JP2854661B2 - Method for measuring molecular weight of polymer materials - Google Patents
Method for measuring molecular weight of polymer materialsInfo
- Publication number
- JP2854661B2 JP2854661B2 JP7835990A JP7835990A JP2854661B2 JP 2854661 B2 JP2854661 B2 JP 2854661B2 JP 7835990 A JP7835990 A JP 7835990A JP 7835990 A JP7835990 A JP 7835990A JP 2854661 B2 JP2854661 B2 JP 2854661B2
- Authority
- JP
- Japan
- Prior art keywords
- molecular weight
- solvent
- polymer material
- weight
- hfip
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000002861 polymer material Substances 0.000 title claims description 21
- 238000000034 method Methods 0.000 title claims description 19
- 239000002904 solvent Substances 0.000 claims description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 239000012046 mixed solvent Substances 0.000 claims description 10
- 230000005526 G1 to G0 transition Effects 0.000 claims description 9
- 229920000642 polymer Polymers 0.000 claims description 6
- BYEAHWXPCBROCE-UHFFFAOYSA-N 1,1,1,3,3,3-hexafluoropropan-2-ol Chemical compound FC(F)(F)C(O)C(F)(F)F BYEAHWXPCBROCE-UHFFFAOYSA-N 0.000 claims description 3
- 238000005259 measurement Methods 0.000 description 14
- 238000005227 gel permeation chromatography Methods 0.000 description 10
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000008213 purified water Substances 0.000 description 4
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 239000003643 water by type Substances 0.000 description 2
- 229920002292 Nylon 6 Polymers 0.000 description 1
- 229920002302 Nylon 6,6 Polymers 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000012442 inert solvent Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Treatment Of Liquids With Adsorbents In General (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は高分子材料の分子量測定方法に関する。The present invention relates to a method for measuring the molecular weight of a polymer material.
一般に、エンジニアリングプラスチックなどに用いら
れる高分子材料は、同一の構造単位をもつ重合度の異な
る分子、すなわち分子量の異なる分子の集団から構成さ
れているため、分子量分布を有している。最近では、こ
のような分子量分布が高分子材料の物性、すなわち耐熱
変形性、耐溶剤性、寸法安定性、電気絶縁性などと相関
関係があることが判かり、これを重要視してきている。Generally, a polymer material used for engineering plastics or the like is composed of molecules having the same structural unit but different degrees of polymerization, that is, a group of molecules having different molecular weights, and thus has a molecular weight distribution. Recently, it has been found that such a molecular weight distribution has a correlation with the physical properties of a polymer material, that is, thermal deformation resistance, solvent resistance, dimensional stability, electrical insulation, and the like, and this has been regarded as important.
上記した分子量分布およびこれから求められる平均分
子量を含めて称する高分子材料の分子量は、諸種の方法
で測定し得るが、その一方法としてゲルパーミエーショ
ンクロマトグラフィー法（以下、GPC法と略称する）が
ある。このGPC法は、不活性重合体からなるカラムを所
定の溶媒でゲル状に膨潤させて定常相とし、この定常相
に前記溶媒に溶解した高分子材料を移動相として浸透さ
せ、この移動相の時間当りの流出量と測定濃度とから前
記高分子材料の分子量分布を求める方法である。このGP
C法によると、試料の高分子材料は、定常相のゲルの網
目中に浸透し、その浸透の深さの違いによって分別が行
なわれることとなり、分子量の大きいものほど網目中に
浸透できずに早く溶離流出する。The molecular weight of the polymer material, including the molecular weight distribution described above and the average molecular weight obtained therefrom, can be measured by various methods. One of the methods is gel permeation chromatography (hereinafter abbreviated as GPC). is there. In the GPC method, a column made of an inert polymer is swollen in a gel state with a predetermined solvent to form a stationary phase, and a polymer material dissolved in the solvent is permeated into the stationary phase as a mobile phase. In this method, the molecular weight distribution of the polymer material is determined from the amount of outflow per unit time and the measured concentration. This GP
According to the C method, the polymer material of the sample permeates into the network of the gel in the stationary phase, and is separated by the difference in the depth of permeation. Elutes and elutes quickly.
第４図に示すように、GPC法による実際の測定装置で
は、溶媒タンク１からポンプ２で送給され、試料注入口
３から測定対象の高分子材料を注入された溶液は、試料
カラム４のゲル中を浸透流下して分別され、示差屈折計
５に入り、比較カラム６からの溶媒を対照として濃度が
測定された後、サイホン７によって所定量（たとえば5m
l）流れる毎に信号が出るようセットされた流量検出部
８を通る。この信号の数を数えて流量を分子量に対応さ
せ、分子量分布曲線を記録計にプロットさせている。As shown in FIG. 4, in an actual measuring device by the GPC method, a solution which is fed from a solvent tank 1 by a pump 2 and in which a polymer material to be measured is injected from a sample inlet 3 is supplied to a sample column 4. The fraction is separated by permeation flow through the gel, enters the differential refractometer 5, and the concentration is measured using the solvent from the comparison column 6 as a control.
l) The flow passes through the flow detector 8 set so that a signal is output each time it flows. The number of these signals is counted and the flow rate is made to correspond to the molecular weight, and the molecular weight distribution curve is plotted on a recorder.
いま、分子量の測定条件を分子鎖のレベルでみると、
溶液中での高分子鎖の広がりは、溶媒と測定温度に依存
するという事実があり、高分子の排除体積による影響、
すなわち摂動状態となるθ温度下での分子量測定が望ま
しいといえる。このことをストックマイヤー−フィック
スマンの式についてみると、 〔η〕＝ＫθＭ1/2＋CM …… （式中〔η〕は極限粘度、Ｋθは定数、定数Ｃ＝0.51φ
Ｂ、Ｍは分子量） 式の両辺をＭ1/2で割ると、 〔η〕/M1/2＝Ｋθ＋CM1/2 ……′ となり、縦軸に〔η〕/M1/2をとり、横軸にＭ1/2をプロ
ットして直線が得られる。直線の勾配ＣはＢに依存する
が、このＢは溶媒と高分子間の相互作用の大きさに依存
する定数で、θ温度ではＢ＝Ｏ、良溶媒系でＢ＜Ｏとな
る。したがって、第１図に例示するグラフで、摂動のな
い理想の測定条件、すなわちθ温度での式′は、溶媒
の種類に拘らず横軸に平行な直線となる。Now, looking at the measurement conditions of molecular weight at the level of the molecular chain,
There is a fact that the spread of polymer chains in a solution depends on the solvent and the measurement temperature.
In other words, it can be said that it is desirable to measure the molecular weight at the temperature of θ which becomes a perturbation state. Looking at this from the Stockmeyer-Fixman equation, [η] = KθM 1/2 + CM (where [η] is the limiting viscosity, Kθ is a constant, and the constant C = 0.51φ.
(B, M are molecular weights) When both sides of the equation are divided by M 1/2 , [η] / M 1/2 = Kθ + CM 1/2 ... ′, And the vertical axis is [η] / M 1/2 . A straight line is obtained by plotting M 1/2 on the horizontal axis. The gradient C of the straight line depends on B. This B is a constant depending on the magnitude of the interaction between the solvent and the polymer, and B = O at the θ temperature and B <O in the good solvent system. Accordingly, in the graph illustrated in FIG. 1, the ideal measurement condition without perturbation, that is, the equation 'at the θ temperature is a straight line parallel to the horizontal axis regardless of the type of the solvent.
しかし、従来のGPC法では、測定条件としての室温に
近いθ温度が得難く、このため測定に誤差が生じて分子
量分布を示すグラフに再現性がなく、左右対称となるべ
きピークが測定毎にテーリング（左右非対称）するとい
う問題点を有していた。However, in the conventional GPC method, it is difficult to obtain a θ temperature close to room temperature as a measurement condition, which causes an error in the measurement, the graph showing the molecular weight distribution is not reproducible, and a peak to be symmetrical in each measurement is generated every measurement. There was a problem of tailing (left-right asymmetric).
この発明の課題は、上記GPC法によって高分子材料の
分子量を測定する際に、この高分子材料の溶媒を室温に
近いθ温度として測定し得ることにより、正確な分子量
分布を得て分子量を求めることにある。An object of the present invention is to obtain a precise molecular weight distribution and obtain a molecular weight by measuring the solvent of the polymer material as a θ temperature close to room temperature when measuring the molecular weight of the polymer material by the GPC method. It is in.
上記の課題を解決するため、この発明においては、不
活性重合体からなるカラムを所定の溶媒でゲル状に膨潤
させて定常相とし、この定常相には前記溶媒に溶解した
高分子材料を移動相として浸透させ、この移動相の時間
当りの流出量と測定濃度とから前記高分子材料の分子量
を求める分子量測定方法において、 前記所定の溶媒がヘキサフルオロイソプロパノールに
水を0.1重量％以上２重量％未満添加した混合溶媒から
なる分子量測定方法を作用したのである。以下、その詳
細を述べる。In order to solve the above problems, in the present invention, a column made of an inert polymer is swollen in a gel state with a predetermined solvent to form a stationary phase, and a polymer material dissolved in the solvent is transferred to the stationary phase. A method for determining the molecular weight of the polymer material from the amount of the mobile phase per hour and the measured concentration, wherein the predetermined solvent is hexafluoroisopropanol in which water is added in an amount of 0.1% by weight to 2% by weight. The method of measuring the molecular weight consisting of the mixed solvent added in less than an amount worked. The details are described below.
この発明に用いる不活性重合体からなるカラムは、特
に限定されるものではなく、代表的な有機溶媒系カラム
を採用し得るが、たとえばハイポーラスな架橋をしたス
チレンジビニルベンゼン共重合体を、テトラヒドロフラ
ン（THF）やトルエンなどの溶剤でステンレス管に被着
したもの、または所定の粒子径（たとえば10μｍ）の全
多孔性シリカに官能基としてエーテルを化学結合したも
の、その他測定対象の高分子材料およびその溶媒に不活
性なものを採用する。The column made of the inert polymer used in the present invention is not particularly limited, and a typical organic solvent-based column can be adopted.For example, a highly crosslinked styrenedivinylbenzene copolymer can be prepared by using tetrahydrofuran. (THF) or a solvent coated on a stainless steel tube with toluene or the like, or a porous material having a predetermined particle size (for example, 10 μm) chemically bonded with ether as a functional group, other polymer materials to be measured, Use an inert solvent.
測定対象の高分子材料としては、ポリ1,4−ブチレン
テレフタレート（以下、PBTと略称する）のほか、ナイ
ロン６、ナイロン66などを挙げることができる。Examples of the polymer material to be measured include poly-1,4-butylene terephthalate (hereinafter abbreviated as PBT), nylon 6, and nylon 66.
前記カラムを膨潤させかつ高分子材料を溶解する所定
の溶媒は、ヘキサフルオロイソプロパノール（以下HFIP
と略称する）に水を0.1重量％以上２重量％未満添加し
たものを用いる。なぜなら、HFIPに添加する水の割合が
0.1重量％未満の少量または、２重量％以上の多量で
は、分子量測定条件としてのθ温度が室温から離れたも
のとなるからである。特に好ましい配合割合としては、
HFIP99重量％に対して水１重量％を例示することができ
る。The predetermined solvent for swelling the column and dissolving the polymer material is hexafluoroisopropanol (hereinafter HFIP).
To which 0.1% by weight or more and less than 2% by weight of water are added. Because the proportion of water added to HFIP
This is because a small amount of less than 0.1% by weight or a large amount of 2% by weight or more causes the θ temperature as a molecular weight measurement condition to be apart from room temperature. As a particularly preferred compounding ratio,
For example, 1% by weight of water can be exemplified with respect to 99% by weight of HFIP.
この発明に用いる所定の溶媒において、HFIPに添加す
る少量の水がどのような作用で高分子材料の分子量の測
定方法をθ温度に接近させるのか、その作用機構は明ら
かではないが、HFIPと高分子材料との間の何らかの反応
を抑制するため測定値の誤差が少なくなり、分子量分布
のピークのテーリングが防止されるとも考えられる。It is not clear how the small amount of water added to the HFIP causes the method for measuring the molecular weight of the polymer material to approach the θ temperature in the given solvent used in the present invention. It is also believed that errors in the measured values are reduced to suppress any reaction with the molecular material, and tailing of the peak of the molecular weight distribution is prevented.
PBTの分子量分布および分子量をθ温度条件下でGPC法
によって求めるため、以下の実験を行なった。すなわ
ち、測定試料のPBTを溶解するHFIPに対して、精製水を
全く加えない溶媒ａ、HFIP98重量％に対して精製水を２
重量％を加えた混合溶媒ｂ、HFIP99重量％に対して精製
水を１重量％を加えた混合溶媒ｃを調製し、測定温度45
℃でストックマイヤー−フィックスマンプロットを求め
た（第１図参照）。第１図の直線の傾きから明らかなよ
うに、混合溶媒ｃが測定温度45℃でほぼθ温度であり、
この系が測定溶媒に適していることがわかった。The following experiment was performed to determine the molecular weight distribution and molecular weight of PBT by the GPC method under θ temperature conditions. That is, the solvent a to which no purified water is added is added to the HFIP in which the PBT of the measurement sample is dissolved,
A mixed solvent b containing 1% by weight of purified water with respect to 99% by weight of HFIP was prepared.
A Stockmeyer-Fixman plot was determined at ° C. (see FIG. 1). As is clear from the inclination of the straight line in FIG. 1, the mixed solvent c has a measurement temperature of 45 ° C. and a temperature of approximately θ,
This system was found to be suitable for the measurement solvent.
次に、第４図に示す装置の試料カラム４（ウォーター
ズ社製:ULTRASTYRAGEL liner×104A）および比較カラム
６（試料カラムに同じ）に、HFIP99重量％と精製水を１
重量％の混合溶媒ｃを充分浸透させ、これらカラム４、
６を膨潤させて定常相とした。この定常相に対して、上
記の混合溶媒ｃを移動相とし、45℃の温度条件下でポン
プ２（ウォーターズ社製:M510）によって流速0.5ml/分
で供給し、両カラム４、６を浸透、流下させた。その
際、クロマトプロセッサー（東ソウ社製:CP−8000）の
記録紙の横軸に流出量（ml）、縦軸に変換値をとって分
子量分布の変換曲線をプロットした。このグラフを第２
図に示す。また、対照例として、上記の混合溶媒に代え
てHFIP100％の溶媒ａを用いる以外は、全く同様にして
得た変換曲線を第２図中、一点鎖線で併記した。Next, 99% by weight of HFIP and purified water were added to a sample column 4 (ULTRASTYRAGEL liner × 10 4 A, manufactured by Waters) and a comparison column 6 (same as the sample column) of the apparatus shown in FIG.
% By weight of the mixed solvent c.
6 was swollen to a stationary phase. To the stationary phase, the mixed solvent c was used as a mobile phase, and the mixture was supplied at a flow rate of 0.5 ml / min by a pump 2 (manufactured by Waters: M510) at a temperature of 45 ° C. to permeate both columns 4 and 6. And let it flow down. At this time, the conversion curve of the molecular weight distribution was plotted by plotting the outflow amount (ml) on the horizontal axis and the conversion value on the vertical axis of the recording paper of a chromatoprocessor (manufactured by Tosoh Corporation: CP-8000). This graph is
Shown in the figure. In addition, as a control example, a conversion curve obtained in exactly the same manner except that a solvent a of 100% HFIP was used instead of the above-mentioned mixed solvent was also shown by a dashed line in FIG.
また、流出量の測定時毎に、別途、極限粘度〔η〕を
求め、この結果を第３図に示した。この場合、流出量と
極限粘度は直線関係にあり、 （ａはカラムごとに決まる定数）の関係から流出量別に
分子量を求めた。In addition, the intrinsic viscosity [η] was separately obtained every time the outflow amount was measured, and the results are shown in FIG. In this case, the outflow and the limiting viscosity have a linear relationship, (A is a constant determined for each column), and the molecular weight was determined for each outflow amount.
第２図のグラフから明らかなように、HFIP99重量％に
精製水１重量％を添加した混合溶媒ｃで、PBTのGPC法に
よる分子量分布をプロットすると、ほぼ正規分布に近い
曲線が得られ、従来、100％HFIP溶媒で得られた曲線に
比べてピーク（極大値付近）が左右非対称とならず、測
定誤差の少ないものが得られた。As is clear from the graph of FIG. 2, when the molecular weight distribution of PBT by the GPC method is plotted with a mixed solvent c in which 1% by weight of purified water is added to 99% by weight of HFIP, a curve substantially similar to a normal distribution is obtained. The peak (near the maximum value) did not become bilaterally asymmetric as compared with the curve obtained with 100% HFIP solvent, and a measurement error was obtained.
なお、PBTは、加水分解し易いため、移動相に水を添
加した場合にPBTの加水分解が問題となるが、PBTを移動
相と同じ溶媒に溶解し、24時間放置した後の測定でも同
じピークが得られ、加水分解による分子量の劣化は殆ん
どないことが判明した。さらに、混合溶媒中のHFIPは、
水とは共沸しないため蒸留による分離が可能であり、ま
た脱水分離も容易であり、高価な試薬であるHFIPを再使
用して用いることができた。Since PBT is easily hydrolyzed, hydrolysis of PBT becomes a problem when water is added to the mobile phase.However, the same applies to the measurement after dissolving PBT in the same solvent as the mobile phase and allowing it to stand for 24 hours. A peak was obtained, and it was found that there was almost no deterioration in molecular weight due to hydrolysis. Further, HFIP in the mixed solvent is
Since it does not azeotrope with water, it can be separated by distillation, and can be easily separated by dehydration. The expensive reagent HFIP can be reused and used.
この発明は、以上説明したように、GPC法で使用する
溶媒をHFIPに水を所定量添加した混合溶媒として、室温
に近いθ温度下で測定し得ることにより、測定材料の分
子相互間の作用である排除体積効果を無くすることがで
きるため、プロットされるグラフのピークがテーリング
せず、再現性よく高分子材料の分子量分布および分子量
の測定を正確に行なうことができるという利点がある。As described above, the present invention can measure the solvent used in the GPC method at a θ temperature close to room temperature as a mixed solvent obtained by adding a predetermined amount of water to HFIP, so that the interaction between the molecules of the measurement material can be measured. Since the excluded volume effect can be eliminated, there is an advantage that the peak of the plotted graph does not tail, and the molecular weight distribution and molecular weight of the polymer material can be accurately measured with good reproducibility.
第１図はストックマイヤー−フィックスマンプロットを
示すグラフ、第２図は分子量分布を示すグラフ、第３図
は流出量と極限粘度の関係を示すグラフ、第４図は模式
化して示すGPC法の測定装置図である。 ４……試料カラム、６……比較カラム。FIG. 1 is a graph showing a Stockmeyer-Fixman plot, FIG. 2 is a graph showing a molecular weight distribution, FIG. 3 is a graph showing a relationship between an outflow amount and an intrinsic viscosity, and FIG. 4 is a schematic diagram of a GPC method. FIG. 4 ... sample column, 6 ... comparison column.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) G01N 30/26 G01N 30/88──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 6 , DB name) G01N 30/26 G01N 30/88
Claims (1)
でゲル状に膨潤させて定常相とし、この定常相には前記
溶媒に溶解した高分子材料を移動相として浸透させ、こ
の移動相の時間当りの流出量と測定濃度とから前記高分
子材料の分子量を求める分子量測定方法において、 前記所定の溶媒がヘキサフルオロイソプロパノールに水
を0.1重量％以上２重量％未満添加した混合溶媒からな
ることを特徴とする高分子材料の分子量測定方法。1. A column comprising an inert polymer is swollen in a gel form with a predetermined solvent to form a stationary phase, and a polymer material dissolved in the solvent is permeated into the stationary phase as a mobile phase. In the molecular weight measuring method for determining the molecular weight of the polymer material from the outflow per unit time and the measured concentration, the predetermined solvent comprises a mixed solvent obtained by adding water to hexafluoroisopropanol in an amount of 0.1% by weight or more and less than 2% by weight. A method for measuring the molecular weight of a polymer material, comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7835990A JP2854661B2 (en) | 1990-03-26 | 1990-03-26 | Method for measuring molecular weight of polymer materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7835990A JP2854661B2 (en) | 1990-03-26 | 1990-03-26 | Method for measuring molecular weight of polymer materials |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03276065A JPH03276065A (en) | 1991-12-06 |
| JP2854661B2 true JP2854661B2 (en) | 1999-02-03 |
Family
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7835990A Expired - Lifetime JP2854661B2 (en) | 1990-03-26 | 1990-03-26 | Method for measuring molecular weight of polymer materials |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2854661B2 (en) |
-
1990
- 1990-03-26 JP JP7835990A patent/JP2854661B2/en not_active Expired - Lifetime
Non-Patent Citations (1)
| Title |
|---|
| Ｏｈｒｏｍａｔｏｇｒ．Ｓｃｉ．（１９７７），８（Ｌｉｑ．Ｃｈｒｏｍａｔｏｇｒ．Ｐｏｌｙｍ．Ｒｅｌａｔ．Ｍａｔｅｒ），４１−５０ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03276065A (en) | 1991-12-06 |
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