JP2019209509A - Fiber-reinforced resin - Google Patents

Abstract

To provide the fiber-reinforced resin having excellent mechanical properties and retaining molding processability.SOLUTION: The fiber-reinforced resin containing a thermoplastic resin, a glass fiber and nanocellulose is characterized by that the glass fiber has an irregular cross section.SELECTED DRAWING: None

Description

  The present invention relates to a fiber reinforced resin.

  The fiber reinforced resin is a composite material in which a fiber material such as glass fiber, carbon fiber, alumina fiber, or aramid fiber is blended with the resin. Since such a resin is lightweight and excellent in mechanical properties and moldability, it is used as a substitute for metal in transportation equipment such as automobiles and airplanes and electronic members of various electrical products.

  Until now, relatively inexpensive glass fiber among fiber materials has been widely used as a material for fiber reinforced resin. Particularly in recent years, various methods for improving mechanical properties such as tensile strength and bending strength in glass fiber-containing fiber reinforced resins have been studied in order to cope with higher performance of fiber reinforced resin parts.

  As a method for improving the mechanical properties of the glass fiber-containing fiber reinforced resin, a method of containing a large amount of glass fiber, a method of adjusting the glass fiber length, and the like have been studied. For example, Patent Document 1 discloses a molded product obtained by molding a composition obtained by mixing 20 to 90% by weight of polytetramethylene adipamide and 10 to 80% by weight of glass fibers having an average fiber length of 1 to 20 mm. A polyamide resin molded product characterized in that the average glass fiber length in the molded product is 0.05 to 0.6 mm and the standard deviation of the glass fiber length is 0.1 to 0.5 mm is disclosed. ing.

  Patent Document 2 discloses that 99.5 to 70% by weight of one or more thermoplastic resins (A) selected from styrene-based resins, polycarbonate-based resins, and polyphenylene ether-based resins, and liquid crystalline resins (B) 0. A fiber reinforced resin composition consisting of 100 parts by weight of a resin composition consisting of 5 to 30% by weight and 5 to 300 parts by weight of glass fiber, and having a fiber length distribution of 0.1 to 1 mm in the composition. A fiber reinforced resin composition that is 60% or more is disclosed.

  Furthermore, Patent Document 3 discloses a resin composition containing 35 to 49% by weight of polycarbonate resin (A) and 65 to 51% by weight of glass fiber (B), and is a weight average of glass fibers in the resin composition. Using a test piece having a length of 260 μm or more, a 4 mm-thickness obtained by molding the resin composition, the bending strength measured based on ISO 178 is 240 MPa or more, and the bending elastic modulus is 14 GPa or more. A glass fiber reinforced polycarbonate resin composition is disclosed.

Japanese Patent Publication No. 8-22947 JP 2000-159958 A Japanese Patent Laid-Open No. 2006-79355

  By the way, a fiber reinforced resin part using a thermoplastic resin as in the above-mentioned patent document is often processed into a desired shape by injection molding. In general, when the amount of glass fiber contained in the fiber reinforced resin is increased, the mechanical properties of the fiber reinforced resin are improved, but the fluidity during molding is often lowered. Such a fiber-reinforced resin having low fluidity needs to be injection-molded with a larger force, and thus there has been a problem of deterioration in molding processability such as the injection nozzle being easily clogged. Therefore, there has been a demand for a fiber reinforced resin having mechanical properties that can cope with high performance of fiber reinforced resin parts without impairing moldability.

  The present invention has been made in view of the above problems, and provides a fiber reinforced resin having improved mechanical properties without impairing moldability.

  The fiber reinforced resin of the present invention is a fiber reinforced resin containing a thermoplastic resin, glass fiber, and nanocellulose, and the glass fiber has an irregular cross section.

  The fiber reinforced resin which consists of the said structure contains the glass fiber which has a deformed cross section. Since the glass fiber having such a modified cross section is more easily oriented in the flow direction during kneading with the resin and injection molding than the glass fiber having a circular cross section, the flow resistance is reduced. As a result, even if the amount of glass fiber increases, the fluidity is unlikely to decrease, so that the moldability of the fiber reinforced resin can be maintained. In addition, since the flow resistance is reduced, the glass fiber is not easily broken, and the glass fiber can easily maintain the initial fiber length. As a result, the reinforcing effect of the fiber reinforced resin by the glass fiber is improved, and the mechanical properties can be improved.

  Furthermore, the fiber reinforced resin which consists of the said structure contains the nano cellulose in addition to the glass fiber. Nanocellulose has a high aspect ratio and functions to improve mechanical properties by forming a network by being entangled with each other. As a result, the glass fiber content necessary for obtaining the desired mechanical properties can be reduced, so that the fluidity of the fiber reinforced resin is less likely to be lowered, and the moldability can be improved. In addition, since glass fibers having an irregular cross section are used in the present invention, the area of the interface between the glass fibers, the resin, and the nanocellulose is larger than when glass fibers having a circular cross section are introduced. The reinforcing effect by cellulose can be obtained more efficiently. Thus, by containing both the glass fiber and nano cellulose which have an irregular cross section, a mutual reinforcement effect can be heightened and both mechanical characteristics and moldability can be made compatible.

  In the fiber reinforced resin of the present invention, when the major axis in the cross section of the glass fiber is A and the minor axis is B, the cross-sectional shape flat ratio (A / B) is preferably 1.1 to 10. If it does in this way, it will become easy to orientate in a flow direction at the time of kneading with resin and injection molding, and it can improve moldability more.

  The fiber reinforced resin of the present invention preferably contains 10 to 60% glass fiber and less than 0.1 to 15% nanocellulose by mass%.

  In the fiber reinforced resin of the present invention, the mass ratio of nanocellulose to glass fiber is preferably 0.002 to 1.5.

  In the fiber reinforced resin of the present invention, the glass fiber is preferably chopped strand.

  In the fiber reinforced resin of the present invention, the average diameter of nanocellulose is preferably 3 to 100 nm.

  The fiber reinforced resin component of the present invention is characterized by comprising the above fiber reinforced resin.

  The method for producing a fiber-reinforced resin part of the present invention is characterized in that the fiber-reinforced resin is injection-molded.

  ADVANTAGE OF THE INVENTION According to this invention, the fiber reinforced resin which improved the mechanical characteristic can be provided, without impairing moldability.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

(Thermoplastic resin)
The thermoplastic resin of the present invention is not particularly limited as long as it is generally available on the market, but it is preferable to use a thermoplastic resin having high heat resistance, particularly when producing a fiber reinforced resin part that requires heat resistance. .

  Examples of the thermoplastic resin include polypropylene resin, polyethylene resin, polystyrene resin, acrylic resin, polyamide resin, polycarbonate resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyacetal resin, and modified polyphenylene ether. Resin, polyethersulfone resin, polyamideimide resin, polyetherimide resin, polyetheretherketone resin, polyphenylene sulfide resin, polysulfone resin, polyarylate resin, thermoplastic polyimide, and the like. Further, fluorine-based resins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-ethylene copolymer (ETFE) can also be used.

  In addition, any of the above thermoplastic resins may be used alone or in admixture of two or more.

(Glass fiber)
Glass fiber is an important material that imparts mechanical properties, dimensional stability, and moldability to thermoplastic resins. Glass fibers can be obtained at low cost, and can be easily mixed with various thermoplastic resins by applying an arbitrary sizing agent.

  The glass fiber in the present invention has an irregular cross section. In particular, when the major axis in the cross section is A and the minor axis is B, the cross-sectional aspect ratio (A / B) is preferably 1.1 to 10, more preferably 2 to 8, and more preferably 3 to 7 preferable. When the flatness ratio of the cross-sectional shape is too low, the glass fiber is difficult to be oriented in the flow direction during kneading with the thermoplastic resin and injection molding, and the flow resistance is increased, so that the molding processability is lowered. In addition, since the area of the interface between the glass fiber and the thermoplastic resin is reduced and the reinforcing effect by the glass fiber is reduced, it is difficult to obtain desired mechanical characteristics. On the other hand, when the flatness ratio of the cross-sectional shape is too high, the glass fiber is easily broken and it becomes difficult to obtain desired mechanical characteristics. In addition, the unusual cross section which has a cross section which has such a flat ratio shows an oval or flat cross-sectional shape normally. In addition, although it is preferable that all the glass fibers have an irregular cross section, a part of glass fiber may have a circular cross section. Specifically, the proportion of fibers having a modified cross section among the glass fibers contained is preferably 80% or more, more preferably 90% or more, and particularly preferably 95% or more.

  The glass fiber in the present invention preferably has a perfect circle equivalent diameter of 5 to 30 μm, more preferably 7 to 25 μm, and particularly preferably 10 to 25 μm. In addition, a perfect circle equivalent diameter means the diameter of the perfect circle which has an area equal to the area of the irregular cross section of glass fiber. If the true circle equivalent diameter of the glass fiber is too small, the glass fiber is easily broken, making it difficult to obtain desired mechanical properties. On the other hand, if the true circle equivalent diameter of the glass fiber is too large, the contact area between the glass fiber and the thermoplastic resin becomes small, and the reinforcing effect by the glass fiber becomes small, making it difficult to obtain desired mechanical characteristics.

  The length of the glass fiber is preferably 1 to 20 mm, more preferably 1 to 11 mm, and particularly preferably 1 to 10 mm. If the glass fiber is too long, the fluidity of the glass fiber is deteriorated, so that the glass fiber is likely to be unevenly distributed in the thermoplastic resin. If the glass fiber is too short, it is difficult to obtain desired mechanical properties.

  The glass fiber content in the fiber reinforced resin is 10 to 60% by mass, preferably 11 to 55%, and more preferably 15 to 50%. If the glass fiber content is too small, mechanical properties such as bending strength and tensile strength are lowered. On the other hand, when there is too much content, moldability will fall.

  The glass fiber in the present invention is preferably chopped strand. Here, the chopped strand means a bundle of the above glass fibers and cut into a predetermined length. Since the chopped strand has a high aspect ratio, it is preferable from the viewpoint of improving mechanical properties such as bending strength and tensile strength. 1-20 mm is preferable, as for the length of a chopped strand, 1-11 mm is more preferable, and 1-10 mm is especially preferable.

(Nanocellulose)
Nanocellulose in the present invention is generally called by the name of cellulose nanofiber, cellulose microfibril, cellulose microfibril bundle, microfibrillated cellulose, etc., and is a fiber material containing a nanostructure composed of cellulose molecules. Inclusive meaning. These generally have a diameter of 3 nm to 100 nm, and depending on the fiber length, cellulose nanofiber (fiber length 5 μm to), cellulose nanowhisker (fiber length 100 to 500 nm), cellulose nanocrystal (fiber length 100 to 500 nm), etc. being classified. In particular, since the cellulose nanofiber has a high aspect ratio, the fibers are entangled with each other, and the mechanical properties of the fiber reinforced resin can be improved. In addition, you may use these nano cellulose individually or in mixture of 2 or more types.

  Nanocellulose in the present invention can be obtained by defibrating plant raw materials such as pulp. The defibration method is either mechanical defibration using a defibrator such as a strong shear kneader or a ball mill pulverizer, chemical defibration using TEMPO catalytic oxidation, or a combination of both. preferable. For example, when mechanical defibrating is used, it becomes easy to obtain nanocellulose having a large fiber diameter. Moreover, when chemical defibration is used, it becomes easy to obtain nanocellulose having a small fiber diameter and a short fiber length.

  Thus, since the shape of the nanocellulose obtained by the defibrating method is different, it is preferable to select an optimum method capable of obtaining a desired mechanical property to produce the nanocellulose.

  In addition, in terms of uniformly dispersing nanocellulose in the thermoplastic resin, it is preferable that variations in average diameter and length are small. In the method in which the modified pulp is dispersed while being defibrated in the resin, the defibration may be insufficient and may be unevenly distributed in the thermoplastic resin. Therefore, it is preferable to use nanocellulose in a defibrated state as a raw material. By doing in this way, it can prevent that nanocellulose is unevenly distributed in a thermoplastic resin.

  Content of the nano cellulose in fiber reinforced resin is the mass%, and is less than 0.1-15%, 0.2-12% is preferable and 0.3-10% is more preferable. When there is too little content of nanocellulose, it will become difficult to improve mechanical characteristics, such as tensile strength. On the other hand, when there is too much content, the fluidity | liquidity of fiber reinforced resin will fall and the moldability in injection molding will fall. Specifically, an increase in time required for injection molding or clogging of the injection nozzle may occur. In addition, from the viewpoint of increasing the impact strength of the fiber reinforced resin component, it is preferable that the content of nanocellulose is small. Specifically, it is preferably 4% or less, particularly preferably 3% or less.

  The average diameter of the nanocellulose is preferably 3 to 100 nm, more preferably 5 to 90 nm, and particularly preferably 11 to 80 nm. If it is such an average diameter, the specific surface area of the nano cellulose which contacts a thermoplastic resin will become large, and a mechanical characteristic can be improved. The length of the nanocellulose is preferably 0.1 μm or more, more preferably 1 μm or more, further preferably 3 μm or more, and particularly preferably 5 μm or more. By setting it as such a value, a mechanical characteristic can be improved.

  The aspect ratio of nanocellulose is preferably 50 or more, more preferably 100 or more, and particularly preferably 500 or more. If the aspect ratio of nanocellulose is too small, the effect of improving the mechanical properties of the resin composition will be small.

  The nanocellulose of the present invention may be obtained by chemically modifying the surface as necessary. For example, nanocellulose modified with a functional group such as an alkyl group, an acyl group, a cyano group, an alkoxy group, an aryl group, an amino group, an aryloxy group, a silyl group, or a carboxyl group can be used.

  The mass ratio of nanocellulose to glass fiber (nanocellulose / glass fiber) is preferably 0.002 to 1.5, more preferably 0.05 to 1.5, still more preferably 0.1 to 0.9, and 0 .1 to 0.8 is particularly preferable. If the mass ratio of nanocellulose to glass fiber is too low, the improvement in mechanical properties of the fiber reinforced resin is reduced. On the other hand, when the mass ratio is too high, the moldability of the fiber reinforced resin is lowered. In addition, it is preferable that the mass ratio of the nano cellulose with respect to glass fiber is low from a viewpoint of raising the impact strength of a fiber reinforced resin component. In this case, 0.002 to 0.6 is preferable, 0.005 to 0.5 is more preferable, and 0.01 to 0.4 is particularly preferable.

  Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to these examples.

  Tables 1 and 2 show examples (Nos. 1 to 4, 9, 10, and 13) and comparative examples (Nos. 5 to 8, 11, 12, and 14) of the present invention.

(Sample preparation)
The following raw materials were used for the preparation of the sample. Polyamide resin PA-6 (Novamid 1013J manufactured by DSM) was used as the thermoplastic resin. As the glass fiber, a glass chopped strand having an irregular cross section with an aspect ratio of 4 to 7 and a glass chopped strand having a circular cross section were used. Nanocellulose powder prepared by freeze-drying Vinfis (Sugino Machine WMa-10010) was used as nanocellulose. Binfisu is a dispersion of nanocellulose in water. Therefore, when nanocellulose was pulverized, in order to prevent aggregation due to moisture, t-butanol was substituted for water, and then lyophilized.

  Samples were prepared as follows. First, polyamide resin and glass fiber are kneaded separately with a uniaxial kneader (manufactured by Sumitomo Heavy Industries, Ltd.), polyamide resin and nanocellulose powder with a biaxial kneader (manufactured by Toshiba Machine Co., Ltd.), and molded into a rod shape. The obtained rod-shaped molded product was cut at regular intervals to prepare pellets made of polyamide resin and glass fiber, and pellets made of polyamide resin and nanocellulose powder. Then, after weighing and mixing the two types of pellets and the additional polyamide resin so as to obtain the mixing ratio of each sample described in the table, the desired plate shape is obtained with an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd.). Molded into.

(Evaluation of physical properties)
About the produced test sample, tensile strength, bending strength, and Izod impact strength were measured. The tensile strength was measured according to ASTM D-638 (Type-1), the bending strength was measured according to ASTM D790, and the Izod impact strength was measured according to ASTM D-256.

  The evaluation of the moldability was judged from the fluidity (molding time) when the fiber reinforced resin was molded under the same conditions with an injection molding machine. Comparative Example No. 14 with reference to the molding time No. 14 A case where it was equal to or earlier than 14 was judged as “◯”, and a case where it was clearly delayed was judged as “x”. The evaluation results obtained in the examples and comparative examples are shown in Tables 1 and 2.

  As is clear from Tables 1 and 2, Examples (No. 1-4, 9, 10, 13) using glass fibers having a high aspect ratio are comparative examples containing the same amount of glass fibers and nanocellulose ( Compared with No. 5-7, 11, 12, 14), the mechanical properties of tensile strength, bending strength, and Izod impact strength were higher. Further, in all examples, the moldability was “◯”.

  In addition, Comparative Example No. containing 15% by mass of nanocellulose. No. 8 was comparatively excellent in tensile strength and bending strength, but the molding time was comparative example No. 8. It was clearly slower than 14, and the molding processability was “x”.

Claims (8)

  A fiber reinforced resin containing a thermoplastic resin, glass fiber, and nanocellulose, wherein the glass fiber has an irregular cross section.   2. The fiber according to claim 1, wherein when the major axis in the cross section of the glass fiber is A and the minor axis is B, the cross-sectional aspect ratio (A / B) is 1.1-10. Reinforced resin.   The fiber-reinforced resin according to claim 1 or 2, wherein the fiber-reinforced resin contains 10 to 60% glass fiber and less than 0.1 to 15% nanocellulose by mass%.   The fiber-reinforced resin according to any one of claims 1 to 3, wherein the mass ratio of nanocellulose to glass fiber is 0.002 to 1.5.   The fiber reinforced resin according to any one of claims 1 to 4, wherein the glass fiber is chopped strand.   The average diameter of nanocellulose is 3-100 nm, The fiber reinforced resin as described in any one of Claims 1-5 characterized by the above-mentioned.   A fiber-reinforced resin part comprising the fiber-reinforced resin according to any one of claims 1 to 6.   A method for producing a fiber-reinforced resin component, comprising injection-molding the fiber-reinforced resin according to any one of claims 1 to 6.