JP2005082622A - Method for producing raw rubber having small gel content - Google Patents
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本発明はゲル分の含有量が少ない生ゴムの製造方法に関する。 The present invention relates to a method for producing raw rubber having a low gel content.
生ゴムは、天然ゴムラテックスから調製される固形の天然ゴム原料であって、加硫を施すことによって優れた機械的特性が発揮されることから、各種ゴム製品の製造に用いられている。
ゴム製品の製造上、生ゴムには、混練、シーティング、各種成形工程等での加工性に優れていることが要求されており、かかる加工性の良否は、生ゴム中にゲル分が存在することによって大きく影響されることが知られている。そこで、生ゴム中のゲル分を低減させることが検討されているが、天然状態のゴムラテックスに含まれるゲル分の量を調節することは現実的ではない。なお、ゲル分とは、溶剤に対する難溶性部分のことであって、天然ゴムラテックスが蛋白質、脂質等の不純物を多く含んでいることに起因するものと考えられている。
Raw rubber is a solid natural rubber raw material prepared from natural rubber latex, and exhibits excellent mechanical properties when vulcanized. Therefore, raw rubber is used in the production of various rubber products.
In the production of rubber products, raw rubber is required to have excellent processability in kneading, sheeting, various molding processes, etc., and the quality of such processability is due to the presence of a gel component in the raw rubber. It is known to be greatly affected. Therefore, it has been studied to reduce the gel content in the raw rubber, but it is not realistic to adjust the amount of the gel content contained in the natural rubber latex. The gel content is a hardly soluble part in the solvent, and is considered to be caused by the natural rubber latex containing a large amount of impurities such as proteins and lipids.
ところで、生ゴムをゴム製品の製造原料として供給する際には、分子量を低下させて加工性を向上させるために、練りロール機や密閉式混合機で素練り処理を施しているが、生ゴムにゲル分が含まれていると、見かけの分子量が高くなることから、素練りが過剰に施されることとなる。しかも、素練り処理は、ゲル分の発生原因となるゴム分子の分岐部分を切断するよりも、ゴム分子の主鎖をランダムに切断することが多いことから、過剰な素練り処理によって、分子量が高く、主鎖骨格の立体構造が均一（概ね１００％がｃｉｓ−１，４−ポリイソプレン）であるという天然ゴム本来の特徴を十分に生かすことができなくなってしまう。 By the way, when raw rubber is supplied as a raw material for producing rubber products, in order to reduce the molecular weight and improve processability, the raw rubber is subjected to mastication treatment with a kneading roll machine or a closed mixer. If the content is contained, the apparent molecular weight becomes high, so that the kneading is applied excessively. In addition, since the mastication treatment often cuts the main chain of the rubber molecule at random rather than the branched portion of the rubber molecule that causes the gel content, the molecular weight is increased by excessive mastication treatment. The main structure of the natural rubber, which is high and the steric structure of the main chain skeleton is uniform (approximately 100% is cis-1,4-polyisoprene), cannot be fully utilized.
また、生ゴムは、各種改質ゴムの製造原料としても用いられているが、ゲル分を多く含む生ゴムは改質剤との反応効率が低く、改質処理の効果が十分に現れにくいという問題もある。
天然ゴム（生ゴム）中でのゲル分含有率が高くなる原因の一つとして、前述のように、天然ゴム中に蛋白質が含まれることが挙げられている。この蛋白質については、従来、即時型アレルギーを誘発する原因物質であるとしてその除去が求められており、それゆえ、主としてアレルギーの防止を目的として蛋白質を分解除去する処理が広く行われている（特許文献１，２）。
Raw rubber is also used as a raw material for producing various modified rubbers. However, raw rubber containing a large amount of gel has a low reaction efficiency with the modifier, and there is a problem that the effect of the modification treatment is not sufficiently exhibited. is there.
One of the causes for the high gel content in natural rubber (raw rubber) is that protein is contained in natural rubber as described above. Conventionally, removal of this protein has been required as a causative substance that induces immediate allergy, and therefore, treatment for decomposing and removing the protein has been widely performed mainly for the purpose of preventing allergy (patents). References 1, 2).
しかしながら、天然に含まれる蛋白質を分解除去した、いわゆる脱蛋白天然ゴムは、そのゲル量が通常の天然ゴムより少なくなっているものの、０にはならない。しかも、脱蛋白天然ゴムは、天然ゴムラテックスに含まれる蛋白質を分解する処理（蛋白分解処理）を行った後、分解蛋白質等を除去するために遠心分離等による洗浄処理（脱蛋白処理）が施されることから、工程数が多く、しかも歩留まりの低下を余儀なくされる。それゆえ、通常の天然ゴムに比べて、生産コストが高くなるという問題がある。
本発明の目的は、簡易な方法でかつ低コストで、ゲル分の含有量を低減させることのできる生ゴムの製造方法を提供することである。 The objective of this invention is providing the manufacturing method of the raw rubber which can reduce content of a gel part by a simple method and low cost.
上記目的を達成するための本発明に係るゲル分含有量の少ない生ゴムの製造方法は、天然ゴムラテックスに蛋白分解酵素と界面活性剤とを加えて熟成させた後、ゴム分を凝固させて固形化することを特徴とする。
前述のように、通常、蛋白分解酵素を用いた脱蛋白天然ゴムの製造工程では、天然ゴムラテックスに蛋白分解酵素と界面活性剤とを添加して蛋白質の分解処理を行った後、分解蛋白質を除去するために遠心分離による洗浄処理（脱蛋白処理）を施している。しかしながら、本発明は天然ゴムのアレルギー性を低減することを目的としているのではなく、蛋白分解酵素による蛋白質の分解処理によって天然ゴムの蛋白質による分岐を切断し、ゲル分の生成を阻害することを目的としている。従って、天然ゴムラテックスに蛋白分解酵素と界面活性剤とを加えて熟成させて、天然ゴムの蛋白質による分岐を切断した後に、そのままの状態でゴム分を凝固させて固形化させている。それゆえ、本発明の製造方法によれば、簡易な方法でかつ低コストで、ゲル分の含有量を低減させた生ゴムを製造することができる。
In order to achieve the above object, a method for producing a raw rubber with a low gel content according to the present invention comprises aging a natural rubber latex by adding a proteolytic enzyme and a surfactant, and then coagulating the rubber to obtain a solid. It is characterized by becoming.
As described above, in the process of producing a deproteinized natural rubber using a proteolytic enzyme, a proteolytic enzyme and a surfactant are usually added to natural rubber latex to decompose the protein, In order to remove it, washing treatment (deproteinization treatment) by centrifugation is performed. However, the present invention is not intended to reduce the allergenicity of natural rubber, but to cleave branches due to the protein of natural rubber by protein degradation treatment with proteolytic enzymes to inhibit the generation of gel content. It is aimed. Therefore, after a proteolytic enzyme and a surfactant are added to natural rubber latex and ripened to cut off the branch of the natural rubber due to protein, the rubber is coagulated and solidified as it is. Therefore, according to the production method of the present invention, it is possible to produce a raw rubber with a reduced gel content by a simple method and at a low cost.
なお、本出願人は、先に、天然ゴムラテックス中にリン酸アンモニウム等のリン酸塩を添加して、ゲル化の原因となるマグネシウムを除去するとともに、ラテックスの採取から１０日以内に固形化もしくは脱蛋白処理を行うことによって、ゲル量が１０％以下である生ゴムを製造する方法を提案している（特願２００３−４１５９５号）。しかしながら、本発明に係るゲル分含有量の少ない生ゴムの製造方法では、リン酸塩を添加し、沈殿生成物を除去するという余分の工程を必要とすることから、生産コストの観点から好ましくない。 The applicant first added phosphate such as ammonium phosphate to natural rubber latex to remove magnesium that causes gelation, and solidified within 10 days from the collection of latex. Alternatively, a method for producing a raw rubber having a gel amount of 10% or less by deproteinization is proposed (Japanese Patent Application No. 2003-41595). However, the method for producing raw rubber with a low gel content according to the present invention is not preferable from the viewpoint of production cost because it requires an extra step of adding phosphate and removing the precipitated product.
一方、特許文献３には、末端に蛋白質を有する固形天然ゴムに蛋白分解酵素を添加して、固定状態で末端蛋白質を分解させる天然ゴムの製造方法が記載されている。しかしながら、同文献に記載の方法では、混練りで酵素を入れるために、蛋白質を分解する効率が本発明の方法に比べて低い。しかも、素練りの工程を含むことから、ゴム分子の主鎖が切断されることによって天然ゴム本来の利点が損なわれてしまう。 On the other hand, Patent Document 3 describes a method for producing natural rubber in which a proteolytic enzyme is added to a solid natural rubber having a protein at the terminal to decompose the terminal protein in a fixed state. However, in the method described in this document, since the enzyme is added by kneading, the efficiency of degrading the protein is lower than that of the method of the present invention. In addition, since the process of mastication is included, the main advantage of natural rubber is lost by cutting the main chain of the rubber molecule.
本発明において、生ゴム中のゲル分含有量とは、生ゴムを非極性溶媒であるトルエンに溶解させた時の不溶分の量を意味するものである。以下、生ゴム中のゲル分の含有割合を単に「ゲル分含有率」と称することがある。
本発明の製造方法によって得られた生ゴムは、そのゲル分含有率がトルエン不溶分の含有割合として２０重量％以下にまで低減されることから、ゴム製品に加工するのに際して素練りを必要とせず、加工性が極めて良好で、しかも改質ゴム製造時の反応性にも優れている。
In the present invention, the gel content in raw rubber means the amount of insoluble matter when raw rubber is dissolved in toluene, which is a nonpolar solvent. Hereinafter, the content ratio of the gel in the raw rubber may be simply referred to as “gel content”.
The raw rubber obtained by the production method of the present invention has a gel content reduced to 20% by weight or less as a toluene-insoluble content, and therefore does not require mastication when processed into a rubber product. The processability is extremely good, and the reactivity when producing the modified rubber is also excellent.
本発明において、生ゴムとは、例えばスモークド・シート（ＲＳＳ）、ペールグレープ、ブラウンクレープ等のほか、ラテックスにヒマシ油、プロセスオイル、塩酸ホドロキシルアミン（または水化ヒドラジン）をそれぞれ添加して作製されるヘベアクラム、油天然ゴム粘度安定化ゴム等を包含するものである。
天然ゴムラテックスはヘビア樹の樹液として採取され、ゴム分のほか水、蛋白質、脂質、無機塩類等を含み、ゴム中のゲル分は種々の不純物の複合的な存在に基づくものと考えられている。本発明では、ヘビア樹をタッピングして出てくる生ラテックス、あるいは遠心分離法によって濃縮した精製ラテックスが用いられる。さらに、生ゴムラテックス中に存在するバクテリヤによる腐敗の進行を防止し、ラテックスの凝固を避けるために、常法どおりにアンモニアを添加したハイアンモニアラテックスであってもよい。本発明の製造方法に用いられるゴムラテックスは、採取してから１０日以内のものであるのが好ましい。
In the present invention, raw rubber is prepared by adding castor oil, process oil, and hydroxylamine hydrochloride (or hydrated hydrazine) to latex in addition to smoked sheet (RSS), pale grape, brown crepe, and the like. Hebe akram, oil natural rubber viscosity stabilized rubber and the like.
Natural rubber latex is collected as sap of heavy trees and contains rubber, water, proteins, lipids, inorganic salts, etc., and the gel content in rubber is thought to be based on the complex presence of various impurities. . In the present invention, raw latex produced by tapping a heavy tree or purified latex concentrated by centrifugation is used. Furthermore, high ammonia latex to which ammonia is added in a usual manner may be used in order to prevent the progress of decay by bacteria present in the raw rubber latex and to avoid coagulation of the latex. The rubber latex used in the production method of the present invention is preferably within 10 days after collection.
本発明に係る生ゴムの製造方法においては、天然ゴムラテックスに蛋白分解酵素と界面活性剤とを加えた上で、これを熟成させる、いわゆる蛋白分解処理が施される。
蛋白分解酵素には従来公知の種々のものが使用可能であって、特に限定されるものではないが、例えばアルカリプロテアーゼ等が好適に用いられる。プロテアーゼの由来としては、細菌由来のもの、糸状菌由来のもの、酵母由来のもの等のいずれであってもよいが、これらの中では細菌由来のものを使用するのが好ましい。また、リパーゼ、エステラーゼ、アミラーゼ、ラッカーゼ、セルラーゼ等の酵素を併用してもよい。
In the raw rubber production method according to the present invention, a so-called proteolytic treatment is performed, in which a proteolytic enzyme and a surfactant are added to natural rubber latex, followed by aging.
Various conventionally known proteolytic enzymes can be used, and are not particularly limited. For example, alkaline protease is preferably used. Protease may be derived from bacteria, filamentous fungi, yeast or the like. Among these, it is preferable to use bacteria. In addition, enzymes such as lipase, esterase, amylase, laccase and cellulase may be used in combination.
蛋白分解酵素としてアルカリプロテアーゼを用いる場合、その活性は０．１〜５０ＡＰＵ／ｇ、好ましくは１〜２５ＡＰＵ／ｇの範囲であるのが適当である。この酵素活性は、アンソン−ヘモグロビン法［Anson. M. L., J. Gen. Physiol., 22, 79(1938)］の改良法を用いて測定することができる。すなわち、基質として用いる尿素変性ヘモグロビンの終濃度が１４．７ｍｇ／ｍｌとなるように調整した溶液中で、温度２５℃、ｐＨ１０．５にて１０分間反応させた後、反応溶液にトリクロロ酢酸を終濃度が３１．２５ｍｇ／ｍｌとなるように添加する。次いで、トリクロロ酢酸の可溶分をフェノール試薬によって呈色させ、１モルのチロシンの呈色度を１ＡＰＵとした検量線により反応１０分間当りの活性を求め、これを１分間当りに換算することによって測定した。なお、１ＡＰＵとは、１モルのチロシンがフェノール試薬によって呈色するのと同じ呈色度のトリクロロ酢酸可溶分量を１分間に与えるプロテアーゼの量のことを示す。但し、アルカリプロテアーゼの活性測定はこの測定方法に限定されるものではない。 When alkaline protease is used as the proteolytic enzyme, the activity is suitably in the range of 0.1 to 50 APU / g, preferably 1 to 25 APU / g. This enzyme activity can be measured using an improved method of the Anson-hemoglobin method [Anson. M. L., J. Gen. Physiol., 22, 79 (1938)]. That is, after reacting at a temperature of 25 ° C. and a pH of 10.5 for 10 minutes in a solution adjusted so that the final concentration of urea-modified hemoglobin used as a substrate is 14.7 mg / ml, trichloroacetic acid is terminated in the reaction solution. Add to a concentration of 31.25 mg / ml. Next, the soluble content of trichloroacetic acid is colored with a phenol reagent, and the activity per 10 minutes of reaction is obtained by a calibration curve with the coloration degree of 1 mol of tyrosine as 1 APU, and this is converted per 1 minute. It was measured. In addition, 1 APU indicates the amount of protease that gives a soluble amount of trichloroacetic acid having the same coloration degree as 1 mol of tyrosine is colored by a phenol reagent in one minute. However, alkaline protease activity measurement is not limited to this measurement method.
蛋白分解酵素の添加量は、酵素活性に応じて適宜設定されるものであるが、通常天然ゴムラテックスの固形分１００重量部に対して０．０００１〜２０重量部、好ましくは０．００１〜１０重量部の範囲で設定される。蛋白分解酵素の添加量が前記範囲を下回ると、ラテックス中の蛋白質を充分に分解することができなくなるおそれがある。一方、蛋白分解酵素の添加量が前記範囲を超えると、酵素の活性が低下し、かつコストアップにつながるおそれがある。また、酵素を添加する際にｐＨ調整剤等の他の添加剤を添加してもよい。 The amount of proteolytic enzyme added is appropriately set according to the enzyme activity, but is usually 0.0001-20 parts by weight, preferably 0.001-10 parts per 100 parts by weight of the solid content of the natural rubber latex. It is set in the range of parts by weight. When the amount of the protease added is less than the above range, there is a possibility that the protein in the latex cannot be sufficiently degraded. On the other hand, if the amount of the proteolytic enzyme exceeds the above range, the enzyme activity may be reduced and the cost may be increased. Moreover, when adding an enzyme, you may add other additives, such as a pH adjuster.
蛋白質分解処理の処理時間も酵素活性に応じて適宜設定されるものであって、特に限定されないが、通常数分から１週間程度行うことが好ましい。蛋白質分解処理中、ラテックスは攪拌していてもよく、静置していてもよい。温度調節は必要に応じてすればよいが、処理に適当な温度としては５〜９０℃、好ましくは２０〜６０℃である。処理温度が９０℃を超えると酵素の失活が早く、５℃未満であれば酵素の反応が進行しにくくなる。 The processing time for the proteolytic treatment is also appropriately set according to the enzyme activity, and is not particularly limited, but it is usually preferable to carry out the treatment for several minutes to one week. During the proteolytic treatment, the latex may be stirred or allowed to stand. The temperature may be adjusted as necessary, but the temperature suitable for the treatment is 5 to 90 ° C, preferably 20 to 60 ° C. If the treatment temperature exceeds 90 ° C, the enzyme is rapidly deactivated, and if the treatment temperature is less than 5 ° C, the reaction of the enzyme is difficult to proceed.
蛋白分解処理時に配合される界面活性剤としては、(a) 陰イオン性界面活性剤、(b) 非イオン性界面活性剤および(c) 両性イオン界面活性剤が使用可能である。これらは１種のみを用いてもよく、２種以上を混合して用いてもよい。(a) の陰イオン界面活性剤には、例えばカルボン酸系、スルホン酸系、硫酸エステル系、リン酸エステル系等の界面活性剤が挙げられる。(b) の非イオン界面活性剤には、例えばポリオキシアルキレンエ−テル系、ポリオキシアルキレンエステル系、多価アルコ−ル脂肪酸エステル系、糖脂肪酸エステル系、アルキルポリグリコシド系等の界面活性剤が挙げられる。(c) の両性イオン界面活性剤には、例えばアミノ酸型、ベタイン型、アミンオキサイド型等が挙げられる。 As the surfactant to be incorporated during the proteolytic treatment, (a) anionic surfactant, (b) nonionic surfactant and (c) zwitterionic surfactant can be used. These may use only 1 type and may mix and use 2 or more types. Examples of the anionic surfactant (a) include carboxylic acid-based, sulfonic acid-based, sulfate ester-based and phosphate ester-based surfactants. Examples of the nonionic surfactant (b) include polyoxyalkylene ether-based, polyoxyalkylene ester-based, polyhydric alcohol fatty acid ester-based, sugar fatty acid ester-based, alkyl polyglycoside-based surfactants and the like. Is mentioned. Examples of the zwitterionic surfactant (c) include amino acid type, betaine type, and amine oxide type.
上記例示の蛋白分解酵素や界面活性剤を用いるのにあたって、他の添加剤、例えばｐＨ調整剤、分散剤等を添加してもよい。ｐＨ調整剤としては、例えばリン酸二水素カリウム、リン酸水素二カリウム、リン酸二水素ナトリウム、リン酸水素二ナトリウム等のリン酸塩、酢酸カリウム、酢酸ナトリウム等の酢酸塩や、硫酸、酢酸、塩酸、硝酸、クエン酸、コハク酸等の酸類またはその塩、アンモニア、水酸化カリウム、水酸化ナトリウム、炭酸ナトリウム、炭酸水素ナトリウム等が挙げられる。ｐＨ調整剤の添加量は、ラテックスのゴム固形分１００重量部に対して、通常、０．０１〜０．５重量部である。分散剤としては、例えばスチレンスルホン酸共重合物、ナフタレンスルホン酸ホルマリン縮合物、リグニンスルホン酸、多環型芳香族スルホン酸共重合物、アクリル酸および無水マレイン酸のホモポリマーおよび共重合物、イソブチレン−アクリル酸およびイソブチレン−無水マレイン酸共重合物等が挙げられる。 In using the above-mentioned proteolytic enzymes and surfactants, other additives such as a pH adjusting agent and a dispersing agent may be added. Examples of the pH adjuster include phosphates such as potassium dihydrogen phosphate, dipotassium hydrogen phosphate, sodium dihydrogen phosphate and disodium hydrogen phosphate, acetates such as potassium acetate and sodium acetate, sulfuric acid, acetic acid And acids such as hydrochloric acid, nitric acid, citric acid and succinic acid or salts thereof, ammonia, potassium hydroxide, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate and the like. The addition amount of the pH adjuster is usually 0.01 to 0.5 parts by weight with respect to 100 parts by weight of the rubber solid content of the latex. Examples of the dispersant include styrene sulfonic acid copolymer, naphthalene sulfonic acid formalin condensate, lignin sulfonic acid, polycyclic aromatic sulfonic acid copolymer, homopolymer and copolymer of acrylic acid and maleic anhydride, isobutylene. -Acrylic acid and isobutylene-maleic anhydride copolymer etc. are mentioned.
本発明に係る生ゴムの製造方法においては、天然ゴムラテックスに蛋白分解処理を施した後、ゴム分を凝固させて固形化する処理が施される。
天然ゴムラテックスの固形化は、前述の各種生ゴムの製造方法に準ずる凝固工程および乾燥工程を経るものであって、目的に応じて、圧延、水洗等の工程を含むものである。
例えば、スモークド・シート（ＲＳＳ）の製造方法に準じて固形化を行う場合には、まず、蛋白質の分解処理が施されたゴムラテックスを凝固槽に入れ、必要に応じて水を入れてゴム固形分の濃度を約２０重量％に調整した後、凝固薬品として主に酢酸またはギ酸を加える。生成する凝固物を二本ロールに通しながら、上から水を注いで漿液をしぼり、水洗しながら一定の厚みになったところで、型付ロールにかける。次いで、煙室に吊るして煙で燻しながら乾燥させることによって生ゴムが得られる。乾燥室内の温度は４５〜６０℃程度とする。なお、スモーキングすることなく、ＡＤＳ（Air Dried Sheet）として得てもよい。ペールクレープの製造方法に準じて固形化を行う場合には、凝固剤を添加する前に腐敗防止と純白化のために重亜硫酸ナトリウムを加える。乾燥処理は、自然通風または熱風を強制通風するトンネル式乾燥方法とし、クレープ状にロールに押し出すことによって生ゴムが得られる。
In the raw rubber production method according to the present invention, after subjecting natural rubber latex to proteolytic treatment, the rubber component is solidified by solidification.
The solidification of the natural rubber latex goes through a coagulation step and a drying step according to the above-described methods for producing various raw rubbers, and includes steps such as rolling and washing according to the purpose.
For example, when solidification is performed in accordance with the method for producing smoked sheet (RSS), first, rubber latex that has been subjected to protein decomposition treatment is placed in a coagulation tank, and water is added as necessary to solidify the rubber. After adjusting the concentration of the minute to about 20% by weight, mainly acetic acid or formic acid is added as a coagulation chemical. While passing the produced coagulated product through two rolls, water is poured from above to squeeze the serum, and when it reaches a certain thickness while being washed with water, it is put on a mold roll. Subsequently, the raw rubber is obtained by suspending in a smoke chamber and drying it with smoke. The temperature in the drying chamber is about 45 to 60 ° C. In addition, you may obtain as ADS (Air Dried Sheet), without smoking. When solidification is performed according to the method for producing a pale crepe, sodium bisulfite is added to prevent spoilage and pure whitening before adding the coagulant. The drying treatment is a tunnel-type drying method in which natural ventilation or hot air is forcibly ventilated, and raw rubber is obtained by extruding into a roll in a crepe shape.
＜生ゴムの製造＞
（実施例１）
天然ゴムのフィールドラテックス約１６７重量部（ゴム固形分１００重量部）に対して、プロテアーゼ（蛋白分解酵素）０．０６７重量部と、１０％ポリオキシエチレンラウリルエーテル硫酸ナトリウム〔界面活性剤、花王（株）製の「ＫＰ４４０１」〕１．５重量部とを添加し、水で希釈して、ゴム固形分が３０重量％の天然ゴムラテックスを調製した。次いで、上記ラテックスを室温で１６時間撹拌しながら熟成し、蛋白質の分解処理を行った。
<Manufacture of raw rubber>
(Example 1)
About 167 parts by weight of natural rubber field latex (100 parts by weight of rubber solid content), 0.067 parts by weight of protease (proteolytic enzyme), 10% sodium polyoxyethylene lauryl ether sulfate [surfactant, Kao ( "KP4401" manufactured by K.K.) 1.5 parts by weight was added and diluted with water to prepare a natural rubber latex having a rubber solid content of 30% by weight. Next, the latex was aged with stirring at room temperature for 16 hours to perform protein degradation treatment.
こうして蛋白分解処理が施された天然ゴムラテックスを固形分濃度約１５重量％までイオン交換水で希釈し、これに２〜２０重量％の蟻酸を添加してゴム分を凝固させた。この凝固したゴムをロールに通しながら漿液を絞り、シート状にした。これを４５℃のオーブンで乾燥して固形天然ゴム（生ゴム）を得た。上記の工程において、ゴムラテックス採取後から脱蛋白処理し、固形化するまでの日数は２日間とした。 The natural rubber latex thus proteolyzed was diluted with ion-exchanged water to a solid concentration of about 15% by weight, and 2 to 20% by weight of formic acid was added thereto to coagulate the rubber. The serum was squeezed into a sheet by passing the solidified rubber through a roll. This was dried in an oven at 45 ° C. to obtain solid natural rubber (raw rubber). In the above process, the number of days from collection of rubber latex to deproteinization and solidification was 2 days.
（比較例１）
天然ゴムのフィールドラテックスを、固形分濃度が約１５重量％になるまでイオン交換水で希釈して、これに２〜２０重量％の蟻酸を添加してゴム分を凝固させた。この凝固したゴムをロールに通しながら漿液を絞り、シート状にした。これを４５℃のオーブンで乾燥して固形天然ゴム（生ゴム）を得た。上記の工程において、ゴムラテックス採取後から脱蛋白処理し、固形化するまでの日数は２日間とした。
(Comparative Example 1)
Natural rubber field latex was diluted with ion-exchanged water until the solid content was about 15% by weight, and 2 to 20% by weight of formic acid was added thereto to coagulate the rubber. The serum was squeezed into a sheet by passing the solidified rubber through a roll. This was dried in an oven at 45 ° C. to obtain solid natural rubber (raw rubber). In the above process, the number of days from collection of rubber latex to deproteinization and solidification was 2 days.
（比較例２）
天然ゴムのフィールドラテックス約１６７重量部（ゴム固形分１００重量部）に対して、プロテアーゼ（蛋白分解酵素）０．０６７重量部と、１０％ポリオキシエチレンラウリルエーテル硫酸ナトリウム〔界面活性剤、花王（株）製の「ＫＰ４４０１」〕１．５重量部とを添加し、水で希釈して、ゴム固形分が３０重量％の天然ゴムラテックスを調製した。次いで、上記ラテックスを室温で１６時間撹拌しながら熟成し、蛋白質の分解処理を行った。
(Comparative Example 2)
About 167 parts by weight of natural rubber field latex (100 parts by weight of rubber solid content), 0.067 parts by weight of protease (proteolytic enzyme), 10% sodium polyoxyethylene lauryl ether sulfate [surfactant, Kao ( "KP4401" manufactured by K.K.) 1.5 parts by weight was added and diluted with water to prepare a natural rubber latex having a rubber solid content of 30% by weight. Next, the latex was aged with stirring at room temperature for 16 hours to perform protein degradation treatment.
こうして蛋白分解処理が施された天然ゴムラテックス約３３３重量部（ゴム固形分１００重量部）を水で希釈し、全量を１０００重量部（ゴム固形分約１０重量％）に調整した後、１００００ｒｐｍ（重力加速度約９０００Ｇ）で３０分間遠心分離を行った。遠心分離処理後、上層に分離したクリーム状のゴム分を取り出し、さらに水で希釈することにより、ゴム固形分６０％の脱蛋白処理された天然ゴムラテックスを得た。 After diluting about 333 parts by weight of natural rubber latex (100 parts by weight of rubber solids) with water to adjust the total amount to 1000 parts by weight (about 10% by weight of rubber solids), 10000 rpm ( Centrifugation was performed at a gravitational acceleration of approximately 9000 G) for 30 minutes. After the centrifugal separation treatment, the creamy rubber component separated into the upper layer was taken out, and further diluted with water to obtain a deproteinized natural rubber latex having a rubber solid content of 60%.
次に、上記の脱蛋白天然ゴムラテックスを、固形分濃度が約１５重量％になるまでイオン交換水で希釈し、これに２〜２０重量％の蟻酸を添加してゴム分を凝固させた。この凝固したゴムをロールに通しながら漿液を絞り、シート状にした。これを４５℃のオーブンで乾燥して固形天然ゴム（生ゴム）を得た。上記の工程において、ゴムラテックス採取後から脱蛋白処理し、固形化するまでの日数は２日間とした。 Next, the deproteinized natural rubber latex was diluted with ion-exchanged water until the solid content was about 15% by weight, and 2 to 20% by weight of formic acid was added thereto to coagulate the rubber. The serum was squeezed into a sheet by passing the solidified rubber through a roll. This was dried in an oven at 45 ° C. to obtain solid natural rubber (raw rubber). In the above process, the number of days from collection of rubber latex to deproteinization and solidification was 2 days.
＜ゲル分含有率の測定＞
本発明において、生ゴム中の「ゲル分の含有率」とは、トルエン不溶分として測定した値を意味する。ゲル分含有率の測定には、実施例および比較例で得られた生ゴムを、それぞれ１ｍｍ×１ｍｍの大きさに切断してサンプルとした。次いで、このサンプルを７０．００ｍｇ量り取って、これに３５ｍＬのトルエンを加えて冷暗所にて１週間静置した。静置後、遠心分離処理を施してトルエンに不溶のゲル分を沈殿させ、上澄みのトルエン可溶分を除去した。さらに、沈殿したゲル分のみをメタノールで固めた後、乾燥させて重量を測定して、測定されたゲル分の乾燥重量（ｍｇ）と、最初のサンプル重量（＝７０.００ｍｇ）とから、次式によりゲル分含有率（％）を算出した。
<Measurement of gel content>
In the present invention, the “gel content” in the raw rubber means a value measured as a toluene insoluble matter. For the measurement of the gel content, the raw rubbers obtained in the examples and comparative examples were cut into 1 mm × 1 mm sizes as samples. Next, 70.00 mg of this sample was weighed, 35 mL of toluene was added thereto, and the mixture was allowed to stand in a cool dark place for 1 week. After standing, a centrifugal separation treatment was performed to precipitate a gel component insoluble in toluene, and the toluene-soluble component in the supernatant was removed. Furthermore, after solidifying only the precipitated gel with methanol, it was dried and weighed. From the measured dry weight (mg) of the gel and the initial sample weight (= 70.00 mg), The gel content (%) was calculated from the formula.
ゲル分含有率＝［（ゲル分の乾燥重量）／（最初のサンプル重量）］×１００
なお、ゲル分含有率の測定は、固形ゴムの製造直後に行った。
ゲル分含有率の測定結果を、天然ゴムラテックスに対する蛋白分解酵素による処理（酵素処理）の有無、界面活性剤の添加の有無、および酵素処理後の遠心分離処理（脱蛋白処理）の有無と併せて、表１に示す。
Gel content rate = [(dry weight of gel) / (initial sample weight)] × 100
The gel content was measured immediately after the production of the solid rubber.
Measurement results of gel content are combined with the presence or absence of proteolytic enzyme treatment (enzyme treatment) on natural rubber latex, the presence or absence of addition of surfactant, and the presence or absence of centrifugation treatment (deproteinization treatment) after enzyme treatment. Table 1 shows.
これに対し、天然ゴムラテックスに蛋白分解酵素と界面活性剤を加えて蛋白分解処理を施した後、そのままの状態で固形ゴムを作製した実施例１では、ゲル分含有率を大幅に低下させることができた。
On the other hand, in Example 1 in which solid rubber was produced as it was after adding proteolytic enzyme and surfactant to natural rubber latex to produce a proteolytic treatment, the gel content was greatly reduced. I was able to.
また、実施例１でのゲル分含有率は、蛋白分解処理後に、遠心分離処理による（分解）蛋白質の除去処理（脱蛋白処理）を施した比較例２と同程度であった。従って、遠心分離処理（脱蛋白処理）によって（分解）蛋白質を除去する工程を経なくても、ゲル分含有量の少ない天然ゴムが得られることが確認された。
本発明は、以上の記載に限定されるものではなく、特許請求の範囲に記載した事項の範囲において、種々の設計変更を施すことが可能である。
Further, the gel content in Example 1 was almost the same as that of Comparative Example 2 in which (degradation) protein removal treatment (deproteinization treatment) was performed by centrifugation after the proteolysis treatment. Therefore, it was confirmed that natural rubber having a low gel content can be obtained without going through the step of removing (degraded) protein by centrifugation (deproteinization).
The present invention is not limited to the above description, and various design changes can be made within the scope of the matters described in the claims.
Claims (2)
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