JPS61180542A - Motor casing - Google Patents

Abstract

PURPOSE:To improve heat resistance, mechanical properties, heat dissipation and dimensional accuracy by mixing aromatic polyether ketone resin, fibrous inorganic filler and thermoconductive inorganic filler at special composition ratio to form a resin composition. CONSTITUTION:A resin composition is produced by aromatic polyether ketone resin (A), fibrous inorganic filler (B) and thermoconductive inorganic filler (C) having 1.3kcal/m.hr. deg.C of higher of thermal conductivity. The composition is produced to contain 5-100pts.wt. with respect to 100pts.wt. of (A), 5-150pts. wt. of (C) and the total amount of (B) and (C) is 250pts.wt. or lower. A motor casing is formed with the resin composition. Here, (B) may use asbestos fiber or wollastonite fiber, and (C) may use silica or alumina.

Description

[Detailed Description of the Invention] CI) Purpose of the Invention (Industrial Field of Application) The present invention is made by molding a resin composition consisting of an aromatic polyetherketone resin with excellent heat resistance and two types of inorganic fillers. Regarding motor casing. More specifically, it relates to a motor casing formed by molding a composition consisting of (A) aromatic polyetherketone resin, (B) HAM-like inorganic filler, and (C) thermally conductive inorganic filler, and has heat resistance. The object of the present invention is to provide a motor casing that not only has good mechanical properties and heat dissipation properties, but also has good dimensional accuracy.

(II) Background of the invention (prior art) Aluminum die-cast products are used as casings for motors, especially small motors such as non-tipped motors used in VTRs (video tape recorders), cassette decks, etc. properties, sliding properties,
It is widely used because of its good properties such as mechanical strength. However, since it is difficult to achieve accurate dimensional accuracy with aluminum die-cast products, not only a post-finishing process is always required, but also a complicated quality control process to check the dimensional accuracy of each side.

In addition, corrosion occurs due to humidity, and depending on the environment, painting may be necessary. For this reason, attempts have been made to manufacture casings by precision molding using thermoplastic resins. However, if thermoplastic resin is simply used, the casing will deform over time when the motor casing is assembled, causing problems such as abnormal rotation of the rotor. It is extremely difficult to prevent temperature rises due to heat generation, leading to problems such as deterioration of insulators and damage to bearings and commutators due to burnout.

(m) Structure of the Invention Based on the above, the present inventors have conducted various searches to obtain a motor casing that solves these problems. Inorganic filler and (C) thermal conductivity is 1.3Kcal/m*hr @
It consists of a thermally conductive inorganic filler with a molecular weight of 100 parts by weight or more, and the composition ratio of the fibrous inorganic filler to 100 parts by weight of aromatic polyetherketone resin is 5 to 150 parts by weight.
Furthermore, the composition ratio of the thermally conductive inorganic filler is 5 to 150 parts by weight, but the total amount of these inorganic fillers is at most 250 parts by weight per 100 parts by weight of the aromatic polyetherketone resin. The motor casing is made by molding a resin composition.

We have discovered a motor casing that has solved all of the above problems, that is, has not only good heat resistance, but also excellent mechanical properties and heat dissipation, as well as good dimensional accuracy, and have arrived at the present invention. .

(IV) Detailed Description of the Invention (A) Aromatic Polyetherketone Resin The polyetherketone resin used in the present invention is well known as described in European Patent Publication No. 1879.

It is obtained by polycondensation reaction of bisphenol and aromatic cibaride in the presence of an alkali metal bicarbonate, and is represented by the structural formula. In addition, the intrinsic viscosity (100cm
(measured at 25°C by dissolving 0.1 g of polymer in concentrated sulfuric acid of
The melt viscosity at a shear rate of 1000°C (1/5ea) is generally 1000 poise or more.

Specific examples of the aromatic polyetherketone resin include Pictrex PEEK (trade name) 45G and 38G from Imbellial Chemical Industries Ltd. (UK).

15P etc. can be given.

(B) Fibrous inorganic filler Furthermore, the average diameter of the fibrous inorganic filler used in the present invention is usually 0.5 to 100 microns, and 1 to 100 microns.
70 microns is preferred, particularly 1 to 50 microns. If a fibrous inorganic filler with an average diameter of less than 0.5 microns is used, it is difficult to uniformly disperse the filler during the production of the composition.

On the other hand, if fibers exceeding 100 microns are used, the resulting molded product (motor casing) will have poor rigidity, which is undesirable.Furthermore, the average length of the fibers is generally 0.1 to 6 layers. , 0.1 to 5 fat layer is desirable;
Particularly suitable is 0.1 to 4 cm.

If a fibrous inorganic filler with a length of less than 0.1 mm is used, it is undesirable because the rigidity of the motor casing is poor, whereas if one is used with a length of more than 8 mm, it may be difficult to disperse it uniformly during mixing. This is a problem because it is difficult. Moreover, the volume resistivity value of the fibrous inorganic filler is 0.
．． It is 1Ω·C11 or more, particularly preferably 10Ω·011 or more.

Volume resistivity value is 0. If a fibrous inorganic filler (for example, aluminum fiber, metal fiber such as steel wool) having a value of less than 1Ω·C11 is used, a problem arises because the insulation properties of the composition are reduced.

Preferred representative examples of the fibrous inorganic filler of the present invention include asbestos man, wollastonite fiber, glass fiber, milled glass fiber, carbon fiber, milled carbon fiber, alumina fiber, silicon carbide fiber, and potassium titanate fiber. can give.

(C) Thermal conductive inorganic filler The thermal conductivity of the thermally conductive inorganic filler used in the present invention (measured according to ASTM G-177) is 1.3K.
cal/m*hr*” is greater than or equal to 0, and 1
．． 5Kcal/m@hr◆℃ or higher is preferable, and 2.0Kcal/m@hr◆°C or higher is particularly preferable.

If an inorganic filler with a thermal conductivity of less than 1.3 Kcal/m@hr・°C is used, the molded product of the resulting composition (
The average particle size of this thermally conductive inorganic filler is generally from 0.1 to 70 microns, preferably from 0.2 to 50 microns, and especially from 0.2 to 50 microns. .5 to 30 microns is optimal. If a thermally conductive inorganic filler with an average particle size of less than 0.1 micron is used, it will be difficult to uniformly disperse the filler in producing the composition. On the other hand, if a thermally conductive inorganic filler with a diameter exceeding 70 microns is used, the impact resistance of the molded product (motor casing) obtained from the composition will be low, which is undesirable.

Representative examples of desirable thermally conductive inorganic fillers of the present invention include silica, alumina, silicon carbide, boron nitride,
Examples include powders such as graphite and carbon black.

(D) Composition ratio In the composition used for manufacturing the motor casing of the present invention, aromatic polyetherketone resin 100%
The blending ratio of the fibrous inorganic filler to parts by weight is 5 to 15.
0 parts by weight, preferably 10 to 150 parts by weight, particularly preferably 20 to 120 parts by weight. Said resin 10
If the blending ratio of the fibrous inorganic filler to 0 parts by weight is less than 5 parts by weight, the resulting composition will have low mechanical strength, especially rigidity, while if it exceeds 150 parts by weight, uniform dispersion will become difficult. .

Further, the blending ratio of the thermally conductive inorganic filler to 100 parts by weight of the aromatic polyetherketone resin is 5 to 150 parts by weight, preferably 10 to 150 parts by weight, and especially 3 to 150 parts by weight.
0 to 100 parts by weight is suitable. If the blending ratio of the thermally conductive inorganic filler to 100 parts by weight of the resin is less than 5 parts by weight, the heat dissipation properties of the composition will be poor. On the other hand, if it exceeds 150 parts by weight, it becomes difficult to obtain a uniform composition.

Further, the total amount of these fibrous inorganic fillers and thermally conductive inorganic fillers is at most 250 parts by weight based on 100 parts by weight of the aromatic polyetherketone resin, and especially 30 to 30 parts by weight.
200 parts by weight is preferred.

(E) Production of Composition In order to produce the resin composition of the present invention, the aromatic polyetherketone resin, the fibrous inorganic filler, and the thermally conductive inorganic filler are mixed within the above composition ratio range. In manufacturing this composition, all the components may be mixed at the same time, or at least a part of the components containing the aromatic polyetherketone resin may be mixed in advance. A so-called masterbatch may be produced, and this masterbatch and the remaining composition components may be mixed to produce a composition having the above-mentioned composition ratio.

The resin composition of the present invention includes an aromatic polyetherketone resin,
It consists of a fibrous inorganic filler and a thermally conductive inorganic filler, but in addition to these compositional ingredients, it also contains stabilizers against oxygen, heat and ultraviolet rays, flame retardants, metal deterioration inhibitors, colorants, and electrical properties. Additives such as modifiers, antistatic agents, lubricants, processability modifiers, and tack modifiers may be incorporated within the range that does not impair the properties of the resin composition of the present invention.

To produce this composition, it may be triblended using mixers such as Henschel mixers and tumblers commonly used in the synthetic resin industry, or melt-kneaded using mixers such as screw extruders. It can also be manufactured by At this time, a more uniform composition can be obtained by tri-blending in advance and further melt-kneading the resulting mixture.

Regardless of whether the composition is melt-kneaded or molded as described below, if the process is carried out at high temperatures, the aromatic polyetherketone resin, which is a component of the composition, may deteriorate. Therefore, melt kneading and molding generally require 40
It is preferable to carry out at 0°C or lower.

(F) Production of motor casing The composition obtained as described above is molded into motor casings of various shapes by an injection molding method practiced in the field of synthetic resins. At this time, the injection molding temperature is higher than the softening temperature of the aromatic polyetherketone resin, but lower than the deterioration temperature, and it is generally preferable to carry out the injection molding in a temperature range of 280 to 400°C.

(V) Effects and Applications of the Invention The motor casing obtained by the present invention exhibits the following effects (characteristics).

(1) Not only is it easy to mold, but it also has excellent one-dimensional viscosity, so secondary processing and finishing are not required.

(2) # Good humidity and no corrosion even under high humidity.

(3) It has excellent mechanical strength (for example, bending strength, tensile strength, and bending modulus), and has small creep deformation.

(4) Due to its high thermal conductivity, heat does not accumulate inside the casing.

(5) It is lightweight.

Since the motor casing obtained by the present invention exhibits the above-mentioned excellent effects, it can be supplied in large quantities at low cost as a casing, and can be stably used as a motor for a long period of time.

The motor casing obtained by the present invention can be used as a casing for a motor used in the following articles.

(1) Video tape recorder (VTR) (2) Audio equipment (for example, turntable) (3) Facsimile- (0 tape-recorder (radio cassette, cassette deck, oven reel) (Vl) Examples and comparisons EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the Examples and Comparative Examples, the bending strength and bending modulus were both measured according to ASTM D-790, and the tensile strength was measured according to ASTM D-838. Furthermore, the coefficient of linear expansion is ASTM D-898.
The thermal conductivity was measured according to ASTM G-177.
Measured according to. In addition, the creep test is AST
According to MD-790, temperature is 120℃ and load is 3
A bending creep test was conducted under the condition of 50 kg/crn', and the amount of strain after 1000 hours was measured. Furthermore, the sled heated the molded motor casing from room temperature to 100℃ over 2 hours, left it at this temperature for 2 hours,
Then, the temperature was lowered to 20° C. over 2 hours, and the sample was left at this temperature for 2 hours. After performing this heat cycle a total of 30 times, the warpage of the plane (maximum warpage height) was measured.

In addition, as a practical test of thermal conductivity, each obtained motor casing was assembled into a motor (DC8V, holding torque), and then operated under the condition of 8Kg@cm. The temperature at point C) is 120
The time taken to reach ``C'' was measured.

Note that the aromatic polyetherketone resin, fibrous inorganic filler, thermally conductive inorganic filler, and other inorganic fillers used in the Examples and Comparative Examples each have the following shapes and physical properties.

[(A) Aromatic polyetherketone resin] Aromatic polyetherketone resin having a melt viscosity of 3800 poise (manufactured by Imperial Chemical Industries, trade name: Pictrex P)
EEK38G, hereinafter referred to as "rPEE") was used.

[(B) Fibrous inorganic filler] As the fibrous inorganic filler, chopped glass N11 fibers (hereinafter referred to as rGF) with an average diameter of 13 microns and a length of 3 mm were used.
J) was used.

[(C) Thermally conductive inorganic filler]

As a thermally conductive inorganic filler, silicon carbide with an average particle size of 1.0 microns (thermal conductivity 78 Kcal/mah
r*”0, volume resistivity 200Ω @ elm, hereinafter rs
boron nitride with rough and average particle size of 1.5 microns (thermal conductivity 35 Kcal/m a hr
@'C! , volume resistivity of 1014 Ω·cm or more, hereinafter referred to as rBNJ) was used.

[(D) Other inorganic fillers]

For comparison, other inorganic fillers with an average particle size of 5.
．． Calcium carbonate is 0 micron (thermal conductivity 1.0K)
cal/m*hr*”O1 volume resistivity 10
14Ωm C11 (hereinafter referred to as rcacO3J) was used.

A fibrous inorganic filler and a thermally conductive inorganic filler [In Comparative Example 3, CaCO3 was used; in Comparative Example 4, CaCO
3 and SiC (mixture ratio CaCO3/5iC
= 40/130 (weight ratio)] was tri-blended for 5 minutes using a tumbler. ).

Each of the resulting mixtures was melted and kneaded using an extruder (diameter: 40 ml) at a resin temperature of 320° C. to produce pellets. Each pellet obtained was injection molded Ia at a mold clamping pressure of 100 tons (cylinder temperature 320°C).
, mold temperature 150° C.) to produce test pieces for measuring physical properties and motor casings. The manufactured motor casing will be explained with reference to the drawings. Figure 1 is a back view of the motor casing, and Figure 2 is A-A in Figure 1.
The size of the motor casing is as follows. The wall thickness is 2 m, and the casing is tightened by the distance between the holes (the distance between 3' and 31 in Figure 1). ) is 4
0+sm, and the height (as shown in Figure 2) is 10 mm.

Note that FIG. 3 is a cross-sectional view of the obtained motor casing assembled into a motor. In Figure 3, 4
is a rotor, and 5 is a bearing. 6 is the shaft of the motor, and 7 is a magnet.

The tensile strength, bending strength, bending modulus,
Measurements of linear expansion coefficient and thermal conductivity, creep tests, and practicality tests for warpage and thermal conductivity of each motor casing were conducted.

The results are shown in Table 2.

Note that the motor casings obtained in Comparative Examples 1 and 4 were destroyed when assembled into a motor.

(Left below) Comparative Example 5 100 parts by weight of PEEK, 150 parts by weight of glass fiber (CF) and 150 parts by weight of SiC were triblended in the same manner as in Example 1, and the resulting mixture was kneaded. However, it was not possible to obtain a uniform composition.

From the results of the above Examples and Comparative Examples, the motor casing obtained by the present invention and the composition for manufacturing the same have excellent mechanical strength such as tensile whitening, bending strength, and bending modulus (rigidity). Not only does it have a high thermal conductivity, so no heat is trapped inside the casing.
Furthermore, it is clear that creep deformation and warpage due to heat are small.

FIG. 2 is a back view of the motor casing, and FIG. 2 is an end view taken along line AA' in FIG. 1. Furthermore, FIG. 3 is a sectional view of the obtained motor casing assembled into a motor.

l... Hole 2 for rotor shaft... Rib 3 for rotor bearing... Hole 4 for tightening the casing...
Rotor 5...Bearing 6...Shaft 7...Magnet

Claims (1)

[Claims] (A) aromatic polyetherketone resin, (B) fibrous inorganic filler, and (C) thermally conductive inorganic filler having a heat transfer rate of 1.3 Kcal/m・hr・°C or more The composition ratio of the fibrous inorganic filler to 100 parts by weight of aromatic polyetherketone resin is 5 to 150 parts by weight, and the composition ratio of the heat-conductive inorganic filler is 5 to 150 parts by weight. However, the motor casing is formed by molding a resin composition in which the total amount of these inorganic fillers is at most 250 parts by weight based on 100 parts by weight of the aromatic polyetherketone resin.