Polyurethane foam and method for producing same

Abstract

A polyurethane foam in which the porosity of at least one of the main surfaces facing each other is 0-1.0%, the root mean square surface roughness of the main surface having the porosity in accordance with JIS B 0601: 1994 is 0.01-0.30 [mu] m, and the air permeability in accordance with JIS K6400 is 0-2.0 cm3 / cm2 / sec.

Description

Technical Field

[0001] The invention relates to polyurethane foam with excellent sound absorption and insulation performance and a preparation method thereof. Background Art

[0002] Polyurethane foam is widely used in daily necessities, automobile interior materials, clothing, sports and leisure products, medical materials, civil engineering and construction materials, etc. In such application fields, especially in transportation machinery such as automobiles and buildings such as houses, it is required to further reduce noise by improving the performance of noise-proof materials such as sound absorbing materials and sound insulating materials.

[0003] Especially in the automotive field, with the application of the prescribed values ​​of the regulations on exterior noise and the trend of gradually strengthening the regulations in the future, reducing the sound in the low and medium frequency range (500-1200Hz) such as the engine transmission sound and the radiated sound from the tires is an urgent technical issue, and the demand for sound-absorbing and insulating materials is increasing. In response to these requirements, although it is relatively easy to improve the noise reduction performance and vibration absorption performance by increasing the thickness of the substrate, when the substrate is thicker, it may not be possible to ensure sufficient space in transportation machinery or buildings. Therefore, it is necessary to reduce the thickness of the substrate while improving the sound-absorbing and insulating performance.

[0004] Various attempts have been made in the past to improve the sound absorption and insulation performance. For example, Patent Documents 1 and 2 have studied the improvement of the sound absorption and insulation performance by laminating a resin film on a porous material such as polyurethane foam.

[0005] However, when using a resin film with high releasability (easy releasability) from polyurethane foam, such as a polypropylene film or a polyethylene film, it is necessary to overlap the film on the polyurethane foam and heat and melt-bond it by pressurizing with a hot plate using release paper or the like, so that the increase in manufacturing cost and manufacturing man-hours becomes a technical problem. In addition, when using a resin film such as polyurethane with low releasability from polyurethane foam, since it can be integrally molded in a hard mold (mold), it is not necessary to perform melt bonding, but it is necessary to arrange the film in the mold each time, and the manufacturing cost and manufacturing man-hours increase similarly to the easy releasable film.

[0006] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 1998-119220 Patent Document 2: Japanese Patent Application Publication No. 2005-263118 Summary of the invention

[0007] Technical problem to be solved by the invention The present invention has been completed in view of the above-mentioned background technology, and its purpose is to provide a polyurethane foam and a method for producing the same, wherein the polyurethane foam, when used as a sound absorbing material / sound insulating material, can have high noise reduction performance especially in the low / mid-frequency range even if the base material is thin.

[0008] Technical solutions for solving technical problems The present invention provides [1] to

[17] .

[0009] [1] A polyurethane foam having an air permeability of 0 to 2.0 cm as measured in accordance with JIS K6400 3 / cm 2 / sec, the open porosity of at least one of the upper and lower surfaces in the foaming direction is 0 to 1.0%, and the root mean square surface roughness described in JIS B 0601:1994 on the same surface as the surface for measuring the open porosity is 0.01 to 0.30 μm.

[0010] That is, a polyurethane foam, wherein the open porosity of at least one of the main surfaces facing each other is 0 to 1.0%, and the root mean square surface roughness of the main surface having the open porosity is 0.01 to 0.30 μm according to JIS B 0601:1994, and the air permeability of the polyurethane foam according to JIS K6400 is 0 to 2.0 cm 3 / cm 2 / sec.

[0011] [2] The polyurethane foam according to [1], wherein the polyurethane foam has an Asker C hardness of 20 to 100 points as measured in accordance with JIS K7312.

[0012] [3] The polyurethane foam according to [1] or [2], 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.

[0013] [4] The polyurethane foam according to any one of [1] to [3], wherein the thickness of the thinnest part of the polyurethane foam is 5.0 to 50 mm.

[0014] [5] A method for producing a polyurethane foam as described in any one of [1] to [4], which is a method for producing a polyurethane foam obtained by pre-arranging a film containing a resin having an SP value of 10 or less on at least one inner side of a lower mold or an upper mold of a mold and molding the film by mold forming, wherein the film is peeled off from the polyurethane foam to obtain the polyurethane foam.

[0015] That is, the method for producing a polyurethane foam according to any one of [1] to [4], wherein the polyurethane foam is molded in a state where a film made of a resin having an SP value of 10 or less is arranged on the inner surface of at least one of a pair of dies constituting the mold, and the film is peeled off.

[0016] [6] The method for producing a polyurethane foam according to [5], wherein the resin having an SP value of 10 or less is a polyolefin resin.

[0017] [7] The method for producing a polyurethane foam according to [5], wherein the resin having an SP value of 10 or less is polyethylene or polypropylene.

[0018] [8] The production method according to any one of [5] to [7], wherein a mold release agent having a melting point of 60 to 100° C. is disposed between the film and the mold, and the mold molding is performed.

[0019] [9] The method for producing a polyurethane foam according to any one of [1] to [4], wherein A mold release agent having a melting point of 70 to 90° C. is disposed on the inner surface of at least one of a pair of molds constituting the mold, and mold molding of the polyurethane foam is performed without disposing a film on the surface on which the mold release agent is disposed.

[0020]

[10] The method for producing a polyurethane foam according to any one of [1] to [4], wherein a film containing a resin is preliminarily arranged on at least one inner surface of a lower mold or an upper mold of a mold, and the polyurethane foam is obtained by mold molding.

[0021] That is, the method for producing a polyurethane foam according to any one of [1] to [4], wherein the mold forming of the polyurethane foam is performed in a state where a film containing a resin is arranged on the inner surface of at least one of a pair of dies constituting the mold.

[0022]

[11] The production method according to any one of [5] to

[10] , wherein the temperature of the pair of molds is set to 30 to 80° C. to perform mold molding of the polyurethane foam.

[0023]

[12] The method for producing a polyurethane foam according to any one of [5] to

[11] , which is a method for producing a polyurethane foam by reacting and foaming a polyurethane foam molding composition comprising 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). At least one of the polyol component (A) and the polyisocyanate component (B) contains a defoaming agent (F), and the content of the defoaming agent is 0.1 to 7.5% by mass based on the total amount of the polyurethane foam molding composition.

[0024] That is, the production method according to any one of [5] to

[11] , wherein The polyurethane foam is obtained by reacting and foaming a polyurethane foam molding composition having a polyol component (A) and a polyisocyanate component (B) as constituent components. 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) or the polyisocyanate component (B) contains a defoaming agent (F), wherein the content of the defoaming agent (F) is 0.1 to 7.5% by mass relative to the total amount of the polyurethane foam molding composition.

[0025]

[13] The method for producing a polyurethane foam according to

[12] , wherein the defoaming agent (F) is a silicone oil, and the number average molecular weight of the polysiloxane component contained in the silicone oil is 10,000 to 50,000.

[0026]

[14] The method for producing a polyurethane foam according to

[12] or

[13] , wherein the defoaming agent (F) is contained in the polyol component (A).

[0027]

[15] The method for producing a polyurethane foam according to any one of

[12] to

[14] , 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.

[0028]

[16] The method for producing a polyurethane foam according to any one of

[12] to

[15] , wherein the average cell diameter of the obtained polyurethane foam is 2000 μm or more, and the area ratio of cells with a diameter of 5000 μm or more is 20% or more.

[0029]

[17] The method for producing a polyurethane foam according to any one of

[12] to

[16] , wherein the thickness of the thinnest part of the polyurethane foam is 5.0 to 50 mm.

[0030] Effects of the Invention By using the polyurethane foam of the present invention, when used as a sound absorbing material or a sound insulating material, the base material thickness is thin, and high noise insulation performance can be achieved particularly in low and medium frequency regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a perspective view of the polyurethane foam 1 in this embodiment.

[0032] Figure 2 It is the edge of polyurethane foam 1 Figure 1 The cross-sectional view of line II-II, Figure 2 (a) is a diagram of the polyurethane foam 1 according to the first embodiment. Figure 1 The cross-sectional view of line II-II, Figure 2 (b) is a diagram of the polyurethane foam 1 according to the second embodiment. Figure 1 The cross-sectional view of line II-II, Figure 2 (c) is the edge of the polyurethane foam 1 according to the third embodiment. Figure 1 Cross-sectional view along line II-II.

[0033] Figure 3 This is an optical microscope photograph of the surface of the polyurethane foam of Example 1.

[0034] Figure 4 This is an optical microscope photograph of the surface of the polyurethane foam of Example 2.

[0035] Figure 5 This is an optical microscope photograph of the surface of the polyurethane foam of Example 7.

[0036] Figure 6 This is an optical microscope photograph of the surface of the polyurethane foam of Example 8.

[0037] Figure 7 This is an optical microscope photograph of the surface of the polyurethane foam of Example 9.

[0038] Figure 8 This is an optical microscope photograph of the surface of the polyurethane foam of Comparative Example 1.

[0039] Fig. 9 This is an optical microscope photograph of the surface of the polyurethane foam of Comparative Example 3.

[0040] Fig.10 This is an optical microscope photograph of the surface of the polyurethane foam of Comparative Example 4. DETAILED DESCRIPTION

[0041] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. It should be noted that in each figure, the same reference numerals are given to the same or corresponding parts, and repeated descriptions are omitted. In addition, the dimensional ratios of the drawings are not limited to the ratios shown in the drawings.

[0042] Figure 1 It is a perspective view of the polyurethane foam 1 in this embodiment. Figure 1The polyurethane foam 1 shown is in the shape of a plate as a whole, and at least one of the main surfaces facing each other, that is, one of the upper surface or the lower surface of the polyurethane foam 1, has an open porosity of 0 to 1.0%, and the main surface having the open porosity, that is, the upper surface or the lower surface having an open porosity of 0 to 1.0%, has a root mean square surface roughness of 0.01 to 0.30 μm according to JIS B0601:1994. It should be noted that the polyurethane foam is not limited to a plate shape (it can also be a block shape or a panel shape), and can also be any shape (for example, a cylindrical shape) having a main surface facing each other. The main surface does not have to be flat, and can be curved or have concave and convex shapes.

[0043] The porosity is 0 to 1.0%, but the porosity may be 0 to 0.6%, or 0 to 0.5%. The root mean square surface roughness is 0.01 to 0.30 μm, but the root mean square surface roughness may be 0.02 to 0.30 μm, or 0.05 to 0.30 μm. By making the porosity and the root mean square surface roughness below the above upper limits, the polyurethane foam 1 can exert excellent sound absorption and insulation effects in the low and medium frequency regions.

[0044] Figure 1 The dotted arrow in the figure indicating the thickness direction of the polyurethane foam 1 is the foaming direction of the polyurethane foam 1. The polyurethane foam 1 can be produced by reacting and foaming a polyurethane foam molding composition, and the direction in which the thickness of the polyurethane foam molding composition increases when foaming in a molding device (mold, etc.) is the foaming direction. The formed foam (cell) generally has a shape extending in the thickness direction (e.g., spindle shape), so the foaming direction can also be determined from its shape.

[0045] The air permeability of the polyurethane foam 1 according to JIS K6400 is 0 to 2.0 cm 3 / cm 2 / sec. That is, along Figure 1 The air permeability measured in the direction of the dotted arrow is 0 to 2.0 cm 3 / cm 2 / sec. The air permeability can be 0 to 1.5 cm 3 / cm 2 By setting the air permeability to be equal to or less than the above upper limit, sufficient sound insulation in low and medium frequency regions can be obtained.

[0046] The polyurethane foam 1 preferably has a sound absorption coefficient of 0.4 or more at 800 Hz under the conditions of a sample with a diameter of 100 mm and a thickness of 10 mm in the normal incidence sound absorption coefficient measurement method according to JISA1405-2:2007, and a simple average value of sound transmission loss at 800 to 1250 Hz under the conditions of a sample with a diameter of 100 mm and a thickness of 10 mm in the normal incidence sound transmission loss measurement according to ASTM E2611 of 15 dB or more. The sound insulation performance can be evaluated by the normal incidence sound transmission loss measurement, and the simple average value of sound transmission loss at 800 to 1250 Hz refers to the simple average value of normal incidence sound transmission losses at 800 Hz, 1000 Hz, and 1250 Hz.

[0047] The polyurethane foam 1 can be a soft polyurethane foam, a semi-rigid polyurethane foam, or a rigid polyurethane foam.

[0048] Soft polyurethane foam refers to a reversibly deformable foam having an open-cell structure and showing high air permeability [for example, see Gunter Oertel, "Polyurethane Handbook" (1985 edition), Hanser Publisher (Germany), pp. 161-233, Keiji Iwata, "Polyurethane Resin Handbook" (1987 first edition), Nikkan Kogyo Shimbun, pp. 150-221].

[0049] The physical properties of flexible polyurethane foam vary depending on the chemical structure of the polyol, isocyanate, etc. used in its production, the amount of the foaming agent, the isocyanate index and other chemical factors, the cell structure, etc., and therefore are difficult to specify. However, the density (which can be measured as the apparent density, the same applies hereinafter) is generally 10 to 100 kg / m 3 The range of the tensile strength (ILD25%) is 2 to 80 kgf (20 to 800 N) (JIS K 6401), the range of the elongation is 80 to 500% (JIS K 6301) [for example, refer to Gunter Oertel, "Polyurethane Handbook" (1985 edition) Hanser Publisher (Germany), pp. 184 to 191 and 212 to 218, Keiji Iwata, "Polyurethane Resin Handbook" (1987 first edition) Nikkan Kogyo Shimbun, pp. 160 to 166 and 186 to 191].

[0050] Semi-rigid polyurethane foam refers to a reversibly deformable foam that has an open-cell structure and high air permeability, similar to soft polyurethane foam, although its foam density and compression strength are higher than those of soft polyurethane foam. The raw materials such as polyol and isocyanate used in its production are also the same as those of soft polyurethane foam, so it is generally classified as soft polyurethane foam [for example, refer to Gunter Oertel, "Polyurethane Handbook" (1985 edition) Hanser Publisher (Germany), pages 223-233, Keiji Iwata "Polyurethane Resin Handbook" (1987 first edition) Nikkan Kogyo Shimbun, pages 211-221]. The physical properties of semi-rigid polyurethane foam are not particularly limited, and the density is usually 40 to 800 kg / m 3 The range of 25% compression strength is 0.1~2kgf / cm 2 The range of pressure is 9.8~200kPa, and the range of elongation is 40~200%.

[0051] Rigid polyurethane foam is a foam with a highly cross-linked closed-cell structure that cannot be reversibly deformed, and has completely different properties from soft and semi-rigid polyurethane foams [for example, see Gunter Oertel, "Polyurethane Handbook" (1985 edition) Hanser Publisher (Germany), pp. 234-313, Keiji Iwata, "Polyurethane Resin Handbook" (1987 first edition) Nikkan Kogyo Shimbun, pp. 224-283]. The properties of rigid foam are not particularly limited, but the density is usually 20 to 100 kg / m 3 The range of compression strength is 0.5~10kgf / cm 2 (50~1000kPa) range.

[0052] Figure 2 is along Figure 1 sectional views taken along line II-II of , (a) is a sectional view of the polyurethane foam 1 according to the first embodiment, (b) is a sectional view of the polyurethane foam 1 according to the second embodiment, and (c) is a sectional view of the polyurethane foam 1 according to the third embodiment.

[0053] Figure 2 The polyurethane foam 1 according to the first embodiment shown in (a) comprises a polyurethane foam body 2 having a main surface 2a with an open cell ratio of 0 to 1.0% and a root mean square surface roughness of 0.01 to 0.30 μm in accordance with JIS B 0601:1994.

[0054] The polyurethane foam 1 according to the first embodiment can be produced by the following production method: a production method in which a polyurethane foam is molded in a state in which films containing a resin having an SP value of 10 or less are respectively arranged on the inner surfaces of a pair of dies constituting the mold, and the films are peeled off; or a production method in which a release agent having a melting point of 70 to 90° C. is arranged on the inner surfaces of a pair of dies constituting the mold, and the polyurethane foam is molded (in this case, no film is interposed between the molded polyurethane foam and the release agent).

[0055] In the case of the above-mentioned production method, the surface of the polyurethane foam may be in a form as if a film is laminated. That is, the surface of the polyurethane foam 1 after peeling off the film containing the resin having an SP value of 10 or less, and the surface of the polyurethane foam 1 obtained after passing through a release agent at 70 to 90° C., has a dense layer (foam skin layer) whose foaming degree is greatly suppressed.

[0056] Figure 2 The polyurethane foam 1 according to the second embodiment shown in (b) is composed of a polyurethane foam body 2 and films 4 laminated on the upper and lower surfaces of the polyurethane foam body 2. The main surface 4a of the polyurethane foam 1 has an opening ratio of 0 to 1.0% and a root mean square surface roughness of 0.01 to 0.30 μm in accordance with JIS B 0601:1994.

[0057] The film 4 is composed of a resin film, and a film without holes penetrating in the thickness direction (non-perforated) is used. In the second embodiment, the film 4 may be a resin film (sometimes referred to as a "polar film") containing a resin having an SP value (solubility parameter) exceeding 10. The films 4 on the upper and lower surfaces may be of the same type or of different types.

[0058] The SP value is based on a known method used as a method for calculating the SP value of a polymer. For example, there are a method of obtaining the SP value from the solubility in a solvent with a known SP value (G. Gee, Trans. Inst. Rubber Ind, 18, 266 (1943)), a method of obtaining the SP value from the osmotic pressure of a polymer solution (RF Fedors, Polym. Eng. Sci, 14 (2), pl47, p472 (1974)), a method of obtaining the SP value from the swelling degree (MB Huglin, DJ Pass, J. Appl. Polym. Sci, 12, 473 (1968), LA Errede, Macromolecules 19, 1522 (1986)), and a method of obtaining the SP value from the change in turbidity when a poor solvent is added to a polymer solution (KW Suh, JM Corbett, J. Appl. Polym. Sci, 12, 2359 (1968)). Generally, there is not much difference in SP value depending on the measurement method and calculation method, but if there is a difference, the average value of the available data can be used. It should be noted that when comparing SP values, it is preferred to use the same measurement method and calculation method.

[0059] The polyurethane foam 1 according to the second embodiment can be produced by a production method of performing mold molding of the polyurethane foam in a state where films containing a resin having an SP value exceeding 10 are respectively arranged on the inner surfaces of a pair of dies constituting the mold.

[0060] Figure 2 The polyurethane foam 1 according to the third embodiment shown in (c) is composed of a polyurethane foam body 2 and a film 4 laminated on the upper surface of the polyurethane foam body 2. The main surface 4a of the polyurethane foam 1 has an open porosity of 0 to 1.0%, and a root mean square surface roughness of 0.01 to 0.30 μm in accordance with JIS B0601:1994. In the polyurethane foam 1 according to the third embodiment, a foam skin layer may be formed on the opposite surface to the main surface 4a, or may not be formed.

[0061] The polyurethane foam 1 according to the third embodiment can be produced by disposing a film containing a resin having an SP value of more than 10 on the inner surface of one of a pair of molds constituting a mold and performing mold molding of the polyurethane foam. When a foam skin layer is formed on the surface of the polyurethane foam on the side opposite to the side on which the film is disposed, the following methods can be used: (1) a method of performing mold molding of the polyurethane foam in a state where a film containing a resin having an SP value of less than 10 is disposed on the other inner surface, and peeling off the film containing the resin having an SP value of less than 10; (2) a method of disposing a release agent having a melting point of 70 to 90° C. on the other inner surface, and performing mold molding of the polyurethane foam without interposing a film.

[0062] When the foam skin layer is not formed on the surface of the polyurethane foam opposite to the side where the film is disposed, a method other than the above (1) or (2) may be used (for example, a method of disposing a release agent having a melting point outside the range of 70 to 90° C. on the other inner surface).

[0063] It should be noted that the air permeability of the polyurethane foams according to the first, second and third embodiments is 0 to 2.0 cm in accordance with JIS K6400. 3 / cm 2 / sec.

[0064] Hereinafter, the polyurethane foam molding composition for producing the polyurethane foam 1 and the production method using the composition will be described in detail.

[0065] The polyurethane foam 1 can be obtained by reacting and foaming a polyurethane foam molding composition containing the following polyol component (A), polyisocyanate component (B), catalyst (C), foam stabilizer (D), foaming agent (E) and defoaming agent (F).

[0066] The polyol component (A) is a component that forms a polyurethane by addition polymerization with the polyisocyanate component (B), and is preferably at least one selected from the group consisting of polyether polyols and polyester polyols. Furthermore, the number average molecular weight is preferably 1000 to 10000, more preferably 3000 to 8000, and most preferably 4000 to 8000. In addition, the nominal number of functional groups is more preferably 2 or more.

[0067] When the number average molecular weight is less than the lower limit, the flexibility of the obtained foam is likely to be insufficient, and when it exceeds the upper limit, the hardness of the foam is likely to decrease. In addition, when the nominal number of functional groups is less than 2, the following problems arise: the resilience of the foam is significantly reduced, and the foam cannot be restored to its original shape when compressed. It should be noted that the nominal number of functional groups represents the theoretical average number of functional groups (the number of active hydrogen atoms per molecule) assuming that no side reactions occur in the polymerization reaction of the polyol.

[0068] As the polyether polyol, for example, polypropylene ether polyol, polyethylene polypropylene ether polyol (hereinafter referred to as PPG), polytetramethylene ether glycol (hereinafter referred to as PTG) and the like can be used. As the polyester polyol, for example, polyester polyol containing adipic acid and diol as a polycondensation-type polyester polyol, polycaprolactone polyol as a lactone polyester polyol and the like can be used.

[0069] 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 may be used in the polyol component (A). Examples of such at least one polyol selected from the group consisting of castor oil and castor oil-modified polyols include castor oil derivatives such as refined castor oil, semi-refined castor oil, unrefined castor oil, and hydrogenated castor oil to which hydrogen has been added.

[0070] In addition, in order to promote the interconnection of the polyurethane foam, it is preferred that the polyol component (A) contains a polyether polyol having a polyoxyalkylene chain containing a copolymer of ethylene oxide and propylene oxide. The number average molecular weight is preferably 3000 to 8000, and the nominal number of functional groups is preferably 2 to 4. Furthermore, the ethylene oxide unit in the polyether polyol is preferably 60 to 90% by mass, and more preferably 60 to 80% by mass.

[0071] By setting the ethylene oxide unit content to 60 to 90% by mass, the durability of the foam can be improved. In addition, from the viewpoint of storage stability at low temperatures, the copolymer containing ethylene oxide and propylene oxide is preferably a random copolymer.

[0072] The amount of the polyether polyol added is preferably 0.5 to 5.0% by mass based on the polyol component (A). When it is less than the lower limit, the moldability of the foam may deteriorate, while when it exceeds the upper limit, the elongation of the foam may decrease.

[0073] In order to adjust the hardness, a polymer polyol obtained by polymerizing a vinyl monomer in a conventional method may be used in the polyol component (A). Such a polymer polyol includes, for example, a polymer polyol obtained by polymerizing and stably dispersing a vinyl monomer in a polyalkylene polyol such as PPG described above in the presence of a free radical initiator.

[0074] Examples of the vinyl monomer include acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl methacrylate, and alkyl methacrylate, of which acrylonitrile and styrene are preferred. Examples of such polymer polyols include EL-910 and EL-923 manufactured by AGC, and FA-728R manufactured by Sanyo Chemical Industries, Ltd.

[0075] The polyisocyanate component (B) is preferably 4,4'-diphenylmethane diisocyanate (hereinafter referred to as 4,4'-MDI), 2,4'-diphenylmethane diisocyanate (hereinafter referred to as 2,4'-MDI), 2,2'-diphenylmethane diisocyanate (hereinafter referred to as 2,2'-MDI), etc. diphenylmethane diisocyanate (hereinafter referred to as MDI), polyphenylene polymethylene polyisocyanate (hereinafter referred to as P-MDI) as the 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, a urethane-modified product, a allophanate-modified product (Japanese original: ヌレート変性体), a biuret-modified product, etc. can also be used.

[0076] The MDI content of the polyisocyanate component (B) is preferably in the range of 50 to 85% by mass. If the MDI content exceeds 85% by mass, the storage stability of the obtained polyisocyanate composition at low temperature and the durability of the obtained foam may be reduced. On the other hand, when it is less than 50% by mass, as the crosslinking density increases, the elongation of the polyurethane foam decreases, and it may be difficult to obtain sufficient foam strength.

[0077] Furthermore, the total content of 2,2'-MDI and 2,4'-MDI relative to the total amount of MDI (hereinafter referred to as the isomer content) is preferably 10 to 50% by mass.

[0078] When the content of 2,2'-MDI and 2,4'-MDI relative to the total amount of MDI is less than 10% by mass, the storage stability of the obtained polyisocyanate composition at low temperature may be impaired, and it is sometimes necessary to continuously heat the isocyanate storage place, piping, and foaming molding machine. In addition, the molding stability of the polyurethane foam is impaired, and foam collapse may occur during foaming. On the other hand, if it exceeds 50% by mass, problems such as reduced reactivity, extended molding cycle, increased single-bubble rate of the foam, and shrinkage after molding may occur.

[0079] As the catalyst (C), various carbamate catalysts known in the art can be used. For example, 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-diazabicyclo[5.4.0]undecene-7, 1,2-dimethylimidazole, dimethylethanolamine, N,N-dimethyl-N-hexanolamine, and their organic acid salts, stannous octoate, zinc naphthenate and other organometallic compounds, etc. In addition, amine catalysts having active hydrogen such as N,N-dimethylethanolamine and N,N-diethylethanolamine are also preferred.

[0080] The amount of the catalyst added is preferably 0.01 to 10% by mass relative to the polyol component (A). When it is less than the lower limit, insufficient curing tends to occur, while when it exceeds the upper limit, moldability may deteriorate.

[0081] As the foam stabilizer (D), a common surfactant can be used, preferably a silicone surfactant. For example, SZ-1327, SZ-1325, SZ-1336, SZ-3601 manufactured by Dow-Toray, Y-10366J, L-5309J manufactured by Momentive, B-8724LF2, B-8715LF2 manufactured by Evonik, etc. can be mentioned. The amount of these foam stabilizers added is preferably 0.1 to 3.0% by mass relative to the polyol component (A).

[0082] As the blowing agent (E), water is mainly used. Water forms a high-hardness urea group by reacting with an isocyanate group and generates carbon dioxide, thereby enabling foaming. In addition, any blowing agent may be used in addition to water. For example, a small amount of low-boiling point organic compounds such as cyclopentane and isopentane may be used in combination, or air, nitrogen, or liquefied carbon dioxide may be mixed and dissolved in the stock solution using a gas loading device to perform foaming.

[0083] The amount of the foaming agent added is usually 0.5 to 10% by mass relative to the polyol composition, and the ... 3 In the case of a low-density polyurethane foam, it is preferably 4.0 to 7.0 mass %, and more preferably 4.0 to 6.5 mass %. If the upper limit is exceeded, the foaming may be difficult to stabilize, and if it is less than the lower limit, the density of the foam may not be sufficiently reduced.

[0084] The defoamer (F) is used to coarsen the cells of the polyurethane foam. By coarsening the cells, a resonator-type sound absorption mechanism can be manifested in the polyurethane foam, and the sound absorption and insulation effect of a specific frequency can be improved. As components of the defoamer (F), for example, silicone-based, oil-based, fatty acid-based, fatty acid ester-based, and phosphate-based defoamers, and substances in which a part of the structure of these defoamers is modified, etc. can be cited. Only one of them may be contained, or two or more of them may be contained.

[0085] When containing two or more kinds, it can be a combination of any defoamer components of silicone series, alcohol series, ether series, polyol series, metal soap series, nonionic surfactant series, oil series, fatty acid series, fatty acid ester series, and phosphate ester series. In addition, the defoamer component is particularly preferably a silicone defoamer.

[0086] As the silicone defoamer, oil-type, oil-complex-type, solution-type, emulsion-type, self-emulsifying-type and powder-type defoamers can be cited, all of which can be used appropriately. The silicone defoamer has a polysiloxane structure like the above-mentioned silicone foam stabilizer, but in order to show the defoaming property, the polysiloxane chain is relatively long, and it is different in that it is highly 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. When the number average molecular weight is less than 10,000, it may be difficult to obtain a defoaming effect. When the number average molecular weight exceeds the upper limit, the dispersibility of the defoamer decreases and separation may occur.

[0087] Examples of the silicone defoaming agent include dimethyl silicone oil [(CH3)3Si-〔OSi(CH3)2〕nO-Si(CH3)3], methylphenyl silicone oil [(CH3)3Si-〔OSi(CH3)2〕m-〔OSi(CH3)(C6H5)〕nO-Si(CH3)3, (CH3)3Si-〔OSi(CH3)2〕m-〔OSi(C6H5)2〕nO-Si(CH3)3, etc.], and methyl hydrogen silicone oil [(CH3)3Si-〔OSi(CH3)2〕m-〔OSi(CH3)(H)〕nO-Si(CH3)3, etc.].

[0088] The content of the defoaming agent (F) is preferably 0.1 to 7.5% by mass, more preferably 0.1 to 7.0% by mass, relative to the total amount of the polyurethane foam molding composition. When the content is less than 0.1% by mass, the coarsening of the cells becomes insufficient and sufficient sound absorbing properties may not be obtained, while when the content exceeds 7.5% by mass, the foaming may become difficult to stabilize.

[0089] The polyurethane foam molding composition may contain various known additives and auxiliaries such as fillers such as calcium carbonate and barium sulfate, flame retardants, plasticizers, colorants, and antifungal agents, as needed.

[0090] The polyurethane foams according to the first embodiment, the second embodiment, and the third embodiment can be manufactured by the above method. When the polyurethane foam according to the first embodiment is manufactured using a film containing a resin having an SP value of 10 or less, and when the polyurethane foam according to the second embodiment is manufactured using a film containing a resin having an SP value of more than 10, a release agent having a melting point of 60 to 100° C. may be disposed between the film and the mold. In addition, in the method for manufacturing the polyurethane foam according to the third embodiment, when a film containing a resin having an SP value of more than 10 is disposed, a release agent having a melting point of 60 to 100° C. may be disposed between the film and the mold. In either case, the temperature of the pair of molds can be set to 30 to 80° C.

[0091] In the above-mentioned production method, a mixed solution (foaming stock solution) containing a polyol component (A), a polyisocyanate component (B), a catalyst (C), a foam stabilizer (D), a foaming agent (E) and a defoaming agent (F) can be injected into a mold, and then demolded after foaming and curing. The defoaming agent (F) is preferably added to the polyol component (A) from the viewpoint of ensuring dispersion stability.

[0092] When a polyurethane foam is produced using a film, a foaming stock solution containing a polyol component (A), a polyisocyanate component (B), a catalyst (C), a foam stabilizer (D), a foaming agent (E) and a defoamer (F) is injected into a mold in which a resin film is arranged in advance on at least one surface of a lower mold or an upper mold in a shape along the inner surface shape to obtain a polyurethane foam molded product. When a film containing a resin having an SP value of 10 or less is used, the film is peeled off during or after demolding.

[0093] As for the resin film, from the viewpoint of being able to reduce the time required for each placement on the mold and being able to be reused, it is more preferable to fix it to the mold using an adhesive or the like so that it can be peeled off from the polyurethane foam during demolding. In addition, the resin film is placed on at least one surface of the lower mold or the upper mold, but may be placed on both surfaces in order to improve the sound insulation rate.

[0094] The NCO index (100 times the molar ratio of NCO to active hydrogen) of all isocyanate groups in the polyisocyanate composition and all active hydrogen groups in the active hydrogen group-containing compound including water during mixed foaming is preferably 70 to 140, and more preferably 70 to 120 as a range with a good molding cycle.

[0095] When the NCO index is less than 70, the single cell property of the foam is excessively improved, and when it is higher than 120, the molding cycle may be prolonged due to the long-term residual unreacted isocyanate, or the foam may collapse during foaming due to the delay in molecular weight increase.

[0096] In the production of molded foam, the mold temperature when the foaming stock solution is injected into the mold is usually 30 to 80° C., preferably 45 to 70° C. If the mold temperature when the foaming stock solution is injected into the mold is lower than 30° C., the reaction rate may be reduced, resulting in a longer production cycle. On the other hand, if the mold temperature is higher than 80° C., the reaction between water and isocyanate is excessively accelerated relative to the reaction between polyol and isocyanate, and the foam may collapse in the middle of foaming.

[0097] The curing time when the foaming stock solution is foamed and cured is preferably 10 minutes or less, more preferably 7 minutes or less, in consideration of a general production cycle of molded foam.

[0098] When manufacturing molded foam, as in the case of ordinary molded foam, a high-pressure foaming machine, a low-pressure foaming machine, etc. can be used to mix the above-mentioned respective components.

[0099] The isocyanate component and the polyol component are preferably mixed immediately before foaming. Other components can be premixed with the isocyanate component or the polyol component within a range that does not affect the storage stability of the raw materials and the change over time of the reactivity. These mixtures can be used immediately after mixing, or the required amount can be appropriately used after storage. 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, antifoaming agent, etc. can also be separately introduced into the mixing section.

[0100] In addition, the mixing method can be either dynamic mixing carried out in the mixing chamber of the head of the foaming machine or static mixing carried out in the liquid supply pipe, and the two can also be used in combination. The mixing of gaseous components such as physical foaming agents and liquid components is mostly carried out by static mixing, and the mixing of components that can be stably stored as liquids is mostly carried out by dynamic mixing. 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.

[0101] The mixed liquid obtained by such mixing is injected into a mold, foamed and cured, and then demolded. In order to smoothly carry out the above demolding, it is also preferable to pre-coat a mold release agent on the mold surface where the resin film is not arranged.

[0102] As the mold release agent, a substance obtained by dissolving a hydrocarbon-based wax, silicone, or fluorine as the main component in an organic solvent, or a substance obtained by dispersing an emulsifier in water can be used. The melting point of the mold release agent is preferably 60°C to 100°C, more preferably 70°C to 100°C. When the melting point of the mold release agent is too low relative to the mold temperature, the main component of the molten mold release agent mixes with the mixed liquid of the polyol component and the isocyanate component, and there may be cell cracking of the polyurethane foam ("cell cracking" in Japanese: セル荒れ). When the melting point of the mold release agent is too high relative to the mold temperature, the open cell ratio on the surface of the polyurethane foam may become high.

[0103] The demolded product can be used directly, but it is preferably to break the cell membranes of the foam under compression or decompression by a known method to stabilize the appearance and dimensions of the subsequent product.

[0104] The resin film preferably has an SP value of less than 10, and more preferably has an SP value of less than 9.5. When the SP value exceeds the upper limit, the adhesion to the polyurethane foam is improved, and it is possible that the film cannot be peeled off during or after demolding. As resin, for example, ethylene-α-olefin copolymers such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, ethylene-vinyl acetate-methyl methacrylate copolymer, polyolefin resins such as polystyrene, polytetrafluoroethylene (Teflon (registered trademark)), etc. can be used, wherein preferably cheap polyethylene resins and polypropylene resins are used.

[0105] The thickness of the film is preferably 1 to 250 μm. If the thickness of the film is less than 1 μm, workability when placed in a mold may be deteriorated, and if the thickness exceeds 250 μm, moldability of the polyurethane foam may be reduced.

[0106] The hardness of the polyurethane foam obtained by the above-mentioned production method is preferably 20 to 100 points, more preferably 40 to 100 points, in terms of the ASKER C hardness measured in accordance with JIS K7312. When the ASKER C hardness is less than 20, sufficient sound absorption and insulation in the low and medium frequency regions may not be obtained. In addition, the air permeability of the polyurethane foam obtained by the above-mentioned production method measured in accordance with JIS K6400 is preferably 0 to 2.0 cm 3 / cm 2 / sec, more preferably 0 to 1.5 cm 3 / cm 2 When the air permeability exceeds the upper limit, sufficient sound insulation in the low and medium frequency ranges may not be obtained.

[0107] The thickness of the thinnest portion of the polyurethane foam obtained by the above-mentioned production method is preferably 5.0 to 50 mm, more preferably 5.0 to 30 mm. When the thickness of the thinnest portion is less than 5.0 mm, sufficient sound absorption and insulation effects in the low and medium frequency regions may not be obtained. When the thickness exceeds the upper limit, sufficient space may not be ensured in transportation machinery, buildings, etc.

[0108] The porosity of the surface layer of at least one of the upper and lower surfaces relative to the foaming direction is preferably 0 to 1.0%. When the porosity exceeds 1.0%, the sound absorption and insulation effect in the low and medium frequency regions may be reduced. In addition, the root mean square surface roughness recorded in JIS B 0601:1994 of the same surface as the surface on which the porosity is measured is preferably 0.01 to 0.30 μm. When the root mean square surface roughness exceeds the upper limit, the sound absorption and insulation effect in the low and medium frequency regions may be reduced.

[0109] By the above-mentioned method for producing polyurethane foam, the following polyurethane foam can be appropriately obtained: in the normal incidence sound absorption coefficient measurement method according to JISA1405-2:2007, the sound absorption coefficient at 800 Hz is 0.4 or more under the condition of a sample with a diameter of 100 mm and a thickness of 10 mm, and in the normal incidence sound transmission loss measurement according to ASTM E2611, the simple average value of the sound transmission loss at 800 to 1250 Hz under the condition of a sample with a diameter of 100 mm and a thickness of 10 mm is 15 dB or more. Here, the sound insulation performance can be evaluated by the normal incidence sound transmission loss measurement, and the simple average value of the sound transmission loss at 800 to 1250 Hz refers to the simple average value of the normal incidence sound transmission losses at 800 Hz, 1000 Hz, and 1250 Hz.

[0110] The pores of polyurethane foam are coarsened by using a defoaming agent, thereby obtaining a high sound absorption and insulation effect. It is believed that this is because, by making the pores coarsened, the membrane vibration of the surface layer is effectively manifested, thereby improving the sound absorption and insulation of a specific frequency, and the sound absorption mechanism of the Helmholtz resonator type is manifested in the polyurethane foam, thereby improving the sound absorption effect of a specific frequency. In the Helmholtz resonator, the air inside the container with an opening acts as a spring, resonating with the vibration of a specific frequency determined by the internal volume of the container and the area of ​​the opening, and the air introduced into the container is violently vibrated through the above-mentioned resonance phenomenon, and the energy of the noise is eliminated through friction loss, thereby absorbing the sound.

[0111] In the present invention, it is considered that the coarse cells are used as containers, and relatively small cells other than the coarse cells, pores existing in the foam skin layer formed during production, or the openings of the film are used as container openings, and the size of the coarse cells (the internal volume of the container) is adjusted so that the resonance frequency of the Helmholtz resonator becomes 1000 Hz to 3500 Hz, thereby exhibiting a high sound absorbing effect.

[0112] Example Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples. It should be noted that, unless otherwise specified, "parts" and "%" herein are by mass.

[0113] (Examples 1 to 9, Comparative Examples 1 to 4) [Preparation of polyol composition] After nitrogen substitution in a reactor equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer, 40 g of polyol 1, 60 g of polyol 2, 1.0 g of polyol 3, 0.5 g of catalyst 1, 0.03 g of catalyst 2, 1.0 g of foam stabilizer 1, 0.7 g of defoamer 1, and 3.8 g of water were added, 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-3) were prepared in the same manner as P-1.

[0114] [Mold forming conditions] The liquid temperature of the isocyanate composition and the mixture of all raw materials other than the isocyanate composition (polyol composition) in the raw materials shown in Table 1 was adjusted to 24°C to 26°C. A predetermined amount of polyisocyanate components was added to the polyol composition, mixed for 7 seconds using a mixer (7000 revolutions per minute), and then injected into a mold to foam the polyurethane foam. It should be noted that in the examples and comparative examples, the film and release agent shown in "0" in Table 1 were used (the parts without "0" in the film and release agent indicate that they were not used.).

[0115] Mold temperature: 50~65℃ Mould shape: 400mm×400mm×10mm Mold material: Aluminum Curing time: 5 minutes Film placement: A resin film was placed on a mold in advance (Examples 1 to 7, Comparative Example 2).

[0116] [Foam properties] Foam properties were measured as follows.

[0117] After demolding, if the film can be peeled off, the measurement is performed after peeling off (Examples 1 to 5) After demolding, if the film was difficult to peel off, the measurement was performed without peeling off (Examples 6 to 7, Comparative Example 2) · No film was provided: Measurement was performed without a film (Examples 8 to 9, Comparative Examples 1, 3, and 4) · Regarding Comparative Example 2, after demolding, the laminated film portion on the surface was subjected to hot needle processing (perforation), and the hole was forced to be opened before measurement. [Table 1]

[0118] [Raw materials used] Polyol 1: Polyoxyethylene-polyoxypropylene polyol having an average number of functional groups = 3.0 and a hydroxyl value = 33 (mgKOH / g), EXCENOL 823 (trade name) manufactured by AGC Corporation Polyol 2: polymer polyol having an average number of functional groups = 3.0 and a hydroxyl value = 24 (mgKOH / g), EXCENOL 923 (trade name) manufactured by AGC Corporation Polyol 3: average number of functional groups = 4.0, hydroxyl value = 28 (mgKOH / g), polyoxyethylene polyoxypropylene polyol containing 80% by mass of oxyethylene units in the polyether polyol, NEF-024 (trade name) manufactured by Tosoh Corporation Polyol 4: Unrefined castor oil having an average number of functional groups of 2.7 and a hydroxyl value of 160 (mgKOH / g) (URIC H-24 manufactured by Ito Oil Products Co., Ltd.) Catalyst 1: 33% dipropylene glycol solution of triethylenediamine (manufactured by Tosoh Corporation, trade name: TEDAL-33) Catalyst 2: 70% dipropylene glycol solution of bis(2-dimethylaminoethyl) ether (manufactured by Tosoh Corporation, trade name: TOYOCAT ET) Foam stabilizer 1: Silicone foam stabilizer (Momentive, trade name: L-5309J) Defoamer 1: GC-302SS (trade name) Silicone defoamer manufactured by Nissin Chemical Research Institute Co., Ltd. Isocyanate 1: Polyphenylene polymethylene polyisocyanate having an MDI content of 75% by mass and an isomer content of 38.4% by mass (manufactured by Tosoh Corporation, trade name: CEF-549) Isocyanate 2: Polyphenylene polymethylene polyisocyanate having an MDI content of 70% by mass and an isomer content of 17.7% by mass (manufactured by Tosoh Corporation, trade name: CEF-538) Release agent 1: Hydrocarbon wax diluted with an organic solvent (K-878, manufactured by Chukyo Yushi Co., Ltd.) Release agent 2: Water-dispersible hydrocarbon wax (S-509, manufactured by Chukyo Yushi Co., Ltd.) Release agent 3: Water-dispersible hydrocarbon wax (M-975, manufactured by Chukyo Yushi Co., Ltd.) Release agent 4: hydrocarbon wax diluted with an organic solvent (manufactured by Konishi Co., Ltd., UR-658) Film 1: High-density polyethylene film with a film thickness of 20 μm (Nipolon Hard FW10, manufactured by Tosoh Corporation) Film 2: Low-density polyethylene film with a film thickness of 50 μm (manufactured by Tosoh Corporation, Petrocene 231F) Film 3: Polypropylene film with a film thickness of 30 μm (TORAYFAN (registered trademark), manufactured by Toray Industries, Inc.) Film 4: Polystyrene film with a film thickness of 30 μm (Styrofan, manufactured by Oishi Industry Co., Ltd.) Membrane 5: Polyvinyl chloride membrane with a thickness of 30 μm (Lonace NP manufactured by Lonseal) Film 6: A thermoplastic polyurethane elastomer film having a film thickness of 30 μm (manufactured by Okura Industries, Ltd., SILKLONET 85).

[0119] [Evaluation of moldability] In Table 1, the evaluation of "0" for moldability means that the polyurethane foam can be molded without collapse in which the polyurethane foam sinks significantly after reaching the maximum height, and the phenomenon that the generated polyurethane foam shrinks just after foaming or curing occurs, "difficult to peel off the film" means that the adhesion to the polyurethane foam is high and it is difficult to peel off the film after demolding, and "×" for "cell cracking" means that the foam surface state is disordered during the foaming process of the polyurethane foam and the surface open porosity becomes high.

[0120] [Apparent density] It is determined by the method described in JIS K6400.

[0121] [C hardness] The measurement was performed using a rubber hardness tester (ASKER-C type) described in JIS K7312.

[0122] [Breathability] The measurement was carried out by the method described in JIS K6400.

[0123] [Average cell diameter] The average cell diameter of each polyurethane foam molded body is determined as follows: a 10 mm thick molded body is hollowed out into a disk shape with a diameter of 28.8 mm, and an image of a field of view of 10 mm in length and 16.3 mm in width is taken of the foam side using a microscope equipped with a lens MTL5518C-034-01 manufactured by Moritex. The cell diameter of a specified number of cells existing in the field of view is measured, and the cell diameter is simply averaged to determine the average cell diameter.

[0124] [Surface opening ratio] The open porosity of each polyurethane foam molded body is calculated as follows: a 10 mm thick molded body is hollowed out into a disk shape with a diameter of 28.8 mm, and an image with a diameter of 28.8 mm is taken using a microscope equipped with a telecentric lens MM014-HR110-5M manufactured by Moritex for the surface that contacts the upper mold of the mold during molding. The image is binarized into the open part and the surface part other than the open part using the software "ImageJ", and the total area of ​​the open part is calculated, and then the calculation is based on the following calculation formula.

[0125] Opening ratio = (total area of ​​openings / sample area) × 100... (Formula).

[0126] [Root mean square surface roughness] The surface on which the above-mentioned opening ratio was measured was measured using a laser microscope (VK-9500 / VK-9510) manufactured by KEYENCE and an objective lens magnification (20×) and evaluated as the root mean square surface roughness described in JIS B0601:1994.

[0127] [Area ratio of cells with a diameter of 5000 μm or more] The area ratio of cells with a diameter of 5000 μm or more in each polyurethane foam molded body is calculated as follows: a molded body with a thickness of 10 mm is hollowed out into a disk shape with a diameter of 28.8 mm, and an image of the foam cross section is taken using a microscope equipped with a lens MTL5518C-034-01 manufactured by Moritex, with a field of view of 10 mm in length and 16.3 mm in width. The area of ​​cells with a diameter of 5000 μm or more present in the field of view is measured and calculated based on the following calculation formula.

[0128] Area ratio of cells with a diameter of 5000 μm or more = (Total area of ​​cells with a diameter of 5000 μm or more / viewing area) × 100... (Formula) [Sound absorption coefficient] The sound absorption coefficient at normal incidence of 50 to 1600 Hz was measured using a 4206 type sound tube manufactured by Brüel & Kjær & Japan based on the method described in JIS A1405-2: 2007. The sound absorption coefficient was measured under the following conditions: a polyurethane foam having a diameter of 100 mm and a thickness of 10 mm was arranged with the upper mold molding surface of the mold facing the sound source side, and no air layer was provided behind the polyurethane foam.

[0129] [Transmission loss] The sound transmission loss at normal incidence at 12.5 to 1600 Hz was measured using a 4206 type acoustic tube manufactured by Brüel & Kjær & Japan based on the method described in ASTM E2611. The sound transmission loss was measured under the following conditions: a polyurethane foam having a diameter of 100 mm and a thickness of 10 mm was arranged with the upper mold surface of the mold facing the sound source side, and no air layer was provided behind the polyurethane foam.

[0130] [Surface state] The molded body with a thickness of 10 mm was hollowed out into a disk shape with a diameter of 28.8 mm, and the surface in contact with the upper mold of the mold during molding was observed using an optical microscope. The images of Examples 1, 2, 7, 8, 9, and Comparative Examples 1, 3, and 4 are shown in Figure 1. Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 , Fig.10 The diameter of the polyurethane foam in the image is 28.8 mm.

[0131] As shown in Comparative Example 1 of Table 1, when no film is configured in the mold, the 800Hz sound absorption coefficient and the average sound transmission loss of 800-1000Hz are extremely low. In this case, compared with the embodiment, the air permeability and the porosity are high, and the root mean square surface roughness is large. As shown in Comparative Example 2, even when the film is configured in the mold, when the laminated film portion on the surface is subjected to hot needle processing and forced to open the hole, the air permeability and the porosity are high, the root mean square surface roughness becomes larger, and the 800Hz sound absorption coefficient and the average sound transmission loss of 800-1000Hz are extremely low. As shown in Comparative Example 3, when the melting point of the release agent is too low relative to the mold temperature, the molten main component mixes with the mixed liquid of the polyol component and the isocyanate component, resulting in cracked cells of the polyurethane foam. As shown in Comparative Example 4, when the melting point of the release agent is too high relative to the mold temperature, the opening rate of the polyurethane foam surface becomes high.

[0132] By comparing the above embodiments and comparative examples, it is clear that in the present invention, even if the thickness of the substrate is thin, a molded body with high sound absorption and insulation performance in the low and medium frequency regions can be obtained, and the importance and remarkable excellence of the structure of the present invention can be understood.

[0133] Description of Reference Numerals 1 ... polyurethane foam, 2 ... polyurethane foam main body, 2a ... main surface, 4 ... film, 4a ... main surface.

Claims

1. A polyurethane foam, characterized in that The opening ratio of at least one of the main surfaces facing each other is 0 to 1.0%, and the root mean square surface roughness of the main surface having the above opening ratio is 0.01 to 0.30 μm according to JIS B 0601:1994, The air permeability of the polyurethane foam according to JIS K6400 is 0 to 2.0 cm 3 / cm 2 / sec.

2. The polyurethane foam according to claim 1, wherein The Asker C hardness according to JIS K7312 is 20 to 100 points.

3. The polyurethane foam 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.

4. The polyurethane foam according to claim 1, wherein The thickness of the thinnest part is 5.0 to 50 mm.

5. The method for producing a polyurethane foam according to claim 1, characterized in that: The polyurethane foam is molded in a state where a film containing a resin having an SP value of 10 or less is arranged on the inner surface of at least one of a pair of molds constituting the mold, and the film is peeled off.

6. The manufacturing method according to claim 5, wherein: The resin having an SP value of 10 or less is a polyolefin resin.

7. The manufacturing method according to claim 5, wherein: The resin having an SP value of 10 or less is polyethylene or polypropylene.

8. The manufacturing method according to claim 5, wherein: A mold release agent having a melting point of 60 to 100° C. is placed between the film and the mold, and mold molding is performed.

9. The method for producing a polyurethane foam according to claim 1, characterized in that: A mold release agent having a melting point of 70 to 90° C. is disposed on the inner surface of at least one of a pair of molds constituting the mold, and mold molding of the polyurethane foam is performed without disposing a film on the surface on which the mold release agent is disposed.

10. The method for producing a polyurethane foam according to claim 1, characterized in that: The mold molding of the polyurethane foam is performed in a state where a film containing a resin is arranged on the inner surface of at least one of a pair of molds constituting the mold.

11. The production method according to any one of claims 5 to 10, wherein The temperature of the pair of molds is set at 30 to 80° C. to perform mold molding of the polyurethane foam.

12. The production method according to any one of claims 5 to 10, wherein: The polyurethane foam is obtained by reacting and foaming a polyurethane foam molding composition having a polyol component (A) and a polyisocyanate component (B) as constituent components. 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) or the polyisocyanate component (B) contains a defoaming agent (F), wherein the content of the defoaming agent (F) is 0.1 to 7.5% by mass relative to the total amount of the polyurethane foam molding composition.

13. The manufacturing method according to claim 12, wherein: The defoaming agent (F) is a silicone oil, and the number average molecular weight of the polysiloxane component contained in the silicone oil is 10,000 to 50,000.

14. The manufacturing method according to claim 12, wherein: The defoaming agent (F) is contained in the polyol component (A).

15. The manufacturing method according to claim 12, wherein: The polyisocyanate component (B) contains 50 to 85% by mass of diphenylmethane diisocyanate, 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 based on the total amount of the diphenylmethane diisocyanate.

16. The manufacturing method according to claim 12, wherein: The average cell diameter of the produced polyurethane foam is 2000 μm or more, and the area ratio of cells having a diameter of 5000 μm or more is 20% or more.

17. The manufacturing method according to claim 12, wherein: The thickness of the thinnest part of the produced polyurethane foam was 5.0 to 50 mm.

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