JP4514531B2 - A composition for molding a long fiber reinforced polyamide resin and a method for producing a molded body. - Google Patents

Description

  The present invention relates to a long fiber reinforced polyamide resin molding composition for producing a molded article excellent in mechanical strength, surface appearance, and the like, and a method for producing a molded article using the same.

  Conventionally, as a material for molding a long fiber reinforced thermoplastic resin, a material in which a reinforced fiber is impregnated with a thermoplastic resin as a matrix resin and made into a pellet is known. Further, as a method for producing a long fiber glass reinforced thermoplastic resin composition, a resin obtained by plasticizing and melting a matrix resin raw material with an extruder is filled into an impregnation die, and the resin is drawn out from a wound body or the like into the impregnation die. There is known a method in which a strand which is an aggregate of reinforced fibers, that is, filaments, is passed, and a continuous reinforcement obtained by shaping a resin-impregnated strand obtained by a nozzle is cut with a pelletizer to form pellets.

  In general, it is known that the mechanical strength of the long fiber reinforced thermoplastic resin molded product is improved as the reinforcing fiber content in the long fiber reinforced thermoplastic resin composition used for molding increases. On the other hand, the higher the reinforcing fiber content in the long fiber reinforced thermoplastic resin composition, the lower the resin component ratio to the reinforcing fiber, so that the resin impregnation property in the reinforcing fiber in the long fiber reinforced thermoplastic resin composition is inferior. It will be. Moreover, when molding this, there are problems that the plasticizing fluidity is lowered, the surface appearance of the resulting molded product is inferior, and that a lack of thickness occurs.

  The long fiber reinforced polyamide resin composition, which is one of the long fiber reinforced thermoplastic resin compositions, uses, for example, a polypropylene resin as a matrix resin by using a polyamide resin excellent in adhesion to glass fibers and impregnation properties. Compared to the long-fiber polypropylene resin composition to be made, glass fibers can be contained in a large amount by volume ratio, so that a high-strength molded product is obtained. In this case, a polyamide resin using nylon 66 is known in many cases.

  However, a molded article of the long fiber polyamide resin composition using nylon 66 is inferior in surface appearance although it is excellent in mechanical strength and heat resistance. As a long fiber reinforced polyamide resin composition for improving this, Patent Document 1 discloses (A) a polyamide resin obtained by blending 99 to 1% by weight of nylon 66 component and 1 to 99% by weight of nylon 6 component, B) It is disclosed that 5 to 80% by weight (in the composition) of a fibrous reinforcing material is blended, and the fibrous reinforcing material has a fiber length of 3 mm or more in the composition. In Patent Document 1, the reason that the surface appearance can be improved is that the polyamide resin, which is a matrix, is a blend of nylon 66 and nylon 6 component, thereby lowering the crystallization temperature of the matrix. It is explained that it is possible to slow down the crystallization speed and to improve the molding fluidity at the time of molding.

However, in the method of Patent Document 1, the matrix resin is still easily crystallized in the step of impregnating the fiber reinforcement with the matrix resin, and the use of expensive equipment for maintaining the temperature of the plasticizing and impregnation die at a high temperature is required. Needed. Furthermore, the matrix resin overflowing from the impregnation die and crystallizing has problems such as inhibiting the introduction of the fibrous reinforcing material into the impregnation die, causing breakage, and hindering continuous production.
JP-A-6-107944

  In view of the above problems in the prior art, the present invention uses expensive equipment necessary to maintain the temperature of the plasticizing and impregnation die at a higher temperature in the step of impregnating the fiber reinforcement with the matrix resin, and impregnation. It is an object of the present invention to provide a composition for melt molding in which problems relating to productivity due to inhibition of introduction and breakage of a fibrous reinforcing material caused by crystallization of a matrix resin at the time are eliminated.

  Another object of the present invention is to provide a method for producing a long fiber reinforced polyamide resin molded article having excellent mechanical strength and surface appearance, using the above-described melt molding composition.

  As a result of diligent research, the present inventor has made a long fiber reinforced polyamide resin pellet (A) containing polyamide 6 reinforced with a fibrous reinforcement and a resin pellet containing polyamide 66 that is not substantially reinforced with a fibrous reinforcement ( It was found that the object can be achieved by using as a molding material a composition containing B) and containing the resin pellet (A) and the resin pellet (B) in a specific ratio.

Thus, the present invention is characterized by having the following gist.
(1) and the long fiber-reinforced resin pellets containing polyamide 6 reinforced with fibrous reinforcing material (A), and a resin pellet containing polyamide 66 not reinforced substantially (B) fibrous reinforcing material, wherein the polyamide 6 MFR (melt flow rate: temperature 280 ° C., load 325 g) specified in JIS K7210 is 50 to 80 g / 10 min, the resin pellet (A) is impregnated with a long fibrous reinforcement with polyamide 6, and then cut A long fiber reinforced polyamide resin molding composition comprising 5 to 100 parts by mass of the resin pellet (B) with respect to 100 parts by mass of the resin pellet (A).
(2) The long fiber reinforced polyamide resin molding composition as described in (1) above, wherein the resin pellet (A) has a length of 3 to 20 mm .
(3) The composition for molding a long fiber reinforced polyamide resin according to the above (1) or (2), wherein the resin pellet (A) contains 30 to 70 parts by mass of a fiber reinforcing material with respect to 100 parts by mass of the resin pellet. .
(4) The composition for molding a long fiber reinforced polyamide resin according to any one of claims 1 to 3, wherein the resin pellet (B) contains 60 to 100 parts by mass of polyamide 66 per 100 parts by mass of the resin pellet (B). object.
(5) A long fiber reinforced resin pellet (A) impregnated with polyamide 6 in a fibrous reinforcing material and a resin pellet (B) containing polyamide 66 that is not substantially reinforced with a fibrous reinforcing material, the resin pellet (A) A method for producing a long fiber reinforced polyamide resin molded product, wherein the resin pellet (B) is molded into a composition containing 5 to 100 parts by mass with respect to 100 parts by mass.
(6) The long fiber reinforced polyamide resin according to the above (5), wherein the composition is injection molded, and a fibrous reinforcing material having a weight average fiber length of 3 mm or more is dispersed in the long fiber reinforced polyamide resin molded body. Manufacturing method of a molded object.

  By using the composition for melt molding according to the present invention, a long fiber reinforced polyamide resin excellent in mechanical strength and surface appearance can be obtained. That is, as shown in Examples and Comparative Examples described later, a molded article using the composition for melt molding according to the present invention is a conventional long fiber reinforced resin pellet containing a blend resin of polyamide 66 and polyamide 6, Compared to a molded product using a melt molding composition such as a long fiber reinforced resin pellet containing polyamide 66, the content of the fibrous reinforcing material and the matrix resin in the molded product is the same, but unexpected. In particular, a molded product having excellent surface appearance, mechanical strength and impact resistance can be obtained.

  Further, the long fiber reinforced resin pellet (A) in the present invention has a matrix 6 having a large molding fluidity and a good impregnation property to the fibrous reinforcing material, so that the fiber reinforcing material is impregnated at a low temperature. Can do. As a result, the equipment required to maintain the high temperature, which was necessary in the past, is no longer necessary, and the introduction of fiber reinforcement caused by crystallization of the matrix resin during impregnation into the impregnation die, productivity due to breakage, etc. The related problem is also solved.

  The melt molding composition of the present invention comprises a long fiber reinforced resin pellet (A) containing polyamide 6 reinforced with a fibrous reinforcing material, and a resin pellet (B) containing polyamide 66 that is not substantially reinforced with a fibrous reinforcing material. Containing.

  The content ratio of the long fiber reinforced resin pellet (A) and the resin pellet (B) in the composition for melt molding is important, and the content ratio is 100 parts by mass of the resin pellet (A). Is 5 to 100 parts by mass, preferably 10 to 100 parts by mass. When the resin pellet (B) is smaller than 5 parts by mass, the ratio of polyamide 6 in the melt-molding composition is increased, and although the processability and surface appearance of the molded product are excellent, the strength is reduced. On the other hand, when it is larger than 100 parts by mass, the ratio of polyamide 66 in the composition for melt molding becomes high and the strength of the molded product is excellent, but the processability and surface appearance are inferior, and the object of the present invention cannot be achieved.

  Examples of the fibrous reinforcing material in the long fiber reinforced resin pellet (A) include glass fiber, carbon fiber, metal fiber, and resin fiber. Of these, glass fiber is preferred from the viewpoints of processability, economy, and versatility of the molded body. The glass fibers are preferably used in the form of glass fiber bundles. The glass fiber bundle is made of glass fibers spun from a bushing. The glass fiber has a diameter of 6 to 23 μm, and preferably contains 100 to 5000 glass fibers in one fiber bundle. Furthermore, it is particularly preferable that the glass fiber has a diameter of 9 to 16 μm and contains 1000 to 4000 glass fibers in one fiber bundle.

  The glass fiber which is a fibrous reinforcing material may be treated with a surface treatment agent containing a coupling agent in order to improve the adhesion to the matrix resin. As the coupling agent, silane coupling agents such as aminosilane, epoxy silane, amide silane, azido silane, and acrylic silane, titanate coupling agents, or a mixture thereof can be used. Of these, aminosilane and epoxysilane are preferred, and aminosilane coupling agents are particularly preferred.

  The composition ratio of the fibrous reinforcing material and the polyamide 6 in the long fiber reinforced resin pellet (A) can be arbitrarily set, but the fibrous reinforcing material is preferably 30 to 70 parts by mass with respect to 100 parts by mass of the resin pellets. Particularly preferred is 35 to 60 parts by mass. If the amount of fibrous reinforcing material is less than 30 parts by mass, the strength of the molded body may be reduced. Further, when the amount of the fibrous reinforcing material is more than 70 parts by mass, the impregnation property to the fibrous reinforcing material is lowered, and the surface appearance of the molded body may be poor.

The polyamide 6 is a matrix resin of fiber-reinforced resin pellet (A), the homopolymer or copolymer can be used, you can use particular commercial polyamide 6. Polyamides 6, MFR defined in JIS K7210 (melt flow rate: temperature 280 ° C., load 325 g) is 50 to 80 g / 10min, good Mashiku the Ru 60~80g / 10min der. MFR impregnation property with 50 g / 10min smaller inferior in productivity, also, 80 g / 10min larger than mechanical strength ing a downward trend.

  As the matrix resin of the resin pellet (A), it is preferable that polyamide 6 is 100% from the viewpoint of melting and impregnation of the resin, but a thermoplastic resin equivalent to or lower than the MFR of polyamide 6 may be used. it can. Examples of the thermoplastic resin include polyamide 11, polyamide 12, and polypropylene. The thermoplastic resin is desirably 15% or less with respect to 100% by mass of the matrix resin (A).

  The resin pellet (A) is produced by impregnating a polyamide 6 into a fibrous reinforcing material. When glass fiber is used as the fibrous reinforcing material, the resin pellet (A) is preferably produced as follows. That is, using an impregnation die attached with an extruder, the polyamide 6 plasticized and melted by the extruder is fed into the impregnation die, and at the same time, the glass fiber bundle is passed through the impregnation die, thereby opening the opened glass. The fiber bundle is impregnated with polyamide 6. The impregnated glass fiber bundle is cooled by removing excess polyamide 6 with a die or the like at the exit of the impregnation die. Next, this is cut | disconnected to a desired magnitude | size with a pelletizer, and a resin pellet (A) is manufactured. The plasticizing and melting temperature by the extruder is preferably 250 to 300 ° C., and 270 to 290 ° C. is required to further improve the dispersibility of the glass fibers in the molded product and to further suppress the thermal deterioration of the polyamide 6. More preferred.

  In addition, when using the resin etc. which were illustrated above in addition to polyamide 6, they are melt-dissolved or melt-mixed, and then sent to an impregnation die by an extruder, and thereafter, resin pellets (A) are produced in the same manner as described above. Is done.

  The resin pellet (B) contained in the composition for melt molding of the present invention is made of polyamide 66 which is not substantially reinforced with a fibrous reinforcing material. Here, “substantially does not reinforce” does not play a role of reinforcement even if a fibrous reinforcing material is contained, for example, 3% by mass or less, particularly 1% by mass of the fibrous reinforcing material in the non-reinforced resin pellet. The following cases are included. As the polyamide 66 contained in the resin pellet (B), a commercially available polyamide 66 can be used as in the case of the polyamide 6 in the resin pellet (A), and other polyamide resins, mixtures with other polymers, or alloys. Can be used in combination. However, in the present invention, the content of the polyamide 66 in the resin in the resin pellet (B) is preferably 60% by mass or more, particularly preferably 80% by mass or more.

  As the resin pellet (B), a polyamide 66 or other resin selected as required may be melt-dissolved or melt-mixed and then cut into a desired size by a pelletizer. It can be used without melting, melting and mixing.

  The shape of the resin pellet (A) in the present invention is not particularly limited, but is preferably a columnar shape, and its length (size) is preferably 3 to 20 mm, particularly preferably 4 to. 12 mm. If the length of the resin pellet (A) is less than 3 mm, the resin pellet (A) is liable to break vertically, and problems such as fuzz due to damage to the fibrous reinforcing material occur. On the other hand, if the size exceeds 20 mm, the resin pellets (A) and the resin pellets (B) in the melt molding composition are classified, and the content of the fibrous reinforcing material in the molded product varies.

  The composition for melt molding in the present invention is prepared by mixing resin pellets (A) and resin pellets (B). The mixing method does not cause classification, and any method and equipment can be used as long as they can be mixed uniformly, but it is preferable to use an air mixing type or tumbler type mixer.

  The manufacturing method of the molded article in the present invention is performed using a melt-molding composition containing a long fiber reinforced resin pellet (A) and a resin pellet (B) that is not substantially reinforced with a fibrous reinforcing material. The molding method is not particularly limited, but preferably injection molding is used. In the present invention, it is preferable that the fibrous reinforcing material in the molded product is dispersed with a weight average fiber length of preferably 3 mm or more. In order to manufacture such a molded article, it is preferable to use a molding machine equipped with a screw having a deep groove and a nozzle having a large diameter.

  The melt molding composition of the present invention may contain an appropriate additive for imparting desired characteristics to the molded product within a range that does not significantly impair the object of the present invention. For example, antioxidants, stabilizers such as ultraviolet absorbers, antistatic agents, coloring agents such as dyes and pigments, lubricants, plasticizers, and inorganics such as glass flakes, glass powder, glass beads, mica, alumina and carbon powder An appropriate amount of the material may be blended. In addition, an appropriate amount of a compound selected from a lubricant such as a metal salt of a fatty acid, for example, a salt of a fatty acid and a metal such as lithium, which is effective for improving the fluidity of the melt-molding composition during molding and making the fibrous reinforcing material uniform. Can be blended. These additives may be added to the resin pellet (A) and / or the resin pellet (B), or may be added to the composition after mixing these components.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention should not be construed as being limited to such examples.

In the following, Example 1 is an example of the present invention, Examples 2 to 4 are comparative examples, and the fibrous reinforcing material, polyamide 6 and polyamide 66 used are as follows.
-Fibrous reinforcing material: Fiber bundle made of 4000 glass fibers having a diameter of 16 µm-Polyamide 6: Nylon 6 (shape: 2 mm long pellet, MFR: 70 g / 10 min)
Polyamide 66: Nylon 66 (shape: 2 mm long pellet, MFR: 25 g / 10 min)

  Using the above-mentioned materials, a melt molding composition containing long fiber reinforced resin pellets and resin pellets was produced by the method described below, and a molded product was obtained by injection molding using these melt molding compositions. . Table 1 shows the materials used in the production, the composition (parts by weight), the temperature in the production of long fiber reinforced resin pellets, the impregnation of the fibrous reinforcement, the evaluation of productivity, the surface appearance of the molded product, and the tensile strength. The evaluation results of bending strength, bending elasticity, and impact resistance are summarized.

Production of long fiber reinforced resin pellets:
While the glass fiber bundle of the fibrous reinforcing material is opened and drawn with an impregnation die, plasticized with an extruder, melted and infiltrated into the fibrous reinforcing material with the polyamide melt fed into the impregnation die, It was taken as a strand through a shaping die, cooled, and cut to a length of 12 mm with a pelletizer.
The plasticizing and melting temperatures are 290 ° C. for Example 1 and 310 ° C. for Examples 2, 3 and 4.

Production of resin pellets:
The above-mentioned commercially available polyamide 6 and polyamide 66 pellets were used.
Manufacture of a composition for melt molding containing fiber reinforced resin pellets and resin pellets:
The long fiber reinforced resin pellets produced above and the resin pellets were mixed using a tumbler-type mixer under a mixing time of 5 minutes.

Molded body production:
The fiber reinforced resin pellet or melt molding composition obtained above was injection molded under the conditions of a cylinder temperature of 310 ° C., an injection speed of 13 mm / sec, and an injection pressure of 145 MPa, to prepare a test piece having a thickness of 4 mm.
Evaluation:
a. Manufacture of long fiber reinforced resin pellets ・ Productivity:
In the same production facility, the number of occurrences of inhibition and breakage of the fibrous reinforcing material introduced into the impregnation die was evaluated as superior or inferior. (◎ indicates excellent, ○ indicates good, △ indicates slightly inferior, × indicates inferior)
・ Impregnation properties;
The long fiber reinforced resin pellet is dipped in the red water-based ink for 1 minute, and the penetration of the ink is visually confirmed. Inks with excellent impregnation properties do not soak ink, while those with poor impregnation properties soak ink in many areas. (◎ indicates excellent, ○ indicates good, △ indicates slightly poor, and × indicates poor)
b. Molded product surface appearance; visual tensile strength; compliant with JIS-K-7161 (unit: MPa)
Bending strength: Conforms to JIS-K-7171 (Unit: MPa)
Flexural elasticity is compliant with JIS-K-7171 (unit: MPa)
Impact resistance evaluation: Conforms to JIS-K-7110 (Unit: KJ / m ² )

（注） ＧＣ％：ガラス繊維含有率で、単位は質量％である。

(Note) GC%: Glass fiber content, unit is mass%.

As is apparent from Table 1, Example 1 which is an example of the present invention does not require high temperature for production compared to Examples 2 to 4 which are comparative examples, and impregnation into a fibrous reinforcement. Is good and has excellent productivity.
Furthermore, as for the molded product, Example 1 which is an example of the present invention has a better surface appearance and is superior in strength and impact resistance as compared with Examples 2 to 4 which are comparative examples.

Claims (6)

A long fiber reinforced resin pellet (A) containing polyamide 6 reinforced with a fibrous reinforcing material, and a resin pellet (B) containing polyamide 66 that is not substantially reinforced with a fibrous reinforcing material, and the polyamide 6 is JISK7210 Specified MFR (melt flow rate: temperature 280 ° C., load 325 g) is 50 to 80 g / 10 min, and the resin pellet (A) is produced by impregnating a long fibrous reinforcement with polyamide 6 and then cutting. A long fiber reinforced polyamide resin molding composition comprising 5 to 100 parts by mass of the resin pellet (B) with respect to 100 parts by mass of the resin pellet (A). The composition for molding a long fiber reinforced polyamide resin according to claim 1, wherein the length of the resin pellet (A) is 3 to 20 mm . The long fiber reinforced polyamide resin molding composition according to claim 1 or 2, wherein the resin pellet (A) contains 30 to 70 parts by mass of a fibrous reinforcing material with respect to 100 parts by mass of the resin pellet. The composition for long fiber reinforced polyamide resin molding according to any one of claims 1 to 3, wherein the resin pellet (B) contains 60 to 100 parts by mass of polyamide 66 per 100 parts by mass of the resin pellet (B). 100 mass of the said resin pellet (A) including the long fiber reinforced resin pellet (A) which impregnated the polyamide 6 in the fibrous reinforcement, and the resin pellet (B) containing the polyamide 66 which is not substantially reinforced with a fibrous reinforcement. A method for producing a long fiber reinforced polyamide resin molded product, wherein a composition containing 5 to 100 parts by mass of the resin pellet (B) is molded with respect to a part. 6. The production of a long fiber reinforced polyamide resin molded product according to claim 5, wherein the composition is injection molded, and a fibrous reinforcing material having a weight average fiber length of 3 mm or more is dispersed in the long fiber reinforced polyamide resin molded product. Method.