KR20160083549A - Method Of Manufacturing Composites By Pultrusion Process - Google Patents

Abstract

The present invention relates to a method for producing a composite material by a pultrusion process, which includes: (S1) a fiber supplying step for supplying fiber thread in a bundle form; (S2) a fiber opening step for opening the supplied bundled fiber into a fiber with the width 5-20 times bigger than the supplied one; (S3) a resin impregnation step for impregnating the opened fiber thread into a resin; and (S4) a cooling step for cooling the resin-impregnated fiber thread.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a composite material by a draw-

The present invention relates to a composite material manufacturing method, and more particularly, to a method of manufacturing a thermoplastic composite material by using a drawing and forming process.

Compostie is a material that artificially blends or combines materials with different ingredients and properties to maximize the properties of each material or to have new properties that are not expressed in a single material. Composite materials are basically excellent in properties such as strength, corrosion resistance, fatigue life, abrasion resistance, impact resistance, and light weight compared to conventional materials. Therefore, they are widely used in aerospace, sports goods, shipbuilding, It is a representative 21st century industrial material that is attracting attention in the field.

The composite material is generally made of a reinforced material that is responsible for the load applied to the material, and a matrix that transmits the load to the reinforcement in combination with the reinforcement. The reinforcing material is usually glass fiber, carbon fiber, aramid Fiber reinforced materials such as polyolefins, polyolefins, polyolefins, polyolefins, polyolefins, polyolefins, polyolefins, polyolefins, polyolefins, polyolefins, Resin type base materials such as thermoplastic resins including phenylene sulfide resins and the like are widely used.

Such a composite material is classified into various types depending on which materials are combined with each other. Among them, Pultrusion refers to a process in which a supplied fiber yarn is continuously impregnated with a resin by impregnating a die to form a product having a certain shape. The production of a product having a high productivity and a high fiber volume content And it is possible to produce products with unlimited length of products. Through the drawing and forming process, when a fiber bundle is supplied in the form of a bundle and formed into a pellet, a long fiber reinforced thermoplastics (LFT) can be manufactured, and a fiber yarn can be made by spreading When supplied, a unidirectional tape (UD Tape) can be manufactured.

Generally, the impregnation property and the impregnation content of the resin on the fiber greatly affect the physical properties of the final product when the molded product of the fiber reinforced composite material is produced by the draw-forming. In particular, the lack of uniformity of the impregnation of the resin and the generation of voids as such may cause defects in mechanical properties in the final product, and this phenomenon is more prominent as the number of fibers supplied and the amount of impregnated fibers are increased, It becomes. It is therefore important that the fibers supplied from the krill be controlled so that when the resin is impregnated in the impregnation tank, the resin is well dispersed so that it penetrates into all portions of the fiber and uniform impregnation to the inside of the fiber occurs.

Regarding the manufacture of composite materials, Korean Patent Registration No. 10-0880805 discloses a method in which a fiber yarn laminated through a fabric arranger is supplied and a resin is sprayed on a fiber yarn to always apply a predetermined amount of resin, Korean Patent Registration No. 10-0574608 discloses a draw-forming method comprising a step of vertically stacking a fiber bundle so that a bundle of fibers is naturally released without moving and then impregnating the resin.

However, in the field of producing composite materials by still drawing, the most problem is to improve the uniformity of resin impregnation. In the case of using the curing resin in the drawing process, a curing process is additionally required, And so on. In addition, despite the fact that the resin impregnation property and the uniformity may depend on the degree of opening of the fibers in the UD tape manufacturing field, there is a limit to improve the physical properties of the final product due to the lack of the technology for arranging the fibers.

Accordingly, in order to improve the degree of arrangement and uniformity of fiber density per unit area of the reinforcing fiber yarn impregnated with the resin in the drawing-forming process, the fiber yarn before spreading into the impregnating die is spread, The present invention provides a method for manufacturing a fiber-reinforced composite material which can increase the resin impregnation rate and the amount of fiber input, as well as the physical properties of the final product, by spreading the fiber yarn in a bundled state uniformly over a wide area and then impregnating the resin.

A preferred embodiment of the present invention capable of solving the above problem is a composite material manufacturing method by a draw-forming process including the following steps.

(S1) a fiber supplying step of supplying a bundle of fiber yarns;

(S2); a fiber opening step of opening the bundle-type fiber yarn supplied in a width direction of 5 to 20 times the supplied width;

(S3) a resin impregnating step of impregnating the resin into the resin; And

(S4) A cooling step for cooling the resin-impregnated fiber yarn.

In the embodiment, the fiber opening step may include a first opening step for preheating the supplied fiber bundle in the form of bundle; A second opening step of applying vibration to the first opened fiber yarn; And a third opening step of applying a further vibration to the second opened fiber yarn.

More specifically, in the embodiment, the fiber opening step may include a first opening step of preheating the supplied fiber bundle in a bundle form at a temperature of 150 to 200 DEG C and an air pressure of 0.3 to 0.7 MPa; A second opening step of applying vibration to the first opened fiber yarn at a vertical amplitude of 5 to 15 mm per second at a temperature of 150 to 200 DEG C and an air pressure of 0.5 to 1 MPa; And a tertiary carding step in which the secondary carded fiber yarn is further subjected to vibration at a vertical amplitude of 5 to 15 mm per second at a temperature of 160 to 220 DEG C and an air pressure of 0.8 to 1.5 MPa.

In the meantime, it is preferable that the fiber yarn supplied in the step (S1) of the embodiment is at least one selected from among carbon fiber, glass fiber and aramid fiber, and the drawing forming process including the steps (S1) to (S4) The process speed may be between 2 and 20 m / min.

In this embodiment, the resin in step (S3) may be at least one thermoplastic resin selected from polyolefins, polyamides, polyesters, polysulfones and polyacetals, and cooling in step (S4) .

Further, it is preferable that the composite material has a fiber specific gravity deviation of less than 0.05 measured in two arbitrary sections based on the cross-section of the composite material in the width direction.

It is possible to maximize the impregnation property and uniformity of the resin in the draw-forming process by improving the degree of arrangement of the fibers to be supplied, and thereby to improve the physical properties of the fiber-reinforced composite material final product to manufacture a product requiring high strength and high precision As shown in Fig. In addition, it is possible to produce a thin-walled product, which can be expected to be further reduced in weight.

Fig. 1 is a photograph of the surface of UD tape (left) manufactured by using 2400TEK glass fiber as a reinforcing fiber and UD tape (right) manufactured by carding.
Fig. 2 is a photograph of the surface of a UD tape (left) manufactured by using 12K carbon fiber as a reinforcing fiber and a UD tape (right) manufactured by carding. Fig.

According to an aspect of the present invention, there is provided a method of producing a fiber bundle, comprising: (S1) (S2); a fiber opening step of opening the bundle-type fiber yarn supplied in a width direction of 5 to 20 times the supplied width; (S3) a resin impregnating step of impregnating the resin into the resin; And (S4) a cooling step of cooling the resin-impregnated fiber yarn.

The term " spreading "in the present specification means that a plurality of filaments are bundled in the form of bundles in the present invention in the sense that the bundles are unfolded, . ≪ / RTI > Also, the opening step may be described as a spreading step, and the carding device may be described as a spreader.

In general, in the drawing-forming, the fibers are put into the impregnation tank, and the fibers injected into the impregnation tank meet with the resin supplied from the extruder to the impregnation tank to impregnate the resin. In this case, The impregnation dispersibility and the efficiency which are uniformly impregnated become poor, resulting in an excessive content or impregnation nonuniformity. However, in the case of fiber impregnation by carding the fiber, since the resin can easily contact between the fibers, impregnation efficiency is improved. As a result, not only the physical properties of the final composite material can be maximized, but also the thickness decreases as the width of the fiber is increased as the width of the fiber is increased, so that a composite material having a thin thickness and excellent physical properties can be manufactured.

Conventionally, however, it has been limited to uniformly and evenly spreading the fibers in the width direction in the continuous drawing forming process, thereby failing to maximize the impregnation dispersibility and efficiency of the resin. On the other hand, according to the present invention, fiber yarn supplied in the form of a bundle is opened at a width of 5 to 20 times the supplied width on the basis of the width direction, so that it can be controlled to have a good fiber arrangement degree. Accordingly, the impregnation property of the resin can be improved, the physical properties of the final product can be improved, and a thin product can be produced, thereby further reducing the weight of the product. At this time, when the width is less than 20 times, excellent resin impregnation effect by carding can be sufficiently obtained. However, if it is less than 5 times, carding is insufficient and fibers can be impregnated with each other.

In the present invention, in order to allow fiber sorting at the above level, that is, 5 to 20 folds in the width direction, the fiber opening step (S2) is a first opening step for preheating the supplied bundle- ; A second opening step of applying vibration to the first opened fiber yarn; And a third opening step of applying a further vibration to the second opened fiber yarn.

More specifically, in the present invention, the fiber opening step (S2) includes a first opening step of preheating the supplied bundled fiber yarn at a temperature of 150 to 200 DEG C and an air pressure of 0.3 to 0.7 MPa; A second opening step of applying vibration to the first opened fiber yarn at a vertical amplitude of 5 to 15 mm per second at a temperature of 150 to 200 DEG C and an air pressure of 0.5 to 1 MPa; And a tertiary carding step in which the secondary carded fiber yarn is further subjected to vibration at a vertical amplitude of 5 to 15 mm per second at a temperature of 160 to 220 DEG C and an air pressure of 0.8 to 1.5 MPa.

In the first opening step, the fiber yarn is preliminarily preheated so that the fiber can be adapted to various external conditions applied to the fiber during the entire spreading process. After the preliminary heating of the fiber yarn in the impregnation tank, This is a step for raising the temperature of the fiber surface in advance so as to penetrate the fiber surface. If the fibers are not pre-heated, the melted resin at high temperatures can harden without uniformly penetrating into the fiber bundles due to temperature differences. In addition, the preheating by the primary carding is a necessary process for removing moisture and volatile substances from the fiber. If the removal can not be efficiently performed, the adhesion of the resin to the resin may deteriorate and the gas may be excessively generated in the impregnation tank The impregnation degree may become uneven.

According to a preferred embodiment of the present invention, it is preferable that the temperature is maintained at 150 to 200 ° C in the first carding step in view of removing sufficient moisture and volatile matter, and cohesion between fibers, It is preferable to maintain 0.3 to 0.7 MPa to open the bag. If the pressure is too low, the effect of carding is insignificant, and if the pressure is too high, the fibers may become bundled again. In this way, the fiber yarn preheated in the first opening step is conveyed to the second spreader through the rollers provided in the first spreader.

The second spreader is provided with rollers that vibrate at a vertical amplitude of 5 to 15 mm per second and rotate at a speed of 600 to 1,200 RPM to impart vibration to the yarns passing through the rollers, The transferred fiber yarn will be fully opened. At this time, it is preferable that the temperature of the second opening is maintained at 150 to 200 ° C to remove moisture and volatile substances inside the fiber, and it is preferable that the pressure applied during the first opening is gradually increased It is preferable to maintain the pressure in the high 0.5 to 1 MPa pressure range.

The fiber yarn passed through the second spreader and transferred to the last third spreader continues to pass through the rollers provided in the third spreader, and the carding in the width direction can proceed. The third spreader is also provided with a roller that vibrates at a speed of 800 to 1500 RPM and a vertical amplitude of 5 to 15 mm per second. At this time, the roller of the third spreader efficiently maintains the open state of the fiber yarn, It may be desirable to rotate at a faster speed than the rollers of the second spreader to minimize the effect of tension on the fibers entering the impregnation tank.

Since the third spreader is just before the fiber yarn is fed into the impregnation tank, the temperature of 160 to 220 ° C, which is similar to the temperature of the impregnation tank, is maintained to prevent the temperature drop of the resin when the fiber yarn meets the high temperature resin in the impregnation tank Which is preferable in terms of reliability. The pressure during the third opening is preferably maintained at 0.8 to 1.5 MPa so as to maintain the opened state in the first and second opening stages and to allow homogeneous impregnation in the additional opening and impregnation tank.

As described above, the fiber yarn is gradually opened through the carding steps over the first, second, and third orders, and finally can be carded to a width of 5 to 20 times the initial insertion width. At this time, the rollers provided in the second spreader and the third spreader are preferably treated with Teflon so as to improve the carding efficiency of the fibers and reduce the frictional force applied to the fiber yarn as much as possible. However, It is not.

On the other hand, it is preferable that the fiber yarn supplied in the step (S1) of the embodiment is one or more high strength fibers selected from among aramid fiber, carbon fiber and glass fiber. There are no particular restrictions on the specific type of fiber yarn, but generally E-glass, which is roving in the case of glass fiber, and PAN-based carbon fiber, such as 3K, 12K, 24K, 48K in roving state And aramid fibers can be para-oriented aramids such as Heraclon (Kolon Industries, Inc.). At this time, the roving fibers should be attached to a creel rack so that there is no single yarn as possible, so that there is no problem of trimming in opening. The diameter is preferably in the range of 1 to 20 占 퐉 per filament, but is not limited thereto.

According to a preferred embodiment of the present invention, the drawing-forming process including the steps (S1) to (S4) may be carried out by various process elements such as the carding efficiency, the retention time of the fiber yarn in the impregnation bath, the resin impregnation rate, Is preferably carried out at a draw rate of 2 to 20 m / min, more preferably 3 to 15 m / min, in order to further improve the impregnation rate. The drawing speed can be controlled by the speed of the rotating roller mounted on the drawing device and the speed of the puller of the UD tape made by cooling after impregnation.

According to a preferred embodiment of the present invention, in the (S3) resin impregnation step, the resin is at least one thermoplastic resin selected from polyolefin, polyamide, polyester, polysulfone and polyacetal, more preferably polyethylene, Polyolefin resins selected from these alloys; A polyamide resin selected from polyamide 6, polyamide 66, polyamide 12 or alloys thereof; A polyester resin selected from polybutylene terephthalate, polyethylene terephthalate, copolyester elastomer, or their alloys; Polysulfone resins such as polyphenylene sulfide resin; And one or more thermoplastic resins selected from the group consisting of polyacetal homo or copolymer resins.

In the present invention, the resin is not particularly limited as long as it is a commonly used thermoplastic resin. However, in order to secure the flowability of the resin and improve the impregnation efficiency, the flow index MI of the resin in the molten state is preferably 40 to 200 as measured according to ASTM D1238 desirable. The resin should be introduced in a sufficiently melted state when it enters the impregnation tank, and an extruder may be provided beside the impregnation tank to add other additives commonly used together with the thermoplastic resin to be added together with the resin. Typical additives include, but are not limited to, antioxidants, secondary heat resistant agents, mold release agents, plasticizers, endurance agents, pigments, dyes, and carbon black.

In the present invention, the resin is preferably impregnated with an impregnation amount of 30 wt% or more with respect to the carded fiber yarn. When the amount of impregnation is less than 30% by weight, the manufactured UD tape can be applied to the use of the final product. Problems with low physical properties may occur. The amount of impregnation may be affected by the speed of the entire process, but may be determined by controlling the thickness of the nip provided at the end of the impregnation bath. At this time, the thickness can be adjusted in accordance with the process in consideration of the thickness and physical properties of the final product.

Further, the fiber yarn (resin-impregnated fiber yarn, i.e., fiber-reinforced resin composite) through which the impregnation amount of the resin is controlled through the nip of the impregnation tank is cooled and solidified in the form of composite material, And is finally recovered by a winding roll. According to a preferred embodiment of the present invention, the cooling in the step (S4) is preferably performed at a cooling temperature of 10 to 60 ° C. If the cooling temperature is less than 10 캜, sufficient cooling to the inside is not performed. As a result, the surface of the finally prepared UD tape becomes poor. When the temperature exceeds 60 캜, the cooling time becomes longer and productivity is lowered. A phenomenon may occur. Cooling may be accomplished with, but not limited to, a device with two or more rollers with chillers.

The composite material produced according to the manufacturing method of the present invention is preferably manufactured in the form of a UD tape, the thickness of the UD tape is 0.1 to 0.5 mm, It may be 10 mm or more and may be different depending on the state or kind of the fibers. However, according to a preferred embodiment of the present invention, the UD tape-type composite material produced by the above method is preferably uniform in fiber distribution at any point based on the cross-section cut in the width direction, It is preferable that the deviation of fiber specific gravity between arbitrary two points is less than 0.05.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for the purpose of illustrating the present invention more specifically, and the present invention is not limited thereto.

Example  One

2200 TEK E-glass fiber (SE1200-2200 TEX, OCV yarn) wound on a krill as a reinforcing fiber was prepared, and then the glass fiber filament wound on the krill was supplied to the first spreader at a speed of 15 m / min. At this time, the width of the fiber supplied to the first spreader was 3 mm, and the temperature and the air pressure of the first spreader were controlled to 170 ° C and 0.5 MPa, respectively. Further, the filament fed to the first spreader is continuously fed to the second spreader through the rollers provided in the first spreader.

In the same manner, the filaments conveyed to the second spreader were passed through the rollers provided in the second spreader to be conveyed to the third spreader, and the temperature and the air pressure of the second spreader were controlled to 170 DEG C and 0.7 MPa, 2 The vibration of vertical spreading of 10 mm per second was applied to the rollers of the spreader (rotational speed 1,000 RPM) to induce the filament to be naturally opened by vibration. When the third spreader is passed, the temperature and the air pressure are controlled to 200 ° C and 0.7 MPa, respectively, and a vibration of 10 mm vertical amplitude per second is applied to the rollers of the third spreader (rotational speed 1,200 rpm) so that the filaments are continuously opened .

Then, the filament passing through the spreading step of the above three stages was transferred to a impregnation die to perform resin impregnation. At this time, a polypropylene resin having a melt index (MI) of 140 (HP5035, Polymira) was supplied to the impregnation tank, and the temperature of the impregnation tank was set to 260 ^° C. Finally, the resin impregnated filament that passed through the impregnation bath was passed through a 30 ° C cooling roll and wound on a winder to produce a UD tape. The width of the finally fabricated UD tape was 15 mm and the thickness was 0.3T.

Example  2

A UD tape was prepared in the same manner as in Example 1, except that a polyamide 6 resin (KN120, manufactured by Kolon Plastic Co., Ltd.) having a melt index of 40 was supplied to the impregnation tank.

Example  3

A UD tape was prepared in the same manner as in Example 1, except that a polybutylene terephthalate resin (KP210, manufactured by Kolon Plastic Co., Ltd.) having a melt index of 45 was supplied to the impregnation tank.

Example  4

A UD tape was prepared in the same manner as in Example 1, except that a polyacetal resin (K900, manufactured by Kolon Plastic Co., Ltd.) having a melt index of 45 was supplied to the impregnation tank.

Example  5

A UD tape was prepared in the same manner as in Example 2 except that 12K carbon fiber (Torayca, Toray) was used as reinforcing fiber instead of E-glass fiber.

Comparative Example

A UD tape was manufactured in the same manner as in Example 1 except that the spreading process by the second spreader and the third spreader was omitted.

Measurement example  One

In order to measure the degree of fiber arrangement of the UD tape manufactured through the above examples and comparative examples, a cross section SEM photograph taken along the width direction of each specimen was taken, and 10 sections were arbitrarily taken from each SEM photograph, It was confirmed that uniform fiber densities were observed in all sections. Furthermore, it was more accurate to obtain a quantitative value for any sampling period of 10 samples in accordance with ASTM D792 by measuring the specific gravity of the fiber, and reflects the result in Table 1 below. In this case, the specific gravity of the section showing the highest gravity and the gravity of the lowest gravity were measured, and when the gravity difference was 0.05, the uneven impregnation was considered.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example Highest specific gravity 1.43 1.55 1.68 1.78 1.4 1.5 Lowest specific gravity 1.40 1.51 1.65 1.74 1.39 1.35 Weight difference 0.03 0.04 0.03 0.04 0.01 0.15 Uniformity Good Good Good Good Good Bad

Table 1 shows that when the fibers are opened according to the present invention, the degree of arrangement of the fibers is improved and the uniformity of the fibers in the UD-Tape obtained as the final product is all good. On the other hand, in the case of the comparative example, it was analyzed that when the first carding is performed only as in the ordinary process, the fibers are not uniformly distributed in the UD-tape manufactured as a final product, and the difference in specific gravity is large. From these results, it can be seen that the resins of Examples 1 to 5 prepared according to the present invention can be uniformly impregnated with the resin because the fiber arrangement is excellent, that is, the uniformity is excellent.

In particular, as can be seen from the photographs reflected in FIG. 1, in the case of the product to which the carding step was applied (Example 1, right side of FIG. 1) as in the present invention, the arrangement of the resin-impregnated fibers was uniform, (Comparative Example, left side of Fig. 1) showed that the state of the resin-impregnated fibers was not sufficiently released and aggregated with each other, so that the difference in the final product was remarkable depending on the presence or absence of opening .

Measurement example  2

The UD tapes prepared in the above Examples and Comparative Examples were laminated in the same direction (0 ^° ), and then pressed at a pressure of 3 Bar and a temperature of 280 ° C. to prepare sheets having a thickness of 3.2 tons. The physical property test was conducted, and the measured physical property test results were reflected in Table 2 below.

- Tensile Strength: A test piece according to the standard was manufactured using the manufactured sheet, and then measured at room temperature using an Instron tensile tester according to ASMT D640

- Flexural Strength / Elastic Modulus: The flexural strength / elastic modulus was measured at 23 ° C according to ASTM D 638 using a Universal testing machine (model SFM-10) manufactured by United Co. of the United States.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example The tensile strength
(MPa) 650 750 730 700 1,600 600 Flexural strength
(MPa) 710 900 820 800 1,100 660 Flexural modulus
(GPa) 25 31 28 27 80 20

As a result of the physical properties test, as shown in Table 2, although there were some differences according to the resin applied, it was confirmed that the properties of Examples 1 to 4 were all improved as compared with those of Comparative Examples . Particularly, when Example 1 and Comparative Example using the same resin were compared, when the carding step was carried out as in the present invention, the average was increased by about 10% or more in terms of physical properties, It was found that effective carding affects the physical properties of the final product.

Claims (8)

(S1) a fiber supplying step of supplying a bundle of fiber yarns;
(S2); a fiber opening step of opening the bundle-type fiber yarn supplied in a width direction of 5 to 20 times the supplied width;
(S3) a resin impregnating step of impregnating the resin into the resin; And
(S4) a cooling step of cooling the resin-impregnated fiber yarn;
The method according to claim 1,
The fiber opening step may include a first opening step for preheating the supplied bundle-type fiber yarn; A second opening step of applying vibration to the first opened fiber yarn; And a third opening step of applying further vibration to the second opened fiber yarn. ≪ RTI ID = 0.0 > 11. < / RTI >
3. The method according to claim 1 or 2,
The fiber opening step may include a first opening step of preheating the supplied bundled fiber yarn at a temperature of 150 to 200 DEG C and an air pressure of 0.3 to 0.7 MPa; A second opening step of applying vibration to the first opened fiber yarn at a vertical amplitude of 5 to 15 mm per second at a temperature of 150 to 200 DEG C and an air pressure of 0.5 to 1 MPa; And a tertiary carding step in which the secondary carded fiber yarn is further subjected to vibration at a vertical amplitude of 5 to 15 mm per second at a temperature of 160 to 220 DEG C and an air pressure of 0.8 to 1.5 MPa, Process for manufacturing composite material.
The method according to claim 1,
Wherein the fiber yarn supplied in the step (S1) is one or more high-strength fibers selected from aramid fiber, carbon fiber and glass fiber.
The method according to claim 1,
Wherein the drawing forming process including the steps (S1) to (S4) has a process speed of 2 to 20 m / min.
The method according to claim 1,
Wherein the resin in step (S3) is at least one thermoplastic resin selected from polyolefin, polyamide, polyester, polysulfone, and polyacetal.
The method according to claim 1,
Wherein the cooling in the step (S4) is performed at a temperature of 10 to 60 캜.
The method according to claim 1,
Wherein the composite material has a fiber specific gravity deviation of less than 0.05 measured in two arbitrary sections based on the cross section of the composite material in the width direction.

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