JPH043295B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to polyolef interpolins. Conventionally, tarpaulins are made of a multifilament plain-woven mesh fabric made of nylon, polyester, etc., and a coating of flexible synthetic resin such as polyvinyl chloride or rubber is pasted on the front or front and back sides of the fabric by calendering or laminating. I was wearing it and forming it. However, conventional tarpaulins based on plain-woven mesh fabrics suffer from not only appearance problems but also problems such as misalignment during the weaving of the base material or coating formation process, which causes wrinkles in the product. Depending on the alignment of the eyes,
It has the disadvantage that it cannot fully demonstrate its strength as a base material that bears most of its strength, and that the strength varies greatly. Therefore, various methods for preventing misalignment have been proposed, but none have yet been found to be good and this is considered to be a major problem with tarpaulins. In addition, conventional tarpaulins have low thread pull-out resistance between the coating resin and the base material, and perhaps because of this, they have the disadvantage of low weld creep and weld peel strength, which are required for tarpaulins. Improvements in material resin composition, etc. are being studied. According to the report, the resin used for the base material of tarpaulins needs to be able to withstand high temperatures during coating processing and high-frequency sealing, and conventionally, nylon or polyester with a high melting point has been used for the base material. ,
It has been thought that resins with relatively low melting points, such as polyolefins such as polypropylene and high-density polyethylene, cannot be used. However, according to the studies of the present inventors, as in the present invention, a Karami mesh fabric is used as a base material, and an ethylene vinyl acetate copolymer (hereinafter referred to as EVA) with a vinyl acetate content of 10 to 30% is used as a skin material. In this case, by using highly drawn polyolefin filaments such as polypropylene (PP) or polyethylene (PE), we can take advantage of the advantages of polyolefin, which is lightweight, inexpensive, and easy to spin, and can also be high-frequency sealed to prevent welding creep. The present invention was completed based on the discovery that a tarpaulin with high welding and peeling strength could be obtained. That is, the present invention was completed as a result of intensive studies in view of the above circumstances, and it is based on polypropylene 30~
After melt-extruding a resin composition consisting of 90% by weight and 10-70% by weight of high-density polyethylene, it is strongly stretched to an overstretched state of 10 times or more, and then pressed with an embossing roll to obtain a flatness ratio of 600 to 3000 deniers. is 1:2~
A flat monofilament with a ratio of 1:10 is used as the warp,
5-15 consisting of highly drawn polyolefin threads of 1,200-6,000 deniers as the weft and kalami weave as the warp.
Using a mesh fabric with 1/2 inch stitching as the base material,
Vinyl acetate content on the front or/and back side of the base material
A tarpaulin with 10 to 30% by weight ethylene vinyl acetate copolymer pasted over 0.2mm on one side that has high weld creep and weld peel strength, is capable of high frequency sealing, and has excellent performance with light weight and high strength. Exists. The fiber shape of the warp threads used in the present invention is a flat monofilament which has high strength, has minimal weave deterioration during weaving, is free from weaving troubles, and has good adhesion to the skin material. This flat yarn is made by melt-extruding a resin composition of PP and PE in a specific ratio, strongly stretching it at high temperature to an overstretched state, and then embossing it. In the present invention, a resin composition of PP and PE is used, and flattened yarns that have been strongly stretched and then embossed are used for the following reason. That is, by doing the above, the PE component and PP
Microphase separation of the components results in microfibrillated flexible monofilaments. In addition, since the surface is microfibrillated, minute fluff is generated, and this fluff exerts an anchoring effect with the coating layer during film formation, improving the adhesion between the base material and the skin material. This is because it increases In addition, since it is embossed, the surface of the monofilament has irregularities, which also creates an anchor effect with the coating, and the presence of these irregularities can also contribute to preventing misalignment of the base material. It is. Furthermore, in order to obtain a flexible monofilament with fluff as described above, it is essential to draw it strongly to an overdrawn state of 10 times or more, and if the drawing ratio is low, the monofilament becomes microfibrillated. cannot be obtained. The temperature during stretching is preferably 80°C or higher, preferably 95° to 130°C. On the other hand, the composition ratio of the resin composition consisting of PP and PE is as follows. That is, when PE is less than 10% by weight and PP is more than 90% by weight, it is difficult to stretch at a high magnification, and stable operation in an overstretched state after stretching whitening is impossible. On the other hand, if PE is 70% by weight or more and PP is 30% by weight or less, there are problems with creep resistance and strength, and also in this case, stable operation in an overstretched state is difficult. Therefore, the composition proportions are PP30-90% by weight, PE10
~70% by weight is good, and by stretching the composition to an overstretched state, a monofilament with the above-mentioned advantages can be obtained. Any PP or PE may be used, but PP is preferably one with an MFI of 1.0 to 4.0, and PE is preferably high density polyethylene (HDPE) with a density of 0.945 or more and an MFI of 0.3 to 1.5. Next, the reason why flat monofilaments are used for the warp yarns in the present invention is as follows. Multifilament is expensive to spin, and there are many weaving problems due to single thread breakage during karami weaving. In addition, the stretched tape suffers from severe weaving deterioration, making it impossible to obtain the desired strength, and fine-denier (less than 600 denier) monofilament twisted yarns have poor cohesiveness, which causes many weaving problems during karami weaving. Therefore, a thick denier monofilament is used, but in this case, a perfectly round monofilament contains vacuum bubbles during spinning, resulting in reduced stretchability, significantly inferior strength, and lacks flexibility.
The disadvantage is that the thickness of the base fabric due to Karami weaving cannot be made thinner. On the other hand, the above-mentioned drawbacks can be greatly improved with flat monofilaments. The flatness ratio of the flat monofilament is 1:2 ~
It needs to be 1:10. In other words, if the flattening ratio is less than 1:2, the effect as a flat monofilament will be small, and if it is more than 1:10, yarn shaking will be large during monofilament spinning, resulting in problems such as poor drawability and small mesh size. There is a problem that the bridging effect of the coating layer becomes small and the adhesion between the base material and the coating layer is poor. Further, the flat monofilament used has a denier of 600 to 3000. In other words, if it is less than 600 denier, there is a problem in terms of strength, and if it exceeds 3,000 denier, the yarn becomes too hard and poor weaving properties occur.
Another problem is that the obtained base fabric lacks flexibility. In the tarpaulin of the present invention, it is important to use a mesh fabric made of kalami weave. In the case of a tarpaulin using a plain woven base fabric, the creep property itself is not a major problem, but there is a problem that the creep property of the high frequency seal welded part is low. In particular, since the creep resistance of longitudinal welds is important in flexible containers, etc., it is desired to improve the weld creep strength. For this reason, in conventional plain weave tarpaulins, in order to improve this problem, the single filament fineness of the raw fibers has been reduced, the bonding area with the laminate layer resin has been increased, or treatment with a treatment agent has been applied. Improvements have been made at the expense of various physical properties and cost, such as reducing the vinyl acetate content to 10% or less at the expense of high frequency sealing properties, but these have not been sufficient. The kalami woven base fabric according to the present invention dramatically improves this welding creep. That is, the warp weave prevents the weft from shifting due to creep loads, and the welding creep resistance is greatly improved. Furthermore, the base fabric according to the present invention improves the adhesion between the base fabric and the coating. That is, when manufacturing a tarpaulin, the front and back skin materials bite into the grains of the base fabric and bond together, creating a bridge effect and improving peel strength. If there is no mesh and there is no bridging effect, the base fabric and the coating layer will easily separate, causing problems such as welding creep, making it unsuitable for fields such as tarpaulins that require high mechanical properties. Become something. In particular, the bridge effect is essential when forming an EVA coating with high frequency sealing properties on a base fabric such as PP or PE as in the present invention. The spacing between the mesh fabrics made of the Karami weave of the present invention needs to be set at the following number of stitches. Warp threads are rated 5 in terms of welding creep properties, strength, and peelability.
×(2) pieces/inch or more, and preferably 15×(2) pieces/inch or less in terms of weavability and mesh spacing. For the same reason, the number of weft yarns is preferably 5 to 15 yarns/inch. In the present invention, the resin coated on the substrate is an ethylene vinyl acetate copolymer having a vinyl acetate content of 10 to 30% by weight. This makes it possible to obtain a tarpaulin that is lightweight, has good high-frequency sealing properties, and has no hygienic problems due to the migration of plasticizer to the outside. That is, the vinyl acetate content is
If it is less than 10%, there will be problems with high frequency sealing, and 30
If it exceeds %, problems will arise in blocking properties. This coating resin may contain a small amount of additives such as additives that improve high-frequency sealing properties and chlorinated polyethylene, and may also contain commonly used antioxidants, light stabilizers, lubricants, pigments, etc. as appropriate. However, the effects of the present invention will not be impaired. Furthermore, the method of forming the film is not particularly limited. The thickness of the coating layer must be 0.2 mm or more on one side. If the coating layer is less than 0.2 mm, there will be no bridging effect between the front and back of the coating layer, and the peelability and welding creep properties will be significantly reduced. There is also the danger of sparks during high frequency welding. The weft used in the present invention is a highly oriented polyolefin having a density of 1,200 to 6,000 deniers. The shape of the filament is inexpensive, provides high strength, and has little weaving deterioration.
There is no particular problem as long as it has good weavability, but the thickness of the thread should be 1200 to 6000 to balance strength and weavability.
Good denier. The polyolefin resin used for this weft is preferably PP, and PP/
HDPE, PP/LDPE (low density polyethylene),
A blend of PP/EVA may also be used. This is because PP has particularly good creep properties. Also, EVA
When the bundle is 30% or less, preferably 10 to 20%, welding creep and peelability are greatly improved. According to intensive studies by the present inventors, a tarpaulin with excellent longitudinal welding and creep properties can be obtained by using a mesh fabric in which the warp and weft are made of polyolefin resin and the warp is made of kalami weave as a base material. However, when welding creep resistance in the transverse direction is particularly required, weft yarns made of polypropylene split fiber, polypropylene monofilament, or PP
It turned out that it would be better to use a multifilament. This is for the following reason. In other words, the skin material of polypropylene split fibers tends to bite into the finely split fibers and the twists, and the fluff on the surface increases the anchoring effect with the skin material. This is because it increases the adhesive strength with the skin material. This is because the split fiber is very flexible, so it blends well with the warp threads of the karami weave and prevents the base material from shifting. This is because the skin material of polypropylene monofilament strands is easily bitten into the strands of the strands, so that the above-mentioned effects can be obtained. Furthermore, monofilament twisted yarns are particularly suitable where high strength is required. FIG. 1 shows an example of the polyolef interpolin of the present invention. In FIG. 1, 1 is a kalami weave warp, 2 is a weft, and 3 is an ethylene-vinyl acetate copolymer coating. In the present invention, by using the tarpaulin obtained as described above in the longitudinal direction in the circumferential direction of the body of the flexible container, the tarpaulin is lightweight and has high strength.
We have successfully developed a flexible container with excellent welding and creep resistance. 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 2. That is, the measurement conditions for measuring welding creep by suspending a test piece 6 having a weld portion 5 from a base 4 and applying a load 7 to it are as follows. Welding width 30m/m/Width length 60m/mL Sample length 120m/mL 40Kg load, left at 30℃ for 48 hours, then left at 40℃ for another 24 hours, and measured the residual strength (3) Thread withdrawal resistance (Kg/2 yarns) ) Three notches 8 are made on the sample as shown in Figure 3, and the sample is pulled left and right as shown by the arrows in the figure to measure the thread withdrawal resistance. The other numbers in the figure indicate dimensions, and the unit is mm. Moreover, the tensile speed was 200 mm/m. (4) Heat resistance 1Kg/6m ² loads, 70℃ observed for 1 hour for blocking. (5) Peel strength The test piece having the welded portion 9 was pulled from the left and right sides in the manner shown in Figure 4, 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 (6) Tear strength Compliant with JIS Z1651. By single tongue method. (7) Tensile strength Compliant with JIS Z1651. Example 1 Polypropylene (PP) with MFI 2.5g/10min
MI0.8g/10min of high density polyethylene (HD)
A resin composition with a mixing ratio of 70/30 was mixed with a flattening ratio of 1:
The warp yarn is a 1500 denier flat yarn with an aspect ratio of 1:4, extruded through a 2.5 nozzle, stretched 12 times and embossed, and 2500 denier polypropylene split yarn is used as the weft yarn. Toyota Sulzer 110 inch kalami weaving machine is used. Warp thread 10 with sulzer
×(2) threads/inch, Karami mesh base fabric with 8 weft threads/inch, this base fabric has a VA content of 18.0%,
MI3.5g/10 minutes EVA manufactured by Mitsubishi Heavy Industries, Ltd. 120m/
Double-sided adhesion using a mT diamond width 160m/m laminator at a molding speed of 10m/min (300μ on one side)
A tarpaulin with a thickness of 0.92 m/m was obtained. The results are shown in Table 1. The vertical welding strength of this tarpaulin is 214Kg/3cm, and the horizontal welding strength is 169Kg/3cm.
3cm, welding creep is vertical direction after 72 hours of creep
It has a residual strength of 109% and a residual strength of 92% in the horizontal direction, and has less welding creep and less resistance than the comparative tarpaulin.
It is understood that the welding strength, thread pull-out resistance, etc. are very high. Example 2 Same as Example 1 except that polypropylene 2040 denier multifilament manufactured by Chubu Japan Textile Rope Cooperative Association was used for the weft yarn, with a thickness of 0.89 m/m.
obtained a tarpaulin. The results are shown in Table 1. Example 3 The procedure was the same as in Example 1, except that six 380-denier polypropylene monofilaments made by stretching polypropylene with an MFI of 1.5 g/10 minutes to a 7-fold weft were assembled to form a 2280-denier twine (twisted yarn). Got a tarpaulin. The results are shown in Table 1. Example 4 85% by weight polypropylene and EVA for weft yarn
(MI5g/min, vinyl acetate content 15% by weight) A tarpaulin was made in the same manner as in Example 1, except that six 380-denier monofilaments made of a resin composition of 15% by weight were assembled to form a 2280-denier twine. I got it. The results are shown in Table 1. Comparative example 1 With polypropylene (PP) with MFI 2.5g/10min
A composition consisting of a 70/30 mixing ratio with high density polyethylene (HD) of MI 0.8 g/10 min was added to the flattening ratio of 1:2.5.
It is extruded from a nozzle, stretched 12.0 times, and then embossed to make warp and weft yarns of 1800 denier flat yarn with a flatness ratio of 1:4, and vinyl acetate is applied to a plain weave base fabric with the number of yarns: 12 vertically x 12 horizontally. (VA) content
A tarpaulin with a thickness of 0.84 m/m was obtained by pasting ethylene vinyl acetate copolymer (EVA) of 18.3% and MI 3.5 g/10 min. The results are shown in Table 1. The vertical welding strength of this tarpaulin was 127 kg/3cm, the horizontal welding strength was 125 kg/3cm, and the vertical welding creep was cut in the middle of 10 hours. About 13 hours later, it was disconnected.
Also, the thread pulling resistance of this tarpaulin is vertical.
The weight was 15.8Kg/2 yarns, and the width was 16.3Kg/2 yarns. Additionally, problems with misalignment of stitches were observed during weaving and adhesion processing. The data of Comparative Example 1 used was data with relatively few problems of misalignment. Comparative Example 2 In Example 1, the draw ratio of the warp yarn was set to 7 times. The warp threads were stiff, resulting in poor entanglement and poor weaving, and subsequent measurements were discontinued. Comparative Example 3 In Example 1, the warp yarn was spun using a round nozzle, and no stretching was performed. The same results as in Comparative Example 2 were obtained, and subsequent measurements were discontinued. Comparative Example 4 In Example 1, a resin composition consisting of a 92/8 mixing ratio of polypropylene and high-density polyethylene was used for the warp yarn, and no stretching was performed. Similar results to Comparative Example 2 were obtained. Comparative Example 5 A tarpaulin with a thickness of 0.91 m/m was obtained in the same manner as in Example 1, except that the resin composition of the warp yarn was polypropylene/high-density polyethylene = 20/80. The results are shown in Table 1.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of the tarpaulin of the present invention, FIG. 2 is an explanatory diagram of a welding creep test, FIG. 3 is an explanatory diagram of a thread pull-out resistance test, and FIG.
The figure is an explanatory diagram of a peel strength test. 1... Warp, 2... Weft, 3... Coating, 4...
Base, 5... Weld part, 6... Test piece, 7...
Load, 8...notch, 9...welder part.

Claims (1)

[Claims] 1 A resin composition consisting of 30 to 90% by weight of polypropylene and 10 to 70% by weight of high-density polyethylene is melt-extruded, then strongly stretched to an overstretched state of 10 times or more, and then pressed with an embossing roll. The warp is a flat monofilament with a denier and aspect ratio of 1:2 to 1:10, and the weft is a highly drawn polyolefin thread of 1,200 to 6,000 denier, and the warp is a kalami weave with 5 to 15 threads per inch. A polyolefin interpolin made of a woven fabric as a base material and 0.2 mm or more of ethylene vinyl acetate copolymer having a vinyl acetate content of 10 to 30% by weight attached to the front and/or back surfaces of the base material.