JP2011025179A - Protective mat - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective mat which can reduce drawing force due to deposited snow or the like and prevent a slipping-over. <P>SOLUTION: The protective mat is laid down on the upper surface side of an impermeable sheet installed at the installation site such as a waste repository, and is configured to include a base layer and a slipperiness-giving layer formed on the base layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a protective mat used for the purpose of protecting a water shielding sheet installed in a waste disposal site or the like.

  In the waste disposal site, a water-impervious sheet that is impermeable to water is used for the purpose of preventing contamination of groundwater. As the material of the water shielding sheet, synthetic rubber materials such as ethylene / propylene diene monomer, synthetic resin materials such as polyvinyl chloride and polyethylene, asphalt materials, bentonite materials and the like are used.

  In order to protect the water shielding sheet from damage due to ultraviolet rays or protrusions, the front and back surfaces of the water shielding sheet or one of the surfaces is covered with a protective mat. In other words, this protective mat is installed between the water-impervious sheet and the ground to protect the water-impervious sheet from projections on the ground, or by covering this protective mat on the upper side of the water-impervious sheet, it can be protected from ultraviolet rays contained in sunlight. Protecting the water shielding sheet is performed.

In general, a long fiber nonwoven fabric or a short fiber nonwoven fabric is used for the protective mat. Most of the materials constituting the nonwoven fabric are polyester and polypropylene.
When such a protective mat is installed in a waste disposal site, a protective effect may not be exhibited because a gap is formed. In order to prevent such a decrease in the protective effect, it is necessary to combine a plurality of protective mats by bonding them together by a method such as heat fusion (thermal welding), bonding with an adhesive, or sewing. is there.

  As a method for connecting the protective mats, it is known that the ends of adjacent protective mats are overlapped with each other and the overlapped portions are combined with a hook-and-loop fastener (see Patent Document 1). However, it is not preferable to use a hook-and-loop fastener because it cannot be used unless the hook-and-loop fastener is bonded to each other by bonding the hook-and-loop fastener to the protective sheet.

  Also, as a method for bonding the protective mats, a method of bonding by heat fusion using a thermal iron or a hot air generator is known. However, since conventional protective mats are often composed of a single component, problems such as over-melting during heat-sealing and opening of holes, or insufficient melting and peeling off may occur. was there.

  From such a background, a protective mat having good heat sealability (thermal adhesiveness) has been eagerly desired, and the present applicant has proposed a protective mat using a core-sheath composite fiber as a fiber constituting the protective mat ( Patent Document 2). Since the sheath component in the core-sheath composite fiber is a component having a low melting point, it has a special effect on heat fusion.

JP 2000-144686 A JP 2008-221052 A

  In the method of Patent Document 2 described above, the purpose was achieved in terms of thermal adhesiveness, but the upper surface side of the water shielding sheet was covered by the weight of snow in the cold region, its own weight, and the pulling force during landfilling of waste. It has been found that there is a problem that the protective mat is slipped off or necking occurs, and the surface of the water-impervious sheet is exposed, and the function of protecting the water-impervious sheet cannot be performed satisfactorily. Therefore, the present inventor has studied to make further improvements. The present invention prevents a protective mat placed on the upper surface side of a water shielding sheet installed in a waste disposal site or the like from sliding down due to a pulling force caused by snow accumulation or the like.

  As a result of intensive studies to solve the above problems, the present inventors have found that the surface smoothness can be greatly improved by forming a slipperiness-imparting layer on the protective mat. Reached.

That is, the gist of the present invention is as follows.
(1) A protective mat laid on the upper surface side of a water shielding sheet installed at a target location such as a waste disposal site, wherein the protective mat is formed on the base layer and the slipperiness imparted A protective mat characterized by comprising layers.
(2) The protective mat according to (1), wherein the slipperiness-imparting layer is formed by extruding and laminating a polymer on the base layer.
(3) The protective mat according to (1) or (2), wherein the mass per unit area of the slipperiness-imparting layer is 50 to 400 g / m ² .
(4) The protective mat according to (1) to (3), wherein the penetration resistance is 700 N or more.

  According to the present invention, since the slipperiness-imparting layer is formed by extruding and laminating a polymer on the surface of the protective sheet, the smoothness of the surface can be improved, and in addition, the slipperiness can be improved. Therefore, it is possible to prevent the protective mat from sliding off or causing necking due to the pulling force caused by snow accumulation or the like, and the surface of the water shielding sheet can be well protected.

It is a figure which shows the outline of the water-proof sheet | seat by which the protection mat of this invention was laid. It is a schematic sectional drawing which shows an example of the protection mat of this invention. It is a schematic sectional drawing which shows another example of the protection mat of this invention, and the laminated body is used for the base layer.

Hereinafter, the present invention will be described in detail.
The protective mat of the present invention is laid on the upper surface side of a water shielding sheet used in a treatment pond or the like of a waste disposal site. The water shielding sheet is used for the purpose of preventing the liquid inside the treatment pond from contaminating the groundwater. By laying a protective mat on the water-impervious sheet, even if there are items with sharp projections in the waste, they are prevented from coming into direct contact with the water-impervious sheet, thereby preventing damage to the water-impervious sheet can do. Further, the water shielding sheet can be protected from the occurrence of damage based on the irradiation with ultraviolet rays contained in sunlight.

  FIG. 1 shows an example of a sectional structure of a treatment pond in a waste treatment plant. Here, 1 is earth and sand, for example, the processing pond 2 is formed by digging up this earth and sand from the ground surface. A water-impervious sheet 3 is installed at the bottom or slope of the treatment pond 2. By installing the water shielding sheet 3, it is possible to prevent the liquid inside the treatment pond 2 from entering the earth and sand 1 and contaminating the groundwater. A conventionally used protective mat 5 is laid between the back surface of the water-impervious sheet 3, that is, between the water-impervious sheet 3 and the earth and sand 1 to prevent and protect the water-impervious sheet 3 from coming into direct contact with the ground surface. ing. In the present invention, the protective mat 4 having the slipperiness-imparting layer of the present invention is laid on the upper surface side of the water-impervious sheet 3. By adopting such a structure, the waste and snow on the protective mat 4 having the slipperiness-imparting layer can be actively slid down from the surface of the protective mat 4, and pulling in due to the snow and waste is not caused. The surface of the water shielding sheet can be well protected without being generated.

  The water shielding sheet is formed of a synthetic rubber material such as ethylene / propylene diene monomer, a synthetic resin material such as polyvinyl chloride or polyethylene, an asphalt material, or a bentonite material.

  The protective mat of the present invention has a structure in which a slipperiness-imparting layer is formed on one side of the base layer. When the protective mat of the present invention is laid on the water-impervious sheet, it is laid on the water-impervious sheet so that the water-impervious sheet and the base layer are adjacent to each other.

First, the base layer will be described in detail.
The base layer is not particularly limited as long as it is used as a base material in a protective mat for a water shielding sheet. In addition, the base layer may have a single layer structure or a laminated structure. Moreover, as a base layer, what is comprised with the fiber (single-phase fiber) which consists of a single polymer, the thing containing the fiber which has heat adhesiveness, etc. are mentioned. In the present invention, as the base layer, a layer composed of a core-sheath composite fiber composed of a core having a high melting point component and a sheath having a low melting point component [hereinafter sometimes referred to as (A) layer], (A) layer A layered product obtained by laminating a layer composed of fibers having a melting point higher than the low melting point component (hereinafter sometimes referred to as (B) layer) and the above layer (A) [hereinafter simply referred to as “layer”] Preferred examples include “sometimes referred to as a laminate”. By using a laminate, strength characteristics can be imparted to the protective mat.

  The fiber used for the layer (A) is a core-sheath composite fiber having a cross-sectional structure including a core component and a sheath component having a melting point lower than that of the core component. As the polymer constituting the core component and the sheath component, polymers generally used for fibers can be used and are not particularly limited. For example, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyolefins such as polyethylene and polypropylene, polyamides such as nylon 6 and nylon 66, and the like can be preferably used.

  As described above, the sheath component in the layer (A) has a lower melting point than the core component. This is because the sheath component functions reliably as a thermal adhesive component and the core component functions reliably as a fiber shape maintaining component. For this purpose, the difference between the melting points of the two is preferably 20 ° C. or more, and more preferably 50 ° C. or more. If the melting point difference is small, when the sheath component is melted by heat and heat bonding is performed, even the core component is melted, and the fiber form is lost, which may cause defects in the protective mat. is there.

  As a typical example of the combination of the core component and the sheath component in the layer (A), there can be mentioned those in which the core component is polyester, for example, polyethylene terephthalate, and the sheath component is polyethylene. In this case, the melting point difference between the core component and the sheath component can be set to, for example, 100 ° C. or more, and the core component polyethylene terephthalate has crystallinity, and has high strength among the polymers. Even if the sheath component as the thermal bonding component is sufficiently melted, the core component can be reliably maintained without melting the core component.

  The mixing ratio of the core component and the sheath component is preferably a volume ratio of core component: sheath component = 30: 70 to 70:30. By being in this range, it is possible to combine required thermal bonding performance and fiber shape maintenance performance.

  In addition to the core-sheath composite fiber, the layer (A) can contain a single-phase fiber or other cross-sectional fiber. The ratio of the fiber mixture can be set to such an extent that the function of thermal bonding by melting the sheath component of the core-sheath composite fiber is not hindered. For example, when a single-phase fiber is contained, the melting point of the polymer constituting the fiber needs to be higher than the melting point of the sheath component of the core-sheath composite fiber. This is to prevent the fibers from melting and losing the fiber form during thermal bonding.

  The fibers constituting the (B) layer are preferably made of a high strength polymer. Specific examples of the polymer used for the fibers constituting the layer (B) include polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, and the like. Among these, polyethylene terephthalate can be suitably used from the viewpoint of improving the strength.

  In addition, when laminating | stacking (A) layer and (B) layer to make a base layer, the fiber which comprises (B) layer is melting | fusing point higher than the low melting component used for the sheath component of (A) layer A polymer having The reason for this is to prevent the fibers of the B layer from melting and losing the fiber form during thermal bonding.

As a method for producing the core-sheath composite fiber and other fibers for forming the layers (A) and (B) constituting the protective mat, a known melt spinning method may be applied.
As a method of forming and laminating the (A) layer and the (B) layer using the core-sheath composite fiber and other fibers, a known method can be appropriately used, and is not particularly limited. A fiber web is obtained by the method, and a needle punch method is applied thereto. As an example, the fibers obtained by a known spinning method are made into a web-like shape and subjected to, for example, needle punching, so that the fibers are three-dimensionally entangled to form the (A) layer and the (B) layer. Can be stacked. If the fibers are temporarily fixed to each other by resin bonding or thermal bonding in order to maintain the web form before the needle punching process, the needle punching process can be performed satisfactorily.

  In addition, when laminating the (A) layer and the (B) layer by the needle punch method, it is appropriate that the length of the fiber exceeds 30 mm. If the thickness is 30 mm or less, layer formation by the needle punch method becomes difficult, which is not appropriate. Moreover, it is suitable that the fiber diameter of the fibers forming the (A) layer and the (B) layer is in the range of 10 to 100 μm. If it is out of the above range, it may be difficult to perform needle punching, and the performance of the protective mat may be hindered such as insufficient strength.

  When a laminate of the (A) layer and the (B) layer is used as the base layer, it is necessary in addition to the needle punch method described above when laminating the (A) layer and the (B) layer. For example, it is possible to further add resin bonding or heat bonding.

(A) It is preferable that the mass per unit of a layer is 100 g / m < ² > or more from a viewpoint of adhesive force. The mass per unit of the (B) layer is preferably 400 g / m ² or more from the viewpoint of protective performance (penetration resistance).

Next, the slipperiness imparting layer will be described in detail.
In the present invention, it is necessary to form a slipperiness-imparting layer made of a polymer on the surface of the base layer. The slipperiness-imparting layer improves the smoothness of the surface of the protective mat, making it possible to actively slide off snow and waste on the protective mat, and cover the upper surface of the water shielding sheet with the weight of snow and waste. It plays a role of preventing the formed protective mat from sliding down.

  The polymer is not particularly limited, and general-purpose polymers such as polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyolefins such as polyethylene and polypropylene, and polyamides such as nylon 6 and nylon 66 can be used. Among the above, it is preferable to select a polymer having good adhesion to the component forming the base layer.

  When the protective mats are bonded to each other, for example, the slipperiness-imparting layer of one protective mat and the base layer of the other protective mat are bonded by, for example, thermal bonding or the like. Accordingly, among the polymers used for the slipperiness-imparting layer, it is preferable to select a polymer having good adhesion to the (A) layer and the (B) layer.

As a method for forming the slipperiness-imparting layer on the base layer, a publicly known and commonly used method can be used, and it is not particularly limited, but an extrusion laminating method is optimal.
The mass per unit area of the slipperiness-imparting layer is preferably 50 to 400 g / m ² .

  Examples of the method for producing a protective mat according to the present invention include the following methods. That is, a core-sheath composite long fiber web is prepared as the (A) layer, a single-phase long fiber web is prepared as the (B) layer, and these (A) and (B) layers are overlapped to form a needle punch. The target protective mat can be obtained by processing and further laminating an appropriate polymer on the layer (A).

  The following method is mentioned as another manufacturing method of the protection mat which concerns on this invention. That is, a core-sheath composite short fiber web is created as the (A) layer, and a single-phase fiber web is created as the (B) layer. Next, (A) layer / (B) layer / (A) layer are laminated in the order of three layers, needle punched, and an appropriate polymer is extruded and laminated on one (A) layer. A protective mat can be obtained.

  The performance of general protection mats is described in the “Waste Final Disposal Site Technical System Handbook” published by Environmental Industry Newspaper. In order for the protective mat of the present invention to function well as the protective mat, it is preferable that the mass per unit area (weight per unit area), penetration resistance, and the like are designed so as to have this performance.

  In particular, the penetration resistance is a performance indispensable for protecting the water shielding sheet, and it is necessary to adjust the fiber amount of the protective mat to a target numerical value. In the present invention, the penetration resistance value is preferably 700 N or more.

Moreover, in this invention, it is preferable that the mass per unit area of a protection mat is 500-2500 g / m < ² >.
Furthermore, in the present invention, it is preferable that the tensile strength of the protective mat is 700 N / 5 cm or more in both the vertical direction and the horizontal direction.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited only to an Example.
[Evaluation methods]
Below, the measuring method used for evaluation of an Example and a comparative example is shown.
(1) Confirmation test of thermal bonding state A handy type hot air welding machine (manufactured by Leister) was used. The temperature of the outlet of the hot air welding machine is set to an appropriate temperature that is equal to or higher than the melting point of the portion of the fiber constituting the protective mat, the hot air is applied at a speed of 1 to 2 m / min, The distance from the heating unit was set to 10 to 20 cm, and the surface of the protective mat was adhered and adhered, and the situation at that time was visually observed.
(2) Penetration resistance It measured according to ASTM D4843. A push rod having a diameter of 8 mm, a chamfered tip of 0.8 mm and an oblique angle of 45 degrees was used.
(3) Tensile strength In accordance with JIS L 1908, the specimen was tested with a sample width of 5 cm, a grip interval of 100 mm, and a tensile speed of 20 mm / min.

Example 1
(A) A core-sheath composite long fiber web was prepared by a spunbond method using polyethylene terephthalate having a melting point of 255 ° C. as the core component and polyethylene having a melting point of 125 ° C. as the sheath component. In the core-sheath composite fiber constituting this web, the component ratio of the core part to the sheath part was 1: 1 by volume ratio, and the fiber diameter was 25 μm. Further, the adhesion between the fibers by the hot embossing roll was adjusted slightly so as to be suitable for the needle punching process in the next step, and the adhesion between the fibers was easily released by physical impact. The mass per unit area of the core-sheath composite long fiber web was 200 g / m ² .

Separately, a long fiber web made of polyethylene terephthalate having a melting point of 255 ° C. was prepared as a layer component (B) by a known spunbond method. The long-fiber web was slightly adjusted for adhesion between fibers by a hot embossing roll, and was in a state in which adhesion between fibers was easily released by physical impact. The mass per unit area of the long fiber web was 300 g / m ² .

Subsequently, said (A) layer and (B) layer were laminated | stacked, the needle punch process was performed, and the laminated body (base layer) whose mass per unit area is 520 g / m < ² > was obtained. As the needle punching conditions, a 40th needle manufactured by FOSTER was used, the punch density was 90 P / square inch, and the needle density was 10 mm.

The surface of the layer (B) of the laminate obtained above was coated with 200 g / m ² of polyethylene by extrusion lamination. The mass per unit area of the protective mat of the present invention obtained by coating was 720 g / m ² and was excellent in surface smoothness.

  Using two of the obtained protective mats, a heat adhesion state confirmation test was performed so that the first (A) layer and the second slipperiness-imparting layer were bonded. In a test using a hot air dryer at 150 to 250 ° C., it was possible to obtain a good adhesion state without problems such as adhesion failure and melt tear.

  Further, the tensile strength of the obtained protective mat was 1800 N / 5 cm in length, 1350 N / 5 cm in width, and the penetration resistance was 770 N.

(Example 2)
(A) A core-sheath composite long fiber web was prepared by a spunbond method using polyethylene terephthalate having a melting point of 255 ° C. as the core component and polyethylene having a melting point of 125 ° C. as the sheath component. In the core-sheath composite fiber constituting this web, the component ratio of the core part to the sheath part was 1: 1 by volume ratio, and the fiber diameter was 25 μm. Further, the adhesion between the fibers by the hot embossing roll was adjusted slightly so as to be suitable for the needle punching process in the next step, and the adhesion between the fibers was easily released by physical impact. The mass per unit area of the core-sheath composite long fiber web was 200 g / m ² .

Separately, as a layer component (B), a web made of polyethylene terephthalate having a melting point of 255 ° C., using a short fiber having a fiber length of 51 mm and a fiber diameter of 25 μm and a mass per unit area of 1200 g / m ² using a card machine. did.

Next, the (A) layer and the (B) layer are laminated, and needle punching is performed in the same manner as in Example 1 to obtain a laminated body (base layer) having a mass of 1430 g / m ² per unit area. did it.

The surface of the layer (B) of the laminate obtained above was coated with 200 g / m ² of polyethylene by extrusion lamination. The protective mat of the present invention obtained by coating had a mass per unit area of 1630 g / m ² and was excellent in surface smoothness.

  About the obtained protection mat, when the confirmation test of the heat bonding state was done like Example 1, in the test using a 150-250 degreeC hot-air dryer, there are no malfunctions, such as adhesion failure and a melt tear, and it is favorable. It was possible to obtain an adhesive state.

  Further, the tensile strength of the obtained protective mat was 1080 N / 5 cm in length and 2500 N / 5 cm in width. The penetration resistance was 1900N.

(Comparative Example 1)
A single layer of a long fiber web made of polyethylene terephthalate having a melting point of 255 ° C. was used, and a protective mat having a mass per unit area of 500 g / m ² was obtained through the same needle punching process as in Example 1. The surface was composed of fibers and was not at a level where the desired slipperiness of the present invention could be achieved.

  When the obtained protective mat was subjected to a test for confirming the thermal bonding state, it could not be bonded at 150 to 230 ° C., and when it was bonded at 270 ° C. or higher, it was difficult to handle, for example, holes were easily formed. .

  Further, the tensile strength of the obtained protective mat was 2330 N / 5 cm in length, 1370 N / 5 cm in width, and the penetration resistance was 1100 N.

(Comparative Example 2)
Using a polyethylene terephthalate having a melting point of 255 ° C. as the core component and polyethylene having a melting point of 125 ° C. as the sheath component, a core / sheath composite long fiber web was produced by a known spunbond method as a long fiber nonwoven fabric manufacturing method. In the core-sheath composite fiber constituting this web, the component ratio of the core part to the sheath part was 1: 1 by volume ratio, and the fiber diameter was 25 μm. Further, the adhesion between the fibers by the hot embossing roll was adjusted slightly so as to be suitable for the needle punching process in the next step, and the adhesion between the fibers was easily released by physical impact. Moreover, the mass per unit area of the core-sheath composite long fiber web was 500 g / m ² .

Next, through the same needle punching as in Example 1, a protective mat having a mass per unit area of 500 g / m ² was obtained. Since the surface is composed of fibers and has normal smoothness, it was not at a level where the slipperiness intended by the present invention could be achieved.

  About the obtained protection mat, when the confirmation test of the heat bonding state was done like Example 1, in the test using a 150-250 degreeC hot-air dryer, there are no malfunctions, such as adhesion failure and a fusion | melting tear, and it is favorable. It was possible to create an adhesive state.

Further, the tensile strength of the protective mat was 1400 N / 5 cm in length and 600 N / 5 cm in width, and the penetration resistance was 550 N.
Table 1 shows the evaluation results obtained in the examples and comparative examples.

DESCRIPTION OF SYMBOLS 1 Earth and sand 2 Treatment pond 3 Water shielding sheet 4 Protective mat 5 of the present invention Conventional protective mat 6 conventionally used Liquid 7 in the treatment pond 2 Sliding property imparting layer 8 (B) layer 9 (A) layer

Claims (4)

  A protective mat laid on the upper surface side of a water shielding sheet installed at a target location such as a waste disposal site, the protective mat comprising a base layer and a slipperiness-imparting layer formed on the base layer Protective mat characterized by being made.   The protective mat according to claim 1, wherein the slipperiness-imparting layer is formed by extruding and laminating a polymer on the base layer. Protection mat according to claim 1 or 2 weight per unit area of the sliding property layer is characterized by a 50 to 400 g / m ^2.   The penetration resistance is 700 N or more, The protective mat according to any one of claims 1 to 3.

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