JP2011184839A - Flame-retardant wet-laid nonwoven fabric and production method therefor - Google Patents
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本発明は、ポリフェニレンサルファイド繊維と防炎レーヨン繊維とからなる難燃性湿式不織布（混抄紙）とその製造方法に関するものである。 The present invention relates to a flame-retardant wet nonwoven fabric (mixed paper) made of polyphenylene sulfide fiber and flameproof rayon fiber, and a method for producing the same.
耐熱性と耐薬品性に優れているポリフェニレンサルファイド繊維（以下、ＰＰＳ繊維と称することがある。）は、高機能繊維として用途が拡大しており、具体的に、高温のガス集塵に用いるフィルター、工業製品の乾燥工程に使用するドライヤー用カンバス、およびオフィス用コピー機のロール拭き取り材などの用途に用いられており、今後も適用用途の広がりを見せるとされる。 Polyphenylene sulfide fibers (hereinafter sometimes referred to as PPS fibers), which are excellent in heat resistance and chemical resistance, are expanding their use as high-performance fibers. Specifically, filters used for high-temperature gas dust collection It is used in applications such as dryer canvases used in the drying process of industrial products and roll wiping materials for office copiers.
ＰＰＳ繊維が用途を拡大しつつある中で、ＰＰＳ繊維が融点を有し２８５℃の温度で溶融するという特徴があるため、非溶融性が必要な防炎素材としての適用はなされていない。それは、ＰＰＳ繊維は着炎すると繊維が溶融して孔が開き、炎が貫通する性質を有するからである。 While PPS fibers are expanding their uses, the PPS fibers have a feature that they have a melting point and melt at a temperature of 285 ° C. Therefore, they are not applied as flameproof materials that require non-melting properties. This is because the PPS fiber has a property that when the flame arrives, the fiber melts to open a hole and the flame penetrates.
一般的な技術として、着炎しても孔が開かない性質を付与するために、繊維自体に後加工を施して難燃化する技術が存在する。後加工による繊維の難燃化技術としては、チタン、ジルコニウム化合物および有機リン化合物等に代表される難燃剤を繊維そのものに固着させる手法が知られている。しかしながら、後加工による難燃化技術では難燃剤の脱落が生じやすく、更なる改良が求められている。 As a general technique, there is a technique in which the fiber itself is post-processed to make it flame-retardant in order to impart a property in which holes do not open even when flaming. As a technique for making a fiber flame-retardant by post-processing, a technique of fixing a flame retardant represented by titanium, a zirconium compound, an organic phosphorus compound, or the like to the fiber itself is known. However, the flame retardant technology by post-processing tends to cause the flame retardant to drop off, and further improvement is required.
また、昨今では、繊維形成性ポリマーに難燃剤を練り込んでポリマーを改質し、しかる後に紡糸し繊維化する手法も採用されるが、難燃剤を練り込んでＰＰＳポリマーを改質する手法については、製造方法の困難さから実用化に到っていない。 Also, in recent years, a method of modifying a polymer by kneading a flame retardant into a fiber-forming polymer and then spinning and fiberizing is adopted, but a method of modifying a PPS polymer by kneading a flame retardant. Has not yet been put into practical use due to the difficulty of the manufacturing method.
一方で、ＰＰＳ繊維以外の他の繊維素材に着目すると、レーヨン繊維に代表されるセルロース繊維は天然素材として広く活用されているが、セルロース繊維は非常に燃えやすいために難燃化する技術が必須である。このことから、セルロース中に難燃成分を混合し、しかる後に紡糸し繊維化する技術が提案されている（特許文献１参照。）。この提案では、難燃剤として珪素やマグネシウム成分を選択的に使用することにより、着炎してもハロゲン元素に由来する有害物質の発生が無い防炎レーヨン繊維を提供できるとしている。 On the other hand, when paying attention to other fiber materials other than PPS fibers, cellulose fibers represented by rayon fibers are widely used as natural materials, but since cellulose fibers are very flammable, technology to make them flame-retardant is essential. It is. For this reason, a technique has been proposed in which a flame-retardant component is mixed in cellulose, and then spun to fiber (see Patent Document 1). According to this proposal, by selectively using a silicon or magnesium component as a flame retardant, it is possible to provide a flame-proof rayon fiber that does not generate harmful substances derived from halogen elements even when it is flared.
しかしながら、特許文献１に記載の提案で用いられる防炎レーヨン繊維で不織布を構成して燃焼試験をすると、確かに着炎して孔が開かないことから好ましい手段であるが、不織布全体が収縮して原型を留めないという課題がある。すなわち、この提案では、防炎レーヨン繊維自体が溶融しないので、不織布に着炎しても孔は開かないが、防炎レーヨン繊維同士の接合が弱いために、着炎時の熱で大きく収縮するという課題があった。 However, when a non-woven fabric is composed of flameproof rayon fibers used in the proposal described in Patent Document 1 and a combustion test is performed, it is a preferable means because it surely flames and does not open a hole, but the entire non-woven fabric shrinks. Therefore, there is a problem that the prototype is not kept. That is, in this proposal, since the flameproof rayon fiber itself does not melt, a hole is not opened even if flame is applied to the nonwoven fabric, but since the bonding between the flameproof rayon fibers is weak, the flameproof shrinkage is greatly contracted by the heat at the time of flame ignition. There was a problem.
また、ＰＰＳ繊維と難燃化されたレーヨン繊維を組み合わせて使用する方法が提案されている（特許文献２参照。）。この方法は、ＰＰＳ繊維と難燃レーヨン繊維の混合不織布に、難燃剤とバインダーを有する接着剤を用いて接着させるものであり、層間剥離の無い難燃不織布を提供するものである。 In addition, a method of using a combination of PPS fibers and flame retardant rayon fibers has been proposed (see Patent Document 2). This method is to bond a PPS fiber and a flame retardant rayon fiber to a mixed nonwoven fabric using an adhesive having a flame retardant and a binder, and provide a flame retardant nonwoven fabric without delamination.
しかしながら、特許文献２に記載の手法では、接着剤を用いて不織布を接着させており、特にガラス転移温度が４０℃以下のバインダーが好ましいとしていることと、更には、不織布の見掛け密度を０．２５ｇ／ｃｍ３より低く設計することにより、接着剤の内部侵入が達成できるとしている。すなわち、この提案では、ガラス転移温度の低い接着成分を必要とするので難燃不織布全体で見ると耐熱性が悪くなり、かつ、見掛け密度を０．２５ｇ／ｃｍ３よりも高く設計し緻密な難燃不織布を提供できるものではなかった。 However, in the method described in Patent Document 2, the nonwoven fabric is bonded using an adhesive, and a binder having a glass transition temperature of 40 ° C. or lower is particularly preferable. By designing it to be lower than 25 g / cm 3 , internal penetration of the adhesive can be achieved. That is, in this proposal, an adhesive component having a low glass transition temperature is required, so that the heat resistance is deteriorated when viewed as a whole of the flame retardant nonwoven fabric, and the apparent density is designed to be higher than 0.25 g / cm 3 and is difficult to be precise. It was not possible to provide a non-woven fabric.
また、別の技術として、ＰＰＳ繊維からなる密度の高い不織布が提案されている（特許文献３参照。）。この提案は、ＰＰＳ繊維の中途配向繊維をＰＰＳ繊維の配向繊維と混合し、中途配向繊維の軟化点以上の温度で熱処理することにより、中途配向繊維が大きく熱収縮して不織布が高密度化するとともに、中途配向繊維が軟化して不織布を構成する単繊維を部分的に接着せしめるものである。 As another technique, a high-density nonwoven fabric made of PPS fibers has been proposed (see Patent Document 3). In this proposal, the mid-oriented fibers are mixed with the oriented fibers of the PPS fibers and heat-treated at a temperature equal to or higher than the softening point of the mid-oriented fibers, so that the mid-oriented fibers are largely heat-shrinked and the nonwoven fabric is densified. At the same time, the mid-oriented fibers soften and the single fibers constituting the nonwoven fabric are partially bonded.
しかしながら、この方法で得られる不織布は、高密度化しているものの、ＰＰＳ繊維単独で形成されることから着炎時には溶融して孔が開き、炎が貫通するという課題は解決できないものであった。 However, although the nonwoven fabric obtained by this method is densified, since it is formed of PPS fibers alone, the problem of melting and opening a hole when the flame arrives and the penetration of the flame cannot be solved.
そこで本発明の目的は、上記従来技術のもつ課題に鑑み、ＰＰＳ繊維と防炎レーヨン繊維とからなる緻密な湿式不織布であって、難燃性を有して着炎しても孔が開かず、更に着炎したときの熱に曝されても不織布の収縮が極めて小さい難燃性湿式不織布を提供することにある。 Accordingly, an object of the present invention is a dense wet nonwoven fabric composed of PPS fibers and flameproof rayon fibers in view of the above-mentioned problems of the prior art, and has flame retardancy and does not open a hole even when flame is applied. Another object of the present invention is to provide a flame retardant wet nonwoven fabric in which the shrinkage of the nonwoven fabric is extremely small even when exposed to heat when flame is applied.
本発明は、上記目的を達成せんとするものであり、本発明の難燃性湿式不織布は、ＰＰＳ繊維と防炎レーヨン繊維とからなる湿式不織布であって、前記ポリフェニレンサルファイド繊維の少なくとも一部が前記防炎レーヨン繊維と融着して結合しており、０．３〜１．２ｇ／ｃｍ３の範囲内にある緻密な見掛け密度を有することを特徴とするものである。 The present invention is intended to achieve the above object, and the flame retardant wet nonwoven fabric of the present invention is a wet nonwoven fabric composed of PPS fibers and flameproof rayon fibers, wherein at least a part of the polyphenylene sulfide fibers are present. The flameproof rayon fiber is fused and bonded, and has a dense apparent density in the range of 0.3 to 1.2 g / cm 3 .
本発明の難燃性湿式不織布の好ましい態様によれば、前記のポリフェニレンサルファイド繊維の少なくとも一部は、未延伸ポリフェニレンサルファイド繊維を含み、該未延伸ポリフェニレンサルファイド繊維と前記の防炎レーヨン繊維とが融着して結合していることである。 According to a preferred aspect of the flame retardant wet nonwoven fabric of the present invention, at least a part of the polyphenylene sulfide fiber includes unstretched polyphenylene sulfide fiber, and the unstretched polyphenylene sulfide fiber and the flameproof rayon fiber are melted. It is wearing and combining.
本発明の難燃性湿式不織布の好ましい態様によれば、前記の防炎レーヨン繊維は、湿式不織布を構成する繊維全体の３５〜９０重量％を占めることである。 According to the preferable aspect of the flame-retardant wet nonwoven fabric of this invention, the said flame-proof rayon fiber is 35 to 90 weight% of the whole fiber which comprises a wet nonwoven fabric.
本発明の難燃性湿式不織布の好ましい態様によれば、前記の防炎レーヨン繊維は、珪素またはマグネシウムを含み、かつ、ハロゲン原子または燐原子を含まないことである。 According to a preferred aspect of the flame retardant wet nonwoven fabric of the present invention, the flameproof rayon fiber contains silicon or magnesium and does not contain a halogen atom or a phosphorus atom.
本発明の前記の難燃性湿式不織布は、前記の未延伸ポリフェニレンサルファイド繊維と前記の防炎レーヨン繊維とを混合して抄紙加工し、しかる後に加熱・加圧加工を施すことにより製造される。 The flame-retardant wet nonwoven fabric of the present invention is manufactured by mixing the unstretched polyphenylene sulfide fiber and the flameproof rayon fiber, and then paper-processing and then heating / pressurizing.
防炎レーヨン繊維単独で構成される不織布等の布帛は接炎時に溶融しない特徴を有するが、接炎時の熱で収縮するという問題があった。これに対し、本発明によれば、ＰＰＳ繊維と防炎レーヨン繊維とをＰＰＳ未延伸糸の融着で結合させ、特定の高い見掛け密度に設計した湿式不織布とすることにより、接炎時にも孔が開かず、尚且つ熱による収縮も同時に抑制することが可能な難燃性湿式不織布が得られる。また、防炎レーヨン繊維がハロゲン原子や燐原子を含まず、ＰＰＳ繊維も同様の原子を含まないことから、接炎時にダイオキシンなどの有毒ガス発生を抑制することができる効果も奏する。 Fabrics such as non-woven fabric composed of flameproof rayon fibers alone have a feature that they do not melt at the time of flame contact, but there is a problem that they shrink due to heat at the time of flame contact. On the other hand, according to the present invention, a PPS fiber and a flameproof rayon fiber are bonded by fusion of unstretched PPS yarns to form a wet nonwoven fabric designed to have a specific high apparent density. Can be obtained, and a flame-retardant wet nonwoven fabric that can simultaneously suppress shrinkage due to heat can be obtained. Further, since the flameproof rayon fiber does not contain halogen atoms or phosphorus atoms, and the PPS fiber does not contain similar atoms, the effect of suppressing the generation of toxic gases such as dioxins at the time of flame contact is also achieved.
本発明者らは、ＰＰＳ繊維を用いてなる不織布において、難燃性能を有して着炎時に孔が開かない難燃不織布とするには防炎レーヨン繊維との混抄で改善することを見出した。本発明者らは、更に、防炎レーヨン繊維単独の紙であったり、ＰＰＳ繊維と防炎レーヨン繊維とを単純に混合しただけの湿式不織布では着炎時の収縮が大きいという問題点に着目し、かかる問題が、湿式不織布を構成する繊維同士の結合が弱いことや湿式不織布の密度が大きいことに起因するため、未延伸ＰＰＳ繊維を融着させて防炎レーヨン繊維と結合することで解決することを見出し、本発明に到達した。 The present inventors have found that, in a nonwoven fabric using PPS fibers, it is improved by blending with flameproof rayon fibers in order to obtain a flame retardant nonwoven fabric that has flame retardancy and does not open a hole when flaming. . Furthermore, the present inventors pay attention to the problem that the shrinkage at the time of flame is large in the case of a paper made of flameproof rayon fiber alone or a wet nonwoven fabric in which PPS fiber and flameproof rayon fiber are simply mixed. This problem is caused by the weak bonding between the fibers constituting the wet nonwoven fabric and the high density of the wet nonwoven fabric, so that the unstretched PPS fiber is fused and bonded to the flameproof rayon fiber. The present invention has been found.
すなわち、本発明の難燃性湿式不織布は、ＰＰＳ繊維と防炎レーヨン繊維とからなる湿式不織布であって、前記ポリフェニレンサルファイド繊維の少なくとも一部が前記防炎レーヨン繊維と融着して結合しており、０．３〜１．２ｇ／ｃｍ３の範囲内にある見掛け密度を有する湿式不織布である。 That is, the flame retardant wet nonwoven fabric of the present invention is a wet nonwoven fabric composed of PPS fibers and flameproof rayon fibers, and at least a part of the polyphenylene sulfide fibers are fused and bonded to the flameproof rayon fibers. It is a wet nonwoven fabric having an apparent density in the range of 0.3 to 1.2 g / cm 3 .
本発明で規定する難燃性の定義は、ＪＩＳ Ｌ １０９１（１９９９）のＡ−１法に規定される４５°ミクロバーナ試験法において孔が開かず、試験後の湿式不織布が収縮しないことを意味する。孔が開かないということは、すなわち、着炎しても十分な難燃性能を有しており、繊維が溶融して脱落しないことを意味し、また収縮しないとは、着炎時の熱によって湿式不織布が収縮しないことを意味する。 The definition of flame retardancy defined in the present invention means that a hole is not opened in the 45 ° micro burner test method defined in A-1 method of JIS L 1091 (1999), and the wet nonwoven fabric after the test does not shrink. To do. The fact that the hole does not open means that the flame has sufficient flame retardancy even when flaming, meaning that the fiber does not melt and fall off, and that it does not shrink due to the heat at the time of flaming. It means that the wet nonwoven fabric does not shrink.
更に好ましくは、上記の試験において、孔が開かずに収縮もせず、なおかつ、難燃試験の結果が区分「３」に分類できることである。区分「３」では、１分の加熱もしくは着炎した後において残炎時間が３秒以下であり、燃焼面積も３０ｃｍ２以下であることから、実質的に炎の延焼が継続しない性質を意味する。 More preferably, in the above test, the hole does not open and does not shrink, and the result of the flame retardant test can be classified into category “3”. In category “3”, the afterflame time is 3 seconds or less and the combustion area is 30 cm 2 or less after 1 minute of heating or ignition, which means that the flame spread does not continue substantially. .
本発明の難燃性湿式不織布の見掛け密度は、０．３〜１．２ｇ／ｃｍ３の範囲内にあることが必要である。見掛け密度が０．３ｇ／ｃｍ３より小さいと構成する繊維同士の空隙が多く、繊維同士も密着していないことから、着炎したときの熱で容易に収縮が発生するので問題であるし、構成繊維の本数そのものも少ないので、本発明で目的としている難燃性能を有しない。また、見掛け密度が１．２ｇ／ｃｍ３より大きいと、構成繊維の密着性や緻密さは高くなるが、湿式不織布の剛性が高くなり、絶縁資材として組み込むときの追従性と装着性が損なわれる。 The apparent density of the flame-retardant wet nonwoven fabric of the present invention needs to be in the range of 0.3 to 1.2 g / cm 3 . If the apparent density is less than 0.3 g / cm 3 , there are many voids between the fibers, and the fibers are not in close contact with each other. Since the number of constituent fibers itself is small, it does not have the flame retardancy targeted by the present invention. Further, when the apparent density is larger than 1.2 g / cm 3 , the adhesiveness and denseness of the constituent fibers are increased, but the rigidity of the wet nonwoven fabric is increased, and the followability and the mounting property when incorporated as an insulating material are impaired. .
本発明で用いられるＰＰＳ繊維とは、ポリマー構成単位の９０モル％以上が−（Ｃ６Ｈ４−Ｓ）−で構成されるフェニレンサルファイド構造単位を含有する重合体からなる合成繊維である。 The PPS fibers used in the present invention, more than 90 mole% of the polymer structural units - (C 6 H 4 -S) - is a synthetic fiber made of a polymer containing phenylene sulfide structural units composed.
本発明で用いられるＰＰＳ繊維は、湿式不織布に使用するために、その繊維長が２〜３８ｍｍの範囲内であることが好ましい。繊維長が２〜３８ｍｍの範囲内であれば、抄紙用の原液に均一に分散が可能となり、抄紙した後の湿式不織布が十分な引張強力を有する。また、ＰＰＳ繊維の太さについても、抄紙用の原液に繊維が凝集せずに均一分散できることから、単繊維繊度は０．１〜１０．０ｄｔｅｘの範囲内にあるものが好ましい。 The PPS fiber used in the present invention preferably has a fiber length in the range of 2 to 38 mm in order to be used for a wet nonwoven fabric. If the fiber length is in the range of 2 to 38 mm, it can be uniformly dispersed in the stock solution for papermaking, and the wet nonwoven fabric after papermaking has sufficient tensile strength. The thickness of the PPS fiber is preferably in the range of 0.1 to 10.0 dtex because the fiber can be uniformly dispersed without agglomerating in the stock solution for papermaking.
本発明で用いられるＰＰＳ繊維の製造方法は、上述のフェニレンサルファイド構造単位を有するポリマーをその融点以上で溶融し、紡糸口金から紡出することにより繊維状にするものである。紡出された繊維は、その大部分が非晶構造で寸法安定性が乏しいので、熱延伸して配向させることにより繊維の強力を向上させ、市販のＰＰＳ繊維とされる。市販品としては“トルコン”（登録商標）（東レ社製）、“プロコン”（登録商標）（東洋紡社製）など、複数のＰＰＳ繊維が流通している。 The method for producing PPS fibers used in the present invention is to form a fiber by melting the polymer having the phenylene sulfide structural unit described above at or above its melting point and spinning from a spinneret. Since most of the spun fibers have an amorphous structure and poor dimensional stability, the strength of the fibers is improved by orientation by hot drawing, and commercial PPS fibers are obtained. As a commercial product, a plurality of PPS fibers such as “Torcon” (registered trademark) (manufactured by Toray Industries, Inc.) and “Procon” (registered trademark) (manufactured by Toyobo) are in circulation.
また、本発明で用いられる防炎レーヨン繊維は、レーヨンに難燃剤を練り込んで構成されるものであり、この防炎レーヨン繊維も繊維長が２〜３８ｍｍの範囲内であることが好ましい。繊維長の好ましい範囲については、ＰＰＳ繊維の場合と同様の理由である。 The flameproof rayon fiber used in the present invention is constituted by kneading a flame retardant into rayon, and the flameproof rayon fiber also preferably has a fiber length in the range of 2 to 38 mm. About the preferable range of fiber length, it is the same reason as the case of PPS fiber.
本発明で用いられる防炎レーヨン繊維の単繊維繊度は、抄紙用の原液に十分に分散し、尚且つ十分な紙力を得るために、１．０〜１０．０ｄｔｅｘの範囲内にあるものが好ましい。 The single fiber fineness of the flameproof rayon fiber used in the present invention is in the range of 1.0 to 10.0 dtex in order to sufficiently disperse in the stock solution for papermaking and to obtain sufficient paper strength. preferable.
本発明で用いられる防炎レーヨン繊維の製造方法は、ビスコース原液（セルロース、苛性ソーダおよび二硫化炭素の混合体）と、珪酸ソーダに代表される珪素含有物、あるいは、硫酸マグネシウムに代表されるマグネシウム含有物を混合し、紡糸口金から紡出することにより繊維状にするものである。ダイワボウレーヨン社などから、“ＤＦＧ”（登録商標）や“ＦＲ ＣＯＲＯＮＡ”（登録商標）として市販されている。 The method for producing flameproof rayon fibers used in the present invention includes a viscose stock solution (a mixture of cellulose, caustic soda and carbon disulfide), a silicon-containing material typified by sodium silicate, or magnesium typified by magnesium sulfate. The inclusions are mixed and made into a fiber by spinning from the spinneret. It is commercially available as “DFG” (registered trademark) or “FR CORONA” (registered trademark) from Daiwabo Rayon.
また、本発明の難燃性湿式不織布においては、ＰＰＳ繊維の一部が未延伸のＰＰＳ繊維を含み、その未延伸のＰＰＳ繊維と防炎レーヨン繊維とが融着して結合していることが重要である。未延伸のＰＰＳ繊維とは、その大部分が非晶構造で構成される繊維であって、１２０〜１４０℃程度の低い温度で処理することにより軟化し、バインダーとしての機能を奏するものである。 In the flame-retardant wet nonwoven fabric of the present invention, part of the PPS fiber includes unstretched PPS fiber, and the unstretched PPS fiber and the flameproof rayon fiber are fused and bonded. is important. The unstretched PPS fiber is a fiber composed mostly of an amorphous structure, and is softened by treatment at a low temperature of about 120 to 140 ° C., and functions as a binder.
本発明で用いられる未延伸糸は、その紡糸口金から特定の速度で引き取った繊維であって、実質的な延伸がなされていない糸である。特定の引き取り速度は、５００〜７，０００ｍ／分の範囲が、異常糸の発生が少ないことから好適に採用される。このようにして得られた未延伸糸は、好適には３〜７倍の延伸倍率で熱延伸して配向することにより、３．０ｃＮ／ｄｔｅｘ以上の強度を有する市販の延伸糸となる。 The undrawn yarn used in the present invention is a fiber that has been drawn from the spinneret at a specific speed and has not been substantially drawn. A specific take-up speed of 500 to 7,000 m / min is preferably employed since abnormal yarns are less likely to be generated. The undrawn yarn thus obtained becomes a commercially available drawn yarn having a strength of 3.0 cN / dtex or more by being oriented by heat drawing at a draw ratio of preferably 3 to 7 times.
このような未延伸のＰＰＳ繊維と防炎レーヨン繊維とを混合した湿式不織布において、上述の１２０〜１４０℃程度の低温で熱処理することにより未延伸のＰＰＳ繊維と防炎レーヨン繊維とが融着して結合し、繊維同士が固く結合される。このように融着による結合が存在することにより、湿式不織布に着炎したときの熱に曝されても、湿式不織布が収縮しない。 In such a wet nonwoven fabric in which unstretched PPS fibers and flameproof rayon fibers are mixed, the unstretched PPS fibers and flameproof rayon fibers are fused by heat treatment at a low temperature of about 120 to 140 ° C. And the fibers are firmly bonded. Thus, the presence of the bond by fusion does not cause the wet nonwoven fabric to shrink even when exposed to heat when the wet nonwoven fabric is flamed.
かかる収縮が発生しないという観点から、未延伸のＰＰＳ繊維は湿式不織布全体の１０〜４０重量％であることが好ましい。未延伸のＰＰＳ繊維が１０重量％未満では、防炎レーヨン繊維と融着して結合する点が少ないため、着炎したときの熱で湿式不織布が収縮することになる。また、未延伸のＰＰＳ繊維が４０重量％を超えると、防炎レーヨン繊維の混率が減少し、着炎したときの炎で湿式不織布に孔が開いてしまう傾向がある。 From the viewpoint that such shrinkage does not occur, the unstretched PPS fiber is preferably 10 to 40% by weight of the entire wet nonwoven fabric. If the unstretched PPS fiber is less than 10% by weight, there are few points that are fused and bonded to the flameproof rayon fiber. On the other hand, when the unstretched PPS fiber exceeds 40% by weight, the mixing ratio of the flameproof rayon fiber is reduced, and the wet nonwoven fabric tends to be opened by the flame when it is flared.
同様の理由から、防炎レーヨン繊維は、湿式不織布を構成する繊維全体の３５〜９０重量％であることが好ましい。防炎レーヨン繊維が３５重量％未満では、着炎したときの防炎性能が十分に達成できず、湿式不織布に孔が開いてしまう傾向がある。また、防炎レーヨン繊維が９０重量％を超えると、バインダーとして機能する未延伸のＰＰＳ繊維と融着して結合する点が減少し、接炎したときの熱で湿式不織布が収縮してしまうことになる。より好ましくは、防炎レーヨン繊維は湿式不織布を構成する繊維全体の５０〜７５重量％であり、このようにすることにより難燃性能と着炎時の形態保持性能という２つの面で特に優れている。 For the same reason, it is preferable that the flameproof rayon fiber is 35 to 90% by weight of the whole fiber constituting the wet nonwoven fabric. When the flameproof rayon fiber is less than 35% by weight, the flameproof performance when the flame is applied cannot be sufficiently achieved, and the wet nonwoven fabric tends to be perforated. In addition, when the flameproof rayon fiber exceeds 90% by weight, the number of fusion-bonded and unstretched PPS fibers functioning as a binder decreases, and the wet nonwoven fabric contracts due to the heat generated when the flame comes into contact. become. More preferably, the flameproof rayon fiber is 50 to 75% by weight of the whole fiber constituting the wet nonwoven fabric, and in this way, it is particularly excellent in two aspects of flame retardancy and shape retention performance during flame. Yes.
本発明の難燃性湿式不織布は、湿式不織布を構成する繊維として、ＰＰＳ繊維と防炎レーヨン繊維とを含むことが必要であるが、ＰＰＳ繊維として未延伸のＰＰＳ繊維と延伸したＰＰＳ繊維の両方を含んでも良い。未延伸のＰＰＳ繊維は上述のとおりに防炎レーヨン繊維と融着して結合し、着炎したときの形態安定性を発揮する。一方、延伸したＰＰＳ繊維は、抄紙過程で必要な湿紙強力を発揮し、更に抄紙完了後の湿式不織布全体の引張強力を高くすることができる。 The flame retardant wet nonwoven fabric of the present invention needs to contain PPS fibers and flameproof rayon fibers as fibers constituting the wet nonwoven fabric, and both PPS fibers and unstretched PPS fibers are stretched as PPS fibers. May be included. As described above, the unstretched PPS fiber is fused and bonded to the flameproof rayon fiber, and exhibits morphological stability when the flame is applied. On the other hand, the stretched PPS fiber exhibits the wet paper strength required in the papermaking process, and can further increase the tensile strength of the entire wet nonwoven fabric after the papermaking is completed.
本発明の難燃性湿式不織布を構成する繊維は、難燃性能と着炎時の形態保持性という観点から、ＰＰＳ繊維と防炎レーヨン繊維との割合が２５〜５０：７５〜５０重量％が好ましく、中でもＰＰＳ繊維としては、着炎したときの形態安定性と湿式不織布全体の引張強力という両方の性能を満たすために、湿式不織布全体に占める割合としてＰＰＳ繊維の未延伸糸は５〜５０重量％であることが好ましい。 The fiber constituting the flame retardant wet nonwoven fabric of the present invention has a ratio of PPS fiber to flame retardant rayon fiber of 25 to 50:75 to 50% by weight from the viewpoint of flame retardancy and form retention at the time of flame. Among them, the PPS fiber is preferably 5 to 50% by weight of the unstretched yarn of the PPS fiber as a proportion of the whole wet nonwoven fabric in order to satisfy both the performance of the form stability when flaming and the tensile strength of the whole wet nonwoven fabric. % Is preferred.
より具体的な好ましい態様は、湿式不織布を構成する各繊維比率として、防炎レーヨン繊維：ＰＰＳ繊維の未延伸糸：ＰＰＳ繊維の延伸糸は４０〜６０：１０〜３０：５０〜１０重量％である。 A more specific preferred embodiment is that each fiber ratio constituting the wet nonwoven fabric is 40-60: 10-30: 50-10 wt% of flameproof rayon fiber: unstretched yarn of PPS fiber: stretched yarn of PPS fiber. is there.
また、本発明で用いられる防炎レーヨン繊維は、珪素またはマグネシウムを含み、かつ、ハロゲン原子または燐原子を含まないことが好ましい態様である。難燃剤として、チタン化合物、ジルコニウム化合物および有機リン化合物等が一般的に知られているが、中でも珪素またはマグネシウムという無機系の難燃成分を含むことが好ましい。珪素またはマグネシウムを含む防炎レーヨン繊維は、着炎しても珪素またはマグネシウムという無機成分が残留して形態を維持することから、高い難燃性能を有する。 Moreover, it is a preferable aspect that the flameproof rayon fiber used in the present invention contains silicon or magnesium and does not contain a halogen atom or a phosphorus atom. As the flame retardant, titanium compounds, zirconium compounds, organophosphorus compounds, and the like are generally known, but among them, it is preferable to include an inorganic flame retardant component such as silicon or magnesium. The flameproof rayon fiber containing silicon or magnesium has a high flame retardancy because an inorganic component such as silicon or magnesium remains and maintains its form even when flame is applied.
更にまた、難燃剤として一般的なハロゲン原子または燐原子を含まないことから、着炎してもハロゲン原子に由来する有害物質の発生が無い。またこの性質は、ＰＰＳ繊維がポリマー構成単位としてハロゲンを含まないので、ＰＰＳ繊維と防炎レーヨン繊維とからなる湿式不織布全体で見たときに、着炎してもハロゲン原子に由来する有害物質の発生が無いので、極めて好ましい態様である。 Furthermore, since a general halogen atom or phosphorus atom is not included as a flame retardant, no harmful substances derived from the halogen atom are generated even when the flame is ignited. In addition, this property is that PPS fibers do not contain halogen as a polymer constituent unit, and therefore, when viewed as a whole wet nonwoven fabric composed of PPS fibers and flameproof rayon fibers, even if the flame is ignited, harmful substances derived from halogen atoms Since there is no generation | occurrence | production, it is a very preferable aspect.
本発明の難燃性湿式不織布においては、本発明の効果を妨げない範囲で、他種の繊維を混合して用いることができる。 In the flame-retardant wet nonwoven fabric of the present invention, other types of fibers can be mixed and used within a range not impeding the effects of the present invention.
本発明の難燃性湿式不織布の製造方法は、未延伸のＰＰＳ繊維と防炎レーヨン繊維とを混合して抄紙加工し、しかる後に加熱・加圧工程を施すものである。未延伸のＰＰＳ繊維と防炎レーヨン繊維とを所定の割合で混合し、抄紙原液として水、分散剤および消泡剤とからなる水溶液中に分散して調整する。しかる後に、抄紙機に通じて漉きあげ抄紙とする。抄紙機は、一般的な構造のものであれば問題なく採用することができ、円網、長網および短網のいずれでも良い。得られた湿紙をベルト上に載せて、水を絞りつつ乾燥して巻き取ることにより湿式不織布とすることができる。 In the method for producing a flame retardant wet nonwoven fabric of the present invention, unstretched PPS fibers and flameproof rayon fibers are mixed and processed to make paper, and then subjected to a heating / pressurizing step. An unstretched PPS fiber and a flameproof rayon fiber are mixed in a predetermined ratio, and dispersed and adjusted in an aqueous solution composed of water, a dispersant, and an antifoaming agent as a papermaking stock solution. After that, it is passed through a paper machine to make paper. As long as the paper machine has a general structure, it can be adopted without any problem, and may be any of a circular net, a long net, and a short net. The obtained wet paper can be placed on a belt, dried and rolled up while squeezing water, to obtain a wet nonwoven fabric.
本発明の難燃性湿式不織布においては、水を絞って乾燥した後に、得られた湿式不織布を加熱・加圧工程を施すことが必要である。加熱・加圧を同時に行うことにより初めて、未延伸のＰＰＳ繊維が軟化して防炎レーヨン繊維と融着して結合し、難燃性湿式不織布に着炎しても収縮しない特徴を有することになる。 In the flame-retardant wet nonwoven fabric of the present invention, it is necessary to heat and pressurize the obtained wet nonwoven fabric after squeezing water and drying. For the first time by performing heating and pressurization simultaneously, unstretched PPS fiber is softened and fused and bonded with flameproof rayon fiber, and has a characteristic that it does not shrink even when flame retardant wet nonwoven fabric is flared Become.
かかる加熱・加圧工程は、一対のローラー間に不織布を通すことで処理することができ、一対のローラーに用いられる材質は、鉄同士のもの、鉄とペーパーのものおよび鉄とゴムのもの等、適宜選択して用いることができる。 Such heating / pressurization process can be performed by passing a nonwoven fabric between a pair of rollers, and the materials used for the pair of rollers are iron-to-iron, iron-paper, iron-rubber, etc. Can be appropriately selected and used.
加熱温度と加圧圧力は、未延伸のＰＰＳ繊維が軟化して防炎レーヨン繊維と結合する条件とすることが必要であり、８０〜２２０℃の温度範囲と、１００〜８，０００Ｎ／ｃｍの線圧範囲が好ましい。温度が８０℃未満で線圧が１００Ｎ／ｃｍ未満の場合、未延伸のＰＰＳ繊維が十分に軟化しない傾向がある。また、温度が２２０℃を超えて線圧が８，０００Ｎ／ｃｍを超える場合、湿式不織布はフィルムのように極めて緻密化し、見掛け密度が１．２ｇ／ｃｍ３より大きくなって剛性が高くなり、湿式不織布に比べて割れやすくなり、絶縁資材として組み込むときの追従性と装着性が損なわれることがある。 The heating temperature and the pressurizing pressure must be such that the unstretched PPS fiber is softened and bonded to the flameproof rayon fiber, and the temperature range of 80 to 220 ° C. and 100 to 8,000 N / cm. A linear pressure range is preferred. When the temperature is less than 80 ° C. and the linear pressure is less than 100 N / cm, unstretched PPS fibers tend not to be sufficiently softened. In addition, when the temperature exceeds 220 ° C. and the linear pressure exceeds 8,000 N / cm, the wet nonwoven fabric becomes extremely dense like a film, the apparent density becomes larger than 1.2 g / cm 3 and the rigidity becomes high, It becomes easier to break than wet nonwoven fabric, and the followability and wearability when incorporated as an insulating material may be impaired.
本発明の湿式不織布は、モーターやトランス、セパレーター等に用いられる電気絶縁紙として利用可能であり、非溶融性能と難燃性能が同時に必要な難燃資材として利用可能である。 The wet nonwoven fabric of the present invention can be used as an electrical insulating paper used for motors, transformers, separators, and the like, and can be used as a flame retardant material that requires both non-melting performance and flame retardant performance.
次に実施例を用いて本発明を詳細に説明するが、本発明はこれらの実施例に限定されるものではない。 EXAMPLES Next, although this invention is demonstrated in detail using an Example, this invention is not limited to these Examples.
［測定・評価方法］
（１）目付
ＪＩＳ Ｌ １９０６：２０００に準じて、２５ｃｍ×２５ｃｍの試験片を、１枚採取し、標準状態におけるそれぞれの質量（ｇ）を量り、１ｍ２当たりの質量（ｇ／ｍ２）で表した。
[Measurement and evaluation method]
(1) Basis weight According to JIS L 1906: 2000, one 25 cm × 25 cm test piece is collected, and each mass (g) in a standard state is measured, and the mass per 1 m 2 (g / m 2 ). expressed.
（２）厚さ
ＪＩＳ Ｌ １９０６：２０００で準用するＪＩＳ Ｌ １０９６：１９９９に準じて、試料の異なる１０か所について、厚さ測定機を用いて、直径２２ｍｍの加圧子による２ｋＰａの加圧下、厚さを落ち着かせるために１０秒間待った後に厚さを測定し、平均値を算出した。
(2) Thickness According to JIS L 1906: 2000, which is applied mutatis mutandis according to JIS L 1906: 2000, thickness was measured under a pressure of 2 kPa with a 22 mm diameter pressurizer using a thickness measuring device at 10 different points of the sample. In order to calm the thickness, after waiting for 10 seconds, the thickness was measured, and an average value was calculated.
（３）難燃性能
ＪＩＳ Ｌ １０９１：１９９９のＡ−１法（４５°ミクロバーナ法）に準じて、約２５０ｍｍ×約２００ｍｍサイズにサンプルをカットし、試験片支持枠にたるみの無いように挟む。これを燃焼試験箱に取り付けて１分間加熱し、残炎時間と残じん時間を測定する。次に、サンプルを試験片支持枠から外して燃焼面積を測定し、区分「１」〜「３」を判断した。
(3) Flame Retardant Performance According to JIS L 1091: 1999 method A-1 (45 ° micro burner method), a sample is cut into a size of about 250 mm × about 200 mm and sandwiched between the test piece support frames without slack. . This is attached to a combustion test box and heated for 1 minute, and the after flame time and the after dust time are measured. Next, the sample was removed from the test piece support frame, the combustion area was measured, and the categories “1” to “3” were judged.
区分「１」・・・燃焼面積（炭化面積）が４５ｃｍ２を超える
区分「２」・・・燃焼面積（炭化面積）が４５ｃｍ２以下
区分「３」・・・燃焼面積（炭化面積）が３０ｃｍ２以下
また試験後のサンプルについて、着炎部分に孔があるか無いかを目視で判定した。
Category “1”: combustion area (carbonization area) exceeds 45 cm 2 Category “2”: combustion area (carbonization area) is 45 cm 2 or less Category “3”: combustion area (carbonization area) is 30 cm 2 or less Moreover, about the sample after a test, it was judged visually whether there was a hole in a flaming part.
更に試験後のサンプルについて、ヨコ方向の収縮があるか無いか確認した。収縮のある場合には、次式で収縮率を計算した。
ヨコ方向の収縮率（％）＝（試験前の幅−試験後の幅）／（試験前の幅）×１００。
Further, it was confirmed whether or not there was any shrinkage in the horizontal direction for the sample after the test. When shrinkage occurred, the shrinkage rate was calculated by the following formula.
Horizontal shrinkage (%) = (width before test−width after test) / (width before test) × 100.
（ＰＰＳ繊維の未延伸糸）
未延伸のＰＰＳ繊維として、単繊維繊度３．０ｄｔｅｘ、カット長６ｍｍの東レ社製“トルコン”（登録商標）、品番Ｓ１１１を用いた。
(Undrawn yarn of PPS fiber)
As the unstretched PPS fiber, “Torcon” (registered trademark) manufactured by Toray Industries, Inc., having a single fiber fineness of 3.0 dtex and a cut length of 6 mm, product number S111 was used.
（ＰＰＳ繊維の延伸糸）
延伸されたＰＰＳ繊維として、単繊維繊度１．０ｄｔｅｘ、カット長６ｍｍの東レ社製“トルコン”（登録商標）、品番Ｓ３０１を用いた。
(PPS fiber drawn yarn)
As the stretched PPS fiber, “Torcon” (registered trademark) manufactured by Toray Industries, Inc. having a single fiber fineness of 1.0 dtex and a cut length of 6 mm, product number S301 was used.
（防炎レーヨン繊維）
防炎レーヨン繊維として、単繊維繊度３．３ｄｔｅｘ、カット長５ｍｍのダイワボウレーヨン社製“ＦＲ ＣＯＲＯＮＡ”（登録商標）を用いた。
(Fireproof rayon fiber)
As the flameproof rayon fiber, “FR CORONA” (registered trademark) manufactured by Daiwabo Rayon Co., Ltd. having a single fiber fineness of 3.3 dtex and a cut length of 5 mm was used.
（手漉きの抄紙機）
底に１４０メッシュの手漉き抄紙網を設置した大きさ２５ｃｍ×２５ｃｍ、高さ４０ｃｍの手すき抄紙機（熊谷理機工業社製）を用いた。
(Handmade paper machine)
A handmade paper machine (manufactured by Kumagai Riki Kogyo Co., Ltd.) having a size of 25 cm × 25 cm and a height of 40 cm in which a 140-mesh handmade papermaking net was installed on the bottom was used.
（加熱・加圧工程）
金属ロールとペーパーロールとからなるカレンダー加工機（由利ロール社製）を使用して加熱・加圧工程を施した。
(Heating / pressurizing process)
A heating / pressurizing step was performed using a calendar processing machine (manufactured by Yuri Roll Co., Ltd.) consisting of a metal roll and a paper roll.
［実施例１］
ＰＰＳ繊維の未延伸糸と防炎レーヨン繊維とを表１の重量比率になるように準備し、水に分散した分散液を用いて手漉きの抄紙機で湿紙を作成し、ろ紙の上で１日、常温乾燥した。続いて温度１５０℃、線圧２，０００Ｎ／ｃｍ、ロール回転速度５ｍ／ｍｉｎで加熱・加圧し、見掛け密度が０．３ｇ／ｃｍ３の湿式不織布を得た。得られた湿式不織布は、燃焼試験での孔開きも収縮も無く、難燃性能に優れるものであった。ただし燃焼面積（炭化した面積）は広かったため、燃焼試験での区分は最も劣る「１」に分類された。結果を表１に示す。図１に、実施例１で得られた湿式不織布の燃焼試験後の外観を示す。上部の中間部分が、試験後の取扱で脱落している。
[Example 1]
Prepare unstretched yarn of PPS fiber and flameproof rayon fiber so as to have the weight ratio shown in Table 1, make a wet paper with a handmade paper machine using a dispersion dispersed in water, and place 1 on the filter paper. Dried at room temperature for 1 day. Subsequently, heating and pressurization were performed at a temperature of 150 ° C., a linear pressure of 2,000 N / cm, and a roll rotation speed of 5 m / min to obtain a wet nonwoven fabric having an apparent density of 0.3 g / cm 3 . The obtained wet nonwoven fabric was excellent in flame retardancy without any opening or shrinkage in the combustion test. However, since the combustion area (carbonized area) was wide, the classification in the combustion test was classified as “1”, which is the worst. The results are shown in Table 1. In FIG. 1, the external appearance after the combustion test of the wet nonwoven fabric obtained in Example 1 is shown. The upper middle part is missing during handling after the test.
［比較例１］
ＰＰＳ繊維の延伸糸と防炎レーヨン繊維とを表１の重量比率になるように準備し、水に分散した分散液を用いて手漉きの抄紙機で湿紙を作成し、ろ紙の上で１日、常温乾燥した。続いて温度１６０℃、線圧３，０００Ｎ／ｃｍ、ロール回転速度５ｍ／ｍｉｎで加熱・加圧したが、ＰＰＳ繊維の未延伸成分を含まないために緻密化せず、見掛け密度は０．１ｇ／ｃｍ３の湿式不織布を得た。得られた湿式不織布は、燃焼試験での孔開きこそ無かったが、ヨコ方向で収縮し、難燃性能は不十分であった。また、燃焼面積（炭化した面積）も広く、燃焼試験での区分は最も劣る「１」に分類された。結果を表１に示す。図２に、比較例１で得られた湿式不織布の燃焼試験後の外観を示す。上部の一部分が、試験後の取扱で脱落している。
[Comparative Example 1]
Prepare the PPS fiber drawn yarn and flameproof rayon fiber in the weight ratio shown in Table 1 and make a wet paper with a hand-made paper machine using the dispersion in water. Dried at room temperature. Subsequently, heating and pressurization were performed at a temperature of 160 ° C., a linear pressure of 3,000 N / cm, and a roll rotation speed of 5 m / min. However, the PPS fiber was not densified because it did not contain an unstretched component, and the apparent density was 0.1 g. A wet nonwoven fabric of / cm 3 was obtained. The obtained wet nonwoven fabric did not have a hole in the combustion test, but shrunk in the horizontal direction, and the flame retardancy was insufficient. Also, the combustion area (carbonized area) was wide, and the classification in the combustion test was classified as “1”, which is the worst. The results are shown in Table 1. In FIG. 2, the external appearance after the combustion test of the wet nonwoven fabric obtained by the comparative example 1 is shown. A part of the upper part is missing during handling after the test.
比較例１は、防炎レーヨン繊維とＰＰＳ繊維の延伸糸のみで、ＰＰＳ繊維の未延伸糸が含まれていない。ＰＰＳ延伸糸は、結晶成分が多く熱や圧力を加えても軟化し難い。従って、比較例１では加熱・加圧はしたものの、ＰＰＳ延伸糸が軟化せずに防炎レーヨン繊維との融着がなく湿式不織布の厚みも薄くならなかったので、見掛け密度は０．１と低いままである。 Comparative Example 1 is only a stretched yarn of flameproof rayon fiber and PPS fiber, and does not include an unstretched yarn of PPS fiber. PPS drawn yarn has many crystal components and is difficult to soften even when heat or pressure is applied. Therefore, in Comparative Example 1, although heating and pressurization were performed, the PPS stretched yarn was not softened and was not fused with the flameproof rayon fiber, and the thickness of the wet nonwoven fabric was not reduced, so the apparent density was 0.1. Stays low.
［実施例２］
ＰＰＳ繊維の未延伸糸と延伸糸、さらに防炎レーヨン繊維とを表１の重量比率になるように準備し、水に分散した分散液を用いて手漉きの抄紙機で湿紙を作成し、ろ紙の上で１日、常温乾燥した。続いて温度１７０℃、線圧４，０００Ｎ／ｃｍ、ロール回転速度５ｍ／ｍｉｎで加熱・加圧し、見掛け密度が０．９ｇ／ｃｍ３の湿式不織布を得た。得られた湿式不織布は、燃焼試験での孔開きも収縮も無く、難燃性能に優れるものであった。更には燃焼面積（炭化した面積）も少なく、燃焼試験での区分は最も優れる「３」に分類された。結果を表１に示す。図３に、実施例２で得られた湿式不織布の燃焼試験後の外観を示す。
[Example 2]
Prepare PPS fiber undrawn yarn, drawn yarn, and flameproof rayon fiber at the weight ratio shown in Table 1, and make wet paper with a hand-made paper machine using a dispersion dispersed in water. And dried at room temperature for 1 day. Subsequently, heating and pressurization were performed at a temperature of 170 ° C., a linear pressure of 4,000 N / cm, and a roll rotation speed of 5 m / min to obtain a wet nonwoven fabric having an apparent density of 0.9 g / cm 3 . The obtained wet nonwoven fabric was excellent in flame retardancy without any opening or shrinkage in the combustion test. Furthermore, the combustion area (carbonized area) was small, and the classification in the combustion test was classified as “3”, which is the most excellent. The results are shown in Table 1. In FIG. 3, the external appearance after the combustion test of the wet nonwoven fabric obtained in Example 2 is shown.
［比較例２］
ＰＰＳ繊維の未延伸糸と延伸糸、さらに防炎レーヨン繊維とを表１の重量比率になるように準備し、水に分散した分散液を用いて手漉きの抄紙機で湿紙を作成し、ろ紙の上で１日、常温乾燥した。続いて温度１７０℃、線圧２，０００Ｎ／ｃｍ、ロール回転速度５ｍ／ｍｉｎで加熱・加圧し、見掛け密度が０．２ｇ／ｃｍ３の湿式不織布を得た。得られた湿式不織布は、燃焼試験で孔が開き、ヨコ方向でも収縮したため、難燃性能は極めて不十分であった。また、燃焼面積（炭化した面積）は燃焼試験で孔が開いたことから延焼せず、燃焼試験での区分は最も良い「３」に分類された。結果を表１に示す。図４に、比較例２で得られた湿式不織布の燃焼試験後の外観を示す。
[Comparative Example 2]
Prepare PPS fiber undrawn yarn, drawn yarn, and flameproof rayon fiber at the weight ratio shown in Table 1, and make wet paper with a hand-made paper machine using a dispersion dispersed in water. And dried at room temperature for 1 day. Subsequently, heating and pressurization were performed at a temperature of 170 ° C., a linear pressure of 2,000 N / cm, and a roll rotation speed of 5 m / min to obtain a wet nonwoven fabric having an apparent density of 0.2 g / cm 3 . The obtained wet nonwoven fabric had holes in the combustion test and contracted in the horizontal direction, so that the flame retardant performance was extremely insufficient. In addition, the combustion area (carbonized area) did not spread due to the formation of holes in the combustion test, and the classification in the combustion test was classified as “3”, the best. The results are shown in Table 1. In FIG. 4, the external appearance after the combustion test of the wet nonwoven fabric obtained by the comparative example 2 is shown.
比較例２は、加熱・加圧して軟化して緻密化するＰＰＳ繊維の未延伸糸が５重量％しかないので、見掛け密度は０．２と緻密化は十分進まなかった。 In Comparative Example 2, since the undrawn yarn of PPS fiber softened and densified by heating and pressing was only 5% by weight, the apparent density was 0.2 and the densification did not proceed sufficiently.
［比較例３］
ＰＰＳ繊維の未延伸糸と延伸糸、さらに防炎レーヨン繊維とを表１の重量比率になるように準備し、水に分散した分散液を用いて手漉きの抄紙機で湿紙を作成し、ろ紙の上で１日、常温乾燥した。加熱・加圧加工しないで得られた湿式不織布は見掛け密度が０．１ｇ／ｃｍ３のものであり、繊維同士の融着は無かった。この湿式不織布は、燃焼試験で孔こそ開かなかったが、ヨコ方向で収縮したため、難燃性能は不十分であった。また、燃焼面積（炭化した面積）は燃焼試験で孔が開いたことから延焼が進まず、燃焼試験での区分は中間の「２」に分類された。結果を表１に示す。
[Comparative Example 3]
Prepare PPS fiber undrawn yarn, drawn yarn, and flameproof rayon fiber at the weight ratio shown in Table 1, and make wet paper with a hand-made paper machine using a dispersion dispersed in water. And dried at room temperature for 1 day. The wet nonwoven fabric obtained without heating / pressurizing had an apparent density of 0.1 g / cm 3 and there was no fusion between the fibers. Although this wet nonwoven fabric did not open a hole in the combustion test, it shrunk in the horizontal direction, so that the flame retardant performance was insufficient. In addition, the fire area did not spread due to the formation of holes in the combustion test, and the classification in the combustion test was classified as “2” in the middle. The results are shown in Table 1.
［比較例４］
ＰＰＳ繊維の未延伸糸と延伸糸とを表１の重量比率になるように準備し、水に分散した分散液を用いて手漉きの抄紙機で湿紙を作成し、ろ紙の上で１日、常温乾燥した。続いて温度１９０℃、線圧５，５００Ｎ／ｃｍ、ロール回転速度５ｍ／ｍｉｎで加熱・加圧し、見掛け密度が１．３ｇ／ｃｍ３のＰＰＳ繊維のみからなる湿式不織布を得た。得られた湿式不織布は、燃焼試験で瞬時に孔が開いたので、収縮や延焼こそ無かったものの、難燃性能が劣るものであった。結果を表１に示す。
[Comparative Example 4]
Prepare unstretched yarn and drawn yarn of PPS fiber so as to have a weight ratio shown in Table 1, create a wet paper with a hand-made paper machine using a dispersion dispersed in water, Dried at room temperature. Subsequently, heating and pressurization were performed at a temperature of 190 ° C., a linear pressure of 5,500 N / cm, and a roll rotation speed of 5 m / min, to obtain a wet nonwoven fabric composed only of PPS fibers having an apparent density of 1.3 g / cm 3 . The obtained wet nonwoven fabric had pores instantly opened in a combustion test, and thus had no flame retardant performance although there was no shrinkage or fire spread. The results are shown in Table 1.
表１から明らかなように、実施例１と２について、いずれも燃焼試験での収縮や孔開きが無く、優れた難燃性能を有する結果であった。中でも、実施例２は収縮や孔開きも無いことに加えて、燃焼試験での区分も「３」と最も燃焼面積が小さく優れるものであり、未延伸ＰＰＳ繊維と延伸ＰＰＳ繊維、更に防炎レーヨン繊維とを適正比率で混合し、湿式不織布の見掛け密度を適正に設計したもののみが優れた難燃性能を兼備することがわかった。 As is apparent from Table 1, Examples 1 and 2 were both free from shrinkage and perforation in the combustion test, and had excellent flame retardancy. Among them, in addition to the fact that Example 2 has no shrinkage or perforation, the classification in the combustion test is “3”, which has the smallest burning area and is excellent, and is unstretched PPS fiber, stretched PPS fiber, and flameproof rayon. It was found that only those that were mixed with fibers at an appropriate ratio and the apparent density of the wet nonwoven fabric was appropriately designed had excellent flame retardancy.
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Cited By (4)
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| JP2015052183A (en) * | 2013-09-06 | 2015-03-19 | 大王製紙株式会社 | Electric insulating paper and method of producing electric insulating paper |
| JP2016191020A (en) * | 2015-03-31 | 2016-11-10 | ダイワボウホールディングス株式会社 | Substrate for fire retardant composite molding, fire retardant composite molded body and manufacturing method therefor |
| WO2025182458A1 (en) * | 2024-02-27 | 2025-09-04 | 東レ株式会社 | Sheet, refractory material using same, and secondary battery |
| WO2025258497A1 (en) * | 2024-06-13 | 2025-12-18 | 東レ株式会社 | Flame-shielding heat-insulating material |
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| JP2015052183A (en) * | 2013-09-06 | 2015-03-19 | 大王製紙株式会社 | Electric insulating paper and method of producing electric insulating paper |
| JP2016191020A (en) * | 2015-03-31 | 2016-11-10 | ダイワボウホールディングス株式会社 | Substrate for fire retardant composite molding, fire retardant composite molded body and manufacturing method therefor |
| WO2025182458A1 (en) * | 2024-02-27 | 2025-09-04 | 東レ株式会社 | Sheet, refractory material using same, and secondary battery |
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