JPH111857A - Filament nonwoven fabric and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce filament, nonwoven fabric excellent in mechanical characteristics and shape stability and having good flexibility in good operability. SOLUTION: A nonwoven fleece comprising multifoil cross section conjugate filament, composed of a high-melting point polymer component A having compatibility and low-melting point polymer component B, arranging the component A in the center part 1 and arranging the component B as 2-8 leaf parts is partially heat pressure-welded at a temperature from (Tm-40) deg.C to (Tm-5) deg.C [Tm: melting point ( deg.C) of the component B] by using an emboss roll at 4-40% pressure weld area ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a long-fiber nonwoven fabric which has excellent flexibility and is suitable for a wide range of fields such as medical and sanitary materials, living materials and industrial materials, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, in order to produce a long-fiber nonwoven fabric, a fiber-forming polymer is melt-spun, and the spun yarn is drawn and thinned by air soccer, and then deposited on a conveyor net to form a nonwoven fleece. A method of forming a long-fiber nonwoven fabric by hot-pressing the fleece and then pressing the fleece is adopted.

[0003] The most common long-fiber nonwoven fabric is composed of long fibers composed of a single polymer component. In the case of such a nonwoven fabric, it is necessary to lower the hot pressing temperature or to obtain a soft nonwoven fabric. In addition, it is necessary to reduce the proportion of the heat-pressed portion, and this causes problems such as poor mechanical properties and shape stability of the nonwoven fabric and fuzzing of the nonwoven fabric surface due to friction.

[0004] As a method of obtaining a long-fiber nonwoven fabric free of such a problem, a composite fiber having a high-melting polymer as a core component and a low-melting polymer as a sheath component is spun and drawn and thinned to form a nonwoven fleece. Then, there is known a method of producing a non-woven fabric by heat-pressing to make the adhesiveness of the sheath component apparent to adhere and bond the entangled points between the fibers (Japanese Patent Publication No. 54-38214).

According to this method, a nonwoven fabric having excellent mechanical properties and shape stability can be obtained due to the presence of the core component. However, since the entire fiber surface of the conjugate fiber is covered with the low melting point polymer, In the hot pressing process, not only the hot pressing portion, but also the low melting point polymer in the portion adjacent to the hot pressing portion is partially softened and then cured, so that the resulting nonwoven fabric has a problem of poor flexibility. .

Further, when a non-woven fabric is used as a carpet base fabric by needle punching, troubles may occur in the needle punching process and the quality of the product may be poor unless the conditions of the thermal pressing are strictly controlled. There was a problem of becoming. That is, if the welding temperature is too high,
If the temperature is too low, delamination tends to occur in the processed product, resulting in inferior product quality.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a long-fiber nonwoven fabric which is excellent in mechanical properties and shape stability and has good flexibility, and a method for producing the same.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and the gist thereof is as follows. 1. Multi-leaf cross section composite long fiber comprising compatible high-melting polymer component A and low-melting polymer component B, wherein component A is disposed at the center and component B is disposed as 2 to 8 leaves A non-woven fleece comprising a non-woven fleece partially hot-pressed and having a shape stability, wherein both component A and component B are exposed on the fiber surface. 2. The nonwoven fleece described in the preceding section obtained by the spunbonding method was embossed with an embossing roll having a pressed area ratio of 4 to 40%, at a temperature (Tm-40) to (Tm-5) ° C [Tm: component B
(Partial melting point (° C.)).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, component A and component B include:
Thermoplastic polymer having a fiber-forming property is used, specifically, polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate copolymerized with isophthalic acid, polyamide such as nylon 6, nylon 66, polyethylene, polypropylene, and polyethylene. Polyolefin, such as a copolymer with polypropylene, is preferably used.

A preferred combination of the component A and the component B has a difference in melting point between the two components of not less than 20 ° C. and is compatible with each other.

If the difference between the melting points of the two components is less than 20 ° C., the components up to the high melting point component A are softened or melted during hot pressing.
A softened or melted fiber adheres to the embossing roll, impairing operability, and the resulting nonwoven fabric has poor mechanical properties, and the surface becomes film-like or flexibility is impaired. In some cases, problems may occur in the high-order processing.

If the two components are not compatible with each other, the two components will undergo phase separation in the fleece deposition step and the heat welding step, deteriorating the operability and failing to achieve the object of the present invention.

Component A and component B each include a matting agent, a pigment, a flame retardant, a deodorant, as long as the effects of the present invention are not impaired.
Optional additives such as an antistatic agent, an antioxidant, and an ultraviolet absorber may be added.

The cross-sectional shape of the conjugate fiber is such that the component A has a central portion,
It is necessary that component B has a leaf section of 2 to 8 leaves. In this case, the low melting point component B and the high melting point component A are alternately arranged in the fiber cross section, and the component A having a melting point considerably higher than the heat welding temperature is partially exposed on the fiber surface. Even when the temperature is raised to near the melting point of the low melting point component B, a softened or melted fiber does not adhere to the embossing roll. Since the low-melting point component B is present in the leaves (convex portions), a sufficient adhesive strength can be obtained when hot-pressed. And, even if the conditions of the thermal pressure welding are not strictly controlled, troubles hardly occur in higher-order processing such as needle punching.

The number of leaves of the conjugate fiber must be 2 to 8, preferably 3 to 6. If the number of leaves is one, it becomes a side-by-side type, while 8 leaves
If the number is more than the number, the component B becomes close to a core-sheath type covering the entire circumference of the fiber, and the effect of the present invention is not sufficiently exhibited.

FIG. 1 is a schematic cross-sectional view of a specific example of the conjugate fiber according to the present invention. In FIG. 1, reference numeral 1 denotes a high melting point component A at the center, and 2 denotes a low melting point component B at the leaves.

It is desirable that the composite ratio of component A to component B in the composite fiber be 80/20 to 40/60 by weight.
When the proportion of the component A is too large, the adhesive strength becomes insufficient. On the other hand, when the proportion of the component A is too small, the component A becomes close to a core-sheath type covered with the component B, and The same problem as in the case where it is used occurs.

The single fiber fineness of the composite fiber is 3 to 15 d,
Preferably, it is 4 to 10d. If the single-fiber fineness is too small, it is difficult to stably produce the multi-leaf cross-section conjugate fiber. Conversely, if the single-fiber fineness is too large, the bonding points between the fibers are easily peeled or obtained. The mechanical properties and flexibility of the nonwoven will be impaired.

The nonwoven fabric of the present invention is obtained by partially heat-welding the nonwoven fleece composed of multifilament cross-section long fibers as described above, and both components A and B are exposed on the fiber surface. It is necessary to maintain the state.
In the case where the component A is coated with the component B by the heat pressing treatment, the same problem as in the case of using the core-sheath type composite fiber occurs.

Further, the nonwoven fabric of the present invention has a compression stiffness (measured by a method described later) of 1.5 g /
(g / m ² ) or less. The softness of the nonwoven is
Although the weight becomes poorer as the basis weight increases, the compression stiffness takes into account the basis weight and enables the degree of flexibility of the nonwoven fabrics having different basis weights to be evaluated with the same index. And, the compression stiffness is 1.5 g / (g / m
Non-woven fabrics exceeding ² ), regardless of the basis weight,
Insufficient flexibility.

The compression stiffness of the nonwoven fabric can be determined by appropriately selecting the composite ratio of the component A and the component B of the composite filament, the fineness of the single yarn, the ratio of the pressed portion when the nonwoven fleece is hot pressed, and the like. , Can be adjusted.

The basis weight of the nonwoven fabric varies depending on the single-filament fineness of the conjugate fiber and the use of the nonwoven fabric, but is usually appropriately selected in the range of 10 to 200 g / m ² . If the basis weight is too small, the number of fibers constituting the nonwoven fabric will be small and the uniformity will be poor.On the other hand, if the basis weight is too large, sufficient heat will not be given to the inner layer of the nonwoven fabric at the time of hot pressing, and the shape will be stable. It becomes poor in nature. In general, low-weighted ones are very flexible and are used as medical and sanitary materials, living materials, etc. High-weighted ones of 100 g / m ² or more are industrial materials, especially needle-punched carpets. Used as a base cloth.

Next, a method for producing the long-fiber nonwoven fabric of the present invention will be described. First, the polymers of the component A and the component B are separately melted and spun using a spinneret for a multi-lobed conjugate fiber, and the spun yarn is cooled using a cooling device such as a horizontal spray or an annular spray. After cooling, it is pulled and thinned to the target fineness using air soccer. The traction speed is preferably 3500 m / min or more, particularly 4000 m / min or more, because the dimensional stability of the nonwoven fabric is improved. After the composite fibers discharged from the air soccer are spread by a general method, they are spread and accumulated on a moving deposition device such as a conveyor made of a screen to form a nonwoven fleece, and then the fleece is embossed with an embossing roll. Partially heat-welded to obtain a long-fiber nonwoven fabric.

The fleece can be thermally pressed by using a pair of rolls composed of an embossing roll and a flat roll or two embossing rolls, the former being preferred.

What is important here is the hot pressing temperature and pressing area ratio given to the fleece when performing hot pressing.

The thermal pressure welding temperature is (Tm-40) to (Tm-
5) It is necessary to set the temperature to ° C [Tm: melting point of component B (° C)]. If this temperature is too low, the mechanical properties and shape stability of the resulting nonwoven fabric will be poor. Conversely, if this temperature is too high, the fleece will fuse to the embossing roll or flat roll, impairing operability. At the same time, the surface of the obtained non-woven fabric is formed into a film, resulting in a poor quality product.

It is necessary that the press contact area ratio is 4 to 40%, and it is particularly preferable that the press contact area ratio is 10 to 20%. If the press-contact area ratio is too small, the bonding portion is small and the bonding strength is insufficient, and the resulting nonwoven fabric has excellent flexibility but poor mechanical properties and shape stability. On the other hand, if the pressure contact area ratio is too large, the number of bonded portions becomes too large, and the flexibility of the obtained nonwoven fabric is impaired.

The area ratio of the press contact means the ratio of the area of the press contact portion to the area of the entire nonwoven fabric sheet.

The shape of the portion forming the convex portion applied to the embossing roll is not particularly limited, such as a circle, a square, a well, a line, etc., and a specific pattern may be formed. An embossing roll having an area of one convex portion of 0.1 to ² mm ² and the number of convex portions of 10 to 40 / cm ² is preferably used.

The linear pressure between the rolls at the time of hot pressing is 10 to 10 mm.
A suitable value is 0 kg / cm.

[0032]

According to the present invention, since the multi-lobed composite long fiber composed of the high melting point component A and the low melting point component B disposed around the high melting point component A is used, the nonwoven fleece is subjected to partial heat welding.
In the heat-pressed portion, the low-melting components B arranged on the outer periphery are temporarily and tightly adhered to each other, and the high-melting component A in the center is heat-softened.
There is no thermal curing, and the original flexibility of the fiber is maintained in the non-thermally pressed portion. Therefore, the mechanical properties and shape stability of the nonwoven fabric are ensured in the heat-welded portion, the flexibility is ensured in the non-heat-welded portion, and the long-fiber nonwoven fabric has excellent mechanical properties and shape stability, and has good flexibility. Is obtained.

[0033]

Next, the present invention will be described specifically with reference to examples. In addition, the measuring method of a characteristic value is as follows. (a) Melting point The melting point was measured at a heating rate of 20 ° C./minute using a DSC-2 type differential scanning calorimeter manufactured by PerkinElmer. (The temperature giving the maximum value of the melting endothermic peak was defined as the melting point.) (B) Relative viscosity of polyester 0.5 g of a sample was dissolved in 100 ml of an equal weight mixed solvent of phenol and ethane tetrachloride, and measured at a temperature of 20 ° C. (c) Melt flow rate (MFR) of polypropylene Measured by the method described in ASTM D 1238 (L). (d) Fabric weight of non-woven fabric Ten pieces of 10 cm × 10 cm pieces were prepared from the sample in the standard state, and after adjusting the equilibrium moisture content, the weight (g) of each sample piece was weighed, and the average of the obtained values was measured. The value was converted per unit area (1 m ² ) to obtain a basis weight (g / m ² ). (e) Tensile strength of non-woven fabric Constant-speed stretching type tester: Tensilon manufactured by Toyo Baldwin Co., Ltd.
Using a UTM-4-1-100 model, measurement was performed on 10 test pieces with a width of 5 cm (horizontal direction) and a length of 20 cm (longitudinal direction) at a gripping interval of 10 cm and a tensile speed of 20 cm / min. Indicated. (f) Compression stiffness of non-woven fabric Using Tensilon UTM-4-1-100, width (vertical direction) 5cm,
Ten test pieces with a length (lateral direction) of 10 cm were bent in the horizontal direction into a cylindrical shape, and the ends were joined to form a sample of 5 cm /
The cylindrical sample was compressed vertically at a compression rate of 1 minute, and the stress at the maximum load was measured and indicated as an average value. (The smaller the value, the better the flexibility.)

Example 1 Polypropylene having a melting point of 160 ° C. and an MFR of 50 g / 10 min as a high melting point component A, and a melting point of 138 ° C. as a low melting point component B
A polypropylene copolymer having an MFR of 30 g / 10 min and ethylene being randomly copolymerized at 4% by weight was prepared. These are fed to a known melt composite spinning machine, and the leaves are 6
Spinning temperature 230 ° C, single hole discharge rate using individual spinneret
The spinning was performed under the conditions of 3.5 g / min and a composite weight ratio (component A / component B) of 70/30. After cooling the spun yarn, the yarn is taken up by air soccer at a speed of 4500 m / min, opened by a known method, collected and deposited on a moving collecting surface to form a fleece, and the fleece is hot pressed. Into a long-fiber nonwoven fabric. At the time of hot pressing, an embossing roll and a flat roll having a hexagonal pressing contact at a density of 18 pieces / cm ² and a pressing area ratio of 15% were used, the surface temperature of both rolls was set at 125 ° C., and the basis weight was 100 g / cm ^2. m ² long-fiber nonwoven fabric was obtained. The single fiber fineness of the composite fiber collected from the fiber assembly was 7d.

Example 2 Polyethylene terephthalate having a melting point of 260 ° C. and a relative viscosity of 1.38 as high melting point component A, and melting point as low melting point component B
A polyethylene terephthalate copolymer having a relative viscosity of 1.39 at 213 ° C. and prepared by copolymerizing 15% by mole of isophthalic acid was prepared. These are supplied to a known melt composite spinning machine, and the spinning temperature is 290 ° C., the single hole discharge rate is 4.2 g / min, and the composite weight ratio (component A / component B) is 60 /
It was spun under the conditions of 40. After cooling the spun yarn, the spun yarn is drawn at a speed of 5400 m / min by air soccer, opened by a known method, collected and deposited on a moving collecting surface to form a fleece, and the fleece is hot pressed. Into a long-fiber nonwoven fabric. At the time of hot pressing, an embossing roll and a flat roll having a pressing area ratio of 15% having 30 square pressing contacts at a density of 30 pieces / cm ² are used, the surface temperature of both rolls is 200 ° C., and the basis weight is 100 g / m 2. ^Two long-fiber nonwoven fabrics were obtained. The single fiber fineness of the composite fiber collected from the fiber assembly was 7d.

Example 3 Polyethylene terephthalate having a melting point of 260 ° C. and a relative viscosity of 1.38 as high melting point component A, and melting point as low melting point component B
A polyethylene terephthalate-based copolymer prepared by copolymerizing isophthalic acid at 8% by mole and having a relative viscosity of 1.44 at 230 ° C was prepared. These are fed to a known melt composite spinning machine, using a spinneret having six leaves, a spinning temperature of 290 ° C., a single hole discharge rate of 1.67 g / min, and a composite weight ratio (component A / component B) of 40 /
Spinning was performed under the conditions of 60. After cooling the spun yarn, the yarn is drawn by air soccer at a speed of 5000 m / min, opened by a known method, collected and deposited on a moving collecting surface to form a fleece, and the fleece is hot pressed. Into a long-fiber nonwoven fabric. At the time of thermal pressure welding, an embossing roll and a flat roll having a hexagonal pressure contact at a density of 20 pieces / cm ² and a pressure contact area ratio of 15% were used, the surface temperature of both rolls was 217 ° C., and the basis weight was 30 g / cm ^2. m ² long-fiber nonwoven fabric was obtained. The single fiber fineness of the composite fiber collected from the fiber assembly was 3d.

Example 4 Example 4 was carried out in the same manner as in Example 2 except that the pressed area ratio was 8%.

Example 5 Example 5 was carried out in the same manner as in Example 2 except that the pressure contact temperature was 205 ° C.

Example 6 Example 6 was carried out in the same manner as in Example 2 except that the pressure welding temperature was 195 ° C.

Comparative Example 1 Using the same high melting point component A and low melting point component B as in Example 2,
The concentric core-sheath composite fiber having the former as the core and the latter as the sheath is prepared under the conditions of a spinning temperature of 290 ° C., a single hole discharge rate of 4.4 g / min, and a composite weight ratio (component A / component B) of 60/40. Spun out. After cooling the spun yarn, the spun yarn was taken up by air soccer at a speed of 5600 m / min.
m ² long-fiber nonwoven fabric was obtained. The single fiber fineness of the composite fiber collected from the fiber assembly was 7d.

Comparative Example 2 A long-fiber nonwoven fabric was produced under the same conditions as in Comparative Example 1, except that the temperature of the heat-welding was 205 ° C.

Comparative Example 3 Using the same high melting point component A and low melting point component B as in Example 3,
The concentric core-sheath composite fiber having the former as the core and the latter as the sheath was prepared under the conditions of a spinning temperature of 290 ° C., a single-hole discharge rate of 1.7 g / min, and a composite weight ratio (component A / component B) of 40/60. Spun out. After cooling the spun yarn, the yarn was taken up by air soccer at a speed of 5100 m / min, and the basis weight was 30 g / m ² as in Example 3.
Was obtained. The single fiber fineness of the composite fiber collected from the fiber assembly was 3d.

Table 1 summarizes the characteristic values and the like of the nonwoven fabrics obtained in Examples 1 to 6 and Comparative Examples 1 to 3.

[0044]

[Table 1]

[0045]

According to the present invention, a long-fiber nonwoven fabric having excellent mechanical properties and shape stability and good flexibility can be manufactured with good operability.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a specific example of a multilobe composite long fiber according to the present invention.

[Explanation of symbols]

 1 Central part (high melting point component A) 2 Leaf part (low melting point component B)

Claims (3)

[Claims] 1. A polyolefin comprising a high-melting polymer component A and a low-melting polymer component B having compatibility, wherein the component A is arranged in the center and the component B is arranged as 2 to 8 leaves. A long-fiber nonwoven fabric having a shape stability in which a nonwoven fleece made of a composite leaf having a leaf section is partially hot-pressed, wherein both components A and B are exposed on the fiber surface. Fiber non-woven fabric. 2. The difference in melting point between component A and component B is 20 ° C. or more, and the composite weight ratio of component A and component B is 80/20 to 40/60.
The long-fiber nonwoven fabric according to claim 1, which is: 3. The method according to claim 1, which is obtained by a spunbond method.
The nonwoven fleece described in (1) above, using an embossing roll having a pressed area ratio of 4 to 40%, was used at a temperature of (Tm-40) to (Tm-5) ° C.
A method for producing a long-fiber nonwoven fabric, which comprises partially heat-pressing at [Tm: melting point of component B (° C.)].