KR960005469B1 - Conjugated for strand molding - Google Patents

Abstract

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Description

Molded Composite Fiber Yarn

1 and 2 are cross-sectional views illustrating an example of an unmixed island state in the present invention.

3 is a cross-sectional view illustrating an example of a mixed island state in the present invention.

* Explanation of symbols for main parts of the drawings

1: ultra-high strength polyethylene fiber 2: thermoplastic organic fiber

TECHNICAL FIELD The present invention relates to a composite fiber yarn and a fabric as a molding composite material having excellent strength, elastic modulus, and workability. More specifically, reinforcing material for molded articles such as automobile parts such as radial tires, various mechanical structural parts, pressure vessels, or pipes, etc. The present invention relates to a composite fiber yarn and a fabric for molding which can be used in a wide range of fields.

As a composite reinforcing material using a thermoplastic resin as a matrix and a reinforcing fiber as a dispersing material, for example, a method of opening a glass fiber strand using static electricity, attaching a thermoplastic resin powder, followed by heating and melting to form a tape-like strand (Japan 47-36467), or a method of coating a flexible thermoplastic resin on a strand of reinforcing fiber to which a powder of thermoplastic resin is applied to form a flexible strand, and thermoforming the strand with a fabric or the like (JP-60-36156). ).

In such a composite material, what reinforcing fiber is selected, and what means is used to impregnate the reinforcing fibers so that the melting point and thermoplastic resin (hereinafter referred to as a matrix) are uniform and have less voids, or by any method. The point is whether the matrix and the reinforcing fibers are melt-molded without deteriorating the properties such as strength and elastic modulus of the reinforcing fibers.

In order to obtain a molding composite material having good impregnation using the conventional technique as described above, it is necessary to use a micron powder as a matrix, and to open reinforcement fibers, adhere and melt the matrix, and in some cases, coatings, etc. In addition to the complicated process, the workability is not good, and depending on the type of reinforcing fibers, the properties of the reinforcing fibers may be deteriorated due to the heat effect during melt molding, thereby degrading the performance of the molding composite.

The present invention has been made in view of such a situation, and the impregnability of the matrix is very good, and the composite fiber yarn for molding, which is a fabric constituent material for producing the composite fiber fabric for molding, having excellent strength, elastic modulus and processability, is formed by the yarn. It is an object of the present invention to provide a thread that can use the fabric or itself as a reinforcing fiber of FRP.

That is, the present invention is made up of the yarns and the woven fabric formed by the yarns in which ultra-high strength polyethylene fibers having excellent strength and elastic modulus and thermoplastic fibers having a melting point lower than 10 ° C. and less than 50 ° C. are lower than the ultra high strength polyethylene fibers.

The present invention is to use an ultra-high strength polyethylene fiber (hereinafter referred to as reinforcing fiber) having a high strength, high elastic modulus, the strength, the initial elastic modulus is an automotive part manufactured using a fabric formed from the composite fiber for molding according to the present invention Alternatively, considering the strength and initial elastic modulus required for products such as mechanical structural parts, tensile strength 20 to 55 g / denier, preferably 30 to 50 g / denier, more preferably 45 to 55 g / denier, initial elastic modulus 800 to It is required to be 2600 g / denier, preferably 1000 to 2600 g / denier. High-strength polyethylene fibers with strengths exceeding 55g / denier or elastic modulus exceeding 2600g / denier have the problem that the filaments cause so-called fibrillation by simple pulling because the molecular chain is excessively oriented in the fiber axis direction. . Fibrillation is a phenomenon in which a plurality of fibrils are divided in one filament. When fibrillation occurs, a problem occurs in that the fibrill is wound around a roller or a guide when the thread is running, and the thread is broken. Even when the yarn is used as a reinforcing material as it is, the strength and initial elastic modulus promise excellent results.

Regarding the number of denier, when the fiber having a total denier of 100 to 1000 denier (the number of filaments 10 to 100) is used for both the reinforcing fibers and the matrix fibers, a good opening state is obtained by, for example, the electroforming method, and the matrix in the final composite molded article Although the mixed state with the reinforcing fiber becomes more uniform, an excellent composite effect is obtained, but it is not limited to this range.

Referring to one example in the manufacturing method of such a reinforced fiber as follows.

The reinforcing fibers are solution spun using ultra high molecular weight polyethylene (e.g., ultra high molecular weight polyethylene having a weight average molecular weight of 1 × 10 ⁵ or more, preferably 1 × 10 ⁶ or more), and the resulting gel fiber is drawn into a drawing zone (supplying an inlet temperature). Multistage stretching while passing the fiber at a melting point above and below its melting point, while the outlet temperature is above the melting point of the feed fiber and below the melting point of the fiber after stretching. A new high pear is obtained by the stretching method.

The reinforcing fibers and matrix fibers obtained in this way are combined to form a fabric, but the matrix fibers are required to have their melting points lower than 10 ° C. and lower than 50 ° C. above the reinforcing fibers. That is, in the case of melt molding the fabric, the fabric is processed at a temperature approaching the melting point of the reinforcing fiber, and when the melting point difference between the reinforcing fiber and the matrix fiber is less than 10 ° C, the temperature control in the melt molding process of the fabric is not easy, In addition, the reinforcing fiber is thermally affected and its physical properties change, which may deteriorate the performance of the final composite molded product. On the other hand, when the melting point difference between the reinforcing fibers and the matrix fibers is 50 ° C. or higher, the heat resistance of the product is lowered, and thus the product form is not maintained when it is generated by friction or the like during use.

If the melting point of the matrix fiber is less than 10 ° C. or less than 50 ° C. below the melting point of the reinforcing fiber, it is lower than the melting point of the reinforcing fiber as the temperature higher than the softening point of the matrix fiber (preferably above the temperature sufficient to melt the matrix fiber). It is relatively easy to melt molding in the temperature range. Therefore, the impregnation of the matrix with the reinforcing fibers is sufficiently performed so that the voids are uniform and the voids are reduced, and further, the final composite molded article can be obtained in which the physical properties of the reinforcing fibers are not affected by the melt molding temperature and do not cause deterioration in performance. .

The matrix fiber is not particularly limited as long as it is made of a fiber-forming thermoplastic polymer that satisfies the above temperature conditions. Polyethylene fiber, polybutene-1 fiber, and the like are exemplified. However, when using the reinforcing fiber produced by the above method, the melting point is 147. As the matrix fiber, polyethylene fiber (melting point 110 to 137 ° C) and polybutene-1 fiber (melting point 120 to 130 ° C) are particularly preferable as the matrix fiber.

Reinforcing fibers are a composite method of matrix fibers, either in a non-mixed island or in a mixed island. The non-mixed island state means that the reinforcing fibers 1 and the matrix fibers 2 are in a side-by-side shape as shown in FIG. 1 (cross section), or as shown in FIG. 2 (cross section). It is a case where it becomes a sheath-core shape. The former can be formed by doubling or coalescence, and the latter can be formed by the well-known coating method or its improvement method.

On the other hand, the mixed island refers to a state in which the reinforcing fibers 1 and the matrix fibers 2 are completely mixed with each other as in FIG. 3 (cross section). In the present invention, the composite may be mixed in any of mixed and unmixed islands. However, the composite is mixed in a mixed island state in order to uniformly disperse the matrix between the reinforcing fibers to reduce voids and improve the strength of the final composite molding.

)나 시트를 사용하는 것이 아니고 섬유를 사용하는 것이므로, 복합공정 및 용융성형공정중의 어느것에 있어서도 복잡한 조작이 필요하지 않고, 혼섬 또는 비혼섬중의 어느것을 채용하여도 제조공정의 작업성은 매우 훌륭한 것이 된다.The present invention is a powder (粉) in the form of a matrix as described above

Since it does not use a sheet or a sheet but uses a fiber, no complicated operation is required in any of the composite process and the melt molding process, and the workability of the manufacturing process is excellent even when employing either mixed or unmixed islands. It becomes.

In addition, the method of combining the matrix fiber and the reinforcing fiber in a mixed island state is not limited, but the Taslan method, the electro-opening method, and the interlace method are exemplified. These methods are described below.

(1) Taslan method

This method is a turbulent disturbance method in which a plurality of filaments are supplied to the fluid turbulent region by an air jet in a relaxed state to form a bulky yarn by forming loops or entanglements.

According to this method, the single-fiber filaments are separated from each other and disturbed in the turbulent region, and then pulled out from the turbulent disturbance region continuously so as not to be tensioned, thereby obtaining bulk yarns with irregularly mixed loops or entanglements. have.

By applying this technique to the composite fiber and matrix fiber composite of the present invention, both fibers can be combined with very high production efficiency. The characteristic of the composite yarn produced by the turbulence disturbance method is that a number of loops or entanglements are formed as described above. When this method is applied to the present invention, the composite yarn can be produced by utilizing the properties of the reinforcing fibers and the matrix fibers. It is also very easy to melt-form the fabric using the composite yarn. In this method, compared with matrix fibers such as polyethylene and polybutene-1, by reducing the feeding speed of the reinforcing fibers and increasing the tension, loops and entanglements of the matrix fibers are formed with respect to the reinforcing fibers in the turbulent disturbance zone. In particular, the reinforcing fiber has a high modulus, and it is possible to reduce the turning in the turbulent disturbance zone by merely increasing the tension.

An important point in this method is the feed rate ratio, which is determined by the mixing ratio of both fibers, and the reinforcing fibers are preferably 0.05 to 0.5 times, preferably 0.1 to 0.3 times, relative to the matrix fibers. If it is less than 0.05 times, the reinforcing efficiency is poor in the final composite molding. On the other hand, if it is more than 0.5, the void ratio of the final composite molded article is increased, and loops or entanglement of reinforcing fibers in turbulent disturbance zones are undesirable. Can not do it.

According to the turbulence disturbance method, the total denier and number of filaments of the two fibers are determined by the mechanical conditions such as the feed rate ratio, the nozzle shape, and the fluid pressure, but it is preferable to use 100 to 1000 denier and 10 to 100 filament fibers. Do.

(2) electric opening method

A method of manufacturing a composite yarn by mixing filaments and staples, in which a filament is opened using an electric carding device, and the staples are rolled up and rolled up in front of the front rollers so that both fibers are not biased to one side. According to this method, a yarn obtained by continuously and uniformly mixing filaments and staples of different fibers can be obtained.

By applying this method to the present invention, a very uniform composite yarn can be produced. When this method is used, the reinforcing fiber is very suitable because it is obtained in a good opening state by voltage application.

Denier and filament numbers in the case of using this method are also suitable for 100 to 1000 denier and 10 to 100, respectively, and can be improved in operability in the fabric manufacturing process by adding and combusting after opening and mixing. It can be denser and contribute to reduced supply in melt molding.

(3) interlacing method

The interlacing method is a technique for producing two or more vortex turbulent bands almost parallel to the bent axis, drawing a filament in the band and tensioning them so that no loops or crimps are formed, thereby producing an inexhaustible close transformer.

The principles of the present invention allow the fluid to impinge on the filament such that the fluid is perpendicular to the filament axis, and at the same time create a parallel turbulence with respect to the filament, such that the turbulent filament is responsive to the tension of the seal and the speed or pressure of the fluid At the same time, it splits the inside and randomly folds each individual filament into interlacing.

The degree of interlace obtained is influenced by tension, fluid pressure, overfeed rate, filament denier, number of filaments, thread modulus and the like. The effect of using the interlacing method is that the productivity is high, the mixing between the fibers is uniform, the fabric of the composite yarn can be easily produced, and the void during melt molding can be very small.

Of particular importance in this method are overfeed rate, tension, fluid pressure and denier, and number of filaments. The reinforcing fibers generally have a higher modulus than the matrix fibers, so it is necessary to slightly increase the overfeed rate, and it is important to set it to 105 to 110% by weight. The matrix fiber may be set based on the overfeed rate of the reinforcing fiber in response to the content rate. Similarly, in terms of tension and fluid pressure, it is important to process a condition that is slightly higher than that of a conventional medical company based on reinforcing fibers. In particular, in order to perform uniform mixing, the fluid pressure is suitably 10 to 50 psig, preferably 30 to 50 psig. In addition, in the uniform division mixing, the number of deniers and filaments of both fibers to be combined is important, in addition to the above conditions. Since the linear density is closely related to mixing in the turbulent flow region, the linear density is preferably equal for uniform mixing.

In the present invention, it is preferable that the fibers having 100 to 1000 denier and the number of filaments 10 to 100 are interlaced yarns, and as the denier of the short fibers, 1 to 10 denier, preferably 1 to 3 denier, shows good workability and productivity, and a straight knitting process And also in a melt molding process, sufficient workability is acquired and it becomes an excellent composite molded object.

The composite fiber yarn for molding (hereinafter referred to as yarn) obtained by the above method may be used for melt molding by forming a fabric alone, or by forming a fabric by using some yarn and using matrix fibers in the remainder. It may also be molded.

In any of the methods described above, when the mixing ratio of the reinforcing fibers and the matrix fibers in the obtained fabric is less than 5% (meaning the weight%, hereinafter the same), the reinforcing efficiency is not good in the final composite molding, and 80 When the percentage is exceeded, it is not preferable because the content of the matrix is reduced, so that the impregnation is poor and the porosity of the final composite molding is large. Therefore, the content of reinforcing fibers (ultra high strength polyethylene fibers) in the yarn made of yarn is 5 to 80%, preferably 10 to 70%, more preferably 20 to 60%.

In the case of forming a fabric from yarns, comparing the method of using the yarns alone and the method of mixing yarns and matrix fibers, the uniformity of mixing of the reinforcing fibers and the matrix fibers is obtained by the former method. Since it is excellent, it is more preferable. That is, in the case of the former, uniformity can be obtained as the level of the short fibers constituting the yarn, whereas in the latter case, only the uniformity between the yarn and the matrix fibers composited therewith is obtained. Therefore, the impregnability of the matrix fiber to the reinforcing fibers and the strength characteristics of the final composite molded article are also excellent in the former case.

Meanwhile, the cloth of the present invention includes a woven fabric, a knitted fabric or a nonwoven fabric. Examples of the direct organization include plain weave, twill, and runners, as well as their derived organizations, lions, graves, blue tombs, and samreung. In addition, various fabrics may be exemplified depending on the purpose such as wood board flat weave, anti-laid fabric, woolen weave, etc., which are usually used as the weave structure of reinforcement cloths such as glass crosses. When the molten molded article is used as a unidirectional reinforcing agent or a cross laminated plate, a thread is used for either one of the warp yarns or the weft yarn (preferably on the warp side), and the other of the same type of the yarn The matrix fibers may be woven and laminated at a desired number and desired angle, followed by melt molding. In addition, when a letter is formed using a thread, any type of warp knitting, circular knitting, and flat knitting may be used, and any knitting structure may be adopted. In particular, in order to increase the utilization rate of the molded sheet melt-molded after knitting, the yarns are preferably incorporated in a lay in or tack in shape without forming knitting, and more preferably, a lay in to be. In the knitting system to give the lay in the warp knitting method, the inclined yarn of the composite yarn can be inserted and knitted by the body movement of 0-0 / 1-1, etc., and this letter is highly retracted in the radial direction. . In addition, in order to highly strengthen both the radial direction and the upper direction, a weft insertion piece may be added in addition to the inclined insertion piece. These letters can be easily cut with a warp knitting machine. Since the reinforcing piece and the flat piece are excellent in reinforcing only in one direction, it can be used as a reinforcing material or a laminated board in one direction by laminating letters in a desired direction.

Sheets for composite moldings produced by knitting, etc., from yarns of the present invention are cut into a predetermined size for use in secondary processing steps, and the number of sheets equivalent to the weight of the composite molding is piled up as samples. The sample preheated to a temperature above the softening point of the matrix fibers (preferably sufficient to melt the matrix fibers) is placed in the mold. Thus, the mold is finally pressed into a desired shape. The press pressure generally requires 50 to 150 kg / mm 2 with respect to the projected area, and the faster the pressing speed, the better and 1 to 2 seconds are suitable. The temperature of the mold is suitably below the melting point of the matrix fiber, and the cooling time is determined by the thickness of the thickest part of the molded article. In addition, the sheet for a composite molded article can be used for solid-phase stamping by plastic deformation by first using a blank obtained by melt-impregnating the matrix fibers with a hot press roller or the like and using a preheating temperature below the melting point of the matrix fibers.

Hereinafter, although an Example is described, this invention is not limited to a following example, The design change suitably according to the said meaning is contained in the technical scope of this invention.

EXAMPLE

The elongation (tensile strength and initial modulus) of the ultra-high strength polyethylene fibers used as reinforcing fibers in the following examples and comparative examples and the pore content evaluation method of the obtained laminate were as follows.

[Measurement of Elongation of Ultra High Strength Polyethylene Fiber]

According to JIS-L-1013 (1981), Tensilon UTM-1T, 500,250 made by TOYO BALDWIN, was used, and the sample length (gauge length) was 30 mm and the elongation rate was 100% / min. The SS curve of the short fibers was measured to calculate tensile strength (g / denier) and initial elastic modulus (g / denier). The initial modulus was calculated from the maximum gradient near the origin of the S-S curve. Each characteristic value was made into the average value measured about 20 single fibers.

[Evaluation Method of Pore Content of Laminated Plate]

The reinforcing laminate was cut into a short book of 2.5 cm in width and 15 cm in length as a test piece. The test piece was perpendicular to the ink solution liquid level, and the lower end of the test piece was immersed and fixed in an ink solution having a depth of 1 cm and left for 10 minutes. The height of the sucked ink liquid after standing for 10 minutes was measured, and this length was taken as a representative standard of the void content of a laminated board.

Example 1

Ultra high strength polyethylene fiber (molecular weight: 2 million, melting point: 147 ℃) with tensile strength of 32g / denier, initial elastic modulus of 1200g / denier (molecular weight: 2 million, melting point: 147 ℃) and polyethylene fiber with 400 denier, 150 filaments (melting point) : 120 ° C.), a composite yarn was produced using an interlace machine in which two pairs of butt-laid fluid conduits were opened.

Fluid pressure 50 psig. 850 denier composite yarns in which both fibers were uniformly mixed with each other were obtained by compounding in the vortex region at a rate of about 500 m / min. Next, the composite yarn was inclined, and the same polyethylene fiber used in the composite yarn was used as the weft yarn, and a plain weave fabric having a warp density of 50 yarns / inch and a weft density of 50 yarns / inch was woven. Using the sheet cut out to the size of 20 cm x 20 cm from this plain fabric as a sample, it vacuum-dried on the conditions of 80 mm and 16 hours, 0.1 mmHg or less, and three sheets were made so that the composite yarn of each layer might become the same direction. The laminated sheet was filled into a mold previously heated to 120 ° C., preheated and melted for 3 to 5 minutes under light load, and then subjected to heat compression molding at a pressure of 50 to 70 kgf / cm 2. Before taking out from the metal mold | die, it rapidly raised to 60 degreeC under pressure.

By melt-molding in the above-described order, the polyethylene fibers used in the composite yarn and the weft yarn are melt-impregnated at the edges of the ultra high strength polyethylene fibers remaining as the reinforcing material, thereby obtaining a one-way reinforcement laminated board using the super strong polyethylene fibers as the reinforcing agent.

The laminate was subjected to a tensile test in accordance with JIS K7054, with the axial direction of the ultra high strength polyethylene fiber as the longitudinal direction of the test piece. As a result, the volume content of the ultra high strength polyethylene fiber was about 35% of the test piece, 1220 to 320 Mpa (124.4 to 124.4). 134.6 kg / mm 2) of tensile strength. As a result of evaluating the pore content of the laminated plate by the ink-hop method, it was evaluated that the polyethylene matrix was melted in a state almost near perfect, and had a very good appearance.

Example 2

A composite yarn doubling the same material as in Example 1 was prepared. The denier of the composite yarn was 800 denier. Subsequently, the composite yarn was used as warp and weft yarn, and the plain fabric was woven at a warp density of 50 bones / inch and a weft density of 50 bones / inch. In the same manner as in Example 1, three sheets of the fabric cut out to 20 cm x 20 cm were laminated to form a sample.

The sample was vacuum dried, pre-melt and compression molded under the same conditions as in Example 1 to obtain a reinforced laminate having a thickness of 1.5 mm.

The volume content of the ultra-high strength polyethylene fiber of this reinforced laminated board was about 50%, and the void content evaluation was performed by the ink-hop method, and it was 1 cm, and it was favorable with few voids. When the laminate was subjected to a tensile test according to JIS K7054, a tensile strength of 1700 to 1850 MPa (173.4 to 188.7 kg / mm 2) was obtained and is isotropic.

Comparative Example 1

A 400 denier ultra high strength polyethylene fiber used in Example 1 was used as the warp and weft yarn to weave a plain fabric having a warp and weft density of 40 bones / inch. The unit weight of the obtained fabric was 145 g / m 2. Four pieces of 0 cm x 20 cm fabric pieces were cut out from this plain fabric.

On the other hand, four sheets of 20 cm x 20 cm dimension were cut out by the commercially available low density polyethylene film (melting point 120 degreeC) of thickness 150 microns.

Four fabric pieces and four film sheets were laminated alternately to form a sample for molding.

Samples obtained by alternately laminating the four sheets were subjected to vacuum drying, preheating, and compression molding under the same conditions as in the molding conditions of Example 1 to obtain a laminate having a thickness of about 1.4 mm.

The ultrahigh strength polyethylene fiber contained in this laminated sheet had a volume content of about 50% and a tensile strength of 1500 to 650 MPa (153 to 168.3 kg / mm 2). In addition, as a result of the evaluation of the supply content by the ink-hop phase method, it showed a very large value with respect to the value of the said Example as 8 cm, and it turns out that the gap between fibers exists considerably.

Comparative Example 2

Ultra high strength polyethylene fiber (molecular weight: 2 million, melting point 147 ℃) of 30g / denier, filament number 800 with 110g / denier initial modulus, total denier 1600 denier, was opened by static electricity, A particle diameter of 120 microns and a melting point of 120 ° C.) were electrostatically attached, and subsequently passed through a melt extruder having a die temperature of 230 ° C. to coat a low density polyethylene having a thickness of 0.15 mm by a tubular method to obtain a strand having a diameter of 1 mm. The volume content of the ultra high strength polyethylene fiber contained in the obtained strand was about 30%.

The tensile strength of this strand was 29 kg, which was very low, and the strength retention was about 60% with respect to the yarn strength of the starting material. It is presumed that the decrease in the strong retention rate is caused by thermal degradation in the coating process.

The strands were aligned and wound on a steel sheet in a sheet form and hot pressed at 120 ° C to fuse the strands together to obtain a unidirectional sheet in which ultra-high strength polyethylene fibers were integrated into low-density polyethylene.

The unit weight of this sheet was 600 g / m <2>. The sheet was cut out to a size of 20 cm x 20 cm, laminated in two sheets with the same fiber axis direction, and vacuum dried, preheated melted, and compression molded as in the molding conditions of Example 1 to obtain a unidirectional reinforced laminate.

The laminate was subjected to a tensile test with the axial direction of the ultra high strength polyethylene fiber as the tensile direction of the test piece, and showed a tensile strength of 600 to 650 MPa (61.2 to 66.3 kg / mm 2). This was very inferior to that obtained in Example 1 above.

Moreover, as a result of evaluating the supply content of the obtained laminated sheet, it is estimated that the value is 4 cm and there exist many gaps.

According to the present invention, by using a yarn composed of a combination of ultra high strength polyethylene fiber having excellent strength and elasticity as described above and a thermoplastic fiber having a melting point of 10 ° C. or higher and less than 50 ° C. lower than the ultra high strength polyethylene fiber, the impregnation property is very good and voids are caused. It is possible to provide a composite molding fabric having no strength, elasticity and processability with good workability. The yarn of the present invention can be used as a composite reinforcement as it is.

Claims (5)

An ultra-high strength polyethylene fiber having excellent strength and elastic modulus and a thermoplastic fiber having a melting point of 10 ° C. or higher and less than 50 ° C. lower than the ultra high strength polyethylene fiber, which are formed in a mixed or unmixed state. 2. The molding composite fiber yarn of claim 1, wherein the ultra-high strength polyethylene fiber and the thermoplastic fiber are mixed in a mixed island state. The molding composite fiber yarn according to claim 1 or 2, wherein the ultra high strength polyethylene fiber has a strength of 20 to 50 g / denier and an elastic modulus of 800 to 2600 g / denier. The composite fiber yarn according to claim 1 or 2, wherein the ultra high strength polyethylene fiber and the thermoplastic fiber have a total denier of 100 to 1000 denier and a number of filaments of 10 to 100. The composite fiber yarn for molding according to claim 1 or 2, wherein the ultra-high strength polyethylene fibers and thermoplastic fibers have deniers of 1 to 10 deniers.

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