JPH02129207A - Preparation of water-absorbing polymer - Google Patents
Preparation of water-absorbing polymerInfo
- Publication number
- JPH02129207A JPH02129207A JP28135388A JP28135388A JPH02129207A JP H02129207 A JPH02129207 A JP H02129207A JP 28135388 A JP28135388 A JP 28135388A JP 28135388 A JP28135388 A JP 28135388A JP H02129207 A JPH02129207 A JP H02129207A
- Authority
- JP
- Japan
- Prior art keywords
- water
- absorbing polymer
- polymerization
- reaction
- salt
- 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.)
- Granted
Links
- 229920000642 polymer Polymers 0.000 title claims abstract description 29
- 239000000178 monomer Substances 0.000 claims abstract description 32
- 238000000034 method Methods 0.000 claims abstract description 17
- 238000009835 boiling Methods 0.000 claims abstract description 16
- 150000003839 salts Chemical class 0.000 claims abstract description 10
- 230000000379 polymerizing effect Effects 0.000 claims abstract description 4
- 239000000203 mixture Substances 0.000 claims description 22
- 238000004519 manufacturing process Methods 0.000 claims description 14
- 239000012736 aqueous medium Substances 0.000 claims description 7
- 238000003825 pressing Methods 0.000 claims description 3
- 150000007934 α,β-unsaturated carboxylic acids Chemical class 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 abstract description 23
- 150000001732 carboxylic acid derivatives Chemical class 0.000 abstract description 6
- 239000004566 building material Substances 0.000 abstract description 3
- 239000003795 chemical substances by application Substances 0.000 abstract description 3
- 238000009833 condensation Methods 0.000 abstract description 3
- 230000005494 condensation Effects 0.000 abstract description 3
- 238000001035 drying Methods 0.000 abstract description 3
- 239000003921 oil Substances 0.000 abstract description 3
- 239000010802 sludge Substances 0.000 abstract description 3
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 abstract description 2
- 230000015271 coagulation Effects 0.000 abstract description 2
- 238000005345 coagulation Methods 0.000 abstract description 2
- 230000018044 dehydration Effects 0.000 abstract 1
- 238000006297 dehydration reaction Methods 0.000 abstract 1
- RPACBEVZENYWOL-XFULWGLBSA-M sodium;(2r)-2-[6-(4-chlorophenoxy)hexyl]oxirane-2-carboxylate Chemical compound [Na+].C=1C=C(Cl)C=CC=1OCCCCCC[C@]1(C(=O)[O-])CO1 RPACBEVZENYWOL-XFULWGLBSA-M 0.000 abstract 1
- 238000006116 polymerization reaction Methods 0.000 description 33
- 239000007864 aqueous solution Substances 0.000 description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 21
- 239000000047 product Substances 0.000 description 17
- 238000010521 absorption reaction Methods 0.000 description 12
- 239000000843 powder Substances 0.000 description 12
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 11
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 11
- 239000002245 particle Substances 0.000 description 10
- 239000011347 resin Substances 0.000 description 9
- 229920005989 resin Polymers 0.000 description 9
- -1 polyoxyethylene Polymers 0.000 description 8
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 229910052783 alkali metal Inorganic materials 0.000 description 4
- 229920000578 graft copolymer Polymers 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 3
- 229920001577 copolymer Polymers 0.000 description 3
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 3
- 238000006386 neutralization reaction Methods 0.000 description 3
- 150000002978 peroxides Chemical class 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 229920000058 polyacrylate Polymers 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- KUDUQBURMYMBIJ-UHFFFAOYSA-N 2-prop-2-enoyloxyethyl prop-2-enoate Chemical compound C=CC(=O)OCCOC(=O)C=C KUDUQBURMYMBIJ-UHFFFAOYSA-N 0.000 description 2
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 2
- 229920002472 Starch Polymers 0.000 description 2
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 2
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000004132 cross linking Methods 0.000 description 2
- 238000007720 emulsion polymerization reaction Methods 0.000 description 2
- 239000003999 initiator Substances 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- ZIUHHBKFKCYYJD-UHFFFAOYSA-N n,n'-methylenebisacrylamide Chemical compound C=CC(=O)NCNC(=O)C=C ZIUHHBKFKCYYJD-UHFFFAOYSA-N 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 235000010352 sodium erythorbate Nutrition 0.000 description 2
- 239000004320 sodium erythorbate Substances 0.000 description 2
- 235000011121 sodium hydroxide Nutrition 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- RBWSWDPRDBEWCR-RKJRWTFHSA-N sodium;(2r)-2-[(2r)-3,4-dihydroxy-5-oxo-2h-furan-2-yl]-2-hydroxyethanolate Chemical compound [Na+].[O-]C[C@@H](O)[C@H]1OC(=O)C(O)=C1O RBWSWDPRDBEWCR-RKJRWTFHSA-N 0.000 description 2
- 239000008107 starch Substances 0.000 description 2
- 235000019698 starch Nutrition 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 238000010557 suspension polymerization reaction Methods 0.000 description 2
- BLKRGXCGFRXRNQ-SNAWJCMRSA-N (z)-3-carbonoperoxoyl-4,4-dimethylpent-2-enoic acid Chemical compound OC(=O)/C=C(C(C)(C)C)\C(=O)OO BLKRGXCGFRXRNQ-SNAWJCMRSA-N 0.000 description 1
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- DPBJAVGHACCNRL-UHFFFAOYSA-N 2-(dimethylamino)ethyl prop-2-enoate Chemical compound CN(C)CCOC(=O)C=C DPBJAVGHACCNRL-UHFFFAOYSA-N 0.000 description 1
- 125000000954 2-hydroxyethyl group Chemical group [H]C([*])([H])C([H])([H])O[H] 0.000 description 1
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 108010009736 Protein Hydrolysates Proteins 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 241000482268 Zea mays subsp. mays Species 0.000 description 1
- 150000001252 acrylic acid derivatives Chemical class 0.000 description 1
- VAZSKTXWXKYQJF-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)OOS([O-])=O VAZSKTXWXKYQJF-UHFFFAOYSA-N 0.000 description 1
- 235000010323 ascorbic acid Nutrition 0.000 description 1
- 229960005070 ascorbic acid Drugs 0.000 description 1
- 239000011668 ascorbic acid Substances 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 230000001112 coagulating effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000005183 environmental health Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 229920005615 natural polymer Polymers 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000012966 redox initiator Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- SCWRZVNHPALKOK-UHFFFAOYSA-M sodium;2-methyl-2-(prop-2-enoylamino)butane-1-sulfonate Chemical compound [Na+].[O-]S(=O)(=O)CC(C)(CC)NC(=O)C=C SCWRZVNHPALKOK-UHFFFAOYSA-M 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 238000012719 thermal polymerization Methods 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Landscapes
- Polymerisation Methods In General (AREA)
Abstract
Description
【発明の詳細な説明】
（イ）発明の目的
「産業上の利用分野」
本発明は吸水性ポリマーの新規な製造法に関するもので
あり、該吸水性ポリマーは生理用品、おむつ、使い捨て
雑巾等の衛生用品や保水剤等の農園芸用品として使用さ
れている他、汚泥の凝固、建材の結露防止、油類の脱水
等の用途にも用いられているものでもあり、本発明は、
それら各種の業界および吸水性ポリマーを製造する化学
業界において広く利用されるものである。DETAILED DESCRIPTION OF THE INVENTION (a) Object of the invention "Field of industrial application" The present invention relates to a new method for producing a water-absorbing polymer. In addition to being used as sanitary products and agricultural and horticultural supplies such as water retention agents, it is also used for purposes such as coagulating sludge, preventing condensation on building materials, and dehydrating oils.
It is widely used in these various industries and in the chemical industry that manufactures water-absorbing polymers.
「従来の技術」
従来吸水性ポリマーとしては、カルボキシメチルセルロ
ース架橋物、ポリオキシエチレン架橋物、澱粉−アクリ
ロニトリルグラフト共重合体の加水分解物、澱粉−アク
リル酸グラフト共重合体、アクリル酸塩重合体架橋物、
アクリル酸塩系共重合体架橋物等が知られている。"Prior art" Conventional water-absorbing polymers include carboxymethylcellulose crosslinked products, polyoxyethylene crosslinked products, starch-acrylonitrile graft copolymer hydrolysates, starch-acrylic acid graft copolymers, and acrylate polymer crosslinks. thing,
Crosslinked acrylate copolymers are known.
これらの内、カルボキシメチルセルロース架橋物及びポ
リオキシエチレン架橋物では未だ満足すべき吸水能、保
水能を有するものは得られていない。Among these, carboxymethylcellulose crosslinked products and polyoxyethylene crosslinked products have not yet been found to have satisfactory water absorption and water retention abilities.
また、澱粉−アクリロニトリルグラフト共重合体の加水
分解物及び澱粉−アクリル酸グラフト共重合体は比較的
高い吸水能、保水能を有するが、天然高分子である澱粉
を使用しているため耐熱性、腐敗分解等に欠点があり、
その製造方法も複雑であるという問題点も有している。In addition, the hydrolyzate of starch-acrylonitrile graft copolymer and the starch-acrylic acid graft copolymer have relatively high water absorption and water retention capacity, but because they use starch, which is a natural polymer, they have low heat resistance, There are drawbacks to rotting and decomposition, etc.
Another problem is that the manufacturing method thereof is complicated.
さらに、アクリル酸塩重合体架橋物及びアクリル酸塩系
共重合体架橋物については吸水能、保水能及び品質安定
性等を満足し得るものであるが、その重合方法には種々
の問題点がある。Furthermore, although crosslinked acrylate polymers and crosslinked acrylate copolymers can satisfy water absorption capacity, water retention capacity, quality stability, etc., there are various problems with their polymerization methods. be.
即ち、アクリル酸塩重合体架橋物又はアクリル酸塩系共
重合体架橋物等の製造法として、水溶液重合、逆相乳化
重合、逆相懸濁重合等の各種重合方法が採用されている
が、これらの方法の何れも下記の様な問題点を有してい
る。That is, various polymerization methods such as aqueous solution polymerization, reverse-phase emulsion polymerization, and reverse-phase suspension polymerization have been adopted as methods for producing crosslinked acrylate polymers or crosslinked acrylate copolymers. All of these methods have the following problems.
例えば、逆相乳化重合、逆相懸濁重合等の場合は、重合
工程に有機溶媒を用いることが必須であるが、有機溶媒
の使用は、突発的重合や重合温度管理のミス等の発生に
より、反応系の温度や圧力が異常に上昇し爆発、火災を
招（危険性あるいは作業員に対する環境衛生等の問題が
ある。For example, in the case of reverse-phase emulsion polymerization, reverse-phase suspension polymerization, etc., it is essential to use an organic solvent in the polymerization process. , the temperature and pressure of the reaction system may rise abnormally, leading to explosions and fires (there are dangers and environmental health issues for workers, etc.).
一方、水溶液重合の場合は、反応制御が容易な点からバ
ッチ式で熱重合させる方法が主流であるが、収量の向上
を目的として、高濃度の単量体水溶液を重合させようと
すると、重合反応は、烈しく生じ、反応熱によって系の
温度は急激に上昇して沸騰状態になり、水蒸気の放出が
妨げられるため、反応が暴走してゲルにポツプコーン現
象が発生する。更に、溶液の粘度上昇によって、重合速
度が著しく増大するゲル効果現象も加わり、温度制御が
一層困難で、好ましい品質の製品が得られ難くなる。又
、製品の取り出し等の作業性も著しく劣る様になる。On the other hand, in the case of aqueous solution polymerization, batch thermal polymerization is the mainstream method because it is easy to control the reaction, but when trying to polymerize a highly concentrated monomer aqueous solution with the aim of improving the yield, The reaction occurs violently, and the temperature of the system rapidly rises due to the reaction heat, reaching a boiling state, which prevents the release of water vapor, causing the reaction to run out of control and causing a popcorn phenomenon in the gel. Furthermore, due to the increase in the viscosity of the solution, there is also the phenomenon of gel effect, which significantly increases the polymerization rate, making temperature control more difficult and making it difficult to obtain products of favorable quality. In addition, the workability of taking out products, etc. becomes significantly inferior.
この問題点の解消、即ちに反応の温度制御を容易にする
ため比較的低温度で重合反応させるという方法も考えら
れているが、その方法では反応時間が長くなるため生産
効率が低いという欠点が生ずる。In order to solve this problem, a method has been considered in which the polymerization reaction is carried out at a relatively low temperature in order to make it easier to control the temperature of the reaction, but this method has the drawback of low production efficiency due to the long reaction time. arise.
一方、こうした生産性の問題を解決すべく、比較的高濃
度の単量体水溶液をあらかじめ加温しておき、これに重
合反応開始剤を添加して外部加熱を行うことなく、エン
ドレスベルト上等で連続的に重合させると共に水分を気
化させるという、乾燥工程も要しないという生産効率の
高い製造方法も提案されているが、この方法においては
、生産効率が高い反面、苛酷な重合条件故重合熱による
水の蒸発のため得られる樹脂が多孔質となる傾向があり
、得られた樹脂は、保水率が低く加圧時に一旦吸収した
水が放出されるいわゆるもどり現象を生じるという問題
点があり、更に、低分子量物が多く生成するために吸水
時にべとつき感が生じるという問題点がある。又、いず
れの製造方法であっても、得られた樹脂の吸水速度向上
のためには、後架橋、表面処理等を行う必要があった。On the other hand, in order to solve these productivity problems, a relatively high concentration monomer aqueous solution is heated in advance, a polymerization reaction initiator is added to it, and an endless belt can be used without external heating. A production method with high production efficiency that does not require a drying process has also been proposed, in which continuous polymerization is carried out at the same time as moisture is vaporized.However, although this method has high production efficiency, it does not require much heat of polymerization due to the harsh polymerization conditions. The resulting resin tends to become porous due to the evaporation of water, and the resulting resin has a problem of low water retention and a so-called rebound phenomenon in which water that has been absorbed is released when pressurized. Furthermore, since a large amount of low molecular weight substances are produced, there is a problem that a sticky feeling occurs when water is absorbed. In addition, regardless of the production method, post-crosslinking, surface treatment, etc. must be performed in order to improve the water absorption rate of the resulting resin.
「発明が解決しようとする課題」 本発明は、アクリル酸又はアクリル酸塩等のα。"Problem that the invention attempts to solve" The present invention relates to α such as acrylic acid or acrylate.
β−不飽和カルボン酸又はその塩を主体とする単量体混
合物を重合して吸水性ポリマーとする際の上記問題点を
解消し、生産性、作業性に優れ、物性面の優れた吸水性
ポリマーが得られる製造方法を提供することにある。Solved the above-mentioned problems when polymerizing a monomer mixture mainly composed of β-unsaturated carboxylic acid or its salt to form a water-absorbing polymer, which has excellent productivity and workability, and has excellent water-absorbing properties in terms of physical properties. It is an object of the present invention to provide a manufacturing method by which a polymer can be obtained.
（ロ）発明の構成
「課題を解決するための手段」
本発明者は、前記の如き実状に鑑み、上記目的を達成す
べく、従来吸水性ポリマーの製造では実質的に行われた
ことのない加圧重合により反応系における沸騰を防止し
ながら重合することによれば、アクリル酸又はアクリル
酸塩等のα、β−不飽和カルボン酸又はその塩を主体と
する単量体混合物水溶液から、上記問題点を解消し生産
性、作業性に優れ、物性面の優れた吸水性ポリマーが得
られることを見出して、本発明を完成したのである。(B) Structure of the Invention "Means for Solving the Problem" In view of the above-mentioned circumstances, the present inventor has proposed a method that has not been practically used in the production of water-absorbing polymers in the past, in order to achieve the above-mentioned object. By performing polymerization while preventing boiling in the reaction system by pressure polymerization, the above-mentioned monomer mixture can be prepared from an aqueous solution of a monomer mixture mainly consisting of α, β-unsaturated carboxylic acids such as acrylic acid or acrylates, or salts thereof. The present invention was completed by discovering that the problems could be solved and a water-absorbing polymer with excellent productivity, workability, and physical properties could be obtained.
即ち、本発明はα、β−不飽和カルボン酸又はその塩を
主体とする単量体混合物を、水性媒体中において加圧に
より水性媒体の沸騰を防止しつつ重合することを特徴と
する吸水性ポリマーの製造方法に関するもので、ある。That is, the present invention provides a water-absorbing method characterized by polymerizing a monomer mixture mainly composed of α,β-unsaturated carboxylic acid or a salt thereof in an aqueous medium while preventing boiling of the aqueous medium by applying pressure. It relates to a method for producing polymers.
本発明におけるα１．β−不飽和カルボン酸又はその塩
とは、アクリル酸、メタクリル酸、イタコン酸、マレイ
ン酸等に代表される不飽和カルボン酸又は該カルボン酸
のナトリウム、カリウム等の金属塩等のことであり、そ
れらを主体とする単量体混合物とは、それらの単量体の
１種又は２種以上からなるか、それらと他の親水性単量
体、例えばアクリルアミド、２−ヒドロキシエチル（メ
タ）アクリレート、２−（メタ）アクリロイルエタンス
ルホン酸、２−アクリルアミド２−エチルプロパンスル
ホン酸ソーダ、ジメチルアミノエチルアクリレートの四
級塩等のビニル系親水性単量体、架橋構造を導入し得る
Ｎ、Ｎ−メチレンビスアクリルアミド、エチレングリコ
ールジアクリレートなどの親水性多官能単量体との混合
体のことである。α1 in the present invention. β-Unsaturated carboxylic acid or its salt refers to an unsaturated carboxylic acid represented by acrylic acid, methacrylic acid, itaconic acid, maleic acid, etc. or a metal salt such as sodium or potassium of the carboxylic acid, etc. A monomer mixture mainly composed of these monomers includes one or more of these monomers, or a mixture of these monomers and other hydrophilic monomers such as acrylamide, 2-hydroxyethyl (meth)acrylate, Vinyl hydrophilic monomers such as 2-(meth)acryloylethanesulfonic acid, sodium 2-acrylamido-2-ethylpropanesulfonate, quaternary salt of dimethylaminoethyl acrylate, N,N-methylene that can introduce a crosslinked structure It is a mixture with hydrophilic polyfunctional monomers such as bisacrylamide and ethylene glycol diacrylate.
もちろん該単量体混合物として、従来より吸水性ポリマ
ーの製造に用いられている澱粉やセルロース等の添加さ
れているものであっても良い。Of course, the monomer mixture may be one to which starch, cellulose, etc., which have been conventionally used in the production of water-absorbing polymers, are added.
本発明にとり好ましい単量体混合物は、アクリル酸とア
クリル酸アルカリ金属塩を２０重量％以上含む単量体混
合物であり、アクリル酸とアクリル酸アルカリ金属塩の
割合（モル比）がθ〜８０；２０〜１００のものである
。尚、アクリル酸とアクリル酸アルカリ金属塩の混合物
は、アクリル酸をアルカリ金属塩で部分中和することに
より、任意のものが極めて容易に調製され、本発明に用
いられる。A preferred monomer mixture for the present invention is a monomer mixture containing 20% by weight or more of acrylic acid and an alkali metal salt of acrylate, and the ratio (molar ratio) of acrylic acid to an alkali metal salt of acrylate is θ to 80; 20 to 100. Any mixture of acrylic acid and an alkali metal salt of acrylic acid can be very easily prepared by partially neutralizing acrylic acid with an alkali metal salt, and can be used in the present invention.
単量体混合物の重合は水性溶液中でバッチ又は連続的に
行われるが、その隙の単量体濃度については、単量体が
溶解度の関係から水性溶液から析出しない範囲において
任意に調整することが出来、それも本発明の特長となる
ものである。当然、それは析出濃度付近での重合をも可
能とするものであり、それは生産効率を最大限に向上さ
せ得るものである。Polymerization of the monomer mixture is carried out batchwise or continuously in an aqueous solution, but the monomer concentration in the gap can be arbitrarily adjusted to the extent that the monomer does not precipitate from the aqueous solution due to solubility. This is also a feature of the present invention. Naturally, it also allows polymerization near the precipitate concentration, which can maximize production efficiency.
たとえば、アクリル酸９部分中和塩（中和度７０％ニア
クリル酸とアクリル酸塩の混合物）の水に対する溶解度
は、常温で４８％であり、本発明によれば、その様な濃
度での重合反応も可能にするものである。For example, the solubility of acrylic acid 9-partially neutralized salt (a mixture of niacrylic acid and acrylate with a degree of neutralization of 70%) in water is 48% at room temperature, and according to the present invention, polymerization at such a concentration is possible. It also enables reactions.
本発明においては１１重合時に水性媒体が沸騰すること
を防止するために、加圧することが必要で物と単量体混
合物の重合により生成した重合体を含む反応系（水性溶
液）の沸騰、特に水性媒体の沸騰を防止するできるもの
でなければならない。In the present invention, in order to prevent boiling of the aqueous medium during polymerization, it is necessary to pressurize the reaction system (aqueous solution) containing the polymer produced by the polymerization of the substance and monomer mixture. It must be possible to prevent boiling of the aqueous medium.
加圧により、ゲルも沸騰することなく、均一なゲルを生
成し得るが、単量体混合物濃度及び重合開始温度によっ
て、沸騰時圧力は種々変動するので、それに応じて、沸
騰を防止するに足る圧力を適宜設定すれば良いが、一般
的には０．５ Ｋｇ／ｃｓ＋”Ｇ以上の加圧下に重合さ
せるのが好ましく、より好ましくは２ Ｋｇ／ｃ＋＋＋
”Ｇ以上の加圧下の重合である。By applying pressure, a uniform gel can be produced without boiling, but the pressure at boiling varies depending on the concentration of the monomer mixture and the polymerization initiation temperature, so it is necessary to adjust the pressure to prevent boiling accordingly. Although the pressure may be set appropriately, it is generally preferable to polymerize under pressure of 0.5 Kg/cs+"G or more, more preferably 2 Kg/c+++
``Polymerization under pressure of G or higher.
加圧の上限は、得られる吸水性ポリマーの特性によって
制限されることはな（、主として製造設備化における経
済性および操作の難易性等から定められるものである。The upper limit of pressurization is not limited by the characteristics of the water-absorbing polymer to be obtained (it is mainly determined by the economical efficiency of manufacturing equipment, the difficulty of operation, etc.).
加圧は重合温度が高くなり水性媒体が沸騰するのを防止
するために行われるのであるから、単量体混合物或いは
単量体混合物と単量体混合物の重合により生成した重合
体を含む反応系（水性溶液）の沸騰温度前後で行えば良
いが、操作の容易性からは、重合期間中、前記した様に
設定された圧力を加えてお（のが望ましい。Pressurization is carried out to prevent the aqueous medium from boiling due to the high polymerization temperature, so the reaction system containing the monomer mixture or the polymer produced by the polymerization of the monomer mixture and the monomer mixture. It may be carried out at around the boiling temperature of the (aqueous solution), but from the viewpoint of ease of operation, it is desirable to apply the pressure set as described above during the polymerization period.
重合開始温度については、特に制限はなく、使用する触
媒系に応じて設定すれば良く、反応速度が著しく低下し
ない温度に設定すれば問題はない。The polymerization initiation temperature is not particularly limited and may be set depending on the catalyst system used, and there will be no problem as long as it is set at a temperature that does not significantly reduce the reaction rate.
開始剤としては、過硫酸塩、過酸化水素、こは（酸過酸
化物、ｔ−ブチルパーオキシマレイン酸などの過酸化物
の一種又は二種以上、或いはこれら過酸化物と亜硫酸ソ
ーダ、アスコルビン酸などの還元剤を組み合わせたレド
ックス系開始剤およびアゾ化合物などが用いられ、添加
量は通常単量体に対して０．０５〜０．５重量％である
。Examples of initiators include persulfates, hydrogen peroxide, one or more peroxides such as acid peroxide and t-butyl peroxymaleic acid, or these peroxides and sodium sulfite, ascorbic acid, etc. A redox initiator in combination with a reducing agent such as an acid, an azo compound, etc. are used, and the amount added is usually 0.05 to 0.5% by weight based on the monomer.
「作用」
前記した水性溶液重合によって吸水性ポリマーを製造し
ようとした場合、反応系の温度は、水性溶液の沸点を越
えないよう制御しなければ、反応の暴走のみならず、均
一なゲルを生成することが困難であると考えられていた
。そのために採用されていた方法は、ベルト重合するか
、モノマー濃度を低くして、反応熱を押さえるか、反応
スタート温度をできるだけ下げて、水溶液の沸点を越え
ないよう制御するという方法であった。このため、反応
時間が長くなったり、反応器容積当りの取得量に限界が
あり、又物性の優れた吸水性ポリマーが得にくいという
問題が存在した。"Effect" When attempting to produce a water-absorbing polymer by the above-mentioned aqueous solution polymerization, unless the temperature of the reaction system is controlled so as not to exceed the boiling point of the aqueous solution, the reaction will not only run out of control, but will also produce a uniform gel. It was considered difficult to do. The methods used for this purpose were to suppress the heat of reaction by performing belt polymerization, lowering the monomer concentration, or lowering the reaction start temperature as much as possible so as not to exceed the boiling point of the aqueous solution. For this reason, there were problems in that the reaction time was long, the amount obtained per reactor volume was limited, and it was difficult to obtain a water-absorbing polymer with excellent physical properties.
ところが、重合反応を加圧下に行うという本発明によれ
ば、即ち、重合反応時の反応温度における重合反応水溶
液の蒸気圧以上に加圧することにより、ゲルの沸騰が押
さえられ、沸点を気にする必要もなく、高濃度の単量体
水溶液でも制御良く重合反応を進めることが出来又、吸
水性ポリマーの均一なゲルを生成することが出来る。更
に、加圧下で反応させているので反応完結後ゲルの取り
出しも自圧を利用して容易に取り出すということも出来
る。However, according to the present invention in which the polymerization reaction is carried out under pressure, that is, by pressurizing the polymerization reaction solution to a level higher than the vapor pressure of the polymerization reaction aqueous solution at the reaction temperature during the polymerization reaction, boiling of the gel is suppressed, and boiling points are not a concern. This is not necessary, and the polymerization reaction can proceed in a well-controlled manner even with a highly concentrated monomer aqueous solution, and a uniform gel of the water-absorbing polymer can be produced. Furthermore, since the reaction is carried out under pressure, the gel can be easily taken out after the reaction is completed using its own pressure.
特に本発明によれば、加圧のためとは推定されるが、得
られる吸水性ポリマーのゲルは無数の細かい気泡を内包
し、吸水性ポリマーの吸水速度を大幅に向上し、かつ、
継粉になりにくいものになるという予測しえない優れた
性能を有する吸水性ポリマーが得られる。そしてこれは
、高濃度重合することにより、より顕著になる。In particular, according to the present invention, although it is presumed that this is due to pressurization, the resulting water-absorbing polymer gel contains countless fine bubbles, which greatly improves the water absorption rate of the water-absorbing polymer, and
A water-absorbing polymer is obtained that has unexpectedly excellent performance in that it is resistant to joint powder. This becomes more noticeable when polymerization is carried out at a high concentration.
一般に、吸水性ポリマー粉末は、その粒度が細かければ
細かい程、表面積が大きくなり、このため吸水速度が向
上するが、ある粒度までくると、吸水中に、粒子同志が
くっつき合って、継粉になり、これが吸水速度を下げる
原因となる。このため、無機系の微粉を表面にコーティ
ングしたり、表面架橋をする等の後処理によって、これ
を解決しようとしているが、本発明によれば、このよう
な工程もなくすことが出来る。In general, the finer the particle size of water-absorbing polymer powder, the larger the surface area, which improves the water absorption rate.However, when the particle size reaches a certain point, the particles stick together while absorbing water, causing joint powder. This causes the water absorption rate to decrease. Therefore, attempts have been made to solve this problem by post-processing such as coating the surface with inorganic fine powder or crosslinking the surface, but according to the present invention, such steps can be eliminated.
「実施例」
実施例１
アクリル酸３５．３部に水２２．８部加えて得た水溶液
に濃度３２％の苛性ソーダ水溶液４２部をかきまぜなが
ら加えて中和した。２０°Ｃまで冷却したのちこの水溶
液にメチレンビスアクリルアミド（以下ＭＢＡＭという
）を０．２部加え、加圧重合反応器で窒素バブリングし
たのち、過硫酸アンモニウム（以下ＡＰＳという）０．
０９部、エリソルビン酸ナトリウム（エルピントＮ：商
品名藤沢薬品工業株式会社製）０．００４５部をそれぞ
れ１０％水溶液にした状態で添加し、圧力４ Ｋｇ／ｃ
ｍ”Ｇ下で重合させた。"Examples" Example 1 To an aqueous solution obtained by adding 22.8 parts of water to 35.3 parts of acrylic acid, 42 parts of a 32% aqueous solution of caustic soda was added with stirring to neutralize the solution. After cooling to 20°C, 0.2 parts of methylenebisacrylamide (hereinafter referred to as MBAM) was added to this aqueous solution, nitrogen was bubbled in a pressure polymerization reactor, and 0.2 parts of ammonium persulfate (hereinafter referred to as APS) was added to this aqueous solution.
09 parts of sodium erythorbate (Elpinto N, manufactured by Fujisawa Pharmaceutical Co., Ltd.) and 0.0045 parts of sodium erythorbate (trade name: manufactured by Fujisawa Pharmaceutical Co., Ltd.) were each added as a 10% aqueous solution, and a pressure of 4 Kg/c was added.
Polymerization was carried out under m''G.
なお、この混合物は、中和度７０％、単量体見掛は濃度
４８％である。Note that this mixture has a degree of neutralization of 70% and an apparent monomer concentration of 48%.
系の温度は１３５°Ｃまで上昇し、約１０分間で重合反
応が終了した。The temperature of the system rose to 135°C, and the polymerization reaction was completed in about 10 minutes.
生成物を細断し、１２０°Ｃの熱風乾燥器中で乾燥し、
乾燥物を粉砕して樹脂粉末を得た。この粉末摺脂をふる
い分けをし、６０〜１００ｍｅｓｈの粒度のものを選別
した。The product was shredded and dried in a hot air oven at 120°C,
The dried product was pulverized to obtain resin powder. This powdered resin paste was sieved and those with a particle size of 60 to 100 mesh were selected.
１水１度■淵主ｍ
ガラスフィルター（１１Ｇ２）と５０ｍ１ビユレツトを
ゴム管で接続し、０６９％ＮａＣ１水溶液を入れ、フィ
ルター下部の空気を十分抜いたのち、フィルター表面が
液で滲みる程度に液面をビユレットを上下して合わせる
。６０〜１００ｍｅｓｈの粒度の粉末試料０．１ｇを精
秤し、これをフィルターに均一になるようばらまき、１
分後の吸水量を測定する（以下この方法をＣＡＰ法とい
う）。Connect the glass filter (11G2) and the 50ml bottle with a rubber tube, add 069% NaCl aqueous solution, remove enough air from the bottom of the filter, and then lower the liquid level so that the filter surface is smeared with liquid. Align the billet up and down. Precisely weigh 0.1 g of a powder sample with a particle size of 60 to 100 mesh, scatter it evenly on the filter, and
The amount of water absorbed after 5 minutes is measured (hereinafter this method will be referred to as the CAP method).
豫述ｊ団１乞１こに
１００ｄビーカーに０．９％ＮａＣ１水溶液５０蔵入れ
６００ ｒｐｍでマグネチックスクーラーで回転する。Place 50 0.9% NaCl aqueous solution in a 100 d beaker and rotate at 600 rpm with a magnetic cooler.
これに、６０〜１００ ｍｅｓｈの粒度の粉末試料２ｇ
を入れ、溶液表面が平らになる時間を読む。To this, 2 g of powder sample with particle size of 60 to 100 mesh was added.
and read the time it takes for the surface of the solution to become flat.
測定後継粉（白い固まり）状態をチエツクする（以下こ
の方法を渦巻法という）。Check the state of the powder (white lumps) after measurement (hereinafter this method is referred to as the swirl method).
実施例２
アクリル酸２２．１部に水５１．２部加えて得た水溶液
に濃度３２％の苛性ソーダ水溶液２６．２部をかきまぜ
ながら加えて中和した。２０゛Ｃまで冷却したのちこの
水溶液にＭＢＡＭを０．０６部加え、加圧重合反応器で
窒素バブリングしたのち、ＡＰＳｏ、０６部、エルビッ
トＮｏ、 ＯＯ３部をそれぞれ１０％水溶液にした状態
で添加し、圧力３ Ｋｇ／ｃｍｚＧ下で重合させた。こ
の混合物は中和度７０％、単量体見掛は濃度３０％であ
る。Example 2 To an aqueous solution obtained by adding 51.2 parts of water to 22.1 parts of acrylic acid, 26.2 parts of a 32% aqueous solution of caustic soda was added with stirring to neutralize the solution. After cooling to 20°C, 0.06 parts of MBAM was added to this aqueous solution, and nitrogen bubbling was carried out in a pressure polymerization reactor, followed by adding 10% aqueous solutions of APSo, 06 parts, Elbit No., and 3 parts of OO. , and a pressure of 3 Kg/cmzG. This mixture has a degree of neutralization of 70% and an apparent monomer concentration of 30%.
系の温度は９０°Ｃまで上昇し、約２０分間で重合反応
が終了した。The temperature of the system rose to 90°C, and the polymerization reaction was completed in about 20 minutes.
生成物を細断し、１２０°Ｃの熱風乾燥器中で乾燥し、
乾燥物を粉砕して樹脂粉末を得た。この粉末樹脂をふる
い分けをし、６０〜１００ｍｅｓｈの粒度のものを選別
した。The product was shredded and dried in a hot air oven at 120°C,
The dried product was pulverized to obtain resin powder. This powdered resin was sieved to select particles with a particle size of 60 to 100 mesh.
比較例１
実施例１と同様の混合物を作り常圧下で重合させた。反
応中１０６°Ｃを越えた時点で、ゲルが飛び出した。Comparative Example 1 A mixture similar to Example 1 was prepared and polymerized under normal pressure. When the temperature exceeded 106°C during the reaction, the gel popped out.
生成物を細断し、１２０°Ｃの熱風乾燥器中で乾燥し、
乾燥物を粉砕して樹脂粉末を得た。この粉未樹脂をふる
い分けをし、６０〜１００ｍｅｓｈの粒度のものを選別
した。The product was shredded and dried in a hot air oven at 120°C,
The dried product was pulverized to obtain resin powder. The unresin powder was sieved to select particles with a particle size of 60 to 100 mesh.
吸水樒皿二鷹星
以上の様にして得た樹脂粉末について吸水性能を測定し
第１表にまとめた。The water absorption performance of the resin powder obtained as described above was measured and summarized in Table 1.
第１表
第１表で明らかな様に、加圧重合したものは、吸水速度
が向上し、何等吸水後のゲルに継粉は発生しない。特に
高濃度で加圧重合したものは、後処理を行わなくても、
吸水速度が飛躍的に向上する。As is clear from Table 1, the pressure-polymerized gel has an improved water absorption rate, and no splintering occurs in the gel after water absorption. In particular, products polymerized under pressure at high concentrations can be treated without post-treatment.
Water absorption speed is dramatically improved.
（ハ）発明の効果 本発明は次の様な優れた効果を示す。(c) Effects of the invention The present invention exhibits the following excellent effects.
１、高濃度水溶液反応が可能で均一な吸水性ポリマーを
得ることができる。1. A highly concentrated aqueous solution reaction is possible and a uniform water-absorbing polymer can be obtained.
２、反応熱の除熱装置が不要である。2. A heat removal device for reaction heat is not required.
３、無数の微細な気泡を有する吸水性ポリマーが得られ
、後処理等を行わなくとも吸水速度の速い吸水性ポリマ
ーを得ることができる。3. A water-absorbing polymer having countless fine bubbles can be obtained, and a water-absorbing polymer with a high water absorption rate can be obtained without any post-treatment.
４、ゲルの取り出しが容易に行なえる。4. Gel can be easily taken out.
５、高濃度で重合できるため、乾燥工程が大幅に短縮で
き、設備規模もエネルギーコストも押さえられる。5. Because it can be polymerized at a high concentration, the drying process can be significantly shortened, reducing equipment scale and energy costs.
６、本発明で得られた吸水性ポリマーは、前記した優れ
た特性の故に、生理用品、おむつ、使い捨て雑巾等の衛
生用品や保水剤等の農園芸用品さらには、汚泥の凝固、
建材の結露防止、油類の脱水等に用いられて、従来のも
のよりさらに優れた効果を奏し得る。6. Due to the above-mentioned excellent properties, the water-absorbing polymer obtained in the present invention can be used for sanitary products such as sanitary products, diapers, and disposable rags, agricultural and horticultural products such as water retention agents, as well as coagulation of sludge,
It can be used to prevent condensation on building materials, dehydrate oil, etc., and can provide even better effects than conventional ones.
Claims (1)
単量体混合物を、水性媒体中において加圧により水性媒
体の沸騰を防止しつつ重合することを特徴とする吸水性
ポリマーの製造方法。1. Production of a water-absorbing polymer characterized by polymerizing a monomer mixture mainly consisting of an α,β-unsaturated carboxylic acid or a salt thereof in an aqueous medium while preventing boiling of the aqueous medium by applying pressure. Method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63281353A JPH0678389B2 (en) | 1988-11-09 | 1988-11-09 | Method for producing water-absorbent polymer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63281353A JPH0678389B2 (en) | 1988-11-09 | 1988-11-09 | Method for producing water-absorbent polymer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02129207A true JPH02129207A (en) | 1990-05-17 |
| JPH0678389B2 JPH0678389B2 (en) | 1994-10-05 |
Family
ID=17637929
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63281353A Expired - Lifetime JPH0678389B2 (en) | 1988-11-09 | 1988-11-09 | Method for producing water-absorbent polymer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0678389B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02170808A (en) * | 1988-12-23 | 1990-07-02 | Toagosei Chem Ind Co Ltd | Production of water-absorbing polymer |
| US6867269B2 (en) | 2001-12-19 | 2005-03-15 | Nippon Shokubai Co., Ltd. | Water-absorbent resin and production process therefor |
| US6906159B2 (en) | 2000-08-03 | 2005-06-14 | Nippon Shokubai Co., Ltd. | Water-absorbent resin, hydropolymer, process for producing them, and uses of them |
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| JPS5867706A (en) * | 1981-09-28 | 1983-04-22 | バスフ アクチエンゲゼルシヤフト | Manufacture of copolymer from monoethylenically unsaturated mono- and dicarboxylic acid |
| JPS62227904A (en) * | 1986-03-21 | 1987-10-06 | バスフ アクチェン ゲゼルシャフト | Discontinuous production of crosslinked fine particulate polymer |
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1988
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS52111986A (en) * | 1976-03-17 | 1977-09-20 | Sumitomo Chem Co Ltd | Preparation of sodium polyacrylate |
| JPS5867706A (en) * | 1981-09-28 | 1983-04-22 | バスフ アクチエンゲゼルシヤフト | Manufacture of copolymer from monoethylenically unsaturated mono- and dicarboxylic acid |
| JPS62227904A (en) * | 1986-03-21 | 1987-10-06 | バスフ アクチェン ゲゼルシャフト | Discontinuous production of crosslinked fine particulate polymer |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02170808A (en) * | 1988-12-23 | 1990-07-02 | Toagosei Chem Ind Co Ltd | Production of water-absorbing polymer |
| US6906159B2 (en) | 2000-08-03 | 2005-06-14 | Nippon Shokubai Co., Ltd. | Water-absorbent resin, hydropolymer, process for producing them, and uses of them |
| US7091253B2 (en) | 2000-08-03 | 2006-08-15 | Nippon Shokubai Co., Ltd. | Water-absorbent resin, hydropolymer, process for producing them, and uses of them |
| US7741400B2 (en) | 2000-08-03 | 2010-06-22 | Nippon Shokubai Co., Ltd. | Water-absorbent resin, hydropolymer, process for producing them, and uses of them |
| US6867269B2 (en) | 2001-12-19 | 2005-03-15 | Nippon Shokubai Co., Ltd. | Water-absorbent resin and production process therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0678389B2 (en) | 1994-10-05 |
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