JPH04146209A - Production of polyester fiber from reclaimed resin - Google Patents

Abstract

PURPOSE:To obtain the subject fiber having excellent strength, elongation, bulkiness, uniformity and cost competitiveness and useful for carpet, etc., by melt-spinning pellets containing reclaimed pellets under specific condition. CONSTITUTION:The objective fiber is produced by melting pellets containing >=20wt.% of reclaimed pellets having an intrinsic viscosity of 0.38-0.63 and spinning the molten pellet through a spinneret having a spinning nozzle cross-section of 0.12-0.18mm<2> (preferably a circular cross-section nozzle having a nozzle diameter of 0.4-1.5mm and a diameter/length ratio of 0.5-4) at an extrusion speed of 0.5-15m/min and a productivity of 7.5-250g/cm<2>.min per unit area of the effective part of the spinneret.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to polyester fibers produced using polyethylene terephthalate resin recovered from molded articles as a raw material. It has suitable performance as needle punch carpet, stuffed cotton, and nonwoven fabric.

The present invention uses polyethylene terephthalate resin recovered from molded products, which has a relatively low molecular weight or intrinsic viscosity (hereinafter abbreviated as IV) and has spinning characteristics different from conventional fiber resins, as the main raw material, and has excellent strength and elongation. This method produces polyester fibers with a high degree of uniformity.

The polyester fiber produced by the method of the present invention can be crimped with excellent performance as a filament or staple, and is cost competitive because it is made from inexpensive polyethylene terephthalate resin recovered from molded products. It has excellent properties and can be used for a variety of purposes, including as a face yarn for carpets such as tufted carpets.

The polyester fiber produced by the method of the present invention can be heated to produce a dimensional difference sufficient to provide sufficient bulk as a filament, and can be processed using inexpensive polyethylene terephthalate resin recovered from molded products. Because it is used as a raw material, it is highly cost-competitive and can be used for a variety of purposes, including as the face yarn for carpets such as tufted carpets.

The polyester fiber produced by the method of the present invention is excellent in cost competitiveness because it is made from inexpensive polyethylene terephthalate resin recovered from molded products, and is suitable for use in stuffing and nonwoven fabrics, especially for futon cotton and needle punching. Can be used for carpets, carpet base fabrics, and filters.

(B) Conventional technology Polyester fibers have high strength and elongation, excellent durability such as light resistance and abrasion resistance, and good texture, so they can be used as various textile products of excellent quality. Since it has a higher specific gravity than other synthetic fibers such as nylon, acrylic, and polypropylene, or natural fibers such as wool, it has the disadvantage that its covering power is somewhat low. For this reason, it has traditionally been used as a blended product or a 100% product, mainly in the fields of cotton, linen, and rayon, which have high specific gravity.

In recent years, polyester fibers have been increasingly used in the field of silk, which has a similar specific gravity, in order to avoid the drawback of slightly lower covering power. However, due to the high price of silk in this field, price is no longer an important issue; rather, similarity in appearance and texture is desired. Furthermore, in this field, the unique texture of polyester is receiving high praise, and it appears that a market unique to polyester is being formed.

In order to solve the problem of high specific gravity and low covering power, it has traditionally been thought that increasing the amount of fiber used is a good idea. In order to enter a field where a specific market for polyester has not yet been formed, it is necessary that the price of polyester fiber be low.

Another way to solve this problem is to reduce the cost per volume of polyester fiber by making the cross-sectional shape of the fiber non-circular, making it hollow fiber, or expanding the space between fibers through advanced crimping. is being carried out. In addition, various methods are being used to reduce production costs, such as shortening processing steps.

In addition to rationalizing the manufacturing process, possible ways to reduce costs include labor saving and lowering the price of raw materials.

However, in the production of polyester fiber, high speeds and large packaging have already been advanced, so even if efforts are made to save labor, it will not be possible to achieve a significant cost reduction effect. Since the scale has become sufficiently large, it is considered difficult to further reduce it beyond the current level even if the scale is increased further. Furthermore, research on cost reduction through the adoption of new manufacturing processes has a long history, and it is currently difficult to find a direction for development.

In this current situation, one material that deserves attention is the resin recovered from the layers of molded products. With the recent development of polyethylene terephthalate (PET) film and PET bottles, this raw material has grown to the point where we can expect a large amount of resources.

However, there are many types of recovered resin, and there are large fluctuations in quality, and the problem is that it repeatedly melts and solidifies during the recycling process.
Many alterations that cause a decrease in fiber performance, such as a decrease in IV and an increase in carboxyl groups, occur.

A decrease in IV lowers the strength and elongation of the fibers, causing the problem that fibrillation of the fibers rapidly progresses during use, especially in applications that are subjected to strong friction such as carpets. The problem is that this fibrillation causes dirt to easily accumulate on the surface of the carpet, but it also causes the fibers to become lighter in color, resulting in a situation where the light fastness is apparently lowered.

Due to the decrease in Tv, the tensile strength, bursting strength, and fatigue resistance of woven and nonwoven fabrics used as industrial materials decrease, resulting in a decrease in competitiveness with other types of fibers. However, on the other hand, due to the decrease in IV, there are products such as knits that are less prone to pilling and have a longer lifespan in terms of appearance. In addition, there are many products such as futon cotton and stuffed cotton whose strength reduction has no effect on performance.

It has been said that polyesters with a small IV have poor spinnability compared to standard polyesters, and that the range of conditions under which they can be stably spun is narrow. In Japanese Patent Publication No. 47-2061, suitable conditions for spinning polyester with an IV of 0.33 to 0.50 are given as follows: cross-sectional area of the spinning hole ^ (12) per spinning hole, fishing output Q (CM'/min), IV Between [η] (1)
The range of formula (2)<3) is disclosed.

^・(-0,078[η]+0.(1751Q/(1,
45±0.0138 (1)＾≦0.06
(2) 0.46≦q≦2.67
(3) Although this technology seems suitable as a spinneret for low-viscosity resins immediately after polymerization,
In the case of recycled resin, it contains a large amount of a modifier that is not used for LLI maintenance, which is added to improve film-forming properties, and it has a high content of carboxyl terminals and a low content of impurities. Therefore, spinning conditions within this technical range are not suitable.

The advantage of using a spinning hole with such a small cross-sectional area is that the spun fibers have a good uniformity, and under special spinning conditions, the technology of using a spinning hole with a large cross-sectional area from the viewpoint of spinnability is possible. is also known. For example, Tokko Sho 47-1
No. 8046 discloses that 1.
A method of spinning through a spinhole having a cross-sectional area of 0 to 5.5 mm2 is disclosed.

This technique is certainly a preferable method for stably melt-spinning polyester with a small IV, but the wind speed is about 10 times that of cooling for normal melt-spinning.
4. It is characterized by cooling for 5-7 seconds, and under such special cooling conditions, a spinning hole with a large cross-sectional area is preferable. It is not possible to infer that the spinholes are preferred.

(c) Problems to be Solved by the Invention The use of recycled resin is an effective means for reducing the manufacturing cost of polyester fibers. However, due to repeated melting and solidification during the regeneration process, a significant change in the spinnability of the polyester resin is observed. In addition, various additives are mixed into the recycled resin to improve film-forming properties, and changes in spinnability are observed due to these additives. Therefore, recycled resin cannot necessarily be spun well under conditions conventionally considered suitable.

The purpose of the present invention is to solve the problem that such recycled resin has different spinability from ordinary polyester resin, and to obtain fibers of excellent quality.

(d) Means for Solving the Problems The present invention involves melting pellets containing at least 20% by weight of recycled pellets, so that the cross-sectional area of one spinning hole is 0.12 to 0.12%.
Melt spinning is carried out from a spinneret having a 1.81" spinning hole at a spinning solution discharge rate of 0.5 to 151 minutes and a production rate of 7.5 to 250 g/cm"/minute per effective area of the spinneret. This is a method for producing polyester fiber using recycled resin as a raw material.

If the cross-sectional area of the spinning hole is less than 0.12 11', the spun liquid yarn tends to flow while adhering to the surface of the nozzle, an abnormal spinning condition called so-called two-ink, which tends to occur on the surface of one nozzle. The cross-sectional area of the spinning hole is preferably 0.8 mm2 or more, which is undesirable because it requires frequent cleaning.If the diameter is more than 1.8 mm2, the unevenness of the fineness becomes very large and the generation of fuzz increases, which is undesirable. 25~1.2mm'
It is.

If the discharge speed of the spinning solution is less than 0.5 m/min, it is not preferable because the unevenness in fineness becomes large and the elapsed time until stabilization after exchanging the spinneret becomes very long.

In addition, if it is more than 15 threads/min, it is not preferable to clean the surface of the spinneret frequently, and the undrawn yarn often becomes loose in the form of loops, resulting in fluff.

The effective part of the spinneret is essentially the part where the spinning holes are present, and is the part where the spinning holes are connected by taking an average distance between the spinning holes around the outer periphery of the group of spinning holes. When a group of spinning holes exists in an annular shape, an average distance between the spinning holes is taken inside the inner periphery, and a portion that is not an effective portion is assumed to exist inside the average distance between the spinning holes. If the production amount per area of the effective part of the spinneret is less than 7.5 g/am2・min, the thermal stability of the recycled resin is poor, resulting in large thermal deterioration during the spinning process, and This is not preferable because the volumetric efficiency deteriorates and the cost increases, and if it exceeds 250 g/as'·min, it becomes difficult to perform sufficient cooling with air and fused fibers are generated, which is not preferable.

The recycled resin used as a raw material in the present invention is preferably IV
has 038 to 063. If the IV is less than 038, the strength and elongation of the obtained fiber will be too low, which is undesirable, and if the IV is 0.63 or more, if a spinning hole with a large cross-sectional area as in the present invention is used, The IV used in the present invention is measured at 30° C. using a mixture of equal weights of phenol and tetrachloroethane as a solvent when the spinning solution is discharged at a high speed because thread breakage increases.

In the present invention, the spinneret used to produce fibers with a circular cross section has a hole diameter of 0.4 to 1.5 mm as a spinning hole.
It is preferable to have a circular cross section with a diameter-to-length ratio (hole diameter/hole length) of 0.5 to 4. If the diameter-to-length ratio is less than 0.5, unevenness in fineness will increase and the frequency of cleaning the cap will increase. This is not preferable, and if the diameter/length ratio is 4 or more, the manufacturing cost of the spinneret increases, which is not preferable.

In the present invention, the polyester fiber made from recycled resin is preferably a continuous yarn having bulkiness. This continuous yarn exhibits excellent performance in a variety of applications, but is especially excellent as a carpet face yarn. This continuous yarn has the advantage of reducing the number of steps from spinning to tufting, and has recently been increasingly used in carpets under the name BCF.

In the present invention, polyester fibers made from recycled resin are preferably heated at 100 to 170°C to produce a dimensional difference of 5 to 25% between single fibers. This fiber can be made into a product with excellent bulk by processing it into a thread and then heat-treating it.

Especially when it is a continuous yarn, it is excellent as a face yarn for carpets.

Such a dimensional difference makes it possible to give BCF, which is a continuous yarn, an appearance similar to that of a spun yarn, giving it a high-quality appearance, and has the advantage of making dyeing unevenness that occurs in the yarn less noticeable.

In the present invention, the polyester fiber made from recycled resin is preferably a staple fiber. This fiber exhibits excellent performance as nonwoven fabrics, futons, and stuffed cotton.

The polyester fiber made from the recycled resin of the present invention preferably has 3 to 15 crimps per 25 mm. This fiber exhibits excellent performance as carpet face yarn, futon cotton, and padding.

Having a crimp number in this range is particularly preferred in the case of BCF, which is a continuous fiber, when the polyester filament has a crimp number of less than 3 per 25 when used as BCF for the face yarn of a carpet. is unfavorable because the covering characteristics are poor due to the low volume of the livestock stalls, and the thread layer tends to collapse, +1! If the number of contractions is 15 or more per 25 mm, the yarn layer becomes soft, which makes the rug weak, and the mats are easily crushed due to entanglement, and the durability is low, which is undesirable.

The polyester fiber made from the recycled resin of the present invention preferably contains one selected from the group of antioxidants and ultraviolet absorbers.
It contains 0.01 to 2% of one or more additives.

If the amount added is less than 0.01%, there is a problem with the persistence of the effect of the additive, and if it is more than 2%, coloration due to contact between the resin and the additive becomes noticeable during melt spinning, which is not preferable. .

Polyethylene terephthalate resin for molding often contains large amounts of components that are not contained in polyester fibers in order to improve moldability, and it is difficult to remove these components from recycled pellets. Therefore,
It is preferable to prevent the deterioration of performance due to this component by adding an antioxidant or an ultraviolet absorber.

Examples of specific additives include tocopherol, 3゜5-dibutylhydroxytoluene, 2
, 4.6-) so-1-butylphenol or 3.5
-Hindered phenol-type compounds such as di-t-butyl-4-hydroxybenzyl phosphate diethyl ester, phosphite-based compounds such as triphenylphosphite, and phosphate-based compounds such as trimethyl phosphophosphate are used. can.

However, aromatic amines, which are effective in preventing oxidation of rubber, cannot be used because they react with polyester and produce colored substances.

As the ultraviolet absorber, those having an absorbing wavelength of 280 to 310 mm can be used. Among these, triplet quenchers such as benzophenone or benzotriazole are preferred.

Many of these additives have functional groups such as phenolic hydroxyl groups, alcoholic hydroxyl groups, carboxyl groups, and amino groups, but the additives used in the present invention are added by kneading them during melt spinning. In such cases, it is preferable to use one that does not have such a functional group, or one whose reaction with polyester is inhibited by steric hindrance, or one that does not lose its function even after reaction with polyester.

Instead of adding these additives by kneading them into the resin during melt spinning, they may be infiltrated into the fibers by a treatment method such as a dyeing process after fiber formation.

(E) The behavior of the spinning solution when spinning recycled polyester fibers is different from that of regular polyester fibers, and the problem of easy discharge diagonally, contaminating the spinneret and reducing mold release properties can be solved by increasing the cross-sectional area of the spinning hole. The solution is to do so.

A spinning hole with a large cross-sectional area has the advantage that the liquid yarn is hard to bend during spinning, and since the spinning tension per spinning hole is high, there is an advantage that there is less yarn breakage.

(f) Examples Next, the present invention will be explained in detail and concretely using examples.

Example 1 30 parts of PET pellets recovered from film molding waste with 1V=0.54 and carboxyl end group content 55 microequivalents/g, IV=0.52 and carboxyl end group content 72 microequivalents/g 50 parts of pellets recovered from bottle waste of
After mixing and drying, the mixture was melted using a screw extruder.

The resulting fiber had an IV of 0.55 and a carboxyl end group content of 57 microequivalents/g. The melt after melt extrusion was melt-spun through a spinning hole with a hole diameter of 0.8 mm and a major axis of 1.5 at a discharge speed of 10.7 s/min, and after being wound at a winding speed of 827 m/min, stretching and crimping were performed. A BCF of 3960 denier/272 filament was obtained. The production amount per area of the effective part of the spinneret during this spinning is 31.57
It was e-2.min.

This fiber has sufficient strength and elongation as carpet yarn, and is comparable to ordinary P in terms of hue, white charcoal, dyeability, and level dyeability.
It is comparable to ET fiber, and the color fastness is also the same for many dyes, and for some dyes it is 0.
．． It was grade 5 to grade 1 lower. This value is generally considered satisfactory for normal rug applications.

Example 2 Using the same mixed pellets as in Example 1, the pellets were melt-extruded and then spun using spinnerets with various specifications to evaluate spinnability and products as BCF. The results are shown in Table 1.

Table 1 Spinneret, spinnability and product performance Example 3 50 parts of PET pellets recovered from film molding waste with IV = 0.54 and carboxyl end group content of 39 microequivalents/g, IV = 0.52 , P recovered from bottle waste with a carboxyl end group content of 61 microequivalents/g
After drying a mixture of 50 parts of ET pellets, it was melt-extruded, spun using a spinneret with a moderately shaped cross-section, and stretched and crimped to 3600 denier/28
A BCF of 0 filaments was obtained.

The product was evaluated for spinnability and BCF.

The results are shown in Table 2.

Table 2 Comparative example of spinneret, spinnability, and product performance After drying under the following drying conditions, it was melt-extruded, melt-spun by a conventional method, and stretched and crimped to obtain a BCF of 3900 denier/272 filament.

When a spinneret with a spinning hole of 0.23@IIφ, which is used for spinning conventional low-viscosity polyester, was used, the yarn breakage rate during spinning was 82 times.

This thread breakage rate is considered to be so high that practical production is impossible.

Example 4 To the same recovered pellet mixture as in Example 1, a hindered phenol type antioxidant, tetrakis methylene-
3 (3°, 5°-di-t-butyl-4°-hydroxyphenyl)propionate methane] 0.05%, ultraviolet absorber, o, o'-dioxybenzophenone 0.07%
%, dried under the same conditions as in Example 1, melt-extruded and spun to obtain a 3600 denier 7280 filament BCF by a conventional method.

The IV of the obtained fiber was 0.55. The light fastness of dyed products of this fiber was about 1 grade better than that of dyes without antioxidants and ultraviolet absorbers for many dyes, and the heat aging resistance was also good. .

(G) Effects of the Invention The present invention relates to polyester fibers produced using polyethylene terephthalate resin recovered from molded products as a raw material.The polyester fibers produced by the method of the present invention can be used particularly as carpet face yarns, needle punch carpets, stuffed cotton, and nonwoven fabrics. Has suitable performance.

The present invention uses polyethylene terephthalate resin, which is recovered from molded products and has a relatively low molecular weight or intrinsic viscosity and has different spinning properties from conventional fiber resins, as the main raw material, and is a polyester resin that has excellent strength and elongation, and has a high degree of uniformity. This is a method for producing fibers.

The polyester fiber produced by the method of the present invention can be crimped with excellent performance as a filament or stable, and is cost competitive because it is made from inexpensive polyethylene terephthalate resin recovered from molded products. It has excellent properties and can be used for a variety of purposes, including as a face yarn for carpets such as tufted carpets.

The polyester fiber produced by the method of the present invention can be heated to produce a dimensional difference sufficient to provide sufficient bulk as a filament, and can be processed using inexpensive polyethylene terephthalate resin recovered from molded products. Because it is used as a raw material, it is highly cost-competitive and can be used for a variety of purposes, including as the face yarn for carpets such as tufted carpets.

The polyester fiber produced by the method of the present invention is excellent in cost competitiveness because it is made from inexpensive polyethylene terephthalate resin recovered from molded products, and is suitable for use in padding and nonwoven fabrics, especially for futon cotton and needle punch carpets. Can be used for carpet base fabrics, filters.

that's all Applicant: Shinka Takumi Co., Ltd.

Claims (8)

[Claims] (1) Melt pellets containing at least 20% by weight of recycled pellets, and create a spinning hole with a cross-sectional area of 0.12 to 1.8 mm^
2. Melt spinning is performed from a spinneret having spinning holes at a spinning solution discharge rate of 0.5 to 15 m/min and a production amount of 7.5 to 250 g/cm^2 min per effective area of the spinneret. A method for producing polyester fiber using recycled resin as a raw material. (2) The recycled resin according to claim 1 has an intrinsic viscosity of 0.38 to 0.
．． 63. A method for producing polyester fiber using recycled resin as a raw material, characterized in that it has a polyester fiber having a polyester fiber of 63. (3) The spinning hole according to claims 1 or 2 has a spinning hole diameter of 0.4.
A method for producing polyester fiber using recycled resin as a raw material, characterized in that the fiber has a circular cross section of ~1.5 mm and a length-to-diameter ratio of 0.5 to 4. (4) A method for producing polyester fibers using recycled resin as a raw material, characterized in that the polyester fibers according to claims 1 to 3 are continuous yarns having bulkiness. (5) The polyester fiber according to claims 1 to 4 contains 10
A method for producing polyester fibers using recycled resin as a raw material, characterized in that heating at 0 to 170°C produces a dimensional difference of 5 to 25% between single fibers. (6) A method for producing polyester fibers using recycled resin as a raw material, characterized in that the polyester fibers according to claims 1 to 3 are staple fibers. (7) The polyester fiber according to claims 1 to 6 contains 25
A method for producing polyester fiber using recycled resin as a raw material, characterized by having 3 to 15 crimps per mm. (8) A recycled resin characterized in that the polyester according to claims 1 to 7 contains 0.01 to 2% of one or more additives selected from the group of antioxidants and ultraviolet absorbers. A method for producing polyester fiber using raw material.