KR102140515B1 - Composite material using hollow fiber and method for preparing the same - Google Patents

Abstract

A first fiber; Second fibers; It includes; a binding material for binding the first fiber and the second fiber; includes, the first fiber and the second fiber is a single-layer structure that is bound by the binding material to form an irregular network structure including pores , The first fiber is a hollow fiber including an inorganic fiber or an organic fiber, the second fiber includes a first thermoplastic resin, the binder includes a second thermoplastic resin, the inorganic fiber or organic fiber, and The melting point of the first thermoplastic resin provides a composite material using a hollow fiber that is higher than the melting point of the second thermoplastic resin, respectively, and a method for manufacturing the same.

Description

Composite material using hollow fiber and its manufacturing method {COMPOSITE MATERIAL USING HOLLOW FIBER AND METHOD FOR PREPARING THE SAME}

It relates to a composite material using a hollow fiber and a method for manufacturing the same.

Conventional fiber-reinforced composite materials are made of glass fiber, carbon fiber, and PET fiber reinforced fibers dispersed in a matrix formed of a polymer. At this time, when the shape of the final composite material has a dense structure, it is difficult to exhibit light weight and sound absorption performance.

On the other hand, a composite material of a porous structure capable of exhibiting light weight and excellent sound absorption performance is used, and as the sound energy from the outside is attenuated by the vibration of the structure and the pore-formed structure and the fiber, the light weight and sound absorption sound absorption It can be applied to automotive parts that require performance.

One embodiment of the present invention provides a composite material capable of implementing excellent sound absorbing and insulating performance and light weight. Unlike the conventional reinforced fiber, the composite material may use hollow fibers having an empty center portion of the fiber, thereby reducing the weight of the composite material according to reduction in fiber density and achieving excellent sound absorbing and insulating performance compared to the conventional reinforced fiber.

Another embodiment of the present invention provides a method of manufacturing a composite material using hollow fibers.

In one embodiment of the invention, the first fiber; Second fibers; It includes; a binding material for binding the first fiber and the second fiber; includes, the first fiber and the second fiber is a single-layer structure that is bound by the binding material to form an irregular network structure including pores , The first fiber is a hollow fiber including an inorganic fiber or an organic fiber, the second fiber includes a first thermoplastic resin, the binder includes a second thermoplastic resin, the inorganic fiber or organic fiber, and Each of the melting points of the first thermoplastic resin provides a composite material using hollow fibers higher than the melting point of the second thermoplastic resin.

In another embodiment of the present invention, (a) dispersing the reinforcing fibers and bicomponent polymer fibers in an aqueous solution to prepare a slurry solution; (b) forming a web from the slurry solution by a wet papermaking process; (c) drying the formed web; And (d) laminating at least one layer of the dried web, followed by heat treatment to prepare a composite material having a single layer structure, wherein the reinforcing fibers are hollow fibers including inorganic fibers or organic fibers. , Wherein the bicomponent polymer fiber includes a core portion including a first thermoplastic resin and a sheath portion including a second thermoplastic resin, and the melting point of the inorganic fiber or organic fiber, and the first thermoplastic resin. It provides a method for producing a composite material using a hollow fiber higher than the melting point of each of the second thermoplastic resin.

The composite material using the hollow fiber may realize excellent sound absorbing and insulating performance and light weight, as sound energy is attenuated by vibration of the hollow fiber and resonance in an empty space inside the fiber.

Accordingly, the composite material using the hollow fiber can be applied to automobile parts, such as underbody covers and wheel guards, which require sound absorbing and insulating performance and weight reduction.

The composite material using the hollow fiber is a method using a wet process, and it is possible to realize uniform physical properties over the entire process compared to a dry process, and provides an effect of improving fiber dispersibility.

1 is a schematic schematic diagram of a composite material using hollow fibers according to an embodiment of the present invention.
2 is a composite material using a hollow fiber according to an embodiment of the present invention, schematically showing a cross section perpendicular to the longitudinal direction of the hollow fiber.
Figure 3 schematically shows the process of manufacturing a composite material using a hollow fiber according to an embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will be clarified with reference to embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and the general knowledge in the technical field to which the present invention pertains. It is provided to fully inform the holder of the scope of the invention, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.

Hereinafter, a composite material using a hollow fiber and a method for manufacturing the same according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In one embodiment of the invention, the first fiber; Second fibers; It includes; a binding material for binding the first fiber and the second fiber; includes, the first fiber and the second fiber is a single-layer structure that is bound by the binding material to form an irregular network structure including pores , The first fiber is a hollow fiber including an inorganic fiber or an organic fiber, the second fiber includes a first thermoplastic resin, the binder includes a second thermoplastic resin, the inorganic fiber or organic fiber, and Each of the melting points of the first thermoplastic resin provides a composite material using hollow fibers higher than the melting point of the second thermoplastic resin.

In the present specification, the first fiber and the second fiber are described as being separately classified as the first and the second for convenience, in order to indicate that they are separate components from each other in consideration of their raw material components. It does not mean.

In addition, similarly, in the present specification, the first thermoplastic resin, the second thermoplastic resin, and the third thermoplastic resin are simply described as being separated into first, second, and third for convenience, to indicate that they are separate structures from each other. It does not mean resins of different materials.

1 is a schematic schematic diagram of a composite material using hollow fibers according to an embodiment of the present invention.

Referring to FIG. 1, the composite material 10 includes a first fiber 11 and a second fiber 12, and a binding material binding the first fiber 11 and the second fiber 12 (13).

At this time, the first fiber 11 is a hollow fiber including an inorganic fiber or an organic fiber, the second fiber 12 includes a first thermoplastic resin, and the binder 13 includes a second thermoplastic resin do. In addition, the melting point of the inorganic fiber or the organic fiber, and the first thermoplastic resin is higher than the melting point of the second thermoplastic resin, respectively.

The binding material 13 is present in a coated state on a part or the entire surface of each of the first fiber 11 and the second fiber 12. Coating parts formed on the surfaces of the first fiber 11 and the second fiber 12 by the binder 13 are fused to each other, so that the first fiber 11 and the second fiber 12 ) between; Between the plurality of first fibers 11; Alternatively, the plurality of the second fibers 12 may be irregularly bound. Thus, the composite material 10 may be a single layer structure having an irregular three-dimensional network structure including open pores.

Since sound waves coming through the open cell have an effect of being attenuated by vibration of the fiber, sound absorbing and insulating performance can be realized. In addition, as sound energy is attenuated by a resonance phenomenon in an empty space in the hollow fiber, excellent sound absorbing and insulating performance can be realized.

The first fiber 11 is made of hollow fiber including inorganic fiber such as glass fiber or carbon fiber or organic fiber made of thermoplastic resin. The second fiber 12 is made of a thermoplastic resin material.

The specific gravity of the inorganic fiber or organic fiber and the first thermoplastic resin is preferably greater than about 1, and more preferably about 1 to about 2. The composite material 10 is manufactured by a wet papermaking process, and the reinforcing fibers and the bicomponent polymer fibers are blended and dispersed in an aqueous solution. At this time, considering that the specific gravity of water is about 1, when the specific gravity of the first fiber 11 and the second fiber 12 is greater than about 1, the first fiber 11 and the second fiber 12 are It can show excellent dispersibility without floating on the surface of the aqueous solution, and may exist in the form of fibers even after thermoforming.

The hollow fiber is a fiber having a penetrating portion penetrating in the longitudinal direction of the fiber inside the fiber, and provides a lightweight composite material and excellent sound absorbing and insulating performance.

The hollow fiber, the first fiber 11 may have a length of about 10 mm to about 20 mm, for example, about 12 mm to about 14 mm. Further, the length of the second fiber 12 may be about 1 mm to about 10 mm. When the lengths of the first fiber 11 and the second fiber 12 satisfy each of the above ranges, the dispersibility of the fibers is excellent, and it is easy to manufacture a web using a wet papermaking process.

At this time, in order to realize the complementary effect of strength and rigidity of the first fiber 11 as the hollow fiber, the length of the first fiber 11 may be longer than the length of the second fiber 12.

2 is a composite material using a hollow fiber according to an embodiment of the present invention, schematically showing a cross section perpendicular to the longitudinal direction of the hollow fiber.

Referring to FIG. 2, the cross-sectional diameter of the first fiber 11 as the hollow fiber, that is, the outer diameter X may be about 5 μm to about 20 μm, for example, about 5 μm to about 10 μm Can be In addition, the diameter of the cross section perpendicular to the longitudinal direction of the second fiber 12 may be about 5 μm to about 20 μm. The thickness of the first fibers 11 and the second fibers 12, which are the hollow fibers, satisfies the above range, thereby realizing appropriate physical interweaving properties.

The ratio of the outer diameter (X) to the inner diameter (Y) of the hollow fiber 14 may be about 1: 0.2 to 1: 0.9. The outer diameter (X) and the inner diameter (Y) mean the mean diameter of the outer contour and the mean diameter of the inner contour, respectively, in the cross section of the hollow fiber.

In addition, the shape of the cross section of the hollow fiber may be various shapes such as a circle or a polygon, and the shape of the cross section of the hollow fiber and the shape of the cross section of the through portion forming the hollow may be a structure that conforms to each other and a structure that does not conform. It might be. 2 is an embodiment of the hollow fiber, and shows an example in which the shape of the cross-section is circular and the shape of the cross-section of the through-section forming the hollow is also conforming to this.

The hollow fiber may have a hollow ratio of about 20% to about 90% by volume. The hollowness ratio refers to a volume ratio of an empty space by a through portion of the hollow fiber. When the hollow fiber has a hollow fiber ratio that satisfies the above range, the hollow fiber reinforced fiber has an improved porosity of about 60% or more compared to that of the existing porous structured reinforced fiber, thereby improving the sound absorbing and insulating effect according to the resonance phenomenon in the hollow space in the fiber. Can be maximized, and a high weight reduction effect can be realized.

With respect to 100 parts by weight of the first fiber 11, the total content of the second fiber 12 and the binder 13 may be about 20 parts by weight to about 60 parts by weight. If it is out of this range, it may be difficult to exhibit excellent strength according to the first fiber 11 and the second fiber 12, and may be insufficient to form a porous structure by the binder 13.

Further, with respect to 100 parts by weight of the second fiber 12, the binder 13 may be about 30 parts by weight to about 200 parts by weight.

The second fiber 12 and the binder 13 originate from a bicomponent polymer fiber, and the second fiber 12 corresponds to a core portion of the bicomponent polymer fiber, and the binder 13 ) Corresponds to the sheath of the bicomponent polymer fiber, and the first fiber 11 originates from reinforcing fibers. In the manufacturing method to be described later, by controlling the content ratio of each component constituting the bicomponent polymer fiber, and the length and thickness of the reinforcing fiber and bicomponent polymer fiber, a composite material 10 capable of exhibiting excellent sound absorbing and insulating performance and weight reduction is provided. Can be obtained.

The first thermoplastic resin forming the second fiber 12 is, for example, polyester, polypropylene (PP), polyethylene (PE), acrylic butadiene styrene (ABS), polycarbonate (PC), nylon (Nylon) , Polyvinyl chloride (PVC), polystyrene (PS), polyurethane (PU), polymethyl methacrylate (PMMA), polylactic acid (PLA), at least one selected from the group consisting of polytetrafluoroethylene and combinations thereof It may include.

The second thermoplastic resin forming the binder 13 is, for example, polyester, polypropylene (PP), polyethylene (PE), acrylic butadiene styrene (ABS), polycarbonate (PC), nylon (Nylon), At least one selected from the group consisting of polyvinyl chloride (PVC), polystyrene (PS), polyurethane (PU), polymethyl methacrylate (PMMA), polylactic acid (PLA), polytetrafluoroethylene, and combinations thereof It can contain.

The binder 13 corresponds to the sheath portion of the bicomponent polymer fiber, and the sheath portion melts under a predetermined temperature condition, and a part thereof is transferred to the surface of the first fiber 11, and as the binder 13 It serves to bind the first fiber 11 and the second fiber 12.

Therefore, the second thermoplastic resin constituting the binder 13 has a lower melting point than the inorganic fibers or organic fibers constituting the first fiber 11 and the first thermoplastic resin.

More specifically, the inorganic fiber or organic fiber, and the first thermoplastic resin may have a melting point of about 200°C to about 280°C, respectively. If it is outside this range, as the binder melts, they may melt together, and thus it may be difficult to maintain the fiber shape. If their melting point is less than 200°C, the thermoforming temperature must be lowered to maintain the fiber shape, and the thermal stability of the composite material 10 is lowered, resulting in deformation of dimensions.

The second thermoplastic resin may have a melting point of less than about 200°C, and specifically, about 100°C to less than about 200°C.

The melting point of the inorganic fiber or the organic fiber, and the first thermoplastic resin and the second thermoplastic resin can be measured using a thermogravimetric analysis (TGA) instrument.

As described above, the composite material may exhibit high weight reduction, including hollow fibers having a hollowness ratio of about 20% to about 90% by volume, and specifically, a basis weight of about 500g/m ² to about 2000g/m Can be ² In addition, the thickness of the composite material may be about 1mm to about 10mm, for example, about 2mm to about 5mm.

In addition, the composite material using the hollow fiber may be applied to an underbody cover of an automobile component requiring high weight and sound absorption performance. In particular, the composite material may be disposed on the side of the vehicle body to implement high strength for supporting members constituting the vehicle body, and prevent foreign matters entering the vehicle body from the ground through the mesh structure including pores to pass through and prevent accumulation. It has the effect of blocking or absorbing noise introduced into the furnace.

In another embodiment of the present invention, a method for manufacturing a composite material using the hollow fiber is provided.

Figure 3 schematically shows the process of manufacturing a composite material using a hollow fiber according to an embodiment of the present invention.

First, the step of manufacturing the composite material 10 using the hollow fiber includes: (a) preparing a slurry solution by dispersing reinforcing fibers and bicomponent polymer fibers in an aqueous solution; (b) forming a web from the slurry solution by a wet papermaking process; (c) drying the formed web; And (d) laminating at least one layer of the dried web, followed by heat treatment to produce a single layer composite material.

In this case, the reinforcing fiber is a hollow fiber including an inorganic fiber or an organic fiber, and the bicomponent polymer fiber includes a core portion including a first thermoplastic resin and a sheath portion including a second thermoplastic resin. do.

The melting points of the inorganic fibers or organic fibers and the first thermoplastic resin are higher than those of the second thermoplastic resin, respectively. Matters regarding the inorganic fiber or organic fiber, the first thermoplastic resin and the second thermoplastic resin are as described above.

The slurry solution is prepared by dispersing the reinforcing fibers and the bicomponent polymer fibers in an aqueous solution.

In the step of preparing the slurry solution, the total content of the reinforcing fibers and the bicomponent polymer fibers per 1 L of the aqueous solution may be about 0.1 g to about 10 g, and excellent dispersibility can be secured in this range, and uniformity A thickness of web can be produced.

In addition, the pH of the aqueous solution may be from about 1 to about 4. By adjusting the pH of the aqueous solution to the above range, dispersibility can be further improved by generating charges on the surfaces of the reinforcing fibers and the bicomponent polymer fibers.

The slurry solution may include about 20 parts by weight to about 60 parts by weight of the bicomponent polymer fiber with respect to 100 parts by weight of the reinforcing fibers.

In addition, the bicomponent polymer fiber may include about 30 parts by weight to about 200 parts by weight of the sheath part, and about 50 parts by weight to about 100 parts by weight, based on 100 parts by weight of the core part. have.

The web is produced from the slurry solution by a wet papermaking process.

The slurry solution is prepared by uniformly mixing and stirring the reinforcing fibers and the bicomponent polymer fibers in an aqueous solution using a stirrer 20. The slurry solution 30 is made of a wet web 50 while following a mesh moving along the conveyor belt 40.

The wet web 50 may be manufactured as the slurry solution 30 is dehydrated through the vacuum intake system 60.

The conveyor belt 40 may have a slope at a predetermined angle with respect to the ground, if necessary. As a result, at least a portion of the reinforcing fibers and the bicomponent polymer fibers may have orientation in the direction of movement of the conveyor belt, and in this case, high strength may be achieved in the orientation direction.

Subsequently, the wet web 50 is dried through a dryer, and drying is preferably performed at a temperature lower than the melting point of the second thermoplastic resin so that the sheath portion of the bicomponent polymer fiber does not melt, and is about 100°C to about Drying can be performed at 180°C.

Subsequently, at least one layer of the dried web is laminated and then heat-treated to prepare a composite material having a single-layer structure. As the web is stacked and heat-treated, the interface between the layers disappears, and the composite material 10 having a single layer structure can be formed.

The heat treatment may be performed at a temperature higher than the melting point of the second thermoplastic resin forming the sheath portion of the bicomponent polymer fiber, and lower than the melting point of the inorganic fiber or organic fiber, and the first thermoplastic resin. The sheath portion of the bicomponent polymer fiber is melted to bind the core portion of the bicomponent fiber and the reinforcing fiber to each other.

For example, the heat treatment may be performed at a temperature of about 120°C to about 200°C and a pressure of about 1bar to about 20bar. If it is outside this range, the adhesiveness between the interfaces of the sheet decreases, and the composite material is difficult to manufacture in a single layer structure. In addition, when the pressure is less than 1 bar, the adhesion between the interfaces of the sheet may decrease, and when it exceeds 20 bar, the shape of the hollow fiber is difficult to maintain, and the physical properties of the composite material may deteriorate.

That is, the sheath portion of the bicomponent polymer fiber is melted by the heat treatment to serve as a binder, and at the same time, it is possible to form a pore structure by physically weaving the core portion of the reinforcing fiber and the bicomponent fiber. In addition, a composite material having a thickness of about 1 mm to about 10 mm may be prepared by the heat treatment.

Looking at the specific embodiment of the composite material using the hollow fiber and a method of manufacturing the same as follows.

<Examples and Comparative Examples>

Example

A polyester core portion having a melting point of 260°C and a polyester sheath portion having a melting point of 160°C have a weight ratio of 50:50, a length of 5 mm, and a bicomponent polymer fiber having a cross section perpendicular to the longitudinal direction and a diameter of 20 μm. Was prepared.

Subsequently, a polyester fiber having a length of 12 mm, a cross-section perpendicular to the longitudinal direction (outer diameter) of 7 µm, a melting point of 250° C., and a porosity of 60% by volume was prepared as reinforcing fibers.

Based on 100 parts by weight of the reinforcing fibers, 40 parts by weight of the bicomponent polymer fibers were blended, and stirred in an aqueous hydrochloric acid (HCl) solution adjusted to pH 2 to 2.5 for 1 hour to prepare a slurry solution. In this case, the reinforcing fiber and the bicomponent polymer fiber per 1L of the aqueous solution were made to total 2g.

Subsequently, the slurry solution was passed through a vacuum suction system while moving through a mesh moving on a conveyor belt to prepare a wet web.

Subsequently, the wet web was completely dried by passing through an oven dryer at 140°C, four dried webs were stacked, and pressurized at 20 bar at 180°C to have a thickness of 3 mm and a plate weight of 1200 g/m ² A composite material was prepared.

Comparative example

The composite material was prepared under the same conditions as in Example 1, except that the length was 12 mm, the cross section perpendicular to the longitudinal direction had a diameter (outer diameter) of 7 µm, and a polyester fiber having a melting point of 250° C. was prepared as a reinforcing fiber. It was prepared. The composite material has a thickness of 3 mm and a basis weight of 1200 g/m ² .

2. Method for evaluating physical properties and results

Sound absorption performance evaluation

For the composite materials of the examples and the comparative examples, the sound absorption performance was compared by measuring the average sound absorption coefficient. The average sound absorption coefficient was measured at a frequency in the high frequency range (500 Hz to 6300 Hz) based on KS2816-2. The results are shown in Table 1 below.

[Table 1]

When referring to the results of Table 1, it can be seen that the composite material of the example has better sound absorption performance than the composite material of the comparative example.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and may be manufactured in various different forms, and having ordinary knowledge in the technical field to which the present invention pertains. It will be understood that a person can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

10: Composite material
11: first fiber
12: second fiber
13: binder
20: stirrer
30: slurry solution
40: conveyor belt
50: Web
60: vacuum intake system

Claims (16)

A first fiber; Second fibers; It includes; a binding material for binding the first fiber and the second fiber; includes, the first fiber and the second fiber is a single-layer structure that is bound by the binding material to form an irregular network structure including pores ,
The first fiber is a hollow fiber comprising an inorganic fiber or an organic fiber,
The second fiber includes a first thermoplastic resin,
The binder includes a second thermoplastic resin,
The first fiber has a length of 10mm to 20mm, the second fiber has a length of 1mm to 10mm, and the length of the first fiber is longer than the length of the second fiber,
The inorganic fibers or organic fibers, and the melting point of the first thermoplastic resin is higher than the melting point of the second thermoplastic resin, respectively
Composite material using hollow fiber.
According to claim 1,
The first fiber and the second fiber form a coating part formed by coating a part or all of the binding material on the surface, and the coating parts are fused to each other and bound.
Composite material using hollow fiber.
According to claim 1,
The first fiber has a hollow ratio of 20% to 90% by volume
Composite material using hollow fiber.
According to claim 1,
With respect to 100 parts by weight of the first fiber, the total content of the second fiber and the binder is 20 parts by weight to 60 parts by weight
Composite material using hollow fiber.
According to claim 1,
With respect to 100 parts by weight of the second fiber, the binder is 30 parts by weight to 200 parts by weight
Composite material using hollow fiber.
According to claim 1,
The first fiber has a cross-sectional diameter of 5㎛ to 20㎛
Composite material using hollow fiber.
According to claim 1,
The second fiber has a cross-sectional diameter of 5㎛ to 20㎛
Composite material using hollow fiber.
According to claim 1,
The inorganic fiber or organic fiber, and the melting point of each of the first thermoplastic resin is 200 ℃ to 280 ℃,
The melting point of the second thermoplastic resin is less than 200 ℃
Composite material using hollow fiber.
According to claim 1,
The basis weight of the composite material is 500g/m ² to 2000g/m ²
Composite material using hollow fiber.
(A) preparing a slurry solution by dispersing the reinforcing fibers and bicomponent polymer fibers in an aqueous solution;
(b) forming a web from the slurry solution by a wet papermaking process;
(c) drying the formed web; And
(D) laminating the dried web (web) at least one layer and then heat-treating to prepare a composite material having a single-layer structure;
The reinforcing fibers are hollow fibers including inorganic fibers or organic fibers,
The bicomponent polymer fiber includes a core portion including a first thermoplastic resin and a sheath portion including a second thermoplastic resin,
The hollow fiber has a length of 10 mm to 20 mm, the bicomponent polymer fiber including the core portion has a length of 1 mm to 10 mm, and the length of the hollow fiber is longer than the length of the bicomponent polymer fiber containing the core portion,
The melting point of the inorganic fiber or organic fiber, and the first thermoplastic resin is higher than the melting point of the second thermoplastic resin, respectively
Method for manufacturing a composite material using hollow fibers.
The method of claim 10,
The inorganic fiber or organic fiber, and the melting point of each of the first thermoplastic resin is 200 ℃ to 280 ℃,
The melting point of the second thermoplastic resin is less than 200 ℃
Method of manufacturing a composite material using hollow fibers.
The method of claim 10,
The slurry solution contains 20 parts by weight to 60 parts by weight of the bicomponent polymer fiber with respect to 100 parts by weight of the reinforcing fiber
Method of manufacturing a composite material using hollow fibers.
The method of claim 10,
The total content of the reinforcing fiber and the bicomponent polymer fiber per 1 L of the aqueous solution is mixed to be 0.1 g to 10 g
Method of manufacturing a composite material using hollow fibers.
The method of claim 10,
PH of the aqueous solution is 1 to 4
Method of manufacturing a composite material using hollow fibers.
The method of claim 10,
Forming a web from the slurry solution by a wet papermaking process involves a vacuum suction process.
Method of manufacturing a composite material using hollow fibers.
The method of claim 10,
The step of drying the formed web is performed at a temperature lower than the melting point of the second thermoplastic resin,
The step of manufacturing a composite material having a single-layer structure by laminating at least one layer of the dried web and heat-treating is higher than the melting point of the second thermoplastic resin, and the inorganic fiber or organic fiber, and the first thermoplastic resin Is performed at a temperature lower than the melting point of
Method of manufacturing a composite material using hollow fibers.

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