KR20180115180A - Synthetic resin manhole cover and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a manhole cover. More specifically, the present invention relates to a synthetic resin manhole cover and a method for manufacturing the manhole cover that is made by using an unsaturated polyester resin as a main material to prevent detachment and separation, to increase abrasion resistance and double its service life, and to enhance its ability to withstand loads by using a continuous reinforced fiber frame. The manhole cover manufacturing method according to the present invention, which uses a synthetic resin based on an unsaturated polyester resin as a raw material, includes a step of preparing 20 parts by weight of color chip, 10 parts by weight of glass fiber (VUP 3518), 10 parts by weight of discoloration preventing glass fiber (STYPOL 040-4923SP), and 1 part by weight of shrinkage preventing agent (low-shrinkage agent, AT10) as a flat-bottom wear layer; a step of mixing the prepared color chip, glass fiber, discoloration preventing glass fiber, and shrinkage preventing agent in a mixer; a step of spraying the mixed material onto a molding frame (mold) with a sprayer, and then curing the mixture as the wear layer; and a step of laminating a synthetic resin layer and a glass fiber cloth on the cured wear layer alternately in three or more layers to complete a manhole cover having a desired thickness.

Description

Technical Field [0001] The present invention relates to a synthetic resin manhole cover and a manufacturing method thereof,

The present invention relates to a manhole cover, and more particularly, to a manhole cover which is made of an unsaturated polyester resin as a main material to prevent detachment and detachment, to increase abrasion resistance, to double its service life, Reinforced synthetic resin manhole cover and a method of manufacturing the same.

Generally, manhole is a hole that allows people to enter the road surface. It is installed at the place where the thickness or direction of the pipe changes, the starting point or the crossing point, the middle of the long straight portion, do.

The shape of the circle is the most easily rounded, and the square has a rectangular or elliptical shape. The entrance is surrounded by a frame made of iron or a stone, and covers a circular lid of a cast iron or reinforced concrete with a diameter of about 60 cm.

The main body is made of concrete or brick, and the inside diameter of the passage hole is usually 1 to 1.2 m, and the bottom is made to be equal to the bottom of the channel or somewhat down to accommodate the deposit. The depth varies depending on the depth of the channel, but some depths exceed 100 meters.

In addition to the above manhole, sewage treatment facilities and storage tanks buried in the underground are tiled in the ground, and a method of burying a tank manufactured from the outside or a concrete is laid on the site.

These manholes, sewage treatment facilities, storage tanks, etc. are provided with manhole covers so that the inside of the manholes or the storage tanks can be directly accessed or pass by the man, and slip prevention protrusions for preventing slippage and various specifications and guide letters are inserted in the upper part of the manhole cover .

The manhole cover is generally made of cast iron. The cast-iron manhole cover has the advantage of having a strong bearing capacity and a semi-permanent life. However, the manhole cover made of cast iron is expensive, has a high risk of theft, and is damaged by corrosion during long-term use. In addition, there is a problem that a manhole cover made of a cast iron material has a problem that it is required to cut a round block so as to conform to the shape of a manhole cover, thereby causing a risk of electric shock due to electric leakage. In addition, the lid of the manhole dedicated to the fire extinguishes the yellow paint generally. In the case of the manhole cover made of the cast iron, the paint is easily erased and difficult to distinguish.

A manhole cover made of cement has been developed to overcome the disadvantages of such cast iron manhole cover. However, the manhole cover made of cement has a problem in that the strength to withstand the load is limited, and the lifetime is relatively short, which causes cracks on the surface of the cement mortar for a long period of use and causes surface contamination. In addition, since the manhole cover made of cement is made by mixing cement and artificial stone, color and manhole surface are inevitably simple.

Document 1. Utility Model Registration No. 0416495 (Registered on May 10, 2006) Document 2. Patent Registration No. 0442005 (registered on July 19, 2004)

DISCLOSURE Technical Problem Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide an unsaturated polyester resin as a main material for preventing segregation and separation, The present invention provides a synthetic resin manhole cover having a reinforcing fiber frame and a method of manufacturing the same.

In order to achieve the above-mentioned object, the synthetic resin manhole cover of the present invention is a manhole cover manufactured by using synthetic resin made of Unsaturated Polyester resin as a raw material, Glass fibers, anti-discoloration-resistant glass fibers and anti-shrinkage agents are mixed to give various colors as required, with 20 parts by weight of color chips and 10 parts by weight of glass fibers (VUP 3518). (Unsaturated Polyester) resin as a raw material is used as a raw material in a lower part of a wear layer mixed with 10 parts by weight of discoloration-preventive glass fiber (STYPOL 040-4923SP) and 1 part by weight of a shrinkage inhibitor (water-reducing agent, AT10) A resin layer having a molecular weight of about 500 to 4,000 and curing the resin with a vinyl unit to form a molded product; and a reinforcing fiber frame (frame) for absorbing the load of the manhole cover and dispersing the load to the periphery thereof. The synthetic resin layer and the glass fiber fabric are each formed in a shape fit to the metal mold and have elasticity and are not easily broken by an external force. .

Here, the synthetic resin manhole cover is formed to have a convex entasis shape from the outer circumferential surface to the upper surface of the inner circumferential surface.

The synthetic resin layer is made of a mixture of quartz and synthetic resin. The synthetic resin is made of Unsaturated Polyester resin as a raw material, and has a polymerizable double bond having a molecular weight of about 500 to 4,000, To form a molded product.

The abrasion layer was prepared by mixing color chips, glass fibers, discoloration-preventive glass fiber and anti-shrinkage agent, and various colors were prepared as necessary. 20 parts by weight of color chips, 10 parts by weight of glass fibers (VUP 3518) 10 parts by weight of discoloration-preventive glass fiber (STYPOL 040-4923SP) and 1 part by weight of a shrinkage preventive agent (AT10) are mixed.

In order to achieve the above object, a synthetic resin manhole cover of the present invention is a manhole cover manufactured by using a synthetic resin made of Unsaturated Polyester resin as a raw material, A wear layer formed by mixing a glass fiber, a discoloration-preventive glass fiber and an anti-shrinkage agent to form a uniform thickness; A first synthetic resin layer formed as a lower layer from the bottom of the abrasion layer to prevent the manhole cover from being split; A first glass fiber monolayer formed below the first synthetic resin layer and absorbing a load and dispersing the load around; A second synthetic resin layer formed below the first glass fiber monolayer and formed in a convex shape from the outer circumferential surface to the inner circumferential surface downward to prevent the manhole cover from being split; A second glass fiber monolayer formed in the lower portion of the second synthetic resin layer to have a uniform thickness to absorb a load and disperse the load around; A third synthetic resin layer formed below the second glass fiber monolayer and having a uniform thickness on the second glass fiber monolayer to prevent the manhole cover from being split; A third glass fiber monolayer formed in a lower portion of the third synthetic resin layer to absorb the load and disperse the load to the surroundings; And a fourth synthetic resin layer formed to a uniform thickness below the third glass fiber layer to prevent the manhole cover from being split.

In order to accomplish the above object, a method of manufacturing a manhole cover of a synthetic resin according to the present invention is a method for manufacturing a manhole cover using a synthetic resin having an unsaturated polyester resin as a raw material, , 10 parts by weight of glass fiber (VUP 3518). 10 parts by weight of discoloration-preventive glass fiber (STYPOL 040-4923SP) and 1 part by weight of an anti-shrinkage agent (AT10); Mixing the prepared color chips, glass fibers, discoloration preventing glass fiber and anti-shrinkage agent in a blender; Spraying the mixed material onto a mold with a splay unit, and curing the mixed material as the wear layer; And laminating a synthetic resin layer and a glass fiber cloth on the cured abrasion layer in three or more layers alternately to complete a manhole cover having a desired thickness.

The present invention has the following effects.

First, the manhole cover of the present invention can prevent separation / separation phenomenon by using an unsaturated polyester resin as a main material.

Second, the manhole cover of the present invention can increase the wear life by using an unsaturated polyester resin as a main material, thereby doubling the service life.

Third, the manhole cover of the present invention can enhance the ability to withstand load by using a continuous reinforced fiber frame with an unsaturated polyester resin as a main material.

Fourth, by adjusting the thickness according to the application, it can provide manhole cover which is better than the international standard in weight of 4-60 tons to bear the load.

Fifth, it is economical because it does not rust, it does not have corrosion, it has a strong force to withstand load, it has a semi-permanent service life, it is easy to maintain, and there is no risk of theft compared with a case made of cast iron.

Sixth, the manhole cover of the present invention is made of unsaturated polyester resin as a main material, and it has various values such as water and sewage manhole cover, electricity, communication lid, and tree protection.

Seventh, the manhole cover of the present invention is mainly made of unsaturated polyester resin and has a small risk of breakage during installation and maintenance work.

Eighth, the manhole cover of the present invention is formed in a convex shape that is convex from the outer peripheral surface to the uppermost central portion of the inner peripheral surface to serve as a step to prevent high-speed travel in order to assist the pedestrian in safety while walking, Can be strengthened.

1 is a cross-sectional view illustrating a synthetic resin manhole cover according to a first embodiment of the present invention.
2 is a cross-sectional view illustrating a synthetic resin manhole cover according to a second embodiment of the present invention.
3 is a cross-sectional view illustrating a synthetic resin manhole cover according to a third embodiment of the present invention.
FIGS. 4 to 7 are views showing products to which a synthetic resin manhole cover according to the present invention can be applied.
8 is a flowchart illustrating a method of manufacturing a synthetic resin manhole cover according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In addition, although the term used in the present invention is selected as a general term that is widely used at present, there are some terms selected arbitrarily by the applicant in a specific case. In this case, since the meaning is described in detail in the description of the relevant invention, It is to be understood that the present invention should be grasped as a meaning of a term that is not a name of the present invention. Further, in describing the embodiments, descriptions of technical contents which are well known in the technical field to which the present invention belongs and which are not directly related to the present invention will be omitted. This is for the sake of clarity of the present invention without omitting the unnecessary explanation.

1 is a cross-sectional view illustrating a synthetic resin manhole cover according to a first embodiment of the present invention.

1, the synthetic resin manhole cover according to the first embodiment of the present invention basically comprises at least three layers to coat the first synthetic resin layer 100, The first glass fiber fabric 110, the second synthetic resin layer 120, the second glass fiber fabric 130, the third synthetic resin layer 140, the third glass fiber fabric 150, the n-2 synthetic resin layer The n-1 glass fiber fabric 170, the n-1 synthetic resin layer 180, the n-1 glass fiber fabric 190, the n-th synthetic resin layer 200 and the wear layer 210 .

Here, the synthetic resin layers 100, 120, 140, 160, 180, and 200 are made of a mixture of quartz and synthetic resin. The synthetic resin is composed of an unsaturated polyester resin (Unsaturated Polyester) And a resin having a molecular weight of about 500 to 4,000. The resin is cured by using a vinyl unit to form a molded article. Such an unsaturated polyester resin is useful for preventing separation and separation phenomenon. In addition, wear resistance can be increased and the service life can be doubled.

The glass fiber fabrics 110, 130, 150, 170, and 190 absorb most of the load and absorb and partially disperse the load. The fiberglass fabrics 110, 130, 150, 170, And has elasticity, which is advantageous in that it is not easily broken by an external force. This structure reinforces the ability to withstand loads by using a continuous reinforced fiberglass frame.

In addition, the wear layer 210 is formed to prevent the surface from being easily worn, and can be manufactured by hopping a quartz, a wear resistant material, and a light stabilizer. Such a wear layer 210 can be applied to the surface of a manhole cover by fusing the art of door art, the art of brass art, and the art of color integrally based on the demand of the user, thereby beautifully creating the beauty of the city. And by applying various colors, designs, pictures, and logos can be inserted, so that a unique design is possible. These examples are shown in Figs. 3 to 6.

The abrasive layer 210 is formed by mixing color chips, glass fibers, anti-discoloration-preventive glass fibers, and anti-shrinkage agents so as to provide various colors as required. The glass fiber is excellent in heat resistance, flame retardancy, And corrosion resistance according to excellent chemical durability, excellent tensile strength and small elongation, while preventing the discoloration when installed at a position receiving light such as a road. For this, 1 part by weight of STEPOL 040-4923SP and 10 parts by weight of anti-shrinkage agent (water-shrinking agent, AT10) as 10 parts by weight of color chips (2 kg, for example), 10 parts by weight of glass fibers (1 kg, (For example, 0.1 Kg). This will be described in more detail with reference to FIG.

2 is a cross-sectional view illustrating a synthetic resin manhole cover according to a second embodiment of the present invention.

The synthetic resin manhole cover according to the second embodiment of the present invention is formed so as to have a convex shape in the lower layer from the upper layer to the inner circumference from the outer periphery to increase the thickness at the center to further strengthen the structural bearing load.

In other words, the thickness increases toward the center, and the ability to withstand the load is superior to the uniform thickness. Further, when layers having different materials are stacked, mutual engagement of the layers increases the force against the load.

To this end, in the second embodiment of the present invention, the first synthetic resin layer, the first glass fiber monolayer, the second synthetic resin layer, the second glass fiber monolayer, the third synthetic resin layer, the third glass fiber monolayer, A fourth synthetic resin layer and a wear layer are sequentially laminated.

Here, the first to fourth synthetic resin layers absorb most of the load and absorb and partially disperse the load. The first to fourth synthetic resin layers are made of a reinforcing fiber frame (frame) so that they are made into a shape fit to the metal mold and have elasticity, so that they are not easily broken by an external force.

As described above, the synthetic resin is mainly composed of unsaturated polyester resin (Unsaturated Polyester). The unsaturated polyester resin is a polymer compound belonging to thermosetting plastic. It is made of a resin having a polymerizable double bond and having a molecular weight of about 500 to 4,000 Vinyl units are used to cure to form moldings. Such an unsaturated polyester resin is useful for preventing separation and separation phenomenon. In addition, wear resistance can be increased and the service life can be doubled. Here, the second synthetic resin layer is formed to have a convex shape so as to further increase the thickness from the outer circumferential surface to the central lower portion of the inner circumferential surface to further strengthen the structural bearing load.

The first to third reinforcing fiber monolayers are used for preventing the manhole cover from being split. The glass fiber used as the reinforcing fiber is a mineral fiber in which the molten glass is formed into a fiber shape. The glass fiber is excellent in heat resistance and flame retardancy It has low absorbency and low hygroscopicity. In addition, glass fiber has excellent chemical durability and therefore does not corrode, has excellent tensile strength and low elongation.

The abrasion layer is intended to prevent the surface from being easily worn, and can be produced by mixing color chips, glass fibers, discoloration-inhibiting glass fiber and anti-shrinkage agent. This wear layer can be applied to the surface of the manhole cover by integrating the art of the door, the art of the weak and the art of the color based on the demand of the user, so that the beauty of the city can be beautifully created. And by applying various colors, designs, pictures, and logos can be inserted, so that a unique design is possible. These examples are shown in Figs. 4 to 7.

These abrasive layers are made by mixing color chips, glass fibers, discoloration-preventive glass fibers and anti-shrinkage agents to provide various colors as required, and through glass fibers, excellent heat resistance, flame retardancy, low water absorption, hygroscopicity and chemical durability It is possible to prevent discoloration when it is installed at a location receiving light such as roads while maintaining characteristics of corrosion resistance, excellent tensile strength and small elongation according to storm. For this, 1 part by weight of STEPOL 040-4923SP and 10 parts by weight of anti-shrinkage agent (water-shrinking agent, AT10) as 10 parts by weight of color chips (2 kg, for example), 10 parts by weight of glass fibers (1 kg, (For example, 0.1 Kg). This will be described in more detail with reference to FIG.

3 is a cross-sectional view illustrating a synthetic resin manhole cover according to a third embodiment of the present invention.

The synthetic resin manhole cover according to the third embodiment of the present invention is formed so as to have an entassical shape convex upward in the lower layer from the outer peripheral face to the inner peripheral face and serves as a step for preventing a high speed running to assist the walking of the pedestrian among the roads Thereby increasing the thickness of the central portion, thereby further strengthening the structural load.

That is, the thickness is increased toward the center portion and has an entasis shape at the upper portion. Such a structure is excellent in the ability to withstand a load as compared with a uniform thickness. Further, when layers having different materials are stacked, mutual engagement of the layers increases the force against the load.

For this, in the third embodiment of the present invention, the first synthetic resin layer, the first glass fiber monolayer, the second synthetic resin layer, the second glass fiber monolayer, the third synthetic resin layer, the third glass fiber monolayer, A fourth synthetic resin layer and a wear layer are sequentially laminated.

Here, the first to fourth synthetic resin layers absorb most of the load and absorb and partially disperse the load. The first to fourth synthetic resin layers are made of a reinforcing fiber frame (frame) so that they are made into a shape fit to the metal mold and have elasticity, so that they are not easily broken by an external force.

As described above, the synthetic resin is mainly composed of unsaturated polyester resin (Unsaturated Polyester). The unsaturated polyester resin is a polymer compound belonging to thermosetting plastic. It is made of a resin having a polymerizable double bond and having a molecular weight of about 500 to 4,000 Vinyl units are used to cure to form moldings. Such an unsaturated polyester resin is useful for preventing separation and separation phenomenon. In addition, wear resistance can be increased and the service life can be doubled. Here, the third synthetic resin layer has an entasis shape in which the thickness increases from the outer circumferential surface to the central portion of the inner circumferential surface.

The first to third reinforcing fiber monolayers are used for preventing the manhole cover from being split. The glass fiber used as the reinforcing fiber is a mineral fiber in which the molten glass is formed into a fiber shape. The glass fiber is excellent in heat resistance and flame retardancy It has low absorbency and low hygroscopicity. In addition, glass fiber has excellent chemical durability and therefore does not corrode, has excellent tensile strength and low elongation.

The abrasion layer is intended to prevent the surface from being easily worn, and can be produced by mixing color chips, glass fibers, discoloration-inhibiting glass fiber and anti-shrinkage agent. This wear layer can be applied to the surface of the manhole cover by integrating the art of the door, the art of the weak and the art of the color based on the demand of the user, so that the beauty of the city can be beautifully created. And by applying various colors, designs, pictures, and logos can be inserted, so that a unique design is possible. These examples are shown in Figs. 4 to 7.

These abrasive layers are made by mixing color chips, glass fibers, discoloration-preventive glass fibers and anti-shrinkage agents to provide various colors as required, and through glass fibers, excellent heat resistance, flame retardancy, low water absorption, hygroscopicity and chemical durability It is possible to prevent discoloration when it is installed at a location receiving light such as roads while maintaining characteristics of corrosion resistance, excellent tensile strength and small elongation according to storm. For this, 1 part by weight of STEPOL 040-4923SP and 10 parts by weight of anti-shrinkage agent (water-shrinking agent, AT10) as 10 parts by weight of color chips (2 kg, for example), 10 parts by weight of glass fibers (1 kg, (For example, 0.1 Kg). This will be described in more detail with reference to FIG.

FIGS. 4 to 7 are views showing products to which a synthetic resin manhole cover according to the present invention can be applied.

4 to 7 show a design example of a manhole cover of a police station, FIG. 5 shows an example of a design of a manhole cover for a traffic signal, FIG. 6 FIG. 7 is a design example of a manhole cover of the Korea Gas Corporation. At this time, the manhole cover shown is a surface exposed to the ground, showing that various colors and designs are performed.

8 is a flowchart illustrating a method of manufacturing a synthetic resin manhole cover according to the present invention.

8, a synthetic resin manhole cover is manufactured by kneading 20 parts by weight (e.g., 2 kg) of a color chip, glass fiber, discoloration-preventive glass fiber and anti-shrinkage agent on a color chip, STEPOL 040-4923SP and 10 parts by weight of anti-discoloration-resistant glass fiber (S100) and 10 parts by weight of glass fiber (1 kg, for example) are prepared.

Then, the prepared color chips, glass fiber, discoloration preventing glass fiber and anti-shrinkage agent are mixed in a blender (S110).

The mixed material is then sprayed on a mold with a splay unit and cured as a wear layer (S120).

Next, a synthetic resin layer and a glass fiber cloth are alternately laminated on the cured abrasion layer in three or more layers respectively to complete a manhole cover having a desired thickness (S130). After the completion of the manhole cover, the necessary design can be performed on the wear layer. At this time, the synthetic resin layer and the glass fiber fabric may have the same structure as that of the first or second embodiment of the present invention.

Although the present invention has been described with reference to the above examples, the present invention is not necessarily limited to these examples, and various modifications may be made without departing from the technical idea of the present invention. Therefore, the examples disclosed in the present invention are not intended to limit the scope of the present invention and are not intended to limit the scope of the present invention. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

100: first synthetic resin layer 110: first glass fiber fabric
120: second synthetic resin layer 130: second glass fiber fabric
140: third synthetic resin layer 150: third glass fiber fabric
160: n-2 th synthetic resin layer 170: n-1 th glass fiber fabric
180: n-1 th synthetic resin layer 190: n-1 th glass fiber fabric
200: nth synthetic resin layer 210: wear layer

Claims (6)

In a manhole cover manufactured by using a synthetic resin having an unsaturated polyester (Unsaturated Polyester) resin as a raw material,
Color chips, glass fiber, anti-discoloration-preventing glass fiber, and anti-shrinkage agent were mixed so as to give various colors as necessary, and 20 parts by weight of a color chip, 10 parts by weight of glass fiber (VUP 3518) part. 10 parts by weight of discoloration preventive glass fiber (STYPOL 040-4923SP) and 1 part by weight of anti-shrinkage agent (water-reducing agent, AT10)
A synthetic resin layer having a polymerizable double bond and having a molecular weight of about 500 to 4,000 and being cured by using a vinyl unit to form a molded product,
A glass fiber cloth which has a function of absorbing the load of the manhole cover and dispersing it to the periphery but is made of a reinforcing fiber frame (frame) so that it is made into a shape fit to the mold and has elasticity and is not easily broken by an external force Respectively,
Wherein the synthetic resin layer and the glass fiber cloth are laminated alternately in order of at least three to ten layers in order.
The method according to claim 1,
Wherein the synthetic resin manhole cover has a convex shape protruding from an outer circumferential surface to a lower inner circumferential surface or formed to have an entasis shape from an outer circumferential surface to an upper surface of an inner circumferential surface.
The method according to claim 1,
The synthetic resin layer is made of a mixture of quartz and synthetic resin. The synthetic resin is made of Unsaturated Polyester resin as a raw material, and has a polymerizable double bond having a molecular weight of about 500 to 4,000, Wherein the synthetic resin manhole cover is formed by curing using a synthetic resin.
The method according to claim 1,
The abrasion layer,
Color chips, glass fibers, discoloration resistant glass fibers and anti-shrinkage agents are mixed to give various colors as required, with 20 parts by weight of color chips and 10 parts by weight of glass fibers (VUP 3518). 10 parts by weight of discoloration-preventive glass fiber (STYPOL 040-4923SP) and 1 part by weight of anti-shrinkage agent (water-reducing agent, AT10) are mixed.
In a manhole cover manufactured by using a synthetic resin having an unsaturated polyester (Unsaturated Polyester) resin as a raw material,
(2 Kg) of a color chip, 10 parts by weight (for example, 1 Kg) of a glass fiber, and a color chip, glass fiber, anti-discoloration-preventing glass fiber and anti-shrinkage agent, VUP 3518, a wear layer formed by mixing STEPOL 040-4923SP with 10 parts by weight of discoloration-preventive glass fiber and 1 part by weight (e.g., 0.1 Kg) of an anti-shrinkage agent (AT10);
A first synthetic resin layer formed as a lower layer from the bottom of the abrasion layer to prevent the manhole cover from being split;
A first glass fiber monolayer formed below the first synthetic resin layer and absorbing a load and dispersing the load around;
A second synthetic resin layer formed below the first glass fiber monolayer and formed in a convex shape from the outer circumferential surface to the inner circumferential surface downward to prevent the manhole cover from being split;
A second glass fiber monolayer formed in the lower portion of the second synthetic resin layer to have a uniform thickness to absorb a load and disperse the load around;
A third synthetic resin layer formed below the second glass fiber monolayer and having a uniform thickness on the second glass fiber monolayer to prevent the manhole cover from being split;
A third glass fiber monolayer formed in a lower portion of the third synthetic resin layer to absorb the load and disperse the load to the surroundings;
And a fourth synthetic resin layer formed at a lower portion of the third glass fiber raw layer so as to prevent the manhole cover from being split.
A method for manufacturing a manhole cover using a synthetic resin having an unsaturated polyester (Unsaturated Polyester) resin as a raw material,
20% by weight of color chips and 10% by weight of glass fiber (VUP 3518) as a flat abrasive layer. 10 parts by weight of discoloration-preventive glass fiber (STYPOL 040-4923SP) and 1 part by weight of an anti-shrinkage agent (AT10);
Mixing the prepared color chips, glass fibers, discoloration preventing glass fiber and anti-shrinkage agent in a blender;
Spraying the mixed material onto a mold with a splay unit, and curing the mixed material as the wear layer; And
And laminating at least three layers of a synthetic resin layer and a glass fiber cloth to the hardened abrasion layer to complete a manhole cover having a desired thickness.

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