JP5354923B2 - Method for manufacturing damping material for electronic device parts - Google Patents

Description

  The present invention relates to a vibration damping material for electronic device parts formed by heat compression molding a low-rebound resilience polyurethane foam.

  A hard disk drive (hereinafter referred to as “HDD”) mounted on an electronic device is required to have a member for suppressing the vibration because vibration generated from a motor or a disk propagates to the outside during operation.

  Conventionally, polyurethane foam, particularly low resilience polyurethane foam, has been used to suppress vibration and noise of automobiles, for example, vibration and noise when expanding a refrigerant with an expansion valve that is a piping part of a car air conditioner. Has been demonstrated. However, when polyurethane foam is used as a vibration damping material for electronic device parts, there is a risk of malfunctions such as malfunctions and failures of the electronic device parts. This is because the amine catalyst and silicone surfactant used in the production of the polyurethane foam volatilize and contaminate the control substrate.

There is an example of using a surfactant containing a silanol-containing organosiloxane as a means for suppressing the generation of a silicone-based surfactant (Patent Document 1), but the volatilization of the amine catalyst cannot be sufficiently suppressed, and for electronic device parts. Use as is difficult. There is also known a means for preventing migration of an amine catalyst by using an amine catalyst having a secondary hydroxyl group in the molecule (Patent Document 2). However, the amine catalyst has low hydroxyl group activity and generates amine. Is not sufficiently suppressed. Further, since the catalytic action is weak, the foam formation reaction tends to be dull and the molding tends to be poor. Especially in low resilience polyurethane foams, the average hydroxyl value of polyols generally used is large, so the polymerization activity is strong, and the use of tin catalyst as a polymerization catalyst is often suppressed to a very small amount. The place to rely on becomes larger and the above tendency becomes stronger.
JP 2007-92068 A JP-A-4-85317

This invention is made | formed in view of said present condition, Comprising: The manufacturing method of the damping material for electronic device components with little generation | occurrence | production of outgas is provided.

  As a result of various studies to solve the above problems, the present inventor has produced a specific amine catalyst and a specific foam stabilizer in the production of a low resilience polyurethane foam forming a vibration damping material for electronic device parts. The present inventors have found that a vibration-damping material having excellent vibration damping properties and almost no outgassing can be obtained by hot compression molding the foam, and the present invention has been completed.

That is, the present invention has a rebound resilience formed by using a reactive amine catalyst represented by the following general formula as a catalyst and a silicone surfactant having an active hydrogen group at the structure terminal as a foam stabilizer. % Of the low resilience polyurethane foam is heat compression molded, and the hysteresis loss rate after the heat compression molding is 50% or more, the generation amount of the silicone compound is 0.5 μg / g or less and the total VOC amount is It is possible to obtain a vibration damping material for electronic device parts that generates a very small amount of outgas that is 300 μg / g or less.
<Chemical formula 1>
_{(CH 3) 2 N (CH} 2) X OH (X = 4~8)

The vibration damping material for electronic device parts of the present invention is a silicone having a specific reactive amine catalyst and active hydrogen at the structure terminal as a foam stabilizer in the production of a low resilience polyurethane foam having a resilience of 15% or less. Since a surfactant loss is used and the hysteresis loss rate after hot compression molding is 50% or more, the generation amount of the silicone compound is 0.5 μg / g or less and the total VOC amount is 300 μg / g or less. . Therefore, even if it is used as a damping material for electronic device parts, there is no malfunction such as malfunction or failure of the electronic device.

  The present invention will be described in detail below. The vibration damping material for electronic device parts of the present invention is a low repulsion formed using a specific reactive amine catalyst as a catalyst and a silicone surfactant having an active hydrogen group at the structure terminal as a foam stabilizer. It is made by hot compression molding an elastic polyurethane foam.

  First, the low resilience polyurethane foam will be described. The low resilience polyurethane foam is obtained by foaming and curing using a polyol, a foam stabilizer, a foaming agent, a catalyst or other auxiliary agent and an organic polyisocyanate, and a flexible polyurethane foam having a resilience of 15% or less. It is.

[Polyol component]
As the polyol component used in the present invention, those known as a polyol component constituting a conventionally known low resilience polyurethane foam can be used. For example, polyoxyalkylene polyol, vinyl polymer-containing polyoxyalkylene polyol, polyester A polyol, a polyoxyalkylene polyester block copolymer polyol, etc. can be mentioned.

  Examples of polyoxyalkylene polyols include initiators of polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, trimethylene glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sucrose. Alkylene oxide adducts; alkylene oxide adducts of polyhydric phenols such as bisphenol A; polyhydric hydroxy compounds such as phosphoric acid, polyphosphoric acid (eg, tripolyphosphoric acid and tetrapolyphosphoric acid), phenol-aniline-formaldehyde condensation Products, ethylenediamine, diethylenetriamine, triethylenetetraamine, methylenebisorthochloroaniline, 4,4'- and 2,4'-dipheni Polyamines such as methanediamine, 2,4-tolylenediamine, 2,6-tolylenediamine, alkanolamines such as triethanolamine and diethanolamine, and one kind such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, and styrene oxide Or polyether polyols obtained by adding 2 or more types; or polytetramethylene ether glycol etc. can be illustrated.

  Polyester polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, triethylene glycol, 1,3- and 1,4-butanediol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, decamethylene glycol. , Glycerin, trimethylolpropane, pentaerythritol, sorbit, etc., one or more compounds having at least two hydroxyl groups and malonic acid, maleic acid, succinic acid, adipic acid, tartaric acid, sebacic acid, sulphur Mention may be made of polyester polyols obtained from one or more compounds having at least two or more carboxyl groups such as acid, phthalic acid, terephthalic acid and trimellitic acid. Also, ring-opening polymers of cyclic esters such as polycaprolactone can be used.

  Examples of the vinyl copolymer-containing polyoxyalkylene polyol include those obtained by polymerizing vinyl polymers such as acrylonitrile and styrene in the presence of radicals in the polyoxyalkylene polyols exemplified above. In addition, content of the vinyl polymer in polyoxyalkylene polyol is about 10 to 45 weight% normally.

  The said polyol component is used by 1 type, or 2 or more types of blends. Since the low resilience polyurethane foam has so-called temperature sensitivity that increases in hardness as the outside air temperature decreases, it is preferable to blend two or more polyols, specifically, a high molecular weight polyol having a molecular weight of 2000 to 6000 and a molecular weight. It is preferred to blend 400 to 1500 low molecular weight polyols. The high molecular weight polyol is a polyol having a molecular weight of 2000 to 6000, a functional group number of 2 to 4, and an average hydroxyl value of 20 to 110 mgKOH / g. The low molecular weight polyol has a molecular weight of 400 to 1500 and a functional group number. It is a polyol having 2 to 4 and an average hydroxyl value of 75 to 560 mgKOH / g. When the hydroxyl value of the high molecular weight polyol is small, the molecular weight increases, so that the resilience increases and the return of the foam after compression tends to be accelerated. On the contrary, when the hydroxyl value of the low molecular weight polyol is large, the molecular weight becomes small and tends to be hard, so it is possible to adjust the blend ratio of the polyol to obtain a low rebound resilience polyurethane foam having physical properties that match the purpose of use. I can do it.

  In order to obtain the low resilience polyurethane foam constituting the vibration damping material of the present invention, it is more preferable that the average hydroxyl value of the high molecular weight polyol and the low molecular weight polyol be 90 to 280 mgKOH / g. When the average hydroxyl value is less than 90 mgKOH / g and the average molecular weight is increased, the resilience increases and the return of the foam after compression tends to be faster. When the average hydroxyl value of the polyol is larger than 280 mgKOH / g and the average molecular weight is small, the foam tends to be hard and may be unsuitable as a vibration damping material for electronic device parts.

[Polyisocyanate component]
It does not specifically limit as a polyisocyanate component used in this invention, The well-known polyisocyanate compound normally used for manufacture of a polyurethane foam can be used. Specifically, one or more of aromatic, alicyclic and aliphatic polyisocyanates and modified polyisocyanates obtained by modifying them can be appropriately selected and used.

  As the aromatic polyisocyanate, a mixture of 2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate = 80/20 or 2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate = 65/35 Examples include, but are not limited to, mixtures, diphenylmethane diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, xylylene diisocyanate, polymethylene polyphenyl diisocyanate, and the like.

  Examples of the alicyclic polyisocyanate include cyclohexylmethane diisocyanate and cyclohexane diisocyanate. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate and cyclohexanemethane diisocyanate.

  Among these polyisocyanate compounds, in the present invention, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, which are aromatic polyisocyanates, tends to give good results.

〔catalyst〕
The catalyst used in the present invention is a reactive amine catalyst represented by the following general formula.
<Chemical formula 1>
_{(CH 3) 2 N (CH} 2) X OH (X = 4~8)
By using the reactive amine catalyst represented by the above general formula, the activity as a catalyst is high, and the amount of free amine can be suppressed when a foam is formed. The reason for this is not necessarily clear, but it has high activity as a catalyst because of its small steric hindrance of N, and is highly reactive due to its primary hydroxyl group and low steric hindrance, and is easily involved in the polymerization of urethane resins. This is probably because of this. The addition amount of the amine catalyst is preferably about 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the polyol component.

  In the present invention, in addition to the reactive amine catalyst represented by the above general formula, other catalysts used for producing polyurethane foam may be used as long as the total VOC amount is within a range of 300 μg / g or less. It is possible to combine them.

[Foam stabilizer]
As the foam stabilizer used in the present invention, a reactive silicone surfactant having an active hydrogen group at the structure terminal is used. Examples of the reactive silicone surfactant having an active hydrogen group at the structure terminal include silicone surfactants having a structure terminal at the hydroxyl group, amino group, and the like. Specifically, SZ-1327, SZ-1333, SZ-1718, SZ-1710, SF-2937F, SF-2945F, SH-193 manufactured by Toray Dow Corning Co., Ltd., F- manufactured by Shin-Etsu Chemical Co., Ltd. 114, F-341, F-345, F-305 Momentive Performance Materials, Inc. L-626, and the like. By using a reactive silicone surfactant having an active hydrogen group at the structure terminal, it is possible to make the cell properties of the foam uniform, and the silicone surfactant is incorporated into the urethane resin. Therefore, generation of outgas derived from the silicone compound can be suppressed to 0.5 μg / g or less. The addition amount of the silicone surfactant is preferably 0.5 to 1.5 parts by weight with respect to 100 parts by weight of the polyol.

[Foaming agent]
As the blowing agent used in the present invention, it is environmentally preferable to use only water as the blowing agent. However, if necessary, low boiling point organic compounds such as trichloromonofluoromethane and methylene chloride, carbon dioxide and the like are also used. be able to.

[Other additives]
In the low resilience polyurethane foam constituting the vibration damping material of the present invention, conventionally known antioxidants, light stabilizers, ultraviolet absorbers, flame retardants, pigments and the like can be used as other additives as required.

  The method for producing a low-rebound resilience polyurethane foam constituting the vibration damping material of the present invention can be performed based on a conventionally used method for producing a low-rebound resilience polyurethane foam. For example, a prepolymer method, a one-shot method Etc. can be applied.

The low resilience polyurethane foam constituting the vibration damping material for electronic device parts of the present invention preferably has a density of 40 to 100 kg / m ³ . An excellent vibration damping property can be obtained by hot compression molding a low-rebound resilience polyurethane foam having a density of 40 to 100 kg / m ³ . Moreover, in the same volume, since a thing with a low density can suppress generation | occurrence | production of outgas more, More preferably, it is 40-80 kg / m < ³ >.

  The vibration damping material for electronic device parts of the present invention is obtained by hot compression molding the above-mentioned low-resilience polyurethane foam. The low resilience polyurethane foam used in the present invention uses a reactive amine catalyst and a reactive silicone-based surfactant having an active hydrogen group at the structure terminal to generate silicone compounds and VOCs to some extent. Can be suppressed. And generation | occurrence | production of those outgas can be further suppressed by carrying out hot compression molding. This is considered to be because the amine catalyst and silicone foam stabilizer remaining without being incorporated into the skeleton of the low-rebound resilience polyurethane foam volatilize by heat. Therefore, the generation amount of the silicone compound can be 0.5 μg / g or less and the total VOC amount can be 300 μg / g or less.

  The compression ratio can be appropriately set depending on the use of the damping material, but it is preferably 1.5 to 5 times in view of both sides of damping performance and suppression of outgas generation. Low resilience polyurethane foam generally has a high hysteresis loss rate. However, when low resilience polyurethane foam is heat compression molded at a compression ratio of 1.5 to 5 times, the hysteresis loss rate is further increased and the material has excellent shock absorption. It becomes. On the other hand, if it exceeds 5 times, the density increases and the amount of outgas generated tends to increase.

  As a method for hot compression molding, a method of hot pressing the hot plate at 160 to 220 ° C. for about 30 seconds to 5 minutes to obtain a desired compression ratio is preferable.

  The thickness of the vibration damping material formed by heat compression molding the low resilience polyurethane foam of the present invention can be set as appropriate depending on the application to be used. For example, it is about 0.5 to 5 mm for HDDs.

  The vibration damping material obtained by heat compression molding the low resilience polyurethane foam of the present invention is produced by producing the low resilience polyurethane foam with the above-described configuration, and is excellent in vibration damping properties by generating the silicone compound. Is 0.5 μg / g or less, and a damping material having a total VOC amount of 300 μg / g or less is obtained. Therefore, even if it is used as a vibration damping material for electronic device parts, problems such as malfunction and failure do not occur.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited by these Examples.
<Examples 1 to 10, Comparative Examples 1 to 7>
A low resilience polyurethane foam was produced according to the formulation shown in Table 1. That is, a low rebound resilience polyurethane foam (a polyurethane foam which is not low rebound resilience in Comparative Example 1) is obtained by stirring and mixing a polyol, a foam stabilizer, a catalyst and a foaming agent, adding a polyisocyanate thereto, and mixing and foaming. Manufactured. The obtained low resilience polyurethane foam was subjected to hot compression molding at a compression ratio shown in Table 1 by a hot press method (180 ° C., 3 minutes) to obtain a damping material.

  The following measurements and evaluations were performed on the low resilience polyurethane foams used in the examples and comparative examples.

<Form properties>
Judgment was made visually.

◯: Low foam ratio, fine and uniform cells △: High foam ratio and foam shrink

<Density>
It measured according to JIS K7222.

<Rebound resilience>
It measured according to JIS K6400.

  The following measurements were performed on the vibration damping materials obtained in the examples and comparative examples.

<Hysteresis loss rate>
It measured according to JIS K6400.
In addition, it can be said that when the hysteresis loss rate is high (in particular, 50% or more), the impact absorption is high and the vibration damping property is excellent.

<Outgas generation amount>
The damping material obtained in each example and comparative example was cut into 1 cm length × 5 cm width × 0.1 cm thickness, weighed, put into a glass tube exclusively for thermo extractor, and high purity nitrogen gas at 80 ° C. Was extracted by heating at 50 mL / min for 20 minutes, and the generated gas was collected in an adsorption tube and measured by thermal desorption-gas chromatography / mass spectrometry to determine the generation amount of silicone compound and total VOC.
(A) Silicone compound About the siloxane gas component, the component amount was calculated | required in toluene conversion.
○: Less than 0.5 μg / g ×: 0.5 μg / g or more (B) Total VOC
◯: Less than 250 μg / g Δ: 250 μg / g to 300 μg / g
X: 300 μg / g or more

In the table:
Polyol A: Polyether polyol Number of functional groups 3, OHv = 240, Mw = 700 (EXCENOL 730 manufactured by Asahi Glass Co., Ltd.)
Polyol B: Polyether polyol Number of functional groups 3, OHv = 56, Mw = 3000 (EXCENOL 3030 manufactured by Asahi Glass Co., Ltd.)
Foam stabilizer A: Reactive silicone surfactant L-626, manufactured by Momentive Performance Materials
Foam stabilizer B: Reactive silicone surfactant F-114 manufactured by Shin-Etsu Chemical Co., Ltd.
Foam stabilizer C: Silicone surfactant SH-192 manufactured by Toray Dow Corning
Catalyst A: Amine catalyst Triethylenediamine 33% Dipropylene glycol 67% mixture Catalyst B: Reactive amine catalyst N, N-dimethylaminohexanol catalyst C: Reactive amine catalyst N, N-dimethylaminobutanol catalyst D: Reactive amine Catalyst N, N-dimethylaminododecanol catalyst E: Reactive amine catalyst N, N-diethylaminohexanol catalyst F: Reactive amine catalyst N, N-dimethylaminoethoxyethanol catalyst G: Tin catalyst Neostan U-28 manufactured by Nitto Kasei Co., Ltd.

As can be seen from Table 1, in Examples 1 to 9 , almost no outgas was generated, and a vibration damping material excellent in shock absorption was obtained.

On the other hand, Comparative Example 1 used a foam having a rebound resilience exceeding 15%. Therefore, a hysteresis loss ratio was low, and a vibration damping material excellent in shock absorption was not obtained.
Since Comparative Example 2 did not use a silicone-based surfactant having an active hydrogen group at the structure terminal as a foam stabilizer, generation of a silicone compound could not be suppressed, and was not suitable as a vibration damping material for electronic device parts. It was.
Since Comparative Examples 3 to 6 used an amine catalyst other than those specified in the present application, generation of outgas could not be suppressed, and it was unsuitable as a damping material for electronic device parts.
In Comparative Example 7, since the low resilience polyurethane foam was not subjected to hot compression molding, generation of outgas could not be sufficiently suppressed.

Claims (2)

A method for producing a damping material for electronic device parts comprising a polyurethane foam obtained by reacting at least a polyol component, a polyisocyanate component, a catalyst, a foam stabilizer, and a foaming agent,
The polyurethane foam is formed by using a reactive amine catalyst represented by the following general formula as the catalyst and a silicone surfactant having an active hydrogen group at the structure terminal as the foam stabilizer. Is formed by heat compression molding a low resilience polyurethane foam of 15% or less,
The hysteresis loss rate of the heat-resisting molded low resilience polyurethane foam is 50% or more,
A method for producing a vibration damping material for electronic device parts, wherein the generation amount of the silicone compound is 0.5 μg / g or less and the total VOC amount is 300 μg / g or less.
<Chemical formula 1>
_{(CH 3) 2 N (CH} 2) X OH (X = 4~8) A method for producing a damping material for electronic device parts, wherein the low resilience polyurethane foam according to claim 1 is heat compression molded at a compression ratio of 1.5 to 5 times.