JP2023039722A - Glass nonwoven fabric, glass fiber-reinforced plastic molded body, glass chopped strand, and production method of glass nonwoven fabric - Google Patents

Abstract

To realize a glass nonwoven fabric having high strength, and having practical productivity.SOLUTION: A glass nonwoven fabric (1) has a cross section of a flat shape, and contains a glass filament (10) that satisfies the following conditions (i), (ii), and (iii). (i) The average value of flatness ratios (major axis/minor axis) of the cross section is 1.5 or larger and 8.0 or smaller. (ii) The average value of circle equivalent diameters of the cross section is 5 μm or larger and 20 μm or smaller. (iii) The standard deviation of the circle equivalent diameter is 0.5 or larger and 4.0 or smaller.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a glass nonwoven fabric or the like containing glass filaments.

BACKGROUND ART In recent years, various studies have been made with the aim of further miniaturizing electrical insulating boards, printed wiring boards, etc., or improving mechanical properties thereof. For example, a glass nonwoven fabric is used as a reinforcing material for the substrate.

A glass nonwoven fabric containing flat glass fibers has better mechanical properties than a glass nonwoven fabric containing circular glass fibers. Therefore, even if the thickness is thin, it has relatively high strength.

Patent Literature 1 describes a glass nonwoven fabric that contains flat glass fibers and is densified without increasing the binder content. Further, Patent Document 2 describes a glass nonwoven fabric containing flat glass fibers and a binder with a binder content of 3 to 8% by weight.

JP-A-6-257042 JP 2004-100142 A

In response to the growing demand for further weight reduction and miniaturization of electronic device parts, further improvements in the strength and productivity of glass nonwoven fabrics are being demanded.

An object of one aspect of the present invention is to realize a glass nonwoven fabric having high strength and practical productivity.

In order to solve the above problems, a glass nonwoven fabric according to an aspect of the present invention has a flat cross section and contains glass filaments that satisfy the following conditions (1), (2) and (3). (1) The average value of the flatness ratio (major axis/minor axis) of the cross section is 1.5 or more and 8.0 or less; (2) The average value of the circle equivalent diameter of the cross section is 5 μm or more and 20 μm or less; The standard deviation in the equivalent circle diameter distribution is 0.5 or more and 4.0 or less.

Further, the glass chopped strand in one aspect of the present invention has a flat cross section and contains glass filaments satisfying the following conditions (1), (2) and (3): (1) the cross section of (2) The average value of the equivalent circle diameter of the cross section is 5 μm or more and 20 μm or less; (3) The standard in the distribution of the equivalent circle diameter The deviation is 0.5 or more and 4.0 or less.

Further, in the method for producing a glass nonwoven fabric according to one aspect of the present invention, a glass chopped strand having a flat cross section and containing glass filaments satisfying the following conditions (1), (2) and (3) is prepared. (1) the average value of the flatness ratio (major axis / minor axis) of the cross section is 1.5 or more and 8.0 or less; (2) the average value of the circle equivalent diameter of the cross section is 5 μm or more and 20 μm or less; (3) The standard deviation in the distribution of the circle equivalent diameter is 0.5 or more and 4.0 or less; a fiber opening step of immersing the glass chopped strands in white water and stirring, and making a glass nonwoven fabric using the white water. and a papermaking process.

ADVANTAGE OF THE INVENTION According to 1 aspect of this invention, the glass nonwoven fabric which has a practical productivity while having high intensity|strength is realizable.

It is an optical microscope photograph which partially expanded and imaged the glass nonwoven fabric in one Embodiment of this invention. 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 flatness ratio distribution of glass filaments contained in the glass nonwoven fabric in one embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing the configuration of a glass fiber reinforced plastic molded body in 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 equivalent circle diameter of several micrometers to several tens of micrometers. Next, a 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 filament fibers is called a glass strand, and a piece cut into 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 of 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, the end surface of the glass filament is usually observed without cutting the glass filament to form a cross section. At this time, 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 with 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.

The distribution of the flatness ratio means the frequency distribution. For example, the distribution of the flatness ratio of a plurality of glass filaments can be grasped by a histogram in which the horizontal axis is the flatness ratio and the vertical axis is the frequency (number) or relative frequency (blending ratio). be. 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 explaining the glass nonwoven fabric according to one aspect of the present invention, the following is an overview of the knowledge found by the present inventors.

A glass nonwoven fabric is generally produced by dispersing a plurality of glass fibers (chopped strands) in white water, followed by papermaking and drying. Glass fibers are dispersed (opened) into aggregates of glass filaments in white water. Thereafter, the glass filaments can aggregate in the white water over time. If the paper is made while the glass filaments are agglomerated, a glass nonwoven fabric with an unsuitable appearance as a product will be obtained. Therefore, the poorer the dispersibility (in other words, aggregation resistance) of the glass fibers in the white water, the lower the productivity of the glass nonwoven fabric.

The present inventors have investigated the shape (flatness ratio and circle equivalent diameter) of the chopped strands used in the production of the glass nonwoven fabric and the glass filaments contained in the glass nonwoven fabric, and the aggregation resistance of the chopped strands (plurality of glass fibers) in white water. , and the strength of the resulting glass nonwoven fabric. As a result, the inventors have found that by using glass filaments having a flat cross-sectional shape and setting the flatness ratio and circle equivalent diameter of the glass filaments within a predetermined range, it is possible to realize a glass nonwoven fabric having improved performance.

By setting the average value of the flatness ratio of the glass filaments contained in the glass nonwoven fabric and the chopped strands within an appropriate range, the aggregation of the glass filaments in the white water can be suppressed and the strength of the glass nonwoven fabric can be increased. Glass filaments having a circular cross-section tend to aggregate relatively easily in white water. Further, the glass nonwoven fabric is formed by interweaving a plurality of glass filaments, and the larger the adhesion area between the plurality of glass filaments, the higher the bonding strength. A glass nonwoven fabric containing glass filaments having a flattened cross section has a relatively high tensile strength because the bonding area between the glass filaments can be increased.

In addition, by setting the average value of the equivalent circle diameters of the glass filaments contained in the glass nonwoven fabric and the chopped strands within an appropriate range, it is possible to prevent the aggregation of the glass filaments in white water and increase the strength of the glass nonwoven fabric. can be done. For example, if the weight of chopped strands added to a certain amount of white water (that is, the weight of glass filaments) is constant, the following can be said. That is, when the equivalent circle diameter of the glass filaments is small, the number (number) of glass filaments contained in the white water increases compared to the case where glass filaments having a large equivalent circle diameter are added to the white water. As a result, the glass filaments become entangled relatively easily in white water, thereby shortening the flocculation start time. On the other hand, when the number (number) of glass filaments contained in the white water increases, the number of bonding points between the glass filaments in the glass nonwoven fabric increases, so the tensile strength of the glass nonwoven fabric becomes relatively high.

Furthermore, it was found that it is also important to keep the standard deviation in the distribution of equivalent circle diameters of the glass filaments contained in the glass nonwoven fabric and the chopped strands within an appropriate range. When the distribution of the equivalent circle diameters of the glass filaments contained in the nonwoven glass fabric and the chopped strands is wide (the standard deviation in the distribution is large), relatively thin glass filaments and relatively thick glass filaments are mixed, and in white water The aggregation start time tends to be shortened, and the tensile strength of the glass nonwoven fabric tends to decrease. This is because relatively thin glass filaments tend to get entangled in white water, and if relatively thick glass filaments are included in the glass nonwoven fabric, the number of adhesion points between the glass filaments decreases, resulting in a decrease in the tensile strength of the glass nonwoven fabric. Because it is easy.

The glass nonwoven fabric according to one aspect of the present invention has been conceived based on the above findings, and can be produced while ensuring anti-agglomeration in white water, and has high strength.

(Glass non-woven fabric)
FIG. 1 is an optical microscope photograph of a partially enlarged glass nonwoven fabric 1 according to the present embodiment. As shown in FIG. 1, the glass nonwoven fabric 1 is formed by intertwining a plurality of glass filaments 10 with each other. The glass nonwoven fabric 1 in this embodiment is mostly formed of glass filaments 10 . FIG. 1 mainly shows an image of the glass filament 10 because it is difficult to image a material having translucency to observation light (such as a secondary binder described below).

The glass nonwoven fabric 1 may have a secondary binder in addition to the glass filaments 10 and may have other additive components. The secondary binder may have a loss on ignition of 5% by mass or more and 30% by mass or less, and may be 10% by mass or more and 20% by mass or less. For example, an acrylic resin or an epoxy resin can be used as the secondary binder. Ignition loss can be measured according to JIS R 3420 (2013). The content of other additive components in the glass nonwoven fabric 1 may be 3% by mass or less, and may be 2% by mass or less. Other additive components include, for example, a processing agent (primary binder) contained in glass fibers. Although the above treatment agent dissolves in white water during the manufacturing process, it is possible that it may be mixed into the glass nonwoven fabric 1 to some extent.

(glass filament)
In the glass nonwoven fabric 1, the content of the glass filaments 10 is not particularly limited, but may be, for example, 70% by mass or more and 95% by mass or less, or 80% by mass or more and 90% by mass or less.

FIG. 2 is a cross-sectional view of the glass filament 10 taken 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 10, and L2 be the minor axis thereof. In this specification, the length of the longest line segment connecting two points on the outer edge in the cross section of the glass filament 10 is the "longest diameter of the glass filament 10", and The length of the longest line segment is defined as the "minor diameter of the glass filament 10" and used.

In addition, the cross-sectional shape of the glass filament 10 is not limited to an elliptical shape. The glass filament 10 has a flattened shape with a modified cross-section, and may have a flattened shape such as an oval, elliptical, or rounded rectangle, for example. The glass filament 10 preferably has an oblong flat shape.

The glass filaments 10 contained in the glass nonwoven fabric 1 in this embodiment satisfy all of the following conditions (1) to (3).

(1) The average value of the flatness ratio (major axis L1/minor axis L2) of the cross section is 1.5 or more and 8.0 or less;
(2) The average equivalent circle diameter of the cross section is 5 μm or more and 20 μm or less;
(3) The standard deviation of the equivalent circle diameter distribution is 0.5 or more and 4.0 or less.

Regarding the above (1), when the average value of the flatness ratio of the cross section of the glass filaments 10 contained in the glass nonwoven fabric 1 is less than 1.5, the adhesion area between the glass filaments 10 tends to be small, and the tensile strength is low. hard to get taller. On the other hand, if the average flatness ratio of the cross section of the glass filaments 10 is more than 8.0, the glass filaments 10 are likely to break, and the glass nonwoven fabric 1 cannot obtain sufficient tensile strength.

Regarding (2) above, if the average cross-sectional equivalent circle diameter of the glass filaments 10 contained in the glass nonwoven fabric 1 is less than 5 μm, the glass filaments 10 may break during the papermaking process. On the other hand, when the average value of the equivalent circle diameter of the cross section of the glass filaments 10 contained in the glass nonwoven fabric 1 exceeds 20 μm, the porosity of the glass nonwoven fabric 1 increases and the number of bonding points between the glass filaments 10 decreases. . Therefore, the tensile strength of the glass nonwoven fabric 1 is lowered.

Regarding (3) above, when the standard deviation in the distribution of the equivalent circle diameters of the cross sections of the glass filaments 10 contained in the glass nonwoven fabric 1 is less than 0.5, the glass filaments 10 having a more uniform cross-sectional shape are several hundred to Since thousands of fibers are bundled, the glass fibers are difficult to open in white water. On the other hand, if the standard deviation in the equivalent circle diameter distribution is greater than 4.0, there are too many relatively thin glass filaments 10 that tend to aggregate and relatively thick glass filaments 10 that lead to a decrease in strength. As a result, the aggregation start time is shortened, and the tensile strength of the glass nonwoven fabric 1 is lowered.

The glass nonwoven fabric 1 of the present embodiment has a high strength because the glass filaments 10 contained therein satisfy the above (1) to (3), and makes it difficult for the glass filaments to aggregate during papermaking in the manufacturing process (aggregation start time) and have practical productivity.

The composition of the glass filaments 10 is not particularly limited as long as it is possible to manufacture the glass nonwoven fabric 1 having high strength and practical productivity. not a thing The composition of the glass filament 10 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 glass filament 10 may have a minor axis L2 of 3 to 15 μm, or may be 5 to 12 μm in cross section. Further, the glass filament 10 may have a major axis L1 of 10 to 50 μm, or 15 to 30 μm, in the cross section.

(flatness ratio distribution)
The flatness ratio distribution of the glass filaments 10 contained in the glass nonwoven fabric 1 in this embodiment will be described below. The flatness ratio distribution of the glass filaments 10 contained in the glass nonwoven fabric 1 is substantially the same as the flatness ratio distribution of the glass filaments 10 contained in the chopped strands used in the manufacturing process of the glass nonwoven fabric 1 . Therefore, the chopped strand used in the manufacturing process of the glass nonwoven fabric 1 may be used for the measurement of the aspect ratio distribution described below.

First, the measurement of the flatness ratio distribution will be described. 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 10 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 10, a plurality of glass filaments 10 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 10 is observed with an electron microscope, and the major axis L1 and the minor axis L2 of the observed glass filament 10 are measured to calculate the flatness ratio. Then, by classifying each of the specific total number of glass filaments 10 for which the flatness ratio was calculated into a plurality of flatness ratio ranges, the compounding ratio in each flatness ratio range was quantified.

The glass nonwoven fabric 1 may have the following flatness ratio distribution of the glass filaments 10 measured as described above. That is, the ratio of the number of glass filaments classified into a certain flatness ratio category to the specific total number of the plurality of glass filaments 10 is defined as (i) a flatness ratio category of 1.5 or more and less than 3.0 ( Hereinafter, the total blending ratio of the glass filaments 10 having the flatness ratio classified into the first flatness ratio class A1) is 0 to 20%, and (ii) the flatness ratio is 3.0 or more and less than 5.0 The total blending ratio of the glass filaments 10 having a flatness ratio classified into the category (hereinafter referred to as a second flatness ratio category A2) is 30 to 70%, and (iii) 5.0 or more and 8.0 or less. The total compounding ratio of the glass filaments having a flatness ratio classified into the flatness ratio division (hereinafter referred to as a third flatness ratio division A3) is 30 to 60%. By setting the flatness ratio distribution of the glass filaments 10 as described above, the aggregation resistance of the glass filaments 10 in the white water in the papermaking process can be improved, and the strength of the glass nonwoven fabric 1 can be increased.

Furthermore, it is preferable that the glass nonwoven fabric 1 exhibits a histogram including a plurality of peaks in the flatness ratio distribution of the glass filaments 10 . 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 10 contained in the glass nonwoven fabric 1 of this embodiment.

The histogram shown in FIG. 3 is a histogram showing the flatness ratio distribution, created with the flatness ratio of the glass filaments 10 on the horizontal axis, the compounding ratio of the glass filaments 10 on the vertical axis, and the class width of 0.25. 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. As shown in FIG. 3, the glass nonwoven fabric 1 of the present embodiment has at least two peaks (also referred to as peaks) in the histogram showing the flatness ratio distribution.

Here, the glass filaments 10 with a relatively small flatness ratio tend to have a cross section close to a circle and have a relatively small circle equivalent diameter, and such glass filaments 10 aggregate in white water as described above. It's easy to do. Further, glass filaments 10 having a relatively large flatness ratio tend to have relatively large equivalent circle diameters, and such glass filaments 10 can reduce the strength of the glass nonwoven fabric 1 as described above. The glass nonwoven fabric 1 in one aspect of the present invention satisfies the conditions (1) to (3) described above for the glass filaments 10 contained therein, and furthermore, the flatness ratio of the cross section of the glass filaments 10 contained in the glass nonwoven fabric 1 The standard deviation in the distribution of may be 0.5 or more and 1.5 or less. According to the above configuration, the presence of the glass filaments 10 whose flatness ratio is much smaller than the average flatness ratio of the glass filaments 10 and the glass filaments 10 whose flatness ratio is much higher than the average flatness ratio is included in the glass nonwoven fabric 1. The ratio (number) can be reduced. Therefore, when the glass filaments 10 are dispersed in white water in the papermaking process, the glass filaments 10 have appropriate dispersibility and good aggregation resistance, and the strength of the glass nonwoven fabric 1 can be increased.

A large number of glass filaments 10 included in the chopped strands may have various flatness ratio distributions due to differences in manufacturing processes. For example, the aspect ratio distribution of the strand can be changed by adjusting conditions such as the hole shape (arrangement of holes) 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 peak-free histogram (eg, half-width greater than or equal to 2.0, or no half-width). That is, the glass nonwoven fabric 1 in one aspect of the present invention has improved performance as compared with the case where two or more chopped strands are simply mixed and dispersed in white water to make paper.

(Circle equivalent diameter distribution)
Regarding the circle-equivalent diameter distribution of the glass filaments 10 contained in the glass nonwoven fabric 1 in this embodiment, in the same manner as the above-described method used when measuring the aspect ratio distribution, a circle Equivalent size distributions can be measured.

Although illustration is omitted, the glass nonwoven fabric 1 may have a standard deviation of 0.5 or more and 4.0 or less in the distribution of equivalent circle diameters, and may exhibit a unimodal histogram.

Here, the distribution of the flatness ratio and the distribution of the equivalent circle diameter of the glass filaments 10 contained in the glass nonwoven fabric 1 are related to each other. In the process of manufacturing the strands used to manufacture the glass nonwoven fabric 1, there is generally a relationship that the wider the distribution of the flatness ratio of the glass filaments 10 contained in the chopped strands, the wider the distribution of the equivalent circle diameters of the glass filaments 10. Therefore, according to the fact that the glass filaments 10 contained in the glass nonwoven fabric 1 exhibit the above-described flatness ratio distribution (histogram having at least two peaks), the equivalent circle diameter of the glass filaments 10 contained in the glass nonwoven fabric 1 is The standard deviation in the distribution can be easily set to 0.5 or more and 4.0 or less.

(Manufacturing method of glass nonwoven fabric)
A method for manufacturing the glass nonwoven fabric 1 in this embodiment will be described. The manufacturing method of the glass nonwoven fabric 1 of this embodiment includes a preparation process, a fiber opening process, and a papermaking process.

The preparation step is a step of preparing chopped strands containing glass filaments that satisfy the above conditions (1) to (3). In the preparation step, raw materials are first weighed so as to obtain a desired glass composition, and the weighed glass raw materials are melted in a melting furnace. Next, the obtained molten glass is pulled out as a flat fiber from a platinum bushing. Next, several hundred to several thousand flat fibers having an equivalent circle diameter of 5 to 20 μm are coated with a treatment agent (glass fiber sizing agent) as a primary binder by a roll coater method. After that, the flat fiber is bundled and then wound around a paper tube placed on a rotating collet to form a wound body. Then, chopped strands are produced by performing cutting, drying, and the like as necessary. For example, the aspect ratio distribution of the chopped strands can be changed by adjusting the hole shape (hole arrangement) of the bushing through which the molten glass is drawn and various manufacturing conditions. Chopped strands prepared by the preparation process as described above also fall within the scope of the present invention.

The glass fibers, which are bundles of the glass filaments 10 contained in the chopped strands, have their surfaces coated with organic substances containing components such as aminosilane, urethane resin, acrylic resin, epoxy resin, olefin resin, lubricant, and antistatic agent. It may be coated with a sizing agent. The compounding ratio of the components of the sizing agent is determined according to the purpose of use. The mass ratio of the sizing agent to the total mass of the glass filaments 10 and the sizing agent is preferably 0.01 to 0.2% by mass.

The opening step is a step of immersing the chopped strands in white water and stirring them. The white water may be conventionally known water that is generally used for making paper from glass fibers or the like, and the specific components of the white water are not particularly limited. The specific components of white water do not greatly affect the tensile strength of the glass nonwoven fabric 1 .

The viscosity of white water can be measured by a known method, for example, according to JIS Z8803 (2011). The viscosity of white water may be, for example, 1-40 cP, and may be 1-20 cP. Also, the stirring speed after dipping the chopped strands in the white water may be 200 rpm to 500 rpm. For example, the amount of chopped strands added to 500 ml of white water may be 1 g to 100 g. The length of the chopped strands may be between 3 mm and 30 mm.

In the fiber opening step, the chopped strands introduced into the white water are opened to disperse the glass filaments 10 in the white water, making the white water cloudy. After that, when the glass filaments 10 agglomerate in the white water over time, visible agglomerates are produced. This aggregate has a size of, for example, about 3 mm in diameter.

The time from when the chopped strands are added to white water to when the aggregates are visually observed is specified as the aggregation start time. For example, the aggregation start time (aggregate generation timing) may be specified based on photographs or moving images taken at predetermined time intervals.

The paper-making step is a step of paper-making the glass nonwoven fabric 1 using the white water in which the glass filaments 10 are dispersed and which is in a state before aggregates are generated. In the papermaking process, a papermaking machine is used to make white water in which the glass filaments 10 are dispersed, and then a secondary binder is applied by a spray device or the like. After that, the glass nonwoven fabric 1 can be created by drying. As the papermaking process, a conventionally used wet papermaking method may be applied.

The secondary binder covering at least part of the surface of the glass nonwoven fabric 1 may have an ignition loss of 5% by mass or more and 30% by mass or less, and may be 10% by mass or more and 20% by mass or less. For example, an acrylic resin or an epoxy resin can be used as the secondary binder. Ignition loss can be measured according to JIS R 3420 (2013).

In the method for producing the glass nonwoven fabric 1 in the present embodiment, the chopped strands are immersed in white water having a viscosity of 20 cP and stirred at 200 rpm. Assuming that the tensile strength (N/100 mm) of the glass nonwoven fabric 1 is B, it is preferable to satisfy A×B≧50000.

(Glass fiber reinforced plastic molding)
FIG. 4 is a schematic diagram showing the configuration of the glass fiber reinforced plastic molding 50 in this embodiment. As shown in FIG. 4, the glass fiber reinforced plastic molding 50 has a pair of conductor layers 51 facing each other and a plurality of prepregs 52 .

The prepreg 52 is a member obtained by impregnating the glass nonwoven fabric 1 with a resin. A thermosetting resin or a thermoplastic resin can be used as the resin. Examples of thermoplastic resins that can be used include polyesters such as polycarbonate, polypropylene, polyamide, polyetherimide, and polyethylene terephthalate (PET). As the thermosetting resin, for example, epoxy resin, phenol resin, polyimide resin, and unsaturated polyester resin can be used.

The glass fiber reinforced plastic molding 50 contains one or more layers of glass nonwoven fabric, and can be produced, for example, as follows. First, a desired number of prepregs 52 are placed on one conductor layer 51 . Next, the other conductor layer 51 is placed on the opposite side of the laminated prepreg 52 from the one conductor layer 51 . Next, the pair of conductor layers 51 are pressed in the direction in which the prepregs 52 are placed. As a result, a glass fiber reinforced plastic molded body 50 in which a plurality of prepregs 52 (in other words, glass nonwoven fabric 1) are arranged between a pair of conductor layers 51 can be manufactured.

[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 glass nonwoven fabric according to one aspect of the present invention will be described below, but the present invention is not limited to these examples.

First, as shown in Table 1 below, chopped strands having a length of 13 mm containing glass fibers having an E-glass composition with an adjusted aspect ratio distribution and the like were dispersed in white water, and then subjected to Examples 1 to 7 and 1 to 7 using a paper machine. Glass nonwoven fabrics of Comparative Examples 1 to 4 were produced.

The tensile strength and cohesion initiation time of the produced glass nonwoven fabric were measured by the following measurement methods.

<Tensile strength>
The tensile strength was measured according to JIS R-3420 74 using a precision universal testing machine (Autograph AGS-X 10 kN, manufactured by Shimadzu Corporation).

<aggregation start time>
A beaker with an inner diameter of 110 mm containing 1000 mL of an aqueous solution of sodium polyacrylate adjusted to a viscosity of 20 cP at 25° C. was prepared. Next, two blades with a rotation diameter of 75 mm, a height of 30 mm, and a thickness of 3 mm were arranged at a position 10 mm from the bottom of the beaker, and the two blades were rotated at 200 rpm, and the length was lowered into the sodium polyacrylate aqueous solution. 3 g of chopped strands cut to 13 mm were added. After the chopped strands were opened, the time required for the glass filaments to aggregate was measured. In addition, it was determined visually whether it aggregated.

(evaluation)
In the example of the glass nonwoven fabric according to one aspect of the present invention, the obtained glass nonwoven fabric was evaluated to have high strength when the tensile strength was 196 N/100 mm or more. In addition, when the aggregation start time was 150 minutes or more, it was evaluated as having good aggregation resistance, that is, having practical productivity.

(Test results)
Table 1 shows the data of the glass filaments contained in the glass nonwoven fabrics of Examples 1 to 7 and Comparative Examples 1 to 4 and the test results of the above tests. In Table 1, "the number of peaks in the aspect ratio distribution" indicates the number of peaks in the histogram indicating the aspect ratio distribution.

As shown in Table 1, the glass nonwoven fabrics of Examples 1 to 7, which satisfy all the conditions (1) to (3) of the present invention, had high strength and practical productivity.

On the other hand, the glass nonwoven fabrics of Comparative Examples 1 to 4 did not satisfy any of the conditions (1) to (3) of the present invention, and at least one of tensile strength and aggregation resistance was insufficient. .

1 glass nonwoven fabric 10 glass filament

Claims (7)

A glass nonwoven fabric having a flat cross section and containing glass filaments satisfying the following conditions (1), (2) and (3):
(1) The average value of the flatness ratio (major axis / minor axis) of the cross section is 1.5 or more and 8.0 or less;
(2) The average equivalent circle diameter of the cross section is 5 μm or more and 20 μm or less;
(3) The standard deviation of the equivalent circle diameter distribution is 0.5 or more and 4.0 or less. The ratio of the number of glass filaments classified into a certain flatness ratio range to the specific total number of the plurality of glass filaments is defined as a blending ratio,
(i) the total blending ratio of the glass filaments having a flatness ratio classified into the first flatness ratio category of 1.5 or more and less than 3.0 is 0 to 20%, (ii) 3.0 or more and 5.0 The total blending ratio of the glass filaments having an aspect ratio of less than 30 to 70%, (iii) classified into the third aspect ratio category of 5.0 or more and 8.0 or less The total blending ratio of the glass filaments having a flatness ratio of 30 to 60%,
2. The histogram according to claim 1, wherein, for the plurality of glass filaments, the 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 0.25 has at least two peaks. glass non-woven fabric. Further comprising a secondary binder covering at least part of the surface of the glass nonwoven fabric,
3. The glass nonwoven fabric according to claim 1, wherein the secondary binder has an ignition loss of 5 to 30% by mass. The glass nonwoven fabric according to any one of claims 1 to 3, wherein the standard deviation in the distribution of the aspect ratio is 0.5 or more and 1.5 or less. A glass fiber reinforced plastic molded article containing one or more layers of the glass nonwoven fabric according to any one of claims 1 to 4. A glass chopped strand having a flat cross section and containing glass filaments satisfying the following conditions (1), (2) and (3):
(1) The average value of the flatness ratio (major axis / minor axis) of the cross section is 1.5 or more and 8.0 or less;
(2) The average equivalent circle diameter of the cross section is 5 μm or more and 20 μm or less;
(3) The standard deviation of the equivalent circle diameter distribution is 0.5 or more and 4.0 or less. a preparation step of preparing a glass chopped strand having a flat cross section and containing glass filaments satisfying the following conditions (1), (2) and (3);
(1) The average value of the flatness ratio (major axis / minor axis) of the cross section is 1.5 or more and 8.0 or less;
(2) The average equivalent circle diameter of the cross section is 5 μm or more and 20 μm or less;
(3) the standard deviation in the equivalent circle diameter distribution is 0.5 or more and 4.0 or less;
A fiber opening step of immersing and stirring the glass chopped strands in white water;
A method for producing a glass nonwoven fabric, comprising a papermaking step of making a glass nonwoven fabric using the white water.

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