JP7279231B2 - Polylactic acid monofilament for palatability beverage extraction filter and its production method - Google Patents

Description

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

Traditionally, paper and polypropylene or polyethylene non-woven fabrics have been the main materials used as materials for extracting palatable beverages. There are problems such as not being able to Therefore, as a trend in recent years, there has been an increase in the number of bags for extracting a favorite beverage made of woven fabric, which have a high-class feel and allow the tea leaves in the bag to be seen.

Polyamide fibers are mainly used as material fibers for filters for extracting a favorite beverage, which are used in bags for extracting a favorite beverage made of fabric. A woven extraction filter using polyamide fibers has excellent three-dimensional shape retention and elastic recovery against deformation, so that the woven fabric is soft and has an excellent texture. However, the extraction bag made of polyamide fiber is subject to yellowing due to the influence of oxygen in the air, dimensional change of the extraction bag due to swelling of the polyamide fiber in hot water, and lack of liquid when the bag is removed from the container after extraction. It has long been pointed out that the polyamide has a low specific gravity, so that the extraction bag does not easily settle in boiling water, and that the incineration after use causes environmental pollution due to the generation of nitrogen oxides.

For the purpose of improving such problems of polyamide fibers, studies have been made on a filter for extracting a soft drink made of polyester fibers and the like. However, there are also problems with polyester fibers over how to dispose of them after use. In other words, polyester fibers hardly decompose in the natural environment, and when incinerated, there is a risk of generating a high amount of combustion heat. A proposal is made. These synthetic resins are so-called carbon-neutral materials derived from nature, and have the advantage of being biodegradable. However, compared with conventional (non-biodegradable) synthetic resins, there are many problems in terms of practicality.
That is, polylactic acid fibers tend to have low strength and high shrinkage in boiling water. Various studies have been conducted to solve these problems.
For example, a tea bag using a linear polylactic acid resin having a relative viscosity of 2.7 to 4.0, a monomer content of 0.5% by weight or less, and a Sn content of 30 ppm or less. is disclosed (Patent Document 1).
In addition, 99.0 to 85% by weight of L-lactic acid or D-lactic acid component and 0.1 to 15% by weight of 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 polylactic acid-based biodegradable fibers has been disclosed in which polylactic acid is melt-spun at 4000 m/min or higher (Patent Document 2).
A modified cross-section polylactic acid monofilament having excellent abrasion resistance and good weaving properties has been disclosed (Patent Document 3).

Japanese Patent Application Laid-Open No. 2002-104506 JP-A-10-37020 JP-A-2005-273084

However, the fibers specifically described in Patent Document 1 have a boiling water shrinkage rate of 10% or more and a low elongation of 30% or less, so there is a problem that it is difficult to increase the weaving speed. In addition, since the spinning speed is as low as 1500 m/min, the productivity is poor, which is disadvantageous in terms of cost.
The fibers specifically described in Patent Document 2 have a boiling water shrinkage of 10% or less, but the spinning speed is as high as 7000 to 8000 m/min, making stable spinning difficult. Therefore, normal equipment cannot handle high-speed winding. In terms of physical properties, it is difficult to achieve both boiling water shrinkage of 10% or less and elongation of 30% or more.
The fibers described in Patent Document 3 have a boiling water shrinkage rate as high as 15% or more, and therefore tend to cause warping of the texture and misalignment of the opening, resulting in a problem that the quality of tea bags tends to deteriorate.
Therefore, the present invention has a good balance of strength and elongation, has physical properties with low boiling water shrinkage, and can obtain a palatability beverage extraction that can obtain processability comparable to that of polyester and nylon fibers even in subsequent processes such as weaving. An object of the present invention is to provide a polylactic acid monofilament for filters.

The present invention solves the above problems, and is made of poly-L-lactic acid with an optical purity of 97% or more, a strength of 3 cN/dtex or more, an elongation of 30% or more, and a boiling water shrinkage of 10%. A first aspect is a monofilament for a palatable beverage extraction filter characterized by:
In addition, the second aspect of the present invention is a woven fabric for a palatability beverage extraction filter using the monofilament.
Further, in the present invention, the polylactic acid undrawn monofilament once wound at a spinning speed of 2500 m/min or more and 4000 m/min or less is drawn between a hot roller heated to 70° C. or more and 110° C. or less and a non-heated roller. In addition, the third gist is a method for manufacturing the monofilament, in which the monofilament 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 fabric is equivalent to that of polyester or nylon, the texture is less likely to curl and the opening shift occurs, the processability in the post-process is good, and the filament for a practical taste beverage extraction filter and the same The fabric used is provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic process drawing which shows one embodiment of the manufacturing method of the polylactic acid monofilament for palatability drink extraction filters of this invention.

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

The polylactic acid resin in the present invention contains L-lactic acid as a main component, and the optical purity of L-lactic acid is preferably 97% or more. When the purity of L-lactic acid is less than 97%, the crystallinity is lowered and the melting point is lowered, resulting in poor heat resistance, which is not practically preferable. In addition, additives such as polymers and particles other than polylactic acid, flame retardants, and antistatic agents may be contained within a range that does not impair the properties of polylactic acid.
In the polylactic acid resin of the present invention, L-lactic acid preferably does not copolymerize components other than lactic acid.

The polylactic acid monofilament for a filter for extracting a palatable beverage of the present invention has a boiling water shrinkage rate of 10% or less. By setting it within this range, the woven fabric does not bend during heat setting and is excellent in workability during molding. In addition, the obtained filter fabric can maintain the open area ratio, and does not cause any misalignment or warping of the weave. In particular, the boiling water shrinkage ratio is preferably 3% or more from the viewpoint of ease of handling without misalignment. The shrinkage ratio of the polylactic acid monofilament for a filter for extracting a palatable beverage of the present invention after boiling water treatment 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. It is preferably 3 cN/dtex or more from the viewpoint of ease of processing in higher-order processes, and preferably 5 cN/dtex or less from the viewpoint of spinning stability. From the viewpoint of weaving stability, the elongation at break is 30% or more, and from the viewpoint of dimensional stability, it is preferably 55% or less. If the physical properties are within this range, yarn breakage is less likely to occur in the warping and weaving processes, and process passability is improved.
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 filter for extracting a palatable beverage of the present invention is preferably in the range of 15 dtex or more and 40 dtex or less.

By weaving the polylactic acid monofilament for a preferred beverage extraction filter of the present invention, a fabric suitable for use in a preferred beverage extraction filter can be produced.

Plain weave or the like is preferable as the texture of the woven fabric. In the present invention, the polylactic acid monofilament of the present invention may be 100% woven or partially used as the woven fabric for a filter for extracting a palatable beverage. Preferably, 40% or more is used.

The woven fabric using the polylactic acid monofilament for a filter for extracting a palatable beverage of the present invention has an opening ratio of 40% to 70% because it is easy to run out of liquid when used as a filter for extracting beverages and the mesh of the filter is less likely to be misaligned. % is preferred.

The woven fabric made of the polylactic acid monofilament for a filter for extracting a favorite beverage of the present invention can be heat-treated, sealed by an ultrasonic sealing method or the like, and molded to be used as a filter for a favorite beverage.

The woven fabric made of polylactic acid monofilament for a filter for extracting palatable beverages according to the present invention can retain the strength of the fabric even when sealed and has excellent moldability. It is possible to easily obtain a variety of three-dimensionally shaped beverage extracting filters, such as those of four-handed mesh type, and other polyhedral shapes.

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

An example of a suitable method for producing a monofilament for a filter for extracting a palatable beverage according to the present invention is shown below.
FIG. 1 is a diagram for explaining the outline of the manufacturing process of the monofilament for a filter for extracting a palatability beverage of the present invention. The outline of the manufacturing process will be described with reference to FIG. FIG. 1(a) shows a melt spinning device and FIG. 1(b) shows a drawing heat treatment device. Using these devices, a monofilament for a filter for extracting a palatability beverage of the present invention is obtained through a melt spinning step and a drawing heat treatment step. be able to.
First, in FIG. 1(a), the above poly-L-lactic acid is melted in a melt spinning apparatus, weighed by a gear pump, and discharged from a spinneret 1. FIG. The discharged yarn 3 is subsequently cooled by cooling air blown from the chimney 2 (cooling device), oiled by the yarn convergence oil supply guide 4, and then taken up by the first take-up roller 5. After being taken up by the second roller 6 , it is wound up as an unstretched monofilament 7 .
Next, in the drawing heat treatment apparatus of FIG. It can be drawn through a draw roller 11 to obtain the polylactic acid monofilament (drawn monofilament 12) of the present invention.
In the above, the spinneret preferably has L/D (mm/mm)=0.35/0.35 to 0.75/0.75.
In the melt spinning process, the spinning temperature (the temperature discharged from the spinneret) is preferably 210° C. or higher and 260° C. or lower, more preferably 220° C. or higher and 255° C. or lower, from the viewpoint of the melting point of polylactic acid and spinning properties. The spinning speed (the speed of the fiber taken 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 that has been drawn in such a range is subsequently subjected to stretching and heat treatment.
Moreover, in the drawing heat treatment step, the drawing temperature is preferably 70° C. or higher and 110° C. or lower from the viewpoint of suppression of whitening of fibers and spinning properties. The draw ratio is appropriately selected from the viewpoint of spinning speed, required physical properties, and spinning properties. preferable. Among them, 1.4 times or more and 2.5 times or less are particularly preferable. The heat treatment process is performed by a plate heater 10 installed between a hot roller (roll heater 9) and an unheated draw roller 11, and from the viewpoint of the required physical properties and the melting point of polylactic acid, the temperature is 140° C. or higher and 165° C. or lower. preferable. As a result, the size of the stretching heat treatment apparatus can be reduced, and the operability is improved.
Next, the resulting polylactic acid monofilament is 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.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples described below. In addition, various physical-property measurement and evaluation methods are the following methods.

<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 type viscometer at a temperature of 20 ° C. measured by
<Strength, Elongation>
In accordance with JIS L 1013, using an AGS-1KNG autograph tensile tester manufactured by Shimadzu Corporation, measurement is performed under the conditions of a sample thread length of 20 cm and a constant 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 taken as the strength (cN/dtex), and the elongation rate at that time is taken as the elongation (%).
<Boiling water shrinkage>
A sample with an initial value of 50 cm was applied with an initial load of 200 mg, immersed in boiling water for 20 minutes, and air-dried for 5 minutes.
Boiling water shrinkage rate (%) = {(initial sample length - sample length after shrinkage)} / (initial sample length x 100)
<Spinnability>
The spinning property was evaluated by the number of yarn breakages when 20 kg of yarn was produced.
○: Thread breakage 1 time or less △: Thread breakage number exceeds 1 time and is less than 3 times ×: Thread breakage number is 3 or more times <Weaving performance>
When the woven fabric was produced, the number of stoppages per 100 m (converted value) was determined, and 0 to 2 times was considered acceptable, and more than that was considered unacceptable.

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

[Example 2]
A 33 dtex polylactic acid monofilament for a beverage extraction filter was obtained in the same manner 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 sexual beverages was manufactured.

[Example 3]
A 33 dtex polylactic acid monofilament for a beverage extraction filter was obtained in the same manner 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 sexual beverages was manufactured.

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

[Examples 5 to 8]
A 33 dtex polylactic acid monofilament for a palatability beverage extraction filter was produced in the same manner 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 drawing temperature was changed to the conditions shown in Table 1. was obtained, and in the same manner as in Example 1, a filter for extracting a palatability beverage was produced.

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

[Comparative Examples 1 to 5]
A polylactic acid monofilament for a filter for extracting a favorite drink was obtained in the same manner as in Example 1, except that the spinning speed, draw ratio, drawing temperature, and heat treatment temperature during drawing were set as shown in Table 2. An attempt was made to manufacture an extraction filter.

The polylactic acid monofilaments for preference beverage extraction filters obtained in Examples 1 to 9 have good spinning and weaving properties, an excellent balance between strength and elongation, and a boiling water shrinkage rate of 10% or less. It was a monofilament for liquid beverage filters. Even when a filter for extracting a favorite drink was produced from the obtained monofilament for a filter for a favorite drink, the monofilament was excellent in dimensional stability, free from misalignment of the opening and warping of the texture. In addition, when used as a filter fabric, the workability at the time of processing was equivalent to that of polyester and polyamide.

On the other hand, in Comparative Example 1, the heat treatment temperature was low, and the resulting polylactic acid monofilament had a high boiling water shrinkage rate and poor dimensional stability. The obtained filter fabrics tended to be misaligned and were inferior in dimensional stability as compared with the products of the examples.

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

In Comparative Example 3, the drawing temperature was low, and whitening was observed in part of the polylactic acid monofilament obtained after the drawing and heat treatment steps, resulting in poor physical properties. In addition, the weavability was also inferior.

In Comparative Example 4, the spinning speed was slow, the yarn was often broken during the spinning process and the drawing/heat treatment process, and the spinning property was poor. In addition, the obtained filter fabrics tended to be misaligned and were inferior in dimensional stability as compared with the products of the examples.

Since Comparative Example 5 had a low poly-L-lactic acid ratio, it was difficult to obtain a polylactic acid monofilament.

As in Examples 1 to 9, by setting the spinning speed, winding the undrawn polylactic acid monofilament, and drawing and heat-treating the once-wound undrawn polylactic acid monofilament, the boiling water shrinkage rate is low and appropriate. Lactic acid monofilaments with suitable strength and elongation can be obtained with good productivity.

The polylactic acid monofilament of the present invention for a filter for extracting palatable beverages has a good balance of strength and elongation, and has physical properties such as low boiling water shrinkage. It is possible to obtain a polylactic acid monofilament for a beverage extraction filter with a palatability.

1 Spinneret 2 Chimney 3 Thread 4 Convergent oil supply guide 5 First take-up roller 6 Second take-up roller 7 Undrawn monofilament 8 Feed roller 9 Roll heater 10 Plate heater 11 Draw roller 12 Drawn monofilament a Melt spinning device b Drawing heat treatment Device

Claims (3)

A filter for extracting a delicious beverage, comprising poly-L-lactic acid having an optical purity of 97% or more, having a strength of 3 cN/dtex or more, an elongation of 30% or more, and a boiling water shrinkage of 10% or less. Polylactic acid monofilament. A fabric for a filter for extracting a palatable beverage using the monofilament according to claim 1. A polylactic acid undrawn monofilament once wound at a spinning speed of 2000 m/min or more and 4500 m/min or less is stretched between a hot roller heated to 70 ° C. or more and 110 ° C. or less and a non-heated roller, and stretched between the rollers. 2. The method for producing a monofilament for a filter for extracting a palatable beverage according to claim 1, wherein the heat treatment is performed with a contact heater installed at 140° C. or higher and 165° C. or lower.

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