JP3441402B2 - Blended yarn containing polylactic acid fiber - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a blended yarn composed of biodegradable fibers and natural fibers.

[0002]

2. Description of the Related Art Conventionally, many chemical fibers and synthetic fibers have been produced and used together with natural fibers in various fields according to their respective fiber characteristics. However, the fiber characteristics are desired requirements for specific applications. However, these fibers have been blended and mixed, or mixed and twisted and woven to impart new properties to meet their applications.

An example is a means for producing a blended yarn by mixing natural fibers such as cotton, silk (for silk spinning), and wool with cut fibers and filaments of synthetic fibers in the spinning process and twisting them. Various manufacturing methods are already known.

In recent years, however, from the standpoint of environmental protection, the reuse of various household textile products, especially clothing, has been called for, and the use of biodegradable materials that are completely decomposed by the action of microorganisms in products that cannot be reused. In addition, there is a social demand for the use of materials with low air pollution when incinerated.

To explain this in more detail, in general, landfilling or incineration is used as a method for discarding non-reusable textile products. Among the materials for blending, natural fibers are gradually decomposed by microorganisms such as soil under the natural environment and eventually disappear. Also, since it is easy to incinerate, there is no concern about air pollution or environmental destruction even when left unused or incinerated.

However, fibers such as nylon, polyester, and acrylic, which are conventionally used synthetic fiber materials for blending, are not decomposed by microorganisms, and since such materials are chemically stable, they are synthetic fiber parts. Remain in the soil for long periods of time, resulting in environmental problems. Furthermore, when these synthetic cotton parts are incinerated, the calorific value during combustion is high, which not only shortens the life of the incinerator but also generates harmful gas such as cyan gas in the case of polyacrylonitrile-based synthetic fiber material. There is also a risk of doing it.

[0007]

As described above, when a synthetic fiber material is used as one of the constituent materials in the currently used blended yarn, various environmental obstacles occur at the time of disposal after use. There is.

The present invention solves the above problems of conventional blended yarns, does not impair the inherent performance of the contained synthetic fiber material, and is relatively short in the soil, activated sludge or compost at the time of disposal. The present invention intends to provide a novel blended yarn which decomposes in time, does not generate a harmful gas upon incineration, and has a combustion heat as low as that of cellulose and can suppress generation of a high temperature gas.

[0009]

In order to solve the above problems, the present invention has the following configuration. That is, the first invention is a blended yarn composed of biodegradable fibers and natural fibers such as cotton, silk and wool, wherein the biodegradable fibers have a tensile strength of 2.0 g / d or more and a breaking elongation of 100. % or less, a configuration characterized by using the staple fiber of the optical purity of 9 8% or more polylactic acid fibers, also the second th invention, a biodegradable fiber, cotton, silk, wool, etc. 1. A blended yarn composed of natural fibers, which has a tensile strength as a biodegradable fiber.
0 g / d or more, elongation at break of 100% or less, the optical purity of 9 8%
This is a constitution characterized by using the above polylactic acid fiber filament. A third aspect of the invention is the configuration according to the first and second aspects of the invention, characterized in that the mixing ratio of the polylactic acid fiber is 20% by weight or more and less than 80% by weight.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a biodegradable fiber which can be used as a yarn, the polyhydroxybutyrate (hereinafter referred to as PHB) disclosed by the present applicant in Japanese Patent Application Laid-Open No. 7-305227 has been disclosed.
, Polycaprolactone (hereinafter referred to as PCL),
Fibers obtained from melt-formable polymers such as polylactic acid are mentioned.

As described in the above publication, the PHB not only has an excessively high production cost but also requires a large amount of energy for collecting and purifying the polymer for biosynthesis by a microorganism, and controls the molecular weight and crystallinity. Therefore, there are difficulties in molding and control of the physical properties of the molded product, and it is difficult to industrially inexpensively provide performance and moldability according to the application.
In addition, since PCL has a melting point of too low as 60 ° C., it has a large amount of creep during use, and it has practically serious problems such as lack of maintaining the morphological stability of the product and extreme decrease in strength depending on the operating temperature. There is.

On the other hand, polylactic acid is a relatively low cost, thermoplastic resin having a melting point of 178 ° C. and sufficient heat resistance, and as described above, it can be melt-molded and is relatively low in manufacturing cost. Therefore, it is the most suitable polymer for the biodegradable fiber of the present invention.

[0013] The optical purity of the polylactic acid used in the present invention (hereinafter, abbreviated as OP) is 9 8% or more. OP is 9
If it does not reach 8 %, the crystallinity of the polymer is low and the crystallization speed is slow, so that yarn breakage is likely to occur during fiber production, and the operability is lowered and the crystallinity of the obtained fiber is lowered. Has a low strength, does not have thermal stability, and has a problem in the manufacturing process such as a change in dyeability and a problem in use. Further, there is a problem that the mature setting property, which is indispensable for the production of the woven or knitted fabric, becomes poor, and the processed yarn or the like by the push-in aging gear method cannot be performed.

When the OP is 90% or more, the crystals are good and the above problems are small. Particularly when the OP is 98% or more, the crystallinity of the fiber is particularly excellent, there are few problems during fiber production, and the strength, maturation resistance and heat setting property of the obtained fiber are extremely good.

Generally, polylactic acid is an optical isomer of L-
It is a polymer (copolymer in a broad sense) in which the body and D-form lactic acid are mixed, and the optical purity of polylactic acid is determined by their ratio. The body of natural organisms consists mostly of L-compounds,
Therefore, there are abundant enzymes that decompose L-form polymers and compounds. However, the D-form rarely exists in nature, and a polymer or compound containing a large amount of D-form is difficult to decompose in nature. Therefore, the polylactic acid fiber of the present invention is also preferably poly-L-lactic acid having a high L-lactic acid content.

Therefore, in the composition of polylactic acid fiber, the biodegradability decreases as the proportion of D-form increases. In this sense, the higher OP is preferable.

The polylactic acid fiber is produced by melt spinning or solution spinning of polylactic acid, and it is preferable in that the melt spinning has a small effect on production efficiency, variety of products, and environment in production.

In the melt spinning, a polylactic acid resin is heated and melted to a temperature equal to or higher than the melting point, discharged from the spinneret having fine holes and cooled in the air to form fibers. The discharged and cooled fiber is wound to go to the next step, but for long fiber, the winding speed is a method called a conventional spinning, which has a winding speed of about 2,000 m / min or less, POY (Partia
lly 0riented Yarn) method
Method less than 500m / min, HOY (Highly 0riented Ya)
rn) method with a winding speed of about 5,500 m / min or more, or immediately after spinning using the same device S
The PD (Spin Draw) method or the like can be adopted. Further, since short fibers are overwhelmingly extruded from a large number of nozzles as compared with long fibers, the winding speed is usually slower than that of long fibers, and it is usually 2,000 m / min or less. In particular,
Most commonly done at 1,500 m / s or less.

Although the draw ratio in the above process varies depending on the spinning speed and the required performance of the desired stable fiber, a fiber having a tensile strength of 2.0 g / d or more and a cutting and elongation of 100% or less is used. Must be set to obtain. If the tensile strength is less than 2.0 g / d, problems may occur during the working process, and the strength of the final product may be insufficient, which may cause problems in practice. The cutting elongation is 100
If it exceeds%, the carding effect becomes poor and it becomes difficult to put it to practical use.

As the natural fiber mixed with the polylactic acid fiber, cotton fiber, silk fiber for silk spinning, wool fiber and the like are used. Each of the fibers of cotton, silk, and wool consists of staple fibers having a unique fineness and fiber length, and the polylactic acid fiber mixed with each of these fibers is melt-spun in the case of the long fibers. It is then stretched and then used in the form of staple fibers which are mechanically cut to length. Further, in the case of polylactic acid fiber directly formed into short fibers, this is used after being cut or as it is for mixed spinning.

In general, when different kinds of fibers are mixed, it is optimal that the fineness and the fiber length be the closest to those of the mixed spinning, if the uniformity of the obtained mixed yarn is desired to be high. For example, when cotton fibers are to be blended, polyester staples have conventionally had a fineness of 1.0 to 1.5 d and a fiber length of 30 to 5
In the polylactic acid fiber of the present invention, the fineness of 1.0 to 10 mm is frequently used for such purpose.
It is preferable that the fiber length is 1.5 d and the fiber length is 30 to 50 mm. Similarly, in the case of worsted spinning using both wool and polylactic acid fiber, it is preferable that the fineness of the polylactic acid fiber is 1.0 to 3.0 d and the fiber length is 70 to 90 mm. In this case, the fineness of the polylactic acid fiber is preferably 3.0 to 7.0 d, and the fiber length is preferably 30 to 50 mm.

Further, the swelling of the blended yarn obtained by appropriately setting the shrinkage ratio (for example, heat shrinkage ratio) together with setting the fineness of the polylactic acid fiber can be adjusted. For example,
The bulge of the blended yarn can be thickened by increasing the shrinkage ratio of the fibers of large fineness and setting the shrinkage ratio of the fibers of fineness to be low.

The polylactic acid fiber used in the blended yarn of the present invention is
Any fiber cross section can be used, such as ordinary O cross section fiber, flat cross section fiber, Δ cross section fiber, hollow cross section fiber (○, Δ), and non-circular cross section fiber such as U-shaped cross section fiber. In consideration of wearing feeling and the like, a mixture of flat cross-section fibers, modified cross-section fibers such as Δ cross-section fibers and U cross-section fibers is preferable to simple cross-section fibers. In order to improve the texture and the feeling of swelling, the modified cross-section fiber is mixed in the polylactic acid fiber at a weight ratio of about 10% or more, preferably 20% or more, more preferably 30% or more.
In addition, the polylactic acid fiber is not limited to the straight fiber cut into a predetermined length after the spinning and drawing, and after being crimped by the stuffing method, the indentation heating gear method, the high-speed air jet indentation method, etc., the length of 20 to 100 mm Cut fibers cut into pieces can also be used.

The polylactic acid fiber having the above-mentioned structure and the natural fiber are mixed in a series of spinning steps. As for the cotton blending method, the raw cotton method in which the raw cotton state before the carding process is blended, the sliver method in which both fibers are individually blended in a carding machine, and then the two fibers are blended in the sliver state are used. It is possible to use a roving method in which the two are combined with a spinning machine after being formed into a composite. In the cotton spinning and the worsted spinning, it is preferable to mix them in a sliver state from the viewpoint of uniformity, and in the case of woolen spinning, it is preferable to mix them in a raw wool state.

As described above, a blended yarn generally seeks to obtain new fiber characteristics by compensating the advantages and disadvantages of each of the constituent fibers. However, the characteristic of one fiber is imparted to a blended yarn containing it. In order to do so, it is necessary to add at least 20% (by weight) of the fiber. Therefore, in the case of blended spinning of polylactic acid fiber and natural fiber, when the blended amount of either one reaches 20% (weight ratio), it will be buried in the characteristics of the other fiber. It is preferable that the mixing ratio of 20% or more and less than 80% (all are weight ratios).

The polylactic acid fiber and the natural fiber of the present invention configured as described above are produced by a known cotton yarn spinning process (1 inch spinning),
Through a worsted spinning process (2, 2.5, 3 inch spinning), a woolen spinning process, a silk yarn spinning process, or the like, both fibers are mixed at a predetermined portion in the process, and a spun yarn is obtained. And sent out from the spinning machine. The spun yarn of the present invention is used for various purposes after weaving or knitting as it is or as a single yarn.

As described above, the embodiment in which the polylactic acid fiber is cut into a predetermined length to form the staple fiber and is mixed with the natural fiber is described in detail. However, unlike the second invention, the polylactic acid fiber is not cut, It is also possible to produce natural fiber and composite spun yarn in the form of filaments.

Specifically, in the spinning process, (1) the roving of natural fibers, which is supplied to the draft part of the spinning device and immediately after exiting the front roller, is left in an opened state, and the draft part is placed on the roving. Core yarn type obtained by a method of stacking and twisting polylactic acid fiber filament yarns that have passed through only the front roller without being supplied to
(2) The roving yarn of the natural fiber which is supplied to the draft part of the spinning device and immediately after exiting the front roller is arranged on both sides,
Place the polylactic acid fiber filament yarn that has passed through the front roller only in the center without supplying it to the draft part,
Examples thereof include a silofil type obtained by ply twisting, (3) a cover ring type and a twisted yarn type obtained by ply twisting a natural fiber spun yarn and a polylactic acid fiber filament. In addition, the above "Silofill" is Wool Developme
nt International Limited is a registered trademark.

The waste of the woven or knitted fabric using the spun yarn of the present invention after use can be naturally eliminated in the case of landfill treatment because both the polylactic acid fiber and the natural fiber are excellent in biodegradability. When burning, the heat of combustion of polylactic acid fiber is 3,400 to 3,500 cal / g, which is about the same as that of newsprint, and natural fiber is also made of animals and plants and can be burned at a relatively low temperature. It can be incinerated easily without damaging it and generating no toxic gas. Either method can be easily implemented without causing environmental damage.

[0030]

The present invention will be described in more detail with reference to the following examples. In this example, “%” means “% by weight” unless otherwise specified. Relative viscosity: ηrel
Is fettle / tetrachloroethane = 6/4 (heavy weight ratio)
It was determined by a conventional method at 20 ° C. in the mixed solvent of. Melting point (Tm)
Was determined from the beak value of endothermic beak of a differential scanning meter (hereinafter referred to as DSC) manufactured by Rigaku Denki Co., Ltd.

L-lactic acid content is 99.4%, ηrel
(Relative viscosity) = 3.1, weight average molecular weight is 120,000
0, a biodegradable composition having a melting point of 175 ° C. was melted at 230 ° C., extruded into the air from a spinning nozzle having a hole diameter of 0.2 mm and 48 holes, and spun by a known method. After obtaining 1.5d polylactic acid fiber filament,
The polylactic acid fiber filament was cut into a fiber length of 38 mm to obtain a polylactic acid fiber stable fiber. The stable fiber has a strength of 4.0 g / d and an elongation of 3
The elastic modulus was 5% and the elastic modulus was 520 kg / mm ² .

A carding machine-dried sliver made of only the polylactic acid fiber staple fibers and a carding machine-dried sliver made of only the same weight of cotton fiber per unit length are simultaneously formed in the same drawing. It is fed to the machine and mixed with the sliver to form a blended sliver with a polylactic acid fiber content of 50%. After further doubling and drafting to homogenize the sliver, a unit weight of 0.5 g / m is twisted with a roving machine. A roving of several 0.8 times / inch was formed.

Next, the above roving yarn is supplied to a spinning machine, subjected to a draft of 35 times and a twist number of 23 times / inch and spun out, and spun at a 40th count (English cotton count) with a polylactic acid fiber content of 50%. I got a thread. Using this blended yarn for both the warp and weft, a plain woven fabric 1 of polylactic acid fiber / cotton blend was produced by a conventional method.

In addition, the above polylactic acid fiber filament is
A 6 mm fiber length was cut into staple fibers, and a carding machine sliver consisting only of the polylactic acid fiber stable fibers and a tobb consisting of this and only the same weight of wool fiber per unit length Both were mixed and mixed to prepare a roving. Then, this was supplied to a spinning machine in the form of single roving, and a draft of 20 times and a twist of 660 times / meter were applied to obtain a worsted single yarn.

Then, two above-mentioned worsted single yarns are combined and 69
A twist of 0 times / meter was imparted and spinning was performed to obtain a 40th count spun yarn having a polylactic acid fiber content of 50%. Using this spun yarn for both the warp and weft, a plain woven fabric 2 of polylactic acid fiber / wool blend was produced by a conventional method.

Further, using a device as shown in FIG. 1, the cotton roving (1) is fed to the draft zone (5) of the spinning machine which comprises the back roller (2), the middle roller (3) and the front roller (4). ), And at the same time, the plain weave 1
The polylactic acid fiber used at the time of not being cut is supplied as a 75d / 24f polylactic acid fiber filament (6) immediately before the front roller (4), and then twisted to form a polylactic acid fiber filament ( In 6), a core yarn having a sheath of cotton yarn was obtained. At this time, the core (polylactic acid fiber filament) was 28% by weight, and the sheath (cotton yarn) was 78% by weight. This core yarn was used for both the background and the background, and a plain woven fabric 3 of polylactic acid fiber / cotton blend was manufactured by a conventional method.

The obtained flat fiber 1, plain woven fabric 2, plain woven fabric 3
The specific gravity of the polylactic acid fiber contained in these is 1.
27 and other fibers (polyester 1.38, cotton 1.54)
Since it is smaller than the above, it is lightweight, and the strength of the above polylactic acid fiber is 3.8 to 5.5 g / d, which is equivalent to that of nylon and polyester, but the Young's modulus of the fiber is 400 to 6
00 kg / mm ² and polyester 1,200 kg /
less than mm ^2, and substantially the same extent as 300 kg / mm ² nylon has a Drave of nylon par,
It was excellent in touch and had a sense of volume. Garments manufactured using these plain fabrics can be easily disposed of by landfill or incineration when discarded after use.
It was suitable for environmental protection.

[0038]

EFFECT OF THE INVENTION The mixed yarn containing the polylactic acid fiber of the present invention has basic properties such as washing resistance originally possessed by the synthetic fiber material described at the beginning, and when it is used for clothes etc., it is landfilled after use. In any of the incineration treatments, it is possible to carry out a treatment suitable for the environment, and it is possible to completely eliminate the drawbacks of the conventional spun yarn mixed with synthetic fiber and described in the beginning.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a core yarn manufacturing method.

[Explanation of symbols] 1 roving 2 back rollers 3 middle roller 4 front roller 5 Draft zone 6 Polylactic acid fiber filament

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-9-111566 (JP, A) JP-A-7-118922 (JP, A) JP-A-8-283392 (JP, A) JP-A-10- 102337 (JP, A) JP 9-324329 (JP, A) JP 9-209222 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D02G 3/00-3 / 04 D01F 6/62

Claims (3)

(57) [Claims] 1. A blended yarn comprising biodegradable fibers and natural fibers such as cotton, silk and wool, wherein the biodegradable fibers have a tensile strength of 2.0 g / d or more, a breaking elongation of 100% or less, and an optical fiber. A biodegradable spun yarn comprising staple fiber of polylactic acid fiber having a purity of 98% or more. 2. A composite spun yarn comprising biodegradable fibers and natural fibers such as cotton, silk and wool, wherein the biodegradable fibers have a tensile strength of 2.0 g / d or more and a breaking elongation of 100% or less. A biodegradable composite spun yarn comprising a polylactic acid fiber filament having an optical purity of 98% or more. 3. A polylactic acid fiber mixing ratio of 20 wt% or more, and claim 1 and less than 80 wt%
Is a spun yarn containing biodegradability according to 2.