JPH073598A - Nonwoven fabrics and fabric lamination - Google Patents

Abstract

PURPOSE:To produce a nonwoven fabrics of the high density which has not been accomplished in the past by interlacing fibers which is made of a specific copolymer and has high shrinkage higher than a specific value. CONSTITUTION:The fiber layers containing 30wt.% of high-shrinkage fibers of greater than 50% of maximum shrinkage, made of a polymer containing more than 70wt.% of ethylene-propylene random copolymer satisfying the equation: 130<Tm<145 where Tm is fusion peak temperature are interlaced by the water jet method, needle punch method or the like to form the first fiber layer of 10 to 100g/m<2> unit weight. On the one surface of the first fiber layer, the second fiber layer of 10 to 100g/m<2> unit weight, made of other fibers such as natural fibers or synthetic fibers is laminated, they are interlaced, then heat- treated to allow the whole of the interlaced nonwoven fabric to shrink into the nonwoven fabric having never-attained high density readily and easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulky and high apparent density nonwoven fabric obtained by heat-treating highly shrinkable fibers.

[0002]

2. Description of the Related Art As a known example for post-processing a non-woven fabric to increase the fiber density, a bulky non-woven fabric in which a large number of wrinkles are formed on the surface of the non-woven fabric to increase the apparent thickness of the non-woven fabric, is disclosed in JP-A-2-160962. There is an example in which the shrinkability of elastic crimp elastic fibers or elastic fibers described in Japanese Patent Publication is used. As the highly shrinkable fiber, a polyvinyl alcohol fiber having a water absorbing and swelling effect described in JP-A-60-2709 is put into practical use and described in JP-A-58-214550. There are examples of polyolefin-based heat-shrinkable fibers that use α-olefins having a carbon number of butene or higher and propylene copolymers with a propylene content of 50 to 85 mol% that utilize heat-shrinking properties, but in both cases, the degree of shrinkage is a nonwoven fabric. There is no example in which the overall density was reduced to an apparent density of about 0.1.

Further, the inventors of the present invention disclosed a spun yarn and a woven knit of highly shrinkable fibers in Japanese Patent Laid-Open No. 5-44108, but the invention did not reach a highly shrinkable nonwoven fabric.

[0004]

The conventional dry heat-shrinkable fibers usually have a maximum shrinkage of 30 to 40%, no fibers shrink further, and the fibers shrinkable from these dry heat-shrinkable fibers are as described above. Although there are wet heat shrinkable polyvinyl alcohol fibers, but the shrinkage stress is small, bulky nonwoven fabric or high density nonwoven fabric in which the fiber density of the nonwoven fabric is positively increased by utilizing the shrinkage property to increase the thickness of the nonwoven fabric. It could not be used for the purpose, and these nonwoven fabrics were not realized. In addition, the uneven nonwoven fabric using the heat-shrinkable net is also another point in view of increasing the fiber density.

Even with the highly shrinkable fibers described in JP-A-5-44108, a highly shrinkable nonwoven fabric cannot be obtained by the method of directly heat-bonding the web. In the filter field, a non-woven fabric having a higher fiber density is required to capture finer particles, but an expensive non-woven fabric has been used because the present non-woven fabric cannot handle it. In addition, although there is a great demand for a woven or knitted product or a molded product in which a large number of wrinkles are attached to a metal foil, there is a problem because there is no means for providing it at low cost.

[0006]

DISCLOSURE OF THE INVENTION The inventor of the present invention has made a fiber having a significantly higher shrinkage than conventional ones alone or mixed with other fibers, and after making a card web with a roller card, a needle punching method or a spunlace method. By forming a entangled nonwoven fabric in which fibers are entangled and integrated by a method and shrinking the highly shrinkable fibers in the nonwoven fabric, it is possible to easily shrink the entire nonwoven fabric to a nonwoven fabric having a high fiber density. I came to the present invention. That is, the present inventor first developed fibers having a significantly higher shrinkage than conventional ones, and used the fibers alone or mixed them with other fibers suitable for the purpose to improve the fiber density of the nonwoven fabric. In addition, it has succeeded in easily producing a nonwoven fabric in which the fibers are unevenly distributed in the thickness direction and a density gradient of the fibers is provided.

The highly shrinkable fibers used in the present invention are opened to form a web, and the entire web does not shrink even when the fibers are shrunk. That is, unless at least the fibers are intertwined with each other and connected, the entire fiber assembly cannot be contracted. As described above, the present invention is a combination of a remarkably highly shrinkable fiber and a method of performing a shrinking treatment in a state where the fibers are connected and integrated.

According to the present invention, a entangled nonwoven fabric in which a fiber assembly containing at least a highly shrinkable fiber having a shrinkage ratio of more than 50% is integrated by interfiber entanglement is used to freely shrink as much as possible by using a pin tenter or the like to obtain the entire fiber assembly. To increase the fiber density of the fiber assembly, resulting in a bulky nonwoven fabric, a high-density nonwoven fabric, a nonwoven fabric having a fiber density gradient, and a bonded nonwoven fabric having wrinkles in the bonded product. .

If the shrinkable fiber cannot have a shrinkage ratio exceeding 50%, the shrinkage of the entangled nonwoven fabric becomes insufficient when the fiber entanglement is strong or when mixed cotton is used, which is not preferable.
Moreover, even if the shrinkable fiber has a shrinkage ratio of about 80%,
When blended with 50% or more of other ordinary fibers, shrinkage may not be sufficient for some purposes, and blending of more than 70% is not preferable. When mixed cotton is used, a entangled nonwoven fabric in which a shrinkable fiber layer and another ordinary fiber layer are layered is more preferable because of good shrinkability.

That is, according to the present invention, the maximum heat shrinkage (S%)
At least 50% high shrinkable fiber
A fiber layer containing 0% by weight is integrated by the entanglement of the fibers constituting them, and the highly shrinkable fiber is shrinked by heat treatment, which is a nonwoven fabric.

The highly shrinkable fiber used is a fiber made of 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.

Further, the high shrinkable fiber is made of the above-mentioned polymer (E
P) of at least 70% by weight and melting peak temperature (Tm
(C) is 130 <Tm <145, and is a fiber made of a mixed polymer with an ethylene-propylene-butene-1 terpolymer (EPB).

Further, as the highly shrinkable fiber, a fiber made of a ternary mixed polymer in which a small amount of polypropylene (PP) is further mixed with the above-mentioned mixed polymer of EP and EPB can be used.

As the other fiber, a polyester-based heat-shrinkable or heat-shrinkable fiber can be used, and any fiber having a shrinkage ratio of more than 50% can be conveniently used.

In the above-mentioned olefin-based heat-shrinkable fiber, EP is the easiest material to be heat-shrinked, and EPB is the second most likely to be heat-shrinked, so it is preferable to use a large amount of EP. In some cases, the material conditions are limited to the above range in which the maximum heat shrinkage exceeds 50%.

When a fiber made of EP alone is stretched about 3 times, it exhibits a heat shrinkage ratio of 93% within 1 minute at 130 ° C. just below the melting point. That is, the fiber is 7% of the original length.

The melting peak temperature of the present invention is the temperature at which the DSC curve at the time of carrying out the differential calorimetry (DSC) of the polymer shows the highest value.

The maximum heat shrinkage ratio is the maximum shrinkage ratio in the shrinking state in which the heated fiber maintains the fiber shape.

Generally, the fibers for a non-woven fabric are produced by adhering an aqueous solution of a fiber treatment agent such as an antistatic agent on the production and drying, but the same applies to the present invention, and those having a shrinkage temperature of more than 100 ° C. are used.

When the fibers are melted, the shrinkage stress is remarkably reduced. Therefore, depending on the time of the heat shrinking process, if the fiber is not completely melted, the heat shrinking process temperature (T ° C.) is 100 <T. The range of <= Tm + 30 is preferable.

The fibers to be mixed include cotton, hemp and other wood fibers, wool and other animal fibers, raw silk and other natural fibers, rayon and acetate and other chemical fibers, and polypropylene, polyester, acrylic, nylon, vinyl chloride and vinylon. A fibrous material commonly referred to as a fiber, such as a synthetic fiber that does not melt at the heat shrink processing temperature, can be conveniently used.

When the non-woven fabric of the present invention is used as a thick wiper, hydrophilic fibers such as rayon are mixed, and when it is used as a precision filter, fibers having the finest possible fineness, or division treatment or fibrillation treatment and entanglement treatment are performed. It is particularly preferable to use a water jet method using a high-pressure water flow of about 120 kg / cm ² capable of simultaneously performing the above, and to mix the splittable conjugate fiber and the easily fibrillated acrylic fiber by a combination of nylon and polyester or polyester and polypropylene. When used as a filter material such as a filter or a mask, it is preferable that the shrinkable fiber and the other fiber are not simply mixed but used in the state of being laminated in layers. In such a case, the general fiber may be a spunbonded nonwoven fabric or a meltblown nonwoven fabric with loose adhesion, and may be an aggregate of long fibers such as a tow opening web.

In the nonwoven fabric of the present invention, it is necessary that the constituent fibers are entangled with each other before heat shrinking. By heat-treating the highly entangled highly shrinkable fibers, the entire web is uniformly shrunk to obtain a nonwoven fabric having a high fiber density.

As the method for entanglement of fibers, the water jet method or the spunlace method using a high-pressure water stream that can be produced with a thin weight is most convenient, and the needle punch method is also preferable for a high weight. However, in the present high-density non-woven fabric, it is advantageous to shrink the entangled non-woven fabric, and it is not preferable to use the high-entangled non-woven fabric.
The basis weight is preferably g / m ² or less, and the basis weight is 15 to 10
Preferably ^{0g / m 2, 25~60g / m} 2 is particularly preferred.

It is preferable that the shrinking process is carried out in a state as free as possible. Since the entangled nonwoven fabric shrinks due to the shrinking process, the shrinkage rate of warp and weft and the area shrinkage rate were evaluated in the examples. In addition, when a layer containing shrinkable fibers (first fiber layer) and a layer consisting only of other fibers are laminated, the first fiber layer of the entangled non-woven fabric due to shrinkage processing has a higher density fiber state. Therefore, the filtration accuracy is improved without using ultrafine fibers.

[0026]

INDUSTRIAL APPLICABILITY The nonwoven fabric of the present invention contains highly shrinkable fibers and is integrated by interfiber entanglement. When the highly shrinkable fibers shrink, the entangled nonwoven fabric as a whole shrinks and the fiber density increases. , Becomes a non-woven fabric that shrinks in the thickness direction and has a density gradient. Also, when it is mixed with other fibers, the other fibers are caught and contracted and deformed. The high-density non-woven fabric or the non-woven fabric with a fiber density gradient of the present invention is densified due to the shrinkage of the shrinkable fibers, so that it is made by an irreversible action. Or the fiber density gradient is maintained. Therefore, unlike reversible materials such as elastic fibers,
Deformation does not disappear easily.

As described above, there is a difference in the fiber density between the fiber layer containing the shrinking fiber and the fiber layer not containing the shrinking fiber, and a nonwoven fabric having a density gradient is obtained, which enables deep layer filtration and is extremely convenient as a filter material. There is.

[0028]

【Example】

Preparation of fibers EP, EPB and PP shown in Table 1 were made into fibers under the conditions shown in Table 1, a fiber treating agent such as an antistatic agent was added, and mechanical crimping was performed in a stuffing box, and hot air was conveyed at 60 ° C. It was dried with a through-type dryer and cut into a staple having a length of 51 mm. The fiber performance measured by the conventional method is shown in Table 1.
And shown in Table 2. Further, commercially available polyethylene terephthalate and nylon having a denier of 2 mm and 51 mm were prepared.

[0029]

[Table 1]

[0030]

[Table 2]

In the above Tables 1 and 2, single; single fiber mixed with one kind of polymer mixed; single fiber mixed with two kinds of polymer and spun S / S; parallel type composite fiber, mixed The ratio indicates the composite ratio Split; 8-section fiber with a wind turbine type cross section PET; Polyethylene terephthalate NY; Nylon The dry heat shrinkage (%) of 100 fibers bundled when exposed for 20 seconds at each temperature The shrinkage ratio was measured. NMR
Was measured at 230 ° C. However, PET and NY are 28
It was measured at 0 ° C.

[0032]

【Example】

[Examples 1 to 14 and Comparative Examples 1 to 5] A card web was formed using the above fibers, and the fibers were entangled with each other and then heat treated to obtain the nonwoven fabric of the present invention. Further, two kinds of webs were laminated to obtain a nonwoven fabric in the same manner. The results are shown in Table 3,
It shows in Table 4 and Table 5.

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

In the above Tables 3, 4 and 5, R: rayon 2 denier, 51 mm AC; acrylic 2 denier, 45 mm PET; polyester 1.5 denier, 38 mm Entangling method N is needle punch method, S is spun lace method , N-S represent the combined use of needle punch and spun lace. The non-woven fabric shrinkage rate is obtained by subjecting a test piece of 20 cm × 20 cm to heat treatment for 1 minute with a conveyor hot air processing machine, and then [1- (length after heat processing (cm) × width after heat processing (cm)) ÷ (20
cm × 20 cm)] × 100 (%).

The interlacing between fibers was carried out by high density punching using a needle punching machine, or pre-punching and spunlacing with pressure water of 40 kg / cm ² to obtain a entangled nonwoven fabric.

The heat treatment was carried out for 1 minute at a predetermined temperature with a conveyor type hot air dryer. However, in Examples 10 and 11,
12 is a sandwich state in which the second fiber layers are arranged on both sides of the first fiber layer containing the heat-shrinkable fibers, respectively, and 120
Spunlace processing was performed with pressure water of kg / cm ² .

The apparent density of the nonwoven fabric obtained in Example 1 was measured. The surface of the non-woven fabric was uneven, but the thickness was measured almost uniformly when viewed from the side. The results are as follows. Heat treatment temperature (° C) Apparent density (g / cm ³ ) 120 0.08 130 0.17 140 0.24 150 0.40

When the non-woven fabric of Example 1 was impregnated with a diluted kitchen holding liquid detergent and the gas range soiled with oil was wiped,
I was able to wipe it off as quickly as the trial wiper for kitchen use. In addition, since it is less stretchable and harder than the sponge for trial sale, it does not bleed dirt on the back side,
My hands were hard to get dirty.

The nonwoven fabric of Example 10 was wound tightly around a porous cylinder, the winding ends were melted and fixed with an electric iron, and both ends of the resulting cylinder were melted and sealed with a hot plate to form a cartridge type cylindrical filter. did. In the same way, we made a heat-bonded nonwoven fabric using our heat-bonded fiber NBF (H) with 2 denier PP as the core component and polyethylene as the sheath component, and made a test dust (Kanto loam, average particle size) with a concentration of 200 ppm into them. (30 μm in diameter) When the suspension was filtered by pouring it from the outside to the inside hollow part, the cylindrical filter wrapped with NBF (H) non-woven fabric clogs the water and the water pressure rises. Was able to be filtered without rising.

After the polyester plain weave having a basis weight of 120 g / m and the aluminum foil having a thickness of 15 μm were bonded to the entangled nonwoven fabric obtained in Example 1 with a foaming urethane adhesive, heat shrinkage treatment was performed at 140 ° C. Wrinkles on the fabric and foil gave the appearance similar to crepe fabric.

[0043]

INDUSTRIAL APPLICABILITY The high-density non-woven fabric or the non-woven fabric having a fiber density gradient according to the present invention can be manufactured easily and easily as compared with the conventional equivalent products, and therefore can be manufactured at low cost, which is convenient. In particular, when used as a filter material such as a filter, there is a fiber density gradient, which is convenient because clogging hardly occurs and the filtration life is improved. A simple mask having a nonwoven fabric having a density gradient of the present invention as a constituent element is easy to stack thin high density layers in multiple stages, and has a ventilation resistance higher than that of a constituent having a high density layer using a melt blown nonwoven material as a constituent element. There is little possibility that even very small particles can be removed. In the high-density nonwoven fabric of the present invention, a woven or knitted fabric or a soft metal foil having a low basis weight is adhered to the entangled nonwoven fabric before the shrinking treatment, and when the shrinking treatment is applied, the entangled nonwoven fabric is caught in the shrinkage of the entangled nonwoven fabric and attached to the surface of the nonwoven fabric Also has a contraction effect, but in consideration of the tensile strength of the adhered object, it is possible to cause a phenomenon in which wrinkles are randomly generated in the adhered object.

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Claims (5)

[Claims] 1. The maximum heat shrinkage (S%) is at least 50.
%, A fiber layer containing at least 30% by weight of highly shrinkable fibers is integrated by the entanglement of the fibers constituting them, and the highly shrinkable fibers are shrunk by heat treatment. 2. The maximum heat shrinkage (S%) is at least 50.
% Of highly shrinkable fibers are at least one surface of the first fibrous layer having a basis weight of 10 to 100 g / m ² comprising at least 30 wt%, the second fiber layer having a basis weight of 10 to 100 g / m ² made of other fibers is laminated A bonded non-woven fabric characterized in that constituent fibers of both fiber layers are entangled with each other, and the high shrinkage fibers are contracted by heat treatment. 3. The high shrinkable fiber has a melting peak temperature (Tm).
3. The non-woven fabric according to claim 1, which is made of a polymer containing at least 70% by weight of an ethylene-propylene random copolymer (EP) having a temperature of 130 <Tm <145. 4. The highly shrinkable fiber comprises at least 70% by weight of the polymer (EP) according to claim 3, and an ethylene-propylene-butene-1 ternary material having a melting peak temperature (Tm ° C.) of 130 <Tm <145. The non-woven fabric according to claim 1 or 2, which is composed of a mixed polymer with a copolymer (EPB). 5. The non-woven fabric according to claim 1, wherein the highly shrinkable fiber comprises a ternary mixed polymer obtained by further mixing polypropylene (PP) with the mixed polymer according to claim 4.