JPH0149802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing synthetic resin strings used for binding, handicrafts, packaging, and other textile applications.

(Prior art) Polyolefin-based foamed synthetic resin or the like is melt-extruded using an extrusion molding machine, and a string-like material containing air bubbles inside is then heated and stretched to give parallel micelle molecular orientation in the longitudinal direction. With,
By arranging the spherical bubbles contained therein as flat bubbles along the longitudinal direction and bending and transporting them in a substantially U-shape within the turning device, each string-like material is twisted in opposite directions. Therefore, the inventor of the present invention developed a cord and a method for producing the same by promoting the opening of the flat cell groups and freeing the fibers from fuzzing, etc.
Disclosed in No. 3854.

(Problems to be Solved by the Invention) The above-mentioned conventional string applies a twisting action in opposite directions to the above-mentioned specific string material, so that the flat cells along the longitudinal direction are torn into small pieces to form a fiber-opening structure. However, the part of the finished string that was subjected to the twisting action became extremely weak, and there were problems with its strength. Moreover, according to the above manufacturing method, the micelle molecules are oriented parallel to each other in the longitudinal direction, and there is almost no disturbance in the micelle molecule orientation in the transverse direction. This caused cracking, and although it was a foldable foamed string, it was rigid and had poor expansion and flexibility, making it particularly unsuitable for use in automatic tying machines.

The present invention solves the above-mentioned problems and provides a method for producing a synthetic resin string that can be used in automatic tying machines and the like and has excellent strength, swelling flexibility, and good fastening properties.

(Means for Solving the Problems) In order to achieve the above object, a foamed synthetic resin such as polyolefin resin is melt-extruded into a round bar shape, formed into a string-like material containing air bubbles inside, and then heated and stretched in the longitudinal direction. The spherical bubbles contained therein are aligned as flat bubbles along the longitudinal direction, and then this stretched string-like material has an arc-shaped bottom and a U-shaped circumferential groove. A first pressurizing device includes a gear having a notch in its teeth, and a gear that meshes with the first pressurizing device. Apply pressure in the opposite direction to cause disturbance in the orientation of the micelle molecules in the transverse direction, and form a network-like fiber opening structure through the flat cells, and then use a pressure device having the same structure as the first pressure device. A shaping pressure is applied inward in the transverse direction to the portion that has been unevenly pressurized by the first pressurizer by passing through a second pressurizer, and the unpressurized unevenly pressurized portion is subjected to the first pressurization. A structure was adopted in which the fibers were opened into a net-like structure in the same manner as in the pressure device, and then passed through a shaping and pressure device consisting of a pair of rolls provided with circumferential grooves.

(Example) Fig. 1 is an explanatory drawing showing the method for manufacturing the string of the present invention, and 1 is an extrusion molding machine, in which olefin-based foamed synthetic resin (expansion rate, e.g. 2 to 3 times) such as polyethylene or holypropylene is After being heated and plasticized as a molding material to give it sufficient fluidity, it is extruded from a die into a round bar shape, immediately cooled in a water tank or other cooling device 2, guided to a nip roll, and heated in a heating device 3 to heat the string-like material B. For example, the film is stretched at a stretching rate of 6 to 7 times. By this stretching, the string-like material B is given parallel micelle molecular orientation in the longitudinal direction, and the spherical cells contained therein are aligned as flat cells along the longitudinal direction. This string-like material B
Then, as shown in FIG. 1, a first pressurizing device 4,
It passes through the second pressurizing device 5, the third pressurizing device 6 and the shaping pressurizing device 7, and is wound up by the winding device 8, but the first
As shown in the figure, it is also possible to omit the third pressurizing device 6, or the number may be further increased in addition to the first to third pressurizing devices 4 to 6. Further, the first to third pressurizing devices 4 to 6 are substantially the same, and details thereof are shown in FIGS. 2, 3, and 4. The pressurizing device consists of a pair of upper and lower driving and driven gears 9 and 10 with smooth chamfered tooth surfaces and the same diameter. The gear 9 is provided with a groove-shaped notch in the circumferential direction, so that each tooth 11 has a U-shape with an arcuate bottom when viewed from the circumferential direction (see FIG. 4), and the shaft and When viewed from the direction, both shoulders 12, 12 form a notch 13 with a smooth curved surface (see FIG. 5). On the other hand, the other gear 10 is adapted to be adjusted so as to be able to come into contact with and separate from the gear 9, and is not provided with a notch like the gear 9, and when meshed as shown in FIG. The gaps 15, 15 between the shoulders 12, 12, the gear 10, and the tooth 14 are approximately the same width as the string-like material d, and the gap 18 between the bottom 16 of the gear 9 and the peak 17 of the tooth 14 is approximately the same width as the string-like material d.
is much narrower than the gap 15, for example by 1/2 or more.

The stretched string-like material B first passes through the first pressurizing device 4 configured as described above, and the effect of this passing state will be explained. When the gears 9 and 10 are rotated as shown in FIG. 2, the string-like material B receives almost no external force from the material B at the notch 13 position and the gap 15 position of the gear 9, as shown in FIG. Gap 18
In this position, the material B is strongly pressed and biased by the peaks 17 of the teeth 14 of the gear 10, and escapes along the tooth bottom 16 of the opposing gear 9, ie, outward in both transverse directions, as shown in FIG. . At this time, the flat cells in material B had a linear shape with almost all of their inner surfaces touching, but the external pressure opened the cell mouths and formed a network-like open structure, and The micelle molecular orientation in the transverse direction is disturbed. FIG. 6 shows the state, and in the same figure, the unevenly pressurized portion is indicated by b,
The unpressurized portion is indicated by a.

Next, when it passes through the second pressurizing device 5, it acts on the material B in the same way as the first pressurizing device 4, but as shown in FIG. 6, part a in the same figure receives uneven pressure. The previous part b in the same figure passes through the notch 13 of the gear 9 and is applied inward shaping pressure in the transverse direction, and becomes the state c in the figure, and its diameter D is larger than the diameter d of material B. That is, the bubbles of the flat bubble group become open and expand and become soft. Even when passing through the second pressurizing device 5, the orientation of the micelle molecules in the transverse direction of the unevenly pressurized portion b is disturbed. At this time, in order to suitably avoid leaving unpressurized unevenly pressurized parts in the state from the state shown in FIG. It is necessary to do so.

In this way, when the third pressurizing device 6 is further passed, the portion c in FIG. 6 is further subjected to uneven pressure, and the portion b
The portion is subjected to inward shaping pressure, and the network-like opening structure further progresses in the longitudinal direction, causing it to swell and soften, and as a final step, it passes through the shaping and pressure device 7 shown in FIG. 7. The device 7 consists of a pair of rolls 19, 19, both of which are provided with circumferential grooves 20, 20, and these grooves form a through hole 21. The through hole 12 shapes the outer diameter and slightly The final product, product string B', is obtained as shown in FIG. Note that instead of the pair of rolls 19, 19, a first roll 23 provided with a circumferential groove 22 as shown in FIG. The pressurizing device 7 is not limited to these devices.

(Effects of the Invention) The string obtained by the method of the present invention has parallel micellar molecular orientation arranged in the longitudinal direction as a whole, and has a reticular spread structure generated from flat cell groups in the longitudinal direction substantially throughout the string. Since the string has portions in which the micelle molecular orientation is disordered intermittently in the transverse direction, the string has a rounded appearance and does not have any fuzz on its surface.
It is extremely flexible and has strength in the longitudinal direction, and the disordered orientation of the micelle molecules in the transverse direction prevents further opening, thus providing an ideal string for automatic tying machines. This is because the pressurizing device used in the method of the present invention is not a conventional pressurizing device that runs between two sets of simple gears and bends to open the fibers. This is the result of using a shaping pressure device having a unique configuration in the final process.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the method for manufacturing the string of the present invention, Figs. 2 to 4 are detailed views of the pressurizing device, Fig. 5 is an explanatory drawing of pressurization, and Fig. 6 is a state of deformation of the string under pressure. The explanatory drawings, FIGS. 7 and 8, show the shaping pressurizing device. B... String-shaped material, 4, 5, 6... 1st to 3rd pressure device, 7... Shaping pressure device, B'... Product string.

Claims (1)

[Claims] 1. Polyolefin-based or other foamed synthetic resin is melt-extruded into a round rod shape and formed into a string-like material containing air bubbles inside.This is heated and stretched to give parallel micelle molecular orientation in the longitudinal direction, and the spherical particles contained inside the rod are heated and stretched. The bubbles are aligned as a flat cell group along the longitudinal direction, and then this stretched string-like material is meshed with a gear whose teeth have a notch with an arcuate bottom and a U-shaped circumferential groove. The micelles are passed through the notch of the first pressurizing device consisting of a gear, and are intermittently applied to the string-like material in both outward directions in the transverse direction with respect to the longitudinal direction. Disturbance of molecular orientation is caused, and a network-like opening structure is formed through the flat cell group, and then the first pressurizing device is passed through a second pressurizing device having the same configuration as the first pressurizing device. Applying shaping pressure inward in the transverse direction to the unevenly pressurized portion with the device, and forming the unpressurized unevenly pressurized portion into a network-like fiber opening structure in the same manner as in the first pressurizing device, A method for producing a synthetic resin string, which comprises obtaining a flexible string having a substantially circular cross section by passing it through a shaping and pressing device consisting of a pair of rolls provided with a circumferential groove.