Polytrimethylene terephthalate composition, polyester fiber, and methods for producing the same
A polytrimethylene terephthalate composition including a polyester having a trimethylene terephthalate unit as a main repeating unit, which satisfies all the following requirements: (a) the intrinsic viscosity is 0.50 to 1.60 dL/g; (b) titanium dioxide whose weight distribution of particles having a particle size of more than 1.0 μm is 5.0% by weight or less is contained in an amount of 0.05 to 3.0% by weight; (c) the crystallization exothermic peak top temperature is 165° C. or more; and (d) the half-width of the crystallization exothermic peak is 20° C. or less. In addition, the invention further encompasses a method for producing a polytrimethylene terephthalate composition using titanium dioxide that has been subjected to a wet-grinding treatment, and also a fiber obtained from the composition. The invention provides a polytrimethylene terephthalate composition, which stabilizes the process in the production of a fiber having small single-fiber fineness by melt-spinning, and is suitable for obtaining a fiber with reduced fluffing.
1. A polytrimethylene terephthalate composition comprising a polyester having a trimethylene terephthalate unit as a main repeating unit,
the polytrimethylene terephthalate composition satisfying all the following requirements (a) to (e):
(a) the intrinsic viscosity is within a range of 0.50 to 1.60 dL/g;
(b) titanium dioxide whose weight distribution of particles having a particle size of more than 1.0 μm in particle size distribution measurement using a laser diffraction/scattering particle size distribution analyzer is 5.0% by weight or less is contained in an amount of 0.05 to 3.0% by weight;
(c) the crystallization exothermic peak top temperature that appears when the polytrimethylene terephthalate composition heated to the melting point or higher is cooled at a rate of 10° C./min using a differential scanning calorimeter is 165° C. or more;
(d) the half-width of the crystallization exothermic peak that appears when the polytrimethylene terephthalate composition heated to the melting point or higher is cooled at a rate of 10° C./min using a differential scanning calorimeter is 20° C. or less; and
(e) the titanium dioxide is in anatase form.
2. The polytrimethylene terephthalate composition according to claim 1 , having an elemental phosphorus content of 3 to 100 ppm by weight.
3. A polyester fiber comprising the polytrimethylene terephthalate composition according to claim 1 .
4. A polyester composite fiber comprising the polytrimethylene terephthalate composition according to claim 1 as at least one component.
5. A method for producing a polytrimethylene terephthalate composition, characterized in that
titanium dioxide is subjected to a wet-grinding treatment to form a titanium dioxide slurry whose weight content of titanium dioxide particles having a particle size of more than 1.0 μm is 5.0% by weight or less, wherein the titanium dioxide is in anatase form, and
then the titanium dioxide slurry is added to a polytrimethylene terephthalate composition having a trimethylene terephthalate unit as a main repeating unit, thereby making the titanium dioxide concentration in the composition 0.05 to 3.0% by weight, and the intrinsic viscosity of the polytrimethylene terephthalate composition after polymerization within a range of 0.50 to 1.60 dL/g,
wherein when a differential scanning calorimeter is used, the crystallization exothermic peak top temperature that appears when the polytrimethylene terephthalate composition heated to the melting point or higher is cooled is controlled at 165° C. or more, while the half-width of the crystallization exothermic peak is controlled at 20° C. or less.
6. The method for producing a polytrimethylene terephthalate composition according to claim 5 , wherein an organic titanium compound is used as a polymerization catalyst.
7. The method for producing a polytrimethylene terephthalate composition according to claim 5 , wherein the titanium dioxide has an average particle size within a range of 0.1 to 0.8 μm before the wet-grinding treatment.
8. The method for producing a polytrimethylene terephthalate composition according to claim 5 , wherein the titanium dioxide slurry is obtainable by dispersing a powder of titanium dioxide in trimethylene glycol.
9. The method for producing a polytrimethylene terephthalate composition according to claim 5 , wherein the polytrimethylene terephthalate composition is a polytrimethylene terephthalate composition comprising a polyester having a trimethylene terephthalate unit as a main repeating unit,
the polytrimethylene terephthalate composition satisfying all the following requirements (a) to (d):
(a) the intrinsic viscosity is within a range of 0.50 to 1.60 dL/g;
(b) titanium dioxide whose weight distribution of particles having a particle size of more than 1.0 μm in particle size distribution measurement using a laser diffraction/scattering particle size distribution analyzer is 5.0% by weight or less is contained in an amount of 0.05 to 3.0% by weight;
(c) the crystallization exothermic peak top temperature that appears when the polytrimethylene terephthalate composition heated to the melting point or higher is cooled at a rate of 10° C./min using a differential scanning calorimeter is 165° C. or more; and
(d) the half-width of the crystallization exothermic peak that appears when the polytrimethylene terephthalate composition heated to the melting point or higher is cooled at a rate of 10° C./min using a differential scanning calorimeter is 20° C. or less.
10. A method for producing a polyester fiber, characterized by comprising melt-spinning the polytrimethylene terephthalate composition according to claim 1 .
11. A polyester fiber comprising the polytrimethylene terephthalate composition according to claim 2 .
12. A polyester composite fiber comprising the polytrimethylene terephthalate composition according to claim 2 as at least one component.
13. The method for producing a polytrimethylene terephthalate composition according to claim 6 , wherein the titanium dioxide has an average particle size within a range of 0.1 to 0.8 μm before the wet-grinding treatment.
14. A method for producing a polyester fiber, characterized by comprising melt-spinning the polytrimethylene terephthalate composition according to claim 2 .