JP3286862B2 - Waterproof sheet for civil engineering - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waterproof sheet for civil engineering which is excellent in interlayer adhesion, mechanical properties and workability.

[0002]

2. Description of the Related Art Waterproof sheets used for water control and riverbank construction, reservoirs, pools, landfills for wastewater, and the like, are made of ethylene propylene rubber, polyvinyl chloride, ethylene-vinyl acetate copolymer. Union, high density polyethylene and the like are conventionally used in the form of a single layer.

[0003] Waterproof sheets include weather resistance that can withstand long-term exposure to weather and sunlight, chemical resistance that can withstand acids and alkalis, heat resistance and cold resistance that can withstand environmental temperature changes, large breaking loads, Properties such as sealing properties at the time of joining sheet ends at the site and flexibility to follow the ground shape to be constructed are required. Further, the sheet is used for civil engineering work, and is required to be inexpensive, have a low density, and have good workability during construction.

[0004] However, the conventional water-stop sheet cannot be said to sufficiently satisfy the above-mentioned requirements.

[0005] For example, polyvinyl chloride has a high density and is inferior in workability at the time of on-site construction. For a long period of sun exposure, the plasticizer volatilizes and loses its flexibility, and the weather resistance decreases. As the agent blooms, the sealing force decreases over time.

[0006] Ethylene propylene rubber is inferior in sealing performance due to bonding with an adhesive, and there are many accidents of water leakage from the sealing portion. Also, during the production of the sheet, the sheet is expensive because it requires a series of many steps such as a kneading step of a rubber component and additives such as an inorganic filler and carbon black, a sheet forming step by calendering, and a vulcanizing step. It is. Polyolefin resin has many advantages such as low density, excellent workability at the time of on-site construction, excellent chemical resistance, sealability, sheet workability, and excellent durability because it does not contain a plasticizer. . However, ethylene-vinyl acetate copolymer is excellent in cold resistance, flexibility and weather resistance, but is inferior in heat resistance. High-density polyethylene is excellent in heat resistance and has a large sheet breaking load, but is inflexible and inferior to the shape of the ground.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks of the conventional single-layer waterproof sheet and to provide a waterproof sheet having excellent interlayer adhesion, mechanical properties and workability. .

[0008]

Means for Solving the Problems As a result of extensive studies by the present inventors to solve the above problems, polyethylene having a specific range of density and a torsional rigidity of 400 kgf / c
The present inventors have found that the above-mentioned problems can be solved by forming a three-layer sheet using a composition with a thermoplastic resin of m ² or less, and changing the blending ratio of polyethylene and thermoplastic resin between the intermediate layer and both outer layers. The invention has been completed.

That is, the present invention is a multilayer sheet having a three-layer structure comprising an intermediate layer and both outer layers, and the intermediate layer has a density of 0.940 to 0.940.
90% by weight of polyethylene (1) of 0.965 g / cm ³
The following and torsional rigidity (JIS K6730) 400kg
f / cm ² or less of the thermoplastic resin (2) composition containing a 10% by weight or more made from (A), both outer layers density 0.9
40 to 0.965 g / cm ³ of polyethylene (3) 10
30% by weight and torsional rigidity (JIS K6730) 4
Thermoplastic resin (4) 70 to 9 of 00 kgf / cm ² or less
0% by weight of the composition (B), 30 kg
The present invention relates to a waterproof sheet for civil engineering having a sheet breaking load of f / cm or more. Hereinafter, the present invention will be described in detail.

The polyethylene used as the components (1) and (3) in the sheet of the present invention is a homopolymer of ethylene or ethylene and 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, It is a copolymer with an α-olefin such as 1-decene. Its density (JIS K6760) is 0.940 to 0.965 g /
cm ³ . If the density is less than this range, the breaking load of the sheet is not sufficient, and if the density exceeds this range, the water stopping sheet lacks flexibility, and the ground followability at the time of construction is deteriorated. Melt flow rate of polyethylene (JIS K7
210, a condition of 190 ° C. and a load of 2160 g, sometimes abbreviated as “MFR”. ) Is not particularly limited, but is preferably 0.1 to 5.0 g / 10 min. Outside this range, sheet workability may be poor, and beyond this range the sheet breaking load may be reduced. In addition, the sheet breaking load refers to the multi-layer sheet of the present invention according to JIS K7.
127 is a load when a sheet is punched out with a JIS No. 3 dumbbell and a No. 3 test piece is pulled at a speed of 200 mm / min to break the sheet. The sheet of the present invention is 30 kgf /
cm or more is sufficient.

The thermoplastic resin used as the component (2) or (4) in the sheet of the present invention is JIS.
The torsional rigidity by K6730 is 400 kgf / cm ²
Or less, preferably 300 kgf / cm ² or less. If the torsional rigidity exceeds 400 kgf / cm ² , the multilayer water stopping sheet lacks flexibility, and the ground following ability at the time of construction is deteriorated. The MFR of the thermoplastic resin (at 190 ° C. under a load of 2160 g according to JIS K7210) is not particularly limited, but is preferably 1.0 to 5.0 g / 10 minutes. Outside this range, sheet workability may be poor, and beyond this range the sheet breaking load may be reduced. This thermoplastic resin has a torsional rigidity of 400 kgf.
/ Cm ² or less, but the type is not limited, but ethylene-based copolymers and modified products thereof, styrene-based, olefin-based, PVC-based, urethane-based, ester-based,
An amide-based thermoplastic elastomer or the like alone or a mixture thereof is suitably used. Among these thermoplastic resins, they can be used alone without being mixed with other resins, and are excellent in multi-layer co-extruded sheet workability, interlayer adhesion and ground followability at the time of construction. Modified forms are preferably used.

Specific examples of ethylene copolymers and modified products thereof include copolymers of ethylene with vinyl esters such as vinyl acetate, vinyl propionate, and vinyl benzoate, and ethylene and methyl ester of acrylic acid or methacrylic acid. , A copolymer with an unsaturated carboxylic acid ester such as ethyl, n-butyl and isobutyl ester, and a copolymer with ethylene and an α-olefin such as propylene, 1-butene, 4-methyl-1-pentene and 1-hexene Copolymers, copolymers of ethylene with unsaturated carboxylic acids such as acrylic acid and methacrylic acid and metal salts thereof, ethylene / vinyl ester / carbon monoxide copolymer, ethylene / unsaturated carboxylic acid ester / carbon monoxide copolymer Copolymer, ethylene / unsaturated carboxylic acid ester / unsaturated carboxylic acid copolymer and metal salt thereof, ethylene / vinyl Ester / unsaturated carboxylic acid copolymer and its metal salt, ethylene / methyl acrylate / monoethyl maleate, ethylene / vinyl acetate / monoethyl maleate, saponified ethylene / vinyl acetate copolymer, and carboxylic acid of each of the above resins Modifications such as acid modification and silane modification are exemplified.

Among the above ethylene copolymers, the density (JISK7112) is 0.1 in consideration of the balance of sealing properties, heat resistance, flexibility, cold resistance, breaking load, elongation, etc. required for the water-stop sheet. 850 to 0.905 g / c
m ³ , the maximum peak temperature (T
Particularly preferred is a copolymer of ethylene having m) of 100 ° C. or more and α-olefin having 4 or more carbon atoms. When the above-mentioned ethylene copolymer is used as the thermoplastic resin, if the density is less than 0.850 g / cm ³ , industrial production becomes difficult and blocking of the composition pellets easily occurs, and the density is lowered. If it exceeds 0.905 g / cm ³ , the torsional rigidity may exceed 400 kgf / cm ² , and as a result, the flexibility of the sheet may be poor. If the maximum peak temperature (Tm) shown by differential scanning calorimetry is less than 100 ° C., the sheet may be excellent in flexibility, but the breaking load of the sheet may be small.

The method of measuring Tm by the differential scanning calorimeter is as follows.

[Method of Measuring Tm by Differential Scanning Calorimeter] A sample of about 5 mg is weighed from a hot-pressed film having a thickness of about 100 μm, and the temperature is raised from 80 ° C. to 230 ° C. at a rate of 80 ° C./min. Raise the temperature and hold for 5 minutes. 10 ℃
The temperature is lowered to −10 ° C. at a rate of / min and kept at −10 ° C. for 5 minutes. Next, the temperature is raised again to 230 ° C. at a rate of 10 ° C./min, and the temperature (° C.) at the apex of the largest peak among the peaks appearing during the temperature rise is defined as Tm.

The component (1) in the resin composition (A) constituting the intermediate layer of the present invention is 90% by weight or less, and the component (2) is 10% by weight or more. When the amount of the component (1) exceeds 90% by weight (the amount of the component (2) is less than 10% by weight), the interlayer between the intermediate layer and the outer layer of the sheet after co-extrusion molding, which is a preferred method for producing the multilayer sheet of the present invention. It is not preferable because the adhesiveness is poor. The upper limit of the addition amount of the component (2) is not particularly limited, and is appropriately selected depending on the type of the thermoplastic resin used so that the breaking load of the multilayer sheet of the present invention is 30 kgf / cm or more.

In the resin composition (B) constituting both outer layers of the present invention, the component (3) is 10 to 30% by weight, preferably 15 to 25% by weight, and the component (4) is 70 to 90% by weight, preferably Is 75 to 85% by weight. When the component (3) exceeds 30% by weight (the component (4) is less than 70% by weight), the water-stop sheet lacks flexibility, so that the ground following ability at the time of sheet construction deteriorates. The component (3) is less than 10% by weight ((4)
If the component exceeds 90% by weight), the interlayer adhesion between the intermediate layer and both outer layers of the co-extruded sheet, which is a preferred method for producing the multilayer sheet of the present invention, is poor.

The components (2) and (4) may be the same type of resin or different types of resins. However, the resin after co-extrusion molding which is a preferred method for producing the multilayer sheet of the present invention is sufficient. In order to provide interlayer adhesion between the intermediate layer and both outer layers, it is preferable that the resins are the same type of resin. For example, if an ethylene / vinyl acetate copolymer is used as the component (2), the interlayer adhesion of the sheet is better when the ethylene / vinyl acetate copolymer is used as the component (4).

Since the component (1) and the component (3) are the same kind of polyethylene, even if their densities and MFRs are different, they do not affect the interlayer adhesion.

The thickness of the multilayer waterproof sheet of the present invention is not particularly limited, but is preferably 0.8 to 3 mm. If the thickness is less than 0.8 mm, the breaking load of the waterproof sheet tends to be small, and if the thickness exceeds 3 mm, the cost increases and the workability at the time of sheet construction deteriorates because the weight becomes heavy. The thickness of the intermediate layer constituting the multilayer waterproof sheet is not particularly limited, and the breaking load of the multilayer sheet of the present invention is 30 kgf / cm or more depending on the type of the thermoplastic resin used as the component (2) or (4). Is appropriately selected so that

The polyethylenes (1) and (3) and the thermoplastic resins (2) and (4) of the present invention may contain, if necessary, an antioxidant and an antistatic as long as the effects of the present invention are not impaired. Thermoplastics such as agents, anti-blocking agents, lubricants, light stabilizers, ultraviolet absorbers, inorganic and organic fillers, nucleating agents, clarifying agents, coloring agents, organic peroxides, catalyst neutralizing agents, plasticizers, etc. Additives used for plastics may be used. Of these, it is preferable to add an ultraviolet absorber, a light stabilizer, carbon black, and the like to each layer for the purpose of enhancing the weather resistance of the waterproof sheet. Examples of the ultraviolet absorber and the light stabilizer include salicylates, benzophenones, benzotriazoles, cyanoacrylates, hindered amines, and organic nickels.

[0022] The multilayer waterproof sheet of the present invention has a breaking load of 30.
kgf / cm or more. When it is less than 30 kgf / cm, the sheet is broken at the time of construction due to ground protrusions or human power, or the sheet is destroyed by the weight of industrial waste or water put on the sheet after the construction, so that the sheet cannot be put to practical use.

The method for producing the multilayer waterproof sheet according to the present invention is not particularly limited, but the resin compositions (A) and (B) forming the intermediate layer and the outer layer are supplied to separate extruders, respectively. A method of forming a co-extrusion sheet by feeding it to a three-layer structure die after melt-kneading, a method of sandwich-laminating both outer layer sheets using a resin composition that forms an intermediate layer after forming an outer layer sheet in advance, an intermediate layer and one outer layer And a method of extruding and laminating a resin composition for forming an outer layer on the laminated sheet. Among these methods, a method of co-extruding a resin composition for forming the intermediate layer and the outer layer in three layers is most preferable from the viewpoint of productivity.

If necessary, polyethylene, polypropylene, polyamide, polyester, polyvinyl chloride, polystyrene, or the like, as far as the effects of the present invention are not impaired, may be further provided on both outer layers of the present invention and / or between the outer layer and the intermediate layer.
A resin layer of rubber, elastomer, or the like may be provided.

[0025]

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. % In Examples and Comparative Examples indicates% by weight. The physical properties in the examples were measured by the following methods.

Sheet breaking load According to JIS K7127, a sheet was punched out with a JIS No. 3 dumbbell, a No. 3 test piece was pulled at a speed of 200 mm / min, and a tensile load when the sheet was broken was measured. 30
It is sufficient if it is at least kgf / cm.

The torsional rigidity was measured according to JIS K6730.

Flexibility (Following the ground) The following of the shape of the sheet when the sheet was covered from above the tree shown in FIG. 1 was visually observed and evaluated as follows. ；: Excellent in shape followability. ×: Poor shape followability.

The interlayer adhesion was visually inspected for delamination between the intermediate layer and both outer layers during the sheet tensile test and evaluated as follows. ；: No delamination. Δ: slight delamination is observed. ×: remarkable delamination.

Examples 1 to 3 The components (1) and (3) had a density of 0.956 g.
/ Cm ³ , polyethylene having an MFR of 0.45 g / 10 min and a density of 0.90 as component (2) and component (4).
An ethylene / 1-butene copolymer having a ratio of 0 g / cm ³ , an MFR of 2 g / 10 min, and a torsional rigidity of 200 kgf / cm 2 was blended in the ratio shown in Table 1, and further, 2% of carbon black was used for both the intermediate layer and both outer layer resins. The mixture was melt-kneaded using a twin-screw extruder to prepare a composition pellet.

The pellets of the composition are converted into a resin (A) for an intermediate layer.
Is supplied to an extruder having a diameter of 50 mm and an outer layer resin (B) having a diameter of 65 mm. The intermediate layer is passed through a three-layer T-die at 220 ° C. To obtain a multilayer sheet.

The results of measuring various physical properties of this sheet are shown in Table 1. The sheet was excellent in breaking load, flexibility and interlayer adhesion, and had good properties as a water-stop sheet.

Example 4 The components (1) and (3) had a density of 0.953 g.
/ Cm ³ , polyethylene having an MFR of 1 g / 10 min, and a component (2) and a component (4) having an MFR of 3 g / 10 min.
Min, vinyl acetate content is 10% by weight, torsional rigidity is 25
0 kgf / cm ^{2 of} an ethylene / vinyl acetate copolymer was blended at the ratio shown in Table 1, 2% of carbon black was added to both the intermediate layer and both outer layer resins, and the mixture was melt-kneaded using a twin-screw extruder to obtain a composition pellet. Produced.

Using the pellets of the composition, a multilayer sheet was prepared by co-extrusion at the thickness shown in Table 1 under the same conditions as in Example 1.

The results of measuring various physical properties of this sheet are shown in Table 1. The sheet was excellent in breaking load, flexibility and interlayer adhesion, and had good properties as a water-stop sheet.

Example 5 The components (1) and (3) had a density of 0.958 g.
/ Cm ³ , polyethylene having an MFR of 0.85 g / 10 min, and a component (2) and a component (4) having an MFR of 1.5
g / 10 minutes, an ethylene / ethyl acrylate copolymer having an ethyl acrylate content of 15% by weight and a torsional rigidity of 180 kgf / cm ² was blended in the ratio shown in Table 1, and further, carbon black was used in both the intermediate layer and both outer layer resins. % And melt-kneaded using a twin-screw extruder to prepare a composition pellet.

Using the pellets of the composition, a multilayer sheet was prepared by co-extrusion under the same conditions as in Example 1 with the thickness shown in Table 1.

The results of measuring various physical properties of this sheet are shown in Table 1. The sheet was excellent in breaking load, flexibility and interlayer adhesion, and had good properties as a water-stop sheet.

Example 6 As a resin composition for an intermediate layer (A), 2% of carbon black was added to 79% of polyethylene used in Example 1 and 19% of an ethylene / vinyl acetate copolymer used in Example 4; As the outer layer resin composition (B), 2% of carbon black was added to 19% of the polyethylene used in Example 2 and 79% of the ethylene / ethyl acrylate copolymer used in Example 5, and melted using a twin screw extruder. The mixture was kneaded to prepare a composition pellet.

Using the pellets of the composition, a multilayer sheet was prepared by co-extrusion under the same conditions as in Example 1 with the thickness shown in Table 1.

Table 1 shows the results of measuring various physical properties of this sheet. This sheet using different kinds of resins for the component (2) and the component (4) was excellent in flexibility and breaking load, but was found to have a little lack in interlayer adhesion.

Example 7 As a resin composition for the intermediate layer, 79% of the polyethylene used in Example 1 and 15% of the ethylene / vinyl acetate copolymer used in Example 4, having a density of 0.88 g / cm ³ and an MFR of 3g
/ 10 minutes, an ethylene / propylene copolymer having a torsional rigidity of 10 kgf / cm ² (trade name: Toughmer P028)
0, manufactured by Mitsui Petrochemical Industry Co., Ltd.), 4% of carbon black was added, and the resin composition for both outer layers was 19% of polyethylene used in Example 5;
2% of carbon black was added to 79% of the ethyl acrylate copolymer, and the mixture was melt-kneaded using a twin-screw extruder to prepare a composition pellet.

The composition pellets were coextruded under the same conditions as in Example 1 with the thickness shown in Table 1 to produce a multilayer sheet.

Table 1 shows the results of measurement of various physical properties of the sheet. This sheet using different types of resins for the component (2) and the component (4) was excellent in breaking load and flexibility, but was found to have a little lack of interlayer adhesion.

Comparative Example 1 Carbon black was added at 2% to 98% of the polyethylene used in Example 1 as the resin composition for the intermediate layer (A), and the ethylene used in Example 1 as the resin composition for both outer layers (B). /
2% of carbon black was added to 98% of 1-butene copolymer, and the mixture was melt-kneaded using a twin-screw extruder to prepare a composition pellet.

The composition pellets were coextruded under the same conditions as in Example 1 with the thickness shown in Table 1 to produce a multilayer sheet.

Table 1 shows the results of measuring various physical properties of this sheet. The present sheet comprising the composition (A) containing only the component (1) and the composition (B) containing only the component (4) was excellent in flexibility but lacked interlayer adhesion, resulting in a small breaking load.

Comparative Example 2 A composition pellet was prepared in the same manner as in Example 1 except that 2% of carbon black was added to 98% of the polyethylene used in Example 1. Using a 90 mm diameter cast molding machine equipped with a T die, a single layer sheet having a thickness of 1.5 mm was produced at a resin temperature of 220 ° C. and a processing speed of 1.5 m / min.

The results of measuring various physical properties of this sheet are shown in Table 1. The polyethylene single-layer sheet was sufficient in breaking load but poor in flexibility.

Comparative Example 3 The polyethylene used in Example 1 was used as the component (1) and the component (3), and M was used as the component (2) and the component (4).
FR 1.6 g / 10 min, density 0.920 g / 10
A low-density polyethylene having a torsional rigidity of 500 kgf / cm ² is blended in the ratio shown in Table 1, and 2% of carbon black is added to both the intermediate layer and the outer layer resin, and the mixture is melt-kneaded using a twin-screw extruder. Pellets were made.

Using the pellets of the composition, a multilayer sheet was produced by co-extrusion under the same conditions as in Example 1 with the thickness shown in Table 1.

Table 1 shows the results of measuring various physical properties of this sheet. This sheet using a thermoplastic resin having a torsional rigidity of more than 400 kgf / cm ² for the component (2) and the component (4) had sufficient breaking load but was poor in flexibility.

Comparative Example 4 The polyethylene used in Example 1 was used as the component (1) and the component (3), and the ethylene / 1-butene copolymer used in Example 1 was used as the component (2) and the component (4). Table 1
, And 2% of carbon black was added to both the intermediate layer and both outer layer resins, and the mixture was melt-kneaded using a twin-screw extruder to produce a composition pellet.

Using the pellets of the composition, a multilayer sheet was prepared by co-extrusion under the same conditions as in Example 1 with the thickness shown in Table 1.

Table 1 shows the results of measuring various physical properties of this sheet. When the content of the component (4) in the composition (B) was less than 70% by weight, the sheet had sufficient breaking load but poor flexibility.

Comparative Example 5 The polyethylene used in Example 4 was used as the component (1) and the component (3), and the ethylene / vinyl acetate copolymer used in Example 4 was used as the component (2) and the component (4). 1
, And 2% of carbon black was added to both the intermediate layer and both outer layer resins, and the mixture was melt-kneaded using a twin-screw extruder to produce a composition pellet.

Using the pellets of the composition, a multilayer sheet was prepared by co-extrusion under the same conditions as in Example 1 with the thickness shown in Table 1.

Table 1 shows the results of measurement of various physical properties of the sheet. Although this sheet was excellent in flexibility, the breaking load was insufficient.

Example 9 (On-site execution test) An on-site execution test was performed using the sheets of Example 4 and Comparative Example 5. The sheets were placed along a gentle slope, the sheet ends were overlapped, and hot air of 350 ° C. or more was blown with a hot air gun and hot-sealed to fuse the sheets together while pressing the sheets with rollers. During this operation, the sheet of Comparative Example 5 was damaged at the place where it hit the ground protrusion. On the other hand, the sheet of Example 4 did not show any breakage of the sheet during construction.

[0060]

[Table 1]

[0061]

The multilayer sheet of the present invention is excellent in weather resistance, chemical resistance, heat resistance, cold resistance, breaking load, sealability, flexibility, durability, workability during construction, flood control / river work, reservoir. It is suitably used as a water stop sheet used for the purpose of stopping water in pools, waste landfills and the like.

[Brief description of the drawings]

FIG. 1 is a perspective view of a flexibility test device used for measuring flexibility in Examples and Comparative Examples of the present invention.

Claims (5)

(57) [Claims] 1. A multilayer sheet having a three-layer structure comprising an intermediate layer and both outer layers, wherein the intermediate layer has a density of 0.940 to 0.965 g /
cm ³ of polyethylene (1) 90 wt% or less torsional rigidity (JIS K6730) 400 kgf / cm ² or less of the thermoplastic resin (2) composition containing a 10% by weight or more made from (A), the both outer layers Density 0.940 ~ 0.96
5 g / cm ³ of polyethylene (3) 10 to 30% by weight and torsional rigidity (JIS K6730) 400 kgf / c
consists m ² or less of the thermoplastic resin (4) 70 to 90% by weight composition containing (B), civil engineering waterproofing sheet having a sheet breaking load of more than 30 kgf / cm. 2. A thermoplastic resin (2) and a thermoplastic resin (4).
Are the same type of resin. 3. The waterproof sheet for civil engineering according to claim 1, wherein the thermoplastic resin (2) and the thermoplastic resin (4) are ethylene copolymers. 4. An ethylene copolymer having a density of 0.850 or less.
4. A copolymer of ethylene having a maximum peak temperature (Tm) of 0.905 g / cm < ³ > and a differential scanning calorimetry of 100 [deg.] C. or more and at least one other [alpha] -olefin.
Waterproof sheet for civil engineering described in 1. 5. The composition (A) and the composition (B) are co-extruded in three layers with the composition (A) as an intermediate layer and the composition (B) as both outer layers. 5. The method for producing a water-blocking sheet for civil engineering according to any one of items 4 to 4.