JPH05208418A - Long-fiber-reinforced polyamide resin composition and its molded product - Google Patents

Abstract

PURPOSE:To provide a long-fiber-reinforced polyamide resin composition which not only possesses mechanical properties such as extremely high tensile strength, bending strength and shock strength but also does not generate a problem such as smoking or generation of gas or burning of a molded product at the time of molding has been a defect peculiar to the long-fiber-reinforced polyamide resin. CONSTITUTION:This is long-fiber-reinforced polyamide resin composition which is constitute by compounding a 5-80wt.% reinforcing material (B) (in a composition) which polyamide resin (A) whose quantities of residual monomer and oligomer measured by this measuring method do not exceeding 3wt.% and possesses a long fiber having a length of at least 3mm within the composition in a fibrous reinforcing material.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD 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 in molding, and a molded product of the same, which has high mechanical strength and less scorching during molding. Regarding molded products.

[0002]

2. Description of the Related Art As a means for improving the strength of a polyamide resin, it is known to blend a fibrous reinforcing material such as glass fiber,
Generally, a fiber resin-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, this method cannot avoid the breakage of the fibers during the kneading in the extruder, and thus cannot meet the demands for higher mechanical strength and the like. On the other hand, in recent years, as a method to fully bring out the inherent performance of the fibrous reinforcing material to be blended,
Reinforcement of polyamide resin with long fibers has been studied. Such long fiber reinforced polyamide resin, for example,
It can be obtained by, for example, a method of impregnating a continuous reinforcing fiber with an emulsion, solution or melt of a polyamide resin. However, such a long fiber reinforced polyamide resin has a problem that smoke or gas generation is severe during molding using the same or purging of the resin. In addition, when molding is performed using such a material, the molded product may be burnt to impair the appearance, or the strength of the molded product may not be sufficiently improved. Such smoke generation, gas generation, or burning of molded products is a problem peculiar to polyamide resin reinforced with long fibers. Does not substantially occur, and there is no practical problem.
Such a polyamide resin reinforced with long fibers has essentially excellent mechanical strength and the like, but its moldability is not always sufficient, and its improvement has been earnestly desired.

[0003]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that the monomer / oligomer remaining in the polyamide resin is specific to the polyamide resin reinforced with long fibers. The present invention has been achieved by finding that it adversely affects That is, the present invention provides (A) a polyamide resin having an amount of residual monomers and oligomers of 3% by weight or less measured by the measuring method described below, and (B) 5 to 80% by weight (in the composition) of a fibrous reinforcement. And the fibrous reinforcement is 3% in the composition.
The present invention relates to a long fiber-reinforced polyamide resin composition having a fiber length of mm or more, and a molded article obtained by injection molding using such a composition.

The present invention will be described in detail below. In general, polyamide resins are unavoidably left unreacted monomers and low-molecular weight oligomers in the production process, and the present inventors measured the amount of residual monomers and oligomers of various polyamide resins by the following method. 6 to 10
It was found that more than 5% by weight of nylon 66 and more than 3% by weight of nylon 66 remained as monomer and oligomer components. Also,
According to the study of the present inventor, even when such a polyamide resin is used, a molding problem does not occur in those not reinforced with fibers and those reinforced with short fibers, but only those reinforced with long fibers It has been found that the extremely large molding problem described above occurs. The reason for this is that when polyamide resin reinforced with long fibers is plasticized for molding, air entrainment during plasticization is severe, and due to cotton-like entanglement of long fibers, plasticization with high porosity in the molding machine is performed. It is presumed that the formation of the state accelerates vaporization and decomposition of the monomer / oligomer component present in the polyamide resin and accompanying smoke generation, which is a problem peculiar to the long fiber reinforced polyamide resin. The present invention has been made as a result of extensive studies based on such findings, 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 matrix polyamide resin. If a polyamide resin containing more than 3% by weight of residual monomers and oligomers is used,
Sufficient effects cannot be obtained for the improvement of problems such as smoke generation during molding and burning of molded products. It is preferable to use a polyamide resin having a residual monomer and oligomer content of 2% by weight or less. Here, the method for measuring the amount (% by weight) of residual monomers and oligomers 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, by introducing this into 100 ml of water, only the polymer component is precipitated and reprecipitated. Next, the precipitated polymer is separated by filtration and dried to measure the weight Y. The amount of residual monomers and oligomers (% by weight) is calculated by (X−Y) × 100 / X. There are no particular restrictions on the method for obtaining the polyamide resin having a small amount of the above-mentioned monomers and oligomers used in the present invention, but it can be obtained by, for example, treating a normal polyamide resin in hot water.

Polyamide resin used in the present invention
Examples of (A) include nylon 6, nylon 66, nylon 11, nylon 12, nylon 6/10, nylon 6/12, etc., but are not limited thereto, and the amount of residual monomer and oligomer is not particularly limited. Any known polyamide resin can be used as long as it meets the requirements of the invention. It is also possible to use a mixture of two or more of these polyamide resins. Among these polyamide resins, in the present invention, in consideration of various characteristics such as long-term thermal stability, heat resistance and mechanical strength, a resin mainly composed of nylon 66 is preferable.

Next, the fibrous reinforcing material used in the present invention
The type of (B) is not particularly limited, and for example, glass fiber, carbon fiber, metal fiber, resin fiber having a high melting point (high softening point), etc. can be used. In the present invention, the reinforcing material selected from such fibers is blended in the composition in an amount of 5 to 80% by weight (in the composition) in a state of having a length of 3 mm or more. When the content of the fibrous reinforcing material is less than 5% by weight, the reinforcing effect by the fibers is small, and when it exceeds 80% by weight, the workability in the preparation or molding of the composition is significantly deteriorated. Little improvement in strength can be expected. Considering the balance between the reinforcing effect and the processability, the preferable fiber content is 20 to 70% by weight (in the composition),
Particularly preferably, it is 30 to 65% by weight (in the composition). Further, in the present invention, an appropriate amount of short fibers may be blended in addition to the above long fibers as long as the total amount of the fibrous reinforcing material does not exceed 80% by weight.

The method for producing the composition of the present invention is not particularly limited, but in order to suppress the breakage of the fiber, a production method in which shearing force is not applied as much as possible is preferable, and a production method by pultrusion molding is particularly preferable. It is preferably used.
Basically, pultrusion is a method of impregnating a resin while pulling a continuous reinforcing fiber, and a method of impregnating a fiber through an impregnation bath containing a resin emulsion, suspension, solution or melt, and a resin. The method of spraying the powder of the fiber to the fiber or passing the fiber through the tank filled with the powder and adhering the resin powder to the fiber, then melting and impregnating the resin, from the extruder etc. while passing the fiber through the crosshead die Any known method such as a method of supplying a resin to the crosshead die and impregnating it can be used. In order to use the resin composition thus obtained for 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. Then, the pellets are arranged in parallel in the length direction.

The resin composition of the present invention can be used in combination with one or more kinds of other thermoplastic resins as long as the objects and effects are not significantly impaired. Further, in order to impart desired properties depending on the purpose, known substances generally added to thermoplastic resins, for example, antioxidants,
Heat resistance stabilizers, stabilizers such as UV absorbers, antistatic agents, flame retardants, flame retardant aids, colorants such as dyes and pigments, lubricants, plasticizers, crystallization accelerators, crystal nucleating agents, etc. It is also possible to do so. Also, glass flakes, mica, glass powder,
An appropriate amount of a plate-like or powdery inorganic compound such as glass beads, talc, clay, alumina, carbon black, wollastonite, or whiskers may be used in combination. Particularly in the case of those reinforced with long fibers as in the present invention, the presence of a lubricant is often necessary especially for the flow of pellets during molding, the flow of molten resin during plasticization, or the uniform mixing of fibers. fatty lithium salt and C ₂₂ -C ₃₂
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 effects are particularly remarkably exhibited, and smoke generation, gas generation, or burning of a molded product during molding are remarkably improved. Although it is inevitable that the fibers will be broken during injection molding, it is preferable that the fibrous reinforcing material is dispersed in the molded article with a weight average fiber length of 1 mm or more.

[0011]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

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 a different time and washed with hot water to give residual monomers and oligomers as shown in Table 1. Different amounts of polyamide resin were prepared. Next, while opening and pulling the glass roving, pull the polyamide resin (nylon prepared above)
After impregnation with 66), it was taken out as a strand through a shaping die and cut to prepare a pellet composition having a glass content of 60% by weight and a length of 12 mm. For comparison, a pelletized composition was prepared in the same manner using a polyamide resin (nylon 66) that was not treated with hot water. Table 1 shows the results of evaluation by injection molding of these pellet compositions. 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 free-flowed was evaluated by visual observation. Burning of molded product: Burning (discoloration) of the molded product obtained by injection molding was evaluated by visual observation.

[0013]

[Table 1]

[0014]

As is clear from the above description and examples, when a polyamide resin is blended with a fibrous reinforcing material having a long fiber length for reinforcement, a polyamide resin containing a small amount of residual monomers and oligomers is used. The long fiber-reinforced polyamide resin composition of the present invention has not only mechanical properties such as extremely high tensile strength, bending strength, and impact strength because it is reinforced with long fibers, but also has drawbacks peculiar to the long fiber-reinforced polyamide resin. However, it has excellent characteristics such as no problems such as smoke generation, gas generation or burning of the molded product at the time of molding, and is of extremely high industrial value.

Claims (4)

[Claims] 1. A polyamide resin having a residual monomer and oligomer content of 3% by weight or less measured by the measuring method described in (A) and (B) 5 to 80% by weight (in the composition) of a fibrous reinforcing material. And the fibrous reinforcement is 3% in the composition.
A long fiber reinforced polyamide resin composition having a fiber length of at least mm. 2. A long fiber reinforced polyamide resin composition having a length of 3
The long-fiber-reinforced polyamide resin composition according to claim 1, which is in the form of pellets of -50 mm and in which the fibrous reinforcing material (B) has substantially the same length as the pellet and is arranged in parallel in the length direction of the pellet. 3. A long-fiber-reinforced polyamide resin composition further comprising 0.01 to 3% by weight of one or more compounds selected from lithium salts of fatty acids and metal salts of C _{22 to} C ₃₂ fatty acids. The long fiber-reinforced polyamide resin composition according to claim 1. 4. A long fiber reinforced polyamide resin composition according to claim 1, which is injection molded.
A molded product in which fibrous reinforcing material is dispersed with a weight average fiber length of 1 mm or more.