JP3683050B2 - Polyester no crimp shortcut fiber for kneading rubber - Google Patents

Description

【０００７】
【数４】

【０００８】
以上のように本発明のポリエステルノークリンプショートカット繊維は、繊維長、繊維径、水分率、油剤付着量を規定することで、溶融ゴム中に混練しても繊維がカールすることなく、単繊維同志の絡みがなくなり、媒体中で良好な分散性を示す。その結果、ゴム中に繊維が均一に分散され、ゴムの改質効果が高くなる。
【０００９】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明のポリエステル繊維の融点は２２０℃以上である必要がある。融点が２２０℃未満であるとポリエステル繊維を高温のゴム中に混練したときに単糸同志が融着したり、繊維物性が大きく変化して好ましくない。
【００１０】
このようなるポリエステル系ポリマーとして、具体的にはポリエチレンテレフレートやポリエチレンナフタレートが好適に用いられる。また、酸化チタンなどの顔料、ヒンダードフェノール系化合物などの抗酸化剤、その他各種添加物を含有していても本発明の効果を妨げない範囲であれば特にかまわない。
【００１１】
本発明のポリエステルノークリンプショートカット繊維は、繊維長が１ｍｍ以上１０ｍｍ以下であることが必要である。特に好ましくは１ｍｍ以上５ｍｍ以下の範囲である。１ｍｍ未満であるとカットするときに摩擦熱によりカールが生じやすくなり好ましくない。また、１０ｍｍより長いとゴム中に混練した際に分散不良が生じやすくなるので好ましくない。
【００１２】
本発明のポリエステルノークリンプショートカット繊維は、繊維径が２０μｍ以上７０μｍ以下であることが必要である。特に好ましくは３０μｍ以上６０μｍ以下の範囲である。単糸径が２０μｍ未満であると単糸分散性が悪く、また曲げに対する剛性が不足しカールしやすくなり好ましくない。また、７０μｍより太いとトウの収束性が著しく悪くなり、生産性が低下するので好ましくない。
【００１３】
本発明のポリエステルノークリンプショートカット繊維は、下記の数５式を満足する必要がある。
【００１４】
【数５】

【００１５】
これを満たさない場合、曲げに対する剛性が不足し、繊維がカールしやすくなるので好ましくない。
本発明のポリエステルノークリンプショートカット繊維は水分率が２重量％以上４重量％以下であることが必要である。水分率が２重量％未満であると静電気の発生により繊維がばらけてショートカットする際の作業性が悪くなり好ましくない。水分率が４重量％を超えるとゴム中に混練する際に水蒸気が多量に発生し、製品中に気泡が入ったり、繊維が混練される際にも充分開繊せず、未分散部分が残るので好ましくない。
【００１６】
本発明のポリエステルノークリンプショートカット繊維は、油剤付着量が０．０１重量％以上０．４重量％以下であることが必要である。油剤付着量が０．０１重量％未満であると静電気が発生し、ショートカットする際にトウがばらけるのでカット後の繊維長が不均一になり好ましくない。油剤付着量が０．４重量％を超えると混練後にゴム中に油剤に起因する異物が発生したり、繊維同志が固着してゴム中に未分散部分が残る場合があり好ましくない。
【００１７】
本発明のポリエステルノークリンプショートカット繊維は、下記の数６式を満足する必要がある。
【００１８】
【数６】

【００１９】
これを満たさない場合、繊維の分散不良、水蒸気発生、異物発生の問題が起こり、好ましくない。
数６式を満足するように製造する方法は以下の通りである。すなわち、紡糸工程で紡糸油剤を０．０５重量％程度付与する。続いて未延伸糸をトウの状態に収束して延伸し、２００℃程度で熱処理し一旦絶乾状態にする。その後、冷却ローラーもしくは冷却スプレーでトウを冷却し、所定の濃度の仕上油剤を付与した後、ニップローラーで水分量を調整する。水分率はニップローラーの圧力以外に冷却スプレーの噴射量、仕上げ油剤の付着量でも調整できる。
【００２０】
なお、本発明に用いる油剤に配合される成分としては、平滑剤、収束剤、乳化剤、帯電防止剤などがある。平滑剤としては、高級アルコールの硫酸エステル、アルキル燐酸エステルなどが用いられる。その配合量としては組成全体の５〜４０％程度が望ましい。収束剤としてはラウリルホスフェートの金属塩などが好適に用いられる。その配合量としては組成全体の５〜４０％程度が望ましい。乳化剤としてはポリオキシエチレンのアルキルエーテルなどのノニオン系界面活性剤が好適に用いられる。その配合量としては組成全体の５〜４０％程度が望ましい。また帯電防止剤としては、アルキルスルホネート、アルキルホスフェートなどの金属塩あるいは脂肪酸の金属塩が好適に用いられる。その配合量としては組成全体の１〜２０％程度が望ましい。なお、これらの組成以外にも防錆剤、抗菌剤、酸化防止剤その他の改質剤を含んでいても本発明の目的を損なわない範囲であれば差し支えない。
【００２１】
本発明のポリエステルノークリンプショートカット繊維の断面形状は特に規制するものではないが、丸断面、三角断面、中空断面あるいはＨ型断面などが好適に用いられる。
【００２２】
（実施例）
次に、本発明を実施例によって具体的に説明する。なお、実施例における各特性の評価方法は次の通りである。
（１）融点
パーキンエルマー社製の示差走査熱量計ＤＳＣ−２型を使用し、昇温速度２０℃／分で測定した。
（２）極限粘度
フエノールと四塩化エタンとの等重量混合物を溶媒とし、温度２０℃で測定した。
（３）繊維長および繊維径
ＪＩＳ Ｌ １０１５ ７．４の方法により測定した。なお繊維径は求めた繊度（デニール）より、次式によって算出した。
繊維径（μｍ）＝２×（１０００×ｄ／９ρπ）^1/2
（ｄ；繊度（デニール）、ρ；繊維の密度（＝1.39））
【００２３】
（４）水分率
繊維を７０℃、３０分で乾燥し、次式により水分率を求めた。
水分率（重量％）＝｛（乾燥前重量−乾燥後重量）／乾燥前重量｝×１００
【００２４】
（５）油剤付着量
ｎ−ヘプタンで油剤を繊維から抽出し、ｎ−ヘプタンを蒸発乾固させた後、重量を測定して算出した。
油剤付着量（重量％）＝（抽出油剤重量／抽出前繊維重量）×１００
【００２５】
（６）カット後の分散性
ポリエステルノークリンプトウを５０万デニールに集束して所定の長さに切断した後の分散状態を目視にて判定した。
１；カールもなく、繊維の絡まりもなく、１本１本が分散している。
２；カールはないが繊維の絡まりが見られる。
３；カールが発生し、繊維も絡まっている。
【００２６】
（７）ゴム中の分散性
１７０℃で溶融したゴム中にポリエステルノークリンプショートカット繊維を５重量％入れて、単軸ニーダで混練した後、金型に入れて固化する。固化した後、縦１０ｃｍ、横１０ｃｍ、厚さ５ｍｍのサンプルを１０枚採取した。サンプルの表面を観察し、繊維の分散性、カールの有無を評価した。
１；カールもなく、繊維の絡まりもなく、１本１本が分散している。
２；カールが発生したり、未分散部分が残ったりして繊維が分散していないかたまりが見られる。
【００２７】
（８）ゴム混練時の異物発生
上記（７）の試験サンプルの表面を顕微鏡で観察し、ゴム中の異物を観察した。
１；異物が全く存在しない。
２；異物の存在が認められる。
【００２８】
実施例１
融点２６０℃、極限粘度０．６３のポリエチレンテレフタレートを、紡糸温度２９０℃、吐出量３００ｇ／分、紡糸速度６００ｍ／分の条件で、孔径０．６φ、ホール数６０の丸型断面のノズルで紡出して未延伸糸を得た。これを集束して１０万デニールのトウにして延伸倍率４．７、温度８０℃で延伸し、続いて２００℃で熱処理を行い、冷却スプレーで冷却後平滑剤・帯電防止剤を主成分とする濃度２．０％の仕上げ油剤を付与し、ニップローラーで水分を調整してノークリンプトウを得た。これを２ｍｍの長さに切断して繊維径５０μｍのポリエステルノークリンプショートカット繊維を得た。この繊維を用い、前記した条件でゴム中の分散性などを調べた。
【００２９】
実施例２〜１０および比較例１〜１１
繊維長、繊維径、水分率、油剤付着量を表１に記載する値に変更した以外は、実施例１と同様な方法でノークリンプショートカット繊維を得た。
【００３０】
実施例１〜１０および比較例１〜１１の特性値を表１に示す。
【００３１】
【表１】

【００３２】
表１から明らかなように実施例１〜１０は本発明の要件を満たすものであり、カット後の分散性、ゴム中の分散性、ゴム混練時の異物発生などの評価項目は何れも問題はなく、良好である。
【００３３】
これに対し、比較例１はカット長が短く、また繊維径が細すぎるため、カット時の摩擦のためにカールが発生した。比較例２、６はカット長と繊維径の関係が適正でないため、単糸同志の絡みが激しく、溶融ゴム中で混練したときに分散しなかった。
【００３４】
比較例３は繊維径が太すぎるため集束性が悪く、カット時に乱れが生じて、ミスカットが発生したり糸同志の密着が見られた。比較例４、５は繊維長が短かすぎるためカット時の摩擦が激しく、カールが発生した。
【００３５】
比較例７は水分率が低すぎるため、カット時にトウが乱れ、ばらついた結果ミスカットやカールの発生が見られた。比較例８は油剤付着量が多すぎるため、溶融ゴム中で混練したときに煙が発生し、サンプルを観察したときに異物が認められた。比較例９は水分率が高すぎるため、ゴム混練時に水蒸気が発生しサンプル中に気泡が残ったと同時にサンプル中での分散性も悪かった。比較例１０は油剤付着量が少なすぎるためカット時の摩擦が激しく、カールが発生した。比較例１１は水分率と油剤付着量の関係が適正でないため、カット時にトウが乱れ、ばらついた結果ミスカットやカールの発生が見られた。
【００３６】
【発明の効果】
以上のように本発明のポリエステルノークリンプショートカット繊維は、繊維長、繊維径、水分率、油剤付着量を規定することで、溶融ゴム中に混練しても繊維がカールすることなく、単繊維同志の絡みがなくなり、媒体中で良好な分散性を示す。その結果、ゴム中に繊維が均一に分散され、ゴムの改質効果が高くなる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polyester no crimp shortcut fiber for kneading rubber having excellent performance as a modifier for rubber (natural rubber, synthetic rubber, etc.) used as industrial materials.
[0002]
[Prior art]
Traditionally, we have reinforced rubber products with fibers to improve strength, pressure resistance and dimensional stability. Examples of such a fiber material include long fibers such as nylon, polyester, and vinylon. However, it has been rarely carried out until now to knead the fibers into a rubber product in the form of short-cut short fibers and use it as a reinforcing material.
[0003]
Until now, as a rubber reinforcing material using general-purpose fibers, JP-A-2-118119 discloses that polyester fibers having high strength and high elastic modulus are kneaded in the form of short fibers. However, when short fibers are kneaded in high-temperature molten rubber, the short fibers curl and the short fibers are entangled with each other, so that there is a disadvantage that the short fibers do not disperse well in the rubber. Japanese Patent Application Laid-Open No. 60-65117 discloses a method for solving the problem of curling short fibers by regulating the oil component to increase the affinity with rubber. It has not been completely resolved.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a polyester no crimp shortcut fiber that solves the problem of curling of the above-mentioned shortcut fibers and quickly disperses when kneaded into molten rubber as a rubber modifier. It is.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that it is effective to use fibers having the characteristics described below, and have reached the present invention. That is, the present invention provides a no-crimp shortcut fiber made of polyester having a melting point of 220 ° C. or more, a fiber length of 1 mm to 10 mm, a fiber diameter of 20 μm to 70 μm, and a moisture content of 2 wt% to 4 wt%. In the following, the oil agent adhesion amount is 0.01 wt% or more and 0.4 wt% or less, and further satisfies the relationship between the fiber length and fiber diameter of Equation (1) and the relationship between the moisture content and Equation (2) of Equation (2). The gist is a polyester no crimp shortcut fiber for kneading rubber.
[0006]
[Equation 3]

[0007]
[Expression 4]

[0008]
As described above, the polyester no-crimp shortcut fiber of the present invention regulates the fiber length, fiber diameter, moisture content, and oil adhesion amount, so that the fibers do not curl even when kneaded into molten rubber, No entanglement is observed and good dispersibility is exhibited in the medium. As a result, the fibers are uniformly dispersed in the rubber, and the rubber reforming effect is enhanced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The melting point of the polyester fiber of the present invention needs to be 220 ° C. or higher. When the melting point is less than 220 ° C., the polyester fibers are kneaded into a high-temperature rubber, so that the single yarns are fused or the physical properties of the fiber are greatly changed.
[0010]
Specifically, polyethylene terephthalate or polyethylene naphthalate is preferably used as such a polyester polymer. Moreover, even if it contains pigments, such as titanium oxide, antioxidants, such as a hindered phenol type compound, and other various additives, if it is a range which does not interfere with the effect of this invention, it does not interfere.
[0011]
The polyester no crimp shortcut fiber of the present invention is required to have a fiber length of 1 mm or more and 10 mm or less. Especially preferably, it is the range of 1 mm or more and 5 mm or less. If it is less than 1 mm, curling tends to occur due to frictional heat when cutting, which is not preferable. On the other hand, if it is longer than 10 mm, poor dispersion tends to occur when kneaded in rubber, which is not preferable.
[0012]
The polyester no crimp shortcut fiber of the present invention needs to have a fiber diameter of 20 μm or more and 70 μm or less. Especially preferably, it is the range of 30 micrometers or more and 60 micrometers or less. When the single yarn diameter is less than 20 μm, the single yarn dispersibility is poor, and the bending rigidity is insufficient, and curling tends to occur. On the other hand, when the thickness is larger than 70 μm, the convergence of tow is remarkably deteriorated, and the productivity is lowered.
[0013]
The polyester no crimp shortcut fiber of the present invention needs to satisfy the following formula (5).
[0014]
[Equation 5]

[0015]
If this is not satisfied, the rigidity against bending is insufficient, and the fiber is likely to curl, which is not preferable.
The polyester no-crimp shortcut fiber of the present invention needs to have a moisture content of 2% by weight to 4% by weight. If the moisture content is less than 2% by weight, the workability at the time of shortcut due to the dispersion of the fibers due to the generation of static electricity is not preferable. When the moisture content exceeds 4% by weight, a large amount of water vapor is generated when kneading into rubber, and bubbles are not formed in the product or when the fibers are kneaded, the fiber is not fully opened and an undispersed part remains. Therefore, it is not preferable.
[0016]
The polyester no crimp shortcut fiber of the present invention is required to have an oil agent adhesion amount of 0.01 wt% or more and 0.4 wt% or less. When the amount of the oil agent is less than 0.01% by weight, static electricity is generated, and the tow is scattered at the time of performing a shortcut. If the amount of the oil agent is more than 0.4% by weight, foreign matter due to the oil agent may be generated in the rubber after kneading, or fibers may stick together and an undispersed part may remain in the rubber.
[0017]
The polyester no crimp shortcut fiber of the present invention needs to satisfy the following formula (6).
[0018]
[Formula 6]

[0019]
If this is not satisfied, problems such as poor fiber dispersion, generation of water vapor, and generation of foreign matter occur, which is not preferable.
A method of manufacturing so as to satisfy Equation 6 is as follows. That is, about 0.05% by weight of spinning oil is applied in the spinning process. Subsequently, the undrawn yarn converges to a tow state and is drawn, and is heat-treated at about 200 ° C. to make it completely dry. Thereafter, the tow is cooled with a cooling roller or a cooling spray, a finishing oil agent having a predetermined concentration is applied, and the water content is adjusted with a nip roller. The moisture content can be adjusted not only by the pressure of the nip roller but also by the spray amount of the cooling spray and the amount of the finish oil applied.
[0020]
In addition, there exist a smoothing agent, a convergence agent, an emulsifier, an antistatic agent etc. as a component mix | blended with the oil agent used for this invention. As the smoothing agent, sulfates of higher alcohols, alkyl phosphates and the like are used. The blending amount is desirably about 5 to 40% of the entire composition. As the sizing agent, a metal salt of lauryl phosphate is preferably used. The blending amount is desirably about 5 to 40% of the entire composition. As the emulsifier, a nonionic surfactant such as an alkyl ether of polyoxyethylene is preferably used. The blending amount is desirably about 5 to 40% of the entire composition. As the antistatic agent, metal salts such as alkyl sulfonates and alkyl phosphates or metal salts of fatty acids are preferably used. The amount is preferably about 1 to 20% of the total composition. In addition to these compositions, a rust inhibitor, an antibacterial agent, an antioxidant and other modifiers may be included as long as they do not impair the object of the present invention.
[0021]
The cross-sectional shape of the polyester no crimp shortcut fiber of the present invention is not particularly limited, but a round cross section, a triangular cross section, a hollow cross section, an H-shaped cross section, or the like is preferably used.
[0022]
(Example)
Next, the present invention will be specifically described with reference to examples. In addition, the evaluation method of each characteristic in an Example is as follows.
(1) Melting | fusing point It measured with the temperature increase rate of 20 degree-C / min using the differential scanning calorimeter DSC-2 type made from Perkin Elmer.
(2) Measurement was carried out at a temperature of 20 ° C. using an equal weight mixture of intrinsic viscosity phenol and ethane tetrachloride as a solvent.
(3) Fiber length and fiber diameter Measured by the method of JIS L 1015 7.4. The fiber diameter was calculated from the calculated fineness (denier) by the following formula.
Fiber diameter (μm) = 2 × (1000 × d / 9ρπ) ^1/2
(D; fineness (denier), ρ; fiber density (= 1.39))
[0023]
(4) Moisture content fiber was dried at 70 ° C. for 30 minutes, and the moisture content was determined by the following formula.
Moisture content (% by weight) = {(weight before drying−weight after drying) / weight before drying} × 100
[0024]
(5) Oil agent adhesion amount The oil agent was extracted from the fiber with n-heptane, and after evaporating and drying n-heptane, the weight was measured and calculated.
Oil adhesion amount (% by weight) = (weight of extracted oil / weight of fiber before extraction) × 100
[0025]
(6) Dispersibility after cutting The disperse polyester noclampto was focused to 500,000 denier and cut into a predetermined length to visually determine the dispersion state.
1: No curling, no entanglement of fibers, and each one is dispersed.
2: There is no curl, but fiber entanglement is observed.
3; Curling occurs and fibers are tangled.
[0026]
(7) Dispersibility in rubber 5% by weight of polyester no-crimp shortcut fiber is put in rubber melted at 170 ° C., kneaded with a uniaxial kneader, and then solidified in a mold. After solidification, 10 samples having a length of 10 cm, a width of 10 cm, and a thickness of 5 mm were collected. The surface of the sample was observed, and the dispersibility of the fibers and the presence or absence of curling were evaluated.
1: No curling, no entanglement of fibers, and each one is dispersed.
2: Curls are generated or undispersed portions remain, and a lump in which fibers are not dispersed is observed.
[0027]
(8) Generation of foreign matter during rubber kneading The surface of the test sample of (7) above was observed with a microscope, and foreign matters in the rubber were observed.
1; no foreign matter is present.
2: Existence of foreign matter is recognized.
[0028]
Example 1
Polyethylene terephthalate having a melting point of 260 ° C. and an intrinsic viscosity of 0.63 was spun by a round cross-section nozzle having a hole diameter of 0.6φ and a hole number of 60 at a spinning temperature of 290 ° C., a discharge rate of 300 g / min, and a spinning speed of 600 m / min. The undrawn yarn was obtained. This is concentrated to a tow of 100,000 denier, drawn at a draw ratio of 4.7 and at a temperature of 80 ° C., subsequently heat-treated at 200 ° C., cooled with a cooling spray, and then mainly composed of a smoothing agent and an antistatic agent. A finishing oil agent having a concentration of 2.0% was applied, and moisture was adjusted with a nip roller to obtain a no-crimptow. This was cut into a length of 2 mm to obtain a polyester no crimp shortcut fiber having a fiber diameter of 50 μm. Using this fiber, the dispersibility in rubber was examined under the conditions described above.
[0029]
Examples 2 to 10 and Comparative Examples 1 to 11
A no-crimp shortcut fiber was obtained in the same manner as in Example 1 except that the fiber length, fiber diameter, moisture content, and oil adhesion amount were changed to the values shown in Table 1.
[0030]
Table 1 shows the characteristic values of Examples 1 to 10 and Comparative Examples 1 to 11.
[0031]
[Table 1]

[0032]
As is apparent from Table 1, Examples 1 to 10 satisfy the requirements of the present invention, and there are problems with any of the evaluation items such as dispersibility after cutting, dispersibility in rubber, and generation of foreign matter during rubber kneading. Not good.
[0033]
On the other hand, in Comparative Example 1, the cut length was short and the fiber diameter was too thin, so curling occurred due to friction during cutting. In Comparative Examples 2 and 6, since the relationship between the cut length and the fiber diameter was not appropriate, the single yarns were strongly entangled and did not disperse when kneaded in molten rubber.
[0034]
In Comparative Example 3, since the fiber diameter was too thick, the convergence property was poor, disturbance occurred at the time of cutting, miscutting occurred, and close contact between yarns was observed. In Comparative Examples 4 and 5, since the fiber length was too short, the friction at the time of cutting was intense, and curling occurred.
[0035]
In Comparative Example 7, since the moisture content was too low, tow was disturbed during cutting, and as a result of variation, miscutting and curling were observed. In Comparative Example 8, since the amount of the oil agent adhered was too large, smoke was generated when kneaded in molten rubber, and foreign matters were observed when the sample was observed. In Comparative Example 9, since the moisture content was too high, water vapor was generated during rubber kneading, and bubbles remained in the sample, and at the same time, the dispersibility in the sample was poor. In Comparative Example 10, since the amount of the oil agent adhered was too small, the friction during cutting was intense and curling occurred. In Comparative Example 11, since the relationship between the moisture content and the amount of oil adhered was not appropriate, tow was disturbed during cutting, and as a result of variation, miscutting and curling were observed.
[0036]
【The invention's effect】
As described above, the polyester no-crimp shortcut fiber of the present invention regulates the fiber length, fiber diameter, moisture content, and oil adhesion amount, so that even if kneaded into molten rubber, the fiber does not curl, No entanglement is observed and good dispersibility is exhibited in the medium. As a result, the fibers are uniformly dispersed in the rubber, and the rubber reforming effect is enhanced.

Claims (1)

A no-crimp shortcut fiber made of polyester having a melting point of 220 ° C. or higher, having a fiber length of 1 mm to 10 mm, a fiber diameter of 20 μm to 70 μm, and a moisture content of 2 wt% to 4 wt%. The amount is 0.01% by weight or more and 0.4% by weight or less, and further satisfies the relationship between the fiber length and the fiber diameter of Formula 1, and the relationship between the moisture content and the amount of oil agent attached according to Formula 2. Polyester no crimp shortcut fiber for kneading rubber.