JPH10273861A - Nonwoven fabric manufacturing method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Conventionally, a flexible non-woven fabric was obtained using ultrafine fibers, but advanced technology was required in the spinning process and the dividing process.
The problem is that the process is complicated and the cost is high. This problem is solved, and a method for producing a nonwoven fabric having a soft feeling by a simple means of splitting fibers by needle punching is proposed. SOLUTION: After a nonwoven fabric made of a fiber containing a polyester fiber having a hollow / or irregular cross section is shrunk by heating, the polyester fiber having the hollow / or irregular cross section is split by performing needle punching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a nonwoven fabric, and more particularly, to a method for obtaining a nonwoven fabric having a soft feel by a simple means of splitting fibers by needle punching.

[0002]

2. Description of the Related Art It has been known that a nonwoven fabric having a soft feeling can be obtained by using fine denier fibers. However, when fine denier fiber is used, the passability of the card process used for manufacturing the nonwoven fabric is poor, so that a problem that a good quality nonwoven fabric cannot be obtained and the workability of the card process are reduced. There was a problem of doing.

[0003] For this reason, conventionally, to obtain a fine denier nonwoven fabric, fine nondenier fibers having poor handling properties are not directly used, but a nonwoven fabric is prepared using splittable composite fibers, and then the nonwoven fabric is prepared by some means. Many methods have been proposed for dividing and thinning conjugate fibers.

For example, JP-A-5-25772 discloses that a polyamide and a polyester are divided along a longitudinal direction in a cross section of a single filament so that one component does not completely include the other component. After forming the fabric using the shaped composite filament, 50 to 90% by weight of the polyester is continuously dissolved and removed with an alkali aqueous solution, and further, 95% by weight or more of the polyester is continuously dissolved and removed with an alkaline aqueous solution to obtain an ultrafine pattern. There is disclosed a method for converting the data.

In Japanese Patent Application Laid-Open No. 2-169720, a polyolefin component and a fiber-forming polymer component which is incompatible with the polyolefin component are used, and the melting point difference between the two components is adjusted to 20 ° C. or more. A method is disclosed in which a high melting point component is arranged in a state where the high melting point component is divided into a plurality of parts in a state where the high melting point component is partially exposed to the fiber surface, and the heat melting type composite fiber in which the high melting point component is split by heat treatment is used for ultrafine formation. Have been.

Further, Japanese Patent Application Laid-Open No. Hei 4-289225 discloses that at least a two-component polyamide comprising an aliphatic polyamide as a first component and a polyamide containing an aromatic ring as a second component is formed into a composite fiber by a composite spinning method. A method is disclosed in which a pretreatment such as a high-pressure heat treatment or a weight-reduction treatment is performed to generate a distortion between constituent components, and then divided by a physical impact treatment of pressurized water such as a water jet.

[0007] In these methods, a nonwoven fabric having a uniform feel and a soft feeling made of ultrafine fibers can be obtained. However, for this purpose, advanced yarn production techniques and strict process control in the division process of the conjugate fibers are required. Further, there is a problem that the cost is increased due to complicated and diverse processes.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a simple method of splitting the fibers constituting the nonwoven fabric by needle punching.
It is to propose a method for producing a nonwoven fabric having a soft feel.

[0009]

According to the present invention, a nonwoven fabric made of a fiber containing a polyester fiber having a hollow and / or irregular cross-section is shrunk by heating, and then the polyester fiber is split by performing needle punching. A method for producing a nonwoven fabric characterized by the following.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The nonwoven fabric obtained according to the present invention comprises:
It is preferably made of fibers containing polyester fibers having a hollow and / or irregular cross section, and the proportion of the polyester fibers having a hollow and / or irregular cross section to the total weight of the nonwoven fabric is 30% by weight or more.

When the proportion of the hollow and / or polyester fiber having a modified cross section in the whole nonwoven fabric is less than 30% by weight, the effect of the texture by splitting is not obtained, and the soft texture may not be obtained. is there.

In the method of the present invention, a plurality of cracks or split portions are formed in the polyester fiber by needle punching to split the fiber and the polyester fiber is used. Therefore, the cross section of the polyester fiber is a round cross section other than a solid fiber. Fiber, that is,
It is important to use a non-woven fabric comprising hollow and / or polyester fibers having an irregular cross section.

The irregular cross-sectional shape of the polyester fiber is preferably exemplified by a multi-lobed shape having three or more projections, a flat shape having a rectangular cross section, and the like.

The hollow body may have a circular outer shape or a non-circular shape as long as it has a hollow portion in the core. In short, fibers with a solid and round cross section cannot be used, but fibers with other cross sectional shapes can be used.

The fibers having a hollow and / or irregular cross-section are preferably composed of a polymer having a single composition from the viewpoint of handling of the nonwoven fabric in splitting treatment or the like.

Here, being composed of a polymer having a single composition means that it does not include a conjugate fiber composed of polymers having two or more compositions, and the polymer composition itself is composed of two or more polymers. It may be.

The polyester fiber comprises terephthalic acid as a main dicarboxylic acid component and at least one glycol, preferably at least one alkylene glycol selected from ethylene glycol, trimethylene glycol, tetramethylene glycol and the like. What consists of polyester which is a component can be used.

The polyester fiber may be modified, if necessary, by copolymerizing and / or blending the third component. In addition, the polyester fiber may contain an optional additive such as a catalyst, a coloring inhibitor, a heat-resistant agent, a flame retardant, an antioxidant, and inorganic fine particles as needed.

Next, in order to prepare a non-woven fabric using the above fibers, a conventionally known method is used. For example, in the case of a non-woven fabric made of short fibers, a method of producing a web by passing fibers as a raw material through a carding process and laminating the web to form a non-woven fabric is exemplified. Needle punching can be performed.

In the case of a nonwoven fabric made of long fibers,
The fiber is spun by a spunbond method to form a web,
A method of laminating a nonwoven fabric is exemplified, and a needle punch for entanglement may be performed as necessary. The needle punch for the entanglement is different from the needle punch for splitting, and the degree of the needle punch may be light so as not to affect the shrinkage treatment.

In the present invention, the entire nonwoven fabric is heated and shrunk before applying a needle punch for splitting (hereinafter referred to as a needle punch unless otherwise specified, which means a needle punch for splitting). It is necessary to perform the treatment, and the density of the nonwoven fabric is reduced by 0.15 to
It is preferably in the range of 0.40 g / cm ^3, more preferably in a range of 0.20~0.30g / cm ^3.

If the density of the non-woven fabric is less than 0.15 g / cm ³ , the effect of splitting by needle punch is small, and if it exceeds 0.40 cm ³ , needle breakage increases, which is not preferable.

By setting the density of the nonwoven fabric in such a range, the fiber is easily cracked and split by a needle punch performed later, and a flexible nonwoven fabric can be obtained.

In order to shrink the nonwoven fabric as described above,
The hollow and / or polyester fibers having an irregular cross section may be shrinkable fibers, but the hollow and / or shrink fibers other than the polyester fibers having an irregular cross section may be used, and the hollow and / or hollow fibers may be used. And / or may be mixed with polyester fibers having an irregular cross section.

As the type of the shrinkable fiber, a polyester fiber having high shrinkage is preferably used because it is mixed with a polyester fiber having a hollow and / or irregular cross section.

The above-mentioned shrinkable fiber may be any as long as it shrinks the entire nonwoven fabric. For this purpose, a shrinkable fiber having a shrinkage ratio in the range of 5 to 60% is preferably used. When the shrinkage ratio is less than 5%, the nonwoven fabric does not shrink sufficiently, which is not preferable. On the other hand, when the shrinkage ratio exceeds 60%, the density of the nonwoven fabric increases and the flexibility is impaired.

The mixing ratio of the shrinkable fibers can be appropriately selected according to the level of the shrinkage of the fibers used and the range of the basis weight of the obtained nonwoven fabric. Are preferred.

The type and condition of the needle of the needle punch for splitting used in the present invention are not particularly limited, but those having a kick-up in the range of 0.01 to 0.10 mm are preferably used.

If the kick-up is less than 0.01 mm, the fiber cracks due to the needle punch are small, so that the polyester fibers having the hollow and / or irregular cross section may not be split. On the other hand, if the kick-up exceeds 0.10 mm, the fibers may be cut and the strength may be reduced, which is not preferable.

The number of punches of the needle punch for splitting the fiber depends on the diameter of the fiber constituting the nonwoven fabric, the density of the nonwoven fabric, and the type of needle used for the needle punch.
000 P / m ² is preferably exemplified.

In the present invention, preferably, a heating and pressurizing treatment using a calender roll or the like is performed after needle punching. By the calender roll processing, a crack portion generated by the needle punch can be completely divided.

The conditions for the calender roll processing are not particularly limited.
C. at 100 to 1000 kg / cm under pressure.

Needle punching performed in this manner,
The final fiber division ratio of the nonwoven fabric obtained by calendering or the like is preferably 5% or more, more preferably 10% or more, and further preferably 30% or more.

Further, in the method of the present invention, the nonwoven fabric is subjected to an alkali weight reduction treatment before the needlepunching of the nonwoven fabric, so that the splitting grooves are formed on the surface of the constituent fibers, especially on the surfaces of the hollow and / or polyester fibers having an irregular cross section. More preferably, the effect of the needle punch is increased.

As a method for reducing the alkali, a known method can be used. For example, a reduction treatment is performed using hot water containing sodium hydroxide for 10 to 30 minutes to reduce the alkali reduction rate to 10%.
５０50%. The weight loss rate is 10%
If the amount is less than 50%, the effect of reducing the alkali is not exhibited.
%, It is not preferable because the strength of the fiber decreases and the strength of the obtained nonwoven fabric decreases.

[0036]

The nonwoven fabric obtained according to the present invention is made of fibers containing hollow and / or polyester fibers having an irregular cross section, and can be produced by a simple means of splitting with a needle punch. Not only the production cost is low because a complicated dividing process is not required, but also the natural and flexible feeling is achieved because the hollow and / or polyester fibers constituting the nonwoven fabric are randomly split. Will have.

[0037] In addition, the use of high-shrinkable fibers gives a firm feeling, and is suitable for use as, for example, a leather-like nonwoven fabric.

[0038]

EXAMPLES The present invention will be described below more specifically with reference to examples. In addition, the measured value shown in the Example was measured by the following method.

(1) Fiber splitting ratio A cross-sectional photograph of the nonwoven fabric is taken, and the number of fibers having a split cross-section within a certain range of the cross-sectional photograph is represented by a, and the fiber having the original cross-sectional shape (split fiber) When the number of unprocessed fibers is b, the fiber division ratio is calculated by the following equation.

[0040]

(Equation 1)

When the division ratio is less than 5%, the result is indicated by "X",
Those with 30% were evaluated as “○”, and those with more than 30% were evaluated as “◎”.

(2) Bending resistance Measurement was performed in accordance with the measurement method of JIS L-1096.
The softness (flexibility) is measured by the 45-degree cantilever method. A sample having a value of less than 40 mm was evaluated as “◎”, a sample exceeding 40 mm and less than 50 mm was evaluated as “○”, and a sample having a value of 50 mm or more was evaluated as “X”.

(3) Hand feeling of nonwoven fabric Sensory evaluation was made in comparison with the conventional ultrafine fiber nonwoven fabric, and those having a better hand were indicated by “◎”, and those having a feeling comparable to the conventional were indicated by “○”. Those which were inferior to the conventional ones were evaluated as “×”.

(4) Shrinkage of fiber The fiber shrinkage treatment temperature was 70 ° C.
The measurement is performed in accordance with the measurement method of SL-1015, and the contraction rate of the fiber is calculated by the following equation.

[0045]

(Equation 2)

(5) Shrinkage rate of nonwoven fabric A rectangular sample was cut out from the original nonwoven fabric (about 15 cm).
× 20 cm), spread on a flat surface in a free state, measure the length and width accurately, determine the area (S ₁ ) of the nonwoven fabric before shrinkage treatment, and then immerse it in 70 ° C warm water for 1 minute to free Let it shrink. After the free shrinkage treatment, air-dry. After drying, the length and width of the nonwoven fabric are measured again to determine the area (S ₂ ) of the nonwoven fabric after the shrinkage treatment, and the shrinkage of the nonwoven fabric is calculated by the following equation.

[0047]

(Equation 3)

[Example 1] Polyester staple fiber (fineness: 3.5 denier, cut length: 51 m) having a triangular cross-sectional shape (the cross-sectional shape shown in Fig. 1A) obtained by a conventional method
m) 50% by weight of shrinkable polyester short fiber (shrinkage rate: 45% shrinkage rate at 70 ° C. for 1 minute in hot water, cross-sectional shape; round cross-section solid, fineness; 2.0 denier, cut length; 5
1 mm) 50% by weight and opened by a carding process to form a web, and the web is laminated into a sheet by a cross lay, and then needle-punched for entanglement; 500 P / c.
entangled with m ² to obtain a nonwoven fabric. 70 ° C
Was subjected to shrinkage treatment under warm water conditions for 1 minute. At this time, the shrinkage of the nonwoven fabric was 30%. After the shrink-treated nonwoven fabric was dried, needle punching for splitting was performed at 1000 P / cm ² , and heat compression was performed using a calendar roll at 120 ° C. The obtained nonwoven fabric had a basis weight of 300 g / m ² and a density of 0.23 g / cm ³ . Table 1 shows the evaluation results of the obtained nonwoven fabric.

[Examples 2 to 4, Comparative Example 1] Instead of the triangular cross-section shaped polyester fiber used in Example 1, the cross-section has the same area as the triangular cross-section shaped polyester fiber.
In addition, the cross-sections shown in FIGS. 1B to 1E respectively have a cross (Example 2), a round hollow (Example 3), a round solid cross section (Comparative Example 1), and a flat cross section (FIG. 1B). A nonwoven fabric was prepared in the same manner as in Example 1 using the polyester fiber having Example 4), and then subjected to splitting treatment to obtain a nonwoven fabric. Table 1 also shows the evaluation results of the obtained nonwoven fabric.

Example 5 The nonwoven fabric prepared in Example 1 was subjected to a shrinkage treatment, and then the nonwoven fabric was heated at a temperature of 1%.
At an aqueous sodium hydroxide solution having a concentration of 50 g / l at 05 ° C,
Perform alkali reduction treatment for 10 minutes (weight loss rate 20%),
Thereafter, splitting treatment was performed in the same manner as in Example 1 to obtain a nonwoven fabric. Table 1 also shows the evaluation results of the obtained nonwoven fabric.

[Comparative Example 2] A nonwoven fabric was prepared in the same manner as in Example 1 except that no shrinkage treatment was performed, and then splitting was performed to obtain a nonwoven fabric. Table 1 also shows the evaluation results of the obtained nonwoven fabric.

Example 6 A nonwoven fabric was prepared in the same manner as in Example 1 except that thermal compression by a calender roll was not performed, and then splitting to obtain a nonwoven fabric. Table 1 also shows the evaluation results of the obtained nonwoven fabric.

[0053]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a cross section of a polyester fiber used in Examples and Comparative Examples, (a) having a triangular cross section, (b) having a cross section, and (c) having a cross section. Is a hollow one, (d) is a solid one with a round cross section, (e)
Indicates a flat cross section.

Claims (5)

[Claims] 1. A method for producing a nonwoven fabric, comprising shrinking a nonwoven fabric containing a polyester fiber having a hollow and / or irregular cross section by heat and then performing needle punching to split the polyester fiber. 2. The polyester fiber having a hollow and / or irregular cross section has a content of 30% by weight based on the total weight of the nonwoven fabric.
The method for producing a nonwoven fabric according to claim 1, which is as described above. 3. The density of the nonwoven fabric after heat shrinkage is 0.15 to
0.40 g / cm ³ The manufacturing method according to claim 1 or 2, wherein the nonwoven fabric. 4. The method for producing a nonwoven fabric according to claim 1, wherein the nonwoven fabric is further subjected to calendering after needle punching. 5. The method for producing a nonwoven fabric according to claim 1, wherein the nonwoven fabric is subjected to an alkali reduction treatment before the needle punching.