JPS6337607B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a flexible structure for irrigation (hereinafter referred to as irrigation tube) that has excellent repeated pressure fatigue strength, heat resistance, cold resistance, tear resistance, impact resistance, etc. Our goal is to provide the following. In recent years, irrigation tubes made of high-pressure polyethylene or ethylene-vinyl acetate copolymer have been used instead of hard synthetic resin pipes. These irrigation tubes expand into a cylindrical shape when water is flowing through them, and have a flat shape when water is not flowing through them, so they are easier to store and store than conventional hard synthetic resin tubes.
It is easy to transport and store, and can be freely adapted to change the spacing of cultivated plants or to any shape of the irrigation area. On the other hand, because of this shape, conventional irrigation tubes made of high-pressure polyethylene or ethylene/vinyl acetate copolymer are heat-sealed by repeating the water flow/non-water flow cycle. There is a problem that peeling occurs in some parts. As a result of intensive research into this problem, the present inventors discovered that by using a specific resin composition for the outer layer of the irrigation tube, an irrigation tube with good repeated pressure fatigue strength can be obtained, and the present invention has been made. I was able to complete it. That is, the present invention provides a thermoplastic material having at least one continuous heat-sealed portion extending along its length and having a number of irrigation holes arranged at appropriate intervals along its length. An irrigation tube made of a synthetic resin film, which expands and assumes a cylindrical shape when water is flowing through it, but becomes flat when no water is flowing through it, and the thermoplastic synthetic resin film has a melt index (190 ℃, 2.16Kg) 0.5 to 10g/10min,
Density 0.900 to 0.940g/cm ³ , melting point 110 to 130
℃ and ethylene content of 60 to 97.5% by weight by medium and low pressure method and ethylene with carbon number of 4 to 97.5%.
A preferred embodiment of the present invention relates to an irrigation tube characterized in that it is made of a thermoplastic synthetic resin film made of a random copolymer of 20 α-olefins; It has a continuous heat-sealed part,
and an irrigation tube consisting of two layers, an inner and an outer layer, having a large number of irrigation holes arranged at appropriate intervals in the length direction of the outer layer, the outer layer having a melt index of 0.5 to 10 g/10 min, a density of Consisting of a random copolymer of ethylene and α-olefin having 4 to 20 carbon atoms obtained by a medium-low pressure method with a weight of 0.900 to 0.940 g/cm ³ , a melting point of 110 to 130°C, and an ethylene content of 60 to 97.5% by weight. The tube is made of a flexible thermoplastic synthetic resin film, the inner layer is located inside the outer layer, and the flexible inner layer is made of a water-permeable and water-insoluble sheet-like material fixed to the outer layer. , relates to an irrigation tube characterized in that it expands and assumes a cylindrical shape when water is flowing, but becomes a flat piece when water is not flowing. In the present invention, α-olefins having 4 to 20 carbon atoms copolymerized with ethylene in the copolymer used in the outer layer include 1-butene, 1-pentene, 1-
hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene or mixtures thereof, especially α-olefins having 6 to 8 carbon atoms, especially 4-
Methyl-1-pentene is preferred. Also, the copolymer melt index (ASTM
D1238; 190℃, 2.16Kg, hereinafter MI) is 0.5 to 10
g/10 min, preferably in the range of 0.5 to 5 g/10 min. If the MI is less than 0.5, the fluidity will be poor and the moldability will be poor, and if the MI is more than 10, the mechanical properties such as impact resistance and tear strength will be poor. The density of the copolymer must be determined in order to have good impact resistance.
It is preferably 0.940 g/cm ³ or less, and preferably 0.900 g/cm ³ or more for excellent tensile strength and rigidity. In addition, in order for the fog level to be within the above range,
The ethylene content in the copolymer should be between 60 and 97.5% by weight. Furthermore, the copolymer has one or more melting points (points showing sharp peaks), often two or three, as determined from the endothermic curve of differential thermal analysis (DSC) at a heating rate of 10°C/min. Preferably there are three. And its highest melting point is 110 or
130°C, preferably in the range of 115 to 125°C.
If the melting point is less than 110°C, the film will have poor heat resistance, and if it exceeds 130°C, the low-temperature heat sealability will be poor. The above-mentioned copolymer can be produced by polymerizing ethylene and α-olefin in a proportion that provides the required density by a so-called medium-low pressure method using a transition metal catalyst. At that time, the desired
To obtain MI, a molecular weight modifier such as hydrogen may be used. Polymerization can be carried out by various methods such as slurry polymerization, gas phase polymerization, and high temperature solution polymerization. In addition, weathering stabilizers, heat-resistant stabilizers, antistatic agents, antifogging agents, anti-blocking agents, slip agents, lubricants, pigments, dyes, etc. may be added to the above copolymer to the extent that its properties are not impaired. good. Further, a portion of the copolymer may be replaced with high-pressure polyethylene in an amount of less than 10% by weight. In order to obtain an irrigation tube, that is, a flexible structure for irrigation, using the copolymer, for example, a large number of irrigation holes (the holes may be round, polygonal, slit, etc.) in the longitudinal direction of the film are used. A continuous film made of the copolymer in the form of a tape with perforations (which may be of any shape) and a continuous film made of the copolymer in the form of a tape with no perforations are laminated, and while running the laminated tape-like material, It is obtained by successively heat-sealing both widthwise ear portions. In addition, in order to prevent clogging of the irrigation holes, if a water-permeable, water-insoluble sheet-like material is used as the inner layer, a water-permeable, water-insoluble nonwoven fabric, etc. It is obtained by laminating the tape-like articles in such a way that continuous tape-like articles are positioned, and then heat-sealing both edges in the width direction of the laminated tape-like articles. The irrigation tube obtained in this way has a repeated pressure fatigue strength (for a 1.2 m long tube,
A method of passing water for 2 minutes at an irrigation pressure of 1.0 Kg/cm ² and then not allowing water to pass for 2 minutes, repeating the water passing/not passing cycle and seeing how many times the tube breaks), conventional high pressure Legal polyethylene and ethylene
It is superior to irrigation tubes made of vinyl acetate copolymer, and also has excellent impact resistance, tear resistance, cold resistance, and heat resistance. The irrigation tube of the present invention, that is, the flexible structure for irrigation, can be used not only for water but also for liquid fertilizers, water-soluble insecticides, acaricides, water-soluble fungicides, virucidal agents, water-soluble herbicides, dustproofing agents, and other substances. It has a wide range of applicability, allowing for drainage or irrigation of water containing chemicals, and also for underground irrigation in relatively shallow soil. Example 1 MI2.1g/10min, density 0.920g/cm ³ , melting point 120
A film (width 42 mm) of ethylene/4-methyl-1-pentene random copolymer obtained by a medium-low pressure method with an ethylene content of 91% by weight at These films are laminated continuously while running so that a continuous tape-like material of non-woven fabric made of thermoplastic synthetic resin fibers is located between the film with holes and the film with no holes. While running, both edges in the width direction were continuously heat-sealed to obtain a flexible structure for irrigation. Using this structure, repeated pressure fatigue strength tests and JIS
A tensile creep test was conducted according to the method of K715.
The results are shown in Table 1. For reference, the tear strength of the original film (JIS
Table 1 also shows the test results of heat sealing strength (according to the method of Z1702) and heat sealing strength (heat sealing conditions: 220°C, 2Kg/cm ² , 2sec). Comparative Example 1 The same procedure as in Example 1 was carried out using high-pressure polyethylene (Mirason ACE30N, Mitsui Polychemical Co., Ltd.) with an MI of 0.5 g/10 min. The results are shown in Table 1. 【table】

Claims (1)

[Claims] 1. It has at least one continuous heat-sealed portion extending along its length, and has a large number of irrigation holes arranged at appropriate intervals in its length. An irrigation tube made of a thermoplastic synthetic resin film, which expands and assumes a cylindrical shape when water is flowing through it, but becomes flat when no water is flowing through it, and the thermoplastic synthetic resin film has a melt index. (190℃, 2.16Kg) 0.5 to 10g/10min,
Density 0.900 to 0.940g/cm ³ , melting point 110 to 130
℃ and ethylene content of 60 to 97.5% by weight by medium and low pressure method and ethylene with carbon number of 4 to 97.5%.
An irrigation tube characterized by being made of a thermoplastic synthetic resin film made of a random copolymer with 20 α-olefins. 2. The irrigation tube according to claim 1, which has an inner layer made of a water-permeable, water-insoluble sheet-like material located inside the layer made of the thermoplastic synthetic resin film.