JP3264720B2 - Biodegradable composite short fiber non-woven fabric - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable composite short-fiber nonwoven fabric which is biodegradable , has excellent mechanical strength and dimensional stability, is highly flexible, and has thermal adhesiveness. .

[0002]

2. Description of the Related Art Conventionally, nonwoven fabrics of viscose rayon short fibers obtained by a dry method or a solution immersion method, nonwoven fabrics of kipura rayon or viscose rayon long fibers obtained by a wet spunbond method, chitin, atelocollagen, etc. Various biodegradable nonwoven fabrics such as a nonwoven fabric made of a natural chemical fiber and a spunlace nonwoven fabric made of cotone are known. However, in these conventional biodegradable nonwoven fabrics, the mechanical strength of the constituent materials of the nonwoven fabric itself is low and hydrophilic, so that the mechanical strength during water absorption / wetting is remarkably reduced. There were various problems such as poor stability, poor flexibility, and lack of thermal adhesiveness because the material itself is non-thermoplastic.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a nonwoven fabric having biodegradability, excellent mechanical strength and dimensional stability, high flexibility, and heat adhesion. It is an object of the present invention to provide a conjugate short fiber nonwoven fabric suitable for the above.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention provides a biodegradable conjugate short fiber having a core portion composed of a high-melting-point biodegradable thermoplastic polymer component and a sheath portion composed of a low-melting-point biodegradable thermoplastic polymer component. The present invention provides a biodegradable conjugate short fiber nonwoven fabric, which is constituted, and wherein constituent fibers are thermally bonded to each other at a pressure contact area ratio of 5 to 50% .

Further, the present invention provides a biodegradable composite short-circuit comprising a core composed of a high-melting-point biodegradable thermoplastic polymer component and a sheath portion composed of a biodegradable thermoplastic-polymer component having a lower melting point than the above polymer. Non- woven biodegradable conjugate short fibers comprising fibers and the constituent fibers being three-dimensionally entangled with each other
The gist is a cloth .

Next, the present invention will be described in detail. The biodegradable thermoplastic polymer in the present invention is a thermoplastic aliphatic polyester polymer having biodegradability, and is composed of, for example, polyglycolic acid or polylactic acid such as poly (α-hydroxy acid). Polymers or copolymers thereof, and poly (ω-hydroxyalkanoates) such as poly (ε-caprolactone) and poly (β-propiolactone), and poly-3-hydroxypropionate. , Poly-3-hydroxybutyrate, poly-3-
Hydroxycaprolate, poly-3-hydroxyheptanoate, poly-3-hydroxyoctanoate, and poly-3-hydroxyvalerate and poly-4-
Poly (β-) such as a copolymer with hydroxybutyrate
Hydroxyalkanoate). Further, as those comprising a condensation polymer of glycol and dicarboxylic acid, for example, polyethylene oxalate, polyethylene succinate, polyethylene adipate, polyethylene azelate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, polybutylene sebacate, Examples thereof include polyhexamethylene sebacate, polyneopentyl oxalate, and a copolymer thereof.
Further, the aliphatic polyester, polycapramid (nylon 6), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 6)
6), aliphatic polyester amide copolymers which are co-condensed with aliphatic polyamides such as polyundecanamide (nylon 11) and polylaurolactamide (nylon 12). In the present invention, a thermoplastic polymer other than those described above as the biodegradable thermoplastic polymer can be used as long as it is biodegradable. In the present invention, the above-mentioned thermoplastic polymer having biodegradability, if necessary, for example, various additives such as matting agents, pigments, light stabilizers, heat stabilizers, antioxidants, etc. Can be added in a range that does not impair the effects of the present invention.

The conjugate short fibers composed of a biodegradable thermoplastic polymer constituting the nonwoven fabric of the present invention are composed of two kinds of polymers having different melting points selected from the above polymers by 3 ° C. or more and 150 ° C. or less. It is composed of a polymer component, wherein the core portion is composed of a high-melting-point biodegradable thermoplastic polymer component, and the sheath portion is composed of a low-melting-point biodegradable thermoplastic polymer component than the polymer. It is joined so as to have a concentric core-sheath type composite form in which both polymer components are arranged. In this conjugate short fiber, the difference in melting point between the two polymer components is 3 ° C.
When a non-woven web is prepared using the obtained fibers and subjected to a heat treatment to obtain a non-woven fabric, not only the low-melting polymer component but also the high-melting polymer component is softened and melted. Therefore, in the present invention, the difference in melting point is 3 ° C. or more, preferably 5 ° C. or more, and more preferably 10 ° C. or more. On the other hand, if the difference in melting point exceeds 150 ° C., the difference in melting point between the two polymer components is so large that it is difficult to control the spinning temperature in the spinning nozzle pack when performing composite spinning using both polymers. . In the present invention, when a thermoplastic polymer component having a melting point of 60 ° C. or more, preferably 80 ° C. or more, and more preferably 100 ° C. or more is employed as the biodegradable thermoplastic polymer component, the short fiber having the sheath portion is used. When a non-woven fabric is used, a certain heat resistance can be provided to the non-woven fabric, which is preferable. In this conjugate short fiber, the conjugate ratio, that is, the weight ratio of the sheath polymer component to the core polymer component is preferably 1/5 to 5/1. When the ratio of the polymer component in the sheath portion to the polymer component 1 in the core portion exceeds 5, the strength of the short fiber is reduced, or the non-woven fabric obtained by using the short fiber becomes hard and the texture deteriorates. To do
On the other hand, when the ratio of the polymer component of the sheath portion to the polymer component 5 of the core portion is less than 1, the non-woven fabric obtained by heat-bonding the fibers using this short fiber is used to form the heat-bonded portion between the constituent fibers. In the present invention, the composite ratio is set to 1/5 to 5/1, preferably 1/2 to 2/1.

The conjugate short fibers have a single fiber fineness of 1.
When the single fiber fineness is less than 1.0 denier, the card permeability at the time of producing a card web is inferior. On the other hand, when the single fiber fineness exceeds 20 denier, this short fiber is used. The resulting non-woven fabric has a coarse and hard texture and is inferior in quality.

The nonwoven fabric according to the present invention is composed of the conjugate short fibers, and the constituent fibers are partially thermally bonded to each other. Further, the nonwoven fabric is composed of the conjugate short fibers, and the constituent fibers are tertiary. It is originally confounded. This partial thermal bonding is formed by a known thermal bonding process, and the three-dimensional confounding is formed by a known so-called high-pressure liquid flow process. Alternatively, the form as a nonwoven fabric is maintained by three-dimensional confounding, and the nonwoven fabric exhibits excellent mechanical strength and dimensional stability.

[0010] The nonwoven fabric comprising the conjugate short fibers in the present invention preferably has a basis weight of 20 g / m ² or more. In this nonwoven fabric, the basis weight is 20 g / m
^If it is less than ² , handling properties are inferior during nonwoven fabric production,
In particular, if the basis weight is less than 10 g / m ² , the strength of the nonwoven fabric itself is low, the quality of the nonwoven fabric is poor, such as roughening, or the productivity in producing the nonwoven fabric is unfavorably reduced.

[0011] The nonwoven fabric of the present invention is a known nonwoven fabric.
It can be manufactured efficiently by the method. That is, always
By the method, whether the thermoplastic polymer having biodegradability
The melting point selected from 3 ° C or more and 150 ° C or less
Molten composite spinning of two types of polymer and cooling air flow
Alternatively, after cooling using cooling water, take up
Elongated fiber yarn or continuous without winding
Cold stretching or hot stretching in one or more stages
Is applied to the obtained drawn continuous fiber yarn, for example, using a staple fiber.
After applying a predetermined mechanical crimp using gbox
Or after applying a predetermined crimp by heat shrinkage treatment,
Cut into long fibers into short fibers, and then use the obtained short fibers as raw cotton
And carding using a carding machine to create a card web
Heat-bonding the resulting card web
Obtained by partially thermally bonding synthetic fibers to each other
Can be. Alternatively, apply high pressure liquid to the resulting card web
Flow treatment to make the constituent fibers three-dimensionally entangled.
And can be obtained by Spinning temperature for melt spinning
The degree depends on the melting point and the degree of polymerization of the polymer to be used.
The temperature is desirably 20 to 300 ° C. Spinning temperature is 120
If the temperature is lower than ℃, it becomes difficult to melt-extrude the polymer.
On the other hand, when the spinning temperature exceeds 300 ° C., thermal decomposition of the polymer becomes significant.
And high strength fibers cannot be obtained.
Not preferred. When drawing undrawn long fiber yarn
Depends on the strength level of the target short fiber
However, it is usually 2.0 to 4.0 times, whereby 3.0 g
/ Short fibers with tensile strength not less than denier
it can.

When the web is subjected to a partial thermal bonding treatment, a known method can be adopted. For example, a method in which the web is passed between a heated emboss roller and a roller having a smooth surface such as a metal roller, a method using a hot-air drying device, or a method using an ultrasonic welding device. When using a heated embossing roller to partially heat bond the fibers present in the embossed pattern portion,
When the embossing roller has a pressure contact area ratio of 5 to 50%, and if the pressure contact area ratio is less than 5%, the mechanical strength of the nonwoven fabric is reduced due to a small number of point-like fused areas, and good dimensional stability can be obtained. On the other hand, if the pressed area ratio exceeds 50%, the nonwoven fabric becomes rigid and the flexibility is impaired. Further, the roller temperature is usually preferably set to a temperature lower by about 5 to 50 ° C. than the melting point of the low melting point thermoplastic polymer constituting the sheath portion, and by appropriately selecting this temperature, the adhesive force between the fibers is improved. It is possible to obtain a nonwoven fabric which is high, that is, excellent in mechanical strength and dimensional stability, and which is rich in flexibility. The emboss pattern in the case of using the hot emboss roller is not particularly limited as long as the pressure contact area ratio is in the range of 5 to 50%, and is round, elliptical, rhombic, triangular, T-shaped, and well. Any shape such as a mold may be used. Also, when using a hot air drying device to partially heat bond the fibers at the intersection of the fibers, the processing temperature depends on the processing time,
Usually, the temperature is preferably in the range of not less than the melting point of the low melting point thermoplastic polymer constituting the sheath portion and about 10 ° C. lower than the melting point of the high melting point thermoplastic polymer. In addition, these
For example, the partial thermal bonding using a hot embossing roller, a hot air drying device, or an ultrasonic fusing device may be either a continuous process or a separate process.

In performing the high-pressure liquid flow treatment on the web, a known method can be employed. For example, a device having a large number of injection holes having a hole diameter of 0.05 to 1.0 mm, particularly 0.1 to 0.4 mm is used.
There is a method of injecting a high-pressure liquid of kg / cm ² G from the injection hole. The arrangement of the injection holes is arranged in a row in a direction orthogonal to the traveling direction of the web. This processing may be performed on either one side or both sides of the web, but particularly in the case of single-side processing, the processing is performed by arranging the injection holes in a plurality of rows and lowering the injection pressure in the previous stage and increasing it in the later stage. Thus, a nonwoven fabric having a uniform and dense entangled form and a uniform formation can be obtained. Generally, water or hot water is used as the high-pressure liquid. The distance between the injection hole and the web is 1 to 15
cm. If this distance is less than 1 cm, the formation of the web will be disturbed, while if this distance exceeds 15 cm, the impact force when the liquid flow collides with the web will be reduced, and three-dimensional confounding will not be sufficiently performed. Is also not preferred.
This high pressure liquid flow treatment may be a continuous step or a separate step. After applying the high pressure liquid flow treatment, excess moisture is removed from the web. When removing the excess moisture, a known method can be adopted. For example,
The excess water is removed to some extent using a squeezing device such as a mangle roll, and the remaining water is subsequently removed using a drying device such as a continuous hot air dryer.

[0014]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In the following examples, measurement of each characteristic value was performed by the following method.

Melting point (° C.): Measured with a differential scanning calorimeter DSC-2 manufactured by Perkin Elmer Co. under the condition of a heating rate of 20 ° C./min. Melting point.

Melt flow rate value (g / 10 minutes): A
The measurement was performed according to the method described in STM D1238 (L). Tensile strength of short fiber (g / denier): JIS-L-
The measurement was performed according to the method described in 1013.

KGSM tensile strength (kg) of nonwoven fabric: JI
The measurement was carried out according to the method described in SL-1096A. That is, a sample piece 1 having a sample length of 10 cm and a sample width of 5 cm
Create a zero point, and for each sample piece,
Using a constant speed elongation type tensile tester (Tensilon UTM-4-1-100 manufactured by Toyo Baldwin Co., Ltd.), a tensile speed of 10 c
It was stretched at m / min, and the average value of the obtained load values at break (kg) was converted to a per-grain weight of 100 g / m ² to obtain a KGSM tensile strength (kg). Example 1 A polyethylene succinate polymer having a melting point of 102 ° C. and a melt flow rate of 5 g / 10 min was used as a low melting point component in the sheath, and a melting point of 118 ° C. and a melt flow rate of 5 g / 1.
A 0 minute polybutylene succinate polymer was used as the high melting point component of the core, and both of these polymers were melted and passed through a spinneret having 36 composite spinning holes having a hole diameter of 0.5 mm to a spinning temperature of 2.
At 30 ° C. and a composite ratio (weight ratio) of 1/1, the composite spinning is performed in a concentric core / sheath type, and the spun yarn is cooled using a cooling air flow having a temperature of 20 ° C., and an oil agent is applied. Winding speed 10
The film was once wound at 00 m / min to obtain an undrawn yarn. Then
The obtained undrawn yarn was subjected to a total draw ratio of 3.8 and a temperature of 6
One-stage hot drawing is performed using a heating roll at 0 ° C., and the obtained drawn yarn is 17/2 using a stuffing box.
A 5 mm mechanical crimp was applied and cut to a length of 51 mm.
Cotton of a concentric core-sheath composite short fiber having a single fiber fineness of 2.0 denier was obtained. The obtained conjugate short fiber has a tensile strength of 4.1 g.
/ Denier and had practically sufficient mechanical strength. Further, when the short fibers were buried in the soil for two months and then taken out and observed, it was confirmed that the short fibers had lost their form as fibers and had excellent biodegradability.

The staple cotton was used as raw cotton and carded using a carding machine to produce a card web having a basis weight of 38 g / m ^2.
The fibers were passed through an embossing roll heated to 0 ° C. and having a press contact area ratio of 15% and a smoothing roll at the same temperature to partially heat-bond the fibers to each other to obtain a nonwoven fabric. The obtained non-woven fabric is KGS
5. M tensile strength is 10.8 kg / 5cm in the longitudinal direction and 6 in the lateral direction.
At 9 kg / 5 cm, mechanical strength and dimensional stability were excellent. When the nonwoven fabric was buried in the soil for two months and then taken out and observed, it was confirmed that the nonwoven fabric had disappeared and had excellent biodegradability. Example 2 The short fiber cotton obtained in Example 1 was used as raw cotton and carded using a carding machine to produce a card web having a basis weight of 38 g / m ^2. The obtained card web was placed on an 80 mesh wire mesh. And subjected to high-pressure liquid flow treatment to three-dimensionally entangle the constituent fibers. For high pressure liquid flow treatment, a pore size of 0.
Using a high pressure columnar water flow treatment device in which 12 mm injection holes are arranged in three groups with a hole interval of 0.6 mm, a water pressure of 60 kg / c
Under the condition of m ^2, a columnar water flow was applied from above the web. This treatment was performed three times from the front and back of the web. Next, after removing excess moisture from the obtained treated web using a mangle roll, the web was subjected to a drying treatment at a temperature of 70 ° C. using a hot air drier to obtain a nonwoven fabric.
The obtained nonwoven fabric has a KGSM tensile strength of 12.0 in the machine direction.
kg / 5 cm and 8.1 kg / 5 cm in the lateral direction, the mechanical strength and dimensional stability were excellent and the flexibility was high. When the nonwoven fabric was buried in the soil for two months and then taken out and observed, it was confirmed that the nonwoven fabric had disappeared and had excellent biodegradability.

[0019]

The biodegradable conjugate short fiber nonwoven fabric of the present invention comprises:
The core is composed of a high melting point biodegradable thermoplastic polymer component,
And the sheath portion is composed of short fibers composed of a biodegradable thermoplastic polymer component having a lower melting point than the polymer, and has biodegradability, excellent mechanical strength and dimensional stability,
It is highly flexible and has excellent thermal adhesion . Soshi
The composite short-fiber nonwoven fabric has the above-described excellent properties, and is used as a material for sanitary materials such as diapers and sanitary articles, a disposable towel, a wiping cloth, a base cloth for wrapping materials, and a household or commercial fabric. It is suitable as a material for living related materials such as dust collection bags and other waste treatment materials. Moreover, this nonwoven fabric is useful from the viewpoint of protecting the natural environment because it is completely decomposed and disappears when left in an environment where a large number of microorganisms are present, such as soil or water, after use, or it is made into a compost, for example. Since it can be reused as fertilizer, it is useful from the viewpoint of resource reuse.

Continuation of front page (72) Inventor Takashi Inagaki 23, Uji Kozakura, Uji City, Kyoto Prefecture Unitika Central Research Laboratory (56) References JP-A-6-248516 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) D01F 8/04 D01F 8/14 D04H 1/46 D04H 1/54

Claims (3)

(57) [Claims] 1. A core comprising a biodegradable thermoplastic polymer component having a high melting point, and a sheath portion comprising a biodegradable conjugate short fiber comprising a biodegradable thermoplastic polymer component having a lower melting point than the polymer. A biodegradable conjugate short fiber nonwoven fabric, wherein constituent fibers are thermally bonded to each other at a pressure contact area ratio of 5 to 50% . 2. A core comprising a biodegradable thermoplastic polymer component having a high melting point and a sheath portion comprising a biodegradable conjugate short fiber comprising a biodegradable thermoplastic polymer component having a lower melting point than the polymer. A biodegradable conjugate short fiber nonwoven fabric, wherein the constituent fibers are three-dimensionally entangled with each other. 3. The biodegradable composite short fiber nonwoven fabric according to claim 1, wherein the biodegradable thermoplastic polymer is an aliphatic polyester-based polymer or an aliphatic polyesteramide-based copolymer. .