KR101079004B1 - A collective fibers reinforced polymeric strip, method thereof, and a geogrid using the same - Google Patents

Abstract

The present invention relates to a fiber reinforced polymer strip, a method and apparatus for manufacturing the same, and a geogrid using the same. According to the present invention, a fiber-reinforced polymer strip having a matrix strip of thermoplastic polymer and a fiber assembly positioned inside the strip and having a plurality of fibers arranged in parallel with the strip, wherein the matrix strip has an average particle diameter of 0.1 to 60. A foam comprising a plurality of micropores having a thickness of 10 μm, the porosity of which is 10 to 70%, and the total cross sectional area of the fiber aggregate is 10 to 80% of the total cross sectional area of the fiber reinforced polymer strip. The fiber-reinforced polymer strip of the present invention is not only lightweight and economical because it has a matrix strip made of foam, but is also useful for producing geogrids because the reduction of mechanical properties due to foam introduction is minimized by controlling the amount and size of the fine pore size of the foam. Can be used.

Description

Fiber-reinforced polymer strip, manufacturing method and geogrid using the same {A COLLECTIVE FIBERS REINFORCED POLYMERIC STRIP, METHOD THEREOF, AND A GEOGRID USING THE SAME}

The present invention relates to a fiber-reinforced polymer strip constituting the geogrid mainly used as civil reinforcement materials, a method of manufacturing the same and a geogrid using the same.

Geogrid is a civil reinforcement material mainly used for retaining wall reinforcement, slope reinforcement, ground reinforcement, etc. Geogrid requires physical properties such as construction resistance, friction characteristics and shape stability in addition to high tensile strength, low tensile strain and creep deformation characteristics.

Geogrids can be divided into textile geogrids, extruded geogrids and bonded geogrids, depending on the material and the method of manufacture thereof.

Textile geogrids are made by weaving lattice-shaped fabrics using high-strength fibers and then coating them with polyvinyl chloride, bitumen, acrylic, latex, rubber-based resins, and the like. The textile geogrid has excellent tensile strength and creep properties because it uses high strength fibers, but the geogrid is more likely to be damaged depending on the condition of the soil during construction.

Extruded geogrid is produced by passing a polymer sheet extruded through an extruder through a roller to make holes at regular intervals and then stretch it uniaxially or biaxially (see GB 19890020843). Extruded geogrid can cause a problem that the stability of the reinforcing structure is deteriorated because the creep deformation is large when the load is applied for a long time due to the material properties.

On the other hand, the bonded geogrid is produced by extruding and stretching the polymer resin in the form of a strip, and forming the radial strip and the upward strip into a flat lattice, and then integrating the intersections of the strips using a laser or frictional heat (GB). 2266540), a strip reinforced with fiber aggregates is prepared and then arranged in a planar manner or by crossing the strips up and down to integrate the intersections (WO 99/28563 and Korean Patent Laid-Open No. 2005). -70384).

Among these bonded geogrids, so-called “fiber-reinforced polymer strips” reinforced with fiber aggregates are particularly useful for geogrid production because of their excellent mechanical properties.

However, since the geogrid is used as a reinforcing material for civil engineering structures, it is necessary to easily handle transportation, laying, etc. in civil engineering sites. In other words, there is a need for a lightweight fiber reinforced polymer strip without reducing the above-described fiber reinforced polymer strip significantly mechanical properties.

Typically, foaming methods are used to reduce the weight of plastic products. However, the plastic foam has a pore size of more than 100 μm and its size distribution is also uneven, resulting in deterioration of mechanical properties and shape stability. In addition, since the plastic foam is usually manufactured in a batch manner in which a mixture of polymer melt and gas is put into a mold (see EP 432997, USP 2005/0256215, USP 2007/0202326), there is a problem in that productivity is lowered.

Accordingly, an object of the present invention is to provide a fiber-reinforced polymer strip and geogrid using the same, which is light and economical, and minimizes the deterioration of mechanical properties due to foam introduction by controlling the amount and size of the micropore size of the foam.

It is a further object of the present invention to provide a method and apparatus for continuously producing a fiber reinforced polymer strip having the aforementioned characteristics.

In order to achieve the above object, the fiber-reinforced polymer strip according to the present invention is a fiber-reinforced polymer having a matrix strip of thermoplastic polymer and a fiber assembly located inside the strip and a plurality of fibers arranged in parallel with the strip. As a strip, the matrix strip is a foam comprising a plurality of fine pores having an average particle diameter of 0.1 to 60 μm, the porosity of which is 10 to 70%, and the total cross sectional area of the fiber aggregate is 10 of the total cross sectional area of the fiber reinforced polymer strip. To 80%.

In the fiber-reinforced polymer strip of the present invention, the thermoplastic polymer is a polyolefin resin having a melt index (MI) of 1 to 35, a polyethylene terephthalate (polyethylene terephthalate) having a intrinsic viscosity (IV) of 0.64 to 1.0, and a polyamide ( polyamides, polyacrylates, polyacrylonitrile, polycarbonates, polyvinylechloride, polystyrene, polybutadiene, etc., alone or in combination Two or more of them may be mixed and used, and as the fiber aggregate, each of polyester fiber, glass fiber, aramid fiber, polyvinyl alcohol fiber, carbon fiber, basalt fiber, stainless steel fiber, copper fiber, and amorphous metal fiber may be used alone. Or two or more of these fibers may be spliced together.

These fiber-reinforced polymer strips are arranged parallel to each other in the radial and upward directions at predetermined intervals, and intersecting portions of the fiber-reinforced polymer strips are integrated with each other, thereby forming geogrids.

In addition, in order to achieve the above object of the present invention, the method of producing a fiber-reinforced polymer strip of the present invention, (a) preparing a mixture of gas and polymer melt and a fiber assembly in which a plurality of fibers are arranged in parallel, respectively step; (b) feeding the fiber aggregate to a first inlet of the cross head, injecting a mixture of the gas and the polymer melt through a second inlet of the cross head formed around the first inlet, and then passing the Moving the fiber aggregate and the mixture of gas and polymer melt and adhering to each other to discharge to the outlet of the cross head; And (c) cooling the resultant of step (b).

In the manufacturing method of the fiber-reinforced polymer strip of the present invention, it is preferable that the outlet size of the cross head is smaller than the size of the moving path.

In addition, the apparatus for producing a fiber-reinforced polymer strip of the present invention, the first inlet through which a plurality of fibers in a fiber assembly arranged in parallel; A second inlet formed around the first inlet and into which a mixture of gas and polymer melt is introduced; A moving passage communicating with the first inlet and the second inlet and attached to each other while the mixture of the fiber aggregate and the gas and the polymer melt are moved; And a cross head including a fiber assembly attached to each other and an outlet through which a mixture of gas and polymer melt is discharged to the outside.

The fiber-reinforced polymer strip according to the present invention is not only light and economical because it has a matrix strip made of foam, but also to control the amount and size of the fine pore size of the foam, thereby minimizing the deterioration of mechanical properties due to the introduction of the foam, to geogrid production It can be usefully used.

In addition, according to the method of manufacturing a fiber-reinforced polymer strip of the present invention, it is possible to continuously produce a fiber-reinforced polymer strip excellent in light and mechanical properties.

Hereinafter, the present invention will be described in detail. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all of the technical idea of the present invention, which can be replaced at the time of the present application It should be understood that there may be various equivalents and variations.

Referring to FIG. 1, the fiber reinforced polymer strip 1 according to the present invention is located in a matrix strip made of thermoplastic polymer and inside the strip, such as a conventional fiber reinforced polymer strip, and a plurality of fibers are parallel to the strip. It is a fiber reinforced polymer strip having an array of fibers 3 arranged, wherein the matrix strip 2 is a foam. In particular, the foam of the matrix strip 2 is formed to include a plurality of fine pores having an average particle diameter of 0.1 to 60 탆, and the porosity is adjusted to 10 to 70%, and the total cross sectional area of the fiber aggregate 3 is adjusted to the fiber reinforced polymer strip. 10 to 80% of the total cross-sectional area, which is not only light and economical, but also minimizes the deterioration of mechanical properties due to foam introduction.

In the fiber-reinforced polymer strip of the present invention, when the average particle diameter and the porosity of the micropores included in the matrix strip foam are less than 0.1 μm and 10%, respectively, the physical properties are similar to those of the non-foamed product, but it is difficult to form micropores of less than 0.1 μm. As the specific gravity of the matrix strip is increased, the weight of the strip is not reduced, which does not have the characteristics as a foam. When the average particle diameter exceeds 60 µm and 70%, the mechanical properties of the strip are degraded due to excessive pore generation, resulting in the aggregates of the reinforcing fiber when laid. It is difficult to prevent damage, making it difficult to use geogrid manufacturing. In addition, when the total cross sectional area of the fiber aggregate is less than 10% of the total cross sectional area of the fiber reinforced polymer strip, the reinforcement effect by the fiber aggregate is insignificant, and when the cross sectional area exceeds 80%, the thickness of the matrix strip becomes too thin. Geogrids can easily be damaged by aggregates.

In the fiber-reinforced polymer strip of the present invention, any thermoplastic polymer may be used as the thermoplastic polymer, for example, a polyolefin resin having a melt index (MI) of 1 to 35, intrinsic viscosity (IV). ) Is 0.64 to 1.0 polyethylene terephthalate, polyamides, polyacrylates, polyacrylonitrile, polycarbonates, polyvinylechloride, polystyrene polystyrene), polybutadiene, and the like may be used alone or in combination of two or more thereof.

In addition, the fiber aggregate may be used as long as it is a collection of fibers used for manufacturing bonded geogrid, for example, polyester fiber, glass fiber, aramid fiber, polyvinyl alcohol fiber, carbon fiber, basalt fiber, stainless steel fiber, copper fiber And amorphous metal fibers may be used alone or in combination of two or more of them.

Such fiber-reinforced polymer strips can be produced in the form of various cross sections and thicknesses, such as circles and squares, preferably 2 to 100 mm in width (more preferably 3 to 50 mm), and 1 to 10 mm in thickness. More preferably 1.5 to 5 mm).

The fiber-reinforced polymer strips of the present invention described above are disposed parallel to each other in the radial and upward directions at predetermined intervals, and the cross-sections of the fiber-reinforced polymer strips are integrated with each other, thereby being formed of geogrids. The crossing angle of the fiber-reinforced polymer strips arranged in the radial direction and the upward direction can be changed depending on the purpose of use of the geogrid, but is preferably arranged in parallel within 80 to 100 degrees.

Looking at the manufacturing method of the fiber-reinforced polymer strip of the present invention with reference to Figs.

First, a fiber assembly in which a plurality of fibers are arranged in parallel and a mixture of a gas and a polymer melt are respectively prepared.

The fiber assemblies 3 are prepared according to a conventional method using the above-described fibers, and a mixture of gas and polymer melt (hereinafter referred to as gas / polymer mixture) is used to melt and knead the polymer resin in the extruder 4. A gas is injected, or a blowing agent that generates gas by pyrolysis together with the polymer resin is added to prepare a mixture of the uniform gas and the polymer melt in the extruder 4. In case of directly injecting gas, it is preferable to use a supercritical fluid such as carbon dioxide (CO ₂ ) or nitrogen (N ₂ ) .In the case of adding a blowing agent such as a polymer resin, a blowing agent is added separately, or the blowing agent is a polymer resin. It can be added in the form of pellets mixed with.

Next, the gas / polymer mixture in the extruder 4 is transferred to the crosshead 11 on which the fiber assembly 3 is mounted using a gear pump, so that the gas / polymer compound and the fiber assembly 3 are mutually different. After attachment, the fiber assembly 3 to which the gas / polymer compound is attached is discharged out of the cross head 11. At this time, due to the pressure difference between the pressure in the crosshead 11 and the atmospheric pressure, the gas melted in the polymer resin is expanded to produce a fiber-reinforced polymer strip 1 having a fine foaming structure.

Next, the continuously extruded micro-foamed fiber-reinforced polymer strip 1 passes through the cooling water tanks 13 and 14 to prevent the pores formed in the polymer resin from collapsing or the gas from escaping out of the polymer resin. If the foamed polymer strip is not cooled as described above, a foam having a desired porosity cannot be obtained, and a foam having small and uniform pores cannot be obtained.

Next, the fiber-reinforced polymer strip 1 having the micro-foamed structure, which is cooled, is wound on the bobbin 15 at a constant length of 5 to 150 m / min. Since the pore size and density of the resulting micro-foaming structure are closely related to the pressure difference and the pressure drop rate between the crosshead 11 and the atmospheric pressure, the pressure assembly 17 has a difference between the pressure in the pressure assembly 17 and the atmospheric pressure. ) Depends on how it is designed, and the rate of pressure drop can vary with the speed at which it is wound. It is known that the larger the pressure difference and the pressure drop speed, the smaller and uniform the cell is.

The present invention will be described in more detail with reference to the manufacturing apparatus and process diagram of the fiber reinforced polymer strip of the present invention. As shown in FIG. 2, an gas injector 6 including an extruder 4 for melt extrusion of the polymer resin 2, a high-pressure metering pump 8 for quantitatively injecting the gas supplied from the gas tank 7, Krill (9) equipped with fiber aggregate (3), fiber feeder (10) for supplying the fiber aggregate (3) to the crosshead (11) of the extruder, the molten polymer resin (2) and the fiber aggregate (3) a crosshead (11) to meet and form a fiber-reinforced polymer strip (1), a cooling device (13, 14) for cooling the fiber-reinforced polymer strip from the crosshead (11), manufactured fiber reinforcement It consists of a winding device 15 for pulling the strip at a constant speed, and a winder 16 for winding the strip to a constant length.

Referring to the configuration of the strip manufacturing process in detail as follows.

Referring to the process diagram of Figure 2, first, the reinforcing fibers 3 go through the fiber supply device (10). The fiber supply device 10 adjusts the speed at which the fiber aggregate 3 enters the crosshead 11, and the winding device 15 adjusts the speed of pulling the fiber-reinforced polymer strip 1 to the fiber aggregate 3. Ensure constant tension on the The fiber assembly 3 passing through the fiber supply device 10 passes through the crosshead 11.

In the process diagram of FIG. 2, the polymer resin 2 in pellet form is introduced into the extruder 4 through the hopper 5. The polymer resin 2 in pellet form releases gas upon decomposition so that a gas / polymer mixture is formed in the extruder. It is also possible to inject the blowing gas directly into the barrel of the extruder 4 using the high pressure pump 8 using the gas injection device 6.

The gas / polymer mixture is sent to the crosshead 11 where the fiber aggregate is located. The fiber assembly and the gas / polymer mixture adhere to each other in a pressurizing assembly 17 as shown in FIG. 3 in the crosshead 11. The pressurizing assembly 17 is composed of a nipple 18, a bushing 19, and a die 20. The nipple 18 is formed with a first inlet 21 through which the fiber aggregate 3 is introduced and a second inlet 22 through which the gas / polymer mixture is introduced. The second inlet 22 is preferably formed around the first inlet 21 because it is advantageous to completely cover the fiber aggregate 3 with the gas / polymer mixture. The first inlet 21 positions the reinforcing fibers 3 in the fiber-reinforced polymer strip 1 so as to be located in the center of the strip 1, and in the moving path 19a of the bushing 19 the fiber assembly 3. ) And a gas / polymer compound are attached, and the polymer resin 2 is designed to prevent backflow when a high pressure is formed in the die 20. If the pressure is not high here, the gas and the polymer resin do not form a single phase, thereby increasing the pore size. The die 20 is designed such that the combined fiber assembly 3 and the gas / polymer resin mixture are subjected to high pressure, and the shape of the strip 1 is determined.

Preferably, the size of the outlet 20a formed in the die 20 is smaller than the size of the moving path 19a. This is to allow the pressure 1 to be greater while the strip 1 is discharged through the outlet 20a. The pressurized gas / polymer mixture and the fiber assembly 3 exit the die 20 and at the same time, as the gas expands, pores grow in the polymer resin, and thus the fiber-reinforced polymer strip shown in FIG. ) Is created.

The fiber-reinforced polymer strip (1) exiting the die (20) is passed through a cooling water tank (13) (14) that can be temperature controlled so that the gas in the strip is not released to the outside. The cooled fiber reinforcement strip 1 is wound to a constant length by the winder 16 via the winding device 15.

After arranging the fiber-reinforced polymer strips (1) having the foam structure manufactured as described above to have a predetermined interval in the radial direction and the upward direction, the cross-sections of the strips arranged in the radial direction and the upper direction by ultrasonic, laser, and vibration The geogrid can be produced by integrating by welding or heating.

Thus, the geogrid composed of the fiber-reinforced polymer strip (1) having a micro-foamed structure produced by the method of the present invention does not significantly reduce the mechanical strength compared to the geogrid composed of a non-foamed fiber-reinforced polymer strip, and uniform micropores Since it has excellent light weight and impact mitigation properties, raw material cost per unit volume can be reduced.

In the present invention, the porosity is calculated by the following formula.

Porosity (%) = (ρ _N -ρ _F ) / ρ _N Ｘ 100

In the formula, ρ _N is the density of the foamless, ρ _F is the density of the foam.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The physical property measurement method of the Example is as follows.

density : ASTM  D 792

After cutting the fiber-reinforced polymer strip 1 to a certain length and removing the fibers, the density (d) is calculated by measuring the mass (m) and volume (V).

d = m / V

Pore size

After breaking the fiber-reinforced polymer strip 1, the cross section is measured using an electron microscope (SEM).

Tensile strength and Elongation  : ASTM  D 6637

The tension between the clamps attached to the top and bottom of the strain-controlled tensile tester is tensioned at a rate of 10 ± 3% / min.

Creep test: ASTM  D 5262

To evaluate the geogrid's unsteady tensile creep behavior under constant temperature loads (21 ± 2 ℃), the reload was 45% of the maximum tensile strength of the geogrid specimen. Measurements were made for 1,000 hours using the system.

Constructability  evaluation : ASTM  D 5818

After then treated in the same manner based on the hearth from the original structure built upon laying the geogrid sample area of at least 10m ² and laying the seongtojae thereon commit in the same manner as the real structure during construction. As the fill material, aggregates up to 60 mm in size were used.

After the compaction was completed, the compacted aggregate was removed so as not to damage the geogrid, the geogrid sample was extracted, and the tensile test was performed on the extracted sample to compare the tensile strength of the raw material.

Therefore, the workability is expressed by the percentage of decrease in strength.

Example  One

The polyester high-strength yarn of fineness 40000 denier is divided into three bundles and passed through a three-hole circular cross-section niple (18), a bushing (19), and a rectangular die (20). % Blowing agent was introduced into the extruder 4 preheated to 230 ° C., melted and kneaded to move the gas / polymer mixture to the crosshead 11 to extrude the fiber aggregate and gas / polymer mixture, and to 20 ° C. water bath (13). Winding through 14), while winding to 100m / min to prepare a fiber reinforced polymer strip (1) having a micro-foaming structure of 9.0mm in width, 1.1mm in thickness.

The physical properties of the strip 1 thus prepared are shown in Table 1 below.

Example  2

A fiber-reinforced polymer strip 1 having a micro-foamed structure was prepared in the same manner as in Example 1 except that the winding speed was changed to 60 m / min.

Example  3

Except for changing the fineness of the fiber (3) to 15000 denier, and having a fine foamed structure in the same manner as in Example 1 except that the die 20, the strip (1) having a width of 5.8mm, 1.0mm thick is used A fiber reinforced polymer strip (1) was prepared.

Comparative example  One

The fiber-reinforced polymer strip was prepared in the same manner as in Example 1 without using the foaming agent and the pressure assembly 17 of FIG.

Comparative example  2

A fiber-reinforced polymer strip was prepared in the same manner as in Example 4 without using a blowing agent and the pressure assembly 17 of FIG. 4.

Example  4

The strip 1 prepared in Example 1 was used as the radial strip 1, and the strip 1 prepared in Example 3 was used as the upward strip 1, and then arranged in a strip arrangement device. The geogrid was prepared by vibration welding. Number of ribs per unit width of fabricated geogrid (ribs / m), wide tensile strength (kN / m), 5% tensile strength (kN / m), tensile strain (%), creep strain (%), strength reduction rate ( %) Is shown in Table 2.

Comparative example  3

Geogrid was prepared in the same manner as in Example 5, except that the strip prepared in Comparative Example 1 was used as the radial strip, and the strip prepared in Comparative Example 2 was used as the upward strip. Number of ribs per unit width of fabricated geogrid (ribs / m), wide tensile strength (kN / m), strength at 5% tensile (kN / m), tensile strain (%), creep strain (%), strength reduction rate ( %) Is shown in Table 2.

As shown in Table 1, the fiber reinforced polymer strip (1) having a micro-foamed structure prepared in accordance with an embodiment of the present invention has an average pore size of 32 ㎛ to 48 ㎛, non-foaming fiber of the comparative example even at a low specific gravity It exhibits a similar level of physical properties as the reinforced polymer strip.

In addition, it can be seen that the physical properties of the geogrid composed of the fiber-reinforced polymer strip (1) having a micro-foaming structure as shown in Table 2 exhibits properties similar to those of the geogrid composed of the non-foamed fiber-reinforced polymer strip.

1 is a partially enlarged perspective view schematically showing the fiber-reinforced polymer strip of the present invention.

2 is an explanatory diagram showing a manufacturing process of a fiber reinforced polymer strip according to an embodiment of the present invention.

Figure 3 is a schematic cross-sectional view showing a pressing assembly provided in the apparatus for producing a fiber reinforced polymer strip of the present invention.

Claims (8)

A fiber-reinforced polymer strip having a matrix strip of thermoplastic polymer and a fiber aggregate located inside the strip, the plurality of fibers arranged in parallel with the strip, The matrix strip is a foam comprising a plurality of fine pores having an average particle diameter of 0.1 to 60 ㎛, the porosity of 10 to 70%, And the total cross sectional area of the fiber aggregate is 10 to 80% of the total cross sectional area of the fiber reinforced polymer strip. The method of claim 1, The thermoplastic polymer may be a polyolefin resin having a melt index (MI) of 1 to 35, a polyethylene terephthalate, polyamides, polyacrylates, and polyolefin having an intrinsic viscosity (IV) of 0.64 to 1.0. Fiber characterized in that it is any one selected from the group consisting of acrylonitrile (polyacrylonitrile), polycarbonates, polyvinylechloride, polystyrene and polybutadiene or a mixture of two or more thereof. Reinforcing polymer strips. The method of claim 1, The fiber aggregate is any fiber selected from the group consisting of polyester fiber, glass fiber, aramid fiber, polyvinyl alcohol fiber, carbon fiber, basalt fiber, stainless steel fiber, copper fiber and amorphous metal fiber or two or more of these fibers Fiber-reinforced polymer strips, characterized in that consisting of plied yarn. The method of claim 1, The fiber-reinforced polymer strip is a fiber-reinforced polymer strip characterized in that it has a square cross section of 2 to 100mm in width, 1 to 10mm in thickness. (a) preparing a mixture of gas and polymer melt and a fiber aggregate in which a plurality of fibers are arranged in parallel; (b) feeding the fiber aggregate to a first inlet of the cross head, injecting a mixture of the gas and the polymer melt through a second inlet of the cross head formed around the first inlet, and then passing the Moving the fiber aggregate and the mixture of gas and polymer melt and adhering to each other to discharge to the outlet of the cross head; And (c) cooling the resultant of step (b); manufacturing method of a fiber reinforced polymer strip comprising a. The method of claim 5, The outlet size of the cross head is a method of manufacturing a fiber reinforced polymer strip, characterized in that smaller than the size of the moving path. In a geogrid in which fiber-reinforced polymer strips are disposed parallel to each other in a radial direction and an upward direction at predetermined intervals, and intersecting portions of the fiber-reinforced polymer strips are integrated with each other. Geogrid, characterized in that the fiber-reinforced polymer strip is the fiber-reinforced polymer strip of any one of claims 1 to 4. The method of claim 7, wherein And wherein the crossing angle between the radially arranged fiber reinforced polymer strip strips and the upwardly arranged fiber reinforced polymer strip strips is 80 to 100 degrees.

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