JP3491648B2 - Waterproof barrier sheet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waterproof cutoff sheet suitable for landfilling of waste, dam and reservoir construction, and waterproofing on a building roof. 2. Description of the Related Art As a waterproof cut-off sheet for landfilling of waste, construction of dams, reservoirs or waterproofing on building roofs, a soft vinyl chloride resin type or rubber type has been used for a long time. Was. However, soft vinyl chloride resin sheet
Although the heat-sealing bondability between the sheets is good, there is a problem in the transferability of the plasticizer. 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-59-1984)
15416, JP-A-1-29436, JP-A1-2
No. 9439) and an ethylene-vinyl acetate copolymer sheet. However, these polyethylene sheets have poor fusion bonding properties between the sheets, so that despite the good physical properties of the sheets themselves, water tends to leak from the joints. Has a problem that the ability to follow the undulation is poor. Further, the ethylene-vinyl acetate copolymer-based sheet has a problem that although the sheet is easily heat-sealed, the physical properties of the sheet are insufficient. SUMMARY OF THE INVENTION The present invention has been made to provide an olefin-based hard sheet having excellent heat-fusibility, high mechanical strength, and good followability of the base shape. . Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a specific high-density polyethylene and an α-olefin-based polyethylene have been A sheet formed using a material to which an ethylene-vinyl acetate copolymer is added has excellent heat-fusing properties, excellent tensile and tear strengths, and has a low tensile yield strength, is unlikely to have curl, and has a base shape. The inventor has found that the present invention has good followability, and has completed the present invention based on this finding. That is, the present invention provides a melt flow rate of 0.01 to 3.
0 g / 10 minutes (190 ° C) high density polyethylene 100
Parts by weight, 5 to 50 parts by weight of a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms and 20 to 4 vinyl acetate units
A waterproof barrier sheet comprising 0% by weight of an ethylene-vinyl acetate copolymer, wherein the content of the ethylene-vinyl acetate copolymer is such that the ratio of the vinyl acetate monomer units to the sheet is 0.5 to 0.5%. It is intended to provide a waterproof barrier sheet having an amount of 3.0% by weight. The high-density polyethylene used in the present invention is manufactured at a low pressure and has a specific gravity of 0.94 to 0.96. The melt flow rate at a measurement temperature of 190 ° C. needs to be 0.01 to 3.0 g / 10 minutes (190 ° C.), and preferably 0.04 to 2.0 g / 10 minutes. When the melt flow rate is less than 0.01 g / 10 min, or more than 3.0 g / 10 min, the moldability tends to deteriorate, and the mechanical strength of the sheet tends to decrease. If it exceeds, the heat sealability of the sheet also deteriorates. High-density polyethylene has the effect of improving the rigidity, impact resistance, water resistance, chemical resistance, cold resistance, etc. of the molded sheet. The ethylene-α-olefin copolymer used in the present invention is a copolymer of ethylene and 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like having 4 to 8 carbon atoms. Is a copolymer with an α-olefin. When the carbon number of the α-olefin is less than 4, the molded sheet tends to have insufficient tensile strength, impact resistance and stress crack resistance. In the present invention, the ethylene-α-olefin copolymer has a function of imparting flexibility to a hard olefin sheet without impairing mechanical strength. In addition, by combining an ethylene-vinyl acetate copolymer described below, the flexibility of the molded sheet can be adjusted so as to follow the base shape. The amount of the ethylene-α-olefin copolymer to be used is required to be 5 to 50 parts by weight, preferably 15 to 40 parts by weight, per 100 parts by weight of the high-density polyethylene. If the amount is less than 5 parts by weight, the flexibility of the formed sheet is insufficient, and if it is more than 50 parts by weight, the tear strength and the hardness of the formed sheet tend to decrease. The ethylene-vinyl acetate copolymer used in the present invention has a vinyl acetate unit content of 20 to 40% by weight.
And preferably 25 to 35% by weight. If the amount of the vinyl acetate unit is less than 20% by weight, the mechanical strength of the formed sheet is reduced, and if it is more than 40% by weight, the sheet is difficult to be formed. The amount of the ethylene-vinyl acetate copolymer to be used is such that the total amount of the vinyl acetate monomer units is 0.5 to 0.5 with respect to the molded sheet.
The amount occupies 3.0% by weight, preferably 1.0 to 2.0% by weight. When the amount of the vinyl acetate monomer unit is less than 0.5% by weight of the sheet, the heat sealability between sheets is insufficient, and when it is more than 3.0% by weight, the mechanical strength of the sheet is inferior. [0008] As properties suitable for the hard type waterproof blocking sheet, rigidity such as a tensile breaking strength of 300 kgf / cm ² or more, a tensile breaking elongation of 600% or more, and a tear strength of 140 kgf / cm ² or more is required, but it can follow the shape of the substrate. For this purpose, tensile yield strength of 220 kgf / cm ² or less, tensile elongation at break of 1,000% or less, and tear strength of 160 kgf / cm ²
The flexibility determined by cm ² or less is required. According to the present invention, the high-density polyethylene and ethylene-α-
By combining the above-mentioned ethylene-vinyl acetate copolymer in addition to the olefin copolymer in a specified amount, the rigidity and flexibility described above were not found in the conventional high-density polyethylene-based hard sheet. , And a property having more excellent thermal adhesiveness can be realized. In the compounding of the molding material of the waterproof barrier 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 molding the waterproof barrier 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 fluid state and extruded by T-die. It can also be formed by a calender roll method. Sheet thickness is usually 0.5 ~
It is 3.0 mm, preferably 1.0 to 2.0 mm. INDUSTRIAL APPLICABILITY The waterproof barrier sheet of the present invention is used as a barrier sheet for landfill treatment of household waste, industrial waste, and the like, as a waterproof sheet for dams and reservoir construction, as a waterproof sheet on the roof of a building, and the like. At the time of construction, the ends of multiple sheets can be fused using a hot air blower or the like,
It can be installed in a vast area, and can achieve the function of blocking leakage of water and harmful substances. [0010] Embodiments of the present invention include the following. (1) 100 parts by weight of high-density polyethylene having a melt flow rate of 0.01 to 3.0 g / 10 minutes (190 ° C.), and a copolymer 5 of ethylene and an α-olefin having 4 to 10 carbon atoms
What is claimed is: 1. A waterproof barrier sheet comprising an ethylene-vinyl acetate copolymer having a content of the ethylene-vinyl acetate copolymer of from 50 to 50 parts by weight and 20 to 40% by weight of a vinyl acetate unit.
A waterproof barrier sheet wherein the ratio of the vinyl acetate monomer unit to the sheet is 0.5 to 3.0% by weight. (2) The high-density polyethylene has a melt flow rate of 0.
The above (1), which is from 04 to 2.0 g / 10 minutes (190 ° C.)
Waterproof barrier sheet. (3) 15 to 40 ethylene-α-olefin copolymers
The waterproof blocking sheet according to the above (1) or (2), which is used by weight. (4) The above (1) to (3), wherein the content of vinyl acetate units in the ethylene-vinyl acetate copolymer is 25 to 35% by weight.
One of the waterproof barrier sheets. (5) When the content of the ethylene-vinyl acetate copolymer is such that the ratio of the vinyl acetate monomer unit to the sheet is 0.5
The waterproof shut-off sheet according to any one of the above (1) to (4), which is an amount of up to 3.0% by weight. (6) The waterproof cut-off sheet according to any one of (1) to (5), wherein the sheet has a thickness of 0.5 to 3.0 mm. 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) Tensile yield strength, tensile breaking strength and tensile breaking elongation JIS K6301. The test piece was used by punching a sheet with a No. 3 dumbbell. Pulling speed 200 at 23 ° C
The test was performed at mm / min. 3) Tear strength According to JIS K 6301, use a B-type test piece.
The test was performed at 3 ° C. at a tensile speed of 200 mm / min. 4) Specific gravity was carried out by a water displacement method according to JIS K 7112. 5) Bonding strength According to JIS K 6850. Using a 25 mm-wide tangled test piece, at 23 ° C., a pulling speed of 200 mm / mi
n. Examples 1 to 3 and Comparative Examples 1 to 7 The molding materials were sufficiently mixed by a tumbler in the composition shown in Table 1, and a cylinder temperature of 200 ° C. and a die were formed by a 120 mm diameter single belt extruder equipped with a T die. Temperature 210 ° C
To form a sheet having a width of 1,000 mm and a thickness of 1.5 mm. Table 1 shows the results of measuring the tensile properties, tear properties, and specific gravities of the obtained sheets. The weight ratio of the vinyl acetate units of the ethylene-vinyl acetate copolymer to the sheet is shown in parentheses in the column of the copolymer. Also, 1,0
Two sheets of 00 mm × 10,000 mm × 1.5 mm are overlapped with an area of 30 mm × 10,000 mm and heat-sealed using an automatic leister exclusively for polyethylene sheets and a manual and automatic leister exclusively for vinyl chloride resin sheets, respectively. The bonding strength was measured for each. Table 2 shows the results
Shown in [Table 1] Note) * 1 Trade name: HF310B, Mitsubishi Yuka Co., Ltd., MFR
0.06 g / 10 min, specific gravity 0.950 * 2 Trade name JX20, manufactured by Mitsubishi Yuka Co., Ltd., MFR5.
0 g / 10 min, specific gravity 0.964 * 3 Trade name: Sumikacene α FZ102-0, manufactured by Sumitomo Chemical Co., Ltd., ethylene-1-hexene copolymer, MF
R 0.80 g / 10 min, specific gravity 0.912 * 4 Sumikasen L FA102-0, trade name, manufactured by Sumitomo Chemical Co., Ltd., ethylene-1-butene copolymer, MFR
0.80 g / 10 min, specific gravity 0.925 * 5 Trade name Ultracene 710, manufactured by Tokuyama Corporation
Vinyl acetate content 28% by weight, MFR 18.0 g / 10
Min, specific gravity 0.948 * 6 Trade name Ultracene 541, manufactured by Tokuyama Corporation
Vinyl acetate content 10% by weight, MFR 9.0g / 10min * 7 Ultratrane 760, manufactured by Tokuyama Corporation
Vinyl acetate content 42% by weight, MFR 70.0 g / 10
Min, specific gravity 0.970 The sheets of Examples 1-4, which are examples of the invention, are judged to have sufficient tensile strength, tensile strength at break, tensile elongation at break, and tear strength, all of which have sufficient substrate shape following properties. Range. Satisfactory values were also obtained for the bonding strength of the heat-sealed portions of these sheets by the respective leisters. A sheet obtained by using a high-density polyethylene having an MFR of more than 3.0 g / 10 min has poor elongation and breaking strength, is brittle, and has poor bonding strength in heat fusion (Comparative Example 1). It can be seen that if the amount of the ethylene-α-olefin copolymer used is small, the tensile yield strength is large, and the material is hard and has poor substrate shape followability (Comparative Example 2). On the other hand, when the amount of the ethylene-α-olefin copolymer is too large, the tensile yield strength and the tear strength are low, and the heat fusion bonding strength is low (Comparative Example 3). Comparative Example 4 or 5 using an ethylene-vinyl acetate copolymer having a vinyl acetate content smaller or larger than a specified value
All gave sheets with reduced mechanical strength. When the blending amount of the ethylene-vinyl acetate copolymer is too small, the heat-sealing strength is low (Comparative Example 6), and when too large, the sheet properties such as tensile yield strength and breaking strength deteriorate (Comparative Example 7). . As described above, according to the present invention, an olefin-based hard sheet having excellent heat-fusibility, high mechanical strength, and excellent ability to follow the substrate shape can be obtained.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-232245 (JP, A) JP-A-6-32950 (JP, A) JP-A-61-168646 (JP, A) JP-A 64-64 29437 (JP, A) JP-A-59-15416 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 23/00-23/36 C08J 5/18

Claims (1)

(57) [Claims 1] Melt flow rate 0.01 to 3.0 g
100 parts by weight of high-density polyethylene at / 10 minutes (190 ° C.), 5 to 50 parts by weight of a copolymer of ethylene and an α-olefin having 4 to 8 carbon atoms, and 20 to 40% by weight of vinyl acetate units. A waterproof barrier sheet comprising a copolymer, wherein the content of the ethylene-vinyl acetate copolymer is such that the ratio of the vinyl acetate monomer unit to the sheet is 0.5 to 3.0% by weight. A waterproof cutoff sheet characterized by the following.