Glass-chopped strand mat and manufacturing method thereof

Abstract

To provide a glass-chopped strand mat excellent in mechanical strength.SOLUTION: A glass-chopped strand mat is formed by bonding a plurality of glass-chopped strands by a binder. Standard deviation of the glass-chopped strand counts in a normal distribution is 4 or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a glass chopped strand mat and a method for producing the glass chopped strand mat. [Background technology]

[0002] A glass chopped strand mat is a reinforcing material formed by bonding a large number of glass chopped strands together into a mat shape, and is known to be lightweight and have high mechanical strength. Such glass chopped strand mats are widely used as reinforcing materials for glass fiber reinforced plastics (GFRP), automotive molded ceiling materials, etc.

[0003] A known method for producing glass chopped strand mat involves applying a sizing agent to the surfaces of a large number of glass filaments, bundling the resulting glass strands, and cutting the resulting glass chopped strands to a predetermined length, which are then stacked evenly and randomly in the form of a sheet. The resulting sheet-like deposit is then sprayed with a binder and water, and the binder is then heated to melt, after which the sheet-like deposit is press-molded and cooled to solidify (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 068872 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when producing glass chopped strands, a roving made by bundling a plurality of glass strands is prepared, and the roving is cut to a predetermined length to produce the glass chopped strands. However, the mechanical strength of a glass chopped strand mat made using the glass chopped strands produced in this manner may not be sufficiently high. For this reason, a glass chopped strand mat having high mechanical strength is required for applications such as automobile molded ceiling materials, and a method for increasing the mechanical strength without changing the basis weight is particularly required.

[0006] An object of the present invention is to provide a glass chopped strand mat having excellent mechanical strength and a method for producing the glass chopped strand mat. [Means for solving the problem]

[0007] Various embodiments of a glass chopped strand mat and a method for producing the glass chopped strands that solve the above problems will be described below.

[0008] A glass chopped strand mat according to a first aspect of the present invention is a glass chopped strand mat formed by binding a plurality of glass chopped strands with a binder, and is characterized in that the standard deviation in a normal distribution of the yarn counts of the glass chopped strands is 4 or less.

[0009] In the glass chopped strand mat according to aspect 2, in accordance with aspect 1, the glass chopped strands preferably have a yarn count of 6 tex or more and 20 tex or less.

[0010] The glass chopped strand mat according to aspect 3 is the same as in aspect 1 or 2, except that the length of the glass chopped strands is preferably 20 mm or more and 150 mm or less.

[0011] The glass chopped strand mat according to aspect 4 is the glass chopped strand mat according to any one of aspects 1 to 3, wherein the glass chopped strand mat has a basis weight of 40 g / m 2 More than 200g / m 2 It is preferable that:

[0012] A method for producing a glass chopped strand according to a fifth aspect of the present invention is a method for producing a glass chopped strand mat according to any one of the first to fourth aspects, and includes the steps of preparing a roving formed by bundling a plurality of glass strands, obtaining glass chopped strands by cutting the roving to a predetermined length, dispersing and depositing the glass chopped strands to obtain a glass chopped strand deposit sheet, and spraying a binder on the glass chopped strand deposit sheet and press-molding with a roller, wherein the roving has a division rate of 50% or more. Effect of the Invention

[0013] According to the present invention, it is possible to provide a glass chopped strand mat having excellent mechanical strength and a method for producing the glass chopped strand mat. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a graph showing an example of a normal distribution of the yarn count of glass chopped strands constituting a glass chopped strand mat. [Diagram 2] FIG. 2 is a schematic diagram showing an example of a roving production apparatus used in producing a glass chopped strand mat according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing an example of an apparatus for producing the glass chopped strand mat of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Preferred embodiments will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. In addition, in each drawing, components having substantially the same functions may be referred to by the same reference numerals.

[0016] (Glass chopped strand mat) The glass chopped strand mat of the present invention (hereinafter, "glass chopped strand mat" may be simply referred to as "mat") is a glass fiber sheet formed by binding a plurality of glass chopped strands with a binder. In the glass chopped strand mat, a sheet-like deposit of a plurality of glass chopped strands is bonded with a binder.

[0017] In the glass chopped strand mat of the present invention, the standard deviation in the normal distribution of the yarn count of the glass chopped strands is 4 or less. Therefore, the glass chopped strand mat of the present invention has excellent mechanical strength. This will be described below with reference to FIG.

[0018] Fig. 1 is a graph showing an example of a normal distribution of the yarn count of glass chopped strands constituting a glass chopped strand mat. The solid line in Fig. 1 is a graph of the glass chopped strand mat of the present invention. The dashed line in Fig. 1 is a graph of the glass chopped strand mat of a comparative example.

[0019] In measuring the normal distribution of the grain size of the glass chopped strands constituting the glass chopped strand mat, for example, the glass chopped strand mat is incinerated to decompose and remove the binder, and 500 glass chopped strands are randomly extracted from the obtained glass chopped strands. Next, the grain sizes of the extracted 500 glass chopped strands are measured, and the average value and standard deviation are calculated. Next, the above average value is substituted for μ and the above standard deviation is substituted for σ in the following formula (1), to obtain a graph of the normal distribution.

[0020]

number

[0021] In addition, the yarn count of the glass chopped strand can be measured in accordance with "7.1 Yarn count" of JIS R3420 (2013).

[0022] 1, in one example of the glass chopped strand mat of the present invention, the peak height in the normal distribution of the glass chopped strand count is high and the peak width is narrow, whereas in the glass chopped strand mat of the comparative example, the peak height in the normal distribution of the glass chopped strand count is low and the peak width is broad.

[0023] As is clear from Fig. 1, in the glass chopped strand mat of the present invention, the peak height in the normal distribution of the glass chopped strand count is high and the peak width is narrow, so that the variation in the glass chopped strand count is small. In particular, in the glass chopped strand mat of the present invention, the standard deviation in the normal distribution of the glass chopped strand count is 4 or less, and the glass chopped strand mat is composed of glass chopped strands with particularly small variation in the glass chopped strand count, so that the mechanical strength of the glass chopped strand mat (mat) can be effectively increased without changing the basis weight. The reason for this is thought to be as follows.

[0024] If the variation in the count of the glass chopped strands is small, the number of glass chopped strands will be large when compared with mats of the same basis weight. If the number of glass chopped strands is large, the glass chopped strands can be arranged more densely, so that the number of bonding points between the glass chopped strands increases, and the mechanical strength of the glass chopped strand mat increases. In this case, even if the amount of binder used is relatively small, it is easy to obtain a glass chopped strand mat having the desired mechanical strength.

[0025] In the present invention, the standard deviation in the normal distribution of the yarn count of the glass chopped strands is preferably 0.5 or more, more preferably 0.75 or more, even more preferably 1.0 or more, and is preferably 4.0 or less, more preferably 3.5 or less, even more preferably 3.0 or less, particularly preferably 2.5 or less, and most preferably 2.0 or less.

[0026] When the standard deviation in the normal distribution of the yarn count of the glass chopped strands is equal to or greater than the above lower limit, the productivity of the glass chopped strands can be further improved. When the standard deviation in the normal distribution of the yarn count of the glass chopped strands is equal to or less than the above upper limit, the variation in the yarn count of the glass chopped strands can be further reduced, and the mechanical strength of the glass chopped strand mat can be further improved.

[0027] The standard deviation in the normal distribution of the glass chopped strand count is determined, for example, from 500 glass chopped strands. In addition, it is preferable to determine the standard deviation in the normal distribution of the glass chopped strand count by extracting glass chopped strands from the glass chopped strand mat by the above-mentioned method.

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

[0029] When the glass chopped strand count is equal to or higher than the above lower limit, the productivity in producing the glass chopped strand mat can be further improved. When the glass chopped strand count is equal to or lower than the above upper limit, the number of glass chopped strands increases and they can be arranged more densely when compared with mats of the same basis weight, and the mechanical strength of the glass chopped strand mat can be further improved.

[0030] The yarn count of the glass chopped strands can be determined, for example, from the average value of 500 glass chopped strands. The average yarn count of the glass chopped strands is desirably determined by extracting glass chopped strands from the glass chopped strand mat by the above-mentioned method.

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

[0032] When the length of the glass chopped strands is equal to or greater than the above-mentioned lower limit, the mechanical strength of the glass chopped strand mat can be further improved. When the length of the glass chopped strands is equal to or less than the above-mentioned upper limit, the glass chopped strands can be arranged so as to be more uniformly distributed in the glass chopped strand mat, and the mechanical strength of the glass chopped strand mat can be further improved.

[0033] In the present invention, the weight of the glass chopped strand mat is preferably 40 g / m 2 More preferably, 50 g / m 2 More preferably, 60 g / m 2 More preferably, it is 200 g / m 2 Less than 180 g / m 2 More preferably, 160 g / m 2The following is the result.

[0034] When the basis weight of the glass chopped strand mat is equal to or greater than the above lower limit, the mechanical strength of the glass chopped strand mat can be further improved, whereas when the basis weight of the glass chopped strand mat is equal to or less than the above upper limit, the weight of the glass chopped strand mat can be further reduced.

[0035] In this specification, the basis weight of the glass chopped strand mat can be measured in accordance with "7.2 Mass (mass) of cloth and mat" of JIS R3420 (2013).

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

[0037] When the thickness of the glass chopped strand mat is equal to or greater than the above lower limit, the mechanical strength of the glass chopped strand mat can be further improved, whereas when the thickness of the glass chopped strand mat is equal to or less than the above upper limit, the glass chopped strand mat can be further made thinner (or lighter).

[0038] Examples of the material of the glass chopped strands constituting the glass chopped strand mat include E glass, S glass, T glass, A glass, C glass, D glass, and H glass.

[0039] The binder constituting the glass chopped strand mat may be made of, for example, polyester, polypropylene, vinyl acetate, acrylic, epoxy, or other resin. Among them, polyester resin is preferred as the binder, and powdered unsaturated polyester resin is preferred. In this case, the binder can be melted and cooled to solidify more easily.

[0040] In the glass chopped strand mat of the present invention, the amount of the binder adhered, in mass percentage, is preferably 1% or more, more preferably 3% or more, even more preferably 5% or more, and is preferably 20% or less, more preferably 17% or less.

[0041] When the amount of binder attached to the glass chopped strand mat is equal to or greater than the lower limit, the mechanical strength of the glass chopped strand mat can be further improved. When the amount of binder attached to the glass chopped strand mat is equal to or less than the upper limit, the thickness of the glass chopped strand mat becomes more uniform, and the flexibility of the glass chopped strand mat can be increased. When the amount of binder attached to the glass chopped strand mat is equal to or less than the upper limit, the amount of binder used is reduced, and thus the manufacturing cost can be reduced.

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

[0043] The glass chopped strand mat of the present invention has excellent mechanical strength and can therefore be suitably used in fiber-reinforced molded composite materials, and can be particularly suitably used as a reinforcing material for molded automobile ceiling materials and the like.

[0044] (Method of manufacturing glass chopped strand mat) The method for producing a glass chopped strand mat of the present invention includes a step (step 1) of preparing a roving consisting of a plurality of glass strands bundled together, a step (step 2) of obtaining glass chopped strands by cutting the roving to a predetermined length, a step (step 3) of dispersing and depositing the glass chopped strands to obtain a glass chopped strand deposit sheet, and a step (step 4) of spraying a binder on the glass chopped strand deposit sheet and press-molding with a roller.

[0045] An example of steps 1 to 4 will be described below.

[0046] Step 1; 2 is a schematic diagram showing an example of a roving manufacturing apparatus used in the production of a glass chopped strand mat according to one embodiment of the present invention. In step 1, a roving is prepared using the roving manufacturing apparatus 1 shown in FIG.

[0047] In step 1, glass raw materials fed into a glass melting furnace are melted to form molten glass. After the molten glass is made homogenous, it is drawn out from a heat-resistant nozzle attached to a bushing 2. The drawn molten glass is then cooled to form a plurality of glass filaments 3 (monofilaments). For example, a platinum bushing can be used as the bushing 2.

[0048] The composition of the glass filaments 3 is not particularly limited, and for example, E glass, S glass, T glass, A glass, C glass, D glass, H glass, etc. are used. Among these, it is preferable that the composition of the glass filaments 3 is E glass. E glass is inexpensive and can further increase the mechanical strength of the glass chopped strand mat.

[0049] The number of the glass filaments 3 is not particularly limited, but is preferably 500 or more, more preferably 1000 or more, and preferably 10000 or less, and more preferably 8000 or less. When the number of the glass filaments 3 is equal to or more than the above lower limit, the productivity of the roving to be produced can be further improved. When the number of the glass filaments 3 is equal to or less than the above upper limit, the length of each glass filament 3 can be more easily uniformed.

[0050] Next, a sizing agent is applied to the surfaces of the obtained plurality of glass filaments 3 by a sizing agent application mechanism 4. In a state in which the sizing agent is evenly applied to the surfaces of the plurality of glass filaments 3, the plurality of glass filaments 3 are aligned and bundled. The plurality of glass filaments 3 can be aligned and bundled by a focusing shoe 5. In this way, a glass strand 6 can be formed.

[0051] 2, for convenience of illustration, only one glass strand 6 is shown, but in the focusing shoe 5, the glass filaments 3 are split and focused into multiple glass strands 6. For example, when using 5,000 glass filaments 3, the glass filaments 3 may be aligned in groups of 500 to form 10 glass strands 6.

[0052] The number of glass strands 6 formed by the splitting yarns 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 glass strands 6 formed by the splitting yarns is within the above range, the productivity of the roving can be further improved.

[0053] The sizing agent may contain, for example, a thermoplastic resin such as polypropylene resin, nylon resin, polyvinyl acetate, or polyphenylene sulfide resin. The sizing agent may also contain a thermosetting resin such as polyester (unsaturated polyester) resin, epoxy resin, or polyurethane resin. The sizing agent may also contain components such as a lubricant, a nonionic surfactant, or an antistatic agent. The compounding ratio of these components may be appropriately set as needed.

[0054] Next, the glass strands 6 are wound around a collet 8 while being traversed by a wire traverse 7, and a roving wound body 9 is produced in which the glass strands 6 are bundled together.

[0055] The wire traverse 7 is not particularly limited, but may be, for example, the wire traverse shown in FIG. 8 of JP 2021-147208 A. In JP 2021-147208 A, the glass strand S split into four strands is wound by the wire traverse while being traversed around a collet.

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

[0057] Next, the sizing agent is heated and dried to evaporate the water, thereby forming a coating on the surface of the glass filaments 3. For example, hot air drying or dielectric drying can be used as the method of heating and drying. Heat drying can be performed, for example, at a temperature range of 100°C to 150°C for 1 hour to 24 hours. This makes it possible to obtain a dried cake of the roving (hereinafter, also simply referred to as cake). The winding thickness of the dried cake is, for example, 5 mm to 500 mm.

[0058] For the heat drying, it is preferable to use hot air drying. In this case, the glass strand 6 can be heated and dried more uniformly from the winding start to the winding end. Hot air drying makes it easy to maintain the sizing agent at a certain temperature range. Hot air drying and dielectric drying may be used in combination.

[0059] The roving prepared in step 1 has a split rate of 50% or more. The split rate refers to the proportion of glass strands 6 that are not bonded to other glass strands 6 and are composed of a single glass strand 6 when 100 arbitrary points of the roving are cut into a length of 2.5 cm. Therefore, it can be used as an index of the number of bonded points between the glass strands 6 that compose the glass strand bundle, and the larger the split rate, the fewer the number of bonded points between the glass strands 6. Therefore, by having the split rate of the roving be 50% or more, it is possible to reduce the variation in the count of the glass chopped strands described below.

[0060] The split ratio of the roving prepared in step 1 is preferably 60% or more, more preferably 65% ​​or more, even more preferably 70% or more, and is preferably 99% or less, more preferably 98% or less.

[0061] When the division ratio of the roving prepared in step 1 is equal to or greater than the above-mentioned lower limit, the variation in the count of the glass chopped strands described below can be further reduced. When the division ratio of the roving prepared in step 1 is equal to or less than the above-mentioned upper limit, the workability in unwinding the divided glass strands 6 from the roving is further improved.

[0062] The division ratio of the roving can be adjusted, for example, by changing the distance A, the distance B, and the distance C shown in FIG.

[0063] Distance A is the distance in the height direction between the center of the focusing shoe 5 and the center of the collet 8. If distance A is too small, the tension applied to the glass strands 6 becomes large, the glass strands 6 tend to adhere to each other, and the division rate of the roving becomes small. If distance A is too large, the tension applied to the glass strands 6 becomes small, which may result in a poor shape of the cake or poor unwinding of the roving from the cake. Taking these points into consideration, distance A can be, for example, 500 mm or more and 3000 mm or less.

[0064] The distance B is the horizontal distance between the contact point of the carbon roller 4a of the sizing agent application mechanism 4 with the glass filaments 3 and the center of the focusing shoe 5. If the distance B is too small, the tension applied to the glass strands 6 is small, which may result in a poor shape of the cake or poor unwinding of the roving from the cake. If the distance B is too large, the tension applied to the glass strands 6 is large, which makes the glass strands 6 more likely to adhere to each other, thereby reducing the division rate of the roving. Taking these points into consideration, the distance B can be set to, for example, 50 mm or more and 200 mm or less.

[0065] Distance C is the horizontal distance between the surface of the wound body 9 closest to the wire traverse 7 and the point furthest from the axis 7a of the wire traverse 7. Note that at the start of winding the glass strand 6, the distance C is not the surface of the wound body 9 closest to the wire traverse 7, but the horizontal distance between the surface of the collet 8 closest to the wire traverse 7 and the point furthest from the axis 7a of the wire traverse 7.

[0066] If the distance C is too small, the tension applied to the glass strands 6 becomes large, the glass strands 6 tend to adhere to each other, and the division rate of the roving becomes small. If the distance C is too large, the tension applied to the glass strands 6 becomes small, which may result in a poor shape of the cake or poor unwinding of the roving from the cake. Taking these points into consideration, the distance C can be set to, for example, 10 mm or more and 200 mm or less.

[0067] Step 2~Step 4; FIG. 3 is a schematic diagram showing an example of an apparatus for producing the glass chopped strand mat of the present invention.

[0068] As shown in Fig. 3, the roving 10 is unwound from the inner layer of the cake obtained in step 1 and fed into a plurality of cutters 12 attached to the ceiling of the chamber 11. As a result, the glass strands constituting the roving 10 are cut to a predetermined length to obtain glass chopped strands 10A. Each cutter 12 is composed of a cutter roller 12a and a rubber roller 12b. In each cutter 12, the roving 10 is fed between the cutter roller 12a and the rubber roller 12b which rotate relative to each other, thereby cutting the glass strands.

[0069] Next, the glass chopped strands 10A are uniformly dispersed on a first transfer conveyor 13 disposed at the bottom of the chamber 11, and are deposited in a sheet form. The glass chopped strands 10A deposited in a sheet form are transported outside the chamber 11, and then transferred to the next second transfer conveyor 14.

[0070] Next, a binder is uniformly spread on the glass chopped strands 10A moving on the second transport conveyor 14 by a spreader 15, and the strands are transported to the next, third transport conveyor 16. The sheet-like pile of glass chopped strands 10A with the binder spread thereon is moved into a heating furnace 17 and heated to soften and melt the binder.

[0071] Next, the sheet-like deposit of the glass chopped strands 10A is moved to the outside of the heating furnace 17, and is cooled and pressed by passing through water-cooled rolls 18 of a cooling rolling machine. This solidifies the molten binder, and a glass chopped strand mat 19 can be obtained. The glass chopped strand mat 19 can be wound by a winding machine 20 and pulled out for use.

[0072] The binder for binding the glass chopped strands 10A is not particularly limited, and may be, for example, a resin such as polyester, polypropylene, vinyl acetate, acrylic, or epoxy. Among them, the binder is preferably a polyester resin, and more preferably a powdered unsaturated polyester resin. In this case, the binder can be melted and cooled to solidify more easily.

[0073] The form of the binder is not particularly limited, and for example, a powder, liquid, fiber, sheet, or film form can be used.

[0074] In the method for producing a glass chopped strand mat of the present invention, the split ratio of the roving produced in step 1 is 50% or more, so that the variation in the count of the glass chopped strands can be reduced, and the standard deviation in the normal distribution of the count of the glass chopped strands can be made 4 or less. Therefore, the glass chopped strand mat obtained by the method for producing a glass chopped strand mat of the present invention has excellent mechanical strength.

[0075] The present invention will be described in more detail below with reference to specific examples. The present invention is not limited to the following examples, and can be modified as appropriate within the scope of the present invention.

[0076] Example 1 Roving was manufactured using a roving manufacturing apparatus 1 shown in Fig. 2. Specifically, first, molten glass having an E-glass composition was drawn out from a bushing 2 to obtain 1000 glass filaments 3. Next, a sizing agent was applied to the surface of the obtained glass filaments 3 by a sizing agent application mechanism 4, with the sizing agent adjusted so that the ignition loss was 0.50 mass%, and the glass filaments 3 were bundled using a bundling shoe 5 to obtain a glass strand 6. In the bundling shoe 5, the 1000 glass filaments 3 were split and aligned in groups of 100 to form 10 glass strands 6.

[0077] Next, the obtained 10 glass strands 6 were wound around a collet 8 having a diameter of 300 mm while being traversed by a wire traverse 7, and a roving wound body 9 was produced in which the glass strands 6 were bundled. Next, the wound body 9 produced was heated and dried in a hot air drying oven at 150°C for 600 minutes to obtain a dried cake (cake) of the roving. The wound thickness of the dried cake (cake) was 45 mm.

[0078] In addition, when producing a cake of roving, the distance A in the height direction between the center of the focusing shoe 5 and the center of the collet 8 was set to 500 mm. The distance B in the horizontal direction between the contact point of the carbon roller 4a of the sizing agent application mechanism 4 with the glass filaments 3 and the center of the focusing shoe 5 was set to 100 mm. The distance C in the horizontal direction between the surface of the wound body 9 closest to the wire traverse 7 and the point farthest from the axis 7a of the wire traverse 7 was set to 100 mm.

[0079] Next, as shown in Fig. 3, the roving 10 was unwound from the inner layer of the dried cake and fed into a plurality of cutters 12 attached to the ceiling of the chamber 11, where it was cut to a predetermined length. Each cutter 12 is composed of a cutter roller 12a and a rubber roller 12b, and the roving 10 is cut by being fed between the cutter roller 12a and the rubber roller 12b which rotate relative to each other.

[0080] A first transport conveyor 13 was placed at the bottom of the chamber 11, and the glass chopped strands 10A, cut to a length of 50 mm, were uniformly dispersed on the first transport conveyor 13, deposited in a sheet form, and then transported outside the chamber 11 and to the next second transport conveyor 14.

[0081] A polyester resin as a binder was uniformly spread by a spreader 15 onto the glass chopped strands 10A moving on the second transport conveyor 14 so that the adhesion amount was 15.0 mass %, and then the strands were transported to the next third transport conveyor 16. A heating furnace 17 was disposed midway along the third transport conveyor 16, and the sheet-like deposit of the glass chopped strands 10A on which the polyester resin had been spread was moved into the heating furnace 17 and heated at 260°C to soften and melt the polyester resin.

[0082] Next, this sheet-like deposit of glass chopped strands 10A was moved to the outside of the heating furnace 17, and then cooled and pressed through water-cooled cooling mill rolls 18, the lower roll of which had a rubber layer of 100 mm in thickness and hardness of 80 degrees fixed to its outer periphery, whereby the molten polyester resin solidified to produce a glass chopped strand mat 19, which was then wound up by a winder 20. The thickness of the obtained glass chopped strand mat 19 was 0.25 mm.

[0083] The amount of the binder attached to the glass chopped strand mat of Example 1 thus obtained was measured to be 15.0 mass %, and the basis weight was measured to be 79.8 g / m 2 It was.

[0084] The basis weight of the glass chopped strand mat (basis weight of the mat) and the amount of binder attached, i.e., the ignition loss, were measured in accordance with JIS R3420 (2013). Specifically, the amount of binder attached was determined by subtracting the ignition loss of the cake used in producing the glass chopped strands from the ignition loss of the glass chopped strand mat measured in accordance with JIS R3420 (2013).

[0085] (Examples 2 to 10 and Comparative Examples 1 to 6) In producing the roving cake, the distances A, B, and C were set as shown in Tables 1 to 3 below, and the amount of the binder (polyester resin) attached was adjusted to the amount shown in Tables 1 to 3 below, and other than this, glass chopped strand mats were produced in the same manner as in Example 1. In the glass chopped strand mats of Examples 2 to 10 and Comparative Examples 1, 4, and 5, the basis weight of the mat was measured in the same manner as in Example 1, and as shown in Tables 1 to 3 below, the values ​​were almost the same as in Example 1. In Comparative Examples 2, 3, and 6, as described below, the shape of the cake and the unwinding property of the roving were poor, and a glass chopped strand mat could not be obtained.

[0086] (Examples 11 to 15 and Comparative Examples 7 and 8) When producing a cake of roving, the distances A, B, and C are set as shown in Tables 4 and 5 below, the amount of the binder (polyester resin) is adjusted to be the amount shown in Tables 4 and 5 below, and the basis weight of the mat is 100 g / m 2 ~140g / m 2 A glass chopped strand mat was produced in the same manner as in Example 1, except that the deposition amount of the glass chopped strands 10A was adjusted so as to be about 100%.

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

[0088] (Roving division ratio) The roving was cut into 100 pieces having a length of 2.5 cm, and the number of glass strands dispersed from each cut roving was measured, and the division ratio was calculated according to the following formula (2).

[0089] Division ratio=X / (Y×Z)×100(%)…Equation (2) X: Average value of the measured number of glass strands Y: Number of glass strands per cake Z: Number of cakes to be yarned

[0090] The splitting rate was measured by taking 100 pieces, each 2.5 cm long, from the tip of the roving at 4100m, 8200m, 12300m, 16400m, 20500m, 24600m, and 28700m (15 pieces at 4100m and 8200m, and 14 pieces at 12300m, 16400m, 20500m, 24600m, and 28700m), and calculating the average value.

[0091] (Glass chopped strand count) The glass chopped strand mat was incinerated to decompose and remove the binder, and 500 glass chopped strands were randomly selected from the resulting glass chopped strands. The numbers of the 500 glass chopped strands selected were then measured and their average value was calculated. The number of the glass chopped strands (average strand number) was measured in accordance with "7.1 Number" of JIS R3420 (2013).

[0092] (Standard deviation in normal distribution of glass chopped strand count) The glass chopped strand mat was incinerated to decompose and remove the binder, and 500 glass chopped strands were randomly selected from the resulting glass chopped strands. Next, the counts of the 500 glass chopped strands selected were measured, and the standard deviation (standard deviation of strand count) was calculated. The glass chopped strand count was measured in accordance with "7.1 Number" of JIS R3420 (2013).

[0093] (Tensile strength of strip) The strip tensile strength was measured in accordance with the Japanese Industrial Standards (JIS R3420 (2013) 7.18). The strip tensile strength of the glass chopped strand mat was determined by cutting the glass chopped strand mat into pieces measuring 150 mm x 300 mm, measuring the strip tensile strength for n=50 pieces, and averaging the results. The strip tensile strength of the glass chopped strand mat was measured in both the longitudinal direction, which is the material flow direction, and the transverse direction, which is perpendicular to the material flow direction.

[0094] (Cake shape and releasability) The shape of the roving cake and the releasability of the roving were evaluated according to the following criteria.

[0095] <Evaluation criteria> Good: Cake shape and roving releasability are good. ×: Poor cake shape and roving releasability

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

[0097] [Table 1]

[0098] [Table 2]

[0099] [Table 3]

[0100] [Table 4]

[0101] [Table 5]

[0102] As shown in Tables 1 to 5, the glass chopped strand mats of Examples 1 to 15 had a standard deviation in the normal distribution of the glass chopped strand count of 4 or less, and it was confirmed that the tensile strength was increased in both the longitudinal and transverse directions.

[0103] On the other hand, the glass chopped strand mats of Comparative Examples 1, 4, 5, 7, and 8 had standard deviations in the normal distribution of the glass chopped strand counts that were greater than 4, and when compared with mats of equivalent basis weight, the tensile strength was insufficient in both the longitudinal and transverse directions.

[0104] For example, although Examples 1 to 10 and Comparative Examples 1, 4, and 5 have almost the same basis weight, it was confirmed that the mechanical strength such as tensile strength could be increased in the glass chopped strand mats of Examples 1 to 10 by setting the standard deviation in the normal distribution of the count of the glass chopped strands to 4 or less. The same can be said in comparisons between Examples 11 to 13 and Comparative Example 7, and between Example 14 and Comparative Example 8.

[0105] In Comparative Examples 2, 3, and 6, the shape of the cake was distorted, and when the roving was unwound from the cake, the glass strands got caught and could not be unwound halfway through, which was a problem. Therefore, a glass chopped strand mat could not be obtained. [Explanation of symbols]

[0106] 1...Roving manufacturing equipment 2…Bushing 3…Glass filament 4…Bundle application mechanism 4a…Carbon roller 5…Focusing shoe 6…Glass strand 7…Wire traverse 7a…axis 8. Colette 9…Rolled body 10. Roving 10A…Glass chopped strand 11…Chamber 12...Cutting machine 12a…Cutter roller 12b...Rubber roller 13…First conveyor 14…Second transport conveyor 15...Spreader 16…Third conveyor 17...Heating furnace 18...Water-cooled rolls for cooling rolling mill 19…Glass chopped strand mat 20…Winding machine

Claims

1. A glass chopped strand mat formed by binding a plurality of glass chopped strands with a binder, A glass chopped strand mat, wherein the standard deviation in a normal distribution of the yarn count of the glass chopped strands is 4 or less.

2. 2. The glass chopped strand mat according to claim 1, wherein the glass chopped strands have a yarn count of 6 tex or more and 20 tex or less.

3. 3. The glass chopped strand mat according to claim 1, wherein the length of the glass chopped strands is 20 mm or more and 150 mm or less.

4. The glass chopped strand mat has a basis weight of 40 g / m ２ Above, 200g / m ２ 3. The glass chopped strand mat according to claim 1 or 2, wherein:

5. A method for producing the glass chopped strand mat according to claim 1 or 2, A step of preparing a roving including a plurality of glass strands bundled together; cutting the roving to a predetermined length to obtain glass chopped strands; a step of dispersing and depositing the glass chopped strands to obtain a glass chopped strand deposit sheet; a step of spraying a binder onto the glass chopped strand pile sheet and press-molding the sheet with a roller; Equipped with The method for producing a glass chopped strand mat, wherein the roving has a split rate of 50% or more.

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