JP2008024856A - Shock-buffering material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shock-buffering material exhibiting a good shock-buffering property, releasing less volatile components, and suitable for precision OA instruments such as a hard disc drive, etc., having a fear of being broken by released gas, vibration and shock. <P>SOLUTION: This shock-buffering material consisting of a soft polyurethane foam formed from foaming raw materials containing a polyol, polyisocyanate, blowing agent, catalyst and foam stabilizer is provided by using water as the blowing agent, containing a reactive catalyst having functional groups in the catalyst, using a silicon compound having active hydrogens as the foam stabilizer, and setting 0.8 to 1.2 pts.wt. amount of water as the blowing agent based on 100 pts.wt. polyol, and also 100 to 110 isocyanate index. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an impact cushioning material, and more particularly to an impact cushioning material made of a flexible polyurethane foam.

  Conventionally, shock-absorbing materials have been used in devices that are easily damaged by impact. For example, in hard disk drives, it has been proposed to place columnar shock absorbers made of foamed resin at the upper and lower four corners inside the housing, and plate-like shock absorbers made of foamed resin on the side surfaces. (See Patent Document 1).

  In addition, it has been proposed to use a soft low-resilience polyurethane foam using a low molecular weight polyol and having an isocyanate index lower than 100 as a damping material for precision OA equipment and the like (see Patent Document 2). In addition, making an isocyanate index lower than 100 is what is generally performed in energy-absorbing flexible polyurethane foam (for example, refer to the Example of patent document 3).

  By the way, in precision OA equipment, particularly hard disk drives, if volatile components may be emitted from components such as the housing, they may adhere to the disk surface and cause malfunctions. It is required that volatile components are not released from these components.

  However, the conventional shock-absorbing material made of flexible polyurethane foam cannot be said to have a sufficient countermeasure against the emitted gas (the countermeasure against the emission of volatile components), and has a problem of the emitted gas with respect to precision OA equipment such as the hard disk drive. In particular, since the flexible polyurethane foam is formed by the reaction of isocyanate groups in the raw material and active hydrogen, when the isocyanate index is lowered, unreacted components tend to remain in the flexible polyurethane foam. Therefore, in an impact buffer material made of a flexible polyurethane foam having an isocyanate index lower than 100, volatile components are released from unreacted components remaining in the flexible polyurethane foam, and the released gas causes a hard disk drive or the like. May cause malfunction.

  Furthermore, usually, a flexible polyurethane foam contains an amine catalyst in the catalyst. However, the amine catalyst is not always used in the reaction, and a part of the amine catalyst may remain in the flexible polyurethane foam. is there. Therefore, the conventional shock-absorbing material made of flexible polyurethane foam may cause gas to be released from the residual amine catalyst and cause malfunction of the hard disk drive.

JP 2005-256882 A JP 2001-288240 A JP 2000-290344 A

  The present invention has been made in view of the above-mentioned points, and exhibits good shock buffering properties, and emits less volatile components. When used in a hard disk drive, the present invention reduces the adverse effects of the emitted gases. The purpose is to provide an impact cushioning material that can be used.

  The invention according to claim 1 is an impact cushioning material made of a flexible polyurethane foam formed from a foaming raw material including a polyol, a polyisocyanate, a foaming agent, a catalyst, and a foam stabilizer, wherein the foaming agent comprises water, and the catalyst is functional. At least a reactive catalyst having a group, the foam stabilizer is made of a silicon compound having active hydrogen, and the amount of water as the blowing agent is 0.8 to 1.2 parts by weight with respect to 100 parts by weight of the polyol. The isocyanate index is 100 to 110.

  The invention of claim 2 is characterized in that, in claim 1, the polyisocyanate is 2,4-toluene diisocyanate / 2,6-toluene diisocyanate = 65/35.

  A third aspect of the invention is characterized in that, in the first or second aspect, the foam stabilizer is composed of a linear silicon compound having active hydrogen.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the density of the flexible polyurethane foam is 80 kg / m ³ or more.

  According to the present invention, since the catalyst includes a reactive catalyst having a functional group, the foam stabilizer is made of a silicon compound having active hydrogen, and the isocyanate index is 100 to 110, the volatile component in the flexible polyurethane foam When the shock-absorbing material of the present invention is used in a hard disk drive, adverse effects due to volatile component released gas can be reduced. Furthermore, the amount of water as the foaming agent was set to 0.8 to 1.2 parts by weight with respect to 100 parts by weight of the polyol, so that the vibration damping of the shock absorbing material could be improved.

  Hereinafter, embodiments of the present invention will be described in detail. The shock-absorbing material of the present invention is suitable as a shock-absorbing material for OA equipment that is particularly vulnerable to shock, vibration and emitted gas, such as a hard disk drive, and includes a polyol, polyisocyanate, foaming agent, catalyst, and foam stabilizer. It consists of the flexible polyurethane foam formed from the foaming raw material containing.

  As the polyol used in the present invention, any one or both of known ether polyols and ester polyols used in flexible polyurethane foams can be used. Examples of ether polyols include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sucrose, or polyhydric alcohols thereof. The polyether polyol which added alkylene oxides, such as ethylene oxide and a propylene oxide, can be mentioned. As ester polyols, polycondensation of aliphatic carboxylic acids such as malonic acid, succinic acid and adipic acid and aromatic carboxylic acids such as phthalic acid and aliphatic glycols such as ethylene glycol, diethylene glycol and propylene glycol. The polyester polyol obtained in this way can be mentioned.

  In particular, the polyol preferably contains a polyol that exhibits low resilience. The polyol exhibiting low resilience (that is, low resilience polyol) is a blended polyol obtained by physically mixing polyols having different molecular weights (low molecular weight polyol and high molecular weight polyol). The low molecular weight polyol preferably has a molecular weight of 700 to 3000 and an average functional group number of 1.5 to 4.5, while the high molecular weight polyol preferably has a molecular weight of 4000 to 12000 and an average functional group number of 1.5 to 4.5. The ratio of the low molecular weight polyol to the high molecular weight polyol is preferably 50 to 80% by weight of the low molecular weight polyol, and the rest as the high molecular weight polyol. When the proportion of the low molecular weight polyol is small, the crosslink density is low and the low resilience is not expressed. On the other hand, when the proportion of the low molecular weight polyol is large, the crosslink density is high and the resulting flexible polyurethane foam is hard. As a result, the shock-absorbing property becomes worse.

  Examples of the low molecular weight polyol and the high molecular weight polyol include one or more selected from polyoxyalkylene polyol, vinyl polymer-containing polyoxyalkylene polyol, polyester polyol, and polyoxyalkylene polyester block copolymer polyol. preferable.

  The polyol that exhibits low resilience may be used alone, but the amount of polyol that exhibits low resilience is more preferably 30 to 90 parts by weight in 100 parts by weight of all polyols.

  The polyisocyanate used in the present invention is preferably toluene diisocyanate (referred to as TDI). More preferably, 2,4-toluene diisocyanate / 2,6-toluene diisocyanate = 65/35 (commonly referred to as T-65). By setting the polyisocyanate to T-65, a flexible polyurethane foam having high rigidity can be obtained, and thus excellent vibration damping properties are exhibited.

  The blowing agent used in the present invention consists of water. The amount of water is 1.2 parts by weight or less with respect to 100 parts by weight of polyol. When the amount of water exceeds 1.2 parts by weight with respect to 100 parts by weight of the polyol, the density becomes low and the vibration damping properties become poor. The lower limit of the amount of water is determined in consideration of the foamability of the flexible polyurethane foam. A more preferable range of the amount of water is 0.8 to 1.2 parts by weight with respect to 100 parts by weight of polyol.

  As the catalyst used in the present invention, a reactive catalyst having a functional group is used alone or in combination with another catalyst. The reactive catalyst having a functional group refers to a catalyst having a hydroxyl group. Examples of the reactive catalyst having a functional group include dimethylaminoethanol, trimethylaminoethanolamine, trimethylaminopropanolamine, hydroxyethylmorpholine, hydroxypropylimidazole, trisdimethylaminomethylphenol, triethanolamine and the like. Examples of the catalyst used together with the reactive catalyst having a functional group include a tin catalyst such as stannous octoate and dibutyltin dilaurate, and a metal catalyst such as phenylmercurypropionate or lead octenoate (also referred to as an organometallic catalyst). .). In addition, although the compounding quantity of the reactive catalyst which has the said functional group is suitably determined by the kind of catalyst, about 0.2-1.0 weight part is preferable with respect to 100 weight part of polyols. Moreover, although the compounding quantity of the said metal catalyst is suitably determined by the kind of catalyst, about 0.01-0.1 weight part is preferable with respect to 100 weight part of polyols.

  The foam stabilizer used in the present invention is a silicon compound having active hydrogen (that is, a reactive silicon compound). By using a silicon compound having active hydrogen as a foam stabilizer, volatile components can be reduced. In particular, the silicon compound having active hydrogen is preferably linear. By adopting a straight chain, the gas release at the time of foaming of the flexible polyurethane foam is improved and the degree of communication is improved, so that the flexible polyurethane foam is easily elastically deformed, and an impact cushioning material having excellent vibration damping properties. can get. Examples of the linear silicon compound having active hydrogen include polyoxyalkylene / dimethylpolysiloxane copolymer. The compounding amount of the silicon compound having active hydrogen is appropriately determined depending on the type of the silicon compound, but is usually preferably about 0.5 to 1.5 parts by weight with respect to 100 parts by weight of the polyol.

  In addition, auxiliary agents are appropriately blended. For example, a crosslinking agent, a flame retardant, a coloring agent, etc. can be mentioned. As a crosslinking agent, the polyhydric alcohol etc. which are used as a crosslinking agent in normal flexible polyurethane foam can be used. For example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, hexanediol, glycerin, trimethylolpropane, polyethylene glycol, polypropylene glycol and the like can be mentioned. Although the compounding quantity of a crosslinking agent is suitably determined by the kind of crosslinking agent, 0.5-2.0 weight part is preferable normally with respect to 100 weight part of polyols. Moreover, as a flame retardant, a non-halogen type thing is preferable. Examples thereof include expansive graphite, magnesium hydroxide, aluminum hydroxide, phosphorus polyphosphate such as ammonium phosphate and red phosphorus, and silicone powder. Although the compounding quantity of a flame retardant is suitably determined by the kind of flame retardant, 1.0-10.0 weight part is preferable normally with respect to 100 weight part of polyols. Moreover, the colorant according to the color calculated | required by the impact buffering material of this invention is used, and the compounding quantity of a colorant is determined according to the color etc. calculated | required.

  In the present invention, the isocyanate index is 100 or more. The isocyanate index is calculated by [(isocyanate equivalent in foaming raw material / equivalent of active hydrogen in foaming raw material) × 100]. When the isocyanate index is less than 100, the flexible polyurethane foam has an increased volatile component, and has poor impact resilience and compressive strain, making it unpreferable as an impact buffer. In the present invention, the preferable upper limit of the isocyanate index is 110. When the isocyanate index exceeds 110, the hardness increases and the impact absorbability decreases.

The density of the flexible polyurethane foam constituting the cushioning material is preferably 80 kg / m ³ or more. When the density is less than 80 kg / m ³ , the vibration damping performance decreases. A preferable upper limit of the density is 100 kg / m ³ . When the density exceeds 100 kg / m ³ , the hardness is increased and the impact absorbability is lowered. More preferred density in the range ^{is 80kg / m 3 ~90kg / m 3} .

  The production of the flexible polyurethane foam constituting the impact cushioning material is performed by preparing a foaming raw material from the polyol, polyisocyanate, foaming agent, catalyst, foam stabilizer and appropriate additive aid, and then subjecting the foaming raw material to room temperature and atmospheric pressure. It is preferably carried out by known slab foaming to be reacted. Specifically, a foam, a foaming agent, a catalyst, a foam stabilizer, and appropriate additives are mixed, and a foaming raw material obtained by mixing polyisocyanate with this mixture with a known polyurethane injector is discharged onto a belt conveyor. And while a belt conveyor moves, a flexible polyurethane foam can be continuously manufactured by making the said foaming raw material react at normal temperature atmospheric pressure, making it foam naturally, and making it harden | cure. The flexible polyurethane foam thus obtained is appropriately cut into a required size according to the target device to be used, and used as an impact cushioning material.

  Examples of the present invention will be specifically described below together with comparative examples. Each component shown in Table 1 is blended in the proportions in the table to prepare a foaming raw material, and the foamed raw material obtained by this preparation is slab-foamed. The resulting flexible polyurethane foam is 200 × 200 × 30 mm. The impact buffer material of the Example and the comparative example was obtained by cutting.

  In Table 1, polyol 1 is product number: G700, polyether polyol, MW700, functional group number f = 3, OH number = 240, manufactured by Asahi Denka Co., Ltd., polyol 2 is low-repulsive polyol, product number: Actol LR00, MW1600, A blended product of 65% polyether polyol having a functional group number f = 3 and MW 5000, 35% polyether polyol having a functional group number f = 3, OH number = 106, manufactured by Mitsui Takeda Chemical Co., Ltd., a reactive catalyst having a functional group, An amine catalyst having a hydroxyl group as a functional group, product number: KL No81, manufactured by Kao Corporation, non-reactive catalyst is triethylenediamine 33% propylene glycol, product number: 33LV, manufactured by Chukyo Oil Co., Ltd., metal catalyst is stannous octylate , Product No .: MRH110, manufactured by Johoku Chemical Industry Co., Ltd., Silico with active hydrogen The compound (foam stabilizer) is a foam stabilizer made of a linear silicon compound having active hydrogen, product number: L626, manufactured by GE Toshiba Silicone Co., Ltd., and the silicon compound without active hydrogen (foam stabilizer) has active hydrogen. No foam stabilizer made of non-linear silicon compound, product number: F650, manufactured by Shin-Etsu Chemical Co., Ltd., crosslinker is 1,4-butanediol, flame retardant is phosphate ester compound, polyisocyanate is 2,4-toluene Diisocyanate / 2,6-toluene diisocyanate = 65/35, product number: T-65, manufactured by Nippon Polyurethane Industry Co., Ltd.

  Examples 1 and 2 are examples in which the isocyanate index is set to 100 and 110. Examples 1 and 3 to 4 are examples of the flexible polyurethane foam in which the isocyanate index is set to 100 and the amount of polyol 2 is changed. This is an example in which the density is changed. On the other hand, Comparative Example 1 is an example in which the isocyanate index is 90 which is outside the range of the present invention with respect to 100 of Example 1, and Comparative Example 2 is based on 1 part by weight of Example 1 with respect to 1 part by weight of water. This is an example of 1.5 parts by weight. Comparative Example 3 is an example in which a non-reactive catalyst was used instead of the reactive catalyst having a functional group in Example 3. Comparative Example 4 is an example in which a non-linear silicon compound that does not wait for active hydrogen is used instead of the linear silicon compound having active hydrogen. Comparative Example 5 is an example in which the amount of water is 0.7 parts by weight, which is less than the range of the present invention.

  The density (JIS K 7222: 1999 compliant), compressive strain (JIS K 6400-4: 2004 A method compliant), impact resilience (JIS K 6400-3: 2004), and the examples and comparative examples thus obtained. Compliant), flame retardancy (based on UL-94), and VOC (volatile organic compound, based on VDA278). The measurement results are shown in the lower column of Table 1. In Comparative Example 5 in which the amount of water is 0.7 parts by weight less than the range of the present invention, the flexible polyurethane foam shrinks (shrinks) and does not become a good foam, and the density, compressive strain, rebound resilience, difficulty Neither flammability nor VOC could be measured.

As understood from the measurement results shown in Table 1, the shock-absorbing materials of Examples 1 to 4 have a density of 85.0 to 91.7 kg / m ³ and sufficiently small compressive strain and impact resilience. Moreover, it emits less volatile components and has flame retardancy. From this, it can be seen that the shock-absorbing material of the present invention is suitable as a shock-absorbing material in precision OA equipment, particularly a hard disk drive, which may be damaged by shock or released gas.

  On the other hand, Comparative Example 1 (an example in which the isocyanate index is 90 lower than the range of the present invention) has a very large impact resilience compared to the Examples, is inferior in shock absorption, and is easily damaged by an impact. Etc. are not preferable. Comparative Example 3 (an example in which a non-reactive catalyst is used instead of a reactive catalyst having a functional group) and Comparative Example 4 (a non-linear chain that does not wait for active hydrogen instead of a linear silicon compound having active hydrogen) This example using a silicon compound is not preferable for a hard disk drive or the like in which the amount of released gas (VOC value) is much larger than that of the example and is easily affected by the released gas.

  In addition, Comparative Example 2 (an example in which water is 1.5 parts by weight more than the range of the present invention) is equivalent to Example 1 in terms of measurement results of compression strain, impact resilience, flame retardancy, and released gas (VOC). Met. Therefore, it was examined whether or not there was a difference in vibration damping between Example 1 and Comparative Example 2. The vibration damping property was measured by the central support steady vibration method in accordance with JIS G 0602, the vibration damping characteristic test method for the damping steel plate. At that time, the shock-absorbing material of Example 1 and Comparative Example 1 was 30 × 300 × 10 mm thick, and was attached to an iron plate having a thickness of 1.0 mm with a double-sided adhesive tape to obtain a measurement specimen. The test temperature is 20 ° C. and the number of tests n = 3. Further, the loss factor was calculated from the half-value width of the resonance point of the mechanical impedance (F / V) at the excitation point. The result is shown in FIG. As understood from FIG. 1, Comparative Example 2 in which the amount of water blended is 1.5 parts by weight, which is larger than the range of the present invention, has a smaller loss coefficient than that of Example 1 and is inferior in vibration damping. . From this, it can be seen that when the amount of water exceeds the range of the present invention, the shock-absorbing material becomes inferior in vibration damping properties, which is not preferable for a hard disk drive or the like that is easily affected by vibration.

It is a graph which shows the vibration damping measurement result of Example 1 and Comparative Example 2.

Claims (4)

In an impact cushioning material comprising a flexible polyurethane foam formed from a foaming raw material containing a polyol, a polyisocyanate, a foaming agent, a catalyst, and a foam stabilizer,
The blowing agent is made of water;
The catalyst includes a reactive catalyst having a functional group,
The foam stabilizer comprises a silicon compound having active hydrogen,
The shock absorbing material, wherein the amount of water as the foaming agent is 0.8 to 1.2 parts by weight with respect to 100 parts by weight of the polyol, and the isocyanate index is 100 to 110.   2. The impact buffering material according to claim 1, wherein the polyisocyanate is 2,4-toluene diisocyanate / 2,6-toluene diisocyanate = 65/35.   The shock absorbing material according to claim 1 or 2, wherein the foam stabilizer is made of a linear silicon compound having active hydrogen. The impact buffer material according to any one of claims 1 to 3, wherein the density of the flexible polyurethane foam is 80 kg / m ³ or more.

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