JPS6228223B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for industrially manufacturing a reticulated composite fiber sheet that is a fiber material for forming a nonwoven fiber aggregate with excellent bulkiness and drapability. (Prior art) In general, in order to impart bulkiness and drapability to a nonwoven fiber aggregate (for example, a sheet-like nonwoven, futon cotton, tow-like aggregate, etc.), the denier of the raw material fiber must be as small as possible. It is known that crimped fibers are effective, and conventionally the extruder (spinning machine) has been used as a means to achieve this purpose.
A method in which two or more different polymers are extruded from a nozzle so as to be arranged in a block in the cross section to form a composite filament, and then (a) one type of polymer in the composite filament is eluted, or ( B) A method is known in which a machine separates different types of polymers, and a method to produce thinner fibers. (Problems to be Solved by the Invention) Although such conventional methods have certainly achieved the desired purpose in terms of producing thin fibers, they are not necessarily satisfactory in terms of forming non-woven fiber aggregates. isn't it. That is, in the method (a), one type of polymer is eluted from the fibers, resulting in a decrease in mass and an increase in cost, and in the method (b), it is difficult to form a fiber aggregate. For example, if the configuration is easy to mechanically split, splitting will occur in the pre-process mechanical process of cards, etc., making it difficult to create a web.On the other hand, if it is made difficult to split in the pre-process, it will be difficult to perform the desired splitting. , requiring special means and energy in post-processing. (Means for Solving the Problems) The present inventors have solved the problems of these conventional methods, and at the same time produced a fiber material that most effectively imparts bulkiness and drapability to a nonwoven fiber aggregate. The present invention was arrived at as a result of intensive research into the method. That is, in the method of the present invention, two or more types of thermoplastic polymers containing foamable substances are separately melted, and while being fed in a molten state from each extruder, they are brought together just before a die, so that each polymer is completely melted. In a state where they are mixed in a block shape without being mixed and without having a laminar planar boundary,
By extruding through a slit die with a gap of 0.5 mm or less and taking it off at a draft rate of 50 to 250 times while rapidly cooling it, it is a reticulated fiber sheet that is arranged approximately parallel to the length direction and interconnected. This is a method for producing a reticulated conjugate fiber sheet in which the cross sections of the individual fibers constituting the sheet-like product are different in shape and size, and two or more types of thermoplastic polymers are mixed in blocks in random shapes. According to the method of the present invention, the method can function most effectively to form a nonwoven fiber aggregate with excellent bulkiness and drapability, and the aggregate can be easily formed, which is novel in itself. A reticulated composite fiber sheet is produced. That is, as shown in FIG. 1, the reticular composite fiber sheet produced by the method of the present invention is a structure in which the fibers are arranged approximately parallel to each other in the length direction and are connected to each other in a reticulated manner. When forming a non-woven fiber aggregate, by stretching the sheet in the width direction, a reticulated fiber aggregate structure (web) in which fibers are two-dimensionally oriented as shown in FIG. Not only can it be easily formed regardless of the denier of the fibers (therefore, even with fibers of 1 denier or less, which is difficult with the conventional carding method), such a reticulated fiber aggregate structure can also be easily formed. Since it has a large degree of freedom with respect to stretching and deformation, it basically has excellent drapability. Furthermore, the most significant feature of the reticulated composite fiber sheet produced by the method of the present invention is that, as shown in Figure 3, the shapes and sizes of the individual fibers are different in cross section, and two or more different types of polymers are randomly distributed. They are mixed together in a block shape. When forming a nonwoven fiber aggregate with excellent bulkiness and drapability using this reticulated composite fiber sheet, first, several reticulated composite fiber sheets are laminated, and then the width is adjusted as described above. After stretching in the direction to form a mesh-like web, it may be heat-treated at an appropriate temperature, but in this case, when focusing on a single fiber, crimp occurs in the fiber due to the difference in thermal contraction of different polymers. do. What is important here is that each fiber has a completely different crimped shape because its cross section is different in shape and size, as well as the arrangement of different polymers. without causing
Rather, the fibers are oriented in the direction of separation and opening. Therefore, the fiber aggregate after heat treatment has extremely bulky properties, has a large degree of freedom against bending deformation, and has increased drapability. In the method of the present invention, two or more different polymers are used, and examples of such different polymers include polyethylene, polypropylene, polyacrylonitrile, polyvinyl chloride, polystyrene, vinyl fluoride copolymer, polyacetal, and ionomer resin. , acrylate resins, copolymers of vinyl monomers and diene compounds, nylon, polyester, polycarbonate, etc., as well as thermoplastic polymers with completely different chemical compositions, as well as different mixing ratios of two or more polymers. For example, in the case of a blend of two different polymers as shown in Figure 3, one polymer (A polymer) is 100% nylon, and the other polymer (B polymer) is 40% nylon and 60% polypropylene. Blend polymer of 80% nylon and 20% polypropylene as A polymer, or nylon 30 as B polymer
%, 70% polypropylene blend polymers, etc. are also included. Furthermore, in the present invention, the state in which "different types of thermoplastic polymers are mixed in a random block shape" means that different types of polymers have a macroscopic non-uniform shape and are non-uniform, as schematically shown in FIG. This refers to a state in which a certain arrangement is observed. Next, the method of the present invention for manufacturing such a reticulated composite fiber sheet will be described in detail. Conventionally, the burst fiber method described in Japanese Patent Publications No. 49-18508 and Japanese Patent Publication No. 52-44315 has been known as a method for forming a reticulated fiber sheet. According to this method, a molten polymer containing a foamable material is extruded from a slit die, immediately after which it is rapidly cooled and taken off with a high draft.
A reticular fiber sheet that is arranged approximately parallel to the length direction and interconnected, forming a reticular fiber sheet in which the cross section of each fiber constituting the sheet has a different shape and size. be able to. However, this method is still fully satisfactory in terms of crimp development and fine denier, which are necessary to obtain a nonwoven fiber aggregate with excellent bulkiness and drapability, which is the objective of the present invention. It wasn't something. However, in the method of the present invention, the different types of polymers that are combined just before the slit die are not completely mixed and are formed into a block shape without having a planar boundary due to completely laminar flow, as shown in FIG. It is extruded to the exit of the slit die while being mixed with the liquid. The polymer extruded from the slit die foams moderately while being rapidly cooled, but when it is taken off at a draft rate of 50 to 250 times, cracks occur in the foamed parts and a reticulated composite fiber sheet is formed. As mentioned above, the reticulated composite fiber thus obtained has different polymers randomly formed and mixed together in a block shape, so when it is heat-treated, complex crimp occurs.
Furthermore, in addition to narrowing the die slit width,
Fine denier can be achieved by increasing the draft rate as much as possible so that the polymer can be broken as finely as possible during drafting. That is, according to the method of the present invention, since different types of polymers are dispersed in the form of blocks, it is easy to break near the interlayers of different types of polymers during drafting, and therefore it is possible to make the fibers thinner more easily than in the conventional method. be. Furthermore, the spinnability of the molten polymer poses a problem in increasing the draft rate.
By selecting one of the different polymers as the main component polymer required for the desired nonwoven fiber aggregate and the other being a polymer with high spinnability, it is possible to draw at a high draft rate that is difficult with conventional methods. It is. In the method of the present invention, the thermoplastic polymer containing an expandable substance refers to (a) a gas that is substantially inert to the molten polymer (e.g., nitrogen, carbon dioxide, helium, etc.), or (b) the polymer used. Organic liquids (e.g., butane, propane, etc.) that vaporize during melting or extrusion of the polymer and significantly increase its deposition and are substantially inert to the polymer, or (c) Refers to a thermoplastic polymer that contains a foamable substance such as a blowing agent (e.g., azodicarbonamide, paratoluenesulfonyl semicarbazide, etc.) that generates a gas that is substantially inert to the polymer itself when melted or extruded. . Any thermoplastic polymer may be used as long as it can be melt extruded, such as polyethylene, polypropylene, polyacrylonitrile, polyvinyl chloride, polystyrene, vinyl fluoride copolymers, polyacetals, ionomer resins, and acrylate resins. , copolymers of vinyl monomers and diene compounds, nylon, polyester,
Examples include polycarbonate, thermoplastic polyurethane, copolymers and mixtures thereof, and the like. Furthermore, in the method of the present invention, two or more of these different types of polymers are used, as described above. Further, the draft rate in the present invention is the ratio of the take-up speed of the reticulated composite fiber sheet to the linear velocity of the polymer at the exit of the slit die, and is defined as follows. Draft rate = take-up speed of reticulated composite fiber sheet/polymer linear velocity at die exit According to the present invention, two or more different types of thermoplastic polymers (different types of polymers) containing foamable substances are For example 100-350 from different extruders
They are each extruded into polymer pipes in a molten state in the temperature range of
For example, 150 to 330℃ from a slit die of 0.5 mm or less
The reticulated conjugate fiber sheet is formed by extrusion at a temperature range of , and taking it off under a high draft with a draft ratio of 50 to 250 times, preferably 100 to 200 times while rapidly cooling using a cooling medium such as air or water to form the above-mentioned reticulated composite fiber sheet. Next, an example of an embodiment of the method of the present invention will be explained with reference to the drawings. FIG. 1 is a front view of a reticulated composite fiber sheet according to the present invention, and FIG. 2 is a front view of the reticulated composite fiber sheet stretched in the width direction. FIG. 3 is an enlarged cross-sectional view of the reticulated composite fiber sheet, in which the shapes and sizes of individual fibers are different in cross-section, and different types of polymers are randomly mixed in blocks. FIG. 4 is a schematic diagram of the method for manufacturing the reticulated composite fiber sheet. There are two sets of extruder systems A and B, and two different thermoplastic polymers are supplied from respective hoppers 1a and 1b to vent type extruders 2a and 2b, and the vent parts of both extruders Kneading is carried out in a molten state while introducing nitrogen gas from the polymer pipes 3a and 3b, and the foamable material-containing thermoplastic polymer is sent to the molding machine 4 through the respective polymer pipes 3a and 3b, where they are merged at the confluence 5 to be completely mixed. They are extruded from the slit die outlet 6 while being mixed in a block shape without forming a planar boundary due to a completely laminar flow. When the extruded thermoplastic polymer is rapidly cooled by the cooling air supplied from the cooling air outlet and taken off with a high draft, the nitrogen gas dispersed in the molten polymer foams after being discharged and is cooled, causing cracks. , and finally wound up as a reticulated composite fiber sheet 8. (Effects of the Invention) According to the present invention, a special reticular composite fiber sheet made of thin fibers is manufactured in one step. and,
Since the reticular composite fiber sheet according to the present invention has the above-described structure, it is a good fiber material for forming a web-like reticular fiber structure and a bulky non-woven fiber aggregate, and can be used as a material for non-woven production or as a supermaterial. , packaging materials, clothing, insulation materials, cushion materials, synthetic paper,
It can be used as an excellent material in many fields such as electrical insulation materials, interior materials, vehicle materials, and agricultural materials. It is especially suitable for high-quality clothing, high-grade filter materials, etc. The reticulated composite fiber sheet according to the present invention is also excellent as a material for various impregnated base materials, coating base materials, etc., and its processing uses are not limited to these. (Example) The method of the present invention will be described in more detail below with reference to Examples. Example 1 Using the apparatus shown in FIG. 4, polystyrene lentil chips were put into the hopper 1a of the extruder of system A, and polypropylene lentic chips were put into the hopper 1b of the extruder of system B, and the temperature was 240 to 300°C and 270 to 310°C. It was extruded into polymer pipes 3a, 3b from vent-type extruders 2a, 2b at a temperature of .degree. At this time, nitrogen gas was introduced from the vent part of each extruder at a pressure of 600 Kg/cm ² . The two polymers merging from the two polymer pipes 3a and 3b are mixed in a block shape and extruded through a slit die 6 with a gap of 300 μm at a temperature of 280°C, and are rapidly cooled by cooling air at a draft rate of 160 times. After winding up, a reticulated composite fiber sheet 8 was obtained. This reticulated composite fiber sheet had an appearance as shown in FIG. 1, and its fiber cross section was as shown in FIG. 3. The thus obtained reticular composite fiber sheet is
A crimped fiber sheet with an average fiber denier of 1.2 de and an average number of crimps of 96 crimps/cm was obtained by heat treatment in a temperature range of 140°C. Examples 2 to 7 The same procedure as in Example 1 was carried out except that various polymer mixtures were used, and the results shown in Table 1 were obtained. Comparative Examples 1 and 2 In FIG. 4, the same procedure as in Example 1 was carried out except that only the extruder of system A was operated and the extruder of system B was stopped. The results are listed in Table 1 together with Examples. In Table 1 below, the abbreviations represent the following, respectively. PS Polystyrene PP Polypropylene PET Polyethylene terephthalate PBT Polybutylene terephthalate NY-6 Nylon 6 AS Acrylonitrile-styrene copolymer PC Polycarbonate EEA Ethylene-ethyl acrylate copolymer

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a front view showing an example of a reticulated composite fiber sheet produced by the method of the present invention, and FIG. 2 is a front view of the reticulated composite fiber sheet stretched in the width direction. FIG. 3 is an enlarged sectional view of the reticulated composite fiber sheet. FIG. 4 is a schematic diagram of a method for manufacturing a reticulated composite fiber sheet, showing an example of the method of the present invention.

Claims (1)

[Claims] 1. Two or more types of thermoplastic polymers containing foamable substances are separately melted, and while being fed in a molten state from each extruder, they are brought together just before a die,
The polymers are extruded through a slit die with a gap of 0.5 mm or less without being completely mixed, without having any laminar planar boundaries, and are rapidly cooled to achieve a draft rate. 50～
By drawing at a magnification of 250 times, the fibers are arranged approximately parallel to each other in the longitudinal direction and are interconnected. 1. A method for producing a reticulated conjugate fiber sheet, which comprises forming a reticulated conjugated fiber sheet in which two or more thermoplastic polymers, each having different properties, are mixed in blocks in random shapes.