【発明の詳細な説明】[Detailed description of the invention]
(イ) 発明の目的
（産業上の利用分野）
この発明は、ピツチ分散剤に関する。更に詳し
くは、紙、パルプ等の抄造のクローズ化に伴ない
生じるピツチ障害を抑制するピツチ分散剤に関す
る。
（従来の技術）
最近、紙、パルプの抄造において、本資源節約
のため、抄紙系のクローズ化が盛んに行われるよ
うになつている。しかしながら、クローズ化が進
むにつれてピツチ（ただし、ここで言うピツチと
は、通常紙パルプ製造工程において木材細胞から
剥離した天然樹脂又はガム質ピツチもしくはその
他の添加剤に由来する有機物を主体とする小球状
の粘着性凝集物を意味する）の生成頻度が増加す
るに至つている。
なお、現在の学説によれば、抄紙系でのピツチ
障害の発生には、コロイダルピツチの急激な凝集
巨大化が大きい役割を演じていると述べられてい
る。即ちこのコロイダルピツチが何等かの外的作
用、例えば大きい剪断力、過剰の硫酸バンドの添
加、急激なPHを変化等の作用を受けて、コロイド
が破壊され、以要以上のピツチ凝集巨大化が起つ
てピツチトラブルが生じると言われている。そし
て、このピツチは抄紙工程におけるチエスト、ピ
ーター、ワイヤー、フエルト、ロール等の製紙機
械設備各所に凝集付着して作業能率を低下させた
り、あるいは製品中に混入してパルプシートまた
は紙の汚点または穴の原因となつたり、はなはだ
しい場合には操業を停止せしめるに至るなど種々
のピツチ障害をもたらす。
従来、このようなピツチ障害の防止対策として
種々の方法が採用されている。たとえば、タル
ク、硅藻土のごとき多孔性無機性質を抄紙系に微
粉末の状態で投入し、系に存在するピツチを吸着
せしめるとともに、紙料中にこの無機物質を抄き
込む方法、分散剤を投入して、ピツチをできる
だけ微細粒子の状態に保持し、コロイド状のピツ
チの凝集巨大化を防止する方法等がある。前記
の方法において用いられる分散剤としては、ポリ
オキシエチレンアルキルフエノールエーテル等の
ノエオン系界面活性剤が多く利用されている。
（発明が解決しようとする問題点）
しかしながら、上記のごとき分散剤を用いた場
合、水系のクローズ化が進むにつれて、界面活性
剤が系中に累積すること、起泡性の大きいこと等
の問題点が生じてくる。そのため、最近、他種の
分散剤、とくに水溶性高分子に注目が向けられつ
つある。例えばRohm＆Hass社はポリビニルピ
ロリドンのホモポリマーあるいはコポリマーをピ
ツチ分散剤として提案している（USP3081219）。
日本に於て世界にさきがけて、合成繊維に利用
されたポリビニルアルコールは水に可溶性の重合
物であつて低廉なる原料資材と言える。かかるポ
リビニルアルコール（以下にPVAと略称）は紙
質増強剤として紙の抄造に使用されていることは
公知に属するが、ピツチの分散剤ないしは保護コ
ロイド剤として利用して有効なる効果を得た事実
は見当らず、本発明者等はこの点に着目して、上
記問題点を解決すべく鋭意研究した結果、興味あ
る事実を見出しこの発明に到達した。
(ロ) 発明の構成
いわゆるPVAは単体であるビニルアルコール
を重合して得られるものではなく、ポリ酢酸ビニ
ルのけん化によつて製造されている。従つて完全
なるけん化は期く難く、幾分のエステル結合を分
子中に残存せしめるが故に１種のビニルアルコー
ル−酢酸ビニル共重合体と言える、通常、かよう
な共重合体は単にPVAと呼ばれている。このこ
とを式で示すと以下の通りとなる。
（ｎ又はｍ＋ｌは重合度に相当する）
すなわち、市販の高純度のPVAは95〜99モル
％のけん化度を示し、100モル％のけん化度のも
のは存在しない。なお、ここでけん化度というの
は、ポリビニルアルコール試験方法JISK 6726−
1977に記載するけん化度であつて部分けん化物で
あるPVAに於て、水酸基の割合をモル％で表わ
した値のことで、上記式のｍ／ｍ＋ｌ×100で得られ
る値に相当する。
本発明者らは、かような部分けん化物に相当す
る市販のPVAのけん化度とピツチ分散能（試験
法は後述）との関係を求め、
けん化度95モル％以上の所謂純PVAに近い
PVAにあつてはピツチ分散能を全然保有しな
い、
けん化度90〜85モル％程度のPVAになると
ピツチ分散能を示し始める。そして其の分散能
はパルプ工業界に於て広く使用されているピツ
チ分散剤のそれに匹敵する、
けん化度70〜80モル％のPVAになると更に
大きい分散能を示しの場合のPVAにより１
オーダー高い分散能を発揮する、
かようなピツチ分散能の効果はけん化度40モ
ル％のものまで認められ、けん化度が約40モル
％以下になると実質的に水に不溶となり使用に
供し得ない、
という事実を見出した。
かくしてこの発明によれば、
式（）：
で表わされる構成単位と、
式（）：
で表わされる構成単位からなり、式（）で表わ
される構成単位が約70〜80モル％、式（）で表
わされる構成単位が約30〜20モル％である水溶性
のポリビニルアルコールを有効成分とするピツチ
分散剤が提供される。
上記PVAの重合度としては特に限定されない
が、少なくとも水に溶解して透明になる溶液をつ
くる程度のものであればよく、通常約300〜2000
のものを好適に用いることができる。
この発明で用いられるPVAの量的使用範囲は、
存在するピツチの量により左右されるが、通常、
パルプに対して、0.001〜0.2重量％の添加により
充分な効果を挙げることができ、0.01〜0.03重量
％の添加が好ましい。また他の公知のピツチ分散
剤、たとえばノニオン系界面活性剤などとの併用
も可能である。
また、この発明の有効成分であるPVAは、適
当な濃度となるように水に溶解して使用できる。
（実施例）
以下、実施例を挙げてこの発明を説明する。
（ピツチの組成）
Burk、JM氏はNon−microbiological deposit
problems and their systematic control.
Southern pulp Paper Mfr42(12)：19−21（Dec
1979）に於てコロイダルピツチは40〜50％の樹脂
酸、15〜20％の脂肪酸とステロールよりなり残り
はステリルエステル、ヂ及びトリグリセライドよ
りなることを報告している。そして本発明の実施
例で用いる某製紙工場のワイヤーに付着したピツ
チは、そのエタノール抽出したものにつき分析を
行つた結果、樹脂酸40％、脂肪酸20％、不ケン化
物20％、脂肪酸エステル20％であつたため両者の
分析値が似ているので本発明においては上記組成
のワイヤー付着ピツチをエタノールに加温溶解し
た後、過して供試ピツチ溶液とした。
実施例 １
よく洗浄されたフエルト10cm×35cmを内張りし
た１のビーカーに、必要量のPVAを溶解した
水溶液490mlを入れ、50℃に加温し、回転速度
98rpmで、後記供試ピツチのアルコール液を添加
する。次いで、これに後記硫酸バンド10ml（液が
20ppmのアルミニウム濃度を示すようにする）を
添加する。更に１時間撹拌をつづけた後、フエル
トを取出し、付着したピツチをアルコールベンゼ
ン（１：２容積）で抽出し、添加ピツチ量に対す
るピツチの付着率を求める。なお、本発明のピツ
チ分散剤無添加（ブランクテスト）の付着率は
85.0％であつた。以下の式で付着率より付着防止
率を求める。
付着防止率＝Ao−Ax／Ao×100
Ax：ｘ％のピツチ分散剤の添加時のピツチ付着
率
Ao：ピツチ分散剤無添加のときのピツチ付着率
なお、本実施例においては、付着率が80％を示
すPVAの添加率（対供試ピツチ）をもつてPVA
の分散能指数とした。言い換えると、該指数が小
さいほどピツチ分散剤として優れたものであると
言える。また実施例に用いられた供試ピツチ及び
硫酸バンド水溶液は以下の通りである。
Γ供試ピツチ：
某製紙工場のワイヤー付着ピツチをエタノー
ルに加温溶解して不溶部分を別後、エタノー
ルを補充して10ml中に0.645ｇの有効成分を含
むようにした。
Γ硫酸バンド水溶液：
11ｇのAl2（SO4）3・13〜14H2Oを水に溶解し
て1000mlとした、10mlの水溶液は0.01ｇのAlを
含有。
実施例１で用いたピツチ分散剤は、No.12の
PVA〔粘度：６〜9cps（ヘプラー粘度計、４％水
溶液20℃）、けん化度（モル％）：71.0〜75.0〕
を、供試ピツチに対して10、４、２、１、0.4、
0.2（％）の種々の添加濃度にて試験を行い、前記
付着率及び付着防止率を求めた。その結果を第１
表に示す。
(a) Purpose of the invention (industrial field of application) This invention relates to a pitch dispersant. More specifically, the present invention relates to a pitch dispersant that suppresses pitch defects that occur as a result of closed paper manufacturing of paper, pulp, and the like. (Prior Art) Recently, in paper and pulp manufacturing, in order to save natural resources, closed paper making systems have become popular. However, as the process of closed production progresses, pitch (here, "pitch" refers to small spherical particles consisting mainly of organic matter derived from natural resin or gummy pitch or other additives that are exfoliated from wood cells during the paper pulp manufacturing process). (meaning sticky aggregates) are occurring with increasing frequency. According to current theories, it is stated that the rapid aggregation of colloidal pitches to a large size plays a major role in the occurrence of pitch failures in papermaking systems. That is, when this colloidal pitch is subjected to some external action, such as a large shearing force, addition of excessive sulfuric acid band, or sudden change in pH, the colloid is destroyed and the pitch aggregate becomes larger than necessary. It is said that this will cause pitch trouble. During the papermaking process, this pitch can aggregate and adhere to papermaking machine equipment such as cheeseboards, pipes, wires, felts, rolls, etc., reducing work efficiency, or it can get mixed into the product and cause stains or holes on pulp sheets or paper. This can lead to a variety of pitfalls, including causing problems, and in extreme cases, leading to the suspension of operations. Conventionally, various methods have been adopted as measures to prevent such pitch failures. For example, porous inorganic materials such as talc and diatomaceous earth are introduced into the papermaking system in the form of fine powder to adsorb the pitch present in the system, and methods for incorporating these inorganic materials into the paper stock, as well as dispersing agents, are used. There is a method of keeping the pitches in the fine particle state as much as possible by injecting them, and preventing the colloidal pitches from agglomerating and becoming huge. As the dispersant used in the above method, noeon surfactants such as polyoxyethylene alkyl phenol ether are often used. (Problems to be Solved by the Invention) However, when using the above dispersant, as the aqueous system becomes more closed, the surfactant accumulates in the system, and there are problems such as high foaming properties. A point appears. Therefore, other types of dispersants, particularly water-soluble polymers, have recently attracted attention. For example, Rohm & Hass has proposed homopolymers or copolymers of polyvinylpyrrolidone as pitch dispersants (USP 3081219). Polyvinyl alcohol, which was used in synthetic fibers in Japan for the first time in the world, is a water-soluble polymer and can be said to be an inexpensive raw material. It is well known that polyvinyl alcohol (hereinafter abbreviated as PVA) is used in paper making as a paper quality enhancer, but there is no evidence that it has been used as a dispersant or protective colloid for pitch powder to achieve effective results. However, the inventors of the present invention paid attention to this point and conducted intensive research to solve the above-mentioned problems. As a result, they discovered an interesting fact and arrived at the present invention. (B) Structure of the Invention So-called PVA is not obtained by polymerizing vinyl alcohol, which is a simple substance, but is produced by saponifying polyvinyl acetate. Therefore, complete saponification is difficult to achieve, and since some ester bonds remain in the molecule, it can be said to be a type of vinyl alcohol-vinyl acetate copolymer. Usually, such a copolymer is simply called PVA. It is. This can be expressed as follows. (n or m+l corresponds to the degree of polymerization) That is, commercially available high-purity PVA shows a saponification degree of 95 to 99 mol%, and there is no one with a saponification degree of 100 mol%. Note that the degree of saponification here refers to polyvinyl alcohol test method JISK 6726-
1977, which is a value expressed in mole percent of the proportion of hydroxyl groups in PVA, which is a partially saponified product, and corresponds to the value obtained by m/m+l×100 in the above formula. The present inventors determined the relationship between the degree of saponification of commercially available PVA, which corresponds to such a partially saponified product, and its pitch dispersion ability (the test method will be described later), and found that it is close to so-called pure PVA with a degree of saponification of 95 mol% or more.
PVA has no pitch dispersion ability at all, but PVA with a saponification degree of 90 to 85 mol% begins to exhibit pitch dispersion ability. Its dispersing ability is comparable to that of Pitz dispersant, which is widely used in the pulp industry. PVA with a saponification degree of 70 to 80 mol% shows an even greater dispersing ability.
The effect of such pitch dispersing ability, which exhibits an orderly high dispersing ability, is observed up to a saponification degree of 40 mol%, and when the saponification degree is less than about 40 mol%, it becomes virtually insoluble in water and cannot be used. , I found out the fact that. Thus, according to the invention, the formula (): The constituent unit represented by and the formula (): The active ingredient is a water-soluble polyvinyl alcohol consisting of the structural units represented by the formula () and approximately 70 to 80 mol% of the structural units represented by the formula () and approximately 30 to 20 mol% of the structural units represented by the formula (). A pitch dispersant is provided. The degree of polymerization of the above-mentioned PVA is not particularly limited, but it may be at least as long as it dissolves in water to form a transparent solution, and is usually about 300 to 2000.
The following can be suitably used. The quantitative usage range of PVA used in this invention is:
It depends on the amount of pituti present, but usually
Sufficient effects can be obtained by adding 0.001 to 0.2% by weight of the pulp, and addition of 0.01 to 0.03% by weight is preferred. It is also possible to use it in combination with other known pitch dispersants, such as nonionic surfactants. Furthermore, PVA, which is the active ingredient of this invention, can be used by dissolving it in water to an appropriate concentration. (Example) The present invention will be described below with reference to Examples. (Composition of Pituchi) Burk, JM is a non-microbiological deposit.
problems and their systematic control.
Southern pulp Paper Mfr42(12): 19−21 (Dec.
(1979) reported that colloidal pitch consists of 40 to 50% resin acids, 15 to 20% fatty acids and sterols, and the remainder consists of steryl esters, di, and triglycerides. The pitch that adhered to the wire of a certain paper mill used in the examples of the present invention was extracted with ethanol and analyzed and found to contain 40% resin acids, 20% fatty acids, 20% unsaponifiables, and 20% fatty acid esters. Since the analytical values of the two were similar, in the present invention, the wire-attached pitch of the above composition was dissolved in ethanol by heating, and then filtered to obtain a test pitch solution. Example 1 490 ml of an aqueous solution containing the required amount of PVA was poured into a beaker lined with well-washed felt 10 cm x 35 cm, heated to 50°C, and the rotation speed was increased.
At 98 rpm, add the alcohol solution from the sample pitch described below. Next, add 10 ml of sulfuric acid band (liquid) to this.
(to give an aluminum concentration of 20 ppm). After continuing stirring for an additional hour, the felt was taken out, the adhering pitches were extracted with alcohol benzene (1:2 volume), and the adhesion rate of pitches relative to the amount of pitches added was determined. In addition, the adhesion rate of the present invention without the addition of pitch dispersant (blank test) is
It was 85.0%. Calculate the adhesion prevention rate from the adhesion rate using the following formula. Adhesion prevention rate = Ao - Ax / Ao × 100 Ax: Pitch adhesion rate when x% of pitch dispersant is added Ao: Pitch adhesion rate when no pitch dispersant is added In this example, the adhesion rate is PVA with a PVA addition rate of 80% (vs. sample pitch)
was used as the dispersion power index. In other words, it can be said that the smaller the index, the better the pitch dispersant. Further, the test pitches and sulfate band aqueous solutions used in the examples are as follows. Γ test pitch: A wire-adhered pitch from a certain paper mill was dissolved in ethanol by heating, the insoluble portion was separated, and ethanol was replenished so that 0.645 g of the active ingredient was contained in 10 ml. Γ Sulfuric acid band aqueous solution: 11 g of Al 2 (SO 4 ) 3 ·13-14H 2 O was dissolved in water to make 1000 ml. 10 ml of the aqueous solution contained 0.01 g of Al. The pitch dispersant used in Example 1 was No. 12.
PVA [Viscosity: 6 to 9 cps (Hepler viscometer, 4% aqueous solution at 20°C), saponification degree (mol%): 71.0 to 75.0]
For the test pitch, 10, 4, 2, 1, 0.4,
Tests were conducted at various additive concentrations of 0.2 (%), and the adhesion rate and adhesion prevention rate were determined. The result is the first
Shown in the table.
【表】
得られた結果から、片対数のグラフ用紙の対数
表示側を横軸としてPVAの添加率、縦軸には付
着防止率をとつた。その結果を第１図に示す。前
記６点のプロツトしたデーターより滑らかな曲線
を引き、付着防止率80％のときのPVAの添加率
をPVAの分散能指数とした。
No.12のPVAの分散能指数0.64
実施例２〜５及び比較例１〜10
PVAの種類を変えた以外は、実施例１と同様
にしてそれぞれの分散能指数を求めた。その結果
を実施例１と合わせて第２表に示す。
なお、比較例１〜４に用いた分散剤は供試ピツ
チに対して60、10、４、２（％）の添加濃度にて
試験を行つたが、比較例１〜３は、付着率がほぼ
80％を越えており、比較例４に至つては水に溶け
ないため、ピツチ分散能が実質的に無いので分散
能指数を∞とした。[Table] Based on the results obtained, the PVA addition rate was plotted on the horizontal axis with the logarithmic side of the semi-logarithmic graph paper, and the adhesion prevention rate was plotted on the vertical axis. The results are shown in FIG. A smooth curve was drawn from the data plotted at the six points above, and the PVA addition rate when the adhesion prevention rate was 80% was defined as the PVA dispersion ability index. Dispersion power index of No. 12 PVA 0.64 Examples 2 to 5 and Comparative Examples 1 to 10 The dispersion power index of each was determined in the same manner as in Example 1 except that the type of PVA was changed. The results are shown in Table 2 together with Example 1. In addition, the dispersants used in Comparative Examples 1 to 4 were tested at addition concentrations of 60, 10, 4, and 2 (%) to the test pitch, but in Comparative Examples 1 to 3, the adhesion rate was almost
Since Comparative Example 4 is not soluble in water and has substantially no pitch dispersing ability, the dispersing ability index was set as ∞.
【表】【table】
【表】
以上の結果から明らかなように、けん化度が約
90をこえるか、約40より小さいPVAは実質的に
ピツチ分散剤としての効果はなく、70〜80になる
と非常に優れたピツチ分散能を示す。
(ハ) 発明の効果
特定の範囲のけん化度を有する水溶性のPVA
を有効成分とした本発明のピツチ分散剤は、工程
水の回収率を高くしたクローズ化と言つた悪条件
の抄紙工程でも優れたピツチ分散効果を有してお
り、工程管理が容易になるとともに、他のピツチ
分散剤と比較した場合、経済的にも安価に優れた
ものである。[Table] As is clear from the above results, the degree of saponification is approximately
PVA greater than 90 or less than about 40 has virtually no effect as a pitch dispersant, while PVA of 70 to 80 exhibits very good pitch dispersing ability. (c) Effects of the invention Water-soluble PVA having a saponification degree within a specific range
The pitch dispersant of the present invention, which contains as an active ingredient, has an excellent pitch dispersing effect even in papermaking processes under adverse conditions such as closed papermaking with a high recovery rate of process water, making process control easier and When compared with other pitch dispersants, it is economically superior and inexpensive.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は、実施例１における本発明のピツチ分
散剤の分散能指数を示す片対数グラフである。
FIG. 1 is a semi-log graph showing the dispersibility index of the pitch dispersant of the present invention in Example 1.