JPH0443782B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing tarpaulin. Traditionally, tarpaulins have been made from woven fabrics made of synthetic fibers such as polyamide, polyester, and polyvinyl alcohol, that is, so-called synthetic woven fabrics, and the surface of which has been coated with polyvinyl chloride (PVC) or rubber by calendering or dry laminating. It was manufactured by applying a coating such as However, in the case of these tarpaulins, a large amount of plasticizer is mixed in to improve the thermal stability in the drawing process and the thermal stability, physical properties, flexibility, etc. of the product, and as a result, the plasticizer bleeds. Various problems were observed regarding the hygiene of the contents. For this reason, the coating material was changed from PVC and rubber to ethylene vinyl acetate copolymer (EVA), and other synthetic fiber base fabrics such as polyamide, polyester (PET), and polyvinyl alcohol were used as before.
Products manufactured by a calendar method or a dry lamination method have been proposed. In this case, the problem of hygiene is improved, but when molding with EVA by the calendar method, the anchoring effect of single fibers is not fully demonstrated because the molding is done at a low temperature, and in the case of dry lamination, it is cheap, easy, and good. For this reason, problems occurred in terms of seal welding creep properties, peel strength, etc., and the product was not satisfactory in terms of light weight and price. In addition, the use of polyolefin flat yarn cloth made of polypropylene (PP) or high-density polyethylene (HDPE) for conventional PVC tarpaulins to reduce weight and cost has been considered and considered, but problems caused by heat during the cloth-spreading process have been considered. There is,
In addition, there were problems such as a decrease in the strength of the base fabric and cutting during high-frequency sealing, so it was not used. The present invention solves these problems,
A multifilament made of isotactic polypropylene with a tacticity (expressed as extraction residue (wt%) with boiling n-heptane) of 96 or more and a single fiber fineness of 25 denier or less is used for the warp and/or weft. A mesh fabric is used as a base material, and an ethylene vinyl acetate copolymer having a vinyl acetate content of 10 to 30% is melted on at least one side of the base material within a temperature range of 220 to 290°C to form a lamination (hereinafter referred to as fused laminate). The present invention relates to a method for producing a tarpaulin characterized by: In the present invention, the polypropylene resin used for the mesh fabric base material (base fabric) is isotactic polypropylene, and its tactility is 96%.
% or more is essential. If it is less than this, in the tarpaulin of the present invention, not only will the strength decrease after high-frequency sealing be large, but also problems will occur in welded part creep and tarpaulin creep, problems will arise in the practical properties of the tarpaulin, and furthermore, the base fabric will deteriorate during the coating process. There is a problem of heat shrinkage change. Regarding the molecular weight and molecular weight distribution of this polypropylene, MFR (melting index), which is a guideline for molecular weight, is 3 to 15g/10min (the same applies hereinafter), and MLMFR/MFR (melting index under 10Kg load/2.16), which is a guideline for molecular weight distribution.
Kg load melting index (measured at 230°C) is preferably 13 to 20. At MFR3 or less, there is no problem in terms of strength and creep property, but there are problems in terms of spinnability and drawability, and at MFR15 or more, strength, creep property,
There is a problem with spinnability due to yarn wobbling. or
If the MLMFR/MFR is less than 13, there will be problems in the production of PP resin and in spinability due to yarn wobbling, while if the MLMFR/MFR is 20 or more, there will be problems in terms of strength and stretchability. It is important that the isotactic polypropylene multifilament used in the present invention has a single fiber fineness of 25 denier or less. That is, in the case of a filament of 25 denier or more, the contact area with the EVA coating is small, and there is a problem in the adhesion between the base fabric and the EVA coating, resulting in extremely poor peel strength, welding creep, etc. Naturally, in the present invention, the single fibers are twisted or coated with a sizing agent to prevent them from coming apart, but the single fibers may be bundled by any method and used as yarn. In the present invention, polyolef interpolin is produced using a mesh fabric as a base material, which is formed by using the polypropylene multifilament as one or both of the warp and weft. In this case, the number of mesh fabrics is not limited, but
In the case of plain weave, it is preferable to insert 10 threads/inch to 30 threads/inch. In other words, if the number of drives is 10 or less/inch,
There is a problem that the eyes are easily misaligned. On the other hand, the number of drives
If it is more than 30 lines/inch, the mesh will become narrower.
The bridging effect of the EVA coating resin layer disappears, causing problems in terms of removability. In addition, in the case of a mesh weave made of warp threads, welding creep in the tarpaulin warp direction is very good, and there are advantages such as no misalignment of the base fabric. In this case, the number of threads to be driven is preferably 5 to 15 threads/inch from the viewpoint of weavability and mesh spacing. In the present invention, the EVA coated on at least one side of the base fabric must have a vinyl acetate content of 10 to 30%;
If it is less than 10%, problems will occur with high frequency sealing properties, and if it exceeds 30%, problems will occur with blocking, welding creep, etc. Further, the MFR of EVA is not particularly limited, but the lower the MFR, the better the physical properties such as peel strength. However, if it is too low, there will be problems in the lamination process, so from this point of view, MFR of 1 to 20 is preferable. In the tarpaulin of the present invention, when EVA is laminated to the mesh fabric base fabric obtained above,
It is essential to melt-laminate at a high temperature of 220-290°C, preferably 240-270°C. In other words, by melt laminating, the EVA resin enters the woven fibers that are bundled with 25 denier or less using twisting and binding agents.
The single fiber itself has a so-called anchor effect and connects with the base fabric yarn.
The adhesiveness of the EVA layer is improved, and the bridge effect of the mesh weave further increases the adhesiveness. Conventionally, in the case of the calendar method using EVA, it is 120 ~
It can only be formed at 150℃, and the anchor effect of single fibers cannot be fully demonstrated, and in the case of dry lamination, PP
For EVA, there was no cheap, simple, and good processing agent. If the above melt lamination temperature is below 220℃, the adhesion between the base fabric and EVA will be poor, and the tarpaulin peel strength will decrease.
There are problems with welding creep, etc., and there are also problems with lamination workability. On the other hand, the melt lamination temperature is
At temperatures above 290°C, EVA resin decomposes, causing problems with adhesion and workability. Next, the present invention will be explained using Examples and Comparative Examples. The measurement methods for various test items used in the examples are as follows. (1) Welding strength (Kg/3cm) Using Seidensha's high-frequency welder KW2000, each sample was welded for 12 seconds at an output of 2KW and a welding pressure of 2.5Kg/cm ² . The length of the overlapped part is 50m/m,
Among them, the welding width is 30m/m. Also, the distance between the chucks is 200m/m, and the pulling speed is 200mm/min. (2) Welding creep Measured by the method shown in Figure 1. That is, a test piece 3 having a weld portion 2 is suspended from a base 1, and a load 4 is applied to the test piece 3 to measure weld creep. The measurement conditions are as follows. Weld width 30m/m Width length 60m/mL Sample length 120m/mL 40Kg load, left at 30℃ for 48 hours, then left at 40℃ for 24 hours, and measured residual strength. In addition, in the following examples, the strength of cutting and breaking in the middle is also shown. (3) Thread withdrawal resistance (Kg/2 yarns) As shown in Figure 2, make three notches 5 on the sample, and measure the yarn pullout resistance by pulling the sample left and right as shown by the arrows in the figure. The other numbers in the figure indicate dimensions, and the unit is mm. Moreover, the tensile speed was 200 mm/m. (4) Peel strength The test piece having the welded portion 6 was pulled from the left and right sides in the manner shown in Figure 3, and the peel strength was measured.
The measurement conditions are as follows. Welder width 30mm Length 30mm Distance between chucks 200mm Tensile speed 200mm/min (5) Tear strength Compliant with JIS Z1651. By single tongue method. (6) Tensile strength Compliant with JIS Z1651. Example 1 Isotactic polypropylene with MFR of 8.5, MLMFR/MFR of 14, and tacticity of 97.0% was extruded using a 40 m/mφ extruder with a 1.5 m/mφ125 hole nozzle at a temperature of C ₁ C ₂ C ₃ C ₄ nozzles 200 230 260 290 The undrawn yarn was spun at 290°C, the spinning speed was 200 m/min, and the cooling air temperature was 18°C, and then the undrawn yarn was drawn using a hot roll drawing machine at a drawing temperature of 130°C and a drawing speed of 200 m/min.
Stretched 8.74 times in m, 65 ^F 1000 denier single yarn fineness
I got a 15 denier multifilament. There were no problems in spinning or drawing, and the strength of the obtained multifilament was 8.84 g/d. The multifilament obtained above was used for the warp and weft, and was woven into a plain weave base fabric with a number of threads of 17 x 17 threads/inch using a 110-inch loom manufactured by Toyota Sulzer.
The base fabric has a vinyl acetate content of 18.3% and an MI of 3.5g/
Molding speed of 10 minutes ethylene vinyl acetate 10m/
Adhesive on both sides (300μ on one side) at min. thickness 0.85m/m
obtained a tarpaulin. As shown in Table 1, welding creep is good,
A tarpaulin with good peel strength, thread pull-out strength, and welding strength was obtained. Example 2 Two multifilaments used in Example 1 were bundled and used as the weft, and PP/HDPE 1500 denier flat yarn manufactured by Konyoshi Kako Co., Ltd. was used as the warp.
A 110-inch loom with a karami device made by Toyota Sulzer was used to make a karami mesh base fabric with 10 x 2 warp threads/inch and 8 weft threads/inch, and EVA was laminated to this base fabric under the same conditions as in Example 1. , thickness 0.92
A tarpaulin of m/m was obtained. As shown in Table 1, a tarpaulin with particularly good longitudinal welding creep and other very good physical properties was obtained. Comparative Example 1 A multifilament of 30 ^F denier and 40 denier single yarn fineness was obtained under the same conditions as in Example 1. The strength of the obtained multifilament was 8.2 g/d. This multifilament was used for the warp and weft, and was woven on a plain weave base fabric with a number of threads of 17 x 17 threads/inch on a Toyota Sulzer 110-inch loom, and the base fabric had a vinyl acetate content of 18.3% and an MI of 3.5 g/inch. 10-minute ethylene vinyl acetate copolymer manufactured by Mitsubishi Heavy Industries, Ltd.
Using a 120m/mφ extruder die width 1600m/m laminator, molding speed 10 at resin temperature 260℃
Adhesive on both sides at m/min (300μ on one side), thickness 0.85
A tarpaulin of m/m was obtained. As shown in Table 1, although there was no problem with tensile strength, welding creep was poor, and problems were observed with peelability and thread pullability. Comparative Example 2 Isotactic polypropylene with MFR 8.7, MLMFR/MFR=20.5, and tacticity 93.1% was spun under the same conditions as in Example 1, but at a draw ratio of 7.3 times. There were no problems with spinning or drawing. Strength is 5.8
It was g/d. A tarpaulin with a thickness of 0.82 m/m was obtained in the same manner as in Example 1. As shown in Table 1, tensile strength,
Problems are seen in terms of weld creep. Comparative Example 3 Example 1 except that the resin temperature during laminator was 190°C and the molding speed was 5 m/min.
A tarpaulin was obtained in the same manner. As shown in Table 1, welding creep was worse than in Example 1, and problems were observed in peelability and thread pullability. Comparative Example 4 Various physical properties were measured for a commercially available tarpaulin made by adhering EVA to a polyester base fabric. As shown in Table 1, problems with weld creep were observed.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a welding creep test, FIG. 2 is an explanatory diagram of a thread pull-out resistance test, and FIG. 3 is an explanatory diagram of a peel strength test. 1... Base, 2... Weld part, 3... Test piece, 4...
Load, 5...notch, 6...welder part.

Claims (1)

[Claims] 1 Multifilament made of isotactic polypropylene with a tactility of 96 wt% or more and a single fiber fineness of 25 denier or less is used as the warp and/or weft, and the number of threads is 10/inch to 30/inch for plain weave. inch, 5 for Karami weave
~15 pieces/inch of mesh fabric is used as a base material, and at least one side of the base material has a vinyl acetate content of 10 to 30
% ethylene vinyl acetate copolymer within a temperature range of 220 to 290°C and laminated.