Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2002-09-11
2003-10-07
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S372000, C428S395000, C428S398000, C428S400000, C264S103000, C264S210800, C264S210500, C264S3420RE, C264S210100
Reexamination Certificate
active
06630240
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a bulky polyester multifilament composite yarn and a process for producing the same. Particularly, the present invention relates to a bulky polyester multifilament composite yarn comprising two types of polyester filaments differing from each other in average single filament length, in which the polyester filaments having a larger average single filament length contain a micropore-forming agent to cause the composite yarn to exhibit a high bulkiness and a good hand, and a high productivity and process stability in production thereof, and a process for producing the same.
BACKGROUND ART
A bulky synthetic multifilament textured yarn has heretofore been produced by simultaneously drawing and false twisting and/or drawing a raw yarn comprising at least two types of multifilaments differing in drawability, thermal shrinkage and/or elastic recovery from each other. In the conventional process, differences of the elongation and/or thermal shrinkage among the at least two types of multifilaments are utilized, and differences of the multifilament length among the types of multifilaments in the composite yarn are enlarged. As a result, gaps among individual filaments in the resultant multifilament yarn are enlarged, and filaments having a shorter length and a portion of filaments having a longer length form the core portion of the multifilament yarn; the remainder of the filaments having a longer length are bulged outward from the core portion to form a sheath portion. Consequently, the bulkiness of the multifilament yarn is significantly increased.
A woven or knitted fabric formed from a bulky multifilament yarn has recently been required to be still more improved in delicate hand, touch, appearance. In order to meet the requirements, the properties of the sheath portion of the multifilament yarn forming the surface portion of the bulky yarn woven or knitted fabric must be improved.
Various investigations have therefore been carried out to effect modification of a filament-forming polymer so that the following can be realized: (1) further thinning each of the filaments forming the sheath portion; and (2) manifestation of a desired hand of filaments for forming the sheath portion. The following procedures have been known as means for the modification of a polymer mentioned above: a polyester polymer is made to contain a micropore-forming agent, or a polyester polymer is modified with a micropore-forming agent; a multifilament yarn is produced from the resultant micropore forming agent-containing or modified polyester; a desired woven or knitted fabric is produced from the multifilament yarn; and the multifilament yarn or the woven or knitted fabric is subjected to a weight-reduction treatment with an alkali to improve the hand of multifilaments. The alkali weight reduction forms many fine craters caused by the trace of the micropore-forming agent removed from the surface of the individual filament. As a result, the treated multifilament yarn, or woven or knitted fabric has improved dry touch, a draping property and a creaky (Kishimi) hand.
The modified polyester multifilament yarn or woven or knitted fabric thereof as explained above has been industrially highly evaluated as a fiber material having a special and new hand. However, when individual multifilaments for forming the sheath portion are required to be further thinned (e.g., 1.0 dtex or less), particularly when the multifilaments contain a micropore-forming agent, the process stability of the production of multifilaments having thin individual filament thickness from the modified polyester containing the agent decreases, and the production efficiency is lowered. Moreover, the efficiency of manifesting the effect of improving the hand with the micropore-forming agent decreases.
As a result of intensively investigating the causes of the above problems, the inventors of the present invention have found that the process stability decreases during the production of a bulky composite yarn containing, as a sheath portion, filaments that contain a micropore-forming agent and that the effect of improving the hand of the resultant composite yarn decreases for the reason that during melt spinning filaments for the sheath portion, the micropore-forming agent contained therein is thermally decomposed to deteriorate the polyester and/or form foreign particles by aggregation.
DISCLOSURE OF THE INVENTION
The present invention is intended to provide a bulky polyester multifilament composite yarn containing, as a filament component for forming the sheath portion, polyester filaments that contains a micropore-forming agent and having an excellent hand, and a process for producing the composite yarn with high productivity and process stability.
As a result of investigating means for preventing the deterioration of polyester during melt-spinning polyester multifilaments containing a micropore-forming agent and/or the formation of foreign particles caused by aggregation of the micropore-forming agent, the inventors of the present invention have discovered that the use of a micropore-forming agent in combination with a residual elongation-improver can solve the above problems and improve both the process stability of the production of the multifilament composite yarn and the hand of the resultant bulky composite yarn, and the present invention has been completed on the basis of the discovery.
The bulky polyester multifilament composite yarn of the present invention comprises two types of polyester filaments (FA) and (FB) differing from each other in average filament length,
the polyester filaments (FA) being formed from a polyester resin that contains from 0.1 to 9.0% by mass of a micropore-forming agent and from 0.5 to 5.0% by mass of a residual elongation-improver based on the mass of the polyester resin, and
the polyester filaments (FA) having an average filament length that is from 1.07 to 1.40 times the average filament length of the polyester filaments (FB).
For the bulky polyester multifilament composite yarn of the present invention, the polyester filaments (FA) preferably have a single filament size of 1.5 dtex or less.
For the bulky polyester multifilament composite yarn of the present invention, the micropore-forming agent preferably contains at least one compound selected from the group consisting of polyethers having a polyoxyalkylene group, metal organic sulfonates and metal-containing phosphorus compounds.
For the bulky polyester multifilament composite yarn of the present invention, the residual elongation improver preferably contains a polymer obtained by addition polymerization of an unsaturated monomer and having a molecular weight of 2,000 or more.
For the bulky polyester multifilament composite yarn of the present invention, the elongation improvement ratio I defined by the following formula (I) of the polyester filaments (FA) is preferably 50% or more:
I
(%)=[
EL
A
/(
EL
0
−1)]×100 (I)
wherein EL
A
is a single filament elongation of the undrawn filaments of the polyester filaments (FA), and EL
0
is a single filament elongation of undrawn polyester filaments produced from the same composition as that of the undrawn filaments of the polyester filaments (FA) under the same conditions as those under which the undrawn filaments of the polyester filaments (FA) have been produced except that the composition contains no residual elongation improver.
For the bulky polyester multifilament composite yarn of the present invention, the residual elongation improver preferably contains at least one polymer substance selected from the group consisting of polymers or copolymers of methyl methacrylate, isotactic polymers or copolymers of styrene compounds, syndiotactic polymers or copolymers of styrene compounds and polymers or copolymers of methylpentene compounds.
A process for producing a bulky polyester multifilament composite yarn of the present invention comprises: melt extruding a polyester composition (PA) containing a polyester resin, from 0.1 to 9
Iohara Koichi
Kasaoka Katsuyuki
Yoshimura Mie
Edwards N.
Teijin Limited
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