JPH06200458A - Biodegradable short fiber non-woven fabric - Google Patents

Abstract

PURPOSE:To obtain the biodegradable short fiber non-woven fabric having proper hydrophilicity and hydrophobicity and excellent in mechanical strength and dimensional stability by blending the short fibers of a biodegradable thermoplastic polymer with cellulosic short fibers and subsequently partially heat- adhering the constituent fibers of the blended product to each other. CONSTITUTION:A biodegradable thermoplastic polymer having a melting point of >=60 deg.C, such as polyethylene succinate or polycaprolactone, is melt-spun to form biodegradable thermoplastic short fibers. 95-5wt.% of the short fibers and 5-95wt.% of cellulosic short fibers such as cotton are blended with each other and subsequently carded to form a carded web. The carded web is passed between a heated embossed roll and a smooth roll to partially heat-adhere the fibers to each other, thus providing the objective biodegradable short fiber non-woven fabric.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable short fiber nonwoven fabric having biodegradability, moderate hydrophilicity and hydrophobicity, and excellent mechanical strength and dimensional stability.

[0002]

2. Description of the Related Art Conventionally, viscose rayon short fiber non-woven fabric obtained by a dry method or a solution dipping method, Kyupra rayon long fiber non-woven fabric obtained by a wet spun bond method, viscose rayon long fiber non-woven fabric, chitin, atelocollagen, etc. Various biodegradable non-woven fabrics such as non-woven fabrics made of natural chemical fibers and spunlace non-woven fabrics made of Kotton are known. However, in these conventional biodegradable nonwoven fabrics, the mechanical strength of the constituent material itself of the nonwoven fabric is low and hydrophilic, so that the mechanical strength is remarkably lowered when absorbing / wetting water, and the shrinkage occurs during repeated drying / wetting. It has various problems such as a large inferior dimensional stability and the fact that the material itself is non-thermoplastic and does not have thermal adhesiveness. On the other hand, in recent years, a biodegradable nonwoven fabric composed of thermoplastic fibers has been proposed to solve the above problems, but this nonwoven fabric has poor hydrophilicity and is practically used in a field of application where a certain water retention capacity is required. It could not be used for.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and has biodegradability, moderate hydrophilicity and hydrophobicity, and excellent biodegradability in terms of mechanical strength and dimensional stability. It is intended to provide a non-woven fabric. Further, the present invention has excellent mechanical properties not only under dry conditions but also under water absorption / wet conditions, and has extremely small shrinkage even after repeated drying / wet conditions and excellent biodegradability. It is intended to provide a short fiber non-woven fabric.

[0004]

The present inventors have arrived at the present invention as a result of extensive studies to solve the above problems. That is, the present invention provides 95 to 5% by weight of short fibers made of a thermoplastic polymer having biodegradability and 5 to 9% of cellulose-based short fibers.
The gist of the present invention is a biodegradable short fiber non-woven fabric characterized in that 5% by weight is mixed and the constituent fibers are partially heat-bonded to each other.

Next, the present invention will be described in detail. The biodegradable thermoplastic polymer in the present invention is a thermoplastic aliphatic polyester polymer, for example, a polymer composed of polyglycolic acid or polylactic acid such as poly (α-hydroxy acid) or These copolymers also
Poly (ω-hydroxyalkanoate) such as poly (ε-caprolactone), poly (β-propiolactone)
In addition, poly-3-hydroxypropionate, poly-3-hydroxybutyrate, poly-3-hydroxycaprolate, poly-3-hydroxyheptanoate,
Mention may be made of poly-3-hydroxyoctanoate and poly (β-hydroxyalkanoates) such as copolymers thereof with poly-3-hydroxyvalerate and poly-4-hydroxybutyrate. Examples of the polycondensate of glycol and dicarboxylic acid include polyethylene oxalate, polyethylene succinate, polyethylene adipate, polyethylene azelate, polybutylene oxalate, polybutylene succinate, polybutylene adipate, polybutylene sebacate. , Polyhexamethylene sebacate, polyneopentyl oxalate or copolymers thereof. Furthermore, the aliphatic polyester and polycapramide (nylon 6), polytetramethylene adipamide (nylon 4)
6), polyhexamethylene adipamide (nylon 6
6), polyundecanamid (nylon 11), polylaurolactamide (nylon 12), and a cocondensation polymer with an aliphatic polyamide. In the present invention, a thermoplastic polymer other than those described above can be used as long as it has biodegradability. In the present invention, the above-mentioned biodegradable thermoplastic polymer may be added, if necessary, to
For example, various additives such as matting agents, pigments, light stabilizers, heat stabilizers and antioxidants can be added within a range that does not impair the effects of the present invention.

In the present invention, when the thermoplastic polymer having biodegradability has a melting point of 60 ° C. or higher, preferably 80 ° C. or higher, more preferably 100 ° C. or higher, a short polymer consisting of this polymer is used. When a non-woven fabric is formed using fibers, it is preferable because the non-woven fabric can have a certain heat resistance.

The short fibers composed of the above-mentioned biodegradable thermoplastic polymer in the present invention are composed of the above-mentioned polymer, but in addition to those composed of a single biodegradable polymer. The two or more kinds of biodegradable polymers may be composite staple fibers having various composite forms such as a concentric core-sheath type, an eccentric core-sheath type or a side-by-side type. Further, the short fibers in the present invention may have various irregular cross-sections such as triangles and stars or hollow cross-sections in addition to the normal circular cross-section. The short fibers in the present invention have a monofilament fineness of 0.3 to 20 denier, and if the monofilament fineness is less than 0.3 denier, the card passing property in producing a card web is poor. However, if the single fiber fineness exceeds 20 denier, the texture of the resulting non-woven fabric becomes rough and the quality is inferior.

The cellulosic short fibers in the present invention are natural fibers such as cotton and hemp, and chemical fibers made of natural products such as various rayon fibers and chitin. In addition to these fibers, biodegradability is also considered. It is not particularly limited as long as it has fibers.

The biodegradable short fiber nonwoven fabric of the present invention is
95 to 5% by weight of short fibers made of the above polymer and 5 to 95% by weight of cellulose-based short fibers are mixed. In this non-woven fabric, when the short fibers made of the polymer exceeds 95% by weight, the water retention of the non-woven fabric is inferior. It is not desirable because it does not develop the sex.

The nonwoven fabric in the present invention is one in which the constituent fibers thereof, that is, the biodegradable short fibers, and the biodegradable short fibers and the cellulosic short fibers are partially heat-bonded. . This partial thermal bonding is
It is formed by a known heat-bonding treatment, whereby the shape of the non-woven fabric is maintained, and the non-woven fabric exhibits excellent mechanical strength and dimensional stability.

The non-woven fabric in the present invention preferably has a basis weight of 20 g / m ² or more. If the basis weight of this non-woven fabric is less than 20 g / m ² , the handling property during production of the non-woven fabric is poor, which is not preferable.

The nonwoven fabric of the present invention can be manufactured by the following method. First, the above-mentioned biodegradable thermoplastic polymer is melt-spun by a conventional method, and the spun yarn is cooled with a cooling air flow or cooling water and then once wound into an undrawn yarn, or Continuously without winding, this is subjected to cold drawing or hot drawing in one or more steps, and then the obtained drawn yarn is subjected to mechanical crimping, for example, using a stuffing box, or heat shrinkage. Crimping is given by the treatment and cut into a predetermined length to obtain short fibers. The spinning temperature at the time of melt spinning depends on the melting point and the degree of polymerization of the polymer to be used, but is usually preferably 120 to 300 ° C. If the spinning temperature is less than 120 ° C, melt extrusion of the polymer becomes difficult, while the spinning temperature is 300 ° C.
If it exceeds the above range, the thermal decomposition of the polymer becomes remarkable and a high strength fiber cannot be obtained, either of which is not preferable. The total draw ratio when drawing the undrawn yarn depends on the strength level of the target short fiber, but is usually 2.0 to 4.0 times, and thereby the tensile strength of 3.0 g / denier or more is obtained. It is possible to obtain short fibers having the same.

Separately, cellulosic short fibers are prepared. The cellulosic short fibers used in the present invention are mainly the above-mentioned natural fibers such as Kotton and hemp, and various kinds of rayon fibers and chemical fibers composed of natural products such as chitin. When high mechanical strength and quality are required, it is better to use natural fibers mainly composed of kotton rather than rayon-based recycled fiber.

Next, the obtained biodegradable short fibers and the cellulosic short fibers are mixed in the above ratio and carded by using a carding machine to prepare a card web. A heat-bonding treatment is performed to partially heat-bond the constituent fibers. A publicly known method can be adopted for the partial heat-bonding treatment. For example, there is a method of passing a web between rollers that include a heated embossing roller and a metal roller having a smooth surface, a method of using a hot air drying device, or a method of using an ultrasonic fusing device.
When the fibers existing in the embossing pattern part are partially heat-bonded by using the heated embossing roller, the pressure contact area ratio of the embossing roller is set to 5 to 50%, and the pressure contact area ratio is less than 5%. There are few fusion zones and the mechanical strength of the non-woven fabric is reduced, and good dimensional stability cannot be obtained. On the other hand, when the pressure contact area ratio exceeds 50%, the non-woven fabric becomes rigid and the flexibility is impaired. ， Neither is preferable. The roller temperature is usually set to a temperature about 10 to 20 ° C. lower than the melting point of the biodegradable thermoplastic polymer, and by appropriately selecting this temperature, the adhesive force between fibers is high, that is, It is possible to obtain a non-woven fabric that has excellent mechanical strength and dimensional stability and is highly flexible.
The embossing pattern when using the hot embossing roller is
The pressure contact area ratio is not particularly limited as long as it is within the range of 5 to 50%, and is round, elliptical, rhombic, triangular, T
Any shape such as a letter shape or a well shape may be used. When the fibers are partially heat-bonded to each other at the crossing points of the fibers by using a hot air dryer, the treatment temperature depends on the treatment time, but is usually 5 or more than the melting point of the biodegradable thermoplastic polymer. ~ 15
It is preferable to set the temperature at about ℃. The partial heat-bonding treatment using, for example, a hot embossing roller, a hot air drying device or an ultrasonic fusing device may be a continuous process or a separate process.

[0015]

The biodegradable short fiber non-woven fabric of the present invention has the above-mentioned constitution, has biodegradability, appropriate hydrophilicity and hydrophobicity, and absorbs water / wet as well as under dry conditions. It has excellent mechanical strength properties and dimensional stability even under conditions, and this nonwoven fabric has excellent mechanical strength properties and dimensional stability not only under dry conditions but also under water absorption / wet conditions. , In general, hydrophobic biodegradable thermoplastic fibers and hydrophilic cellulosic fibers, which have little decrease in strength and have excellent dimensional stability under water-absorption / wet conditions, have uniform partial thermal adhesion points between the fibers. It is thought that this is due to the formation of a steric bond and the development of a three-dimensional bond structure in the nonwoven fabric.

[0016]

EXAMPLES Next, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the examples, each characteristic value was measured by the following method. Melting point (℃): Differential scanning calorimeter DS manufactured by Perkin Elma
Using a C-2 type, the measurement is performed at a temperature rising rate of 20 ° C./min,
The temperature that gives the extreme value in the obtained melting endothermic curve was taken as the melting point. Melt flow rate value (g / 10 minutes): ASTM D1
It was measured according to the method described in 238 (L). Short fiber tensile strength (g / denier): JIS-L-10
It was measured according to the method described in 13. Nonwoven fabric KGSM tensile strength (kg): JIS-L-10
It was measured according to the method described in 96A. That is, 10 sample pieces having a sample length of 10 cm and a sample width of 5 cm were prepared, and a constant speed elongation type tensile tester (Tensilon UTM manufactured by Toyo Baldwin Co., Ltd.) was used for each sample piece in the warp direction of the nonwoven fabric.
4-1-100) was used for elongation at a tensile speed of 10 cm / min, and the average value of the load values (kg) at cutting obtained was converted per unit weight per 100 g / m ^{2 of} KGSM tensile strength (k).
g). Area shrinkage (%): A plurality of sample pieces each having a sample length and a sample width of 25 cm were prepared, and each sample piece was subjected to a wet / dry treatment three times. Regarding the treatment conditions, the wet treatment temperature was room temperature, the treatment time was 30 minutes, the dry treatment temperature was room temperature, and the treatment time was 24 hours. At this time, the area S1 of the sample piece before the wet / dry treatment and the area S2 of the sample piece after the third wet / dry treatment were obtained, and the average value of the values calculated by the following equation (1) from the obtained S1 and S2 was calculated. The area shrinkage rate (%) was used. Area shrinkage (%) = [1- (S2 / S1)] × 100 ... (1)

Example 1 A polyethylene succinate chip having a melting point of 102 ° C. and a melt flow rate value of 5 g / 10 min was melted and passed through a spinneret having 36 spinning holes having a hole diameter of 0.5 mm at a spinning temperature of 230 ° C. Melt spinning, spun yarn temperature is 20
After cooling with a cooling air flow of ° C, an oil agent was applied, and the unstretched yarn was obtained by once winding at a winding speed of 1000 m / min. Then, the total draw ratio of the obtained undrawn yarn is 3.2.
As a result, a one-stage hot drawing is performed using a heating roll at a temperature of 60 ° C., a mechanical crimp of 18 pieces / 25 mm is applied to the obtained drawn yarn using a stuffing box, and a length of 51 mm.
Then, it was cut into short fiber cotton having a single fiber fineness of 2.2 denier and a tensile strength of 3.2 g / denier.

Next, 50% by weight of the obtained short-fiber cotton and 50% by weight of cotton (blistered cotton) having a length of 28 mm and a single fiber fineness of 1.5 denier were mixed, and a cotton carding machine was used. A card web having a basis weight of 40 g / m ² was formed by carding, and the obtained card web was heated to 90 ° C. and passed through an embossing roll having a pressing area ratio of 15% and a smooth roll having the same temperature. The two parts were partially heat-bonded to obtain a nonwoven fabric. The resulting nonwoven fabric has a KGSM tensile strength of 4.2 kg / 5 cm in the longitudinal direction and 2.6 kg / 5 cm in the transverse direction.
The area shrinkage was 1.9%, and the mechanical strength and dimensional stability were excellent. Further, when this non-woven fabric was embedded in soil for 2 months and then taken out and observed, it was confirmed that the non-woven fabric had lost its morphology and had excellent biodegradability.

Example 2 A polycaprolactone chip having a melting point of 60 ° C. and a melt flow rate value of 3 g / 10 min was melted to give a pore size of 0.5.
melt spinning at a spinning temperature of 265 ° C. through a spinneret having 36 mm spinning holes, cooling the spun yarn using a cooling air stream having a temperature of 15 ° C., applying an oil agent, and winding speed 1200 m / It was once wound in minutes to obtain an undrawn yarn. Then, the total draw ratio of the obtained undrawn yarn is set to 2.4 and 1
The cold drawing is performed, and the resulting drawn yarn is provided with 20/25 mm mechanical crimps using a stuffing box.
It was cut into a length of 51 mm to obtain short fiber cotton having a single fiber fineness of 2.4 denier and a tensile strength of 4.2 g / denier.

Next, 30% by weight of the obtained short fiber cotton and 70% by weight of a cotton (blistered cotton) having a length of 28 mm and a single fiber fineness of 1.5 denier were mixed, and a cotton carding machine was used. A card web having a basis weight of 40 g / m ² was prepared by carding, and the obtained card web was heated at a temperature of 50 ° C. and passed between an embossing roll having a pressing area ratio of 15% and a smooth roll having the same temperature. The two parts were partially heat-bonded to obtain a nonwoven fabric. The resulting non-woven fabric has a KGSM tensile strength of 3.7 kg / 5 cm in the longitudinal direction and 2.3 kg / 5 cm in the transverse direction.
The area shrinkage ratio was 2.8%, and the mechanical strength and dimensional stability were excellent. Further, when this non-woven fabric was embedded in soil for 2 months and then taken out and observed, it was confirmed that the non-woven fabric had lost its morphology and had excellent biodegradability.

[0021]

The biodegradable nonwoven fabric of the present invention comprises 95 to 5% by weight of short fibers composed of a biodegradable thermoplastic polymer and 5 to 95% by weight of cellulosic short fibers, and The constituent fibers are partially heat-bonded, have biodegradability, moderate hydrophilicity and hydrophobicity, and have excellent mechanical strength not only under dry conditions but also under water-absorption and wet conditions. It has extremely small shrinkage even after repeated drying and wetting, and has excellent dimensional stability. Moreover, since this non-woven fabric has excellent thermal adhesiveness, sewing is not required when the product is commercialized.

The non-woven fabric of the present invention is used as a material for agricultural, horticultural, and civil engineering materials used outdoors, especially vegetation sheets,
Suitable as a seed sheet, seed tape, and nursery bed material. In other words, conventional rayon-based non-woven fabrics and other biodegradable non-woven fabrics have poor dimensional stability due to the fact that the constituent materials of the non-woven fabrics themselves largely contract during repeated drying and wetting, so when the non-woven fabrics are laid on the ground, Although it has a problem that it partially floats to lower the ground contact rate and lowers the germination rate of seeds, the nonwoven fabric of the present invention has excellent dimensional stability as described above, and therefore has good ground contact with the ground. The seed germination rate can be improved. Moreover,
In the nonwoven fabric of the present invention, the nonwoven fabric itself is decomposed from the ground contact surface with the ground mainly by the enzyme released from the microorganisms in the soil to the outside of the cell, and finally disappears completely as the plant newly germinates and grows. It is also useful from the perspective of protecting the natural environment because it is returned to soil.

The nonwoven fabric of the present invention is also suitable as a material for a life-related material, particularly as a material for a life-related material such as a wet wiper used under wet conditions. In other words, conventional rayon-based nonwoven fabrics and various other biodegradable nonwoven fabrics have a problem that the mechanical strength of the nonwoven fabrics is low and hydrophilic, so that the mechanical strength of the nonwoven fabrics is significantly reduced when water is absorbed and wet. The constructed biodegradable nonwoven fabric has a problem that it cannot be put to practical use in an application field where hydrophilicity is poor and a certain water retention capacity is required, but the nonwoven fabric of the present invention has a mechanical strength. It has both water retention capacity and water retention capacity, and can be applied to application fields used under wet conditions such as wet wipers, which require a certain water retention capacity. It is also useful from the perspective of resource reuse.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshinari Yoshinari Unitika Central Research Institute, 23 Uji Kozakura, Uji City, Kyoto Prefecture

Claims (3)

[Claims] 1. Short fibers 95 to 5% by weight composed of a biodegradable thermoplastic polymer and cellulosic short fibers 5 to 95.
A biodegradable short-fiber non-woven fabric characterized by being mixed with the weight% and the constituent fibers are partially heat-bonded. 2. The biodegradable short fiber nonwoven fabric according to claim 1, wherein the biodegradable thermoplastic polymer is a polymer having a melting point of 60 ° C. or higher. 3. The biodegradable short fiber nonwoven fabric according to claim 1 or 2, wherein the cellulosic short fibers are Kotton.