, N′-tetramethylpropylenediamine, N, N, N ′, N′-tetramethylethylenediamine, tri Examples include ethylenediamine, N-methyl-N ′-(dimethylamino) ethylpiperazine, N-methylmonoforin, N-ethylmonoforin, triethylamine, and the like, and examples of organometallic catalysts include tin laurate and tin octoate. Etc. can be mentioned.

As the foaming agent, known water is preferably used. However, other than water, methylene chloride, chlorofluorocarbon, CO ₂ gas, and the like can also be used as the foaming agent. The amount of the foaming agent used is determined empirically so as to obtain the density as described above, and is used in an amount similar to the amount used in the production of a conventional polyurethane foam. For example, in the case of water as a blowing agent, it is generally used in a ratio of about 1 to 6 parts by weight with respect to 100 parts by weight of the polyol component.

  Furthermore, the cross-linking agent is appropriately selected from small cross-linking agents having a relatively low molecular weight depending on the hardness. For example, diol, triol, polyvalent amine, or ethylene oxide or propylene oxide is added to these. And the like, triethanolamine, diethanolamine and the like. In addition, as a foam stabilizer, a typical silicone foam stabilizer for producing polyurethane foams can be cited as typical examples thereof. For example, SRX-274C manufactured by Toray Dow Corning Co., Ltd., manufactured by Nihon Unicar Co., Ltd. No. L-5390, SZ1313, B-4113 manufactured by Goldschmidt, Inc., and the like are commercially available.

  In addition to the above-described blending components, flame retardants, fillers, antistatic agents, colorants, stabilizers, etc., as required, do not depart from the purpose of the present invention, depending on the performance required for the foam. To some extent, it will be added.

  When producing the desired polyurethane foam, usually, a predetermined amount of water, a catalyst, a foam stabilizer and other auxiliaries as foaming agents are mixed in advance with the specific polyol component described above. Then, using the prepared resin premix (premix polyol), a specific organic polyisocyanate component as described above is mixed and reacted, and further foamed. Specifically, such a resin premix and an organic polyisocyanate component are mixed using a known urethane foaming machine with an NCO / OH index (equivalent ratio) of 0.6 to 1. 2 and preferably 0.7 to 1.1, more preferably 1 in a ratio, and the mixture is poured into a predetermined mold, reacted and foamed to form a polyurethane foam of the desired shape. It is.

  In the reaction between the organic polyisocyanate component and the polyol component, if the NCO / OH index is less than 0.6, there is a problem that the physical properties are deteriorated, and if it exceeds 1.2, the crosslinking reaction proceeds. As a result, the foam easily burns, the curing property is poor, and the foam is poorly moldable.

  The flexible polyurethane foam thus obtained can be advantageously used as a flame-retardant soundproofing / vibration-proof material according to the present invention. For example, the flexible polyurethane foam is disposed around the engine in the engine room of a vehicle. Used to reduce engine noise, engine cover, side cover, oil pan cover, under cover, hood silencer, dashboard silencer, etc. It is advantageously used as a spacer that fills the space formed between them and suppresses standing waves generated therebetween.

  Examples of the present invention will be shown below to clarify the present invention more specifically. However, the present invention is not limited by the description of such examples. Needless to say. In addition to the following examples, the present invention includes various descriptions based on the knowledge of those skilled in the art without departing from the gist of the present invention, in addition to the descriptions in the embodiments of the present invention described above. It should be understood that other changes, modifications, improvements, etc. may be made.

First, PPG (manufactured by Sanyo Chemical Industries, Ltd., average molecular weight = 5000, functional group number = 3) is used as a polyol component, and 100 parts by weight of diethylene glycol (DEG) as a crosslinking agent and water as a blowing agent. , Amine catalyst (manufactured by Kao Corporation, triethylenediamine), silicone-based foam stabilizer (manufactured by Nihon Unicar Co., Ltd., viscosity: 50 mm ² / s, surface tension: 25.7 mN / m), pigment (Daiichi Seika Kogyo Co., Ltd.) Manufactured carbon black 30% + PPG 70%) in the proportions shown in Table 1 below to prepare premix polyols.

  On the other hand, as the polyisocyanate, 4,4'-MDI and 2,4'-MDI, or three kinds of commercially available products having different composition compositions of crude MDI (polynuclear isocyanate) and prepolymerized MDI are used. The organic polyisocyanate components (compositions) according to Invention Examples 1 to 3 and Comparative Examples 1 and 2 having the compositions shown in Table 2 below were prepared by appropriately selecting and combining at a predetermined ratio. did. In addition, as the prepolymerized MDI, a prepolymer (molecular weight: about 6000) of trifunctional ether-based polyol and MDI was used.

  Next, using the prepared premix polyol and various organic polyisocyanate components, the premix polyol (POL) and various organic polyisocyanate components (ISO) are each adjusted so that the NCO / OH index is 0.8. And POL: ISO = 60: 40 at a weight ratio. After that, by pouring into a predetermined mold (mold) at a raw material temperature: 22 ° C., and foaming and curing at a mold temperature: 52 ° C. and a curing time: 5 minutes, a size of 120 mm × 120 mm × 60 mm is obtained. Various polyurethane foams (Invention Examples 1 to 3 and Comparative Examples 1 and 2) were obtained.

  The various polyurethane foams thus obtained were measured for their density, 50% compressive load value, tensile strength (TB) and elongation (EB), and the results are shown in Table 3 below. In addition, a 50% compressive load value is measured based on ASTM-D-3574.

  Further, for such polyurethane foam, each flammability is evaluated based on the FMVSS-302 flammability test method, and the sound absorption coefficient is 1000 Hz or more according to the “normal incidence sound absorption coefficient method” based on JIS-A-1405. The average values were obtained and the measured values obtained were also shown in Table 3 below. And in FIG. 1, the sound absorption coefficient measurement result about the polyurethane foam which concerns on Example 1 of this invention and the comparative example 1 is shown in the relationship between a frequency and a sound absorption coefficient. In addition, the evaluation of the flammability by the FMVSS-302 flammability test method is carried out by holding the foam sample horizontally, applying a burner flame to one end of the foam sample for 15 seconds, and then evaluating the flammability after removing the flame. When the foam sample immediately self-extinguishes after evaluation according to the test method and removal of such a flame, it was judged as “pass”.

  Further, the polyurethane foam was subjected to a heat aging test at 160 ° C. for 72 hours, and then subjected to a flammability test for each polyurethane foam. The obtained results are shown in Table 3 below, and heat aging is also performed. The tensile strength and elongation of each polyurethane foam after the test were measured. And the ratio of the tensile strength and elongation after a heat-aging aging test with respect to the tensile strength and elongation at the normal state was calculated, respectively, and is shown in Table 3 below as TB retention (%) and EB retention (%). . Further, the heat aging resistance was evaluated from the values of the TB retention rate (%) and the EB retention rate (%), and the results are shown in Table 3 below. The evaluation criteria are: ◎: TB retention and EB retention are both 70% or more, ○: TB retention and EB retention are both 60% or more, and Δ: TB retention and EB retention are both 50% or more. X: TB retention and EB retention were both less than 50%.

  Furthermore, in Table 3 below, for the moldability of each of the above polyurethane foams, the evaluation results from the viewpoint of the presence or absence of cavities and shrinkage and the state of cure, and the measurement results of the air flow rate according to ASTM-D-1564-71, It is also shown. The formability (cavity) in Table 3 was evaluated as “◯” when the presence of voids was not recognized inside the polyurethane foam, and “X” when recognized, and the moldability (shrinkage) was evaluated as polyurethane foam. In the case where deformation of the appearance is not recognized, it is evaluated as ○, and in the case where deformation is observed, it is evaluated as ×, and the moldability (cure) is foamed after demolding after 5 minutes from the raw material injection. If the foam returns to its original state even after pressing down (confirmation that the curing is completely completed), it is evaluated as ◯, and when it does not return, it is evaluated as x.

  As is apparent from the results of Table 3 and FIG. 1, when the same polyol component (functional group number: 3, molecular weight: 5000) is used, 4,4′-MDI, 2,4 is used as the organic polyisocyanate component. In the polyurethane foams according to Examples 1 to 3 of the present invention obtained by using ′ -MDI, crude MDI, and prepolymerized MDI at the specific blending ratio as described above, all of them are excellent in difficulty. It is provided with flammability and excellent heat deterioration resistance, and furthermore, the sound absorption rate of 1000 Hz or more, in other words, the sound absorption property in the high frequency region can be effectively enhanced. -It turns out that it can be used advantageously as a vibration isolator.

  On the other hand, in the polyurethane foam of Comparative Example 1 having a large content of 2,4′-MDI in the monomeric MDI, as apparent from FIG. The rate is not enough. In Comparative Example 2, it is recognized that in addition to the moldability, the normal physical properties are inferior.

  First, as a polyol component, PPG (1) (manufactured by Sanyo Chemical Industries, average molecular weight = 5000, functional group number = 3), polymer polyol (manufactured by Asahi Denka Kogyo Co., Ltd., average molecular weight = 6000, functional group number = 3), PPG (2) (manufactured by Sanyo Chemical Industries, average molecular weight = 6000, number of functional groups = 4) or PPG (3) (manufactured by Sanyo Chemical Industries, Ltd., average molecular weight = 7000, number of functional groups = 4), 100 With respect to parts by weight, diethylene glycol (DEG) as a crosslinking agent, water as a blowing agent, amine catalyst (manufactured by Kao Corporation, triethylenediamine), silicone-based foam stabilizer (manufactured by Nihon Unicar Corporation), pigment (Daiichi Chemical Black Co., Ltd., carbon black) was blended in the proportions shown in Table 4 below, and 5 types of premixed polyols were added. The a~e was prepared.

  Next, using the prepared premix polyols a to e and the organic polyisocyanate component according to Example 1 of the present invention in Example 1, the premix polyol (POL) was adjusted so that the NCO / OH index was 0.8. ) And the organic polyisocyanate component (ISO) were mixed in a weight ratio of approximately POL: ISO = 60: 40. After that, by pouring into a predetermined mold (mold) at a raw material temperature: 22 ° C., and foaming and curing at a mold temperature: 52 ° C. and a curing time: 5 minutes, a size of 120 mm × 120 mm × 60 mm is obtained. Various polyurethane foams were obtained.

  The various polyurethane foams thus obtained were subjected to measurement of normal physical properties, flammability test, and property evaluation after heat aging as in Example 1 above, while measuring sound absorption rate. As a result, it was confirmed that all the polyurethane foams had excellent sound absorption characteristics in the high frequency region as well as excellent physical properties and combustion resistance.

4 is a graph showing the measurement results of the sound absorption coefficient of the polyurethane foam obtained in Example 1.

Claims (6)

A soundproofing and vibration isolating material composed of a flexible polyurethane foam obtained by reacting and foaming an organic polyisocyanate component and a polyol component,
The organic polyisocyanate component is (A) 75 to 90% by weight of monomeric MDI containing 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate; and (B) 8 to 24.9 of polynuclear isocyanate. And (C) 0.1 to 2% by weight of the prepolymerized isocyanate, and in such a monomeric MDI at a ratio of 28 to 36% by weight, 2,4′- While the diphenylmethane diisocyanate is contained, the polyol component contains a polyol having a functional group number of 2 to 8 and a molecular weight of 1000 to 10000 in a ratio of 50% by weight or more, and the polyurethane foam has a density thereof. There 30~70kg / m ^3, 50% compressive load value ^{(5~60) × 10 -2 N /} mm 2 A flame retardant for a vehicle having a tensile strength of 120 kPa or more, an elongation of 100% or more, and exhibiting nonflammability by the FMVSS-302 flammability test method before and after a heat aging test at 160 ° C. for 72 hours. Soundproof and vibration-proof material.   The flame-retardant soundproofing / vibration-proof material for vehicles according to claim 1, wherein an NCO content of the organic polyisocyanate component is adjusted to 31.0 to 33.5%.   The tensile strength and elongation rate of the polyurethane foam after a heat aging test at 160 ° C. for 72 hours are both 50% or more of the value before the test. Item 3. A flame-retardant soundproofing / vibration-proof material for vehicles according to Item 2.   The polynuclear isocyanate is a polymeric MDI made of crude MDI having 3 or more benzene rings in the molecule, and the polynuclear isocyanate is 8.5 to 19.5% by weight in the organic polyisocyanate component. The flame-retardant soundproofing / vibration-proof material for vehicles according to any one of claims 1 to 3, which is used in proportion. In producing a desired soundproofing / vibration-proof material in a flexible polyurethane foam obtained by reacting and foaming an organic polyisocyanate component and a polyol component,
As the organic polyisocyanate component, (A) 75 to 90% by weight of monomeric MDI containing 2,4′-diphenylmethane diisocyanate and 4,4′-diphenylmethane diisocyanate, and (B) 8 to 24.9 of polynuclear isocyanate. 2,4′-diphenylmethane diisocyanate in a proportion of 28 to 36% by weight in such a monomeric MDI, and 0.1 to 2% by weight of (C) prepolymerized isocyanate. On the other hand, as the polyol component, those comprising a polyol having a functional group number of 2 to 8 and a molecular weight of 1000 to 10,000 in a proportion of 50% by weight or more are used, and these organic polyisocyanate component and polyol component are used. So that the NCO / OH index is 0.6 to 1.2 To, by reacting a density of 30~70kg / m ^3, 50% compressive load value ^{(5~60) × 10 -2 N /} mm 2, a tensile strength of more than 120 kPa, with elongation of 100% or more A flame retardant soundproofing for a vehicle, characterized in that the flexible polyurethane foam exhibiting incombustibility is formed by the FMVSS-302 flammability test method before and after a heat aging test at 160 ° C. for 72 hours. -Manufacturing method of vibration isolator. The method for producing a flame-retardant soundproof / vibration-proof material for a vehicle according to claim 5, wherein the polyurethane foam is formed by performing the reaction between the organic polyisocyanate component and the polyol component in the presence of a foaming agent. .