JP7053346B2 - Polylactic acid monofilament for tasteful beverage extraction filter and its manufacturing method - Google Patents

Description

The present invention relates to a monofilament for a palatable beverage extraction filter, a woven fabric for a palatable beverage extraction filter comprising the monofilament, and a method for producing the same.

Conventionally, paper, polypropylene, or polyethylene non-woven fabric has been mainly used as the material for the tasteful beverage extraction filter, but the transparency is poor and the tea leaves in the packaging material are difficult to see, and the paper is heat-sealed. There is a problem such as not being able to do it. Therefore, as a trend in recent years, the number of high-quality woven beverage extraction bags in which tea leaves in the beverage extraction bag can be seen is increasing.

Polyamide fiber is the mainstream as the material fiber of the tasteful beverage extraction filter used for the tasteful beverage extraction bag made of woven fabric. The extraction filter made of a woven fabric using a polyamide fiber has excellent morphological retention of a three-dimensional shape and also has abundant elastic recovery power against deformation, so that the woven fabric is soft and has an excellent texture. However, the extraction bag made of polyamide fiber is yellowed due to the influence of oxygen in the air, the size of the extraction bag changes due to the swelling of the polyamide fiber in boiling water, and the liquid runs out when the bag after extraction is taken out of the container. Problems such as poor sedimentation of the extraction bag in boiling water due to the light specific gravity of polyamide and environmental pollution due to the generation of nitrogen oxides due to incineration after use have been pointed out for some time.

For the purpose of improving such a problem of polyamide fiber, a tasteful beverage extraction filter using polyester fiber and the like have been studied. However, polyester fibers also have a problem regarding the disposal method after use. That is, polyester fibers hardly decompose in the natural environment and may generate high combustion heat when incinerated. Recently, they are used for fibers such as polycaprolactone and polylactic acid, which are biodegradable synthetic resins. Proposals have been made. These synthetic resins are so-called carbon-neutral materials whose raw materials are naturally derived, and have the advantage of having biodegradability. However, there are many problems in terms of practicality as compared with conventional (non-biodegradable) synthetic resins.
That is, in the case of polylactic acid fiber, the strength tends to be low and the boiling water shrinkage rate tends to be high. Various studies have been conducted to solve these problems.
For example, a tea bag using a polylactic acid resin having a relative viscosity of 2.7 to 4.0, a monomer content of 0.5% by weight or less, a Sn content of 30 ppm or less, and a linearity. Is disclosed (Patent Document 1).
Further, 99.0 to 85% by weight of the L-lactic acid or D-lactic acid component and 0.1 to 15% by weight of the polyethylene glycol component having a molecular weight of 1000 or more are block-copolymerized, and the relative viscosity is 2.5 or more. A method for producing a polylactic acid-based biodegradable fiber in which polylactic acid is melt-spun at 4000 m / min or more is disclosed (Patent Document 2).
Further, a modified cross-section polylactic acid monofilament having excellent scratch resistance and good weaving property is disclosed (Patent Document 3).

Japanese Unexamined Patent Publication No. 2002-104506 Japanese Unexamined Patent Publication No. 10-37020 Japanese Unexamined Patent Publication No. 2005-273804

However, the fiber specifically described in Patent Document 1 has a problem that it is difficult to increase the weaving speed because the boiling water shrinkage rate is 10% or more and the elongation is as low as 30% or less. In addition, since the spinning speed is as low as 1500 m / min, the productivity is poor and the cost is disadvantageous.
Although the fiber specifically described in Patent Document 2 has a boiling water shrinkage rate of 10% or less, the spinning speed is as high as 7,000 to 8,000 m / min, and stable spinning is difficult. Yes, ordinary equipment cannot handle high-speed winding. In terms of physical properties, it is difficult to achieve both a boiling water shrinkage rate of 10% or less and an elongation of 30% or more.
Since the fiber described in Patent Document 3 has a high boiling water shrinkage rate of 15% or more, there is a problem that the texture is easily bent and the opening is easily displaced, and the quality of the tea bag is easily deteriorated.
Therefore, the present invention has a good balance of strength and elongation, has physical properties with a low boiling water shrinkage rate, and can obtain processability comparable to that of polyester and nylon fibers even in a post-process such as weaving. The purpose is to provide a polylactic acid monofilament for a filter.

The present invention solves the above-mentioned problems, and is composed of poly-L-lactic acid having an optical purity of 97% or more, an intensity of 3 cN / dtex or more, an elongation of 30% or more, and a boiling water shrinkage rate of 10%. The first gist is a monofilament for a palatability beverage extraction filter, which is characterized by the following.
The second gist of the present invention is a woven fabric for a palatable beverage extraction filter using the above monofilament.
Further, in the present invention, a polylactic acid unstretched monofilament once wound at a spinning speed of 2500 m / min or more and 4000 m / min or less is stretched between a hot roller heated to 70 ° C. or higher and 110 ° C. or lower and a non-heated roller. The third gist is a method for producing the monofilament, which is heat-treated by a contact heater installed between the rollers and heated to 140 ° C. or higher and 165 ° C. or lower.

According to the present invention, the strength of the dough is equivalent to that of polyester or nylon, the texture is less likely to be bent or the opening is displaced, the processability in the post-process is good, and the filament for a practical tasteful beverage extraction filter and the filament thereof are used. The fabric used is provided.

It is a schematic process diagram which shows one Embodiment of the manufacturing method of the polylactic acid monofilament for a palatability beverage extraction filter of this invention.

Hereinafter, the present invention will be described in detail.
The present invention is characterized by being composed of poly-L-lactic acid having an optical purity of 97% or more, an intensity of 3 cN / dtex or more, an elongation of 30% or more, and a boiling water shrinkage rate of 10% or less. It is a polylactic acid monofilament for a tasteful beverage extraction filter.

The polylactic acid resin in the present invention contains L-lactic acid as a main component, and it is preferable that the optical purity of L-lactic acid is 97% or more. If the purity of L-lactic acid is less than 97%, the crystallinity is lowered and the heat resistance is deteriorated as the melting point is lowered, which is not preferable in practical use. Further, it may contain additives other than polylactic acid, such as polymers, particles, flame retardants, and antistatic agents, as long as the properties of polylactic acid are not impaired.
Further, in the polylactic acid resin in the present invention, it is preferable that L-lactic acid does not copolymerize components other than lactic acid.

The polylactic acid monofilament for a palatable beverage extraction filter of the present invention has a boiling water shrinkage rate of 10% or less. Within this range, the woven fabric does not bend during heat setting and is excellent in processability during molding. In addition, the obtained filter woven fabric can maintain the aperture ratio, does not shift, and does not bend. The boiling water shrinkage rate is preferably 3% or more from the viewpoint of easy handling without misalignment. The shrinkage rate of the polylactic acid monofilament for a palatable beverage extraction filter of the present invention after treatment with boiling water is a value measured by the method described later.

The polylactic acid monofilament for a palatable beverage extraction filter of the present invention has a breaking strength of 3 cN / dtex or more and a breaking elongation of 30% or more. From the viewpoint of ease of processing in the higher-order process, it is preferably 3 cN / dtex or more, and from the viewpoint of silk reeling stability, it is preferably 5 cN / dtex or less. Further, from the viewpoint of weaving stability, the elongation at break is 30% or more, and from the viewpoint of dimensional stability, 55% or less is preferable. If the physical characteristics are within this range, yarn breakage in the warping and weaving process is unlikely to occur, and the process passability is good.
Particularly preferably, the breaking strength is 3.5 cN / dtex or more, and the breaking elongation is 35% or more.

The fineness of the polylactic acid monofilament for a palatable beverage extraction filter of the present invention is preferably in the range of 15 dtex or more and 40 dtex or less.

The polylactic acid monofilament for a palatable beverage extraction filter of the present invention can be woven to produce a woven fabric suitable for use in a palatable beverage extraction filter.

As the structure of the woven fabric, a plain woven fabric or the like is suitable. In the present invention, as the woven fabric for the tasteful beverage extraction filter, the polylactic acid monofilament of the present invention may be woven using 100% or may be partially used. It is preferable to use 40% or more.

The fabric using the polylactic acid monofilament for a palatable beverage extraction filter of the present invention has an aperture ratio of 40% to 70 because it is easy to run out of liquid when used as a beverage extraction filter and the filter is less likely to be misaligned. % Is preferable.

The woven fabric made of the polylactic acid monofilament for a palatable beverage extraction filter of the present invention can be used as a palatable beverage filter by heat-treating, sealing and molding by an ultrasonic sealing method or the like.

The woven fabric made of the polylactic acid monofilament for a tasteful beverage extraction filter of the present invention can maintain the fabric strength even when sealed and has excellent moldability. Therefore, it is rectangular, planar, spherical, or triangular pyramid. It is possible to easily obtain a tasteful beverage extraction filter having various three-dimensional shapes, such as one having a four-handed net type, one having a polyhedral shape, and the like.

The beverage extraction filter obtained by using the fabric made of the polylactic acid monofilament for the preference beverage extraction filter of the present invention can be suitably used for various preference beverages such as black tea, barley tea, oolong tea, jasmine tea, green tea and coffee. can.

An example of a suitable manufacturing method of the monofilament for a palatable beverage extraction filter in the present invention is shown below.
FIG. 1 is a diagram illustrating an outline of a manufacturing process for a monofilament for a palatable beverage extraction filter of the present invention. The outline of the manufacturing process will be described with reference to FIG. FIG. 1 (a) shows a melt spinning apparatus, and FIG. 1 (b) shows a draw heat treatment apparatus, and using these apparatus, a monofilament for a tasteful beverage extraction filter of the present invention is obtained through a melt spinning step and a draw heat treatment step. be able to.
First, in FIG. 1 (a), in the melt spinning apparatus, the above poly-L-lactic acid is melted, weighed by a gear pump, and discharged from the spinneret 1. The discharged yarn 3 is subsequently cooled by the cooling air blown from the chimney 2 (cooling device), the oil is applied from the yarn convergent refueling guide 4, and then the yarn 3 is taken up by the first take-up roller 5. After being taken up by the second roller 6, it is taken up as an unstretched monofilament 7.
Next, in the stretching heat treatment apparatus of FIG. 1B, the unstretched monofilament 7 was passed through a feed roller 8 and a heated hot roller (roll heater 9), and subsequently heated by a contact type plate heater 10 and unheated. The polylactic acid monofilament (stretched monofilament 12) of the present invention can be obtained by stretching through the draw roller 11.
In the above, the spinneret is preferably L / D (mm / mm) = 0.35 / 0.35 to 0.75 / 0.75.
In the melt spinning step, the spinning temperature (temperature discharged from the spinneret) is preferably 210 ° C. or higher and 260 ° C. or lower, and more preferably 220 ° C. or higher and 255 ° C. or lower, from the viewpoint of the melting point of polylactic acid and the spinnability. The spinning speed (the speed of the fibers taken up by the take-up roller) is preferably 2000 m / min or more and 4500 m / min or less, and particularly preferably 2500 m / min or more and 4000 m / min or less. The unstretched monofilament once taken in such a range is continuously drawn and heat-treated.
Further, in the draw heat treatment step, the draw temperature is preferably 70 ° C. or higher and 110 ° C. or lower from the viewpoint of suppressing whitening of fibers and silk-reeling property. The draw ratio is appropriately selected from the viewpoints of spinning speed, required physical characteristics, and yarn-making property, and can be drawn 1.2 times or more and 3 times or less between the hot roller (roll heater 9) and the unheated draw roller 11. preferable. Above all, 1.4 times or more and 2.5 times or less are particularly preferable. The heat treatment step is performed by a plate heater 10 installed between the hot roller (roll heater 9) and the unheated draw roller 11, and the temperature is 140 ° C. or higher and 165 ° C. or lower from the viewpoint of required physical properties and the melting point of polylactic acid. preferable. This makes it possible to reduce the size of the stretch heat treatment apparatus and improve operability.
Next, the obtained polylactic acid monofilament can be woven, sealed by an ultrasonic sealing method or the like, and molded into an appropriate shape such as a triangular pyramid shape to obtain a palatable beverage extraction filter.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the examples described below. The various physical property measurement and evaluation methods are as follows.

<Relative viscosity (ηrel)>
Dissolve the sample in a mixed solvent of phenol / 1,1,2,2,-tetrachloroethane = 60/40 (mass ratio) to a concentration of 0.5 g / 50 ml, and use an Ostwald viscometer at a temperature of 20 ° C. Was measured.
<Strength, Elongation>
According to JIS L 1013, measurement is performed using an AGS-1KNG autograph tensile tester manufactured by Shimadzu Corporation under the conditions of a sample yarn length of 20 cm and a constant velocity tensile speed of 20 cm / min. The value obtained by dividing the maximum value of the load on the load-elongation curve by the fineness is defined as the strength (cN / dtex), and the elongation rate at that time is defined as the elongation (%).
<Boiling water shrinkage rate>
A sample having an initial value of 50 cm was immersed in boiling water for 20 minutes with an initial load of 200 mg, air-dried for 5 minutes, and then the shrinkage of boiling water was determined by the following formula.
Boiling water shrinkage rate (%) = {(initial sample length-sample length after shrinkage)} / (initial sample length x 100)
<Silk reeling property>
The yarn-making property was evaluated by the number of yarn breaks when 20 kg of yarn was manufactured, and ○ was judged as acceptable according to the following criteria.
◯: Thread breakage 1 time or less △: Thread breakage number exceeds 1 time and less than 3 times ×: Thread breakage number 3 times or more <Weaving property>
When the woven fabric was produced, the number of stops per 100 m (converted value) was calculated, and 0 to 2 times were passed, and more than that, it was rejected.

[Example 1]
A polylactic acid resin having a poly-L-lactic acid ratio of 98.6% is supplied to a melt spinning apparatus and melted under spinning conditions of a spinning temperature of 240 ° C. and a spinning speed of 2500 m / min using a spinneret having a hole diameter of 0.45 mm. It was spun and unstretched polylactic acid monofilament was wound up.
Subsequently, the wound unstretched polylactic acid monofilament was stretched 2.055 times between a hot roller heated to 90 ° C. and a non-heated roller, and a contact heater installed between the rollers was heated to 150 ° C. Was heat-treated using the above to obtain a polylactic acid monofilament for a tasteful beverage extraction filter of 33 dtex.
The obtained polylactic acid monofilament was woven with a plain weave structure under the conditions of a warp density of 100 lines / 2.54 cm and a weft density of 100 lines / 2.54 cm to obtain a woven fabric. The obtained woven fabric was refined and heat-treated at 140 ° C. to obtain a woven fabric for a filter. The obtained woven fabric for a filter was formed into a triangular pyramid shape by an ultrasonic sealing method to produce a filter for extracting a favorite beverage.

[Example 2]
A polylactic acid monofilament for a tasteful beverage extraction filter of 33 dtex was obtained by the same method as in Example 1 except that the spinning speed was 3000 m / min and the draw ratio was 1.683 times. A filter for extracting sex beverages was manufactured.

[Example 3]
A polylactic acid monofilament for a tasteful beverage extraction filter of 33 dtex was obtained by the same method as in Example 1 except that the spinning speed was 3000 m / min and the draw ratio was 1.733 times. A filter for extracting sex beverages was manufactured.

[Example 4]
A polylactic acid monofilament for a tasteful beverage extraction filter of 33 dtex was obtained by the same method as in Example 1 except that the spinning speed was 3300 m / min and the draw ratio was 1.486 times. Manufactured a filter for beverage extraction.

[Examples 5 to 8]
Polylactic acid monofilament for a tasteful beverage extraction filter of 33 dtex by the same method as in Example 1 except that the spinning speed was changed to 3500 m / min, the draw ratio was changed to 1.534 times, and the draw temperature was set to the conditions shown in Table 1. Then, in the same manner as in Example 1, a filter for extracting a palatable beverage was produced.

[Example 9]
A polylactic acid monofilament for a tasteful beverage extraction filter of 33 dtex was obtained by the same method as in Example 1 except that the spinning speed was 4000 m / min and the draw ratio was 1.534 times. Manufactured a filter for beverage extraction.

[Comparative Examples 1 to 5]
Polylactic acid monofilament for a palatable beverage extraction filter is obtained by the same method as in Example 1 except that the spinning speed, the stretching ratio, the stretching temperature, and the heat treatment temperature at the time of stretching are as shown in Table 2. An attempt was made to manufacture an extraction filter.

The polylactic acid monofilaments for beverage extraction filters obtained in Examples 1 to 9 have good silk-reeling and weaving properties, have an excellent balance between strength and elongation, and have a boiling water shrinkage of 10% or less. It was a monofilament for a sex beverage filter. Even when a filter for extracting a palatable beverage was produced from the obtained monofilament for a palatable beverage filter, the dimensional stability was excellent, and the quality was excellent with no opening deviation or bending of the texture. Further, in making the woven fabric for a filter, the processability at the time of processing was equivalent to that of polyester or polyamide.

On the other hand, in Comparative Example 1, the heat treatment temperature was low, and the obtained polylactic acid monofilament had a high boiling water shrinkage rate and was inferior in dimensional stability. The obtained woven fabric for a filter was liable to be misaligned and was inferior in dimensional method stability as compared with the example product.

In Comparative Example 2, the stretching temperature was high, yarn breakage occurred frequently in the stretching and heat treatment steps, and it was difficult to collect the polylactic acid monofilament.

In Comparative Example 3, the stretching temperature was low, and whitening was observed in a part of the polylactic acid monofilament obtained after the stretching / heat treatment step, and the physical characteristics were inferior. It was also inferior in weavability.

In Comparative Example 4, the spinning speed was slow, and there were many yarn breaks in the spinning step and the drawing / heat treatment step, and the spinning performance was inferior. Further, the obtained woven fabric for a filter was liable to be misaligned and was inferior in dimensional method stability as compared with the example product.

In Comparative Example 5, since the poly-L-lactic acid ratio was low, it was difficult to collect polylactic acid monofilament.

As in Examples 1 to 9, the undrawn yarn polylactic acid monofilament is wound by setting the spinning speed, and the undrawn yarn lactic acid monofilament once wound is drawn and heat-treated, so that the boiling water shrinkage rate is low and appropriate. Lactic acid monofilaments with high strength and elongation can be obtained with high productivity.

The polylactic acid monofilament for a palatable beverage extraction filter of the present invention has a good balance of strength and elongation, has physical properties with a low shrinkage of boiling water, and has the same processability as polyester and nylon fibers even in a post-process such as weaving. It is possible to obtain a polylactic acid monofilament for a palatable beverage extraction filter.

1 Spinning cap 2 Chimney 3 Thread 4 Convergent refueling guide 5 1st take-up roller 6 2nd take-up roller 7 Unstretched monofilament 8 Feed roller 9 Roll heater 10 Plate heater 11 Draw roller 12 Stretched monofilament a Molten spinning device b Stretching heat treatment Device

Claims (7)

It is composed of poly-L-lactic acid having an optical purity of 97% or more, an intensity of 3 cN / dtex or more, an elongation of 30% or more, a boiling water shrinkage rate of 3% or more and 10% or less, and a fineness of 15 dtex or more and 40 dtex or less. Preference Beverage Extraction Filter Polylactic acid monofilament for woven fabrics . The polylactic acid monofilament for woven fabrics according to claim 1, wherein the boiling water shrinkage rate is 9.8% or less. The polylactic acid monofilament for a woven beverage extraction filter according to claim 1 or 2, wherein the unstretched monofilament is a monofilament obtained by winding and then stretching the unstretched monofilament. A woven fabric for a tasteful beverage extraction filter using the monofilament according to any one of claims 1 to 3 . The woven fabric for a tasteful beverage extraction filter according to claim 4 , which has an aperture ratio of 40 to 70%. Poly-L-lactic acid having an optical purity of 97% or more is melted, discharged from a spinneret, cooled by cooling air, and then wound once at a spinning rate of 2000 m / min or more and 4500 m / min or less. The monofilament is stretched between a hot roller heated to 70 ° C. or higher and 110 ° C. or lower and a non-heated roller, and heat-treated by a contact heater installed between the rollers at 140 ° C. or higher and 165 ° C. or lower. A method for producing a monofilament for a palatability beverage extraction filter having a fineness of 3 cN / dtex or more, an elongation of 30% or more, a boiling water shrinkage rate of 3% or more and 10% or less, and a fineness of 15 dtex or more and 40 dtex or less . Poly-L-lactic acid having an optical purity of 97% or more is melted, discharged from a spinneret, cooled by cooling air, and then wound once at a spinning rate of 2000 m / min or more and 4500 m / min or less. The monofilament is stretched 1.2 times or more and 3 times or less between a hot roller heated to 70 ° C. or more and 110 ° C. or less and a non-heated roller, and heated to 140 ° C. or more and 165 ° C. or less installed between the rollers. A monofilament for a tasteful beverage extraction filter having a strength of 3 cN / dtex or more, an elongation of 30% or more, a boiling water shrinkage rate of 3% or more and 10% or less, and a fineness of 15 dtex or more and 40 dtex or less, which is heat-treated with a contact-type heater. Production method.

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