JP2002013060A - Nonwoven fabric for sand-protecting sheet and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonwoven fabric for a sand-protecting sheet, hardly generating fuzz and the propagation of the fuzz even on being exposed to water flow or wave for a long period of time and not opening a hole. SOLUTION: This nonwoven fabric for the sand-protecting sheet is provided by laminating a short fiber nonwoven fabric obtained by interlacing short fibers consisting of a thermoplastic polymer over at least the one side surface of a long fiber nonwoven fabric obtained by interlacing long fibers consisting of the thermoplastic polymer so as to laminate them as on unit at the laminated surface by interlacing the constituting fibers of the above short fiber nonwoven fabric and the long fiber nonwoven fabric each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric for a sandproof sheet suitable for a filter material for preventing the outflow of soil particles at the time of revetment of a river or reclamation of the sea in the field of civil engineering and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, woven fabrics made of synthetic fibers and needle-punched nonwoven fabrics made of long fibers or short fibers have been used for civil engineering filter materials. However, although the woven fabric has a high strength in the vertical and horizontal directions, it has a problem that the elongation is small, it is difficult to follow the unevenness of the base, and it is easily broken. Further, there is a problem that once a tear occurs, the tear is easily propagated in the vertical or horizontal direction.

[0003] On the other hand, a needle-punched nonwoven fabric made of long fibers or short fibers has a larger elongation than a woven fabric and can easily follow a base material, so that breakage hardly occurs. However, the needle-punched nonwoven fabric made of long fibers is slightly fuzzy on the surface of the needle-punched nonwoven fabric at the site where it is exposed to a flow or a wave.
There is a problem that tears and holes occur. Further, the needle-punched nonwoven fabric made of short fibers does not propagate fluff, but has a low strength, so that it is necessary to increase the basis weight in order to obtain strength, and there is a problem that the cost is high.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is difficult for fluff and propagation of fluff to occur even when exposed to a flow or a wave for a long period of time, and a hole is not formed. An object of the present invention is to provide a nonwoven fabric for a sandproof sheet.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have reached the present invention. That is, the present invention has the following (1) to (4).

(1) A short-fiber nonwoven fabric formed by intermingling short fibers made of a thermoplastic polymer is laminated on at least one surface of a long-fiber nonwoven fabric formed by intermingling long fibers made of a thermoplastic polymer. Is a nonwoven fabric for a sandproof sheet, wherein constituent fibers of the long-fiber nonwoven fabric and the short-fiber nonwoven fabric are laminated and integrated by being entangled with each other.

(2) The short-fiber nonwoven fabric according to the above (1) has a binder fiber in which at least a part of the fiber surface is formed of a binder component, and the constituent fibers of the short-fiber nonwoven fabric are thermally bonded by the binder component. A nonwoven fabric for a sandproof sheet, comprising:

(3) A short-fiber non-woven web made of a thermoplastic polymer is laminated on at least one surface of a long-fiber non-woven web made of a thermoplastic polymer to obtain a laminate. Needle punching is performed from the web side, and between long fibers, short fibers and on the laminated surface,
A method for producing a nonwoven fabric for a sandproof sheet, wherein long fibers and short fibers are entangled and laminated and integrated.

(4) The short-fiber nonwoven web in (3) above has a binder fiber having at least a part of the fiber surface formed of a binder component, and is subjected to a needle punching treatment, followed by a hot air treatment, A method for producing a nonwoven fabric for a sandproof sheet, wherein the binder component is melted or softened, and the constituent fibers of the short-fiber nonwoven fabric are thermally bonded to each other with the binder component.

[0010]

Next, the present invention will be described in detail. The constituent fibers of the long-fiber nonwoven fabric and the short-fiber nonwoven fabric in the present invention are made of a thermoplastic polymer having a fiber-forming property, and as the thermoplastic polymer having a fiber-forming property,
Examples include a polyester-based polymer, a polyamide-based polymer, and a polyolefin-based polymer.

As the polyester polymer, an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid or an aliphatic dicarboxylic acid such as adipic acid or sebacic acid is used as an acid component, and ethylene glycol, Diethylene glycol, 1,4-butanediol, neopentyl glycol, cyclohexane-1,
A homopolyester polymer or copolymer containing 4-dimethanol or the like as a diol component is exemplified. Incidentally, these polyester-based polymers, paraoxybenzoic acid,
5-sodium sulfoisophthalic acid, polyalkylene glycol, bisphenol A, etc. may be added or copolymerized.

Examples of polyamide polymers include polyimino-1-oxotetramethylene (nylon 4), polytetramethylene adipamide (nylon 46), polycapramide (nylon 6), polyhexamethylene adipamide (nylon 66), Polyundecanamid (nylon 11),
Polymeta-xylene adipamide, poly-para-xylene decanamide, or a polyamide-based copolymer containing these monomers as a constitutional unit is exemplified. In particular, in the case of polytetramethylene adipamide (nylon 46), the polytetramethylene adipamide (nylon 46) contains 30 mol% of a polyamide component such as polycapramid, polyhexamethylene adipamide, or polyundecamethylene terephthalamide. A copolymer of polytetramethylene adipamide copolymerized below may be used.

Examples of the polyolefin polymer include aliphatic α-monoolefins having 2 to 18 carbon atoms, such as ethylene, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, -Octene, 1-
Homopolyolefin polymers composed of dodecene and 1-octadecene are exemplified. The aliphatic α-monoolefin may be used in other ethylenically unsaturated monomers such as butadiene,
It may be a polyolefin copolymer in which similar ethylenically unsaturated monomers such as isoprene, 1,3-pentadiene, styrene and α-methylstyrene are copolymerized. In the case of a polyethylene polymer, propylene, 1-butene, 1-hexene, 1-
Octene or a similar higher α-olefin may be copolymerized to 10% by mass or less, and in the case of a polypropylene polymer, ethylene or a similar higher α-olefin is 10% by mass or less to propylene. Copolymers may be used, but if the copolymerization ratio of the above-mentioned copolymers exceeds the above-mentioned mass%, the melting point of the copolymer is lowered and spinning operability is undesirably lowered.

Further, a blend in which two or more polymers selected from the above-mentioned polymers are blended within a range that does not impair melt spinnability may be used as a constituent polymer.

In the present invention, the fibers constituting the long-fiber nonwoven fabric and the short-fiber nonwoven fabric may be single-phase fibers composed of a single polymer as described above, or two or more polymers may be composed of a core-sheath. Composite fibers formed by compounding into a mold, a side-by-side mold, a split mold and the like may be used. Further, the fiber cross-sectional shape is not limited to a circular cross-section, and may be an irregular cross-section such as an ellipse, a triangle, a well, a multi-leaf, or a hollow cross-section.

The density of the fibers constituting the long-fiber nonwoven fabric and the short-fiber nonwoven fabric is preferably 1 g / cm ³ or more. If the fiber density is less than 1 g / cm ³ , the sandproof sheet may float when used in water, which is not preferable. However, even if the fiber density is less than 1 g / cm ³ , there is no problem as long as the entire sandproof sheet sinks in water.

The single fiber fineness of the constituent fibers of the long-fiber nonwoven fabric is 2
Preferably it is ~ 17 dtex. If the single yarn fineness is less than 2 dtex, the fibers are highly entangled, so that the fibers are too entangled in the needling step of entanglement of the fibers, and the obtained nonwoven fabric is inferior in extensibility. Considering the extensibility of
Since the entanglement must be reduced, not only sufficient strength is not obtained but also a nonwoven fabric for a sandproof sheet having a sufficient thickness tends to be not obtained. On the other hand, if it exceeds 17 decitex, the stiffness of the fiber increases, resulting in poor entanglement, and poor spinning stability and operability during the production of the nonwoven fabric. By setting the single fiber fineness of the constituent fibers of the long-fiber nonwoven fabric to 2 to 17 dtex, a nonwoven fabric for a sandproof sheet having sufficient mechanical strength, durability, and appropriate thickness for use can be obtained. A more preferable range of the single yarn fineness is 3 to 11 dtex.
In the long-fiber nonwoven fabric, if the single-fiber fineness is in the range of 2 to 17 decitex, even if it is a long-fiber nonwoven fabric having the same single-fiber fineness, a long-fiber nonwoven fabric obtained by mixing fibers of different finenesses It may be.

The fineness of the constituent fibers of the short-fiber nonwoven fabric in the present invention is preferably 0.1 to 17 dtex. If the fineness is less than 0.1 dtex, the spinning operability when obtaining short fibers is not preferable. On the other hand, when the fineness exceeds 17 dtex, similar to the case of the long fibers described above,
It is not preferable because the stiffness of the fiber is increased and confounding property by needling is inferior. A more preferable range of the single yarn fineness is 0.1 to 10 decitex.

When a fine fiber having a fineness of less than 2 dtex is used as a constituent fiber of the short-fiber nonwoven fabric, the fiber strength is low. It is easy to fall off. For this reason, the single fiber fineness of the short fibers is preferably less than 1.7 dtex, more preferably less than 1 dtex.

As a method for obtaining so-called ultrafine fibers of less than 1 dtex, a method of directly spinning, a method of dissolving the sea portion of the sea-island type composite staple fiber with a solvent or the like or breaking it by impact to obtain a fiber constituting the island portion. Method: A method of applying a physical impact to a splittable conjugate short fiber composed of two types of polymers incompatible with each other, thereby peeling off the boundary surface of each polymer to obtain an ultrafine fiber composed of each polymer. And the like. In the present invention, using a splittable composite short fiber,
When the long fiber nonwoven web and the short fiber nonwoven web are entangled and integrated in the needling step, it is preferable to simultaneously split the splittable conjugate short fibers by the impact of needling to express ultrafine fibers.

The short-fiber nonwoven fabric of the present invention preferably has binder fibers in which at least a part of the fiber surface is formed of a binder component, and the constituent fibers of the short-fiber nonwoven fabric are preferably thermally bonded to each other by the binder component. . Further, it is more preferable that the entire surface of the short fiber nonwoven fabric is thermocompression-bonded and the surface is smooth.

In a short-fiber nonwoven fabric, the main fibers (fibers that are not binder fibers) are thermally bonded with a molten binder component, thereby suppressing the generation of fluff during use and improving the effect of preventing soil particles from flowing out. Can be done.

In the nonwoven fabric for a sandproof sheet of the present invention,
A short-fiber nonwoven fabric is laminated on at least one surface of a long-fiber nonwoven fabric. In use, the short-fiber nonwoven fabric surface is placed on the water flow side. Therefore, by the flow of water and the force of the waves,
When fluff is generated on the surface of the short fiber nonwoven fabric, the fluff composed of short fibers easily falls off the sandproof sheet due to the force of the water flow, and the fluff does not propagate. Further, when the fluff is adhered by the binder component, the fluff is easily cut from the adhered portion (adhesion fixing portion) and falls off the sandproof sheet. In addition, the short fiber nonwoven fabric, when the main fiber and the binder fiber are mixed, even if the binder fiber is fused by heat, since the main fiber maintains the fiber form, has an appropriate inter-fiber space, Suitable air permeability and good soil particle outflow prevention properties (filter properties) can be provided.

The binder fiber is made of a polymer having a melting point lower than the melting points of the main fibers constituting the short-fiber nonwoven fabric and the constituent fibers of the long-fiber nonwoven fabric (for those having no melting point, the softening point is regarded as the melting point). The difference between the melting point of the binder component and the melting point of the constituent fibers of the main fiber and the long-fiber nonwoven fabric is preferably 20 ° C. or more.

The binder fiber may be a single-phase type fiber comprising only a binder component, such as a core-sheath type, a side-by-side type, a sea-island type, and a split type in which the binder component forms all or a part of the surface of the fiber. Conjugate fiber.

As the polymer used as the binder component, copolymerized polyester, nylon, copolymerized nylon,
Examples include polyethylene, polypropylene, and copolymers thereof. When the composite fiber is used as the binder fiber, examples of the combination include high-melting polyester / low-melting polyester, polyester polymer / polyolefin polymer, polyester polymer / polyamide polymer, high-melting polyamide / low-melting polyamide, and polypropylene. / Polyethylene and the like.

The mixing ratio of the binder fibers is preferably 5 to 50% by mass in order to exhibit an adhesive effect. If the mixing ratio is less than 5% by mass, the amount of the binder component that bonds the main fibers to each other is small, and the effect of mixing the binder fibers is not exhibited. On the other hand, if the mixing ratio exceeds 50% by mass, the nonwoven fabric for a sandproof sheet becomes too hard due to heat treatment due to a large amount of a binder component, and the elongation of the sandproof sheet is undesirably hindered.

In addition to the presence or absence of the binder fiber, if the entire surface of the short-fiber nonwoven fabric is thermocompression-bonded and the surface is smooth, the generation of fluff can be further suppressed, and the space between fibers can be reduced. This is preferable because the filter effect of preventing outflow of soil particles is improved.

In the present invention, the basis weight of the long-fiber nonwoven fabric is 8
0-1000 g / m < ² > is preferable, More preferably, it is 20 g / m < ² >.
0 to 900 g / m ² , short fiber nonwoven fabric weight is 50 to 30
0 g / m < ² > is preferable, More preferably, it is 80-250 g.
/ M ² , the basis weight of the nonwoven fabric for a sandproof sheet is 200 to 1200
g / m ² is preferable, and more preferably 300 to 1000
g / m ² .

If the basis weight of the long-fiber nonwoven fabric is less than 20 g / m ^2, it is not preferable because the nonwoven fabric for a sandproof sheet cannot have sufficient strength. On the other hand, if it exceeds 1000 g / m ² , not only is it expensive in price, but also the initial load becomes high, and it becomes difficult to follow the unevenness of the base during laying, which is not preferable because it is difficult to use.

If the basis weight of the short-fiber nonwoven fabric is less than 50 g / m ² , the short-fiber nonwoven fabric cannot provide a sufficient fluffing effect, and the long-fiber nonwoven fabric of the inner layer is exposed to the surface during a long-term use, and fluff is generated. And fluff propagation will occur. Further, since the number of fibers is relatively reduced, the fibers are not easily entangled with each other, and the operation stability during needling is poor, which is not preferable. On the other hand, if it exceeds 300 g / m ² , if binder fibers are contained as short fiber nonwoven fabric,
During the heat treatment, the heat is not sufficiently transmitted in the short fiber nonwoven fabric, so that the adhesive fixing effect cannot be obtained.

The basis weight of the nonwoven fabric for a sandproof sheet is 200 g / m
^If it is less than ² , depending on the use environment, it will be difficult to prevent the outflow of soil particles. On the other hand, if it exceeds 1200 g / m ² , the raw materials and processing costs will be expensive, and the nonwoven fabric will be hard. It is difficult to follow the unevenness of the base when laying, and a problem is likely to occur in use.

The nonwoven fabric for a sandproof sheet of the present invention comprises a long-fiber nonwoven fabric and a short-fiber nonwoven fabric laminated on at least one surface of the long-fiber nonwoven fabric. The long-fiber nonwoven fabric and the short-fiber nonwoven fabric are integrated by three-dimensionally intermingling the constituent fibers with each other. And
And, at the interface between the long-fiber nonwoven fabric and the short-fiber nonwoven fabric, the constituent fibers of each other are three-dimensionally entangled,
It is integrated as a whole. Therefore, the nonwoven fabric for a sandproof sheet of the present invention has integrity even in the thickness direction by being entangled, and does not cause delamination in the form of a layer when used. Also,
Since the fibers are integrated by entanglement, the fibers have an appropriate degree of elongation as a nonwoven fabric, and can easily follow the unevenness of the base during laying. As a method of entanglement of the constituent fibers, a needle punch method is preferably used.

Next, a preferred method for producing the nonwoven fabric for a sandproof sheet of the present invention will be described. A short fiber non-woven web made of a thermoplastic polymer is laminated on at least one surface of a long fiber non-woven web made of a thermoplastic polymer to obtain a laminate, which is subjected to a needle punching treatment.

When laminating a long-fiber nonwoven web and a short-fiber nonwoven web, even if the short-fiber nonwoven web is laminated on one surface of the long-fiber nonwoven web, It may be formed by laminating short fiber nonwoven webs on both sides, and may be appropriately selected depending on the place where the sandproof sheet is laid and the application.

[0036] The long fiber nonwoven web may be one in which constituent fibers are pre-pressed or pre-heat-pressed with pressure and / or low-temperature heat to facilitate transportation.

The long fiber nonwoven web can be obtained by a known spunbonding method. In view of the thermal stability of the fiber, the melt spinning speed is preferably 3000 m / min or more. 3
If it is less than 000 m / min, crystallization does not progress, shrinkage occurs during heat treatment, and workability becomes unstable.

On the other hand, a short fiber nonwoven web is obtained by mixing a main fiber and preferably a predetermined amount of a binder fiber in a cotton mixing machine, and using a carding machine to prepare a carded web having a predetermined basis weight. . This card web is
Various selections can be made according to the degree of arrangement of the fibers.For example, a parallel web in which fibers are arranged in the traveling direction of the card machine, a cross-laid web in which parallel webs are cross-laid, the orientation of fibers is randomly arranged without directionality. Random web or semi-random web.

The needle density in the needling step of performing a needle bunch treatment on a laminate formed by laminating a long-fiber nonwoven web and a short-fiber nonwoven web varies depending on the shape and insertion depth of the needling needle. Although not limited, 20 to 300 times / cm ² is preferable. Needle density is 20
If it is less than times / cm ² , the constituent fibers of the long-fiber nonwoven web and the short-fiber nonwoven web are not sufficiently entangled with each other, so that it is difficult to obtain sufficient strength to withstand use, and delamination tends to occur.
On the other hand, when the needle density exceeds 300 times / cm ² , the constituent fibers of the long-fiber nonwoven web and the short-fiber nonwoven web are excessively three-dimensionally entangled with each other, and the obtained nonwoven fabric for a sandproof sheet is excessively tightened. Although the interspace becomes too small to increase the strength, the stress in the initial stage of elongation increases, the elongation of the nonwoven fabric decreases, and the nonwoven fabric does not easily follow the irregularities of the base during use, and is easily broken.

In the needling, it is necessary to perform the needling at least from the short fiber nonwoven web side.

A needle-punching treatment is performed, and a short-fiber nonwoven fabric in which short fibers are entangled is laminated on at least one surface of a long-fiber nonwoven fabric in which long fibers are entangled. And the nonwoven fabric for a sandproof sheet of the present invention, which are laminated and integrated with each other.

When a binder fiber is mixed as a constituent fiber of the short-fiber nonwoven fabric, a hot air treatment is performed after needle punching to melt or soften the binder component, and the constituent fibers of the short-fiber nonwoven fabric are thermally bonded to each other. Let it. The heat bonding makes it possible to prevent the generation of fluff due to waves and to prevent the surface short fibers from falling off during use. Also,
Since the interfiber voids are fixed, the effect of preventing the outflow of soil particles (filter effect) is improved. As the hot air treatment method, the nonwoven fabric obtained after the needling step may be passed through a hot air circulation type heat treatment machine or the like to melt or soften the binder component. As the processing temperature of the hot air circulation type heat treatment machine, when the processing is performed at a temperature equal to or higher than the melting point of the binder component (for those having no melting point, the softening point is regarded as the melting point) and lower than the melting point of the binder component, Adhesion is not sufficiently obtained, and the effect of preventing generation of fluff is not sufficiently exhibited. On the other hand, when the treatment is performed at a temperature equal to or higher than the melting point of the polymer other than the binder component, even the fibers other than the binder component are softened.
It melts and the whole non-woven fabric becomes hard, does not have an appropriate elongation, and is hard to follow irregularities of the base during use, and is easily broken.

In the present invention, after the needle punching treatment or the hot air treatment, the fabric is passed through a full-surface thermocompression bonding device composed of a pair of smooth rolls, and at least the short fiber nonwoven fabric surface is entirely thermocompression-bonded to smooth the surface. Is preferred.

In the full-surface thermocompression bonding apparatus, various thicknesses can be obtained according to the place of use or the basis weight of the sandproof sheet by appropriately selecting the clearance between the rolls. The degree of thermocompression bonding can be selected by appropriately selecting the roll set temperature, the roll linear pressure, and the processing temperature.

As the roll setting temperature, when the short fiber non-woven fabric does not contain a binder fiber, the glass transition temperature of the thermoplastic polymer constituting the short fiber (hereinafter, referred to as “rolling temperature”).
Tg. ) Set to a temperature not lower than the melting point. If the roll set temperature is lower than Tg, it is difficult to smooth the surface of the nonwoven fabric, and no fuzz prevention effect is exhibited. On the other hand, if the roll set temperature is equal to or higher than the melting point, the nonwoven fabric is fused to the roll, which deteriorates the surface state of the nonwoven fabric and significantly impairs operability.

When the short fiber nonwoven fabric contains a binder fiber, the roll setting temperature is (Tm−20) ° C. or more, where Tm is the melting point of the binder component.
+10) It is preferable that the temperature be lower than 0 ° C. If the roll set temperature is lower than (Tm-20) ° C., even if the clearance between the rolls is set to 0 mm and pressure is applied, the binder component does not sufficiently soften and melt, so that the desired nonwoven fabric having a smooth surface is obtained. Can not. On the other hand, if the roll set temperature exceeds (Tm + 10) ° C., the binder component softens and melts more than necessary and fuses to the roll, which significantly impairs the operability. The preferred range of the roll set temperature is
(Tm-5) ° C or higher and lower than (Tm + 5) ° C.

The set temperature of the two smoothing rolls may be appropriately selected depending on the structure of the nonwoven fabric, and may be the same or different.

For the roll linear pressure, the roll set temperature,
The thickness may be appropriately selected in consideration of the thickness of the obtained nonwoven fabric for a sandproof sheet, and may be a pressure sufficient to adjust the thickness.

The clearance between the rolls is a factor that determines the thickness of the obtained nonwoven fabric for sandproof sheet, and is appropriately selected according to the place where the sandproof sheet is used, the basis weight of the sandproof sheet, and the like. However, the clearance is set smaller than the thickness of the nonwoven fabric before the heat treatment. If the clearance is equal to or larger than the thickness of the nonwoven fabric before the heat treatment, due to insufficient contact between the nonwoven fabric and the roll, heat is not sufficiently transmitted as the binder component is melted, and the nonwoven fabric surface tends to be less smooth. . On the other hand, the clearance may be 0 mm, but in this case, in order to obtain a stable product, it is difficult to adjust the roll set temperature and the linear pressure, and the operation stability tends to be poor.

[0050]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. The measurement of each characteristic value in the examples was performed by the following method.

(1) Melting point (° C.): Differential scanning calorimeter DSC-2 manufactured by Perkin Elmer Co., Ltd .;
/ Min, and the temperature at which an extreme value was obtained in the obtained melting endothermic curve was defined as the melting point.

(2) Melt index (hereinafter abbreviated as MI): Measured according to the method described in ASTM-D-1238 (E).

(3) Relative viscosity: The relative viscosity of the polyester was measured by the following method. A mixture of phenol and ethane tetrachloride in an equal weight was used as a solvent, and 0.5 g of a sample was dissolved in 100 cm ³ of the solvent.

(4) Weight (g / m ² ): Ten samples of 10 cm long × 10 cm wide were prepared from the sample in the standard condition.
After reaching the equilibrium water, the mass (g) of each sample piece was weighed, and the average of the obtained values was converted per unit area (m ² ) to obtain the basis weight (g / m ² ).

(5) Thickness (mm): JIS-L-109
The measurement was performed according to the method described in No. 6. That is, the thickness (mm) was measured at an initial load of 6.86 cN / cm ² using a thickness measuring device (manufactured by Daiei Kagaku Co., Ltd.) at five different locations of the sample, and the average value was defined as the thickness.

(6) Tensile strength (N / 5 cm width): JIS
-Measured according to the method described in L-1096A. That is, 10 points of a sample having a sample width of 5 cm and a sample length of 30 cm were prepared, and a gripping distance of 2 was measured using a constant-speed elongation-type tensile tester (manufactured by Toyo Baldwin: Tensilon RTM-500).
It was measured at 0 cm and a tensile speed of 20 cm / min, and the average value at 10 points was defined as tensile strength (N / 5 cm width). Further, the tensile strength was measured in the MD direction (machine direction) and the CD direction (direction orthogonal to the machine direction) of the nonwoven fabric.

(7) Elongation at break (%): The average value of the elongation at the time of exhibiting the maximum strength in the measurement of tensile strength was defined as the elongation at break (%).

(8) Fluffiness: JIS-L-1096C
The measurement was carried out according to the method described in (1). That is, the diameter 13c
Five circular test pieces of m are prepared, a hole having a diameter of about 6 mm is formed at the center of each test piece, and the test piece is mounted on a sample holder with the surface of the test piece facing upward using a Taber abrasion tester. Load 2.
A 45N abrasion wheel was placed on the test piece and rubbed 100 times. Then, the appearance was observed and judged as follows. ：: No fuzz is observed. Δ: Fuzz is observed, but no propagation is observed. X: Fuzz is generated / transmitted.

Example 1 A long-fiber nonwoven web was produced by a spunbond method using polyethylene terephthalate having a melting point of 255 ° C. and a relative viscosity of 1.38. That is, the polymer was passed through a spinneret having a round fiber cross section by an extruder-type melt extruder to melt and spin a yarn. At the time of melt spinning, the polymer was melt-spun at a melting temperature of 290 ° C. and a single hole discharge rate of 1.60 g / min. After cooling the melt-spun yarn with a known cooler, the yarn is drawn off using an air sucker at a drawing speed of 4000 m / min, opened using a known opening device, and collected on a moving collecting surface. -It was deposited and subjected to temporary thermal pressure welding to obtain a long-fiber nonwoven web. In the preliminary thermal pressure welding treatment, an embossing roll and a metal roll having a smooth surface were used, and the surface temperature of both rolls was set to 120 ° C. The basis weight of long fiber non-woven web is 100g
/ M ² , and the single-fiber fineness was 4 dtex.

On the other hand, short fibers constituting the short fiber nonwoven web are polyethylene terephthalate having a relative viscosity of 1.385 and a melting point of 257 ° C.
The yarn was spun from a spinneret having a diameter of 2 mm, and the spun yarn was cooled by blowing air from a cooling device, an oil agent was applied, and the yarn was taken up as an undrawn yarn through a take-up roller. The speed of the take-off roller was 1100 m / min. Next, 24 undrawn yarns were drawn and aligned, and two stages of roller drawing were performed between a group of rollers having 7 rollers to obtain 4 undrawn yarns.
Draw 5 times to make the single yarn fineness 6 decitex, 180 ° C
After heat-setting, a crimp of 30/25 mm was applied by a press-in type crimping device and cut into 51 mm to obtain short fibers.

The obtained short fibers were carded with a parallel card machine, and five layers of a 20 g / m ² card web were cross-laid to obtain a 100 g / m ² short fiber nonwoven web.

Next, after the oil agent was applied to the long-fiber non-woven web, three layers were laminated, and a laminated body in which the short-fiber non-woven web was laminated on both surfaces thereof was obtained. A needle punch machine (needle: PB-40 manufactured by Foster Co., Ltd.) #) Needle depth 12 mm, needle density 52 times / c
Needling was performed from both sides under the conditions of m ² to obtain a nonwoven fabric for a sandproof sheet.

Example 2 8 mol% of isophthalic acid in ethylene terephthalate units
Using a copolymerized polyester having a melting point of 230 ° C. and a relative viscosity of 1.44 and the polyethylene terephthalate used in Example 1, a long-fiber nonwoven web composed of a core-sheath composite fiber was prepared by a spunbond method. That is, using both extruder-type melt extruders, the copolymers were placed on the sheath and the polyethylene terephthalate was placed on the core, and the core-sheath composite fiber was melt-spun through a core-sheath spinneret. . For melt spinning, set the melting temperature to 2
Melting composite spinning was performed under the conditions of 85 ° C., a single hole discharge rate of 3.33 g / min, and a composite ratio (mass ratio) of copolymerized polyester and polyethylene terephthalate of 1/1. After the spun yarn is cooled by a known cooler, it is taken out at a drawing speed of 5,000 m / min using an air sucker, and is collected and deposited on a moving collecting surface using a known opening device. Let
Temporary heat welding was performed to obtain a long-fiber nonwoven web. In the preliminary thermal pressure welding treatment, an embossing roll and a metal roll having a smooth surface were used, and the surface temperature of both rolls was set to 140 ° C. The basis weight of the web was 100 g / m ² , and the single-fiber fineness was 6 dtex.

On the other hand, as the short fibers constituting the short fiber nonwoven web, the short fibers made of polyethylene terephthalate and the binder fibers used in Example 1 were used. The binder fiber is a core-sheath type using the polyethylene terephthalate used in Example 1 and a copolymerized polyester having a relative viscosity of 1.335 and a softening point of 110 ° C. obtained by copolymerizing 40% by mole of isophthalic acid with ethylene terephthalate unit. Using a composite spinneret, the copolyester was placed in the sheath and the polyethylene terephthalate was placed in the core, melted and spun out, and spun and stretched in the same manner as in Example 1 to give 4 dtex x 51.
mm of binder fiber was obtained.

A fiber made of polyethylene terephthalate and a binder fiber are mixed at a ratio of 70/30 (mass ratio) and carded with a semi-random card machine to obtain a basis weight of 1.
A 50 g / m ² short fiber nonwoven web was obtained.

Next, after the oil agent was applied to the long-fiber non-woven web, four sheets were laminated, and a laminate in which the short-fiber non-woven web was laminated on one side thereof was obtained. A needle punching machine (needle: PB-36 manufactured by Foster Co., Ltd.) #) Needle depth 9 mm, needle density 65 times / cm
^Under the conditions of ² , needling was performed from both sides to obtain a nonwoven fabric.

Next, the obtained nonwoven fabric was guided to an air-through type heat treatment machine and heat-treated at 125 ° C. to obtain a nonwoven fabric for a sandproof sheet of the present invention.

Example 3 In obtaining a nonwoven web of long fibers, in Example 1, the single hole discharge amount during melt spinning was set to 1.60 g / min, and the pulling speed of air soccer was set to 5040 m / min. ,
The same as in Example 1 except that the surface temperature of both rolls at the time of the preliminary heat pressure welding was set to 160 ° C., the basis weight was 100 g / m 2.
^2. A long-fiber non-woven web having a single yarn fineness of 10 dtex was obtained.

On the other hand, as short fibers constituting the short fiber nonwoven web, short fibers made of polyethylene terephthalate used in Example 1 were used as main fibers, and core-sheath type fibers used in Example 2 were used as binder fibers. Instead of the copolyester of the sheath portion (binder component) of the conjugate short fiber, a 4 dtex × 51 mm binder fiber made of a polyethylene polymer having a melting point of 130 ° C. and an MI of 15 g / 10 min was used.

In preparing a nonwoven web of short fibers, the same procedure as in Example 1 was carried out except that short fibers made of polyethylene terephthalate and binder fibers were mixed at a ratio of 75/25 (mass ratio) in Example 1. To obtain a short fiber nonwoven web having a basis weight of 100 g / m ² .

Next, after the oil agent was applied to the long-fiber non-woven web, four sheets were laminated, and the short-fiber non-woven web was laminated on both sides thereof to obtain a laminate, and a needle punching machine (needle: PB- manufactured by Foster Co., Ltd.) 36 #), needle depth 9mm, needle density 90 times / cm
^{In step 2} , needling was performed from both sides of the laminate. Then
Using a full-surface thermal pressure welding device consisting of a pair of metal rolls having a smooth surface, a surface temperature of 122 ° C. and a clearance of 3 m between the rolls
m, and a treatment speed of 5 m / min, the obtained nonwoven fabric was passed between rolls and subjected to surface heat treatment to obtain a nonwoven fabric for a sandproof sheet of the present invention.

Example 4 In Example 2, as a nonwoven web of short fibers, split cotton <E91> made of polyethylene terephthalate and polyethylene and having a 4-fiber cross section as shown in FIG.
2 dtex x 51 mm (Nippon Ester Co., Ltd.)
A short-fiber nonwoven web having a basis weight of 70 g / m ² was used. As a heat treatment after needling, a full-surface heat welding device consisting of a pair of smooth surface metal rolls was used instead of an air-through type heat treatment machine. Used, surface temperature 128
A nonwoven fabric for a sandproof sheet of the present invention was obtained in the same manner as in Example 2 except that the surface heat treatment of the nonwoven fabric was performed at a temperature of 3 ° C., a clearance between rolls of 3 mm, and a processing speed of 5 m / min.

Comparative Example 1 In Example 1, the basis weight was 5 without using the non-woven short fiber web.
Except that only the long fiber non-woven web of 00 g / m ² was used.
In the same manner as in Example 1, a nonwoven fabric for a sandproof sheet made of long fibers was obtained.

Comparative Example 2 The mixing ratio of the polyethylene terephthalate fiber and the binder fiber used as the short fiber in Example 2 was set to 80/20 (mass%), and carding was performed using a parelel card machine to obtain a card web having a basis weight of 100 g / m ^2. A 5-layer cross laid fiber is laid on a short fiber nonwoven web having a basis weight of 500 g / m ² with a needle punching machine (needle: PB-36♯ manufactured by Foster Corporation) at a needle depth of 9 mm and a needle density of 65 times / cm ^2. Needling was performed from both sides of the above to obtain a nonwoven fabric.

Next, the obtained nonwoven fabric was introduced into an air-through hot air treatment machine and heat-treated at 125 ° C. to obtain a nonwoven fabric for a sandproof sheet composed of short fibers.

The evaluation results of the obtained nonwoven fabrics for sandproof sheets of Examples 1-4 and Comparative Examples 1-2 are shown in Table 1.

[0077]

[Table 1]

As is clear from Table 1, the nonwoven fabric for a sandproof sheet of the present invention obtained in Examples 1 to 4 had sufficient strength for practical use and high elongation at break. Example 1
Since the nonwoven fabric for sand-proofing sheet was not subjected to a heat treatment, in the evaluation of fuzziness, a slight fuzziness was observed. Therefore, use in the middle period was sufficiently possible, and propagation of fluff could be prevented. Since the nonwoven fabric for sandproof sheets of Examples 2 to 4 was subjected to heat treatment, the nonwoven fabric had excellent fuzziness on the side surface of the short fiber nonwoven fabric and could withstand use for a very long period. . In Example 4, since the splittable conjugate fiber was used as the constituent fiber of the short fiber, in the needle punching treatment, the fiber was split into segments and polyethylene as a low melting point polymer functioned as a binder component. Was.

On the other hand, with respect to the nonwoven fabric for a sandproof sheet of Comparative Example 1, the strength and the elongation at break were practical, but the fluff generated by abrasion propagated and the nonwoven fabric was torn.

Since the nonwoven fabric for a sandproof sheet of Comparative Example 2 was composed of only short fibers, it had low strength, many fibers fell off due to abrasion, and could not withstand a long-term use.

[0081]

According to the nonwoven fabric for a sandproof sheet of the present invention,
Since the fibers constituting the nonwoven fabric are three-dimensionally entangled, they have an appropriate degree of elongation, and can follow the unevenness of the base when used as a sandproof sheet. In addition, since the nonwoven fabric for a sandproof sheet has a short-fiber nonwoven fabric laminated on at least one surface of a long-fiber nonwoven fabric, the long-fiber nonwoven fabric can maintain sufficient mechanical strength, durability, and elongation for use, On the other hand, on the surface of the short-fiber nonwoven fabric, when affected by the water flow, even if fluff occurs on the surface of the short-fiber nonwoven fabric, it is a short fiber, that is, the fiber length is short and there is no fiber end like a long fiber Because it is not a thing, it can easily fall off from the sandproof sheet with the power of further water flow,
The fluff does not propagate and the sheet itself does not tear.

Further, in the nonwoven fabric for a sandproof sheet of the present invention in which the short-fiber nonwoven fabric has binder fibers and the constituent fibers of the short-fiber nonwoven fabric are thermally bonded to each other with the binder fibers, the short fibers are fixed by heat. Because it is difficult to generate fluff, it can be used satisfactorily over a long period of time, and even if fluff occurs, no propagation of fluff is seen because the short fibers are cut off from the heat bonded part and fall off Things.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a cross-sectional shape of a splittable conjugate short fiber used as a short fiber in the present invention.

Claims (7)

[Claims] A short-fiber nonwoven fabric formed by entangled short fibers made of a thermoplastic polymer is laminated on at least one surface of a long-fiber nonwoven fabric formed by entangled long fibers made of a thermoplastic polymer. A nonwoven fabric for a sandproof sheet, wherein constituent fibers of the long-fiber nonwoven fabric and the short-fiber nonwoven fabric are laminated and integrated by being entangled with each other. 2. The short-fiber nonwoven fabric has a binder fiber in which at least a part of the fiber surface is formed of a binder component, and constituent fibers of the short-fiber nonwoven fabric are thermally bonded to each other by the binder component. The nonwoven fabric for a sandproof sheet according to claim 1, wherein 3. The nonwoven fabric for a sandproof sheet according to claim 1, wherein at least the entire surface of the short fiber nonwoven fabric is thermocompression-bonded and has a smooth surface. 4. A sandproof sheet comprising the nonwoven fabric for a sandproof sheet according to any one of claims 1 to 3. 5. A laminate obtained by laminating a short-fiber non-woven web made of a thermoplastic polymer on at least one surface of a long-fiber non-woven web made of a thermoplastic polymer, and obtaining at least a short-fiber non-woven web of the laminate. Needle punching from the side,
A method for producing a nonwoven fabric for a sandproof sheet, characterized in that long fibers and short fibers are entangled with each other and on the laminating surface so that the long fibers and short fibers are entangled and laminated and integrated. 6. A short-fiber nonwoven web comprising binder fibers having at least a part of the fiber surface formed of a binder component, and after needle punching, hot air treatment is performed to melt or soften the binder component. The method for producing a nonwoven fabric for a sandproof sheet according to claim 5, wherein the constituent fibers of the short-fiber nonwoven fabric are thermally bonded to each other with a binder component. 7. After the needle punching treatment or the hot air treatment, the sheet is passed through a full-surface thermocompression treatment device comprising a pair of smooth rolls, and at least the short fiber nonwoven fabric surface is entirely thermocompression-bonded to smooth the surface. The method for producing a nonwoven fabric for a sandproof sheet according to claim 5 or 6.