A high-strength injection-molded geogrid and its manufacturing process

Abstract

The present invention proposes a high-strength injection-molded geogrid, which is formed by overlapping a number of grid strips that are staggered horizontally and vertically. The grid strips include a PET embryonic strip and a coating layer coated on the outer surface of the PET embryonic strip, and the coating layer is a polyolefin / PET blended modified material. The present invention also proposes a manufacturing process for a high-strength injection-molded geogrid, wherein a single-screw extruder extrude PET material, and another twin-screw extruder extrude polyolefin / PET blended modified material. The two extruders respectively feed the materials into a double-layer co-extrusion composite die head to extrude a composite embryonic strip of polyolefin / PET blended modified material coated with PET. The use of PET material greatly improves the strength of the geogrid belt, and the use of polyolefin / PET blended modified material to produce the coating material allows the polyolefin and PET in the coating material to be well fused. Since the coating material contains PET components, the coating layer and PET are better combined in the subsequent stretching process without the occurrence of stratified stretching, thereby improving the compatibility of the strips and the injection molding nodes.

Description

Technical Field

[0001] The invention belongs to the technical field of geogrid production and processing, and particularly relates to a high-strength injection-molded geogrid and a manufacturing process thereof. Background Art

[0002] Geogrid is a geosynthetic material, a mesh structure made of high-strength polymer fibers through stretching, injection molding and other processes. It can be used in land reinforcement, soil reinforcement and other projects to improve the tensile strength and stability of the soil.

[0003] The existing injection-molded geogrid is to connect the criss-crossed PP tapes by injection molding. Due to the strength of the PP tape, the strength of the injection-molded geogrid is about 100KN / M. Therefore, if you want to improve the strength of the geogrid, you can only use a stronger material to replace the PP tape. PET is low in price and high in strength. The strength of PET tape with the same cross-sectional area is more than three times that of PP tape, making it a very good substitute for PP tape.

[0004] However, due to the extrusion processing characteristics of PET, it is not easy to produce a tape that meets the width and thickness requirements of the injection molding grid, and the compatibility of the PET tape with the injection molding node is too poor, and the tape can be easily pulled out from the injection molding node. Summary of the invention

[0005] In view of the defects pointed out in the background technology, the purpose of the present invention is to provide a high-strength injection-molded geogrid and a manufacturing process thereof, which has solved the problems of injection-molded node separation and belt incompatibility.

[0006] To achieve the above object, one of the technical solutions of the present invention is:

[0007] A high-strength injection-molded geogrid, which is formed by overlapping a number of grid strips that are staggered horizontally and vertically. The grid strips include a PET embryonic strip and a coating layer coated on the outer surface of the PET embryonic strip, and the coating layer is a polyolefin / PET blended modified material.

[0008] Furthermore, the polyolefin / PET blended modified material comprises 20-26% of PET, 50.5%-67.8% of polyolefin, 0.2-0.5% of antioxidant, 8-15% of maleic anhydride grafted polyolefin and 4-8% of carbon black masterbatch.

[0009] Furthermore, the coating thickness of the coating layer is 0.2-0.5 mm, the total thickness of the grid strips is 2.0-2.5 mm, and the total width of the grid strips is 22.0-23.0 m.

[0010] To achieve the above purpose, the second technical solution of the present invention is:

[0011] A manufacturing process of a high-strength injection-molded geogrid comprises the following steps:

[0012] Step 1, drying the raw materials, drying the PET;

[0013] Step 2, extrusion coating, the grid strip is extruded by two extruders, one single-screw extruder extrude PET material, and the other twin-screw extruder extrude polyolefin / PET blended modified material, the two extruders respectively feed the materials into a double-layer co-extrusion composite die head, and extrude a composite embryo belt of polyolefin / PET blended modified material coated with PET, the coating thickness of the composite embryo belt is 1-2mm, the total thickness of the composite embryo belt is 5-8mm, and the total width of the composite embryo belt is 60-80mm;

[0014] Step 3, the embryo strip is shaped. After the embryo strip is extruded, it enters the cooling water tank for cooling and shaping;

[0015] Step 4, the embryonic strip is first-stage drawn, and the shaped embryonic strip is drawn and stretched by a first-stage stretching machine, and the first-stage stretching machine is provided with a preheating unit composed of a plurality of preheating rollers, and the preheating unit is connected to a mold temperature controller, and the medium is heat transfer oil;

[0016] Step 5, heating the embryonic belt in an oven, heating the embryonic belt after primary traction and preheating, the length of the oven is 4-6m;

[0017] Step 6, secondary traction of the embryonic strip, using a secondary stretching device to perform secondary traction and stretching on the embryonic strip heated in the oven, wherein the secondary stretching device is provided with a plurality of steel rollers;

[0018] Step 7, rapid preheating and shaping, using another oven to rapidly heat-shape the embryo strip after secondary traction and stretching, the oven is 4-6m long, and the oven is equipped with multiple fans for air supply;

[0019] Step 8, embossing, embossing the surface of the preheated and shaped embryo strip to increase the friction between the strip body and the soil body;

[0020] Step 9, traction cooling, using cooling traction equipment to stretch, cool and shape the embryo strip after the patterning to form a grid strip. The cooling traction equipment is equipped with multiple cooling rollers, and all cooling rollers are connected to a constant temperature control station to control the temperature of the cooling rollers;

[0021] Step 10, injection molding, transporting the prepared grid strips to the injection molding section, and using an injection molding machine to injection mold the staggered nodes of the grid strips to finally form a geogrid.

[0022] Furthermore, in step 1, the PET is dried at a temperature of 150-180° C. for 6-8 hours.

[0023] Furthermore, in step 2, the operating temperature of the single-screw extruder is 220-250°C, and the operating temperature of the twin-screw extruder is 190-230°C.

[0024] Furthermore, in step 3, the cooling water tank is 3 m long and the water temperature is not higher than 30°C.

[0025] Furthermore, in step 10, the node injection material is made of polyolefin material.

[0026] After adopting the above technical solution, the beneficial effects of the present invention are:

[0027] The use of PET material has greatly improved the strength of the geogrid belt. The use of polyolefin / PET blended modification to produce the coating material allows the polyolefin and PET in the coating material to be well compatible. Since the coating material contains PET components, the coating layer and PET are better combined in the subsequent stretching process without delamination and stretching, thereby improving the compatibility of the strips and injection molding nodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 The process flow chart of the guide plate; DETAILED DESCRIPTION

[0030] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention.

[0031] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of the present invention. In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments to facilitate a clearer understanding of the present invention.

[0033] The embodiment of the present invention provides a high-strength injection-molded geogrid, which is formed by overlapping a plurality of grid strips that are staggered horizontally and vertically. The grid strips include a PET embryonic strip and a coating layer coated on the outer surface of the PET embryonic strip, and the coating layer is a polyolefin material.

[0034] Due to the large performance gap between polyolefin and PET, the contact interface between the polyolefin coating layer and the PET embryonic tape is not compatible. When stretched, the coating material and PET will be delaminated, and qualified tapes cannot be produced. To solve this problem, polyolefin / PET blending modification is used to produce coating. The polyolefin / PET blending modification material includes 20-26% PET, 50.5%-67.8% polyolefin, 0.2-0.5% antioxidant, 8-15% maleic anhydride grafted polyolefin and 4-8% carbon black masterbatch.

[0035] The use of PET material has greatly improved the strength of the geogrid belt. The use of polyolefin / PET blending modification to produce the coating material allows the polyolefin in the coating material to be well compatible with the PET embryo. Since the coating material contains PET components, the coating layer and PET are better combined in the subsequent stretching process without layered stretching, which improves the compatibility of the strips and injection molding nodes.

[0036] Another embodiment of the present invention provides a manufacturing process of a high-strength injection-molded geogrid, comprising the following steps:

[0037] Step 1, drying the raw materials, drying the PET at a temperature of 150-180°C for 6-8 hours;

[0038] Step 2, extrusion coating, the grid strip is extruded by two extruders, one single-screw extruder extrude PET material, its working temperature is 220-250°C, and the other twin-screw extruder extrude polyolefin / PET blended modified material, its working temperature is 190-230°C, the two extruders respectively feed the materials into the double-layer co-extrusion composite die head, extrude the polyolefin / PET blended modified material coated PET composite embryo belt, the coating thickness of the composite embryo belt is 1-2mm, the total thickness of the composite embryo belt is 5-8mm, and the total width of the composite embryo belt is 60-80mm;

[0039] Step 3, the embryo strip is shaped. After the embryo strip is extruded, it enters the cooling water tank for cooling and shaping. The cooling water tank is 3m long and the water temperature is not higher than 30°C.

[0040] Step 4, the embryonic strip is first-stage drawn, and the shaped embryonic strip is drawn and stretched by a first-stage stretching machine, and the first-stage stretching machine is provided with a preheating unit composed of a plurality of preheating rollers, and the preheating unit is connected to a mold temperature controller, and the medium is heat transfer oil;

[0041] Step 5, heating the embryonic belt in an oven, heating the embryonic belt after primary traction and preheating, the length of the oven is 4-6m;

[0042] Step 6, secondary traction of the embryonic strip, using a secondary stretching device to perform secondary traction and stretching on the embryonic strip heated in the oven, wherein the secondary stretching device is provided with a plurality of steel rollers;

[0043] Step 7, rapid preheating and shaping, using another oven to rapidly heat-shape the embryo strip after secondary traction and stretching, the oven is 4-6m long, and the oven is equipped with multiple fans for air supply;

[0044] Step 8, embossing, embossing the surface of the preheated and shaped embryo strip to increase the friction between the strip body and the soil body;

[0045] Step 9, traction cooling, using cooling traction equipment to stretch, cool and shape the embryo strip after the patterning to form a grid strip. The cooling traction equipment is equipped with multiple cooling rollers, and all cooling rollers are connected to a constant temperature control station to control the temperature of the cooling rollers;

[0046] Step 10, injection molding, after the traction and stretching in the above steps, finally form a grid strip with a coating thickness of 0.2-0.5mm, a total thickness of 2.0-2.5mm, and a total width of 22.0-23.0mm, transport the prepared grid strip to the injection molding section, and use an injection molding machine to injection mold the staggered nodes of the grid strip to obtain a geogrid, and the node injection plastic is made of polyolefin material.

[0047] According to the embodiments of the present invention as described above, these embodiments do not describe all the details in detail, nor do they limit the invention to specific embodiments. Obviously, many modifications and changes can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and the modified use based on the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A manufacturing process for high-strength injection-molded geogrid, characterized in that: The following steps are involved: Step 1, drying the raw materials, drying the PET; Step 2, extrusion coating, the grid strip is extruded by two extruders, one single-screw extruder extrude PET material, and the other twin-screw extruder extrude polyolefin / PET blended modified material, the two extruders respectively feed the materials into a double-layer co-extrusion composite die head, and extrude a composite embryo belt of polyolefin / PET blended modified material coated with PET, the coating thickness of the composite embryo belt is 1-2mm, the total thickness of the composite embryo belt is 5-8mm, and the total width of the composite embryo belt is 60-80mm; Step 3, the embryo strip is shaped. After the embryo strip is extruded, it enters the cooling water tank for cooling and shaping; Step 4, the embryonic strip is first-stage drawn, and the shaped embryonic strip is drawn and stretched by a first-stage stretching machine, and the first-stage stretching machine is provided with a preheating unit composed of a plurality of preheating rollers, and the preheating unit is connected to a mold temperature controller, and the medium is heat transfer oil; Step 5, heating the embryonic belt in an oven, heating the embryonic belt after primary traction and preheating, the length of the oven is 4-6m; Step 6, secondary traction of the embryonic strip, using a secondary stretching device to perform secondary traction and stretching on the embryonic strip heated in the oven, wherein the secondary stretching device is provided with a plurality of steel rollers; Step 7, rapid preheating and shaping, using another oven to rapidly heat-shape the embryo strip after secondary traction and stretching, the oven is 4-6m long, and the oven is equipped with multiple fans for air supply; Step 8, embossing, embossing the surface of the preheated and shaped embryo strip to increase the friction between the strip body and the soil body; Step 9, traction cooling, using cooling traction equipment to stretch, cool and shape the embryo strip after tying to form a grid strip, the cooling traction equipment is equipped with multiple cooling rollers, all cooling rollers are connected to a constant temperature control station to control the temperature of the cooling rollers; Step 10, injection molding, transporting the prepared grid strips to the injection molding section, and using an injection molding machine to perform injection molding on the staggered nodes of the grid strips to finally form a geogrid; The geogrid is formed by overlapping a plurality of grid strips staggered in a horizontal and vertical direction, wherein the grid strips include a PET embryonic strip and a coating layer coated on the outer surface of the PET embryonic strip, wherein the coating layer is a polyolefin / PET blended modified material; The polyolefin / PET blended modified material comprises 20-26% of PET, 50.5%-67.8% of polyolefin, 0.2-0.5% of antioxidant, 8-15% of maleic anhydride grafted polyolefin and 4-8% of carbon black masterbatch.

2. The manufacturing process of a high-strength injection-molded geogrid according to claim 1, characterized in that: In the step 1, the PET is dried at a temperature of 150-180° C. for 6-8 hours.

3. The manufacturing process of a high-strength injection-molded geogrid according to claim 1, characterized in that: In the step 2, the operating temperature of the single-screw extruder is 220-250°C, and the operating temperature of the twin-screw extruder is 190-230°C.

4. The manufacturing process of a high-strength injection-molded geogrid according to claim 1, characterized in that: In step 3, the cooling water tank is 3 m long and the water temperature is not higher than 30°C.

5. The manufacturing process of a high-strength injection-molded geogrid according to claim 1, characterized in that: In step 10, the node injection material is made of polyolefin material.

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