JP2023039108A - Fiber reinforced resin molded product and manufacturing method thereof, composite pellet and chopped strand - Google Patents

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 The present invention relates to fiber-reinforced resin moldings and the like containing resin and glass filaments.

BACKGROUND ART Conventionally, there has been known a glass fiber reinforced molding formed by blending glass fibers with a thermoplastic resin or a thermosetting resin. Glass fiber reinforced moldings are widely used as materials for various structures because of their excellent mechanical properties.

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 comprising 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 long diameter of 10 to 50 μm in fiber cross section and an average ratio of long diameter to short diameter of 1.5 to 8, and (2) average fiber length and the 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. It's becoming

Further, Patent Document 2 discloses a glass fiber-reinforced polyamide resin composition containing a polyamide resin and a glass fiber. 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 have a flat cross-section having a minor axis/major axis ratio of 0.3 to 0.5. It is composed of glass fibers 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 fiber and the flat cross-section glass fiber is 0:100 to 100:0.

JP 2007-186571 A International Publication No. WO2019/074038

When a structure made of a glass fiber reinforced molded body is made thinner (when the thickness of the structure becomes thinner), the structure tends to warp after resin molding, and the mechanical properties of the structure deteriorate. is easy to reduce. In response to the increasing demand for the performance of structures, further improvements in warpage resistance (warpage suppression properties) and mechanical properties of structures are being demanded.

An object of one aspect of the present invention is to provide a fiber-reinforced resin molded article having both warp-suppressing properties and mechanical properties.

In order to solve the above problems, a fiber-reinforced resin molded article in one aspect of the present invention is a fiber-reinforced resin molded article containing a resin and a plurality of glass filaments, wherein the plurality of glass filaments has a cross section has a flat cross-sectional shape with a flatness ratio (major axis/minor axis) in the range of more than 1.0 and 7.0 or less, and for a specific total number of the plurality of glass filaments, (i) from 2.8 The blending ratio of the glass filaments having a flatness ratio classified into the first flatness ratio category of 4.6 or less is 50 to 100%; The blending ratio of the glass filaments having a flatness ratio classified into the flatness ratio category is 0 to 50%, and for the specific total number of glass filaments, the horizontal axis is the flatness ratio, the vertical axis is the blending ratio, and the class width is 0. A first histogram showing the distribution of the flatness ratio of .2 has at least two peaks.

Further, the composite pellet in one aspect of the present invention is a composite pellet containing a resin and a plurality of glass filaments, wherein the glass filaments have a flatness ratio (major axis/minor axis) in a cross section of more than 1.0 and 7 having a flattened cross-sectional shape in the range of 0.0 or less, and falling into a first flatness ratio category of (i) greater than 2.8 and less than or equal to 4.6 for a specified total number of said plurality of glass filaments; The blending ratio of the glass filaments having the flatness ratio is 50 to 100%, and (ii) the blending ratio of the glass filaments having the flatness ratio classified into the second flatness ratio category of greater than 4.6 and 7.0 or less. is 0 to 50%, and for the specific total number of glass filaments, the first histogram showing the distribution of the flatness ratio with the horizontal axis as the flatness ratio, the vertical axis as the blending ratio, and the class width of 0.2 is at least It has two peaks.

Further, the chopped strand in one aspect of the present invention is a chopped strand containing a plurality of glass filaments, and the glass filaments have a flatness ratio (major axis/minor axis) in a cross section of more than 1.0 and 7.0. (i) a flatness ratio classified into a first flatness ratio category of greater than 2.8 and less than or equal to 4.6, with respect to a specific total number of the plurality of glass filaments having a flattened cross-sectional shape within the following range: is 50 to 100%, and (ii) the glass filament having a flatness ratio classified into the second flatness ratio category of greater than 4.6 and 7.0 or less is 0. ~ 50%, and for the specific total number of glass filaments, the first histogram showing the distribution of the flatness ratio with the horizontal axis as the flatness ratio, the vertical axis as the blending ratio, and the class width of 0.2. has peaks.

Further, a method for producing a fiber-reinforced resin molded article in one aspect of the present invention includes a preparation step of preparing the chopped strands, a pellet forming step of kneading the chopped strands and a thermoplastic resin to form composite pellets, An injection molding step of performing injection molding using the composite pellet,

According to one aspect of the present invention, it is possible to provide a fiber-reinforced resin molded article having both warp-suppressing properties and mechanical properties.

1 is a schematic diagram showing the configuration of a fiber-reinforced resin molded article in one embodiment of the present invention. FIG. FIG. 3 is a cross-sectional view of the glass filament cut along a plane (cross section) perpendicular to the longitudinal direction. 4 is a histogram showing the distribution of flatness ratios of glass filaments contained in a fiber-reinforced resin molded article in one embodiment of the present invention. 4 is a histogram showing the distribution of equivalent circle diameters of glass filaments contained in a fiber-reinforced resin molded article according to one embodiment of the present invention.

An embodiment of the present invention will be described below. The following description is for better understanding of the gist of the invention, and does not limit the invention unless otherwise specified.

In one embodiment of the present invention, first, molten glass is pulled out from a bushing and cooled to form a flat fiber having an elliptical cross-section and an equivalent circle diameter of several μm to several tens of μm. Next, a strand (glass strand) is formed by applying a treatment agent to the flat fibers and bundling them. Then, the strand is cut to a predetermined length to obtain chopped strands.

Glass fiber is a general term for an aggregate of glass filaments (for example, a bundle of 100 or more) and individual single fibers dispersed from glass fibers (produced by opening glass fibers). A single fiber constituting a glass fiber is called a glass filament, an aggregate of a plurality of glass filaments is called a glass strand, and a glass strand cut to a predetermined length is called a chopped strand (glass chopped strand).

Further, 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. At this time, the end face is not necessarily flat, but the shape formed by the outer edge of the end face (for example, an ellipse or a rounded rectangle) when the end face is viewed with a line of sight parallel to the longitudinal direction of the glass filament. , the flatness ratio is calculated by considering the shape of the "cross section" of the glass filament.

The distribution of the flatness ratio means a frequency distribution, and is grasped by a histogram, for example, in which the horizontal axis is the flatness ratio and the vertical axis is frequency (number) or relative frequency (combination ratio). The distribution of flatness ratios indicates the bias and variation in flatness ratios in a collection of a specific total number of measurement objects (eg, glass filaments).

(Brief description of the findings of the invention)
Prior to describing the fiber-reinforced resin molded article in one aspect of the present invention, the following is an overview of the knowledge found by the present inventors.

The fiber-reinforced resin molding may contain resin, glass filaments forming glass fibers, and glass filaments dispersed from the glass fibers. Unless otherwise specified in this specification, the properties of the glass filaments described below are properties that appear when both the glass filaments constituting the glass fibers and the glass filaments dispersed from the glass fibers are mixed. . For example, the properties of the glass filaments contained in the fiber-reinforced resin molded article described in the present specification are expressed collectively without distinguishing the specific aspects of individual glass filaments. means the overall properties of the glass filament. In addition, in the fiber-reinforced resin molded body formed using chopped strands, the overall properties of the glass filaments contained in the fiber-reinforced resin molded body are almost the same as the overall properties of the glass filaments contained in the chopped strands. Become.

A resin molded article formed to include glass filaments having a cross-sectional aspect ratio of about 4 can have improved mechanical properties. Here, in general, the resin molded body undergoes heat shrinkage during the manufacturing process. A resin molding having a relatively large thickness is less affected by heat shrinkage of the resin. However, a resin molding having a relatively small thickness is likely to warp. A glass filament having a cross section with an aspect ratio of about 4 is considered to have an insufficient effect of suppressing warpage of a resin molded body.

On the other hand, glass filaments with a cross-sectional flatness ratio of more than 4 have relatively good fluidity (dispersibility) in the molten resin, and the effect of suppressing warping of the resin molded product is comparatively high. high. However, a resin molded body formed to contain glass filaments having a shape with an aspect ratio of greater than 4 in the cross section has a problem that when the thickness of the resin molded body is reduced, the mechanical strength is lower than the required performance. was there.

Under such circumstances, the present inventors found the following knowledge as a result of earnest investigation. That is, the flatness ratio distribution of the glass filaments contained in the resin molding is appropriately adjusted (details will be described later). Thereby, both the glass filaments having the flatness ratio shape that facilitates enhancing the warp suppressing properties and the glass filaments having the flatness ratio shape that facilitates enhancing the mechanical properties are included in the resin molding. Specifically, chopped strands are produced so that the flatness ratio distribution of the glass filaments exhibits a histogram including a plurality of peaks, and the chopped strands can be used to obtain the fiber-reinforced resin molded article according to one aspect of the present invention. .

A large number of glass filaments contained in the chopped strands may have various flatness ratio distributions due to differences in manufacturing processes. For example, the flatness ratio distribution of the glass filaments contained in the strand can be changed by adjusting the hole shape (hole arrangement) of the bushing through which the molten glass is drawn out and various manufacturing temperatures. On the other hand, when two or more chopped strands having different medians in the flatness ratio distribution of the glass filaments are simply mixed, the existence ratio of the glass filaments having flatness ratios between the respective medians of the two or more chopped strands is growing. As a result, chopped strands can be obtained that exhibit a histogram that does not contain peaks (eg, half-width greater than or equal to 2.0, or no half-width). That is, the fiber-reinforced resin molded article according to one aspect of the present invention has improved performance as compared with a resin molded article produced by simply mixing two or more types of chopped strands.

(Fiber-reinforced resin molding)
FIG. 1 is a schematic diagram showing the configuration of a fiber-reinforced resin molding 1 according to this embodiment. In FIG. 1, for the sake of simplification, the fiber-reinforced resin molding 1 is illustrated as a rectangular parallelepiped. The shape of the fiber-reinforced resin molded body 1 can be appropriately changed according to the purpose of use, and the specific shape is not particularly limited.

As shown in FIG. 1, the fiber-reinforced resin molding 1 includes a resin 10, glass fibers 20, and glass filaments 21 dispersed from the glass fibers 20. A large number of glass fibers 20 and glass filaments 21 are dispersed in the resin 10. are doing.

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

(resin)
A thermosetting resin or a thermoplastic resin can be used for the resin 10 . Examples of thermoplastic resins that can be used include polyamide resins and polycarbonate resins. By using a thermoplastic resin as the resin 10, injection molding becomes possible as described later, and various structures can be easily molded. The resin 10 may be a mixture of two or more resins.

(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 molded article 1, the content of the glass filaments 21 may be 10% by mass or more and 70% by mass or less, or 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 becomes difficult to obtain a glass fiber reinforced resin molded article having sufficient mechanical properties. Moreover, if the content of the glass filaments 21 is more than 70% by mass, the moldability of the fiber-reinforced resin molded article 1 becomes poor.

FIG. 2 is a cross-sectional view of the glass filament 21 cut along a plane (cross section) perpendicular to the longitudinal direction. Let L1 be the major axis of the cross-sectional shape of the glass filament 21, and L2 be the minor axis thereof. In this specification, the longest length in the cross section of the glass filament 21 is the “longest diameter of the glass filament 21”, and the longest length in the cross section of the glass filament 21 in the direction perpendicular to the long diameter is “the glass filament 21. It is defined as "minor diameter" and used.

In the glass filament 21, the flatness ratio in the cross section, that is, the value (average value) of the ratio of the major axis L1 to the minor axis L2 (major axis L1/minor axis L2) is in the range of more than 1.0 and 7.0 or less. and has a flat cross-sectional shape.

Note that the cross-sectional shape of the glass filament 21 is not limited to an elliptical shape, and the flatness ratio value (average value) represented by the major axis L1/minor axis L2 is greater than 1.0 and 7.0 or less. Any shape may be used as long as it is within the range of The glass filament 21 has a flattened shape with a modified cross-section, and may have a flattened shape such as an oval, an ellipse, or a rounded rectangle, for example. The glass filament 21 preferably has an oblong flat shape. If the flatness ratio of the glass filaments 21 is more than 7.0, it is difficult to obtain the fiber-reinforced resin molding 1 that satisfies the required properties.

The composition of the glass filament 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, or the like. The composition of the glass filaments 21 is not particularly limited as long as the fiber-reinforced resin molded article 1 having both warp-suppressing properties and mechanical properties can be produced. Further, the fiber-reinforced resin molded body 1 may be a mixture of two or more types of glass filaments 21 .

The glass filament 21 may have a minor axis L2 of 4 to 20 μm, or 6 to 15 μm in cross section. Further, the glass filament 21 may have a major axis L1 of 10 to 50 μm, or 20 to 35 μm, in the cross section.

(flatness ratio distribution)
The flatness ratio distribution of the glass filaments 21 contained in the fiber-reinforced resin molding 1 in this embodiment will be described below. The distribution of the flatness ratio of the glass filaments 21 contained in the fiber-reinforced resin molded body 1 is substantially the same as the distribution of the flatness ratio of the glass filaments 21 contained in the chopped strands used in the manufacturing process of the fiber-reinforced resin molded body 1. become. 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.

First, the measurement of the flatness ratio distribution is described below. That is, the flatness ratio distribution is measured for a specific total number of multiple glass filaments. This "specific total number" may be the total number of the glass filaments 21 whose flatness ratio is measured, and may be, for example, 1000 or more. Below, the specific total number may be expressed as N. In order to observe the cross section of the glass filament 21, a plurality of glass filaments 21 are vertically embedded in a room-temperature curing resin Technovit (manufactured by Kulzer), and polished after curing the resin. Next, the cross-sectional shape of the glass filament 21 is observed with an electron microscope, and the major axis L1 and the minor axis L2 of the observed glass filament 21 are measured to calculate the flatness ratio. Then, by classifying each of the specific total number of glass filaments 21 for which the flatness ratio was calculated into a plurality of flatness ratio ranges, the compounding ratio in each flatness ratio range was quantified.

In the fiber-reinforced resin molded article 1, the flatness ratio distribution of the glass filaments 21 measured as described above has a distribution shown below. That is, for a specific total number of the plurality of glass filaments 21, (i) the flatness ratio classified into the flatness ratio division greater than 2.8 and 4.6 or less (hereinafter referred to as the first flatness ratio division A1) The glass filament 21 has a compounding ratio of 50 to 100%, and (ii) is classified into a flatness ratio category greater than 4.6 and 7.0 or less (hereinafter referred to as a second flatness ratio category A2). The compounding ratio of the glass filaments 21 having a is 0 to 50%. If the blending ratio of the first aspect ratio class A1 is less than 50%, it is difficult to obtain the fiber-reinforced resin molded article 1 that has both sufficient mechanical properties and warpage suppressing properties.

Furthermore, in the fiber-reinforced resin molding 1, the flatness ratio distribution of the glass filaments 21 exhibits a multimodal histogram (a histogram having a plurality of peaks). This will be explained below with reference to FIG. FIG. 3 is a histogram showing the distribution of the flatness ratio of the glass filaments 21 contained in the fiber-reinforced resin molding 1 of this embodiment.

The histogram shown in FIG. 3 is a histogram (first histogram) showing the flatness ratio distribution, created with the flatness ratio of the glass filaments 21 on the horizontal axis, the blending ratio of the glass filaments 21 on the vertical axis, and the class width of 0.2. be. In FIG. 3, the graph also shows the cumulative mixture ratio (cumulative relative frequency in the histogram) in each of the first to third flatness ratio divisions. Cumulative percentage values are shown on the right axis.

The fiber-reinforced resin molded article 1 in this embodiment has at least two peaks (also referred to as peaks) in the first histogram. When the fiber-reinforced resin molded article 1 has two peaks in the first histogram, both of the two peaks have peak positions in a flatness ratio range greater than 2.8.

In addition, in the first histogram, both the first flatness ratio division A1 and the second flatness ratio division A2 of the fiber-reinforced resin molded body 1 include a class indicating a peak value of at least one peak. good too.

In the example shown in FIG. 3, in the first histogram, the first peak centered (peak position) is in the class where the flatness ratio is greater than 3.8 and 4.0 or less, and the flatness ratio is higher than 5.0. It has a second peak whose center (peak position) is a class of 5.2 or less. The fiber-reinforced resin molding 1 effectively improves the mechanical properties by including the plurality of glass filaments 21 forming the first peak in the aspect ratio distribution. Further, the fiber-reinforced resin molded article 1 can enhance the warpage suppressing property by including the plurality of glass filaments 21 forming the second peak in the aspect ratio distribution. As a result, the fiber-reinforced resin molded article 1 has both good mechanical properties and warp-suppressing properties.

In addition, the fiber-reinforced resin molded body 1 has a flatness ratio division of more than 1.0 and 2.8 or less (hereinafter referred to as a third flatness ratio division) for a specific total number (N pieces) of the plurality of glass filaments 21. A3) may be 0 to 15%. If the blending ratio of the third aspect ratio class A3 exceeds 15%, it is difficult to obtain the fiber-reinforced resin molded article 1 having both sufficient mechanical properties and warpage suppressing properties.

The fiber-reinforced resin molded body 1 according to one aspect of the present invention has a compounding ratio of 0 to 10% of the glass filaments 21 having the flatness ratio classified into the third flatness ratio category, and is classified into the first flatness ratio category. The blending ratio of the glass filaments 21 having an oblateness ratio of 60 to 80% may be 20 to 40%, and the blending ratio of the glass filaments 21 having an oblateness ratio classified into the second oblateness ratio category may be 20 to 40%. . In addition, the fiber-reinforced resin molded body 1 has a blending ratio of 0 to 5% of the glass filaments 21 having the flatness ratio classified into the third flatness ratio category, and the flatness ratio classified into the first flatness ratio category. may be 65 to 75%, and the blending ratio of the glass filaments 21 having a flatness ratio classified into the second flatness ratio category may be 25 to 35%. As a result, the mechanical properties and warpage suppression properties can be further improved.

In addition, in the first histogram, the fiber-reinforced resin molded article 1 of one aspect of the present disclosure shows that (i) the difference between the maximum value and the minimum value of the blending ratio in each class included in the first flatness ratio division is 5 % or more, (ii) the difference between the maximum value and the minimum value of the blending ratio in each class included in the second flatness ratio division is 5% or more, and (iii) the first flatness ratio division or the second At least one of the flatness ratio divisions of may include a class indicating the peak value of one peak.

Furthermore, the fiber-reinforced resin molded article 1 may have a peak value of 5% or more for each of at least two peaks in the first histogram. In the fiber-reinforced resin molded article 1 of one aspect of the present disclosure, the half width of each of at least two peaks in the first histogram may be 0.5 to 1.6.

In the fiber-reinforced resin molded article 1 according to one aspect of the present disclosure, the difference between class values of different classes indicating 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 different classes indicating the peak values of the two peaks is 1.2.

(Circle equivalent diameter distribution)
The equivalent circle diameter distribution of the glass filaments 21 contained in the fiber-reinforced resin molded article 1 in this embodiment will be described below. Equivalent circle diameter distribution can be measured for a specific total number of a plurality of glass filaments in the same manner as the above-described technique used when measuring the aspect ratio distribution.

In the fiber-reinforced resin molded article 1 of the present 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. Sufficient mechanical properties and warp control properties cannot be obtained.

Furthermore, the fiber-reinforced resin molded body 1 is classified into (i) an equivalent circle diameter category of 6 μm or more and less than 13 μm (hereinafter referred to as a first equivalent circle diameter category B1) with respect to the specific total number of the plurality of glass filaments 21. 15 to 25% of the glass filament 21 having an equivalent circle diameter of 15 to 25%, and (ii) a circle classified into an equivalent circle diameter category of 13 μm or more and less than 15 μm (hereinafter referred to as a second equivalent circle diameter category B2) The glass filament 21 having an equivalent diameter is mixed in 55 to 65%, and (iii) the equivalent circle diameter is classified into the equivalent circle diameter category of 15 μm or more and 27 μm or less (hereinafter referred to as the third equivalent circle diameter category B3). It is preferable that the blending ratio of the glass filaments 21 is 15 to 25%. According to the above configuration, it is possible to easily obtain a fiber-reinforced resin molded article having both warp-suppressing properties and mechanical properties.

Furthermore, in the fiber-reinforced resin molding 1, the equivalent circle diameter distribution of the glass filaments 21 shows a unimodal histogram. This will be explained below with reference to FIG. FIG. 4 is a histogram showing the distribution of equivalent circle diameters of the glass filaments 21 contained in the fiber-reinforced resin molded article 1 of the present embodiment. In FIG. 4, the graph also shows the cumulative mixture ratio (cumulative relative frequency in the histogram) in each of the above-described first to third equivalent circle diameter divisions. Cumulative percentage values are shown on the right axis.

The histogram shown in FIG. 4 is a histogram showing the equivalent circle diameter distribution (second histogram ).

In the fiber-reinforced resin molding 1 of one embodiment of the present disclosure, the second histogram has a unimodal distribution. In other words, the fiber-reinforced resin molding 1 of one embodiment of the present disclosure has only one peak in the second histogram. The second histogram shown in FIG. 4 has only one peak whose center (peak position) is the class whose flatness ratio is greater than 13.0 μm and equal to or less than 13.25 μm. By having the above configuration, it is possible to easily obtain a fiber-reinforced resin molded article having both warp-suppressing properties and mechanical properties.

(fiber length)
The plurality of glass filaments 21 contained in the fiber-reinforced resin molded body 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, or 100 μm or more and 500 μm or less. , 300 μm or more and 400 μm or less.

In the fiber-reinforced resin molded article 1 of this embodiment, the average fiber length of the glass filaments 21 can be calculated as follows. First, the fiber-reinforced resin molded body 1 is heated in an incinerator at 650° C. to decompose the organic substances in the fiber-reinforced resin molded body 1, thereby obtaining the glass filaments 21 contained in the fiber-reinforced resin molded body 1. The obtained glass filaments 21 are transferred to a glass petri dish, and a solvent such as acetone is used to disperse the glass filaments 21 in the glass petri dish. Next, the fiber length of the glass filaments 21 in the glass petri dish was measured using an electron microscope. The fiber length was measured for 1000 or more glass filaments 21, and the average value was taken as the average fiber length.

(other ingredients)
The fiber-reinforced resin molding 1 in this embodiment may contain a coloring agent, a flame retardant, and the like, if necessary. By including these components, for example, the fiber-reinforced resin molding 1 can be colored in a desired color. Moreover, the fire resistance of the fiber-reinforced resin molded article 1 can be improved.

[4. Manufacturing method of fiber-reinforced resin molding]
A method for manufacturing the fiber-reinforced resin molding 1 in this embodiment will be described. The method for manufacturing the fiber-reinforced resin molded article 1 of the present embodiment includes a preparation step of preparing chopped strands, a pellet forming step, and an injection molding step.

In the 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 a specific method is not particularly limited. For example, chopped strands may be produced 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 (arrangement of holes) of the bushing through which the molten glass is drawn and various manufacturing conditions.

The chopped strand in one embodiment of the present invention includes a plurality of glass filaments 21, and the flatness ratio (major axis/minor axis) of the glass filaments 21 in the cross section is in the range of more than 1.0 and 7.0 or less. It has a flat cross-sectional shape. The chopped strands in the present embodiment are classified into a first flatness ratio category A1 of (i) greater than 2.8 and 4.6 or less with respect to a specific total number (N pieces) of the plurality of glass filaments 21. is 50 to 100%; 0 to 50%. The chopped strands in the present embodiment show the distribution of the flatness ratio with the horizontal axis as the flatness ratio, the vertical axis as the mixture ratio, and the class width as 0.2 for a specific total number (N pieces) of glass filaments 21. A histogram of 1 has at least two peaks.

Next, in the pellet forming step, the chopped strands and the thermoplastic resin are kneaded to form composite pellets. A polyamide resin, a polycarbonate resin, or the like can be used as the thermoplastic resin. Composite pellets formed in the pellet forming step are also included in the scope of the present invention. A composite pellet in one embodiment of the present invention includes a resin 10 , a plurality of glass fibers 20 , and glass filaments 21 dispersed from the glass fibers 20 . The glass fiber 20 includes a plurality of bundled glass filaments 21 having a flat cross-sectional shape. The glass filament 21 has a flatness ratio (major axis/minor axis) in a cross section in a range of more than 1.0 and 7.0 or less. The composite pellet in the present embodiment has a flatness ratio classified into a first flatness ratio category of (i) greater than 2.8 and 4.6 or less with respect to a specific total number (N pieces) of the plurality of glass filaments 21. (ii) having a flatness ratio classified into the second flatness ratio category of greater than 4.6 and 7.0 or less, the mixture ratio of the glass filaments 21 being 0 ~50%. The composite pellet in this embodiment shows the distribution of the flatness ratio with the horizontal axis as the flatness ratio, the vertical axis as the blending ratio, and the class width of 0.2 for a specific total number (N pieces) of the glass filaments 21. A histogram has at least two peaks.

The injection molding step is a step of performing injection molding using the composite pellets formed in the pellet forming step. The fiber-reinforced resin molding 1 is manufactured by the injection molding process.

[Additional notes]
The present invention is not limited to the above-described embodiments, and can be modified in various ways within the scope of the claims. It is included in the technical scope of the invention.

Examples of the fiber-reinforced resin molded article according to one aspect of the present invention will be described below, but the present invention is not limited to these examples.

Chopped strands containing glass fibers having an E-glass composition with adjusted aspect ratio distribution and the like and polyamide resin PA66 (manufactured by DuPont: Zytel 101l) were kneaded using a twin-screw kneading extruder. In this way, composite pellets of glass fiber and resin were produced.

Next, using the obtained composite pellet, injection molding is performed with an injection molding machine to prepare a test piece according to ASTM D638 (Type-1), ASTM D790, and ASTM D6110, and subjected to tensile strength test, bending strength test, It was used as a test piece for a Charpy impact strength test. A flat plate of 150×150×2.5 mm was produced using an injection molding machine as a test piece for measuring the warpage height.

Tensile strength, bending strength, Charpy impact strength, and warpage height were measured by the methods described below.

<Tensile strength>
Test pieces conforming to ASTM D638 (Type-1) using a precision universal testing machine (Shimadzu Corporation Autograph AG-X plus 50kN) under conditions conforming to ASTM D638 (Type-1). was performed and the tensile strength was measured.

<Bending strength>
A test piece conforming to ASTM D790 was tested under conditions conforming to ASTM D790 using a precision universal testing machine (manufactured by Shimadzu Corporation, Autograph AG-X plus 10 kN) to measure bending strength.

<Charpy impact strength>
A test piece conforming to ASTM D6110 was tested using an impact tester (UF impact tester manufactured by Ueshima Seisakusho Co., Ltd.) under conditions conforming to ASTM D6110 to measure the tensile strength.

<Warp height>
A flat plate of 150 mm × 150 mm × 2.5 mm is used as a test piece for warpage height, and when one end of the test piece is placed on a plane, the maximum value of the deformation distance from the plane is measured with a caliper. Satoshi.

(evaluation)
The obtained fiber-reinforced resin molded article was evaluated to have high mechanical properties when the tensile strength was 175 Mpa or more, the bending strength was 240 Mpa or more, and the Charpy impact strength was 10 kJ/m ² or more. When the warp height was 12 mm or less, it was evaluated that the warp suppressing property was high.

(Test results)
Fiber reinforced resin moldings of Examples 1 to 4 and Comparative Examples 1 to 6 were obtained. Table 1 shows the test results for each fiber-reinforced resin molded product. In Table 1, "the number of peaks (peak positions)" indicates the number of peaks and the peak positions in the first histogram showing the flatness ratio distribution.

As shown in Table 1, the fiber-reinforced resin molded articles of Examples 1 to 4 have an average flatness ratio of the glass filaments in the range of more than 1.0 and 7.0 or less, and are in the first flatness ratio category. The compounding ratio was 50 to 100%, and the compounding ratio of the second flatness ratio category was 0 to 50%. Also, the compounding ratio of the third flatness ratio category was 0 to 15%. And it was a flatness ratio distribution having two peaks. It can be seen that Examples 1 to 4 have both mechanical properties and warpage suppression properties.

On the other hand, the fiber-reinforced resin molded articles of Comparative Examples 1 to 6 did not satisfy the conditions of the present invention, and were insufficient in at least one of the mechanical properties and the warpage suppression properties.

1 fiber reinforced resin molding 10 resin 20 glass fiber 21 glass filament

Claims (16)

A fiber-reinforced resin molding containing a resin and a plurality of glass filaments,
The plurality of glass filaments have a flat cross-sectional shape in which the flatness ratio (major axis/minor axis) in the cross section is in the range of more than 1.0 and 7.0 or less,
(i) The mixing ratio of the glass filaments having a flatness ratio classified into the first flatness ratio category of more than 2.8 and 4.6 or less is 50 to 100% with respect to the specific total number of the plurality of glass filaments. and (ii) the blending ratio of the glass filaments having a flatness ratio classified into the second flatness ratio category of greater than 4.6 and 7.0 or less is 0 to 50%,
For the specific total number of glass filaments, the first histogram showing the distribution of the flatness ratio with the horizontal axis as the flatness ratio, the vertical axis as the blending ratio, and the class width of 0.2 has at least two peaks. Resin molding. 2. The fiber-reinforced resin molded article according to claim 1, wherein both of said two peaks in said first histogram have peak positions in a range of aspect ratio greater than 2.8. With respect to the specific total number of the plurality of glass filaments, the blending ratio of the glass filaments having a flatness ratio classified into the third flatness ratio category of more than 1.0 and 2.8 or less is 0 to 15%. The fiber-reinforced resin molded article according to claim 1 or 2, wherein The compounding ratio of the glass filaments having the aspect ratio classified into the third aspect ratio category is 0 to 10%, and the compounding ratio of the glass filaments having the aspect ratio classified into the first aspect ratio category is 60. 4. The fiber-reinforced resin molded article according to claim 3, wherein the compounding ratio of the glass filaments having a flatness ratio classified into the second flatness ratio category is 20 to 40%. The blending ratio of the glass filaments having the aspect ratio classified into the third aspect ratio category is 0 to 5%, and the blending ratio of the glass filaments having the aspect ratio classified into the first aspect ratio category is 65. 5. The fiber-reinforced resin molded article according to claim 3, wherein the compounding ratio of the glass filaments having a flatness ratio classified into the second flatness ratio category is 25 to 35%. The plurality of glass filaments have an equivalent circle diameter in a cross section of 6 to 27 μm,
(i) the blending ratio of the glass filaments having an equivalent circle diameter classified into the first equivalent circle diameter category of 6 μm or more and less than 13 μm is 15 to 25% with respect to the specific total number of the plurality of glass filaments; ii) 55 to 65% of the glass filament having a circle equivalent diameter classified into the second equivalent circle diameter category of 13 μm or more and less than 15 μm, (iii) the third equivalent circle diameter category of 15 μm or more and 27 μm or less. The fiber-reinforced resin molded article according to any one of claims 1 to 5, wherein the blending ratio of the glass filaments having an equivalent circle diameter classified as B is 15 to 25%. For the specific total number of glass filaments, the second histogram showing the distribution of the equivalent circle diameter with the horizontal axis as the circle equivalent diameter, the vertical axis as the blending ratio, and the class width of 0.25 μm is the unimodal distribution. The fiber-reinforced resin molded article according to claim 6. In the first histogram,
The difference between the maximum value and the minimum value of the compounding ratio in each class included in the first aspect ratio division is 5% or more,
The difference between the maximum value and the minimum value of the compounding ratio in each class included in the second aspect ratio division is 5% or more,
The fiber-reinforced resin according to any one of claims 1 to 7, wherein at least one of the first aspect ratio division and the second aspect ratio division includes a class showing a peak value of one peak. molding. The fiber-reinforced resin molded article according to any one of claims 1 to 8, wherein the peak value of the compounding ratio of each of said at least two peaks in said first histogram is 5% or more. The fiber-reinforced resin molded article according to any one of claims 1 to 9, wherein the half width of each of said at least two peaks in said first histogram is 0.5 to 1.6. The fiber reinforcement according to any one of claims 1 to 10, wherein the difference between the class values of the different classes indicating the peak values of the at least two peaks in the first histogram is 0.4 or more. Resin molding. Any one of claims 1 to 11, wherein in the first histogram, both the first flatness ratio division and the second flatness ratio division include a class indicating a peak value of at least one peak. The fiber-reinforced resin molded article according to Item 1. The fiber-reinforced resin molded article according to any one of claims 1 to 12, wherein the resin is an injection-moldable thermoplastic resin. A composite pellet containing a resin and a plurality of glass filaments,
The glass filament has 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 7.0 or less,
(i) The mixing ratio of the glass filaments having a flatness ratio classified into the first flatness ratio category of more than 2.8 and 4.6 or less is 50 to 100% with respect to the specific total number of the plurality of glass filaments. and (ii) the blending ratio of the glass filaments having a flatness ratio classified into the second flatness ratio category of greater than 4.6 and 7.0 or less is 0 to 50%,
For the specific total number of glass filaments, the first histogram showing the distribution of the flatness ratio with the horizontal axis as the flatness ratio, the vertical axis as the blending ratio, and the class width of 0.2 has at least two peaks. . A chopped strand containing a plurality of glass filaments,
The glass filament has 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 7.0 or less,
(i) The mixing ratio of the glass filaments having a flatness ratio classified into the first flatness ratio category of more than 2.8 and 4.6 or less is 50 to 100% with respect to the specific total number of the plurality of glass filaments. and (ii) the blending ratio of the glass filaments having a flatness ratio classified into the second flatness ratio category of greater than 4.6 and 7.0 or less is 0 to 50%,
For the specific total number of glass filaments, the first histogram showing the distribution of the flatness ratio with the horizontal axis as the flatness ratio, the vertical axis as the blending ratio, and the class width of 0.2 has at least two peaks. . A preparation step of preparing chopped strands according to claim 15;
a pellet forming 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.

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