JPH07149891A - Production of reinforced polyamide resin molded product - Google Patents

Abstract

PURPOSE:To obtain the molded product having both high mechanical strength and heat resistance at elevated temperatures under high load by incorporating a lactam with glass fibers and inorganic whisker followed by polymerization through monomer casting process in the presence of an alkali catalyst and polymerization initiator. CONSTITUTION:A lactam (epsilon-caprolactam) is heated to 140 deg.C and melted and then incorporated with an alkali catalyst (e.g. sodium hydride), and further with the same lactam, a polymarization initiator (e.g. tolyene diisocyanate), 5-30 pts.wt. based on the lactam, of glass fibers and 0.5-10 pts.wt., based on the lactam, of inorganic whisker (e.g. potassium titanane whisker). The resultant blend is cast in an aluminum mold heated to 150 deg.C and polymerized to solidification (i.e., monomer casting process), thus obtaining the molded product with both the glass fibers and inorganic whisker dispersed uniformly, having both high mechanical strength and heat resistance at elevated temperatures under high load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a reinforced polyamide resin molded product by an alkali polymerization / monomer casting method of lactams, which is fiber reinforced having strength, rigidity and heat resistance suitable for mechanical parts such as bearings. It relates to a method for producing a polyamide resin molded product.

[0002]

2. Description of the Related Art The so-called alkali polymerization / monomer casting method for obtaining a polyamide resin molded article by polymerizing lactams by the action of an alkali catalyst and a polymerization initiator is known (for example, JP-A-1-141914).
No. 4-122774). The polyamide resin molded product obtained by this method is self-lubricating and has relatively high strength, rigidity and heat resistance, and thus has been widely used for rolls, bearings, gears and the like. However, in a high temperature region above the glass transition temperature of the polyamide resin, the strength and the rigidity are drastically lowered, and the application is limited. Therefore, there is a strong demand for a molded product that can be used under high temperature conditions and high load conditions, and a molded product excellent in strength, rigidity and heat resistance is desired.

In order to improve the strength, rigidity and heat resistance of a polyamide resin molded product by the monomer casting method, a method of blending various reinforcing materials has been tried.
Among them, a large number of compositions and molded articles containing glass fibers, which have a large reinforcing effect and can be obtained at low cost, have been proposed (JP-A-60-223822, JP-A-62-207).
No. 330, No. 63-8417, No. 63-17957
No. 63-63720, No. 63-205351, etc.). However, lactams used in the monomer casting method are liquids with low viscosity at the molding temperature and have a lower specific gravity than glass fibers. Sedimentation of glass fibers is likely to occur, and it is very difficult to produce a molded product in which glass fibers are uniformly dispersed.

As a method of solving this problem, by adding an organic thickener to increase the viscosity of lactams,
A method for slowing the sedimentation of a compounded filler such as glass fiber has been disclosed (JP-A-60-223822).
However, this method not only impairs the essential advantage of the monomer casting method of easily injecting or injecting a low-viscosity liquid into a mold, but also has a drawback of lowering strength, rigidity and heat resistance.

Further, there is disclosed a method in which glass fibers and a plate-like substance (such as glass flakes) are mixed at the same time to suppress warp deformation of a molded article (Japanese Patent Laid-Open No. 62-207330).
No. 63-8417). However, this method has the drawbacks that the flowability is poor because a tabular substance is used in combination, and the amount of glass fiber having a greater reinforcing effect is limited. Further, other disclosed methods also do not show a method for effectively preventing the sedimentation of glass fibers compounded as a reinforcing material without any side effect.

The object of the present invention is to solve the problem that in the lactam monomer casting method, the glass fiber blended as a reinforcing material precipitates during the polymerization of the lactam, and a uniformly dispersed molded product cannot be obtained. Especially. That is, the present invention, the reinforcing effect is large and inexpensive glass fiber is blended as a main reinforcing material, by uniformly dispersing in the molded product, strength, rigidity even in the high temperature range of the glass transition temperature of the polyamide resin or higher. The present invention provides an effective and economically superior novel production method for obtaining an excellent reinforced polyamide resin molded article.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have made it possible for the inorganic whiskers to prevent the precipitation of the glass fibers by incorporating a relatively small amount of the inorganic whiskers into the glass fibers, which is the main reinforcing material. The present invention has been completed by finding out that it has a preventive effect.

The present invention is a monomer casting method in which a lactam is polymerized by the action of an alkali catalyst and a polymerization initiator to obtain a polyamide resin molded product, and 5 to 30 parts by weight of glass fiber and an inorganic substance are added to 100 parts of polymerized lactam. It is a method for producing a reinforced polyamide resin molded article, characterized in that 0.5 to 10 parts by weight of whiskers are blended.

The present invention will be described in detail below. The monomer casting method of lactams in the present invention is a method of polymerizing lactams by the action of an alkali catalyst and a polymerization initiator to obtain a polyamide resin molded article, and can be carried out according to a method known per se.

Specific examples of the lactams used in the present invention include ε-caprolactam, ω-capryllactam,
ω-laurin lactam and the like can be mentioned. These lactams may be used alone or in combination of two or more.

As the alkali catalyst, known compounds used in the alkali polymerization method of lactams can be used. Specific examples thereof include alkali metals, alkaline earth metals, hydrides of these metals, oxides, hydroxides,
Examples thereof include alkylated compounds or Grignard compounds, and reaction products of these with lactams. The amount of the alkali catalyst used is 0.05 to lactams.
It is preferably in the range of 10 mol%, particularly 0.2 to 5 mol%.

As the polymerization initiator, a known compound used in the alkali polymerization method of lactams can be used. Specific examples thereof include N-acyl lactams, organic isocyanates, carbodiimides, acid chlorides, and urea derivatives, and the amount used is preferably 0.03 to 10 mol% based on the lactams.

Generally, in the alkali polymerization / monomer casting method of lactams, a liquid obtained by adding an alkali catalyst to lactams heated and melted at a temperature above the melting point (hereinafter referred to as A
Liquid) and a liquid added with a polymerization initiator (hereinafter referred to as liquid B) are separately prepared, and liquid A and liquid B are mixed,
A polyamide resin molded article is obtained by injecting or injecting it into a mold maintained at a predetermined temperature not lower than the melting point of the lactams used and not higher than the melting point of the polyamide resin to be produced, and polymerizing and solidifying as it is. The mixing operation of the A liquid and the B liquid and the injection or injection operation into the mold may be performed at the same time, or either one may be performed in advance. However,
It is preferable to carry out these operations continuously in the shortest possible time. In the present invention, it is preferable to adopt this general method or a method similar thereto.

The glass fibers used in the present invention are in the form of short fibers such as milled glass fibers and chopped glass fibers, and their sizes are 5 to 500 μm and 5 to 25 μm in average fiber length and fiber diameter, respectively, and are preferable. Is 10 to 200 μm and 8 to 20 μm. The type (component) of glass is not particularly limited, and E glass, C glass, S glass, alkali resistant glass and the like can be used.

The inorganic whiskers used in the present invention are:
It is an acicular crystalline substance of an inorganic substance, and specific examples thereof include silicon carbide, silicon nitride, potassium titanate, zinc oxide, aluminum borate, and basic magnesium sulfate. These sizes have an average fiber length and fiber diameter of 5 to 30 μm and 0.2 to 2 μm, respectively.
The range is m. Among these, potassium titanate whiskers and aluminum borate whiskers having an average fiber length and a fiber diameter of 10 to 30 μm and 0.3 to 1 μm, respectively, are preferably used. The inorganic whiskers used in the present invention may be of a single type, or may be a combination of two or more types.

The blending amount of glass fiber is 100 lactams.
5 to 30 parts by weight, preferably 10 to 25 parts by weight
Parts by weight. If the amount of the glass fiber is less than 5 parts by weight, the effect of improving the strength, rigidity and heat resistance is not sufficient, while if it exceeds 30 parts by weight, the glass fiber is precipitated during the polymerization of lactams and a uniform dispersion cannot be obtained. . Furthermore, the viscosity of lactams containing glass fibers becomes high, and the advantage of the monomer casting method is impaired, which is not preferable.

The content of the inorganic whiskers is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of lactams.
If the blending amount is less than 0.5 part by weight, there is no effect on the strength and the like, and the effect of preventing the settling of the glass fibers is small, so that the glass fibers cannot be uniformly dispersed. Further, if it exceeds 10 parts by weight, although there is an effect on the strength and the like, the inorganic whiskers are relatively expensive and are not economical.

In the present invention, the method of blending the glass fiber and the inorganic whiskers in the above-mentioned liquid A and / or liquid B is not particularly limited, but it is preferable to blend the glass fibers after the blending of the inorganic whiskers, and both of them are further added. It is preferable to thoroughly stir after blending.

In the present invention, a plasticizer, a foaming agent, a coloring agent, an antioxidant and the like which do not substantially inhibit the polymerization reaction of lactams can be added to the above-mentioned liquid A and / or liquid B.

[0020]

EFFECT OF THE INVENTION According to the production method of the present invention, when glass fibers which have a high reinforcing effect and are inexpensive are compounded as a main reinforcing material, the inorganic whiskers are used in combination, so that the precipitation of the reinforcing material is extremely small and practical. There is an advantage that a molded product uniformly dispersed can be obtained. In addition, the inorganic whiskers have an effect of improving heat resistance and strength, and the obtained reinforced polyamide resin molded article has significantly improved strength and rigidity, especially at high temperatures. As a result, a reinforced polyamide resin molded article having extremely excellent properties and economically advantageous can be obtained.

INDUSTRIAL APPLICABILITY The present invention is extremely useful for producing various reinforced polyamide resin molded articles such as rolls, bearings and gears which can be suitably used under high temperature conditions and high load conditions.

[0022]

EXAMPLES Specific examples and comparative examples will be shown below.
However, the present invention is not limited to these examples.

Examples 1 to 5 500 g of substantially anhydrous ε-caprolactam was placed in a 1-liter flask, heated and melted at 140 ° C., and 2 g of sodium hydride (oil-based 62.8%) as an alkali catalyst.
To prepare a mixture (solution A). On the other hand, in another 1 liter flask, 500 g of substantially anhydrous ε-caprolactam
After heating and melting at 140 ° C., 8 g of tolylene diisocyanate was added as a polymerization initiator, and then aluminum borate whiskers (Arborex, Shikoku Kasei Co., Ltd.)
And / or potassium titanate whiskers (Otsuka Chemical Co., Ltd. Tofikar YD) are mixed in a predetermined amount, respectively, and further milled glass fibers (Nitto Boseki PFE-301).
A predetermined amount of S) was blended to prepare a mixture (liquid B). Next, after thoroughly stirring the liquids A and B, both were immediately heated to 150 ° C.
It was poured into a mold made of aluminum which had been heated to 1, and was polymerized and solidified as it was to obtain a reinforced polyamide resin molded product having a diameter of about 7 cm and an effective height of about 23 cm.

The density at 23 ° C. was measured from the bottom of the obtained molded product (bottom of the mold) to heights of 4 cm, 12 cm and 20 cm. In addition, a test piece was prepared from the molded product, and the bending strength (test method ASTM D-790) and bending elastic modulus (at the same A
STM D-790), compressive strength (the same ASTM D-6
95), and the deflection temperature under load (the same ASTM D-648) was measured. Table 1 shows the compounding amounts of the glass fibers and the inorganic whiskers used and the measurement results.

[0025]

[Table 1]

Comparative Example 1 A molded product was obtained in the same manner as in Example 1 except that the inorganic whiskers were not added. Table 1 shows the measurement results of the density of the molded product performed in the same manner as in Example 1. The density of this molded product varied greatly depending on the location, and the dispersion of the milled glass fiber was non-uniform.

Comparative Example 2 A molded product was obtained in the same manner as in Example 1 except that the inorganic whiskers and the milled glass fiber were not blended. Table 1 shows the measurement results obtained in the same manner as in Example 1.

Claims (1)

[Claims] 1. In a monomer casting method for polymerizing lactams by the action of an alkali catalyst and a polymerization initiator to obtain a polyamide resin molded product, 5 to 30 parts by weight of glass fibers and 0 parts of inorganic whiskers are used per 100 parts by weight of lactams. A method for producing a reinforced polyamide resin molded article, which comprises blending 5 to 10 parts by weight.