JP3138145B2 - Bulk nonwoven - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fiber layer constituting a high shrinkable fiber over dry heat shrinkage rate of 50%, of other fibers (dry heat of yield <br/> contraction and no or dry heat shrinkage A fibrous layer composed of small fibers), which are superposed and entangled with each other, and a large number of wrinkles are formed on the surface by utilizing a difference in dry heat shrinkage between the two fiber layers. The present invention relates to a bulky nonwoven fabric which can be effectively used as a filter, a mask, a wiper, a towel or the like.

[0002]

2. Description of the Related Art Conventionally, as a bulky nonwoven fabric having an increased apparent thickness of a nonwoven fabric, a shrinkage of an elastic fiber which is a latent crimped elastic fiber or an elastomer fiber described in JP-A-2-160962 is known. The ones used are put to practical use. In addition, as the nonwoven fabric having a large number of wrinkles formed on the nonwoven fabric, a nonwoven fabric is formed by entanglement of fibers from both sides of the heat-shrinkable net to be integrated with the net. Some of them have been used, all of which are primarily used in household disposable wipers.

[0003] As a highly shrinkable fiber, Japanese Patent Application Laid-Open No. Sho 60-27
JP-A-09-0909, a polyvinyl alcohol fiber using a water-absorbing swelling action is put to practical use.
JP-A-214550 discloses an example of a polyolefin-based heat-shrinkable fiber using an α-olefin having a carbon number of butene or more and a propylene copolymer having a propylene content of 50 to 85 mol% by utilizing the heat-shrinkage property described in Japanese Patent Application Laid-Open No. 214550. Examples of the heat-shrinkable fibers having a maximum shrinkage of 50% or more include fibers of an ethylene-propylene random copolymer and an ethylene-propylene-butene-1 terpolymer previously provided by the present applicant. (JP-A-5-44108)
No.)

[0004]

The maximum shrinkage of dry heat-shrinkable fibers used in conventional nonwoven fabrics is usually 30 to 4%.
Since it is 0%, even if the nonwoven fabric before the shrinkage treatment is subjected to the shrinkage treatment, the rate of increase in bulk is small, and it is difficult to obtain a bulky nonwoven fabric in which the thickness of the nonwoven fabric after the shrinkage treatment exceeds 200% before the treatment. Met. Further, since the wet heat shrinkable polyvinyl alcohol fiber has a higher shrinkage but a smaller shrinkage stress, even if it is used for some fibers of a non-woven fabric in which the fibers are entangled and the shrinkage property is used, the thickness of the polyvinyl alcohol fiber is high. Increase rate of 200%
And a bulky nonwoven fabric having many wrinkles formed on the surface of the nonwoven fabric cannot be obtained.

[0005] A bulky nonwoven fabric utilizing the shrinkage of an elastic fiber as a latently crimped elastic fiber or an elastomer fiber has a first fiber section mainly composed of a fiber whose elasticity is exhibited by heat shrinkage, and a substantially non-woven fabric. Heat-treating the nonwoven fabric in which the non-stretchable second fiber sections are alternately juxtaposed in the width direction to form a plurality of crepes in the width direction by causing the fibers of the first fiber sections to exhibit elasticity. Because it is bulky and rich in elasticity, it is suitable for a dressing, a bandage, a cushion cover, etc., but when applied to a wiper or a towel, for example, a crepe portion (wrinkle portion)
And the crepe portion cannot be used effectively.

[0006] Such a disadvantage that the wrinkle portion is stretched can be improved by using a nonwoven fabric in which fibers are entangled on both sides of the heat-shrinkable net and then heat-treated to shrink the net and increase the bulk. Because of the remaining inside, the texture is not good and the flexibility is impaired.The surface of the non-woven fabric, which has become bulky due to the shrinkage of the net, has a wrinkled shape in which the fibers between the meshes of the net are swollen. Hard to say. Such a bulky nonwoven fabric is easily flattened when a surface pressure is applied. For example, when used as a wiper, an increase in wiping amount cannot be expected.

As described above, Japanese Patent Application Laid-Open No. 58-214 discloses
Japanese Patent Laid-Open No. 550 describes a heat-shrinkable fiber of 20% or more, and JP-A-5-44108 describes a heat-shrinkable fiber having a maximum shrinkage of 50% or more. Only examples of woven knits obtained with the yarn are taught. Since the heat shrinkage initiation temperature of such a high shrinkage fiber is relatively low and the shrinkage rate is high, it is expected that it is difficult to perform a uniform heat treatment when the fiber web is mixed. At the time, the idea of utilizing these highly shrinkable fibers as a part of the constituent fibers of the nonwoven fabric to form a large number of wrinkles on the surface of the nonwoven fabric was unexpected.

[0008] Generally, not only household wipers but also wipers with a large wiping amount have a large number of irregularities on the surface, the wiped one is pressed into the concave part, and the wiper surface has little wiping. Therefore, there is a demand for a nonwoven fabric having a more wrinkled surface, rich in irregularities, a wrinkle that does not expand even under tension, and a bulky appearance. However, the conventional uneven nonwoven fabric is not always satisfactory as a wiper intended for a material having a large wiping amount without being wrinkled enough to attain a sufficient purpose. In addition, a wiper using ultrafine fibers that has been widely used in recent years is suitable for wiping delicate dust, but is unsuitable as a wiper intended for a large wiping amount, and has a number of wrinkles that do not collapse on the surface. There has been a strong need in the industry for a soft, bulky nonwoven.

In the field of filters, the larger the filtering surface, the longer the filter can be used for filtration.
Efforts have been made to further increase the filter surface by, for example, pleating flat filters, but it is desired to realize a bulky nonwoven fabric having a large filtering area by forming wrinkles without pleating. I was

The present invention is intended for use in which a large pile of fine piles is formed in a short ridge and irregularly densely packed, and various volumes and flexibility are required such as various wipers, filters, towels and sheets. And a bulky nonwoven fabric which is convenient for

[0011]

According to the present invention, a web made of other fibers is laminated on a web layer made of high-shrinkable fibers having a dry heat shrinkage of 50% or more, and a fiber between these two webs is formed. the by entangled found that dry heat bulky nonwoven fabric that many wrinkles on the surface by deflating the layer of the high shrinkable fiber is formed by the process can be obtained, the above-mentioned problems are eliminated.

That is, the bulky nonwoven fabric according to the present invention has a maximum dry heat shrinkage (S%) by heating of at least 50%.
Melting point temperature (Tm ° C) is 130 <Tm <145
Of ethylene-propylene random copolymer (EP)
A second fiber layer made of another fiber is located on at least one surface of a first fiber layer containing at least 50% by weight of a high- shrinkable fiber made of a polymer containing at least 70% by weight , and these two layers are formed by a water jet method using a high-pressure water flow. The fibers are entangled and integrated, and the first fiber layer is shrunk by the dry heat treatment to form a large number of wrinkles due to the second fiber layer on the surface, and the apparent thickness is at least twice the thickness of the entangled nonwoven fabric. It is characterized by having.

If the high shrinkable fiber cannot have a performance exceeding its dry heat shrinkage of more than 50%, it becomes a nonwoven fabric having crepe-like irregularities, and fine pile loops are irregularly densely packed in short ridges. It is not possible to obtain a highly wrinkled, bulky nonwoven fabric. Further, even shrinkable fibers having a shrinkage of about 80%, other ordinary fibers more than 50% and cotton mixing and not obtained the desired multi wrinkles of the bulky nonwoven fabric, the maximum dry heat yield <br / > It is important to form the first fibrous layer with a fibrous web containing at least 50% by weight of highly shrinkable fibers having a shrinkage (S%) of at least 50%.

As the highly shrinkable fiber, a fiber comprising a polymer containing at least 70% by weight of an ethylene-propylene random copolymer (EP) having a melting peak temperature (Tm ° C.) of 130 <Tm <145 is preferable.

Further, the highly shrinkable fiber may be a polymer (E)
P) of at least 70% by weight and a melting peak temperature (Tm
C) of 130 <Tm <145.
Fibers composed of a mixed polymer of butene-1 terpolymer (EPB) are preferred. Further, a small amount of an olefin-based polymer such as polypropylene (PP) may be mixed with the mixed polymer of EP and EPB.

The above-mentioned olefin-based dry heat shrinkable fiber, particularly EP
When the fiber consisting of only the fiber is stretched about three times, it shows a dry heat shrinkage of 93% within 1 minute at 130 ° C. just below the melting point.
That is, it is 7% of the original length, and EP is the most easily shrunk to dry heat as a material, and then EPB is easily shrunk to dry heat . Therefore it is preferable to intensive EP, depending on the application may need to control the high shrinking EP, than EP to the extent that the maximum dry heat yield <br/> shrinkage does not fall below 50% dry heat A polymer having a small shrinkage may be mixed.

[0017] a temperature at the above melting peak temperature is DSC curve when performing differential thermal calorimetry of polymer (DSC) shows the maximum value, also with the maximum dry heat shrinkage,
It refers to the highest shrinkage ratio in the shrunk state of the heated fiber while maintaining the fiber shape.

In general, fibers for nonwoven fabrics are produced by attaching an aqueous solution of a fiber treating agent such as an antistatic agent during production and then drying the fibers. Therefore, fibers having a shrinkage temperature exceeding 100 ° C. are used. Also to lower significantly the shrinkage stress fibers is melted, dry
Depending on the time of the heat shrinking process, if the fiber is devised so that it does not completely melt, the dry heat shrinking temperature (T ° C is 1 ° C)
The range of 00 <T <= Tm + 30 is preferable.

The fibers constituting the second fiber layer include wood fibers such as cotton and hemp, animal hair such as wool, and natural fibers such as raw silk.
Conveniently use fibrous materials generally called fibers, such as synthetic fibers such as rayon and acetate and synthetic fibers such as polypropylene, polyester, acrylic, nylon, vinyl chloride and vinylon that do not melt at the dry heat shrinkage processing temperature. These can be used by mixing them with shrinkable fibers in the first fiber layer.

For example, in the bulky nonwoven fabric of the present invention for a wet wiper, a hydrophilic fiber such as rayon is used for the second fiber layer, and for a precision wiper, a combination of nylon and polyester or polyester and polypropylene is used. When the splittable conjugate fiber or the easily fibrillated acrylic fiber is used for the second fiber layer, and the filter or the mask, the splittable conjugate fiber or the easily fibrillated acrylic fiber is used alone or in combination with the general fiber, or the like. It is convenient to use.

When used for a precision wiper, a bulky nonwoven fabric is formed by arranging the second fiber layer on both sides of the first fiber layer having high shrinkage and entanglement between fibers and heat treatment to form wrinkles on both sides. It is desirable to be able to use both front and back surfaces as wiping surfaces. When disposing the second fiber layers on both surfaces, it is more convenient to make one of the second fiber layers lower in weight than the other second fiber layer and to form wrinkles of different sizes on the front and back.

The second fiber layer may be a spunbonded nonwoven fabric or a meltblown nonwoven fabric having a gradual adhesion, or may be composed of an aggregate of long fibers such as a towed web.

The bulky nonwoven fabric of the present invention, thickness apparent after dry heat shrinking treatment has a more than double the thickness of the dry heat shrinking treatment before the entangled nonwoven fabric, have a large number of wrinkles were clustered in the surface are doing. In order to obtain such a bulky nonwoven fabric, the fibers of the second fiber layer are mixed and entangled in the first fiber layer containing at least 50% of the above-described high- shrinkage fibers before performing the dry heat shrink processing. Is essential. Such entire web laminated by dry-heat treatment in a state under a thickness uniformly contracted is increased, the surface bulky nonwoven fabric having a large number of wrinkles dense (surface of the second fiber layer) can get.

The nonwoven apparent after dry heat shrinkage treatment thickness is, in the bulky nonwoven fabric that does not exceed 2 times the thickness of the dry heat shrinking treatment before the entangled nonwoven fabric, wrinkles interval that is formed on the surface When used as a wiper or a towel, for example, wrinkles lie down and it is difficult to maintain bulkiness, and when used as a filtering material, the fiber density difference between the wrinkled portion and the portion between the wrinkles is reduced. And a uniform filtering action cannot be expected over the entire surface. The preferred increase in thickness after dry heat shrinkage is about 250-600%.

As a method of entanglement between the fibers of the first fiber layer and the second fiber layer, the basis weight of the laminated fiber web is 15 to 1
The water jet method (also referred to as a spunlace method) using a high-pressure water stream is most convenient for those having a low basis weight of about 00 g / m ² , and in the case of a laminated fiber web having a high basis weight of about 100 to 300 g / m ² . In addition to the water jet method using a high-pressure water flow, a needle punch method may be used. The contraction processing by dry heat treatment after fiber entanglement is preferably carried out in the absence of possible binding.

However, in order to obtain the bulky nonwoven fabric of the present invention having a large number of wrinkles on the surface, the basis weight of the laminated fiber web must be 15 times.
Bear in order to 250 g / m ^2, the laminated web is between fibers entangled with a water Jeffrey bract method by high-pressure water, it is advantageous to apply a dry heat treatment later scold, is not preferable too high basis weight. That dry heat shrinkage treatment processing confounding nonwoven may have to the 250 g / m ² or less of basis weight, a particularly preferred number of wrinkles on the surface of the second fibrous layer in basis weight entangled non-woven fabric of 25~60g / m ² Can be formed.

The ratio of the first fiber layer to the second fiber layer cannot be unconditionally determined due to factors such as the use, configuration, and basis weight. However, in order to increase wrinkles, the ratio of the first fiber layer is higher than that of the second fiber layer. Less is better. Then, due to the dry heat shrinkage processing, wrinkles are generated in the second fiber layer of the entangled nonwoven fabric, and at the same time, the first fiber layer becomes a higher-density fiber state, so that a fiber density difference is formed in the thickness direction of the nonwoven fabric. For example, when used as a filtering material such as a filter or a mask, the filtering area per unit area increases, and a deep-layer filtering function is exhibited, which is convenient for improving the filtering accuracy and the filtering life.

[0028]

According to the bulky nonwoven fabric of the present invention, the first fiber layer containing the high-shrinkable fibers and the second fiber layer made of general fibers are integrated by inter-fiber entanglement, and the high-shrinkable fibers shrink. Because the entire first fiber layer shrinks and the fiber density also increases, the second fiber layer is entangled and contracted and deformed, resulting in a large number of small pile loops irregularly densely packed in short ridges on the second fiber layer side. Wrinkles are formed. The wrinkles are formed by an irreversible action, and the bulky deformation of the second fiber layer is fixed, and the wrinkles do not grow even when tension is applied, and are not easily eliminated.

Therefore, for example, when the second fiber layer is made of rayon, it becomes a bulky nonwoven fabric which is rich in flexibility and excellent in water retention, and improves the function as a towel or wiper. In the case where the second fiber layer is composed of hydrophobic fibers, the surface area of the hydrophobic fibers increases. For example, when used as a filtering material, it exhibits a deep filtration effect and improves filtration accuracy and filtration life. Contribute.

[0030]

Example Preparation of Fibers Fibers were formed under the respective spinning conditions using EP, EPB and PP shown in Tables 1 and 2, and after applying a fiber treating agent such as an antistatic agent, the fibers were mechanically crimped in a stuffing box. And dried by a conveyor-type hot air penetration dryer at 60 ° C., and cut into a length of 51 mm to form staples. Tables 1 and 2 show the fiber performance of the staple measured by a conventional method.

A commercially available rayon (2 denier, 51
mm), acrylic fiber (2 denier, 45 mm), and polyester fiber (1.5 denier, 38 mm).

[0032]

[Table 1]

[0033]

[Table 2]

In Tables 1 and 2, single: a single fiber obtained by spinning a kind of polymer. Blended: Single fiber spun by mixing two or more polymers. S / S: Side-by-side composite fiber, and the mixing ratio indicates the composite ratio. Splitting: 8-split fiber with a fiber cross section of a windmill type. PET: polyethylene terephthalate. The dry heat shrinkage (%) was obtained by measuring the shrinkage when a bundle of 100 fibers was exposed to each temperature. MFR is 230
Measured in ° C. However, PET was measured at 280 ° C.

[Examples 1 to 13 and Comparative Examples 1 to 3] As shown in Tables 3, 4 and 5, two types of webs used for the first fiber layer and the second fiber layer were prepared. And water jet method (water pressure 40 kg / cm ² )
Thus, the constituent fibers of the first fiber layer and the second fiber layer were entangled. However, Examples 6, 7, 8 and 9 are 120 kg / cm.
Pressure water of ² was used. In Examples 6, 7, and 9, the weight of the second fiber layer was divided into two, that is, 20 g / m ² and 10 g / m ² . Further, for the first fiber layer of Example 8, a parallel web in which the A fibers were oriented in the length direction was used.

Next, the nonwoven fabric in which the first fiber layer and the second fiber layer are entangled with each other is heat-treated for 1 minute at the processing temperatures shown in Tables 3, 4 and 5 to shrink the first fiber layer. In the comparative example, the apparent thickness was about twice that of the entangled nonwoven fabric, but in all of the examples, the apparent thickness was 2.5 times or more that of the entangled nonwoven fabric. A bulky nonwoven fabric having many wrinkles such that fine pile loops were irregularly densely packed in a short ridge shape on the surface of the fiber layer was obtained.

A conveyor type hot air penetration type dryer was used for the heat treatment. Tables 3, 4 and 5 show the results.
And the strength and elongation of Examples 1 and 8 and Comparative Example 1 are shown in Table 6.

[0038]

[Table 3]

[0039]

[Table 4]

[0040]

[Table 5]

[0041]

[Table 6]

The bulky nonwoven fabric of the present invention of Example 1 was impregnated with a diluted kitchen liquid detergent, and a gas range contaminated with oil was wiped off. As a result, it could be wiped off as quickly as a commercially available kitchen wiper. . In addition, since there is less expansion and contraction than commercially available products, the degree of dirt oozing on the back side is small,
My hands were hard to get dirty.

The bulky nonwoven fabric of Example 5 was cut into a strip having a width of 25 cm, wound tightly around a porous cylinder having an outer diameter of 35 mm until the outer diameter reached 65 mm, and the wound end was melted and fixed with an electric iron. Both ends were melted and sealed with a hot plate to obtain a cartridge type cylindrical filter. Similarly, a cylindrical filter having the same shape as a heat-bonded nonwoven fabric having a basis weight of 40 g / m ² using heat-bonding fiber NBF (H) (manufactured by Daiwa Spinning Co., Ltd.) having PP of 2 denier as a core component and polyethylene as a sheath component is used. Had made.

When the non-woven fabric of Example 5 was used, it was a cylindrical filter having the same outer diameter, and the winding length was 1 / the length of the above-mentioned heat-bonded non-woven fabric.
3 and productivity was improved. Using the above two types of cylindrical filters, a filtration test was conducted in which a suspension of test dust (Kanto loam, average particle size: 30 μl) having a concentration of 200 ppm was penetrated from the outside to the inside hollow part. Even with the amount of water at which the water pressure increases due to clogging of the cylindrical filter around which the nonwoven fabric is wound, the water pressure does not increase so much in the nonwoven fabric cylindrical filter of Example 5, and an improvement in the filtration life was confirmed.

The bulky nonwoven fabric of the present invention obtained in Example 8 has a particularly large shrinkage in the longitudinal direction, an apparent thickness of 2 mm or more, and a fine pile on the surface on the second fiber layer side. A large number of wrinkles, such as loops, which are irregularly densely packed in a short ridge shape, are prominently formed, and the back side of the first fiber layer is densified by excessive shrinkage of the A fiber. Had a hard surface. Therefore, when this bulky nonwoven fabric was used as a bath towel, the foaming of the soap on the second fiber layer side was extremely good, and the back side exhibited a function as scouring.

[0046]

Bulky nonwoven fabric according to the present invention Thus, the present invention is heated up to a dry heat shrinkage rate (S%) are Ru <br/> Oh at least 50% by melting peak temperature (Tm ° C.) is 130 <Tm <14
5 ethylene-propylene random copolymer (EP)
The at least a second fiber layer made of other fibers on one side position of the first fibrous layer comprising a high yield <br/> contraction fibers comprising a polymer comprising at least 70 wt% or more at least 50% by weight, these two layers The first fiber layer is shrunk by the dry heat treatment to form a plurality of wrinkles on the surface, and the apparent thickness is twice or more the thickness of the entangled nonwoven fabric. Therefore, the basis weight is much lower than that of a conventional nonwoven fabric having the same thickness as the apparent thickness of the bulky nonwoven fabric of the present invention, which is economical.

In addition, since it is rich in flexibility, has a large apparent thickness, and has a large number of wrinkles on the surface without shape collapse,
When used as a wiper, wrinkles on the surface exhibit an excellent wiping effect, and dirt does not easily seep to the back side, so that it is easy to use. Further, when used as a filtering material, the surface area per unit area is increased, and there is a fiber density gradient, so that clogging hardly occurs and the filtering life can be improved.

When the bulky nonwoven fabric of the present invention is used as a simple mask, in addition to the same effect as the above-mentioned filtering material, since a thin high density layer is present, a high density layer using a melt blown nonwoven fabric or the like is used as a component. There is an advantage that the airflow resistance is smaller and particles can be considerably removed. Furthermore, since the bulky nonwoven fabric of the present invention has a low fiber density as a whole and is bulky and flexible, it exhibits an excellent effect as a heat retaining material for clothing and the like, and the bulky nonwoven fabric obtained in Example 8 above. Is suitable as a bath towel.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) D04H 1/00-18/00

Claims (3)

(57) [Claims] 1. A maximum dry heat shrinkage ratio due to heating (S%) are Ru least 50% der, melting peak temperature (Tm ° C.) of 1
Ethylene-propylene random copolymer with 30 <Tm <145
Poly containing at least 70% by weight of polymer (EP)
A second fiber layer composed of other fibers is located on at least one side of a first fiber layer containing at least 50% by weight of a high- shrinkable fiber composed of a polymer, and these two layers are entangled with each other by a water jet method using a high-pressure water flow. The first fiber layer is shrunk by dry heat treatment of the entangled nonwoven fabric to form a large number of wrinkles due to the second fiber layer, and the apparent thickness is twice or more the thickness of the entangled nonwoven fabric. A bulky nonwoven fabric characterized by having. 2. The highly shrinkable fiber has a melting peak temperature (Tm).
° C) is 130 <Tm <145.
And Ndamukopo Rimmer the (EP) at least 70 wt.%,
An ethylene-propylene-butene-1 terpolymer having a melting peak temperature (Tm ° C.) of 130 <Tm <145 (EP
The bulky nonwoven fabric according to claim 1, comprising a mixed polymer with B). 3. The first fiber layer has a basis weight of 5 to 40 g / m ² ,
The second fiber layer dividable composite fibers or consists of easily fibrillated acrylic fibers bulky nonwoven fabric of claim 1 wherein the basis weight is 10 to 50 g / m ^2.