JP4284984B2 - Production method of magnetic fluid - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、磁性流体の製造法に関する。さらに詳しくは、平均粒子径が小さくかつその粒度分布の狭い微粒子を生成させるマグネタイト微粒子を用いた磁性流体の製造法に関する。
【０００２】
【従来の技術】
一般に、微粒子の製造法は、微粒子の生成過程から分類すると、細分化と生長法とに大別される。細分化法は、粗粒子の機械的粉砕によって微粒子を得る方法であるが、平均粒子径が1μm以下の微粒子を効率よく得ることは困難である。一方、生長法は、ガスや溶液状態での化学反応により、原子もしくは分子から核生成と成長により微粒子を得る方法であり、粒子径1μm以下の微粒子を効率よく得ることができ、また粒度分布の制御も可能である。
【０００３】
マグネタイト微粒子の製造法においても、生長法が広く利用されており、特に3価の鉄イオンと2価の鉄イオンとが混在した水溶液にアルカリを添加し、加熱熟成して微粒子を生成させる共沈法は、nmサイズの平均粒子径を有するマグネタイト微粒子が容易に得られ、しかもその粒度分布も狭いことから、磁性流体等の磁性コロイドやトナー、磁気記録材料等に広く利用されている。
【０００４】
最近では、磁気記録媒体のさらなる高密度化や磁性コロイドの高磁場での分散安定性が求められるにつれて、より粒子径が小さくかつ粒度分布が狭いマグネタイト微粒子が必要とされている。しかしながら、マグネタイトの粒子径が8nm以下、特に5nm以下となると、飽和磁化値は大きく低下するため、磁性微粒子としての使用に問題を生ずるようになる。
【０００５】
従来周知の共沈法によるマグネタイト微粒子の製造法では、平均粒子径が10nmよりも大きくなってしまい、このため磁性流体等の磁性コロイドとした場合、凝集粒子径が大きくなるのを避けることができない。そのため、共沈法での鉄塩水溶液に予め界面活性剤(日本化学会誌 1991年9月号第1183〜1187頁)や水溶性高分子(Rep. Asahi Glass Found.第57号第143〜151頁、1990年)等を添加しておき、平均粒子径を小さくする方法が知られているが、これらの添加剤の添加によって粒子の結晶化が阻害されるため、マグネタイト微粒子の飽和磁化率が大きく低下することとなる。
【０００６】
また、マグネタイト微粒子の調製後、遠心分離法や磁気分離法により粗大粒子を除去し、粒子径や粒度分布を調節することは可能であるが、所望の粒子径を有するマグネタイト微粒子の収率は大きく低下する。
【０００７】
【発明が解決しようとする課題】
本発明の目的は、鉄塩水溶液にアルカリを添加し、熟成させる共沈法によりマグネタイト微粒子を製造するに際し、良好な飽和磁化率を保持しながら、平均粒子径(FERET径)が5〜10nm程度と小さくしかも粒度分布の狭いマグネタイト微粒子を用いた磁性流体の製造方法を提供することにある。
【０００８】
【課題を解決するための手段】
かかる本発明の目的は、共沈法によりマグネタイト微粒子を製造するに際し、3価の鉄イオン化合物と2価の鉄イオン化合物とが混在する鉄塩水溶液中に、3価の鉄イオン化合物であるFeCl 3 ・6H 2 O 1モルに対し0.01〜1モルの割合で用いられるアルコールアミンを添加した後アルカリを添加して製造されたマグネタイト微粒子を基油中に分散させて磁性流体を製造する方法によって達成される。
【０００９】
【発明の実施の形態】
共沈法によるマグネタイト微粒子の製造は、3価の鉄イオン化合物、例えばFeCl3・6H2Oと2価の鉄イオン化合物、例えばFeCl2・4H2Oとを等モル量混在した水溶液中に、アンモニア水、水酸化ナトリウム等のアルカリを添加することにより行われるが、本発明にあっては、アルカリの添加に先立って、水の沸点以下、好ましくは約3〜40℃の温度に保持された鉄塩水溶液中にアルコールアミンの添加が行われる。
【００１０】
アルコールアミンとしては、例えば2-アミノエタノール、2-エチルアミノエタノール、ジエチルアミノエタノール、N,N-ジエチルヒドロキシアミン、2-ジメチルアミノエタノール、1-アミノ-2-プロパノール、3-アミノ-1-プロパノール、3-(ジメチルアミノ)-1-プロパノール、N-n-ブチル-2,2′-イミノジエタノール、2-アニリノエタノール、2-(ベンジルアミノ)エタノール、N-ベンジル-N-メチルエタノールアミン、2,2′,2′′-ニトリロトリエタノール、1,1′,1′′-ニトリロ-トリス(2-プロパノール)が用いられるが、特に2,2′,2′′-ニトリロトリエタノール〔トリエタノールアミン〕、1,1′,1′′-ニトリロ-トリス(2-プロパノール)〔トリイソプロパノールアミン〕が好んで用いられる。
【００１１】
これらのアルコールアミンは、3価の鉄イオン化合物であるFeCl3・6H2O 1モルに対し約0.01〜1モル、好ましくは約0.1〜1モルの割合で用いられる。これ以下の添加割合では、得られるマグネタイト微粒子の平均粒子径が10μm以下とはならず、また粒度分布も大きくなり、さらにはそれから調製された磁性流体の個数50％粒子径(個数基準分布による個数中位径)も大きくなる。一方、これ以上の割合で用いることは、アルコールアミンの洗浄除去性の点から好ましくない。なお、アルコールアミンは微粒子への吸着性が弱いため、微粒子生成時の結晶化を阻害することはない。
【００１２】
このようなアルコールアミンの代りに、界面活性剤であるドデシルベンゼンスルホン酸を使用した場合には、後記比較例3の結果に示されるように、マグネタイト微粒子の平均粒子径、その粒度分布およびそれから調製された磁性流体の50％粒子径はそれぞれ満足されるものの、肝心の飽和磁化率が低くなる。
【００１３】
鉄塩水溶液中へのアルコールアミンの添加に引続いて、従来法での如くアルカリの添加および約80〜99℃で約0.5〜2時間程度の熟成が行われ、そこにマグネタイト微粒子ゾルを形成させる。アルコールアミンの次にアルカリを添加することは必須の条件であり、後記比較例2の結果に示されるように、この添加順序を逆にすると所望の飽和磁化率は得られるものの、マグネタイト微粒子の平均粒子径は10nm以上となりまたその粒度分布も広くなり、さらにそれから調製された磁性流体の個数50％粒子径も大きくなる。
【００１４】
このようにして得られるマグネタイトゾルを用いての磁性流体の調製は、公知の任意の方法、例えば後記実施例1に記載されるような方法に従って、オレイン酸被覆マグネタイト微粒子を基油中に分散させることによって行われ、この際には特に分散剤を用いなくとも良好に基油中への分散が行われる。
【００１５】
基油としては、トルエンによって代表される芳香族炭化水素等も用いられるが、一般には低蒸気圧基油が用いられる。低蒸気圧基油としては、25℃において0.1mmHg以下、好ましくは0.01mmHg以下の蒸気圧を有する液体、例えば天然油であるホワイトオイル(流動パラフィン)、鉱油、スピンドル油など、あるいは合成油である高級アルキルベンゼン、高級アルキルナフタレン、ポリブテン(分子量約300〜2000)など、また酸化防止剤、耐摩耗剤、油性剤、清浄分散剤などのいわゆる潤滑添加剤を含んだ潤滑油等が用いられる。
【００１６】
【発明の効果】
本発明方法により、良好な飽和磁化率を保持しながら、平均粒子径が約5〜10nmと細かくかつその粒度分布の狭いマグネタイト微粒子を効率よく簡便な方法で製造することができ、これを基油中に分散させることによって、磁性流体を始め磁性コロイドの分散安定性が改善され、この微粒子から製造された磁性流体の50％粒子径を小さくすることができる。また、遠心分離や磁気分離による微粒子の精製が不要となるため、微粒子の収率が向上する。
【００１７】
このため、本発明方法で用いられたマグネタイト微粒子は、磁性流体以外にも種々のマグネタイトコロイド、トナー、磁気記録材料等の用途に有効に用いられる。
【００１８】
【実施例】
次に、実施例について本発明を説明する。
【００１９】
実施例１
FeCl3・6H2O 270gおよびFeCl2・4H2O 100gを溶解させた水溶液5000mlの温度を20℃に保持しながら、これに2,2′,2′′-ニトリロトリエタノール N(CH2CH2OH)3 220gを攪拌しながら、徐々に添加した。次いで、28％アンモニア水330mlを添加した後、90℃で60分間加熱熟成し、得られたマグネタイトゾルを脱塩水でデカンテーションする洗浄を数回行った後、マグネタイトゾルを12時間静置し、沈降したマグネタイト微粒子を分離した。
【００２０】
このマグネタイト微粒子を透過型電子顕微鏡で写真撮影し、写真に投影されたマグネタイト微粒子の配向がほぼランダムであることから、FERET径(日刊工業新聞社刊「粉体工学の基礎」第285〜7頁、1992年)を微粒子径とし、母集団400に対する数平均を平均粒子径とすると、マグネタイト微粒子の平均粒子径は8.0nmであり、その標準偏差は2.6であった。また、マグネタイト微粒子の飽和磁化率を、振動試料型磁力計で測定すると、70emu/gであった。
【００２１】
また、加熱熟成後のマグネタイトゾルに、オレイン酸ナトリウム40gを溶解させた水溶液500mlを加え、90℃で30分間吸着処理を行った。このオレイン酸被覆マグネタイト微粒子を、脱塩水でデカンテーションする洗浄を数回くり返した後、乾燥させた。乾燥後のオレイン酸被覆マグネタイト微粒子10gにトルエン400mlを加え、超音波照射を30分間行った後、マグネタイト微粒子分散液にアセトン400mlを加え、微粒子を凝集沈殿させて、上澄み液を除去した。
【００２２】
この微粒子に、高級アルキルナフタレン(ライオン製ポンプオイルS)20gおよびトルエン400mlを加え、超音波照射を30分間行った後、遠心分離(12000G)して沈殿物を除去し、次いでトルエンを除去して磁性流体を得た。硫性流体中のマグネタイト微粒子の凝集径を、光散乱粒度計によって測定したところ、個数50％粒子径は20nmであった。
【００２３】
実施例２
実施例1において、FeCl3・6H2OおよびFeCl2・4H2Oを溶解させた水溶液の保持温度を5℃に変更し、平均粒子径5.5nm、その標準偏差1.9、飽和磁化率62emu/gのマグネタイト微粒子を得、またマグネタイトゾルを用いて調製された磁性流体の個数50％粒子径は18nmであった。
【００２４】
実施例３
実施例1において、2,2′,2′′-ニトリロトリエタノール量を22gに変更し、平均粒子径8.2nm、その標準偏差3.1、飽和磁化率73emu/gのマグネタイト微粒子を得、またマグネタイトゾルを用いて調製された磁性流体の個数50％粒子径は23nmであった。
【００２５】
実施例４
実施例1において、2,2′,2′′-ニトリロトリエタノールの代りに同量(220g)の1,1′,1′′-ニトリロ-2-プロパノールを使用し、平均粒子径8.3nm、その標準偏差2.8、飽和磁化率72emu/gのマグネタイト微粒子を得、またマグネタイトゾルから調製された磁性流体の個数50％粒子径は23nmであった。
【００２６】
比較例１
実施例1において、2,2′,2′′-ニトリロトリエタノールを用いないと、平均粒子径12.0nm、その標準偏差4.0、飽和磁化率75emu/gが得られ、またマグネタイト微粒子から調製された磁性流体の個数50％粒子径は36nmであった。
【００２７】
比較例２
実施例1において、鉄塩水溶液への2,2′,2′′-ニトリロトリエタノールとアンモニア水の添加順序を逆にすると、平均粒子径11.8nm、その標準偏差3.9、飽和磁化率75emu/gのマグネタイト微粒子が得られ、またマグネタイト微粒子から調製された磁性流体の個数50％粒子径は36nmであった。
【００２８】
比較例３
実施例1において、2,2′,2′′-ニトリロトリエタノールの代りに同量(220g)のドデシルベンゼンスルホン酸を用いると、平均粒子径4.0nm、その標準偏差1.8、飽和磁化率28emu/gのマグネタイト微粒子が得られ、またマグネタイトゾルを用いて調製された磁性流体の個数50％粒子径は17nmであった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a magnetic fluid . More specifically, the present invention relates to a method for producing a magnetic fluid using magnetite fine particles that generate fine particles having a small average particle size and a narrow particle size distribution.
[0002]
[Prior art]
In general, fine particle production methods are roughly classified into subdivision and growth methods when classified from the production process of fine particles. The fragmentation method is a method of obtaining fine particles by mechanical pulverization of coarse particles, but it is difficult to efficiently obtain fine particles having an average particle diameter of 1 μm or less. On the other hand, the growth method is a method of obtaining fine particles by nucleation and growth from atoms or molecules by a chemical reaction in a gas or solution state. Fine particles having a particle diameter of 1 μm or less can be efficiently obtained, and the particle size distribution is Control is also possible.
[0003]
The growth method is also widely used in the production method of magnetite fine particles, especially coprecipitation in which alkali is added to an aqueous solution in which trivalent iron ions and divalent iron ions are mixed, and heat aging is performed to generate fine particles. This method is widely used in magnetic colloids such as magnetic fluids, toners, magnetic recording materials and the like because magnetite fine particles having an average particle size of nm size can be easily obtained and the particle size distribution is narrow.
[0004]
Recently, as the recording density of magnetic recording media is further increased and the dispersion stability of magnetic colloids in a high magnetic field is required, magnetite fine particles having a smaller particle size and a narrow particle size distribution are required. However, when the particle size of magnetite is 8 nm or less, particularly 5 nm or less, the saturation magnetization value is greatly reduced, which causes a problem in use as magnetic fine particles.
[0005]
In the conventionally known method for producing magnetite fine particles by the coprecipitation method, the average particle size becomes larger than 10 nm. Therefore, when a magnetic colloid such as a magnetic fluid is used, it is inevitable that the aggregated particle size becomes large. . For this reason, surfactants (September 1991, No. 1183 to 1187 pages) and water-soluble polymers (Rep. Asahi Glass Found. No. 57, pages 143 to 151) were added to the iron salt aqueous solution by the coprecipitation method. , 1990) and the like, and a method of reducing the average particle diameter is known, but the addition of these additives inhibits the crystallization of the particles, so the saturation magnetic susceptibility of the magnetite fine particles is large. Will be reduced.
[0006]
In addition, after preparing magnetite fine particles, coarse particles can be removed by centrifugal separation or magnetic separation, and the particle size and particle size distribution can be adjusted. However, the yield of magnetite fine particles having a desired particle size is large. descend.
[0007]
[Problems to be solved by the invention]
The purpose of the present invention is to produce magnetite fine particles by coprecipitation method by adding an alkali to an iron salt aqueous solution and aging, while maintaining a good saturation magnetic susceptibility, the average particle diameter (FERET diameter) is about 5 to 10 nm Another object of the present invention is to provide a magnetic fluid production method using magnetite fine particles having a small particle size distribution.
[0008]
[Means for Solving the Problems]
An object of the present invention is to produce FeCl which is a trivalent iron ion compound in an iron salt aqueous solution in which a trivalent iron ion compound and a divalent iron ion compound are mixed when producing magnetite fine particles by a coprecipitation method. 3 · 6H 2 O 1 mol dispersed in the base oil alkaline magnetite fine particles produced by adding after adding alcohol amine used in a proportion of 0.01 to 1 mole and achieved by a method of producing a magnetic fluid Is done.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Production of magnetite fine particles by the coprecipitation method is carried out in an aqueous solution in which equimolar amounts of a trivalent iron ion compound , for example, FeCl 3 · 6H 2 O and a divalent iron ion compound , for example, FeCl 2 · 4H 2 O are mixed. Although it is performed by adding an alkali such as aqueous ammonia or sodium hydroxide, in the present invention, prior to the addition of the alkali, the temperature was kept below the boiling point of water, preferably about 3 to 40 ° C. Alcoholamine is added to the iron salt aqueous solution.
[0010]
Examples of the alcohol amine include 2-aminoethanol, 2-ethylaminoethanol, diethylaminoethanol, N, N-diethylhydroxyamine, 2-dimethylaminoethanol, 1-amino-2-propanol, 3-amino-1-propanol, 3- (dimethylamino) -1-propanol, Nn-butyl-2,2 '- iminodiethanol, 2-anilinoethanol, 2- (benzylamino) ethanol, N- benzyl -N- methylethanolamine, 2,2 ′, 2 ″ -nitrilotriethanol, 1,1 ′, 1 ″ -nitrilo-tris (2-propanol) is used, and in particular, 2,2 ′, 2 ″ -nitrilotriethanol ( triethanolamine ) , 1 1,1 ′, 1 ″ -nitrilo-tris (2-propanol) [ triisopropanolamine ] is preferably used.
[0011]
These alcohol amines are used in a ratio of about 0.01 to 1 mol, preferably about 0.1 to 1 mol, per 1 mol of FeCl 3 .6H 2 O which is a trivalent iron ion compound . When the addition ratio is less than this, the average particle size of the obtained magnetite fine particles does not become 10 μm or less, the particle size distribution becomes large, and the number of magnetic fluids prepared therefrom is 50% (the number based on the number-based distribution). The median diameter is also increased. On the other hand, it is not preferable to use it in a proportion higher than this from the viewpoint of washing and removing alcoholamine. In addition, since alcohol amine has a weak adsorptivity to fine particles, it does not hinder crystallization during fine particle generation.
[0012]
When dodecylbenzenesulfonic acid, which is a surfactant, is used in place of such alcohol amine, as shown in the results of Comparative Example 3 to be described later, the average particle size of the magnetite fine particles, its particle size distribution and the preparation thereof. Although the 50% particle size of the ferrofluid is satisfied, the saturation susceptibility of the core is lowered.
[0013]
Subsequent to the addition of alcohol amine to the iron salt aqueous solution, alkali is added as in the conventional method and aging is carried out at about 80 to 99 ° C. for about 0.5 to 2 hours to form a magnetite fine particle sol there. . It is an indispensable condition to add an alkali next to the alcohol amine, and as shown in the results of Comparative Example 2 to be described later, when this addition order is reversed, a desired saturation magnetic susceptibility can be obtained, but the average of the magnetite fine particles The particle diameter is 10 nm or more, the particle size distribution is widened, and the number of magnetic fluids prepared from the particle diameter is 50%.
[0014]
The magnetic fluid using the magnetite sol thus obtained is prepared by dispersing oleic acid-coated magnetite fine particles in the base oil according to any known method, for example, the method described in Example 1 below. In this case, the dispersion into the base oil is favorably performed without using a dispersant.
[0015]
As the base oil, aromatic hydrocarbons typified by toluene are used, but generally, a low vapor pressure base oil is used. The low vapor pressure base oil is a liquid having a vapor pressure of 0.1 mmHg or less, preferably 0.01 mmHg or less at 25 ° C., such as white oil (liquid paraffin) which is a natural oil, mineral oil, spindle oil, or synthetic oil. Higher alkylbenzene, higher alkylnaphthalene, polybutene (molecular weight of about 300 to 2000) and the like, and lubricating oils containing so-called lubricating additives such as antioxidants, antiwear agents, oiliness agents, detergent dispersants and the like are used.
[0016]
【The invention's effect】
The present invention method, while maintaining good saturation magnetization ratio, narrow magnetite fine particles having an average particle size of the fine and the particle size distribution of about 5~10nm can be manufactured in efficient and simple method to which the base oil By dispersing in, the dispersion stability of the magnetic colloid including the magnetic fluid is improved, and the 50% particle diameter of the magnetic fluid produced from the fine particles can be reduced. Further, since the purification of the fine particles by centrifugation or magnetic separation becomes unnecessary, the yield of the fine particles is improved.
[0017]
For this reason, the magnetite fine particles used in the method of the present invention are effectively used for various magnetite colloids, toners, magnetic recording materials and the like in addition to magnetic fluids.
[0018]
【Example】
Next, the present invention will be described with reference to examples.
[0019]
Example 1
While maintaining the temperature of 5000 ml of an aqueous solution containing 270 g of FeCl 3 · 6H 2 O and 100 g of FeCl 2 · 4H 2 O at 20 ° C., 2,2 ′, 2′-nitrilotriethanol N (CH 2 CH 2 OH) 3 220 g was added slowly with stirring. Next, after adding 330% of 28% aqueous ammonia, heating and aging at 90 ° C. for 60 minutes, the resulting magnetite sol was decanted with demineralized water several times, and then the magnetite sol was allowed to stand for 12 hours. The settled magnetite fine particles were separated.
[0020]
This magnetite fine particle was photographed with a transmission electron microscope, and the orientation of the magnetite fine particle projected on the photograph was almost random. Therefore, the FERET diameter (Nikkan Kogyo Shimbun, “Basics of Powder Engineering”, pages 285-7 1992) is the fine particle diameter, and the average particle diameter is the number average for the population 400, the average particle diameter of the magnetite fine particles is 8.0 nm, and its standard deviation is 2.6. The saturation magnetic susceptibility of the magnetite fine particles was 70 emu / g as measured by a vibrating sample magnetometer.
[0021]
Further, 500 ml of an aqueous solution in which 40 g of sodium oleate was dissolved was added to the magnetite sol after heat aging, and an adsorption treatment was performed at 90 ° C. for 30 minutes. The oleic acid-coated magnetite fine particles were repeatedly decanted with demineralized water several times and then dried. 400 g of toluene was added to 10 g of the oleic acid-coated magnetite fine particles after drying, and ultrasonic irradiation was performed for 30 minutes. Then, 400 ml of acetone was added to the magnetite fine particle dispersion to coagulate and precipitate the fine particles, and the supernatant was removed.
[0022]
To this fine particle, 20 g of higher alkylnaphthalene (Lion's pump oil S) and 400 ml of toluene were added, and after ultrasonic irradiation for 30 minutes, the precipitate was removed by centrifugation (12000G), and then toluene was removed. A magnetic fluid was obtained. When the agglomerated diameter of the magnetite fine particles in the sulfur fluid was measured with a light scattering particle size meter, the 50% number particle diameter was 20 nm.
[0023]
Example 2
In Example 1, the holding temperature of the aqueous solution in which FeCl 3 · 6H 2 O and FeCl 2 · 4H 2 O were dissolved was changed to 5 ° C., the average particle diameter was 5.5 nm, its standard deviation was 1.9, and the saturation magnetic susceptibility was 62 emu / g. In addition, the number of magnetic fluids prepared using a magnetite sol was 50% and the particle diameter was 18 nm.
[0024]
Example 3
In Example 1, the amount of 2,2 ′, 2 ″ -nitrilotriethanol was changed to 22 g, and magnetite fine particles having an average particle diameter of 8.2 nm, a standard deviation of 3.1, and a saturation magnetic susceptibility of 73 emu / g were obtained. The number of 50% ferrofluids prepared using the particle size was 23 nm.
[0025]
Example 4
In Example 1, instead of 2,2 ′, 2 ″ -nitrilotriethanol, the same amount (220 g) of 1,1 ′, 1 ″ -nitrilo-2-propanol was used, and the average particle size was 8.3 nm. Magnetite fine particles having a standard deviation of 2.8 and a saturation magnetic susceptibility of 72 emu / g were obtained, and the number of 50% magnetic fluid prepared from the magnetite sol had a particle size of 23 nm.
[0026]
Comparative Example 1
In Example 1, when 2,2 ′, 2 ″ -nitrilotriethanol was not used, an average particle diameter of 12.0 nm, a standard deviation of 4.0, a saturation magnetic susceptibility of 75 emu / g was obtained, and a magnetic material prepared from magnetite fine particles was obtained. The 50% particle number of the fluid was 36 nm.
[0027]
Comparative Example 2
In Example 1, when the order of adding 2,2 ′, 2 ″ -nitrilotriethanol and aqueous ammonia to the iron salt aqueous solution was reversed, the average particle diameter was 11.8 nm, its standard deviation was 3.9, and the saturation magnetic susceptibility was 75 emu / g. Magnetite fine particles were obtained, and the 50% number of magnetic fluids prepared from the magnetite fine particles had a particle size of 36 nm.
[0028]
Comparative Example 3
In Example 1, when the same amount (220 g) of dodecylbenzenesulfonic acid was used instead of 2,2 ′, 2 ″ -nitrilotriethanol, the average particle diameter was 4.0 nm, its standard deviation was 1.8, and the saturation magnetic susceptibility was 28 emu / g. The magnetite fine particles were obtained, and the number of 50% of the magnetic fluid prepared using the magnetite sol was 17 nm.
Claims (4)
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