KR102266290B1 - Method for preparing surface modified glass fiber and glass fiber reinforced polymeric composite material comprising the glass fiber - Google Patents

Abstract

The present invention relates to a method for producing a surface-modified glass fiber and a glass fiber-reinforced polymer composite comprising the surface-modified glass fiber, and more particularly, to a) the surface of the glass fiber through the reaction of a silane coupling agent with the glass fiber. A method for producing a surface-modified glass fiber comprising the steps of primary reforming and b) chemically bonding the primary modified glass fiber with the maleic anhydride-graft-olefin resin to secondary-modify the glass fiber, and thus The present invention relates to a glass fiber-reinforced polymer composite comprising a surface-modified glass fiber having improved compatibility and interfacial adhesion and a polyolefin resin.

Description

METHOD FOR PREPARING SURFACE MODIFIED GLASS FIBER AND GLASS FIBER REINFORCED POLYMERIC COMPOSITE MATERIAL COMPRISING THE GLASS FIBER

The present invention relates to a method for producing a surface-modified glass fiber and a glass fiber-reinforced polymer composite comprising the surface-modified glass fiber, and more particularly, to an olefin in which the surface of the glass fiber is modified with an olefin resin grafted with maleic anhydride. The present invention relates to a surface-modified glass fiber having improved interfacial adhesion when forming a composite material with a resin, and a glass fiber-reinforced polymer composite having excellent mechanical properties including the same.

In general, a composite material refers to a material having effective performance by combining two or more types of materials having different chemical components or shapes to have an interface that is macroscopically distinguished from each other as a reinforcing material and a matrix. Since such a composite material can be modified into a material having various properties according to the characteristics of each component to be combined, it is being applied to various industries such as aerospace, space, automobile, and industrial machinery fields. Among various composite materials, fiber-reinforced composite materials are manufactured using fiber-type reinforcing materials such as glass fiber, carbon fiber, aramid fiber, and silicon carbide fiber as a reinforcing material. It is one of the most popular composite materials. In particular, among fibrous reinforcing materials, glass fiber is widely used in the manufacture of composite materials because of its low cost, high tensile strength, impact resistance, dimensional stability, abrasion resistance, high chemical resistance and excellent insulation properties. Because.

Polypropylene, a thermoplastic polymer, is used as a matrix resin in the field of glass fiber reinforced polymer composite materials due to its low cost, easy processability and excellent corrosion resistance. This glass fiber reinforced polypropylene composite material is applied to various fields including the automobile industry requiring high strength. is becoming In general, glass fiber reinforced polypropylene composites are manufactured through a processing process such as extrusion by mixing a polypropylene resin used as a matrix and a glass fiber reinforcing material and then melting it. In this process, glass fibers penetrate between the microstructures of the polypropylene resin and are uniformly dispersed as a reinforcing material in the matrix. At this time, due to the weak interfacial adhesion between the glass fiber reinforcing material and the polypropylene resin, the glass fibers are interposed between the microstructures of the matrix polypropylene resin. The increase in the physical properties of the composite material was insufficient because the penetration of the fiber reinforcement was not easy.

Many research groups are trying to stabilize the interfacial properties between the matrix resin and the fiber for reinforcing material, and the method of using a compatibilizer during processing is the most common. Recently, in order to further improve the performance of glass fiber composites, research has been conducted to further improve the interfacial adhesion by modifying the surface of glass fibers, and heat treatment, acid or alkaline etching methods, and glass fiber modification using a coupling agent are in progress. is becoming However, there is a report that surface modification by hydrolysis of -Si-O-Si- tends to decrease the interfacial strength.

In addition, as a method of improving the adhesion between the polypropylene resin and glass fibers, a method of adding glass fibers to polypropylene modified with carboxylic acid, carboxylic acid anhydride or unsaturated carboxylic acid, or determining an unsaturated carboxylic acid or anhydride thereof A method of mixing glass fiber with a graft polypropylene resin obtained by performing a graft reaction with a polypropylene resin has been proposed, but the type of olefin resin that can be used is limited and the mechanical properties required in the industrial field are not met. There was a limit I couldn't.

US Registered Patent Publication No. 4,003,874 Korean Patent Publication No. 1993-0000588

The technical problem to be achieved by the present invention is that, when glass fibers are mixed with an olefin resin, glass fibers having excellent interfacial adhesion and miscibility with a modified surface so as to exclude self-aggregation of glass fibers and to be effectively dispersed and uniformly mixed, and To provide a manufacturing method thereof.

Another technical object of the present invention is to provide a glass fiber-reinforced polymer composite having excellent mechanical properties including surface-modified glass fibers having improved miscibility and dispersibility with the olefin resin.

In order to solve the above problems, the present invention comprises the steps of: a) first modifying the surface of the glass fiber through the reaction of the silane coupling agent and the glass fiber; and b) chemically bonding the first-modified glass fiber with the maleic anhydride-graft-olefin resin to secondary-modify the glass fiber, and the glass fiber thus prepared. to provide.

In addition, the present invention provides a glass fiber reinforced polymer composite comprising the glass fiber and the polyolefin resin having the surface modified as described above.

When the surface-modified glass fiber according to the present invention is mixed in an olefin resin to form a composite material, it has excellent compatibility with the olefin resin constituting the matrix and excellent dispersibility. That is, through surface modification of glass fibers, dispersibility can be secured by excluding aggregation between glass fibers, and miscibility (affinity) with the olefin resin is increased, thereby improving interfacial adhesion.

When a composite material is formed by mixing the glass fiber modified by the present invention with an olefin resin, an additional compatibilizer is not required, so that mechanical properties can be improved only with a small amount of compatibilizer, and the distribution of the compatibilizer is limited to the glass fiber region. Polarization of the olefin resin constituting the matrix by the compatibilizer can be minimized. This is because, in general, an olefin resin having an increased degree of polarization may weaken chemical resistance and weather resistance. In addition, when the glass fiber modified according to the present invention is added to an olefin resin to prepare a composite material, tensile strength and tensile modulus are improved, thereby providing an olefin resin composite having excellent mechanical properties.

1 is a schematic diagram showing the modification process of glass fiber according to the present invention, (A) shows the process of primary reforming of glass fiber using an APS silane coupling agent, (B) is the primary modified glass fiber and It shows the process of preparing the secondary modified glass fiber by reacting MAPP.
Figure 2 is a SEM photograph and each EDX energy spectrum of the glass fiber (A) first modified using the APS silane coupling agent according to an embodiment of the present invention and the glass fiber (B) secondarily modified using MAPP (a, b).
3 is a SEM photograph showing the morphology of a polypropylene composite using glass fibers modified with MAPP and glass fibers before modification.
4 and 5 show the tensile strength of the glass fiber reinforced polypropylene composite according to the glass fiber content in the polypropylene composite reinforced with pre-modified glass fiber (bare GF) and modified glass fiber (MAPP-a-GF). ) and a graph showing the tensile modulus.

Hereinafter, the present invention will be described in more detail with reference to examples and drawings.

In the present invention, the interfacial adhesion between the glass fiber reinforcement and the polyolefin resin matrix is improved by inducing surface modification of the glass fiber through the process of chemically bonding the polyolefin resin grafted with maleic anhydride to the surface of the glass fiber having silanol groups. did it To this end, in the present invention, a step of primarily preparing a glass fiber having an amine group (primary or secondary amine) on the surface of the glass fiber and chemically bonded to a hydrolyzable silane group is performed. Then, the primary modified glass fiber is chemically bonded to the maleic anhydride-graft-olefin resin through an amide reaction, which is a nucleophilic substitution reaction, to prepare a glass fiber. In addition, there is provided a glass fiber reinforced polymer composite including the surface-modified glass fiber and the polyolefin resin.

The surface modification step according to the present invention will be described in detail as follows.

The method for producing a surface-modified glass fiber according to the present invention comprises the steps of a) first modifying the surface of the glass fiber through the reaction of a silane coupling agent with the glass fiber, and b) the first modified glass fiber and maleic anhydride-graf It is characterized in that it comprises a step of chemically bonding the di-olefin resin to secondary-modify the glass fiber.

In this case, the glass fiber usable in the present invention preferably has a diameter of 1 to 50 μm and a length of 1 to 10 mm. When short fibers are used to manufacture olefin-based glass fiber reinforced composites, both the side parts using the extruder hopper part or the side feeder can be used to input glass fibers during processing, which is advantageous for manufacturing various grade products.

In addition, the silane coupling agent used in the primary reforming of the present invention is preferably a silane compound containing an amino group, for example, 3-aminopropyltriethoxysilane, aminopropyltrimethoxysilane, amino-methoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N -(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropyltridimethoxysilane, γ-aminopropyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyldiethoxysilane One or more of them may be selected and used, but the present invention is not particularly limited thereto.

In addition, the maleic anhydride-graft-olefin resin used for secondary modification of glass fibers in the present invention is, for example, maleic anhydride-graft-polypropylene, maleic anhydride-graft-polyethylene, polystyrene-(maleic anhydride- graft-polyethylene)-polybutene triblock copolymer, polystyrene-(maleic anhydride-graft-polybutene)-polyethylene triblock copolymer, and maleic anhydride-graft-polybutadiene, and the like, but primary modification Any olefin resin capable of chemical bonding with the glass fiber may be used, and the present invention is not particularly limited thereto.

In the present invention, first, the surface of the glass fiber is first modified through a silylation reaction between the silane coupling agent containing an amino group and the glass fiber. In this case, the glass fiber is preferably subjected to a pretreatment process of removing organic matter using an organic solvent. Glass fibers provided as commercial products generally undergo a post-treatment process of sizing with organic materials after spinning in order to improve fiber friction properties or interfacial adhesion. Therefore, pure glass fiber can be obtained by removing organic matter using a boiling xylene solvent.

In the present invention, the first surface modification step of the glass fiber is performed by impregnating the glass fiber in a solution in which the silane coupling agent is hydrolyzed and then drying. In addition, in the second reforming step, the second reforming step is by dispersing the first modified glass fiber and the maleic anhydride-grafted olefin resin in a high-temperature organic solvent of 80° C. to 180° C. for reaction, followed by filtration, washing, and drying. is carried out As a solvent of maleic anhydride-grafted olefin resin, the boiling point of industrial xylene (ortho-xylene, meta-xylene, para-xylene mixture) is about 130 ℃, and it starts to melt from around 80 ℃. Trichlorobenzine solvent is also widely used, and the olefin resin grafted with maleic anhydride begins to melt from around 130°C.

Specifically, examples of the organic solvent that can be used in the present invention include ortho-xylene, meta-xylene, para-xylene, or a mixture thereof xylene, dichlorobenzene, trichlorobenzene, tetralin, decalin ) and the like, but is not particularly limited thereto, and any organic solvent suitable for chemically bonding the grafted olefin resin with the glass fiber may be used.

As described above, the glass fiber surface-modified through the first and second reforming steps according to the present invention has excellent dispersibility and miscibility with respect to the olefin resin, and when added to the olefin resin to form a composite material, the mechanical properties are improved has the advantage of being Accordingly, the present invention can provide a glass fiber-reinforced olefin resin composite including glass fibers and polyolefin resins whose surface is modified according to the first and second reforming steps, wherein the polyolefin resins that can be used are homo-polypropylene, random -Polypropylene, terpolypropylene, block-polypropylene, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, etc. may be mentioned, but are not particularly limited thereto. At this time, the content of glass fibers in the glass fiber reinforced olefin resin composite is preferably 5 to 50 wt%, and if more glass fibers are contained in excess of this, it is difficult to input more than a certain amount of glass fibers due to excessive torque during extrusion. .

Hereinafter, the present invention will be described in more detail through specific examples. However, the following examples are provided by way of illustration to help the understanding of the present invention, and the scope of the present invention should not be construed as being limited thereto.

The glass fiber used in this experiment was provided by Owens Corning, a glass fiber for a thermoplastic composite material (CS04-144A; length 4 mm, filament 14 μm). For polypropylene, SK General Chemicals (YUPLENE H730F; MFI=3.5 g/10 min) was used. For MAPP, PH-200, a product of Lotte Chemical (MFI>100 g/10 min, density=0.36 g/cm ³ , MA content>1 wt-%) was provided and used. As a silane coupling agent for surface modification, 3-aminopropyltriethoxy silane from Gelest was purchased and used without purification. Other common solvents were used directly without purification.

Example 1: Glass fiber primary surface modification (APS-GF)

Glass fibers provided as commercial products generally undergo a post-treatment process of sizing with organic materials after spinning in order to improve fiber friction properties or interfacial adhesion. Therefore, in order to obtain pure glass fibers, glass fibers from which organic matter has been removed in a boiling xylene solvent were used. For the nucleophilic substitution reaction with maleic anhydride in the modified polyolefin prepared by grafting polypropylene resin and maleic anhydride, primary surface modification with a silane coupling agent was performed on the surface of the glass fiber. A silane coupling agent (2 wt-%) was diluted in a cosolvent (95:5 w/w) of methanol and distilled water, and the pH was fixed at about 4.0 to 5.0 using acetic acid, followed by hydrolysis for 30 minutes. After impregnating the glass fiber in the hydrolyzed solution for about 30 minutes, it was ^{dried in a convection oven at 80 o} C for 30 minutes and then dried at 30 ^o C for 24 hours. (Fig. 1A)

Example 2: Glass fiber secondary surface modification (MAPP-a-GF)

To chemically bond maleic anhydride-graft-polypropylene (MAPP: Polypropylene- graft- maleic anhydride) to the glass fiber surface, the first modified glass fiber and MAPP are dispersed in boiling xylene solvent for 2 hours stirred for a while. After stirring and filtering in a hot state, they were washed several times with a hot xylene solvent, and then dried in a vacuum oven at ^{60 o C for 48 hours.} (Fig. 1B)

Example 3: Glass Fiber Reinforced Polypropylene Composite Preparation

Melt mixing of the glass fiber reinforced polymer composite was ^{performed at 180 o C at 40 rpm for 10 minutes using a HAAKE Rheomix 600p melt mixer, and specimen molding was performed at 180 o} C, 5 ton pressure using a Carver hydraulic hot press (Model 3912). After being prepared in , it was cut and used to measure the mechanical strength. Glass fiber reinforced polypropylene (PP) composites were prepared by fixing the content of glass fibers in the composite to 10 and 20 wt-%, respectively.

Experimental Example: Confirmation of surface modification of glass fibers and characterization of composites

For thermal analysis of the glass fiber reinforced composite, TA Instruments' DSC Q2000 was used, and the melting point was measured by raising and lowering the temperature at a rate ^{of 20 °C/min in a nitrogen atmosphere.} In order to measure the mechanical properties, LR30K-Plus universal testing machine (AMETEK Ltd.) was used. After the composite sample was cut into 100 (L) × 5 (W) × 1 (T) mm, the mechanical properties were measured at a test speed of 5 mm/min. Five specimens were prepared and repeatedly measured, and then the average value was used. For the morphological study of the composite, the composite specimen was fractured in a liquid nitrogen atmosphere, the fracture surface was coated with gold, and then a scanning electron microscope (SEM, Hitachi S-4700) equipped with an X-ray spectrometer (Noran Instruments: EDX) was used. was used.

In Example 1, as a pretreatment reaction for surface modification of glass fibers, many silanol groups distributed on the surface of glass fibers and a silane coupling agent (APS; 3-aminopropyl triethoxy silane) were reacted with 1 through a silyation reaction. Tea glass fiber surface modification was performed. The silylation reaction is a reaction well known as a hydrolysis-condensation reaction, and the hydrolyzable alkoxy group becomes a silanol in the presence of water molecules, and the hydrolyzed silanol is again subjected to a condensation reaction with the silanol group on the surface of the glass fiber. A stable '-O-Si-O-' covalent bond is formed on the surface of the glass fiber. Since carbon and nitrogen elements as well as silicon elements derived from the silane coupling agent should be distributed on the surface of the modified glass fibers, the presence or absence of carbon and nitrogen elements on the surface of the glass fibers was checked using SEM/EDX. In Figure 2, the SEM photograph of the glass fiber (A) first modified using the APS silane coupling agent and the glass fiber (B) secondarily modified using MAPP and the respective EDX energy spectra (a, b) are shown. .

The following [Table 1] shows the elements and the content of each element distributed on the surface of the primary and secondary modified glass fibers. On the energy spectrum of the surface of the glass fiber modified with the APS silane coupling agent, it was confirmed that the intrinsic energy peak of the silicon element at 1.75 eV as well as the energy peak of the carbon and nitrogen elements by the silane coupling agent were found. This indirectly means that the silane coupling agent has been successfully modified on the glass fiber surface. In the surface energy spectrum of the secondary-modified glass fiber, the energy peak of carbon element due to MAPP was found to be large, confirming that MAPP is chemically bonded to the surface of the glass fiber. From these results, it was confirmed that the primary and secondary glass fiber surface modification reactions were successfully performed.

The following [Table 2] shows the melting temperature and temperature-falling crystallization temperature of polypropylene according to the content of glass fibers in the glass fiber reinforced polypropylene (PP) composite. The melting temperature of the glass fiber reinforced polypropylene composite did not show a certain trend depending on the presence or absence of glass fiber and whether or not it was modified. However, the crystallization temperature on cooling shows a higher crystallization temperature on cooling for the composite material containing glass fibers than for pure polypropylene. In addition, the composite material containing glass fibers modified with MAPP showed a higher crystallization temperature on cooling than the composite material containing glass fibers that were not finely modified. These results indicate that the glass fibers dispersed in the polypropylene matrix using the glass fiber reinforcement increase the crystallization temperature on cooling due to the role of the nucleating agent of the glass fibers during recrystallization of polypropylene.

In general, for polymer composite materials containing micro-sized reinforcing materials, the fracture surface morphology of the composite material varies depending on the adhesive force between the interfaces between the two materials. In order to confirm the dispersion state of the glass fibers in the polypropylene matrix, the results are shown in FIG. 3 through SEM morphology analysis. As shown in FIG. 3 , it was possible to confirm the difference between the degree of dispersion of the glass fibers and the degree of interfacial adhesion in the polypropylene composite using the glass fibers modified with MAPP and the glass fibers before modification. It can be seen that in the composite using the glass fiber modified with MAPP, the gap between the glass fiber interfaces was almost disappeared and the adhesion was improved. However, it was confirmed that the gap between the polypropylene mattress and the glass fiber was clearly visible when the glass fiber before modification was used together. These results show that the glass fiber modified with MAPP is much more effective than the pre-modified glass fiber in minimizing the gap between the glass fiber and the matrix interface by greatly improving the compatibility with the polypropylene matrix.

4 and 5 show the tensile strength of the glass fiber reinforced PP composite according to the glass fiber content in the polypropylene composite reinforced with pre-modified glass fiber (bare GF) and modified glass fiber (MAPP-a-GF). and tensile modulus are shown. As the content of glass fibers in the composite increased, the tensile strength increased from about 30 MPa to about 35 MPa, and the tensile modulus increased from 1.25 GPa to 1.5 GPa. When the glass fiber modified with MAPP is used, as shown in FIGS. 4 and 5 , the tensile strength and tensile modulus are increased compared to the case of using the glass fiber before modification. This result is considered to be the result of increasing the interfacial adhesive force between the glass fiber modified with MAPP and the polypropylene matrix more effectively than the glass fiber before modification.

In summary, in the present invention, MAPP-a-GF was prepared through a two-step modification reaction on the surface of the glass fiber using MAPP to improve the interfacial bonding force between the glass fiber and the polypropylene matrix resin. The pre-modified glass fiber reinforced PP composite was compared together as a control. The thermal properties of the prepared glass fiber reinforced polypropylene composite increased the crystallization temperature upon cooling, but the change in the melting temperature was insignificant. The tensile strength and tensile modulus of the PP composite by MAPP-a-GF were increased compared to that of the pre-modified glass fiber. Based on these results, MAPP-a-GF acts as a reinforcing material with excellent interfacial bonding strength in the PP composite, and the mechanical properties of the composite are improved, so that it can be usefully used in the field of polymer composites requiring high functionality.

Claims (13)

A method for producing a glass fiber reinforced polymer composite comprising a surface-modified glass fiber and a polypropylene resin, the method comprising:
a) reacting a silane compound containing an amino group with a glass fiber to first modify the surface of the glass fiber;
b) chemically bonding the first modified glass fiber and maleic anhydride-graft-polypropylene resin to secondarily modify the glass fiber; and
c) melting and mixing the second modified glass fiber and polypropylene resin,
The method for producing a glass fiber reinforced polymer composite, characterized in that the content of the surface-modified glass fiber is 10 to 20% by weight. According to claim 1,
The glass fibers have a diameter of 1 to 50 μm and a length of 1 to 10 mm. delete delete delete According to claim 1,
The glass fiber used for the primary reforming is a glass fiber reinforced polymer composite material, characterized in that it is a glass fiber that has undergone a pretreatment process of removing organic matter using an organic solvent. According to claim 1,
The first reforming step is a method of manufacturing a glass fiber reinforced polymer composite, characterized in that the impregnated glass fiber in a solution in which a silane compound containing an amino group is hydrolyzed and then dried. According to claim 1,
The secondary reforming step is characterized in that the primary modified glass fiber and maleic anhydride-graft-polypropylene resin are dispersed and reacted in a high temperature organic solvent of 80 to 180° C., followed by filtration, washing, and drying. A method for manufacturing a fiber-reinforced polymer composite. 9. The method of claim 8,
The organic solvent is ortho-xylene, meta-xylene, para-xylene or a mixture thereof, characterized in that at least one selected from the group consisting of xylene, dichlorobenzene, trichlorobenzene, tetralin, decalin A method for manufacturing a glass fiber reinforced polymer composite. delete delete delete delete

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