JP2008150414A - Lightweight fiber reinforced resin composition having excellent impact resistance and molded article comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber reinforced resin molded article excellent in impact resistance and bending properties despite being light weight with a density of 1000 kg / m ³ or less.
SOLUTION: A cut yarn of vinylon short fiber is contained in a modified polypropylene resin, and a Charpy impact strength of a notched test piece is 8.5 kJ / m ² or more, a three-point bending strength is 45 MPa or more, and a density is 1000 kg / m. ³ or less vinylon fiber reinforced resin composition and a molded article comprising the same.
[Selection figure] None

Description

  The present invention relates to a resin composition in which a shortcut yarn of vinylon fiber is contained in a polypropylene resin, and a fiber-reinforced resin molded article obtained by molding the resin composition.

Conventionally, a thermoplastic resin molded body reinforced with glass fiber is frequently used because of its excellent reinforcement performance.
However, in recent years, the weight reduction of the vehicle body has become an important issue in order to reduce fuel consumption and improve acceleration performance of automobile materials. Since the thermoplastic resin molded body reinforced with glass fiber has a high glass density, when it is contained in an amount of 20% by weight or more, the density becomes 1000 kg / m ³ or more. There was a problem. Further, when the molded body is discarded, there is a problem that the detached glass fiber is scattered and the skin is tinged, and there is a problem that the furnace is easily damaged because incineration is difficult.

As an alternative to the glass fiber as described above, it is focused on a short fiber of organic fiber with a sizing agent, cut into a bundled yarn, and further compounded with a thermoplastic resin to obtain a fiber reinforced thermoplastic resin. Has been used (see, for example, Patent Documents 1 to 6).
However, even if these methods are used, a fiber-reinforced thermoplastic resin and a molded body satisfying the three important performances of strength, impact resistance and light weight in a well-balanced manner have not been obtained.

JP 7-251437 A JP-A-9-267327 JP-A-48-042035 JP-A-8-336879 Japanese Patent Laid-Open No. 2002-060502 JP-A-7-080834

The present invention has been made in view of such a problem. A fiber-reinforced resin composition and a molded body having excellent impact resistance and bending strength despite a lightweight density of 1000 kg / m ³ or less. The purpose is to provide.

  As a result of intensive studies to solve the above problems, the present inventors used a shortcut yarn made of vinylon fiber as a reinforcing fiber, and without attaching an excessive sizing agent to the shortcut yarn of many vinylon fibers. By coating with polypropylene resin and molding using a resin composition cut into pellets, it was found that the resulting molded product has excellent impact resistance and bending properties despite being lightweight, The present invention has been completed.

That is, in the present invention, a vinylon fiber shortcut yarn is contained in a polypropylene resin, and a Charpy impact strength of a notched test piece is 8.5 kJ / m ² or more, a three-point bending strength is 45 MPa or more, and a density is 1000 kg / m. It is a fiber reinforced resin composition having a fiber reinforced resin composition of ³ or less, preferably the above fiber reinforced resin composition in which a short cut yarn of vinylon fiber is contained in 10 to 35% by mass of polypropylene resin, more preferably the above resin. It is a fiber reinforced resin molded article made of the composition.

In the resin composition of the present invention, the short-cut yarns of vinylon fibers are covered with polypropylene resin to protect them, so that there is no damage in the molding process and there are few entanglements of fibers during processing. In addition, it can be suitably used to produce pellets by compounding with colorants, fillers, flame retardants, pigments, extenders, inorganic fillers, etc., and it does not require a sizing agent or the like in the reinforcing fiber during molding. The dispersibility of the fibers is good, and a high-quality molded product can be formed. Specifically, the resin composition containing the vinylon fiber shortcut yarn of the present invention in a polypropylene resin has a Charpy impact strength of 8.5 kJ / m despite being lightweight with a density of 1000 kg / m ³ or less. ^Since it has a high performance of ² or more and 3-point bending strength of 45 MPa or more, when it is formed into a molded body, it is possible to reduce the weight and thickness. Furthermore, since the impact resistance and bending properties are improved by the content of the vinylon shortcut yarn, the physical properties can be freely controlled according to the application.

The vinylon fiber used as a shortcut yarn for reinforcement in the present invention may be a vinylon fiber bundle formed by converging a large number of filament yarns, or a yarn added with twist, as long as it is a continuous fiber in form. . The fiber diameter of the reinforcing fibers constituting the reinforcing fiber bundle and the number of filaments are not particularly limited, but the fiber diameter is preferably 3 to 200 μm, more preferably 5 to 20 μm, while the number of filaments is 500 to 10,000. The number is preferably 500 to 4000.
As will be described later by using vinylon fiber as the reinforcing fiber, the obtained fiber-reinforced resin composition and molded product are conventional glass fibers, general-purpose organic fibers such as inorganic filler, polyester, nylon, and high-strength fibers such as aramid fibers. It has reinforcement performance such as impact resistance and bending characteristics that could not be achieved by reinforcement using the above.

  The method for producing the vinylon fiber used in the present invention is not particularly limited, but a spinning stock solution prepared by dissolving a polyvinyl alcohol polymer in water or an organic solvent contains water or an organic solvent having a solidifying ability with respect to polyvinyl alcohol. The fibers are preferably produced in the solidification bath by a wet spinning method or a dry and wet spinning method. The wet spinning method is a method in which the spinning stock solution is discharged directly from the spinneret into the solidification bath, while the dry and wet spinning method is a method in which the spinning stock solution is temporarily discharged from the spinneret into air or an inert gas. And then into the solidification bath. The constitution of the vinylon fiber used in the present invention is not particularly limited, but in terms of mechanical properties, heat resistance, etc., the average degree of polymerization is preferably 1000 or more, more preferably 1200 or more, and 5000 or less, particularly 4000 or less. preferable. For the same reason, the degree of saponification is preferably 99 mol% or more, particularly 99.8 mol% or more. The vinyl alcohol polymer constituting the fiber may be modified by other components or may be copolymerized.

As a method for improving the fuel efficiency of automobiles, it is required to reduce the weight of the vehicle body. Therefore, the molded body is a low-density material and requires the same impact strength and bending strength as the conventional product, or even if the density is the same, the impact strength is several times that of the conventional product. In addition, it is required to reduce the thickness by using a material having bending strength.
In the present invention, the resin composition containing the vinylon fiber shortcut yarn in the polypropylene resin has a Charpy impact strength of 8.5 kJ / m for the notched test piece, although the density is 1000 kg / m ³ or less and light weight. It is possible to achieve ^two or more and a three-point bending strength of 45 MPa or more. Here, when the Charpy impact strength is lower than 8.5 kJ / m ^2, it cannot be used for applications requiring impact resistance. Preferably 10 kJ / ^{m 2} or more, more preferably 15 kJ / ^{m 2} or more 50 kJ / ^{m 2} or less. The density of the molded body is required to be 1000 kg / m ³ or less from the viewpoint of reducing the weight of the material, preferably 990 kg / m ³ or less, more preferably 970 kg / m ³ or less.

It is important that the polypropylene resin to be used is a resin composed of a normal homopolypropylene polymer, and examples thereof include, but are not limited to, high polymers and low polymers. These polypropylene resins may be used in combination and mixed, and an appropriate amount of colorant, filler, flame retardant, etc. may be added to these polypropylene resins. Moreover, when an inorganic filler etc. are contained as a 3rd component, although impact resistance falls, high bending strength is obtained, maintaining high impact resistance by containing the shortcut yarn of a vinylon fiber. The inorganic filler to be used is not particularly limited, but is preferably mica, and more preferably has a high aspect ratio and a flake shape. Further, the amount of mica added to the polypropylene resin is preferably 1 to 15% by mass and more preferably 2 to 15% by mass in order to make the density of the resulting resin composition 1000 kg / m ³ or less. .

  In the resin composition containing the vinylon fiber shortcut yarn of the present invention in the polypropylene resin, the polypropylene resin is peeled off when the polypropylene resin is bonded to the continuous fiber located on the outer periphery of the fiber bundle made of the vinylon shortcut yarn. It becomes difficult. Accordingly, it is possible to prevent troubles such as the polypropylene resin being peeled off from a fiber bundle made of vinylon fiber shortcut yarns in a step of cutting the resin composition using a rotary type cutting machine or a guillotine type cutting machine.

  Next, the manufacturing method of the resin composition in which the shortcut yarn of the vinylon fiber of this invention contained in the polypropylene resin is demonstrated. The present invention provides a core sheath having a cylindrical passage for extruding a molten polypropylene resin so as to surround the fiber bundle in a state where a large number of vinylon fiber bundles are running, and passing the polypropylene resin around the extruded polypropylene resin. More preferred is a method in which a vinylon fiber is passed through a core part using a spinning nozzle of a type, and a polypropylene resin is contacted with the outer periphery of the vinylon fiber bundle under pressure from a sheath part to coat the fiber with the polypropylene resin. A method of coating the fibers with the resin by melting and bundling the resin after the discharged resin and a large number of vinylon fibers are bonded together is not particularly limited.

Next, after the resin composition containing the vinylon fiber bundle contained in the polypropylene resin and the polypropylene resin were mixed by a method such as chip blending, a strand was produced by a method such as extrusion with a melt extruder or injection molding. Thereafter, it is cut into pellets containing a vinylon fiber shortcut yarn in a polypropylene resin. Examples of the cutting method include a cutting method using a rotary cutting machine, a guillotine cutting machine, and the like, but are not particularly limited.
The length of the pellet obtained by the above-described cutting method is 2 to 2 from the viewpoint of kneadability when producing a molded body by a method such as subsequent extrusion with a melt extruder or injection molding, and dispersibility of reinforcing fibers. The length is preferably 15 mm, and more preferably 3 to 10 mm.
Moreover, it is preferable that the shortcut thread of vinylon fiber is 10-35 mass% in polypropylene resin. If the content of the shortcut yarn is less than 10% by mass, the intended impact resistance and bending characteristics may not be obtained. On the other hand, when the content of the shortcut yarn is more than 35% by mass, the dispersibility of the fibers in the resin is deteriorated. More preferably, it is 15-33 mass%, More preferably, it is 20-30 mass%.
Furthermore, it is more preferable when the obtained pellets are dried with a hot air dryer or the like to lower the moisture content in the pellets when extruding with a melt extruder or injection molding.

A molded body is obtained by molding the pellets obtained by the method as described above by a molding method such as melt extrusion or injection molding. The molded body obtained in this way could not be achieved with conventional glass fiber, inorganic filler, general-purpose organic fibers such as polyester and nylon, or thermoplastic resin molded bodies reinforced with high-strength fibers such as aramid fibers. In spite of being light weight with a density of 1000 kg / m ³ or less, it has excellent reinforcing performance in impact resistance, bending characteristics, and the like.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the present invention, Charpy impact strength, three-point bending strength, and density mean those measured by the following measuring methods.

[Charpy impact strength kJ / m ² ]
Using a digital impact tester “DG-CB” manufactured by Toyo Seiki Co., Ltd., the Charpy impact strength of the notched specimen was measured according to the JIS K7111 test method.

[3-point bending strength MPa]
It was measured according to JIS K7171 test method using Shimadzu Corporation autograph AG / R.

[Density kg / m ³ ]
Using an electronic hydrometer SD-120L manufactured by Mirage Trading Co., Ltd., the measurement was performed according to the JIS K7112 test method.

[Example 1]
(1) Use of Kuraray Co., Ltd. “5501-2” (fiber diameter: 14 μm, number of filaments: 2000) as the vinylon filament, and Prime Polymer Co., Ltd. polypropylene “Y-2005GP” as the polypropylene resin passes the yarn. A vinylon fiber having a nozzle inner diameter of 0.95 mm, a nozzle having an inner diameter of 1.20 mm from which the resin is extruded, a spinning head temperature of 200 ° C., a polypropylene resin discharge rate of 12 g / min, and a winding speed of 15 m / min. A resin composition obtained by coating the outer periphery of the bundle with a polypropylene resin was obtained.
(2) The resin composition obtained in the above (1) was cut and the cross section was observed with an electron microscope “S510” manufactured by Hitachi, Ltd. at a magnification of 100 times. As a result, the resin surrounded the vinylon fiber bundle. The resin was adhered to the continuous fibers on the outer periphery of the vinylon fiber bundle. Further, when the coated polypropylene resin was peeled off and the inner vinylon fiber bundle was observed, the inner vinylon fiber was not damaged, and therefore the vinylon fiber was not damaged in the step (1). The obtained resin composition was flexible.
(3) Further, the resin composition obtained in (1) is cut with a cutter, and the resin composition and the same polypropylene (Y-2005GP) manufactured by Prime Polymer Co., Ltd. as in (1) above have a vinylon content of 10 The chips were blended so as to be in mass%, strands were produced with an extruder, and cut into pellets by 4 mm with a pelletizer. Using the pellets thus obtained, an injection molding machine (“M-100C” manufactured by Meiki Seisakusho Co., Ltd., clamping force 100 tons) has a cylinder temperature of 200 ° C., a mold temperature of 40 ° C., and an injection time of 10 seconds. A vinylon fiber reinforced resin molded product was molded under the condition of a cooling time of 33 seconds, and performance evaluation was performed. The results are shown in Table 1.

[Example 2]
A pellet was prepared in the same manner as in Example 1 except that the vinylon content was 20% by mass. Using this pellet, a vinylon fiber reinforced resin was used under the same conditions as in Example 1 using the same injection molding machine as in Example 1. Molded bodies were molded and performance evaluation was performed. The results are shown in Table 1.

[Example 3]
A pellet was prepared in the same manner as in Example 1 except that the vinylon content was 30% by mass. Using this pellet, a vinylon fiber reinforced resin was used under the same conditions as in Example 1 using the same injection molding machine as in Example 1. Molded bodies were molded and performance evaluation was performed. The results are shown in Table 1.

[Example 4]
A resin composition was prepared in the same manner as in Example 1, and the obtained resin composition and polypropylene “Y-2005GP” manufactured by Prime Polymer Co., Ltd. and Kuraray Co., Ltd. mica “Kuralite Mica 200-D” each contained vinylon. Chip blending is performed so that the rate is 5% by mass and the mica content is 14% by mass, and a strand is produced by an extruder, and is cut into a pellet of 4 mm by a pelletizer. A vinylon fiber reinforced resin molding was molded under the same conditions as in Example 1 using the same injection molding machine as in Example 1, and performance evaluation was performed. The results are shown in Table 1.

[Comparative Example 1]
Using a polypropylene “Y-2005GP” manufactured by Prime Polymer Co., Ltd., to which no vinylon fiber was added, a molded body was molded under the same conditions as in Example 1 using the same injection molding machine as in Example 1, and performance evaluation was performed. . The results are shown in Table 1. As shown in Table 1, in the performance of the resin to which no vinylon fiber was added, the impact resistance was low.

[Comparative Example 2]
(1) Polyester fiber “E-721” (fiber diameter: 21 μm, number of filaments: 384) manufactured by Unitika Co., Ltd. instead of vinylon fiber filament, polypropylene “Y-2005GP” manufactured by Prime Polymer Co., Ltd. as a thermoplastic resin Using a nozzle having an inner diameter of 0.75 mm through which the yarn passes, an inner diameter of 0.86 mm of the nozzle through which the resin is extruded, a spinning head temperature of 200 ° C., a discharge amount of polypropylene resin of 6 g / min, and a winding speed of 9 m / min A resin composition obtained by coating the outer periphery of a polyester reinforcing fiber bundle with a polypropylene resin under the conditions described above was obtained.
(2) The resin composition obtained in the above (1) is cut with a cutter, and the resin composition and the same polypropylene polymer “Y-2005GP” manufactured by Prime Polymer Co., Ltd. as in the above (1) have a polyester fiber content of 10. Chip blending was carried out so that the mass% would be, and a strand was produced with an extruder, cut into 4 mm with a pelletizer and pelletized, and further using this pellet in the same injection molding machine as in Example 1. A fiber-reinforced resin molded body was molded under the same conditions as in No. 1, and performance evaluation was performed. The results are shown in Table 1.
(3) As shown in Table 1, the obtained molded product did not have satisfactory performance in both impact and bending strength.

[Comparative Example 3]
Asahi Fiber Glass Co., Ltd. chopped strand “Glaslon 03JAFT17” and Prime Polymer Co., Ltd. polypropylene “Y-2005GP” are chip-blended so that the glass fiber content is 20% by mass, and a strand is produced by an extruder. Then, a fiber reinforced resin molded product is molded under the same conditions as in Example 1 on the same injection molding machine as in Example 1 using this pellet and pelletized. It was. The results are shown in Table 1. As shown in Table 1, by adding twice as much fiber as in Example 1 in the obtained molded product, the bending strength was equivalent to that in Example 1, but the impact resistance was Charpy impact. The strength was 3.8 kJ / m ² and was insufficient.

[Comparative Example 4]
(1) Instead of vinylon filament, aramid fiber “TYPE 956” (fiber diameter: 14 μm, number of filaments: 2000) manufactured by DuPont Toray Kevlar Co., Ltd. Polypropylene “Y-2005GP” manufactured by Prime Polymer Co., Ltd. is used as the polypropylene resin. The nozzle having an inner diameter of 0.75 mm through which the yarn passes, an inner diameter of 1.16 mm of the nozzle through which the resin is extruded has a spinning head temperature of 200 ° C., a polypropylene resin discharge rate of 12 g / min, and a winding speed of 15 m / min Under the conditions, a resin composition in which the outer periphery of the aramid fiber bundle was coated with a polypropylene resin was obtained.
(2) The resin composition obtained in (1) above is cut with a cutter, and the resin composition and the same polypropylene polymer “Y-2005GP” manufactured by Prime Polymer Co., Ltd. as in (1) above have an aramid fiber content of 10 Chip blending is carried out so as to be mass%, and a strand is produced with an extruder, cut into a pellet of 4 mm with a pelletizer, pelletized, and further using this pellet in the same injection molding machine as in Example 1, the cylinder temperature A fiber reinforced resin molded article was molded under the conditions of 230 ° C., mold temperature of 40 ° C., injection time of 10 seconds, and cooling time of 33 seconds, and performance evaluation was performed. The results are shown in Table 1.
(3) As shown in Table 1, the Charpy impact strength of the obtained molded product was 4.7 kJ / m ² , and satisfactory impact resistance was not obtained.

[Comparative Example 5]
A pellet was prepared in the same manner as in Comparative Example 4 except that the aramid fiber content was 20% by mass, and this pellet was used in the same injection molding machine as in Example 1 under the same conditions as in Comparative Example 4. Molded bodies were molded and performance evaluation was performed. The results are shown in Table 1. The Charpy impact strength of the obtained molded product was 6.2 kJ / m ² , and satisfactory impact resistance was not obtained.

[Comparative Example 6]
A pellet was prepared in the same manner as in Comparative Example 4 except that the aramid fiber content was 30% by mass, and this pellet was used in the same injection molding machine as in Example 1 under the same conditions as in Comparative Example 4. Molded bodies were molded and performance evaluation was performed. The results are shown in Table 1. The Charpy impact strength of the obtained molded product was 7.2 kJ / m ² , and satisfactory impact resistance was not obtained.

[Comparative Example 7]
(1) An ethylene-vinyl acetate copolymer resin containing 7% by mass of an ethylene component has an emulsion concentration of 55% by mass and 7% of a nonionic surfactant as a protective colloid with respect to the ethylene-vinyl acetate copolymer resin. % Emulsion ("Puraflex OM-5000" manufactured by Kuraray Co., Ltd. was diluted with water to a concentration of 8% by mass. Next, the same vinylon fiber bundle as in Example 1 was passed through the diluted solution, dried, and then cut length. A vinylon fiber chopped strand having an ethylene-vinyl acetate copolymer resin adhesion amount of 2.7% by mass was cut to 3 mm.
(2) The chopped strand obtained in the above (1) was chip-blended with the same polypropylene polymer “Y-2005GP” manufactured by Prime Polymer Co., Ltd. as in Example 1 so that the vinylon fiber content was 30% by mass. Using the same injection molding machine as in Example 1, a vinylon fiber reinforced resin molded product was molded under the same conditions as in Example 1, and performance evaluation was performed. The results are shown in Table 1.

As shown in Examples 1 to 4 of Table 1, the fiber reinforced resin molded product obtained by pelletizing a resin composition containing the vinylon fiber of the present invention in polypropylene resin and injection-molding using this pellet has a density of Despite being as light as 1000 kg / m ³ or less, both impact resistance and bending strength are superior to conventional fiber-reinforced resin molded bodies.
On the other hand, a molded product to which the reinforcing fiber of Comparative Example 1 is not added, and a fiber reinforced resin molded product obtained by pelletizing a resin composition using polyester fiber in the reinforcing fiber of Comparative Example 2 and injection-molding using the pellet are Both impact properties and bending strength are inferior to the vinylon fiber reinforced resin molded product of the present invention. Further, the resin composition using the glass fiber of Comparative Example 3 and the aramid fiber of Comparative Examples 4 to 6 are pelletized, and these pellets are used. The injection-molded fiber reinforced resin molded product was inferior in impact resistance to the vinylon fiber reinforced resin molded product of the present invention.
Further, since the vinylon fiber reinforced resin molded article using the chopped strand in which the bundle of vinylon fibers is impregnated into the bundling agent as in Comparative Example 7 is poor in dispersibility of the vinylon fibers in the resin, the vinylon fibers of the present invention Both impact resistance and bending strength were inferior compared to the reinforced resin molding.

In the resin composition of the present invention, the polypropylene fiber covers and protects the reinforcing fiber bundle composed of a large number of continuous fibers, and has an appropriate flexibility. However, the fiber-reinforced resin molded product obtained can be suitably used for producing pellets for fiber-reinforced polypropylene resin molded products, and a sizing agent is not required for the reinforcing fibers at the time of molding. It has the feature that a high-quality fiber-reinforced resin molding can be molded. In addition, the manufacturing process is simple, it can be manufactured at low cost, and the productivity is good. In addition, since it is a fiber-reinforced resin molded product that does not contain glass fibers, it can be incinerated, and there is no need to bury the molded product.
The fiber-reinforced resin molded body of the present invention having the above-described features can be used for bumpers, fenders, spoilers, aero parts, console boxes, etc. in automobile applications, as well as fiber reinforcement formed by helmets and other injection molding machines. It can also be used for resin molding applications.

Claims (3)

A fiber in which a shortcut yarn of vinylon fiber is contained in a polypropylene resin, and a Charpy impact strength of a notched test piece is 8.5 kJ / m ² or more, a three-point bending strength is 45 MPa or more, and a density is 1000 kg / m ³ or less. Reinforcing resin composition.   The fiber-reinforced resin composition according to claim 1, wherein the vinylon fiber shortcut yarn is contained in 10 to 35 mass% polypropylene resin.   A fiber-reinforced resin molded article comprising the resin composition according to claim 1.