JPS62212459A - Polyamide resin composition having high specific gravity - Google Patents

Abstract

PURPOSE:To provide the titled polyamide resin compsn. which has excellent moldability, gives moldings having excellent uniformity, etc., has a high specific gravity and is suitable for use in the production of a flywheel, etc., by blending a mixture of two polyamides having different number-average MW's with metallic powder. CONSTITUTION:1-75wt% polyamide (A) having a number-average MW of 500-15,000 selected from the group consisting of nylons 610, 612, 11 and 12 and copolymer thereof is mixed with 99-25wt% polyamide (B) having a number- average MW of 15,000-30,000. 5-50wt% polyamide mixture is mixed with 99-50wt% metallic powder (e.g., iron powder) to obtain the desired polyamide resin compsn. having a high specific gravity. Since the polyamide mixture of the low-molecular polyamide and the high-molecular polyamide is blended with metallic powder, the resulting compsn. has high flow characteristics and can be easily injection-molded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a polyamide resin composition containing metal powder. More specifically, the present invention relates to a high-density polyamide resin composition containing metal powder, particularly iron powder, having good moldability.

[Conventional technology and problems]

Resin compositions in which glass fibers, carbon fibers, etc. are blended with polyamide resins have conventionally been widely used as high-rigidity materials. In addition to these fibers, inorganic powders such as talc and calcium carbonate are also used as fillers, and have shown the effect of improving the elastic modulus of polyamide.

Furthermore, in recent years, polyamide resins have also been used as electromagnetic shielding materials made by blending metal fibers with polyamide resins, or as plastic magnet materials made by blending ferrite and the like with polyamide resins.

As described above, the use of materials in which a polyamide resin is used as a matrix material and a reinforcing agent or filler is blended therein is increasing. These materials are formed into shapes using currently commonly used injection molding or extrusion molding methods, and are used for their respective purposes.

One such application field is flywheels and inertia gears, which require materials with high specific gravity. All of these utilize the inertia of an object to provide smooth rotation.

Therefore, a device that can maintain a large inertial force, that is, one made of a material with a large specific gravity, can obtain a large inertial force even if it is small, and is therefore advantageous for use in a small space. It is also necessary that these materials be well balanced. If it is unbalanced, the inertial force will be uneven, resulting in shaft wobbling and uneven rotation.

However, conventionally known resin compositions using polyamide resin as a matrix material cannot satisfy the above requirements.

[Means for solving problems]

As a result of intensive studies to satisfy these requirements, the inventors of the present invention found that: 1) it has excellent moldability, 2) the molded product has sufficient uniformity, and 3) it has a high specific gravity and is resistant to external forces. The present invention was achieved by discovering a high-density polyamide resin molding material composition that is strong.

That is, the present invention provides (a) one or more polyamides selected from nylon 610.612.11゜12 and copolymers thereof, with a number average molecular weight of 500 to 15
．． 1 to 75% by weight of 000 and (b) 99 to 25% by weight of number average molecular weight of 15.000 to 30.000.
5 to 50% by weight of a polyamide mixture formed by blending the
The present invention relates to a high specific gravity polyamide resin composition comprising 95 to 50% by weight of metal powder.

Hereinafter, the polyamide resin composition of the present invention will be explained in detail.

The polyamide used in the composition of the invention is nylon 1
1.12.610.612 or a copolymerized nylon mainly composed of these monomers or a mixture thereof,
Preferably nylon 11. It is nylon 12.

The polyamide resin composition used in the present invention is preferably a mixture of these polyamides having a number average molecular weight of 500 to 15,000 and those having a number average molecular weight of 15,000 to 30,000. has a number average molecular weight of 1
, 000-15.000 and 15.000-26
．． It is better to combine it with 000. The number average molecular weight of the main component, high molecular weight polyamide, is 15,000.
If it is lower, the resistance to impact is insufficient, and although the fluidity is good, the mechanical properties cannot be maintained, and if the number average molecular weight exceeds 30,000, the mechanical properties are insufficient. However, when metal powder is added, the fluidity becomes poor and molding becomes difficult.

When comparing the above compound with a polyamide having a standard molecular weight distribution, when viewed as a polyamide, there is no change in fluidity at all as long as the number average molecular weight is the same. However, in the case of a high specific gravity composition mixed with metal powder, compared to a resin composition in which metal powder is blended with polyamide having a standard molecular weight distribution, a high molecular weight composition having a different number average molecular weight according to the present invention is used. In the case of a resin composition in which metal powder is blended with a mixed polyamide that is a combination of a polyamide with a low molecular weight and a polyamide with a low molecular weight, less force is required when kneading these materials, and the fluidity of the resin composition is also improved. In good condition.

The reason for this is that polyamide with a low number average molecular weight exerts a plasticizing effect on polyamide with a high number average molecular weight, and the fluidity is particularly good in areas where the resin component is small, that is, where the metal powder is highly concentrated. It is presumed that it will appear in the form it has become.

The mixed polyamide made by combining polyamides having different number average molecular weights according to the present invention can have even higher heat resistance by adding a suitable stabilizer.

In addition, metal powders include Fes, Zns Sns Pb
Powders such as SCu and its alloys and oxides are used, but
From the viewpoint of cost, iron powder is most preferable, and in addition to resin and metal powder, a silane coupling agent corresponding to these properties can also be added.

The metal powder used in the present invention may be obtained by any method, and the shape of the metal powder may be any shape.
It is preferable to use something close to a spherical shape rather than an angular metal powder. Square metal powder not only deteriorates the fluidity of the material, but also
Equipment used to obtain resin compositions or molded products is likely to be worn out.

The metal powder may have a particle size of 0.1 to 300μ, preferably 0.1 to 200μ, more preferably 0.1 to 50μ. If the particle size is smaller than 0.1μ, it is inconvenient to handle;
If it is larger, moldability will be inhibited.

The blending amount of these metal powders is 95 to 50% by weight relative to 5 to 50% by weight of the polyamide resin component.

[For production]

The following properties can be obtained by using a polyamide resin composition in which a metal powder is blended with a polyamide resin component blended with a polyamide low-molecular prize and a high-molecular prize as described above as a high-density molding material.

1) When performing kneading, extrusion, and injection molding, the fluidity of the mixture becomes high, and molding can be performed even if it contains a large amount of metal.

2) Friction and wear on the molding machine and the scree surface are reduced, making it possible to reduce the amount of impurities mixed into the molded product.

Furthermore, the life of the device can be extended.

The composition of the present invention is produced by melt-mixing a high molecular weight polyamide and a low molecular weight polyamide, usually using a screw or twin screw extruder. Further, kneading may be carried out using a kneader. It is also possible to use a small amount of lubricant at this time. Specifically, the polyamide component and metal powder according to the present invention are blended together, and the metal powder is mixed with granular or powdered polyamides of high molecular weight and low molecular weight. A polyamide mixture containing a low molecular weight polyamide and a high molecular weight polyamide is prepared in advance in the form of granules or powder, mixed with metal powder, and then put into the extruder hopper and heated. A method of melt-mixing and granulating, or a method of kneading the premixed material in a kneader, and granulating it by cutting or crushing the material discharged from the discharge port when the kneading is completed, or using an extruder to produce low molecular weight polyamide. There is a method in which a mixture of polyamide and high molecular weight polyamide is charged from a portion of a hopper, heated and melted, and metal powder is added and mixed through a hole provided in the middle of the cylinder of an extruder.

At this time, a mixture of a low molecular weight polyamide and a high molecular weight polyamide may be heated and kneaded in an extruder or kneader in advance and granulated, or a powder thereof may be used.

The pellet thus obtained can be further molded by injection molding, extrusion molding, etc. to obtain a resin molded product.

Moreover, instead of such two-stage molding, a molded article can also be obtained by charging a mixture of metal powder, low molecular weight polyamide, and high molecular weight polyamide into a molding machine. Alternatively, a molded product can be similarly obtained at once by charging a molding machine with metal powder and a mixed polyamide that has been heat-kneaded with a low molecular weight polyamide and a high molecular weight polyamide in advance.

In the case of obtaining an injection molded article made only of polyamide, when trying to obtain a very thin molded article, a polyamide with good fluidity and a low degree of polymerization may be used. Even if such a polyamide mixture is used,
Alternatively, a polyamide with a single standard molecular weight distribution may be used, providing the same flowability and moldability, provided the number average molecular weight is the same.

However, in the case of the polyamide resin composition according to the present invention containing metal powder, it has been found that the state of molecular weight distribution of the polyamide resin used as the base greatly influences the fluidity of the resin composition containing metal powder. In the present invention, a low molecular weight polyamide and a high molecular weight polyamide are used in an appropriate ratio as a base resin for a composition containing metal powder, and stabilizers, lubricants, colorants or dispersants are added as necessary. It is possible to obtain a metal powder-containing high-density polyamide composition that has good fluidity that is exhibited only under conditions where the metal powder is filled.

Therefore, when obtaining a molded article using the composition of the present invention, the molding temperature can be selected from a wide range.

Furthermore, improved fluidity enables molding at lower temperatures, which not only allows for savings in power consumption, but also can be expected to extend machine life.

As described above, according to the present invention, it is possible to obtain a high specific gravity composition material containing uniformly dispersed metal powder and having good moldability. It can be used for various purposes.

〔Example〕

Next, the present invention will be explained with reference to examples.

Examples 1-3 Nylon 12 was selected as the polyamide.

As the low molecular weight polyamide, NYO-3500 (number average molecular weight 3.50
0) and NYO-8100 (number average molecular weight 8.100)
was used.

As the high molecular weight polyamide, "Diamide J L-1940" manufactured by Daicel Huls ■ was used.

The number average molecular weight of this product was 25.800. These low molecular weight polyamides and high molecular weight polyamides are shown in the table below.
Rheocord
Samples of the mixed polyamide were obtained by kneading using a Type M (Ilaake Inc.) at a temperature of 210° C. and 5 Orpm+ for 15 minutes. In addition, the number average molecular weight was measured by relative viscosity measurement. That is, by dissolving the sample in metacresol to make a 0.5% metacresol solution and measuring the relative viscosity of this solution, each η1. L is determined, and the determined η1. ．． was calculated as the number average molecular weight by substituting it into the following formula.

F Proverbs 10300 (ηrat) l@4! ff1s Number average molecular weight fret: Relative viscosity By blending a low molecular weight polyamide and a high molecular weight polyamide at the resin blending ratio shown in Table 1, a polyamide mixture having an appropriate number average molecular weight was obtained.

The results of measuring positive values only for these polyamide mixtures are also listed in Table 1. The Ml value was measured using Melt In.
Measurements were performed using dexer. The measurement conditions are 19
A load of 2.16 kg was used at 0°C. As iron powder■
Kobe Steel's atomized iron powder (product name: Atmel 300
M-200J) was used.

A sample was prepared in which 100 parts by weight of iron powder was subjected to surface treatment with 1 part by weight of a silane coupling agent "SiLa Ace A-320J" manufactured by Chisso ■, and was subjected to the following test.

That is, when examining the kneading torque using the polyamide mixture and iron powder prepared in advance according to the above procedure,
The iron powder content was adjusted to 82.5% by weight.

A mixture of these iron powders and polyamide (iron powder content 82.
5% by weight) was weighed to have a volume of 50 cc, and the kneading torque during heating and kneading was examined. R for investigating kneading torque
heocord Type M (Haake Inc.
), kneading temperature 220℃, rotation speed 100rρ-
The crosstalk torque was observed 15 minutes after the start of kneading.

Similarly, the iron powder content was 82.5% by weight, and M
Kneading and granulation was performed at a temperature of 180°C to 240°C using a CI kneading extruder. The pellet thus obtained was molded to obtain a test piece for measuring physical properties. Molding was carried out using a Nissin TS-1OO injection molding machine, with a molding temperature of 220°C to 240°C and an injection pressure of 1
00kg/c was carried out at a G1 type temperature of 85°C.

Physical properties are measured according to ASTM D-638,0-790,0-
This was carried out by the method of No. 256.

Comparative Examples 1 to 3 Nylon 12 was selected as the polyamide as in the examples.

Examples of polyamide include Daicel Huls ■'s product name "Diamide J L-1940, L-1700 and L-16".
00 was used. The number average molecular weights of these were 25,800.22,000.20.200, respectively. The number average molecular weight was measured by the relative viscosity measurement method as in the examples.

Only resin! The values were measured using the same device and under the same conditions as in the examples. The results are shown in Table-1.

As the filler, the previously surface-treated iron powder used in the experiments of Examples was used.

The iron powder and polyamide prepared above were mixed in the proportions shown in Table 1, and the kneading torque was observed as in the example when the iron powder content was 82.
．． It was carried out at 5% by weight using the same equipment and under the same conditions as in the example. Further, samples for measuring physical property values were prepared under the same conditions as in the examples, and physical property values were also measured using the same equipment and under the same conditions as in the examples. The results are also listed in Table-1.

Claims (1)

[Claims] (a) 1 to 75% by weight of one or more polyamides selected from nylon 610, 612, 11, 12 and copolymers thereof, with a number average molecular weight of 500 to 15,000; , (b) Number average molecular weight is 15,000
5-50% by weight of a polyamide mixture of 99-25% by weight of ~30,000 and 95-5% by weight of metal powder.
A high specific gravity polyamide resin composition consisting of 0% by weight.