JPH0560787B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a resin-coated base fabric with an improved synthetic resin coating layer. ``Prior Art'' Conventionally, resin-coated base fabric, so-called tarpaulin, which is made by coating various fabrics and other base materials with a flexible synthetic resin coating, has been widely used in various fields as an industrial material, and its applications are tents. , sheets, flexible containers, etc. The resin-coated base fabric is made of synthetic rubber, soft vinyl chloride (soft
PVC), ethylene-vinyl acetate copolymer (EVA)
It is generally used as a synthetic resin to coat woven fabrics such as. ``Problem to be solved by the invention'' However, among these synthetic resins, synthetic rubber has excellent heat resistance and cold resistance, but has disadvantages such as poor colorability and processability, and has an odor, so it is not used. Limited range. Soft PVC has advantages such as excellent workability and good abrasion resistance, but it is inferior in terms of cold resistance and specific gravity, and problems arise due to plasticizer migration. In addition, EVA with a high vinyl acetate content (hereinafter referred to as high VA-containing EVA) has flexibility and rubber-like elasticity without the addition of plasticizers, and has excellent cold resistance. It has the disadvantage of poor wear resistance and heat resistance. In addition, this high VA content EVA generates a large amount of internal heat generated by high-frequency welding, and thus exhibits good welding strength, but has the disadvantage of strong adhesion to the weld bar during welding, which reduces workability during continuous processing. Here, the high-frequency welder is a device that heats and welds materials from the inside using high-frequency waves, and the weld bar refers to a mold that applies pressure for welding in the device. In addition, EVA with low vinyl acetate content (hereinafter referred to as low VA)
Containing EVA) does not stick to the weld bar during high-frequency welding, but
Since the amount of internal heat generation is small, it is necessary to take a long time for welding, which reduces work efficiency. Furthermore, although low VA-containing EVA has good abrasion resistance and scratch resistance, it has the drawback of lacking flexibility. The present invention was made in view of the above circumstances, and provides a resin-coated base fabric that has good surface abrasion resistance and scratch resistance, is highly flexible, and has good workability, especially workability and weldability during high-frequency welding. The purpose is to "Means for Solving the Problems" In the present invention, a surface layer made of EVA containing 5 to 15% by weight of vinyl acetate, and a surface layer made of EVA containing 18 to 30% by weight of vinyl acetate.
The solution was to use a resin-coated base fabric having at least two layers as a coating layer, including an inner layer made of EVA containing vinyl acetate. ``Effect'' First, in terms of processability, the inner layer is made of high VA-containing EVA.
As a result, the amount of internal heat generated during high-frequency welding is large, so when welding a resin-coated base fabric,
Good welding strength can be obtained in a short time. In addition, by making the surface layer EVA with low VA content, welding to the weld bar is prevented during high-frequency welding, resulting in good workability. Next, in terms of physical properties, the surface hardness is increased by making the surface layer of EVA with low VA content.
Improved surface wear resistance and scratch resistance, and high VA inner layer
By containing EVA, it becomes a flexible resin-coated base fabric. Hereinafter, the resin-coated base fabric of the present invention will be explained in detail. The resin-coated base fabric of the present invention has a surface layer made of EVA containing 5 to 15% by weight of vinyl acetate;
This is a resin-coated base fabric characterized by having at least two layers as a coating layer, including an inner layer made of EVA containing % by weight of vinyl acetate. Here, if the vinyl acetate content of the EVA in the surface layer is less than 5% by weight, the hardness of the surface layer becomes too high and the welding strength decreases. If it exceeds 15% by weight, welding to the weld bar becomes severe during high-frequency welding, resulting in poor workability. In addition, if the vinyl acetate content of the EVA in the inner layer is less than 18% by weight, the amount of internal heat generated during high-frequency welding will be low and welding will take time, and the flexibility of the resin-coated base fabric will be impaired. If it exceeds 30% by weight, physical properties such as creep properties will deteriorate. Additives such as stabilizers, lubricants, colorants, ultraviolet absorbers, antioxidants, flame retardants, fillers, and the like may be added to the EVA as appropriate. In addition, these EVA
Those having an MFR (melt flow rate ASTM D1238) of 3 to 12 g/10 min are preferably used. The material of the woven fabric of the resin-coated base fabric of the present invention is selected from polyolefins such as polyethylene and polypropylene, nylon, polyester, acrylic resin, etc. depending on the purpose and use. Further, as for the shape of the fibers, long fibers, flat yarns, flat yarns, etc. are preferably used. The weave shape is preferably a plain weave, and a woven fabric in which the weft and warp are entwined is particularly preferred. In the resin-coated base fabric of the present invention, first, as shown in FIG. 1, a woven fabric 1 is laminated with coating layers 2 sandwiching the woven fabric 1. The coating layer 2 is preferably laminated in a molten state. Here, coating layer 2 has a low VA
It consists of a surface layer 3 made of EVA containing EVA and an inner layer 4 made of EVA containing high VA. The coating layer 2 is formed in a molten state using a calender, an extrusion laminator, etc., but the processing time,
Due to the strength of welding between each layer, it is preferably formed using a multilayer extrusion laminator that can simultaneously melt and extrude multilayer resins. Although FIG. 1 shows the coating layer 2 provided on both sides of the woven fabric 1, the coating layer 2 may be provided only on one side of the woven fabric 1. Moreover, the thickness of the surface layer 3 is preferably 25 to 100 μm, and the thickness of the inner layer 4 is preferably 75 to 300 μm. Further, the thickness of the resin-coated base fabric used in the multilayer flexible container is preferably 0.5 to 1.1 mm in consideration of its mechanical strength and waterproof properties. "Examples" The present invention will be described in more detail below with reference to Examples. Example As the surface layer of the coating layer, Showa Denko Co., Ltd.'s SHOREX EVA DL19-8 (VA content 10% by weight, MFR=
8.5g/10min), and Evaflex EV-260 manufactured by Mitsui-Dupont Polychemical Co., Ltd. was used as the inner layer.
(VA content 28% by weight, MFR = 6.0g/10min), these were extruded in a multilayer laminator, 1150 denier flat yarn was used for the warp, 2700 denier flat yarn was used for the weft, and the weft was changed to warp 2. Intertwined with books,
After forming a coating layer by melt extrusion on one side of a so-called leno weave woven fabric, a coating layer is formed on the other side using the same method as described above, thereby forming a resin-coated base having coating layers on both sides of the woven fabric. Formed a cloth. The thickness of one side of the above coating layer is 270 μm, and the ratio of the surface layer to the inner layer is:
The surface layer was 25 and the inner layer was 75. The thickness of the resin-coated base fabric after welding molding was about 1 mm. (Sample A) Comparative example As the coating layer, Showa Denko Co., Ltd.'s Shorex
EVA, FL14-1 (VA content 19%, MFR=3.7
g/10 min), and a resin-coated base fabric was formed in the same manner as in the example. Note that the thickness of the coating layer and the thickness of the resin-coated base fabric were the same as in the examples.
(Sample B) Table 1 shows the tensile strength, tensile elongation, tearing strength, welding strength, yarn pull-out resistance, and bending hardness of the example (sample A) and comparative example (sample B) in the warp direction and weft direction, respectively. The results are shown below. The tear strength was measured by the single tongue method. In addition, as bending hardness, the force when a resin-coated base fabric of a constant width was bent at an angle of 15 degrees was measured using the Taber stiffness tester method. The smaller this value is, the more flexible it is. Table 2 shows the results of testing the resistance to rubbing in the Examples and Comparative Examples in the warp and weft directions by varying the load and the number of times of rubbing. The test method was conducted in accordance with JIS Z-1651, and a Scotto kneading tester was used as the testing machine. The test conditions were a kneading speed of 120
times/min, round trip distance 50mm, chuck distance 25mm
And so. ○ shown in the table indicates that there was no abnormality, △ indicates that a slight abnormality occurred, and × indicates that an abnormality occurred. Table 3 shows the test results for the surface heat resistance of the resin-coated base fabrics of Examples and Comparative Examples.
The symbols in the table are for changing the temperature from 80℃ to 95℃,
The results of observing the surface condition are shown, with ◯ indicating no adhesion, △ indicating a slightly sticky state, and × indicating a sticky state. Table 4 shows the measurement results of the high frequency characteristics of the examples and comparative examples. The dielectric loss factor shown in the table is a value given by dielectric constant (ε) x dielectric loss tangent (tan δ). The dielectric loss factor is a value related to the amount of internal heat generated during high-frequency welding, and the larger the value, the greater the amount of internal heat generated. Table 5 shows the state of adhesion to the weld bar during continuous use of the high-frequency welders of Examples and Comparative Examples in terms of the number of times of continuous use.

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[Table] As is clear from the bending hardness in Table 1 and Tables 2 and 3, this example had good flexibility, rubbing resistance, and surface heat resistance. Furthermore, as is clear from Table 4, the dielectric loss factor of the example was nearly 1.5 times greater than that of the comparative example. This shows the large amount of internal heat generated in the example. Furthermore, as is clear from Table 5, this example had good workability during high-frequency welding. "Effects of the Invention" As explained above, the present invention has a surface layer made of EVA containing 8 to 15% by weight of vinyl acetate, and 18% by weight of vinyl acetate.
Since it is a resin-coated base fabric characterized by having at least two layers as a coating layer, including an inner layer made of EVA containing ~30% by weight of vinyl acetate,
By providing low VA content EVA on the surface layer, the surface properties such as surface abrasion resistance and heat resistance are improved, and by providing high VA content EVA on the inner layer, flexibility is improved and it is possible to use high-frequency welding. Internal heat generation has increased. In other words, the resin-coated base fabric of the present invention has a long service life due to improved surface properties such as abrasion resistance, is flexible, and has good surface heat resistance, making it suitable for high-frequency welding. It is a resin-coated base fabric that can be used continuously for long periods of time, and can be processed for short periods of time or with low output because it generates a large amount of internal heat. Therefore, the resin-coated base fabric of the present invention has the advantage of long life, flexibility, and ease of processing.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a resin-coated base fabric after lamination with molten resin.

Claims (1)

[Claims] 1 A surface layer made of ethylene-vinyl acetate copolymer containing 5 to 15% by weight of vinyl acetate;
A resin-coated base fabric comprising at least two layers as a coating layer, including an inner layer made of an ethylene-vinyl acetate copolymer containing % by weight of vinyl acetate.