High-tenacity conjugated fiber and process for preparation thereof

• US 4,987,030 A
• Filed: 10/04/1988
• Issued: 01/22/1991
• Est. Priority Date: 10/07/1987
• Status: Expired due to Term

• Current Assignee: Toray Industries Incorporated
• Original Assignee: Toray Industries Incorporated
• Inventors: Yamamoto, Masaharu, Sato, Takuji, Saito, Isoo, Kubota, Koichi
• Primary Examiner(s): KENDELL, LORRAINE
• Application Number:
  US07/253,135
• Time in Patent Office: 840 Days
• Field of Search: 428/373, 428/374, 428/401, 57/902, 264/171, 264/210.8, 152/359
• US Class Current: 428/373
• CPC Class Codes: D01F 8/12 with at least one polyamide as constituent
• CPC Class Codes: D01F 8/14 with at least one polyester as constituent
• CPC Class Codes: Y10S 57/902 Reinforcing or tire cords
• CPC Class Codes: Y10T 428/2929 Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
• CPC Class Codes: Y10T 428/2931 Fibers or filaments nonconcentric [e.g., side-by-side or eccentric, etc.]

Abstract

A conjugated fiber having a sheath-core conjugated structure comprising a polyester core component composed mainly of polyethylene terephthalate and a polyamide sheath component composed mainly of polyhexamethylene adipamide, is disclosed, which has excellent mechanical properties such as a high tenacity, a high modulus, and an improved dimensional stability, and an improved adhesion to a rubber, especially a high-temperature adhesion, an improved heat resistance in a rubber, and a high fatigue resistance, and thus is useful as an industrial material. By adopting a high-speed spinning procedure in the fiber preparing process, the peel resistance in the interface of the sheath-core conjugated structure is greatly improved, and the following valuable characteristics not possessed by conventional conjugated yarns can be obtained:

(1) Excellent adhesion and high-temperature adhesion comparable to those of a polyamide, which cannot be obtained in a polyester.

(2) High modulus and dimensional stability comparable to those of a polyester, which cannot be obtained in a polyamide.

(3) A heat resistance in a rubber and a fatigue resistance superior to those of a polyester.

Claims

1. A high-tenacity conjugated fiber having a sheath-core conjugated structure consisting essentially of a polyester composed mainly of ethylene terephthalate units as the core component and a polyamide as the sheath component, wherein the ratio of the core component to the sum of the core component and sheath component is 30 to 90% by weight, and the conjugated fiber has (a) a hynamic elasticity (E'"'"'₂₀) at 20°

C. of at least 8×

10⁴ dyne/denier and a dynamic elasticity (E'"'"'₁₅₀) at 150°

C. of at least 3×

10⁴ dyne/denier, as measured at 110 Hz, and a main dispersion peak temperature (Tα

) of at least 140°

C. in the mechanical loss tangent (tan δ

) curve, (b) a creep rate (CR₂₀) not larger than 2.0% as measured at 20°

C. after 48 hours'"'"' standing under a load of 1 g/denier and a creep rate (CR₁₅₀) not larger than 3.0% as measured at 150°

C. after 48 hours'"'"' standing under a load of 1 g/denier, (c) an intrinsic viscosity ([η

]) of at least 0.8 and a birefringence (Δ

n) of 160×

10^-3 to 190×

10^-3 in the polyester core component, (d) a sulfuric acid relative viscosity (η

r) of at least 2.8 and a birefringence (Δ

n) of at least 50×

10^-3 in the polyamide sheath component, (e) a tenacity (T/D) of at least 7.5 g denier, (f) an initial modulus in tension (Mi) of at least 60 g/denier, and (g) a dry heat shrinkage (Δ

S₁₅₀) as measured at 150°

C. of not larger than 7%.

2. A high-tenacity conjugated fiber as set forth in claim 1, wherein the polyester core component has a density (η

) of at least 1.395 g/cm³ and the polyamide sheath component has a density (η

) of at least 1.135 g/cm³.

3. A high-tenacity conjugated fiber as set forth in claim 1, wherein the polyester core component has an initial modulus in tension (Mi) at least 90 g/denier and a terminal modulus in tension (Mt) not larger than 20 g/denier.

4. A high-tenacity conjugated fiber as set forth in claim 1, which has a tenacity (T/D) of at least 7.5 g/denier, an initial modulus in tension (Mi) of at least 60 g/denier, and a dry heat shrinkage (Δ

S₁₅₀) as measured at 150°

C. of not larger than 7%.