JPS60181311A - Production of fiber having protrusion and nozzle for producing fiber - Google Patents

Abstract

PURPOSE:To obtain fibers having umbrella-shaped protrusions without disappearance even by drawing, by melt extruding a melt of a thermoplastic resin through a nozzle having a tapered tip opening area thereof with a tilting angle. CONSTITUTION:The shape of a nozzle at the tip of an extruder is tapered to give a tilted angle (theta) of a molten resin channel at the nozzle tip part, and the cross-sectional area of the nozzle tip opening is smaller than that of other parts in the molten resin channel. The angle (theta) is usually within 3-10 deg. range. Protrusions formed by melt fracture become mutually discontinuous umbrella-shaped protrusions, and the aimed fibers having protrusions scarcely disappearing even by drawing are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing fibers with protrusions for reinforcing cement, and a monofilament forming nozzle used in producing the fibers.

When manufacturing various structures and molded products using cement, it is common practice to incorporate fibrous reinforcing materials to enhance the strength or toughness of the structures and molded products. Examples of reinforcing fibers for cement include asbestos fibers, carbon fibers, glass fibers, nylon fibers, polyethylene fibers, polypropylene fibers, Kevlar, and steel fibers.
Among these, fibers made of thermoplastic resins such as polyethylene, polypropylene, and nylon, which are lightweight and have good performance, are suitable. Fibers made of such thermoplastic resin include straight fibers, fibers with knots in the middle, feather-like fibrillated threads, and fibers with uneven surfaces due to embossing. In terms of ease of dispersion into the cement, difficulty in pulling out the fibers due to the anchoring effect in the cement after hardening, and strength development effects, fibers having large, undamaged protrusions on the fiber surface are particularly preferred. be.

The object of the present invention is to provide a fiber made of thermoplastic resin having random large protrusions on its surface,
Specifically, the object of the present invention is to provide a method for manufacturing fibers having a special shape as described above in an extremely simple manner, and a nozzle used in the process.

Traditionally, this type of fiber has been produced by molding thermoplastic resin into a tape shape using an extruder, adding uneven patterns to the surface using an embossing roll, etc., and then cutting it into thin strips, or by using resins with different melt viscosities. There is a method of drawing and cutting the monofilament in which melt fracture has actively occurred by mixing the monofilaments. However, the former process is complicated, the latter requires the effort of blending resins with different melt viscosities, and the types of resins that can be used are limited in order for melt fracture to occur stably. There was a problem. In view of the current situation, the present inventors have repeatedly investigated whether it is possible to obtain the desired fiber more easily, and found that if the nozzle shape at the tip of the extruder is made into a special shape, even if a single resin is used. The present invention was achieved by discovering that a stable melt-fractured monofilament can be obtained and that the protrusions generated by melt-fracture become protrusions of a special shape that do not disappear even when stretched.

That is, in the present invention, the thermoplastic resin melt is tilted at an inclination angle θ
This is a method for producing monofilament having mutually discontinuous and independent umbrella-like protrusions, which is characterized by melt extrusion through a nozzle having a small opening area at the tip of the nozzle. The present invention relates to a nozzle for producing fibers having an inclination angle θ so that the opening area of the nozzle tip becomes small.

The thermoplastic resin that can be used in the present invention may be any known resin, such as high-pressure low-density polyethylene, medium-low-ratio low-density polyethylene, medium-low-ratio high-density polyethylene, polypropylene, and poly-1-butene. ,
Polyolefins such as poly-4-methyl-1-pentene, copolymers of α-olefins and other monomers such as ethylene/vinyl acetate copolymers, ethylene/methyl methacrylate copolymers, polyvinyl chloride, polystyrene,
Examples include polymethyl methacrylate, polycarbonate, polyamide, polyester, and polysulfone. Among these, polyolefins are preferred because they are inexpensive, easy to mold, and have excellent chemical resistance, that is, they exhibit alkalinity in cement, so they have excellent alkali resistance.

The above polyolefins include α-olefins such as ethylene, propylene, ■-butene, ■-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, ■-heptene, and 1-octene. homopolymers or copolymers of these α-olefins and small amounts of other polymerizable monomers, such as vinyl acetate, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, etc. , Polymerization of vinyl acetate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, methyl acrylate, methyl methacrylate, methyl maleate, ethyl acrylate, ethyl methacrylate, ethyl maleate, maleic anhydride, etc. to the above polyolefin. Graft-modified polyolefins to which a synthetic monomer is grafted are also included in the polyolefins of the present invention. Among these, highly crystalline polymers such as polyethylene, polypropylene, and poly-1-butene are preferred because of their high rigidity, and among them, polyethylene is most preferred because of its good moldability.

The above resins contain heat stabilizers, weather stabilizers, lubricants, slip agents, dyes, pigments, flame retardants, antistatic agents, fillers, foaming agents, crosslinking agents, curing agents, silane coupling agents, etc. However, in order to stably and continuously produce monofilaments having umbrella-like protrusions, it is preferable that no lubricant, slip agent, or coupling agent be included. In other words, if a lubricant is contained in the resin, even if a monofilament with umbrella-shaped protrusions is produced using the nozzle described below, the protrusions will disappear midway through, making it impossible to obtain a monofilament with uniform umbrella-shaped protrusions. It may appear that there is no such thing.

In order to obtain a monofilament having umbrella-shaped protrusions more stably, the intrinsic viscosity [η
] is 1.5 to 3.5 a/g, especially 2.2 to 2.8, d
l/g, the ratio of weight average molecular weight (Mw) to number average molecular weight (in) measured by gel permeation chromatography; Mw/page n is preferably 8 or less, particularly 4 or less.

In order to obtain a monofilament having umbrella-like protrusions that are discontinuous and independent from each other and that do not disappear even when drawn using the above resin, the nozzle tip opening area was made small by setting the inclination angle θ. It can be manufactured by melt extruding resin from a nozzle.

To explain this specially shaped nozzle in detail, as shown in Figures 2 to 4, the molten resin flow path at the nozzle tip is tapered at an inclination angle θ, and the cross-sectional area of the nozzle tip opening is reduced. The cross-sectional area is smaller than that of other parts of the molten resin flow path. The angle of θ can be set to any appropriate angle, but is usually within the range of 3 to 101. Such a monofilament molding nozzle that is tapered so that the opening area of the resin flow path at the tip of the nozzle is small has not been known in the past. That is, as shown in FIG. 1, the conventional nozzle has a resin flow path at the tip of the nozzle that is flat and cylindrical, which is completely different from the specially shaped nozzle of the present invention. Of course, it is known to obtain melt-fractured monofilaments using conventional nozzles; for example, the smaller the cross-sectional diameter or cross-sectional area of the nozzle tip opening, the more melt-fracture will occur. However, in the melt-fractured product produced by this method, when a monofilament with a large diameter, that is, a monofilament with a diameter of 1.5 mm or more is produced using a single resin, the protrusions generated on the surface become continuous end spirals (see Fig. 6). ), it can be used as a reinforcing fiber for cement, and if a spiral force is applied, it is surprisingly easy to pull out, and when stretched to increase the fiber strength, the protrusions disappear or almost disappear (Fig. 7), for cement. However, when the nozzle of the present invention is used, fibers with almost no protrusions to exhibit the anchoring effect necessary to fully exert their effect as reinforcing fibers can be obtained. The protrusions become discontinuous and independent umbrella-like protrusions, and even when used as is as reinforcing fiber for cement, each umbrella-like protrusion independently exhibits an anchoring effect and is difficult to pull out, and even when stretched, the protrusions remain This results in fibers that hardly disappear (Figure 9).

The diameter of the monofilament with protrusions on the surface obtained by melt extrusion using the above-mentioned nozzle is 0.5 to 5 m.
m, and is preferably a thick monofilament with a diameter of 1.5 mm or more, more preferably 2.0 mm or more. If it is outside this range, stretching may occur, the strength of the reinforcing fibers obtained may be weakened and the reinforcing effect may be insufficient, or it may be difficult to mix in cement. Although the fibers obtained by the method of the present invention may be used as they are as reinforcing fibers for cement, it is particularly preferable to subject them to stretching treatment.

When a polyolefin is used as the resin, the monofilament having protrusions is preferably stretched at a temperature below the melting point of the polyolefin and above the secondary transition point, and the stretching ratio is 3 to 20 times, particularly 6 to 12 times. is appropriate. By this drawing process, a filament with high rigidity, low elongation, strength, and randomly large protrusions on the surface is obtained.

The thickness of the drawn filament thus obtained varies depending on the drawing ratio, but is approximately 150 to 15,000 deniers, and is then cut to an appropriate length to obtain reinforcing fibers for cement.

The manufactured reinforcing fibers can take various shapes, and can be cut into long lengths and assembled into net-like objects,
It can be used by cutting it into short fibers. Among them, the length is 5~IUOm m%, especially 30~80++u
It is preferable to use it by cutting it into n pieces.

The cement to which the reinforcing fibers obtained by the method of the present invention are blended may be hydraulic cements such as portland cement, white portland cement, silica cement, magnesia cement, pozzolan cement, or air-hard cements such as plaster, lime, acid-resistant cement, etc. In addition to special cement, one or more of various cement mortars, inorganic materials such as calcium carbonate and magnesium hydroxide, and earth and sand such as wall soil can be used.

Compared to conventional methods, the nozzle of the present invention and the production of reinforcing fibers for cement using the nozzle have the following advantages: (i) Even when a single resin is used without blending resins with different melt viscosities, projections are stably formed on the surface; Monofilament can be produced continuously.

(ii) Since the protrusions on the surface are not continuous with each other and form an independent umbrella shape, the protrusions do not disappear even if stretched.

(iii) Anchoring effect that imparts physical properties suitable for reinforcing fibers No special process is required to provide surface protrusions for practical use.

(iv) Stretching treatment for improving fiber strength and treatment for imparting random protrusions to the surface can be integrated.

It has excellent features such as

Experimental Example Using the nozzle in Fig. 1 with a nozzle tip diameter of 2.5 mm and the nozzle in Fig. 2 (θ = 5°), [η] in decalin solvent at 135°C was 2.5 dl/g, Mw/
High density polyethylene with Mn of 3.3 (density 0.96g/
cJ) as a raw material resin, a monofilament was obtained by melt extrusion at 200°C, and then a stretched product (8 times stretched) of the monofilament was obtained.

As a result, the monofilament molded using the nozzle shown in FIG. 1 had continuous spiral protrusions as shown in FIG. 6, and when it was stretched, most of the protrusions disappeared (FIG. 7). On the other hand, the second
The monofilament formed with the nozzle shown in the figure has discontinuous protrusions that form an independent umbrella shape as shown in Fig. 8, and the protrusions do not disappear even when stretched (Fig. 9), making it suitable for use as cement reinforcing fibers. It had a protrusion.

[Brief explanation of drawings]

Fig. 1 is a vertical sectional view of a conventional monofilament molding phase nozzle, Figs. 2 to 4 are longitudinal sectional views of a nozzle of the present invention, Fig. 5 is a sectional view of a nozzle using the nozzle of the present invention, and Figs. Figure 7 is a diagram (photograph) of a monofilament molded with a conventional nozzle and its drawn filament, and Figures 8 to 9 are diagrams (photograph) of a monofilament molded with the nozzle of the present invention and its stretched filament. . Applicant Mitsui Petrochemical Industries Co., Ltd. Agent Kazuki Yamaguchi 1 Figure 2 Figure 3 Figure 41jCj Figure 5, Figure 1:' Figure t Figure °nX Procedural amendment (method) % formula % 1. Indication of the case Patent Application No. 34324 of 1982 2. Name of the invention Method for producing fibers having protrusions and nozzle for producing fibers 3. Person making the amendment Relationship with the case Patent applicant (588) Mitsui Petrochemical Industry Co., Ltd. 4, Agent 3-2-5 Kasumigaseki, Chiyoda-ku, Tokyo 100, Japan Date of amendment order May 29, 1980 Dispatch 7, Statement of contents of amendment, page 13, lines 2-6 [ Figure 6... "Figures 6 to 7 are photographs showing the shape of fibers molded with a conventional nozzle, and Figures 8 to 9 are photographs showing the shape of fibers molded with the nozzle of the present invention. ” is corrected. that's all

Claims (4)

[Claims] (1) Having mutually discontinuous and independent umbrella-like protrusions characterized by extruding a melted thermoplastic resin through a nozzle that has an inclination angle θ to reduce the opening area of the nozzle tip. Method of manufacturing monofilament. (2) The manufacturing method according to claim 1, wherein a monofilament having mutually discontinuous and independent umbrella-like protrusions is drawn and cut at appropriate intervals. (3) The manufacturing method according to claim 1 or 2, wherein the thermoplastic resin is a polyolefin. (4) A nozzle for manufacturing fibers having protrusions, characterized in that the nozzle has an inclination angle θ so that the opening area at the tip of the nozzle is small.