JP2009242616A - Resin injection-molded article and its molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure strength and surface impact resistance of a resin injection-molded article by suppressing bending fracture of a reinforcing fiber. <P>SOLUTION: A thermoplastic resin (pellet) R is charged into a twin screw extruder 1C and kneaded and melted, and a granular solid material A of which the aspect ratio is set to be 1-5 and the average particle size is set to be 10 μm or less of 0.5-5 wt.% is added and charged and uniformly mixed therewith. A roving F1-a is introduced into the twin screw extruder 1C and is cut and unraveled in the kneading process of the thermoplastic resin R and the granular solid material A, and subsequently the thermoplastic resin with the granular solid material A and the reinforcing fiber mixed thereinto is extruded into an injection molding machine 15C, and is injected into a mold 23 by the injection molding machine 15C so as to form the resin injection-molded article. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improvement in a resin injection molded product in which reinforcing fibers are mixed and a molding method thereof, and particularly to measures against breakage of reinforcing fibers.

  2. Description of the Related Art Conventionally, reinforcing and reinforcing fibers such as glass fibers are mixed into a resin injection molded product to ensure strength and rigidity. In particular, recently, by adopting a fiber having a relatively long fiber length as a reinforcing fiber, the strength and surface impact property of a resin injection molded product are greatly improved, and the application has been extended to structural members.

  As an example, Patent Document 1 discloses a resin injection molded product that is injection-molded with a crystalline resin in which a long fibrous reinforcing material and a scaly filler are mixed.

Patent Document 2 discloses an injection molding machine suitable for plasticizing injection of pellets containing long glass fibers.
JP 2004-323559 A (pages 3 to 5) JP 2004-291409 A (paragraph 0019 column, FIG. 1)

  However, since the reinforcing fibers generally used are often rigid, when the fiber length becomes long, the fibers become entangled during plasticizing and melting, kneading and injection molding, the resin viscosity becomes high, and the reinforcing fibers break. The improvement of physical properties by using a reinforcing fiber having a long fiber length is not expected as expected.

  In order to suppress the breakage of the reinforcing fiber, the above-mentioned Patent Document 2 employs a special screw with a small kneading force, but because it is a special injection molding machine different from a general injection molding machine, capital investment Is necessary and the cost increases. Further, since the kneading force is small, it is not suitable for molding other general resin injection molded products, and is not versatile and the productivity of the injection molding machine is not good.

  On the other hand, it is also possible to suppress breakage of the reinforcing fibers by lowering the resin viscosity by increasing the molding temperature, but the resin tends to deteriorate due to high temperature molding, and measures such as adding an antioxidant are newly added. Necessary and costly.

  In addition, in said patent document 1, from a viewpoint which prevents the curvature deformation of a resin injection molded product, the thing of a scale shape with which the aspect-ratio was set to 5-200 and the average diameter to 20-700 micrometers was employ | adopted as a filler. No measures are taken for breakage of the reinforcing fiber. That is, when the filler is scaly and has a large diameter, the applicant has experienced through experiments (Comparative Example 3) described later in the embodiment that the frequency of breakage of the reinforcing fibers increases during kneading.

  The present invention has been made in view of such points, and the object of the invention is to lengthen the reinforcing fiber length in the resin injection molded product by suppressing breakage of the reinforcing fiber, and as a result, the resin injection. The object is to ensure the physical properties of the molded product, particularly the strength and surface impact.

  In order to achieve the above object, the present invention is characterized in that a granular solid material that exhibits a lubricating function at the time of kneading or the like is employed as a filler.

  Specifically, the present invention is directed to a resin injection molded article and a molding method thereof, and has taken the following solutions.

  That is, the invention described in claims 1 to 3 relates to a resin injection molded product that is injection-molded with a thermoplastic resin in which reinforcing fibers and granular solids are mixed. Of these, the invention described in claim 1 The particulate solid has an aspect ratio of 1 to 5, an average particle size of 10 μm or less, and a blending amount of 0.5 to 5% by weight.

  According to a second aspect of the present invention, in the first aspect of the present invention, the granular solid material includes at least one selected from talc, calcium carbonate, titanium oxide, silica, zinc oxide and alumina. It is characterized by.

  The invention according to claim 3 is the invention according to claim 1, wherein the reinforcing fiber is at least one selected from glass fiber, carbon fiber, rock wool, quartz fiber, metal fiber, whisker, and aramid fiber. It consists of one.

  The invention described in claims 4 to 8 relates to a molding method for injection molding a resin injection molded product with a thermoplastic resin in which reinforcing fibers and granular solids are mixed. Of these, the invention described in claim 4 A pellet forming step of forming fiber-mixed pellets obtained by impregnating a columnar fiber bundle of reinforcing fibers with a thermoplastic resin, and the fiber-mixed pellets are put into an injection molding machine and melted, and the molten resin is injected into a mold In the molded product molding process for molding a resin injection molded product, and the pellet molding process or the molded product molding process, a granular solid having an aspect ratio of 1 to 5 and an average particle size of 10 μm or less is set to 0.0. And 5-5% by weight of a solid substance addition step.

  In the invention according to claim 5, 0.5 to 5% by weight of a granular solid having an aspect ratio of 1 to 5 and an average particle size of 10 μm or less is added to the thermoplastic resin, and the chopped strand is reinforced. Pellet molding process for molding fiber-mixed pellets in which fibers are dispersed, and molding the resin-mixed pellets into an injection molding machine, and then injecting the molten resin into a mold to mold a resin injection molded product And a product molding step.

  The invention according to claim 6 introduces a thermoplastic resin into a twin screw extruder, and 0.5 to 5% by weight of a granular solid having an aspect ratio of 1 to 5 and an average particle size of 10 μm or less. Introducing the roving reinforcing fiber into the twin screw extruder, cutting and defibrating in the kneading process of the thermoplastic resin and the granular solid, and then mixing the granular solid and the reinforcing fiber The thermoplastic resin in a state is extruded into an injection molding machine and injected into a mold by the injection molding machine to form a resin injection molded product.

  The invention according to claim 7 is the invention according to any one of claims 4 to 6, wherein the particulate solid is selected from talc, calcium carbonate, titanium oxide, silica, zinc oxide and alumina. It consists of at least one.

  The invention according to claim 8 is the invention according to any one of claims 4 to 6, wherein the reinforcing fiber is made of glass fiber, carbon fiber, rock wool, quartz fiber, metal fiber, whisker and aramid fiber. It is characterized by comprising at least one selected from among them.

  According to the inventions according to claims 1 and 4 to 6, as the granular solid, those having an aspect ratio of 1 to 5, an average particle size of 10 μm or less, and a blending amount of 0.5 to 5% by weight Since the above-mentioned granular solids serve as a lubricant when kneading the reinforcing fiber and the thermoplastic resin, the reinforcing fiber is used even if the resin viscosity is high and the fiber length of the reinforcing fiber is relatively long. The strength and surface impact of the resin injection molded product are ensured. In addition, since it is only necessary to specify the shape, size, and blending amount of granular solids, resin injection molded products can be injection molded with a general-purpose injection molding machine, eliminating the need for extra equipment investment and reducing costs. It is possible to produce plastic injection molded products, increasing the operating rate of injection molding machines and improving productivity. Furthermore, since it is not necessary to increase the molding temperature in order to lower the resin viscosity in consideration of fluidity, there is no thermal degradation of the thermoplastic resin, and no addition of an antioxidant for preventing thermal degradation is necessary. Also reduces costs. In particular, in the invention according to claim 6, since the pellet forming step can be omitted, the forming cycle is shortened and the production efficiency and the energy efficiency are improved. In addition, since the raw material and the reinforcing fiber are kneaded and the injection molding of the resin injection molded product is performed directly on the spot, a biaxial extrusion process having a stronger kneading force than that of the inventions according to claims 4 and 5 is required. When a strong twin screw extruder is used, the reinforcing fibers are easily broken, but the effect of suppressing breakage of the reinforcing fibers is increased by adding the granular solid of the present invention.

  According to the inventions according to claims 2 and 7, the granular solid is made of at least one selected from talc, calcium carbonate, titanium oxide, silica, zinc oxide and alumina, so it is inexpensive and has a low aspect ratio. A granular solid is easily obtained.

  According to the third and eighth aspects of the invention, at least one selected from glass fiber, carbon fiber, rock wool, quartz fiber, metal fiber, whisker, and aramid fiber is used as the reinforcing fiber. The strength and surface impact property of the resin injection molded product can be effectively increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 6 shows a shroud S as a resin injection-molded product according to an embodiment of the present invention that covers a radiator core of an automobile and a cooling fan of the radiator. This shroud S is injection-molded with a thermoplastic resin in which reinforcing fibers and granular solids are mixed, and is particularly excellent in physical properties such as strength and surface impact. The shroud S is an example of a resin injection molded product, and is not limited thereto.

  The thermoplastic resin is not particularly limited. For example, poly-α olefins such as polyethylene, polypropylene, propylene-α olefin copolymer, polybutene, poly-4 methylpentene, polyamide-6, polyamide-6, 6, Polyamide such as polyamide-6,10, polyamide-12, aromatic polyamide, polyester such as polyethylene terephthalate, polybutylene terephthalate, polyester copolymer, polystyrene, acrylonitrile / butadiene / styrene resin, polyacetal, polyphenylene Oxides, polyphenylene sulfide, and the like. Among these, polypropylene, propylene-α-olefin copolymer, polyamide-6, polyamide-, in particular, from the viewpoint of being used in a large amount and available at low cost and applied to the automotive field where strength and surface impact properties are required. 6,6 are preferred. It is also preferable to employ a resin composition comprising two or more of the above and a polymer alloy comprising two or more. Furthermore, in order to reinforce the interfacial adhesion with the reinforcing fiber, a resin modified with a reactive functional group or a polar functional group such as an unsaturated acid or acid anhydride, a silicon-containing compound, or the like is added. It is also useful to graft polymerize a compound having a reactive functional group or a polar functional group together with a peroxide during the kneading process of the resin. The blending amount of the thermoplastic resin is not particularly limited, but is preferably selected in the range of 40 to 95% by weight in consideration of the purpose and application of the resin injection molded product.

  The reinforcing fiber is composed of at least one selected from glass fiber, carbon fiber, rock wool, quartz fiber, metal fiber, whisker, and aramid fiber. Among them, particularly preferred are glass fibers that are used in large quantities and inexpensive and carbon fibers that exhibit high strength. The reinforcing resin is used in the form of a roving in which strands having an average diameter of 5 to 30 μm and a filament focusing number of 400 to 25000 are aligned to form a string, or a chopped strand in which the strand is cut into 3 to 20 mm. Moreover, the yarn which combined the strand more as needed can also be used. In general, the surface of the reinforcing fiber is preferably treated with a coupling agent and a sizing agent in order to facilitate the opening of filament bundles and to increase the affinity with the thermoplastic resin. The blending amount of the reinforcing fiber is not particularly limited, but is 5 to 60% by weight, preferably 20 to 50% by weight.

  The granular solid consists of at least one selected from talc, calcium carbonate, titanium oxide, silica, zinc oxide and alumina. Of these, talc and calcium carbonate, which are used in large quantities and are inexpensive, are preferable. This granular solid has an aspect ratio of 1 to 5, an average particle size of 10 μm or less, and a blending amount of 0.5 to 5% by weight. This is the greatest feature of the present invention. As for the granular solid, a talc or the like close to a plate shape has a small aspect, and the closer to a spherical shape, the more preferable. If the aspect ratio exceeds 5, the lubrication function between the reinforcing fibers and between the reinforcing fibers and the screws and heating cylinders of the extruder and injection molding machine is hindered, and the frequency of breakage of the reinforcing fibers increases, and the fibers in the resin injection molded product The aspect ratio is set to 5 or less because the length is shortened and the physical properties, particularly the surface impact property are lowered. The average particle size of the granular solid is set to 10 μm or less because when the average particle size exceeds 10 μm, the lubrication function is lowered and the breakage frequency of the reinforcing fibers is increased, and the fiber length in the resin injection molded product is increased. This is because the surface impact is reduced, and the amount of blending is set to 0.5 to 5% by weight. If the blending amount is less than 0.5% by weight, the lubrication function cannot be sufficiently achieved. This is because if the blending amount exceeds 5% by weight, the influence of the particulate solid on the thermoplastic resin is increased, and particularly the surface impact is reduced. In order to maintain the affinity of the solid solid material with the thermoplastic resin, it is preferable that surface treatment or the like with stearic acid or a titanium coupling agent is performed. In addition, the granular solid may be kneaded into the thermoplastic resin in advance, and then the reinforcing fiber may be blended, or may be kneaded with the reinforcing fiber or the thermoplastic resin, and further, the thermoplastic resin containing the reinforcing fiber. May be added during injection molding.

  In addition, additives such as heat resistance stabilizers, weather resistance stabilizers, lubricants, antistatic agents, slip agents, and other auxiliary materials may be used in combination as necessary.

  There are three types of molding methods for resin injection molded products that require strength and surface impact, such as the shroud S.

<First molding method>
This molding method includes a pellet molding step shown in FIG. 1 and a molded product molding step shown in FIG.

  First, as shown in FIG. 1, a thermoplastic resin (pellet) R and other additives (not shown) as necessary are put into a hopper 3A of an extruder 1A. The screw 7A is rotated in the heating cylinder 5A to melt and knead the thermoplastic resin (pellet) R. This molten resin is extruded into an impregnation die 9 attached to the tip of the heating cylinder 5A.

  On the other hand, the roving F1-a is introduced into the impregnation die 9 from the reinforcing fiber roving raw fabric F1, and the roving F1-a is impregnated with the molten resin. The roving F1-a impregnated with the molten resin is pulled out from the impregnation die 9 and introduced into the cooling bath 11 to cure the impregnated resin, and further introduced into the cutter device 13 and cut into a predetermined size to form a fiber-mixed pellet P1. To do. At this time, the roving F1-a is cut, and the fiber-mixed pellets P1 have reinforcing fibers as columnar fiber bundles F1-b, and the columnar fiber bundles F1-b are impregnated with a thermoplastic resin.

  Next, as shown in FIG. 2, the fiber-mixed pellet P1 and the same thermoplastic resin R as the thermoplastic resin (pellet) R used in the pellet molding step are charged as dilution resins into the hopper 17 of the injection molding machine 15A. At the same time, 0.5 to 5% by weight of a granular solid A having an aspect ratio of 1 to 5 and an average particle size of 10 μm or less is added. The screw 21 is rotated in the heating cylinder 19A to melt and knead the thermoplastic resin (pellet) R and the fiber-mixed pellet P1, and the particulate solid A is mixed uniformly. The molten resin is injected into the cavity 23a of the mold 23 to mold a resin injection molded product. In addition, you may add a solid substance addition process with a thermoplastic resin previously at the time of the pellet formation process which shape | molds the fiber mixing pellet P1.

<Second molding method>
This molding method includes a pellet molding step shown in FIG. 3 and a molded product molding step shown in FIG.

  First, as shown in FIG. 3, among the two hoppers 3B-1 and 3B-2 of the twin-screw extruder 1B, the thermoplastic resin (pellet) R is introduced into one hopper 3B-1, and the aspect ratio is set. 1 to 5 and 0.5 to 5% by weight of a granular solid A having an average particle size set to 10 μm or less is added. Moreover, the reinforced fiber F2 in a chopped strand state is put into the other hopper 3B-2. The biaxial screw 7B is rotated in the heating cylinder 5B to melt and knead the thermoplastic resin (pellet) R and the reinforcing fiber F2, and the particulate solid A is mixed uniformly, and the reinforcing fiber F2 is melted into the molten resin. Disperse evenly. After this molten resin is extruded from the heating cylinder 5B to the cooling tank 11 and cured, the molten resin is introduced into the cutter device 13 and cut into a predetermined size to form a fiber-mixed pellet P2 in which the reinforcing fibers F2 are dispersed.

  Next, as shown in FIG. 4, the fiber-mixed pellets P2 are put into the hopper 17 of the same injection molding machine 15A as that used in the first molding method, and the screw 21 is rotated in the heating cylinder 19A to produce fibers. The mixed pellet P2 is melted and kneaded, and the molten resin is injected into the cavity 23a of the mold 23 to mold a resin injection molded product.

<Third molding method>
In this molding method, as shown in FIG. 5, the pellet molding process and the molded product molding process are continuously performed.

  First, as shown in FIG. 5, a thermoplastic resin (pellet) R and other additives (not shown) are added to a hopper 3C of a twin screw extruder 1C, and an aspect ratio is 1 to 5, Add 0.5 to 5% by weight of granular solid A having a diameter of 10 μm or less. The biaxial screw 7C is rotated in the heating cylinder 5C to melt and knead the thermoplastic resin (pellet) R, and the particulate solid A is mixed uniformly. In this kneading process, the roving F1-a is introduced into the heating cylinder 5C from the roving raw fabric F1 of the reinforcing fiber on the downstream side of the hopper 3C, and the roving F1-a is cut by the cut gear 25 provided on the outer periphery of the biaxial screw 7C. Is cut and defibrated, and the cut and defibrated reinforcing fibers are uniformly dispersed in the molten resin.

  Next, the molten resin is extruded into a heating cylinder 19C of an injection molding machine 15C connected to the biaxial extruder 1C by a connecting pipe 27 to advance the plunger 29, and the molten resin enters the cavity 23a of the mold 23. The resin injection molded product is molded by injection.

  In this way, the thermoplastic resin, which is a molding raw material of the resin injection molded product, has a granular solid A having an aspect ratio of 1 to 5, an average particle size of 10 μm or less, and a blending amount of 0.5 to 5% by weight. Since the reinforcing fibers are added, the above-mentioned granular solid A plays a role as a lubricant during kneading, etc., and even if the resin viscosity is high and the fiber length of the reinforcing fibers is relatively long, It is possible to suppress breakage and lengthen the fiber length in the resin injection molded product, and to injection mold a molded product having excellent physical properties, particularly strength and surface impact. Moreover, when using a twin-screw extruder with a strong kneading force, the reinforcing fiber is easily broken, but the addition of the granular solid A increases the effect of suppressing the breaking of the reinforcing fiber. Moreover, when the compounding amount of the reinforcing fiber is increased, the viscosity of the melt is rapidly increased and the fiber is broken and the fiber length is shortened. However, by adding the granular solid A, the reinforcing fiber can be used at a high concentration. This also leads to improved physical properties such as strength.

  In addition, since it is only necessary to specify the shape, size, and blending amount of the granular solid A, it is possible to injection-mold resin injection molded products with a general-purpose injection molding machine, and there is no need for extra equipment investment. The injection molded product can be used at low cost and the injection molding machine can be used efficiently.

  Furthermore, since it is not necessary to increase the molding temperature in order to lower the resin viscosity in consideration of fluidity, it is possible to eliminate the thermal deterioration of the thermoplastic resin and not to add an antioxidant for preventing the thermal deterioration. The cost can also be reduced.

  In particular, in the third molding method, the pellet molding step can be omitted as compared with the first and second molding methods, so that the production efficiency and energy efficiency can be improved by shortening the molding cycle. Moreover, since the raw material and the reinforcing fiber are kneaded and the injection molding of the resin injection molded product is performed directly on the spot, a biaxial extrusion process with a strong kneading force compared to the first molding method and the second molding method is required, When the twin screw extruder 1C having a strong kneading force is used, the reinforcing fibers are easily broken, but the addition of the granular solid A can increase the effect of suppressing the breaking of the reinforcing fibers.

  Further, since the granular solid A is composed of at least one selected from talc, calcium carbonate, titanium oxide, silica, zinc oxide and alumina, it is possible to easily obtain a granular solid having a low aspect ratio at a low cost. it can.

  Furthermore, since at least one selected from glass fiber, carbon fiber, rock wool, quartz fiber, metal fiber, whisker and aramid fiber is adopted as the reinforcing fiber, the fiber length in the resin injection molded product is reduced. As a result, it is possible to effectively increase strength and surface impact among physical properties.

  An experiment was conducted to demonstrate the above. The data is shown in Table 1.

  In Table 1, as the types of thermoplastic resins, “PP” refers to polypropylene, and “NY6” refers to polyamide-6.

  As the type of reinforcing fiber, “GF” refers to the glass fiber used in Examples 1 to 5 and Comparative Examples 1 to 6, and “CF” refers to Examples 6 to 10 and Comparative Examples 7 to 10. It is the carbon fiber used in.

  As the shape of the reinforcing fiber, the “columnar shape” is a form of the reinforcing fiber mixed in the resin injection molded product obtained by the first molding method. The “chopped shape” is a form of reinforcing fibers mixed in the resin injection molded product obtained by the second molding method. The “roving shape” is a form of reinforcing fibers mixed in the resin injection molded product obtained by the third molding method.

  In the fiber length distribution of the molded product, “short fibers” are those having a fiber length of less than 0.5 mm, “medium fibers” are those having a fiber length of 0.5 mm to 1 mm, and “long fibers” are fibers exceeding Are those exceeding 1 mm. Regarding the measurement of the fiber length, in “GF”, the resin in the molded product was removed by incineration, sieved to measure the weight, and then the fiber length was subjected to image analysis. With “CF”, sieving cannot be performed because it breaks during sieving. Therefore, the resin in the molded product was incinerated (dissolved and removed), and the fiber length was directly subjected to image analysis. Therefore, in Examples 6 to 10 and Comparative Examples 7 to 10 using CF, the fiber length weight distribution is not described in Table 1.

  In the physical properties of the molded product, “strength” means that a square plate (width: 100 mm, length: 420 mm, thickness: 3 mm) was molded by an injection molding machine, and this was subjected to a bending test in accordance with JIS K 7171. . As the evaluation, the mark ◎ is over 300 MPa, the mark ◯ is 300 to 250 MPa, the mark △ is less than 250 MPa to 150 MPa, and the mark X is less than 150 MPa.

Judgment: Good ← ◎>○> ○ ~ △>△> △ ~ ×> × → bad In the physical properties of the molded product, “surface impact” is a square plate (width: 100 mm, length: 420 mm, with an injection molding machine). (Thickness: 3 mm) was formed, and an iron weight having a weight of 3.8 kgf was dropped on the square plate at a room temperature, and the drop height when a crack occurred was measured. As the evaluation, the mark ◯ is over 50 cm, the mark Δ is 50 to 40 cm, and the mark x is less than 40 cm.

    Judgment: Good ← ○> ○ to △> △> △ to ×> × → Evil

  From this data, the following became clear.

<Examples 1 and 2 and Comparative Examples 1 to 4: The shape of the reinforcing fiber is columnar (first molding method)>
In Example 1, the aspect ratio of the granular solid is 4 and in the range of 1 to 5, the average particle size is 4.5 μm and 10 μm or less, and the blending amount is 0.5 to 5% and 0.5 to 5 Compared to Comparative Example 1, the proportion of short fibers in the molded product was as low as 19% by weight and the weight average fiber length was as long as 2.71 mm. In addition, the strength was improved from Δ to ○.

  In Example 2, the aspect ratio of the granular solid is 1 and in the range of 1 to 5, the average particle size is 0.1 μm and 10 μm or less, and the blending amount is 0.5 to 5% and 0.5 to 5 Compared with Comparative Example 1, the proportion of short fibers in the molded product was as small as 22% by weight and the weight average fiber length was as long as 2.85 mm. Further, the strength was improved to ○.

  This is because in Examples 1 and 2, the granular solid material plays the role of a lubricant during kneading and makes it difficult to break the reinforcing fibers.

  On the other hand, in Comparative Example 1, no granular solid was mixed, and the proportion of short fibers in the molded product was 43% by weight, which was larger than Examples 1 and 2, and the weight average fiber length was 1.88 mm. Although the surface impact property was good as ◯, the strength was Δ, which was worse than that of Examples 1 and 2. This is because there is no granular solid that acts as a lubricant during kneading and the reinforcing fibers are broken short.

  In Comparative Example 2, the aspect ratio of the granular solid is 4 and in the range of 1 to 5, and the average particle size is 4.5 μm and 10 μm or less, but the blending amount is 10 wt% and 0.5 to 5 wt. %, The proportion of short fibers in the molded product is as high as 35% by weight compared to Comparative Examples 1 and 2, and the weight average fiber length is 2.06 mm, compared with Examples 1 and 2. It was short, and both the strength and the surface impact property were bad as compared with Examples 1 and 2. This is because even if a granular solid serving as a lubricant is added, the blending amount is too large, so that the resin viscosity becomes high during kneading and the reinforcing fibers are broken short. In addition, a large amount of granular solids deteriorates the physical properties of the thermoplastic resin, particularly the surface impact property.

  In Comparative Example 3, the amount of the granular solid is in the range of 1.5 wt% and 0.5 to 5 wt%, but the aspect ratio is 12 and greatly exceeds the range of 1 to 5, Since the diameter greatly exceeds 15 μm and 10 μm, the proportion of short fibers in the molded product is very large at 50% by weight, the weight average fiber length is 1.60 mm, which is shorter than those in Examples 1 and 2, and the strength is high. Δ and surface impact were also bad with Δ. This means that even when a granular solid serving as a lubricant is added, both the aspect ratio and the average particle size are large, so that the lubricating function is not fully exhibited, and the resin viscosity becomes high during kneading. This is because the reinforcing fiber was broken shortly.

  In Comparative Example 4, the aspect ratio of the granular solid is 4 and in the range of 1 to 5, and the average particle size is 4.5 μm and 10 μm or less, but the blending amount is 0.4% by weight and 0.5 to 0.5%. Since it is below the range of 5% by weight, the proportion of short fibers in the molded product is as high as 42% by weight, the weight average fiber length is 1.86 mm, which is shorter than those in Examples 1 and 2, and the surface impact property is ○ Although it was good, the strength was Δ, which was worse than that of Examples 1 and 2. In addition, it is almost the same as Comparative Example 1 in which no granular solid is added, and even if a granular solid serving as a lubricant is added, since the blending amount is small, the resin viscosity is low during kneading. This is because the reinforcing fiber is not so high that the reinforcing fiber is broken shortly to exhibit the effect of adding the granular solid.

<Examples 3 and 4, Comparative Example 5: Reinforcing fiber has a roving shape (third molding method)>
In Example 3, the aspect ratio of the granular solid is 4 and in the range of 1 to 5, the average particle size is 4.5 μm and 10 μm or less, and the blending amount is 2% by weight and 0.5 to 5% by weight. The ratio of the short fibers in the molded product is as low as 20% by weight, the weight average fiber length is as long as 2.02 mm, the strength is Δ to ○, and the surface impact is good. It was.

  In Example 4, the aspect ratio of the granular solid is 4 and in the range of 1 to 5, the average particle size is 4.5 μm and 10 μm or less, and the blending amount is 4% by weight and 0.5 to 5% by weight. The ratio of short fibers in the molded product is as small as 20% by weight, the weight average fiber length is as long as 2.32 mm, the strength is Δ to ○, and the surface impact property is good. It was.

  This is because in Examples 3 and 4, the granular solid material plays the role of a lubricant during kneading and makes it difficult to break the reinforcing fibers.

  On the other hand, Comparative Example 5 does not contain any particulate solids, the proportion of short fibers in the molded product is very large at 49% by weight, the weight average fiber length is as short as 1.11 mm, and surface impact properties Although ◯ was good, the strength was △, which was worse than Examples 3 and 4. This is because there is no granular solid that serves as a lubricant during kneading, and the reinforcing fibers are broken short. Compared to the first molding methods of Examples 1 and 2 and Comparative Example 1, the third molding method having a twin-screw extruder having a large kneading force and the reinforcing fibers easily breaks is more granular. The effect of addition was large.

<Example 5, Comparative Example 6: The shape of the reinforcing fiber is chopped (second molding method)>
In Example 5, the aspect ratio of the granular solid is 1 and in the range of 1 to 5, the average particle diameter is 0.1 μm and 10 μm or less, and the blending amount is 0.5 to 5% and 0.5 to 5 Within the range of% by weight, the proportion of short fibers in the molded product is 63% by weight, which is larger than in Examples 1 to 4, and the weight average fiber length is 0.85 mm, which is shorter than in Examples 1 to 4. It was. Accordingly, both the strength and the surface impact property were Δ. However, Comparative Example 6 does not contain any particulate solid, and the proportion of short fibers in the molded product is 79% by weight, which is larger than that of Example 5, and the weight average fiber length is 0 as compared with Example 5. It was as short as .35 mm, and both the strength and the surface impact property were bad. This means that the granular solid plays the role of a lubricant during kneading and the like, and in Comparative Example 6 in which no granular solid is added, the reinforcing fiber breaks shorter than in Example 5. It is because it has stopped.

<Examples 6 and 7, Comparative Examples 7 and 8: Reinforcing fiber has a columnar shape (first molding method)>
In Example 6, the aspect ratio of the granular solid is 4 and in the range of 1 to 5, the average particle size is 4.5 μm and 10 μm or less, and the blending amount is 0.5 to 5% and 0.5 to 5 The weight average fiber length of the reinforcing fibers in the molded product was as long as 2.19 mm, the strength was good, and the surface impact properties were good to good.

  In Example 7, the aspect ratio of the granular solid is 1 and in the range of 1 to 5, the average particle size is 0.1 μm and 10 μm or less, and the blending amount is 0.5 to 5% and 0.5 to 5 The weight average fiber length of the reinforcing fibers in the molded product was as long as 2.30 mm, the strength was good, and the surface impact properties were good to good.

  This is because in Examples 6 and 7, the granular solid material plays the role of a lubricant during kneading and makes it difficult to break the reinforcing fibers.

  On the other hand, in both Comparative Examples 7 and 8, granular solids were not mixed, and the weight average fiber length of the reinforcing fibers in the molded product was 1.63 mm in Comparative Example 7 and 1.67 mm in Comparative Example 8. Although it was short and the strength was good as ◯, the surface impact property was △, which was worse than that of Examples 6 and 7. This is because there is no granular solid that serves as a lubricant during kneading, and the reinforcing fibers are broken short.

<Example 8, Comparative Example 9: The shape of the reinforcing fiber is chopped (second molding method)>
In Example 8, the aspect ratio of the granular solid is 1 and in the range of 1 to 5, the average particle size is 0.1 μm and 10 μm or less, and the blending amount is 0.5 to 5% and 0.5 to 5 Within the range of% by weight, the weight average fiber length of the reinforcing fibers in the molded product was 0.67 mm, which was shorter than in Examples 1-7. Accordingly, the strength was Δ and the surface impact property was Δ˜ ×. However, Comparative Example 9 does not contain any particulate solid, the weight average fiber length of the reinforcing fibers in the molded product is as short as 0.15 mm compared to Example 8, and both the strength and the surface impact property are x. It was a bad result. This means that the granular solid plays a role of a lubricant during kneading and the like, and in Comparative Example 9 in which no granular solid is added, the reinforcing fibers are broken shorter than in Example 8. It is because it has stopped.

<Examples 9 and 10, Comparative Example 10: Reinforcing fiber has a columnar shape (first molding method)>
In Example 9, the aspect ratio of the granular solid is 1 and in the range of 1 to 5, the average particle size is 0.1 μm and 10 μm or less, and the blending amount is 0.5 to 5% and 0.5 to 5 The weight average fiber length of the reinforcing fibers in the molded product was as long as 2.01 mm, the strength was excellent, and the surface impact property was good from ◯ to Δ.

  In Example 10, the aspect ratio of the granular solid is 1 and in the range of 1 to 5, the average particle size is 0.1 μm and 10 μm or less, and the blending amount is 1.5 to 5% by weight and 0.5 to 5 The weight average fiber length of the reinforcing fiber in the molded product was as long as 2.15 mm, the strength was excellent, and the surface impact property was good from ◯ to Δ.

  This is because in Examples 9 and 10, the granular solid material plays the role of a lubricant during kneading and makes it difficult to break the reinforcing fibers.

  On the other hand, Comparative Example 10 did not mix granular solids, the weight average fiber length of the reinforcing fibers in the molded article was as short as 1.61 mm, and the strength was good with ◎, but the surface impact property was △. Compared to Examples 9 and 10, the results were bad. This is because there is no granular solid that serves as a lubricant during kneading, and the reinforcing fibers are broken short.

  In addition, although both Examples 9 and 10 and Comparative Example 10 were the best in strength compared to other Examples and Comparative Examples, this was due to the physical properties of NY6 (polyamide-6) adopted as a thermoplastic resin. Is.

  The present invention is useful for a resin injection molded product in which reinforcing fibers are mixed and a molding method thereof.

It is a pellet formation process figure in the 1st forming method. FIG. 2 is a molded product molding process diagram using pellets molded in the pellet molding process of FIG. 1. It is a pellet formation process figure in the 2nd forming method. FIG. 4 is a molded product molding process diagram using pellets molded in the pellet molding process of FIG. 3. It is a molded article shaping | molding process figure in a 3rd shaping | molding method. It is a perspective view of the shroud attached to the radiator of a motor vehicle.

Explanation of symbols

1B, 1C Twin screw extruder 15A, 15C Injection molding machine 23 Mold A Granular solid F1-b Reinforcing fiber (columnar fiber bundle)
F2 Reinforcing fiber P1, P2 Fiber mixed pellet R Thermoplastic resin (pellet)
S shroud (resin injection molded product)

Claims (8)

A resin injection-molded product that is injection-molded with a thermoplastic resin mixed with reinforcing fibers and granular solids,
The granular solid is a resin injection molded product having an aspect ratio of 1 to 5, an average particle size of 10 μm or less, and a blending amount of 0.5 to 5% by weight. In the resin injection molded product according to claim 1,
The above-mentioned granular solid material is a resin injection molded product comprising at least one selected from talc, calcium carbonate, titanium oxide, silica, zinc oxide and alumina. In the resin injection molded product according to claim 1,
A resin injection molded article, wherein the reinforcing fiber comprises at least one selected from glass fiber, carbon fiber, rock wool, quartz fiber, metal fiber, whisker and aramid fiber. A molding method in which a resin injection molded article is injection molded with a thermoplastic resin mixed with reinforcing fibers and granular solids,
A pellet molding process for molding fiber-mixed pellets obtained by impregnating thermoplastic fibers into columnar fiber bundles of reinforcing fibers;
A molded product molding step in which the fiber-mixed pellet is put into an injection molding machine and melted, and the molten resin is injected into a mold to mold a resin injection molded product,
A solid addition step of adding 0.5 to 5% by weight of a granular solid having an aspect ratio of 1 to 5 and an average particle size of 10 μm or less at the time of the pellet forming step or the molded product forming step. A method for molding a resin injection molded product, comprising: A molding method in which a resin injection molded article is injection molded with a thermoplastic resin mixed with reinforcing fibers and granular solids,
Resin-mixed pellets obtained by adding 0.5 to 5% by weight of a granular solid having an aspect ratio of 1 to 5 and an average particle size of 10 μm or less to a thermoplastic resin and dispersing reinforcing fibers in a chopped strand state Pellet molding process to mold,
A resin injection molded product comprising: a molded product molding step of charging the resin-mixed pellets into an injection molding machine, melting the resin, and injecting the molten resin into a mold to mold a resin injection molded product Molding method. A molding method in which a resin injection molded article is injection molded with a thermoplastic resin mixed with reinforcing fibers and granular solids,
Reinforcing fibers in which a thermoplastic resin is introduced into a twin-screw extruder and 0.5 to 5% by weight of a granular solid having an aspect ratio of 1 to 5 and an average particle size of 10 μm or less is added. Is introduced into the twin-screw extruder and cut and defibrated in the kneading process of the thermoplastic resin and the granular solid, and then the molten thermoplastic resin mixed with the granular solid and the reinforcing fiber is injected into the injection molding machine. A method for molding a resin injection-molded product, characterized in that the resin injection-molded product is molded by being extruded into a mold by the injection molding machine. In the molding method of the resin injection molded product according to claim 4-6,
The method for molding a resin injection molded article, wherein the granular solid material comprises at least one selected from talc, calcium carbonate, titanium oxide, silica, zinc oxide and alumina. In the molding method of the resin injection molded product according to claim 4-6,
The method for molding a resin injection molded product, wherein the reinforcing fiber is composed of at least one selected from glass fiber, carbon fiber, rock wool, quartz fiber, metal fiber, whisker, and aramid fiber.

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