JPH0995852A - Polylactate-based laminated nonwoven fabric and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new multifunctional polylactate-based filament nonwoven fabric having water-absorptivity and a mechanical strength sufficient for practical use even in wet state. SOLUTION: This polylactate-based laminated 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, bonding the web to obtain a filament web layer having shape-retainability, laminating a natural fiber or regenerated fiber web layer separately produced by conventional method to the filament web layer and subjecting the laminate to ultrasonic welder treatment to release and interlock at least a part of the bonded points and integrate the web layers with each other.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a laminated nonwoven fabric having degradability in a natural environment and a method for producing the same. More specifically, the present invention relates to a novel multifunctional degradable laminated nonwoven fabric obtained by using a polylactic acid 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, although these biodegradable nonwoven fabrics are generally hydrophilic and have excellent water absorption,
On the other hand, 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.

In recent years, research and development on degradable fibers and non-woven fabrics by a melt spinning method using a biodegradable polymer having thermoplasticity have been actively conducted. For example, a group of polymers collectively referred to as aliphatic polyesters are of particular interest because of their biodegradability. In particular,
Poly-β-hydroxyalkanoates typified by microbial polyesters, poly-ω-hydroxyalkanoates typified by polycaprolactones, polyalkylenediones composed of polycondensates of glycols and dicarboxylic acids such as polybutylene succinate. Examples thereof include carboxylates or copolymers thereof. Among them, poly-
With respect to poly-α-oxy acids such as L-lactic acid, a new polymerization method capable of efficiently producing a polymer having a high degree of polymerization has been developed in recent years, and various investigations have been made on its formation into fibers and nonwoven fabrics. Has been done. 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
Also in 37641 (A1), a polylactic acid spunbonded nonwoven fabric having excellent mechanical strength and multifunctionality such as water absorption as in the present invention has not been obtained.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a novel multifunctional polylactic acid-based non-woven fabric which has water absorbency and at the same time has sufficient mechanical strength for practical use even when wet. Is what you are trying to do.

[0008]

In order to solve the above problems, the present invention has the following structures. 1. A web layer of natural fibers or recycled fibers is laminated on and integrated with a long-fiber web layer made of a polylactic acid polymer.

[0009] 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. Then, the web is bonded to obtain a long-fiber web layer that retains its shape, and after laminating a web layer of natural fiber or regenerated fiber separately prepared by a conventional method on this long-fiber web layer, ultrasonic wave welding is applied. The two web layers are integrated to obtain a polylactic acid-based laminated nonwoven fabric.

3. 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. Then, the web is bonded to obtain a long fiber web layer which retains its shape, and after laminating a web layer of natural fiber or recycled fiber separately prepared by a conventional method on this long fiber web layer, a three-dimensional entanglement treatment is performed. At least a part of the bonding is peeled and entangled, and both web layers are integrated to obtain a polylactic acid-based laminated nonwoven fabric.

As described above, in the laminated nonwoven fabric of the present invention, since the web layer of natural or regenerated fibers is laminated on the polylactic acid-based long fiber web layer, the water absorption is exhibited by the natural or regenerated fibers. The polylactic acid-based long fiber web layer reinforces the property of natural fibers or recycled fibers that they have poor mechanical strength when wet. Moreover, since the long fiber web layer is composed of a polylactic acid-based polymer and the web layer of natural fibers or recycled fibers is composed of a degradable material such as cellulose, all the constituent materials of the laminated nonwoven fabric of the present invention are under natural environment. And can be decomposed, and a laminated nonwoven fabric having excellent decomposition performance can be obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The long fiber web layer of the present invention comprises a polylactic acid polymer. Examples of the polylactic acid-based polymer include poly (D-lactic acid), poly (L-lactic acid), and D-
Among the 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, the melting point is Polymers at 100 ° C. or higher or blends thereof are preferred.

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 preferable that the melting point of the polylactic acid-based polymer is 100 ° C. or higher from the viewpoint of the cooling property in the spinning process. 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 10
It is important to determine the copolymerization ratio of the monomer components so that the temperature becomes 0 ° 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 becomes less than 100 ° C. or the polymer becomes an amorphous polymer. This is not preferable because the cooling property during spinning is lowered and the heat resistance of the resulting nonwoven fabric is impaired, which limits its use.

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 polymers 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.

In the present invention, if necessary, various additives such as matting agents, pigments and crystal nucleating agents may be added to the above-mentioned polymer within a range that does not impair the effects of the present invention. good. In particular, crystal nucleating agents such as talc, boron nitride, calcium carbonate, and titanium oxide are used to prevent fusion (blocking) between yarns in the spinning / cooling process.
It is useful to use in the range of 0.1 to 3% by weight.

The long fibers constituting the long fiber web layer in the present invention may have a fiber form of one of the above polymers alone, or a composite of two or more of the above polymers. Fiber may be used. The fiber cross-section may be a solid cross-section or any other fiber cross-section form, such as hollow cross-section, modified cross-section, parallel composite cross-section, multi-layer composite cross-section, core-sheath composite cross-section, split. It is preferably one of the mold composite sections. In particular, in the case of using a long fiber web layer whose shape is maintained by a hot air bonding treatment described later, it may be a composite cross section such as a parallel composite cross section, a multilayer composite cross section, a core-sheath composite cross section, a split composite cross section, and the like. is necessary.

The single fiber fineness of the long fibers constituting the long fiber web layer in the present invention is preferably 0.5 to 10 denier. If the single yarn fineness is less than 0.5 denier, spinning
Single yarn cutting frequently occurs in the take-up step, and the operability and the strength of the long fiber web layer obtained tend to be poor. vice versa,
If the single yarn fineness exceeds 10 denier, the spun yarn will not be sufficiently cooled, which is not preferable.

The shape of the long-fiber web layer of the present invention is retained by any one of a partial thermocompression treatment, a whole thermocompression treatment, a hot air adhesion treatment, and a three-dimensional entanglement treatment. There is something.

More specifically, the partial thermocompression treatment means that the web is partially thermocompressed without bonding the constituent long fibers to each other at the crossing points, and the sheet-like form having the non-woven structure is maintained. The long fiber web layer shape-maintained by this method has excellent flexibility because only the point-like fused regions that are partially formed are bonded. .

Further, the whole surface thermocompression treatment is a method in which at least one side of the web is entirely thermocompressed to retain a sheet-like form having a non-woven structure, and the non-woven structure is retained inside. However, it forms a film-formed structure only on the surface. Therefore, the long fiber web layer shape-retained by this method exhibits excellent mechanical strength as well as ventilation barrier property and water barrier property because the surface is a film shape, and at the same time, there is a non-woven structure inside. Therefore, it has excellent flexibility as compared with a perfect film sheet.

The hot air adhesion treatment is carried out by applying heat adhesion at a contact point between constituent long fibers of a web formed of a composite long fiber composed of a high melting point component and a low melting point component,
It retains a sheet-like form having a non-woven structure,
Despite having excellent mechanical strength, the web retains its shape without being compressed while maintaining the three-dimensional structure of the web. It has good bulkiness as compared with.

The three-dimensional entanglement treatment is a non-woven structure in which the constituent fibers are closely entangled in a three-dimensional manner by applying a pressurized liquid flow to the web or performing a needle punching treatment. The sheet-like form having the above is retained. Therefore, the long fiber web layer shape-maintained by this method does not cause melting of the polymer unlike the method involving heating, and thus has excellent flexibility.

The web layer of natural fibers or recycled fibers in the present invention is made of natural fibers or recycled fibers.
For example, in addition to cellulosic fibers such as cotton fibers and hemp fibers, animal fibers such as ramie and silk staple fibers, natural pulp, various regenerated fibers represented by rayon, etc. Considering hygroscopicity, heat resistance, raw material cost, and the like, cotton is particularly preferably used. Also,
These natural fibers or regenerated fibers may be in any form such as combed yarn that has not been bleached, bleached cotton that has been bleached, or various fluff obtained from a woven or knitted fabric. In addition, these natural fibers or regenerated fibers may be used alone or as a mixture of a plurality of them, or may be used as a cotton blend with a biodegradable synthetic fiber.

If necessary, the web layer of the natural fiber or the regenerated fiber of the present invention may be subjected to a pressurized liquid flow treatment or a needle punch treatment in advance to be integrated before laminating with the long fiber web layer. it can. The laminated non-woven fabric obtained through such treatment is free from fluff of natural fibers or regenerated fibers and is excellent in mechanical strength.

The long fiber web layer of the present invention and the natural fiber or
The regenerated fiber web layer generally has a basis weight of 10 to 10
0 g / m² Is preferably within the range. Weight is 10g
/ M ² If it is less than, the texture and mechanical strength are inferior.
It will not be usable. Conversely, the basis weight is 100 g / m² 
If it exceeds, the flexibility is impaired, which is not preferable.
Yes. However, this basis weight depends on the intended use of the laminated nonwoven fabric obtained.
It is desirable to make an appropriate adjustment in accordance with
But of course it's good.

In the laminated nonwoven fabric of the present invention, the long fiber web layer and the web layer of natural fiber or recycled fiber are laminated,
Both web layers are integrated by ultrasonic welder processing or three-dimensional entanglement processing.

However, when they are integrated by three-dimensional entanglement treatment, it is preferable that the long fiber web layer is maintained in shape by the above-mentioned partial thermocompression treatment or three-dimensional entanglement treatment. If the long-fiber web layer is entirely heat-pressed or hot-air bonded to maintain its shape, the long-fiber web layers are fixed by heat fusion between the constituent fibers. There is a tendency that it is difficult to densely and three-dimensionally entangle constituent fibers with each other by a mechanical force due to, for example, a pressurized liquid flow or a needle.

When the long-fiber web layer that has been partially thermocompression-bonded and the web layer of natural fibers or regenerated fibers are integrated by a three-dimensional entanglement process, partial thermocompression-bonding of the long-fiber web layer is performed. Processing conditions are especially important. That is,
By appropriately selecting the embossing roll temperature during thermocompression bonding, the linear pressure of the roll, etc., perform partial thermocompression bonding to the extent that at least part of the thermocompression bonding points separate during the three-dimensional entanglement treatment performed after lamination. is necessary. As a result, dimensional stability and mechanical strength are imparted by three-dimensional entanglement of the constituent long fibers including the peeled fibers, and the long fiber web layer in the final laminated nonwoven fabric is mostly unfused. Since the area is retained, a laminated nonwoven fabric having excellent flexibility can be obtained.

The laminated nonwoven fabric of the present invention has a basis weight of 100 g / m.
The tensile strength when converted to ² is preferably 1 kg / 5 cm width or more. 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 proportionally converted to a basis weight of 100 g / m ^2. The non-woven fabric obtained is evaluated. If the tensile strength of the non-woven fabric is less than 1 kg / 5 cm width, the mechanical strength is too low, and it may not be practical.

In the present invention, when laminating a long fiber web layer and a web layer of natural fibers or regenerated fibers, the lamination ratio (weight ratio) is defined as long fiber web layer / natural fiber or regenerated fiber web layer = It is preferably 1/5 to 5/1. If the number of long fiber web layers exceeds this range, the water absorbency and hygroscopicity of the resulting laminated nonwoven fabric will be impaired, and conversely, if the number of web layers of natural fibers or recycled fibers exceeds this range, the obtained laminated nonwoven fabric will increase. However, both of them are not preferable because they impair the mechanical strength of.

Next, a method for producing the polylactic acid-based laminated nonwoven fabric of the present invention will be described. First, a long fiber web layer is manufactured by the so-called spunbond method described below. That is, A
Using the above-mentioned polylactic acid-based polymer composition having a melt flow rate value of 1 to 100 g / 10 minutes measured at a temperature of 190 ° C. according to STM-D-1238 (E), the melting point of this polymer is Tm. (Tm + 15) ° C ~ (T
m + 50) ° C., melted at a spinning temperature and spun through a spinneret having a desired fiber cross-section, and the obtained spun yarn is cooled by a conventionally known cooling device such as horizontal spraying or annular spraying. After cooling with air, a suction device such as an air sucker is used to draw and thin the yarn group discharged from the suction device by pulling and thinning to a target fineness with a high-speed air flow of 1000 to 6000 m / min. Then, the fibers are opened and deposited on a moving and depositing device such as a conveyor including a screen to obtain a web. Then, the web formed on this moving deposition apparatus is subjected to a partial thermocompression treatment using an embossing roll or the like,
By the whole surface thermocompression bonding treatment using a smooth roll or the like, the hot air adhesion treatment, or the three-dimensional entanglement treatment using a pressurized liquid flow or a needle, the shape of the web is retained.
Obtain a long fiber web layer.

Then, the obtained long fiber web layer is laminated with a web layer of the above-mentioned natural fiber or regenerated fiber which is separately prepared by a conventional method, and ultrasonic wave welder treatment or three-dimensional entanglement treatment is applied to both webs. By integrating the layers, a polylactic acid-based laminated nonwoven fabric can be obtained.

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, in the melt spinning for forming the long fiber web layer, as described above, when the melting point of the polymer used is Tm ° C., (Tm + 15) ° C. to (Tm + 50)
It must melt at temperatures in the range of ° 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. The spinning temperature is (Tm + 1
5) If the temperature is lower than ℃, the drawability and take-up property due to high-speed air flow are inferior. Not only is it inferior, but the thermal decomposition of the polymer itself also progresses, making it difficult to obtain a long fiber web layer having a soft and uniform texture.

In the present invention, when the spun yarn is towed and thinned by using a suction device at the time of forming the long fiber web layer, the take-up speed is set to 1000 to 6000 m / min as described above. is important. 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. Long fiber web layers tend to be hard and poor 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 partial thermocompression-bonding treatment of the long fiber web layer is performed by forming a spot-shaped fusion-bonding area by embossing or ultrasonic fusion-bonding, specifically, heated embossing. A method is used in which a web is passed between a roll and a metal roll having a smooth surface to form spot-shaped fused regions between long fibers.

In the present invention, the whole surface thermocompression bonding of the long fiber web layer is carried out by passing the web through a metal roll having a smooth heated surface to form fused regions between the long fibers.
In the present invention, the hot-air bonding treatment of the long fiber web layer is performed by blowing out hot air heated in the hot-air processing machine from one side, and passing the hot air through the web, and then sucking the hot air to the other side in the hot-air processing machine to form the web. It is applied by forming fused regions only at the contact points between the fibers.

In the present invention, the three-dimensional entanglement treatment of the long fiber web layer is carried out by applying a pressurized liquid flow or a mechanical force such as a needle punch to the web to form a three-dimensional entanglement between the constituent fibers. To be done.

The web layer of natural fibers or recycled fibers is prepared from the above-mentioned natural fibers or recycled fibers by a conventional method. For example, when creating a web by carding, the fiber orientation of the web is either a parallel fiber web in which the constituent fibers are arranged in the machine direction of the card machine, a random fiber web in which the constituent fibers are randomly arranged, or a medium degree of both. It may be any of semi-random fiber webs in which constituent fibers are arranged.

As a method for laminating and integrating a long fiber web layer and a web layer of natural fibers or recycled fibers, a method of forming a point-like fused portion by ultrasonic welder treatment or a three-dimensional entanglement treatment is used. A method in which the constituent fibers of both webs are densely entangled three-dimensionally is adopted.

When performing ultrasonic welder processing,
An ultrasonic oscillator with an ultrasonic oscillation frequency of 19 to 22 kHz,
An ultrasonic welder processing machine including an ultrasonic amplifier, a vibrating plate, and an engraving roll that performs ultrasonic welder processing is used. As the engraving roll, one in which dot-shaped or band-shaped ultrasonic welder portions are arranged in one row or a plurality of rows in the circumferential direction of the roll, or one in which a geometric pattern is arranged is used. The pressing force of this engraving roll is 0.5
It is good to be in the range of up to 5 kg / cm.

In carrying out the three-dimensional entanglement treatment, a method of forming a three-dimensional entanglement by using a pressurized liquid flow or a needle punch is used. When performing the pressurized liquid flow treatment, for example, injection holes having a hole diameter of 0.05 to 2.0 mm, preferably 0.1 to 0.4 mm, and a hole interval of 0.
3 to 10 mm, using an apparatus having a large number of orifices arranged in one or more rows, the injection pressure is 5 to 150 k.
A method of ejecting a pressurized liquid at g / cm ² G is adopted. The injection holes are arranged in a row along the direction orthogonal to the traveling direction of the web. When the injection holes are arranged in a plurality of rows, it is preferable that the injection holes are arranged in a zigzag manner in order to impart a uniform pressurized liquid flow action to the web. A plurality of orifices having injection holes may also be arranged. Water or hot water is generally used as the pressurized liquid. The distance between the injection hole and the web is 1 to 15 cm
It is good to If this distance is less than 1 cm, the texture of the nonwoven fabric obtained by this treatment is disturbed, and conversely, 15
If it exceeds cm, the impact force when the liquid flow collides with the web is reduced and the three-dimensional entanglement is not sufficiently performed.
Neither is preferred. Further, when the pressurized liquid flow treatment is performed, the support material for supporting the web may be, for example, a mesh screen such as a wire mesh of 10 to 300 mesh or a perforated plate, which allows the pressurized liquid flow to penetrate the web. There is no particular limitation. Incidentally, depending on the intended use, by further reversing the web that has been subjected to the entanglement treatment on one side by the above method, by supplying a pressurized liquid flow in the same manner to perform entanglement, both the front and back are closely integrated, It is possible to obtain a nonwoven fabric which is particularly excellent in dimensional stability and mechanical strength.

After performing the pressurized liquid flow treatment, it is necessary to remove excess moisture from the treated web, and a known method can be used for removing excess moisture here. For example, a squeezing device such as a mangle roll is used to mechanically remove excess water to some extent, and subsequently, a remaining amount of water is removed using a drying device such as a continuous hot air dryer. In addition to the normal dry heat treatment, the dry treatment may be a wet heat treatment, if necessary. When performing the drying process, when selecting the processing conditions such as the drying temperature and time, the conditions may be selected not only to simply remove the water but also to allow an appropriate shrinkage.

When performing the needle punching process, the needle depth is 5 to 50 mm and the punch density is 50 to 400 punch / cm.
^It is better to do it under condition ² . If the needle depth is less than 5 mm, the degree of entanglement is small and the stability of the form is poor. Further, if the punch density is less than 50 punch / cm ² , the entanglement between the constituent fibers is not sufficiently performed, and the dimensional stability of the nonwoven fabric tends to be poor.
^If it exceeds ² , the mechanical strength of the nonwoven fabric obtained by cutting the fibers with a punch needle may decrease, and both are not preferable. The punch needle is determined by selecting its thickness, length, number of barbs, type of barbs, etc. according to the single yarn fineness, intended use, and the like.

[0047]

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.); extremum value of melting endotherm curve obtained by measurement using a differential scanning calorimeter DSC-2 type manufactured by Perkin Elma Co., Ltd. with a sample weight of 5 mg and a heating rate of 20 ° C./min. Was given as the melting point (° C.).

-Unit weight (g / m ² ); 10 pieces each of 10 cm in length and 10 cm in width were prepared from the sample in the standard state to reach equilibrium water content, and then 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).

Water absorption (mm / 10 minutes); JIS-L-
It was measured according to the Bayrec method described in 1096. That is, five sample pieces each having a sample length of 20 cm and a sample width of 2.5 cm were prepared in the vertical direction and the horizontal direction, and each sample piece was placed at a certain height on a water tank containing water at 20 ± 2 ° Pinned on a horizontal bar that was supported. The lower ends of these sample pieces are aligned and the horizontal bar is lowered so that the lower ends of the sample pieces are just submerged in water.
Was measured. Therefore, the higher the value, the better the water absorption.

Delamination strength (g); sample length 15 cm,
A total of 3 sample pieces with a sample width of 5 cm were prepared, and a constant speed elongation type tensile tester (Tensilon UTM-4-1-10 manufactured by Toyo Baldwin Co., Ltd.) was used for each sample piece in the longitudinal direction of the laminated nonwoven fabric.
0) was used to forcibly peel the web layer of the natural fiber or the regenerated fiber and the long fiber web layer from the end of the laminated nonwoven fabric to a position of 5 cm at a tensile speed of 10 cm / min, and the obtained load value The average value of (g) was defined as the delamination strength (g).

Biodegradability: The non-woven fabric was embedded in an aged compost maintained at about 58 ° C. and taken out after 3 months,
The biodegradability is good when the nonwoven fabric does not retain its morphology, or when its tensile strength is reduced to 50% or less of its initial strength before embedding even though it retains its morphology. And the strength is 5 against the initial strength before burying.
When it exceeded 0%, the biodegradability was evaluated as 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 long fiber web layer was produced using a lactic acid-hydroxycaproic acid copolymer. That is, this polymer has a pore size of 0.5.
A spinning temperature of 19 from a round spinneret having 48 holes in mm
Melt spinning was performed at 5 ° 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 an embossing roll to set the roll temperature to 20 ° C. lower than the melting point of the polymer (148 ° C.), the roll linear pressure was 50 kg / cm, and the compression bonding area ratio was 7.6%.
Partial thermocompression bonding was performed under the conditions described above to obtain a continuous fiber web layer having a basis weight of 30 g / m ² and composed of continuous fibers having a single yarn fineness of 3.5 denier.

Meanwhile, as a natural fiber web layer, the average fineness of 1.5 denier, with a bleached cotton cotton having an average fiber length of 25 mm, a random carding machine, of cotton having a basis weight of 30 g / m ² arrangement of fibers is not uniform A natural fiber web layer was formed.

Next, the natural fiber web layer is laminated on the long fiber web layer and subjected to ultrasonic welder treatment,
An integrated laminated non-woven fabric was used. When performing ultrasonic welder processing, engraved areas with an area of 1 mm ² should be 3 mm apart at 2 mm intervals.
using a roll having a checkered geometry of cm,
It was performed with an ultrasonic frequency of 19.7 kHz. Table 1 shows the production conditions, operability, physical properties and biodegradability of the obtained laminated nonwoven fabric.

Example 2 The same natural fiber web layer as in Example 1 was subjected to a three-dimensional entanglement treatment by a pressurized liquid flow, and then laminated on the same long fiber web layer as in Example 1 to obtain Example 1. A unified nonwoven fabric was obtained in the same manner.

That is, for pressurized liquid flow processing, 3
Placed on a 30-mesh wire mesh that moves at a speed of 0 m / min, the injection holes with a hole diameter of 0.12 mm are 3 with a hole interval of 1.0 mm.
Using a pressurized columnar water flow treatment device arranged in a group arrangement, pressure 80 kg / c is applied from a position 80 mm above the web.
A columnar water stream was applied as m ² G. Then, the same treatment as this was performed once from the front and back of the web. continue,
After removing excess water from the obtained treated product using a mangle roll, it was dried using a hot air drier at a temperature of 60 ° C. to obtain a natural fiber web layer made of cotton of a basis weight of 26 g / m ^2. It was This natural fiber web layer is used in Example 1.
A laminated nonwoven fabric was obtained in the same manner as in Example 1 except that the natural fiber web layer was replaced with. Table 1 shows the production conditions, operability, physical properties and biodegradability of the obtained laminated nonwoven fabric.

Example 3 A long fiber web layer was obtained in the same manner as in Example 1 except that the roll temperature was 90 ° C. and the linear pressure of the roll was 30 kg / cm when the thermocompression bonding was performed on the long fiber web. Got

Next, the natural fiber web layer obtained in the same manner as in Example 1 was laminated on the long fiber web layer, and a tertiary liquid was applied by a pressurized liquid flow under the same conditions as in the formation of the natural fiber web in Example 2. The original entanglement was performed to obtain an integrated laminated nonwoven fabric. Table 1 shows the production conditions, operability, physical properties and biodegradability of the obtained laminated nonwoven fabric.

Example 4 Example 1 was repeated except that the temperature of the roll was 90 ° C., the linear pressure of the roll was 30 kg / cm, and the basis weight was 50 g / m ² when the partial thermocompression bonding was performed on the long fiber web. Similarly, a long fiber web layer was obtained.

Next, a natural fiber web layer obtained in the same manner as in Example 1 except that the basis weight was 100 g / m ² was laminated on the long fiber web layer and three-dimensionally entangled by needle punching, An integrated laminated non-woven fabric was used. In the needle punching process, a # 40 regular barb punch needle was used, the needle depth was 11 mm, and the punch density was 20 mm.
It was performed under the condition of 0 punch / cm ² . Table 1 shows the production conditions, operability, physical properties and biodegradability of the obtained laminated nonwoven fabric.

Example 5 A laminated nonwoven fabric was obtained in the same manner as in Example 2 except that the long fiber web was subjected to full thermocompression bonding to obtain a long fiber web layer. That is, the long fiber web obtained in the same manner as in Example 1 was passed through a thermocompression bonding apparatus consisting of a pair of metal rolls having smooth surfaces, and the roll temperature was set to a temperature 30 ° C lower than the melting point of the polymer (138 ° C). The linear pressure of the roll was set to 30 kg / cm and the entire surface of the web was thermocompression bonded to obtain a long fiber web layer. Table 1 shows the production conditions, operability, physical properties and biodegradability of the obtained laminated nonwoven fabric.

Example 6 As a core component, the melting point was 168 ° C. and the MFR value was 20 g / 1.
L-lactic acid / hydroxycaproic acid which is 0 minutes = 90/1
Using 0 mol% of L-lactic acid / hydroxycaproic acid copolymer, the sheath component has a melting point of 112 ° C. and an MFR value of 20.
G / 10 min L-lactic acid / D-lactic acid = 80/20 mol% of a copolymer of L-lactic acid and D-lactic acid was used to perform melt-spinning with a core-sheath type composite to obtain a core-sheath type. A long fiber web layer made of composite long fibers was obtained, the same natural fiber web layer as in Example 1 was laminated, and an integrated laminated nonwoven fabric was obtained in the same manner as in Example 1.

That is, the core component / sheath component was mixed with each other by using an individual extruder type melt extruder.
5 ° C./sheath component is melted at a temperature of 170 ° C., respectively, and a core-sheath type spinneret device having a core-sheath type fiber cross section is used.
Discharge hole diameter 0.4 mmφ, single hole discharge rate 1.3 g / min, discharge ratio of core component and sheath component is 1/1 (weight ratio), composite spinning temperature 1
The core-sheath type composite long fibers were melt-spun under the condition of 90 ° C. After cooling this spun yarn with a cooling device, it was taken with an air sucker installed below the spinneret at a take-up speed of 3500 m / min, and then opened with a known opening device to capture the moving conveyor. After obtaining a web composed of a core-sheath type composite continuous fiber group having a single yarn fineness of 3.4 denier on the collecting surface, subsequently,
Using a continuous hot air dryer, hot air treatment temperature was 150 ° C., hot air treatment time was 60 seconds, and heat treatment speed was 25 m / min. A long fiber web layer of / m ² was obtained.

Then, the natural fiber web layer obtained in the same manner as in Example 2 was laminated on the long fiber web layer to obtain an integrated laminated nonwoven fabric in the same manner as in Example 2. Table 1 shows the production conditions, operability, physical properties and biodegradability of the obtained laminated nonwoven fabric.

Example 7 The continuous fiber web layer obtained in Example 3 is followed by Example 2
In the same manner as in Example 2 except that the long fiber web layer having a basis weight of 27 g / m ² was obtained by performing a three-dimensional entanglement treatment with a pressurized liquid flow under the same conditions as in the formation of the natural fiber web. A laminated nonwoven fabric was obtained. Table 1 shows the production conditions, operability, physical properties and biodegradability of the obtained laminated nonwoven fabric.

[0069]

[Table 1]

As is clear from Table 1, all of the laminated nonwoven fabrics obtained in Examples 1 to 7 have good mechanical strength enough to withstand practical use, and have excellent water absorption and decomposition performance. It was equipped.

[0071]

According to the present invention, since a web layer of natural fibers or regenerated fibers is laminated on a polylactic acid-based long fiber web layer, the natural fibers or regenerated fibers exhibit water absorption and, at the same time, when wet. It is possible to reinforce the property of the natural fiber or the regenerated fiber, which is inferior in mechanical strength, by the polylactic acid-based long fiber web layer to give mechanical strength sufficient for practical use. Moreover, the long fiber web layer is composed of a polylactic acid-based polymer, and the web layer of natural fibers or recycled fibers is composed of a degradable material such as cellulose,
All the constituent materials of the laminated nonwoven fabric of the present invention can be decomposed in a natural environment, and a laminated nonwoven fabric having excellent decomposition performance can be obtained.

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[Procedure amendment]

[Submission date] March 25, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0069

[Correction method] Change

[Correction contents]

[0069]

[Table 1]

Claims (10)

[Claims] 1. A polylactic acid-based laminated non-woven fabric comprising a long-fiber web layer made of a polylactic acid-based polymer and a web layer of natural fibers or recycled fibers laminated and integrated. 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 non-woven 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 laminated non-woven fabric according to claim 1, wherein the long fiber web layer and the web layer of natural fibers or recycled fibers are integrated by ultrasonic welder treatment. 4. The polylactic acid-based non-woven fabric according to claim 1 or 2, wherein the long fiber web layer and the web layer of natural fibers or regenerated fibers are integrated by a three-dimensional entanglement treatment. . 5. The polylactic acid-based laminated non-woven fabric according to any one of claims 1 to 4, wherein the long fiber web layer is maintained in shape by a partial thermocompression treatment. 6. The polylactic acid-based laminated non-woven fabric according to any one of claims 1 to 3, wherein the long-fiber web layer is held in its shape by a thermocompression treatment on the entire surface. 7. The polylactic acid-based laminated non-woven fabric according to any one of claims 1 to 4, wherein the long-fiber web layer is held in shape by hot air adhesion treatment. 8. The polylactic acid-based laminated non-woven fabric according to any one of claims 1 to 4, wherein the long fiber web layer is maintained in shape by a three-dimensional entanglement treatment. 9. A melt flow rate value of 1 to 1 measured at a temperature of 190 ° C. according to ASTM-D-1238 (E).
When the melting point of this polylactic acid-based polymer, which is 00 g / 10 minutes, is Tm ° C., (Tm + 15) ° C. to (Tm
It is melted at a temperature of +50) ° C. and discharged from a 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 a movable collecting surface. Then, the web is bonded to obtain a long-fiber web layer that retains its shape, and after laminating a web layer of natural fiber or regenerated fiber separately prepared by a conventional method on this long-fiber web layer, ultrasonic wave welding is applied. A method for producing a polylactic acid-based laminated non-woven fabric, which comprises integrating both web layers together. 10. 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, 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. Then, the web is bonded to obtain a long fiber web layer which retains its shape, and after laminating a web layer of natural fiber or recycled fiber separately prepared by a conventional method on this long fiber web layer, a three-dimensional entanglement treatment is performed. A method for producing a polylactic acid-based laminated non-woven fabric, characterized in that at least a part of the bonding is peeled and entangled and both web layers are integrated.