JP3623043B2 - Polyester no crimp shortcut fiber for kneading rubber - Google Patents

Description

【０００７】
【数４】

【０００８】
【化２】

【０００９】
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、繊度、乾熱収縮率、油剤を規定することで、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。
【００１０】
【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。
【００１１】
このような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タ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、ヒンダート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。
【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より長いとゴムに混練した際に分散不良を生じやすくな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、単糸繊度が５ｄ以上４０ｄ以下であることが必要である。特に好ましくは、１０ｄ以上３０ｄ以下である。単糸繊度が５ｄ未満であると単糸分散性が悪く、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、４０ｄより太いとトウの集束性が著しく悪くなり、生産性が悪化し好ましくない。
【００１４】
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。
【００１５】
【数５】

【００１６】
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。
また、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、処理温度ｘ℃（１７０℃≦ｘ≦２１０℃）で測定したときの乾熱収縮率ｙが下記の数６式を満足する必要がある。
【００１７】
【数６】

【００１８】
乾熱収縮率が０．１２５ｘ−２１．２５（１７０℃≦ｘ≦２１０℃）未満であると製糸時に高温の熱処理が必要になり、繊維を安定して生産することが難しくなる。また、乾熱収縮率が０．１２５ｘ−１６．２５（１７０℃≦ｘ≦２１０℃）を超えると、繊維を高温のゴム中に混練するときに繊維がカールして分散不良を起こしやすくなり好ましくない。
【００１９】
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、下記の化学構造式Ａを主成分とする油剤が０．０５重量％以上１．０重量％以下付着している必要がある。さらに好ましくは０．１重量％以上０．５重量％以下付着しているのが良い。０．０５重量％未満であるとカット時に繊維束が乱れて繊維長がばらばらになり好ましくない。また、１．０重量％を超えると繊維同志が固着し、ゴムに混練した際にも１本１本がばらばらに開繊せず、ゴム中に未分散部分が残り好ましくない。
【００２０】
【化３】

【００２１】
前記油剤の主成分は組成全体の１０％以上４０％以下であることが必要である。含有量が１０％未満であると油剤全体に均一に分散しなくなり、繊維トウの集束性にムラができ好ましくない。含有量が４０％を超えると油剤が、トウ表面に固く付着し、この場合も混練後に未分散部分が残り、好ましくない。
【００２２】
また、この油剤の主成分は前記化学構造式Ａのａ：ｂの比率が２：８〜以上８：２以下である必要がある。２：８未満、あるいは８：２を超えると油剤の集束性、分散性が著しく変化し好ましくない。
【００２３】
さらに、この油剤の主成分は分子量が１０００以上１０００００以下である必要がある。分子量が１０００未満であると糸同志が油剤を被覆されない状態で接触して糸摩擦が大きくなり好ましくない。分子量が１０００００より大きいと油剤を繊維に均一に付着させることが難しくなり好ましくない。
【００２４】
前記化学構造式ＡのＲ_２ の具体例としては、フタル酸あるいはアジピン酸などの残基が挙げられる。Ｒ_３ としてはメチル基、エチル基などが挙げられる。油剤に配合される他成分としては乳化剤、帯電防止例などがある。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５〜５０％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、あるいは脂肪族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１〜３０％程度が好ましい。なお、これらの組成以外にも防錆剤、抗菌剤、酸化防止剤、その他改質剤などを含んでいても、本発明の目的が損なわない範囲であればかまわない。
【００２５】
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、Ｈ型断面などが好適に用いられる。
【００２６】
（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
フェノールと四塩化エタンとの等量混合物を溶媒として、温度２０℃で測定した。
（３）繊維長および繊度
ＪＩＳ Ｌ １０１５ ７．４の方法により測定した。
（４）乾熱収縮率
延伸、熱処理後の繊維を、約１５ｍｍに切断し、この繊維に５０ｍｇ／ｄの荷重をかけて繊維長Ｌｏを測定し、１２０℃の加熱オーブン中で１５分間放置する。ついで繊維長Ｌを５０ｍｇ／ｄの荷重をかけて測定し、次の式で算出した。
乾熱収縮率（％）＝｛（Ｌｏ−Ｌ）／Ｌｏ｝×１００
（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
（６）カット後の分散性
ポリエステルノークリンプトウを５０万デニールに収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。
（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】
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、紡糸速度６００ｍ／ｍｉｎ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、化学構造式Ａにおいて表２のＲ_１ ，Ｒ_２ ，Ｒ_３ 、ａ，ｂ，ｎの組み合わせで表される組成の化合物を２０％、乳化剤を４０％、帯電防止剤を３０％、酸化防止剤を１０％含む油剤Ｂを付着量が０．３重量％になるように付与して２ｍｍの長さに切断して単糸繊度２０ｄのノークリンプショートカット繊維を得た。
【００２８】
実施例２〜８
繊維長、単糸繊度、油剤付着量、前記化学構造式Ａで示される化合物の種類を表１および表２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。
【００２９】
比較例１，２
繊維長を表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】
比較例３
単糸繊度を表１に記載する値に変更した以外は、実施例１と同様な方法で単糸繊度４ｄのノークリンプショートカット繊維を得た。
【００３１】
比較例４
延伸時の熱処理温度を１６０℃にした以外は、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。
【００３２】
比較例５
延伸時に１６０℃の温度で弛緩熱処理した以外は、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。
【００３３】
比較例６
延伸時の熱処理温度を１９０℃にした以外は、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。
【００３４】
比較例７，８
油剤付着量を表１に記載の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。
【００３５】
比較例９〜１４
油剤種類を表２に記載の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。なお、前記化学構造式Ａで示される化合物の配合量を変更した場合、乳化剤の配合量変化で全体を調整した。
【００３６】
前記実施例１〜８、比較例１〜１４の特性値を表１、表２に示す。
【００３７】
【表１】

【００３８】
【表２】

【００３９】
表１、表２から明らかなように実施例１〜８は本発明の要件を満たすものであり、カット後の分散性、ゴム中の分散性などの評価項目は何れも良好である。
これに対し、比較例１はカット長が短すぎるため、カット時の摩擦が激しくカールが発生した。比較例２はカット長が長すぎるため、単糸同志の絡みが激しく、溶融ゴムに混練したときに分散しなかった。比較例３は繊度が細すぎるため、カット時にカールが発生した。比較例４〜６は乾熱収縮率が高いため、溶融ゴムに混練したときにカールが発生しゴム中の分散が良くなかった。比較例７は油剤付着量が低すぎるため、カット時に繊維束が乱れ、ばらついた結果カールが発生した。比較例８は油剤付着量が多すぎるため、繊維がばらばらに開繊しにくく、サンプルを観察したときに繊維の未分散部分が認められた。比較例９はカット時に糸同志の摩擦が激しくカールが発生してしまった。比較例１０は糸同志が密着してしまい、ゴム中に均一に分散しなかった。比較例１１〜１４はカット時に繊維束が乱れ、ばらついた結果カールが発生した。
【００４０】
【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、繊度、乾熱収縮率、油剤を規定することで、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 nylon, polyester, and vinylon. However, there has been almost no method for modifying a fiber by kneading the fiber into a rubber product in the form of a short fiber which is shortcut.
[0003]
Until now, as a rubber modifier 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 solve the problem of curling of the above-mentioned shortcut fibers, and to provide a polyester no crimp shortcut fiber that rapidly disperses when kneaded in molten rubber as a rubber modifier. is there.
[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 is a no crimp shortcut fiber made of polyester having a melting point of 220 ° C. or more, the fiber length is 1 mm or more and 10 mm or less, the single yarn fineness is 5 d or more and 40 d or less, and the relationship between the fiber length and the fineness of Formula 3 And an oil agent containing 10% or more and 40% or less of a modified ether polyester having a molecular weight of 1,000 or more and 100,000 or less represented by the following chemical structural formula A: A gist is a polyester no-crimp shortcut fiber for kneading rubber, which is attached in an amount of 0.05% by weight to 1.0% by weight.
[0006]
[Equation 3]

[0007]
[Expression 4]

[0008]
[Chemical formula 2]

[0009]
As described above, the polyester no crimp shortcut fiber of the present invention regulates the fiber length, fineness, dry heat shrinkage rate, and oil agent, so that even if kneaded into molten rubber, the fiber does not curl and the single fibers are entangled. And good dispersibility in the medium. As a result, the fibers are uniformly dispersed in the rubber, and the rubber reforming effect is enhanced.
[0010]
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., polyester fibers are kneaded with a high-temperature rubber, so that the single yarns are fused or the physical properties of the fiber are greatly changed.
[0011]
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 the range which does not interfere with the effect of this invention, it does not interfere.
[0012]
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 into rubber, which is not preferable.
[0013]
The polyester no crimp shortcut fiber of the present invention needs to have a single yarn fineness of 5d to 40d. Particularly preferably, it is 10d or more and 30d or less. If the single yarn fineness is less than 5d, the single yarn dispersibility is poor, the bending stiffness is insufficient, and curling tends to occur. On the other hand, if it is thicker than 40d, the convergence of the tow is remarkably deteriorated and the productivity is deteriorated, which is not preferable.
[0014]
The polyester no crimp shortcut fiber of the present invention needs to satisfy the following formula (5).
[0015]
[Equation 5]

[0016]
If this is not satisfied, the rigidity against bending is insufficient, and the fiber is likely to curl, which is not preferable.
Further, the polyester no crimp shortcut fiber of the present invention needs to satisfy the following formula 6 in terms of dry heat shrinkage y when measured at a processing temperature x ° C. (170 ° C. ≦ x ≦ 210 ° C.).
[0017]
[Formula 6]

[0018]
When the dry heat shrinkage ratio is less than 0.125x-21.25 (170 ° C. ≦ x ≦ 210 ° C.), high-temperature heat treatment is required at the time of yarn production, and it becomes difficult to stably produce fibers. Moreover, when the dry heat shrinkage rate exceeds 0.125x-16.25 (170 ° C. ≦ x ≦ 210 ° C.), the fibers tend to curl when the fibers are kneaded into a high-temperature rubber, and dispersion failure is likely to occur. Absent.
[0019]
In the polyester no-crimp shortcut fiber of the present invention, it is necessary that an oil whose main component is the following chemical structural formula A is attached in an amount of 0.05% by weight to 1.0% by weight. More preferably, it is 0.1 to 0.5% by weight. If it is less than 0.05% by weight, the fiber bundles are disturbed at the time of cutting, and the fiber lengths are not preferable. On the other hand, when the amount exceeds 1.0% by weight, the fibers adhere to each other, and even when they are kneaded with rubber, each one does not open apart, leaving undispersed portions in the rubber, which is not preferable.
[0020]
[Chemical 3]

[0021]
The main component of the oil agent needs to be 10% or more and 40% or less of the entire composition. If the content is less than 10%, it is not preferable that the oil agent is not uniformly dispersed throughout, and the fiber tow has uneven convergence. When the content exceeds 40%, the oil agent adheres firmly to the tow surface, and in this case, an undispersed portion remains after kneading, which is not preferable.
[0022]
In addition, the main component of the oil agent is required to have a ratio of a: b in the chemical structural formula A of 2: 8 to 8: 2. If it is less than 2: 8 or more than 8: 2, the convergence and dispersibility of the oil agent change remarkably, which is not preferable.
[0023]
Furthermore, the main component of this oil agent needs to have a molecular weight of 1,000 or more and 100,000 or less. When the molecular weight is less than 1000, the yarns come into contact with each other without being coated with the oil agent, and the yarn friction is increased. When the molecular weight is larger than 100,000, it is difficult to uniformly attach the oil agent to the fiber, which is not preferable.
[0024]
Specific examples of R _{2 in} the chemical structural formula A include residues such as phthalic acid or adipic acid. Examples of R ₃ include a methyl group and an ethyl group. Other components blended in the oil include emulsifiers and antistatic examples. As the emulsifier, a nonionic surfactant such as an alkyl ether of polyoxyethylene is preferably used. The blending amount is desirably about 5 to 50% of the entire composition. As the antistatic agent, metal salts such as alkyl sulfonates and alkyl phosphates, or aliphatic metal salts are preferably used. The blending amount is preferably about 1 to 30% of the entire composition. In addition to these compositions, a rust inhibitor, an antibacterial agent, an antioxidant, and other modifiers may be included as long as the object of the present invention is not impaired.
[0025]
The cross-sectional shape of the polyester no crimp shortcut fiber of the present invention is not particularly restricted, but a round cross section, a triangular cross section, a hollow cross section, an H-shaped cross section, and the like are preferably used.
[0026]
(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) The measurement was carried out at a temperature of 20 ° C. using an equimolar mixture of intrinsic viscosity phenol and ethane tetrachloride as a solvent.
(3) Fiber length and fineness Measured by the method of JIS L 1015 7.4.
(4) The fiber after dry heat shrinkage stretching and heat treatment is cut to about 15 mm, the fiber length Lo is measured by applying a load of 50 mg / d to the fiber, and left in a heating oven at 120 ° C. for 15 minutes. . Next, the fiber length L was measured by applying a load of 50 mg / d, and calculated by the following formula.
Dry heat shrinkage (%) = {(Lo−L) / Lo} × 100
(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
(6) Dispersibility After cutting The disperse polyester noclampto was converged 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.
(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 to evaluate fiber dispersibility and curl.
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]
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, and a spinning speed of 600 m / min. An undrawn yarn was obtained. This is concentrated to make a tow of 100,000 denier, stretched at a stretching ratio of 4.7, and at a temperature of 80 ° C., followed by heat treatment at 200 ° C., and in the chemical structural formula A, R ₁ , R ₂ , R ₃ in Table 2 , 20% of a compound having a composition represented by the combination of a, b, and n, 40% of an emulsifier, 30% of an antistatic agent, and 10% of an oil agent B containing 10% of an antioxidant. Then, it was cut to a length of 2 mm to obtain a no crimp shortcut fiber having a single yarn fineness of 20 d.
[0028]
Examples 2-8
No crimp shortcut fiber in the same manner as in Example 1, except that the fiber length, single yarn fineness, oil adhesion amount, and the type of compound represented by the chemical structural formula A were changed to the values shown in Tables 1 and 2. Got.
[0029]
Comparative Examples 1 and 2
A no-crimp shortcut fiber was obtained in the same manner as in Example 1 except that the fiber length was changed to the value described in Table 1.
[0030]
Comparative Example 3
A no-crimp shortcut fiber having a single yarn fineness of 4d was obtained in the same manner as in Example 1 except that the single yarn fineness was changed to the value described in Table 1.
[0031]
Comparative Example 4
A no-crimp shortcut fiber was obtained in the same manner as in Example 1 except that the heat treatment temperature during drawing was 160 ° C.
[0032]
Comparative Example 5
A no-crimp shortcut fiber was obtained in the same manner as in Example 1 except that a relaxation heat treatment was performed at a temperature of 160 ° C. during stretching.
[0033]
Comparative Example 6
A no-crimp shortcut fiber was obtained in the same manner as in Example 1 except that the heat treatment temperature during stretching was 190 ° C.
[0034]
Comparative Examples 7 and 8
A no-crimp shortcut fiber was obtained in the same manner as in Example 1 except that the oil agent adhesion amount was changed to the value shown in Table 1.
[0035]
Comparative Examples 9-14
A no-crimp shortcut fiber was obtained in the same manner as in Example 1 except that the oil type was changed to the values shown in Table 2. In addition, when the compounding quantity of the compound shown by the said chemical structural formula A was changed, the whole was adjusted with the compounding quantity change of the emulsifier.
[0036]
The characteristic values of Examples 1 to 8 and Comparative Examples 1 to 14 are shown in Tables 1 and 2.
[0037]
[Table 1]

[0038]
[Table 2]

[0039]
As is clear from Tables 1 and 2, Examples 1 to 8 satisfy the requirements of the present invention, and all evaluation items such as dispersibility after cutting and dispersibility in rubber are good.
On the other hand, since the cut length of Comparative Example 1 was too short, the friction at the time of cutting was intense and curling occurred. In Comparative Example 2, since the cut length was too long, the single yarns were entangled with each other and did not disperse when kneaded into molten rubber. Since Comparative Example 3 was too fine, curling occurred during cutting. Since Comparative Examples 4 to 6 had a high dry heat shrinkage, curling occurred when kneaded with molten rubber, and the dispersion in the rubber was not good. In Comparative Example 7, since the amount of the oil agent adhered was too low, the fiber bundle was disturbed at the time of cutting, and as a result, the curl was generated. In Comparative Example 8, since the amount of the oil agent adhered was too large, the fibers were not easily spread apart, and an undispersed portion of the fibers was observed when the sample was observed. In Comparative Example 9, the friction between the yarns was severe at the time of cutting, and curling occurred. In Comparative Example 10, the yarns were in close contact with each other and were not uniformly dispersed in the rubber. In Comparative Examples 11 to 14, the fiber bundle was disturbed at the time of cutting, and as a result, the curl was generated.
[0040]
【The invention's effect】
As described above, the polyester no crimp shortcut fiber of the present invention regulates the fiber length, fineness, dry heat shrinkage rate, and oil agent, so that even if kneaded into molten rubber, the fiber does not curl and the single fibers are entangled. And good dispersibility in the medium. As a result, the fibers are uniformly dispersed in the rubber, and the rubber reforming effect is enhanced.

Claims (1)

In a no-crimp shortcut fiber made of polyester having a melting point of 220 ° C. or more, the fiber length is 1 mm or more and 10 mm or less, the single yarn fineness is 5d or more and 40d or less, and the relationship between the fiber length and the fineness of Formula 1 and Formula 2 0.05% by weight of an oil agent satisfying dry heat shrinkage properties and further containing 10% or more and 40% or less of a modified ether polyester having a molecular weight of 1,000 or more and 100,000 or less represented by the following chemical structural formula A A polyester no-crimp shortcut fiber for kneading rubber characterized in that it is adhered in an amount of not less than 1.0% and not more than 1.0% by weight.