Fiber-reinforced resin molded body and its manufacturing method, composite pellets, and chopped strands

Abstract

To provide a fiber-reinforced resin molded product having both warp-suppressing properties and mechanical properties.SOLUTION: A fiber-reinforced resin molded product (1) includes a resin (10) and a plurality of glass filaments (21). The plurality of glass filaments (21) have a flat cross-sectional shape with a flattening ratio of greater than 1.0 and less than or equal to 7.0. The plurality of glass filaments (21) have (i) 50-100% of a first flatness ratio category (A1) having a flatness ratio of greater than 2.8 and less than or equal to 4.6 and (ii) 0-50% of a second flatness ratio category (A2) having a flatness ratio of greater than 4.6 and less than or equal to 7.0. A first histogram showing a distribution of flatness ratios has at least two peaks.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a fiber-reinforced resin molding containing a resin and glass filaments. [Background technology]

[0002] Conventionally, glass fiber reinforced moldings formed by blending glass fibers with thermoplastic resins or thermosetting resins have been known. Glass fiber reinforced moldings are widely used as materials for various structures due to their excellent mechanical properties.

[0003] In recent years, various studies have been conducted with the aim of further improving the performance of structures. For example, Patent Document 1 discloses a resin composition consisting of 40 to 99 parts by weight of a thermoplastic resin made of an aromatic polycarbonate resin and 1 to 60 parts by weight of a reinforcing filler. The reinforcing filler is composed of (1) flat cross-section glass fibers having an average major axis value of 10 to 50 μm and an average ratio of the major axis to the minor axis value of 1.5 to 8, and (2) circular cross-section short glass fibers having an average fiber length to average fiber diameter ratio (aspect ratio) of 10 or less, and the weight ratio of the flat cross-section glass fibers to the circular cross-section short glass fibers is 5 / 95 to 95 / 5.

[0004] Patent Document 2 discloses a glass fiber reinforced polyamide resin composition containing a polyamide resin and glass fibers. Some or all of the glass fibers contained in the glass fiber reinforced polyamide resin composition are flat cross section glass fibers, and the flat cross section glass fibers are composed of flat cross section glass fibers having a minor axis / major axis ratio of 0.3 to 0.5 and flat cross section glass fibers having a minor axis / major axis ratio of 0.2 to 0.3. The mass ratio of the flat cross section glass fibers to the flat cross section glass fibers is 0:100 to 100:0. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-186571 A [Patent Document 2] International Publication No. WO2019 / 074038 Summary of the Invention [Problem to be solved by the invention]

[0006] When a structure made of a glass fiber reinforced molding is thinned (when the thickness of the structure is reduced), the structure is prone to warping after resin molding, and the mechanical properties of the structure are prone to decrease. In response to increasing demands for the performance of structures, there is a demand for further improvements in the warping resistance (warping suppression properties) and mechanical properties of the structures.

[0007] An object of one aspect of the present invention is to provide a fiber-reinforced resin molding that combines warpage suppression properties and mechanical properties. [Means for solving the problem]

[0008] In order to solve the above problems, a fiber-reinforced resin molding in one embodiment of the present invention is a fiber-reinforced resin molding including a resin and a plurality of glass filaments, the glass filaments having a flat cross-sectional shape with an aspect ratio (longer diameter / minor diameter) in a transverse section in a range of more than 1.0 and not more than 7.0, (i) a blending ratio of the glass filaments having an aspect ratio classified in a first aspect ratio range of more than 2.8 and not more than 4.6 is 50 to 100% relative to a specific total number of the glass filaments, and (ii) a blending ratio of the glass filaments having an aspect ratio classified in a second aspect ratio range of more than 4.6 and not more than 7.0 is 0 to 50%, and a first histogram showing a distribution of the aspect ratio for the specific total number of glass filaments, with the horizontal axis being the aspect ratio, the vertical axis being the blending ratio, and a class width of 0.2, has at least two peaks.

[0009] In one embodiment of the present invention, the composite pellets include a resin and a plurality of glass filaments, the glass filaments having a flat cross-sectional shape with an aspect ratio (longer diameter / minor diameter) in a transverse section in a range of more than 1.0 and not more than 7.0, (i) a blending ratio of the glass filaments having an aspect ratio classified in a first aspect ratio category of more than 2.8 and not more than 4.6 is 50 to 100% relative to a specific total number of the plurality of glass filaments, and (ii) a blending ratio of the glass filaments having an aspect ratio classified in a second aspect ratio category of more than 4.6 and not more than 7.0 is 0 to 50%, and a first histogram showing a distribution of the aspect ratios for the specific total number of glass filaments, with the horizontal axis representing the aspect ratio, the vertical axis representing the blending ratio, and a class width of 0.2, has at least two peaks.

[0010] In one embodiment of the present invention, the chopped strand includes a plurality of glass filaments, the glass filaments having a flat cross-sectional shape with an aspect ratio (long axis / short axis) in a transverse section in a range of more than 1.0 and not more than 7.0, (i) a blending ratio of the glass filaments having an aspect ratio classified in a first aspect ratio category of more than 2.8 and not more than 4.6 is 50 to 100% relative to a specific total number of the plurality of glass filaments, and (ii) a blending ratio of the glass filaments having an aspect ratio classified in a second aspect ratio category of more than 4.6 and not more than 7.0 is 0 to 50%, and a first histogram showing a distribution of the aspect ratio for the specific total number of glass filaments, with the horizontal axis representing the aspect ratio, the vertical axis representing the blending ratio, and a class width of 0.2, has at least two peaks.

[0011] In addition, a method for producing a fiber-reinforced resin molded body in one aspect of the present invention includes a preparation step of preparing the chopped strands, a pellet formation step of kneading the chopped strands and a thermoplastic resin to form composite pellets, and an injection molding step of performing injection molding using the composite pellets. Effect of the Invention

[0012] According to one aspect of the present invention, it is possible to provide a fiber-reinforced resin molding that combines warpage suppression properties and mechanical properties. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing a configuration of a fiber-reinforced resin molded body in one embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is a cross-sectional view of a glass filament cut along a plane (transverse section) perpendicular to the longitudinal direction. [Diagram 3] 4 is a histogram showing the distribution of the aspect ratio of glass filaments contained in a fiber-reinforced resin molding in one embodiment of the present invention. [Figure 4] 3 is a histogram showing the distribution of circle-equivalent diameters of glass filaments contained in a fiber-reinforced resin molding according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of the present invention will be described below. Note that the following description is intended to provide a better understanding of the gist of the invention, and is not intended to limit the present invention unless otherwise specified.

[0015] In one embodiment of the present invention, first, molten glass is drawn out from a bushing and cooled to form a flat fiber having an elliptical cross section with a circle equivalent diameter of several μm to several tens of μm. Next, a treatment agent is applied to the flat fiber and the fibers are bundled to form a strand (glass strand). The strand is then cut to a predetermined length to obtain a chopped strand.

[0016] Glass fiber is a general term for an aggregate of glass filaments (for example, a bundle of 100 or more filaments) and individual single fibers dispersed from glass fibers (resulting from the opening of glass fibers). A single fiber that constitutes glass fiber is called a glass filament, an aggregate of multiple glass filaments is called a glass strand, and a glass strand cut to a specified length is called a chopped strand (glass chopped strand).

[0017] In addition, in this specification, the "flatness ratio" means the ratio of the length of the major axis to the length of the minor axis in the shape of the surface to be calculated. The "flatness ratio in the cross section" of the glass filament is used in the following sense. That is, when measuring the flatness ratio in the cross section of the glass filament contained in the resin molding, the end face of the glass filament is usually observed. In this case, the end face is not necessarily flat, but the shape formed by the outer edge of the end face when the end face is viewed from a line of sight parallel to the longitudinal direction of the glass filament (for example, an ellipse or a rounded rectangle) is regarded as the shape of the "cross section" of the glass filament to calculate the flatness ratio.

[0018] The distribution of the aspect ratio means a frequency distribution, and can be understood, for example, by a histogram with the horizontal axis representing the aspect ratio and the vertical axis representing the frequency (number) or relative frequency (mixture ratio). The distribution of the aspect ratio indicates the bias and variation of the aspect ratio in a collection of a specific total number of measurement objects (for example, glass filaments).

[0019] (Brief Description of the Findings of the Invention) Prior to describing the fiber-reinforced resin molding according to one embodiment of the present invention, the findings of the present inventors will be outlined below.

[0020] The fiber-reinforced resin molding may include resin, glass filaments constituting the glass fibers, and glass filaments dispersed from the glass fibers. Unless otherwise specified in this specification, the characteristics of the glass filaments described below are characteristics that appear when both the glass filaments constituting the glass fibers and the glass filaments dispersed from the glass fibers are mixed together. For example, the characteristics of the glass filaments contained in the fiber-reinforced resin molding described in this specification mean the overall characteristics of the multiple glass filaments contained in the fiber-reinforced resin molding that appear in combination without distinguishing the specific aspects of the individual glass filaments. In addition, in a fiber-reinforced resin molding formed using chopped strands, the overall characteristics of the glass filaments contained in the fiber-reinforced resin molding are approximately the same as the overall characteristics of the glass filaments contained in the chopped strands.

[0021] A resin molded body formed to include glass filaments having a cross-sectional shape with an aspect ratio of about 4 can have improved mechanical properties. Generally, the resin of a resin molded body undergoes thermal shrinkage during its manufacturing process. The effect of thermal shrinkage of the resin is small in a resin molded body having a relatively large thickness. However, warping is likely to occur in a resin molded body having a relatively small thickness. It is believed that glass filaments having a cross-sectional shape with an aspect ratio of about 4 do not sufficiently suppress warping of the resin molded body.

[0022] In contrast, glass filaments having a cross-sectional shape with an aspect ratio of more than 4 have relatively good fluidity (dispersibility) in molten resin and are relatively effective in suppressing warping of resin molded articles. However, resin molded articles formed to include glass filaments having a cross-sectional shape with an aspect ratio of more than 4 have a problem in that they have mechanical strength lower than the required performance when the thickness of the resin molded article is reduced.

[0023] Under such circumstances, the present inventors have conducted intensive studies and found the following findings. That is, the aspect ratio distribution of the glass filaments contained in the resin molding is appropriately adjusted (details will be described later). As a result, both glass filaments having an aspect ratio shape that is likely to improve the property of suppressing warping and glass filaments having an aspect ratio shape that is likely to improve the mechanical properties are contained in the resin molding. Specifically, chopped strands are produced so that the aspect ratio distribution of the glass filaments shows a histogram including multiple peaks, and the chopped strands can be used to obtain a fiber-reinforced resin molding according to one embodiment of the present invention.

[0024] The many glass filaments contained in the chopped strands may have various distributions of flatness ratios due to differences in the manufacturing process. For example, the flatness ratio distribution of the glass filaments contained in the strands can be changed by adjusting conditions such as the hole shape (arrangement of holes) of the bushing that draws out the molten glass and various manufacturing temperatures. On the other hand, when two or more types of chopped strands having different medians in the flatness ratio distribution of the glass filaments are simply mixed, the proportion of glass filaments having flatness ratios between the respective medians of the two or more types of chopped strands increases. As a result, chopped strands showing a histogram that does not include a peak (for example, a half-width of 2.0 or more, or no half-width exists) can be obtained. That is, the fiber-reinforced resin molding in one embodiment of the present invention has improved performance compared to a resin molding produced by simply mixing two or more types of chopped strands.

[0025] (Fiber reinforced plastic molding) Fig. 1 is a schematic diagram showing the configuration of a fiber-reinforced resin molded body 1 in this embodiment. For simplification, in Fig. 1, the fiber-reinforced resin molded body 1 is illustrated as a rectangular parallelepiped. The shape of the fiber-reinforced resin molded body 1 can be appropriately changed depending on the purpose of use, and the specific shape is not particularly limited.

[0026] As shown in FIG. 1, the fiber-reinforced resin molding 1 includes resin 10, glass fibers 20, and glass filaments 21 dispersed from the glass fibers 20, with a large number of glass fibers 20 and glass filaments 21 dispersed in the resin 10.

[0027] The fiber reinforced resin molding 1 may have a total content of the resin 10, the glass fibers 20, and the glass filaments 21 of 90% by mass or more, or may have a total content of 95% by mass or more. The fiber reinforced resin molding 1 may contain other additive components in addition to the resin 10 and the glass filaments 21.

[0028] (resin) The resin 10 may be a thermosetting resin or a thermoplastic resin. Examples of the thermoplastic resin include polyamide resin and polycarbonate resin. By using a thermoplastic resin as the resin 10, injection molding becomes possible as described below, and it becomes easier to mold various structures. The resin 10 may be a mixture of two or more resins.

[0029] (Glass fiber / glass filament) The glass fiber 20 is formed by bundling a plurality of glass filaments 21 and has an elongated shape. In the fiber reinforced resin molding 1, the content of the glass filaments 21 may be 10% by mass or more and 70% by mass or less, and may be 20% by mass or more and 50% by mass or less. If the content of the glass filaments 21 is less than 10% by mass, it is difficult to obtain a glass fiber reinforced resin molding having sufficient mechanical properties. If the content of the glass filaments 21 is more than 70% by mass, the moldability of the fiber reinforced resin molding 1 is poor.

[0030] 2 is a cross-sectional view of the glass filament 21 cut in a plane (cross section) perpendicular to the longitudinal direction. The long diameter of the cross-sectional shape of the glass filament 21 is designated as long diameter L1, and the short diameter is designated as short diameter L2. In this specification, the longest length in the cross section of the glass filament 21 is defined as the "long diameter of the glass filament 21", and the longest length in the cross section of the glass filament 21 in a direction perpendicular to the long diameter is defined as the "short diameter of the glass filament 21".

[0031] The glass filaments 21 have a flattened cross-sectional shape, with the flattening ratio in the cross section, that is, the ratio (average value) of the major axis L1 to the minor axis L2 (major axis L1 / minor axis L2) being in the range of more than 1.0 and not more than 7.0.

[0032] The cross-sectional shape of the glass filaments 21 is not limited to an ellipse, and may be any shape as long as the value (average value) of the flattening ratio expressed by major axis L1 / minor axis L2 is in the range of more than 1.0 and not more than 7.0. The glass filaments 21 have a flattened shape with an irregular cross section, and may have a flattened shape such as an oval, an ellipse, or a rounded rectangle. The glass filaments 21 preferably have an oval flattened shape. If the flattening ratio of the glass filaments 21 is more than 7.0, it is difficult to obtain a fiber-reinforced resin molding 1 that satisfies the required characteristics.

[0033] The composition of the glass filaments 21 may be, for example, E glass, ECR glass, A glass, AR glass, C glass, D glass, S glass, T glass, NE glass, H glass, etc. The composition of the glass filaments 21 is not particularly limited as long as it is possible to manufacture a fiber-reinforced plastic molding 1 having both warp suppression properties and mechanical properties. In addition, the fiber-reinforced plastic molding 1 may be a mixture of two or more types of glass filaments 21.

[0034] The glass filaments 21 may have a minor axis L2 in the cross section of 4 to 20 μm, or may be 6 to 15 μm, and the glass filaments 21 may have a major axis L1 in the cross section of 10 to 50 μm, or may be 20 to 35 μm.

[0035] (Aspect ratio distribution) The aspect ratio distribution of the glass filaments 21 contained in the fiber reinforced resin molding 1 in this embodiment will be described below. The aspect ratio distribution of the glass filaments 21 contained in the fiber reinforced resin molding 1 is approximately the same as the aspect ratio distribution of the glass filaments 21 contained in the chopped strands used in the manufacturing process of the fiber reinforced resin molding 1. Therefore, the chopped strands used in the manufacturing process of the fiber reinforced resin molding 1 may be used for the various measurements described below.

[0036] First, the measurement of the flattening ratio distribution is described as follows. That is, the flattening ratio distribution is measured for a specific total number of glass filaments. This "specific total number" may be the total number of glass filaments 21 whose flattening ratios are measured, and may be, for example, 1000 or more. Hereinafter, the specific total number may be expressed as N. In order to observe the cross section of the glass filaments 21, the glass filaments 21 are vertically embedded in room temperature curing resin Technovit (manufactured by Kulzer), and polished after the resin is cured. Next, the cross-sectional shape of the glass filaments 21 is observed with an electron microscope, and the lengths of the major axis L1 and the minor axis L2 of the observed glass filaments 21 are measured to calculate the flattening ratio. Then, the specific total number of glass filaments 21 whose flattening ratios have been calculated are classified into a plurality of flattening ratio ranges, and the blending ratio in each flattening ratio range is quantified.

[0037] In the fiber reinforced resin molding 1, the distribution of the flatness ratio of the glass filaments 21 measured as described above is as shown below. That is, the blending ratio of the glass filaments 21 having an aspect ratio classified in (i) a flatness ratio section greater than 2.8 and less than 4.6 (hereinafter referred to as the first flatness ratio section A1) is 50 to 100%, and the blending ratio of the glass filaments 21 having an aspect ratio classified in (ii) a flatness ratio section greater than 4.6 and less than 7.0 (hereinafter referred to as the second flatness ratio section A2) is 0 to 50%, relative to a specific total number of the glass filaments 21. If the blending ratio of the first flatness ratio section A1 is less than 50%, it is difficult to obtain a fiber reinforced resin molding 1 having both sufficient mechanical properties and warpage suppression properties.

[0038] Furthermore, in the fiber reinforced resin molding 1, the aspect ratio distribution of the glass filaments 21 shows a multi-peaked histogram (a histogram having multiple peaks). This will be described below with reference to Fig. 3. Fig. 3 is a histogram showing the distribution of the aspect ratio of the glass filaments 21 contained in the fiber reinforced resin molding 1 of this embodiment.

[0039] The histogram shown in Fig. 3 is a histogram (first histogram) showing the flattening ratio distribution, which is created with the horizontal axis representing the flattening ratio of the glass filaments 21, the vertical axis representing the blending ratio of the glass filaments 21, and a class width of 0.2. Fig. 3 also shows the cumulative blending ratios (cumulative relative frequencies in the histogram) in each of the above-mentioned first to third flattening ratio categories. The value of the cumulative blending ratio is shown on the right axis.

[0040] The fiber reinforced resin molding 1 in this embodiment has at least two peaks in the first histogram. When the fiber reinforced resin molding 1 has two peaks in the first histogram, both peaks have peak positions in an aspect ratio range greater than 2.8.

[0041] In addition, in the first histogram of the fiber-reinforced resin molding 1, both the first aspect ratio section A1 and the second aspect ratio section A2 may include a class indicating at least one peak value of a peak.

[0042] In the example shown in FIG. 3, the first histogram has a first peak centered (peak position) on a class of aspect ratios greater than 3.8 and equal to or less than 4.0, and a second peak centered (peak position) on a class of aspect ratios greater than 5.0 and equal to or less than 5.2. The fiber-reinforced resin molding 1 includes a plurality of glass filaments 21 that form the first peak in the aspect ratio distribution, thereby effectively improving mechanical properties. The fiber-reinforced resin molding 1 includes a plurality of glass filaments 21 that form the second peak in the aspect ratio distribution, thereby improving warpage suppression properties. As a result, the fiber-reinforced resin molding 1 has both good mechanical properties and warpage suppression properties.

[0043] Furthermore, the fiber reinforced resin molding 1 may have a blending ratio of 0 to 15% of the glass filaments 21 having an aspect ratio classified into a third aspect ratio section A3 of more than 1.0 and not more than 2.8 relative to a specific total number (N pieces) of the glass filaments 21. If the blending ratio of the third aspect ratio section A3 exceeds 15%, it is difficult to obtain a fiber reinforced resin molding 1 having both sufficient mechanical properties and warpage suppression properties.

[0044] In one embodiment of the present invention, the fiber reinforced resin molding 1 may have a blending ratio of the glass filaments 21 having an aspect ratio classified in the third aspect ratio division of 0 to 10%, a blending ratio of the glass filaments 21 having an aspect ratio classified in the first aspect ratio division of 60 to 80%, and a blending ratio of the glass filaments 21 having an aspect ratio classified in the second aspect ratio division of 20 to 40%. In addition, the fiber reinforced resin molding 1 may have a blending ratio of the glass filaments 21 having an aspect ratio classified in the third aspect ratio division of 0 to 5%, a blending ratio of the glass filaments 21 having an aspect ratio classified in the first aspect ratio division of 65 to 75%, and a blending ratio of the glass filaments 21 having an aspect ratio classified in the second aspect ratio division of 25 to 35%. This can further improve the mechanical properties and warp suppression properties.

[0045] In addition, in a fiber-reinforced resin molding 1 according to one embodiment of the present disclosure, in a first histogram, (i) the difference between the maximum and minimum values ​​of the blending ratio in each class included in the first aspect ratio division is 5% or more, (ii) the difference between the maximum and minimum values ​​of the blending ratio in each class included in the second aspect ratio division is 5% or more, and (iii) at least either the first aspect ratio division or the second aspect ratio division may include a class showing a peak value of one peak.

[0046] Furthermore, in the fiber-reinforced resin shaped body 1, the peak value of the blending ratio of each of at least two peaks in the first histogram may be 5% or more.In the fiber-reinforced resin shaped body 1 of one embodiment of the present disclosure, the half-width of each of the at least two peaks in the first histogram may be 0.5 to 1.6.

[0047] In the fiber-reinforced resin molding 1 according to one embodiment of the present disclosure, the difference between the class values ​​of the different classes indicating the respective peak values ​​of at least two peaks in the first histogram may be 0.4 or more. In the example shown in Fig. 3, the difference between the class values ​​of the different classes indicating the respective peak values ​​of the two peaks is 1.2.

[0048] (Circle equivalent diameter distribution) The circle equivalent diameter distribution of the glass filaments 21 contained in the fiber-reinforced resin molding 1 in this embodiment will be described below. Similar to the above-mentioned method used in measuring the aspect ratio distribution, the circle equivalent diameter distribution can be measured for a specific total number of multiple glass filaments.

[0049] In the fiber-reinforced resin molding 1 of this embodiment, the equivalent circle diameter of the glass filaments 21 in the cross section is preferably in the range of 6 to 27 μm. If the equivalent circle diameter of the glass filaments 21 is less than 6 μm, it is difficult to manufacture the fiber-reinforced resin molding 1 while maintaining a flat cross-sectional shape, and if the equivalent circle diameter of the glass filaments 21 is more than 27 μm, sufficient mechanical properties and warpage suppression properties cannot be obtained.

[0050] Further, in the fiber reinforced resin molding 1, it is preferable that (i) the blending ratio of the glass filaments 21 having a circle equivalent diameter classified into a circle equivalent diameter section of 6 μm or more and less than 13 μm (hereinafter referred to as the first circle equivalent diameter section B1) is 15 to 25%, (ii) the blending ratio of the glass filaments 21 having a circle equivalent diameter classified into a circle equivalent diameter section of 13 μm or more and less than 15 μm (hereinafter referred to as the second circle equivalent diameter section B2) is 55 to 65%, and (iii) the blending ratio of the glass filaments 21 having a circle equivalent diameter classified into a circle equivalent diameter section of 15 μm or more and less than 27 μm (hereinafter referred to as the third circle equivalent diameter section B3) is 15 to 25% with respect to a specific total number of the glass filaments 21. According to the above configuration, a fiber reinforced resin molding having both warp suppression properties and mechanical properties can be easily obtained.

[0051] Furthermore, in the fiber reinforced resin molding 1, the circle equivalent diameter distribution of the glass filaments 21 shows a unimodal histogram. This will be described below with reference to Fig. 4. Fig. 4 is a histogram showing the circle equivalent diameter distribution of the glass filaments 21 contained in the fiber reinforced resin molding 1 of this embodiment. Fig. 4 also shows the cumulative blending ratio (the cumulative relative frequency in the histogram) in each of the above-mentioned first to third circle equivalent diameter categories in the graph. The value of the cumulative blending ratio is shown on the right axis.

[0052] The histogram shown in FIG. 4 is a histogram (second histogram) showing the distribution of equivalent circle diameters, created with the horizontal axis representing the equivalent circle diameters of the glass filaments 21, the vertical axis representing the blending ratio of the glass filaments 21, and a class interval of 0.25.

[0053] In the fiber reinforced resin molding 1 according to one embodiment of the present disclosure, the second histogram has a single-peak distribution. In other words, in the fiber reinforced resin molding 1 according to one embodiment of the present disclosure, the second histogram has only one peak. The second histogram shown in FIG. 4 has only one peak centered (peak position) on the class in which the aspect ratio is greater than 13.0 μm and equal to or less than 13.25 μm. With the above-mentioned configuration, a fiber reinforced resin molding having both warpage suppression properties and mechanical properties can be easily obtained.

[0054] (fiber length) The multiple glass filaments 21 contained in the fiber-reinforced resin molding 1 may have an average fiber length of 1 μm or more and 9000 μm or less, 10 μm or more and 900 μm or less, 100 μm or more and 500 μm or less, or 300 μm or more and 400 μm or less.

[0055] In the fiber reinforced resin molding 1 of this embodiment, the average fiber length of the glass filaments 21 can be calculated as follows. First, the fiber reinforced resin molding 1 is heated in an incinerator at 650°C to decompose the organic matter in the fiber reinforced resin molding 1, thereby obtaining the glass filaments 21 contained in the fiber reinforced resin molding 1. The obtained glass filaments 21 are transferred to a glass petri dish, and the glass filaments 21 are dispersed in the glass petri dish using a solvent such as acetone. Next, the fiber length of the glass filaments 21 in the glass petri dish is measured using an electron microscope. The fiber lengths of 1,000 or more glass filaments 21 are measured, and the average value is taken as the average fiber length.

[0056] (Other Ingredients) The fiber reinforced resin molded body 1 in this embodiment may contain a coloring agent, a flame retardant, etc., as necessary. By containing these components, for example, the fiber reinforced resin molded body 1 can be colored in a desired color. In addition, the fire resistance of the fiber reinforced resin molded body 1 can be improved.

[0057] [4. Manufacturing method of fiber reinforced resin molding] A method for producing the fiber reinforced resin molded body 1 in this embodiment will be described below. The method for producing the fiber reinforced resin molded body 1 in this embodiment includes a preparation step of preparing chopped strands, a pellet formation step, and an injection molding step.

[0058] In the above preparation step, a chopped strand including a plurality of glass filaments 21 having a desired aspect ratio distribution as described above may be prepared, and the specific method is not particularly limited. For example, the chopped strand may be manufactured by forming a bundle (strand) of flat fibers having a desired aspect ratio distribution and continuously cutting the strand to an appropriate length. For example, the aspect ratio distribution of the strand can be changed by adjusting the hole shape (hole arrangement) of the bushing that draws out the molten glass and various manufacturing conditions.

[0059] The chopped strand in one embodiment of the present invention includes a plurality of glass filaments 21, and the glass filaments 21 have a flat cross-sectional shape in which the flatness ratio (long diameter / short diameter) in the transverse section is in the range of more than 1.0 and not more than 7.0. In the chopped strand in this embodiment, the blending ratio of the glass filaments 21 having an aspect ratio classified in the first aspect ratio section A1 of more than 2.8 and not more than 4.6 is 50 to 100% with respect to a specific total number (N pieces) of the plurality of glass filaments 21, and the blending ratio of the glass filaments 21 having an aspect ratio classified in the second aspect ratio section of more than 4.6 and not more than 7.0 is 0 to 50%. In the chopped strand in this embodiment, a first histogram showing the distribution of the flatness ratio for the specific total number (N pieces) of glass filaments 21, in which the horizontal axis represents the flatness ratio, the vertical axis represents the blending ratio, and the class width is 0.2, has at least two peaks.

[0060] Next, in the pellet forming step, the chopped strands and a thermoplastic resin are kneaded to form composite pellets. As the thermoplastic resin, polyamide resin, polycarbonate resin, etc. can be used. The composite pellets formed in the pellet forming step are also included in the scope of the present invention. The composite pellets in one embodiment of the present invention include a resin 10, a plurality of glass fibers 20, and glass filaments 21 dispersed from the glass fibers 20. The glass fibers 20 include a plurality of bundled glass filaments 21 having a flat cross-sectional shape. The glass filaments 21 have an aspect ratio (major axis / minor axis) in a cross section in a range of more than 1.0 and not more than 7.0. In the composite pellet of this embodiment, the blending ratio of the glass filaments 21 having an aspect ratio classified into a first aspect ratio section of more than 2.8 and not more than 4.6 is 50 to 100% relative to a specific total number (N pieces) of the glass filaments 21, and the blending ratio of the glass filaments 21 having an aspect ratio classified into a second aspect ratio section of more than 4.6 and not more than 7.0 is 0 to 50% relative to a specific total number (N pieces) of the glass filaments 21. In the composite pellet of this embodiment, a first histogram showing the distribution of the aspect ratio with the horizontal axis representing the aspect ratio, the vertical axis representing the blending ratio, and a class width of 0.2 for the specific total number (N pieces) of the glass filaments 21 has at least two peaks.

[0061] The injection molding step is a step of performing injection molding using the composite pellets formed in the pellet forming step. A fiber-reinforced resin molded body 1 is manufactured by the injection molding step.

[0062] [Additional notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the above description are also included in the technical scope of the present invention. EXAMPLES

[0063] Hereinafter, examples of the fiber-reinforced resin molding according to one embodiment of the present invention will be described, but the present invention is not limited to these examples.

[0064] Chopped strands containing glass fibers of E-glass composition with adjusted flatness distribution were mixed with polyamide resin PA66 (Zytel 1011, manufactured by DuPont) using a twin-screw extruder to produce composite pellets of glass fibers and resin.

[0065] Next, the obtained composite pellets were used for injection molding using an injection molding machine to prepare test pieces conforming to ASTM D638 (Type-1), ASTM D790, and ASTM D6110 for tensile strength tests, bending strength tests, and Charpy impact strength tests. In addition, a 150 x 150 x 2.5 mm flat plate was prepared using an injection molding machine as a test piece for measuring warpage height.

[0066] The tensile strength, bending strength, Charpy impact strength, and warpage height were measured by the methods described below.

[0067] <Tensile strength> Test pieces conforming to ASTM D638 (Type-1) were tested under conditions conforming to ASTM D638 (Type-1) using a precision universal testing machine (Shimadzu Corporation, Autograph AG-X plus 50kN) to measure tensile strength.

[0068] <Bending strength> Test pieces conforming to ASTM D790 were subjected to a precision universal testing machine (Shimadzu Corporation, Autograph AG-X plus 10kN) under conditions conforming to ASTM D790 to measure bending strength.

[0069] <Charpy impact strength> Test pieces conforming to ASTM D6110 were subjected to a test using an impact tester (UF impact tester manufactured by Ueshima Seisakusho Co., Ltd.) under conditions conforming to ASTM D6110 to measure the tensile strength.

[0070] <Warp height> A flat plate of 150 mm x 150 mm x 2.5 mm was used as a test piece for warpage height, and one end of the test piece was placed on a flat surface, and the maximum deformation distance from the flat surface was measured with a vernier caliper to determine the warpage height.

[0071] (evaluation) The obtained fiber reinforced resin molding has a tensile strength of 175 MPa or more, a bending strength of 240 MPa or more, and a Charpy impact strength of 10 kJ / m 2 When the warpage height was 12 mm or less, the mechanical properties were evaluated as being high. When the warpage height was 12 mm or less, the warpage suppression properties were evaluated as being high.

[0072] (Test Results) Fiber-reinforced resin molded articles were obtained for Examples 1 to 4 and Comparative Examples 1 to 6. The test results for each fiber-reinforced resin molded article are shown in Table 1. In Table 1, "Number of peaks (peak positions)" indicates the number and peak positions of peaks in the first histogram showing the aspect ratio distribution.

[0073] [Table 1]

[0074] As shown in Table 1, the fiber-reinforced resin moldings of Examples 1 to 4 had an average glass filament flatness ratio in the range of more than 1.0 and not more than 7.0, a first flatness ratio range was 50 to 100%, and a second flatness ratio range was 0 to 50%. The third flatness ratio range was 0 to 15%. The flatness ratio distribution had two peaks. It can be seen that Examples 1 to 4 have both mechanical properties and warpage suppression properties.

[0075] On the other hand, the fiber-reinforced resin moldings of Comparative Examples 1 to 6 did not satisfy the conditions of the present invention, and at least one of the mechanical properties and warpage suppression properties was insufficient. [Explanation of symbols]

[0076] 1 Fiber-reinforced resin molding 10 Resin 20 Glass fiber 21 Glass filament

Claims

1. A fiber-reinforced resin molding comprising a resin and a plurality of glass filaments, The glass filaments each have a flat cross-sectional shape with a flatness ratio (major axis / minor axis) in a transverse cross section in a range of more than 1.0 and not more than 7.0, (i) a blending ratio of the glass filaments having an aspect ratio classified into a first aspect ratio section greater than 2.8 and equal to or less than 4.6 is 50 to 100%, and (ii) a blending ratio of the glass filaments having an aspect ratio classified into a second aspect ratio section greater than 4.6 and equal to or less than 7.0 is 0 to 50%, relative to a specific total number of the plurality of glass filaments; A fiber-reinforced resin molding, in which a first histogram showing a distribution of the aspect ratio for the specific total number of glass filaments, the horizontal axis being the aspect ratio, the vertical axis being the blending ratio, and the class interval being 0.2, has at least two peaks.

2. The fiber-reinforced resin molding according to claim 1 , wherein each of the two peaks in the first histogram has a peak position in an aspect ratio range greater than 2.

8.

3. The blending ratio of the glass filaments having an aspect ratio classified into a third aspect ratio category greater than 1.0 and less than or equal to 2.8 with respect to the specific total number of the plurality of glass filaments is 0 to 15%. The fiber-reinforced resin molding according to claim 1 or 2.

4. The blending ratio of the glass filaments having an aspect ratio classified into the third aspect ratio division is 0 to 10%, the blending ratio of the glass filaments having an aspect ratio classified into the first aspect ratio division is 60 to 80%, and the blending ratio of the glass filaments having an aspect ratio classified into the second aspect ratio division is 20 to 40%. The fiber-reinforced resin molding according to claim 3.

5. The blending ratio of the glass filaments having an aspect ratio classified into the third aspect ratio division is 0 to 5%, the blending ratio of the glass filaments having an aspect ratio classified into the first aspect ratio division is 65 to 75%, and the blending ratio of the glass filaments having an aspect ratio classified into the second aspect ratio division is 25 to 35%. The fiber-reinforced resin molding according to claim 3 or 4.

6. The glass filaments have a cross-sectional equivalent circle diameter in the range of 6 to 27 μm, (i) the blending ratio of the glass filaments having a circle equivalent diameter classified into a first circle equivalent diameter division of 6 μm or more and less than 13 μm is 15 to 25%, (ii) the blending ratio of the glass filaments having a circle equivalent diameter classified into a second circle equivalent diameter division of 13 μm or more and less than 15 μm is 55 to 65%, and (iii) the blending ratio of the glass filaments having a circle equivalent diameter classified into a third circle equivalent diameter division of 15 μm or more and 27 μm or less is 15 to 25%, relative to the specific total number of the plurality of glass filaments. The fiber-reinforced resin molding according to any one of claims 1 to 5.

7. 7. The fiber-reinforced resin molding according to claim 6, wherein a second histogram showing a distribution of the equivalent circle diameters for the specific total number of glass filaments, the horizontal axis being the equivalent circle diameter, the vertical axis being the blending ratio, and the class width being 0.25 μm, is a unimodal distribution.

8. In the first histogram, the difference between the maximum and minimum values ​​of the blending ratio in each class included in the first aspect ratio division is 5% or more; the difference between the maximum and minimum values ​​of the blending ratio in each class included in the second aspect ratio division is 5% or more; The fiber-reinforced resin molding according to any one of claims 1 to 7, wherein at least one of the first flattening ratio division or the second flattening ratio division includes a class indicating a peak value of one peak.

9. The fiber-reinforced resin molding according to any one of claims 1 to 8, wherein the peak value of each of the blending ratios of the at least two peaks in the first histogram is 5% or more.

10. The fiber reinforced resin molding according to any one of claims 1 to 9, wherein the half width of each of the at least two peaks in the first histogram is 0.5 to 1.

6.

11. The fiber-reinforced resin molding according to any one of claims 1 to 10, wherein a difference between class values ​​of different classes indicating the peak values ​​of each of the at least two peaks in the first histogram is 0.4 or more.

12. In the first histogram, both the first flattening ratio division and the second flattening ratio division include a class indicating a peak value of at least one peak. The fiber-reinforced resin molding according to any one of claims 1 to 11.

13. The fiber-reinforced resin molded body according to any one of claims 1 to 12, wherein the resin is an injection-moldable thermoplastic resin.

14. A composite pellet comprising a resin and a plurality of glass filaments, The glass filaments have a flat cross-sectional shape with a flatness ratio (major axis / minor axis) in a cross section in the range of more than 1.0 and not more than 7.0, (i) a blending ratio of the glass filaments having an aspect ratio classified into a first aspect ratio section greater than 2.8 and equal to or less than 4.6 is 50 to 100%, and (ii) a blending ratio of the glass filaments having an aspect ratio classified into a second aspect ratio section greater than 4.6 and equal to or less than 7.0 is 0 to 50%, relative to a specific total number of the plurality of glass filaments; A composite pellet, wherein a first histogram showing a distribution of the aspect ratio with the horizontal axis representing the aspect ratio, the vertical axis representing the blending ratio, and a class interval of 0.2 for the specific total number of glass filaments has at least two peaks.

15. A chopped strand including a plurality of glass filaments, The glass filaments have a flat cross-sectional shape with a flatness ratio (major axis / minor axis) in a cross section in the range of more than 1.0 and not more than 7.0, (i) a blending ratio of the glass filaments having an aspect ratio classified into a first aspect ratio section greater than 2.8 and equal to or less than 4.6 is 50 to 100%, and (ii) a blending ratio of the glass filaments having an aspect ratio classified into a second aspect ratio section greater than 4.6 and equal to or less than 7.0 is 0 to 50%, relative to a specific total number of the plurality of glass filaments; A chopped strand, wherein a first histogram showing a distribution of the aspect ratio with the horizontal axis representing the aspect ratio, the vertical axis representing the blending ratio, and a class interval of 0.2 for the specific total number of glass filaments has at least two peaks.

16. A preparation step of preparing chopped strands according to claim 15; a pellet forming step of kneading the chopped strands with a thermoplastic resin to form composite pellets; and an injection molding step of performing injection molding using the composite pellets.

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