Long glass fiber reinforced thermoplastic resin composition and molded article containing same

Abstract

To provide a thermoplastic resin composition capable of securing high physical property and dimensional stability necessary for a frame of a panoramic sun roof, and useful in weight saving and reduction of production cost.SOLUTION: A thermoplastic resin composition contains 30 wt.% to 70 wt.% of a polyamide; 20 wt.% to 60 wt.% of an enhancer containing a glass fiber and having a planar shape; and 1 wt.% to 5 wt.% of a silane coupling agent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a long glass fiber reinforced thermoplastic resin composition and a molded article containing the same. [Background technology]

[0002] Recently, the automobile industry has been shifting towards lightweight, high-end, and environmentally friendly vehicles. Lightweighting is an especially important factor that has a significant impact on the fuel economy and driving performance of automobiles.

[0003] Panoramic sunroofs were developed to ventilate the interior of a vehicle and give it an open, spacious feel, and are fitted with glass and an electric motor in a frame.

[0004] Panoramic sunroof frames are primarily made of steel, which has excellent physical properties, to withstand the weight of surrounding components and external impacts. Recently, there have been attempts to use engineering plastics with steel inserted to reduce weight. One example is the use of a material made of polybutylene terephthalate (PBT) reinforced with glass fiber, which has achieved a weight reduction of more than 30% compared to steel.

[0005] However, polybutylene terephthalate (PBT) / glass fiber material has the drawback of being deformed after injection, making it difficult to apply in practice.

[0006] There have also been attempts to solve the problems of the prior art by using carbon fibers, but the high cost of carbon fibers has made it difficult to expand the application of this technology.

[0007] Therefore, it is necessary to develop a material that has good dimensional stability and high rigidity so that deformation after injection does not become a problem. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Registration No. 0130491 [Patent Document 2] Japanese Patent Publication No. 2012-509381 [Patent Document 3] Japanese Patent Publication No. 2011-529986 Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a thermoplastic resin composition that can ensure the high physical properties and dimensional stability required for a panoramic sunroof frame, and that is useful for reducing the weight and production cost.

[0010] The objects of the present invention are not limited to the above-mentioned objects, but will become more apparent from the following description and be realized by the means and combinations set forth in the claims. [Means for solving the problem]

[0011] A thermoplastic resin composition according to one embodiment of the present invention comprises 30% to 70% by weight of polyamide; 20% to 60% by weight of a reinforcing agent containing glass fiber and having a flat plate shape; and 1% to 5% by weight of a silane coupling agent.

[0012] The polyamide may include an aliphatic polyamide.

[0013] The aliphatic polyamide may include at least one selected from the group consisting of polyamide 6, polyamide 46, polyamide 66, polyamide 610, polyamide 612, polyamide 6 / 12, polyamide 1010, polyamide 11, polyamide 1012, polyamide 12, polyamide 1212, and combinations thereof.

[0014] The polyamide may have a number average molecular weight of 20,000 to 70,000.

[0015] The reinforcing agent may have an aspect ratio of 2 to 5, as represented by the following formula 1. [Formula 1] Average long side length of cross section / Average short side length of cross section

[0016] The reinforcing agent may have an average short side length in cross section of 3 μm to 15 μm.

[0017] The reinforcing agent may have a length of 5 mm to 15 mm.

[0018] The reinforcing agent may have a sizing agent attached to its surface.

[0019] The sizing agent may include at least one selected from the group consisting of urethane resin, acrylic resin, styrene resin, epoxy resin, and combinations thereof.

[0020] The thermoplastic resin composition may have a sizing agent content of 0.1 to 3% by weight based on the total weight of the thermoplastic resin composition.

[0021] The silane coupling agent may contain an isocyanate functional group.

[0022] The isocyanate functional groups of the silane coupling agent may hydrogen bond with the polyamide; or may form covalent bonds with the amine groups of the polyamide.

[0023] The silane coupling agent may include at least one selected from the group consisting of 3-isocyanate propyl trimethoxysilane, 3-isocyanate propyl triethoxysilane, tris[3-(trimethoxysilyl)propyl]isocyanurate, and combinations thereof. [Effects of the Invention]

[0024] According to the present invention, it is possible to provide a thermoplastic resin composition that can ensure the high physical properties and dimensional stability required for a panoramic sunroof frame, and that is useful for reducing weight and production costs.

[0025] The effects of the present invention are not limited to those described above, and it should be understood that the effects of the present invention include all effects that can be inferred from the following description. [Brief explanation of the drawings]

[0026] [Figure 1] 1 shows the results of a scanning electron microscope (SEM) analysis of a cross section of the reinforcement used in Example 1 of the present invention. [Figure 2] 1 shows the results of a scanning electron microscope analysis of the cross section of the reinforcing agent used in Comparative Example 8. DETAILED DESCRIPTION OF THE INVENTION

[0027] The above and other objects, features, and advantages of the present invention will be readily understood from the following preferred embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure will be thorough and complete, and will fully convey the concept of the present invention to those skilled in the art.

[0028] In describing each drawing, like reference numerals are used to refer to like elements. In the accompanying drawings, the dimensions of structures are exaggerated for clarity of the present invention. Terms such as "first," "second," etc. are used to describe various elements, but the elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first element may be referred to as a "second element," and similarly, a second element may be referred to as a "first element," without departing from the scope of the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0029] As used herein, terms such as "comprise" or "have" are intended to specify the presence of a feature, numeral, step, operation, component, part, or combination thereof described in the specification, but should be understood not to preclude the possibility of the presence or addition of one or more other features, numerals, steps, operations, components, parts, or combinations thereof. Furthermore, when a layer, film, region, plate, or other part is described as being "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part between them. Conversely, when a layer, film, region, plate, or other part is described as being "under" another part, this includes not only the case where it is "directly under" the other part, but also the case where there is another part between them.

[0030] Unless otherwise noted, all numbers, values, and / or expressions expressing quantities of ingredients, reaction conditions, polymer compositions, and formulations used herein should be understood in all instances to be modified by the term "about," as such numbers are inherently approximations that reflect, among other things, the various uncertainties of measurement that arise in obtaining such values. Also, in this description, when ranges of numerical values ​​are disclosed, such ranges are continuous and include every value from the minimum value to, and including, the maximum value of such range, unless otherwise indicated. Furthermore, when such ranges refer to integers, they include every integer from, and including, the minimum value to, and including the maximum value, unless otherwise indicated.

[0031] The thermoplastic resin composition according to the present invention comprises (A) 30% to 70% by weight of a polyamide, (B) 20% to 60% by weight of a reinforcing agent containing glass fiber, and (C) 1% to 5% by weight of a silane coupling agent.

[0032] Each of the components of the present invention will be specifically described below.

[0033] (A) Polyamide The polyamide is a component for improving the mechanical properties, impact resistance, and heat resistance of a molded article produced from the thermoplastic composition, and serves as a kind of base resin.

[0034] The polyamide may be an aliphatic polyamide, and may include at least one selected from the group consisting of polyamide 6, polyamide 46, polyamide 66, polyamide 610, polyamide 612, polyamide 6 / 12, polyamide 1010, polyamide 11, polyamide 1012, polyamide 12, polyamide 1212, and combinations thereof, and may preferably be polyamide 6.

[0035] The polyamide may have a low specific gravity of 1.12 to 1.16, thereby ensuring the lightweight nature of the molded article.

[0036] The polyamide may have a number-average molecular weight of 20,000 to 70,000. The polyamide may be used alone or in combination with two or more polyamides having different number-average molecular weights. When the number-average molecular weight of the polyamide falls within the above range, the moldability of the thermoplastic composition and the mechanical properties, impact resistance, and heat resistance of the molded product can be improved to the desired level. Specifically, when the number-average molecular weight of the polyamide exceeds 70,000, the impregnation of the reinforcing agent (described below) during the pultrusion impregnation process may be poor, resulting in reduced mechanical properties, and the product may not be molded due to insufficient fluidity during injection molding.

[0037] The content of the polyamide may be 30% by weight to 70% by weight. If the content of the polyamide is less than 30% by weight, the flowability may be poor and the appearance and impact resistance of the molded article may be reduced, whereas if the content of the polyamide is more than 70% by weight, the mechanical strength of the molded article may be poor.

[0038] (B) Reinforcement The reinforcing agent is a component for achieving weight reduction while ensuring the mechanical properties, impact resistance, and dimensional stability of the molded article.

[0039] The reinforcing agent may be a fibrous reinforcing agent containing glass fibers and having the shape of a flat plate with a square, elliptical, or polygonal cross section, as shown in FIG.

[0040] The reinforcing agent may have an aspect ratio of 2 to 5, as represented by the following formula 1. [Formula 1] Average long side length of cross section / Average short side length of cross section

[0041] The length of the long side of the cross section of the reinforcing agent is equal to the longest distance between a point located around the cross section of the reinforcing agent and another point where an imaginary line starting from the point and passing through the center of the cross section intersects.

[0042] The length of the short side of the cross section of the reinforcing agent is equal to the shortest distance between a point located around the cross section of the reinforcing agent and another point where an imaginary line starting from the point and passing through the center of the cross section intersects.

[0043] If the flatness of the reinforcing agent is less than 2, deformation of the molded article may occur after molding, and if it exceeds 5, the mechanical properties of the molded article may be poor.

[0044] The reinforcing agent may have an average short side length of 3 μm to 15 μm in cross section. If the average short side length of the reinforcing agent in cross section is less than 3 μm, the dispersibility of the reinforcing agent in the polyamide may be poor, and if it exceeds 15 μm, the mechanical properties and impact resistance of the molded article may be poor.

[0045] The reinforcing agent may have a length of 5 mm to 15 mm. If the length of the reinforcing agent is less than 5 mm, the strength, rigidity, and impact resistance of the molded article may be poor, and the dimensional stability may also be reduced.

[0046] The reinforcing agent may be treated with a sizing material. Specifically, the reinforcing agent may have a sizing material attached to its surface.

[0047] The sizing agent is used to strengthen the bond between the polyamide and the reinforcing agent. The reinforcing agent can be impregnated into the sizing agent to adhere to the surface of the reinforcing agent. However, the method for treating the reinforcing agent is not limited to this, and any method commonly used in the technical field to which the present invention pertains can be used.

[0048] The sizing agent may include at least one selected from the group consisting of urethane resin, acrylic resin, styrene resin, epoxy resin, and combinations thereof.

[0049] The content of the sizing agent may be 0.1 wt % to 3 wt % based on the total weight of the thermoplastic resin composition. If the content of the sizing agent is less than 0.1 wt %, the dispersibility of the reinforcing agent in the polyamide may decrease, resulting in a molded product with poor strength. If the content of the sizing agent is more than 3 wt %, the content of the sizing agent itself may become excessive, resulting in a molded product with poor strength.

[0050] The content of the reinforcing agent may be 20% by weight to 60% by weight, or 30% by weight to 50% by weight. If the content of the reinforcing agent is less than 20% by weight, the strength and impact resistance of the molded article may be poor, and if it exceeds 60% by weight, the weight of the molded article may increase and the flowability of the thermoplastic resin composition may be poor.

[0051] (C) Silane coupling agent The silane coupling agent is used to enhance the compatibility between the polyamide and the reinforcing agent, thereby improving the mechanical properties and impact resistance of the molded article.

[0052] The silane coupling agent may contain an isocyanate functional group, which can form a hydrogen bond with the polyamide or a covalent bond with an amine group remaining in the polyamide, thereby significantly improving the adhesive strength between the components of the thermoplastic resin composition.

[0053] In addition, silane coupling agents containing isocyanate functional groups have a high molecular weight, and are therefore advantageous in that they do not undergo migration under long-term heat resistance conditions, compared to low molecular weight coupling agents.

[0054] The silane coupling agent may include at least one selected from the group consisting of 3-isocyanate propyl trimethoxysilane, 3-isocyanate propyl triethoxysilane, tris[3-(trimethoxysilyl)propyl]isocyanurate, and combinations thereof.

[0055] The content of the silane coupling agent may be 1% by weight to 5% by weight, or 2% by weight to 4% by weight. If the content of the silane coupling agent is less than 1% by weight, the mechanical properties and impact resistance of the molded article may be poor, and if it exceeds 5% by weight, the melt viscosity of the thermoplastic resin composition may increase, resulting in a decrease in flowability and a problem of reduced processability.

[0056] The thermoplastic resin composition can be obtained by mixing the polyamide, the toughening agent, and the silane coupling agent. The mixing method is not particularly limited, and a common melt mixer such as a Banbury mixer, a single-screw extruder, a twin-screw extruder, a multi-screw extruder, or a pultrusion molding machine can be used.

[0057] The thermoplastic resin composition thus obtained can be subjected to extrusion molding, compression molding, injection molding or other methods to obtain the desired molded product.

[0058] The thermoplastic resin composition can be used for various automotive parts that require excellent mechanical properties and dimensional stability. It can also be useful for automotive parts that require weight reduction and reduced production costs in addition to these physical properties. Specifically, the thermoplastic resin composition can be used for sunroof frames.

[0059] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0060] Examples 1 and 2 and Comparative Examples 1 to 9 Thermoplastic resin compositions were prepared according to the formulations shown in Table 1 below.

[0061] [Table 1] (A) Polyamide: Polyamide 6 having a number average molecular weight of approximately 50,000 (B1) Flat-shaped fibrous reinforcing agent: The reinforcing agent shown in FIG. 1, consisting of glass fibers with an average cross-sectional short side length of about 6 μm, an oblateness of about 4, and a length of about 10 mm. 1.5% by weight of sizing agent was used. (B2) Flat-shaped fibrous reinforcing agent: Glass fiber with an average cross-sectional short side length of about 7 μm, an oblateness of about 3, and a length of about 10 mm. 1.5% by weight of sizing agent was used. (B3) Flat-shaped fibrous reinforcing agent: Glass fiber with an average cross-sectional short side length of about 10 μm, an aspect ratio of about 1.5, and a length of about 10 mm. 1.5% by weight of sizing agent was used. (B4) Flat-shaped fibrous reinforcing agent: Glass fiber with an average cross-sectional short side length of about 5 μm, an oblateness of about 5.5, and a length of about 10 mm. 1.5% by weight of sizing agent was used. (B5) Flat-shaped fibrous reinforcing agent: Glass fiber with an average cross-sectional short side length of about 7 μm, flatness of about 3, and length of about 4 mm. 1.5% by weight of sizing agent was used. (B6) Fibrous reinforcing agent: As shown in Figure 2, glass fiber with a circular cross section. The diameter is approximately 12 μm and the length is approximately 10 mm. The fiber is coated with 1.5% by weight of sizing agent. (B7) Fibrous reinforcing agent: Glass fiber with a circular cross section. Glass fiber with a diameter of approximately 12 μm and a length of approximately 4 mm. 1.5% by weight of sizing agent was used. (C1) Tris[3-(trimethoxysilyl)propyl]isocyanurate (C2) 3-Aminopropyltriethoxysilane (C3) Modified polypropylene in which about 8% by weight of maleic anhydride is grafted onto polypropylene

[0062] Molded articles were produced from the thermoplastic resin compositions prepared in this manner. Specifically, the thermoplastic resin compositions of Examples 1 and 2, Comparative Examples 1 to 6, and Comparative Example 8 were extruded using a pultrusion molding machine and then injection molded to obtain molded articles. The thermoplastic resin compositions of Comparative Examples 7 and 9 were extruded using a twin-screw extruder and then injection molded to obtain molded articles.

[0063] The physical properties of the molded product were measured and evaluated by the following methods. - Tensile strength (Mpa): Measured according to ASTM D638. - Flexural strength (MPa): Measured according to ASTM D790. Flexural modulus (MPa): Measured according to the ASTM D790 standard. -IZOD impact strength (kJ / m 2 ): Measured according to ASTM D256 under 1 / 4" notched conditions at room temperature (23°C) and low temperature (-30°C). Heat distortion temperature (°C): The heat distortion temperature was measured according to ASTM D648 when a surface pressure of 1.82 MPa was applied. - Post-deformation: After injecting a 100mm (width) x 200mm (length) x 3mm (thickness) flat test piece into a mold under the same injection conditions, the degree of deformation of the test piece was checked. The evaluation criteria were as follows: O: Almost no warping, △: Slight warping, X: Severe warping

[0064] The results are shown in Table 2 below. [Table 2]

[0065] (Type of coupling agent) Comparing the examples with Comparative Examples 1 and 2, it can be seen that when a silane-based coupling agent containing an isocyanate functional group as in the present invention is used, the mechanical properties are excellent and post-deformation can be prevented.

[0066] (Silane Coupling Agent Content) Comparing the Examples with Comparative Examples 3 and 4, it can be seen that when the silane coupling agent of the present invention is contained in an amount of 1 to 5% by weight, the interfacial adhesion between the polyamide and the reinforcing agent is increased, improving strength and impact resistance, and there is no post-deformation.

[0067] (Flatness of Reinforcing Agent) Comparing the Examples with Comparative Examples 5 and 6, it can be seen that when a reinforcing agent with a flatness of 2 to 5 as in the present invention is used, the dimensional stability is increased to the extent that post-deformation does not occur, and the mechanical properties are improved.

[0068] (Length of Reinforcing Agent) A comparison between the Examples and Comparative Example 7 reveals that when long glass fibers such as those of the present invention are used, the strength, rigidity and impact resistance are improved and dimensional stability is also excellent.

[0069] (Type of Reinforcing Agent) Comparing the Examples with Comparative Examples 8 and 9, it can be seen that when a reinforcing agent having a flat plate shape as in the present invention is used, the dimensional stability is greatly improved.

[0070] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art will understand that the present invention can be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting.

Claims

1. 30% to 70% by weight of polyamide; 20% to 60% by weight of a reinforcing agent comprising glass fibers and having the shape of a flat plate; and Silane coupling agent 1% to 5% by weight A thermoplastic resin composition comprising: The reinforcing agent has a sizing agent attached to its surface, The reinforcing agent has an aspect ratio represented by the following formula 1 of 2 to 5, [Formula 1] Average long side length of cross section / average short side length of cross section The reinforcing agent has a length of 5 mm to 15 mm, the content of the sizing agent is 0.1 to 3% by weight based on the total weight of the thermoplastic resin composition; The thermoplastic resin composition, wherein the silane coupling agent contains an isocyanate functional group.

2. The thermoplastic resin composition according to claim 1 , wherein the polyamide comprises an aliphatic polyamide.

3. 3. The thermoplastic resin composition according to claim 2, wherein the aliphatic polyamide comprises at least one selected from the group consisting of polyamide 6, polyamide 46, polyamide 66, polyamide 610, polyamide 612, polyamide 6 / 12, polyamide 1010, polyamide 11, polyamide 1012, polyamide 12, polyamide 1212, and combinations thereof.

4. 2. The thermoplastic resin composition according to claim 1, wherein the polyamide has a number average molecular weight of 20,000 to 70,000. [Formula 1] Average long side length of cross section / average short side length of cross section

5. 2. The thermoplastic resin composition according to claim 1, wherein the reinforcing agent has an average short side length in cross section of 3 μm to 15 μm.

6. The thermoplastic resin composition according to claim 1, wherein the sizing agent comprises at least one selected from the group consisting of a urethane resin, an acrylic resin, a styrene resin, an epoxy resin, and combinations thereof.

7. 2. The thermoplastic resin composition according to claim 1, wherein the isocyanate functional group of the silane coupling agent forms a hydrogen bond with the polyamide or a covalent bond with an amine group of the polyamide.

8. The thermoplastic resin composition according to claim 1, wherein the silane-based coupling agent comprises at least one selected from the group consisting of 3-isocyanate propyl trimethoxysilane, 3-isocyanate propyl triethoxysilane, tris[3-(trimethoxysilyl)propyl]isocyanurate, and combinations thereof.

9. A sunroof frame comprising the thermoplastic resin composition according to any one of claims 1 to 8.

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