JP3303074B2 - Molded article of long fiber reinforced polyamide resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyamide resin composition reinforced with long fibers and a molded article thereof. More specifically, a long-fiber reinforced polyamide resin composition having less problems such as smoke generation and gas generation at the time of resin purging during molding, and a molded article obtained by molding the same, having high mechanical strength and less occurrence of burning during molding. Related to molded products.

[0002]

2. Description of the Related Art As means for improving the strength of polyamide resin, it is known to incorporate a fibrous reinforcing material such as glass fiber.
Generally, a fiber reinforced polyamide resin composition is produced by mixing a polyamide resin and short fibers such as chopped strands and extruding the mixture with an extruder. However, according to this method, breakage of the fiber during kneading in the extruder is inevitable, so that it is not possible to meet the demand for higher mechanical strength and the like. On the other hand, in recent years, as a method for fully bringing out the inherent performance of the fibrous reinforcement compounded,
Consideration has been given to reinforcing polyamide resins with long fibers. Such a long fiber reinforced polyamide resin, for example,
It can be obtained by a method of impregnating with a polyamide resin emulsion, solution or melt while pulling continuous reinforcing fibers. However, such a long-fiber-reinforced polyamide resin has problems such as intense smoke or gas generation during molding or purging of the resin. In addition, when molding is performed using such a material, the molded product may be burned to impair the appearance or the strength of the molded product may not be sufficiently improved. Such smoke, gas generation, or burning of a molded product is a problem peculiar to a polyamide resin reinforced with long fibers, and such a phenomenon occurs in a polyamide resin not reinforced with fibers and a polyamide resin reinforced with short fibers. Does not substantially occur, and there is no practical problem.
Although the polyamide resin reinforced with long fibers has essentially excellent mechanical strength and the like, its moldability is not always sufficient, and improvement thereof has been desired.

[0003]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the monomer / oligomer remaining in the polyamide resin is specific to the polyamide resin reinforced with long fibers. Have been found to have an adverse effect on the present invention, and have reached the present invention. That is, the present invention relates to (A) Nylon 6, Nylon 66, having a residual monomer and oligomer content of 3% by weight or less as measured by the measurement method described in the present specification .
Nylon 11, Nylon 12, Nylon 6,10, Nylon 6
-At least one polyamide resin selected from 12 ;
(B) Fibrous reinforcement 5 to 80% by weight
(In the composition), wherein the fibrous reinforcing material (B) is substantially the same length as the pellets and is arranged in parallel to the length direction of the resin pellets in the form of pellets having a length of 3 to 50 mm. The present invention relates to an injection molded article obtained by injection molding a reinforced polyamide resin composition, wherein a fibrous reinforcing material is dispersed in the injection molded article at a weight average fiber length of 1 mm or more.

Hereinafter, the present invention will be described in detail. In general, polyamide resin is inevitable in the production method, the unreacted monomer and low molecular weight oligomer remain, and the present inventor measured the amount of residual monomer and oligomer in various polyamide resins by the following method. 6 to 10
It was found that at least 3% by weight of the monomer and oligomer components of nylon 66 remained. Also,
According to the study of the present inventor, even if such a polyamide resin is used, there is no problem in molding with those reinforced with short fibers and those reinforced with short fibers, but only those reinforced with long fibers It has been found that an extremely large molding problem occurs as described above. The cause is that when a polyamide resin reinforced with long fibers is plasticized for molding, the entrainment of air at the time of plasticization is severe, and plasticization with high porosity in the molding machine due to cotton-like entanglement of long fibers. Since the state is formed, it is presumed that the vaporization and decomposition of the monomer / oligomer components present in the polyamide resin and the accompanying fuming are promoted, which is a problem peculiar to the long fiber reinforced polyamide resin. The present invention has been made as a result of earnest studies based on such knowledge, and is characterized in that a polyamide resin having a residual monomer and oligomer content of 3% by weight or less is used as a polyamide resin as a matrix. If a polyamide resin containing more than 3% by weight of residual monomers and oligomers is used,
Sufficient effects cannot be obtained for solving problems such as smoke during molding and burning of molded products. Preferably, a polyamide resin having a residual monomer and oligomer content of 2% by weight or less is used. Here, the method for measuring the residual monomer and oligomer amounts (% by weight) of the polyamide resin specified in the present invention is defined as follows.

First, about 2 g of a polyamide resin is precisely weighed (weight X) and dissolved in 10 ml of hexafluoroisopropanol. Next, this is introduced into 100 ml of water to precipitate and reprecipitate only the polymer component. Next, the precipitated polymer is separated by filtration and dried, and the weight Y is measured. The amount of residual monomer and oligomer (% by weight) is determined by (X−Y) × 100 / X. Although there is no particular limitation on the method for obtaining the polyamide resin having a small amount of the monomer and oligomer used in the present invention, it can be obtained, for example, by a method of treating a normal polyamide resin in hot water.

[0006] Polyamide resin used in the present invention
The (A), nylon 6, nylon 66, nylon 11,
Nylon 12, nylon 6 · 10, nylon 6 · 12 like et al
Is, it is also possible to use a mixture of these polyamide resins of two or more. Of these polyamide resins,
In the present invention, nylon 66 is preferably used in consideration of various properties such as long-term thermal stability, heat resistance, and mechanical strength.

Next, the fibrous reinforcing material used in the present invention
There is no particular limitation on the type of (B), and for example, any of glass fibers, carbon fibers, metal fibers, and resin fibers having a high melting point (high softening point) can be used. In the present invention, a reinforcing material selected from such fibers is blended in the composition at a length of 3 mm or more in an amount of 5 to 80% by weight (in the composition). If the compounding amount of the fibrous reinforcing material is less than 5% by weight, the reinforcing effect by the fiber is small, and if it exceeds 80% by weight, the processability in the preparation or molding of the composition becomes remarkably inferior. Almost no improvement in strength can be expected. Considering the balance between the reinforcing effect and processability, the preferred amount of the fiber is 20 to 70% by weight (in the composition),
Particularly preferably, it is 30 to 65% by weight (in the composition). In the present invention, an appropriate amount of short fibers in addition to the above-mentioned long fibers may be blended as long as the total amount of the fibrous reinforcing material does not exceed 80% by weight.

[0008] The method for producing such a composition of the present invention is not particularly limited. However, in order to suppress fiber breakage, a production method in which a shearing force is generally minimized is preferable, and a production method by pultrusion is particularly preferable. It is preferably used.
Pultrusion molding is basically a process of impregnating a resin while pulling continuous reinforcing fibers, and a method of impregnating a resin through an impregnation bath containing an emulsion, suspension, solution or melt of the resin. A method of spraying powder on fibers or passing powder through a tank containing powder and adhering resin powder to the fibers, then melting and impregnating the resin.Using an extruder etc. while passing the fibers through a crosshead die Any known method such as a method of supplying and impregnating a resin to a crosshead die can be used. In order to subject the resin composition thus obtained to injection molding, it is preferable to form a pellet having a length of 3 to 50 mm. In this case, the fibrous reinforcing material (B) has substantially the same length as the pellet. Thus, the pellets are arranged in parallel in the longitudinal direction.

In the resin composition of the present invention, one or two or more other thermoplastic resins can be used in combination as long as the object and effect thereof are not significantly impaired. In addition, in order to impart desired properties according to the purpose, a known substance generally added to a thermoplastic resin, for example, an antioxidant,
Stabilizers such as heat stabilizers and ultraviolet absorbers, antistatic agents, flame retardants, flame retardant aids, coloring agents such as dyes and pigments, lubricants, plasticizers, crystallization accelerators, crystal nucleating agents, etc. It is also possible. Also, glass flakes, mica, glass powder,
A plate-like or powdery inorganic compound such as glass beads, talc, clay, alumina, carbon black, and wollastonite, or a whisker may be used in an appropriate amount. In particular, as in the present invention, in those reinforced with long fibers, the presence of a lubricant is often required particularly for the flow of the molten resin in the flow of the pellets during plasticization or the uniform mixing of the fibers in many cases, and as a lubricant fatty lithium salt and C ₂₂ -C ₃₂
The compounding of 0.01 to 3% by weight of a compound selected from metal salts of fatty acids is particularly effective.

When the resin composition of the present invention is subjected to injection molding, the effect is particularly remarkably exhibited, and generation of smoke, gas, or burning of a molded article during molding is remarkably improved. It is unavoidable that the fibers are broken during the injection molding, but as a molded product, it is preferable that the fibrous reinforcing material is dispersed with a weight average fiber length of 1 mm or more.

[0011]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 4 and Comparative Example 1 First, a commercially available polyamide resin (nylon 66) was washed with hot water at a normal pressure of 70 ° C. for various periods of time to obtain residual monomers and oligomers as shown in Table 1. Different amounts of polyamide resin were prepared. Next, while opening and pulling the glass roving, the polyamide resin (nylon
After being impregnated with 66), the strand was taken out as a strand through a shaping die, cut, and a pellet composition having a glass content of 60% by weight and a length of 12 mm was prepared. For comparison, a pellet composition was prepared in the same manner using a polyamide resin (nylon 66) that had not been subjected to hot water treatment. Table 1 shows the results of the injection molding of these pellet-like compositions and evaluation. still,
The evaluation was performed by the following method. Smoke generation phenomenon: The amount of smoke generated from the nozzle tip when the resin composition was plasticized by an injection molding machine and caused to flow freely was evaluated by visual observation. Burn of molded article: Burn (discoloration) of a molded article obtained by injection molding was evaluated by visual observation.

[0013]

[Table 1]

[0014]

As is clear from the above description and the examples, in reinforcing a polyamide resin with a fibrous reinforcing material having a long fiber length, a polyamide resin having a small amount of residual monomers and oligomers is used. The long-fiber-reinforced polyamide resin composition of the present invention has very high mechanical properties such as tensile strength, flexural strength, and impact strength because it is reinforced with long fibers, and also has disadvantages unique to long-fiber-reinforced polyamide resins. It has excellent features such as no problems such as smoke, gas generation or burning of the molded product during molding, and is of extremely high industrial value.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-63-82731 (JP, A) JP-A-3-115327 (JP, A) JP-A-3-163165 (JP, A) JP-A-3-3 14831 (JP, A) JP-A-63-260923 (JP, A) JP-A-61-188421 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29B 11/16 B29B 15 / 08

Claims (2)

(57) [Claims] 1. A (A) Residual monomers and weight oligomers was determined by measurement of the body, wherein is 3 wt% or less nylon
6, nylon 66, nylon 11, nylon 12, nylon
A fiber obtained by blending (B) 5 to 80% by weight (in the composition) of a fibrous reinforcing material with at least one kind of polyamide resin selected from the group consisting of 6,10 and nylon 6.12 by a pultrusion method. Injection molding of a pellet-like long fiber reinforced polyamide resin composition having a length of 3 to 50 mm, in which the shape reinforcing material (B) is substantially the same length as the pellet and is arranged in parallel with the length direction of the resin pellet. An injection-molded article comprising a fibrous reinforcing material dispersed in the injection-molded article at a weight average fiber length of 1 mm or more. 2. An injection-molded article according to claim 1, wherein said polyamide resin is mainly composed of nylon 66.