JP2010267494A - Silencer sheet for electronic device operation section - Google Patents

Abstract

Disclosed is a silencer sheet for an electronic device operation unit which is excellent in heat resistance and can improve the silencing effect without impairing the operability of the electronic device.
A sound deadening sheet made of a silicone elastomer and applied to an electronic device operation unit, wherein the sheet has a loss coefficient (tan δ) of 0 measured at a frequency of 10 Hz and a temperature of 20 ° C. by dynamic viscoelasticity measurement. 0.1 to 0.6, and the thickness is in the range of 30 μm to 500 μm.
[Selection] Figure 4

Description

  The present invention relates to a silencer sheet for an electronic device operation section made of a specific elastomeric sheet, and more specifically, an electronic device operation that has excellent heat resistance and improved noise reduction effect without impairing operability when using the electronic device. The present invention relates to a sound deadening sheet for a department.

  In general, various soundproofing devices such as soundproofing walls and soundproofing sheets are used as soundproofing measures in places where high noise is generated such as highways and trains, and construction sites. However, even in an electronic device used in a quiet environment, for example, in an office, it is required to reduce not only the operation sound emitted from the device itself but also the operation sound in the operation unit of the device. Examples of the operation sound include a keystroke sound of a button constituting a pointing device of a personal computer, and a contact sound (return sound) with a case when the button returns.

  Conventionally, non-woven fabrics such as rock wool, glass wool, felt, and the like are known as sound-absorbing sheets used in the operation unit of electronic equipment. Specifically, there is a silencer sheet disclosed in Patent Document 1. The silencer sheet of Patent Document 1 is a push button switch composed of a case and a key button fitted therein, and a silencer sheet, for example, a nonwoven fabric, felt or the like is arranged at the contact portion between the case and the key button. Absorbs contact sound (key button return sound). In this sound deadening sheet, the sound energy is absorbed by being consumed as frictional heat when sound passes through the fiber surface constituting the sheet while colliding. However, in this sound deadening sheet, when it is going to ensure sufficient sound deadening property, the thickness of a millimeter unit (for example, 1-30 mm) is required. The sound-absorbing sheet disclosed in Patent Document 1 has a problem that the operability of the operation unit is not a little affected by its bulkiness, particularly in electronic devices that tend to be miniaturized.

  For example, the sheet | seat disclosed by patent document 2 as a silencer sheet other than a nonwoven fabric is mentioned. The sheet of Patent Document 2 is composed of a multilayer of a high elastic constraining layer such as an aluminum foil, a medium elastic constraining layer such as an olefin elastomer, and an acrylic low elastic adhesive layer. This uses the characteristics of the viscoelastic material constituting each layer and utilizes the internal heat generated by the expansion and contraction of the viscoelastic material, thereby exhibiting a silencing effect while damping the vibration-damped body.

Japanese Utility Model Publication No. 7-16337 Japanese Patent Laid-Open No. 5-220883

  However, the sheet disclosed in Patent Document 2 uses a thermoplastic elastomer and does not have sufficient heat resistance. Therefore, there is a problem that it cannot be easily applied to an electronic device that generates heat. In addition, the sheet of Patent Document 2 has a problem that it is not easy to apply without affecting the operability in an electronic device that is not sufficiently thin and tends to be downsized and thinned.

  As a result of diligent research by the present inventors, the present invention has found that by using a silicone elastomer having a predetermined characteristic, it is excellent in heat resistance and can improve the silencing effect without impairing the operability of the electronic device. It is based on that.

  The object of the present invention is to provide a silencer for an electronic device operation unit that is excellent in heat resistance and can improve the silencing effect without impairing the operability of the electronic device in a silencer sheet applied to the electronic device operation unit. To provide a sheet.

  In order to achieve the object of the present invention, the sound deadening sheet for an electronic device operation section according to claim 1 is a sheet made of a silicone elastomer, and the sheet has a frequency of 10 Hz and a temperature measured by dynamic viscoelasticity measurement. The loss coefficient (tan δ) measured at 20 ° C. is in the range of 0.1 to 0.6, and the thickness is in the range of 30 μm to 500 μm.

  According to a second aspect of the present invention, in the sound deadening sheet for an electronic device operation unit according to the first aspect, the sheet has a cyclic siloxane content of 10 ppm or less of 2000 ppm or less.

  According to a third aspect of the present invention, in the sound deadening sheet for an electronic device operation section according to the first or second aspect, at least one surface of the sheet has adhesiveness derived from the silicone elastomer. Features.

  According to a fourth aspect of the present invention, in the sound deadening sheet for an electronic device operating unit according to any one of the first to third aspects, at least one surface of the sheet is embossed. Features.

  The invention according to claim 5 is the sound deadening sheet for the electronic device operation unit according to any one of claims 1 to 4, wherein the operation unit is an operation button of a pointing device. To do.

  ADVANTAGE OF THE INVENTION According to this invention, in the muffling sheet | seat applied to an electronic device operation part, it is excellent in heat resistance and can improve a muffling effect, without impairing the operativity of an electronic device.

The perspective view of a pushbutton main body. Top view of push button body The top view when the cover part 13 of a pushbutton main body is removed. FIG. 3 is a cross-sectional view of the push button body taken along line AA in FIG. 2.

Hereinafter, an embodiment embodying a sound deadening sheet applied to the electronic device operation unit of the present invention will be described.
A muffler sheet (hereinafter referred to as “muffer sheet”) applied to the electronic device operation unit of the present embodiment is composed of a silicone elastomer sheet in order to improve heat resistance. As the silicone elastomer constituting the sound deadening sheet, for example, a silicone elastomer obtained by crosslinking polyorganosiloxane having a siloxane skeleton as shown below can be used.

このシリコーンエラストマーは、Ｒのすべてがメチル基であるポリジメチルシロキサンをはじめ、メチル基の一部が他のアルキル基、ビニル基、フェニル基、フルオロアルキル基などの一種あるいはそれ以上と置換された各種のポリオルガノシロキサンを単独又は二種類以上ブレンドしたものを使用することができる。

This silicone elastomer includes polydimethylsiloxane in which all of R is a methyl group, and various methyl groups in which a part of the methyl group is substituted with one or more of other alkyl groups, vinyl groups, phenyl groups, fluoroalkyl groups, etc. These polyorganosiloxanes can be used singly or as a blend of two or more.

  The crosslinking method is not particularly limited, and conventionally known methods can be applied. For example, a method of cross-linking a methyl group or vinyl group of polyorganosiloxane by a radical reaction can be mentioned. Moreover, the method of bridge | crosslinking by the condensation reaction of the silanol terminal polyorganosiloxane and the silane compound which has a hydrolyzable functional group, the method of bridge | crosslinking by the addition reaction of the hydrosilyl group to a vinyl group, etc. are mentioned. Moreover, you may use the method of carrying out radiation crosslinking. As the radiation, γ-rays, electron beams, X-rays and the like can be suitably used.

  Furthermore, additives that are conventionally known to be added to the silicone elastomer composition may be added to the silicone elastomer within a range that does not impair the physical properties of the present invention. In addition to reinforcing fillers such as fumed silica, precipitated silica, diatomaceous earth, and quartz powder, various processing aids, heat resistance improvers, and the like, various additives that provide functionality as an elastomer are contained. Examples of the functional additive include a flame retardancy imparting agent, a heat dissipating filler, and a conductive filler.

  The lower limit of the thickness of the sound deadening sheet is 30 μm, preferably 100 μm, more preferably 150 μm, and the upper limit is 500 μm, preferably 300 μm, more preferably 250 μm. When the thickness of the sound-absorbing sheet is less than 30 μm, the sound-absorbing property is lowered, the handleability (handling) is deteriorated, and the production cost may be increased. On the other hand, if the thickness of the sound deadening sheet exceeds 500 μm, the operability may be affected when the sound deadening sheet is arranged in a contact portion that emits a contact sound, for example, a contact portion between a case and a button. In addition, the manufacturing cost may increase due to the increase in bulk.

  The silencing sheet is a silicone elastomer sheet having a loss factor (tan δ) measured by dynamic viscoelasticity measurement at a frequency of 10 Hz and a temperature of 20 ° C. in the range of 0.1 to 0.6, preferably 0.2 to 0.4. Is used. If the loss coefficient (tan δ) is less than 0.1, the sound deadening property is lowered. On the other hand, when the loss coefficient (tan δ) exceeds 0.6, the stickiness becomes strong and the handleability deteriorates. The loss factor (tan δ) is a physical property value affected by the molecular structure and cross-linking state of the polyorganosiloxane, and can be adjusted, for example, by selecting the molecular structure and cross-linking conditions of the raw rubber. Examples of the molecular structure include those obtained by substituting a part of the methyl group of polydimethylsiloxane with an appropriate amount of another functional group to reduce its crystallinity. Examples of the crosslinking method include a method using an addition reaction between a vinyl group and a hydrosilyl group, and a method of crosslinking by selecting a known functional group ratio and crosslinking conditions for obtaining a silicone gel. In addition, the manufacturing method of the sound deadening sheet | seat of this invention is not limited to those content.

  The silencing sheet has a cyclic siloxane content of 10-mer or less, preferably 2000 ppm or less, more preferably 1500 ppm or less. When the cyclic siloxane component of 10-mer or less exceeds 2000 ppm, the component may be transferred to an electronic device. As a method for reducing the siloxane component, a known method can be appropriately adopted. Examples thereof include a method for examining a raw material polymerization method, a heat treatment during molding, and a solvent extraction treatment for the raw material.

  The sound deadening sheet may impart adhesiveness to at least one side. With this configuration, it is possible to easily fix the sound generation source of the electronic device operation unit, for example, the contact portion between the button and the case, the contact portion between the switch and the case, or the like. The range of the adhesive force can be set as appropriate depending on the location where the operation unit is fixed, the purpose, and the like. For example, when it is intended to completely fix the sound deadening sheet without re-peeling, the lower limit of the adhesive strength is preferably 5 N / cm, more preferably 8 N / cm, and the upper limit is preferably 20 N / cm. . When the sheet is peeled again for the purpose of reuse or disposal, the range of adhesive strength is preferably 0.01 N / cm or more and 5 N / cm or less, more preferably 0.1 N / cm or more and 3 N. / Cm or less. In addition, the measuring method of adhesive force can be calculated | required by measuring 180 degree peeling adhesive force based on the adhesive tape and adhesive sheet test method of JISZ0237.

  The adhesiveness imparted to the sound deadening sheet may be adhesiveness derived from a silicone elastomer that is a sheet raw material, and an adhesive layer may be separately laminated. Among these, a method of imparting adhesiveness derived from a silicone elastomer is preferable from the viewpoint that a step of separately laminating the pressure-sensitive adhesive layer is not necessary and an increase in the thickness of the sheet can be suppressed. As a method for imparting silicone elastomer-derived tackiness to the sound deadening sheet, a known method can be appropriately employed. For example, the adhesiveness in the above-mentioned adhesive force range can be imparted by changing the type and molecular weight of polyorganosiloxane and the blending amount of various fillers to appropriately adjust the composition and the degree of crosslinking of the silicone elastomer. In the present invention, the silicone elastomer-derived adhesiveness means that the surface of the sheet having adhesiveness (adhesive strength) has the same composition as the silicone elastomer. Examples of the method for confirming the composition include a method for confirming by elemental analysis.

  As a method of separately laminating the pressure-sensitive adhesive layer on the sound deadening sheet, a known method can be appropriately adopted. For example, an adhesive layer can be provided by coating an adhesive on a silicone elastomer sheet. In addition, a pressure-sensitive adhesive layer is previously provided on a releasable base material such as a film and a sheet, and then the pressure-sensitive adhesive layer is transferred from the releasable base material onto the silicone elastomer sheet. An agent layer may be provided. Moreover, you may use the method of sticking the adhesive tape which has an adhesive layer on a silicone elastomer sheet from a viewpoint of productivity. As an adhesive tape, you may use what consists of a single layer of an adhesive layer, what consists of a multilayer of the adhesive layer which comprises the adhesive layer, a tape base material, and the sticking surface of a tape. A known plastic film can be used as the tape substrate. As an adhesive layer, the well-known silicone adhesive which is excellent in heat resistance can be mentioned, for example. A pressure-sensitive adhesive tape composed of a single layer of a silicone-based pressure-sensitive adhesive layer can be preferably applied. The pressure-sensitive adhesive layer can also be formed using an acrylic pressure-sensitive adhesive by performing primer treatment on a silicone elastomer sheet using a known method.

  As described above, the adhesiveness of the sound deadening sheet can be achieved by appropriately adjusting, for example, the composition of the silicone elastomer and the degree of cross-linking, but other adhesive surfaces may be embossed. The adhesive strength can be adjusted by adjusting the degree of embossing (surface roughness). As a method of embossing the surface of the film, a known method can be appropriately employed. For example, the film surface may be subjected to blasting or laser treatment after film formation, and the embossing roll pattern may be transferred or the embossing film pattern may be transferred during film formation.

  The muffler sheet can be used for an operation unit of an electronic device. Although it does not specifically limit as an electronic device, Preferably it is applied to the electronic device in which silence is requested | required. Examples of the operation unit of the electronic device include a pointing device of a personal computer, a keystroke unit of a mobile phone and a game device, a push button or a switch. Examples of the pointing device of the personal computer include a mouse, a keyboard, and a joystick. The muffler sheet is disposed at the operation sound generation source of the operation unit. For example, it is arranged at the contact sound generation location of the button and the case when the push button is input or when the push button returns. Thereby, the operation sound (contact sound) when using the operation part can be reduced or suppressed.

The operation when the muffler sheet according to the present embodiment is arranged, for example, on the push button body inside the mouse will be described.
As shown in FIGS. 1 and 2, the push button main body 11 includes a base 12, a lid portion 13, and a push button 14 provided on the surface of the lid portion 13. The push button body 11 is usually housed in a mouse body in a final product, and the push button 14 is operated (clicked) by an operation button provided on the surface of the mouse body.

  Inside the push button main body 11, as shown in FIGS. 3 and 4, a push button portion 15, a bent plate 16, and an energizing portion 17 are arranged on a base 12. The push button portion 15 is made of a metal plate, and one end portion is fixed on the base 12 and the other end portion constitutes an operating portion 15a that is movable in the vertical direction. The operating portion 15a is urged upward by a leaf spring 15b disposed in the lower portion thereof. The operating portion 15a is in contact with the contact portion 16a of the bent plate 16 fixed on the base 12 by the urging force of the leaf spring 15b when not operated. The push button portion 15 is in contact with the lower end portion of the push button 14 on the upper surface thereof, and the actuating portion 15a is moved downward against the upward biasing force by the downward force of the push button 14. The energization unit 17 is energized by contact with the operation unit 15a. The sound deadening sheet 18 is bonded and fixed to a contact portion with the contact portion 16a on the operating portion 15a. Thereby, the sound deadening sheet 18 can reduce or suppress the return sound after the operating part 15a and the contact part 16a are separated, that is, the contact sound between the operating part 15a and the contact part 16a.

According to the sound deadening sheet of the present embodiment, the following effects can be obtained.
(1) In the sound deadening sheet of this embodiment, a sheet made of a silicone elastomer having a loss coefficient (tan δ) in the range of 0.1 to 0.6 and a thickness in the range of 30 μm to 500 μm was used. Therefore, it is excellent in thinning and can improve the silencing effect without impairing the operability of the electronic device.

(2) Moreover, since the handleability at the time of manufacture of a film or attaching a film to an electronic device is not reduced by the said structure, the raise of manufacturing cost can be suppressed.
(3) Moreover, it can apply easily to the electronic device which tends to be reduced in size and thickness by the said structure.

  (4) In the sound deadening sheet of this embodiment, silicone elastomer is used. Therefore, it has heat resistance and cold resistance (for example, it can be used in an atmosphere of −40 to 200 ° C.), is excellent in electrical insulation, etc., and many types of electric and electronic devices can be used in various atmospheres. it can.

  (5) In the sound deadening sheet of the present embodiment, a sheet having a content of cyclic siloxane of 10-mer or less as a cyclic siloxane component of 10-mer or less is preferably 2000 ppm or less. Therefore, there is no possibility that the cyclic siloxane component of 10-mer or less in the sheet will be transferred to the electronic device.

  (6) In the sound deadening sheet of this embodiment, preferably at least one surface of the sheet has adhesiveness derived from a silicone elastomer that is a sheet raw material. Therefore, it is not necessary to apply or laminate a pressure-sensitive adhesive layer on the surface of the sound deadening sheet, and an adhesive surface can be formed. Therefore, the thin layer state of the sheet can be maintained and an increase in manufacturing cost can be suppressed.

  (7) In the sound deadening sheet of this embodiment, it is preferable that at least one surface of the sheet is embossed. Therefore, the presence or absence of adhesiveness, adhesive strength, etc. can be easily adjusted by the degree of embossing.

  (8) Since the sound deadening sheet of the present embodiment is thin and excellent in sound deadening, it is preferably applied to, for example, an operation button of a pointing device. Therefore, it is possible to effectively mute the contact sound when the operation button is input, for example, the return sound, without affecting the operability of the operation button.

In addition, you may change the said embodiment as follows.
In the present invention, the term “sheet” includes “film”, and the term “film” includes “sheet”.

  -In the said embodiment, you may mix | blend additives, such as an antibacterial agent, antioxidant, and a light stabilizer, in a silicone elastomer in the range which does not impair the effect of this invention.

Hereinafter, although an Example and a comparative example demonstrate in more detail, this invention is not limited to these.
Example 1
A silicone elastomer sheet having a thickness of 200 μm is cross-linked using a millable type silicone raw material X-30-1193-U (manufactured by Shin-Etsu Chemical Co., Ltd.) and sandwiched with a flat PET (polyethylene terephthalate) sheet as a release film. Got. This elastomer sheet was produced while adjusting the degree of crosslinking so that the loss factor was 0.2 to 0.4. Then, after peeling off the PET sheet on one side, heat treatment was performed at 130 ° C. for 1 hour. A part of the low molecular siloxane component is evaporated and removed by the heat treatment. The content of the cyclic siloxane component in the sheet of 10-mer or less was measured according to the method described below. As a result, the content of the cyclic siloxane component of 10-mer or less was 1843 ppm and 2000 ppm or less. The loss coefficient (tan δ) measured at a frequency of 10 Hz and a temperature of 20 ° C. was 0.32 by dynamic viscoelasticity measurement of the sheet.

(Example 2)
A silicone elastomer sheet was produced in the same manner as in Example 1 except that the thickness of the silicone elastomer sheet was set to 30 μm. The loss coefficient (tan δ) of this sheet and the content of cyclic siloxane component of 10-mer or less were both the same as those in Example 1.

(Example 3)
A silicone elastomer sheet was produced in the same manner as in Example 1 except that the thickness of the silicone elastomer sheet was set to 500 μm. The loss coefficient (tan δ) of this sheet and the content of cyclic siloxane component of 10-mer or less were both the same as those in Example 1.

Example 4
A silicone elastomer sheet having a thickness of 200 μm was obtained in the same manner as in Example 1 except that millable type KE-571U (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the silicone raw material. The loss coefficient (tan δ) measured at a frequency of 10 Hz and a temperature of 20 ° C. by dynamic viscoelasticity measurement of this sheet is 0.13, and the content of the cyclic siloxane component below the 10-mer is 1141 ppm, 2000 ppm It was the following.

(Example 5)
As a silicone raw material, a gel material β gel (manufactured by Taika Co., Ltd.) containing silicone as a main raw material was used, which was cut into a 200 μm thick sheet. In addition, the loss coefficient (tan δ) measured at a frequency of 10 Hz and a temperature of 20 ° C. was 0.56 by the dynamic viscoelasticity measurement of this sheet, and the content of the cyclic siloxane component below the 10-mer was 1015 ppm.

(Example 6)
A silicone elastomer sheet was produced in the same manner as in Example 1 except that the heat treatment was not performed on the silicone elastomer sheet. The loss coefficient (tan δ) of this sheet was the same as in Example 1. The content of the cyclic siloxane component of 10 sheets or less in this sheet was 15000 ppm.

(Comparative Example 1)
A silicone elastomer sheet having a thickness of 200 μm was obtained in the same manner as in Example 1 except that millable type silicone raw material KE-9510U (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as the silicone raw material. Further, the loss coefficient (tan δ) measured at a frequency of 10 Hz and a temperature of 20 ° C. was 0.034 by dynamic viscoelasticity measurement of the sheet. The content of the cyclic siloxane component of 10 sheets or less in this sheet was 815 ppm.

(Comparative Example 2)
A silicone elastomer sheet was produced in the same manner as in Example 1 except that the thickness of the silicone elastomer sheet was set to 600 μm. The loss coefficient (tan δ) of this sheet and the content of cyclic siloxane component of 10-mer or less were both the same as those in Example 1.

(Comparative Example 3)
A non-woven fabric (manufactured by Japan Vilene) having a thickness of 250 μm was used.
(Comparative Example 4)
A non-woven fabric (manufactured by Japan Vilene) having a thickness of 500 μm was used.

  The silicone elastomer sheet or non-woven fabric produced in the examples and comparative examples was used as a sound deadening sheet. For each sound-absorbing sheet, the content of cyclic siloquine components of 10-mer or less and the sound level were measured as follows.

(Measurement method of sound level and sound absorption (silence))
First, the silicone elastomer sheet or non-woven fabric of each example was fixed to the operating part 15a side between the operating part 15a and the contact part 16a (contact part) constituting the operation button of the mouse shown in FIG. The sound-absorbing sheet made of silicone elastomer was fixed to the operating portion 15a using the adhesiveness derived from the silicone elastomer without requiring an adhesive or a pressure-sensitive adhesive. The sound deadening sheet made of a non-woven fabric was not fixed to the operating part 15a, but was sandwiched between the operating part 15a and the contact part 16a.

  Next, the lid portion 13 having the push button 14 on the surface was attached on the base 12 to constitute the push button main body 11. A microphone part of a sound level meter (manufactured by Rion: NL-04) is placed at a distance of about 30 mm from the push button 14 on the surface of the push button body 11, and the push button 14 is clicked so that the operating part 15 a and the contact part 16 a The sound level (dB) of the touching sound was measured. Under the same environment, clicking was performed about 50 times in 10 seconds, and the average at that time was calculated. In addition, the average value of the sound level when the silencer sheet was not used was 22.9 dB. Further, after the measurement, the lid portion 13 was opened, and the silicone elastomer sheet and the nonwoven fabric between the operating portion 15a and the contact portion 16a were confirmed. As a result, some positional deviation was confirmed in the nonwoven fabric that was not fixed to the operating portion 15a.

(Sheet thickness measurement)
The silicone elastomer sheet or nonwoven fabric of each example was fixed so as to be flat, and measured with a constant pressure thickness measuring instrument (Mitutoyo Corporation: Electric Micrometer).

  As an evaluation of sound absorption (silence), when the sound level (22.9 dB) when the sound deadening sheet is not used is 100%, less than 45% is good (excellent), 45% or more and less than 60% Was evaluated as Δ, and 60% or more was evaluated as ×.

(Keystroke (operability))
The touch when the push button 14 of the push button main body 11 was clicked with a finger was evaluated as keystroke (operability) according to the following criteria. Good when there is a click feeling and there is no problem with practicality: ◯, when the click feeling is slightly inferior but there is no problem with practicality: △, when there is no click feeling and there is a problem with practicality: x evaluated.

(Handability (handling))
About the muffling sheet of each example, the handleability was evaluated according to the following criteria. Good when there is no stickiness and strong adhesive strength and no problem with practicality: ○, when stickiness or adhesive strength is slightly strong but there is no problem with practicality: △, stickiness or adhesive strength is strong and there is a problem with practicality The case was evaluated as bad: x.

(Measurement of content of cyclic siloxane component of 10-mer or less)
Measurement method: 1.00 g of the sample was immersed in 10 mL of acetone at 25 ° C. for 16 hours, and the immersion liquid was analyzed by gas chromatography.

Equipment: Capillary gas chromatograph Perkin Elmer AutoSystemXL
Column: DB-5 column Temperature: The temperature was increased from 70 ° C. to 320 ° C. at a heating rate of 3 ° C./min.

Sample injection temperature: 300 ° C
Carrier gas: He (1 mL / min)
Detector: FID
Injection volume: 2 μL
(Migration of cyclic siloxane component (oil) of 10-mer or less)
The transferability of the cyclic siloxane component of 10-mer or less is an evaluation of whether or not the cyclic siloxane component of 10-mer or less is transferred to the working part 15a or the contact part 16a, and the working part 15a after normal use for one month. Or the contact part 16a was observed visually (or loupe), and evaluation was performed according to the following reference | standard. Good when there is no migration of the siloxane component on the surface of the working part 15a and the contact part 16a: ○, the surface of the working part 15a or the contact part 16a has a slight gloss derived from the siloxane component, but the surface with alcohol (ethanol) Slightly worse when wiping loses gloss: Δ, the surface of the actuating portion 15a or contact portion 16a has a clear gloss derived from the siloxane component, but the gloss is lost when the surface is wiped with alcohol (ethanol) : Evaluated as x. In the table, it is expressed as “migration of low molecular weight components”.

表１に示されるように、実施例１は全ての評価が良好であった。

As shown in Table 1, all evaluations of Example 1 were good.

  Since the sheet thickness of Example 2 is thinner than that of Example 1, the sound absorption evaluation is slightly inferior to that of Example 1, but there is no problem in practicality. In Example 2, it is more difficult to peel the film from the flat PET than in Example 1, and in this case, the handleability is slightly inferior to that of Example 1 because it is slightly clinging to the hand, but there is no problem in practicality.

  In Example 3, since the sheet thickness is 500 μm, which is thicker than Example 1, the feel when the push button 14 is clicked is slightly inferior to that of Example 1, but it can be pressed with the same force as Example 1, and is practical. There was no problem with sex.

In Example 4, since the value of tan δ is around 0.1, the sound absorption is slightly inferior to Example 1, but there was no problem in practicality.
Example 5 has the best sound absorption among the examples. The sheet of Example 5 is softer and more sticky than Example 1, and is slightly inferior in handleability, but there is no problem in practicality.

  In Example 6, since the content of the cyclic siloxane component of 10 mer or less was 15000 ppm, the migration property of the cyclic siloxane component (oil) of 10 mer or less was inferior to other examples.

Since Comparative Example 1 had a loss coefficient of 0.1 or less, the sound absorption was evaluated to be worse than that of Example 1.
In Comparative Example 2, since the thickness of the sheet exceeded 500 μm, the click feeling was worse than in Example 1, and it was necessary to press with a stronger force than in Example 3, and it was evaluated that there was no practicality.

In Comparative Examples 3 and 4, the silencing effect was poor with respect to each Example. Moreover, the thickness of Comparative Example 4 was 500 μm, and the keystroke performance was slightly inferior to Example 1.
Next, technical ideas that can be grasped from the above-described embodiment and other examples will be described below together with their effects.

  (A) For an electronic device operation unit comprising a step of crosslinking a silicone raw material sandwiched between two release films to obtain a silicone elastomer sheet, and then a step of performing heat treatment after removing the release film on one side. A method for producing a muffler sheet. Therefore, according to the invention described in (a), the sound deadening sheet is excellent in heat resistance, and can improve the sound deadening effect without impairing the operability of the electronic device, and further the conductivity (contactability) in the operation part. Can be easily obtained.

  DESCRIPTION OF SYMBOLS 11 ... Push button main body, 12 ... Base, 13 ... Cover part, 14 ... Push button, 15 ... Push button part, 15a ... Actuating part, 15b ... Leaf spring, 16 ... Bending plate, 16a ... Contact part, 17 ... Current supply Part, 18 ... silencer sheet.

Claims (5)

  A sheet made of a silicone elastomer, which has a loss coefficient (tan δ) measured by dynamic viscoelasticity measurement at a frequency of 10 Hz and a temperature of 20 ° C. in a range of 0.1 to 0.6 and a thickness of 30 μm. A muffler sheet for an electronic device operation section, characterized by being in a range of ˜500 μm.   The silencing sheet for an electronic device operation unit according to claim 1, wherein the sheet has a cyclic siloxane content of 10 ppm or less of 2000 ppm or less.   At least one surface of the said sheet | seat has the adhesiveness derived from the said silicone elastomer, The silencer sheet for electronic device operation parts of Claim 1 or Claim 2 characterized by the above-mentioned.   The silencing sheet for an electronic device operating unit according to any one of claims 1 to 3, wherein at least one surface of the sheet is embossed.   The mute sheet for an electronic device operation unit according to any one of claims 1 to 4, wherein the operation unit is an operation button of a pointing device.

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