JP2015182911A - Method for regulating the compressibility of expanded graphite sheet, and expanded graphite sheet - Google Patents
Method for regulating the compressibility of expanded graphite sheet, and expanded graphite sheet Download PDFInfo
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本発明は、膨張黒鉛シートの圧縮率を変化させ、所望の値に調整する膨張黒鉛シートの圧縮率調整方法、及び該膨張黒鉛シートの圧縮率調整方法により圧縮率が調整された膨張黒鉛シートに関するものである。 The present invention relates to a method for adjusting the compressibility of an expanded graphite sheet that changes the compressibility of the expanded graphite sheet to a desired value, and an expanded graphite sheet whose compressibility is adjusted by the method for adjusting the compressibility of the expanded graphite sheet. Is.
膨張黒鉛シートの圧縮率は密度に依存し、図３に例示するように、密度が高くなるほど膨張黒鉛シートの圧縮率は低下する。図３は、厚さが０．８ｍｍと同一で、密度がそれぞれ０．５ｇ／ｃｍ３、０．８ｇ／ｃｍ３、１．０ｇ／ｃｍ３、１．２ｇ／ｃｍ３と相違する膨張黒鉛シートを、異なる面圧で一定時間加圧した場合の圧縮率を示したものである。このように、膨張黒鉛シートの圧縮率が密度に依存することに基づき、従来、膨張黒鉛シートの用途に応じて必要とされる圧縮率は、密度によって調整されていた（例えば、特許文献１、特許文献２参照）。 The compressibility of the expanded graphite sheet depends on the density, and as illustrated in FIG. 3, the compressibility of the expanded graphite sheet decreases as the density increases. FIG. 3 shows an expanded graphite sheet having the same thickness as 0.8 mm and different densities from 0.5 g / cm 3 , 0.8 g / cm 3 , 1.0 g / cm 3 , and 1.2 g / cm 3 , respectively. Shows the compression ratio when pressure is applied at different surface pressures for a certain period of time. Thus, based on the fact that the compressibility of the expanded graphite sheet depends on the density, conventionally, the compressibility required depending on the application of the expanded graphite sheet has been adjusted by the density (for example, Patent Document 1, Patent Document 2).
具体的には、特許文献１の技術は、膨張黒鉛シートをるつぼ用保護シートに用いるものであり、衝撃吸収性のために所望される圧縮率とするために、密度の異なる複数種類の膨張黒鉛シートの中から、熱膨張率やガス透過率など他の物性を考慮した上で、ある密度の膨張黒鉛シートを選択している。ここで、密度が相違する膨張黒鉛シートは、一般的に、層間化合物とした黒鉛を急激に加熱して層間の物質をガス化し、層間隔を押し広げて膨張黒鉛とした後、これを圧延してシート化する際の圧力を異ならせることによって製造することができる。従って、かかる方法で所望の圧縮率を得るためには、膨張黒鉛シートの製造段階において、圧延条件を変化させて密度を変化させなければならなかった。また、膨張黒鉛シートの市販品では、予め密度の値が段階的に設定されている。そのため、膨張黒鉛シートの市販品を使用する場合は、任意の値の圧縮率を有する膨張黒鉛シートは得られないという問題があった。 Specifically, the technique of Patent Document 1 uses an expanded graphite sheet as a protective sheet for a crucible, and in order to obtain a desired compressibility for shock absorption, a plurality of types of expanded graphite having different densities are used. In consideration of other physical properties such as thermal expansion coefficient and gas permeability, an expanded graphite sheet having a certain density is selected from the sheets. Here, in general, expanded graphite sheets having different densities are obtained by rapidly heating graphite as an intercalation compound to gasify the material between the layers, expanding the layer spacing to obtain expanded graphite, and then rolling the graphite. The sheet can be manufactured by varying the pressure when forming into a sheet. Therefore, in order to obtain a desired compression ratio by such a method, it has been necessary to change the density by changing the rolling conditions in the production stage of the expanded graphite sheet. Moreover, in the commercial product of an expanded graphite sheet, the value of the density is set in steps. Therefore, when using a commercial product of an expanded graphite sheet, there is a problem that an expanded graphite sheet having an arbitrary value of compression cannot be obtained.
一方、特許文献２の技術は、膨張黒鉛シートをガスケットに用いるものであり、一般的に市販されている密度０．８ｇ／ｃｍ３〜１．３ｇ／ｃｍ３の膨張黒鉛シートは、ガスケットとしての用途には圧縮率が高過ぎるとして、膨張黒鉛シートを加圧成形することにより、密度を高めている。そのため、密度が１．０ｇ／ｃｍ３であった膨張黒鉛シートの密度を１．６５ｇ／ｃｍ３とするために、もともと厚さが３．０５ｍｍであった膨張黒鉛シートの厚さが１．８５ｍｍになり、密度が１．０ｇ／ｃｍ３であった膨張黒鉛シートの密度を１．４１ｇ／ｃｍ３とするために、もともと厚さが２．０ｍｍであった膨張黒鉛シートの厚さが１．７２ｍｍになるなど、圧縮率の調整のために膨張黒鉛シートの厚さが大きく変化してしまうという問題があった。 On the other hand, the technique of Patent Document 2 was used such that the expanded graphite sheet gasket, expanded graphite sheet of density are generally commercially available 0.8g / cm 3 ~1.3g / cm 3 is as a gasket The density is increased by press-molding the expanded graphite sheet, assuming that the compression ratio is too high for the application. Therefore, the density of the expanded graphite sheet density was 1.0 g / cm 3 in order to 1.65 g / cm 3, originally thickness is the thickness of the expanded graphite sheet which was a 3.05 mm 1.85 mm In order to set the density of the expanded graphite sheet whose density was 1.0 g / cm 3 to 1.41 g / cm 3 , the thickness of the expanded graphite sheet originally having a thickness of 2.0 mm was 1. There was a problem that the thickness of the expanded graphite sheet greatly changed due to adjustment of the compression ratio, such as 72 mm.
そこで、本発明は、上記の実情に鑑み、膨張黒鉛シートの圧縮率を、密度によらず調整することができる膨張黒鉛シートの圧縮率調整方法、及び該膨張黒鉛シートの圧縮率調整方法により圧縮率が調整された膨張黒鉛シートの提供を、課題とするものである。 Therefore, in view of the above circumstances, the present invention is a compression method for an expanded graphite sheet that can adjust the compression rate of the expanded graphite sheet regardless of the density, and the compression rate adjustment method for the expanded graphite sheet. An object of the present invention is to provide an expanded graphite sheet with a controlled rate.
上記の課題を解決するため、本発明にかかる膨張黒鉛シートの圧縮率調整方法は、「膨張黒鉛シートを非酸化性雰囲気で加熱処理し、加熱温度及び加熱時間の少なくとも一方によって圧縮率を変化させる」ものである。 In order to solve the above problems, the method for adjusting the compressibility of an expanded graphite sheet according to the present invention is as follows: “Expanding graphite sheet is heat-treated in a non-oxidizing atmosphere, and the compressibility is changed by at least one of heating temperature and heating time. "
「膨張黒鉛シート」は、硫酸、硝酸等で処理して層間化合物とした黒鉛を、急激に加熱して層間の物質をガス化し層間隔を押し広げ、その後圧延することにより得られる黒鉛シートであり、厚さ０．１ｍｍ〜３．０ｍｍのものを好適に使用することができる。 An “expanded graphite sheet” is a graphite sheet obtained by treating graphite with sulfuric acid, nitric acid, etc. to form an intercalation compound, rapidly heating it to gasify the material between the layers, expanding the layer spacing, and then rolling. Those having a thickness of 0.1 mm to 3.0 mm can be preferably used.
「非酸化性雰囲気」は、アルゴンガス等の不活性ガス、窒素ガス、これらの混合ガス雰囲気、或いは、真空雰囲気とすることができる。 The “non-oxidizing atmosphere” can be an inert gas such as argon gas, a nitrogen gas, a mixed gas atmosphere thereof, or a vacuum atmosphere.
本発明者は、詳細は後述するように、膨張黒鉛シートを非酸化性雰囲気で加熱するのみの簡易な方法により、膨張黒鉛シートの圧縮率を変化させられることを見出し、本発明に至ったものである。従って、本発明によれば、ある密度に設定された市販の膨張黒鉛シートを用いて、圧縮率の異なる複数種類の熱膨張黒鉛シートを得ることができる。また、非酸化性雰囲気下での加熱温度及び加熱時間の少なくとも一方を制御することにより、所望する任意の値の圧縮率を有する膨張黒鉛シートを得ることができる。 As will be described in detail later, the present inventor has found that the compressibility of the expanded graphite sheet can be changed by a simple method of simply heating the expanded graphite sheet in a non-oxidizing atmosphere. It is. Therefore, according to the present invention, a plurality of types of thermally expanded graphite sheets having different compressibility can be obtained using a commercially available expanded graphite sheet set to a certain density. Further, by controlling at least one of the heating temperature and the heating time in a non-oxidizing atmosphere, an expanded graphite sheet having a desired compressibility can be obtained.
加えて、加圧成形により密度を変化させることによって圧縮率を変化させていた従来技術とは異なり、厚さをほとんど変化させることなく、膨張黒鉛シートの圧縮率を変化させることができる。 In addition, unlike the prior art in which the compression ratio is changed by changing the density by pressure molding, the compression ratio of the expanded graphite sheet can be changed with almost no change in thickness.
次に、本発明にかかる膨張黒鉛シートは、「密度が１．０ｇ／ｃｍ３で、面圧が１２ＭＰａ〜１６ＭＰａのときの厚さ方向の圧縮率が１１％〜２１％である」ものである。 Next, the expanded graphite sheet according to the present invention is “the compression ratio in the thickness direction is 11% to 21% when the density is 1.0 g / cm 3 and the surface pressure is 12 MPa to 16 MPa”. .
本構成の膨張黒鉛シートは、上記の膨張黒鉛シートの圧縮率調整方法を使用し、加熱温度を１２５０±１００℃、加熱時間を４時間〜８時間として非酸化性雰囲気で加熱処理することによって、厚さ方向の圧縮率が１１％〜２１％に調整された密度が１．０ｇ／ｃｍ３の膨張黒鉛シートであり、詳細は後述するように、加熱処理を施していない同一密度の膨張黒鉛シートに比べて、圧縮率がかなり小さいものである。 The expanded graphite sheet of the present configuration uses the above-described method for adjusting the compressibility of the expanded graphite sheet, and is heated in a non-oxidizing atmosphere at a heating temperature of 1250 ± 100 ° C. and a heating time of 4 hours to 8 hours, An expanded graphite sheet having a density adjusted to a compressibility of 11% to 21% in the thickness direction and having a density of 1.0 g / cm 3 , as will be described in detail later. Compared to the above, the compression ratio is considerably small.
本発明にかかる膨張黒鉛シートは、上記構成に替えて、「密度が１．０ｇ／ｃｍ３で、面圧が１２ＭＰａ〜１６ＭＰａのときの厚さ方向の圧縮率が１１％〜２３％であり、且つ、硫黄含有率が２５０ｐｐｍ〜６４０ｐｐｍである」ものであってもよい。 The expanded graphite sheet according to the present invention has a density of 1.0 g / cm 3 and a compressibility in the thickness direction of 11% to 23% when the surface pressure is 12 MPa to 16 MPa, instead of the above configuration. And the sulfur content is 250 ppm to 640 ppm. "
本構成の膨張黒鉛シートは、上記の膨張黒鉛シートの圧縮率調整方法を使用し、加熱温度を９００℃〜１３５０℃、加熱時間を４時間として非酸化性雰囲気で加熱処理することによって、厚さ方向の圧縮率が１１％〜２３％に調整された密度が１．０ｇ／ｃｍ３の膨張黒鉛シートであり、詳細は後述するように、加熱処理を施していない同一密度の膨張黒鉛シートに比べて、圧縮率がかなり小さいと共に、硫黄含有率が大幅に低いものである。 The expanded graphite sheet of this configuration is obtained by heat treatment in a non-oxidizing atmosphere using the above-described method for adjusting the compressibility of the expanded graphite sheet, with a heating temperature of 900 ° C. to 1350 ° C. and a heating time of 4 hours. This is an expanded graphite sheet having a density adjusted to 11% to 23% in the direction and having a density of 1.0 g / cm 3 , as will be described in detail later, compared with an expanded graphite sheet having the same density that has not been heat-treated. Thus, the compression rate is considerably small and the sulfur content is significantly low.
以上のように、本発明の効果として、膨張黒鉛シートの圧縮率を、密度によらず調整することができる膨張黒鉛シートの圧縮率調整方法、及び、該膨張黒鉛シートの圧縮率調整方法により圧縮率が調整された膨張黒鉛シートを提供することができる。 As described above, as an effect of the present invention, the compression ratio of the expanded graphite sheet can be adjusted regardless of the density, and the compression ratio of the expanded graphite sheet can be adjusted regardless of the density. An expanded graphite sheet with an adjusted rate can be provided.
以下、本発明の一実施形態である膨張黒鉛シートの圧縮率調整方法（以下、単に「圧縮率調整方法」と称する）、及び、本実施形態の圧縮率調整方法により圧縮率が調整された膨張黒鉛シートについて説明する。本実施形態の圧縮率調整方法は、膨張黒鉛シートを非酸化性雰囲気で加熱処理し、加熱温度及び加熱時間の少なくとも一方によって圧縮率を変化させるものである。 Hereinafter, the compression ratio adjustment method (hereinafter, simply referred to as “compression ratio adjustment method”) of the expanded graphite sheet which is an embodiment of the present invention, and the expansion whose compression ratio is adjusted by the compression ratio adjustment method of the present embodiment The graphite sheet will be described. In the compression rate adjusting method of the present embodiment, the expanded graphite sheet is heat-treated in a non-oxidizing atmosphere, and the compression rate is changed by at least one of the heating temperature and the heating time.
より具体的に説明すると、加熱処理は、膨張黒鉛シートの複数枚を積層して、上下に配した黒鉛板で挟み込み、結束バンドで積層状態を保持した上で、黒鉛粒等の詰め粉に埋設した状態で行うことができる。加熱温度は、後述のように、９００℃〜１３５０℃とすると、過度に加熱することなく圧縮率を効果的に変化させることができ、望ましい。また、加熱時間は、２時間〜８時間を一単位とすると、加熱処理の回数によって圧縮率を微調整することができ、望ましい。 More specifically, the heat treatment is performed by laminating a plurality of expanded graphite sheets, sandwiching them between upper and lower graphite plates, holding the laminated state with a binding band, and then embedding in a packing powder such as graphite particles Can be done in the state. As will be described later, when the heating temperature is 900 ° C. to 1350 ° C., the compression rate can be effectively changed without excessive heating, which is desirable. Further, when the heating time is 2 hours to 8 hours as one unit, the compression ratio can be finely adjusted by the number of heat treatments, which is desirable.
膨張黒鉛シート（５３０ｍｍ×９００ｍｍ×厚さ１ｍｍ、密度１．０ｇ／ｃｍ３、ＴＹＫ製）の６０枚を積層し、厚さ１５ｍｍの二枚の黒鉛板で挟み、アルゴンガス雰囲気で加熱処理することにより、加熱温度の異なる三種類の膨張黒鉛シートＳ１〜Ｓ３を得た。Ｓ１の加熱温度は３００±５０℃とし、Ｓ２の加熱温度は９５０±５０℃とし、Ｓ３の加熱温度は１２５０±１００℃とした。膨張黒鉛シートは４００℃以上の温度で酸化するため、Ｓ２及びＳ３については、加熱処理は詰め粉に埋設した状態で行った。加熱時間は、Ｓ２及びＳ３については何れも４時間とし、Ｓ１については４８時間とした。加熱処理後の膨張黒鉛シートＳ１〜Ｓ３について、それぞれ次の方法で圧縮率を測定した。 60 sheets of expanded graphite sheets (530 mm × 900 mm × thickness 1 mm, density 1.0 g / cm 3 , manufactured by TYK) are laminated, sandwiched between two graphite plates with a thickness of 15 mm, and heat-treated in an argon gas atmosphere. Thus, three types of expanded graphite sheets S1 to S3 having different heating temperatures were obtained. The heating temperature of S1 was 300 ± 50 ° C., the heating temperature of S2 was 950 ± 50 ° C., and the heating temperature of S3 was 1250 ± 100 ° C. Since the expanded graphite sheet is oxidized at a temperature of 400 ° C. or higher, the heat treatment for S2 and S3 was performed in a state where it was embedded in the filling powder. The heating time was 4 hours for S2 and S3, and 48 hours for S1. About the expanded graphite sheet S1-S3 after heat processing, the compression rate was measured with the following method, respectively.
＜圧縮率の測定＞
膨張黒鉛シートの上面を、円柱状の金属型の円形の端面で押圧する。所定の面圧に達したら、その圧力を１０秒間保持する。１０秒の経過後に金属型を離隔させ、膨張黒鉛シートの厚さを測定する。金属型で押圧することによる厚さの変化量（厚さの減少量）の、金属型で押圧する前の膨張黒鉛シートの厚さに対する割合（百分率）を、圧縮率として算出した。
<Measurement of compression ratio>
The upper surface of the expanded graphite sheet is pressed with a circular end surface of a cylindrical metal mold. When a predetermined surface pressure is reached, the pressure is maintained for 10 seconds. After 10 seconds, the metal mold is separated, and the thickness of the expanded graphite sheet is measured. The ratio (percentage) of the amount of thickness change (thickness reduction) due to pressing with the metal mold to the thickness of the expanded graphite sheet before pressing with the metal mold was calculated as the compression ratio.
加熱時間の異なる膨張黒鉛シートＳ１〜Ｓ３について、異なる面圧のときの圧縮率の測定結果を表１に示すと共に、面圧に対する圧縮率の関係のグラフを図１に示す。表１及び図１では、加熱処理を行っていない膨張黒鉛シートＳ０について測定した面圧に対する圧縮率の関係を、対比のために示している。 For expanded graphite sheets S1 to S3 having different heating times, the measurement results of the compressibility at different surface pressures are shown in Table 1, and a graph of the relationship of the compressibility to the surface pressure is shown in FIG. In Table 1 and FIG. 1, the relationship of the compressibility with respect to the surface pressure measured about the expanded graphite sheet S0 which is not heat-processed is shown for the comparison.
表１及び図１から明らかなように、加熱処理によって膨張黒鉛シートの圧縮率を変化させることができ、加熱温度が高いほど圧縮率を小さくすることができる。加熱温度が３００±５０℃の試料Ｓ１では、未処理の膨張黒鉛シートＳ０と対比した圧縮率の変化は、さほど大きなものではなかった。そのため、このような低温での加熱処理は、圧縮率を微調整したい場合に適していると考えられた。 As is apparent from Table 1 and FIG. 1, the compressibility of the expanded graphite sheet can be changed by heat treatment, and the compressibility can be reduced as the heating temperature is higher. In the sample S1 having a heating temperature of 300 ± 50 ° C., the change in the compressibility compared with the untreated expanded graphite sheet S0 was not so large. For this reason, it was considered that such low-temperature heat treatment is suitable for fine adjustment of the compression rate.
一方、加熱温度が９５０±５０℃の試料Ｓ２、及び、１２５０±１００℃の試料Ｓ３は、未処理の試料Ｓ０と対比して、圧縮率は大きく低下していた。従って、加熱時間を９００℃〜１３５０℃とすれば、過度に加熱することなく効率的に圧縮率を変化させることができると考えられた。 On the other hand, the compression rate of the sample S2 having a heating temperature of 950 ± 50 ° C. and the sample S3 having a heating temperature of 1250 ± 100 ° C. was greatly reduced as compared with the untreated sample S0. Therefore, it was considered that if the heating time was 900 ° C. to 1350 ° C., the compressibility could be changed efficiently without excessive heating.
そして、種々の加熱温度について、予め、図１に例示されるような圧縮率−面圧曲線を得ておくことにより、膨張黒鉛シートが使用される状況下で受ける面圧に応じて、所望される任意の値の圧縮率を有する膨張黒鉛シートを得るために、行うべき加熱処理の加熱温度条件を知ることができる。 For various heating temperatures, by obtaining a compression rate-surface pressure curve as illustrated in FIG. 1 in advance, it is desired depending on the surface pressure received under the situation where the expanded graphite sheet is used. In order to obtain an expanded graphite sheet having a compressibility of an arbitrary value, it is possible to know the heating temperature condition of the heat treatment to be performed.
圧縮率を変化させた膨張黒鉛シートＳ１〜Ｓ３を得るための加熱処理の前後での膨張黒鉛シートの厚さの変化を表２に、密度の変化を表３に示す。表２及び表３に示すように、圧縮率を変化させるための加熱処理によって、膨張黒鉛シートの厚さも密度も、ほとんど変化していないことが分かる。 Table 2 shows the change in the thickness of the expanded graphite sheet before and after the heat treatment for obtaining the expanded graphite sheets S1 to S3 having different compression ratios, and Table 3 shows the change in the density. As shown in Tables 2 and 3, it can be seen that the thickness and density of the expanded graphite sheet are hardly changed by the heat treatment for changing the compressibility.
また、圧縮率を変化させた膨張黒鉛シートＳ１〜Ｓ３、及び未処理の膨張黒鉛シートＳ０について硫黄含有率を測定したところ、加熱処理によって硫黄含有率を低下させることができることが分かった。具体的には、次の表４に示すように、９５０±５０℃で加熱処理した試料Ｓ２では、硫黄含有率は未処理の試料Ｓ０の約２／３に低下しており、１２５０±１００℃で加熱処理した試料Ｓ３では、硫黄含有率は未処理の試料Ｓ０の約１／４に低下していた。一般的に市販されている膨張黒鉛シートには、硫黄含有率の低いグレードも存在するが、精製の工程を経たものであるため高価である。本実施形態では、膨張黒鉛シートを加熱するのみの簡易な操作で、圧縮率を調整することができると共に、精製されていない通常のグレードである市販の膨張黒鉛シートから、硫黄含有率の低い膨張黒鉛シートを得ることができる。 Moreover, when the sulfur content rate was measured about the expanded graphite sheet S1-S3 and the untreated expanded graphite sheet S0 which changed the compression rate, it turned out that a sulfur content rate can be reduced by heat processing. Specifically, as shown in the following Table 4, in the sample S2 heat-treated at 950 ± 50 ° C., the sulfur content is reduced to about 2/3 of the untreated sample S0, and 1250 ± 100 ° C. In the sample S3 heat-treated in step S1, the sulfur content was reduced to about ¼ that of the untreated sample S0. In general, a commercially available expanded graphite sheet includes a grade having a low sulfur content, but is expensive because it has undergone a purification process. In the present embodiment, the compression rate can be adjusted by a simple operation of merely heating the expanded graphite sheet, and the expansion of the sulfur content is low from a commercially available expanded graphite sheet that is a normal grade that has not been purified. A graphite sheet can be obtained.
次に、加熱処理における加熱温度条件を同一とし、加熱時間（加熱処理の回数）を変化させた膨張黒鉛シートＳ１１、Ｓ１２について、圧縮率を検討した結果を示す。ここでは、膨張黒鉛シート（５３０ｍｍ×９００ｍｍ×厚さ０．８ｍｍ、密度１．０ｇ／ｃｍ３、ＴＹＫ製）の６０枚を積層し、厚さ１５ｍｍの二枚の黒鉛板で挟み、アルゴンガス雰囲気で、１２５０±１００℃の温度で加熱処理した。加熱処理は４時間を一単位とし、膨張黒鉛シートＳ１１は一単位の加熱処理を１回（加熱時間計４時間）行うことにより得、膨張黒鉛シートＳ１２は一単位の加熱処理を２回（加熱時間計８時間）行うことにより得た。得られた膨張黒鉛シートＳ１１、Ｓ１２について、上記と同様の方法で圧縮率を測定した。その結果を表５及び図２に示す。表５及び図２では、加熱処理を行っていない膨張黒鉛シートＳ１０について測定した結果を、対比のために示している。 Next, the result of examining the compressibility of the expanded graphite sheets S11 and S12 in which the heating temperature conditions in the heat treatment are the same and the heating time (the number of heat treatments) is changed is shown. Here, 60 sheets of expanded graphite sheet (530 mm × 900 mm × thickness 0.8 mm, density 1.0 g / cm 3 , manufactured by TYK) are laminated, sandwiched between two graphite plates having a thickness of 15 mm, and an argon gas atmosphere And heat treatment at a temperature of 1250 ± 100 ° C. Heat treatment is performed for 4 hours as one unit, the expanded graphite sheet S11 is obtained by performing one unit of heat treatment once (a total heating time of 4 hours), and the expanded graphite sheet S12 is subjected to one unit of heat treatment twice (heating) For a total of 8 hours). About the obtained expanded graphite sheet S11, S12, the compressibility was measured by the method similar to the above. The results are shown in Table 5 and FIG. In Table 5 and FIG. 2, the result measured about the expanded graphite sheet S10 which has not performed heat processing is shown for the comparison.
表５及び図２から明らかなように、加熱温度が同一の場合、加熱時間が長いほど（加熱処理の回数が多いほど）、圧縮率を小さくすることができる。そして、種々の加熱時間（加熱処理の回数）について、予め、図２に例示されるような圧縮率−面圧曲線を得ておくことにより、膨張黒鉛シートが使用される状況下で受ける面圧に応じて、所望される任意の値の圧縮率を有する膨張黒鉛シートを得るために、行うべき加熱処理の加熱時間条件を知ることができる。加えて、このような加熱時間に対する圧縮率−面圧曲線を、種々の加熱温度について得ておくことにより、所望される圧縮率を有する膨張黒鉛シートを得るために行うべき加熱処理について、加熱温度条件と加熱時間条件とを、同時に定めることができる。 As can be seen from Table 5 and FIG. 2, when the heating temperature is the same, the longer the heating time (the more the number of heat treatments), the smaller the compression ratio. Then, for various heating times (number of times of heat treatment), by obtaining in advance a compression rate-surface pressure curve as exemplified in FIG. 2, the surface pressure received under the situation where the expanded graphite sheet is used. Accordingly, it is possible to know the heating time condition of the heat treatment to be performed in order to obtain an expanded graphite sheet having a desired compression ratio. In addition, by obtaining such a compression rate-surface pressure curve with respect to the heating time for various heating temperatures, the heating temperature to be performed for obtaining an expanded graphite sheet having a desired compression rate is as follows. Conditions and heating time conditions can be determined simultaneously.
以上のように、本実施形態の圧縮率調整方法によれば、膨張黒鉛シートを加熱するのみの簡易な方法で、密度をほとんど変化させることなく、圧縮率を変化させることができる。そして、加熱処理における加熱温度条件及び加熱時間条件の少なくとも一方の制御により、膨張黒鉛シートの圧縮率を所望の値に調整することができる。また、膨張黒鉛シートを加熱することで圧縮率を調整できるため、密度が段階的に設定された市販の膨張黒鉛シートを使用して、圧縮率が任意の値に調整された膨張黒鉛シートを得ることができる。 As described above, according to the compression ratio adjusting method of the present embodiment, the compression ratio can be changed with almost no change in density by a simple method of merely heating the expanded graphite sheet. The compressibility of the expanded graphite sheet can be adjusted to a desired value by controlling at least one of the heating temperature condition and the heating time condition in the heat treatment. In addition, since the compression ratio can be adjusted by heating the expanded graphite sheet, a commercially available expanded graphite sheet having a stepwise density setting is used to obtain an expanded graphite sheet with the compression ratio adjusted to an arbitrary value. be able to.
加えて、膨張黒鉛シートを加熱することで圧縮率を調整できるため、加圧成形によって高密度化することにより圧縮率を変化させていた従来技術と異なり、膨張黒鉛シートの厚さをほとんど変化させることなく、膨張黒鉛シートの圧縮率を変化させることができる。 In addition, since the compression ratio can be adjusted by heating the expanded graphite sheet, the thickness of the expanded graphite sheet is almost changed, unlike the conventional technology that has changed the compression ratio by increasing the density by pressure molding. Without changing, the compressibility of the expanded graphite sheet can be changed.
そして、試料Ｓ３、試料Ｓ１１、及び試料Ｓ１２についての検討結果から分かるように、密度１．０ｇ／ｃｍ３の膨張黒鉛シートを加熱温度１２５０℃±１００℃、加熱時間４〜８時間で加熱処理することにより、面圧１２ＭＰａ〜１６ＭＰａのときの厚さ方向の圧縮率が１１％〜２１％という、加熱処理していない同一密度の膨張黒鉛シートに比べて圧縮率がかなり小さい膨張黒鉛シートを得ることができる。このように圧縮率が調整された膨張黒鉛シートは、圧縮率が重要な特性であるシール材（パッキン材）やクッション材として有用である。 Then, as can be seen from the examination results for sample S3, sample S11, and sample S12, the expanded graphite sheet having a density of 1.0 g / cm 3 is heat-treated at a heating temperature of 1250 ° C. ± 100 ° C. and a heating time of 4 to 8 hours. Thus, an expanded graphite sheet having a compressibility in the thickness direction when the surface pressure is 12 MPa to 16 MPa is 11% to 21% and which is considerably smaller than the expanded graphite sheet of the same density that is not heat-treated. Can do. Thus, the expanded graphite sheet in which the compression rate is adjusted is useful as a sealing material (packing material) or a cushion material in which the compression rate is an important characteristic.
また、試料Ｓ２及び試料Ｓ３の結果から分かるように、密度１．０ｇ／ｃｍ３の膨張黒鉛シートを加熱温度９００℃〜１３５０℃、加熱時間４時間で加熱処理することにより、面圧１２ＭＰａ〜１６ＭＰａのときの厚さ方向の圧縮率が１１％〜２３％であり、且つ、硫黄含有率が２５０ｐｐｍ〜６４０ｐｐｍという、加熱処理していない同一密度の膨張黒鉛シートに比べて、圧縮率及び硫黄含有率がともに小さい膨張黒鉛シートを得ることができる。 Further, as can be seen from the results of the samples S2 and S3, the surface pressure of 12 MPa to 16 MPa is obtained by heat-treating the expanded graphite sheet having a density of 1.0 g / cm 3 at a heating temperature of 900 ° C. to 1350 ° C. and a heating time of 4 hours. The compression ratio and the sulfur content are 11% to 23% in the thickness direction and the sulfur content is 250 ppm to 640 ppm, compared to the expanded graphite sheet of the same density that is not heat-treated. In both cases, an expanded graphite sheet having a small size can be obtained.
なお、試料Ｓ０〜Ｓ３、及び、試料Ｓ１０〜Ｓ１２について、ロックウェル硬度を測定した結果（平均値）を、表６及び表７に示す。ここで、硬度の測定は、それぞれの試料について厚さが４ｍｍとなるように、膨張黒鉛シートを積層して行った。また、測定には電動ツインロックウェル硬さ試験機（Ａｋａｓｈｉ製、ＡＴＫ−Ｆ２０００）を使用し、次の条件で行った。
スケール：Ｒ
圧子：直径１／２インチ（１２．７ｍｍ）の鋼球
基準荷重：１０ｋｇｆ（９８．０７Ｎ）
試験荷重：６０ｋｇｆ（５８８．４Ｎ）
Tables 6 and 7 show the results (average values) of measuring Rockwell hardness for samples S0 to S3 and samples S10 to S12. Here, the hardness was measured by laminating expanded graphite sheets so that each sample had a thickness of 4 mm. In addition, an electric twin Rockwell hardness tester (manufactured by Akashi, ATK-F2000) was used for the measurement, and the measurement was performed under the following conditions.
Scale: R
Indenter: Steel ball with a diameter of 1/2 inch (12.7 mm) Standard load: 10 kgf (98.07 N)
Test load: 60kgf (588.4N)
膨張黒鉛シートは比較的柔らかい材料であるため、表６及び表７に示すように、測定結果は負の値になっているが、加熱処理によって硬度が高くなっており、上記のように加熱処理によって圧縮率が低下している結果と整合している。 Since the expanded graphite sheet is a relatively soft material, as shown in Table 6 and Table 7, the measurement result is a negative value, but the hardness is increased by the heat treatment, and the heat treatment is performed as described above. This is consistent with the result of the decrease in compression ratio.
以上、本発明について好適な実施形態を挙げて説明したが、本発明は上記の実施形態に限定されるものではなく、本発明の要旨を逸脱しない範囲において、種々の改良及び設計の変更が可能である。 Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above-described embodiments, and various improvements and design changes can be made without departing from the scope of the present invention. It is.
例えば、上記の実施形態では、加熱温度として３００±５０℃、９５０±５０℃、及び１２５０±１００℃を例示し、加熱時間の単位を４時間とした場合を例示したが、加熱温度及び加熱時間は何れも例示したものに限定されるものではない。 For example, in the above embodiment, 300 ± 50 ° C., 950 ± 50 ° C., and 1250 ± 100 ° C. are exemplified as the heating temperature, and the case where the unit of the heating time is 4 hours is exemplified. However, the heating temperature and the heating time are exemplified. Are not limited to those illustrated.
Claims (3)
ことを特徴とする膨張黒鉛シートの圧縮率調整方法。 A method for adjusting a compressibility of an expanded graphite sheet, wherein the expanded graphite sheet is heated in a non-oxidizing atmosphere, and the compressibility is changed by at least one of a heating temperature and a heating time.
ことを特徴とする膨張黒鉛シート。 An expanded graphite sheet having a density of 1.0 g / cm 3 and a compressibility in the thickness direction of 11% to 21% when the surface pressure is 12 MPa to 16 MPa.
ことを特徴とする膨張黒鉛シート。 The density is 1.0 g / cm 3 , and the compressibility in the thickness direction when the surface pressure is 12 MPa to 16 MPa is 11% to 23%, and the sulfur content is 250 ppm to 640 ppm. Expanded graphite sheet.
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|---|---|---|---|---|
| JPS60118618A (en) * | 1983-11-25 | 1985-06-26 | Nippon Pillar Packing Co Ltd | Method for decreasing residual sulfur contained in expanded graphite |
| JP2000100453A (en) * | 1998-07-24 | 2000-04-07 | Hitachi Chem Co Ltd | Expansive graphite grain, its manufacture, fuel cell, separator for fuel cell and its manufacture |
| JP2008019137A (en) * | 2006-07-14 | 2008-01-31 | Toyo Tanso Kk | Crucible protective sheet |
| JP2011046794A (en) * | 2009-08-25 | 2011-03-10 | Japan Matekkusu Kk | Gasket made of expanded graphite |
| JP2013519987A (en) * | 2010-02-16 | 2013-05-30 | エスゲーエル カーボン ソシエタス ヨーロピア | Radiator and electrical energy storage |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS60118618A (en) * | 1983-11-25 | 1985-06-26 | Nippon Pillar Packing Co Ltd | Method for decreasing residual sulfur contained in expanded graphite |
| JP2000100453A (en) * | 1998-07-24 | 2000-04-07 | Hitachi Chem Co Ltd | Expansive graphite grain, its manufacture, fuel cell, separator for fuel cell and its manufacture |
| JP2008019137A (en) * | 2006-07-14 | 2008-01-31 | Toyo Tanso Kk | Crucible protective sheet |
| JP2011046794A (en) * | 2009-08-25 | 2011-03-10 | Japan Matekkusu Kk | Gasket made of expanded graphite |
| JP2013519987A (en) * | 2010-02-16 | 2013-05-30 | エスゲーエル カーボン ソシエタス ヨーロピア | Radiator and electrical energy storage |
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