JPH0546911Y2 - - Google Patents

Description

[Detailed explanation of the idea]

<Industrial Application Field> The present invention relates to a sheet for a flexible container filled with synthetic resin or the like. <Prior Art> Currently, flexible containers are made from sheets made by laminating soft polyvinyl chloride resin on both sides of a fabric and bonding them with a welder. These containers are low cost and have excellent weldability, abrasion resistance, and scratch resistance, but the sheet has poor thread pull-out strength at high temperatures, so threads can easily pull out and damage the container, especially at the welder joint. This problem is occurring. Furthermore, if a base fabric with a low porosity is used, it is difficult to identify the items stored in the container from the outside, which is inconvenient in terms of management. Furthermore, if the resin remains in the container after the synthetic resin is discharged from the container, it becomes contamination, which impedes subsequent processes and poses a quality problem. <Problems to be Solved by the Invention> The first object of the present invention is to provide a sheet for a flexible container that has transparency and leaves no residual resin inside the container after the resin is discharged. Modern synthetic resin manufacturing factories are now producing dozens of brands of synthetic resins, each with different hues and shapes, due to the trend toward high-mix, low-volume production. In order to store and manage these synthetic resins in containers, it goes without saying that it would be convenient if the color, shape, and amount of resin in the container could be identified from outside the container. To achieve this, by laminating both sides of a coarse-grained base fabric with transparent soft polyvinyl chloride film, the inside of the container can be observed through the openings of the base fabric. On the other hand, if the inner surface of a container made of transparent soft vinyl chloride film is smooth, the coefficient of surface friction will be high. Resin tends to stick to the inner surface and remain. Generally, in order to reduce the amount of residual resin, the inner surface of the container is appropriately roughened. However, as the degree of surface roughening increases, transparency decreases, making it difficult to observe the inside of the container from the outside. In this case, another method to make it difficult for the resin to adhere to the inner surface of the container is to coat the surface of the film with an ultraviolet curable paint and harden the surface by irradiating it with ultraviolet rays, then use the film as the inner surface of the container. Alternatively, it may be possible to use a film made by reducing the amount of plasticizer in the film to make the film itself hard for the inner surface of the container, but this may deteriorate the flexibility of the container or reduce its weldability. A second object of the present invention is to provide a flexible container that has excellent resistance to string pulling out at high temperatures. At a synthetic resin manufacturing plant, before filling containers with synthetic resin powder or pellets, the synthetic resin must be cooled to a temperature that the container can withstand. In this case, if the synthetic resin can be packed into containers while still at high temperature, the cost for cooling the factory can be significantly reduced. Additionally, flexible containers that are stacked in the hold of a ship sailing in the far southern oceans or stored outdoors in the summer heat up significantly, often resulting in bag breakage. In this way, bag breakage accidents occur at high temperatures for long periods of time under high loads because the synthetic resin layer of flexible container sheets softens due to high temperatures, and the thread pulling strength between the synthetic resin and the threads is reduced. This is because the so-called "thread shedding phenomenon" occurs between the synthetic resin and the thread at the welder part. As a result of various studies in order to simultaneously satisfy the first and second objectives above, the inventor has developed a material that does not impair the flexibility of soft vinyl chloride, has high thread pulling strength at high temperatures, and has good transparency. We were able to find a sheet that was well balanced against contamination. <Means for Solving the Problems> The present invention is characterized in that the polyvinyl chloride paste is impregnated even between the fibers, and at the same time, the fiber surface is coated with the paste. To provide a flexible container sheet comprising a synthetic fiber base fabric laminated with transparent soft polyvinyl chloride film on both sides thereof, the sheet having minute irregularities on one surface of the sheet. FIG. 1 is an enlarged sectional view of the sheet of the present invention.
1 is a warp or weft made of multifilament or spun yarn impregnated with polyvinyl chloride paste. The base fabric is composed of these warp threads. 2 and 2' indicate soft vinyl chloride films lined on both sides of the base fabric. As shown,
3 shows a filament or fiber in which vinyl chloride paste penetrates between the fibers and the paste coats the fiber surface. This paste 4 is a soft vinyl chloride film 2,
2', the base fabric, paste, and film are integrated into a sheet. The sheet has minute irregularities 5 on one surface. In contrast, in conventional sheets, the soft vinyl chloride films 2, 2' shown in FIG. 2 only partially penetrate into the gaps between the filaments or fibers 7. 2 and 2' are integrated by being fused together in the form of a bridge through the gap between the warp or weft threads 6. Conventional sheets for flexible containers made in this way have a weak pull-out strength for the threads between the vinyl chloride and the threads, so it is easy for the threads to "come off" between the vinyl chloride and the threads in the welded part. However, the container is easy to break at the welder part. In the present invention, a synthetic resin fiber base fabric made of multifilament or spun yarn impregnated with polyvinyl chloride paste is used, and there are two methods for manufacturing the base fabric. That is, there is a method in which a base fabric is woven using a multifilament or spun yarn impregnated with vinyl chloride paste, and a method in which a base fabric is woven using a multifilament or spun yarn and then impregnated with polyvinyl chloride paste. It doesn't matter which one. In the present invention, a synthetic fiber base fabric made of multifilament or spun yarn, preferably impregnated with vinyl chloride paste, is heat-press treated with a heat roll, and the intersection of the warp and weft is fixed by the heat-press treatment, and , the warp and weft cross sections are flattened into an elliptical shape. The sheet of the present invention is preferably prepared by heat-sealing a soft vinyl chloride film to both the front and back surfaces of the base fabric after or without heat and pressure treatment as described above. The vinyl chloride paste and soft vinyl chloride film used in the present invention preferably have a high degree of polymerization in order to increase the softening point. Further, in order to raise the softening point of the soft vinyl chloride film, it is desirable to take measures such as adding nitrile rubber, using an ester plasticizer, or epoxy soybean oil. Further, the base fabric used in the present invention is made of synthetic fibers such as polyester, nylon, vinylon, etc. The porosity of the base fabric is generally 20 to 70%. If it is less than 20%, it will be difficult to distinguish the contents inside the container through the eyes of the base fabric, and if it exceeds 70%, not only will the strength of the container decrease, but it will also be difficult to maintain the shape of stacked containers. Further, the method of adhering the soft vinyl chloride film of the present invention to both sides of the base fabric may be a swivel lamination method or a topping method. Next, one side of the vinyl chloride film laminated on both sides of the base fabric can be roughened by subjecting the sheet to heat-pressure treatment using an ordinary embossing roll. The sheet obtained as described above is cut to an appropriate size, and then bonded into a bag shape using, for example, a welder, with the finely uneven surface forming the inner surface of the bag to form a flexible container. Hereinafter, the present invention will be explained in detail based on examples. <Example> 3 polyester filaments 1000d/150 pieces
The sheets are aligned, immersed in a polyvinyl chloride paste solution (average degree of polymerization 800, plasticizer DOP 100 parts by weight), dried at approximately 170°C after draining, and woven into a plain weave.
Use as base fabric. The weaving density at this time is both warp and weft.
17 pieces/10cm. Next, by heat-pressing the base fabric with a heat roll at about 170°C, the intersection of the warp and weft is fixed, and the ratio of the long axis and short axis of the cross section of 1000d/150 threads//3 is fixed. The ratio is approximately 15:1, resulting in a flat oval shape.
The porosity of the base fabric is 23%. A soft vinyl chloride film with a thickness of 0.37 mm (average degree of polymerization 2300, approximately 5 parts by weight of nitrile rubber, 70 parts by weight of polyester plasticizer, approximately 8 parts by weight of epoxy soybean oil, approximately 2 parts by weight of stabilizer) is coated on both the front and back surfaces. , ultraviolet absorber (approximately 1 part by weight) are laminated, heat-sealed, and embossed on one side. In this case, the test was conducted using two types of embossing rolls, A and B, with different degrees of embossing. These were named Examples 1 and 2. Next, a plain roll with a smooth surface was used in place of the embossing roll described above. This was designated as Comparative Example 1. Furthermore, as Comparative Example 2, a transparent soft vinyl chloride film with a thickness of 0.40 mm (degree of polymerization 1300, DOP 70 weight Department)
were laminated and heat-sealed, and one surface was embossed using embossing roll A. The obtained sheet has strong thread pulling strength, transparency,
The coefficient of static friction of the surface with minute irregularities was also measured. (1) Thread pull-out resistance The pull-out resistance of the thread is as shown in Figure 3.
cm, approximately 8 cm from the top of small piece 8 of a sheet approximately 18 cm long
Insert the upper cut 9 so as to leave the two threads in the center at the position, then cut the lower cut 10 so as to cut the two threads at a position 3 cm from there, and use it as a sample. Grasp the sample at the top cut 9 and bottom cut 10 and move it up and down using the autograph at a speed of 200 mm/60 seconds.
Stretch it in a constant temperature box at 80℃. The sample with the two threads 11 pulled out by tension is as shown in FIG. The load on the autograph until two threads are pulled out is read, and the maximum load is named the thread pullout strength, expressed in Kg/2 threads. (2) Transparency Total light transmittance was measured using HGM-2K manufactured by Suga Test Instruments Co., Ltd. (3) Surface static friction coefficient Measured against a polyethylene plate in accordance with ASTM D1894. Test dimensions: 50 x 50 mm Thread load: 200 gf Test machine capacity: Load cell type/Kgf Test room temperature humidity: 22°C x 65% Next, using the obtained sheet, turn the surface with minute irregularities into the inner surface of the bag. In this way, the diameter is 1000mmφ,
Make a flexible container with a height of 1160mm and fill it with about 500 pieces of granular polyethylene (about 3mmφ).
Kg filling. Assuming that three containers are stacked, a load of 3 tons is placed on top of the polyethylene filling bag.
Take time. Open the outlet of the container and shake the container to drain the polyethylene. Next, a person enters the container for measurement and weighs while dropping any remaining polyethylene inside the container. Table 1 summarizes the above measurement results.

[Table] As shown in Examples 1 and 2, when the coefficient of static friction of the sheet decreases due to minute irregularities on the sheet surface, the transparency of the sheet naturally decreases, and the amount of residual resin in the container decreases. Decrease. The relationship between the coefficient of static friction of the sheet, the transparency of the sheet, and the amount of residual resin in the container is plotted in a graph as shown in FIG. From Figure 5, the static friction coefficient of the uneven surface of the sheet to reduce the amount of residual resin in the container to 0 is 1.4 or less.
The transparency of the sheet is 34% or less. Therefore, when using a base fabric with a porosity of 20 to 70%, the static friction coefficient of the surface with minute irregularities is 1.5 or less,
It is desirable that the transparency of the sheet is 35% or less. In addition, as shown in Examples 1 and 2, the thread pulling resistance value is 10 Kg/2 or more at 80°C, preferably 15 Kg/2
A book or more is preferred. Next, Comparative Example and Example are compared. Comparative Example 1 has a high coefficient of static friction on the sheet surface and residual resin inside the container is observed, and Comparative Example 2 has extremely low thread pulling resistance compared to the Example, and the container In order to reduce the amount of residual resin in the sheet to 0, the coefficient of static friction of the sheet is
When it is set to 0.91, the transparency becomes extremely low to 7.0%, partly due to the relationship with the void area, making it difficult to see through. (Effect of the invention) The polyvinyl chloride paste is impregnated between the fibers, and at the same time, the fiber surface is covered with the paste, and the intersection points of the warp and weft of the base fabric are bonded, and the laminated soft Since the vinyl chloride film and the paste are fused and integrated, the pulling strength of the thread between the thread and the vinyl chloride at high temperatures is increased. Therefore, it is a suitable sheet for containers that are filled with synthetic resin or the like and stored or transported at high temperatures. In addition, the status of the resin inside the container can be observed from the outside, which is convenient for management, and there is no resin left inside the container after the resin is discharged.
This sheet is suitable as a container. Furthermore, since soft vinyl chloride film is used for the laminate, it is flexible and can be welded.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of the sheet of the present invention,
Figure 2 is an enlarged sectional view of a conventional sheet;
The figure shows the state of the sample (plan view) after measuring the thread pulling strength, and FIG. 4 shows the state (plan view) of the sample after measuring the thread pulling strength. FIG. 5 is a graph showing the relationship between the static friction coefficient of the sheet, the transparency of the sheet, and the amount of residual resin in the container. 1... Warp or weft made of multifilament or spun yarn impregnated with polyvinyl chloride paste, 2,2'... Soft vinyl chloride film,
3... Filament or fiber impregnated with polyvinyl chloride paste, 4... Vinyl chloride paste, 5... Fine irregularities on the sheet surface, 6... Warp or weft made of multifilament or spun yarn, 7... Filament or fiber , 8...Small piece of sheet, 9...Top cut, 1
0... Lower cut, 11... Thread pulled out.

Claims (1)

[Claims for Utility Model Registration] 1. Made of synthetic fiber with a porosity of 20 to 70%, consisting of multifilament or spun yarn in which polyvinyl chloride paste is impregnated up to the fibers and the surface of the fibers is coated with the paste. 1. A flexible container sheet comprising a base fabric laminated with transparent soft polyvinyl chloride film on both sides thereof, the sheet having minute irregularities on one surface of the sheet. 2. The sheet for a flexible container according to claim 1, which is a utility model registration, characterized in that the sheet has a transparency of 35% or less and a coefficient of static friction of the surface having minute irregularities of 1.5 or less. 3 Utility model registration claim 1 characterized in that the pulling strength of the thread is 10 kg/2 threads or more at 80°C
The flexible container sheet described in item 1 or 2.