KR20200082391A - Interfacial Bonding Enhanced Basalt Long-Fiber Reinforced Thermoplastic Composite Material and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to a basalt long fiber-reinforced thermoplastic composite material and a manufacturing method thereof. More specifically, the present invention relates to the composite material which not only exhibits excellent interfacial properties between basalt long fibers and a polymer matrix, but also exhibits excellent mechanical properties. The basalt long fiber-reinforced thermoplastic composite material with improved interfacial properties includes the basalt long fibers and a thermoplastic polymer base material.

Description

{Interfacial Bonding Enhanced Basalt Long-Fiber Reinforced Thermoplastic Composite Material and Manufacturing Method Thereof}

The present invention relates to a basalt long fiber-reinforced thermoplastic composite material and a method for manufacturing the same, and more particularly, to a composite material showing excellent mechanical properties as well as excellent interfacial properties between basalt long fibers and a polymer matrix.

Basalt fiber is an environmentally friendly fiber made of basalt that has been weathered for over tens of millions of years and has been stabilized, and has excellent heat resistance, alkali resistance, and mechanical properties. These basalt fibers are classified into continuous fibers and short fibers (staple fibers), and usually continuous fibers are characterized by unrestricted long lengths and horizontal arrangements, and short fibers are characterized by long lengths, curvatures, and irregular arrangements. .

These basalt fibers are high strength and have high elastic modulus, and have excellent heat resistance and chemical resistance as compared to glass fibers mainly used as existing reinforcing materials, and their use is remarkably increased as an excellent reinforcing material in manufacturing fiber-reinforced composite materials. have. In addition, due to the alkali-resistant properties of the basalt fiber, it is attracting attention as a corrosion-resistant reinforcement material when exposed to a salty marine environment.

On the other hand, in general, when a long type of fiber is used as a reinforcing agent for a composite material, it exhibits more excellent strength, stiffness, and impact characteristics than a conventional short fiber reinforced composite material. Accordingly, research on long fiber-reinforced thermoplastic composite materials (LFT) has been actively conducted in recent years.

The long fiber-reinforced composite material is a type of long fiber-reinforced polymer composite composed of a thermoplastic polymer and a reinforcing agent having a high aspect ratio of 200 to 3000. In particular, as the use of LFT materials in automobiles and other industries increases, it is essential to study the physical properties of LFT materials under high load, high energy, high elongation, and high impact. Therefore, a systematic analysis of viscoelastic and thermodynamic behavior as well as mechanical behavior for LFT materials is required. In general, the fiber-reinforced composite material is determined by the properties of the composite material according to the process conditions, fiber length, orientation, interface properties, and the like.

However, the LFT material exhibits strong mechanical strength due to the length of the mixed long fibers, but as the length of the fibers increases, it adversely affects the processing of the LFT composite material. Typically, the interfacial adhesion strength between the fiber and the polymer matrix is strongly related to the surface structure of the fiber and the wettability of the polymer matrix. When the length of the fiber increases, the interfacial adhesive strength with the polymer matrix decreases due to the entanglement of long fibers and strong interaction between the fibers, making it difficult to process and manufacture the LFT composite material.

Therefore, in order to manufacture the LFT composite material showing superior strength, stiffness, and impact characteristics using long fibers, a method of solving the entanglement of long fibers and improving processability to improve the interfacial adhesion strength with the polymer matrix R&D is needed.

Korean Registered Patent No. 10-0465272

The basalt long fiber-reinforced thermoplastic composite material according to the present invention and a method for manufacturing the same are intended to solve the above problems,

An object of the present invention is to provide a basalt long fiber composite material that exhibits excellent mechanical properties by preventing the bending, agglomeration, and entanglement of long fibers and thereby improving the interfacial adhesion strength with the polymer matrix.

In the present invention, by adding a wax or rubber-based compatibilizer together with the polymer matrix, the agglomeration and entanglement of long fibers are prevented to improve the dispersibility of the fibers in the composite material due to the improved interfacial adhesion strength, and the fibers and It is intended to process and manufacture composite materials by improving the wettability of the polymer matrix.

On the one hand, the present invention

Basalt long fibers; And

It includes; a thermoplastic polymer base material for coating the basalt long fibers;

The thermoplastic polymer base material further comprises a rubber or wax-based compatibilizer, providing a basalt long fiber-reinforced thermoplastic composite material with improved interfacial properties.

On the other hand, the present invention

(i) adding a thermoplastic polymer base material and a compatibilizer to an extruder hopper, and applying heat to prepare a molten polymer base material;

(ii) discharging the molten thermoplastic polymer base material from an extruder and introducing it into an impregnation tank;

(iii) inserting basalt continuous fibers into the impregnation tank to impregnate the molten polymer base material;

(iv) winding the basalt continuous fiber from the outside of the impregnation tank to produce a prepreg of basalt continuous fiber impregnated with a polymer base material;

(v) cutting the basalt continuous fiber prepreg to produce basalt long fiber pellets; And

(vi) preparing a basalt long fiber composite material by injection molding the cut basalt long fiber pellets; Containing,

Provided is a method of manufacturing basalt long fiber reinforced thermoplastic composite material with improved interfacial properties.

The basalt long fiber-reinforced thermoplastic composite material according to the present invention prevents agglomeration and entanglement of long fibers, improves interfacial adhesion strength, and improves wettability between the polymer matrix and fibers, thereby exhibiting excellent mechanical properties.

1 shows a configuration diagram for a melt impregnation process according to the present invention.
2 is a basaltic long fiber pellet cut into (a) nylon 6 resin impregnated basalt continuous fiber prepreg and (b) 2.5 mm, (c) 5 mm and (d) 10 mm according to an embodiment of the present invention. It is a picture shown.
3 is a photograph showing a composite material specimen produced by the injection molding process according to the present invention.
Figure 4 is an optical micrograph showing the composite material surface according to the length of the basalt long fiber and the type of compatibilizer according to an embodiment of the present invention.
5 is an Izod impact strength graph of a basalt long fiber reinforced composite material according to a length and compatibilizer of a basalt long fiber according to an embodiment of the present invention.
Figure 6 is a graph of the strength and strength (a) and bending strength (b) of the basalt long fiber reinforced composite material according to the length and compatibilizer of the basalt long fiber according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail.

Basalt long fiber reinforced thermoplastic composite material with improved interfacial properties according to an embodiment of the present invention,

Basalt long fibers; And

It includes; a thermoplastic polymer base material for coating the basalt long fibers;

The thermoplastic polymer base material further comprises a rubber or wax-based compatibilizer.

In one embodiment of the present invention, the thermoplastic polymer may be one selected from the group consisting of polyamide 66, nylon 6, polyethylene, polypropylene, polyketone, polyurethane, polystyrene, acrylic and acrylonitrile butamine, , But is not limited to this. It is preferable to use nylon 6 resin. It is preferable that the polymer has a high flow property.

By using the thermoplastic polymer having high flowability, it is easy to process, and a polymer and fiber-reinforced polymer composite material having high mechanical strength and thermal properties can be produced. In addition, a polymer composite material having excellent interfacial properties between polymer and fiber can be produced.

In one embodiment of the present invention, the basalt fiber is a continuous fiber, and is wound with a constant tension on one side of the extruder to impregnate the thermoplastic polymer with a constant thickness. In the present invention, through the resin impregnation process, the impregnation rate of the resin present on the fiber is high, and the resin permeability between the fiber and the fiber is excellent, so that the continuous fiber prepreg having a constant impregnation rate of the resin can be manufactured. In addition, by continuously controlling the distance between the fibers, it is possible to manufacture a continuous prepreg of uniform fibers.

In one embodiment of the present invention, the extruder is a twin-screw extruder (Twin-Screw extruder) is composed of a supply system, an extrusion system, a heating system, a transmission system and a control system, the screw for the transfer of low viscosity resin The speed can be adjusted to low speed.

Basalt long fiber according to the present invention means that the length of the fiber is 2.5 mm or more, for example, can be cut to 2.5 mm, 5 mm, 10 mm, 15 mm or more in length from basalt continuous fibers, limited to this It is not.

When the length of the long fiber is as short as 2.5 mm, the agglomeration of the fibers is small without additional components such as compatibilizers, and the fibers can be evenly dispersed throughout the composite material. However, when the length of the long fiber is long, such as 5 mm or 10 mm, a component such as a compatibilizer may be added to improve the fiber agglomeration phenomenon, powdery state, and the like.

As the length of the basalt long fibers increases, the tensile strength decreases, and the bending strength and impact strength increase.

First, as the length of the fiber increases, the viscosity of the composite material in a molten state increases in the injection molding step, so that the fluidity of the fiber decreases, and thus the dispersion degree decreases. The uneven dispersion of fibers does not sufficiently orient the fibers in the tensile direction, so that the fibers do not properly support the area during tension. However, because the bending direction of the bending test is directed downward, the fiber does not significantly affect the bending strength even if the orientation of the fibers in the polymer is not arranged in a uniaxial direction due to agglomeration of fibers, so the longer the fiber, the better the bending. Strength. In addition, it can be seen that the longer the length of the fiber, the better it withstands the load, thus showing better impact strength.

As the compatibilizer, a compatibilizer based on rubber or wax may be used, and such a compatibilizer may be used together with the thermoplastic polymer base material.

The rubber-based compatibilizers include ethylene propylene rubber, ethylene propylene diene monomer, methyl methacrylate butadiene styrene block copolymer, styrene butadiene styrene block copolymer, styrene ethylene butylene styrene block copolymer, maleic anhydride styrene ethylene butylene styrene block Copolymers, acrylic acid graft polyethylene, maleic anhydride graft polyethylene, maleic anhydride graft ethylene butyl acrylate, styrene and butadiene copolymers, and the like can be used, but are not limited thereto.

It is preferable to use a fatty acid-based compatibilizer for the wax-based compatibilizer, and Montan wax fatty acid ethylene ester, low-density polyethylene wax, high-density polyethylene wax, polyester resin-based wax, and styrene-acrylic resin-based wax may be used. However, it is not limited thereto.

The tensile strength of the composite material according to the present invention is 129 to 158 MPa, the bending strength is 139 to 170 MPa, and the impact strength is 20.0 to 61.5 kg cm/cm.

Method for manufacturing a basalt long fiber-reinforced thermoplastic composite material according to an embodiment of the present invention,

(i) adding a thermoplastic polymer base material and a compatibilizer to an extruder hopper, and applying heat to prepare a molten polymer base material;

(ii) the molten thermoplastic polymer base material is discharged from an extruder (Twin-screw extruder) and introduced into an impregnation bath;

(iii) inserting basalt continuous fibers into the impregnation tank to impregnate the molten polymer base material;

(iv) winding the basalt continuous fiber from the outside of the impregnation tank to produce a prepreg of basalt continuous fiber impregnated with a polymer base material;

(v) cutting the basalt continuous fiber prepreg to produce basalt long fiber pellets; And

(vi) preparing a basalt long fiber composite material by injection molding the cut basalt long fiber pellets.

The basalt long fiber reinforced thermoplastic composite material according to the present invention is manufactured using a melt impregnation process.

In one embodiment of the present invention, in the step (i), it may be mixed by further adding a rubber or wax-based compatibilizer together with the thermoplastic polymer base material to the hopper. At this time, 190 to 250 ℃ heat is applied to prepare a polymer in a molten state in which the compatibilizer is mixed.

In one embodiment of the present invention, the polymer in the molten state prepared through step (i) is discharged from an extruder and stored in an impregnation tank, and the basalt continuous fibers are inserted into the impregnation tank to be impregnated. At this time, the basalt continuous fibers are wound with a certain tension from one side outside the impregnation tank so that the molten polymer is impregnated and coated on the continuous fibers with a certain thickness, and the continuous fibers come out through the outlet die of the discharge port of the impregnation tank. It can be naturally cooled at room temperature to produce a prepreg having a uniform density.

The prepreg is cut to a length of 2.5 mm or more, preferably 2.5 mm to 10 mm, of basalt fiber, and is manufactured in a pellet form, and such pellets are injection molded and made of a composite material. At this time, during injection molding, the melting temperature is 220 to 250°C, the mold temperature is 50 to 70°C, the injection pressure is 500 to 550 bar for 5 to 10 seconds, and the filling pressure is performed under 130 to 150 bar conditions for 3 to 5 seconds. .

Hereinafter, the present invention will be described in more detail by examples. It is apparent to those skilled in the art that these examples are only for describing the present invention, and the scope of the present invention is not limited to these examples.

Examples 1 to 9: Preparation of basalt long fiber-reinforced composite material

The nylon 6 used as the polymer base material used was a resin having high fluidity (KOPLA, KNP1000), and a continuous fiber having a 2400 Tex thickness was used as basalt fiber for reinforcing the nylon 6 resin. In addition, a fatty acid-based Montan wax (Montan wax fatty acid ethylene ester) was used as a wax-based compatibilizer, and a copolymer of styrene and butadiene (KUMHO, KTR602) was used as a rubber-based compatibilizer.

Basalt continuous fiber prepregs of Examples 1 to 9 were prepared according to the composition of Table 1 below. Then, the length of the basalt fiber was cut to be 2.5 mm, 5 mm, and 10 mm to prepare a basalt long fiber pellet.

division Basalt fiber
(wt%) Nylon 6
(wt%) Wax
Compatibilizer (wt%) Rubber series
Compatibilizer (wt%) Basalt fiber
Length (mm) Example 1 40 60 0 0 2.5 Example 2 5 Example 3 10 Example 4 57 3 0 2.5 Example 5 5 Example 6 10 Example 7 57 0 3 2.5 Example 8 5 Example 9 10

Examples 1-1 to 9-1: Preparation of basalt continuous fiber prepreg

1 is a block diagram of a melt impregnation process for preparing a composite material prepreg by impregnating the nylon 6 resin with basalt fiber.

Referring to FIG. 1, nylon 6 resin pellets were inserted into a hopper part, and the molten resin was transferred to a discharge direction using a twin-screw extruder. Upon melting the resin, a basalt continuous fiber prepreg was prepared with or without adding a wax-based or fatty-acid compatibilizer to the hopper.

For effective melting and mixing of the resin, the temperature of the extruder was set at a temperature of 190 to 250°C, and the screw speed was fixed at 500 RPM. The molten resin was stored in an impregnation bath through discharge, wherein the basalt continuous fibers were inserted into the impregnation tank to impregnate the basalt continuous fibers with resin.

An outlet die having a thickness of 0.5t was produced at the discharge port of the impregnating tank to remove excess resin, and a basalt continuous fiber prepreg having a uniform thickness was prepared. At this time, a rotary roller (Traction device) was installed at the end of the discharge port so as to wind the basalt continuous fiber with a certain tension so that the basalt continuous fiber prepreg could be manufactured at a uniform speed. A separate cooling system was not used when winding the prepreg, and a basalt continuous fiber prepreg having a uniform density of fibers and polymers was produced by natural cooling.

Examples 1-2 to 9-2: Preparation of basalt long fiber pellets

The basalt continuous fiber prepregs of Examples 1-1 to 9-1 with uniform thickness were prepared and then cut into various lengths using an automatic cutter, respectively. Specifically, the length of the basalt fiber was cut to be 2.5 mm, 5 mm, and 10 mm to prepare a basalt long fiber pellet (see FIG. 2).

Examples 1-3 to 9-3: Preparation of basaltic long fiber reinforced composite tensile specimen

The cut basalt long fiber pellets were prepared by using an injection molding process to prepare tensile specimens made of basalt long fiber reinforced composite materials. At this time, in consideration of the melting point of nylon 6 resin during injection molding, the melting temperature is 250°C, the mold temperature is 60°C, the injection pressure is adjusted to 550 bar for 5 seconds, and the filling pressure is adjusted to 150 bar for 3 seconds to prepare a tensile specimen. (See FIG. 3).

Experimental Example 1: Structural property measurement

The dispersion state and surface of the basalt long fiber reinforced composite material were confirmed using an optical microscope. Figure 4 shows the surface of the basalt long fiber reinforced composite material according to the fiber length and compatibilizer.

First, as shown in Example 1, when the length of basalt long fibers is the shortest with 2.5 mm, it was found that there is little agglomeration of the fibers regardless of the addition of a wax-based or rubber-based compatibilizer, and the fibers are evenly and well overall. It was confirmed that the dispersion.

On the other hand, as the lengths of basalt long fibers are increased to 5 mm and 10 mm, as in Examples 2 and 3, the aggregation of fibers increases, and as the number of locally arranged fibers increases, the effect of attraction between fibers increases, thereby increasing the overall fiber It was confirmed that the dispersion state was bad.

The reason for the even dispersion of the basalt long fibers is that the composite material is produced through the injection process, and the shorter the fiber length, the lower the viscosity and the lower the viscosity, so that the melted composite material can flow smoothly. . On the contrary, it is understood that the longer the length of basalt long fibers, the higher the viscosity of the molten composite material during the injection process, and the poor dispersion due to the long fiber agglomeration effect.

In addition, as the lengths of basalt long fibers, such as Examples 5, 6, 8, and 9, increased to 5 mm and 10 mm, as a wax-based or rubber-based compatibilizing agent was added, the fiber agglomeration compared to Examples 4 and 7 was observed. It was confirmed that it was less and the fibers were evenly distributed as a whole. This is because the wax-based or rubber-based compatibilizers facilitate the dispersion of long length basalt long fibers.

Experimental Example 2: Tensile strength and bending strength measurement

The mechanical properties of the tensile specimens were measured using a universal material tester (UTM) (3365, Instron). Tensile test was performed according to ASTM D638 standard. The bending test was measured according to the ASTM D790 standard using a universal material testing machine (UTM) (5882, Instron).

5 is a graph showing tensile strength and bending strength of basalt long fiber reinforced composite material according to basalt long fiber length and compatibilizer.

Referring to FIG. 5, when looking at the tensile strength (a) according to the fiber length, as the overall length of the fiber increases, it can be seen that the tensile strength decreases regardless of whether a compatibilizer is added.

In the case of the composite material of Example 1, the tensile strength was measured to be 158.3 MPa, and it was confirmed that the composite materials of Examples 4 and 7 had low tensile strength values of 136.1 MPa and 129.3 MPa, respectively. This is due to the fact that as the length of the basalt long fibers increases, the viscosity of the composite material in a molten state increases in the injection process step, so that the basalt fibers in nylon 6 have low fluidity, and accordingly, the fibers are not effectively dispersed in nylon 6.

Unlike the tensile strength, as the length of basalt long fibers increased, it was found that the bending strength (b) of the composite material increased as a whole. In the case of the composite material of Example 1, the bending strength was measured to be 139.2 MPa, and it was confirmed that the composite materials of Examples 4 and 7 had high bending strength values of 152.8 MPa and 169.7 MPa, respectively.

When analyzing the tensile strength and bending strength according to the addition of the compatibilizer, it was confirmed that the overall mechanical properties of the composite material to which the compatibilizer was added were slightly deteriorated. As a result of this, it can be seen that the addition of a compatibilizer improves the workability of the composite material, but does not have a positive effect on tensile strength and bending strength.

Experimental Example 3: Impact strength measurement

6 is a graph showing the Izod impact strength of basalt long fiber reinforced composites according to fiber length and compatibilizer.

First, by analyzing the impact strength of the composite material according to the length of the basalt long fiber, it was confirmed that the impact strength increased as the fiber length increased, similar to the bending strength. In the case of the composite material of Example 1, the impact strength was 20.0 kg cm/cm, and when comparing the composite materials of Examples 4 and 7, it was confirmed that the impact strength values were as high as 50.0 kg cm/cm and 61.5 kg cm/cm, respectively. Could. This is because, unlike the tensile strength, the load is applied by striking with a hammer in the direction of the notch of the specimen, so it is interpreted that it does not significantly affect the impact strength even if the orientation of the fibers in nylon 6 is not uniaxially arranged due to the bundle of fibers. .

In the case of basalt long fiber composite material with a compatibilizer added, it can be seen that when a rubber-based compatibilizer is added, it is more resistant to external impact and has a relatively high impact strength. In the case of the wax-based compatibilizer, it was found that it had a positive effect on the dispersibility of the basalt long fibers, but not a significant effect on the impact strength.

Since the specific parts of the present invention have been described in detail above, it is obvious that for those skilled in the art to which the present invention pertains, this specific technology is only a preferred embodiment, and the scope of the present invention is not limited thereto. Do. Those of ordinary skill in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above.

Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (11)

Basalt long fibers; And
It includes; a thermoplastic polymer base material for coating the basalt long fibers;
The thermoplastic polymer base material further comprises a rubber or wax-based compatibilizer, basalt long fiber reinforced thermoplastic composite material with improved interfacial properties. According to claim 1, The thermoplastic polymer is nylon 6 resin, basalt long fiber reinforced thermoplastic composite material with improved interfacial properties. The rubber-based compatibilizer is ethylene propylene rubber, ethylene propylene diene monomer, methyl methacrylate butadiene styrene block copolymer, styrene butadiene styrene block copolymer, styrene ethylene butylene styrene block copolymer, maleic anhydride Styrene ethylene butyrene styrene block copolymer, acrylic graft polyethylene, maleic anhydride graft polyethylene, maleic anhydride graft ethylene butyl acrylate, and one selected from the group consisting of styrene and butadiene copolymers. Long fiber reinforced thermoplastic composite material. The method of claim 1, wherein the wax-based compatibilizer is selected from the group consisting of montan wax (Montan wax fatty acid ethylene ester), low density polyethylene wax, high density polyethylene wax, polyester resin wax and styrene-acrylic resin wax. Basalt long fiber reinforced thermoplastic composite material with improved interfacial properties. According to claim 1, Tensile strength is 129 to 158 MPa, bending strength is 139 to 170 MPa, the impact strength is 20.0 to 61.5 kg cm / cm, basalt long fiber reinforced thermoplastic composite material with improved interfacial properties. (i) adding a thermoplastic polymer base material and a compatibilizer to an extruder hopper, and applying heat to prepare a molten polymer base material;
(ii) discharging the molten thermoplastic polymer base material from an extruder and introducing it into an impregnation tank;
(iii) inserting basalt continuous fibers into the impregnation tank to impregnate the molten polymer base material;
(iv) winding the basalt continuous fiber from the outside of the impregnation tank to produce a basaltic continuous fiber prepreg impregnated with a polymer base material;
(v) cutting the basalt continuous fiber prepreg to produce basalt long fiber pellets; And
(vi) preparing a basalt long fiber composite material by injection molding the cut basalt long fiber pellets;
Method of manufacturing basalt long fiber reinforced thermoplastic composite material with improved interfacial properties. The method of claim 6, wherein the thermoplastic polymer is a nylon 6 resin, and the basal fiber long fiber reinforced thermoplastic composite material with improved interfacial properties. 7. The method of claim 6, wherein the compatibilizer in step (i) is a rubber or wax-based compatibilizer, and the basalt long fiber reinforced thermoplastic composite material with improved interfacial properties. The method for manufacturing a basalt long fiber-reinforced thermoplastic composite material with improved interfacial properties according to claim 6, wherein the step (i) is melted by applying heat of 190 to 250°C. The method for manufacturing a basalt long fiber-reinforced thermoplastic composite material according to claim 6, wherein the prepreg is naturally cooled while winding the prepreg in step (iv). According to claim 6, In the step (vi), in the injection molding, the melting temperature is 220 to 250°C, the mold temperature is 50 to 70°C, the injection pressure is 500 to 550 bar for 5 to 10 seconds, and the filling pressure is 3 to 5 Method of manufacturing basalt long fiber-reinforced thermoplastic composite material with improved interfacial properties, performed under conditions of 130 to 150 bar for seconds.

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