JP3491649B2 - Impermeable sheet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for intercepting water transfer in soil during landfilling of waste and construction of dams and reservoirs, and also for rainwater on a building roof. The present invention relates to a seepage control sheet suitable for construction for preventing penetration of water. 2. Description of the Related Art Waterproof insulation sheets for landfill disposal of waste, construction of dams, reservoirs, or waterproofing on building roofs have been used for a long time because they are made of soft vinyl chloride resin or rubber. Have been. However, although the soft vinyl chloride resin-based sheet has good heat fusion bonding property between sheets, it has a problem in plasticizer transferability and the like and lacks durability. Further, the rubber-based sheet has an inconvenience that an adhesive must be used for bonding between the sheets. In order to improve these properties, in recent years, polyethylene-based sheets (JP-A-59-15416, JP-A-1-29436)
And JP-A-1-29437) and an ethylene-vinyl acetate copolymer sheet. However, these polyethylene-based sheets have insufficient fusion bonding properties between the sheets, so that despite the good physical properties of the sheets themselves, water tends to leak from the joints, and hard sheets with curling habits Therefore, there is a problem that the followability of the shape of the base to the undulation is poor. Further, the ethylene-vinyl acetate copolymer-based sheet has an advantage that the sheet is easily heat-sealed, but has a problem that the physical properties of the sheet are insufficient. SUMMARY OF THE INVENTION The present invention has been made to provide an olefin-based soft sheet having excellent heat-fusibility, high strength, and good substrate followability. The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a specific high-pressure method low-density polyethylene and / or a low-pressure method linear low-density polyethylene. A sheet formed using a material obtained by adding a specific low-pressure linear low-density polyethylene and an ethylene-vinyl acetate copolymer to the base, and having excellent heat-fusibility, tensile strength, and I found that the base shape followability was good,
Based on this finding, the present invention has been completed. That is, the present invention provides (A) a melt flow rate of 0.1 to 10
g / 10 minutes (190 ° C.), 100 parts by weight of high-pressure low-density polyethylene or / and low-pressure linear low-density polyethylene, (B) linear ultra-low density of 0.890 to 0.914 g / cm ³ 2 to 50 parts by weight of polyethylene and (C) melt flow rate 0.8 to 40 g / 10 min (190 ° C.)
And 1 to 30 parts by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 10 to 40% by weight. The high-pressure low-density polyethylene (HPLD) or low-pressure linear low-density polyethylene (LLDPE) used as the component (A) in the present invention has a melt flow rate at 190 ° C. of 0.1 to 10 g / 10. Min, preferably 0.
3 to 5.0 g / 10 min. If the melt flow rate is less than 0.1 g / 10 minutes, it becomes difficult to form the sheet, and if it exceeds 10 g / 10 minutes, the mechanical strength of the formed sheet decreases. The high-pressure low-density polyethylene (HPLD) is produced by a radical polymerization method under a high pressure of 1,000 atm or more, and has a molecular structure including a short chain such as an ethyl group and a propyl group and a long chain branch. Therefore, the density is low, generally 0.910 to 0.929 g / cm ³
It is. In addition, the low pressure linear low density polyethylene (L
LDPE) is ethylene and 1-
Butene, 1-pentene, 4-methyl-1-pentene, 1
Produced by anionic polymerization with an α-olefin having 4 to 10 carbon atoms, such as decene, having a density generally of 0.918
0.940. The component (A) has a function of expressing flexibility in the molded sheet in the present invention. The low-pressure linear ultra-low density polyethylene (VLDPE) used as the component (B) in the present invention has a density of 0.890 to 0.910 g / cm ³ . If the density is less than 0.890 g / cm ³ , the surface of the molded sheet is sticky and scratches are easily formed. If the density is greater than 0.910 g / cm ³ , the molded sheet will lack flexibility. The linear ultra-low-density polyethylene is anionic polymerized with ethylene and an α-olefin having 4 to 8 carbon atoms such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene and 1-octene. Is a copolymer. The content of α-olefin is as follows: the low pressure method linear low density polyethylene (LLDPE) is several weight%.
On the other hand, it is as much as 10% by weight. In the present invention,
The linear ultra-low-density polyethylene has an effect of imparting flexibility to a molded sheet without impairing mechanical strength. In addition, by combining an ethylene-vinyl acetate copolymer described below, the flexibility can be adjusted so that the molded sheet can follow the base shape. The amount of the linear ultra-low density polyethylene used is a high pressure method low density polyethylene and / or a low pressure method linear low density polyethylene 100
It is necessary to use 2 to 50 parts by weight per part by weight, preferably 10 to 35 parts by weight. If the amount is less than 2 parts by weight, the flexibility of the molded sheet tends to be insufficient, and if it is more than 50 parts by weight, the peel strength of the heat-sealed portion between the molded sheets tends to decrease. The ethylene-vinyl acetate copolymer (EVA) used in the present invention has a melt flow rate at 190 ° C. of 0.8 to 40 g / 10 minutes and a vinyl acetate monomer unit content of 10 to 40% by weight. It contains. If the melt flow rate is less than 0.8 g / 10 minutes, the workability of sheet molding will be poor, and if it exceeds 40 g / 10 minutes, the mechanical strength such as the tensile strength of the sheet will decrease. The preferred melt flow rate is 2.0 to 30 g / 10 minutes. On the other hand, if the content of the vinyl acetate monomer unit is less than 10% by weight, the mechanical strength of the molded sheet decreases, and if it is more than 40% by weight, the sheet surface becomes inconvenient. The preferred vinyl acetate monomer unit content is 20 to 30% by weight. The amount of the ethylene-vinyl acetate copolymer used is as follows: high-pressure low-density polyethylene and / or low-pressure linear low-density polyethylene.
It is 1 to 30 parts by weight, preferably 5 to 20 parts by weight, per 100 parts by weight. If the amount is less than 1 part by weight, the heat sealability between the formed sheets becomes insufficient, and if the amount is more than 30 parts by weight, the mechanical strength of the formed sheet decreases. In the present invention, in addition to the high-pressure low-density polyethylene and / or the low-pressure linear low-density polyethylene (component (A)) and the low-pressure linear ultra-low-density polyethylene (component (B)), By combining the above-mentioned ethylene-vinyl acetate copolymer (component (C)) in a prescribed amount, it is possible to obtain a rigidity suitable for a water-blocking sheet and a flexibility capable of following the base shape, a heat-fusing property, and the like. Can be combined. [0009] In the compounding of the molding material of the waterproof sheet of the present invention, a filler such as carbon black, calcium carbonate, silica, talc or the like may be added as long as the flexibility and mechanical strength of the sheet are not impaired. it can. As a method of forming the water-blocking sheet of the present invention, for example, a molding material mixture is heated to 160 to 220 ° C. by an extruder to make it into a fluidized state and T-die extruded. It can also be formed by a calender roll method. The thickness of the sheet is usually 0.5 to 3.0
mm. INDUSTRIAL APPLICABILITY The waterproof sheet of the present invention is used as a waterproof sheet at the time of dam and reservoir construction, as a waterproof sheet on the roof of a building, and the like as a shielding sheet at the time of landfill treatment of household waste and industrial waste. The impermeable sheet of the present invention can be applied over a wide area by fusing the ends of a plurality of sheets with a hot blower or the like at the time of construction. [0010] Embodiments of the present invention include the following. (1) (A) Melt flow rate 0.1 to 10 g / 10
100 parts by weight of high-pressure low-density polyethylene and / or low-pressure linear low-density polyethylene (190 ° C.), (B)
2 to 50 parts by weight of a low pressure linear ultra-low density polyethylene having a density of 0.890 to 0.914 g / cm ³ and (C) a vinyl acetate unit of 10 at a melt flow rate of 0.8 to 40 g / 10 min (190 ° C.) A water-blocking sheet comprising 1 to 30 parts by weight of an ethylene-vinyl acetate copolymer in an amount of 40 to 40% by weight. (2) the melt flow rate of the high-pressure low-density polyethylene or / and the low-pressure linear low-density polyethylene is 0.3 to
The water impermeable sheet according to the above (1), which has 5.0 g / 10 minutes (190 ° C.). (3) Low pressure method linear ultra low density polyethylene is 10 to 35
The impermeable sheet according to the above (1) or (2), which is used by weight. (4) The impermeable sheet according to any one of (1) to (3) above, wherein the melt flow rate of the ethylene-vinyl acetate copolymer is 2.0 to 30 g / 10 minutes (190 ° C.). (5) The above (1) to (10), wherein the content of the vinyl acetate monomer unit of the ethylene-vinyl acetate copolymer is 20 to 30% by weight.
The impermeable sheet according to any one of (4). (6) The water impermeable sheet according to any one of (1) to (5), wherein 5 to 20 parts by weight of the ethylene-vinyl acetate copolymer is used. The present invention will be described in more detail with reference to the following Examples, which by no means limit the present invention. Test method 1) Melt flow rate (MFR) Measured at a measurement temperature of 190 ° C. and a load of 2.16 Kg according to JIS K 6760. 2) Surface hardness The hardness of the sheet surface was measured according to JIS K 7215 D method. When the hardness is 50 or more, the sheet is hard, so that it is judged that the base shape following property at the time of construction is poor. 3) Manual Leister Bonding Each end of two sheets obtained by molding was subjected to 30 × 1000.
The portion of 0 mm is superimposed while being heated with hot air of 450 ° C. by a handy typewriter manufactured by Parker Shoji Co., Ltd.
After pressing and fusing with a hand roller, in the following fused part shear peel test, when the material is broken without peeling,
The case where the sheet peels off on the fused surface is indicated by x, and the case where the sheet peels off with partial material destruction is indicated by Δ. 4) Retention rate of fusion strength An index indicating the ratio of the rupture strength of the fused portion by the above-mentioned manual leister to the rupture strength of the non-fused portion, which is obtained by the following equation. . Fusing strength retention rate = (f × 5 / F) × 100 (%) where f is the shearing peel strength of the fused portion (kgf / 25 mm)
It is. f was measured in a direction perpendicular to the welding margin with a width of 25 mm.
mm, a strip of 230 mm in length (100 mm each length was taken on both sides of the width of the fused portion of 30 mm) was cut into a test piece,
Both ends are pulled at a speed of 200 mm / min according to JIS K 6850, and the strength at which the fused portion is peeled or broken is obtained. F is the tensile breaking strength of the sheet (kgf /
5 mm). The measurement of F is obtained as a tensile strength of a non-fused portion based on JIS A 6008 for a sheet test piece punched with a 5 mm width dumbbell. Examples 1 to 5 and Comparative Examples 1 to 7 The molding materials were sufficiently mixed by a tumbler in the composition shown in Table 1, and the temperature of the die portion was reduced to 210 ° C. by a single vent extruder having a diameter of 120 mm equipped with a T die. Thus, a sheet having a width of 1,000 mm and a thickness of 1.5 mm was formed. The hardness, the bondability of the manual leister, and the fusion strength retention were determined for the obtained sheet. Table 1 shows the results. [Table 1] Note) HPLD1: trade name M-082, Ace Polymer Co., Ltd.
Made, high-pressure low-density polyethylene, density 0.926 g / c
m ³ , MFR 0.8 g / 10 min HPLD2: trade name M-221, Ace Polymer Co., Ltd.
Made, high density low density polyethylene, density 0.916g / c
m ³ , MFR 22 g / 10 min LLDPE1: trade name FZ-102-O, manufactured by Sumitomo Chemical Co., Ltd., low pressure linear low density polyethylene, density 0.
912 g / cm ³ , MFR 0.8 g / 10 min LLDPE2: trade name GZ801, Sumitomo Chemical Co., Ltd.
, Low pressure linear low density polyethylene, density 0.920
g / cm ³ , MFR 20 g / 10 min VLDPE1: trade name VL100, Sumitomo Chemical Co., Ltd.
Manufactured, low pressure linear ultra low density polyethylene, density 0.90
0 g / cm ³ , MFR 0.8 g / 10 min VLDPE2: trade name EUL130, manufactured by Sumitomo Chemical Co., Ltd., low pressure linear ultra-low density polyethylene, density 0.890 g / cm ³ , MFR 0.8 g / 10 min EVA1 : Trade name Ultracene 710, manufactured by Tokuyama Corporation, ethylene-vinyl acetate copolymer, vinyl acetate monomer unit 28% by weight, MFR 18 g / 10 minutes EVA2: trade name Ultracene 720, manufactured by Tokuyama Corporation, ethylene -Vinyl acetate copolymer, vinyl acetate monomer unit 28% by weight, MFR 150 g / 10 minutes HDPE: 4551H, trade name, Ace Polymer Co., Ltd.
Made, low pressure method high density polyethylene, density 0.945g / c
m ³ , 0.01 g / 10 min MFR The sheets of Examples 1 to 5 which are examples of the present invention are as follows:
All of them have a sufficient tensile breaking strength and a hardness of 50 or less, so that it is judged that the substrate shape followability is good. Furthermore, the bondability and fusion strength retention of these joints are in a satisfactory range. Since the sheet using the high-density polyethylene has a very high hardness, it is determined that the sheet does not have the ability to follow the underlying shape (Comparative Example 1). If the amount of the low-pressure method linear ultra-low-density polyethylene (B) specified in the present invention is too large or not present, fusion bonding is not successful or the hardness is too large (Comparative Examples 2 and 3). . In addition, a sheet in which the ethylene-vinyl acetate copolymer (C) defined in the present invention is not present is also determined to have too high hardness and insufficient base shape followability (Comparative Example 4). When the melt flow rate of the high-pressure method low-density polyethylene or the low-pressure method linear low-density polyethylene is higher than the value specified in the present invention, the tensile strength at break of the sheet is deteriorated (Comparative Examples 5 and 6). Further, when the melt flow rate of ethylene-vinyl acetate is larger than the specified value of the present invention, the fusion bonding is poor (Comparative Example 7). According to the present invention, there is provided a water-blocking sheet having heat-fusing property, excellent tensile and tear strength, and excellent followability of the base shape.

Continuation of front page (56) References JP-A-61-168646 (JP, A) JP-A-6-32950 (JP, A) JP-A-5-140381 (JP, A) JP-A-5-247280 (JP) JP-A-59-15416 (JP, A) JP-A-64-29437 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 23/00-23/36 C08J 5/18

Claims (1)

(57) [Claim 1] (A) Melt flow rate 0.1 to 10
g / 10 minutes (190 ° C.), 100 parts by weight of high-pressure low-density polyethylene or / and low-pressure linear low-density polyethylene, (B) low-pressure linear over-density of 0.890 to 0.914 g / cm ³ 2 to 50 parts by weight of low density polyethylene and (C) melt flow rate of 0.8 to 40 g / 10 min (1
A water-impervious sheet comprising 1 to 30 parts by weight of an ethylene-vinyl acetate copolymer containing 10 to 40% by weight of vinyl acetate units at 90 ° C).