JP4440712B2 - Foamed polyurethane sheet with support and method for producing the same - Google Patents

Description

  The present invention relates to a foamed polyurethane sheet with a support and a method for producing the same, and more particularly to a foamed polyurethane sheet with a support that does not contain an organosiloxane compound and a method for producing the same.

  In a hard disk drive (hereinafter referred to as HDD) such as a personal computer, a motor sound or a wind noise of the disk is generated during driving, which becomes noise to the surroundings. For this reason, a sound insulating material is disposed between the HDD itself or between the HDD and the substrate and / or the top plate to reduce leakage of generated sound and to suppress vibration.

  Conventionally, a foam sheet sliced to a predetermined thickness from a foam formed in a slab shape such as polyurethane foam has been known as the above-described sound insulating material and vibration damping material. However, such a foam sheet has a problem that sound insulation effect is poor and sound leaks. Therefore, the spring constant of the foam is limited (Patent Document 1); a polymer film having fine irregularities is attached to the inside surface of the foam; the surface of the foam is covered with a film enclosing air (Patent Document 2) has been proposed. In addition, a sound-absorbing layer made of a foam is covered with a film having low air permeability (Patent Document 3), and a compressible foam having a specific range of air permeability (Patent Document 4) is used as a soundproofing material. Proposals have also been made. As the foam, a flexible polyurethane foam is used.

  In these conventional techniques, a silicone-based adhesive or sealing material mainly composed of a high molecular weight polyorganosiloxane is used for fixing a foam to a support or the like. Further, for the convenience of work, a silicone-based pressure-sensitive adhesive mainly composed of polyorganosiloxane is used for temporarily attaching a polyurethane foam used as a sound absorbing material to a support or the like.

  On the other hand, a polysiloxane / polyether graft copolymer is used as a foam stabilizer in forming a polyurethane foam. For special applications, low molecular siloxane compounds may be used in combination.

  As a new problem of sound insulation material used for sound insulation of HDD, the foam which is the sound absorption layer does not contain volatile organic compound (hereinafter referred to as VOC) and is particularly insulating and has contact points and printed circuit boards for HDD controller Thus, there has been a demand for a sound insulating material that does not contain a low-molecular siloxane compound that causes poor contact, and does not generate it during use. None of the aforementioned techniques for improving the sound insulation material solves this new problem.

Furthermore, in the method of adhering the sound insulating material and the support with an adhesive or a sealing material, when the adhesive receives a compressive force, it adheres to the adhesive to the inside of the sound absorbing layer that is the foam, and thus the foam does not recover. There was also a problem and a solution was also sought.
JP 59-102294 A JP-A-7-261768 Japanese Patent Laid-Open No. 10-254453 JP 10-254454 A

  An object of the present invention is to provide a low-molecular-weight organosiloxane compound, a foamed polyurethane sheet with a support that does not substantially contain a compound that is a generation source thereof, and a method for producing the same. Another object of the present invention is to prevent the adhesive from being present up to unnecessary portions of the foam and hindering the restoration of the foam. Another object of the present invention is to provide a sound insulating material for a hard disk drive, which is the above-mentioned foamed polyurethane sheet with a support, and a hard disk drive using the same.

  As a result of repeated researches to solve the above problems, the present inventors have used a polyorganosiloxane-containing adhesive, sealing material, pressure-sensitive adhesive, etc. by integrally forming a support and a foam. It has been found that by using a polyol having a specific number average molecular weight and a primary hydroxyl group ratio as a polyol, an excellent foamed polyurethane can be produced without using a siloxane-containing foam stabilizer. Thus, the present invention has been completed.

  That is, in the present invention, the support and the polyurethane foam are integrally molded, do not contain an organosiloxane compound, and the polyurethane base polymer has a number average molecular weight of 1,500 to 8,000 and a hydroxyl group present in the molecule. The present invention relates to a foamed polyurethane sheet with a support, wherein 20% or more of the groups are primary hydroxyl groups.

  The present invention also relates to a method for producing a foamed polyurethane sheet with a support, which does not use an organosiloxane compound in the process and has a number average molecular weight of 1,500 to 8,000 as a base polymer of polyurethane, The present invention relates to a production method characterized by integrally molding a support and a foam using a polyol in which 20% or more of the hydroxyl groups present in are primary hydroxyl groups.

  Furthermore, the present invention relates to a sound insulating material for a hard disk drive that is the above-mentioned foamed polyurethane sheet with a support, and a hard disk drive using the same.

  According to the present invention, by using a specific range of polyol, an excellent polyurethane sheet can be obtained without using a foam stabilizer. Moreover, workability and sound insulation are improved by using the support. Further, by integrally molding the polyurethane foam and the support, there is no use of adhesives, sealants or adhesives, and therefore no VOCs arising from adhesives, sealants and adhesives. In particular, since the sound insulating material does not contain an organosiloxane compound, there is no contamination of the HDD control board by a low molecular siloxane compound contained in the compound or generated during use, and no malfunction caused thereby. In addition, there is no case where the cured adhesive exists up to unnecessary portions and the shape of the sound absorbing material is not restored. Furthermore, the adhesive does not affect the hardness of the product, and the texture does not change.

  In the present invention, the foamed polyurethane sheet uses a linear or branched polyol having a hydroxyl group at the terminal as a base polymer, which is reacted with an isocyanate compound and / or a prepolymer having an isocyanate group at the terminal, It is obtained by integrally molding with.

  As the base polymer, a polyol having a number average molecular weight of 1,500 to 8,000, preferably 2,000 to 6,000 is used. As a result, the mechanical strength of the system in the initial stage of foaming is increased, and even foaming can be performed without foaming as described above without using a foam stabilizer. In order to give a network structure to the resulting polyurethane, at least a part of the polyol has a branching unit in the molecule and the number of hydroxyl groups in the molecule is 3 or more, and the number of hydroxyl groups in the molecule May be used in combination with one having two or the like, or two or more polyols may be used in combination. When two or more polyols are used in combination, the above number average molecular weight means an average of all the polyols used.

  As the polyol, polyether polyol, polyester polyol, polycarbonate polyol, polybutadiene polyol, or the like can be used. However, a polyol having a polysiloxane chain in the molecule cannot be used. Polyether polyols are preferably used because they are readily available and give polyurethanes with good properties, and especially polyurethanes with excellent hydrolysis resistance and moist heat aging resistance. It is more preferable to use an oxypropylene-based or oxyethylene-oxypropylene-based polyether polyol, which gives a polyurethane having excellent moist heat aging resistance and does not cause shrinkage after foaming. It is particularly preferable to use a polyether polyol having an ethylene unit content of 60 mol% or less, particularly 25 mol% or less. Here, for example, oxypropylene-based means a polyol made of oxypropylene excluding a portion derived from an initiator.

  Another feature of the polyol used in the present invention is that 20% or more, preferably 35% or more, more preferably 50% or more, particularly preferably 60 to 80% of the hydroxyl groups present in the molecule are primary hydroxyl groups. It is a group. Thereby, the reactivity of an isocyanate compound or an isocyanate group-containing prepolymer and an isocyanate group is enhanced, and an excellent foamed polyurethane sheet foamed uniformly can be obtained without the aid of a foam stabilizer.

  Such polyether polyols typically do not use initiators, or are dihydric alcohols such as ethylene glycol, propylene glycol, neopentyl glycol, cyclohexane-1,4-dimethanol as initiators; or glycerin , Synthesized by ring-opening polymerization of cyclic oxides such as ethylene oxide, propylene oxide and tetrahydrofuran using trihydric or higher polyhydric alcohols such as trimethylolethane, trimethylolpropane, pentaerythritol and sorbitol as initiators. Can be mentioned. As the polyester polyol, typically, a dihydric alcohol such as neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, succinic acid, adipic acid, azelaic acid, sebacic acid , Polycondensation reaction with a dibasic acid such as isophthalic acid so that the dihydric alcohol is slightly excessive, or a lactone such as ε-caprolactone or methylvalerolactone with a small amount of dihydric alcohol. Examples of ring-opening polymerization are given below.

  In polyether polyols and polyether-ester polyols synthesized by ring-opening polymerization of propylene oxide or co-opening polymerization of propylene oxide and other cyclic oxides, the terminal hydroxyl group of A secondary hydroxyl group is generated in part or in whole. Polyols suitable for use in the present invention include, for example, ethylene oxide introduction and ring-opening addition at the end of ring-opening polymerization using an acidic catalyst as a ring-opening polymerization catalyst; ring-opening polymerization using benzyl alcohol as an initiator, and terminal polymerization. After the hydroxyl group is coupled, the benzyl group can be removed by hydrogenolysis to form a primary hydroxyl group in the polyether.

  As an isocyanate compound, what is normally used in reacting with a polyol and forming a polyurethane can be used. As isocyanate compounds, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of both (TDI), diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, a mixture of both (MDI) Aromatic isocyanate compounds such as polymethylene polyphenylene diisocyanate; aliphatic isocyanate compounds such as hexamethylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate; derivatives such as dimers, trimers, and carbodiimide modified products Exemplified, one kind may be used or two or more kinds may be used in combination. Diphenylmethane-4,4′-diisocyanate, diphenylmethane-2,4′-diisocyanate and MDI (hereinafter referred to as MDIs) are obtained because an excellent reaction rate is obtained and a homogeneous and excellent polyurethane sheet can be obtained without a foam stabilizer. It is preferable to use a generic name.

  In addition, a prepolymer having an isocyanate group at the molecular end obtained by reacting these isocyanate compounds with a polyol such as polyether polyol or polyester polyol can be used in place of a part or all of the isocyanate compound. . Since an excellent reaction rate can be obtained and a homogeneous and excellent polyurethane sheet can be obtained without a foam stabilizer, it is preferable to use a prepolymer obtained by reacting MDIs with a polyol.

  The compounding amount of the isocyanate compound and / or the prepolymer is an amount such that the isocyanate index is usually in the range of 70 to 120, preferably 80 to 105, since a foam having stable quality can be produced.

  Catalysts for reacting polyols with isocyanate compounds or prepolymers include tin (II) octoate, tin (II) decanoate, tin (II) dodecanoate, tin (II) tetradecanoate, tin (II) oleate, naphthene Tin carboxylates such as tin (II) acid; organotin compounds such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dimaleate; triethanolamine, N, N-dimethylaminoethanol, triethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetramethyl-1,3-butylenediamine, N, N, N ′, N′-tetramethylhexamethylenediamine, dimethylamino Ethylmorpholine, 1,4-diazabicyclo [2.2.2] octane, 1,8-diaza Examples include amines such as cyclo [5.4.0] undecene-7, and one kind may be used or two or more kinds may be used in combination. For example, tin carboxylate or organotin compound and amines may be used. Can be used together. These catalysts may be mixed as they are, or may be blended by dissolving in a solvent such as low molecular weight diols. The usage-amount of a catalyst is 0.1-3.0 weight part normally with respect to 100 weight part of base polymers, Preferably it is 0.8-2.0 weight part.

  For the foamed polyurethane sheet stock solution, the above-mentioned base polymer polyol, isocyanate compound or derivative or prepolymer thereof, and catalyst, and, if necessary, foaming agent, cell stabilizer, chain extender, crosslinking agent, flame retardant In addition, additives such as a filler, a colorant, and an antistatic agent can be blended. Usually, in order to stably store the above materials, an isocyanate compound or a derivative thereof or a prepolymer is heated to a temperature equal to or higher than its melting point as necessary to obtain a liquid B. Prepare a stock solution by mixing uniformly with the solution. For the blending, mixing means such as a stirring mixer can be used at room temperature or in a heated state. For mixing the A liquid and the B liquid, a mixing head equipped with a metering pump such as a gear pump can be used.

  The feature of the polyurethane foam sheet used in the present invention is that the above stock solution does not contain an organosiloxane compound. Here, the organosiloxane compound refers to a compound having a low molecular weight to a high molecular weight having an organic carbon atom directly bonded to a silicon atom and having a siloxane bond in the molecule. Examples of organosiloxane compounds include alkyl groups such as methyl, ethyl, propyl, butyl and decyl bonded to silicon atoms; alkenyl groups such as vinyl; aryl groups such as phenyl; 2-phenylethyl and 2-phenylpropyl And monovalent hydrocarbon groups such as aralkyl groups such as those having monovalent substituted hydrocarbon groups having substituents such as fluorine, chlorine, hydroxyl, amino, mercapto, carboxyl, glycidoxy, methacryloxy, etc. In addition to these organic groups, hydrogen atoms bonded to silicon atoms; hydroxyl groups; those having silicon functional groups such as alkoxy groups such as methoxy and ethoxy, and cured products obtained by crosslinking them are also included. . Typical examples of the polyorganosiloxane include polydimethylsiloxane, polymethylvinylsiloxane, polymethylphenylsiloxane, polymethylhydrogensiloxane and the like having linear, branched, cyclic and network siloxane skeletons.

  Further, the organosiloxane compound includes, as another type, a polysiloxane-polyether block and / or graft copolymer generally used as a foam stabilizer for a foamed polyurethane sheet. As a typical example of such a copolymer, a polysiloxane part has a trimethylene group as a bonding group with a methyl group and a polyether part, and the polyether part is polyoxyethylene, polyoxypropylene or oxyethylene-oxypropylene. Examples thereof include polysiloxane-polyether blocks and / or graft copolymers which are copolymers.

  Silicone adhesives and sealing materials containing polyorganosiloxane as the main component are applied to the surface and the periphery of the sound insulation material in an uncured state, and develop adhesiveness through a curing reaction, and contain polysiloxane chains as the main component. A rubber layer is formed. Similarly, a silicone-based pressure-sensitive adhesive containing polyorganosiloxane as a main component is used as a pressure-sensitive adhesive layer treated on a tape-like base material for temporary fixing during work. It remains on the surface.

  The high molecular weight polyorganosiloxane contained in the above silicone-based adhesives, sealants and pressure-sensitive adhesives, and polysiloxane / polyether graft copolymers used as foam stabilizers contain a small amount of low-molecular siloxane compounds as impurities. ing. The polysiloxane is a temperature exceeding 200 ° C. in the case of the most common polydimethylsiloxane, and a temperature exceeding 250 to 300 ° C. even in a heat resistant grade in which a phenyl group is introduced into the molecule or a heat resistance improver is blended. Then, thermal decomposition produces a low molecular siloxane compound such as a cyclic siloxane such as octamethylcyclotetrasiloxane. In the case of a polysiloxane / polyether graft copolymer, thermal decomposition occurs even at a lower temperature, for example, 180 ° C. Accordingly, a sound insulating material containing an organosiloxane compound as a foam stabilizer, or an adhesive, a sealing material, an adhesive or the like containing polyorganosiloxane as a main component adhered to the surface of a sound absorbing layer or the like is used. When exposed to high temperature during use, a small amount of low molecular siloxane compound is generated by thermal decomposition, volatilizes and adheres to contacts, printed circuit boards, etc., causing contact failure.

  Therefore, in the production method of the present invention, an additive such as a foam stabilizer containing such an organosiloxane compound, an adhesive, a sealing material, a pressure-sensitive adhesive, and a release agent are not used.

  Examples of the support used in the present invention include a porous polymer such as paper, nonwoven fabric, cloth and felt; and a film such as a polypropylene film, a polyethylene terephthalate (hereinafter referred to as PET) film, and a polyphenylene sulfide film. PET film is preferable from the viewpoint of the property, dimensional stability when heated, and cost.

  The sound insulating material of the present invention is an integrally molded body in which a sound absorbing layer 1 made of polyurethane foam and a support 2 are bonded, as shown in a conceptual cross-sectional view in FIG. The thickness of the sound absorbing layer 1 is usually 0.5 to 4.0 mm, preferably 0.8 to 1.6 mm. The thickness of the support 2 is usually 0.025 to 0.1 mm.

  The sound insulating material of the present invention can be produced by a production method including a step of integrally molding a polyurethane foam and a support. In the integral molding, for example, when a release liner is provided, the release agent layer faces the support, and is arranged in parallel with the support with a gap in the width of the sound absorbing layer to be attached. It can be carried out by a method including a step of allowing a polyurethane foam material to flow into the gap. The inflow is performed by an arbitrary method such as casting or injection.

  As the release liner, a polymer film having no affinity for polyurethane and its material, such as polypropylene and polytetrafluoroethylene, or a paper, a nonwoven fabric or a polymer film coated with a release agent on at least one surface thereof is used. Examples of the release agent include polytetrafluoroethylene-containing emulsions, resins with low polarity such as polypropylene, waxes, and liquid paraffin. As the release liner, a PET film or a laminate of paper and polypropylene is preferable.

  Formation of polyurethane foam by curing and foaming can usually be carried out by heating to 50-180 ° C. for 2-10 minutes with the release liner in place. After the formation of the polyurethane foam layer, the release liner is removed to complete the sound insulating material.

  The sound insulating material thus produced can be used by being disposed between the HDD itself or between the HDD and the substrate and / or the top plate.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited by these examples. In Examples and Comparative Examples, parts represent parts by weight, and% of the composition represents% by weight.

  In Examples and Comparative Examples, oxypropylene-based or oxyethylene-oxypropylene-based polyether polyols shown in Table 1 were used.

In the examples and comparative examples, the following catalysts were used.
C-1: 33% dipropylene glycol solution of triethylenediamine C-2: N, N, N ′, N′-tetramethylhexamethylenediamine

Analysis of hydroxyl groups of polyols used in Examples and Comparative Examples, and evaluation of the obtained sound insulating materials were performed as follows.
(1) The proportion of primary hydroxyl groups in the hydroxyl groups of the polyol. The polyol is subjected to ¹ H NMR, and the amount of primary and secondary hydroxyl groups present in the molecule is quantified. The proportion of primary hydroxyl groups was determined.
(2) Determination of VOC of sound insulating material The sound insulating material was sealed in a sealed container, heated to 100 ° C., and the amount of VOC generated in 10 minutes was measured.
(3) Quantification of low-molecular-weight siloxane compound of sound insulation material The generated VOC is subjected to GC-MS, and the retention time and molecular weight obtained in advance for cyclic and chain organosiloxane compounds having up to 20 silicon atoms in the molecule Compounds showing the same retention time and molecular weight were counted as low molecular siloxane compounds.
(4) Noise test The noise generated in the HDD on which the sound insulating material was placed was measured according to JIS Z8732. That is, in the semi-anechoic chamber, using the measuring apparatus shown in the conceptual diagram of FIG. Also, it was placed at a predetermined position on the holding table 7 for providing a gap behind the HDD. The power source 9 was turned on and the HDD 4 was operated, and the generated noise was picked up by a sound collecting microphone 8 provided 10 cm away immediately above the sample, and the noise level was measured by the analyzer 10.

Examples 1-7, Comparative Examples 1-4
According to the blending ratio shown in Table 2, a polyether polyol, a catalyst, and if necessary, an inorganic filler were blended, and then a prepolymer having an isocyanate compound or an isocyanate group was mixed to prepare a polyurethane foam stock solution. That is, taking Example 1 as an example, a container is charged with 70 parts of P-4 and 30 parts of P-2, to which 0.8 parts of C-1 and 0.2 parts of C-2 are added, The liquid A was prepared by mixing with a stirring mixer. 40 parts of liquid B consisting of a prepolymer having an NCO content of 25%, obtained by the reaction of MDI (mixture of 2,4'- and 4,4'-) and polypropylene glycol, was stirred and mixed. A polyurethane foam stock solution was prepared by mixing until homogeneous. A PET film having a thickness of 0.05 mm and a release liner made of paper provided with a polypropylene release agent layer on one side are placed in parallel with a release agent layer facing the PET film with a gap of 0.15 mm. Foaming and curing were performed by casting the polyurethane foam stock solution in the gap and heating it in a drying furnace at 100 ° C. for 5 minutes. Next, the release liner is peeled off from the formed polyurethane foam, and a cross-sectional conceptual diagram as shown in FIG. 1, the polyurethane foam is used as the sound absorbing layer 1 and the PET film is used as the support 2. Was made. The foaming ratio of the polyurethane foam was 7.0 times. This was punched out with a die cut to produce a sound insulating material of 100 mm × 50 mm. Table 2 shows the appearance and properties of the obtained foam.

Examples 8 to 12, Comparative Examples 5 and 6
As a polyol, P-3 used in Example 2 and P-6 or P-8 used in Comparative Example 2 or 4 were blended, and a polyol mixture having various primary hydroxyl group contents as a whole. A polyurethane foam stock solution was prepared in the same manner as in Example 2. Using this, a polyurethane foam was produced by the same process as in Example 2. Table 3 shows the appearance and properties of the obtained foam. For comparison, the results of Example 2 are also recorded in Table 3.

Comparative Example 5
A liquid A was prepared in the same manner as in Example 1 except that 1.0 part of polydimethylsiloxane / polyoxypropylene graft copolymer was added as a foam stabilizer. A sound insulating material was produced in the same manner as in Example 1 except that the polyurethane foam stock solution obtained by uniformly mixing this with the B liquid used in Example 1 was used.

Comparative Example 6
The polyurethane foam stock solution prepared in Example 1 was cast into a mold to produce a foam block. This was sliced with a blade to prepare a sample having a thickness of 1.0 mm. By removing the release paper from the acrylic adhesive using a silicone release paper for protecting the adhesive, and using it for adhesion, a PET film having a thickness of 0.05 mm is adhered to the sample, and die cutting is performed. A sound insulation material having the same dimensions as in Example 1 and having an adhesive layer 3 between the sound-absorbing layer 1 and the support 2 was produced in the same manner as in the conventional method as shown in FIG.

Comparative Example 7
A sound insulating material was produced in the same manner as in Comparative Example 6 except that the polyurethane foam stock solution prepared in Comparative Example 5 was used.

  With respect to the sound insulating materials obtained in Comparative Examples 5 to 7, the total VOC and low molecular siloxane compounds were quantified. The results are shown in Table 4 together with the values of Example 1 reproduced for comparison. Moreover, the noise test of HDD which installed the sound insulation material obtained in Example 1 and Comparative Examples 5-7, and HDD which does not use a sound insulation material was done. The results are shown in Table 4.

  As is apparent from Table 4, not only a foam stabilizer such as a polysiloxane-polyether graft copolymer was used, but an excellent foamed polyurethane sheet was obtained from Example 1 in which no adhesive was used. The obtained sound insulating material had a lower amount of VOC generation than the sound insulating materials of Comparative Examples 5 and 7 using a foam stabilizer, and in particular, no low molecular siloxane compound was produced. In addition, the total VOC and the amount of low-molecular siloxane compounds generated were excellent as compared with the sound insulating material of Comparative Example 6 using no adhesive but using an adhesive.

  When obtaining a foamed polyurethane sheet without using a foam stabilizer, a satisfactory foam is not always obtained depending on the composition of the stock solution used. As apparent from Table 2 and Table 3, a polyol having a number average molecular weight of 1,500 to 8,000 and 20% or more, preferably 35% or more of the hydroxyl groups in the molecule is a primary hydroxyl group, By using it as a base polymer of polyurethane, an excellent foamed polyurethane sheet could be obtained.

  The foamed polyurethane sheet with a support of the present invention is extremely useful as a sound insulating material for hard disk drives, other electronic devices, and acoustic devices.

It is a section conceptual diagram of the sound insulation material of the present invention. It is a cross-sectional conceptual diagram of the conventional sound insulation material. It is a conceptual diagram of the experimental apparatus of a noise test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sound absorption layer 2 Support body 3 Adhesive layer 4 HDD
5 Substrate 6 Sound insulating material 7 Holding stand 8 Sound collecting microphone 9 Power supply 10 Analyzer

Claims (7)

The support and the polyurethane foam are integrally molded, do not contain an organosiloxane compound, and the polyurethane base polymer has a number average molecular weight of 1,500 to 8,000, and 60 to 80 of hydroxyl groups present in the molecule. A foamed polyurethane sheet with a support for a hard disk drive , wherein % is a polyether polyol having a primary hydroxyl group.   The foamed polyurethane sheet with a support for a hard disk drive according to claim 1, wherein the base polymer is an oxypropylene-based or oxyethylene-oxypropylene-based polyether polyol. A method for producing a foamed polyurethane sheet with a support for a hard disk drive , wherein an organosiloxane compound is not used in the process, and the number average molecular weight is 1,500 to 8,000 as a polyurethane base polymer in the molecule. A production method comprising integrally forming a support and a foam using a polyether polyol in which 60 to 80 % or more of the hydroxyl groups are primary hydroxyl groups. The manufacturing method of Claim 3 using the prepolymer which is a reaction product of diphenylmethane diisocyanate or it and a polyether polyol as an isocyanate compound or a prepolymer. The manufacturing method of Claim 3 or 4 including the process of flowing the material of the foamed polyurethane sheet mixed uniformly between a support body and a release liner. The support and the polyurethane foam are integrally molded, do not contain an organosiloxane compound, and the polyurethane base polymer has a number average molecular weight of 1,500 to 8,000, and 20% or more of the hydroxyl groups present in the molecule A sound insulating material for a hard disk drive comprising a foamed polyurethane sheet with a support , wherein is a polyol having a primary hydroxyl group . A hard disk drive using the sound insulating material according to claim 6 .

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