JP3434628B2 - Polylactic acid-based long-fiber nonwoven fabric and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a long-fiber nonwoven fabric having degradability in a natural environment and a method for producing the same. More specifically, it relates to a degradable long-fiber nonwoven fabric having excellent flexibility obtained by using a polylactic acid-based polymer under specific conditions, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a non-woven fabric having degradability, for example, a non-woven fabric made of cotton, hemp, wool, rayon, chitin, alginic acid or the like is known as a biodegradable non-woven fabric derived from natural fibers or recycled fibers. .

However, since these biodegradable non-woven fabrics are generally hydrophilic and water-absorbing, they require hydrophobicity and low water-absorption like a top sheet of a disposable diaper, and require a dry feeling when wet. It is not suitable for the intended use. Further, the strength and dimensional stability of these non-woven fabrics are remarkably deteriorated in a wet environment, and there has been a limit in their development as general industrial material applications. Further, since these nonwoven fabrics are non-thermoplastic, they have no thermoformability and are inferior in processability.

Therefore, in recent years, research and development on biodegradable fibers and biodegradable nonwoven fabrics by a melt spinning method using a thermoplastic and hydrophobic biodegradable polymer have become popular. For example, a group of polymers collectively referred to as aliphatic polyesters are of particular interest because of their biodegradability. Specifically, poly-β-hydroxyalkanoates represented by microbial polyesters, poly-ω-hydroxyalkanoates represented by polycaprolactone, for example, polycondensates of glycols and dicarboxylic acids such as polybutylene succinate. A polyalkylene dicarboxylate or a copolymer thereof. Among them, poly-α represented by poly-L-lactic acid
With respect to oxyacids, recently, as a new polymerization method capable of efficiently producing a polymer having a high degree of polymerization has been developed, various studies have been made on its formation into fibers and non-woven fabrics. In particular, polylactic acid has a relatively high melting point among the above-mentioned aliphatic polyesters, and since the nonwoven fabric is useful in applications requiring heat resistance, it is expected that the polylactic acid nonwoven fabric will be put to practical use.

As a non-woven fabric using polylactic acid, Japanese Unexamined Patent Publication (Kokai) No. 7-126970 discloses a short fiber non-woven fabric containing polylactic acid as a main component, and is useful for producing a polylactic acid short fiber non-woven fabric. Polylactic acid short fiber
-212511. However, such a short-fiber non-woven fabric requires a large number of production steps from melt spinning of fibers to non-woven fabric, and thus there is a limit in reducing the production cost.

On the other hand, a long-fiber non-woven fabric produced by using polylactic acid by a so-called spunbond method, in which a yarn is extruded by a melt extrusion method to deposit a web on a screen, is disclosed in JP-A-7-48769. Kaihei 6-2
64343, International Nonwovens Journal,
Vol. 7, No. 2, p. 69 (1995) and EP-A-0 637 641 (A1). However, JP-A-7-48769 only suggests that a non-woven fabric can be produced from a polylactic acid polymer by a spunbond method, and the specific production method and the physical properties of the obtained non-woven fabric are not described. No description is given. Further, Japanese Patent Laid-Open No. 6-264343 relates to a biodegradable agricultural fiber assembly, but there is no detailed description of the take-up speed or other important production conditions, and the physical properties of the resulting nonwoven fabric are unknown. is there. Also, Internatio
nal Nonwovens Journal, Vol. 7, No. 2, p. 69 (199
In 5 years), only a plate-like hard and brittle polylactic acid spunbonded nonwoven fabric is obtained. Furthermore, European Patent Publication 06
No. 37641 (A1) has not obtained a polylactic acid spunbonded nonwoven fabric which is flexible and has excellent mechanical strength as in the present invention.

[0007]

As described above, the non-woven fabric using polylactic acid has decomposability and generally has a high melting point as compared with other aliphatic polyesters, so that it has the usefulness that it is also excellent in heat resistance. However, on the other hand, although the polylactic acid resin itself has good crystallinity, the above-mentioned International Nonwovens
As is clear from Journal, Vol. 7, No. 2, p. 69 (1995), the crystallization rate is slow under normal spinning conditions,
Since the spun and cooled yarn has a sticky feeling even during the web deposition process, the long fibers that make up the web are bonded at the crossing points, and as a result, only a nonwoven fabric lacking flexibility is obtained. . Further, for example, when a short-fiber non-woven web made of polylactic acid is moderately bonded so as not to impair flexibility, fluffing occurs or mechanical strength is poor and it becomes unusable for practical use.

The present invention solves such a problem, and is a polylactic acid-based length which has decomposability in a natural environment and has excellent flexibility while maintaining mechanical strength for practical use. It is intended to provide a fibrous nonwoven fabric.

[0009]

In order to solve the above problems, the present invention has the following structures. 1. Temperature 190 according to ASTM-D-1238 (E)
Melt flow rate value measured at 0 ° C is 20 to 100 g /
10 minutes polylactic acid based polymer by spunbond method
Long fibers pulled and thinned at a take-up speed of 3500 to 6000 m / min
The polylactic acid-based polymer is composed of poly (D-
Lactic acid), poly (L- lactic acid), and D- lactate and L- lactic acid
Copolymer of D-lactic acid and hydroxycarboxylic acid
Copolymerization of polymer with L-lactic acid and hydroxycarboxylic acid
Among polymers selected from the group of body and body, melting point is 100 ° C or higher
A polymer or a blend thereof,
Fiber is formed of one component of the polylactic acid-based polymer,
Note that the constituent long fibers are partially thermocompressed.
A characteristic polylactic acid-based long-fiber non-woven fabric.

2. According to ASTM-D-1238 (E)
The melt flow rate value measured at a temperature of 190 ° C is 20
A polylactic acid-based polymer having an amount of ˜100 g / 10 minutes,
Poly (D-lactic acid), poly (L-lactic acid), D-lactic acid
Copolymer with L-lactic acid, D-lactic acid and hydroxycarbohydrate
Copolymer with acid, L-lactic acid and hydroxycarboxylic acid
And a copolymer selected from the group of copolymers with
Any polymer or blends of those with a temperature above 00 ° C
When the melting point of this polymer is Tm ° C,
Melt at a temperature of (Tm + 15) ° C to (Tm + 50) ° C
Discharge from the spinneret, and use this suction yarn with a suction device.
After pulling and thinning at a take-up speed of 0 to 6000 m / min, transfer
A web is formed by depositing while opening the fiber on the dynamic collection surface.
Then, the web was applied to the polymer using a partial thermocompression bonding apparatus.
Partial thermocompression bonding at a temperature lower than the melting point by 10 ° C or more
A method for producing a polylactic acid-based long-fiber non-woven fabric, comprising:

With the above-mentioned structure, the non-woven fabric of the present invention retains its form as a non-woven fabric because the polylactic acid-based long fibers are partially bonded by thermocompression without bonding at the crossing points. Contrary to the hard and brittle characteristics of the polylactic acid-based nonwoven fabric, it has excellent flexibility while maintaining mechanical strength that can be put to practical use. Moreover,
Since the polylactic acid-based long fibers are used as the constituent fibers, the nonwoven fabric of the present invention can be decomposed in a natural environment.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The long fibers applied to the present invention are made of a polylactic acid polymer. Polylactic acid polymer
Is poly (D-lactic acid), poly (L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, a copolymer of D-lactic acid and hydroxycarboxylic acid, and L-lactic acid. Among polymers selected from the group of copolymers with hydroxycarboxylic acids, polymers having a melting point of 100 ° C. or higher or blends thereof .
Consists of

Poly (D-lactic acid) as a polylactic acid polymer
Especially when a homopolymer such as poly (L-lactic acid) is used, it is desirable to add a plasticizer for the purpose of improving the spinnability in the spinning step and improving the flexibility of the obtained fiber and nonwoven fabric. . As the plasticizer in this case, triacetin, lactic acid oligomer, dioctyl phthalate and the like are used, and the addition amount thereof is 1 to 30% by weight, preferably 5 to 20% by weight.

In the present invention, it is necessary for the constituent fibers of the nonwoven fabric to have a melting point of 100 ° C. or higher from the viewpoint of the heat resistance of the resulting nonwoven fabric. Therefore, the polylactic acid-based polymer forming the nonwoven fabric is required . It is important that the melting point is 100 ° C. or higher. That is, the melting point of poly (L-lactic acid) or poly (D-lactic acid), which is a homopolymer of polylactic acid, is about 180 ° C., but when the copolymer is used as the polylactic acid-based polymer, the melting point of the copolymer is It is important to determine the copolymerization ratio of the monomer components so that the temperature is 100 ° C. or higher. When the copolymerization amount ratio of L-lactic acid or D-lactic acid in the copolymer is lower than a specific range, the melting point of the polylactic acid-based polymer and thus the melting point of the constituent fibers of the nonwoven fabric becomes less than 100 ° C., or the polymer is amorphous. Since it becomes a water-soluble polymer, the cooling property during spinning is lowered, and the heat resistance of the resulting nonwoven fabric is impaired, limiting its intended use.
It will be .

The hydroxycarboxylic acid in the case of a copolymer of lactic acid and hydroxycarboxylic acid includes glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid and hydroxyoctanoic acid. Among these, hydroxycaproic acid or glycolic acid is particularly preferable from the viewpoints of decomposition performance and low cost.

Further, the polylactic acid polymer definitive to the present invention
In addition to using the above polylactic acid-based polymer alone,
Two or more kinds of polylactic acid-based polymers may be mixed and used as a blend. When used as a blended body, it is advisable to appropriately set the conditions such as mixing type and mixing amount in consideration of spinnability and the like.

The polymers applied in the present invention may each contain, for example, a matting agent, a pigment,
Various additives such as a crystal nucleating agent may be added within a range that does not impair the effects of the present invention. In particular, a crystal nucleating agent such as talc, boron nitride, calcium carbonate, and titanium oxide is contained in a range of 0.1 to 3% by weight in order to prevent fusion (blocking) between yarns in the spinning / cooling process. It is useful when used in.

The long fiber applied to the present invention has a solid cross section,
Although any other fiber cross-sectional shape can be adopted,
In particular, it is preferably either a hollow cross section or a modified cross section .

When the fiber cross section of the long fiber has a hollow cross section as shown in FIG. 1, it is possible to impart excellent decomposition performance to the obtained nonwoven fabric. This is because microorganisms such as erosion starting from the outer peripheral portion and water penetrate into the hollow portion 1 to form a penetrating hole, and as a result, the surface area per unit weight of the polymer is increased, so that the decomposition rate by microorganisms is accelerated. Because. Further, in the hollow cross-section fiber, since the weight of the polymer passing through the cooling region per unit time during spinning is small, and the air containing a small specific heat is contained inside, it is possible to improve the cooling property of the spun yarn. It has a remarkable effect.

Even when the fiber cross section of the long fiber has a polygonal modified cross section or a flat modified cross section as shown in FIGS. 2 and 3, the spinnability of the spun yarn during spinning is improved and the fiber is opened. In addition to having excellent properties, the decomposition performance of the obtained nonwoven fabric is also improved. This is because the surface area per unit weight of the polymer is large even in the modified cross-section fiber.

In the present invention, in addition to the above-mentioned cross section, for example, a triangular shape , a square shape, a hexagonal shape, a flat shape, a Y shape,
Various modified cross sections such as a T-shape may be used. The long-fiber nonwoven fabric of the present invention is one in which the web is partially thermocompressed without the constituent long-fibers being bonded to each other at the crossing points, and the sheet-like form having a non-woven structure is retained. That is, the non-woven fabric of the present invention has excellent flexibility because only the spot-shaped fused regions that are partially formed are adhered.

The single filament fineness of the constituent long fibers of the nonwoven fabric of the present invention is preferably 0.5 to 10 denier. If the single yarn fineness is less than 0.5 denier, single yarn cutting frequently occurs in the spinning and take-up steps, and the nonwoven fabric obtained tends to be inferior in strength as well as operability. On the other hand, if the single yarn fineness exceeds 10 denier, the spun yarn will not be sufficiently cooled, and
This is not preferable because the flexibility of the obtained nonwoven fabric is impaired.

The nonwoven fabric of the present invention is composed of long fibers satisfying the above-mentioned single yarn fineness and has a basis weight of 10 to 100 g.
It is preferably in the range of / m ² . Unit weight is 10g / m
^When it is less than ² , the texture and the mechanical strength are poor and it cannot be used practically. On the other hand, if the fabric weight exceeds 100 g / m ² , flexibility is impaired, which is not preferable.

The nonwoven fabric of the present invention preferably has a tensile strength of 8 kg / 5 cm width or more when converted to a basis weight of 100 g / m ² .
Here, the tensile strength means the average value of the tensile rupture strength in the warp direction and the weft direction when measured according to JIS-L-1096, and in the present invention, this is the basis weight 10.
The non-woven fabric obtained is evaluated in proportion to 0 g / m ² . If the tensile strength of the non-woven fabric is less than 8 kg / 5 cm width, it may not be practically usable because it has too low mechanical strength.

The nonwoven fabric of the present invention has a compression bending resistance per unit weight, which is an index of flexibility, of 5 g / (g / m ² ) or less. Here, the compression stiffness is obtained by bending a sample piece having a sample length of 10 cm and a sample width of 5 cm in the lateral direction into a cylindrical object, and compressing it at a compression rate of 5 cm / min in the axial direction,
A value obtained by dividing the obtained maximum load value (g) by the basis weight was found 5 times and averaged. A smaller value means more flexibility. In the present invention, since the web is partially thermocompression-bonded, the resulting nonwoven fabric has excellent flexibility and a compression stiffness of 5 g / (g / m ² ) or less. If the compression stiffness is more than 5 g / (g / m ² ), the texture of the non-woven fabric becomes hard and unsuitable for use in sanitary materials requiring flexibility.

Next, a method for producing the polylactic acid-based long-fiber nonwoven fabric of the present invention will be described. The long fiber non-woven fabric of the present invention,
It can be efficiently manufactured by a so-called spun bond method. That is, the melt flow rate value measured at a temperature of 190 ° C. according to ASTM-D-1238 (E) is 20.
When the melting point of this polymer is Tm ° C., it is melted at a spinning temperature in the range of (Tm + 15) ° C. to (Tm + 50) ° C., using the above-mentioned polylactic acid-based polymer composition of ˜100 g / 10 min. , After spinning through a spinneret having a desired fiber cross-section, and cooling the obtained spun yarn using a conventionally known cooling device such as horizontal spraying or annular spraying, a suction device such as an air sucker By using, to draw and thin to a target fineness with a high-speed air flow of 3500 to 6000 m / min, and subsequently to open the yarn group discharged from the suction device,
A web is obtained by spreading and depositing fibers on a moving depositing device such as a conveyor made of a screen. Then, using a partial thermocompression bonding device on the web formed on this moving deposition device,
A long-fiber nonwoven fabric can be obtained by partially performing thermocompression bonding at a temperature 10 ° C. or more lower than the melting point of the polymer having the lowest melting point among the above polymers.

The melt flow rate value (hereinafter referred to as MFR value) of the polylactic acid polymer composition applied in the present invention is, as described above, ASTM-D-1238 (E).
20 to 100 measured at 190 ° C. according to the method described in 1.
It is important that it is g / 10 minutes. MFR value is 20 g
If it is less than / 10 minutes, the melt viscosity is too high, resulting in inferior high-speed spinnability, and conversely, the MFR value is 100 g /
If it exceeds 10 minutes, the melt viscosity will be too low and the spinnability will be poor, making stable operation difficult.

In the present invention, during melt spinning, as described above, when the melting point of the polymer used is Tm ° C. (T
It must melt at a temperature in the range of m + 15) ° C to (Tm + 50) ° C. However, when a blend of two or more polylactic acid-based polymers is used, the melting point of the polymer having the highest melting point among the polymers constituting the blend is Tm ° C. If the spinning temperature is lower than (Tm + 15) ° C, the high-speed air flow will result in poor pulling and take-up properties, and conversely, (Tm + 50) ° C.
If it exceeds the above, not only the crystallization in the cooling process is delayed, fusion between filaments occurs and the openability is inferior, but also the thermal decomposition of the polymer itself proceeds, so a nonwoven fabric with a soft and uniform texture is formed. Hard to get.

In the present invention, when the spun yarn is pulled and thinned by using the suction device, the take-up speed is set to 35 as described above.
It is important to set it to 00 to 6000 m / min. The take-up speed of the suction device may be appropriately selected according to the MFR value of the polymer, but if the take-up speed is less than 3500 m / min, oriented crystallization of the polymer is not promoted and sticking occurs between the yarns, resulting in The resulting nonwoven fabric tends to be hard and inferior in mechanical strength. On the other hand, when the take-up speed exceeds 6000 m / min, the yarn breakage occurs, exceeding the towing limit, and stable operability is impaired.

In the present invention, the term "partial thermocompression bonding" of a web means that a point-like fused area is formed by embossing or ultrasonic welding. Specifically, the heated embossing roll and the surface are smooth. A method of forming a spot-shaped fused area between long fibers by passing a web between the long fibers is used.

More specifically, the partial thermocompression bonding has a specific area with respect to the total surface area of the web, that is, an area of 0.2 to 15 mm ² , and each thermocompression bonding area is round or elliptical. It is preferable to have a region having an arbitrary shape such as a die, a rhombus, a triangle, a T-shape, and a well, and its density, that is, the density of crimping points is 4 to 100 points / cm ² . If the density of crimping points is less than 4 points / cm ² , the mechanical strength and shape retention of the resulting nonwoven fabric are not improved, and conversely, if the density of crimping points exceeds 100 points / cm ² , the resulting nonwoven fabric is sparse Tend to be lost and the flexibility is impaired, which is not preferable. Further, the ratio of the area of the total thermocompression bonding area to the total surface area of the web, that is, the pressure bonding area ratio depends on the area of each pressure bonding point,
It should be 50%. When the pressure-bonding area ratio is less than 4%, the mechanical strength and shape retention of the resulting nonwoven fabric are not improved, and conversely, when the pressure-bonding area ratio exceeds 50%, the resulting nonwoven fabric becomes sparsely rigid and flexible. Which is not preferable.

As described above, the processing temperature for thermocompression bonding, that is, the surface temperature of the embossing roll, must be 10 ° C. or more lower than the melting point of the polymer used. However, the web to which thermocompression bonding is applied should be made of two or more kinds of polylactic acid.
Made from long fibers consisting of a blend of polymer
The lowest of the polymers that make up the blend,
Based on the melting point of a polymer with a high melting point,
The processing temperature must be 10 ° C lower than the melting point of
Absent. If this temperature is exceeded, not only will the polymer stick to the thermocompression bonding device, impairing operability, but also the texture of the non-woven fabric will become hard and a soft non-woven fabric will not be obtained.

Regarding the thermocompression bonding treatment, in addition to the method using the above-mentioned heated embossing roll, a high-frequency ultrasonic wave is applied on the pattern roll using an ultrasonic fusing device to form a dot pattern between the long fibers of the pattern portion. It is also possible to employ a method of forming a fusion zone. More specifically, the ultrasonic fusing device is a device including an ultrasonic oscillator having a frequency of about 20 kHz, which is usually called a horn, and a pattern roll having convex protrusions in a dot or band shape on the circumference. Is. The pattern roll is disposed below the ultrasonic oscillator, and the web can be partially heat-sealed by passing the web between the ultrasonic oscillator and the pattern roll. There may be one row or a plurality of rows of convex protrusions arranged on this pattern roll, and when the arrangement is a plurality of rows,
Either parallel or staggered arrangement may be used.

The partial thermocompression bonding process using the embossing roll or the ultrasonic fusing device may be a continuous process or a separate process. Which method is adopted depends on whether a non-woven fabric is used or not. It may be appropriately selected depending on the application.

[0035]

EXAMPLES The present invention will be specifically described below with reference to examples. The present invention is not limited to these examples.

In the examples, each physical property value was determined as follows. Melt flow rate value (g / 10 minutes); ASTM-D
It measured at the temperature of 190 degreeC according to the method as described in -1238 (E). -Melting point (° C); Differential scanning calorimeter D manufactured by Perkin Elma
Using SC-2 type, sample weight 5 mg, temperature rising rate 20
The temperature that gives the extreme value of the melting endothermic curve obtained by measuring as ° C / min was defined as the melting point (° C).・ Basis weight (g / m ² ); 10 cm long from the standard sample
After each 10 points of a 10 cm wide sample piece was prepared and allowed to reach equilibrium water content, the weight (g) of each sample piece was weighed, and the average value of the obtained values was converted per unit area to give a basis weight (g / m ² ).・ KGSM tensile strength (kg / 5cm width); JIS-L-
It was measured according to the strip method described in 1096. That is, 10 pieces each of a sample piece having a sample length of 10 cm and a sample width of 5 cm were prepared, and a constant speed extension type tensile tester (Tensilon UTM-4 manufactured by Toyo Baldwin Co., Ltd.) was used for each sample piece in the warp and weft directions of the nonwoven fabric. -1-100) was used to stretch at a tensile speed of 10 cm / min, and the obtained load value (k) at cutting was obtained.
The value obtained by converting the average value of (g / 5 cm width) into a basis weight of 100 g / m ² was defined as KGSM tensile strength (kg / 5 cm width).・ Compressive bending resistance (g / (g / m ² )) of non-woven fabric; a total of 5 sample pieces with a sample length of 10 cm and a sample width of 5 cm were prepared, and each sample piece was bent laterally to form a cylindrical object. Each of which was joined at its end was used as a sample for measuring compression stiffness. Then
Constant velocity extension type tensile tester (Tensilon UTM-manufactured by Toyo Baldwin Co., Ltd.)
4-1-100) was used for compression at a compression speed of 5 cm / min, and the average of values obtained by dividing the maximum load value (g) obtained by the basis weight was compression stiffness (g / (g / m ² )). And Therefore,
The smaller the value of this compression stiffness is, the better the flexibility is.・ Biodegradability: The non-woven fabric is embedded in an aged compost maintained at about 58 ° C and taken out after 3 months. When the non-woven fabric does not retain its morphology, or even if it retains its morphology, the tensile strength is 50 against the strong initial value before burial
If the strength is less than 50%, the biodegradability is considered to be good, and if the strength exceeds 50% of the initial strength before embedding, the biodegradability is evaluated to be poor.

Example 1 L- having a melting point of 168 ° C. and an MFR value of 20 g / 10 minutes
Lactic acid / hydroxycaproic acid = 90/10 mol% L-
A lactic acid-hydroxycaproic acid copolymer was used, and the pore size was 0.
Spinning temperature 1 from a round spinneret with 5 mm and 48 holes
Melt spinning was performed at 95 ° C. and a single hole discharge rate of 1.35 g / min. Next, the spun yarn is cooled with a cooling air flow having a temperature of 20 ° C., and subsequently, with an air sucker, a take-up speed of 3500 m.
The web was formed by picking up the fiber at a speed of 1 / min, opening the fiber, and depositing it on the collecting surface of the moving conveyor. Next, this web was passed through a partial thermocompression bonding apparatus consisting of embossing rolls, the roll temperature was set to a temperature 20 ° C lower than the melting point of the polymer (148 ° C), and the heating was partially performed under the condition that the compression bonding area ratio was 7.6%. By pressure bonding, a continuous fiber nonwoven fabric having a unit weight of 30 g / m ² and having a single fiber fineness of 3.5 denier was obtained. Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

Example 2 L- in L-lactic acid-hydroxycaproic acid copolymer
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the copolymerization ratio of lactic acid and hydroxycaproic acid, the spinning temperature, and the embossing temperature were changed as shown in Table 1. Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

Example 3 and Example 4 Example 3 and Example 4 were carried out except that the copolymer of L-lactic acid and D-lactic acid was used and the copolymerization amount ratio, spinning temperature and embossing temperature were changed as shown in Table 1. A long fiber nonwoven fabric was obtained in the same manner as in Example 1. Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

Example 5 A long-fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the spinning temperature and the embossing temperature were changed as shown in Table 1 using a poly (L-lactic acid) polymer. Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

Example 6 A long-fiber nonwoven fabric was obtained in the same manner as in Example 5 except that a composition obtained by adding 1% by weight of talc as a crystal nucleating agent to a poly (L-lactic acid) polymer was used. Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

Example 7 The single hole discharge rate was 5.78 g / min, and the take-up speed was 4500.
A long fiber nonwoven fabric made of long fibers having a single yarn fineness of 5.4 denier was obtained in the same manner as in Example 1 except that m / min was set. Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

[0043]

[Table 1]

As is clear from Table 1, all the long-fiber nonwoven fabrics obtained in Examples 1 to 7 have sufficient strength to withstand practical use, and have compression stiffness of 5 g / (g). /
It was less than m ² ) and was excellent in flexibility. Also,
These non-woven fabrics also had very good biodegradability, and when they were taken out after being embedded in compost, all the non-woven fabrics had a large weight loss rate, a large morphological change, and a markedly low strength retention rate.

Comparative Example 1 and Comparative Example 2 Example 1 except that the take-up speed was changed as shown in Table 2.
A long fiber nonwoven fabric was obtained in the same manner as in. Table 2 shows the production conditions and operability.

Comparative Example 3 and Comparative Example 4 Except that the MFR value of the polymer was changed as shown in Table 2,
A long fiber nonwoven fabric was obtained in the same manner as in Example 1. Table 2 shows the production conditions and operability. Comparative Example 5 and Comparative Example 6 Example 1 except that the spinning temperature was changed as shown in Table 2.
A long fiber nonwoven fabric was obtained in the same manner as in. Table 2 shows the production conditions and operability.

Comparative Example 7 A long fiber nonwoven fabric made of long fibers was obtained in the same manner as in Example 4 except that the embossing temperature during thermocompression bonding was 105 ° C. Table 2 shows manufacturing conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

[0048]

[Table 2]

On the other hand, as is clear from Table 2, Comparative Example 1
In the above, since the take-up speed was lower than 3500 m / min , fusion between filaments occurred, the openability became poor, and a sheet with good texture could not be obtained.

In Comparative Example 2, the take-up speed is 6000.
Since it is higher than m / min, it has poor spinnability due to high-speed air flow,
Thread breakage occurred frequently and it could not be made into a sheet. In Comparative Example 3, since the MFR value exceeds 100 g / 10 minutes,
The spinnability due to high-speed air flow was inferior, and yarn breakage occurred frequently, making it impossible to form a sheet.

In Comparative Example 4, the MFR value was 20 g /
Since it was less than 10 minutes , the drawability and take-up property by the high-speed air flow were inferior, and the operability was impaired. In Comparative Example 5, when the spinning temperature was Tm, the melting point of the polymer was (Tm
Since the temperature is lower than +15) ° C, the drawability and take-up property by the high-speed air flow are inferior, and the operability is impaired.

In Comparative Example 6, since the spinning temperature was higher than (Tm + 50) ° C. when the melting point of the polymer was Tm, crystallization was slowed during the cooling process and thermal decomposition of the polymer proceeded. However, fusion between filaments occurred, the openability became poor, and a sheet with a good texture could not be obtained.

In Comparative Example 7, the embossing temperature was only 7 ° C. lower than the melting point of the polymer, so that the obtained nonwoven fabric lacked flexibility and texture.

[0054]

EFFECTS OF THE INVENTION According to the present invention, since the polylactic acid-based long fibers are partially thermocompressed to retain the shape of the nonwoven fabric, they can be decomposed in a natural environment and at the same time,
Contrary to the characteristic of polylactic acid resin itself that it is hard and brittle,
It is possible to provide a nonwoven fabric having excellent flexibility while maintaining mechanical strength that can be put to practical use.

Therefore, the non-woven fabric of the present invention is, for example, a material for sanitary materials such as diapers and sanitary products, disposable hand towels, wiping cloths, base cloths for paps, household or commercial dust collection bags or filters, Agricultural and horticultural materials such as vegetation auxiliary sheets and plant containers, civil engineering materials such as horizontal or vertical drain sheets, and other applications that require degradability and flexibility such as life-related materials such as waste treatment materials It can be effectively applied in, and is beneficial from the viewpoint of protecting the natural environment.

[Brief description of drawings]

FIG. 1 is a model view of a fiber cross section of a hollow cross section long fiber showing an example of a long fiber constituting a nonwoven fabric of the present invention.

FIG. 2 is a model view of a fiber cross section of a modified cross-section long fiber showing another example of the long fiber constituting the nonwoven fabric of the present invention.

FIG. 3 is a model view of a fiber cross section of a modified cross section long fiber showing still another example of the long fiber constituting the nonwoven fabric of the present invention.

[Explanation of symbols]

1 hollow part

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-133511 (JP, A) JP-A-7-34369 (JP, A) JP-A-7-48769 (JP, A) JP-A-8- 35121 (JP, A) JP 9-13256 (JP, A) JP 7-125128 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D04H 1 / 00-18 / 00 D01F 1/00-13/04

Claims (8)

(57) [Claims] 1. A melt flow rate value measured according to ASTM-D-1238 (E) at a temperature of 190 ° C. is 20 to.
The polylactic acid-based polymer, which is 100 g / 10 min, is composed of long fibers drawn and thinned by a spunbond method at a take-up speed of 3500 to 6000 m / min.
Poly (D-lactic acid), poly (L-lactic acid), copolymer of D-lactic acid and L-lactic acid, copolymer of D-lactic acid and hydroxycarboxylic acid, L-lactic acid and hydroxycarboxylic acid Among polymers selected from the group of copolymers with acids, the melting point is 1
A polymer having a temperature of 00 ° C. or higher or a blend thereof, wherein the long fibers are formed of one component of the polylactic acid-based polymer, and the constituent long fibers are partially thermocompression bonded. Polylactic acid type long fiber non-woven fabric. 2. The polylactic acid-based long-fiber nonwoven fabric according to claim 1, wherein a crystal nucleating agent is added to the polylactic acid-based polymer. 3. The polylactic acid-based long-fiber nonwoven fabric according to claim 1, wherein the fiber cross section of the constituent long fiber is a solid cross section or a hollow cross section. 4. The polylactic acid-based long fiber non-woven fabric according to claim 1, wherein the fiber cross section of the constituent long fibers is a polygonal or flat irregular cross section. 5. A single yarn fineness of the constituent long fibers is 0.5 to 10 denier, and a basis weight of the nonwoven fabric is 10 to 100 g / m.
The polylactic acid-based long-fiber non-woven fabric according to any one of claims 1 to 4, characterized in that it is ² . 6. The polylactic acid-based long-fiber nonwoven fabric according to any one of claims 1 to 5, wherein the tensile strength of the nonwoven fabric when converted to a basis weight of 100 g / m ² is 8 kg / 5 cm width or more. . 7. The compression bending resistance of the nonwoven fabric per unit weight is 5 g.
The polylactic acid-based long-fiber non-woven fabric according to any one of claims 1 to 6, which has a ratio of / (g / m ² ) or less. 8. A melt flow rate value measured according to ASTM-D-1238 (E) at a temperature of 190 ° C. is 20 to.
A polylactic acid-based polymer having a weight of 100 g / 10 minutes, wherein poly (D-lactic acid), poly (L-lactic acid), D-lactic acid and L
-A polymer selected from the group consisting of a copolymer of lactic acid, a copolymer of D-lactic acid and hydroxycarboxylic acid, and a copolymer of L-lactic acid and hydroxycarboxylic acid, having a melting point of 10
Any one component of the polymer having a temperature of 0 ° C. or higher or a blend thereof is melted at a temperature of (Tm + 15) ° C. to (Tm + 50) ° C. when the melting point of the polymer is Tm ° C. and discharged from the die, This discharge thread is 350
After being drawn and thinned at a take-up speed of 0 to 6000 m / min, a web was formed by depositing while opening the fibers on the movable collection surface, and the web was formed from the melting point of the polymer by using a partial thermocompression bonding device. Also, a method for producing a polylactic acid-based long-fiber non-woven fabric, which comprises partially thermocompressing at a temperature lower than 10 ° C.