JP2585728C

JP2585728C -

Info

Publication number: JP2585728C
Authority: JP
Original assignee: 株式会社マックサイエンス
Publication date: 1999-01-20

Description

【発明の詳細な説明】［産業上の利用分野］本発明は、試料と標準試料とを同時に昇・降温させてこれらの温度差を測定す
ることにより前記試料の熱的変化を観測する熱分析装置に関する。［従来の技術］試料と標準試料とを同時に昇・降温させてこれらの温度差を測定することによ
り前記試料の熱的変化を観測する熱分析装置として、従来から、示差熱分析装置
（ＤＴＡ；Differential Thermal Analysis）、あるいは、示差走査熱量計(ＤＳ
Ｃ；Differential Scanning Calorimeter)が知られている。これらは、いずれも
、試料の転移温度や転移熱等の試料の熱的性質を定性的あるいは定量的に観測する極めて有効な手段として広く用いられている。ところで、上述のような熱分析装置においては、試料に熱的変化がないときは
、これらの間に温度差が生じないことが前提である。つまり、いま、このような
装置で全く熱的変化のない試料（つまり、標準試料と同じ熱的性質を有する試料
）について測定し、その結果を、縦軸に試料と標準試料との温度差をとり、横軸
に試料の温度（または、時間）をとったグラフに曲線として示した場合、装置が
完全であれば、この曲線は横軸に平行な直線となるはずである。そして、通常、この直線をベースラインといい、このベースラインからのずれ
を読み取って試料の熱的性質を解析する。したがって、このベースラインの安定性がこの種の装置の性能を左右する一つ
の重要な要素となっているこのベースラインの安定性を図るため、従来より種々の試みがなされているが
、その一つに、熱伝導性に富む円形の板材料で構成された感熱板を用い、この感
熱板の表面であって該感熱板の円の中心を中心として互いにほぼ点対象となる位
置にそれぞれ試料と標準試料とを載置し、該感熱板の外周部を加熱もしくは冷却
を行う昇・降温手段に熱的に結合した方式の装置が知られている（例えば、中川
英昭ほか、熱測定7，11，1980参照）。［発明が解決しようとする課題］ところが、近年にいたり、装置の高感度化の要請が益々高まるに従い、上述の
感熱板を用いた方式であってもその要請に十分応えることができなくなってきた
。すなわち、上記感熱板を用いた方式の装置によって従来の最高感度以上の極め
て高い感度（超高感度）で測定すると、試料の昇・降温とともに、ベースライン
に不規則な階段状の乱れが生じ、これがため、上述のような超高感度の測定に支
障をきたすということが判明した。本発明の目的は、上述の問題点を除去した熱分析装置を提供することにある。［課題を解決するための手段］本発明者等は、上記問題点を鋭意究明し、種々の試行錯誤を繰り返した結果、前記感熱板に切り込みをいれるという、極めて簡単な方法によって、前記ベース
ラインの乱れをほぼ完全に除去できるという事実をみいだした。本発明は、この
事実に基づいてなされたもので、以下の構成を有する。試料と標準試料とを同時に昇・降温させてこれらの温度差を測定することによ
り前記試料の熱的変化を観測する熱分析装置であって、前記試料と標準試料とを
載置してこれらをほぼ同一の熱的条件下におく感熱板と、該感熱板に熱的に結合
されて前記試料及び標準試料を昇・降温させる昇・降温手段と、前記試料と標準
試料との温度差を測定する温度差測定手段とを備え、前記感熱板は、略円板状をなした熱伝導性の板状材料で構成され、該円板の中
心を中心として互いにほぼ点対称となる部位に前記試料と標準試料とをそれぞれ
載置することができるように上面が略平坦な凸部に形成されて試料載置部及び標
準試料載置部とされ、前記円板の中心を中心とする円形の領域であって前記試料
載置部及び標準試料載置部が含まれる円形の領域が全体的に平坦な円形の陥没部
とされ、該円形陥没部の外側の部分が平坦な円環領域とされ、前記円形陥没部か
ら円環領域に移行する部分が斜めに形成されてテーパ状部とされ、前記円環領域
の外周端部から前記円形陥没にかけて前記円板の中心に向かう切込みが複数設け
られ、かつ、前記円環領域が前記昇・降温手段に結合されているものであること
を特徴とする熱分析装置。［作用］前記構成によれば、感熱板に切り込みを設けたことによって、切り込みを設け
る前には生じていた超高感度でのベースラインの乱れがほぼ完全になくなること
が確認されている。本発明者等の考察によれば、このような作用が得られる理由は、以下の通りで
あると推察される。すなわち、前記感熱板と昇・降温手段とを熱的に結合するために、これらは機
械的に結合されるが、前記感熱板に切り込みがない場合は、昇・降温の際に、両
者の熱膨張その他の熱的挙動に差異が生じ、これがため、いずれか一方もしくは
両者に歪みを生じさせ、その結果、前記試料と標準試料との間の熱的バランスを
崩し、ベースラインの乱れを生じさせるものと思われる。これに対し、前記感熱板に切り込みを設けた場合には、該切り込みが前記感熱
板と昇・降温手段との熱的挙動の差異にもとづく歪みを吸収し、前記試料と標準
試料との熱的バランスを崩すのを未然に防止する作用をするものと考えられる。［実施例］第１図は本発明の一実施例にかかる熱分析装置を示す図である。第１図において、符号１は昇・降温手段、符号２は前記昇・降温手段１に熱的
に結合された感熱板である。前記昇・降温手段１は、略円筒状をなした熱伝導性の材料からなる均熱ブロッ
ク１１と、この均熱ブロック１１の外周に設けられ、該均熱ブロック１１を加熱
もしくは冷却する加熱・冷却手段１２とから構成されている。前記感熱板２は第２図にその平面図を示したように、円板状をなした熱伝導性
の材料で構成され、該感熱板２の円の中心Ｏを中心として互いにほぼ点対象とな
る部位が円形状に突出され、それぞれ試料載置部２ａと標準試料載置部２ｂとが
形成されている。また、前記感熱板２の半径方向外周よりの円環状の領域には、
外周から中心に向かって半径の１／２以下の長さに延長されたスリット状の切り
込み３，…，３が形成されている。さらに、前記感熱板２はその外周部を残した
中央部が一方の側、すなわち、図中下方側に断面略台形状となるように突出され
、テーパ状部２ｃが形成されている。そして、前記感熱板２は、その外周部が前記均熱ブロック１１の上部に形成さ
れた大径部１１ａと小径部１１ｂとの間の段差部１１ｃに接するようにして前記
大径部１１ａに挿入され、次に、固定リング１３が前記大径部１１ａに圧入され
、該固定リング１３と前記段差部１１ｃとで前記感熱板２の外周部が把持される
ようにして支持されている。すなわち、前記感熱板２は、前記均熱ブロック１１
を介して前記加熱・冷却手段１２に熱的に結合されている。また、前記感熱板２の試料載置部２ａ及び標準試料載置部２ｂの裏面のほぼ中
心部にはそれぞれ温度検出手段としての熱電対４及び５が接続されている。これら熱電対４，５は、前記均熱ブロック１１の小径部１１ｂに形成された遮
熱壁１１ｄに設けられた貫通孔１１ｅを通して外部に導かれ、制御回路部６に接続されている。すなわち、これら熱電対４，５は、前記試料載置部２ａ及び標準試料載置部２
ｂ上にそれぞれ載置された試料７及び標準試料８の温度を検出するもので、これ
ら試料７及び標準試料８の温度に対応した起電力を生じこれを前記制御回路部６
に送出する。前記制御回路部６は、演算処理回路や温度コントロール回路等を内蔵するもの
で、前記熱電対４の起電力を検出して試料７の温度に対応する信号に変換すると
ともに、前記熱電対４，５の起電力の差をとってこの差に対応する信号に変換し
、これらを記録・表示手段９に送出して試料の温度及び試料７と標準試料８との
温度差の表示をさせ、さらに、前記加熱・冷却手段１２を制御してその温度をコ
ントロールするものである。なお、前記熱電対４，５と制御回路部６とは、試料
と標準試料との温度差を測定する温度差測定装置を構成する。また、前記均熱ブ
ロック１１の大径部１１ａの上部には蓋１１ｆを被せることができるようになっ
ている。上述の装置によって熱分析を行うときは、前記感熱板２の試料載置部２ａ及び
標準試料載置部２ｂ上にそれぞれ試料７及び標準試料８を載置し、前記制御回路
部６をにより前記加熱・冷却手段１２をコントロールし、前記試料７及び標準試
料８の温度を昇・降温させ、その際、前記記録・表示手段９によって記録もしく
は表示された温度差を読み取ることにより行う。なお、この場合、この温度差か
ら転移熱等の値を定量的に求めるときは、該温度差を、装置定数等を含む一定の
数式にいれて演算処理を行う等の必要がある。上述の実施例によれば、超高感度測定においてもベースラインに不規則な階段
状のずれは全くみられず、良好な測定が可能であった。すなわち、ほぼ同一の条件下において従来例と前記実施例との比較を行った結
果、１mcal/sフルスケール（記録紙の目盛り幅で135mmフルスケール）の感度で
の測定で、従来例では、ベースラインに約7〜66μcal／ｓ（記録紙の目盛り幅で
1〜9mm）の階段状のずれがみられる場合があった、上記実施例ではベースライン
のずれを全く認めることができなかった。第３図は、本発明の他の実施例の一部を示す図である。この実施例では、前記一実施例における感熱板２のかわりに感熱板２０を用い
たもので、その他の構成は前記一実施例と同じである。前記感熱板２０は、その半径方向外周よりの円環状の領域に、外周から中心に
向かって半径の１／２以下の長さに延長された４個のスリット状の切り込み３１
，…，３１と、該スリット３１，…，３１の先端部を通る円上に形成された４個
の円弧状の切り込み３２，…，３２とが形成されている。なお、前記感熱板２０は、該感熱板２０の円の中心Ｏを中心として互いにほぼ
点対象となる部位が円形状に突出され、それぞれ試料載置部２０ａと標準試料載
置部２０ｂとがそれぞれ形成されている。この実施例によっても、前記一実施例と同様の作用・効果が得られることが確
認されている。なお、本発明は、感熱板に形成される切り込みの位置、形状もしくは数が前記
各実施例に示されたものに限定されるものでなく、前記各実施例の切り込みに類
似する位置、形状もしくは数の範囲で通常考えられる種々の変形例であってもよ
いことが確認されている。［発明の効果］以上詳述したように、本発明は、感熱板に切り込みをいれるという、極めて簡
単な構成によって、超高感度の測定においてもベースラインの乱れのない熱分析
装置を得たものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermal analysis in which a sample and a standard sample are simultaneously heated and cooled and a temperature difference between the samples is measured to observe a thermal change of the sample. Related to the device. 2. Description of the Related Art Conventionally, a differential thermal analyzer (DTA) has been used as a thermal analyzer for observing a thermal change of a sample and a standard sample by simultaneously raising and lowering the temperature and measuring a temperature difference between the samples and the standard sample. Differential Thermal Analysis) or Differential Scanning Calorimeter (DS)
C; Differential Scanning Calorimeter) is known. All of these are widely used as extremely effective means for qualitatively or quantitatively observing the thermal properties of a sample such as the transition temperature and the heat of transition of the sample. By the way, in the above-mentioned thermal analyzer, when there is no thermal change in the sample, it is assumed that there is no temperature difference between them. In other words, a sample having no thermal change (that is, a sample having the same thermal properties as a standard sample) is measured with such an apparatus, and the result is plotted on the vertical axis, where the temperature difference between the sample and the standard sample is plotted. In the case where the temperature (or time) of the sample is plotted as a curve on the horizontal axis, if the apparatus is perfect, this curve should be a straight line parallel to the horizontal axis. This straight line is usually called a baseline, and the deviation from this baseline is read to analyze the thermal properties of the sample. Therefore, the stability of this baseline is one of the important factors influencing the performance of this type of apparatus. Various attempts have been made to improve the stability of this baseline. First, a heat-sensitive plate made of a circular plate material having a high thermal conductivity is used, and the sample and the heat-sensitive plate are respectively positioned on the surface of the heat-sensitive plate and at positions substantially symmetric with respect to the center of the circle of the heat-sensitive plate. There is known an apparatus of a system in which a standard sample is placed and thermally connected to heating / cooling means for heating or cooling the outer peripheral portion of the heat sensitive plate (for example, Hideaki Nakagawa et al., Heat Measurement 7, 11 , 1980). [Problems to be Solved by the Invention] However, with the recent increase in the demand for higher sensitivity of the apparatus, even the above-described method using the heat-sensitive plate cannot sufficiently meet the demand. . In other words, when measurement is performed with an extremely high sensitivity (ultrahigh sensitivity) higher than the conventional maximum sensitivity by using the above-described apparatus using the heat sensitive plate, irregular step-like disturbance occurs in the baseline along with the rise and fall of the sample, This has been found to hinder the above-described ultra-high sensitivity measurement. An object of the present invention is to provide a thermal analyzer that eliminates the above-mentioned problems. [Means for Solving the Problems] The present inventors have intensively investigated the above-mentioned problems, and as a result of repeating various trials and errors, as a result, a cut is made in the heat-sensitive plate. Has been found to be almost completely eliminated. The present invention has been made based on this fact, and has the following configuration. A thermal analyzer for observing a thermal change of the sample by simultaneously raising and lowering the temperature of the sample and the standard sample and measuring a temperature difference between the samples and the standard sample. A heat-sensitive plate under substantially the same thermal conditions; heat-up / cool-down means thermally coupled to the heat-sensitive plate to raise and lower the temperature of the sample and the standard sample; and measure a temperature difference between the sample and the standard sample. The heat-sensitive plate is made of a substantially disc-shaped thermally conductive plate-like material, and the sample is located at a point that is substantially point-symmetric with respect to the center of the disc. And a standard sample, the upper surface of which is formed in a substantially flat convex portion so as to be a sample mounting portion and a standard sample mounting portion, and a circular region centered on the center of the disk. Wherein a circular area including the sample mounting part and the standard sample mounting part is The whole is a flat circular depression, the outer part of the circular depression is a flat annular area, and the part that transitions from the circular depression to the annular area is formed diagonally to form a tapered part. is a, the circle cut towards the center of the disc over the circular recessed from the outer peripheral edge of the ring region is provided with a plurality, and in which said annular region is coupled to said temperature-lowering means A thermal analyzer characterized by the following. [Operation] According to the above configuration, it has been confirmed that by providing the cuts in the heat-sensitive plate, the disturbance of the baseline at the ultra-high sensitivity that occurred before the cuts were formed is almost completely eliminated. According to the considerations of the present inventors, the reason why such an effect is obtained is presumed to be as follows. That is, in order to thermally connect the heat-sensitive plate and the temperature raising / lowering means, they are mechanically connected. Differences in expansion or other thermal behavior can result, causing distortion in one or both, resulting in an unbalanced thermal balance between the sample and the reference sample, resulting in a baseline disturbance. It seems to be. On the other hand, when a cut is provided in the heat-sensitive plate, the cut absorbs a distortion based on a difference in thermal behavior between the heat-sensitive plate and the temperature raising / lowering means, and causes a thermal difference between the sample and the standard sample. It is considered that it acts to prevent the balance from being lost. Embodiment FIG. 1 is a view showing a thermal analyzer according to one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a heating / cooling unit, and reference numeral 2 denotes a heat-sensitive plate thermally coupled to the heating / cooling unit 1. The temperature raising / lowering means 1 includes a heat equalizing block 11 made of a substantially cylindrical heat conductive material, and a heating / cooling unit provided on an outer periphery of the heat equalizing block 11 for heating or cooling the heat equalizing block 11. And cooling means 12. As shown in a plan view of FIG. 2, the heat-sensitive plate 2 is made of a disc-shaped heat conductive material, and is substantially point-symmetric with respect to the center O of the circle of the heat-sensitive plate 2. Are projected in a circular shape, and a sample mounting part 2a and a standard sample mounting part 2b are formed respectively. Further, in an annular region from the outer periphery in the radial direction of the heat sensitive plate 2,
Slit-shaped cuts 3,..., 3 extending from the outer periphery toward the center to a length equal to or less than の of the radius are formed. Further, the heat-sensitive plate 2 has a central portion excluding an outer peripheral portion thereof protruded to one side, that is, a lower side in the drawing so as to have a substantially trapezoidal cross section, and is formed with a tapered portion 2c. The heat-sensitive plate 2 is inserted into the large-diameter portion 11a such that an outer peripheral portion thereof is in contact with a step portion 11c formed between the large-diameter portion 11a and the small-diameter portion 11b formed on the heat equalizing block 11. Then, the fixing ring 13 is press-fitted into the large-diameter portion 11a, and the fixing ring 13 and the step portion 11c are supported such that the outer peripheral portion of the heat-sensitive plate 2 is gripped. That is, the heat-sensitive plate 2 is connected to the heat equalizing block 11.
Is thermally coupled to the heating / cooling means 12 via the Further, thermocouples 4 and 5 as temperature detecting means are connected to substantially the central portions of the back surfaces of the sample mounting portion 2a and the standard sample mounting portion 2b of the heat sensitive plate 2, respectively. These thermocouples 4 and 5 are guided to the outside through through holes 11 e provided in a heat shield wall 11 d formed in the small diameter portion 11 b of the heat equalizing block 11, and are connected to the control circuit unit 6. That is, these thermocouples 4 and 5 are connected to the sample mounting portion 2a and the standard sample mounting portion 2 respectively.
b for detecting the temperatures of the sample 7 and the standard sample 8 placed on the control circuit unit 6 respectively.
To send to. The control circuit unit 6 includes an arithmetic processing circuit, a temperature control circuit, and the like. The control circuit unit 6 detects an electromotive force of the thermocouple 4 and converts the electromotive force into a signal corresponding to the temperature of the sample 7. 5 is converted into a signal corresponding to the difference, and these signals are sent to recording / display means 9 to display the temperature of the sample and the temperature difference between the sample 7 and the standard sample 8. The heating and cooling means 12 is controlled to control its temperature. The thermocouples 4, 5 and the control circuit 6 constitute a temperature difference measuring device for measuring a temperature difference between a sample and a standard sample. A lid 11f can be placed over the large diameter portion 11a of the heat equalizing block 11. When performing the thermal analysis by the above-described device, the sample 7 and the standard sample 8 are respectively placed on the sample placing portion 2a and the standard sample placing portion 2b of the heat sensitive plate 2, and the control circuit portion 6 The heating / cooling means 12 is controlled to raise and lower the temperatures of the sample 7 and the standard sample 8, and at this time, the temperature difference recorded or displayed by the recording / display means 9 is read. In this case, in order to quantitatively determine the value of the transition heat or the like from the temperature difference, it is necessary to perform an arithmetic process on the temperature difference in a certain mathematical expression including a device constant or the like. According to the above-described example, even in the ultra-high sensitivity measurement, no irregular step-like deviation was found in the baseline, and good measurement was possible. That is, as a result of comparison between the conventional example and the above example under almost the same conditions, the measurement was performed at a sensitivity of 1 mcal / s full scale (135 mm full scale in the scale width of recording paper). About 7 ~ 66μcal / s on line
In some cases, a stepwise deviation of 1 to 9 mm) was observed. In the above example, no deviation of the baseline could be recognized. FIG. 3 is a diagram showing a part of another embodiment of the present invention. In this embodiment, a heat-sensitive plate 20 is used in place of the heat-sensitive plate 2 in the above-described embodiment, and other configurations are the same as those in the above-described embodiment. The heat-sensitive plate 20 has four slit-like cuts 31 extending from the outer periphery toward the center to a length of not more than 半径 of the radius in an annular region from the outer periphery in the radial direction.
, ..., and four arc-shaped cuts 32, ..., 32 formed on a circle passing through the tip of the slits 31, ..., 31. The heat sensitive plate 20 has circularly projecting portions that are substantially pointed with respect to the center O of the circle of the heat sensitive plate 20, and the sample mounting part 20a and the standard sample mounting part 20b are respectively formed. Is formed. According to this embodiment, it is confirmed that the same operation and effect as those of the first embodiment can be obtained. In addition, the present invention is not limited to the position, shape or number of cuts formed in the heat-sensitive plate to those shown in each of the above-described embodiments, but may be similar to the positions, shapes or cuts in the above-described embodiments. It has been confirmed that various modifications that are usually considered in the range of numbers may be used. [Effects of the Invention] As described in detail above, the present invention provides a thermal analyzer that has a very simple configuration in which a cut is made in a heat-sensitive plate and has no disturbance of the baseline even in an ultra-sensitive measurement. It is.

【図面の簡単な説明】第１図は本発明の一実施例にかかる熱分析装置を示す図、第２図は第１図に示
される感熱板２の正面図、第３図は本発明の他の実施例における部分構成を示す
図である。１…昇・降温手段、２，２０…感熱板、３，３１，３２…切り込み、４，５…
温度差測定手段の一部を構成する熱電対、６…温度差測定手段の一部を構成する
制御回路部、７…試料、８…標準試料。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a thermal analyzer according to one embodiment of the present invention, FIG. 2 is a front view of a heat-sensitive plate 2 shown in FIG. 1, and FIG. FIG. 14 is a diagram illustrating a partial configuration in another embodiment. 1 ... means for raising and lowering temperature, 2, 20 ... heat-sensitive plate, 3, 31, 32 ... cut, 4, 5 ...
A thermocouple forming a part of the temperature difference measuring means; a control circuit section forming a part of the temperature difference measuring means; a sample; and a standard sample.

Claims

Claims: 1. A thermal analyzer for simultaneously raising and lowering the temperature of a sample and a standard sample and measuring a temperature difference between the samples to observe a thermal change of the sample. A heat-sensitive plate to be placed and placed under substantially the same thermal conditions; heat-up / cool-down means thermally coupled to the heat-sensitive plate to raise and lower the sample and the standard sample; and the sample and the standard sample A temperature difference measuring means for measuring a temperature difference between the heat-sensitive plate and the heat-sensitive plate, the heat-sensitive plate being made of a substantially disc-shaped thermally conductive plate-like material, and substantially point-symmetric with respect to the center of the disc. The sample and the standard sample are protruded in a circular shape so that the sample and the standard sample can be respectively mounted on a portion to be a sample mounting portion and a standard sample mounting portion, and have a circular shape centered on the center of the disk. A circular area including the sample mounting part and the standard sample mounting part The region is formed so as to protrude downward and the cross section becomes substantially inverted trapezoidal shape, a portion outside the circular region is an annular region, and a portion transitioning from the circular region to the annular region is formed obliquely. is a tapered portion, cut toward the center from the outer periphery of the disc over the circular area of the annular region is provided with a plurality,
In addition, the thermal analysis device is characterized in that the annular region is connected to the temperature raising / lowering means.