JPH02216251A - Nonwoven fabric composed of heat-bonding conjugate fiber - Google Patents

Abstract

PURPOSE:To obtain the subject nonwoven fabric having soft feeling by thermocompression bonding spun-bonded nonwoven fabric of hot-adhering conjugate fiber composed of linear low density polyethylene as sheath component and polyamide as core component. CONSTITUTION:Spun-bonded nonwoven fabric made of hot-adhering conjugate fiber having <=5 denier single fiber size composed of linear low density polyethylene (1-15wt.% octene-1 content) having 0.900-0.940g/cm<3> density, 5-45g/10min MI value, >=25cal/g heat of fusion as sheath component and polyamide as core component is subjected to thermocompression bonding at a temperature of 15-30 deg.C lower than melting point of the sheath component to afford the aimed nonwoven fabric having 7-40% pressure contact area fraction and 10-200g/m<2> weight per unit area.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a nonwoven fabric made of heat-adhesive conjugate fibers.

(Prior Art) In the production of nonwoven fabrics, there are methods for fixing fibers together, such as a method of entangling fibers such as a needle punch method, and a method of using various adhesives as a binder. Nonwoven fabrics such as disposable diapers and covering papers for sanitary absorbents, whose demand has been rapidly increasing in recent years, are required to have a soft texture that is pleasant to the touch. In order to satisfy these required qualities as much as possible, a nonwoven fabric production method mainly using a binder method has been adopted. As the binder method, a method of attaching an adhesive solution to a web has been mainly adopted, but there are problems such as energy is required to remove the solvent of the adhesive solution and the working environment is not good. In order to solve these problems, a method has been used in which fibers with a melting point lower than those of the fibers constituting the web are mixed into the web as a binder, and after the web is constructed, the fibers are bonded together by heat treatment. Composite fibers containing fiber-forming polymers with different melting points as composite components have also come to be used as binders for nonwoven fabrics with high strength and good texture. Regarding this, the special public
It is known from Japanese Patent No. 583.

(Problems to be Solved by the Invention) The low melting point component of composite thermally adhesive fibers for nonwoven fabrics that have been conventionally used is usually polyethylene, and medium-density or high-density polyethylene or linear low-density polyethylene (hereinafter referred to as
It is called LLDPE. ).

Nonwoven fabrics made of heat-adhesive conjugate fibers containing medium-density or high-density polyethylene as a low-melting-point component have the disadvantage of being hard to the touch. On the other hand, in terms of performance, nonwoven fabrics made of heat-adhesive composite fibers containing commercially available LLDPE, which is obtained by copolymerizing α-olefins having 4 to 8 carbon atoms, as a low melting point component can be expected to have a soft feel in terms of performance. There is a problem in that it is difficult to obtain a homogeneous nonwoven fabric using the spunbond method from Kokichi, which is difficult to spin at high speed. In addition, L L D P with good spinnability
There is a nonwoven fabric made of composite fibers with E as a sheath component and polyethylene terephthalate as a core component, but in this case,
At low basis weights, softness is not impaired, but because polyethylene terephthalate is used as a core component, nonwoven fabrics with medium basis weights or higher inevitably have a limit in terms of softness.

An object of the present invention is to provide a soft-textured spunbond nonwoven fabric made of a conjugate fiber whose core component is polyamide, which is a sheath component, and is made of LLDPE having good spinnability.

(Means and effects for solving the problem) The present inventors:
The present invention has been arrived at as a result of intensive research to solve the above problems. That is, the present invention is a copolymer of ethylene and octene-1, in which octene-1 is substantially 1 to 1.
Contains 5% by weight and has a density of 0.900 to 0.940g/c
m3. Melt index value is ASTM (7) D-12
38(E) (7) The sheath component is linear low-density polyethylene with a temperature of 5 to 45 g/10 minutes and the heat of fusion is 25 cal/g or more as measured by DSC, and the core component is polyamide. It is a fiber aggregate made of heat-adhesive composite fibers with a single filament fineness of 5 deniers or less, and after the melt-extruded composite fibers are stretched and sent out in an air sucker, a porous collector is moved. A fiber aggregate formed by blowing onto a container, the fiber aggregate is heat-pressed at a temperature 15 to 30°C lower than the melting point of the sheath component constituting the composite fiber, and the welded area ratio is 7 to 30°C. 40%, weight is 1
The gist is a nonwoven fabric made of heat-adhesive conjugate fibers of 0 to 200 g/n2. Here, the press area ratio in the present invention indicates the ratio of the press area to the sheet area, and the larger the press area ratio is, the higher the strength becomes, but the texture becomes rougher and harder.

Moreover, the L L D PE may contain other α-olefins within a range of 15% or less of the content of octene-1. In addition, the LLDPE contains a lubricant, an R material,
It may also contain additives such as stabilizers and flame retardants.

The fibers used in the present invention are suitable for spunbond nonwoven fabrics, and if the single yarn fineness becomes thick, good hand feel cannot be obtained, and the fibers with a single yarn fineness exceeding 5 deniers are not intended.

The polyamide used for the composite fiber may be any polyamide that can be melt-spun (eg, homopolyamides such as nylon 6, nylon 66, nylon 6/12, or copolyamides mainly composed of these polyamides. In the present invention, nylon 6 is particularly preferred.

These polyamides also contain matting agents, stabilizers, pigments, and dyes.
There is no problem even if it contains additives such as M fuel and antistatic agent. LL D P E which is a sheath component of composite fiber
The composition ratio of polyamide, which is the core component, is L L D P
20-80% by weight of E and 80-20% by weight of polyamide
is preferred. If the LLDPH is less than 20x4, the adhesive strength will be weak even if the fiber strength is high, and the texture will be rough and hard, making it impossible to obtain a preferred nonwoven fabric.

On the other hand, nonwoven fabrics containing more than 80% by weight of LLDPE have high fiber adhesion and are soft to the touch, but have low strength, which is undesirable. In the present invention, octene-1
If the content exceeds 15% by weight, it is difficult to obtain a fine denier. On the other hand, if the content is 1% by weight without grooves, the resulting fibers will be hard and have poor feel. Also.

If the density of LLDPH exceeds 0.940 g/cm3, the texture will be rough and hard, and it will not be possible to reduce the weight of the fiber;
If it is less than 0 g/am3, it becomes difficult to obtain fibers with high strength.

The reason why we limited the MI value to LLDPE of 5 to 45 g/10 minutes by measuring it using the ASTM D-1238(E) method is as follows.
If LLDPE alone is used to spin yarn, if the MI value is less than 5 g/10 minutes, the deformation of the discharged yarn will not be smooth and high-speed spinning will be impossible. In other words, high-speed spinning cannot be easily achieved unless the spinning temperature is extremely high, and spinning at extremely high temperatures tends to stain the nozzle surface, which is unfavorable for operation. On the other hand, if the MI value exceeds 45 g/10 minutes, the strength of the obtained fibers will decrease, which is not preferable.

LLDPE with a heat of fusion of less than 25 cal/g has poor spinnability, although the cause is currently unknown. In the spunbond method, in which nonwoven fabrics are directly produced after drawing a continuous filament with an air sucker, LLDPE with a heat of fusion of less than 25 cal/g is air-stretched when making a fine denier.
It is necessary to increase the air pressure in the race car.

However, in the case of LLDPE with a heat of fusion of 25 cal/g or more.

It is possible to reduce the air pressure and make the denier finer.

The heat of fusion in the present invention was measured as follows. In other words, PerkinElmer (Perkfn-E)
lmer) D S C-2C, sample approximately 511
Collect Ig and increase the temperature increase rate (scan rate) to 20
℃/min, and the DSC curve obtained by raising the temperature from room temperature is determined according to the equipment manual.

The fiber of the present invention can be spun using a conventionally known melt spinning apparatus for composite fibers. The spinning temperature of the polymer of LLDPE is 210-270"C, preferably 230-260"C.On the other hand, polyamides, e.g.
In the case of nylon 6, the relative viscosity measured at 25°C in a 96% sulfuric acid solvent is preferably in the range of 2.5 to 3.5, and the spinning temperature is preferably 250 to 280°C.

If the spinning temperature is outside the above range, the spinning condition will be poor and it will be difficult to obtain a satisfactory nonwoven fabric.

In other words, when the spinning temperature is lower than the above range, it is difficult to increase the spinning speed, it is difficult to obtain fine denier fibers, and furthermore, it is difficult to obtain a fine denier fiber.

It is necessary to increase the car's air pressure. Furthermore, the resulting nonwoven fabric frequently breaks during spinning, making it difficult to obtain a homogeneous nonwoven fabric. On the other hand, if the spinning temperature is set higher than the above temperature range, the nozzle surface is likely to get dirty, and when operated for a long time, fiber breakage due to the nozzle surface dirt will result in a non-uniform non-woven fabric. In order to prevent this, it is necessary to clean the nozzle surface periodically and at short intervals, resulting in large losses.

In other words, in the present invention, the temperature difference between the two during melt spinning is small, so cooling of the composite fiber after melt extrusion is smooth.
Distortion due to uneven cooling of the yarn is unlikely to remain. Therefore, the obtained composite fiber is uniform and has good spinnability. In other words, L L D P E has good spinnability at high temperatures.
Composite fibers with a low yarn breakage rate can only be obtained by selecting and bringing the spinning temperatures of both rows close to each other.

When producing the spunbond nonwoven fabric of the present invention, if thread breakage occurs during spinning, the resulting fabric will inevitably have uneven basis weight or large holes. The disadvantage of large holes is that in the case of a low basis weight nonwoven fabric with a basis weight of 10 to 50 g/m, it may break when being pulled out from the roll during the processing process, or wrinkles or hanging may occur at the defective point, resulting in a defect in the nonwoven fabric and reducing the appearance quality. becomes worse. On the other hand, is the basis weight 50g/n? When the above-mentioned high-wetness nonwoven fabric is used as a carpet base fabric, piles cannot be driven in if there are holes caused by thread breakage.

Furthermore, if the webs overlap too much due to wrinkles or hanging during processing and the thickness of the nonwoven fabric increases too much, the pile will not be carried out smoothly and the needles will break at one o'clock. As a result, operability and appearance quality deteriorate. In either case, the defects caused by yarn breakage directly become defects of the nonwoven fabric. Therefore, the defects caused by such yarn breakage during spinning require additional force at the time of shipping, which results in short fabrics and a deterioration in yield.

The reason why the basis weight of the nonwoven fabric is set to 10 to 200g/m is that the weight of the nonwoven fabric is 200g/+y? If it exceeds this, the nonwoven fabric becomes coarse, hard and bulky, which is not preferable. Also, Log/
If it is less than g, the texture will be soft, but the strength will be low and it will be impractical.

In addition, when the web is heat-treated and the fibers are bonded together by thermocompression, the pressure contact area ratio is 7 to 40, due to the relationship between the texture and strength of the nonwoven fabric.
%is necessary. If it is less than 7%, the texture will be soft but the strength will be insufficient. On the other hand, if the pressure contact area ratio exceeds 40%, the strength will be high but the nonwoven fabric will be hard, which is not preferred in the present invention. Note that the nonwoven fabric web is heat-press welded to take advantage of the soft texture of LLDPE and to increase the strength of the nonwoven fabric.

In the pressure bonding method, for example, an embossing heated roll or the like is used to bond the intertwined filaments constituting the web by heat and pressure. This thermal bonding temperature affects the texture and strength of the nonwoven fabric, and in the present invention, it is important to perform heat treatment and thermal bonding at a temperature 15 to 30° C. lower than the melting point of LLDPH, which is a sheath component. That is, if the surface temperature of the embossing heating roll is higher than the above temperature range, the strength of the nonwoven fabric will increase, but the texture will become hard, which is not preferable. On the other hand, if the surface temperature of the embossing heating roll is lower than the above range, the texture of the nonwoven fabric will be soft, but the strength will be low because the adhesion between the filaments will be insufficient. Next, by making the cross-sectional shape of the fibers irregular or flat in addition to circular cross-sections, it is possible to obtain a sheet that takes advantage of the characteristics of the cross-sectional shape.

As detailed above.

The nonwoven fabric of the present invention has few defects and has a good feel.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, the method of measuring the physical property values shown in the examples is as follows.

(1> Tensile strength of nonwoven fabric
The maximum tensile strength was measured from a test piece with a thickness of 130 mm and a length of 1100 tons.

(2) Total hand of nonwoven fabric Measured using slot width IQ ms according to the handle-o-meter method described in JIS L-1096.

The smaller the number, the softer the texture.

Example 1 Contains 5% by weight of octene-1 and has a density of 0.937g/
cJ, Ml value force < 25 g/10 min as measured by ASTM D-1238 (E) method, heat of fusion obtained as measured by DSC is 40 ca 1 g, LLDPE with melting point of 125 ° C.
The sheath component is nylon 6 with a relative viscosity of 2.6 (25℃
The core component was a relative viscosity of 2.6 (measured by dissolving 1 g of sample in 100 cc of 96% sulfuric acid), and the sheath component LLDPH was spun at a spinning temperature of 230"C using a melt spinning device for composite spinning.
Spinning temperature of 1-core nylon 6: 265°C, nozzle: 0
, 4 ** Φ × 200 hole U, melt extrusion of composite ratio of LLDPIE and nylon 6 at a weight ratio of 50:50 under 1 nozzle under the conditions of single hole discharge rate of 1.25 g/min.
The continuous multifilament was taken off using an air sunker installed at the 01- position. The results are shown in Table 1.

Comparative Example 1 Contains 5% by weight of octene-1 and has a density of 0.937g
/CIl+, melt index value is ASTM D-1
25g/10 minutes as measured by the method of 238(E), heat of fusion as 20cal/g as measured by DSC, melting point as 125°c 0
) A continuous multifilament was drawn using LLDPE in the same manner as in Example 1. The results are shown in Table 1.

Table 1 As is clear from Table 1, t, LI)P in Example 1
When IE was used, it was possible to increase the spinning speed compared to the LLDPE of Comparative Example 1, and finer single yarn fineness was obtained. In addition, it was possible to lower the air pressure of the air suture car, and the strength and elongation characteristics of the yarn quality were also excellent.

Example 2 The multifilament obtained using the air suture car of Example 1 was collected on a moving endless wire mesh, and the mesh size was 1.
After forming webs of 5 g/m and 40 g/m, a line pressure of 30 kg/cm and a pressure contact area ratio of 15% were kept constant by a roll group consisting of an embossing heating roll and a metal heating roll.
The effect of heat treatment temperature was examined by changing the heat treatment temperature from 95°C to 110°C. Table 2 shows the performance results of the obtained nonwoven fabric.

Comparative Example 2 A nonwoven fabric was produced in accordance with Example 2, except that the heat treatment temperature was changed to 90°C and 115°C, with all other conditions being the same.

Table 2 shows the performance results of the obtained nonwoven fabric.

Comparative Example 3 The LLDPIE used in Example 1 was used as the sheath component, and the intrinsic viscosity was -〇, 70 (phenol:tetrachloroethane=1=1
The core component was polyethylene terephthalate (measured at 20°C, using a mixed solvent of Polyethylene terephthalate was melt-spun at a temperature of 290°C, a single-hole discharge rate of 1.25 g/min, and a composite ratio of LLDPE and polyethylene terephthalate at a weight ratio of 50:50, and the filament was taken out according to Example 1, and the same process was performed as in Example 2. Preliminary considerations: Table Nylon 6 Table (Continued) The filaments were then made into a web to obtain a nonwoven fabric. The properties of the nonwoven fabric are shown in Table 2. As is clear from Table 2, a nonwoven fabric with good performance can be obtained when the heat treatment temperature is 15 to 30'C lower than the melting point of the sheath component. Also 18
By changing the component from polyethylene terephthalate to nylon 6, a nonwoven fabric with a soft texture can be obtained even if the basis weight of the nonwoven fabric increases.

(Effect of the invention) The nonwoven fabric made of heat-adhesive conjugate long fibers of the present invention is:

Due to its high strength, softness, and extremely smooth texture, low-weight nonwoven fabrics are particularly suitable for lining disposable diapers, while high-weight nonwoven fabrics are used for bags, carpet base fabrics, filters, etc. It can be applied to a wide range of applications.

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Claims (1)

[Claims] (1) A copolymer of ethylene and octene-1, containing substantially 1 to 15% by weight of octene-1 and having a density of 0.
900-0.940g/cm^3, melt index value is 5 when measured by ASTM D-1238(E) method.
~45g/10min, and the heat of fusion is 2 as measured by DSC.
It is a fiber aggregate consisting of heat-adhesive conjugate fibers with a single filament fineness of 5 denier or less, with a sheath component of linear low-density polyethylene of 5ca1/g or more and polyamide as a core component, and the melt-extruded conjugate fibers are A fiber aggregate formed by blowing onto a moving porous collector after being stretched and delivered by an air suction car, and the fiber aggregate is a sheath component that constitutes the composite fiber. 1 from the melting point of
Heat pressure welded at a temperature 5 to 30 degrees lower, with a pressure weld area ratio of 7 to 4.
A nonwoven fabric made of thermoadhesive composite fibers with a weight of 0% and a basis weight of 10 to 200 g/m^2.