JP2004292998A - Absorbent for pitch and method for preventing trouble by pitch - Google Patents

Absorbent for pitch and method for preventing trouble by pitch Download PDF

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Publication number
JP2004292998A
JP2004292998A JP2003088752A JP2003088752A JP2004292998A JP 2004292998 A JP2004292998 A JP 2004292998A JP 2003088752 A JP2003088752 A JP 2003088752A JP 2003088752 A JP2003088752 A JP 2003088752A JP 2004292998 A JP2004292998 A JP 2004292998A
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Japan
Prior art keywords
pitch
talc
water
pulp
contact angle
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JP2003088752A
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Japanese (ja)
Inventor
Yuko Iijima
夕子 飯嶋
Masateru Akimura
将輝 明村
Shigeru Mogi
茂 茂木
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Nippon Paper Industries Co Ltd
Jujo Paper Co Ltd
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Nippon Paper Industries Co Ltd
Jujo Paper Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbent for pitch in which a pitch component which becomes a problem can effectively be absorbed by adding the absorbent to pulp raw materials and/or papermaking raw materials in order to prevent trouble caused by pitch in a pulp-producing step and/or a papermaking step. <P>SOLUTION: A talc in which contact angle with water after 40 sec after dropwise adding drops of water is ≥120° is used as the pitch absorbent and the talc is added to the pulp-producing step and/or the papermaking step in which the pitch component exists to absorb the pitch component and further the talc is incorporated into paper to remove the pitch from a papermaking system. Thereby, trouble caused by pitch is prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【0001】
【産業上の利用分野】
本発明は、紙、パルプなどの製造工程で発生するピッチトラブルを解消するためのピッチ吸着剤に関するもので、より詳細には、白水中に遊離したピッチ成分に対して優れた吸着性能を示すピッチ吸着剤に関する。
【0002】
【従来の技術】
紙やパルプの製造工程や再生紙の製造工程において、原料木材に含まれる樹脂成分や、紙の加工に際して添加される樹脂成分や接着剤として用いられる粘着成分、すなわちピッチがパルプスラリー中に存在し、パルプ工程においてはチェストやパイプ壁面に堆積し、抄紙工程においては、ワイヤー、フェルトなどの抄紙用具を汚し、その析出物が製品に付着することにより製品品質を低下させる、または、紙切れなど操業の不安定化を導くなどのピッチトラブルを引き起こす。
【0003】
従来から、このピッチトラブルを防止する方法として、分散剤や粘着防止剤としての有機薬品や吸着剤として無機薬品が一般に使用されている。無機薬品としてはタルクなどのケイ酸マグネシウム鉱物が製紙用ピッチ吸着剤として高い評価を得ており、広く利用されている。一般に、微粒子タルクのピッチ吸着は、タルク表面が親油性であることから起こるが、そのピッチ吸着能力は主として比表面積が影響しており、比表面積が大きいほどピッチ吸着量は多いと言われている(非特許文献1参照)。無機薬品としてはタルクの他、BET比表面積を特定したマグネシウム変性スメクタイト粘土鉱物を用いたピッチ吸着剤(特許文献1参照)、ホワイトカーボンから成るピッチ吸着剤(特許文献2参照)を用いる方法が開示されている。また、有機薬品としては、カチオン性ポリマーを用いたピッチコントロール剤(特許文献3参照)が開示されている。
【0004】
前述した中でもタルクはピッチ吸着剤として最も普通に使用されており、特に比表面積の大きいタルクを選定してピッチコントロール剤として使用していた。しかしながら、ピッチトラブルが多発した場合は、そのようなタルクの添加量を増加させて対応していたが、ピッチトラブルを完全に解消するに至っておらず、効果に限界が見られていた。
【0005】
【非特許文献1】林順之助、紙パ技協紙53(9)31頁〜39頁(1999)
【特許文献1】特開平6−65892号公報
【特許文献2】特開2002−88682号公報
【特許文献3】特開平7−126996号公報
【発明が解決しようとする課題】
【課題を解決するための手段】
本発明者らは、パルプ工程及び/または抄紙工程において、水滴を滴下後40秒後の水との接触角が120°以上であるタルクをピッチ吸着剤として添加することで、遊離しているピッチ分が減少し、ピッチトラブルが著しく解消されることを見出した。
【0006】
【発明の実施の形態】
本発明で使用するピッチ吸着剤は、水との接触角が120°以上であるタルクで、このようなタルクはピッチ分の吸着において顕著な効果を示す。タルクは表面が比較的親油性であり、パルプスラリー中の遊離ピッチを吸着することで遊離ピッチ量を減少させることができる。従来は、比表面積が大きいほどピッチ分と接触する総面積が多くなるので、比表面積がピッチ吸着能力に相関すると考えられていたが、それ以上にタルク表面と水との接触角がピッチの吸着能力に大きく影響していることが判明したのである。
【0007】
タルクは「含水ケイ酸マグネシウム」と呼ばれ、化学式は4SiO・3MgO・HOで表すことができる。化学組成は産地によって多少異なっており、理論値は、SiO64.4%、MgO31.8%、強熱減量(水分)4.7%の重量比となっている。
【0008】
本発明においてタルクの接触角は、例えば、以下のようにして測定する。DAT1100(Fibro社製)を用いて、サンプル挿入部にタルクを充填し、その表面に0.5μmの清水を滴下し、その水滴との接触角を経時的に測定する。この時、水滴を滴下して40秒後の接触角が120°以上であるものを、水との接触角が120°以上であるタルクと定義し、本発明のピッチ吸着剤とした。水との接触角が120°未満であるタルクでは、ピッチ分の吸着能力が十分ではない。
【0009】
本発明で使用するピッチ吸着剤の平均粒子径は1〜30μmのタルクが好ましい。平均粒子径が1μmより小さいと、ピッチの吸着能力に大きな差はないが、ピッチを吸着したタルクが紙中に保持されなくなり、ピッチを吸着したタルクが白水中を循環することとなり、系内に蓄積されてしまう。本来は、ピッチを吸着したタルクは紙に抄き込まれることにより、系内白水からピッチを除去する働きとなるので、紙に留まらない1μmより小さいものはピッチ除去効果がない。一方、粒子径が大きいタルクはピッチ分を吸着した後、紙に抄き込まれるが、平均粒子径が30μmを超える場合、その後の工程、例えば、乾燥工程で粒子の一部が紙表面から脱落してドライヤーのドラム表面に蓄積する等の問題を引き起こすこともある。また、得られる紙製品の品質面からも、平均粒子径が30μm以下であるタルクに比べ、表面性、平滑度や不透明度を低下させるため好ましくない。
【0010】
本発明において、ピッチ吸着剤は、絶乾パルプ重量当たり0.5重量%〜10重量%添加することが好ましい。被吸着物がある限りは、ピッチ吸着剤の添加量を増加させれば効果は得られるが、10重量%を超えて添加すると粉落ちやカスレなどの印刷トラブルが発生するため好ましくない。
【0011】
本発明においてピッチ分を減少させる対象となるものは、ピッチ分を含むパルプ原料、製紙原料、白水である。特に機械パルプや脱墨パルプを含む系である。
【0012】
本発明のタルクを添加する場所としては、ピッチ分の多い原料に添加する必要があり、抄紙工程の比較的上流のピッチ分が多いパルプ原料に添加することによってより高い効果が得られる。例えば、機械パルプ原料中の成分がトラブルを起こしている場合は、機械パルプ原料の製造工程で添加することが好ましい。機械パルプのピッチの場合はパルプ化される(木材組織から繊維へ、)工程において、木材組織(柔細胞などの樹脂分を含んでいる)から白水中に放出され、ピッチ粒子となり原料中に存在する。このピッチ粒子が凝集を起こしピッチトラブルとなる前にタルクに吸着させることが望ましい。すなわち、パルプ化工程の直後に添加することが好ましい。また、脱墨パルプの製造工程に白水洗浄工程が何段もあり、ピッチ分の多くは工程途中で除去されるので、除去できるものを吸着してパルプに持ちこまないように洗浄工程後の完成脱墨パルプに添加し、抄紙工程に入るピッチ分だけを吸着させることが望ましい。
【0013】
【実施例】
以下、実施例にて本発明を詳細に説明するが、本発明はこれらに限定されるものではない。
【0014】
[実施例1]
機械パルプスラリーをろ布で絞って得られた搾水(pH6.8)500mlに対して、水との接触角が120°以上であるタルクA(商品名:タルクC、日本タルク製)、タルクB(商品名:NK−PUC、兼松ケミカル製)、タルクC(商品名:ミクロコントロールII、日本ミストロン製)の10%懸濁液を、各々絶乾重量で搾水1Lに対して1gとなるように添加し、マグネットスターラーにより攪拌(15分間、600rpm)し、搾水中のピッチ成分をタルクに吸着させた。吸着させた後、遠心分離(2000G、15分)で搾水中のタルクを含む固形分を沈殿させ、上澄み液と固形分を分離した。上澄み液中に残留している総有機物量はTOCによって測定した。タルクを添加しない時のTOC値との差からタルクが吸着したTOC量を算出し、それをピッチ吸着量とした。また、このタルクの比表面積をBET法により測定した。これらの結果を表1及び図1、2に示した。
【0015】
[比較例1]
実施例1と同じ搾水を用い、水との接触角が120°未満であるタルクD(商品名:NTC−2、日本タルク製)、タルクE(サンプル1、日本タルク製)、タルクF(サンプル2、日本タルク製)、タルクG(商品名:NYA、日本タルク製)を使用して、実施例1と同じ条件でピッチ分を吸着させた。吸着後の搾水は同様に遠心分離で固形分と水溶液を分離し、吸着されなかったピッチが残存する水を分離した。上澄み液は、実施例1と同様にTOC値からピッチ吸着量を算出した。タルクの比表面積も同様にBET法により測定した。結果を表1及び図1、2に共に示した。
【0016】
【表1】

Figure 2004292998
【0017】
表1に示されるように、水との接触角が120°未満のタルクを添加した比較例1の場合、比表面積が大きくともピッチの減少量が明らかに小さいものもあるが、水との接触角が120°である実施例1のタルクを添加した場合では、比表面積が小さいものでも、比較例と比べて明らかにピッチ吸着量は大きい。タルク1gあたりのピッチ吸着量は4倍以上異なるものもあり、この差は明白である。また、図1に示されるようにピッチ吸着量と水との接触角は明らかに相関しているが、図2に示されるようにピッチ吸着量と比表面積には、まったく相関が見られない。
【0018】
[実施例2]
実際の製紙工場において、機械パルプに添加していたピッチ吸着剤を接触角が120°未満であるタルクG(商品名:NYA、日本タルク製)から、接触角が120°以上であるタルクG(商品名:NYA、日本タルク製)に置き換え、その時の抄紙工程におけるピッチ発生率を調査した。ピッチの発生率は、製品である新聞用紙の紙面のピッチ欠陥数で評価した。対象の新聞用抄紙機は日産約300トンの新聞用紙を製造し、ピッチ欠陥数は1日の生産量に対しての発生個数で表した。紙面ピッチはスポットディテクターにより自動計測されるもので、この数が増加することは品質が低下していることを示し、数が多くなると紙切れが多発する可能性もあるので、この数を低いレベルに保つことが品質上操業安定上、欠かせないと考えられている。表2に8日間の接触角が120°以上であるタルクの添加結果を示す。
【0019】
【表2】
Figure 2004292998
【0020】
表2より実機工程においても、水との接触角が120°以上のタルクは120°以下のタルクよりピッチ軽減効果が大きいことが明らかとなった。
【図面の簡単な説明】
【図1】タルクのピッチ吸着量と接触角の関係を示すグラフである。
【図2】タルクのピッチ吸着量と比表面積の関係を示すグラフである。[0001]
[Industrial applications]
The present invention relates to a pitch adsorbent for eliminating pitch troubles occurring in the production process of paper, pulp, etc., and more particularly, to a pitch exhibiting excellent adsorption performance for pitch components released into white water. For adsorbent.
[0002]
[Prior art]
In the paper and pulp manufacturing processes and recycled paper manufacturing processes, the resin component contained in the raw wood, the resin component added during paper processing and the adhesive component used as an adhesive, that is, pitch exists in the pulp slurry. In the pulp process, it accumulates on chests and pipe walls, and in the papermaking process, it contaminates papermaking tools such as wires and felt, and the deposits adhere to the product, deteriorating product quality, or causing paper breakage. Pitch troubles such as instability are caused.
[0003]
Conventionally, as a method for preventing this pitch trouble, an organic chemical as a dispersant or an anti-adhesive and an inorganic chemical as an adsorbent have been generally used. As inorganic chemicals, magnesium silicate minerals such as talc have been highly evaluated as pitch adsorbents for papermaking and are widely used. Generally, pitch adsorption of fine particle talc occurs because the talc surface is lipophilic, but its pitch adsorption ability is mainly affected by the specific surface area, and it is said that the larger the specific surface area, the larger the pitch adsorption amount. (See Non-Patent Document 1). A method using a pitch adsorbent using a magnesium-modified smectite clay mineral having a specified BET specific surface area (see Patent Document 1) and a pitch adsorbent made of white carbon (see Patent Document 2) in addition to talc as an inorganic chemical is disclosed. Have been. As an organic chemical, a pitch control agent using a cationic polymer is disclosed (see Patent Document 3).
[0004]
Among the above, talc is most commonly used as a pitch adsorbent, and particularly, talc having a large specific surface area is selected and used as a pitch control agent. However, when pitch troubles occur frequently, such talc was added by increasing the amount of such talc, but the pitch troubles were not completely eliminated, and the effect was limited.
[0005]
[Non-Patent Document 1] Junnosuke Hayashi, Paper-Paper Gikyo 53 (9) pages 31-39 (1999)
[Patent Document 1] JP-A-6-65892 [Patent Document 2] JP-A-2002-88682 [Patent Document 3] JP-A-7-126996 [Problems to be Solved by the Invention]
[Means for Solving the Problems]
In the pulp process and / or the papermaking process, the present inventors add talc having a contact angle of 120 ° or more with water 40 seconds after dropping a water drop as a pitch adsorbent, so that the pitch released is reduced. It was found that the pitch trouble was significantly reduced.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
The pitch adsorbent used in the present invention is talc having a contact angle with water of 120 ° or more, and such talc has a remarkable effect on adsorption of pitch. Talc has a relatively lipophilic surface and can reduce the amount of free pitch by adsorbing free pitch in the pulp slurry. Conventionally, it was thought that the larger the specific surface area, the larger the total area in contact with the pitch, so that the specific surface area was correlated with the pitch adsorption capacity. It turned out that it had a great effect on the ability.
[0007]
Talc is called “hydrated magnesium silicate”, and its chemical formula can be represented by 4SiO 2 .3MgO.H 2 O. The chemical composition is slightly different depending on the place of production, and the theoretical values are a weight ratio of 64.4% of SiO 2 , 31.8% of MgO, and 4.7% of loss on ignition (water).
[0008]
In the present invention, the contact angle of talc is measured, for example, as follows. Using a DAT1100 (manufactured by Fibro), talc is filled in the sample insertion portion, 0.5 μm of clear water is dropped on the surface, and the contact angle with the water droplet is measured with time. At this time, a talc having a contact angle of 120 ° or more after 40 seconds from the dropping of a water drop was defined as a talc having a contact angle with water of 120 ° or more, and was defined as a pitch adsorbent of the present invention. In the case of talc having a contact angle with water of less than 120 °, the adsorption capacity for the pitch is not sufficient.
[0009]
Talc having an average particle diameter of 1 to 30 μm is preferable for the pitch adsorbent used in the present invention. When the average particle diameter is smaller than 1 μm, there is no significant difference in the adsorption capacity of the pitch, but the talc adsorbing the pitch is not retained in the paper, and the talc adsorbing the pitch circulates in the white water. It will be accumulated. Originally, the talc having adsorbed the pitch functions to remove the pitch from the white water in the system by being made into paper, so that the talc having a pitch of less than 1 μm that does not remain on the paper has no pitch removing effect. On the other hand, talc having a large particle diameter is adsorbed on the paper after absorbing the pitch, but when the average particle diameter exceeds 30 μm, some of the particles fall off the paper surface in a subsequent step, for example, a drying step. This may cause problems such as accumulation on the drum surface of the dryer. Further, from the viewpoint of the quality of the obtained paper product, the surface property, smoothness and opacity are unfavorably reduced as compared with talc having an average particle diameter of 30 μm or less.
[0010]
In the present invention, the pitch adsorbent is preferably added in an amount of 0.5% by weight to 10% by weight based on the weight of the absolutely dried pulp. As long as there is an object to be adsorbed, the effect can be obtained by increasing the amount of the pitch adsorbent. However, if the amount exceeds 10% by weight, printing troubles such as powder dropping and blurring occur, which is not preferable.
[0011]
In the present invention, the target of decreasing the pitch component is a pulp raw material, a papermaking raw material, and white water containing the pitch component. Particularly, the system includes mechanical pulp and deinked pulp.
[0012]
As a place where the talc of the present invention is added, it is necessary to add the talc to a raw material having a large pitch, and a higher effect can be obtained by adding the talc to a pulp raw material having a large pitch content relatively upstream in the papermaking process. For example, when a component in the mechanical pulp raw material is causing a trouble, it is preferable to add the component in the manufacturing process of the mechanical pulp raw material. In the case of mechanical pulp pitch, in the process of pulping (from wood structure to fiber), it is released into white water from wood structure (containing resin such as parenchyma cells) and becomes pitch particles, which are present in the raw material I do. It is desirable that the pitch particles be adsorbed to talc before causing aggregation and causing pitch trouble. That is, it is preferably added immediately after the pulping step. In addition, there are many stages of white water washing process in the deinked pulp manufacturing process, and most of the pitch is removed during the process, so that the material that can be removed is adsorbed and removed after the washing process to prevent it from being brought into the pulp. It is desirable to add it to the ink pulp to adsorb only the pitch that enters the papermaking process.
[0013]
【Example】
Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.
[0014]
[Example 1]
Talc A (trade name: talc C, manufactured by Nippon Talc) having a contact angle with water of 120 ° or more with respect to 500 ml of squeezed water (pH 6.8) obtained by squeezing a mechanical pulp slurry with a filter cloth; B (trade name: NK-PUC, manufactured by Kanematsu Chemical) and 10% suspension of talc C (trade name: Microcontrol II, manufactured by Nippon Mistron) are each 1 g in absolute dry weight per 1 L of water squeezed. And the mixture was stirred with a magnetic stirrer (15 minutes, 600 rpm) to adsorb the pitch components in the squeezed water to talc. After the adsorption, the solid content including talc in the squeezed water was precipitated by centrifugation (2000 G, 15 minutes), and the supernatant and the solid content were separated. The total amount of organic substances remaining in the supernatant was measured by TOC. The amount of TOC to which talc was adsorbed was calculated from the difference from the TOC value when talc was not added, and this was defined as the amount of adsorbed pitch. The specific surface area of this talc was measured by the BET method. These results are shown in Table 1 and FIGS.
[0015]
[Comparative Example 1]
Talc D (trade name: NTC-2, manufactured by Nippon Talc), Talc E (sample 1, manufactured by Nippon Talc), and Talc F (using the same water extraction as in Example 1 and having a contact angle with water of less than 120 °) Using Sample 2, Nippon Talc) and Talc G (trade name: NYA, Nippon Talc), the pitch was adsorbed under the same conditions as in Example 1. In the water removal after the adsorption, the solid content and the aqueous solution were similarly separated by centrifugation, and the water in which the pitch not adsorbed remained was separated. The pitch adsorption amount of the supernatant was calculated from the TOC value in the same manner as in Example 1. The specific surface area of talc was similarly measured by the BET method. The results are shown in Table 1 and FIGS.
[0016]
[Table 1]
Figure 2004292998
[0017]
As shown in Table 1, in the case of Comparative Example 1 in which talc having a contact angle with water of less than 120 ° was added, although the decrease in pitch was clearly small even when the specific surface area was large, contact with water was not significant. When the talc of Example 1 having an angle of 120 ° is added, even if the talc has a small specific surface area, the pitch adsorption amount is clearly larger than that of the comparative example. The pitch adsorption amount per gram of talc is different by more than four times, and this difference is obvious. Also, as shown in FIG. 1, the pitch adsorption amount and the contact angle with water are clearly correlated, but as shown in FIG. 2, there is no correlation between the pitch adsorption amount and the specific surface area.
[0018]
[Example 2]
In an actual paper mill, the pitch adsorbent added to the mechanical pulp is changed from talc G having a contact angle of less than 120 ° (trade name: NYA, manufactured by Nippon Talc) to talc G having a contact angle of 120 ° or more ( (Trade name: NYA, manufactured by Nippon Talc), and the pitch generation rate in the papermaking process at that time was investigated. The pitch generation rate was evaluated based on the number of pitch defects on the surface of newsprint paper as a product. The target newspaper paper machine produced newsprint of about 300 tons per day, and the number of pitch defects was represented by the number of occurrences per day of production. The paper pitch is automatically measured by the spot detector, and an increase in this number indicates a decrease in quality.If the number increases, paper breakage may occur frequently. It is considered that maintaining this is indispensable for quality and operation stability. Table 2 shows the results of adding talc having a contact angle of 120 ° or more for 8 days.
[0019]
[Table 2]
Figure 2004292998
[0020]
Table 2 also shows that in the actual process, talc having a contact angle with water of 120 ° or more has a greater pitch reducing effect than talc having a contact angle of 120 ° or less.
[Brief description of the drawings]
FIG. 1 is a graph showing a relationship between a pitch adsorption amount of talc and a contact angle.
FIG. 2 is a graph showing a relationship between a talc pitch adsorption amount and a specific surface area.

Claims (2)

水滴を滴下後40秒後の水との接触角が120°以上であるタルクから成るピッチ吸着剤。A pitch adsorbent made of talc having a contact angle with water of 120 ° or more after 40 seconds from the dropping of a water drop. 水滴を滴下後40秒後の水との接触角が120°以上であるタルクから成るピッチ吸着剤を、パルプ工程及び/または抄紙工程に添加するピッチトラブル防止法。A pitch trouble prevention method in which a pitch adsorbent made of talc having a contact angle with water of 120 ° or more after 40 seconds from the dropping of water drops is added to the pulp step and / or the papermaking step.
JP2003088752A 2003-03-27 2003-03-27 Absorbent for pitch and method for preventing trouble by pitch Pending JP2004292998A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010242233A (en) * 2009-04-01 2010-10-28 Daio Paper Corp Newsprint paper
JP2012057270A (en) * 2010-09-08 2012-03-22 Daio Paper Corp Rolled newsprint paper and evaluation method of peel strength
EP2546410A1 (en) 2011-07-11 2013-01-16 Omya Development AG Hydrophobised calcium carbonate particles
EP2933375A1 (en) 2014-04-16 2015-10-21 Omya International AG Adsorbing and/or reduction of the amount of organic materials in an aqueous medium by using colloidal precipitated calcium carbonate
JP2016125146A (en) * 2014-12-26 2016-07-11 特種東海製紙株式会社 Wood pulp for glass plate inserting paper, and glass plate inserting paper
JP2020059966A (en) * 2019-12-04 2020-04-16 特種東海製紙株式会社 Wood pulp for glass plate interleaving paper and glass plate interleaving paper

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010242233A (en) * 2009-04-01 2010-10-28 Daio Paper Corp Newsprint paper
JP2012057270A (en) * 2010-09-08 2012-03-22 Daio Paper Corp Rolled newsprint paper and evaluation method of peel strength
EP2546410A1 (en) 2011-07-11 2013-01-16 Omya Development AG Hydrophobised calcium carbonate particles
WO2013007717A1 (en) 2011-07-11 2013-01-17 Omya Development Ag Hydrophobised calcium carbonate particles
EP2933375A1 (en) 2014-04-16 2015-10-21 Omya International AG Adsorbing and/or reduction of the amount of organic materials in an aqueous medium by using colloidal precipitated calcium carbonate
WO2015158657A1 (en) 2014-04-16 2015-10-22 Omya International Ag Adsorbing and/or reduction of the amount of organic materials in an aqueous medium by using colloidal precipitated calcium carbonate
US10046984B2 (en) 2014-04-16 2018-08-14 Omya International Ag Adsorbing and/or reduction of the amount of organic materials in an aqueous medium by using colloidal precipitated calcium carbonate
JP2016125146A (en) * 2014-12-26 2016-07-11 特種東海製紙株式会社 Wood pulp for glass plate inserting paper, and glass plate inserting paper
JP2020059966A (en) * 2019-12-04 2020-04-16 特種東海製紙株式会社 Wood pulp for glass plate interleaving paper and glass plate interleaving paper

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