Polyhexamethylene adipamide fibers and process for producing the

Details Polyhexamethylene adipamide fibers and process for producing the Polyhexamethylene adipamide fibers and process for producing the

1996-11-25

1999-07-27

Short, Patricia A.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

524126, 524128, 524135, 524151, 524153, 524414, C08L 7706

Patent

active

059291486

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The present invention relates to hexamethylene adipamide fibers having significantly excellent thermal yellowing resistance to heat during fiber processing, etc. and a composition thereof, and a process for advantageously-producing such fibers. The present invention relates to polyhexamethylene adipamide fibers for clothing capable of being dyed in bright shades and dyed deeply in addition to having significantly excellent thermal yellowing resistance, and a commercially advantageous process for producing the same.


BACKGROUND OF THE INVENTION

Since polyamides (nylon) are generally excellent in mechanical properties and durability, they are used in large amounts as fibers for industrial materials such as tire cords, fibers for carpet and molded articles. On the other hand, polyamides are also used in large amounts as fibers for clothing, particularly for inner wear due to their excellent flexibility and dyeability.
Polyhexamethylene adipamide (nylon 66) is a typical representative of polyamides, and is also used as fibers for industrial materials, fibers for carpet, fibers for clothing, molded articles, and the like. Polyhexamethylene adipamide, however, has a serious disadvantage as fiber for clothing in that it suffers considerable thermal yellowing compared with poly-.epsilon.-capramide (nylon 6) which is also a typical representative of polyamides. The disadvantage matters a great deal regardless of whether it is used as fibers or molded articles, in application where the whiteness in external appearance is required. In addition to the fact that fibers for clothing are particularly susceptible to oxidation inherently due to the small single fiber diameter (large specific surface area), they are thermally set (heat treated) without exception in the process for producing fabrics and in fabrication. As a result, the problem of yellowing mentioned above is manifested. The use of polyhexamethylene adipamide in fibers for clothing is, therefore, extremely limited.
For example, inner wear such as lingerie and foundation garments is an appropriate application for polyamide fibers having flexibility and suitable hygroscopicity. Since polyhexamethylene adipamide fibers suffer considerable yellowing during thermal setting as described above, the whiteness of the products is lowered or the color development thereof becomes a dull shade (dull in shade). Accordingly, the polyhexamethylene adipamide fibers are not substantially used at present for inner wear. Poly-.epsilon.-capramide fibers and polyester fibers have overwhelmingly high shares at present in the application thereof to the inner wear.
Since the poly-.epsilon.-capramide fibers are significantly excellent in thermal yellowing resistance and suffer thermal setting-caused yellowing very slightly, compared with the polyhexamethylene adipamide fibers, they can be used for the inner wear substantially without a problem. Moreover, the polyester fibers have still more excellent thermal yellowing resistance than the poly-.epsilon.-capramide fibers, and suffer almost no yellowing caused by thermal setting, that is, the whiteness of the fibers is maintained.
Improving the thermal yellowing resistance of the polyhexamethylene adipamide fibers to a level comparable to that of the poly-.epsilon.-capramide fibers is, therefore, the first goal for the manufacturers thereof. Improving the resistance to a level comparable to that of the polyester fibers is the final goal for them. The techniques for achieving these goals, however, have not been created.
In melt molding and melt spinning thermoplastic organic polymer, a thermal stabilizer such as a thermal oxidation inhibitor is incorporated in the polymer starting materials to inhibit or decrease the thermal alteration such as thermal degradation and discoloration of the polymer. Although the selection of suitable additives depends on the types of polymers, examples the thermal stabilizer commonly used for polymers which have currently been used at large are phenolic antioxidants including hinder

REFERENCES:
patent: 3078248 (1963-02-01), Ben
patent: 3334046 (1967-08-01), Dexter et al.

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