JPH11315460A - Weather-resistant filament nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weather-resistant filament nonwoven fabric suitable as a material for the field requiring weather resistance, especially as a material, for construction, building and agriculture. SOLUTION: The objective nonwoven fabric is a nonwoven web composed of a core-sheath conjugate filament containing a polyester as the core component and a polyolefin as the sheath component and the web is partially hot-pressed to form a prescribed form. The sheath component composed of the polyolefin contains a weather-resistant agent satisfying the following requirements (a) to (c). (a) The agent is a particulate material composed of cerium oxide crystallized on silica or talc; (b) the surface of the agent is coated with amorphous silica and (c) the average particle diameter of the agent is 0.05-3 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field where weather resistance is required, and particularly to a weather-resistant long-fiber nonwoven fabric suitable as a material for civil engineering materials, construction materials or agricultural materials.

[0002]

2. Description of the Related Art Conventionally, various nonwoven fabrics made of thermoplastic polymers such as polyester and polyolefin have been used as materials for civil engineering materials, building materials or agricultural materials. However, in recent years, repetitive use for two to three years has been required for some disposable applications, for example, for agricultural materials such as heat insulating lining sheets for agricultural houses. Accordingly, there is a demand for a nonwoven fabric having better weather resistance than these conventional nonwoven fabrics.

Conventionally, benzotriazole-based or benzophenone-based organic ultraviolet absorbers, titanium oxide or zinc oxide have been used for the purpose of improving the weather resistance, in particular, preventing the deterioration of the material due to exposure to ultraviolet rays in sunlight. Various additives such as inorganic ultraviolet blocking agents composed of fine particles have been employed. However, such a method of adding an organic UV absorber causes problems such as the inability to cut out a wide range of UV light and the UV absorption effect not being maintained for a long time, and a high degree of weather resistance in agricultural and building materials. It does not provide sufficient weather resistance to be used in the required fields, and is inferior in heat resistance. On the other hand, the method of adding such an inorganic ultraviolet blocking agent has a problem that the additive itself is inferior in dispersibility and transparency.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves such a problem, and has excellent weather resistance, in particular, a weather-resistant long-fiber nonwoven fabric excellent in a function of preventing deterioration of a material due to exposure to ultraviolet rays. The purpose is to provide.

[0005]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problem, and has the following constitution as its gist. A nonwoven fabric comprising a polyester-core component and a core-sheath type composite filament having a polyolefin sheath component, and a non-woven web partially heated and pressed to maintain a predetermined form, wherein the sheath comprising the polyolefin A weather-resistant long-fiber nonwoven fabric, characterized in that the component contains a weathering agent satisfying the following (a) to (c). (A) A granular material obtained by crystallizing cerium oxide on silica or talc. (B) The surface is coated with amorphous silica. (C) The average particle size is 0.05 to 3 μm.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the long fibers constituting the weather-resistant long-fiber nonwoven fabric of the present invention will be described. The long fiber applied to the present invention has a core-in-sheath type composite structure, and the polyester forming the core component includes polyethylene terephthalate or polybutylene terephthalate, or a polyester mainly composed of these. Further, a copolymerized polyester containing a carboxylic acid such as isophthalic acid or adipic acid as an acid component and / or a tetramethylene glycol, neopentyl glycol or the like as a diol component may be used. When the copolymerized polyester is used, the content of the ethylene terephthalate unit or the butylene terephthalate unit is at least 80 mol%.
It is preferable from the viewpoint of the heat resistance of the polymer material itself and the strength of the obtained nonwoven fabric. As the polyester applied in the present invention, those having an intrinsic viscosity of 0.5 or more, preferably 0.6 or more, from the viewpoint of the spinning property and the strength of the obtained long fiber,
preferable.

The polyolefin forming the sheath component of the long fiber applied in the present invention includes high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and crystalline polypropylene. In the case of crystalline polypropylene, a polypropylene obtained by randomly copolymerizing ethylene with polypropylene may be used in order to improve the spinning property. In the present invention,
When the polyolefin applied as the sheath component is polyethylene, the melt index value measured according to the method described in ASTM-D-1238 (E) is 10 to 40 g /.
Preferably, it is 10 minutes. When the polyolefin used as the sheath component is polypropylene, AST
The melt flow rate measured according to the method described in MD-1238 (L) is preferably 40 to 100 g / 10 min. If the upper limit of the preferred melt viscosity range is exceeded, the melt viscosity is too low, resulting in inferior fiber uniformity, and the resulting long-fiber nonwoven fabric tends to be uneven. On the other hand, if the melt viscosity is less than the lower limit of the suitable melt viscosity range, the melt viscosity is too high, resulting in inferior high-speed spinning properties, which is not preferable.

The weathering agent applied to the present invention is silica (excluding amorphous silica coating the surface of the granular material) or granular material obtained by crystallizing cerium oxide on talc, and absorbs ultraviolet rays. This has the function of preventing deterioration of the material due to exposure to ultraviolet light. The weight ratio of cerium oxide to silica or talc is preferably 15/85 to 50/50. When the weight ratio of cerium oxide to silica or talc is less than 15, the function of absorbing ultraviolet rays to improve the weather resistance in the obtained long-fiber nonwoven fabric becomes insufficient, and conversely, the weight ratio of cerium oxide to silica or talc becomes insufficient. Exceeds 50, the brightness of the obtained long-fiber nonwoven fabric decreases. In addition, the weathering agent has a surface of the granular material coated with amorphous silica as described above, and is composed of a granular material composed of cerium oxide and silica of amorphous silica or a cerium oxide and talc. The weight ratio to the granular material is preferably 15 to 25% by weight. If the weight ratio is less than 15% by weight, the mechanical strength of the granular material itself is low, and the surface activity becomes strong to cause a catalytic action. Conversely, the weight ratio becomes 25% by weight.
If it exceeds 300, the function of absorbing ultraviolet rays and improving weather resistance in the obtained long-fiber nonwoven fabric becomes insufficient. Furthermore, in this weathering agent, the average particle diameter needs to be 0.05 to 3 μm, and if the average particle diameter is less than 0.05 μm, the dispersibility in the sheath component of the core-sheath type composite continuous fiber is reduced. Drop,
Conversely, if the average particle size exceeds 3 μm, the function of absorbing ultraviolet rays to improve weather resistance in the obtained long-fiber nonwoven fabric becomes insufficient, and the color tone of the nonwoven fabric deteriorates.

In the present invention, it is necessary that the sheath component of the core-sheath type composite continuous fiber contains a weathering agent satisfying the above (a) to (c) as a weathering agent. because,
This is because sunlight is absorbed from the fiber surface layer, so that the weathering performance can be more effectively exhibited by intensively containing the weathering agent in the sheath component. Further, in the present invention, when the same weathering agent is contained in the core component in addition to the sheath component, more excellent weathering performance can be exhibited. because,
This is because the deterioration of the polymer can be efficiently suppressed by completely absorbing a part of sunlight reaching the core component by the weathering agent contained in the core component. Therefore, even if this weathering agent is contained only in the core component, the effects of the present invention cannot be obtained.

In the present invention, the content ratio of the weathering agent contained in the sheath component of the core-sheath type composite filament is 0.05 to 1%.
It is preferred to be in the range of 0% by weight. When the content ratio of the weathering agent contained in the sheath component is less than 0.05% by weight,
If the obtained long-fiber nonwoven fabric does not have sufficient weather resistance, and if the content ratio of the weather-resistant agent exceeds 10% by weight, the particles of the weather-resistant agent are coagulated when melt-spun long fibers, resulting in poor thread-forming properties. In particular, when the nonwoven fabric of the present invention is produced by a spunbond method having a spinning speed of 2500 m / min or more, thread breakage frequently occurs, which is not preferable. When the same weathering agent is contained in the core component in addition to the sheath component, the content ratio of the weathering agent contained in the core component is preferably in the range of 0.05 to 10% by weight. is there. If the content ratio of the weathering agent contained in the core component is more than 5% by weight, the particles of the weathering agent are aggregated when melt-spinning the long fiber, thereby deteriorating the spinnability. For this reason, when the weathering agent is contained in both the sheath component and the core component, the content ratio of the weathering agent contained in the core component is set to 0.05 to 5% by weight. It is more preferable to set the content ratio of the weathering agent to be at most 5% by weight.

Although the reason why the long-fiber nonwoven fabric of the present invention exhibits excellent weather resistance is not clear, the present inventors have found that the weathering agent containing cerium oxide absorbs ultraviolet energy and suppresses the generation of radicals. Therefore, it is presumed that the deterioration of the core component polyester due to absorption of ultraviolet rays is prevented. The weathering agent composed of cerium oxide and silica or the weathering agent composed of cerium oxide and talc has unstable surface activity and insufficient light resistance and heat resistance, but the surface of the granular material is irregular silica. As a result, the particle surface becomes denser, and as a result, light resistance and heat resistance are improved.

In the present invention, if necessary, the polyester forming the core component and / or the polyolefin forming the sheath component may contain, for example, a matting agent, a pigment, a crystal nucleating agent, a flame retardant or an antioxidant. May be added as long as the effects of the present invention are not impaired.

[0013] The core-sheath type composite long fiber constituting the nonwoven fabric of the present invention comprises polyester as a core component having a relatively high melting point as a core component and polyolefin as a polymer having a melting point lower than that of polyester generally as a sheath component. In the present invention, the above-mentioned weathering agent is contained in polyolefin, which is a polymer having a relatively low melting point, and the main weathering resistance is expressed by using this as a sheath component. By incorporating the above-mentioned weathering agent therein, the sunlight transmitted through the sheath component can be completely absorbed to complement the main weather resistance, and the nonwoven fabric can have excellent weather resistance.

In the core-sheath type composite continuous fiber constituting the nonwoven fabric of the present invention, the compounding ratio of the core component and the sheath component may be appropriately determined according to the application, but if the sheath component is too small, sufficient weather resistance will be obtained. Therefore, it is usually preferable to select the weight ratio of the sheath component to the core component in the range of about 0.5 to 3.0.

In the core-sheath composite long fiber constituting the nonwoven fabric of the present invention, the single-fiber fineness may be appropriately determined according to the application, but is usually selected in the range of 2.0 to 10 denier. Is preferred. If the single-fiber fineness is less than 2.0 denier, yarn breakage tends to occur at the time of spinning, resulting in poor spinning operability. Conversely, if the single-fiber fineness exceeds 10 denier, the texture of the resulting nonwoven fabric is hard and poor in flexibility.

Next, the weather-resistant long-fiber nonwoven fabric of the present invention will be described. The nonwoven fabric of the present invention is one in which a nonwoven web made of such a core-sheath composite long fiber is partially hot-pressed to maintain a predetermined form. The partial heat-welding of the nonwoven web is to form a point-like fused area in which the constituent long fibers are partially hot-welded by embossing or ultrasonic welding, and the core of the polymer is used. Since it is composed of the sheath-type composite continuous fiber, it has excellent flexibility despite its shape being maintained by partial heat welding. In the partial thermal pressure welding of the nonwoven fabric, it is preferable that the ratio of the area of all the point-like fusion zones to the entire area of the nonwoven web, that is, the pressure contact area ratio be 4 to 50%. If the pressed area ratio is less than 4%, the number of point-like fused areas is too small, resulting in poor strength and dimensional stability of the obtained nonwoven fabric, and fuzziness is likely to occur. Conversely, if the pressed area ratio exceeds 50%, the texture of the obtained nonwoven fabric is hard and the flexibility is inferior.

In the nonwoven fabric of the present invention, the basis weight is
Although it is not determined unconditionally because it is selected depending on the purpose of use, it is generally preferable to be in the range of 10 to 150 g / m ² . If the basis weight is less than 10 g / m ² , mechanical performance such as strength is inferior, and conversely, the basis weight is 150 g / m 2.
^If it exceeds ² , the texture of the obtained nonwoven fabric will be hard and inferior in flexibility.

Next, a method for producing the weather-resistant long-fiber nonwoven fabric of the present invention will be described. The nonwoven fabric of the present invention can be efficiently produced by a so-called spunbond method.
That is, the above-mentioned weathering agent is mixed with the above-mentioned polymer chip as a sheath component by a masterbatch method or a dry blending method so that a predetermined amount is contained, and the mixture is melt-spun using a spinneret device having a core-sheath type composite cross section. After cooling the obtained spun yarn using a conventionally known cooling device such as a horizontal spraying or an annular spraying, it is drawn and thinned using a drawing device such as an air sucker so as to have a desired fineness, and is taken up. After the fibers are opened using a known fiber opening device, they are deposited on a moving deposition device consisting of a screen to form a web, and partially heat-welded using a hot pressure welding device consisting of a heated embossing roll and a flat roll. Thereby, a nonwoven fabric made of the core-sheath composite long fiber of the present invention can be obtained.

[0019]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In addition, each characteristic value in the following examples is
It was determined as follows. (1) Intrinsic viscosity of polyester: A sample concentration of 0.5 g / 1 using an equal weight mixture of phenol and ethane tetrachloride as a solvent.
The measurement was performed under the conditions of 00 cc and a temperature of 20 ° C. (2) Melt index value of polyethylene (g / 10
Min): Measured according to the method described in ASTM D-1238 (E). (3) Melting point (° C.): Measured at a temperature rising rate of 20 ° C./min using a differential scanning calorimeter DSC-2 manufactured by Perkin Elmer. (4) Fabric weight of nonwoven fabric (g / m ² ): From a sample in a standard state, 10 sample pieces each having a size of 10 cm × 10 cm were prepared and allowed to reach equilibrium moisture, and then the weight of each sample piece was measured. The average value of the measured values was converted per unit area, and the basis weight (g / m
² ) (5) Tensile strength of nonwoven fabric (kg / 5 cm width): Measured according to the synthetic long fiber nonwoven fabric test method. That is, using a constant speed elongation type tensile tester Tensilon UTM-4-100 manufactured by Toyo Baldwin Co., Ltd., a sample width of 5 cm and a sample length of 2
A sample piece of 0 cm was gripped and measured under the conditions of a gripping interval of 10 cm and a pulling speed of 10 cm / min, an average value of 10 measured pieces was determined, and the result was defined as a tensile strength (kg / 5 cm width). (6) Strong retention of nonwoven fabric (%): The weather resistance of the nonwoven fabric was evaluated by the following strong retention (%). That is, the nonwoven fabric was exposed outdoors, and the tensile strength after 4 months was measured in a standard state, and the ratio of the tensile strength value after the exposure to the initial value of the tensile strength before the exposure was defined as the strength retention rate (%). Strength retention (%) = (tensile strength after 4 months / initial value of tensile strength) × 100 ○: The strength retention is 70% or more, and the weather resistance is good. X: The strength retention was less than 70%, and the weather resistance was poor. (7) Yarn-forming property of long fiber: The spun yarn discharged from the spinneret was visually observed, and the yarn-making property was evaluated according to the following three stages based on the number of times of yarn breakage. ：: The number of thread breaks is 0 times / 1 spindle weight / 24 hours △: The number of thread breaks is 1-2 times / 1 spindle weight / 24 hours ×: The number of thread breaks is 3 times or more / 1 spindle weight / 24 time

In the examples, a weathering agent commercially available from Nippon Inorganic Chemical Industry Co., Ltd. under the trade name "Serigard" was used. The composition is as follows. Serigard T-3018: Granules formed by crystallizing cerium oxide in talc, the surface of which is coated with amorphous silica. The weight ratio of cerium oxide: talc: amorphous silica is 30:52:18. Serigard S-3018: Granules formed by crystallization of cerium oxide on silica, the surface of which is coated with amorphous silica. The weight ratio of cerium oxide: silica: amorphous silica is 30:52:18. Serigard S-2018: Granules obtained by crystallizing cerium oxide on silica, the surface of which is coated with amorphous silica. The weight ratio of cerium oxide: silica: amorphous silica is 20:62:18.

Example 1 Polyethylene terephthalate having a melting point of 260 ° C. and an intrinsic viscosity of 0.70 was used as a core component, and a melting point of 12 was used as a sheath component.
High-density polyethylene having a melt index value of 20 g / 10 min at 0 ° C. was used.
Stuff. ) Was mixed in a predetermined amount, and a core-sheath composite long-fiber nonwoven fabric was produced by a spun bond method. Experimental Example 1: 2.0% by weight of T-3018 (average particle size: 1.0 μm) Experimental Example 2: 1.0% by weight of T-3018 (average particle size: 1.0 μm) Experimental Example 3: Experimental Example 4: 1.0% by weight of S-3018 (average particle size: 2.0 μm) containing S-3018 (average particle size: 2.0 μm) Experimental Example 5: S-2018 ( Experimental Example 6: 1.0% by weight of S-2018 (average particle size: 1.5 μm) containing 2.0% by weight Experimental Example 7: T-3018 (average particle size: 1.5 μm) Experimental Example 8: T-3018 (average particle size: 1.0 μm) contained 1%
That is, the polymer chip was melted, melt-spun using a spinneret having a core-in-sheath composite cross section, and the obtained spun yarn was cooled using a cooling device. Thereafter, the fiber is drawn and thinned using an air sacker, the fiber is opened using a fiber opening device, and then deposited on a moving deposition device composed of a screen to form a web, at a temperature of 130 ° C. and a pressing area ratio of 20%. Partially heat-pressed using a heat-pressing device consisting of an embossing roll and a flat roll, and having a basis weight of 40 g / m
^Thus, a core-sheath type composite long fiber nonwoven fabric was obtained. Table 1 shows the evaluation results of the obtained nonwoven fabric.

Comparative Example 1 The procedure of Example 1 was repeated ^, except that 3.0% by weight of 2- (2 ^, -hydroxy-5 ^, -methylphenyl) benzotriazole ^, which is a benzotriazole ultraviolet absorber, was used as a weathering agent. Thus, a core-sheath type composite long-fiber nonwoven fabric having a basis weight of 40 g / m ² was obtained. Table 1 shows the evaluation results of the obtained nonwoven fabric.
Shown in

[0023]

[Table 1]

As is clear from Table 1, the nonwoven fabrics obtained in Experimental Examples 1 to 6 of Example 1 contained a predetermined weathering agent in the sheath component and were excellent in weatherability. Further, the nonwoven fabric obtained in Experimental Example 7 of Example 1 had a low content ratio of the weathering agent in the sheath component, and was not able to obtain sufficient weatherability. The nonwoven fabric obtained in Experimental Example 8 of Example 1 had a high weathering agent content ratio in the sheath component and was excellent in weather resistance, but was poor in thread formability. On the other hand, the nonwoven fabric obtained in Comparative Example 1 was inferior in both weather resistance and spinning properties.

[0025]

The weather-resistant long-fiber nonwoven fabric of the present invention has excellent weather resistance, and particularly has an excellent function of preventing deterioration of a material due to exposure to ultraviolet rays. Therefore, it is suitable as a material for civil engineering materials, building materials, agricultural materials, or the like.

Claims (2)

[Claims] A nonwoven fabric comprising a nonwoven web comprising a core-sheath composite long fiber having polyester as a core component and polyolefin as a sheath component, which is partially hot-pressed to maintain a predetermined form, A weather-resistant long-fiber nonwoven fabric, characterized in that the sheath component made of polyolefin contains a weathering agent satisfying the following (a) to (c). (A) A granular material obtained by crystallizing cerium oxide on silica or talc. (B) The surface is coated with amorphous silica. (C) The average particle size is 0.05 to 3 μm. 2. The weathering agent content ratio in the sheath component is 0.05-1.
The weather-resistant long-fiber nonwoven fabric according to claim 1, which is 0% by weight.