JPH0995851A - Nonwoven fabric of polylactate-based filament and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new multifunctional polylactate-based filament nonwoven fabric decomposable in natural environment, having a certain flexibility while keeping excellent mechanical strength and exhibiting air-shielding property and water-shielding property. SOLUTION: This polylactate-based filament nonwoven fabric is produced by using a polylactate-based polymer having a melt flow rate of 1-100g/10min measured in conformity to ASTM D-1238(E) at 190 deg.C, melting the polymer at a temperature between (Tm+15) deg.C and (Tm+50) deg.C (Tm is the melting point of the polymer), extruding the molten polymer through a spinneret, thinning down the extruded fiber by drawing with a sucking apparatus at a take-up speed of 1,000-6,000m/min, depositing the fibers on a moving collection face under opening to form a web and heat-bonding one or both surfaces of the web as a whole with a full-face heat-bonding apparatus at <=(Tm+5) deg.C under a linear pressure of a roll of >=0.01kg/cm.

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 novel multifunctional degradable long-fiber nonwoven fabric 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 Nonwoven fabrics made of thermoplastic polymers such as polyethylene, polypropylene, polyester and polyamide have been conventionally known as materials for medical / sanitary materials, general life-related materials and some industrial materials. These non-woven fabrics are not self-degradable because they are composed of the above-mentioned polymers that are chemically stable under normal natural environment, and therefore,
In the single-use application, the fact is that they are treated by incineration or landfill. Regarding incineration,
This is a problem from the viewpoint of protection of the natural and living environment, such as a large amount of cost being required for plant construction and installation of pollution control equipment, and waste gas causing pollution. On the other hand, with respect to landfill, there is a problem in that the material is chemically stable in a normal natural environment as described above, so that it is kept in the original state for a long time in the soil. In order to solve these problems, various non-woven fabrics made of degradable materials have been developed.

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 non-woven fabric derived from natural fibers or recycled fibers.

However, since these degradable non-woven fabrics are generally hydrophilic and water-absorbing, they need to have water-blocking properties and low water-absorption properties such as the top sheet of disposable diapers, and a dry feeling when wet is required. It is not suitable for various uses. Also,
These non-woven fabrics are markedly deteriorated in strength and dimensional stability in a wet environment, and there is a limit in their development as general industrial material applications. Furthermore, since these nonwoven fabrics are non-thermoplastic, they have no thermoformability and are inferior in workability.

As degradable nonwoven fabrics for solving these problems, various degradable nonwoven fabrics by a melt spinning method using a thermoplastic polymer having biodegradability, for example, aliphatic polyester have been reported. And as such an aliphatic polyester, specifically, poly-β-hydroxyalkanoate represented by microbial polyester, poly-ω-hydroxyalkanoate represented by polycaprolactone, for example, polybutylene succinate. Polyalkylene dicarboxylates composed of such polycondensates of glycols and dicarboxylic acids or copolymers thereof are known.

However, these biodegradable polymers generally have a low melting point and a low crystallization temperature and a low crystallization rate, so that the spinnability of the spun yarn is poor and the spinnability is poor. In the cooling, traction thinning, collection, and deposition processes, the filaments cannot be sufficiently opened due to adhesion between the filaments, and the filaments are extruded by the melt extrusion method to deposit the web on the screen. There is a problem that it is difficult to apply to the production of nonwoven fabric by the spunbond method. Even if a spunbonded nonwoven fabric made of these polymers is obtained, the melting point of the nonwoven fabric limits the use environment. Therefore, spunbonded nonwoven fabric using polylactic acid having a relatively high melting point among the above aliphatic polyesters is considered to be useful, and its practical application is expected.

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, regarding the polylactic acid long fiber non-woven fabric by the spunbond method, JP-A-7-48769, JP-A-6-264343 and International Nonwoven are available.
s Journal, Vol. 7, No. 2, p. 69 (1995) and European Patent Publication No. 0637641 (A1). However, in JP-A-7-48769,
It only suggests that a non-woven fabric can be produced from a polylactic acid polymer by a spunbond method, and does not describe any specific manufacturing method or physical properties of the obtained non-woven fabric. 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, Inte
According to rnational Nonwovens Journal, Vol. 7, No. 2, p. 69 (1995), only a plate-like hard and brittle polylactic acid spunbonded nonwoven fabric is obtained. Further, even in European Patent Publication No. 0637641 (A1), a polylactic acid spunbonded nonwoven fabric excellent in mechanical strength as in the present invention has not been obtained.

[0009]

DISCLOSURE OF THE INVENTION The present invention is a degradable spunbonded nonwoven fabric made of a polylactic acid type polymer which can be used even in the field where heat resistance is required, and has excellent mechanical strength. At the same time, it is an object of the present invention to provide a novel multifunctional polylactic acid-based long-fiber non-woven fabric having a certain degree of flexibility, and also having air permeability and water impermeability.

[0010]

In order to solve the above problems, the present invention has the following structures. 1. At least one surface of a web composed of long fibers made of a polylactic acid polymer is thermocompression bonded over the entire surface.

2. The melt flow rate value measured at a temperature of 190 ° C. according to ASTM-D-1238 (E) is 1 to
When the melting point of this polylactic acid-based polymer is 100 g / 10 minutes and the melting point of this polymer is Tm ° C., (Tm + 15) ° C. to (T
m + 50) ° C., melted and discharged from the spinneret, the discharged yarn is drawn and thinned by a suction device at a take-up speed of 1000 to 6000 m / min, and then spread while being spread on the movable collecting surface. To form a web, and using at least one side of the web with a thermocompression bonding apparatus for the entire surface, when the melting point of the polymer is Tm ° C., the linear pressure of the roll is 0.01 kg at a temperature of (Tm + 5) ° C. or less. / Cm or more and thermocompression-bonded over the entire surface to obtain a polylactic acid-based long-fiber nonwoven fabric.

As described above, the non-woven fabric of the present invention retains its form as a non-woven fabric by thermocompression-bonding at least one side of the web formed of long fibers, so that a non-woven structure is formed inside. It has a structure in which only the surface is formed into a film while being held. That is, the nonwoven fabric of the present invention has excellent mechanical strength while exhibiting air-permeable and water-impervious properties depending on the shape of the film on the surface, but at the same time, it is a perfect film due to the presence of a non-woven structure inside. It is a new multifunctional non-woven fabric that has superior flexibility compared to sheet-shaped sheets. Moreover, since the polylactic acid-based long fiber is used as the constituent fiber, the nonwoven fabric of the present invention can be decomposed in a natural environment.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The long fibers applied to the present invention are made of a polylactic acid polymer. Examples of the polylactic acid-based polymer include poly (D-lactic acid), poly (L-lactic acid), D
-Melting point of polymers selected from the group consisting of a copolymer of lactic acid and L-lactic acid, a copolymer of D-lactic acid and hydroxycarboxylic acid, and a copolymer of L-lactic acid and hydroxycarboxylic acid Is preferably a polymer having a temperature of 100 ° C. or higher or a blend thereof.

Poly (D-lactic acid) as a polylactic acid type 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 preferable that the constituent fibers of the non-woven fabric have a melting point of 100 ° C. or higher from the viewpoint of the heat resistance of the obtained non-woven fabric. Therefore, the polylactic acid-based polymer forming the non-woven fabric has a melting point. It is important that the temperature 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 at the time of spinning is lowered, and the heat resistance of the obtained nonwoven fabric is impaired, so that its use is restricted, which is not preferable.

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.

In the present invention, the above polylactic acid-based polymer may be used alone, or 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 above-mentioned 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 as long as the effects of the present invention are not impaired. 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 any one of a hollow cross section, a modified cross section, a core-sheath composite cross section, and a split type composite cross section.

When the fiber cross section of the long fiber has a hollow cross section as shown in FIG. 1, excellent decomposition performance can be imparted 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 inside contains air having a small specific heat, the cooling property of the spun yarn is improved. Exerts a remarkable effect on.

Even when the transverse cross section of the long fiber has a polygonal irregular cross section or a flat irregular 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.

When the fiber cross section of the long fiber has a core-sheath composite cross section, it is formed from two components which are a polylactic acid-based polymer or a blend of two or more polylactic acid-based polymers. It is important to place the component with the higher melting point (hereinafter referred to as the high melting point component) in the core and the component with the lower melting point (hereinafter referred to as the low melting point component) in the sheath. In this case, it is important that the difference in melting point between both components is at least 5 ° C or higher, preferably 10 ° C or higher, more preferably 20 ° C or higher. However, when a blend of two or more polylactic acid-based polymers is used as a core component and / or a sheath component, the melting point of the polymer having the lowest melting point among the polymers constituting the blend is used as the core component. As the sheath component, the melting point difference is judged based on the melting point of the polymer having the highest melting point among the polymers constituting the blend. As a result, when the web is entirely thermocompressed, it can be thermocompressed at a temperature near the melting point of the sheath component having a relatively low melting point, and the high melting point component of the core is not melted, and the flexibility is high. Can be improved.

When the fiber cross section of the long fiber is a split type composite cross section, the resulting non-woven fabric can exhibit excellent effects on decomposability and flexibility. Here, the split-type composite cross section is composed of two components that are a polylactic acid-based polymer or a blend of two or more polylactic acid-based polymers, and the two components have a form in which they are divided from each other, and both are Is a fiber cross section which is continuous in the fiber axis direction and is exposed on the fiber surface, and specific examples include the cross sections shown in FIGS. 4 to 6. More specifically, FIG. 4 is a cross section in which both components radially divide from each other, and FIG.
Is a cross section in which the points are projected symmetrically with respect to the low melting point component 3. According to these fiber cross-sectional shapes, the decomposition of the fiber itself is promoted by the decomposition of a part of the component having a higher decomposition performance (usually the low melting point component 3), so that the decomposability of the resulting nonwoven fabric is improved. Can be improved.
Further, in FIG. 6, since the hollow portion 1 is provided in the cross section shown in FIG. 4, the decomposability, the cooling property of the spun yarn, and the fiber opening property can be further improved. Also in the split type composite cross section, when the web is entirely thermocompressed, the high melting point component 2 may be melted because the heat fusion can be performed at a temperature near the melting point of the low melting point component 3. Therefore, the flexibility can be improved.

In the present invention, in addition to the above-mentioned cross section, for example, a round composite cross section, a triangular shape, a square shape, a hexagonal shape,
It may be a flat type, a Y-shaped type, a T-shaped type, or any other type of complex composite cross section.

The non-woven fabric of the present invention retains its form as a non-woven fabric by thermocompressing at least one side of the web formed of long fibers, and only the surface is retained while retaining the non-woven structure inside. Has a filmed structure. Therefore, the non-woven fabric of the present invention has excellent mechanical strength while exhibiting air-permeable and water-impervious properties depending on the shape of the film on the surface, and at the same time has a non-woven structure inside it, compared to a perfect film-like sheet. It is also possible to provide excellent flexibility. Further, the nonwoven fabric of the present invention, since the filmed surface portion and the inside of the non-woven structure are continuously joined, a better delamination strength than that obtained by simply laminating the film on the surface of the non-woven web. Is to have.

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 cooling property of the spun yarn becomes insufficient and the flexibility of the obtained nonwoven fabric decreases, which is not preferable.

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 1000.
It is preferably in the range of g / m ² . Unit weight is 10g /
When it is less than m ² , the texture and the mechanical strength are poor and it cannot be put to practical use. Conversely, the basis weight is 1000 g / m ²
When it exceeds, the flexibility is lowered and it is not preferable.

The nonwoven fabric of the present invention preferably has a tensile strength of 3 kg / 5 cm width or more when converted to a basis weight of 100 g / m ² . Here, the tensile strength means JIS-L-1096.
Means the average value of the tensile breaking strength in the warp direction and the weft direction, and in the present invention, the non-woven fabric obtained is evaluated in proportion to a basis weight of 100 g / m ² . If the tensile strength of the non-woven fabric is less than 3 kg / 5 cm width, the mechanical strength is so low that it may not be practical.

The nonwoven fabric of the present invention preferably has a compression stiffness per unit weight, which is an index of flexibility, of 10 g / (g / m ² ) or less. Here, the compressive stiffness is 10 for the sample length.
cm, sample width 5 cm, the sample was bent in the lateral direction to form a cylindrical body, and the compression speed was 5 cm / cm in the axial direction.
It is a value obtained by compressing in minutes, dividing the obtained maximum load value (g) by the basis weight and averaging the values five times. A smaller value means more flexibility. In the present invention, since the nonwoven fabric has a non-woven structure inside, the obtained nonwoven fabric retains a certain degree of flexibility, and the compression stiffness is 10 g /
(G / m ² ) or less. Compression stiffness is 10g / (g /
When it exceeds m ² ), the texture of the non-woven fabric becomes hard and becomes close to a perfect film-like sheet, which is not the object of the present invention.

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 1 to
When the above-mentioned polylactic acid-based polymer composition of 100 g / 10 min was used and the melting point of this polymer was Tm ° C. (T
m + 15) ° C. to (Tm + 50) ° C., melted at a spinning temperature and spun through a spinneret having a desired fiber cross-section, and the obtained spun yarn is hitherto known as horizontal spray or annular spray. After having been cooled by using the cooling device of No. 3, the yarn is drawn and drawn to a target fineness with a high-speed air flow of 1000 to 6000 m / min by using a suction device such as an air sucker, and subsequently discharged from the suction device. After the filament group is opened, the filament is opened and deposited on a moving and accumulating device such as a conveyor composed of a screen to obtain a web. Then, the web formed on the moving deposition apparatus is subjected to partial provisional thermocompression bonding treatment and / or three-dimensional entanglement treatment, if necessary, and thereafter,
When the melting point of the polymer having the highest melting point among the polymers is set to Tm ° C. on at least one side of this web using a full-scale thermocompression bonding device, at a temperature of (Tm + 5) ° C. or less,
A long-fiber nonwoven fabric can be obtained by thermocompression-bonding the roll with a linear pressure of 0.01 kg / cm or more.

The melt flow rate value (hereinafter referred to as MFR value) of the polylactic acid-based polymer composition applied in the present invention is, as described above, ASTM-D-1238 (E).
1 to 100 g measured at 190 ° C. according to the method described in 1.
It is important that it is / 10 minutes. MFR value is 1g / 1
If it is less than 0 minutes, the melt viscosity will be too high, resulting in inferior high-speed spinnability. On the contrary, the MFR value will be 100 g / 10.
If it exceeds the minute, the melt viscosity is too low, and thus the spinnability is deteriorated and stable operation becomes 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 10 as described above.
It is important to set it to be 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 1000 m / min, oriented crystallization of the polymer is not promoted and sticking occurs between yarns, which is obtained. Nonwoven fabrics tend 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 web formed on the moving deposition apparatus may be subjected to partial provisional thermocompression bonding treatment and / or three-dimensional entanglement treatment, if necessary, before the entire surface thermocompression bonding is performed. it can. This is because the webs continuously formed by the spunbond method are entangled with each other when the webs are once taken up, and are unwound to perform partial provisional thermocompression bonding treatment and / or three-dimensional entanglement treatment. This is to prevent it from becoming difficult. Therefore, the partial provisional thermocompression bonding process and / or the three-dimensional entanglement process performed here are
It may be any one as long as it can provide a temporary holding force for the shape such that it can prevent the entanglement when wound.

In the present invention, the full thermocompression bonding of the web is performed by
The heating is performed by melting the constituent long fibers near the surface of the web with a metal roll whose surface is heated to form a film.

As described above, the processing temperature for the full thermocompression bonding, that is, the surface temperature of the metal roll must be lower than (Tm + 5) ° C. when the melting point of the polymer used is Tm ° C. I won't. However, when the web to be thermocompression-bonded is formed from long fibers made of a blend of two or more polylactic acid-based polymers, or is composed of two components, for example, the core-sheath composite cross section or split type described above. In the case of being formed from long fibers having a composite cross section such as a composite cross section, the melting point of the polymer having the highest melting point of the polymers forming the blend, or the most of the two components forming the composite cross section. When the melting point of a component having a high melting point is taken as a reference, and these melting points are set to Tm ° C. (Tm
The processing temperature must be +5) ° C or lower.
If this temperature is exceeded, not only the polymer will adhere to the thermocompression bonding device and the operability will be significantly impaired, but also the nonwoven fabric will become stiff and the texture will deteriorate.

Further, when thermocompression bonding is applied, it is important that the linear pressure of the roll is 0.01 kg / cm or more.
When the linear pressure of the roll is less than 0.01 kg / cm, the thermocompression bonding effect is poor, and the mechanical strength and dimensional stability of the resulting nonwoven fabric are not improved, which is not preferable. On the other hand, if the linear pressure of the roll exceeds 10 kg / cm, the thermocompression bonding effect becomes excessive, and the entire nonwoven fabric tends to form a film, so that only a non-stiffened nonwoven fabric tends to be obtained. Therefore, the linear pressure of the roll is 10 kg. / Cm or less is preferable.

In the present invention, at least one surface of the web may be thermocompression bonded. In particular, when thermocompression bonding is applied to both sides of the web, a three-layer structure including a film layer having air-permeable and water-impervious properties on the front and back sides and a non-woven fabric layer containing air between them is formed, so that heat retention is maintained. An excellent nonwoven fabric can be obtained.

The thermocompression bonding process may be a continuous process or a separate process.

[0040]

The present invention will be described below in detail 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.): extreme value of a melting endothermic curve obtained by using a differential scanning calorimeter DSC-2 manufactured by Perkin Elmer, measuring the sample weight at 5 mg and the heating rate at 20 ° C./min. Was given as the melting point (° C.).

-Basis weight (g / m ² ); 10 pieces each of 10 cm in length × 10 cm in width were prepared from a sample in a standard state, and after reaching equilibrium moisture, the weight (g) of each piece was weighed. ,
The average value of the obtained values was converted per unit area to obtain a basis weight (g / m ² ).

KGSM tensile strength (kg / 5 cm width);
It was measured according to the strip method described in JIS-L-1096. That is, the sample length is 10 cm and the sample width is 5 c
10 pieces each of m sample pieces were prepared, and a constant-speed extension type tensile tester (Tensilon UTM-4-1-100 manufactured by Toyo Baldwin Co., Ltd.) was used for each sample piece in the warp and weft directions of the nonwoven fabric.
Was stretched at a tensile speed of 10 cm / min, and the average value of the load values during cutting (kg / 5 cm width) obtained was 100 g / m ^2.
KGSM tensile strength (kg / 5cm
Width).

・ Compression stiffness of non-woven fabric (g / (g / m
² )); 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 into a cylindrical object, and the ends were joined together by compression bending. The measurement sample was used. Then, the maximum load obtained by compressing at a compression rate of 5 cm / min using a constant-speed extension type tensile tester (Tensilon UTM-4-1-100 manufactured by Toyo Baldwin Co., Ltd.) in the axial direction of each measurement sample Compressive stiffness (g / (g / m ² )) is the average of the values obtained by dividing the value (g) by the basis weight.
And Therefore, the smaller the value of this compression stiffness is, the better the flexibility is.

・ Biodegradability of non-woven fabric: Non-woven fabric is about 58 ° C.
When the nonwoven fabric does not retain its shape after being embedded in the aged compost maintained for 3 months, or when the nonwoven fabric retains its shape, the tensile strength is 50 against the initial strength before embedding. 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.
/ Minute, the fibers were opened, and the fibers were deposited on the collecting surface of the moving conveyor, and then partially pre-thermocompressed with an embossing roll heated at 145 ° C to form a web. Next, six of these webs were laminated and a 200 # / cm ² needle punch was performed with a # 40 regular needle to form a three-dimensional entanglement between the constituent fibers. This three-dimensionally entangled web was subjected to a Yankee dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.) under conditions of a surface temperature of 170 ° C., a heat treatment time of 100 seconds, and a linear pressure of 0.5 kg / cm. Only the whole was thermocompression-bonded to obtain a long-fiber nonwoven fabric having a basis weight of 170 g / m ² . 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 processing temperature were changed as shown in Table 1. Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

Example 3 L-lactic acid / D-lactic acid = 80/20 mol% L-lactic acid and D
-Using a copolymer with lactic acid, the spinning temperature and processing temperature are shown in Table 1.
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the change was made as shown in FIG. Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

Example 4 A long-fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the spinning temperature and the processing 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 5 A long-fiber nonwoven fabric was obtained in the same manner as in Example 4 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 6 The single hole discharge rate was 2.70 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.

Example 7 L- having a melting point of 111 ° C. and an MFR value of 20 g / 10 minutes
A copolymer of lactic acid / glycolic acid = 80/20 mol%
As a component, L-lactic acid / D-lactic acid having a melting point of 141 ° C. and an MFR value of 20 g / 10 min = 90/10 mol% of poly (D, L-lactic acid) is a B component, and each component is an A component / B
The component was used at a ratio of 1/1 (weight ratio), and the spinning temperature was 170 ° C. at a spinning temperature of 170 ° C. from a spinneret in which the component A was placed in the core and the component B was placed in the leaf in the split composite cross section shown in FIG. Melt spinning was performed at a hole discharge rate of 1.35 g / min. Next, after the spun yarn is cooled with a cooling air flow having a temperature of 20 ° C., the spun yarn is subsequently taken up with an air sucker at a take-up speed of 3500 m / min, opened, and placed on the collecting surface of a moving conveyor. Accumulate 3
A web of 00 g / m ² was formed. Then, this web was needle punched at 200 punches / cm ² with a # 40 regular needle to form a three-dimensional entanglement between the constituent fibers. This three-dimensionally entangled web has a surface temperature of 125 ° C., a heat treatment time of 100 seconds, and a linear pressure of 1.0 k.
Using a Yankee dryer (manufactured by Kumagai Riki Kogyo Co., Ltd.) under the condition of g / cm, only one side of the web was thermocompressed over the entire surface to obtain a split type composite long fiber nonwoven fabric having a basis weight of 280 g / m ² . Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

Example 8 In the same manner as in Example 1, a long-fiber non-woven sheet having a single surface entirely subjected to thermocompression bonding was obtained. Further, this sheet was reversed, and the entire surface was again subjected to the same heat treatment under the same conditions. Apply crimping treatment,
A double-sided thermocompression-bonded long-fiber nonwoven fabric having a basis weight of 150 g / m ² was obtained. Table 1 shows production conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

[0055]

[Table 1]

As is clear from Table 1, the long-fiber nonwoven fabrics obtained in Examples 1 to 9 all have excellent mechanical strength of 3 kg / 5 cm width or more, and have compression stiffness of 10 g.
It had a certain flexibility of not more than / (g / m ² ). Furthermore, these non-woven fabrics have excellent air-permeable and water-blocking properties, and also have very good biodegradability, and when taken out after embedding in a compost, both non-woven fabrics exhibited a weight reduction rate, The morphological change was large, and the strength retention was significantly reduced.

Comparative Example 1 and Comparative Example 2 Example 1 except that the take-up speed was changed as shown in Table 2.
An attempt was made to make a long-fiber non-woven fabric 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,
An attempt to make a long-fiber nonwoven fabric was made 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.
An attempt was made to make a long-fiber non-woven fabric in the same manner as in. Table 2 shows the production conditions and operability.

Comparative Example 7 A long fiber non-woven fabric was obtained in the same manner as in Example 1 except that the processing temperature at the time of full-scale thermocompression bonding treatment was 175 ° C. Table 2 shows manufacturing conditions, operability, physical properties of non-woven fabric, and biodegradability.
Shown in

Comparative Example 8 A long fiber non-woven fabric was obtained in the same manner as in Example 1 except that the linear pressure at the time of full-scale thermocompression bonding treatment was changed as shown in Table 2.
Table 2 shows manufacturing conditions, operability, physical properties of the nonwoven fabric, and biodegradability.

Comparative Example 9 L- having a melting point of 168 ° C. and an MFR value of 20 g / 10 min.
Lactic acid / hydroxycaproic acid = 90/10 mol% L-
Example 1 using a lactic acid-hydroxycaproic acid copolymer
The same sheet-like film having a basis weight of 170 g / m ² was formed. Table 2 shows the physical properties and biodegradability of this film.

[0063]

[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 1000 m / min, fusion between filaments occurred, the openability was poor, and a sheet with a 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, the MFR value was 100 g.
Since it exceeds / 10 minutes, the spinnability due to high-speed air flow is poor,
Thread breakage occurred frequently and it could not be made into a sheet.

In Comparative Example 4, the MFR value was 1 g / 1.
Since it was less than 0 minutes, the drawability and take-up property by the high-speed air flow were poor, and the operability was impaired.

In Comparative Example 5, since the spinning temperature was lower than (Tm + 15) ° C. when the melting point of the polymer was Tm, the result was poor spinnability / take-off property due to high-speed air flow, resulting in impaired operability. .

In Comparative Example 6, since the spinning temperature was higher than (Tm + 50) ° C. when the melting point of the polymer was Tm, the crystallization in the cooling process was delayed and the 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, since the processing temperature at the time of thermocompression bonding was set to a temperature 7 ° C. higher than the melting point of the polymer,
The obtained non-woven fabric was formed into a film lacking flexibility.

In Comparative Example 8, since the linear pressure at the time of thermocompression bonding was too high, the obtained non-woven fabric was a film lacking in flexibility.

In Comparative Example 9, since it was a perfect film and did not have a non-woven structure inside, it lacked flexibility and was not practical for the intended use of the present invention.

[0073]

According to the present invention, since at least one side of a web formed of long fibers is thermocompressed over its entire surface, its shape as a non-woven fabric is maintained. And long-term non-woven fabric that has excellent mechanical strength and at the same time has a non-woven structure, which makes it more flexible than a perfect film sheet due to its non-woven structure. Can be provided. Moreover, since the nonwoven fabric obtained in the present invention comprises polylactic acid-based long fibers as constituent fibers, it can be decomposed in a natural environment.

Therefore, the non-woven fabric of the present invention can be used as a civil engineering material such as a horizontal or vertical drain sheet or a waterproof sheet,
Agricultural and horticultural materials such as house curtains or vegetation support sheets and planting containers, hygiene materials such as backsheets of disposable diapers, and other general industrial materials that require degradability, water impermeability, and ventilation impermeability. It can be effectively applied in applications 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.

FIG. 4 is a model view of a fiber cross section of a splittable conjugate long fiber showing still another example of long fibers constituting the nonwoven fabric of the present invention.

FIG. 5 is a model diagram of a fiber cross section of a splittable composite continuous fiber showing still another example of continuous fibers constituting the nonwoven fabric of the present invention.

FIG. 6 is a model view of a fiber cross section of a splittable composite continuous fiber showing still another example of continuous fibers constituting the nonwoven fabric of the present invention.

[Explanation of symbols]

 1 Hollow part 2 High melting point component 3 Low melting point component

Claims (15)

[Claims] 1. A polylactic acid-based long-fiber non-woven fabric, characterized in that at least one side of a web composed of long fibers made of a polylactic acid-based polymer is thermocompression-bonded over the entire surface. 2. The polylactic acid-based polymer is 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, copolymer of L-lactic acid and hydroxycarboxylic acid 2. The polylactic acid-based long-fiber nonwoven fabric according to claim 1, which is a polymer having a melting point of 100 ° C. or higher among the polymers selected from the group consisting of: and a blend thereof. 3. 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. 4. The fiber cross section of the constituent long fiber is a solid cross section or a hollow cross section.
The polylactic acid-based long-fiber nonwoven fabric according to any one of items 1 to 6 above. 5. The polylactic acid-based long-fiber nonwoven fabric according to claim 1, wherein the fiber cross section of the constituent long fibers is a polygonal or flat-shaped irregular cross section. 6. The fiber cross section of the constituent long fibers is a core-sheath composite cross section composed of two components constituting the long fibers, and the two components constituting the long fibers are a polylactic acid polymer or two or more kinds of poly. The polylactic acid-based long-fiber nonwoven fabric according to any one of claims 1 to 3, which is a blend of lactic acid-based polymers. 7. A split type composite cross section in which the fiber cross section of the constituent continuous fiber has a form in which two components constituting the continuous fiber are separated from each other, and both are continuous in the fiber axial direction and exposed on the fiber surface. 4. The two components constituting the long fiber are a polylactic acid-based polymer or a blended product of two or more kinds of polylactic acid-based polymers, according to any one of claims 1 to 3. Polylactic acid-based long-fiber non-woven fabric. 8. The melting point of the constituent filaments of the non-woven fabric is 100.degree.
The polylactic acid-based long-fiber nonwoven fabric according to any one of claims 1 to 7, which is the above. 9. The single yarn fineness of the constituent long fibers of the non-woven fabric is 0.5.
10 denier, and the basis weight of the nonwoven fabric is 10 to 10
The polylactic acid-based long-fiber nonwoven fabric according to any one of claims 1 to 8, which has a weight of 00 g / m ² . 10. The polylactic acid-based continuous fiber according to claim 1, wherein the nonwoven fabric has a tensile strength of 3 kg / 5 cm width or more when converted to a basis weight of 100 g / m ^2. Non-woven fabric. 11. The compression stiffness of the nonwoven fabric per unit weight is 1
The polylactic acid-based long fiber non-woven fabric according to any one of claims 1 to 10, which is 0 g / (g / m ² ) or less. 12. A melt flow rate value measured at 190 ° C. according to ASTM-D-1238 (E) is 1 to
When the melting point of this polylactic acid-based polymer is 100 g / 10 minutes and the melting point of this polymer is Tm ° C., (Tm + 15) ° C. to (T
m + 50) ° C., melted and discharged from the spinneret, and the discharged yarn is drawn and thinned by a suction device at a take-up speed of 1000 to 6000 m / min, and then spread while being spread on the movable collecting surface. To form a web, and using at least one side of the web with a thermocompression bonding apparatus for the whole surface, when the melting point of the polymer is Tm ° C., the linear pressure of the roll is 0.01 kg at a temperature of (Tm + 5) ° C. or less. / Cm or more, and thermocompression-bonding the entire surface, a method for producing a polylactic acid-based long-fiber nonwoven fabric. 13. A web formed by depositing fibers on a movable collection surface while opening the fibers is previously subjected to partial provisional thermocompression bonding treatment and / or three-dimensional entanglement treatment, and then at least one surface of the web. 13. The method for producing a polylactic acid-based long-fiber non-woven fabric according to claim 12, characterized in that the entire surface is thermocompression-bonded. 14. The partial provisional thermocompression bonding treatment is performed at a temperature 10 ° C. or more lower than the melting point of the polymer having the lowest melting point among the polymers constituting the web. A method for producing a polylactic acid-based long-fiber nonwoven fabric. 15. Melting-spinning is performed using a spinneret having a cross-section of a fiber having a composite cross section using two or more kinds of components made of a polylactic acid polymer, and the melting point of the highest melting point of the two or more kinds of components is determined. The method for producing a polylactic acid-based long-fiber nonwoven fabric according to any one of claims 12 to 14, wherein thermocompression bonding is carried out entirely at a temperature of (Tm + 5) ° C or lower when (Tm) ° C. .