JP2005264418A - Flame-retardant reclaimed polyester fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flame-retardant reclaimed polyester fiber having a strength sufficiently usable as a polyester fiber for industrial material even by using a recycled polyester and exhibiting excellent flame-retardance. <P>SOLUTION: The flame-retardant reclaimed polyester fiber is composed of a polyester resin containing a recycled polyester and has an intrinsic viscosity [η] of ≥0.75, a strength of ≥5.5 cN/dtex and a phosphorus atom content of 1,000-10,000 ppm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flame-retardant recycled polyester fiber having a high strength and flame retardancy that is a fiber made of a polyester resin containing recycled polyester recovered after use, and can be sufficiently used for industrial materials. is there.

  In recent years, environmental pollution due to waste reclamation and incineration has been seen as a problem. Especially, disposable bottles have become increasingly problematic every year, and it is important to recycle resources as resources. Has been.

  The movement to collect and reuse used PET bottles and PET resin waste generated during the production of PET bottles is increasing year by year, and one of its uses is being reused as a raw material for fibers. Such polyester fibers are attracting attention as environmentally friendly fibers.

  Among these, PET resin waste derived from a PET bottle mainly composed of polyethylene terephthalate (hereinafter referred to as PET) is suitable for fiberization because it has few impurities and relatively little variation in viscosity.

  However, the viscosity of PET regenerated from PET resin waste derived from such PET bottles is usually about 0.5 to 0.75, the intrinsic viscosity [η], which is sufficient for use as a textile fiber. Although it is a level, in order to make the fiber for industrial materials in which high strength is required, the viscosity is low, and it is difficult to obtain the fiber for industrial materials having high strength from such PET resin waste.

  Therefore, as a result of studying to solve such problems, the present inventors have increased the intrinsic viscosity of PET regenerated from PET resin waste derived from PET bottles as described in Patent Document 1. It has become possible to obtain recycled polyester fibers that are high in strength and suitable for industrial materials.

  On the other hand, with regard to safety nets and mesh sheets used for civil engineering and construction work among industrial materials, conventionally, flame retardants are applied by post-processing to fabrics woven and woven using polyester fibers and recycled polyester fibers. It has been common to impart flame retardancy by performing flame retardant processing or resin processing such as vinyl chloride.

  However, post-processing flame retardant processing is inferior in sustainability of the flame retardant performance due to use, and in recent years, there has been a concern about the impact of vinyl chloride on the environment. As a result, flame retardant fibers in which flame retardancy is imparted to the fibers themselves have been proposed.

Patent Documents 2 and 3 also describe a recycled polyester fiber using a recycled polyester recovered after use and containing a flame retardant in the fiber. These fibers are superior in flame retardancy compared to post-processed ones, but only have strength suitable for clothing applications, and have high strength enough to be used for industrial material applications It wasn't.
JP 2002-235243 A JP 2002-54026 A JP 2004-27393 A

  The present invention solves the above-mentioned problems, has a strength that can be sufficiently used as a polyester fiber for industrial use, and is excellent in flame retardancy and weather resistance, while using recycled polyester. Providing polyester fiber is a technical problem.

  The inventors of the present invention have arrived at the present invention as a result of studies to solve the above problems.

  That is, the present invention is a polyester fiber made of a polyester resin containing a recycled polyester, having an intrinsic viscosity [η] of 0.75 or more, a strength of 5.5 cN / dtex or more, and a phosphorus atom content of 1000 to The subject matter of the present invention is a flame retardant recycled polyester fiber characterized by being 10,000 ppm.

  The flame-retarded recycled polyester fiber of the present invention has sufficient strength and flame retardancy suitable for industrial material use, while using recycled polyester, and can be used for various uses. Furthermore, the flame-retarded recycled polyester fiber of the present invention can be made excellent in weather resistance by setting the phosphorus atom content to 2000 to 5000 ppm.

Hereinafter, the present invention will be described in detail.
The recycled polyester fiber of the present invention is a recycled polyester fiber that is used once and then used as a raw material. Recycled polyester fiber is in a form other than pellets such as PET bottles, films, and fibers for liquid food and drink. After molding, it refers to the resin recovered for molding again without returning to low molecules. Of these, those obtained by collecting PET bottles are preferred because of their relatively good quality.

  In the present invention, such a recycled polyester is contained in the polyester resin, but the recycled polyester is preferably mixed in the polyester resin. And when using the thing derived from a PET bottle as recycled polyester, it is preferable to use normal polyester resin (virgin polyester) which has a polyethylene terephthalate as a main component as a polyester resin.

  And, the fiber of the present invention is made of a recycled polyester-containing polyester resin as described above, but the fiber contains a phosphorus compound, and the phosphorus atom content in the fiber is 1000 to 10,000 ppm. Of these, 2000 to 7000 ppm is preferable. When the phosphorus atom content is less than this range, the flame retardancy is inferior. On the other hand, if the amount is too large, the decrease in the viscosity of the polymer increases, making it difficult to obtain high-strength fibers, which is disadvantageous in terms of cost.

  Furthermore, in consideration of weather resistance, the content of phosphorus atoms in the fiber is preferably 2000 to 5000 ppm. In other words, the higher the phosphorus atom content in the fiber, the better the flame retardancy, but it tends to be inferior in weather resistance, so to make a fiber having both flame retardancy and weather resistance performance, The content is preferably within the above range.

  And the weather resistance performance in the present invention is evaluated by the strength retention after the weather resistance test, the phosphorus atom content in the fiber is 2000 to 5000 ppm, and the strength retention is 60% or more, especially 60 to 75%. Preferably there is. In addition, the strength retention after the weather resistance test is to create a stringed sample, and as a weather resistance test, irradiate for 250 hours using a sunshine carbon arc weather meter, measure the strength before and after irradiation, the following formula It is calculated.

Strength retention after weathering test (%) = [Strength before irradiation (N) / Strength after irradiation (N)] × 100
At this time, as the string-made sample, eight fibers (multifilaments) of the present invention are made into eight-beat square-shaped strings, and five of them are produced. The Sunshine Carbon Arc Weather Meter uses a WS type light source, the black panel temperature is 63 ± 3 ° C., and the spray cycle is 12 minutes in 60 minutes. And the strong retention after a weathering test of five string-making samples is calculated, and it is set as the average value.

  In addition, when the phosphorus compound is contained in the fiber, a master chip containing a high concentration of the phosphorus compound in the virgin polyester as described above is prepared, and this master chip and the recycled polyester are metered and mixed at the time of spinning. It is preferable to perform dry blending and melt spinning so as to achieve a target phosphorus concentration using a machine or the like.

  As a specific example of the phosphorus compound to be contained in the fiber of the present invention, a fire retardant “Fire Tard” manufactured by Sanyo Kasei Co., Ltd. is preferable because it is excellent in flame retardancy, heat resistance, and yarn production.

  In addition, in the fiber of the present invention, a copolymer, a matting agent, a heat-resistant agent, a weathering agent, etc. are added as a third component in the polyester resin as long as the effects such as yarn-making property and flame retardancy are not impaired. May be.

  Furthermore, the recycled polyester fiber of the present invention preferably uses recycled polyester in 50% by mass or more of the fiber mass for the purpose of making the fiber friendly to the environment, among which 70% by mass or more, and more preferably 80% by mass or more. It is preferable to use.

  Furthermore, in the fiber of the present invention, in order to obtain a high-strength fiber suitable for industrial material applications, the intrinsic viscosity [η] of the fiber is set to 0.75 or more, preferably 0.8 to 1.0. . When the intrinsic viscosity [η] is less than 0.75, it is difficult to obtain a target high-strength fiber. On the other hand, when it exceeds 1.0, it tends to be disadvantageous in terms of cost as well as being inferior in yarn production.

  Generally, the intrinsic viscosity [η] is about 0.6 to 0.7 in recycled polyester that is obtained by simply melting PET resin waste derived from PET bottles with a melt extruder or the like and regenerating them into chips. In addition, when a flame retardant is added to the polymer, the viscosity of the polymer is lowered. Therefore, in order to set the intrinsic viscosity [η] of the fiber to 0.75 or more, the intrinsic viscosity [η] of the recycled polyester is 0.8 or more. It is preferable to set it as 0.9-1.2.

  In order to set the intrinsic viscosity of the recycled polyester to such a high viscosity, the intrinsic viscosity can be increased by subjecting the recovered resin waste to a chip once melted to form a chip.

  And, by adjusting the polymerization time during such solid phase polymerization, if the terminal carboxyl group concentration of the polyester is 30 eq / ton or less, the heat and humidity resistance is improved, and it can be suitably used for rubber materials and the like. preferable.

  Next, the strength of the fiber of the present invention is 5.5 cN / dtex or more, more preferably 6.5 cN / dtex or more, and still more preferably 7.0 cN / dtex or more. If the strength is less than 5.5 cN / dtex, it is difficult to use it for industrial materials. On the other hand, the upper limit of the strength is not particularly limited, but since it contains a phosphorus compound, the phosphorus compound becomes a foreign substance in a normal manufacturing method, and there is a tendency that fluff is generated during stretching or the operability is deteriorated. Therefore, considering the operability and the physical property value of the obtained fiber, it is preferable to be 9.0 cN / dtex or less.

  Moreover, in order to make the flame-retardant recycled polyester fiber of the present invention suitable for industrial materials, the single yarn fineness is preferably 3 to 20 dtex, and the cross-sectional shape of the single yarn is round, Any of a polygonal shape such as a square or a triangle, a multileaf shape, or the like may be used, and a hollow portion may be used in these shapes.

  And when manufacturing the flame retardant recycled polyester fiber of the present invention, for example, as described above, after making a polyester resin in which a recycled polyester having a high viscosity and a virgin polyester containing a phosphorus compound are mixed, Spinning can be performed using a melt spinning apparatus. After spinning, a two-step method in which the spun yarn is once wound and stretched may be used, but it is preferable from the viewpoint of cost to adopt a spin draw method in which stretching and heat treatment are continuously performed without winding once. Especially, when employ | adopting a spin draw method, it is preferable to set it as the winding speed of 2000-4000 m / min, and the total draw ratio of 4-6.

Next, the present invention will be specifically described with reference to examples. In addition, each physical-property value and evaluation in an Example were measured with the following method.
(A) An equimolar mixture of intrinsic viscosity phenol and ethane tetrachloride was used as a solvent, and measurement was performed at a concentration of 0.5 g / dl and a temperature of 20 ° C.
(B) High elongation In accordance with JIS L-1013, measurement was performed using an autograph DSS-500 manufactured by Shimadzu Corporation at a sample length of 25 cm and a pulling speed of 30 cm / min.
(C) Flame retardancy Measured according to JIS L-1091D method (flame contact test). In addition, it shows that a flame retardance is so high that the numerical value of a flame contact number is large.
(D) Weather resistance Eight pieces of the obtained fibers (multifilament) were made into eight-punch squared cords, a weather resistance test was performed by the above-described method, and the strength retention after the weather test was calculated.

Example 1
Frozen PET resin waste derived from PET bottles with an intrinsic viscosity [η] of 0.62 was melted and chipped into a recycled polyester for 25 hours with stirring at a reduced pressure of 230 ° C. for 25 hours. The polymerization degree was increased to 1.1.
Using “Firetard” manufactured by Sanyo Kasei Co., Ltd. as a flame retardant, it was added to PET (virgin polyester) with an intrinsic viscosity [η] of 0.70 so that the phosphorus atom content was 60000 ppm to obtain a master chip. .
These recycled polyesters and master chips are dry blended using a metering mixer so that the mass ratio (recycled polyester / master chips) = 19/1, and the phosphorus atom content in the fiber is 3000 ppm. Then, it was supplied to a melt extruder.
A spinneret having a hole diameter of 0.6 mm and a number of holes of 192 is mounted on a conventional melt spinning apparatus, spinning at a temperature of 290 ° C., heating at a temperature of 400 ° C. and a length of 40 cm provided just below the spinneret. After passing through the cylinder, it was cooled by blowing a cooling air having a temperature of 15 ° C. and a speed of 0.7 m / sec with a horizontal cooling device having a length of 180 cm, and an oil was applied with an oiling roller. Subsequently, the unheated first roller is pulled four times, and the non-heated second roller is pulled five times to perform 1.01 time alignment, and then the temperature is 430 ° C. using a steam processor. While blowing steam at a pressure of 0.5 MPa, the film was stretched 5.6 times by being applied 6 times to a third roller having a temperature of 210 ° C. Next, 4% relaxation heat treatment is performed 6 times on a fourth roller (speed 2525 m / min) at a temperature of 150 ° C., wound on a winder at a speed of 2500 m / min, and fire-resistant with a round cross section of 1110 dtex / 192 filament. Regenerated polyester fiber was obtained.

Examples 2-5, Comparative Examples 1-2, 5
The same procedure as in Example 1 was performed except that the mass ratio of the recycled polyester and the master chip was changed as shown in Table 1 and dry blended so that the phosphorus atom content in the polymer became the value shown in Table 1. It was.

Comparative Example 3
The same procedure as in Example 1 was carried out except that the solid phase polymerization time of the recycled polyester was changed and only the solid phase polymerization was performed so that the intrinsic viscosity [η] was 0.8.

Comparative Example 4
It was carried out in the same manner as in Example 1 except that flaky PET resin waste derived from a PET bottle having an intrinsic viscosity [η] of 0.62 was melted and the recycled polyester obtained as a chip was used without performing solid phase polymerization.

  Table 1 shows the characteristic values of the fibers obtained in Examples 1 to 5 and Comparative Examples 1 to 5, and the evaluation results of flame retardancy and weather resistance.

As is clear from Table 1, the fibers of Examples 1 to 5 had a high intrinsic viscosity, had sufficient strength and cut elongation, and were excellent in flame retardancy. Among them, the fibers of Examples 1 and 3 to 5 were excellent in weather resistance because the phosphorus atom content was 1000 to 5000 ppm.
On the other hand, since the fiber of the comparative example 1 had too little phosphorus atom content, the fiber of the comparative example 5 did not contain the phosphorus atom, so both fibers were inferior in flame retardancy. Since the fiber of Comparative Example 2 contained too much phosphorus atom, the viscosity of the polymer was lowered, the intrinsic viscosity was low, and the fiber was low in strength. In Comparative Examples 3 and 4, since the intrinsic viscosity of the recycled polyester was low, the intrinsic viscosity of the obtained fiber was low and the strength was low, which was not suitable for industrial material use.

Claims (3)

A polyester fiber comprising a polyester resin containing recycled polyester, characterized in that the intrinsic viscosity [η] is 0.75 or more, the strength is 5.5 cN / dtex or more, and the phosphorus atom content is 1000 to 10,000 ppm. Flame retardant recycled polyester fiber. The flame-retardant recycled polyester fiber according to claim 1, wherein the content of the recycled polyester in the fiber is 50 mass% or more of the fiber mass. The flame-retardant recycled polyester fiber according to claim 1 or 2, wherein the phosphorus atom content is 2000 to 5000 ppm, and the strength retention after the weather resistance test is 60% or more.
The strength retention after the weathering test is calculated from the following formula by preparing a string sample, measuring the strength before and after irradiation for 250 hours using a sunshine carbon arc weather meter. .
Strength retention after weathering test (%) = [Strength before irradiation (N) / Strength after irradiation (N)] × 100