Glass chopped strand mat and manufacturing method thereof

Abstract

The invention provides a glass chopped strand mat with excellent mechanical strength. The glass chopped strand mat is formed by bonding a plurality of strands of glass chopped strands by using a binder, and the standard deviation of the normal distribution of the number of the glass chopped strands is 4 or less.

Description

Technical Field

[0001] This invention relates to chopped glass strand mat and a method for manufacturing the chopped glass strand mat. Background Technology

[0002] Glass chopped strand mat is a reinforcing material made by bonding multiple strands of chopped glass filaments together and forming them into a felt-like structure. It is known to be lightweight and possess high mechanical strength. Such glass chopped strand mats are widely used as reinforcing materials in glass fiber reinforced plastics (GFRP), automotive molding headliner materials, and other applications.

[0003] As a method for manufacturing glass chopped strand mat, there is a known method which involves coating a bundle agent on the surface of multiple strands of glass fibers, cutting the bundled glass filaments to a specified length to prepare multiple strands of glass chopped strands, stacking them uniformly and randomly into a sheet, then spreading an adhesive and water onto the resulting sheet-like stack, heating and melting the adhesive, then pressing the sheet-like stack into a shape, and finally cooling and solidifying it (e.g., Patent Document 1).

[0004] Existing technical documents Patent documents Patent Document 1: International Publication No. 2017 / 068872 Summary of the Invention

[0005] The problem that the invention aims to solve In the production of chopped glass filaments, rovings made by bundling multiple strands of glass filaments are prepared and then cut to specified lengths to produce chopped glass filaments. However, the mechanical strength of chopped glass filament mats made from such filaments is sometimes insufficient. Therefore, in applications such as automotive molding headliner materials, there is a need for chopped glass filament mats with high mechanical strength, particularly methods to improve mechanical strength without changing the weight per unit area.

[0006] The purpose of this invention is to provide a glass chopped strand mat with excellent mechanical strength and a method for manufacturing the glass chopped strand mat.

[0007] Technical solutions for solving the problem Various methods for manufacturing glass chopped strand mat, which solve the above-mentioned problems, are described.

[0008] Method 1 of the present invention relates to a glass chopped strand mat, characterized in that the glass chopped strand mat is formed by bonding multiple strands of glass chopped strands together with an adhesive, wherein the standard deviation of the normal distribution of the number of strands of the glass chopped strands is less than 4.

[0009] The glass chopped strand mat of method 2 is preferably based on method 1, wherein the number of strands of the glass chopped strands is 6 tex or more and 20 tex or less.

[0010] The glass chopped strand mat of method 3 is preferably based on method 1 or method 2, wherein the length of the glass chopped strand is more than 20 mm and less than 150 mm.

[0011] The glass chopped strand mat of method 4 is preferably based on any one of methods 1 to 3, wherein the unit area mass of the glass chopped strand mat is 40 g / m². 2 Above and 200g / m 2 the following.

[0012] Embodiment 5 of the present invention relates to a method for manufacturing chopped glass filaments, which is used to manufacture chopped glass filament mats according to any one of Embodiments 1 to 4. The manufacturing method is characterized by comprising: a step of preparing a roving formed by bundling multiple strands of glass filaments; a step of obtaining chopped glass filaments by cutting the roving to a predetermined length; a step of dispersing and stacking the chopped glass filaments to obtain a stacked sheet of chopped glass filaments; and a step of distributing an adhesive to the stacked sheet of chopped glass filaments and pressing it into shape using rollers, wherein the bundling rate of the roving is 50% or more.

[0013] Invention Effects According to the present invention, a glass chopped strand mat with excellent mechanical strength and a method for manufacturing the glass chopped strand mat can be provided. Attached Figure Description

[0014] Figure 1 This is a graph representing an example of the normal distribution of the number of glass chopped filaments constituting the glass chopped filament mat.

[0015] Figure 2 This is a schematic diagram illustrating an example of a roving manufacturing apparatus used in the manufacture of glass chopped strand mat according to one embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram illustrating an example of an apparatus for manufacturing the glass chopped strand mat of the present invention. Detailed Implementation

[0017] The preferred embodiments are described below. However, these embodiments are merely examples, and the present invention is not limited to them. Furthermore, in the various figures, components having substantially the same function are sometimes labeled with the same symbols.

[0018] (Choped glass mat) The glass chopped strand mat of the present invention (hereinafter sometimes referred to as "glass chopped strand mat" or "mat") is a glass fiber sheet formed by bonding multiple strands of glass chopped strands together using an adhesive. In the glass chopped strand mat, the sheet-like accumulation of multiple strands of glass chopped strands is bonded together by an adhesive.

[0019] In the glass chopped strand mat of the present invention, the standard deviation of the normal distribution of the number of glass chopped strands is 4 or less. Therefore, the glass chopped strand mat of the present invention exhibits excellent mechanical strength. (Refer to the following...) Figure 1 This needs to be explained.

[0020] Figure 1 This is a graph representing an example of the normal distribution of the number of glass chopped filaments constituting the glass chopped filament mat. Figure 1 The solid line represents the curve of the chopped glass filament mat of the present invention. Furthermore, Figure 1 The dashed line represents the curve of the comparative example, chopped glass filament mat.

[0021] Furthermore, when determining the normal distribution of the number of strands of the glass chopped strands constituting the glass chopped strand mat, for example, the glass chopped strand mat is decomposed and the binder is removed by burning, and 500 strands of glass chopped strands are randomly selected from the obtained glass chopped strands. Then, the number of strands of the selected 500 strands of glass chopped strands is determined, and their mean and standard deviation are obtained. Then, by substituting the above mean into μ and the above standard deviation into σ in the following formula (1), a normal distribution curve can be obtained. In addition, the count of glass chopped strands can be determined according to "7.1 count" of JIS R3420 (2013).

[0022] like Figure 1 As shown, in one example of the glass chopped strand mat of the present invention, the peak height and peak width of the normal distribution of the number of glass chopped strands are relatively high. On the other hand, in the glass chopped strand mat of the comparative example, the peak height and peak width of the normal distribution of the number of glass chopped strands are relatively low.

[0023] according to Figure 1 It is clear that in the glass chopped strand mat of the present invention, the peak height and peak width of the normal distribution of the number of glass chopped strands are relatively high, thus the dispersion of the number of glass chopped strands is small. In particular, because the glass chopped strand mat of the present invention is composed of glass chopped strands with a standard deviation of less than 4 in the normal distribution of the number of glass chopped strands and a particularly small dispersion of the number of glass chopped strands, its mechanical strength can be effectively improved without changing the unit area mass of the glass chopped strand mat (felting). Furthermore, the reason for this can be attributed to the following.

[0024] When the dispersion of the number of chopped glass filaments is small, the number of strands of chopped glass filaments is greater than that of a mat of the same unit area mass. Since a higher number of strands of chopped glass filaments allows for a denser arrangement of the filaments, there are more joints between the filaments, thus increasing the mechanical strength of the glass filament mat. Furthermore, in this case, it is easier to obtain a glass filament mat with the required mechanical strength even with a relatively small amount of adhesive.

[0025] In this invention, the standard deviation of the normal distribution of the number of strands of the glass chopped filaments is preferably 0.5 or more, more preferably 0.75 or more, further preferably 1.0 or more, and preferably 4.0 or less, more preferably 3.5 or less, further preferably 3.0 or less, particularly preferably 2.5 or less, and most preferably 2.0 or less.

[0026] When the standard deviation of the normal distribution of the number of chopped glass filaments is above the aforementioned lower limit, the productivity of chopped glass filaments can be further improved. Furthermore, when the standard deviation of the normal distribution of the number of chopped glass filaments is below the aforementioned upper limit, the dispersion of the number of chopped glass filaments can be further reduced, and the mechanical strength of the chopped glass filament mat can be further improved.

[0027] The standard deviation of the normal distribution of the number of strands of chopped glass filaments can be obtained, for example, based on 500 strands of chopped glass filaments. Furthermore, the standard deviation of the normal distribution of the number of strands of chopped glass filaments is preferably obtained by extracting chopped glass filaments from the chopped glass filament mat using the method described above.

[0028] In this invention, the number of strands (average number of strands) of the glass chopped filaments is preferably 6 tex or more, more preferably 8 tex or more, even more preferably 10 tex or more, and preferably 20 tex or less, more preferably 17 tex or less, and even more preferably 14 tex or less.

[0029] When the count of chopped glass filaments is above the aforementioned lower limit, the productivity of manufacturing chopped glass filament mat can be further improved. Furthermore, when the count of chopped glass filaments is below the aforementioned upper limit, compared to mat of the same unit area mass, the increased number of strands allows for a denser arrangement, further improving the mechanical strength of the chopped glass filament mat.

[0030] Furthermore, the count of the chopped glass strands can be obtained based on, for example, the average count of 500 chopped glass strands. Moreover, the average count of the chopped glass strands is preferably obtained by extracting chopped glass strands from the chopped glass strand mat using the method described above.

[0031] In this invention, the length of the chopped glass filament is preferably 20 mm or more, more preferably 30 mm or more, even more preferably 40 mm or more, and preferably 150 mm or less, more preferably 120 mm or less, and even more preferably 90 mm or less.

[0032] When the length of the chopped glass filaments is above the aforementioned lower limit, the mechanical strength of the chopped glass filament mat can be further improved. Furthermore, when the length of the chopped glass filaments is below the aforementioned upper limit, the chopped glass filaments can be configured to be more evenly distributed within the chopped glass filament mat, further improving the mechanical strength of the mat.

[0033] In this invention, the preferred unit area mass of the chopped glass strand mat is 40 g / m². 2 The above, and more preferably 50g / m 2 The above, and more preferably, is 60g / m 2 The above, and preferably 200g / m 2 The following, or more preferably, is 180g / m 2 The following, and more preferably, is 160g / m 2 the following.

[0034] When the unit area mass of chopped glass strand mat is above the aforementioned lower limit, the mechanical strength of the chopped glass strand mat can be further improved. Furthermore, when the unit area mass of the chopped glass strand mat is below the aforementioned upper limit, the chopped glass strand mat can be further reduced in weight.

[0035] In addition, in this specification, the unit area mass of chopped glass strand mat can be determined according to "7.2 Mass of fabrics and felts" of JIS R3420 (2013).

[0036] In this invention, the thickness of the chopped glass strand mat is preferably 0.01 mm or more, more preferably 0.02 mm or more, even more preferably 0.04 mm or more, and preferably 1.0 mm or less, more preferably 0.8 mm or less, even more preferably 0.6 mm or less.

[0037] When the thickness of the chopped glass strand mat is above the lower limit mentioned above, the mechanical strength of the chopped glass strand mat can be further improved. In addition, when the thickness of the chopped glass strand mat is below the upper limit mentioned above, the chopped glass strand mat can be made thinner (or lighter).

[0038] The materials used to make up the glass chopped strand mat include, for example, E-glass, S-glass, T-glass, A-glass, C-glass, D-glass, and H-glass.

[0039] The adhesive used to form the chopped strand mat can be made of resins such as polyester, polypropylene, vinyl acetate, acrylic, and epoxy. Polyester resin is preferred as the adhesive, and powdered unsaturated polyester resin is even more preferable. This allows for easier melting and cooling curing of the adhesive.

[0040] In the glass chopped strand mat of the present invention, the amount of adhesive attached, by mass ratio, is preferably 1% or more, more preferably 3% or more, further preferably 5% or more, and preferably 20% or less, more preferably 17% or less.

[0041] When the amount of adhesive adhering to the chopped glass filament mat is above the aforementioned lower limit, the mechanical strength of the chopped glass filament mat can be further improved. Furthermore, when the amount of adhesive adhering to the chopped glass filament mat is below the aforementioned upper limit, the thickness of the chopped glass filament mat can be more uniform, and the flexibility of the chopped glass filament mat can be improved. Moreover, when the amount of adhesive adhering to the chopped glass filament mat is below the aforementioned upper limit, the amount of adhesive used is reduced, thereby lowering manufacturing costs.

[0042] In addition, in this specification, the amount of adhesive attached to the glass chopped strand mat is the loss on ignition measured in accordance with "7.3 Moisture content and loss on ignition" of JIS R3420 (2013).

[0043] Because of the excellent mechanical strength of the glass chopped strand mat of the present invention, it is suitable for use in fiber-reinforced molded composite materials, and is particularly suitable for use as a reinforcing material for automotive molding headliner materials, etc.

[0044] (Manufacturing method of chopped glass strand mat) The manufacturing method of the glass chopped strand mat of the present invention includes: a step of preparing a roving made of multiple strands of glass filaments bundled together (step 1); a step of obtaining glass chopped strands by cutting the roving into a specified length (step 2); a step of dispersing and stacking the glass chopped strands to obtain a glass chopped strand stack sheet (step 3); and a step of distributing an adhesive to the glass chopped strand stack sheet and pressing it into shape by a pressure roller (step 4).

[0045] The following is an example of process 1 to process 4.

[0046] Process 1: Figure 2 This is a schematic diagram illustrating an example of a roving manufacturing apparatus used in the manufacture of glass chopped strand mat according to one embodiment of the present invention. In step 1, using... Figure 2 The roving manufacturing apparatus 1 shown prepares roving.

[0047] In step 1, the glass raw material is first melted in a glass melting furnace to form molten glass. After the molten glass becomes homogeneous, it is pulled out from a heat-resistant nozzle attached to a stencil 2. Then, the pulled-out molten glass is cooled to form multi-strand glass fibers 3 (monofibers). Alternatively, a platinum stencil can be used as the stencil 2, for example.

[0048] The composition of glass fiber 3 is not particularly limited; for example, E glass, S glass, T glass, A glass, C glass, D glass, H glass, etc., can be used. Among them, E glass is preferred. E glass is inexpensive and can further improve the mechanical strength of chopped glass strand mat.

[0049] The number of strands of glass fiber 3 is not particularly limited, but is preferably 500 strands or more, more preferably 1,000 strands or more, and preferably 10,000 strands or less, more preferably 8,000 strands or less. When the number of strands of glass fiber 3 is above the aforementioned lower limit, the productivity of the manufactured roving can be further improved. In addition, when the number of strands of glass fiber 3 is below the aforementioned upper limit, it is easier to make the length of each glass fiber 3 uniform.

[0050] Next, a bundler is applied to the surface of the obtained multi-strand glass fibers 3 using a bundler coating mechanism 4. With the bundler uniformly coated on the surface of the multi-strand glass fibers 3, the multi-strand glass fibers 3 are aligned and bundled. The multi-strand glass fibers 3 can be aligned and bundled using a bundler member 5. This forms a glass filament 6.

[0051] In addition, although Figure 2 For the sake of illustration, only one glass filament 6 is shown, but in the bundling member 5, multiple glass filaments 6 are bundled together. For example, when using 5000 glass fibers 3, each 500 glass fibers 3 can be aligned to form 10 glass filaments 6.

[0052] The number of strands in the glass filament 6 formed by splitting is not particularly limited, but is preferably 2 or more, more preferably 3 or more, and preferably 25 or less, more preferably 20 or less. When the number of strands in the glass filament 6 formed by splitting is within the above range, the productivity of roving can be further improved.

[0053] As a bundler, it may contain thermoplastic resins such as polypropylene resin, nylon resin, polyvinyl acetate, or polyphenylene sulfide resin. In addition, the bundler may also contain thermosetting resins such as polyester (unsaturated polyester) resin, epoxy resin, or polyurethane resin. The bundler may also contain lubricants, nonionic surfactants, or antistatic agents. The proportions of these components can be appropriately set as needed.

[0054] Next, while the multi-strand glass filaments 6 are being guided laterally by the wire guide 7, the coil is wound up with the jacket 8 to prepare a roll 9 of roving from which the multi-strand glass filaments 6 are bundled together.

[0055] There are no particular limitations on the winding device 7; for example, the winding device shown in Figure 8 of Japanese Patent Application Publication No. 2021-147208 can be used. In addition, in Japanese Patent Application Publication No. 2021-147208, the glass filament S, which is divided into four strands, is wound on a collet while being guided laterally by the winding device.

[0056] When winding up the glass filament 6, for example, a collet 8 with a diameter of 100mm to 500mm can be used.

[0057] Next, the tufting agent is heated and dried to evaporate the moisture, thereby forming a film on the surface of the glass fiber 3. As a method of heating and drying, hot air drying or dielectric drying can be used, for example. Heating and drying can be carried out at a temperature range of 100°C to 150°C for 1 hour to 24 hours. This yields a dried roving cake (hereinafter sometimes simply referred to as "cream"). The thickness of the dried roving cake in a roll is, for example, 5 mm to 500 mm.

[0058] Furthermore, hot air drying is preferred for heat drying. In this case, the glass filament 6 can be heated and dried more evenly from the beginning to the end of the roll. Hot air drying also makes it easier to maintain the bundler within a certain temperature range. Alternatively, hot air drying and dielectric drying can be used together.

[0059] The roving prepared in step 1 has a splitting rate of 50% or higher. The splitting rate refers to the proportion of glass filaments 6 that are not bonded to other glass filaments 6 when the roving is cut into 2.5cm lengths at any 100 points. Therefore, it can be used as an indicator of the number of bonding points between the glass filaments 6 constituting the glass filament bundle; a higher splitting rate indicates fewer bonding points between the glass filaments 6. Therefore, by ensuring a splitting rate of 50% or higher for the roving, the dispersion of the number of strands in the chopped glass filaments described later can be reduced.

[0060] The roving prepared in step 1 has a splitting rate of 60% or more, more preferably 65% ​​or more, even more preferably 70% or more, and preferably 99% or less, more preferably 98% or less.

[0061] When the splitting ratio of the roving prepared in step 1 is above the aforementioned lower limit, the dispersion of the count of the glass chopped filaments described later can be further reduced. When the splitting ratio of the roving prepared in step 1 is below the aforementioned upper limit, the operability of unwinding the split glass filaments 6 from the roving can be further improved.

[0062] In addition, the splitting ratio of the roving can be changed, for example, by altering... Figure 2 Adjust the distances A, B, and C shown.

[0063] Distance A refers to the distance in the height direction between the center of the bundling member 5 and the center of the collet 8. When distance A is too small, the tension applied to the glass filaments 6 increases, making it easier for the glass filaments 6 to bond together, and reducing the splitting rate of the roving. When distance A is too large, the tension applied to the glass filaments 6 decreases, which may sometimes lead to a poorer shape of the yarn cake or a poorer unwinding of the roving from the yarn cake. Taking these aspects into consideration, distance A can be set, for example, to be between 500 mm and 3000 mm.

[0064] Distance B refers to the horizontal distance between the junction of the carbon roller 4a of the slugging agent coating mechanism 4 and the glass fiber 3, and the center of the slugging member 5. When distance B is too small, the tension applied to the glass filament 6 decreases, which may sometimes lead to a poorer shape of the fiber cake or a decrease in the unwinding ability of the roving from the fiber cake. Conversely, when distance B is too large, the tension applied to the glass filament 6 increases, making it easier for the glass filaments 6 to bond together, and reducing the roving splitting rate. Taking these factors into consideration, distance B can be set, for example, to be between 50 mm and 200 mm.

[0065] Distance C refers to the horizontal distance between the surface of the roll 9 closest to the guide wire 7 and the part of the shaft 7a furthest from the guide wire 7. Furthermore, when the glass filament 6 begins to be wound, the distance is not the surface of the roll 9 closest to the guide wire 7, but rather the horizontal distance between the surface of the collet 8 closest to the guide wire 7 and the part of the shaft 7a furthest from the guide wire 7.

[0066] When the distance C is too small, the tension applied to the glass filaments 6 increases, making it easier for the glass filaments 6 to bond together, and reducing the roving splitting rate. Conversely, when the distance C is too large, the tension applied to the glass filaments 6 decreases, which may sometimes lead to a poorer shape of the yarn cake or a poorer unwinding of the roving from the yarn cake. Taking these factors into consideration, the distance C can be set, for example, to be between 10 mm and 200 mm.

[0067] Process 2 to Process 4: Figure 3 This is a schematic diagram illustrating an example of an apparatus for manufacturing the glass chopped strand mat of the present invention.

[0068] like Figure 3As shown, the roving 10 is unwound from the inner layer of the yarn cake obtained in step 1 and fed into a plurality of cutters 12 mounted on the top of the chamber 11. This cuts the glass filament constituting the roving 10 to a predetermined length, resulting in chopped glass filament 10A. Each cutter 12 consists of a cutting roller 12a and a rubber roller 12b. In each cutter 12, the glass filament is cut by feeding the roving 10 between the relatively rotating cutting roller 12a and the rubber roller 12b.

[0069] Next, the chopped glass filaments 10A are evenly distributed on the first conveyor belt 13 located at the bottom of the chamber 11 and stacked into sheets. The stacked sheets of chopped glass filaments 10A are then conveyed out of the chamber 11 to the subsequent second conveyor belt 14.

[0070] Next, the binder is evenly distributed onto the glass chopped strands 10A moving on the second conveyor belt 14 using the distributor 15, and then conveyed to the subsequent third conveyor belt 16. The sheet-like accumulation of glass chopped strands 10A with the binder distributed is then transferred to the heating furnace 17 for heating, thereby softening and melting the binder.

[0071] Next, the sheet-like accumulation of chopped glass filaments 10A is moved to the outside of the heating furnace 17, where it is cooled and rolled between the water-cooled rollers 18 of the cooling mill. This solidifies the molten binder, resulting in chopped glass filament mat 19. Furthermore, the chopped glass filament mat 19 can be wound up using a winding machine 20 and then drawn out for use.

[0072] The adhesive used to bond the chopped glass filaments 10A is not particularly limited, and resins such as polyester, polypropylene, vinyl acetate, acrylic, and epoxy can be used. Among these, polyester resin is preferred as the adhesive, and powdered unsaturated polyester resin is more preferably used. In this case, it is easier to achieve melting and cooling curing of the adhesive.

[0073] There are no particular limitations on the form of the adhesive; for example, it can be in the form of powder, liquid, fiber, sheet, or film.

[0074] In the manufacturing method of the glass chopped strand mat of the present invention, the roving produced in step 1 has a splitting rate of 50% or more, which reduces the dispersion of the count of the glass chopped strands and makes the standard deviation of the normal distribution of the count of the glass chopped strands less than 4. Therefore, the glass chopped strand mat obtained by the manufacturing method of the present invention has excellent mechanical strength.

[0075] The present invention will now be described in more detail based on specific embodiments. The present invention is not limited to any of the following embodiments, and can be implemented with appropriate modifications without altering its spirit.

[0076] (Example 1) use Figure 2 The roving manufacturing apparatus 1 shown manufactures roving. Specifically, molten glass composed of E-glass is first drawn from the spinneret 2 to obtain 1000 strands of glass fiber 3. Next, a wicking agent is applied to the surface of the obtained glass fiber 3 using a wicking agent coating mechanism 4, adjusting the amount of loss on ignition to 0.50% by mass. The glass fiber 3 is then bundled using a wicking member 5 to obtain glass filament 6. Furthermore, in the wicking member 5, the 1000 strands of glass fiber 3 are separated into filaments, with 100 strands combined to form 10 strands of glass filament 6.

[0077] Next, while the 10 strands of glass filament 6 are being guided laterally using a wire guide 7, they are wound up using a 300mm diameter collet 8 to form a roll 9 of roving composed of the glass filament 6. The roll 9 is then dried in a hot air drying oven at 150°C for 600 minutes to obtain a dried roving cake. The thickness of the dried roving cake is 45mm.

[0078] Furthermore, when manufacturing the roving package, the vertical distance A between the center of the bundling member 5 and the center of the collet 8 is set to 500 mm. The horizontal distance B between the contact point of the carbon roller 4a of the roving agent coating mechanism 4 with the glass fiber 3 and the center of the bundling member 5 is set to 100 mm. The horizontal distance C between the surface of the package 9 closest to the guide wire 7 and the part of the shaft 7a furthest from the guide wire 7 is set to 100 mm.

[0079] Next, as Figure 3 As shown, the roving 10 is unwound from the inner layer of the dried yarn cake and fed into a plurality of cutters 12 mounted on the top of the chamber 11, where it is cut to a specified length. Each cutter 12 consists of a cutting roller 12a and a rubber roller 12b, which cut the roving 10 by feeding it between the relatively rotating cutting roller 12a and the rubber roller 12b.

[0080] A first conveyor belt 13 is arranged at the bottom of the chamber 11. Glass chopped filaments 10A cut to a length of 50 mm are evenly distributed on the first conveyor belt 13, piled up into sheets, and then conveyed out of the chamber 11 to the subsequent second conveyor belt 14.

[0081] The adhesive polyester resin is evenly distributed onto the glass chopped strands 10A moving on the second conveyor belt 14 using a distributor 15, achieving an adhesion amount of 15.0% by mass, and then conveyed to the subsequent third conveyor belt 16. A heating furnace 17 is located midway along the third conveyor belt 16, where the sheet-like accumulation of the glass chopped strands 10A with the distributed polyester resin is moved to the heating furnace 17 and heated at 260°C, thereby softening and melting the polyester resin.

[0082] Next, the sheet-like accumulation of the chopped glass filaments 10A is moved to the outside of the heating furnace 17, and then cooled and rolled between water-cooled rollers 18 of a cooling mill, where a rubber layer with a thickness of 100 mm and a hardness of 80 degrees is fixed to the outer periphery of the lower roller. This process solidifies the molten polyester resin, producing a glass chopped filament mat 19, which is then wound up by a winding machine 20. The resulting glass chopped filament mat 19 has a thickness of 0.25 mm.

[0083] The amount of adhesive adhered to the glass chopped strand mat of Example 1 obtained in this way was measured, and the result was 15.0% by mass. The result of measuring the mass per unit area was 79.8 g / m². 2 .

[0084] In addition, the unit area mass (unit area mass of the mat) of chopped glass strand mat and the amount of adhesive attached, i.e., the loss on ignition, were determined according to JIS R3420 (2013). Specifically, the amount of adhesive attached was obtained by subtracting the loss on ignition of the chopped glass strand mat used in manufacturing the mat from the loss on ignition of the chopped glass strand mat measured according to JIS R3420 (2013).

[0085] (Examples 2-10 and Comparative Examples 1-6) When manufacturing the roving cake, distances A, B, and C were set as shown in Tables 1 to 3 below, and the amount of adhesive (polyester resin) attached was adjusted as shown in Tables 1 to 3 below. Otherwise, the process was the same as in Example 1 to produce glass chopped strand mat. Furthermore, in the glass chopped strand mats of Examples 2 to 10 and Comparative Examples 1, 4, and 5, the unit area mass of the mat was measured in the same manner as in Example 1, and the results, as shown in Tables 1 to 3 below, were almost identical to those in Example 1. In addition, in Comparative Examples 2, 3, and 6, as described later, the shape of the roving cake and the unwinding properties were poor, making it impossible to obtain glass chopped strand mat.

[0086] (Examples 11-15 and Comparative Examples 7 and 8) When manufacturing the roving, distances A, B, and C are set as shown in Tables 4 and 5 below. The amount of adhesive (polyester resin) is adjusted as shown in Tables 4 and 5 below, and the stacking amount of chopped glass filaments 10A is adjusted so that the unit area mass of the felt reaches 100 g / m². 2 ~140g / m 2 In addition, the same procedure as in Example 1 was performed to produce glass chopped strand mat.

[0087] [evaluate] The rovings and glass chopped strand mats obtained in Examples 1-15 and Comparative Examples 1-8 were evaluated as follows.

[0088] (Split rate of roving) At 100, the roving was cut into 2.5cm lengths. The number of glass filaments dispersed from the cut roving was actually measured, and the splitting rate was calculated by the following formula (2).

[0089] Beam splitting rate = X / (Y × Z) × 100 (%) Equation (2) X: The average number of actual strands in the glass fiber; Y: The number of strands of glass fiber in each fiber cake; Z: The number of silk cakes used for twisting.

[0090] Regarding the bundle splitting rate, 100 samples with a length of 2.5 cm were collected from the front end of the roving at positions of 4100m, 8200m, 12300m, 16400m, 20500m, 24600m, and 28700m for measurement (15 samples from 4100m and 8200m, and 14 samples from 12300m, 16400m, 20500m, 24600m, and 28700m), and the average value was calculated.

[0091] (Number of strands in chopped glass fiber) The binder was decomposed and removed by burning the glass chopped strand mat. 500 strands of glass chopped strand were randomly selected from the obtained chopped strands. Next, the count of the 500 selected strands of glass chopped strand was determined, and its average value was calculated. The count of the glass chopped strands (average count of strands) was determined according to "7.1 Count" of JIS R3420 (2013).

[0092] (Standard deviation of the normal distribution of the number of strands in chopped glass fibers) The binder was decomposed and removed by burning the glass chopped strand mat. 500 strands of glass chopped strand were randomly selected from the obtained chopped strands. Next, the count of the 500 selected strands of glass chopped strand was determined, and its standard deviation (the standard deviation of the strand count) was calculated. The count of the glass chopped strands was determined according to "7.1 Count" of JIS R3420 (2013).

[0093] (Strip tensile strength) The tensile strength of the strip was determined according to Japanese Industrial Standard (JIS R3420 (2013) 7.18). Furthermore, the tensile strength of the strip of chopped glass strand mat was determined by cutting the chopped glass strand mat into 150mm × 300mm pieces and measuring the tensile strength of the strips under a n = 50 condition, and the average value was obtained. In addition, the tensile strength of the strip of chopped glass strand mat was measured in both the longitudinal direction of the material transport direction and the transverse direction orthogonal to the material transport direction.

[0094] (The shape and soothing properties of the silk cake) The shape and unwinding properties of the roving are evaluated according to the following evaluation criteria.

[0095] <Evaluation Criteria> ○: The shape of the silk cake and the unwinding properties of the roving are good; ×: The shape of the silk cake and the unwinding properties of the roving are poor.

[0096] The results are shown in Tables 1 to 5 below.

[0097] [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] As shown in Tables 1 to 5, it can be confirmed that the standard deviation of the normal distribution of the number of glass chopped strands in the glass chopped strand mats of Examples 1 to 15 is less than 4, and the tensile strength in both the longitudinal and transverse directions is improved.

[0098] On the other hand, the standard deviation of the normal distribution of the number of glass chopped strands in the glass chopped strand mats of Comparative Examples 1, 4, 5, 7 and 8 is greater than 4, and their tensile strength in both the longitudinal and transverse directions is insufficient compared with the mats of the same unit area mass.

[0099] For example, Examples 1-10 and Comparative Examples 1, 4, and 5 demonstrate that, despite having the same mass per unit area, mechanical strengths such as tensile strength can be improved by ensuring that the standard deviation of the normal distribution of the number of glass chopped filaments in the glass chopped filament mats of Examples 1-10 is 4 or less. This is also true when comparing Examples 11-13 with Comparative Example 7, and when comparing Example 14 with Comparative Example 8.

[0100] In Comparative Examples 2, 3, and 6, the shape of the filament cake was deformed, and when the roving was unwound from the filament cake, the glass filaments became entangled and could not be unwound midway. Therefore, glass chopped strand mat could not be obtained.

[0101] Symbol Explanation 1: Roving manufacturing device; 2: Bushing; 3: Glass filament; 4: Bundling agent coating mechanism; 4a: Carbon roller; 5: Bundling component; 6: Glass strand; 7: Wire traverse; 7a: Shaft; 8: Collet; 9: Package; 10: Roving; 10A: Chopped glass strand; 11: Chamber; 12: Cutter; 12a: Cutting roller; 12b: Rubber roller; 13: First conveyor belt; 14: Second conveyor belt; 15: Distributor; 16: Third conveyor belt; 17: Heating furnace; 18: Cooling mill water-cooled roller; 19: Glass chopped strand mat; 20: Winding machine.

Claims

1. A glass chopped strand mat, characterized in that: The glass chopped strand mat is formed by bonding multiple strands of glass chopped strands together with an adhesive. The standard deviation of the normal distribution of the number of strands in the glass chopped filaments is less than 4.

2. The glass chopped strand mat as described in claim 1, characterized in that: The number of strands of the chopped glass filaments is 6 tex or more and 20 tex or less.

3. The glass chopped strand mat as described in claim 1 or 2, characterized in that: The length of the chopped glass filament is more than 20 mm and less than 150 mm.

4. The glass chopped strand mat as described in claim 1 or 2, characterized in that: The unit area mass of the glass chopped strand mat is 40 g / m². 2 Above and 200g / m 2 the following.

5. A method for manufacturing a glass chopped strand mat, used to manufacture the glass chopped strand mat according to claim 1 or 2, characterized in that the method comprises: The process of preparing rovings made by bundling multiple strands of glass filaments; The process of obtaining chopped glass filaments by cutting the roving into specified lengths; The process of dispersing and stacking the chopped glass fibers to obtain a stacked sheet of chopped glass fibers; and The process involves distributing a binder onto the stacked glass chopped filament sheets and then pressing them into shape using rollers. The roving has a splitting rate of 50% or more.

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