JP5435080B2 - How to prevent scale - Google Patents
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本発明は、懸濁物質が存在する水系におけるスケールの防止方法に関する。詳しくは、製紙工場のパルプ蒸解工程、漂白工程、古紙脱墨工程又はこれらに付随する水洗工程、或いは無機懸濁物質が共存する鉄鋼集塵水系などにおいて、配管や機壁等へのカルシウムスケールの付着を効果的に抑制するスケールの防止方法に関する。 The present invention relates to a method for preventing scale in an aqueous system in which suspended substances are present. Specifically, in the pulp milling process, bleaching process, waste paper deinking process or water washing process accompanying these, or in steel dust collection water systems where inorganic suspended substances coexist, etc. The present invention relates to a scale prevention method that effectively suppresses adhesion.
従来、スケール生成傾向を示す工業用水系において、炭酸カルシウムや硫酸カルシウムなどのカルシウムスケールの発生防止に、ホスホン酸やホスホン酸塩（以下「ホスホン酸（塩）」と記載する場合がある。）類及び各種の低分子水溶性ポリマーが有効であることは公知であり、種々の提案がなされている（例えば、特開昭５０−９１５７０号公報、特公昭６０−１７８２８号公報等）。また、ホスホン酸（塩）と低分子水溶性ポリマーを併用してスケール防止をする方法も公知である（例えば、特公昭５７−１３３５８号公報、特公昭６１−５２７６０号公報等）。 Conventionally, phosphonic acids and phosphonates (hereinafter sometimes referred to as “phosphonic acids (salts)”) are used to prevent the generation of calcium scales such as calcium carbonate and calcium sulfate in industrial water systems showing a tendency to produce scales. In addition, it is known that various low-molecular water-soluble polymers are effective, and various proposals have been made (for example, JP-A-50-91570, JP-B-60-17828, etc.). In addition, a method for preventing scale by using a phosphonic acid (salt) and a low-molecular water-soluble polymer in combination is also known (for example, JP-B-57-13358, JP-B-61-52760, etc.).
これらホスホン酸（塩）やポリマーを水系に含有させる濃度は、スケールを形成する陽イオンと化学量論的に結合するに要する量よりも明らかに低い濃度（この濃度は、「しきい値」量 (“threshold”amountと称されている。）に保たれるのが一般的である。 The concentration of these phosphonic acids (salts) and polymers in the water system is clearly lower than the amount required to stoichiometrically combine with the cations that form the scale (this concentration is the “threshold” amount). (Called “threshold” amount).
一方、ホスホン酸（塩）や水溶性ポリマーにはその種類によって、スケール防止効果を発揮できる水質に制限があることが判明しており、水中の溶存成分とその濃度から求めたスケール化傾向の強さによって適用するホスホン酸（塩）の種類を選択することができる。 On the other hand, phosphonic acid (salts) and water-soluble polymers have been found to have limited water quality depending on their types, and they have a strong tendency to scale based on dissolved components in water and their concentrations. The type of phosphonic acid (salt) to be applied can be selected.
ホスホン酸（塩）や水溶性ポリマーを用いるスケール防止技術は、ボイラ水系や冷却水系のように懸濁物質を含まないか、含んでいても極めて低濃度の水系においては有効であり、このような水系において広く適用されている。 Scaling prevention technology using phosphonic acid (salt) and water-soluble polymer is effective in water systems with very low concentration even if it does not contain suspended substances like boiler water systems and cooling water systems. Widely applied in water systems.
しかし、水系に炭酸カルシウムや硫酸カルシウム、その他の無機懸濁物質を含有する水系に、上記技術をそのまま流用した場合、ホスホン酸（塩）は、水質から求めた適用範囲内にあるにも拘わらず「しきい値」量の添加濃度ではスケール防止効果が得られず、高濃度で添加しないと効果が得られないという問題があった。 However, when the above technique is applied to an aqueous system containing calcium carbonate, calcium sulfate, or other inorganic suspended solids in the aqueous system, the phosphonic acid (salt) is in the application range determined from the water quality. There was a problem that the effect of preventing scale could not be obtained with an addition concentration of “threshold” amount, and the effect could not be obtained unless added at a high concentration.
上記公知例においても、無機懸濁物質を含有する水系におけるカルシウムスケールの防止についての記載はなく、またこれを示唆する記載もなく、無機懸濁物質が存在する水系における安定したカルシウムスケールの防止方法の開発が望まれている。 Even in the above-mentioned known examples, there is no description about prevention of calcium scale in an aqueous system containing an inorganic suspended substance, and there is no description suggesting this, and a stable calcium scale prevention method in an aqueous system containing an inorganic suspended substance. Development is desired.
本発明は、炭酸カルシウムなどの懸濁物質を含有する水系において、スケール防止剤の効果を安定的に発揮させることができるスケールの防止方法を提供することを目的とするものである。 An object of the present invention is to provide a scale prevention method capable of stably exhibiting the effect of a scale inhibitor in an aqueous system containing a suspended substance such as calcium carbonate.
本発明のスケールの防止方法は、懸濁物質が存在する、製紙工場の古紙脱墨工程の水系に、ホスホン酸及び／又はホスホン酸塩と低分子水溶性ポリマーとを含有させることにより、該水系のスケールの生成を抑制するスケールの防止方法であって、該水系の懸濁物質の存在量が１００ｍｇ／Ｌ以上であり、該懸濁物質が懸濁状炭酸カルシウム主体であることを特徴とする。 The method for preventing scale according to the present invention comprises adding a phosphonic acid and / or a phosphonate and a low-molecular water-soluble polymer to an aqueous system in a waste paper deinking process of a paper mill where a suspended substance is present. A method for preventing scale, which suppresses the generation of scale, characterized in that the abundance of the aqueous suspension is 100 mg / L or more, and the suspension is mainly composed of suspended calcium carbonate. .
即ち、本発明者は、無機懸濁物質が存在する脱墨工程において、ホスホン酸（塩）を添加しても十分なスケール防止効果が得られない原因を調べた結果、添加後の水中に溶存して検出されるホスホン酸（塩）は、添加濃度に比べて低く、古紙パルプスラリー中に数１００〜数１０００ｍｇ／Ｌ含まれる炭酸カルシウム主体の懸濁物質に吸着、消費されて、いわゆる「しきい値」量にも達していないことが原因であることを知見した。そこで鋭意研究の結果、懸濁物質を含有する水系においては、該懸濁物質によるホスホン酸（塩）の吸着、消耗を抑えるために、低分子水溶性ポリマーを併用すると、ホスホン酸（塩）の消耗が著しく減少し、懸濁物質が共存する水系においても安定したスケールの防止効果が得られることを見出し、本発明を完成した。 That is, as a result of investigating the cause of not being able to obtain a sufficient scale prevention effect even if phosphonic acid (salt) is added in the deinking process in which inorganic suspended solids exist, the present inventor found that it was dissolved in the water after the addition. The phosphonic acid (salt) detected in this manner is lower than the added concentration, and is adsorbed and consumed by suspended substances mainly composed of calcium carbonate contained in several hundred to several thousand mg / L of the waste paper pulp slurry. It was found that the cause was that the “threshold” amount was not reached. Therefore, as a result of earnest research, in aqueous systems containing suspended substances, in order to suppress the adsorption and consumption of phosphonic acid (salt) by the suspended substance, when a low molecular weight water-soluble polymer is used in combination, phosphonic acid (salt) It has been found that consumption is remarkably reduced and a stable scale preventing effect can be obtained even in an aqueous system in which suspended substances coexist, and the present invention has been completed.
本発明は、炭化カルシウム等の無機懸濁物質の存在量が１００ｍｇ／Ｌ以上の水系に対して特に有効であり、この懸濁物質の存在量に応じて低分子量水溶性ポリマーの含有濃度を加減することが好ましい。 The present invention is particularly effective for an aqueous system in which the amount of an inorganic suspended substance such as calcium carbide is 100 mg / L or more, and the content of the low-molecular-weight water-soluble polymer is adjusted depending on the amount of the suspended substance. It is preferable to do.
ホスホン酸（塩）としては、１−ヒドロキシエチリデン−１，１−ジホスホン酸（ＨＥＤＰ）及びその塩、２−ホスホノブタン−１，２，４−トリカルボン酸（ＰＢＴＣ）及びその塩、アミノトリメチレンホスホン酸（ＡＭＰ）及びその塩、並びにヘキサメチレン−Ｎ，Ｎ，Ｎ，Ｎ−ジアミン−テトラメチレンホスホン酸（ＨＭＤＴＭＰ）及びその塩よりなる群から選ばれる１種又は２種以上が好適であり、また、低分子水溶性ポリマーとしては、アクリル酸、メタアクリル酸、２−ヒドロキシ−３−アリルオキシ−１−プロパンスルホン酸（ＨＡＰＳ）、マレイン酸、及び２−アクリルアミド−２−メチルプロパンスルホン酸（ＡＭＰＳ）よりなる群から選ばれる１種又は２種以上のモノマーが重合又は共重合してなる、平均分子量１，０００〜１００，０００のホモポリマー又はコポリマーが好適である。 Examples of the phosphonic acid (salt) include 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) and a salt thereof, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and a salt thereof, and aminotrimethylenephosphonic acid (AMP) and a salt thereof, and one or two or more selected from the group consisting of hexamethylene-N, N, N, N-diamine-tetramethylenephosphonic acid (HMDTMP) and a salt thereof are preferable. As low-molecular water-soluble polymers, acrylic acid, methacrylic acid, 2-hydroxy-3-allyloxy-1-propanesulfonic acid (HAPS), maleic acid, and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) 1 or 2 or more types of monomers selected from the group consisting of polymerization or copolymerization, average molecular weight of 1,0 Homopolymers or copolymers of 0～100,000 are preferred.
本発明は、製紙工場の古紙脱墨工程におけるカルシウムスケールの防止である。 The present invention is the prevention of definitive calcium scale to as old paper de-inking factory of manufacturing paper factory.
本発明のスケールの防止方法によれば、懸濁物質が存在する水系において、ホスホン酸（塩）と低分子水溶性ポリマーを共存させることにより、懸濁物質によるホスホン酸（塩）の吸着、消耗を抑制し、ホスホン酸（塩）によるスケール防止効果を有効に発揮させて系内のスケールの生成、付着を安定かつ効率的に防止することができる。 According to the scale prevention method of the present invention, the phosphonic acid (salt) is adsorbed and consumed by the suspended substance in the aqueous system in which the suspended substance is present by allowing the phosphonic acid (salt) and the low-molecular water-soluble polymer to coexist. It is possible to suppress the generation of scale in the system and adhere to it stably and efficiently by effectively suppressing the scale and effectively exerting the scale prevention effect by the phosphonic acid (salt).
以下に本発明のスケールの防止方法の実施の形態を詳細に説明する。 Hereinafter, embodiments of the scale prevention method of the present invention will be described in detail.
本発明が適用される懸濁物質が存在する水系としては、炭酸カルシウム、硫酸カルシウムなどの難溶性カルシウム化合物、アルミニウム化合物、シリカ化合物、水酸化鉄や酸化鉄などの鉄化合物、ベントナイト、タルク、カオリンなどの粘土鉱物などの無機物を懸濁状態で含有する水系が挙げられる。また、パルプ蒸解工程やその後のパルプ水洗工程では、蓚酸カルシウムを主体とする懸濁物が存在する場合があるが、本発明はこのような懸濁物を含有する水系に対しても有効である。なお、水系に懸濁物質がわずかでも存在すれば、ホスホン酸（塩）を吸着、消費するので、本発明の効果が発揮されるが、懸濁物質濃度が１００ｍｇ／Ｌ以上の場合により明確な差が生じ、更に高濃度の２００ｍｇ／Ｌ以上の懸濁物質を含有する水系に対して本発明の効果が顕著となる。 Examples of aqueous systems to which the present invention is applied include poorly soluble calcium compounds such as calcium carbonate and calcium sulfate, aluminum compounds, silica compounds, iron compounds such as iron hydroxide and iron oxide, bentonite, talc, and kaolin. An aqueous system containing an inorganic substance such as a clay mineral in a suspended state. In the pulp cooking step and the subsequent pulp washing step, there may be a suspension mainly composed of calcium oxalate, but the present invention is also effective for an aqueous system containing such a suspension. . It should be noted that the phosphonic acid (salt) is adsorbed and consumed if a small amount of suspended matter is present in the aqueous system, so that the effect of the present invention is exhibited. However, the suspension is more clearly defined when the suspended matter concentration is 100 mg / L or more. A difference arises and the effect of this invention becomes remarkable with respect to the aqueous system containing the suspended substance of 200 mg / L or more of high concentration.
また、本発明で抑制するスケールは、主に炭酸カルシウム、硫酸カルシウム、蓚酸カルシウムなどの水に難溶性のカルシウム化合物を主体とするカルシウムスケールであり、これらのスケールには通常マグネシウム、アルミニウム、鉄、シリカなどのカルシウム以外の成分が含まれているが、カルシウム成分以外の含有の有無に係らず、カルシウムが主体をなすスケールは全て本発明の処理対象とされる。 The scales to be suppressed in the present invention are calcium scales mainly composed of calcium compounds that are hardly soluble in water such as calcium carbonate, calcium sulfate, calcium oxalate, etc., and these scales usually include magnesium, aluminum, iron, Components other than calcium, such as silica, are included, but all scales mainly composed of calcium are subject to treatment of the present invention regardless of the presence or absence of components other than calcium components.
本発明で用いるホスホン酸（塩）の種類には特に制限はないが、例えば、ＨＥＤＰ（１−ヒドロキシエチリデン−１，１−ジホスホン酸）及びその塩、ＰＢＴＣ（２−ホスホノブタン−１，２，４−トリカルボン酸）及びその塩、ＡＭＰ（アミノトリメチレンホスホン酸）及びその塩、ＨＭＤＴＭＰ（ヘキサメチレン−Ｎ，Ｎ，Ｎ，Ｎ−ジアミン−テトラメチレンホスホン酸）及びその塩などが挙げられ、このうち炭酸カルシウムスケールの防止効果の面からは、ＨＥＤＰ、ＨＥＤＰ塩、ＰＢＴＣ、ＰＢＴＣ塩、ＡＭＰ、ＡＭＰ塩、ＨＭＤＴＭＰ、ＨＭＤＴＭＰ塩が好適である。なお、ホスホン酸塩としては、ホスホン酸のナトリウム塩、カリウム塩等のアルカリ金属塩、アンモニウム塩等が好ましい。 The type of phosphonic acid (salt) used in the present invention is not particularly limited. For example, HEDP (1-hydroxyethylidene-1,1-diphosphonic acid) and its salt, PBTC (2-phosphonobutane-1,2,4) -Tricarboxylic acid) and salts thereof, AMP (aminotrimethylenephosphonic acid) and salts thereof, HMTMMP (hexamethylene-N, N, N, N-diamine-tetramethylenephosphonic acid) and salts thereof, etc. From the aspect of preventing the calcium carbonate scale, HEDP, HEDP salt, PBTC, PBTC salt, AMP, AMP salt, HMDTMP, and HMDTMP salt are preferable. The phosphonate is preferably an alkali metal salt such as sodium salt or potassium salt of phosphonic acid, an ammonium salt, or the like.
これらのホスホン酸（塩）は１種を単独で用いても良く、２種以上を併用しても良い。 These phosphonic acids (salts) may be used alone or in combination of two or more.
また、低分子水溶性ポリマーとしては、特に制限はないが、アクリル酸、メタアクリル酸、ＨＡＰＳ（２−ヒドロキシ−３−アリルオキシ−１−プロパンスルホン酸）、マレイン酸、ＡＭＰＳ（２−アクリルアミド−２−メチルプロパンスルホン酸）、ＨＥＭＡ（２−ヒドロキシエチルメタアクリレート）、アクリル酸メチル、スチレンスルホン酸、イソブチレンよりなる群から選ばれる１種又は２種以上のモノマーが重合又は共重合した、ホモポリマー又はコポリマー、好ましくはアクリル酸、メタアクリル酸、ＨＡＰＳ、マレイン酸、ＡＭＰＳよりなる群から選ばれる１種又は２種以上のモノマーが重合又は共重合した、ホモポリマー又はコポリマーであって、平均分子量が１，０００〜１００，０００のものが挙げられる。 The low-molecular water-soluble polymer is not particularly limited, but acrylic acid, methacrylic acid, HAPS (2-hydroxy-3-allyloxy-1-propanesulfonic acid), maleic acid, AMPS (2-acrylamide-2) -Methylpropane sulfonic acid), HEMA (2-hydroxyethyl methacrylate), methyl acrylate, styrene sulfonic acid, homopolymer or polymerized or copolymerized from one or more monomers selected from the group consisting of isobutylene or A copolymer, preferably a homopolymer or a copolymer obtained by polymerizing or copolymerizing one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, HAPS, maleic acid, and AMPS, and having an average molecular weight of 1 , 100,000 to 100,000.
低分子水溶性ポリマーとしては、特にマレイン酸又はアクリル酸のホモポリマー或いは、アクリル酸とＨＡＰＳとのモル比２０〜８０：８０〜２０のコポリマー、アクリルアミドとＡＭＰＳとのモル比２０〜８０：８０〜２０のコポリマー、マレイン酸とイソブチレンとのモル比５０〜８０：５０〜２０のコポリマー等が好適である。 As the low-molecular water-soluble polymer, a homopolymer of maleic acid or acrylic acid, a copolymer of acrylic acid and HAPS in a molar ratio of 20-80: 80-20, or a molar ratio of acrylamide and AMPS of 20-80: 80- 20 copolymers, copolymers of maleic acid and isobutylene in a molar ratio of 50-80: 50-20, etc. are preferred.
これらの低分子水溶性ポリマーは１種を単独で用いても良く、２種以上を併用しても良い。 These low molecular weight water-soluble polymers may be used alone or in combination of two or more.
ホスホン酸（塩）と低分子水溶性ポリマーとは、各々を別々に添加して対象水系へ含有させるようにしても良いし、両者を混合して添加しても良い。ホスホン酸（塩）と低分子水溶性ポリマーの添加順序には制約はないが、水系に対して低分子水溶性ポリマーを先に添加するか、或いはホスホン酸（塩）と低分子水溶性ポリマーとを同時に添加することがより好ましい。 The phosphonic acid (salt) and the low-molecular water-soluble polymer may be added separately and contained in the target aqueous system, or both may be mixed and added. The order of addition of the phosphonic acid (salt) and the low-molecular water-soluble polymer is not limited, but the low-molecular water-soluble polymer is added to the aqueous system first, or the phosphonic acid (salt) and the low-molecular water-soluble polymer It is more preferable to add at the same time.
本発明において適用するホスホン酸（塩）の種類は、懸濁物質が存在しない水系における公知の方法、即ち水中の溶存成分とその濃度から求まるスケール化傾向の強さに応じて選定することができ、その含有濃度は、懸濁物質の濃度に関わらず、いわゆる「しきい値」量の近傍において、予備実験を行うことによって最適濃度を決めることができる。 The type of phosphonic acid (salt) applied in the present invention can be selected according to a known method in an aqueous system in which no suspended substance exists, that is, according to the strength of the scaling tendency obtained from dissolved components in water and their concentrations. The optimum concentration can be determined by conducting a preliminary experiment in the vicinity of the so-called “threshold” amount regardless of the concentration of the suspended solids.
一方、低分子水溶性ポリマーの含有濃度は存在する懸濁物質の量によって影響を受け、懸濁物質の濃度に応じて増減することが望ましい。しかしながら、低分子水溶性ポリマーの必要量は懸濁物質の成分や粒径によって異なるので化学量論的関係を示すことはできない。 On the other hand, the concentration of the low-molecular water-soluble polymer is affected by the amount of suspended material present, and it is desirable to increase or decrease depending on the concentration of suspended material. However, since the required amount of the low-molecular water-soluble polymer varies depending on the components and particle size of the suspended substance, a stoichiometric relationship cannot be shown.
一般的には、ある対象水系に混入する、又は水系で発生する懸濁物質の種類と性質は、一定の範囲内にあることが多く、含有濃度だけが変動する場合が多い。こうした水系では、ホスホン酸（塩）の含有濃度を一定にして、ポリマー含有濃度だけを懸濁物質の増減に応じて増減させる方法によって、スケール防止効果を安定させることができる。 In general, the types and properties of suspended substances mixed in or generated in a target aqueous system are often within a certain range, and only the concentration of the suspended substances often varies. In such an aqueous system, the scale prevention effect can be stabilized by a method in which the phosphonic acid (salt) content concentration is made constant and only the polymer content concentration is increased or decreased in accordance with the increase or decrease in suspended matter.
なお、対象水系に適した低分子水溶性ポリマーの選定は、例えば以下のような方法によって決定することができる。即ち、対象水系から採取した試料に各種低分子水溶性ポリマーを濃度段階をつけて添加し、しかる後ホスホン酸（塩）を添加、撹拌後、濾過又は遠心分離などによって懸濁物質を除き、水中に残留するホスホン酸（塩）濃度を分析する。最小添加濃度の低分子水溶性ポリマーで最大の残留ホスホン酸（塩）濃度を与える低分子水溶性ポリマーが、該対象水系に適した低分子水溶性ポリマーであると判断することができる。 In addition, selection of the low molecular water-soluble polymer suitable for object water system can be determined with the following methods, for example. That is, various low molecular weight water-soluble polymers are added to a sample collected from the target water system in a concentration step, and then phosphonic acid (salt) is added, stirred, filtered, or centrifuged to remove suspended substances, and water is added. The residual phosphonic acid (salt) concentration is analyzed. It can be determined that the low-molecular water-soluble polymer that gives the maximum residual phosphonic acid (salt) concentration with the minimum addition concentration of the low-molecular water-soluble polymer is the low-molecular water-soluble polymer suitable for the target water system.
以下に実施例及び比較例を挙げて本発明をより具体的に説明する。 Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
実施例１〜１０
純水を用いて塩化カルシウム水溶液を調製し、これを純水で希釈して、調整後のカルシウム硬度が３００ｍｇ−ＣａＣＯ３／Ｌとなるようにした検水１Ｌをビーカーに分注し、供試ポリマー（下記ポリマーＡ又はポリマーＢ）及び供試ホスホン酸（ＨＥＤＰ又はＰＢＴＣ）を各々表１に示す所定濃度となるように添加した。続いて、重炭酸ナトリウム水溶液を調整後の検水Ｍ−アルカリ度が３００ｍｇ−ＣａＣＯ３／Ｌとなるように添加し、さらに水酸化ナトリウム水溶液を加えてｐＨ９．４に調整した。しかる後、製紙工業の填料に用いられる軽質炭酸カルシウム粒状粉末（キシダ化学社製特級、平均粒径１０〜２０μｍ）を表１に示す所定濃度となるように懸濁させ、ビーカーを４０℃の恒温水槽に移し、マグネチックスターラーで懸濁液を１時間撹拌した。撹拌終了後、懸濁液をポアサイズ０．２２μｍのミリポアフィルターで濾過し、濾液中のカルシウム硬度をＪＩＳ Ｋ−０１０１の方法により分析し、結果を表１に示した。
ポリマーＡ：アクリル酸とＨＡＰＳとをモル比８０：２０で共重合させたコポリマー。光散乱法で測定した平均分子量は約１０，０００。
ポリマーＢ：マレイン酸のホモポリマー。光散乱法で測定した平均分子量は約３，０００。
Examples 1-10
Prepare an aqueous calcium chloride solution using pure water, dilute it with pure water, and dispense 1 L of test water with adjusted calcium hardness to 300 mg-CaCO 3 / L into a beaker. A polymer (polymer A or polymer B below) and a test phosphonic acid (HEDP or PBTC) were added so as to have predetermined concentrations shown in Table 1, respectively. Subsequently, a sodium bicarbonate aqueous solution was added so that the sample water M-alkalinity after adjustment was 300 mg-CaCO 3 / L, and a sodium hydroxide aqueous solution was further added to adjust the pH to 9.4. Thereafter, a light calcium carbonate granular powder (special grade manufactured by Kishida Chemical Co., Ltd., average particle size of 10 to 20 μm) used as a filler in the paper industry is suspended to a predetermined concentration shown in Table 1, and the beaker is kept at a constant temperature of 40 ° C. The suspension was transferred to a water tank and the suspension was stirred with a magnetic stirrer for 1 hour. After the stirring, the suspension was filtered through a Millipore filter having a pore size of 0.22 μm, and the calcium hardness in the filtrate was analyzed by the method of JIS K-0101. The results are shown in Table 1.
Polymer A: A copolymer obtained by copolymerizing acrylic acid and HAPS at a molar ratio of 80:20. The average molecular weight measured by the light scattering method is about 10,000.
Polymer B: A homopolymer of maleic acid. The average molecular weight measured by the light scattering method is about 3,000.
比較例１
ホスホン酸（塩）及び低分子水溶性ポリマーと炭酸カルシウム粒状粉末を添加しなかったこと以外は、実施例１と同様にして試験を行い、結果を表１に示した。
Comparative Example 1
The test was conducted in the same manner as in Example 1 except that the phosphonic acid (salt), the low-molecular water-soluble polymer, and the calcium carbonate granular powder were not added, and the results are shown in Table 1.
比較例２〜１１
低分子水溶性ポリマーを添加せず、ホスホン酸（塩）の添加量を表１に示す濃度としたこと以外は実施例１と同様にして試験を行い、結果を表１に示した。なお、比較例２，５，８では炭酸カルシウム粒状粉末を添加しなかった。
Comparative Examples 2-11
The test was conducted in the same manner as in Example 1 except that the low-molecular water-soluble polymer was not added and the addition amount of phosphonic acid (salt) was changed to the concentration shown in Table 1. The results are shown in Table 1. In Comparative Examples 2, 5, and 8, calcium carbonate granular powder was not added.
表１より次のことが明らかである。 From Table 1, the following is clear.
カルシウム硬度３００ｍｇ−ＣａＣＯ３／Ｌ、Ｍ−アルカリ度３００ｍｇ−ＣａＣＯ３／Ｌ、ｐＨ９．４の水質条件においては、懸濁する炭酸カルシウムが存在しなくても溶存するカルシウムイオンと炭酸イオンが反応し、炭酸カルシウムが析出するため、濾液のカルシウム硬度が低下する（比較例１）。この条件で、すなわち懸濁する炭酸カルシウムが存在しない条件下でＨＥＤＰ３ｍｇ／Ｌを加えた場合、炭酸カルシウムの析出は完全に抑制できるため、濾液のカルシウム硬度は３００ｍｇ−ＣａＣＯ３／Ｌである（比較例２）。しかしながら、懸濁状炭酸カルシウムが存在する場合は、ＨＥＤＰ３ｍｇ／Ｌの添加では新たな炭酸カルシウムの析出を防止することができず、そのために溶液中に溶存して残留するカルシウム硬度が低下した（比較例３，４）。同じ条件でホスホン酸の種類をＨＥＤＰからＰＢＴＣに変えても同様の結果が得られた（比較例５〜７）。 Calcium hardness 300mg-CaCO 3 / L, in water conditions M- alkalinity 300mg-CaCO 3 /L,pH9.4 calcium ions and carbonate ions calcium carbonate suspension is dissolved even in the absence of reacting Since calcium carbonate precipitates, the calcium hardness of the filtrate decreases (Comparative Example 1). When HEDP 3 mg / L is added under these conditions, that is, in the absence of suspended calcium carbonate, precipitation of calcium carbonate can be completely suppressed, so the calcium hardness of the filtrate is 300 mg-CaCO 3 / L (comparison) Example 2). However, when suspended calcium carbonate is present, the addition of HEDP 3 mg / L cannot prevent the precipitation of new calcium carbonate, so that the calcium hardness dissolved and remaining in the solution decreases (comparison) Examples 3 and 4). Similar results were obtained even when the type of phosphonic acid was changed from HEDP to PBTC under the same conditions (Comparative Examples 5 to 7).
そこで、ＨＥＤＰの添加濃度を２０ｍｇ／Ｌに増加させた結果、懸濁状の炭酸カルシウムが存在する場合に新たな炭酸カルシウムの析出を防止することはできず、改善効果は殆ど認められなかった（比較例９，１０）。懸濁状炭酸カルシウムが存在しない状態でＨＥＤＰ添加濃度を２０ｍｇ／Ｌに増加させた場合には、ゲル状物質が生成してむしろ溶存するカルシウム硬度が低下する現象さえ認められた（比較例８）。また、ＨＥＤＰの代わりにＰＢＴＣを添加しても新たな炭酸カルシウムの析出を防止することはできず、改善効果は殆ど認められなかった（比較例１１）。 Therefore, as a result of increasing the concentration of HEDP added to 20 mg / L, precipitation of new calcium carbonate could not be prevented when suspended calcium carbonate was present, and almost no improvement effect was observed ( Comparative Examples 9 and 10). When the HEDP addition concentration was increased to 20 mg / L in the absence of suspended calcium carbonate, a phenomenon was observed in which the gel hardness was generated and rather the dissolved calcium hardness decreased (Comparative Example 8). . Moreover, even if PBTC was added instead of HEDP, precipitation of new calcium carbonate could not be prevented, and almost no improvement effect was observed (Comparative Example 11).
これに対して、ホスホン酸添加濃度３ｍｇ／Ｌで、ポリマーＡ又はポリマーＢを３ｍｇ／Ｌとなるように添加してホスホン酸と併用した場合には、ＨＥＤＰとポリマーＡの組合せ（実施例１）、ＨＥＤＰとポリマーＢの組合せ（実施例３）、ＰＢＴＣとポリマーＡの組合せ（実施例２）のいずれにおいても新たな炭酸カルシウムの析出を防止するか、大幅な析出防止の改善効果が認められた。懸濁状炭酸カルシウムの量が５００ｍｇ／Ｌの条件では、新たな炭酸カルシウム析出防止効果が得られなかったが、それでもホスホン酸（ＨＥＤＰ）単独の高濃度添加（比較例１０）に比べると大幅な析出防止効果の改善が認められた（実施例４）。 On the other hand, when phosphonic acid was added at a concentration of 3 mg / L and polymer A or polymer B was added to 3 mg / L and used in combination with phosphonic acid, a combination of HEDP and polymer A (Example 1) In either the combination of HEDP and polymer B (Example 3) or the combination of PBTC and polymer A (Example 2), the precipitation of new calcium carbonate was prevented or a significant improvement in the prevention of precipitation was observed. . Under the condition that the amount of suspended calcium carbonate is 500 mg / L, a new calcium carbonate precipitation preventing effect was not obtained, but it was still much larger than the high concentration addition of phosphonic acid (HEDP) alone (Comparative Example 10). An improvement in the precipitation preventing effect was observed (Example 4).
懸濁状の炭酸カルシウム濃度が高く、ポリマー添加３ｍｇ／Ｌでは十分な析出防止効果が得られなかった条件においても、ホスホン酸の添加濃度は３ｍｇ／Ｌのままで、ポリマー添加濃度だけを増大させた場合には、いずれもポリマー添加量の増加につれて析出防止効果の改善が認められた（実施例５〜１０）。 Even under conditions where the suspended calcium carbonate concentration was high and sufficient precipitation prevention effect was not obtained with 3 mg / L of polymer addition, the addition concentration of phosphonic acid remained at 3 mg / L, and only the polymer addition concentration was increased. In any case, improvement of the precipitation preventing effect was observed as the amount of polymer added increased (Examples 5 to 10).
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