Fiber-reinforced polymer for reinforcing bar comprising glycol oligomer derived from waste pet

Abstract

The present invention relates to a fiber-reinforced polymer for reinforcing a bar comprising a glycol oligomer derived from waste PET. More specifically, disclosed is a fiber-reinforced polymer for reinforcing a bar comprising a glycol oligomer derived from waste PET, the polymer comprising: an impregnating agent composition including 100 parts by weight of vinyl ester resin, 0.1 to 3 parts by weight of an antifoaming agent, 0.5 to 3 parts by weight of a free radical initiator, and 0.1 to 25 parts by weight of a filler; and fibers comprising at least one selected from glass fiber, basalt fiber, and carbon fiber, wherein the vinyl ester resin includes 15-50 wt % of a glycol oligomer obtained by depolymerizing waste polyethylene terephthalate (PET) to have a wide molecular weight distribution, thereby improving tensile strength of the polymer due to increased interaction between the vinyl ester resin and the fiber. According to the fiber-reinforced polymer for reinforcing a bar including a glycol oligomer derived from waste PET of the present invention, the vinyl ester resin including a glycol oligomer derived from waste PET has a high molecular weight with low brittleness and a wide molecular weight distribution, resulting in various intermolecular interactions that facilitate stress transfer against external forces, thereby improving the tensile strength of the fiber-reinforced polymer.

Description

Fiber-reinforced composite for reinforcing bars containing glycol oligomers derived from waste PET

[0001] The present invention relates to a fiber-reinforced composite for reinforcing bars comprising a glycol oligomer derived from waste PET, and more particularly, to a fiber-reinforced composite for reinforcing bars comprising a glycol oligomer derived from waste PET, wherein the vinyl ester resin constituting the fiber-reinforced composite includes a glycol oligomer obtained by depolymerizing waste polyethylene terephthalate (PET), and has a broad molecular weight distribution, thereby increasing the interaction between the vinyl ester resin and fibers, thereby improving the tensile strength.

[0002] As a building material, concrete possesses strong compressive strength but low tensile strength. Therefore, reinforced concrete structures, which incorporate reinforcing bars and allow them to cure, are commonly used. However, the surfaces of concrete structures containing reinforcing bars are usually exposed to the outside, making them susceptible to corrosion from various environmental factors, thereby reducing their strength. This corrosion damages the interface between concrete and reinforcing bars, reducing bond strength and ultimately weakening the reinforcing bars' structural integrity. Furthermore, as civil engineering structures age, periodic maintenance and reinforcement become increasingly necessary.

[0003] To solve these problems, research on materials that can replace steel bars is increasing, and fiber-reinforced polymer (FRP) composites for reinforcing bars are being actively developed recently.

[0004] Typically, to enhance the properties of fiber-reinforced composites, a resin with a narrow molecular weight distribution is used. While this may slightly improve the resin's properties, the lack of intermolecular interaction hinders the smooth transmission of stress from external forces to the glass fibers, resulting in reduced strength. Furthermore, increasing the resin's molecular weight while narrowing its molecular weight distribution can lead to brittleness, making the material susceptible to impact fracture.

[0005] Meanwhile, polyethylene terephthalate (PET) is a thermoplastic resin, the most common material used in everyday life, including the packaging industry. It exists in an amorphous or semi-crystalline state. During the manufacturing process, approximately 5-10% of PET production is in an under-polymerized state, forming oligomers. This amount, which is discharged domestically, amounts to 20,000-30,000 tons. This waste is entirely incinerated, causing secondary pollution. Furthermore, the disposal of recyclable materials leads to significant economic losses.

[0006] To address the above issues, research is underway to recycle waste PET into polyester flakes (physical recycling) or to recover it as raw monomers through chemical reactions (chemical recycling). Of these, chemical recycling is considered the most economically and environmentally desirable method.

[0007] In relation to this, Korean Patent No. 10-2545381 discloses a method for manufacturing an eco-friendly, corrosion-resistant, pultruded vinyl ester resin using recycled polyethylene terephthalate flakes, in which a method for manufacturing a vinyl ester resin is disclosed using a glycol oligomer obtained by depolymerizing waste PET. However, there has been no review at all of a technology for applying a vinyl ester resin containing an oligomer derived from waste PET to a reinforcing bar using fibers.

[0008] Accordingly, the inventors of the present invention have confirmed that by applying a vinyl ester resin having a wide molecular weight distribution, including a glycol oligomer obtained by depolymerization of waste PET, to a fiber-reinforced composite for reinforcing bars, stress transfer to glass fibers of the fiber-reinforced composite can be maximized, thereby improving mechanical properties such as tensile strength, and have completed the present invention.

[0009] Accordingly, the present invention has as a technical solution the problem of providing a fiber-reinforced composite for reinforcing bars containing a glycol oligomer derived from waste PET.

[0010] In order to solve the above technical problem, the present invention,

[0011] An impregnating composition comprising 100 parts by weight of vinyl ester resin, 0.1 to 3 parts by weight of a defoaming agent, 0.5 to 3 parts by weight of a free radical initiator, and 0.1 to 25 parts by weight of a filler; and

[0012] A fiber-reinforced composite material comprising at least one fiber selected from glass fiber, basalt fiber, and carbon fiber,

[0013] The above vinyl ester resin has a wide molecular weight distribution (weight average molecular weight / number average molecular weight) including 15 to 50 wt% of glycol oligomer obtained by depolymerizing waste polyethylene terephthalate (PET), and is characterized in that the tensile strength of the composite is improved.

[0014] A fiber-reinforced composite for reinforcing bars comprising a glycol oligomer derived from waste PET is provided.

[0015] In the present invention, the vinyl ester resin is characterized in that the molecular weight distribution is at least 5.

[0016] In the present invention, the vinyl ester resin is characterized by having a number average molecular weight of 1,000 to 3,000 g / mol and a weight average molecular weight of 5,000 to 30,000 g / mol.

[0017] In the present invention, the fiber-reinforced composite is characterized in that it has a tensile strength of at least 1000 MPa.

[0018] In addition, in the present invention, it is characterized in that the impregnating composition and fibers are included in a weight ratio of 10:90 to 30:70.

[0019] According to the fiber-reinforced composite for reinforcing bars comprising the glycol oligomer derived from waste PET of the present invention, the vinyl ester resin comprising the glycol oligomer derived from waste PET has a high molecular weight but low brittleness, and has a wide molecular weight distribution, so that interactions between molecules are diverse and stress transfer in response to external force is easy, thereby having the effect of improving the tensile strength of the fiber-reinforced composite comprising the vinyl ester resin.

[0020] Figure 1 is a schematic diagram of a fiber-reinforced composite for reinforcing bars according to molecular weight distribution.

[0021] The present invention is described in detail below.

[0022] The present invention is susceptible to various modifications and takes various forms, and thus, embodiments are described in detail herein. However, this is not intended to limit the present invention to a specific disclosed form, but rather to encompass all modifications falling within the spirit and technical scope of the present invention.

[0023] Additionally, throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0024]

[0025]

[0026] The present invention relates to a fiber-reinforced composite for reinforcing bars comprising a glycol oligomer derived from waste PET, which has improved tensile strength by increasing the interaction between the vinyl ester resin and fibers by applying a vinyl ester resin comprising a glycol oligomer derived from waste PET to manufacture the fiber-reinforced composite for reinforcing bars.

[0027] In one aspect, the present invention relates to a fiber-reinforced composite for reinforcing bars comprising a glycol oligomer derived from waste PET, comprising: an impregnating composition comprising 100 parts by weight of a vinyl ester resin, 0.1 to 3 parts by weight of a defoaming agent, 0.5 to 3 parts by weight of a free radical initiator, and 0.1 to 25 parts by weight of a filler; and a fiber selected from at least one of glass fiber, basalt fiber, and carbon fiber, wherein the vinyl ester resin comprises 15 to 50 wt% of a glycol oligomer obtained by depolymerizing waste polyethylene terephthalate (PET), and has a broad molecular weight distribution (weight-average molecular weight / number-average molecular weight), thereby improving the tensile strength of the composite due to increased interaction between the vinyl ester resin and the fiber.

[0028] The above fiber-reinforced composite for reinforcing bars can be manufactured by impregnating fibers into a molten body of an impregnating agent composition containing a vinyl ester resin, a defoaming agent, a free radical initiator, and a filler, and forming and drying the fibers into a rod shape.

[0029] The above vinyl ester resin is one of the polymer resins that acts as a binder for fibers in fiber-reinforced composites. It has acrylic groups at both ends of the molecule and the ester bonds are located only at both ends of the molecule, so it has no unreacted double bonds compared to general unsaturated resins and does not change even when subjected to chemical shocks such as oxidation and halogenation, so it is commonly used as a corrosion-resistant resin because it provides super corrosion resistance.

[0030] In the present invention, the vinyl ester resin is characterized in that it has a broad molecular weight distribution (weight average molecular weight / number average molecular weight) by including 15 to 50 wt% of a glycol oligomer obtained by depolymerizing waste polyethylene terephthalate (PET). According to one embodiment of the present invention, the glycol oligomer can be prepared through a depolymerization reaction of waste PET flakes, glycol, and phthalic anhydride at 220°C in the presence of a zinc acetate catalyst, and then 2-hydroxyethyl acrylate (2-HEA), maleic anhydride, triethylamine, and toluhydroquinone are added to the glycol oligomer derived from waste PET prepared by the reaction and reacted at 110°C for 1 hour to prepare a monobasic acid oligomer, which is then reacted with an epoxy resin to prepare an epoxy resin-modified vinyl ester resin having a specific acid value. Next, a vinyl ester resin for reinforcing bars can be manufactured by adding methylhydroquinone to the epoxy resin-modified vinyl ester resin and diluting it with styrene monomer.

[0031] At this time, when the glycol oligomer derived from the waste PET is added in an amount of less than 15 wt%, the hydroxyl value of the oligomer increases, so that the amount of epoxy resin required for manufacturing the epoxy resin-modified vinyl ester resin increases, thereby increasing the manufacturing cost, and the vinyl ester resin for reinforcing bars manufactured therefrom has a low molecular weight distribution, which cannot cause a change in the interaction between the fiber and the resin, and when it exceeds 50 wt%, the vinyl ester resin for reinforcing bars is manufactured with a high viscosity, which may cause gelation, and has a problem of poor fiber impregnation.

[0032] Specifically, the glycol oligomer derived from waste PET is manufactured through a glycolysis reaction of waste PET flakes and thus has a low purity. Therefore, when the oligomer is added to a vinyl ester resin, the resin has a broad molecular weight distribution, thereby maximizing stress transfer to glass fibers, a key component of fiber-reinforced composites for reinforcing bars, thereby improving mechanical properties, including tensile strength.

[0033] In relation to this, Fig. 1 is a schematic diagram of a fiber-reinforced composite for reinforcing bars according to molecular weight distribution. Fig. 1(a) shows the composite of the present invention having a high molecular weight and a wide molecular weight distribution, and Fig. 1(b) shows a conventional composite having a low molecular weight and a narrow molecular weight distribution. Referring to Fig. 1(b), it can be confirmed that the fiber-reinforced composite for reinforcing bars of the present invention has greater intermolecular interaction compared to the prior art.

[0034] In the present invention, the vinyl ester resin is characterized by having a molecular weight distribution of at least 5. Since the vinyl ester resin, which is the main component of the impregnating agent composition for impregnating fibers, has a molecular weight distribution of at least 5, the interaction between the resin and fibers becomes diverse and stress transmission in response to external force becomes easy, thereby improving the tensile strength of a fiber-reinforced composite manufactured therefrom.

[0035] The above molecular weight distribution is calculated as the value of (weight average molecular weight / number average molecular weight), and each value can be measured using gel permeation chromatography (GPC).

[0036] In the present invention, the vinyl ester resin is characterized by having a number average molecular weight of 1,000 to 3,000 g / mol and a weight average molecular weight of 5,000 to 30,000 g / mol. Preferably, the number average molecular weight may be 1,500 to 2,000 g / mol and the weight average molecular weight may be 7,500 to 10,000 g / mol.

[0037] If the number average molecular weight of the vinyl ester resin is less than 1,000 g / mol, the mechanical properties deteriorate, and if it exceeds 3,000 g / mol, the processability deteriorates due to high viscosity. At the same time, if the weight average molecular weight of the vinyl ester resin is less than 5,000 g / mol, the mechanical properties deteriorate, and if it exceeds 30,000 g / mol, the processability may deteriorate due to high viscosity.

[0038] In the present invention, the fiber-reinforced composite is characterized by a tensile strength of at least 1,000 MPa. That is, the tensile strength required for reinforcing bars is typically 1,000 to 2,000 MPa, and the fiber-reinforced composite of the present invention exhibits sufficient tensile strength, thereby possessing properties suitable for reinforcing bars. More preferably, the tensile strength may be 1,000 to 1,600 MPa.

[0039] In the impregnating composition of the present invention, the defoaming agent prevents deterioration in strength and durability by removing air bubbles generated in the fiber-reinforced composite composition. The type of the defoaming agent is not particularly limited, but is preferably at least one selected from the group consisting of silicone compounds, fluorine compounds, and acrylic compounds. The content of the defoaming agent is 0.1 to 3 parts by weight based on 100 parts by weight of vinyl ester resin. If the content of the defoaming agent is less than 0.1 parts by weight, air bubbles are not removed, which may result in deterioration in strength and durability. If the content of the defoaming agent exceeds 3 parts by weight, the effect is no longer generated, resulting in a decrease in cost-effectiveness, and deformation of the product surface due to plasticization may occur.

[0040] In addition, in the impregnating composition of the present invention, the free radical initiator is used for polymerization and curing of unsaturated monomers, and is included in an amount of 0.7 to 3 parts by weight based on 100 parts by weight of vinyl ester resin. If the content of the free radical initiator is less than 0.7 parts by weight, radical polymerization may require a long period of time and non-curing may occur, and if it exceeds 3 parts by weight, a rapid reaction may occur, resulting in many cracks.

[0041] The free radical initiator may preferably be an organic peroxide, an organic hydroperoxide, or an azo initiator. Specifically, the organic peroxide includes, but is not limited to, compounds such as benzoyl peroxide, di-t-amyl peroxide, t-butyl peroxy benzoate, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3, and di-cumyl peroxide. Useful organic hydroperoxides include, but are not limited to, compounds such as t-amyl hydroperoxide and t-butyl hydroperoxide. Useful azo initiators may include, but are not limited to, 2,2'-azobis(2,4-dimethylpentanenitrile), 2,2'-azobis(2-methylpropanenitrile), 2,2'-azobis(2-methylbutanenitrile), and 2,2'-azobis(cyclohexanecarbonitrile).

[0042] In addition, in the impregnating composition of the present invention, the filler serves to impart flame retardancy, and is added in an amount of 0.1 to 25 parts by weight per 100 parts by weight of the vinyl ester resin. When the content of the additive is less than 0.1 parts by weight, the viscosity decreases and separation from the resin occurs, and when it exceeds 25 parts by weight, it may be difficult to uniformly disperse the filler in the resin component during mixing, and the viscosity may increase, resulting in problems of deterioration of physical properties.

[0043] The above filler may be selected from one or more of calcium carbonate, magnesium carbonate, barium sulfate, mica, talc, kaolin, cerite, asbestos, barite, barite, silica, silica sand, dolomite, limestone, gypsum, aluminum powder, alumina, kaolinite, zirconium oxide, antimony oxide, titanium oxide, and mixtures thereof, but is not limited thereto.

[0044] In addition, the fiber is included to provide effects such as water resistance and chemical resistance along with high mechanical strength, and may be selected from at least one of glass fiber, basalt fiber, and carbon fiber.

[0045] In the present invention, the impregnating composition and the fibers are characterized by being included in a weight ratio of 10:90 to 30:70. If the weight ratio is outside the above range, the manufactured reinforcing bar may have a tensile strength of 1,000 MPa or less, or the fibers may not be sufficiently impregnated with the impregnating composition, making it difficult to manufacture the reinforcing bar. More preferably, the composition may be composed of 20 parts by weight of the impregnating composition and 80 parts by weight of the fibers.

[0046]

[0047] In this way, the present invention manufactures a fiber-reinforced composite for reinforcing bars using a vinyl ester resin and fibers having a wide molecular weight distribution, including 15 to 50 wt% of a glycol oligomer derived from waste PET, thereby maximizing stress transfer within the composite and securing improved tensile strength.

[0048]

[0049] Hereinafter, the present invention will be described in detail with examples, but the present invention is not limited thereto.

[0050]

[0051] <Materials>

[0052] Fiberglass: PS4100 4800 / Owens Corning

[0053] Defoamer: BYK-A530 / BYK

[0054] Free radical initiator: Bis(tert-butylcyclohexyl)peroxydicarbonate,

[0055] tert-Butyl peroxy-2-ethylhexanoate, tert-Butyl peroxybenzoate

[0056]

[0057] *Filler: Al(OH)3 8㎛ / Osung Enterprise

[0058]

[0059] <Example 1> Preparation of vinyl ester resin

[0060] Manufacturing of glycol oligomers derived from waste PET

[0061] 410 parts by weight of waste PET flakes, 310 parts by weight of glycol including diethylene glycol, neopentyl glycol and propylene glycol, 300 parts by weight of phthalic anhydride and 0.10 parts by weight of zinc acetate are mixed in a 2 L flask under a nitrogen atmosphere at elevated temperature and then a glycolysis depolymerization reaction is performed at 220°C. During the reaction, the hydroxyl value of the reaction product by glycolysis is measured, and the reaction is terminated when the value is 110 to 150, thereby producing a product.

[0062] Vinyl ester resin manufacturing

[0063] 250 parts by weight of a glycol oligomer derived from waste PET is added with 60 parts by weight of 2-hydroxyethyl acrylate (2-HEA), 80 parts by weight of maleic anhydride, 0.25 parts by weight of triethylamine, and 0.06 parts by weight of toluhydroquinone, and the mixture is heated to 110°C and reacted for 1 hour to produce a monobasic acid oligomer having an acid value of 120 to 150.

[0064] 100 parts by weight of epoxy resin YD-128 (Kukdo Chemical) and 40 parts by weight of YD-011 (Kukdo Chemical) are added to the monobasic acid oligomer manufactured above, and the reaction is maintained at 100 to 110°C until the designed acid value is reached, and then terminated to manufacture an epoxy resin-modified vinyl ester resin. Finally, the manufactured resin is diluted with 0.10 parts by weight of methylhydroquinone and 300 parts by weight of styrene monomer to manufacture a vinyl ester resin for reinforcing bars with excellent stress transfer.

[0065]

[0066] Comparative Examples 1-3

[0067] Comparative Examples 1 and 2 produced vinyl ester resins in the same manner as Example 1, except that the content of glycol oligomer derived from waste PET was added in amounts of 80 parts by weight and 650 parts by weight, respectively. Comparative Example 3 used Aekyung Chemical's PLF-1001 product.

[0068]

[0069] <Example 1>

[0070] Molecular weight: Measured using a molecular weight test method for polymer solutions using gel permeation chromatography.

[0071] The measurement results of the above examples and comparative examples 1 to 3 are as shown in Table 1 below.

[0072] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Number average molecular weight (g / mol) 1,683 1,198-986 Weight average molecular weight (g / mol) 8,746 2,796-1,468 Molecular weight distribution 5.19 2.33-1.48

[0073] According to Table 1 above, the vinyl ester resin manufactured in the example contained 30 wt% of a glycol oligomer derived from waste PET, and showed a number average molecular weight of 1,683 g / mol, a weight average molecular weight of 8,746 g / mol, and a broad molecular weight distribution of 5.19, whereas Comparative Example 1, which contained 12 wt% of a glycol oligomer derived from waste PET, showed a number average molecular weight of 1,198 g / mol, a weight average molecular weight of 2,796 g / mol, and a narrow molecular weight distribution of 2.33, and Comparative Example 2, which contained 53 wt% of a glycol oligomer derived from waste PET, was gelled during the resin manufacturing process, making molecular weight measurement impossible. In addition, Comparative Example 3, which is a commercial resin, showed a number average molecular weight of 986 g / mol, a weight average molecular weight of 1,468 g / mol, and a very narrow molecular weight distribution of 1.48. Through this, it was confirmed that the molecular weight distribution of the vinyl ester resin containing 30 wt% of glycol oligomers derived from low-purity waste PET had 5 or more.

[0074]

[0075] <Example 2> Manufacturing of fiber-reinforced composites

[0076] For 100 parts by weight of the vinyl ester resins of Example 1, Comparative Example 1, and Comparative Example 3, 0.5 parts by weight of an antifoaming agent, 1 part by weight of a free radical initiator, and 5 parts by weight of a filler were added and mixed with a stirrer to prepare an impregnating composition. After impregnating a glass fiber bundle into the impregnating composition, it was injected into a mold and cured at high temperature to produce a cylindrical reinforcing bar.

[0077] Comparative examples 4-7

[0078] Comparative Examples 4 and 5 were performed in the same manner as Example 2, but the weight ratio of the impregnating agent composition:glass fiber was applied as 40:60 and 5:95, respectively, instead of 20:80. Comparative Examples 6 and 7 were manufactured using Comparative Examples 1 and 3, respectively, instead of Example 2, with vinyl ester resin.

[0079]

[0080] The composition ratios according to the above Example 2 and Comparative Examples 4 to 6 are shown in Table 2.

[0081] Ingredients Example 2 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Impregnation Composition Vinyl Ester Resin Example 1 100 100 100 Comparative Example 1 100 Comparative Example 3 100 Defoamer 0.5 0.5 0.5 0.5 Free Radical Initiator 1 11 11 Filler 5 5 5 5 Fiber Reinforced Composite Impregnation Composition 2 0 4 0 5 2 0 20 Glass Fiber 8 0 6 0 9 5 8 0 80 System 1 0 10 0 10 0 10 0 10 0

[0082] <Example 2>

[0083] Tensile strength: Specimens were manufactured in the form of GFRP rebar and measured using the tensile properties test method of KS F ISO10406-1.

[0084]

[0085] The tensile strength measurement results according to the above Example 2 and Comparative Examples 4 to 6 are as shown in Table 3 below.

[0086] Example 2 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Tensile strength (MPa) 1,294,680-980,954

[0087] Referring to Table 3 showing the tensile strength of the reinforcing bars manufactured according to the above Example 2 and Comparative Examples 4 to 6, in the case of Example 2, which was manufactured using the vinyl ester resin of Example 1 and at a weight ratio of impregnating composition:glass fiber of 20:80, the tensile strength of the reinforcing bar was 1,294 MPa, whereas Comparative Example 4, in which the weight ratio of impregnating composition:glass fiber was 40:60, had a tensile strength of 680 MPa, and in Comparative Example 5, in which the weight ratio of impregnating composition:glass fiber was 5:95, the fiber bundle was not sufficiently impregnated with the impregnating composition, so the tensile strength could not be measured. Therefore, it was confirmed that the reinforcing bar exhibited a tensile strength of 1,000 MPa or more at a weight ratio of 20:80 of the impregnating composition and glass fiber containing the glycol oligomer derived from waste PET. In addition, Comparative Example 5, which had the same weight ratio of impregnating composition:glass fiber as Example 2, As a result of comparing 6, the reinforcing bar (Comparative Example 6) manufactured with vinyl ester resin containing 12 wt% of glycol oligomer derived from waste PET and having a molecular weight distribution of 2.33 showed 980 MPa, and Comparative Example 7 using commercial resin showed 954 MPa, whereas the reinforcing bar (Example 1) manufactured with vinyl ester resin containing 30 wt% of glycol oligomer derived from waste PET and having a molecular weight distribution of 5.19 showed an improved tensile strength of 1,294 MPa.

[0088] Through this, it can be confirmed that the vinyl ester resin including the glycol oligomer derived from waste PET of the present invention has a wide molecular weight distribution, and thus the reinforcing bar manufactured therefrom can maximize stress transfer to glass fibers and improve tensile strength, and thus can be effectively applied to reinforcing bars.

[0089]

[0090] The above description is merely an illustrative description of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of ​​the present invention, but rather to illustrate it, and the scope of the technical idea of ​​the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

[0091] According to the fiber-reinforced composite for reinforcing bars comprising the glycol oligomer derived from waste PET of the present invention, the vinyl ester resin comprising the glycol oligomer derived from waste PET has a high molecular weight but low brittleness, and has a wide molecular weight distribution, so that interactions between molecules are diverse and stress transfer in response to external force is easy, thereby having the effect of improving the tensile strength of the fiber-reinforced composite comprising the vinyl ester resin.

Claims

1. An impregnating composition comprising 100 parts by weight of vinyl ester resin, 0.1 to 3 parts by weight of a defoaming agent, 0.5 to 3 parts by weight of a free radical initiator, and 0.1 to 25 parts by weight of a filler; and A fiber-reinforced composite material comprising at least one fiber selected from glass fiber, basalt fiber, and carbon fiber, The above vinyl ester resin has a wide molecular weight distribution (weight average molecular weight / number average molecular weight) including 15 to 50 wt% of glycol oligomer obtained by depolymerizing waste polyethylene terephthalate (PET), and is characterized in that the tensile strength of the composite is improved. Fiber-reinforced composite for reinforcing bars comprising glycol oligomers derived from waste PET.

2. In paragraph 1, The above vinyl ester resin is, A fiber-reinforced composite for reinforcing bars comprising a glycol oligomer derived from waste PET, characterized in that the molecular weight distribution is at least 5.

3. In paragraph 2, The above vinyl ester resin is, A fiber-reinforced composite for reinforcing bars comprising a glycol oligomer derived from waste PET, characterized in that the number average molecular weight is 1,000 to 3,000 g / mol and the weight average molecular weight is 5,000 to 30,000 g / mol.

4. In paragraph 1, A fiber-reinforced composite for reinforcing bars comprising a glycol oligomer derived from waste PET, characterized in that the fiber-reinforced composite has a tensile strength of at least 1000 MPa.

5. In paragraph 1, A fiber-reinforced composite for reinforcing bars comprising a glycol oligomer derived from waste PET, characterized in that the impregnating composition and the fibers are included in a weight ratio of 10:90 to 30:70.

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