JP2003049323A - Reclaimed polyester-based flat yarn and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reclaimed PET-based flat yarn having a high performance at a low cost by directly forming reclaimed PET flakes having a high IV as a main material into a film, while saving a palletizing process and simultaneously preventing the lowering of IV. SOLUTION: This method for producing the reclaimed PET-based flat yarn comprises directly forming >=50 wt.% of the reclaimed PET flakes having an intrinsic viscosity (IV) of >=0.68 and, if necessary, one or more additives, into a film, slitting and simultaneously thermally drawing the slit films, while maintaining the IV value of the slit films to >=0.62. Thereby, the reclaimed PET-based flat yarn having excellent mechanical properties and excellent durability can easily be obtained at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a flakes made of recycled polyethylene terephthalate (hereinafter abbreviated as recycled PET) to produce a recycled polyester flat yarn having high IV and excellent mechanical performance and durability at low cost and stable. Is what you are trying to get.

[0002]

2. Description of the Related Art At present, PET resins are widely used in the fields of bottles, films and fibers due to their excellent properties. Among them, bottles are used for beverages and foods, and the amount thereof is increasing year by year, and it is actively used to collect used PET bottles and reuse them such as films, fibers and molded products. On the other hand, the general waste of PET bottles is not only discharged in various states of fouling, but also the molecular weight of the main component PET, copolymerization components, additives, etc. differ from bottle to bottle. Therefore, even if an attempt was made to reuse a waste bottle, it was not easy to realize it because the variation in the physical properties of the molded product and the occurrence rate of defective products were very large.

As described above, development of effective utilization of waste PET has been desired, and various proposals have been made. A large-sized injection-molded article (specially made of recycled PET bottle (JP-A-6-255645) and recycled PET composition) Kaihei 8-59967), a foamed sheet made of recycled PET and a tray-shaped container for packaging articles or a partition plate (Japanese Patent Laid-Open No. 11-106545), a nonwoven fabric produced from recycled PET (discarded in December 1999) Article newspaper) etc. are disclosed.

A flat yarn is disclosed in Japanese Patent Laid-Open No. Sho 62-62.
No. 184135, a polyester fibril yarn which is difficult to fibrillate, and a method for producing a polyester stretched tape yarn for obtaining the properties of low heat shrinkage and longitudinal tear resistance of JP-A-2-61122, and further JP-A-2-1874.
PE described in Japanese Patent Laid-Open No. 50-39 and Japanese Patent Laid-Open No. 2-139410
Stretched tapes and the like formed from a composition in which a small amount of polypropylene resin is mixed with T resin have been reported.
The base material for flexible containers is mentioned in many of the application examples of T flat yarn.

On the other hand, recycled PET bottles are recycled P
When used as an ET resin, generally, a bottle is crushed, washed and dried to form flakes, and then melt-kneaded and filtered by an extruder to pelletize. Next, a method is used in which the obtained pellets are subjected to a heat treatment for crystallization and water removal, and then melted and molded by an extruder again. However, in this method, since a thermal history of several degrees is added, a large IV drop occurs due to hydrolysis and the like, and the IV value is usually 0.55 to 0.65. PE of this IV value
When a flat yarn is manufactured from T pellets, the IV value is reduced to 0.6 or less, resulting in lack of stability in the film forming process and a large number of stretch breaks, and it is difficult to obtain sufficient strength as a yarn. There was a problem.

[0006]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention
Mainly made of recycled PET flakes obtained by crushing, washing and drying bottles, the film is directly formed without pelletizing by melt extrusion, and a high IV and high performance flat yarn is manufactured at low cost. Is.

[0007]

When the flakes are produced from the recovered PET bottle, the IV value is usually maintained at 0.68 or more, but when pelletized by melt extrusion, the IV value becomes 0.65 or less. When forming a film with 0.6
It drops to below. The inventors of the present invention have conducted intensive studies focusing on the point of suppressing the IV drop as much as possible, and as a result, found a method of directly forming a film mainly with recycled flakes, and obtaining a flat yarn having an IV value of 0.62 or more. It came to. That is, the film of the present invention is provided with measures such as dryness enhancement of the flakes by a suction method and improvement of bite of the flakes by optimizing the shape of the extrusion screw, further cleaning enhancement of the flakes and removal of foreign substances by filter enhancement by an extrusion screen changer. The direct film forming method from was completed.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester referred to in the present invention is
Mainly composed of ethylene terephthalate units, part of the terephthalic acid in the dicarboxylic acid component may be mixed with isophthalic acid, adipic acid, 2,6-naphthalenedicarboxylic acid, etc. Is diethylene glycol, propylene glycol, 1,4-butanediol,
It also includes a mixture of 1,4-cyclohexanemethanol and the like. Recycled PET resin is a molded product made from this PET resin that is made to be used again as the raw material resin. It is not particularly limited as long as it is a molded product mainly made of PET resin as long as it does not exceed the gist of the present invention, but it is preferably made of bottle, film, fiber, etc. Those from waste are preferred.

In the present invention, the IV value obtained from a used PET resin product is 0. 0 for the purpose of effectively utilizing resources.
A flat yarn is produced by using 50% by weight or more of 68 or more recycled PET flakes. IV value is 0.6
If it is less than 8, it is difficult to obtain a flat yarn of 0.62 or more,
On the other hand, if it is less than 50% by weight, it is not possible to obtain the eco-friendly eco mark of the flat yarn, and the IV is lowered to make it difficult to obtain a high performance flat yarn excellent in strength and durability. It is desirable to use 70% by weight or more of recycled flakes having an IV value of 0.7 or more.

As a method for producing the recycled flakes, generally, the PET resin products collected and sorted are crushed into flakes having a diameter of about 5 to 20 mm by a crushing device such as a uniaxial shredder equipped with a rotary blade or a rotary cutter. Next, using a specific gravity sorting device such as a water storage tank and a stirring tank, different materials such as labels are separated and only flakes are sorted,
Cleaning and dewatering are performed by rotary cleaning, ultrasonic cleaning, etc., and hot air drying is performed using a blower or the like. Further, in the present invention, since the film is directly formed from the flakes, the moisture in the flakes is sufficiently removed by suction drying or the like as a measure against IV reduction due to hydrolysis, and the flakes are supplied to the extruder. In addition, since flake stains can cause clogging of the nozzle filter and deterioration of film-forming properties, detergents and alkalis should be used to enhance flake cleaning and a screen changer should be installed at the end of the extruder to actively remove foreign matter. Is preferred.

In the present invention, the composition of the flat yarn is not limited to recycled PET which is the main component, and other resins such as polyester resin represented by virgin PET or polyolefin, as long as it does not depart from the gist of the present invention. A system resin, a polyamide system resin, a polystyrene system resin, etc. can be appropriately mixed. Among these, polyolefin resins are suitable as a film-forming property for flat yarn molding, a modification for suppressing fibrillation of the yarn and improving mechanical strength. Specific examples of the polyolefin resin include medium density polyethylene, high density polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, and the like, with polypropylene being particularly preferred. As polypropylene, any of propylene homopolymer, propylene-ethylene block copolymer, propylene-ethylene random copolymer and the like can be used,
These polypropylenes may be used alone or in combination of two or more. This polypropylene melt fluorate (hereinafter abbreviated as MFR)
Is preferably 1 to 30 g / 10 min, and 3 to 10 g /
10 min is more preferable.

The proportion of the polyolefin resin in the composition containing recycled PET as a main component is 1 to 20% by weight.
Therefore, 3 to 10% by weight is more preferable. If the blending ratio of the polyolefin resin is less than 1% by weight, modification of recycled PET,
In other words, the effects of stable film formation, suppression of yarn fibrillation, and high tenacity are not exhibited, and 10% by weight
Even if the value exceeds the above range, the effect of modification will not be further increased, and gelation due to poor dispersion and deterioration of heat stretchability may occur.
A general blending method can be sufficiently used.

Further, when blended in a composition containing recycled PET as a main component, the slimy feeling of the flat yarn is suppressed,
As a filler that can be expected to have the effect of improving the lubricity of the molten resin in the extruder while reducing the thermal stretching resistance,
Calcium carbonate, magnesium carbonate, titanium oxide, magnesium hydroxide, magnesium stearate, talc,
There are inorganic fillers such as zeolite, kaolin, bentonite, and silica, and calcium carbonate having a particle system distribution of 1 to 10 μm is particularly preferable. The mixing ratio of the inorganic filler is 0.1 to 10% by weight, more preferably 1 to 5% by weight. If it is less than 0.1% by weight, the above-mentioned improvement effect cannot be expected, and if it exceeds 10% by weight, particles fall off from the yarn surface, and excessive dusting occurs in the yarn drawing process and weaving process. The problem is predicted. As a compounding method, it is preferable to blend as a masterbatch (pellet concentrated in a base resin) as a method for easily mixing uniform fine particles.

The flat yarn is often classified as a fiber material, but the basic point lies in the film forming technique. That is, in the present invention, a composition containing recycled PET as a main component is put into an extruder from a hopper, extruded in a molten state from a die by a single-layer or multi-layer inflation method or a T-die flat method, and cooled to produce the composition. It begins with the production of film films. The extruder used here can be a single-screw extruder used for extrusion molding of a general thermoplastic resin, but an extruder or a twin-screw extruder having a vent mechanism for inhaling and removing volatile components can be used. Even if it exists, stable extrusion molding is possible. In the present invention, since high IV recycled PET flakes are used, there is no particular problem in the case of dies, especially inflation dies, which may be a general upward blowing type, a horizontal type, or a vertical downward blowing type.

Next, the formed film is slit into an appropriate width to form a tape, and then formed into a tape by a hot drawing method such as a hot plate contact type, a hot roll type, or a hot air oven type.
It is stretched and oriented in the longitudinal and uniaxial directions by about 10 times, and further subjected to thermal relaxation treatment to obtain a flat yarn. Regarding this heat drawing, it is a necessary step for obtaining the tensile strength of the flat yarn, and in order to perform stable production at a high draw ratio,
Pre-heat treatment before stretching and two-stage hot stretching are effective. In the two-stage stretching, the first stage is 70 to 95 ° C. and is stretched 3 to 7 times,
As a second stage, the flat yarn is stretched 1.5 to 3 times at 150 to 220 ° C. and then subjected to a heat relaxation treatment by adding a high temperature of about 20 to 50 ° C. to obtain a flat yarn having stable physical properties without stretching unevenness. Can be obtained.

A feature of the present invention is that a flat yarn is directly produced from a raw material using 50% by weight or more of recycled PET flakes having a high IV for the purpose of obtaining a high quality flat yarn by recycling, and an IV value is 0.62. As described above, it is possible to inexpensively and stably manufacture a material having excellent mechanical performance such as strength and toughness and durability. The recycled PET flat yarn obtained according to the present invention can be used in various applications such as various packaging bags, carpet base cloths, sheets and tapes, from miscellaneous goods to interior materials, industrial materials, and civil engineering materials.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. Further, the physical properties of the molded products described in this example are measured by the following methods.

1) Intrinsic viscosity (IV) 0.5 g of measurement sample and 100 cc of orthochlorophenol
Put in a test tube and melt by heating at 130 ° C for 60 minutes, 20 to 3
After filtering with a 0 μ glass filter, the falling time T ₁ at 25 ° C. and the falling time T _{0 of} only the solvent were measured with an Ostwald viscometer, and the relative viscosity η _r = T ₁ / T ₀ and the intrinsic viscosity η according to the following equation: And the intrinsic viscosity IV were calculated. The filter filtrate was considered to be something other than PET, and a large amount of the measurement sample was taken by the weight, and the IV value of only PET was calculated. η = {(1.373 η _r −0.373) ^1/2 −1} /
0.343. IV = (0.26 + 0.581η−0.483η ² +
0.847η ³ ) x1.03

2) Yarn drawability: Evaluation is made by the number of stretch breaks during continuous 8 hours of operation during flat yarn molding for 50 yarns. ◎ ... less than once, ○ ... 2
3 times, △ ... 4 to 6 times, X ... 7 times or more.

4) State of Cracking of Yarn 10 m / min is sampled from the yarn wound on the bobbin to evaluate the state of cracking. ∘: No cracks can be confirmed, ∘: small cracks in 1 to 2 places, ∆: slightly large cracks, X: many large cracks.

5) Tensile strength Tensile strength (Kg) according to JIS Z-1533 when cut with an autograph at a sample length of 10 cm and a tensile speed of 50% / min.
And elongation (%) were measured 10 times, and the average value thereof was calculated.
On the other hand, for denier, a flat yarn was cut into 90 cm under a load of 0.05 g / d and the weight was measured to obtain an average value of n = 5, which was converted to SI unit from 1 dr = 1.11 dtex. The average intensity (g / d) was calculated from them and 1
It was converted to SI unit from g / d = 0.883 cN / dtex.

6) Bending wear According to JIS L-1096 wear strength A-2 method (bending method), a tape yarn of about 1000 dr is cut into 20 cm, and the tape yarn is attached so that the bar is sandwiched by folding in two and the tensile load is applied. 0.9 kg, pressing load 0.45 kg
Then, the number of times of cutting by reciprocating friction at a rate of 125 times / minute for 25 mm was measured. The average value of n = 5 was adopted.

8) After heat-resistant aging tape yarn is treated by dry heat of 150 ° C. × 8 hr,
The yarn tenacity was measured by n = 5 to obtain an average value, and the tenacity retention rate (%) at dry heat was calculated from the average yarn tenacity before treatment.

Examples 1 to 4 and Comparative Examples 1 and 2 In Example 1, PET = 0.72 PET flakes obtained by crushing, washing and drying used PET bottles were used, and polypropylene ( MFR = 2.2g /
10 min) 8% by weight, calcium carbonate 2% by weight, and pigment 1% by weight were added to prepare a resin composition having a total of 100% by weight. This resin composition was dried at 140 ° C. for 5 hours, and a T-screen was rotated at a screw rotation speed of 40 rpm and an extrusion rate of 58 Kg / hr using a 65 mmΦ single-screw extruder with a 300 mesh screen changer (no vent mechanism).
After forming a film by cooling with a chill roll cooling method using a die, slitting the film that has been cooled and solidified, 8
1. Applying tension with a 0 ° C. preheating roller, the first stage hot stretching is stretched 4 times at a temperature of 160 ° C. by a hot roll type, and then the second stage hot stretching is performed at a temperature of 190 ° C. by a hot plate contact type. Stretched 4 times to give a total draw ratio of 9.6 (maximum draw ratio of 0.85
Doubled) and further subjected to heat relaxation by heat treatment at 250 ° C. to obtain a flat yarn having a fineness of 1500 dtex.
Flat yarns having various physical properties were formed by changing the blending amounts of the polyolefin resin and the inorganic filler added to the recycled PET used in Example 1 and adjusting the draw ratio to 0.85 times the maximum draw ratio. From Table 1, in each of the examples, stable film forming properties are exhibited during film formation, the flat yarn is stretched well, stable quality in continuous production can be ensured, and yarn cracking and additive compounding effects are obtained. It has been recognized and has been clearly improved. The IV value of the obtained flat yarn was 0.64 or more, which was 0.6 in the comparative example.
Compared with 1 or less, the strength and elongation were large and the toughness was high. Therefore, it was excellent in bending wear and heat resistance and was suitable as a high performance recycled PET flat yarn for industrial material applications, cloth bags and the like.

[0024]

Example 5 93% by weight of recycled PET flakes with IV = 0.78 and M
FR = 2.0g / 10min polypropylene 5% by weight
And 2% by weight of calcium carbonate and dried at 140 ° C. for 5 hours, melt-kneaded with the same extruder as in Example 1 to form a film by an inflation method, and cooled with water to 20
Slit to a width of mm. 90 by hot plate stretching machine
A flat yarn of 2500 dtex was produced by performing two-stage drawing at 4.2 ° C. and 2.0 times at 200 ° C., but there was almost no drawing break or yarn cracking and it was good. The IV value of the obtained flat yarn was as high as 0.71 and the strength was 4.
7 cN / dtex, elongation was 53%, which was high performance not found in conventional recycled flat yarn. In addition, flexing wear is 155 times, and the dry heat aging strength retention rate is 96%, both of which are high, and high value-added recycled polyester flat yarns can be obtained. Bags for heavy goods and high strength tapes and sheets are obtained. It could be used as

[0026]

EFFECTS OF THE INVENTION According to the present invention, a high IV recycled PET flake is mainly used to directly form a film without pelletization, and the intrinsic viscosity (IV) is 0.62 or more, which is excellent in mechanical performance and durability. You can easily get flat yarn. In particular, since the conventional process is used as it is and the pelletizing process is omitted, it is possible to obtain a high-performance yarn that is inexpensive and has a low IV drop, and can be used for various packaging bags, carpet base cloths, sheets, tapes, and other interior goods, interior goods, It can be widely used for industrial materials and civil engineering materials.

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Claims (6)

[Claims] 1. A polymer comprising recycled polyethylene terephthalate is contained in an amount of 50% by weight or more and has an intrinsic viscosity (I).
V) 0.62 or more recycled polyester flat yarn. 2. A recycled polyester flat yarn according to claim 1, which contains 1 to 20% by weight of a polyolefin resin. 3. A recycled polyester flat yarn according to claim 1 or 2, which contains an inorganic filler in an amount of 0.1 to 10% by weight. 4. A melt extruded film is formed by using 50 wt% or more of flakes made of recycled polyethylene terephthalate having an intrinsic viscosity (IV) of 0.68 or more, and then hot-drawn while slitting to obtain an IV value of 0.62. A method for producing a recycled polyester flat yarn characterized by the above. 5. The method for producing a recycled polyester flat yarn according to claim 4, wherein the polyolefin resin is contained in an amount of 1 to 20% by weight. 6. The method for producing a regenerated polyester flat yarn according to claim 4, wherein the inorganic filler is contained in an amount of 0.1 to 10% by weight.