JP2001123371A - Biodegradable spun-bond nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable spun-bond nonwoven fabric having excellent heat resistance and dimensional stability despite possessing biodegradability, widely usable as a base for sanitary/medical articles, clothing, a base for household and industrial articles, an agricultural material, or the like. SOLUTION: This biodegradable spun-bond nonwoven fabric is characterized in that a continuous filament composed of a biodegradable aliphatic thermoplastic resin is provided with mutually self-fusing filament zones at regular intervals and heat bonded, the fineness of the continuous filament is 1-5 denier and dry-heat shrinkage percentage of the filament constituting the nonwoven fabric at 130 deg.C is <=10%. The dry-heat shrinkage percentage of the continuous filament measured based on JIS L 1,013 at 130 deg.C is preferably <=20%. The aliphatic polyester resin is preferably a polylactic acid polymer containing >=80 mol% L-lactic acid unit or D-lactic acid unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a base material for sanitary and medical supplies, clothing, household use, which can be completely decomposed by microorganisms in compost, wet soil, water containing activated sludge, or seawater. The present invention relates to a biodegradable spunbond nonwoven fabric that can be widely used as a substrate, an industrial article substrate, an agricultural material, and the like.

[0002]

2. Description of the Related Art Spunbonded nonwoven fabrics using long fibers as constituent fibers are used for various purposes because they are higher in strength and relatively inexpensive than short fiber nonwoven fabrics containing short fibers as constituent fibers. . As a fiber material constituting the spunbonded nonwoven fabric, polymers such as polyethylene, polypropylene, polyester, and polyamide are generally used. However, spunbonded nonwoven fabrics made of these materials are not biodegradable by microorganisms and the like, and are chemically very stable under ordinary natural environments.

[0003] Therefore, the disposable non-woven fabric, after use,
At present, it is treated by incineration or landfill. Incineration is widely performed in Japan, but not only requires a great deal of expense, but also, for example, in the case of nylon-based long-fiber nonwoven fabric, which is a polyamide, there is a risk of generating a toxic gas such as cyanide gas. Because
There are concerns about environmental problems caused by waste plastics,
How to solve the problem of waste plastic processing is a major social problem in terms of protection of the natural environment and living environment.

[0004] On the other hand, there is a problem with landfills because the material is chemically stable and therefore remains in the original state for a long time in soil. As a method to solve such a problem, by using a biodegradable material,
There is a need for a new biodegradable spunbond nonwoven that will degrade naturally over a period of time.

[0005] Examples of biodegradable polymers include polysaccharides such as chitin, proteins and polypeptides (polyamino acids) such as cut and gut (intestinal tract) and regenerated collagen, and poly-3-hydroxybutyrate produced by microorganisms in nature. And microbial polyesters such as poly-3-hydroxyvalerate and poly-3-hydroxycaprolate, and synthetic aliphatic polyesters such as polyglycolide and polylactide. However, when producing fibers from these polymers, there is a problem that the melt spinnability essential for spunbonded nonwoven fabrics is very poor, and it cannot be produced with a commonly used spunbonded nonwoven fabric production apparatus.

[0006] Further, since the cost of the material is extremely high, it is not suitable as a general disposable living material such as a sanitary material such as a disposable diaper or a cover stock of a sanitary article, a wiping cloth and a packaging material.

To solve the above problems, Japanese Patent Laid-Open No.
No. 57953 proposes a spunbonded nonwoven fabric made of polyethylene containing 3 to 30% of polycaprolactone as a biodegradable polymer. However, since polyethylene does not decompose semipermanently, it cannot be said to be a biodegradable spunbond nonwoven fabric in the original sense.
Further, Japanese Patent Application Laid-Open No. Hei 5-214648 proposes a spunbonded nonwoven fabric comprising poly-ε-caprolactone and / or poly-β-polopiolactone. In this case, the microorganism can be completely degraded,
The melting point of poly-ε-caprolactone is around 60 ° C, and the melting point of poly-β-polopiolactone is around 100 ° C,
Poor thermal stability causes practical problems.

Further, JP-A-7-48768 and JP-A-7-34369, and the inventors of the present invention disclose in JP-A-8-60513 that glycol and an aliphatic dicarboxylic acid or a derivative thereof are composed of structural units. A biodegradable spunbonded nonwoven fabric made of an aliphatic polyester resin, characterized by being included as a nonwoven fabric, was proposed. Although this nonwoven fabric has substantially solved the above-mentioned problems, it has not yet been found that a nonwoven fabric satisfying the practical spinnability and biodegradability has been obtained.

That is, as the aliphatic polyester suitable for melt spinning and usable for spunbond nonwoven fabric, for example, a polybutylene succinate polymer synthesized from 1,4-butanediol and succinic acid is a urethane High molecular weight by bonding, or 1,4
-Polybutylene succinate-adipate copolymer synthesized from butanediol and succinic acid and adipic acid has good melt spinnability, low elastic modulus and sufficient fiber flexibility, so that biodegradation with excellent texture Although a spunbond nonwoven fabric is obtained, the tensile strength of the fibers is small and the strength of the nonwoven fabric is low. In addition, the biodegradability is too fast and is not suitable for applications requiring strength for a certain period.

Further, Japanese Patent Application Laid-Open No. 9-21018 discloses a thermoplastic resin comprising a polylactic acid polymer and / or a copolymer mainly composed of polylactic acid, wherein the content of the low molecular weight compound is 1% by weight or less. Certain biodegradable fibers have been disclosed. This fiber, and a non-woven fabric using this fiber, if the stretching at the time of fiber production is sufficient, the tensile strength of the fiber is increased, a non-woven fabric with excellent strength is obtained, but if the stretching is insufficient, the fiber Is insufficiently crystallized, and the fibers shrink in the heat bonding step during the processing of the nonwoven fabric, and not only the texture becomes hard, but also the processing of the nonwoven fabric becomes difficult in some cases.

In Japanese Patent Application Laid-Open No. 8-246320,
A nonwoven fabric formed of a polymer derived from lactic acid or a mixture of polymers derived from lactic acid is disclosed. This nonwoven fabric is formed by bonding the nonwoven fabric by hot calendering. However, if the dry heat shrinkage of the fiber in the portion outside the self-fusing area of the nonwoven fabric is large, the dimensional stability of the nonwoven fabric is deteriorated. . In addition, if the elastic modulus is large and the fineness is further increased, the biodegradable spunbond nonwoven fabric manufactured using the long fiber as the web becomes hard, and the nonwoven fabric is inferior in flexibility and texture, and is used as a cover for disposable diapers and sanitary products. It is not suitable for applications requiring flexibility and texture, such as sanitary materials such as stocks, wipes, and packaging materials.

[0012]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies in view of the present situation, and as a result, under certain conditions, a polylactic acid polymer containing 80 mol% or more of an L-lactic acid unit or a D-lactic acid unit. Melt spinning, adjusting the degree of stretching by taking off with high-speed air of the ejector, thereby adjusting the dry heat shrinkage of long fibers before and after thermal bonding within a specific range, and adjusting the fineness of long fibers to a specific range When they were balanced with each other, they found that the biodegradable spunbonded nonwoven fabric obtained while maintaining good spinnability and processability had extremely excellent dimensional stability and flexibility, and completed the present invention. That is, the object of the present invention is to have excellent heat resistance and dimensional stability, while having biodegradability, base materials for sanitary and medical supplies, clothing, household substrates, industrial substrates,
An object of the present invention is to provide a biodegradable spunbonded nonwoven fabric that can be widely used as agricultural materials.

[0013]

Means for Solving the Problems The biodegradable spunbonded nonwoven fabric according to the present invention comprises a continuous long fiber made of an aliphatic polyester resin having biodegradability, and a self-fusion area between the long fibers at regular intervals. The continuous filaments have a fineness of 1 to 5 denier, and the filaments constituting the nonwoven fabric have a dry heat shrinkage at 130 ° C.
It is characterized by being 10% or less.

Further, the continuous filaments may be JIS L 10
The dry heat shrinkage at 130 ° C. measured according to
The content is preferably 0% or less, and the aliphatic polyester resin is preferably made of a polylactic acid polymer containing 80 mol% or more of an L-lactic acid unit or a D-lactic acid unit.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The thermoplastic biodegradable aliphatic polyester resin used in the biodegradable spunbonded nonwoven fabric of the present invention is a polylactic acid polymer, more preferably an L-lactic acid unit or a D-lactic acid unit. Is a polylactic acid polymer containing not less than 80 mol%. Lactic acid monomer has optically active carbon, and it is known that polylactic acid polymer has D-form and L-form which are optical isomers,
When both are copolymerized, the melting point decreases, and when the optical purity, which is the ratio of L-form or D-form, is too low, the melting point is too low, so that good spinnability, which is one of the objects of the present invention, cannot be obtained. . The optical purity of the lactic acid unit in the polylactic acid polymer used is preferably at least 80 mol%, more preferably at least 95 mol%, even more preferably at least 98 mol%.

In general, when lactic acid is produced by fermentation, L-form is produced. Therefore, L-lactic acid is industrially more easily available in large quantities and at low cost. It is mainly composed of lactic acid. However, D
-Even with a polymer mainly composed of lactic acid, the same physical properties as those of L-lactic acid can be obtained.

JIS of polylactic acid polymer used in the present invention
K 7210 (190 ° C., 2.16
The melt flow rate measured with a load of 5 kg is 5 to 50 g.
A range of / 10 minutes is suitable. The polylactic acid polymer having a melt flow rate of less than 5 g / 10 minutes has a melt viscosity that is too high in the production method of the present invention in which the melt spinning temperature is higher than the melting point of the resin by 30 to 70 ° C. Spinning may not be easy and is not suitable for operation. Conversely, if the melt flow rate exceeds 50 g / 10 minutes, the melt viscosity is too low, and yarn breakage frequently occurs in the spinning process,
Not only the formation of the obtained nonwoven fabric is deteriorated, but also the strength may be reduced, which is not suitable for operation.

The polylactic acid polymer may contain, if necessary, various additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, and other additives such as a lubricant, a wax, a coloring agent, and a crystallization accelerator. It can be added within a range that does not impair the effects of the invention.

A polylactic acid polymer containing at least 80 mol% of an L-lactic acid unit or a D-lactic acid unit is hydrophilic, and contains water in the polymer. If this is done, the polymer will be decomposed, so it is necessary to carry out a drying treatment prior to spinning. The water content of the polymer is 0.2% by weight or less, preferably 0.05% by weight or less.

When a non-woven fabric is manufactured, a polylactic acid polymer containing at least 80 mol% of an L-lactic acid unit or a D-lactic acid unit is heated and melted in an extrusion spinning machine, and the spinning temperature is determined by the melting point of the resin. Higher by 30-70 ° C. When the melting temperature is higher than the melting point of the polymer by less than 30 ° C., the viscosity of the melted resin is high, and if the melting temperature is not increased, the melt spinning at a high speed becomes difficult, and the spinning at a high temperature is performed on the die surface. Stains easily occur, which is not suitable for operation. On the other hand, if the melting temperature is higher than the melting point of the resin by more than 70 ° C., the temperature difference from the melting point of the resin is too large, so that the cooling becomes difficult when spinning the resin from a large number of spinnerets of the extrusion spinning machine, Not only is it easy to cause fusion or thread breakage, resin stability is reduced, and decomposition may occur.

The continuous continuous fiber of the present invention can be obtained by using a conventionally known melt spinning apparatus for spunbonded nonwoven fabric. At this time, the amount of the resin discharged per minute per hole from the die hole of the melt extrusion spinning machine was 0.2 to 1.2 g /
It is preferable to be in the range of min / hole. If the amount of the resin to be discharged is less than 0.2 g / min / hole, it is necessary that the stretching by the ejector is almost unstretched when the fineness is within a specific range, and it is difficult to obtain heat resistance. Not suitable because it can be. Conversely, when the discharge amount of the resin exceeds 1.2 g / min / hole, the fineness of the fiber obtained even when stretched by high-speed air by an ejector becomes large, and thus a good texture of the obtained nonwoven fabric can be imparted. Not suitable because it may not be possible.

After being extruded from the spinneret of the melt extrusion spinning machine and spun, it is drawn by high-speed air by an ejector, stretched, and a number of long fiber filaments formed are applied to an impingement plate to triboelectrically charge and charge. The fiber is opened by the repulsive force of In this case, as a charging method, corona discharge treatment can be performed at various positions of the melt spinning device. A number of uniformly opened filaments are then deposited on a support.

The dry heat shrinkage at 130 ° C. of the long fiber of the present invention is 20% or less. If the dry heat shrinkage at 130 ° C. exceeds 20%, the fibers shrink in the heat bonding step during nonwoven fabric processing, and not only the texture deteriorates, but also
In some cases, it may be difficult to process the nonwoven fabric.

The dry heat shrinkage at 130 ° C. of the part of the nonwoven fabric obtained by heat bonding which is outside the self-bonding area is 10% or less. If the dry heat shrinkage at 130 ° C. of the fibers outside the self-fusing area of the nonwoven fabric exceeds 130%, the dimensional stability of the nonwoven fabric may be deteriorated, which is not suitable.

The average fineness of the long fibers of the present invention is in the range of 1 to 5 denier. If the average fineness of the long fiber exceeds 5 denier, the fiber diameter becomes too large, and the softness of the obtained biodegradable spunbonded nonwoven fabric may be impaired, which is not suitable. Conversely, if the long fiber has an average fineness of less than 1 denier, yarn breakage occurs frequently during spinning, and the productivity of the biodegradable spunbonded nonwoven fabric is significantly reduced.

The basis weight of the web formed by collecting and depositing on the support is in the range of 10 to 120 g / m ² .
If the basis weight is less than 10 g / m ² , sufficient strength cannot be imparted to the nonwoven fabric, which is not suitable. Conversely, if the basis weight exceeds 120 g / m ² , the texture of the obtained nonwoven fabric may become hard, which is not suitable.

In the present invention, the long fibers accumulated on the support are provided with self-fusion areas at regular intervals for the purpose of imparting sheet-like shape retention and strength. The self-fusing area is formed by introducing the web between the heated uneven roll and the smooth roll, applying heat and pressure treatment, and fusing the portion corresponding to the convex portion of the uneven roll. . In this case, the temperature of the roll is 5 to 50 ° C. lower than the melting point of the polylactic acid polymer containing 80 mol% or more of the L-lactic acid unit or D-lactic acid unit used. If the difference between the roll temperature and the melting point of the resin is less than 5 ° C., the fibers will adhere to the roll during thermocompression treatment by the roll, causing a manufacturing trouble. Conversely, if the difference between the roll temperature and the melting point of the resin exceeds 50 ° C., the formation of the self-fused portion becomes insufficient, and the strength of the nonwoven fabric may be significantly reduced.

The linear pressure when the thermocompression treatment is performed with the uneven roll and the smooth roll is in the range of 10 to 80 kg / cm.
When the linear pressure is less than 10 kg / cm, formation of the self-fused area by the thermocompression bonding treatment may be insufficient.
If it exceeds kg / cm, the long fiber may be cut by the convex portion of the uneven roll during the thermocompression bonding process,
Any of them is not suitable because the strength of the nonwoven fabric decreases.

In the present invention, the area of each self-fusion zone is in the range of 0.03 to ⁴ mm ² . If the area of the self-fusing area is less than 0.03 mm ² , the strength of the obtained nonwoven fabric may be insufficient. Conversely, if the area of the self-fused area exceeds 4 mm ² , the resulting nonwoven fabric may be too hard, resulting in reduced flexibility.

The total area of the self-fused area is in the range of 2 to 30% of the total surface area of the biodegradable spunbond nonwoven.
If the total area of the self-fused area is less than 2%, the strength of the obtained nonwoven fabric may be insufficient. Conversely, if the self-fused area exceeds 30%, the obtained nonwoven fabric becomes too hard,
Flexibility may be reduced.

Generally, the dry heat shrinkage of the fiber cut from the non-woven fabric after the self-fusion treatment is smaller than that of the long fiber before the treatment. This is presumably because the portion other than the self-fused area was heated by the self-fusing process, causing a slight shrinkage.

As described above, continuous long fibers made of a polylactic acid polymer containing at least 80 mol% of L-lactic acid units or D-lactic acid units are provided at regular intervals with self-fusing zones between the long fibers. In the biodegradable spunbonded nonwoven fabric which has been thermally bonded, the fineness of the continuous filament before thermal bonding is 1
The fiber of about 5 denier, which is outside the self-bonding area of the nonwoven fabric, is cut out, and the biodegradable spunbonded nonwoven fabric having a dry heat shrinkage at 130 ° C. of 10% or less has a spinnability. Suitable for sanitary materials, medical base materials, clothing base materials, household base materials, industrial base materials, etc., because of its excellent workability during heat bonding with heat and excellent dimensional stability, flexibility and texture. It can be used for

[0033]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In Examples and Comparative Examples,% is% by weight unless otherwise specified.

Example 1 Melt flow rate: 10 g / 10 min, melting point: 163 ° C.
A polylactic acid polymer containing 99 mol% of L-lactic acid units of the above was prepared and melted by heating at 220 ° C. in a melt extruder.
0.8g / min / hole resin discharge per minute
After extruding from a large number of micropores and spinning, the spun filaments are stretched and stretched while being taken up by an ejector with high-speed air, and collected on a moving wire-made collecting support. The web was deposited and formed. The fineness of the obtained long fiber was 2.1 denier, and the dry heat shrinkage was 5.2%. The basis weight of the deposited web was 40 g / m ² .

Next, this laminated web was introduced between an uneven roll heated at 135 ° C. and a smooth roll, and a linear pressure of 30 kg was applied.
A biodegradable spunbonded nonwoven fabric was obtained by fusing a portion corresponding to the convex portion of the concave and convex roll at / cm. The area of each self-fusion zone was 0.12 mm ² , and the total area of the self-fusion zone was 4 area%.

The obtained biodegradable spunbond nonwoven fabric and long fiber were tested by the following test methods. The spinnability during sample preparation was also evaluated by the following method. Test method (1) Fineness of long fibers constituting spunbonded nonwoven fabric (referred to as fineness in Table 1) The fiber diameter of 50 long fibers constituting the nonwoven fabric was measured by an electron microscope, and the density was corrected and determined. The average value of fineness was defined as fineness (denier). (2) Dry heat shrinkage of long fibers constituting the spunbonded nonwoven fabric (referred to as long fiber heat shrinkage in Table 1) Measured according to JIS L1013. (3) Dry heat shrinkage of the fiber outside the self-bonding area of the spunbonded nonwoven fabric (referred to as cut-out fiber heat shrinkage in Table 1).
The single fiber was placed on a slide glass, and the fiber length before heating was measured with an optical microscope, and then a heating treatment was performed at 130 ° C. for 30 minutes. Calculate the shrinkage from the length. (4) Spinnability Evaluated by the number of yarn breaks during melt spinning. The evaluation was based on the following five levels. 5 points: No thread breakage, and spinning properties are extremely good. 4 points: There is almost no yarn breakage, and the spinnability is good. 3 points: There is a thread break, but there is no problem, and the spinnability is normal. 2 points: The thread breakage is considerably large, and the spinnability is poor. 1 point: The thread breakage is extremely large, and the spinnability is extremely poor. (5) Flexibility of spunbonded nonwoven fabric (referred to as nonwoven fabric flexibility in Table 1) The flexibility of the spunbonded nonwoven fabric was evaluated by feeling by touch. The sensory evaluation was performed in the following five stages. 5 ... very flexible. 4: It was flexible. 3: The flexibility was normal. 2: It was slightly inferior in flexibility. 1: The flexibility was inferior.

Example 2 A polylactic acid polymer containing 98 mol% of an L-lactic acid unit having a melt flow rate of 16 g / 10 min was prepared, heated and melted at 200 ° C. in a melt extruder, and resin was discharged per minute. After extruding and spinning from a number of micropores so that the amount becomes 1.1 g / min / hole, the spun filament group is stretched and drawn while being taken up by an ejector with high-speed air, and the moving wire trapping is performed. The web was collected and deposited on a collecting support to form a web. The fineness of the obtained long fiber was 2.4 denier, and the dry heat shrinkage was 13.1%. The basis weight of the deposited web was 30 g / m ² .

Next, this laminated web was introduced between a rough roll and a smooth roll heated to 135 ° C., and a linear pressure of 30 kg was applied.
A biodegradable spunbonded nonwoven fabric was obtained by fusing a portion corresponding to the convex portion of the concave and convex roll at / cm. The area of each self-fusion zone was 0.12 mm ² , and the total area of the self-fusion zone was 4 area%. The obtained nonwoven fabric was evaluated in the same manner as in Example 1.

Example 3 Melt flow rate: 11 g / 10 min, melting point: 163 ° C.
A polylactic acid polymer containing 99 mol% of L-lactic acid units of the above was prepared and melted by heating at 220 ° C. in a melt extruder.
0.5g / min / hole resin discharge per minute
After extruding from a large number of micropores and spinning, the spun filaments are stretched and stretched while being taken up by an ejector with high-speed air, and collected on a moving wire-made collecting support. The web was deposited and formed. The dry fiber heat shrinkage of the obtained long fiber was 11.7%, and the fineness was 1.2 denier. The basis weight of the deposited web was 40 g / m ² .

Next, this laminated web was introduced between a rough roll and a smooth roll heated to 135 ° C., and a linear pressure of 30 kg was applied.
A biodegradable spunbonded nonwoven fabric was obtained by fusing a portion corresponding to the convex portion of the concave and convex roll at / cm. The area of each self-fusion zone was 0.12 mm ² , and the total area of the self-fusion zone was 4 area%. The obtained nonwoven fabric was evaluated in the same manner as in Example 1.

Example 4 Melt flow rate: 11 g / 10 min, melting point: 163 ° C.
A polylactic acid polymer containing 98 mol% of the L-lactic acid unit is prepared and melted at 220 ° C. in a melt extruder.
1.1 g / min / hole resin discharge per minute
After extruding from a large number of micropores and spinning, the spun filaments are stretched and stretched while being taken up by an ejector with high-speed air, and collected on a moving wire-made collecting support. The web was deposited and formed. The dry fiber heat shrinkage of the obtained filament was 15.5%, and the fineness was 3.6 denier. The basis weight of the deposited web was 25 g / m ² .

Next, this laminated web was introduced between an uneven roll heated to 135 ° C. and a smooth roll, and a linear pressure of 30 kg was applied.
A biodegradable spunbonded nonwoven fabric was obtained by fusing a portion corresponding to the convex portion of the concave and convex roll at / cm. The area of each self-fusion zone was 0.12 mm ² , and the total area of the self-fusion zone was 4 area%. The obtained nonwoven fabric was evaluated in the same manner as in Example 1.

Comparative Example 1 Melt flow rate: 11 g / 10 min, melting point: 163 ° C.
A polylactic acid polymer containing 98 mol% of the L-lactic acid unit is prepared and melted at 220 ° C. in a melt extruder.
1.0 g / min / hole resin discharge per minute
After extruding from a large number of micropores and spinning, the spun filaments are stretched and stretched while being taken up by an ejector with high-speed air, and collected on a moving wire-made collecting support. The web was deposited and formed. The dry fiber heat shrinkage of the obtained filament was 24.3%, and the fineness was 4.7 denier. The basis weight of the deposited web was 40 g / m ² .

Next, the laminated web was introduced between a rough roll and a smooth roll heated to 135 ° C., and a linear pressure of 30 kg was applied.
A biodegradable spunbonded nonwoven fabric was obtained by fusing a portion corresponding to the convex portion of the concave and convex roll at / cm. The area of each self-fusion zone was 0.12 mm ² , and the total area of the self-fusion zone was 4 area%. The obtained nonwoven fabric was evaluated in the same manner as in Example 1.

Comparative Example 2 Melt flow rate: 11 g / 10 min, melting point: 163 ° C.
A polylactic acid polymer containing 99 mol% of L-lactic acid units of the above was prepared and melted by heating at 220 ° C. in a melt extruder.
0.5g / min / hole resin discharge per minute
After extruding from a large number of micropores and spinning, the spun filaments are stretched and stretched while being taken up by an ejector with high-speed air, and collected on a moving wire-made collecting support. The web was deposited and formed. The dry fiber heat shrinkage of the obtained long fiber was 27.1%, and the fineness was 2.6 denier. The basis weight of the deposited web was 40 g / m ² .

Next, this laminated web was introduced between a rough roll and a smooth roll heated to 135 ° C., and a linear pressure of 30 kg was applied.
A biodegradable spunbonded nonwoven fabric was obtained by fusing a portion corresponding to the convex portion of the concave and convex roll at / cm. The area of each self-fusion zone was 0.12 mm ² , and the total area of the self-fusion zone was 4 area%. The obtained nonwoven fabric was evaluated in the same manner as in Example 1.

Comparative Example 3 Melt flow rate: 25 g / 10 min, melting point: 163 ° C.
A polylactic acid polymer containing 98 mol% of the L-lactic acid unit is prepared and melted at 220 ° C. in a melt extruder.
0.5g / min / hole resin discharge per minute
After extruding from a large number of micropores and spinning, the spun filaments are stretched and stretched while being taken up by an ejector with high-speed air, and collected on a moving wire-made collecting support. The web was deposited and formed. The dry fiber shrinkage of the obtained filament was 4.8%, and the fineness was 0.8 denier. The basis weight of the deposited web was 40 g / m ² .

Next, this laminated web was introduced between a rough roll and a smooth roll heated to 135 ° C., and a linear pressure of 30 kg was applied.
A biodegradable spunbonded nonwoven fabric was obtained by fusing a portion corresponding to the convex portion of the concave and convex roll at / cm. The area of each self-fusion zone was 0.12 mm ² , and the total area of the self-fusion zone was 4 area%. The obtained nonwoven fabric was evaluated in the same manner as in Example 1.

Comparative Example 4 Melt flow rate: 10 g / 10 min, melting point: 162 ° C.
A polylactic acid polymer containing 99 mol% of the L-lactic acid unit was prepared and heated and melted at 200 ° C. in a melt extruder.
1.3 g / min / hole resin discharge per minute
After extruding from a large number of micropores and spinning, the spun filaments are stretched and stretched while being taken up by an ejector with high-speed air, and collected on a moving wire-made collecting support. The web was deposited and formed. The dry fiber heat shrinkage of the obtained filament was 19.5%, and the fineness was 5.2 denier. The basis weight of the deposited web was 40 g / m ² .

Next, this laminated web was introduced between a rough roll and a smooth roll heated to 135 ° C., and a linear pressure of 30 kg was applied.
A biodegradable spunbonded nonwoven fabric was obtained by fusing a portion corresponding to the convex portion of the concave and convex roll at / cm. The area of each self-fusion zone was 0.12 mm ² , and the total area of the self-fusion zone was 4 area%. The obtained nonwoven fabric was evaluated in the same manner as in Example 1.

[0051]

[Table 1]

As is clear from Table 1, when the conditions of the present invention are met, no thread breakage occurs when the resin is melt-spun by a melt extruder, and the resulting biodegradable spunbonded nonwoven fabric is excellent. It has flexibility and heat resistance (Examples 1 to 4).

On the other hand, when the dry heat shrinkage of the fiber cut from the biodegradable spunbond nonwoven fabric exceeds the specified range (Comparative Examples 1 and 2), the heat resistance becomes poor.
Flexibility is impaired by heat shrinkage. Further, when the fibers constituting the biodegradable spunbonded nonwoven fabric become smaller than the specified range (Comparative Example 3), yarn breakage during spinning frequently occurs, and productivity is remarkably deteriorated. When the fineness of the long fibers constituting the biodegradable spunbonded nonwoven fabric exceeds the specified range (Comparative Example 4), sufficient flexibility cannot be imparted.

[0054]

According to the present invention, while having biodegradability,
With excellent heat resistance and dimensional stability, a biodegradable spunbond nonwoven fabric can be obtained that can be widely used as a base material for hygiene and medical supplies, a base material for clothing, a home base material, an industrial base material, an agricultural material, etc. It is a great contribution to the industry.

Claims (3)

[Claims] 1. A biodegradable spunbonded nonwoven fabric in which continuous long fibers made of a biodegradable aliphatic polyester resin are heat-bonded at regular intervals by providing self-fusion areas between the long fibers. The fineness of the continuous filament is 1 to 5 denier, and the length of the filament constituting the nonwoven fabric is 1%.
A biodegradable spunbonded nonwoven fabric having a dry heat shrinkage at 30 ° C. of 10% or less. 2. The continuous filament according to JIS L 101
The dry heat shrinkage at 130 ° C. measured according to
The biodegradable spunbonded nonwoven fabric according to claim 1, which is 0% or less. 3. The biodegradable spunbonded nonwoven fabric according to claim 1, wherein the aliphatic polyester resin comprises a polylactic acid polymer containing at least 80 mol% of an L-lactic acid unit or a D-lactic acid unit.