KR20200025746A - Method for manufacturing prepreg having high toughness, high strength and heat resistance characteristic, prepreg manufactured by the same - Google Patents

Abstract

The present invention relates to a prepreg manufacturing method and, more specifically, to a prepreg manufacturing method having excellent high toughness, high strength and heat resistant properties by controlling optimum epoxy resin synthesis, compounding technology to develop materials for manufacturing parts, and the viscosity of a mixture of an epoxy resin and a thermoplastic toughener, and to prepreg manufactured by the method.

Description

Prepreg manufacturing method having high toughness, high strength and heat resistance characteristics and prepreg manufactured by the method TECHNICAL FIELD

The present invention relates to a prepreg, and to a method for producing a prepreg having excellent high toughness, high strength and heat resistance properties by controlling the viscosity of a mixture of an epoxy resin and a thermoplastic toughening agent for developing a composite component manufacturing material. It relates to a prepreg produced by.

Prepreg is a fiber-reinforced composite made from a combination of reinforcing fibers and an uncured resin matrix, which is easy to form and harden into a final composite part, which is a golf shaft, rod, tennis or badminton racket, hockey stick. And aerospace, automotive applications such as structural materials, drive shafts, leaf springs, windmill blades, pressure vessels, flywheels, papermaking rollers, roofing materials, cables and repair / reinforcement materials for ski poles, automobiles, bicycles, marine vessels and railway vehicles. It is widely used in the manufacture of composite parts such as general industrial uses such as sports and sports.

Such prepregs are well suited for use in composite parts that are susceptible to damage, but require higher levels of prepreg to meet various requirements, such as sufficient tensile strength, damage tolerance and heat resistance. Doing.

The method of increasing the tensile strength of the composite material is to improve the surface of the reinforcing fibers and to weaken the bond strength between the resin matrix and the reinforcing fibers. There is a method of reducing or otherwise weakening the bond strength between the resin matrix and the reinforcing fibers by applying a coating or a size to the reinforcing fibers.

Another alternative is to use a lower coefficient of resin matrix. Low modulus resins here include, for example, cyanate esters or carboxy-terminated butadiene-acrylonitrile (CTBN) with elastomers and amine-terminated butadiene-acrylonitrile (ATBN) and the like. Ingredients can be used.

However, both conventional methods of improving the surface of reinforcing fibers or using low modulus resin matrices have compression characteristics such as compression after impact (CAI) strength and open hole compression (OHC) strength. The reduction can have a negative effect on damage tolerance.

Korean Unexamined Patent Publication No. 10-2015-0116787

As described above, according to the conventional prepreg manufacturing method, it is very difficult to simultaneously increase both tensile strength, compressive strength, and damage tolerance.

Accordingly, the present invention is to solve the above problems, by controlling the viscosity of the mixture of the epoxy resin and the thermoplastic toughening agent to prepare a prepreg of high quality, high strength and excellent heat resistance and the prepreg produced by The purpose is to provide.

In order to achieve the above object, the present invention, as shown in Figure 1, put a thermoplastic toughening agent in a mixed epoxy resin mixed with a bi-functional epoxy resin and a tri-functional epoxy resin of at least three functional groups, the temperature is raised to a set temperature and then The first step (S100) of preparing a first mixture by stirring until the thermoplastic toughening agent is completely dissolved while maintaining the temperature at a predetermined temperature, and adding high melting point thermoplastic particles to the first mixture and stirring until uniformly dispersed In the second step (S200) of preparing a mixture, a curing agent is added to the second mixture and stirred to prepare an epoxy resin composition, and a third step (S300) of preparing a resin paper and the resin paper on both sides of the reinforcing fiber. It provides a prepreg manufacturing method comprising a fourth step (S400) of preparing a prepreg by coating.

The first mixture prepared in the first step has a viscosity of 5000 to 10,000 poise measured at a temperature of 20 to 30 ℃ according to DIN EN ISO 3219, preferably a viscosity of 140 to 1,000 poise at 180 ℃, and also 180 ℃ It is preferable that the viscosity change slope measured at is 0.1 to 1 poise / min or less.

In addition, in the first step, the first mixture may be prepared at a heat treatment temperature of 110 ° C. or more and less than 130 ° C., and the heat treatment temperature is 120 ° C. At this time, the heat treatment execution time in the first step is not particularly limited and is performed until the thermoplastic toughening agent is completely dissolved, and it is preferable to perform about 2 hours.

In the epoxy resin composition of the present invention, the epoxy equivalent is preferably 200 to 300. Therefore, in the present invention, a high molecular weight epoxy resin having an average molecular weight (Mw) of more than 1,000 is mixed with a low molecular weight epoxy resin having an average molecular weight of less than 200.

Therefore, in the first step, the mixed epoxy resin uses at least one mixed epoxy resin independently selected from the bifunctional epoxy resin and the trifunctional or higher polyfunctional epoxy resin, which are discussed below.

The bifunctional epoxy resin is, for example, diglycidyl ether of bisphenol F (Di-glycidyl Ether of Bisphenol-F, DGEBF), diglycidyl ether of bisphenol A (Di-glycidyl Ether of Bisphenol-A, DGEBA ), Bisphenol-based epoxy resins such as di-glycidyl Ether of Bisphenol-S (DGEBS), epoxy phenol novolacs and at least one halogen element of chlorine (Cl) and bromine (Br) Any one or more selected from among these halogenated derivatives may be used, and more preferably, the difunctional epoxy resin may use diglycidyl ether bisphenol F (DGEBF).

As the trifunctional epoxy resin, for example, triglycidyl p-aminophenol (TGAP) and triglycidyl m-aminophenol (triglycidyl m-aminophenol) may be used. Other tetrafunctional epoxy resins include tetraglycidyl-4,4'-diaminodiphenylmethane and tetraglycidyl-3,3'-diaminodiphenylmethane. -3,3'-diaminodiphenylmethane) may be used.

The thermoplastic toughening agent is polyamide, copolyamide, polyimid, aramid, polyketone, polyether ketone, polyether ketone, polyether ether ketone polyetherether ketone (PEEK), polyester, polyurethane, polysulfone, polyethersulfone (PES), polytetrafluoroethylene (PTFE), hydrocarbon polymer, liquid crystal polymer, Among the elastomers and the segmented elastomers may be used alone or in combination of two or more, among which most preferably polyethersulfone (PES) may be used.

The second step (S200) is a step of preparing a second mixture by evenly dispersing the high melting point thermoplastic particles in order to improve the interlaminar toughness and impact resistance of the prepreg in the first mixture prepared in the first step (S100) to be.

The high melting point thermoplastic particles are preferably those conventionally known as powders such as thermoplastic resins, thermosetting resins, elastomers, and the like.

For example, polyamides including polyamide 6, polyamide 66, polyamide 12, etc. may be used as the thermoplastic resins that can be preferably used as the high melting point thermoplastic particles. As the thermosetting resins, epoxy resins, phenol resins, polyurethanes, melamine resins and the like can be preferably used. Moreover, core-shell type rubber fine particles obtained by graft-polymerizing another polymer on the surface of crosslinked rubber fine particles and crosslinked rubber fine particles can be used for elastomers which can be used preferably.

And the content of the high melting point thermoplastic particles can be used by appropriately adjusting the content as needed, in general, may be used about 30 parts by weight relative to the total weight of the epoxy resin composition.

The third step (S300) is a step of preparing an epoxy resin composition by adding a curing agent to the second mixture prepared in the second step and stirring it evenly, and preparing a resin paper, wherein the curing agent used may react with the epoxy group. It can be used if it is a compound which has an active group, Preferably an amine-type hardener and an acid anhydride-type hardener can be used.

For example, the amine-based curing agent is an aliphatic amine such as ethylenediamine, ethylenetriamine, triethylenetetramine, hexamethylenediamine, metaxylenediamine, M-phenylenediamine, diaminodiphenylmethane, diaminodiethyl diphenylmethane, diaminodiethyldiphenylsulfone, diaminodiethyldiphenylsulfone, and the like. Tertiary amines such as aromatic amines, benzyldimethyl amine, tetramethyl guanidine, 2,4,6-tris (dimethylaminomethyl) phenol (2,4,6-tris (dimethylaminomethyl) phenol) Or basic active hydrogen compounds such as dicyandiamide or organic acid dihydrazide such as adipic acid dihydrazide. Or imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole.

In addition, aliphatic acid anhydrides such as polyadipic acid anhydride, poly (ethyl octadecandioic acid) anhydride, and poly sebacic anhydride as acid anhydride-based curing agents, Alicyclic acid anhydrides such as methyl tetrahydro phthalic anhydride, hexahydro phthalic anhydride, methyl cyclohexene dicarboxylic acid anhydride, and phthalic anhydride ), Aromatic acid anhydrides such as trimellitic anhydride, pyromellitic anhydride, glycerol tris trimellitate, hept anhydride, tetrabromophthalic anhydride halogen-based acid anhydrides such as anhydride).

In the present invention, an amine curing agent can be used as a curing agent having a relatively low temperature and having a good storage stability. Among these, a basic active hydrogen compound can be preferably used. More preferably, 3,3'-diaminodiphenylsulfone (3,3'-DDS) may be used as a curing agent suitable for the prepreg of the present invention.

A curing accelerator may be further included to promote the curing reaction of the composition together with the curing agent, and the curing accelerator may be dicyandiamide and 3,3 '-(4-methyl-1,3-phenylene) bis. (1,1-dimethylurea) (3,3 '-(4-metyl-1,3-phenylene) bis (1,1-dimethylurea)) may be used, but is not limited thereto.

When using dicyandiamide as a hardening accelerator, it is preferable to use 4 weight part-8 weight part with respect to the total weight of an epoxy resin composition, and it is most preferable to use 6 weight part-7 weight part. In addition, the amount of 3,3 '-(4-methyl-1,3-phenylene) bis (1,1-dimethylurea) is 0.5 to 10 parts by weight, 2 parts by weight based on the total weight of the epoxy resin composition It is preferably from 5 parts by weight, most preferably from 3 parts by weight to 5 parts by weight.

Although curing can be performed using only a curing agent, the curing time can be greatly shortened by a small amount of catalyst, that is, a curing accelerator. It is necessary to understand that the terms 'catalyst' and 'curing accelerator' refer to chemicals that shorten the curing time achievable with the curing agent alone.

In the third step, the epoxy resin composition is prepared, and then, a predetermined amount of the epoxy resin composition is coated on a release paper made of paper to prepare a resin paper, and preferably, the amount of the epoxy resin on the release paper is 50 g / m ² to coat the epoxy resin composition to be 55g / m ² per unit area to prepare a resin paper.

The fourth step (S400) is a step of preparing a prepreg by coating the resin paper prepared in the third step on both sides of the reinforcing fibers, the method of impregnating the resin paper in the reinforcing fibers in the present invention, but not wet Method and hot melt method can be used, and preferably the hot melt method is used in the present invention.

Specifically, in the wet method, first, the reinforcing fibers are immersed in a solution of the epoxy resin composition produced by dissolving the epoxy resin composition in a solvent such as methyl ethyl ketone or methanol, and then, the solvent is removed by evaporation by an oven or the like. It is a method of impregnating a reinforcing fiber with an epoxy resin composition. The hotmelt method also impregnates the reinforcing fibers directly with the epoxy resin composition in fluid by preheating, or first coats the release paper piece or pieces with the epoxy resin composition for use as a resin film, and then configures the film into a flat shape. It can be carried out by placing on one or both sides of the reinforcing fibers, and then impregnating the reinforcing fibers with the resin by applying heat and pressure.

The reinforcing fibers are not particularly limited or restricted in the type of fibers, and for example, fibers having various forms including long fibers, tows, fabrics, mats, knits, braids, and short fibers drawn in one direction may be used. Can be used. Here, long fibers means a single fiber or a bundle of fibers drawn to at least 10 mm or more. On the other hand, short fibers are fiber bundles chopped to a length of less than 10 mm. Fiber configurations in which the reinforcing fiber bundles are aligned in the same direction may be suitable for applications where high specific strength and inelasticity are required.

And a variety of fibers, including glass fibers, carbon fibers, graphite fibers, aramid fibers, boron fibers, alumina fibers and silicon carbide fibers can be used as the type of reinforcing fibers. In the present invention, in particular, the carbon fiber is preferably a carbon fiber having a tensile modulus of 230 to 800 GPa in consideration of the balance of the stiffness, strength and impact resistance of the prepreg.

On the other hand, the reinforcing fiber cross-sectional density of the prepreg may be 50 to 200 g / ㎡. If the cross-sectional density is at least 50 g / m 2, it may be necessary to laminate a small number of prepregs to fix a predetermined thickness in forming the composite material using the prepreg, which may simplify the lamination operation. . And if the cross-sectional density is 200 g / m <2> or less, the drape property of a prepreg may be excellent.

The reinforcing fiber mass fraction may also be 60 to 90 mass% in some embodiments, 65 to 85 mass% in some embodiments or even 70 to 80 mass% in another embodiment. If the reinforcing fiber mass fraction is at least 60 mass%, there is sufficient fiber content, which not only provides advantages in terms of excellent specific strength and inelasticity, but also prevents excessive heat generation during the curing time of the composite material. have. If the reinforcing fiber mass fraction is 90 mass% or less, the resin impregnation may be satisfactory and reduces the risk of forming many voids.

The prepregs prepared by the manufacturing method of the present invention are laminated and molded into a composite material. The laminating and forming methods of the prepregs are press molding method, autoclave molding method, bagging molding method, lapping tape method, internal pressure. Molding methods and the like can be used as appropriate.

For example, an autoclave molding method is a method in which prepregs are laminated on a tool plate of a predetermined shape, then covered with a bagging film, and then curing is performed by applying heat and pressure while removing air from the laminate. Not only can this allow for precise control of the fiber orientation, but it also provides a high quality molding material with good mechanical properties because of its minimum pore content. The pressure applied during the molding process can be 0.3 to 1.0 MPa, while the molding temperature can range from 90 to 200 ° C.

The lapping tape method is a method of wrapping tubular FRP material by wrapping prepreg around a rod from which a mandrel or some other shim has been removed. This method can be used to make golf shafts, fishing rods and other rod-shaped products. More specifically, this method involves wrapping the mandrel around with a prepreg, wrapping with a wrapping tape made of thermoplastic film over the prepreg under tension for the purpose of securing the prepreg, and applying pressure thereto. After curing the resin by heating inside the oven, the rod with the shim removed is removed to obtain a tubular body. The tension used to wrap with the lapping tape may be 20 to 78 N. Molding temperatures may range from 80 to 200 ° C.

The internal pressure molding method places a preform obtained by wrapping a thermoplastic tube or any other internal pressure presser around with a prepreg inside a metal mold, and then applying a pressure by introducing a high pressure gas into the internal pressure pressurizer, thereby accompanying By simultaneously heating the metal mold to mold the prepreg, the pressure applied during the molding process may be 0.1 to 2.0 MPa. Molding temperatures may range from room temperature to 200 ° C or from 80 to 180 ° C.

The prepreg manufacturing method according to the present invention has the effect of showing excellent high toughness, high strength and excellent heat resistance through controlling the viscosity.

Figure 1 shows a flow chart of the prepreg manufacturing method of the present invention.

Hereinafter, the present invention will be described in detail with reference to Examples, Comparative Examples, and Experimental Examples, which are embodied in various different forms by one of ordinary skill in the art to which the present invention pertains as an example. As such, it is not limited to what is described herein.

<Example 1>

A mixed epoxy resin was prepared by mixing diglycidyl ether (DGEBF) of liquid bisphenol F and triglycidyl p-aminophenol (TGAP), a trifunctional epoxy resin, at a room temperature of about 25 ° C. with a bifunctional epoxy resin. Then, the mixed epoxy resin was heated up to 120 ° C. at a temperature increase rate of 2 ° C./min, and then polyvinyl sulfone (PES) manufactured by solvay was added as a toughening agent, and maintained at 120 ° C. for 2 hours. The first mixture is prepared by mixing until the polyethersulfone (PES) is completely dissolved. In this case, the polyether sulfone (PES) used was a mixture of particles having an average size of 63 μm and polyether sulfone having an average size of 20 μm of particles ground through a ball mill.

The first mixture thus prepared was measured for viscosity according to KS M ISO 3219 standard using a concentric cylinder measuring system with a viscometer, and as a result, the first mixture had a viscosity of 5,000 to 10,000 poise at 25 ° C., At 180 ° C., it had a viscosity of 140 to 1,000 poise, and the gradient of viscosity change measured at 180 ° C. was 0.2 poise / min or less.

Subsequently, a high melting point thermoplastic particle was added to the product name Orgasol ^® 1002 D NAT 1, which is a polyamide 6 powder from ARKEMA, and then stirred for 1 hour or less until uniformly dispersed, thereby preparing a second mixture. After cooling the second mixture to a temperature set at a temperature reduction rate of 2 ° C./min, 3,3′-diaminodiphenylsulphone (3,3′-DDS) was added to the second mixture with a curing agent for 10 minutes. After stirring evenly within, the resin paper was produced so that the amount of epoxy resin might be 53 g / m <^2> per unit area on a release paper. The prepared resin paper was coated on both sides of the product name H3055S, a carbon fiber of Hyosung Co., Ltd. with unidirectional carbon reinforced fiber, to prepare a unidirectional prepreg so that the amount of carbon fiber per unit area was 192 g / m ² .

<Example 2>

Example 2, except that the heat treatment time in the step of preparing the first mixture in Example 1 is 3 hours, and the gradient of the viscosity change measured at 180 ℃ of the prepared first mixture is 0.5 poise / min Prepreg was prepared in the same manner as.

Comparative Example 1

Comparative Example 1, except that the heat treatment temperature and time in the step of preparing the first mixture in Example 1 is 130 ℃, 2 hours, and the gradient of the viscosity change measured at 180 ℃ of the prepared first mixture is 1.5 poise / min And prepreg was prepared in the same manner as in Example 1.

Comparative Example 2

Comparative Example 2 except that the heat treatment temperature and time in the step of preparing the first mixture in Example 1 is 140 ℃, 2 hours, and the gradient of the viscosity change measured at 180 ℃ of the prepared first mixture is 2.0 poise / min And prepreg was prepared in the same manner as in Example 1.

The prepreg of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 prepared as described above using the evaluation specimens as described below by using the test specimen as follows the interlaminar fracture toughness value (G _IIC ) Compression after impact (CAI) strength was evaluated.

Specifically, 20 prepregs of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 were laminated in one direction to fabricate interlaminar fracture toughness (G _IIC ) specimens, respectively. The prepregs of Example 1, Example 2, Comparative Example 1 and Comparative Example 2 were laminated with 24 sheets of (+ 45/0 / -45 / 90) 3S, where +45 refers to the unidirectional fabric of the prepreg The direction of the fiber is inclined 45 ° to the right, 0 is the direction in which the fiber is not inclined, -45 is the direction in which the fiber is inclined 45 ° to the left, and 90 is the direction in which the fiber is bent at 90 °. , S means symmetrically stacked. The prepreg thus laminated was formed at a temperature of 180 ° C. for 2 hours and a pressure of 6 bar by molding using a conventional autoclave. Formed fracture toughness (G _IIC ) specimens were prepared by cutting 13 inches in the 0 degree direction and 0.5 inches in the 90 degree direction, and post-impact compression (CAI) specimens were cut by 4 inches in width and 6 inches in length. The specimen was prepared.

Experimental Example 1

End Notch Flex test was conducted according to the test procedure of BMS 8-276.

The interlaminar fracture toughness (G _IIC ) values were measured, and the results are shown in Table 2 below. At this time, the fracture toughness value is a value representing the magnitude of resistance to the expansion of cracks of the material. Generally, the fracture toughness is high when the material is high in ductility.

In order to measure the interlaminar fracture toughness (G _IIC ) value, five specimens were evaluated for each specimen, and then the average value was recorded in the Examples.

In the case of Specimen G _IIC , five specimens were evaluated and the average value was reported in the Examples.

Table 1 below shows the interlaminar fracture toughness values (G _IIC ) and the compression after impact (CAI) according to the composition and heat treatment conditions of the Examples 1, 2, Comparative Examples 1 and 2, the viscosity change slope. Strength is shown.

division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Gradient of viscosity change
(poise / min) 0.2 0.5 1.5 2.0 Heat treatment condition 120 ℃, 2 hours 120 ℃, 3 hours 130 ℃, 2 hours 140 ℃, 2 hours DGEBF (% by weight) 50 50 50 50 TGAP (% by weight) 50 50 50 50 PES (phr) 30 30 30 30 polyamide 6 30 30 30 30 Carbon fiber H3055S H3055S H3055S H3055S G _IIC (in-lbf / in ² ) 12.19 11.52 7.10 5.03 CAI (ksi) 48.97 46.69 43.81 42.99

Interlaminar fracture toughness values in Examples 1 and 2, where the gradient of viscosity change of the first mixture at 180 ° C. was controlled to be 0.2 poise / min and 0.5 poise / min, respectively, as shown in Table 1 above. (G _IIC ) and post-impact compression (CAI) strength can be seen to improve both when compared to Comparative Examples 1 to 2 the slope of the viscosity change of the first mixture at 180 ℃ more than 1 poise / min.

Therefore, the prepreg manufacturing method according to the present invention has the effect of producing a prepreg of excellent high toughness, high strength and high heat resistance by controlling the viscosity.

The above-described embodiment is just a preferred embodiment to enable those skilled in the art to which the present invention pertains (hereinafter referred to as the person skilled in the art) to easily carry out the present invention. The present invention is not limited thereto, and therefore, the scope of the present invention is not limited thereto. Therefore, it will be apparent to those skilled in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention, and it is obvious that parts easily changed by those skilled in the art are included in the scope of the present invention. .

Claims (10)

The thermoplastic toughening agent was added to a mixed epoxy resin mixed with a bifunctional epoxy resin and a polyfunctional epoxy resin having at least three functional groups, and the temperature was raised to a predetermined temperature, followed by stirring until the thermoplastic toughening agent was completely dissolved while maintaining the temperature at that temperature for the first time. A first step of preparing a mixture;
A second step of preparing a second mixture by putting high melting point thermoplastic particles in the first mixture and stirring until they are evenly dispersed;
A third step of preparing an epoxy resin composition by adding a curing agent to the second mixture and stirring the mixture evenly; And
And a fourth step of manufacturing the prepreg by coating the resin paper on both sides of the reinforcing fiber.
The first mixture prepared in the first step is a prepreg manufacturing method, characterized in that the viscosity is 5000 to 10,000 poise at a temperature of 20 to 30 ℃. The method of claim 1,
In the first step, the first mixture is prepreg manufacturing method, characterized in that the viscosity is measured at 180 ℃ according to DIN EN ISO 3219 140 to 1,000 poise. The method of claim 1,
The first mixture is prepreg manufacturing method characterized in that the gradient of the viscosity change measured at 180 ℃ according to DIN EN ISO 3219 is 0.1 to 1 poise / min or less. The method of claim 1,
In the first step, the prepreg manufacturing method, characterized in that the heat treatment temperature is more than 110 ℃ 130 ℃. The method of claim 1,
The bifunctional epoxy resin is a diglycidyl ether of bisphenol-F of bisphenol F, a diglycidyl ether of bisphenol-A of bisphenol A, and a diglycidyl bisphenol S. Di- ether (Di-glycidyl Ether of Bisphenol-S) and a phenol novolak-type epoxy resin, any one or more selected from the prepreg manufacturing method. The method of claim 1,
The polyfunctional epoxy resin is selected from triglycidyl p-aminophenol, triglycidyl m-aminophenol and tetraglycidyl-4,4'-diaminodiphenylmethane Prepreg manufacturing method characterized by any one or more. The method of claim 1,
The thermoplastic toughening agent is polysulfone, polyethersulfone, polyphenylsulfone, polyetherethersulfone, polyphenylene sulfide, polyamide, polyamide, polyamide A frep characterized by at least one selected from ether amide, aramid, polyketone, polyether ketone, polyetherether ketone, polyester and polyurethane. Leg manufacturing method. The method of claim 1,
The high melting point thermoplastic particles are polyamide 6, characterized in that the prepreg production method. The method of claim 1,
The curing agent is diaminodiphenylsulfone, dicyandiodiamide, 4,4'-methylenedianiline, diethylenetriamine, piperidine , Borontrifluoride monoethylamine (borontrifluoride monoethylamine) and metaphenylenediamine (metaphenylenediamine) any one or more selected from the method of producing a prepreg. A prepreg prepared according to the method of any one of claims 1 to 9.

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