JP3147248B2 - High specific gravity polyamide resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high specific gravity polyamide resin containing a polyamide resin as a main component and metal powder uniformly dispersed therein.

[0002]

2. Description of the Related Art In recent years, reinforcing materials have been developed using a synthetic resin as a matrix material, such as an electromagnetic wave shielding material in which metal fibers are mixed in a synthetic resin, or a plastic magnet material in which ferrite or the like is mixed in a synthetic resin. Alternatively, the use of filler-blended materials is increasing. Such a material is molded using an injection molding method or an extrusion molding method which is generally performed at present, and is used for various applications.

[0003] One of such application fields is a flywheel or an inertia gear which requires a material having a high specific gravity. All of these provide smooth rotation by utilizing the inertial force of the object. Therefore, a material molded from a material having a large specific gravity capable of maintaining a large inertial force can obtain a large inertial force even if it is small, and is therefore advantageous for use in a small space.

[0004] For that purpose, it is necessary to increase the content of the metal powder in the resin. However, when the content of the metal powder is increased, the mechanical properties of the molded product are reduced, and the flow of the melt-kneaded material is deteriorated, so that the molding becomes impossible. These materials also need to be balanced. With a material lacking balance, the inertia force becomes uneven, and the shaft of the flywheel and the inertia gear oscillates and the rotation becomes uneven. Therefore, it is necessary that the metal powder to be blended is uniformly dispersed in the resin.

Conventionally, to solve these problems, a method of blending a lubricant or a plasticizer to lower the melt viscosity, or a method of surface-treating a metal powder with a silane-based coupling agent or the like to improve the wettability with a resin. Accordingly, a method of reducing the melt viscosity has been performed.

In particular, the latter is generally used because it has a large effect without significantly changing the mechanical strength. But,
When a polyamide resin is used as the binder, there have been problems such as an excessively high heating temperature during molding, a long heating time, and an increase in melt viscosity during repetition of regeneration.

According to the present invention, as a result of earnest studies on a polyamide resin used as a binder, it has been found that the above problems can be solved by using a polyamide resin having a specified terminal group and relative viscosity. Reached.

[0008]

That is, the present invention has a terminal carboxyl group concentration of 90 mg equivalent / kg or less, a terminal amino group concentration of 10 mg equivalent / kg or less, and a relative viscosity of 1.50 to 1 mg / kg. A high specific gravity polyamide resin comprising a polyamide resin of .70 or less and a metal powder.

The polyamide resin used in the present invention is a polymer having an amide bond in the main chain and is obtained by polycondensation of diamine and dibasic acid, ring-opening polymerization of lactam, polycondensation of aminocarboxylic acid, and the like. There is no particular limitation as long as it is provided. For example, nylon 6, nylon 11, nylon 12, nylon 46, nylon 66, nylon 610, nylon 61
2, one or two or more selected from nylon 1212 and copolymers thereof.

The terminal group concentration of the polyamide resin used in the present invention is adjusted by performing terminal modification with a monocarboxylic hydrocarbon or the like.
It must be less than mg equivalent / kg. If the terminal carboxyl group concentration is higher than 90 mg equivalent / kg, the interaction with the metal powder at the time of molding and kneading becomes too strong, the melt viscosity increases and the moldability deteriorates. It will be difficult. When used as a plastic magnet material, if the melt viscosity is high, the orientation of the ferrite at the time of melt magnetization deteriorates, and the magnetic characteristics deteriorate.

The terminal amino group concentration of the polyamide resin used in the present invention must be 10 mg equivalent / kg or less. If the terminal amino group concentration is higher than 10 mg equivalent / kg, the polyamide resin itself is cross-linked at the time of heating and kneading with the metal powder or at the time of molding and heating, and as a result, the melt viscosity of the kneaded melt increases, resulting in poor moldability. This makes it difficult to recycle the polyamide resin with high specific gravity. In addition, when used as a plastic magnet material, if the melt viscosity is high, the orientation of ferrite during magnetization deteriorates, and the magnetic properties deteriorate. The lower limit of the terminal amino group concentration is not particularly limited, and those having no terminal amino group can be used.

The polyamide resin used in the present invention must have a relative viscosity of 1.50 or more and 1.70 or less.
Preferably, the relative viscosity is 1.55 or more and 1.65 or less. If the relative viscosity is higher than 1.70, the melt viscosity of the kneaded melt at the time of kneading and melting with the metal powder and at the time of forming and melting will be too high, resulting in poor moldability. In addition, when used as a plastic magnet material, if the melt viscosity is high, the orientation of ferrite during melt magnetization deteriorates, and the magnetic properties deteriorate. Conversely, if the relative viscosity is lower than 1.50, the mechanical strength of the molded product will be reduced due to the low molecular weight of the polyamide resin. The relative viscosity is determined according to DIN 53727 by 0.1.
This is a value measured using a solution viscosity measurement method using a 5% meta-cresol solution.

The polyamide resin used in the present invention can be mixed with a lubricant, a plasticizer or the like to lower the melt viscosity, and it is also possible to add a stabilizer and other additives. The metal powder used in the present invention is not particularly limited. For example, Fe, Mg, ZnSn, Pb, Cu, M
Powders of metals such as n, Cr, Ni, Co, and Nb and alloys thereof, and powders of oxides, borides and silicon salts of these metals can be given, but iron powder is preferred from the viewpoint of price. . Also, ferromagnetic powders such as strontium ferrite and barium ferrite, and soft ferrite powders can be used.

The metal powder used in the present invention may be obtained by any method, and the shape of the metal powder may be any. However, a metal powder that is too square will only deteriorate the fluidity of the material. In addition, the apparatus for obtaining the resin composition or the molded product is worn, which is not preferable because it causes foreign matters to be mixed into the molded product.

The particle size of the metal powder is 0.1 to 300 μm.
m, but preferably 0.1 to 5
Those having a particle size of 0 μm are preferred. If the particle size is smaller than 0.1 μm, it is inconvenient to handle, and if it is larger than 300 μm, molding is hindered, which is not preferable.

In order to improve the wettability between the polyamide resin used in the present invention and the metal powder and reduce the melt viscosity, the metal powder may be treated in advance with a coupling agent or a surface modifier. As the coupling agent or surface modifier used,
Various surface modifiers such as silane-based, titanate-based, aluminum-based, phosphite and other organic phosphorus compound-based, chromium-based, methacrylate-based, and amino-acid-based agents are included, but they improve compatibility with polyamide resins. Therefore, those having an amino group are preferred. For example, γ-aminopropyltriethoxysilane, N-β- (aminoethyl)
-Γ-aminopropyldimethoxymethylsilane, γ-benzylaminopropyltrimethoxysilane and the like.

The content of the metal powder in the high specific gravity polyamide resin of the present invention is 97 to 50% by weight, preferably 95 to 65% by weight based on the total amount. If it is more than 97% by weight, sufficient moldability and mechanical strength cannot be obtained, and if it is less than 50% by weight, a sufficient specific gravity cannot be obtained.

[0018]

The high specific gravity polyamide resin of the present invention has the following effects.

(1) The frictional resistance between the metal powder and the polyamide resin is reduced, and the metal powder is uniformly dispersed to obtain a well-balanced molded product.

(2) When the mixture is molded using an injection molding machine, the flowability of the kneaded melt of the metal powder and the polyamide resin is high, so that the moldability is good even if a large amount of the metal powder is contained. The stability of the precision of the molded product is also good.

(3) Since the coefficient of friction between the wall surface of the molding machine and the kneaded material is small, wear of the molding machine is small, and the life of the molding machine is prolonged. Further, foreign matter such as abrasion material does not enter the molded portion, and the quality of the molded product is improved.

(4) Since the melt viscosity does not increase even after heating and kneading for a long time, the resin can be recycled.

(5) In the case of a resin permanent magnet using ferromagnetic powder as the metal powder, even if a large amount of ferromagnetic powder is contained, a magnet having good orientation and excellent magnetic properties can be obtained. In addition, since the melt viscosity does not increase even after heating and kneading for a long period of time, a magnetic material having excellent orientation and excellent magnetic properties can be obtained even when used for recycling.

Having these characteristics, the high specific gravity polyamide resin of the present invention can be used for a flywheel, an inertia gear, a resin magnet,
It is suitably used for various applications such as electromagnetic wave shielding materials.

[0025]

Next, the present invention will be described with reference to examples and comparative examples.

Examples 1 to 3 As polyamide resins, those obtained by adding stearic acid during polymerization of Nylon 12 manufactured by Daicel Huls Co. and adjusting the terminal group concentration and relative viscosity were used.

Table 1 shows the terminal carboxyl group concentration, terminal amino group concentration and relative viscosity of these polyamide resins. The terminal carboxyl group concentration was measured by dissolving the polyamide resin in benzyl alcohol and performing neutralization titration by potentiometric titration using 0.01 N-KOH. The terminal amino group concentration was measured by dissolving the polyamide resin in a mixed solvent of phenol / methanol (volume ratio: 10/1) and performing neutralization titration by potentiometric titration using 0.01 N-HCl.

The relative viscosity of the polyamide resin is DIN 53
Determined by measuring the solution viscosity using a 0.5% meta-cresol solution according to 727.

Strontium ferrite manufactured by Toda Kogyo was used as the metal powder. The ferrite 10
A surface treatment was performed with 0.7 parts by weight of β- (aminoethyl) -γ-aminopropyltrimethoxysilane with respect to 0 parts by weight.

This surface-treated ferrite 88.
270 g of a composition consisting of 0 parts by weight and 12.0 parts by weight of a polyamide resin was put into a test chamber of a Labo Plastomill (Toyo Seiki Seisakusho Co., Ltd., type 75C100), which had been heated to 300 ° C. in advance, and a roller type (R-100) Shape) Using a blade, the mixture was kneaded at a rotation speed of 50 rpm under heating at 300 ° C., and the torque value of the melt was measured over time. Table 1 shows the measurement results. The higher the torque value, the higher the viscosity of the melt,
Indicates poor liquidity.

Examples 4 to 6 The composition ratios of the polyamide resin of Examples 1 to 3 and the metal powder (ferrite) were 90.0 parts by weight of ferrite and 10.0 parts by weight of polyamide resin. 1 to
The test according to No. 3 was performed. Table 1 shows the results.

Comparative Example 1 A polyamide resin having a high terminal carboxyl group concentration by adding dodecane diacid during polymerization of Nylon 12 manufactured by Daicel Huls Co. (Terminal amino group concentration and relative viscosity are within the scope of the present invention. Examples 1 to 5
The test according to No. 3 was performed. Table 1 shows the results.

Comparative Example 2 A polyamide resin having a high terminal amino group concentration by adding dodecane diacid during polymerization of Nylon 12 manufactured by Daicel Huls Co. (The terminal carboxyl group concentration and relative viscosity are within the scope of the present invention. Examples 1 to 5
The test according to No. 3 was performed. Table 1 shows the results.

Comparative Example 3 A polyamide resin having a very high terminal amino group concentration by adding hexamethylene diamine during polymerization of Nylon 12 manufactured by Daicel Huels Co. (The terminal carboxyl group concentration and the relative viscosity are defined in the scope of the present invention. The test according to Examples 1-3 was performed. Table 1 shows the results
Shown in

Comparative Example 4 A polyamide resin having a high terminal amino group concentration by adding laurylamine during polymerization of Nylon 12 manufactured by Daicel Huls Co., Ltd. (the terminal carboxyl group concentration and the relative viscosity are controlled within the scope of the present invention. Example 1 using
A test according to ３3 was performed. Table 1 shows the results. Comparative Example 5 Polyamide resin having a high relative viscosity by adding dodecane diacid during the polymerization of Nylon 12 from Daicel Huls (the concentration of terminal carboxyl groups and the concentration of terminal amino groups were adjusted within the scope of the present invention). ) Using Examples 1 to
The test according to No. 3 was performed. Table 1 shows the results.

Comparative Example 6 A polyamide resin having a high terminal carboxyl group concentration by adding dodecanedioic acid during polymerization of Nylon 12 manufactured by Daicel Huels Co. (The terminal amino group concentration and the relative viscosity are within the scope of the present invention. Example 4-
The test according to No. 6 was performed. Table 1 shows the results.

Comparative Example 7 A polyamide resin having a high terminal amino group concentration by adding dodecane diacid during the polymerization of Nylon 12 manufactured by Daicel Huls Co. (The terminal carboxyl group concentration and the relative viscosity are within the scope of the present invention. Example 4-
The test according to No. 6 was performed. Table 1 shows the results.

Comparative Example 8 A polyamide resin having a very high terminal amino group concentration by adding hexamethylene diamine during polymerization of Nylon 12 manufactured by Daicel Huels Co. (The terminal carboxyl group concentration and the relative viscosity are defined in the scope of the present invention. ), And the tests according to Examples 4 to 6 were performed. Table 1 shows the results
Shown in

Comparative Example 9 A polyamide resin having a high terminal amino group concentration by adding laurylamine during polymerization of Nylon 12 manufactured by Daicel Huls Co. (the terminal carboxyl group concentration and the relative viscosity are controlled within the scope of the present invention). Example 4 using
A test according to ６6 was performed. Table 1 shows the results. Comparative Example 10 Polyamide resin having a high relative viscosity by adding dodecane diacid during polymerization of Nylon 12 from Daicel Huls (the concentration of terminal carboxyl groups and the concentration of terminal amino groups were controlled within the scope of the present invention). ) Using Examples 4 to
The test according to No. 6 was performed. Table 1 shows the results.

[0040]

[Table 1]

Claims (1)

(57) [Claims] 1. A terminal carboxyl group concentration of 90 mg equivalent / kg or less, a terminal amino group concentration of 10 mg or less, and a relative viscosity measured by a solution viscosity measurement method using a 0.5% meta-cresol solution according to DIN 53727. A high specific gravity polyamide resin composition comprising a polyamide resin having a viscosity of 1.50 to 1.70 and a metal powder.