JPH08246309A - Nonwoven fabric having high weather-resistance and house wrap and agricultural material made thereof - Google Patents

Abstract

PURPOSE: To provide a nonwoven fabric resistant to the lowering of waterproofing performance even after the outdoor exposure to sunlight and rainwater. CONSTITUTION: This nonwoven fabric having high weather-resistance is a nonwoven polyolefin fabric having an ultraviolet reflectivity of 65-80%, a Gurley air-permeability of 15-1,000sec/100cc and a bending rigidity of >=0.1gf/cm<2> /cm. The invention also relates to a house wrap and an agricultural material made of the nonwoven fabric. The lowering of waterproofing performance is remarkably small compared with conventional nonwoven fabric and the fabric has waterproofness and strength favorably comparable to those of conventional nonwoven fabric. Especially, a nonwoven fabric having specified bending rigidity and areal density can be applied with little squeaking noise and has noise- generation preventing effect and excellent effect for preventing the leakage of water through a nail hole.

Description

Detailed Description of the Invention

[0001] The present invention relates to a non-woven fabric used for outdoor applications, and more specifically to a non-woven fabric used for agricultural materials and construction materials having excellent strength, waterproofness and moisture permeability. . More specifically, the present invention relates to a non-woven fabric whose waterproofness is less likely to decrease even when exposed to sunlight or rainwater outdoors.

[0002]

2. Description of the Related Art Nonwoven fabrics made by flash spinning are conventionally known as nonwoven fabrics having excellent strength and a highly balanced waterproofness and moisture permeability. Taking advantage of the above characteristics, this non-woven fabric is used for outdoor applications, specifically, house wraps, agricultural multi-sheets, outdoor posters, outdoor labels and the like.

More specifically, the term "house wrap" means that rainwater and the like are prevented from entering the inner wall of the wall, ceiling, floor, etc. of a building such as a house, and the indoor moisture is discharged to the outside. This sheet is used for the purpose of preventing dew condensation on the inner wall, and this type of sheet is constructed in the state shown in FIG. 1, for example. In recent years, non-woven fabrics have also been used as multi-sheets for fruits such as mandarin oranges, and it is known that the moisture content of fruits can be adjusted by blocking rainwater thereby to increase the sugar content of fruits.

A typical sheet used for these purposes is a non-woven fabric produced by a flash spinning method (hereinafter abbreviated as a flash non-woven fabric). As the flash non-woven fabric, for example, Japanese Patent Publication No. 42-19520 discloses a three-dimensional reticulated fiber having high strength and high abrasion resistance, and its manufacturing method is disclosed in, for example, Japanese Patent Publication No. 43-21112. There is.

The flash non-woven fabric thus obtained has an appropriate pore size and has a property of blocking water and allowing the passage of air and water vapor. A specific example of such a non-woven fabric is Tyvek (trade name, EI Du Po) which is a non-woven fabric obtained by thermocompression bonding three-dimensional mesh fibers of high density polyethylene.
nt) and Luxer (trade name, manufactured by Asahi Kasei Kogyo Co., Ltd.) are known.

However, the flash non-woven fabric generally used in the past is likely to deteriorate in strength and waterproofness when exposed to the outside like other non-woven fabrics. It has been clarified that the deterioration of waterproofness is remarkable. On the other hand, in the above-mentioned application, for example, house wrap, it faces the outside until the outer wall is formed, and is exposed outdoors for about one month. Further, even when it is used as an agricultural mulch sheet, it is exposed to the outdoors for about 1 to 3 months, so that the above-mentioned deterioration in waterproofness of the flash nonwoven fabric becomes a serious problem.

As a method for improving such a problem,
A method of adding an ultraviolet absorber, a light stabilizer, or the like to the polymer constituting the flash non-woven fabric is generally used. For example, Japanese Unexamined Patent Publication (Kokai) No. 5-125611 discloses a stock solution for flash spinning, a method for producing a fiber using the same, and a nonwoven fabric. A UV absorbent such as a hindered amine type is added to a polyethylene polymer to improve weather resistance. It is said that excellent flash-spun nonwoven fabrics can be produced. However, this method slightly improves the retention rate of tensile strength after exposure, but hardly reduces the reduction in retention rate of waterproofness, and cannot be said to suggest a means for improving waterproofness.

As is clear from the above, a non-woven sheet having excellent weather resistance, which can sufficiently prevent deterioration of waterproof property over time, has not been proposed yet.

[0009]

That is, an object of the present invention is to provide a non-woven fabric which is excellent in weather resistance even when it is exposed to the outdoors for a long period of time, and particularly in which the waterproof property is extremely reduced, and its use.

[0010]

DISCLOSURE OF THE INVENTION The present inventors have focused on the fact that fibers made by flash spinning in a non-woven fabric have a complicated atypical cross section and are superior in weather resistance, and utilize a special form of this fiber. However, as a result of repeated intensive research to make a nonwoven fabric having a tissue structure capable of achieving the above-mentioned object of the present invention, it was found that a nonwoven fabric with extremely little deterioration in waterproofness can be obtained even by outdoor exposure, and the present invention is completed. I arrived.

That is, the present invention is a polyolefin-based nonwoven fabric having an ultraviolet reflectance of 65 to 80.
%, Gurley air permeability is 15 to 1000 seconds / 100 cc,
A highly weather resistant non-woven fabric, characterized by being structured so that the flexural rigidity value is 0.1 gf / cm ² / cm or more, which is significantly superior to conventional flash non-woven fabrics in weather resistance. Is.

The present invention is also a house wrap made of the above-mentioned nonwoven fabric. Furthermore, the present invention is an agricultural material comprising the non-woven fabric. The present invention will be described in more detail below. In the present invention, a non-woven fabric made of a three-dimensional mesh fiber obtained by the flash spinning method is particularly preferably used. In the present invention, the structure of this nonwoven fabric fiber assembly is restructured so as to achieve the object of the present invention to obtain a nonwoven fabric having a specific fibrous structure.

That is, in the nonwoven fabric according to the present invention, at least a part of the fibers constituting the flash-spun nonwoven fabric are thermally bonded to each other to form an appropriate void structure between the fibers. By doing so, desired mechanical properties can be imparted to the nonwoven fabric. Further, in the present invention, the fiber assembly forming the surface layer portion of the flash-spun nonwoven fabric has a structure composed of a denser fiber assembly so as to inhibit the absorption of ultraviolet rays. In addition, the fibers forming the surface layer portion hold the atypical cross section to a considerable extent.

According to the present inventors, such a texture structure of the non-woven fabric of the present invention has a specific region formed by a limited region of the ultraviolet reflectance, Gurley air permeability and flexural rigidity of the non-woven fabric. Can be represented by. less than,
The above-mentioned configuration of the present invention will be continuously described. The nonwoven fabric of the present invention needs to have an ultraviolet reflectance of 65 to 80%.
It is more preferably 70 to 80%. When the reflectance is less than 65%, a nonwoven fabric having a tissue structure that more easily absorbs ultraviolet rays is formed, and when exposed outdoors, deterioration is likely to proceed. When the ultraviolet reflectance exceeds 80%, the fibers constituting the non-woven fabric are not sufficiently adhered to each other, and the strength and waterproofness are insufficient.

The Gurley air permeability of the non-woven fabric according to the present invention is 15 to 1000 seconds / 100 cc, preferably 25.
It should be ~ 200 sec / 100 cc. If this air permeability is less than 15 seconds / 100 cc, the pore size of the resulting nonwoven fabric forming the void structure is too large, and the use of such a nonwoven fabric causes a large deterioration in waterproofness even if the deterioration due to outdoor exposure is small. turn into. The air permeability is 1000
When it exceeds sec / 100 cc, in particular, the fusion of the fibers of the surface layer of the nonwoven fabric is excessively promoted, and not only the tissue structure having insufficient moisture permeability and tear strength but also the nonwoven fabric structure lacking flexibility is obtained. Not in.

Further, the bending rigidity value of the nonwoven fabric according to the present invention is
It should be 0.1 gf / cm ² / cm or more. This is because if it is less than 0.1 gf / cm ² / cm, the structure of the structure is such that the degree of thermal bonding between the fibers is insufficient, the tensile strength is low, and the nonwoven fabric is easily broken even when used outdoors. According to the present invention, forming a non-woven fabric structure having a high flexural rigidity value is strongly related to forming a non-woven fabric structure that reduces the reflectance of ultraviolet light, and the ultraviolet light reflectance is substantially 65%.
The flexural rigidity value indicated by the structural structure of% corresponds to the upper limit of the flexural rigidity value of the nonwoven fabric according to the present invention.

In particular, the bending rigidity value is 0.1 to 0.4 gf /
A non-woven fabric of cm ² / cm is particularly preferable in the present invention because it has a low noise of paper creaking when it is fanned by wind and can suppress noise during the construction of house wraps and mulching materials. The basis weight of the nonwoven fabric used in the present invention is
Preferably 20 to 300 g / m ² , more preferably 3
It is 0 to 200 g / m ² . If the basis weight is less than 20 g / m ² , a nonwoven fabric having sufficient waterproofness cannot be obtained.
In addition, if the basis weight is too large, the flexibility of the resulting nonwoven fabric is impaired, and wrinkles or breakage are likely to occur during the production of the nonwoven fabric, which is not preferable in terms of quality.

Particularly, a non-woven fabric having a basis weight of 50 g / m ² or more and satisfying the above-mentioned constitution of the present invention is particularly preferable because a non-woven fabric excellent in waterproofness of nails and tackers can be obtained. Further, the non-woven fabric of the present invention, the non-woven fabric of the present invention having the above-mentioned structure in order to improve the adhesiveness at the time of printing, a non-woven fabric which has been subjected to corona treatment, electron beam treatment, etc. on one side or both sides, and also for improving weather resistance. A non-woven fabric obtained by adding a treatment agent such as an ultraviolet absorber, a light stabilizer, an antistatic agent, or a water repellent to a polymer constituting a fiber and spinning the same, or a non-woven fabric obtained by adding these after forming the non-woven fabric. It doesn't matter.

Furthermore, the non-woven fabric of the present invention is laminated with a reinforcing material for improving the strength of the non-woven fabric, water-stopping treatment for preventing water leakage from a tucker needle, and anti-slip treatment for facilitating walking on the non-woven fabric by a person. For example, a non-woven fabric processed by a known technique may be used. Next, a method for manufacturing the nonwoven fabric used in the present invention will be described. The non-woven fabric used in the present invention is preferably a non-woven fabric composed of a flash-spinning method three-dimensional mesh-like fibers described below, but using at least a part of the short fibers or synthetic pulp produced by the flash-spinning method, a paper-making method or a card method. A nonwoven fabric obtained by heat-bonding after forming the web can be used, and the manufacturing method thereof is not particularly limited.

The above-mentioned nonwoven fabric used in the present invention may be manufactured by a known method. For example, Japanese Examined Patent Publication No. 62-172073 discloses an example of high-density polyethylene flash spinning, and Japanese Examined Patent Publication No. 62-1.
Japanese Patent No. 92598 discloses a flash spinning example of polypropylene. Incidentally, when explaining a specific example of flash spinning, a polyolefin-based polymer is a halogenated carbon such as trichlorofluoromethane or trichlorotrifluoroethane, or a hydrocarbon such as methylene chloride,
Furthermore, after dissolving in these mixed liquids under high temperature and high pressure,
When a sudden pressure loss is applied to the resulting solution, the polymer dissolved in the solution changes into a solution structure as if it was phase-separated into extremely fine particles, and this liquid material is discharged from the spinning nozzle to align the polymer. Three-dimensional reticulated fibers can be formed by feeding and spinning.

A non-woven fabric which can be used in the present invention can be obtained by depositing such discharged fibers on a plate-like or net-like support and forming a web. Conventional flash-spun nonwoven fabric products are produced by web-forming and then heat-bonding them with, for example, an embossing roll or felt calender, and under these heat-bonding conditions, polyolefin nonwoven fabrics having various nonwoven fabric characteristics are obtained.

However, it is difficult to obtain the non-woven fabric that can achieve the above-mentioned object of the present invention by such a simple joining method using a normal calender roll or felt calender. For example, when bonded with a calender roll, the flexural rigidity value becomes 0.1 gf / cm ² / cm or less, that is, the strength of the nonwoven fabric tends to be insufficient, and in order to improve the strength, the calender roll temperature is increased to form the nonwoven fabric. In particular, the fibers of the surface layer part are partially fusion-bonded to each other to form a film, and the nonwoven fabric is corrugated, or the ultraviolet reflectance is lowered, so that the nonwoven fabric capable of achieving the object of the present invention cannot be obtained. Further, when the web-shaped non-woven fabric is heat-bonded by a felt calender, the contact time with the heat roll is inevitably lengthened, so that the complicated atypical cross-section of the fibers forming the non-woven fabric becomes close to a round cross-section due to heat shrinkage. Transformed,
The ultraviolet ray reflectance is lowered, or the pore size of the voids in the surface layer of the non-woven fabric is too large, so that the Gurley air permeability in the present invention is less than 15 seconds / 100 cc. Cannot be

Therefore, as a result of repeated studies on the conventional method for improving the thermal bonding method, the present inventors were able to obtain a nonwoven fabric having the specific fibrous structure. That is, the improved thermal bonding method of the web-shaped nonwoven fabric in the present invention is performed by thermocompressing the web-shaped nonwoven fabric with a calender roll or an embossing roll at a softening point of the polymer or higher to temporarily bond the web-shaped nonwoven fabric with a porosity of 50 to 8
After increasing the fiber density to 0%, a felt calender is used to perform thermal bonding at a temperature of 5 ° C. higher than the melting point of the polymer at a contact time of 0.5 seconds or more to obtain a nonwoven fabric having the specific fibrous structure. Is the way to do it.

More specifically, for example, in the case of a polyethylene web having a basis weight of 50 to 80 g / m ² obtained by the flash spinning method, it was heated at least once to a rubber roll having a rubber hardness of 75 ° or more and 80 ° C. or more. A temporary bonded non-woven fabric having a porosity of 60 to 85% is obtained by press-bonding with a smooth metal roll at a linear pressure of 100 kg / cm. This temporary bonded non-woven fabric is heated with a felt calender at a heating temperature of 1
The UV reflectance is 65 to 80% by secondarily bonding the front and back sides at a temperature of 32 to 140 ° C. and a contact time of 0.5 to 5 seconds.
Air permeability of 15 seconds / 100 cc or more and bending rigidity value of 0.
A non-woven fabric having a tissue structure of 1 gf / cm ² / cm or more can be obtained.

[0025]

The present invention will be described in more detail with reference to the following examples. Prior to the description of the examples, methods for measuring various physical properties of the house wrap of the present invention and the nonwoven fabric used will be described. (1) Bending rigidity value Pure bending tester (manufactured by Katotec Co., Ltd.,
Using a pure bending tester, the bending strengths of the non-woven fabric in the machine direction and the transverse direction are measured 5 times each to obtain an average value, which is represented by the average value (g / cm ² / cm) of both. (2) Porosity (%) Porosity = {1-weight (g / m ² ) ÷ [thickness (m) × specific gravity]} × 100 (3) weight Three 250 mm × 250 mm samples were obtained from the obtained nonwoven fabric. It is a value in which the sample is taken, brought into a water equilibrium state (20 ° C., 65% RH) and then weighed, and the average value thereof is expressed per unit area (g / m ² ). (4) Thickness Using a Peacock direct reading type digital linear gauge PD-2 type (manufactured by Ozaki Seisakusho), an XS-4 adapter (contact surface 8)
φ, weight 120 g) 5 under pressure of 2.4 g / cm ^2.
The thickness is measured once, and is represented by the average value (m). (5) Air permeability It is the air permeability measured by the Gurley air permeability measuring machine defined in JIS-P-8117, which measures the time for which 100 cc of air passes, and the unit of measurement is seconds. The larger this value, the harder it is for air to pass through, and the smaller the pore size. (6) UV reflectance (%) Spectrophotometer (manufactured by Shimadzu Corporation, Shimadzu self-recording spectrophotometer UV-
2200, using integrating sphere unit) wavelength 360n
The ultraviolet reflectance of m is measured. The number of n is 3, and is represented by the average value. (7) Water pressure resistance The static pressure of the method A and method B of the waterproof test method (JIS-L-1092) for textiles was measured at 3 points, and the average value is shown. In the water resistance test, the water pressure resistance of the nonwoven fabric (mmH
₂ O) is a house present goods used in the wrap applications (Asahi Chemical Industry Co., Ltd., it is sufficient to hold about 70% that is 1000mmH ₂ 0 or more Luxer H2040ZZ). (8) Tensile Strength According to JIS-L-1096 Tensile Strength and Elongation Test Method, a sample with a width of 3 cm and a length of 20 cm was gripped with a constant-speed extension type Tensilon tensile tester at a gripping interval of 10 cm and a pulling speed of 20 cm / Measure under the condition of min. Measured vertically and horizontally with n number of 5, respectively, and obtained the average value, and the average value of both (kg
f / 3 cm).

A tensile strength of 5 kgf / 3 cm or more is passed. (9) based on the moisture permeability JIS-L-1099 breathable Test Method A-1 method (calcium chloride method), measured at n number 3, represented by the average value ^{(g / m 2 / 24hr)} . In the moisture permeability test, the moisture permeability of the non-woven fabric is the current product (Luxer H2040Z
And about 70% that is 4000g / m ² / 24hr or more Z) only needs to hold. (10) Weather resistance evaluation A sample was attached to a PP plate for 2 months from 94/7/21 to 94/9/20 on the roof of a three-story building owned by Asahi Kasei Kogyo Co., Ltd. in Takatsuki City, Osaka Prefecture, and grounded on the ground. It was installed horizontally and exposed outdoors.

The amount of energy of ultraviolet rays (300 to 400 nm) was measured with an integrating photometer manufactured by Suga Test Instruments Co., Ltd. at 45 ° to the south, and the value was about 55 MJ / m ² . The water resistance and tensile strength of the sample were measured under the above-mentioned conditions, and expressed as the retention rate (%) after outdoor exposure. If the retention rate of strength and water pressure resistance is 50% or more, there is practically no problem,
Judged as acceptable (11) Water resistance of nail holes Place the sample on plywood with a thickness of 12 mm and hit a nail (straight nail). On top of this, stand a PVC pipe whose bottom is sealed with a sealing agent. 150m to this
Water is poured up to the height of m, the water reduction amount (ml) is calculated from the water reduction height (mm) after 24 hours, measured with n number 10, and the pass rate of 1.0 ml or less as a pass ( %). If the pass rate exceeds 70%, there is virtually no problem and it is judged as pass. (12) Paper squeal property A non-woven fabric is sampled in a size of 50 cm × 50 cm, only the upper part is fixed, and the sample is blown with an air blower so that the wind speed is 4 to 6 m. A decibel value (phone) at 1000 Hz is measured 10 times with an ordinary sound level meter (NA-28 manufactured by Rion Co., Ltd.) at a distance of about 1 m from the sample, and the average value is examined.

The following results are obtained from the evaluation test by the number of phones and sensory inspectors. 75 phones or less ... 2 or less out of 10 people feel noisy 75-80 phones ... 3 to 6 out of 10 people feel noisy 80 phones or more ... 7 out of 10 people feel noisy Therefore, as for the evaluation of the paper ringing property, 75 phone or less is judged to be acceptable, and 75 phone or more is judged to be unacceptable. Next, a production example of the nonwoven fabric of the present invention will be described.

(Nonwoven fabric A) Polyethylene polymer and solvent are discharged from a nozzle to a low temperature and low pressure region under high temperature and high pressure conditions,
The solvent was flashed to form fibrillated reticulated fibers, which were then deposited in a wire mesh to form a 1 m wide web. This web is embossed at 155 ° C (concave is a lattice pattern,
Embossing depth 0.04mm, convex area 25%) and rubber hardness 90 ° smooth silicon roll with linear pressure 180kg
/ Cm, speed 70 m / min, both sides of the surface were partially heat-pressed, and temporarily joined with a porosity of 68%. Then, using a felt calender, the sides of the both sides were thermally joined at a contact time of 1 second and a heating temperature of 130 ° C. , Basis weight 72g / m ² thickness 0.19mm
A polyethylene nonwoven fabric of (Non-woven fabric B) A polyethylene web obtained in the same manner as Non-woven fabric A was treated with a flat metal roll at 160 ° C. and a rubber hardness of 7
Linear pressure of 200 kg / c with a 5 ° smooth silicone roll
m and the speed was 70 m / min, and one side was partially heat-pressed and temporarily joined so that the porosity was 74%, and then the contact time was 1.4 seconds and the heating temperature was 137 using a felt calender.
Thermal bonding of both front and back at ℃, basis weight 70g / m ² Thickness 0.1
A 9 mm polyethylene nonwoven fabric was obtained. (Non-woven fabric C) A web was formed in the same manner as the non-woven fabric A except that the discharge amount was changed, and an embossing roll of 145 ° C. (concave portion was lattice pattern, embossing depth 0.04 mm, convex portion area 25) was formed.
%) And a smooth silicon roll with a rubber hardness of 90 °, the front and back surfaces were partially heat-pressed at a linear pressure of 150 kg / cm and a speed of 85 m / min, and temporarily bonded with a porosity of 69%, and then using a felt calender, the contact time Is 1.2 seconds, the heating temperature is 130 ° C., and the front and back sides are heat-bonded together to give a basis weight of 62 g / m ^2.
A polyethylene nonwoven fabric having a thickness of 0.17 mm was obtained. (Non-woven fabric D) A web of non-woven fabric A is embossed at 135 ° C. (concave portion is lattice pattern, embossing depth is 0.2 mm, area of convex portion is 0.16 mm ² , convex portion area ratio is 40%) and rubber hardness is 75 °. Linear pressure of 300 due to the smooth silicon roll
Both the front and back sides were partially heat-pressed at a speed of 30 m / min at a speed of 30 kg / cm, and temporarily bonded with a porosity of 72%, using a felt calender for a contact time of 0.7 seconds and a heating temperature of 135 ° C.
One surface (front surface) was heat-bonded to obtain a polyethylene nonwoven fabric having a basis weight of 72 g / m ² . (Non-woven fabric E) A web was formed in the same manner as the non-woven fabric A except that the discharge amount was changed, and an embossing roll of 145 ° C. (concave portion was lattice pattern, embossing depth 0.04 mm, convex portion area 25
%) And rubber hardness 99 ° with a smooth silicon roll at a linear pressure of 220 kg / cm and a speed of 105 m / min to heat and pressure-bond both sides, and temporarily bond with a porosity of 65%. Is 1.2 seconds, the heating temperature is 130 ° C., and the front and back surfaces are heat-bonded together, and the basis weight is 92 g / m 2.
² A polyethylene non-woven fabric having a thickness of 0.26 mm was obtained.

Next, a production example of a non-woven fabric as a comparative example will be shown. (Nonwoven fabric a) A polyethylene polymer and a solvent were discharged from a nozzle to a low temperature and low pressure region under high temperature and high pressure conditions, and the solvent was flushed to form fibrillated reticulated fibers, which were then deposited in a wire mesh form to form a 1 m wide web. .

This web was embossed at 25 ° C. (concave portions were lattice pattern, embossing depth was 0.04 mm, convex portion area was 25).
%) And a rubber hardness of 75 ° on a smooth silicon roll to partially press-bond both front and back sides at a linear pressure of 180 kg / cm and a speed of 70 m / min to obtain a polyethylene nonwoven fabric having a basis weight of 68 g / m ^{2 and a} thickness of 0.20 mm. (Non-woven fabric b) A polyethylene web obtained in the same manner as Non-woven fabric a was subjected to a flat metal roll at 160 ° C. and a rubber hardness of 9
Linear pressure of 200kg / c with a 9 ° smooth silicon roll
m and speed 70m / min, one side was partially heat-bonded and temporarily joined so as to have a porosity of 66%. Then, using a felt calender, the contact time was 3 seconds and the heating temperature was 137 ° C. And basis weight 70g / m ² thickness 0.16m
m polyethylene nonwoven fabric was obtained. (Non-woven fabric c) A web was formed in the same manner as the non-woven fabric a except that the discharge amount was changed, and the embossing roll at 135 ° C. (concave portion was lattice pattern, embossing depth 0.2 mm, one area of convex portion was 0.16 mm ² , Convex area ratio 40%) and rubber hardness 75 °
Linear pressure of 200kg / cm
Both front and back surfaces were subjected to thermal partial pressure bonding at a speed of 50 m / min to obtain a polyethylene nonwoven fabric having a basis weight of 42 g / m ² . (Non-woven fabric d) The web of the non-woven fabric A was partially pressure-bonded on both sides by a linear pressure of 50 kg / cm and a speed of 40 m / min using a smooth metal roll at 30 ° C. and a smooth silicon roll having a rubber hardness of 75 °, and the porosity was 82%. After temporary joining with, contact time 1.5 seconds using a felt calender, heating temperature 1
One surface (front surface) was thermally bonded at 45 ° C. to obtain a polyethylene nonwoven fabric having a basis weight of 71 g / m ² . (Non-woven fabric e) After forming a web in the same manner as Non-woven fabric A using a polyethylene polymer similar to Non-woven fabric A except that the hindered amine UV absorber Tinuvin 622LD (manufactured by Ciba-Geigy Co.) is contained at 2000 ppm, the temperature is 30 ° C.
Line pressure 50kg / cm, speed 40m / min by the smooth metal roll and the smooth silicon roll with rubber hardness of 75 °
After partially heat-bonding the front and back sides with each other and temporarily bonding with a porosity of 82%, contact time is 1.0 using a felt calender.
For one second, the heating temperature was 145 ° C. and one side (surface) was thermally bonded to obtain a polyethylene nonwoven fabric having a basis weight of 73 g / m ² .

[0032]

[Examples 1 to 5 and Comparative Examples 1 to 5] The nonwoven fabrics A to E and the nonwoven fabrics a to e were evaluated in the above (1) to (10).
The results are shown in Table 1. From Table 1, it can be seen that the nonwoven fabric of the present invention is a nonwoven fabric that is resistant to water pressure resistance, that is, deterioration in waterproofness, has a high tensile strength value, and is not easily broken.

On the other hand, as shown in Comparative Examples 1 and 3, it can be seen that nonwoven fabrics having a bending rigidity value of less than 0.1 g / cm ² / cm have low tensile strength and are not suitable for outdoor use. Further, from Comparative Examples 2 and 5, it is found that the nonwoven fabric having an ultraviolet reflectance of less than 65% has a large deterioration in water pressure resistance, and the waterproof retention rate is significantly less than 50% after exposure for 2 months outdoors. It can be seen that the addition of the ultraviolet absorber does not significantly improve the waterproof deterioration preventing property.

Further, from Comparative Example 4, it can be seen that even with a nonwoven fabric having an air permeability of less than 15 seconds, the waterproof property is likely to be deteriorated by outdoor exposure.

[0035]

[Example 6 and Comparative Example 6] The nonwoven fabric D and the nonwoven fabric e were examined for waterproofness against nail holes and paper noise. The results are shown in Table 2. From the results shown in Table 2, it is understood that the nonwoven fabric of the present invention is not only excellent in weather resistance, but also has an effect of suppressing noise generation during construction, and is also excellent in preventing water leakage from nail holes.

[0036]

INDUSTRIAL APPLICABILITY The non-woven fabric of the present invention, which is structured so as to have the specific ultraviolet reflectance, Gurley air permeability and flexural rigidity, has excellent weather resistance, and in particular, the decrease in waterproofness is remarkable as compared with the conventional non-woven fabric. It is small and has performance comparable to that of currently used non-woven fabrics in terms of waterproofness and strength.

Further, among them, a non-woven fabric having a specific flexural rigidity value and a specific weight is substantially free from paper noise during construction, has a noise preventing effect, and is also excellent in preventing leakage of water from nail holes.

[0038]

[Table 1]

[0039]

[Table 2]

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a construction example of a house wrap material.

[Brief description of reference numerals]

 1 ... House wrap material 2 ... Studs 3 ... Heat insulating material 4 ... Moisture-proof sheet 5 ... Vertical furring strip 6 ... Outer wall material 7 ... Interior material 8 ... Steam

Claims (3)

[Claims] 1. A polyolefin-based nonwoven fabric, which has an ultraviolet reflectance of 65 to 80%, a Gurley air permeability of 15 to 1000 seconds / 100 cc, and a bending rigidity value of 0.1 g.
A highly weather-resistant non-woven fabric, characterized by being structured so as to be f / cm ² / cm or more. 2. A house wrap made of the non-woven fabric according to claim 1. 3. Agricultural material comprising the non-woven fabric according to claim 1.