JPH0261976B2 - - Google Patents
Info
- Publication number
- JPH0261976B2 JPH0261976B2 JP373183A JP373183A JPH0261976B2 JP H0261976 B2 JPH0261976 B2 JP H0261976B2 JP 373183 A JP373183 A JP 373183A JP 373183 A JP373183 A JP 373183A JP H0261976 B2 JPH0261976 B2 JP H0261976B2
- Authority
- JP
- Japan
- Prior art keywords
- water
- resin
- mol
- weight
- maleic acid
- 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
Links
- 229920005989 resin Polymers 0.000 claims description 40
- 239000011347 resin Substances 0.000 claims description 40
- 229920001577 copolymer Polymers 0.000 claims description 23
- 230000005855 radiation Effects 0.000 claims description 16
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims description 11
- 239000002250 absorbent Substances 0.000 claims description 11
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 claims description 11
- 239000011976 maleic acid Substances 0.000 claims description 11
- 238000007127 saponification reaction Methods 0.000 claims description 11
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 claims description 11
- 238000010894 electron beam technology Methods 0.000 claims description 10
- NKHAVTQWNUWKEO-UHFFFAOYSA-N fumaric acid monomethyl ester Natural products COC(=O)C=CC(O)=O NKHAVTQWNUWKEO-UHFFFAOYSA-N 0.000 claims description 10
- 230000002745 absorbent Effects 0.000 claims description 8
- PEXNXOXCZLFQAO-ODZAUARKSA-N (z)-but-2-enedioic acid;ethenyl acetate Chemical compound CC(=O)OC=C.OC(=O)\C=C/C(O)=O PEXNXOXCZLFQAO-ODZAUARKSA-N 0.000 claims description 7
- NKHAVTQWNUWKEO-IHWYPQMZSA-N methyl hydrogen fumarate Chemical group COC(=O)\C=C/C(O)=O NKHAVTQWNUWKEO-IHWYPQMZSA-N 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 3
- XLYMOEINVGRTEX-ARJAWSKDSA-N Ethyl hydrogen fumarate Chemical compound CCOC(=O)\C=C/C(O)=O XLYMOEINVGRTEX-ARJAWSKDSA-N 0.000 claims description 2
- XLYMOEINVGRTEX-UHFFFAOYSA-N fumaric acid monoethyl ester Natural products CCOC(=O)C=CC(O)=O XLYMOEINVGRTEX-UHFFFAOYSA-N 0.000 claims description 2
- 230000001678 irradiating effect Effects 0.000 claims 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 49
- 238000010521 absorption reaction Methods 0.000 description 22
- 239000002689 soil Substances 0.000 description 8
- 239000004372 Polyvinyl alcohol Substances 0.000 description 7
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 7
- 229920002451 polyvinyl alcohol Polymers 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 230000005484 gravity Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 239000003795 chemical substances by application Substances 0.000 description 4
- 235000019441 ethanol Nutrition 0.000 description 4
- 239000000178 monomer Substances 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 150000002576 ketones Chemical class 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 239000004342 Benzoyl peroxide Substances 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 1
- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 description 1
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 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
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 235000019400 benzoyl peroxide Nutrition 0.000 description 1
- -1 benzoyl peroxide peroxide Chemical class 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- LSXWFXONGKSEMY-UHFFFAOYSA-N di-tert-butyl peroxide Chemical compound CC(C)(C)OOC(C)(C)C LSXWFXONGKSEMY-UHFFFAOYSA-N 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 239000012770 industrial material Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L peroxydisulfate Chemical compound [O-]S(=O)(=O)OOS([O-])(=O)=O JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 229920006267 polyester film Polymers 0.000 description 1
- 239000003505 polymerization initiator Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 229920001567 vinyl ester resin Polymers 0.000 description 1
Landscapes
- Processes Of Treating Macromolecular Substances (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Description
本発明は特に植物や土壌の保水剤用途として有
用な流水中での流亡性を改良した高吸水性樹脂に
関するものである。
高吸水性を有する樹脂は、従来よりその機能を
生かして植物・土壌の保水剤等の他にも、衛生材
料、産業用材料として利用され、その需要はます
ます伸びつつある。それに伴い、高吸水性を有す
る樹脂の製造に関しても多くの技術が知られてい
る。
例えば、未変性のポリビニルアルールを水又は
含水非溶媒中で膨潤させ、これに放射線をあてる
ことにより、架橋させることは古くより行われて
いる。又、熱処理等により架橋させたビニルエス
テルとエチレン系不飽和カルボン酸の共重合体の
ケン化物がが優れた吸水能力を有することも公知
である。
しかしながら、本発明者らがこれまで公知の方
法により得られた高吸水性樹脂を検討したとこ
ろ、静置した状態での吸水能力、並びに保水能力
は確かに優れているものの、実際に例えば植物や
土壌の保水剤として土壌中に配合する場合には常
時かなりの量の水を潅水するし、一時的な大雨と
か、地下水の影響などにより水が静置している場
合には希でたえず土壌中を水が移動しており、か
かる条件下では該高吸水性樹脂が流水中に徐々に
溶け出すという現象のあることが判明し、単に吸
水倍率の大小のみならず、流水中での高吸水性樹
脂の特続効果が実用面で大きな解決課題であるこ
とを知るに到つた。
しかして、本発明者らは上記流水中における流
亡性を最小限に押えてしかも、その性能は従来の
ものと全く変わらない高吸水性樹脂を開発すべく
かねてより鋭意検討中であつたところ、マレイン
酸モノエステルの含量が0.2〜15モル%でかつケ
ン化度が70〜100モル%の酢酸ビニルーマレイン
酸モノエステル共重合体ケン化物に含水状態で
0.1〜50Mradsの電子線又は放射線処理(以下単
に放射線処理という)を施すことによつて、流水
中における流亡性が飛躍的に改善されることを見
出し、本発明を完成するに到つた。
本発明の必須要件の第1はまず共重合体の構成
単量体が酢酸ビニルとマレイン酸モノエステルで
あり、かつ該共重合体におけるマレイン酸モノエ
ステルの含量が0.2〜15モル%、より好ましくは
0.5〜5モル%でかつケン化度が70〜100モル%の
範囲から選ばれるという事である。単量体の種類
が他のエチレン系不飽和カルボン酸、例えばアク
リル酸、メタクリル酸及びその誘導体であつた
り、又マレイン酸モノエステルの含有量が15モル
%を超えた場合、得られる樹脂を放射線処理して
も流水中における流亡性はほとんど改善されな
い。低変性率の酢酸ビニルマレイン酸モノエステ
ル共重合体ケン化物という限定された樹脂に対し
て放射線処理を行うことによりかかる優れた性質
が得られるという事は意外な事である。更にポリ
ビニルアルコールにマレイン酸モノエステル等を
後反応させたマレイン化ポリビニルアルコールを
放射線処理しても本発明の効果は得られない。
又、マレイン酸モノエステルの含量が0.2モル%
以下、即ちほぼ未来性のポリビニルアルコール及
びケン化度が70モル%以下の酢酸ビニルーマレイ
ン酸モノエステル共重合体を放射線処理したもの
では流亡性はもとより、前記共重合体に比して吸
水能力、保水能力がかなり劣るものとなる。尚、
マレイン酸モノエステルとしては通常マレイン酸
モノメチル、マレイン酸モノエチルが使用され
る。
必須要件の第2は、上記酢酸ビニルーマレイン
酸モノエステル共重合体ケン化物を含水状態で
0.1〜50Mradsの放射線処理を施す事である。
含水率は通常1〜50重量%の範囲から選ばれ
る。
1重量%以下では放射線処理を行つても本発明
の目的とする高吸水性樹脂は得られないし、50重
量%を超えると該共重合体ケン化物の粒子同志が
融着して高吸水性樹脂としての性質を失う傾向が
ある。本発明に言う含水状態とは、水とアルコー
ル、エステル、ケトンなどとの混合液であつても
よい。アルコールとしては、共重合体ケン化物を
溶かさなければ特に限定はないが代表的にはメチ
ルアルコール、エチルアルコール、イソプロピル
アルコール等がまたエステル.ケトンとしては酢
酸メチル、アセトンなどとの混合液などが挙げら
れる。但し本発明に言う含水率とは次式により算
出されるものである。
含水率(重量%)
=共重合体ケン化物中の水の重量/共重合体ケン化
物の重量×100
かかる状態の酢酸ビニルーマレイン酸モノエステ
ル共重合体ケン化物に対し、放射線処理を行う。
本発明に言う放射線処理とは電子線、α線、β
線、γ線、X線、中性線を照射することである
が、通常は線源の安定性から電子線・γ線が好ん
で用いられる。該放射線の照射線量は先にも述べ
た如く0.1〜50Mradsでなければならず0.1Mrads
以下では効果が得られず、又50Mrads以上照射す
ると吸水倍率(吸水時の重量と吸水前の重量比)
が急激に低下し、高吸水性樹脂としての機能を果
たさない。
本発明の酢酸ビニルーマレイン酸モノエステル
共重合体ケン化物は公知の任意の方法で製造でき
るが、代表的には、重合開始剤、例えばジターシ
ヤリーブチルパーオキシド、ベンゾイルパーオキ
シドの過酸化物、過硫酸アンモニウムどの過硫酸
塩類の存在下、反応温度60〜75℃で酢酸ビニルと
マレイン酸モノメチルを共重合させる。得られる
共重合体を公知の方法、通常はアルコールを主成
分とする有機溶媒中で、水酸化ナトリウム等の適
当なアルカリ物質を用いてケン化を行う。
該共重合体ケン化物を含水状態にする際は樹脂
を温度30〜45℃、相対湿度90〜100%の状態で20
〜50時間程度吸湿させればよい。
かくして含水率を調整した後、該共重合体ケン
化物に放射線を照射する場合、特に規制するもの
ではないが、照射線量をできるだけ必要最小限に
するために通常は酸素濃度が1000ppm以下の窒素
雰囲下に行う。
かくして得られる本発明の流亡性を改善した高
吸水性樹脂は、従来使用されている衛生用品等に
ももちろん、使用可能ではあるが、特にその性質
が生かされるのは、常時又は、一時的に水が流れ
る場所でかつ常に保水状態がが必要な所、例えば
砂地における植物裁培用の保水剤、育苗用培土、
園芸用培土などの用途に非常に有用なものであ
る。
更に粉末としてのみならず、フイラメント、フ
イルム等の成形物としても優れた性能を有するも
のである。
以下、実施例によつて本発明を具体的に説明す
る。
但し、例中「吸水倍率」及び「残存率」とある
のは次の方法により、算出したものである。
「吸水倍率」:放射線処理を施した樹脂試料の純
樹脂分の500倍(重量比)のイオン交換水に一夜
浸漬した後、得られたゲルを別し、その重量を
測り、次に式により算出する。
吸水倍率
=吸水ゲルの重量/浸漬前の樹脂試料の純樹脂分の
重量
「残存率」:流水中に一定時間さらした樹脂を
別し、105℃にて6時間乾燥後、乾燥樹脂の重量
を測り、次の式により算出する。
残存率(重量%)
=吸水ゲルの乾燥後の重量/浸漬前の樹脂試料の純
樹脂分の重量×100
実施例 1
マレイン酸モノメチル含量2.1モル%の酢酸ビ
ニルーマレイン酸モノメチル共重合体ケン化物
(粒度0.84〜1.41mm、ケン化度94.1モル%)を温度
30℃、相対湿度98%の状態に48時間放置し、含水
率25.6重量%とした。カサ比重(100mlメスシリ
ンダーに該樹脂を入れた縦横方向に振動を加えて
最密充填とし、その重量を測つた。)は0.434g/
mlであつた。
この試料40.6gを13cm×24cmのポリエステルフ
イルム製の容器に入れ、試料の厚みを約2.9mmと
した。試料雰囲気を窒素ガスで置換した後、加速
電圧750KVの電子線照射装置にて5Mradsの電子
線を照射して、吸水倍率が168.4の高吸水性樹脂
を得た。
該高吸水性樹脂1.39をナイロンタフタ製過袋
に入れ、樹脂が袋の口から流出しないようにして
水を一杯に満たしたビーカー中に浸した。更に水
を該袋の上部から約1.1/時間の量で流し続け
て樹脂を流水中にさらした。約20時間後、40時間
後、80時間後、175時間後における該樹脂の残存
率を測定した。又、同時に吸水倍率も測定した
が、167.5でほとんど変化は見られなかつた。
残存率についての測定結果を第1表に示す。
実施例 2
マレイン酸モノメチル含量3.9モル%の酢酸ビ
ニルーマレイン酸モノメチル共重合体ケン化物
(粒度0.84〜0.50mm、ケン化度、98.1モル%)を実
施例1に順じて含水量29.8重量%とした。
カサ比重は0.530g/mlであつた。
以下、実施例1と同様にして電子線照射を行
い、吸水倍率が105の高吸水性樹脂を得て、その
流亡性を測定した。又、175時間後の吸水倍率を
測定したが、101弱冠低くなつただけであつた。
結果を第1表に示す。
実施例 3
マレイン酸モノメチル含量0.5モル%の酢酸ビ
ニルーマレイン酸モノメチル共重合体ケン化物
(粒度2.0〜1.41mm、ケン化度98.0モル%)を実施
例1に順じて含水率15.2重量%(但し、メチルア
ルコールを溶媒中に10重量%含有)とした、カサ
比重は0.583g/mlであつた。
以下、実施例1と同様にして電子線照射を行い
(但し、照射量は3Mrads)、吸水倍率が130.8の高
吸水性樹脂を得てその流亡性を測定した。又、
175時間後の吸水倍率を測定したところ、130とほ
とんど変化なかつた。
結果を第1表に示す。
実施例 4
マレイン酸モノメチル含量11.8モル%の酢酸ビ
ニルーマレイン酸モノメチル共重合体ケン化物
(粒度0.84〜1.41mm、ケン化度98.5モル%)を実施
例1に順じて含水率19.3重量%とした。
カサ比重は0.473g/mlであつた。
以下、実施例1と同様にして電子線照射を行い
(但し、照射量は1Mrads)、吸水倍率が96.2の高
吸水性樹脂を得てその流亡性を測定した。又、
175時間後の吸水倍率を測定したところ、96とほ
とんど変化はなかつた。
結果を第1表に示す。
The present invention relates to a super-absorbent resin with improved washability in running water, which is particularly useful as a water-retaining agent for plants and soil. Resins with high water absorption properties have traditionally been used as water retention agents for plants and soil, as well as sanitary materials and industrial materials, and the demand for them is increasing. Along with this, many techniques are known regarding the production of resins having high water absorption properties. For example, crosslinking has been carried out for a long time by swelling unmodified polyvinyl alcohol in water or a water-containing nonsolvent and exposing it to radiation. It is also known that a saponified copolymer of vinyl ester and ethylenically unsaturated carboxylic acid crosslinked by heat treatment or the like has excellent water absorption ability. However, when the present inventors examined superabsorbent resins obtained by conventional methods, they found that although they certainly have excellent water absorption and water retention abilities when left standing, they are actually used in plants, for example. When mixed into the soil as a soil water retention agent, a considerable amount of water is constantly applied, and in rare cases where water remains still due to temporary heavy rain or the influence of groundwater, water may be constantly added to the soil. It was found that there is a phenomenon in which the superabsorbent resin gradually dissolves into the flowing water under such conditions. I came to know that the special effects of resins are a major problem to be solved in practical terms. However, the present inventors have been conducting intensive studies to develop a super water-absorbent resin that minimizes the wash-off property in flowing water and has the same performance as conventional resins. A saponified vinyl acetate-maleic acid monoester copolymer with a maleic acid monoester content of 0.2 to 15 mol% and a saponification degree of 70 to 100 mol% is hydrated.
The present inventors have discovered that by applying electron beam or radiation treatment (hereinafter simply referred to as radiation treatment) at 0.1 to 50 Mrads, the washability in flowing water can be dramatically improved, and the present invention has been completed. The first essential requirement of the present invention is that the constituent monomers of the copolymer are vinyl acetate and maleic acid monoester, and the content of maleic acid monoester in the copolymer is preferably 0.2 to 15 mol%. teeth
The saponification degree is selected from a range of 0.5 to 5 mol% and a saponification degree of 70 to 100 mol%. If the type of monomer is another ethylenically unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, or its derivatives, or if the content of maleic acid monoester exceeds 15 mol%, the resulting resin may be exposed to radiation. Even after treatment, the washability in running water is hardly improved. It is surprising that such excellent properties can be obtained by subjecting a limited resin, a saponified vinyl acetate maleate monoester copolymer having a low modification rate, to radiation treatment. Furthermore, even if maleated polyvinyl alcohol, which is obtained by post-reacting polyvinyl alcohol with maleic acid monoester or the like, is subjected to radiation treatment, the effects of the present invention cannot be obtained.
In addition, the content of maleic acid monoester is 0.2 mol%
In other words, the almost future-proof polyvinyl alcohol and the vinyl acetate-maleate monoester copolymer with a degree of saponification of 70 mol% or less treated with radiation have not only better flowability but also water absorption ability compared to the above copolymers. , the water retention capacity is considerably inferior. still,
As the maleic acid monoester, monomethyl maleate and monoethyl maleate are usually used. The second essential requirement is that the saponified vinyl acetate-maleic acid monoester copolymer be prepared in a hydrated state.
It involves applying radiation treatment of 0.1 to 50 Mrads. The water content is usually selected from the range of 1 to 50% by weight. If it is less than 1% by weight, the superabsorbent resin that is the object of the present invention cannot be obtained even if radiation treatment is performed, and if it exceeds 50% by weight, the particles of the saponified copolymer will fuse together and the superabsorbent resin will not be obtained. tends to lose its character. The hydrated state referred to in the present invention may be a mixed liquid of water and alcohol, ester, ketone, etc. The alcohol is not particularly limited as long as it does not dissolve the saponified copolymer, but typical examples include methyl alcohol, ethyl alcohol, isopropyl alcohol, and esters. Examples of ketones include mixtures with methyl acetate, acetone, and the like. However, the moisture content referred to in the present invention is calculated by the following formula. Water content (weight %) = weight of water in saponified copolymer/weight of saponified copolymer x 100 The saponified vinyl acetate-maleic acid monoester copolymer in such a state is subjected to radiation treatment.
The radiation treatment referred to in the present invention refers to electron beams, α-rays, β-rays,
rays, gamma rays, X-rays, and neutral rays, but electron beams and gamma rays are usually preferred due to the stability of the radiation source. The irradiation dose of the radiation must be 0.1 to 50 Mrads, as mentioned above, and 0.1 Mrads.
No effect will be obtained below, and if irradiation exceeds 50 Mrads, water absorption capacity (ratio of weight after water absorption to weight before water absorption)
rapidly decreases and does not function as a super absorbent resin. The saponified vinyl acetate-maleic acid monoester copolymer of the present invention can be produced by any known method, but typically a polymerization initiator such as ditertiary butyl peroxide or benzoyl peroxide peroxide is used. Vinyl acetate and monomethyl maleate are copolymerized at a reaction temperature of 60-75°C in the presence of a persulfate such as ammonium persulfate. The resulting copolymer is saponified by a known method, usually in an organic solvent containing alcohol as a main component, using a suitable alkaline substance such as sodium hydroxide. To bring the saponified copolymer into a hydrated state, heat the resin at a temperature of 30 to 45°C and a relative humidity of 90 to 100% for 20 minutes.
It is enough to absorb moisture for about 50 hours. After adjusting the water content in this way, when the saponified copolymer is irradiated with radiation, there are no particular restrictions, but in order to minimize the irradiation dose as much as possible, a nitrogen atmosphere with an oxygen concentration of 1000 ppm or less is usually used. Do it below. The thus obtained superabsorbent resin of the present invention with improved washout properties can of course be used in conventionally used sanitary products, etc., but its properties are particularly useful when used constantly or temporarily. Places where water flows and where water retention is required at all times, such as water retention agents for cultivating plants in sandy soil, soil for raising seedlings, etc.
It is extremely useful for uses such as horticultural soil. Furthermore, it has excellent performance not only as a powder but also as a molded product such as a filament or a film. Hereinafter, the present invention will be specifically explained with reference to Examples. However, in the examples, "water absorption capacity" and "residual rate" are calculated by the following method. "Water absorption capacity": After immersing the radiation-treated resin sample in ion-exchanged water that is 500 times (by weight) the amount of pure resin overnight, the resulting gel is separated, its weight is measured, and then according to the formula: calculate. Water absorption rate = weight of water-absorbing gel / weight of pure resin in resin sample before immersion ``Residual rate'': Separate the resin that has been exposed to running water for a certain period of time, dry it at 105℃ for 6 hours, and then calculate the weight of the dry resin. Measure and calculate using the following formula. Residual rate (weight%) = weight of water absorbing gel after drying/weight of pure resin component of resin sample before immersion x 100 Example 1 Saponified vinyl acetate-monomethyl maleate copolymer with monomethyl maleate content of 2.1 mol% (particle size 0.84-1.41mm, saponification degree 94.1 mol%) at temperature
It was left at 30°C and 98% relative humidity for 48 hours, resulting in a moisture content of 25.6% by weight. Bulk specific gravity (the resin was placed in a 100ml graduated cylinder and vibrated in the vertical and horizontal directions to make it close packed, and the weight was measured) was 0.434g/
It was hot in ml. 40.6 g of this sample was placed in a polyester film container measuring 13 cm x 24 cm, and the thickness of the sample was approximately 2.9 mm. After replacing the sample atmosphere with nitrogen gas, the sample was irradiated with an electron beam of 5 Mrads using an electron beam irradiation device with an accelerating voltage of 750 KV to obtain a super water absorbent resin with a water absorption capacity of 168.4. The super absorbent resin 1.39 was placed in a nylon taffeta bag and immersed in a beaker filled with water so that the resin would not flow out from the mouth of the bag. Further, water was continued to flow from the top of the bag at a rate of about 1.1/hour to expose the resin to the flowing water. The residual rate of the resin was measured after about 20 hours, 40 hours, 80 hours, and 175 hours. At the same time, the water absorption capacity was also measured, and it was found to be 167.5, with almost no change observed. The measurement results regarding the residual rate are shown in Table 1. Example 2 A saponified vinyl acetate/monomethyl maleate copolymer having a monomethyl maleate content of 3.9 mol% (particle size 0.84 to 0.50 mm, degree of saponification, 98.1 mol%) was prepared according to Example 1 to have a water content of 29.8% by weight. And so. The bulk specific gravity was 0.530 g/ml. Thereafter, electron beam irradiation was performed in the same manner as in Example 1 to obtain a super absorbent resin with a water absorption capacity of 105, and its flowability was measured. Furthermore, when the water absorption capacity was measured after 175 hours, it was only 101 points lower. The results are shown in Table 1. Example 3 A saponified vinyl acetate/monomethyl maleate copolymer (particle size 2.0 to 1.41 mm, degree of saponification 98.0 mol%) with a monomethyl maleate content of 0.5 mol% was prepared in accordance with Example 1 with a water content of 15.2% by weight ( However, when the solvent contained 10% by weight of methyl alcohol, the bulk specific gravity was 0.583 g/ml. Thereafter, electron beam irradiation was performed in the same manner as in Example 1 (however, the irradiation dose was 3 Mrads) to obtain a super absorbent resin with a water absorption capacity of 130.8, and its flowability was measured. or,
When the water absorption capacity was measured after 175 hours, it was 130, which was almost unchanged. The results are shown in Table 1. Example 4 A saponified vinyl acetate/monomethyl maleate copolymer having a monomethyl maleate content of 11.8 mol% (particle size 0.84 to 1.41 mm, degree of saponification 98.5 mol%) was prepared in accordance with Example 1 with a water content of 19.3% by weight. did. The bulk specific gravity was 0.473g/ml. Thereafter, electron beam irradiation was carried out in the same manner as in Example 1 (however, the irradiation dose was 1 Mrads) to obtain a super absorbent resin with a water absorption capacity of 96.2, and its flowability was measured. or,
When the water absorption capacity was measured after 175 hours, it was 96, with almost no change. The results are shown in Table 1.
【表】
(注) 単位はいずれも重量%
比較例 1〜7
第2表に示す如き種類の単量体を酢酸ビニルと
共重合させて樹脂を製造し、それぞれ電子線処理
又は、熱処理等を行つて高吸水性樹脂を得た。
実施例1と同じようにして流亡性及び吸水倍率
を測定した。
第2表に各比較例において使用した酢酸ビニル
以外の単量体の種類、含有量及び得られた樹脂の
粒度・ケン化度・処理前の含水率、カサ比重、及
び処理方法を示した。
又、第3表に各樹脂の流亡性、吸水倍率につい
ての測定結果を示す。[Table] (Note) All units are weight%.
Comparative Examples 1 to 7 Resins were produced by copolymerizing the types of monomers shown in Table 2 with vinyl acetate, and each was subjected to electron beam treatment, heat treatment, etc. to obtain highly water-absorbent resins. The flowability and water absorption capacity were measured in the same manner as in Example 1. Table 2 shows the type and content of monomers other than vinyl acetate used in each comparative example, as well as the particle size, degree of saponification, water content before treatment, bulk specific gravity, and treatment method of the resulting resin. Further, Table 3 shows the measurement results regarding the flowability and water absorption capacity of each resin.
【表】
(注) 比較例1は未変性のポリビニルアルコール
を使用した。
[Table] (Note) In Comparative Example 1, unmodified polyvinyl alcohol was used.
【表】【table】
【表】
(注) 残存率の単位はいずれも重量
%である。
比較例 8
実施例1で使用した共重合体ケン化物の代わり
にポリビニルアルコールにマレイン酸を後反応さ
せたマレイン化ポリビニルアルコール(マレイン
酸含有量3モル%、ケン化度88モル%)を使用し
て以下実施例1と同様にして高吸水性樹脂を得
た。該樹脂を用いて残存率及び吸水倍率の変化を
測定したが、結果は比較例2とほぼ同じであつ
た。[Table] (Note) All residual rates are in weight%.
Comparative Example 8 Instead of the saponified copolymer used in Example 1, maleated polyvinyl alcohol (maleic acid content 3 mol%, degree of saponification 88 mol%), which was obtained by post-reacting polyvinyl alcohol with maleic acid, was used. A super absorbent resin was obtained in the same manner as in Example 1. Changes in residual ratio and water absorption capacity were measured using this resin, and the results were almost the same as in Comparative Example 2.
Claims (1)
ル%でかつケン化度が70〜100モル%の酢酸ビニ
ルーマレイン酸モノエステル共重合体ケン化物に
含水状態で0.1〜50Mradsの電子線又は放射線を
照射することを特徴とする高吸水性樹脂の製造
法。 2 マレイン酸モノエステルがマレイン酸モノメ
チル又はマレイン酸モノエチルである特許請求の
範囲第1項記載の高吸水性樹脂の製造法。[Scope of Claims] 1 A vinyl acetate-maleic acid monoester copolymer saponified product having a maleic acid monoester content of 0.2 to 15 mol% and a saponification degree of 70 to 100 mol% in a hydrated state of 0.1 to 50 Mrads A method for producing a super absorbent resin, which comprises irradiating with an electron beam or radiation. 2. The method for producing a superabsorbent resin according to claim 1, wherein the maleic acid monoester is monomethyl maleate or monoethyl maleate.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP373183A JPS59129232A (en) | 1983-01-12 | 1983-01-12 | Production of highly water-absorptive resin |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP373183A JPS59129232A (en) | 1983-01-12 | 1983-01-12 | Production of highly water-absorptive resin |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS59129232A JPS59129232A (en) | 1984-07-25 |
JPH0261976B2 true JPH0261976B2 (en) | 1990-12-21 |
Family
ID=11565399
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP373183A Granted JPS59129232A (en) | 1983-01-12 | 1983-01-12 | Production of highly water-absorptive resin |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS59129232A (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS6032830A (en) * | 1983-08-01 | 1985-02-20 | Sumitomo Chem Co Ltd | Manufacture of article swelling with water |
WO1994005723A1 (en) * | 1992-08-28 | 1994-03-17 | Nippon Shokubai Co., Ltd. | Water absorptive material, water absorptive article and their production method |
EP0648800A2 (en) * | 1993-10-19 | 1995-04-19 | Nippon Shokubai Co., Ltd. | Method for production of absorbent material and absorbent article |
TWI353360B (en) | 2005-04-07 | 2011-12-01 | Nippon Catalytic Chem Ind | Production process of polyacrylic acid (salt) wate |
EP1757645A1 (en) * | 2005-08-23 | 2007-02-28 | Nippon Shokubai Co.,Ltd. | Disclosure of a method of surface cross-linking highly neutralized superabsorbent polymer particles using Bronstedt acids |
EP1757643A1 (en) * | 2005-08-23 | 2007-02-28 | Nippon Shokubai Co.,Ltd. | Method of surface cross-linking superabsorbent polymer particles using vacuum ultraviolet radiation |
TWI394789B (en) | 2005-12-22 | 2013-05-01 | Nippon Catalytic Chem Ind | Water-absorbent resin composition, method of manufacturing the same, and absorbent article |
EP1837348B9 (en) | 2006-03-24 | 2020-01-08 | Nippon Shokubai Co.,Ltd. | Water-absorbing resin and method for manufacturing the same |
WO2011040472A1 (en) | 2009-09-29 | 2011-04-07 | 株式会社日本触媒 | Particulate water absorbent and process for production thereof |
-
1983
- 1983-01-12 JP JP373183A patent/JPS59129232A/en active Granted
Also Published As
Publication number | Publication date |
---|---|
JPS59129232A (en) | 1984-07-25 |
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