TWI595032B - A resin composition for forming a terminal group, and a terminal group for a magnetic disk device - Google Patents

Description

Terminal group forming resin composition and disk device terminal group

The present invention relates to a resin assembly suitable for forming a terminal group for a disk device such as a hard disk drive and a terminal assembly for a disk device formed by molding the resin composition.

As shown in FIG. 1 and FIG. 2, in a disk device such as a hard disk drive (HDD), a loading/unloading mechanism for causing the head to be avoided to the outside of the disk when the driver is stopped or during a non-read/write operation is provided. 1. In the loading/unloading mechanism 1, the head 2 is to be circumvented by placing a tab 5a disposed at the front end of the suspension 5 on the terminal group 4 disposed on the outer peripheral side of the disk 3. The terminal group 4 generally includes an inclined sliding surface 4a that slides the joint 5a to hold the joint 5a, a horizontal sliding surface 4c, and a standby portion 4d that allows the magnetic head 2 to stand by at the time of stopping; the opposite surface 4b is configured to It is ensured that the space for rotating the outer peripheral portion of the disk 3 is provided and faces the recording of the disk 3; and the fixing portion 4e of the HDD body. The terminal group 4 is required to be easily manufactured and has excellent friction characteristics, and thus is usually formed of a resin or a resin composition.

In order to smoothly move the magnetic head 2 between the disk 3 and the terminal group 4, the interval between the disk 3 and the opposing surface 4b of the front end portion of the opposing terminal group 4 becomes extremely narrow. Therefore, there is a case where the disk device is subjected to an impact and the disk 3 collides with the terminal group 4. If the disk 3 collides with the terminal group 4, there is a case where the disk 3 and the terminal group 4 are damaged or deformed, or dust is generated. If such damage or deformation occurs, or dust is generated, it will be on the disk. The performance of the device has an adverse effect.

The reason for the read/write error of the data in the disk is, for example, the following (a) to (c).

a) erroneous reading and error caused by the damage of the surface of the disk caused by the hard substance contained in the additive or the like

b) The sliding surface of the terminal group and the joint at the front end of the suspension (made of metal) are slid, and the resin chips generated by the frictional wear of the two are attached to the surface of the storage disk of the HDD or stored on the disk. Read and write errors caused by the read and write heads

c) read and write errors caused by resin chips caught between the disk and the head at the same timing as the reading and writing of the data

However, as a resin for forming a terminal group, polyoxymethylene resin is widely used. The acetal resin is a resin excellent in friction and abrasion resistance. However, when the terminal group is formed only of a polyacetal resin, the obtained molded article has insufficient sliding properties. Therefore, when a polyacetal resin is used for the formation of a terminal group, it is usually used in the form of a resin composition to which a lubricant is added.

Conventionally, as such a lubricant added to the resin composition, a low molecular lubricant such as a fatty acid ester or polyethylene glycol is used. However, since the disk terminal group is used after being washed by a solvent or pure water to which a surfactant is added, there is a problem that the low molecular lubricant contained in the resin composition forming the terminal group is washed. The net midway is removed from the terminal group, and the slidability of the terminal group after solvent cleaning is significantly reduced.

On the other hand, in Patent Documents 1 to 3, a method of adding a specific polymer-based lubricant which is not removed by a solvent to a polyacetal resin for forming a terminal group is reported. However, these polymer-based lubricants are expensive, and thus cause an increase in the unit price of the entire material.

Further, Patent Document 4 discloses that an inorganic filler is added to a polyacetal resin to improve abrasion resistance. A method of rubbing wear and tear, and an example in which titanium oxide or tantalum carbide is added as an inorganic filler is disclosed, but the effect of improving the sliding resistance is not sufficient.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-63107

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-214471

[Patent Document 3] International Publication No. 2003/055945

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2002-197820

In this case, an object of the present invention is to provide a resin composition for forming a terminal group for a disk device having excellent slidability and frictional wear resistance without using a polymer-based lubricant, and to form the resin composition. A terminal group for a disk device made of a resin composition.

In order to solve the above problems, the present inventors have intensively studied and found that when a zinc oxide particle which is an inorganic pigment is added to a terminal group forming resin such as a acetal resin, the elastic modulus changes, and the resin molded article changes. The wear resistance of the surface of the (terminal group) is improved, thereby completing the present invention.

That is, the present invention relates to the following invention.

<1> A resin composition for forming a terminal group, which is obtained by dispersing zinc oxide particles in a base polymer to form a terminal group for a disk device, and satisfying the following conditions (A- 1) and (A-2).

(A-1) containing 1.0 part by weight or more and 5.0 parts by weight or less of the zinc oxide particles based on 100 parts by weight of the base polymer

(A-2) The average particle diameter of the zinc oxide particles is 0.01 μm or more and 3.0 μm or less

<2> The resin composition of the above <1>, which further satisfies the following condition (B).

(B) a horizontal sliding surface of the sample terminal group formed by molding the resin composition (Ra (calculated) Average roughness (0.1 μm),

A metal joint (Ra (arithmetic mean roughness) 0.4 μm) installed at the front end of the suspension and having a semi-circular cross section is placed so that the lowermost dome portion of the joint is in line contact at a length of 50 μm at a temperature of 5 ° C. In a humidity of 10% RH or less, the dome portion of the lowermost portion of the joint is slid over the horizontal sliding surface of the sample terminal group by 1.2 million cycles under conditions of a contact load of 2.4 g and an average speed of 200.0 mm/s. In the frictional abrasion test, the wear sectional area specified by the following area difference is 50 μm ² or less, which is the height of the cross section perpendicular to the joint sliding direction of the horizontal sliding surface of the sample terminal group after the obtained frictional wear test. Profile, the area difference from the height profile of the sample terminal set prior to the frictional wear test.

<3> The resin composition according to the above <1>, wherein the base polymer is a polyoxymethylene resin.

<4> The resin composition according to the above <1>, wherein the zinc oxide particles have an average particle diameter of 0.03 μm or more and 2.0 μm or less.

<5> The resin composition according to the above <2>, wherein the abrasion cross-sectional area in the condition (B) is 30 μm ² or less.

<6> A terminal assembly for a magnetic disk device, which is formed by the resin composition according to any one of the above <1> to <5>.

According to the present invention, it is possible to provide a resin composition for forming a terminal group for a magnetic disk device having excellent slidability and frictional wear resistance without using a polymer-based lubricant. The terminal group for a disk device obtained by molding the resin composition is excellent in slidability and frictional wear resistance, and can reduce reading and writing errors of data in the disk device, and can be used as a terminal group that realizes a low cost. And use.

1‧‧‧Loading/unloading mechanism

2‧‧‧ heads

3‧‧‧Disk

4‧‧‧ Terminal Group

4a‧‧‧Sloping sliding surface

4b‧‧‧ opposite

4c‧‧‧ horizontal sliding surface

4d‧‧‧Standing Department

4e‧‧‧Installation Department

5‧‧‧suspension

5a‧‧‧ connector

L‧‧‧ length

W‧‧‧Width

R‧‧‧ Height

Figure 1 is a schematic view of a loading/unloading mechanism of a disk device.

Fig. 2 is a schematic view for explaining a state in which a joint disposed at a front end of a magnetic head is in contact with a terminal group.

Figure 3 is a perspective view of a sample terminal set for a frictional wear test.

Figure 4 is a perspective view of the joint for the friction wear test.

Figure 5 is a cross-sectional view of a joint for a frictional wear test.

Fig. 6 is an explanatory view of a friction wear test.

Fig. 7 is a cross-sectional view showing the positional relationship between the horizontal sliding surface of the sample terminal group and the joint viewed from the direction perpendicular to the sliding direction of the joint.

Fig. 8 is a view for explaining the method of calculating the wear sectional area.

In the following, the present invention will be described in detail with reference to the accompanying drawings, and the present invention is not limited thereto, and may be arbitrarily changed without departing from the spirit and scope of the invention. Furthermore, in the present specification, the use of the expression "~" is used in the sense of including the numerical values or physical values before and after.

The resin composition for forming a terminal group of the present invention (hereinafter referred to as "the resin composition of the present invention") is obtained by dispersing zinc oxide particles in a base polymer to form a terminal group for a disk device. It is characterized by satisfying the following conditions.

(A-1) containing 1.0 part by weight or more and 5.0 parts by weight or less of the zinc oxide particles based on 100 parts by weight of the base polymer

(A-2) The average particle diameter of the zinc oxide particles is 0.01 μm or more and 3.0 μm or less

The resin composition for forming a terminal group of the present invention is characterized in that the elastic modulus of the resin material changes when an appropriate amount of inorganic particles is added to the resin material. A zinc oxide particle having a relatively small hardness is used as the inorganic particle, and an appropriate amount of the zinc oxide particle is dispersed in a resin material (base polymer) for forming a terminal group. According to this configuration, the frictional wear resistance of the surface of the resin molded article can be improved without impairing the original slidability of the resin. Therefore, when the terminal group is formed by using the resin composition, the sliding wear of the terminal group and the metal joint of the suspension front end is alleviated.

In addition, the molded article formed by adding inorganic particles such as titanium dioxide having a hardness higher than that of the zinc oxide particles to the resin material tends to have a tendency to withstand the sliding abrasion which is a practical grade of the terminal group.

As the base polymer in the resin composition of the present invention, a known resin relating to the formation of a terminal group for a disk device can be used. Specifically, a polyoxymethylene resin is mentioned. Further, in the present invention, the polyoxymethylene resin is a concept comprising a polyoxymethylene homopolymer and a copolymer based on a polyacetal resin.

When the polyoxymethylene resin is used only when the terminal group is formed of the resin, there is a problem that resin scraps easily occur due to sliding of the joint at the tip end of the suspension, but the zinc oxide particles in the above range are dispersed. The surface wear resistance is improved, and it is not easy to cause resin debris caused by sliding.

As a more preferable example of the base polymer, in order to improve formability or chip generation, a copolymer based on a polyacetal resin which is obtained by copolymerizing a formaldehyde unit and a suitable comonomer unit is more preferable.

The comonomer unit contains an oxyalkylene unit having a carbon number of 2 to 6 (for example, an oxygen-extended ethyl group (-OCH ₂ CH ₂ -), an oxygen-extended propyl group, an oxytetramethylene group, or the like). The content of the comonomer unit is about 0.01 to 20 mol% with respect to the entire polyacetal resin. As a preferred commercial product of such a base polymer, a standard grade product manufactured by Polyplastics Co., Ltd. is mentioned.

In the resin composition of the present invention, the content of the zinc oxide particles is 1.0 to 5.0 parts by weight, preferably 1.0 to 3.5 parts by weight, more preferably 1.2 to 100 parts by weight based on the base polymer. 3.3 parts by weight, particularly preferably 1.5 to 3.0 parts by weight.

When the content of the zinc oxide particles is less than 1.0 part by weight, the effect of surface modification (increased abrasion resistance) by the addition of zinc oxide particles cannot be sufficiently confirmed. Moreover, mixing with a resin becomes difficult, and it is not possible to uniformly disperse zinc oxide particles. When the content of the zinc oxide particles exceeds 5.0 parts by weight, when the terminal group is formed from the resin composition, the excess zinc oxide particles are easily detached from the terminal group with sliding. There will be the following: the detached zinc oxide particles are attached between the magnetic heads, or are sandwiched between the magnetic disk and the magnetic head at the same timing as the reading and writing of the data, and become a cause of reading and writing errors.

The zinc oxide particles have an average particle diameter of from 0.01 to 3.0 μm, preferably from 0.03 to 2.0 μm, more preferably from 0.2 to 0.6 μm. When the particle diameter of the zinc oxide particles is outside the above range, the effect of changing the elastic modulus of the resin material may not be sufficiently obtained.

Here, the average particle diameter herein means an arithmetic mean value calculated from the particle size frequency distribution (volume basis) of the zinc oxide particles. The arithmetic mean value can be obtained by, for example, a particle size distribution device (Model: LS 13 320 (laser analysis-scattering particle size distribution measuring device)) manufactured by BECKMAN COULTER.

The acetal resin composition of the present invention may be added with various additives used in conventional acetal resins, as needed, without departing from the object of the present invention. Examples of such an additive include a dispersant, a lubricant, an impact-resistant modified material, another resin, a crystal nucleating agent, a release agent, a dye, and a pigment.

The resin composition of the present invention is preferably a condition that satisfies the following condition (B). Further, the wear sectional area in the condition (B) is the wear resistance of the resin composition for the terminal group of the evaluation object in the shape of the actual terminal group.

(B) A horizontal sliding surface (Ra (arithmetic mean roughness) 0.1 μm) of the sample terminal group formed by molding the resin composition, and a metal joint which is attached to the front end of the suspension and has a semi-arc cross section (Ra (arithmetic mean roughness) 0.4 μm), the lowermost dome portion of the joint was brought into line contact with a length of 50 μm, and the contact load was 2.4 g and average at an environment of a temperature of 5 ° C and a humidity of 10% RH or less. At a speed of 200.0 mm/s, a frictional wear test was performed in which the dome portion at the lowermost end of the joint was slid over the horizontal sliding surface of the sample terminal group by 1.2 million cycles, and the wear sectional area defined by the following area difference was 50 μm ² or less. The difference in area is the height profile of the section perpendicular to the sliding direction of the joint on the horizontal sliding surface of the sample terminal group after the obtained frictional wear test, and the height profile of the sample terminal group before the frictional wear test. difference.

Hereinafter, the friction wear test and the wear sectional area in the condition (B) will be described with reference to the drawings. 3 is a perspective view of a sample terminal group for a frictional wear test, FIG. 4 is a perspective view of a joint for a frictional wear test, and FIG. 5 is a cross-sectional view of a joint for a frictional wear test (AA cross-sectional view of FIG. 4) ).

The sample terminal group for the friction wear test shown in Fig. 3 has a shape based on the terminal group actually used for the disk device, and the frictional wear test is performed on the horizontal sliding surface shown in Fig. 3.

As shown in Figs. 4 and 5, the cross section of the joint for the friction wear test has a semicircular arc shape. The joint was formed of a metal such as stainless steel, and had a length L of 0.8 mm, a width W of 0.4 mm, a height R of 0.1 mm, and a surface roughness of 0.4 μm in terms of arithmetic mean roughness Ra. Furthermore, the surface roughness of the joint can be confirmed by a laser microscope. The joint is used in the front end of the suspension of the terminal block sliding tester.

The purpose of the terminal group sliding tester is to accelerate the evaluation of the sliding action of the terminal group in the loading/unloading mechanism of the disk device (refer to Figs. 1, 2) and the joint mounted on the front end of the suspension, and the reproducible group Enter the actual position of the terminal group of the disk device - the relative position of the suspension and the sliding action, and repeat the specific number of times.

The terminal group sliding tester is not particularly limited as long as it is a frictional wear tester in the executable condition (B), and specific examples thereof include those manufactured by First Seiko Co., Ltd. Terminal group sliding tester (model: AGB013). The purpose of the testing machine is the frictional wear test of the terminal group, which does not mount the magnetic head on the suspension, but can reproduce the relative position of the terminal group-suspension and the sliding action.

Fig. 6 is an explanatory view of a frictional wear test, and Fig. 7 is a cross-sectional view showing a positional relationship between a horizontal sliding surface of the sample terminal group and a joint viewed from a direction perpendicular to the sliding direction of the joint. Further, Fig. 8 is a view for explaining the method of obtaining the wear sectional area.

In the frictional wear test, for the horizontal sliding surface of the sample terminal group (refer to FIG. 3), first, the lowermost dome portion (refer to FIGS. 4 and 5) provided as the joint is line-contacted with a length of 50 μm according to the initial value. (Refer to Figure 7). Then, under the conditions of a temperature of 5 ° C and a humidity of 10% RH or less, the bottommost portion of the joint is circulated and slided on the horizontal sliding surface of the sample terminal group under the conditions of a contact load of 2.4 g and an average speed of 200.0 mm/s. The horizontal sliding surface is rubbed and worn. Then, the height profile of the horizontal sliding surface of the sample terminal group and the direction perpendicular to the direction in which the joint is slid, and the sample terminal group before the frictional wear test, after the frictional wear test of 1.2 million cycles of the sliding abrasion, will be performed. The area difference of the height profile is defined as the "wearing sectional area". Furthermore, the height profile can be measured using a laser microscope. The specific method of abrading the cross-sectional area is described below in the examples.

The abrasion cross-sectional area specified by the above condition (B) of the resin composition of the present invention is preferably 50 μm ² or less, more preferably 30 μm ² or less, still more preferably 20 μm ² or less, and still more preferably 11 μm ² or less. When the wear sectional area exceeds 50 μm ² , when the resin molded article is used as the terminal group, there is excessive resin debris due to sliding wear of the joint at the front end of the suspension, and reading and writing of data in the disk device is generated. The fault is wrong. If the abrasion sectional area is 50 μm ² or less, it is sufficient as a resin terminal group for general magnetic disks.

The method for producing the resin composition of the present invention is not particularly limited, and a specific amount of the base polymer and the zinc oxide particles may be kneaded by a known melt kneader. Examples of the melt kneader include a single screw extruder, a twin screw extruder, and a multi-axis extruder.

Although the kneading conditions also depend on the type of the melt kneading machine, the content of the base polymer or the zinc oxide particles, it is usually about 200 ° C and about 200 rpm, and the kneading time is appropriate in the range in which the zinc oxide particles are sufficiently dispersed in the base polymer. select. Further, the dispersibility of the zinc oxide particles to the base polymer can be judged by the presence or absence of color unevenness at the time of pellet formation.

The molding method of the resin composition of the present invention is not particularly limited, and can be formed into a desired terminal group shape by a known injection molding method, compression molding method, extrusion molding method, or transfer molding method. The formed terminal group is washed and assembled into a loading/unloading mechanism of the disk device for use.

The terminal group for a magnetic disk device formed by using the resin composition of the present invention has excellent slidability and wear resistance even in a low temperature environment (for example, 5 ° C or lower). Therefore, it is possible to reduce the reading and writing errors of the data in the disk device to the extent equivalent to the conventional acetal resin composition to which the polymer-based lubricant is added, and it is more achievable than the conventional acetal resin composition. Low price.

The resin composition for forming a terminal group of the present invention can be used for a sliding member such as a pulley, a roller, a shaft, a bearing, or the like in addition to the above-mentioned terminal group.

[Examples]

Hereinafter, the present invention will be described in more detail by way of Examples. However, the present invention is not limited to the following examples without departing from the scope of the invention.

The resin composition for forming a terminal group for evaluation was produced by the following method.

(Experimental Example 1)

A specific amount of the base polymer M90S (manufactured by Polyplastics Co., Ltd., standard grade) and zinc oxide particles (manufactured by Daicel Chemical Co., Ltd., average particle diameter: 0.6 μm) were added in an amount of 0.5 part by weight based on 100 parts by weight of the base polymer. Blender (manufactured by KAWATA, SUPERMIXER SMB), from a single-axis extruder (manufactured by Toshiba Machine Co., Ltd., model: The main feed of TEM26SS was added, and then the resin composition which was kneaded and extruded by water was cooled and cut into pellets, whereby the resin for forming the terminal group of Experimental Example 1 was obtained. Particles of the composition. No color unevenness was observed in the obtained granules.

(Experimental Example 2)

Granules of the resin composition for forming the terminal group of Experimental Example 2 were obtained in the same manner as in Experimental Example 1, except that the amount of the zinc oxide particles added was changed to 0.7 parts by weight based on 100 parts by weight of the base polymer. No color unevenness was observed in the obtained granules.

(Experimental Example 3)

A pellet of a resin composition for forming a terminal group of Experimental Example 3 was obtained in the same manner as in Experimental Example 1, except that the amount of the zinc oxide particles added to the base polymer was changed to 1.2 parts by weight. No color unevenness was observed in the obtained granules.

(Experimental Example 4)

A pellet of a resin composition for forming a terminal group of Experimental Example 4 was obtained in the same manner as in Experimental Example 1, except that the amount of the zinc oxide particles added was changed to 1.5 parts by weight based on 100 parts by weight of the base polymer. No color unevenness was observed in the obtained granules.

(Experimental Example 5)

The pellet of the resin composition for forming the terminal group of Experimental Example 5 was obtained in the same manner as in Experimental Example 1, except that the amount of the zinc oxide particles added to the base polymer was changed to 2.0 parts by weight. No color unevenness was observed in the obtained granules.

(Experimental Example 6)

The pellet of the resin composition for forming the terminal group of Experimental Example 6 was obtained in the same manner as in Experimental Example 1, except that the amount of the zinc oxide particles added was changed to 2.5 parts by weight based on 100 parts by weight of the base polymer. No color unevenness was observed in the obtained granules.

(Experimental Example 7)

The addition amount of the zinc oxide particles to 100 parts by weight of the base polymer is set to 3.0 parts by weight. The pellet of the resin composition for forming the terminal group of Experimental Example 7 was obtained in the same manner as in Experimental Example 1. No color unevenness was observed in the obtained granules.

(Experimental Example 8)

A pellet of a resin composition for forming a terminal group of Experimental Example 8 was obtained in the same manner as in Experimental Example 1, except that the amount of the zinc oxide particles added to the base polymer was changed to 4.0 parts by weight. No color unevenness was observed in the obtained granules.

(Experimental Example 9)

A pellet of a resin composition for forming a terminal group of Experimental Example 9 was obtained in the same manner as in Experimental Example 1, except that the amount of the zinc oxide particles added to the base polymer was changed to 5.0 parts by weight. No color unevenness was observed in the obtained granules.

(Experimental Example 10)

Granules of the resin composition for forming the terminal group of Experimental Example 10 were obtained in the same manner as in Experimental Example 1, except that the amount of the zinc oxide particles added to the base polymer was changed to 6.0 parts by weight. No color unevenness was observed in the obtained granules.

(Experimental Example 11)

The terminal of Experimental Example 11 was obtained in the same manner as in Experimental Example 1, except that zinc oxide particles having an average particle diameter of 0.035 μm and zinc oxide particles were added in an amount of 1.5 parts by weight based on 100 parts by weight of the base polymer. The particles of the resin composition for forming a group. No color unevenness was observed in the obtained granules.

(Experimental Example 12)

The terminal of Experimental Example 12 was obtained in the same manner as in Experimental Example 1, except that zinc oxide particles having an average particle diameter of 0.29 μm and zinc oxide particles were added in an amount of 1.5 parts by weight based on 100 parts by weight of the base polymer. The particles of the resin composition for forming a group. No color unevenness was observed in the obtained granules.

(Experimental Example 13)

The terminal group of Experimental Example 13 was obtained in the same manner as in Experimental Example 1, except that zinc oxide particles having an average particle diameter of 2 μm were used, and the amount of zinc oxide particles added was changed to 1.5 parts by weight based on 100 parts by weight of the base polymer. A pellet of the resin composition used is formed. No color unevenness was observed in the obtained granules.

(Experimental Example 14)

The terminal group of Experimental Example 14 was obtained in the same manner as in Experimental Example 1, except that zinc oxide particles having an average particle diameter of 11 μm were used, and the amount of zinc oxide particles added was changed to 1.5 parts by weight based on 100 parts by weight of the base polymer. A pellet of the resin composition used is formed. No color unevenness was observed in the obtained granules.

<Manufacture of sample terminal group for evaluation of wear sectional area>

The granules of the resin compositions of Experimental Examples 1 to 10 were dried by a dryer (hopper dryer manufactured by MATSUI, type HD2), and then formed into a mold for use by an evaluation terminal equipped with an upper and lower mold. The injection molding machine (the injection molding machine manufactured by Sumitomo Heavy Industries, Ltd.) was molded, and the sample terminal group for the abrasion test of Experimental Examples 1 to 10 having the shape shown in Fig. 3 was obtained.

<Friction wear test of sample terminal group>

The abrasion resistance of the above sample terminal group was evaluated using a terminal group sliding tester (manufactured by Seiko Seiko Co., Ltd., model: AGB013). The purpose of the terminal group sliding tester is to accelerate the test of the sliding action of the terminal assembly of the HDD and the joint of the suspension, and to reproduce the relative position and sliding of the terminal group-suspension incorporated into the actual HDD. Actions and repeat the specific number of times.

As shown in FIG. 6, the friction wear test is for the sample terminal group of FIG. 3, and the suspension is reciprocated in the region of the inclined sliding surface, the horizontal sliding surface, and the sliding surface of the standby portion, and the horizontal sliding of the terminal group contacted by the joint is performed. Evaluation of the wear of the surface. Further, the sliding of the joint is one cycle of the inclined sliding surface, the horizontal sliding surface, and the standby sliding surface in FIG.

More specifically, after the sample terminal group is placed at a specific position of the terminal group sliding tester, the joint of the suspension front end made of elastic material (stainless steel) in the terminal group sliding test machine is made (refer to FIG. 4, 5) Contact the horizontal sliding surface of the sample terminal group of Fig. 3 in such a manner that the initial contact maximum load reaches 2.4 g. Then, under the condition of applying a load, the suspension is repeatedly shaken by the driving device at an average speed of 200.0 mm/s (1 cycle of 0.08 sec) in an environment of a temperature of 5 ° C and a humidity of 10% RH or less for the terminal group. Ten thousand cycles were taken to obtain a sample after the frictional wear test. The horizontal sliding surface of the sample terminal group has a surface roughness Ra (arithmetic average roughness) of 0.1 μm, the joint is made of metal and has a semi-cylindrical cross section, and has a surface roughness Ra (arithmetic mean roughness) of 0.4 μm and a dome portion thereof. Line contact was made with a horizontal sliding surface of the sample terminal group at a length of 50 μm. Furthermore, the surface roughness Ra of the horizontal sliding surface or the joint of the sample terminal group was measured using a laser microscope (KEYENCE Co., Ltd., type VK-9700). Further, in each of the friction and wear tests, the suspension and the joint were replaced with the sample terminal group for evaluation.

<Evaluation of the wear amount (abrasion sectional area) of the sample terminal group before and after the friction wear test>

The amount of wear of the sample terminal group before and after the frictional wear test was evaluated by the wear sectional area obtained by the following method.

First, a laser microscope (KEYENCE Co., Ltd., type VK-9700) was used to obtain a height profile of the sample terminal group before the frictional wear test at any position of the sliding surface (the sliding portion of the joint). Then, in the same position as the above-described position of the sliding surface (the portion with the abrasion trace of the joint) in the sample terminal group after the frictional wear test, the height profile was obtained in the same manner. The difference in area when the contours are superposed is defined as the wear sectional area (see Fig. 8). Furthermore, the evaluation of the height profile was performed using the analysis software (VK Analyzer) attached to the above-described laser microscope.

<evaluation result>

(1) Dependence of the addition amount of zinc oxide particles

The results of the frictional abrasion test of the sample terminal groups of the above Experimental Examples 1 to 10 are shown in Table 1. Further, the wear sectional area of Table 1 is an average value when the sample terminal group is n=3 or more.

In Experimental Example 2 in which the amount of zinc oxide particles added was 0.7 parts by weight based on 100 parts by weight of the base polymer, and in Experimental Example 10 in which 6.0 parts by weight, the abrasion cross-sectional area exceeded 50 μm ² , but the amount of zinc oxide particles added thereto was In Experimental Examples 3 to 9 in the range of 1.0 part by weight or more and 5.0 parts by weight or less, the abrasion sectional area was 50 μm ² or less, and the abrasion suppressing effect of the terminal group resulting from the addition of zinc oxide was confirmed. In addition, the average value of Experimental Example 1 in which the amount of addition was 0.5 parts by weight was 50 μm ² or less, but the difference in the cross-sectional area of the abrasion of each sample terminal group became large.

Further, when the amount of the zinc oxide particles added is in the range of 1.2 parts by weight or more and 4.0 parts by weight or less as in Experimental Examples 3 to 8, the abrasion cross-sectional area is greatly reduced. In particular, when the amount of the zinc oxide particles added is from 1.5 parts by weight to 3.0 parts by weight, the abrasion cross-sectional area is 11 μm ² or less, which is extremely small. It is thus apparent that by adding a specific amount of zinc oxide particles to the base polymer, the abrasion of the sample terminal group can be suppressed.

(2) Particle size dependence of zinc oxide particles

Table 2 shows the results of the frictional abrasion test of the sample terminal groups of Experimental Examples 4 and 11 to 14 in which zinc oxide particles having an average particle diameter of 0.035 to 11 μm were added in an amount of 1.5% by weight.

In Experimental Example 14 having a particle diameter of 11 μm, the abrasion cross-sectional area was 200 μm ² or more, which was very large, and it was found that the abrasion suppressing effect by the addition of zinc oxide particles was small. On the other hand, in Experimental Examples 4 and 11 to 13 having a particle diameter of 2.0 μm or less, the abrasion cross-sectional area was 50 μm ² or less, and the abrasion inhibiting effect by the addition of zinc oxide particles was confirmed. In particular, in Experimental Examples 4 and 11 to 12 having a particle diameter of 0.035 to 0.6 μm, the abrasion cross-sectional area was 10 μm ² or less, and it was found that the abrasion suppression effect was excellent.

<Reference example>

(Reference example 1)

Using the pellet of the above Experimental Example 1 containing 0.5 part by weight of zinc oxide particles, the same sample terminal group as in Experimental Example 1 was produced under the same conditions as in Experimental Example 1, and a frictional abrasion test was performed.

The frictional wear test and evaluation of the sample terminal group set the initial contact maximum load in the friction wear test to 2.2 g, the humidity to 40% RH, and the dome portion of the joint to slide horizontally with the length of the sample terminal group by 70 μm. The same procedure as in Experimental Example 1 was carried out except that the surface was subjected to line contact. The results are shown in Table 3.

(Reference example 2)

As a reference example 2, titanium dioxide (TiO ₂ ) particles were used as the inorganic particles other than the zinc oxide particles, and the same sample terminal group as in the above Experimental Example 1 was produced, and a friction abrasion test was performed.

A specific amount of the base polymer M90S (manufactured by Polyplastics Co., Ltd., standard grade) and rutile-type titanium oxide (average particle diameter: 0.21 μm) were added to the blender in an amount of 0.5 part by weight based on 100 parts by weight of the base polymer ( After being manufactured by KAWATA, SUPERMIXER SMB), it was added from the main hopper of a single-axis extruder (manufactured by Toshiba Machine Co., Ltd., model: TEM26SS), and then the resin composition was kneaded by water cooling and cut and made. The state of the particles, whereby particles of the resin composition for forming the terminal group of Reference Example 1 were obtained.

Using the pellets of the resin composition of Reference Example 2, the sample terminal group for the frictional abrasion test of Reference Example 2 was obtained in the same manner as the method for producing the sample terminal group for the evaluation of the abrasion cross-sectional area.

The frictional wear test and evaluation of the sample terminal group were carried out in the same manner as in Reference Example 1. Further, the base polymer M90S used tends to be easily worn when the humidity is low. The results are shown in Table 3.

(Reference Example 3)

As a reference example 3, a sample terminal group composed of only a base polymer containing no zinc oxide particles was produced, and a frictional abrasion test was performed.

Using the pellets of the resin composition of Reference Example 3, the sample terminal group for the frictional abrasion test of Reference Example 3 was obtained in the same manner as the method for producing the sample terminal group for the evaluation of the abrasion sectional area.

The frictional wear test and evaluation of the sample terminal group was the same as the evaluation method in the experimental example except that the humidity was set to 40% RH. Further, the base polymer M90S used tends to be easily worn when the humidity is low. The results are shown in Table 3.

As shown in Table 3, it was found that the sample terminal group of Reference Example 3 containing no inorganic particles had a wear sectional area of more than 400 μm ² and insufficient frictional wear resistance.

Further, Reference Example 2 in which titanium dioxide particles were added had a larger abrasion sectional area (abrasion amount) than Reference Example 1 in which zinc oxide particles were added. From this, it was confirmed that the zinc oxide particles can improve the frictional wear resistance of the resin composition more than the titanium oxide particles when the same amount of inorganic particles are added.

[Industrial availability]

The resin composition for forming a terminal group of the present invention can be used for a wiring device terminal group having excellent slidability and wear resistance without using a polymer-based lubricant. The terminal group for a disk device obtained by molding the resin composition is excellent in slidability, wear resistance, and can reduce reading and writing errors of data in the disk device, and can be reduced in cost.

L‧‧‧ length

W‧‧‧Width

Claims (4)

A resin composition for forming a terminal group, which is obtained by dispersing zinc oxide particles in a base polymer to form a terminal group for a disk device, and is characterized in that the following conditions are satisfied ( A-1) and (A-2): (A-1) contains 1.0 part by weight or more and 5.0 parts by weight or less of the zinc oxide particles based on 100 parts by weight of the base polymer; (A-2) the zinc oxide particles The average particle diameter is 0.2 μm or more and 0.6 μm or less; and the base polymer is a polyoxymethylene lcene resin. The resin composition of claim 1 further satisfies the following condition (B): (B) a horizontal sliding surface of the sample terminal group formed by molding the resin composition (Ra (arithmetic mean roughness) 0.1 Μm), a metal tab (Ra (arithmetic mean roughness) 0.4 μm) mounted on the front end of the suspension and having a semi-circular cross section is placed so that the lowermost dome portion of the joint is 50 μm long. Wire contact, at a temperature of 5 ° C and a humidity of 10% RH or less, with a contact load of 2.4 g and an average speed of 200.0 mm/s, the bottom portion of the joint is slid to the level of the sample terminal group. The frictional wear test of the sliding surface of 1.2 million cycles, the wear sectional area specified by the following area difference is 50 μm ² or less, which is the horizontal sliding surface of the sample terminal group after the obtained frictional abrasion test and the joint The height profile of the profile perpendicular to the sliding direction and the height profile of the sample terminal set prior to the frictional wear test. The resin composition of claim 2, wherein the abrasion cross-sectional area in the condition (B) is 30 μm ² or less. A terminal group for a magnetic disk device, which is formed by forming a resin composition according to any one of claims 1 to 3.