JPH06228362A - Resin composition - Google Patents

Abstract

PURPOSE:To provide a resin composition which has satisfactory sliding properties and can hence be used as a sliding member on which a magnetic tape slides, e.g. a tape guide post or cylinder drum. CONSTITUTION:A resin composition comprising 95-45vol.% thermoplastic resin (a) and 5-60vol.% carbon material (b) which contains one having an average particle diameter of 0.1-100mum, desirably 0.5-50mum, and giving a block molding with a Shore hardness of 50 or higher. A resin composition which comprises 94.5-20vol.% the resin (a), 15-60vol.% at least either of carbon fibers and the material (b), and 0.5-40vol.% polyethylene, and in which the ratio of the melt viscosity of the resin (a) to that of the polyethylene at a shear rate of 1X10<3>sec<-1> at the molding temp. for the composition is 0.5-3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition having excellent sliding properties for magnetic tapes such as VTR and DAT.

[0002]

2. Description of the Related Art A member such as a tape guide post or a cylinder drum that slides on a magnetic tape is required to have sliding characteristics such as a low friction coefficient and little damage to the magnetic tape. Conventionally, since a resin composition satisfying the slidability with respect to a magnetic tape has not been obtained, metal parts have been used as parts (portions) that slide with the magnetic tape. For example, in a tape guide post, a stainless steel guide pin is press-fitted into a base member made of resin or die cast.

[0003]

However, in the conventional structure, the base component supporting the metal component cannot be integrally formed, which increases the number of assembly steps of the component and hinders weight reduction and size reduction. .

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to find a resin composition satisfying the sliding characteristics required for a magnetic tape sliding component, to reduce the man-hours for assembling the component, and to reduce the weight and size of the component. It is in. The inventor

1) 95 to 45% by volume of thermoplastic resin, 0.1 to 100 μm average particle size (preferably 0.5 to 50 μm)
m), a resin composition comprising 5 to 60% by volume of a carbon material containing a molded block having a Shore hardness of 50 or more,
It has been found that the magnetic tape has excellent sliding properties.

Further, as a result of further study, 2) thermoplastic resin 94.5 to 20% by volume and carbon fiber or
Or an average particle size of 0.1 to 100 μm (preferably 0.5 to
50 μm), the Shore hardness of the molded block body is 50 or more.
At least one of the carbon materials of 15 to 60% by volume
And a resin composition containing 0.5 to 40% by volume of polyethylene.
Therefore, the shear rate of the molding temperature of the composition is 1 * 10. ³(Sec
^-1) Melt viscosity ratio of thermoplastic resin to polyethylene
However, a resin composition satisfying the relationship of 0.5 to 3 is more excellent.
It has been found that it has excellent sliding characteristics.

In addition, 3) 83.5 to 20% by volume of a thermoplastic resin and carbon fiber or an average particle diameter of 0.1 to 100 μm (preferably 0.5 to
50 μm), and at least one of the carbon materials having a Shore hardness of 50 or more of the molded block body is 15 to 60% by volume.
And an inorganic filler consisting of at least one of ceramic whiskers having a Mohs hardness of 3 or more and inorganic powders, 1.5 to 30% by volume.
A resin composition consisting of a carbon fiber or a carbon material and a resin composition satisfying the relationship of the compounding ratio of the inorganic filler of 1: 1 to 10: 1 is also excellent as the resin composition of the above 2). It was found that it has sliding characteristics.

(Thermoplastic resin) The thermoplastic resin used in the present invention includes ABS resin, polyacetal (POM), polyamide 6 (PA6), polyamide 66 (PA66),
Polycarbonate (PCa), polysulfone, polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polybutylene terephthalate (P
BT), polyether sulfone (PES), polyether imide (PEI) and the like can be used. A single substance or a mixture of two or more types may be used.

Since the magnetic surface and the back surface of the magnetic tape have different physical properties such as a friction coefficient, it is preferable to use a resin suitable for the usage conditions of the molded part. In particular,
PCa, PPS, PEI, PA when sliding on a magnetic surface
It is desirable to use at least one of 66, PA6 and POM. When sliding on the back surface, P
It is desirable to use at least one of Ca, PPS, PEI, ABS and PES. Furthermore, high dimensional accuracy,
When rigidity and strength are required, PCa, PPS, PE
It is desirable to use at least one of I and PES.

(Carbon Material) As the carbon material, carbon powder having an average particle diameter of 0.1 to 100 μm and a Shore hardness of the molded block body of 50 or more can be used. More preferably, the average particle size is 0.5 to 50 μm, and 0.5 to 20 μm.
Most preferably, the thickness is μm. Average particle size is 100 μm
If it exceeds, the friction coefficient increases and the slidability is remarkably reduced. The shape of the carbon powder is preferably irregular or spherical. A scale-like material such as natural graphite is not preferable because the graphite molecular layer on the surface of the molded article of the composition is easily arranged in the surface direction and the graphite is significantly worn during sliding to increase the friction coefficient. The Shore hardness is more preferably 50 to 110. When the Shore hardness is less than 50, the wear is severe, and as a result, the coefficient of friction is also increased.

As the carbon fiber, PAN-based carbon fiber obtained by carbonizing acrylonitrile fiber and pitch-based carbon fiber obtained by firing pitch can be used.
Graphitized at temperatures above ℃ and tensile modulus of 300GP
A or more is preferable in that the magnetic tape is less scratched, and a tensile elastic modulus of 330 GPa or more is more preferable.
The average fiber diameter is 3 to 20 μm (more preferably 3 to 10).
μm), the average fiber length is preferably 0.5 to 10 mm (more preferably 0.5 to 6 mm), and the average fiber length of the carbon fibers in the resin composition after injection molding is 0.03 to 10 mm.
In the case of (preferably 0.03 to 1 mm), the balance of slidability, mechanical strength and dimensional stability is excellent.

The blending amount of the carbon material is 5 to 60% by volume, preferably 15 to 60% by volume, more preferably 25 to 5%.
It is 0% by volume. If it is less than 5% by volume, the effect of the invention cannot be obtained, and if it exceeds 60% by volume, not only the fluidity is lowered, but also the sliding surface is roughened at the time of molding to lower the slidability.

(Polyethylene) As polyethylene,
In addition to various types of high-density, medium-density, branched low-density and linear low-density polyethylene, resinous copolymers containing ethylene as a main component can be used. Above all, the density is 0.9
High density polyethylene of 40 g / cm ³ or more is preferable.
Melt flow rate (MFR) is 190 ° C, 2.16K
It is preferably 0.03 to 25 g / 10 min under g load,
0.5 to 15 g / 10 min is more preferable.

The content of polyethylene is 1 to 50% by volume, preferably 1 to 20% by volume, and the volume ratio to the thermoplastic resin (thermoplastic resin / polyethylene) is 1 or less.
If it is less than 1% by volume, the slidability is not improved, and if it exceeds 50% by volume, the mechanical strength and the dimensional accuracy are lowered, and the coefficient of friction increases with use.

The melt viscosity ratio between the thermoplastic resin and polyethylene (thermoplastic resin / polyethylene) is 0.5 to 8, preferably at a shear rate of 1 * 10 ³ (sec ^-1 ) at the molding temperature of the resin composition. It is 1.2-5. When the melt viscosity ratio exceeds 8, delamination occurs on the surface of the molded body, and when it is less than 0.5, the effect of the present invention cannot be obtained.

(Inorganic filler) As the inorganic filler,
Average diameter 5 μm or less, preferably 2 μm or less, length 1 to
500 μm or less, Mohs hardness of 3 or more, preferably 3
~ 7 ceramic whisker or average particle size 10μ
An inorganic powder having a Mohs hardness of 3 or more and a Mohs hardness of 3 or more, preferably 3 to 7, can be used. When the Mohs hardness of the inorganic filler is less than 3, slidability decreases.

The ceramic whiskers include potassium titanate whiskers, alumina boron whiskers, silicon nitride,
Glass beads, silica, stainless powder, and tungsten powder can be used. Among these, potassium titanate whiskers and alumina boron whiskers are preferable because of their small friction coefficient.

As the ceramic whiskers, those having an average diameter of 5 μm or less, preferably 2 μm or less and a length of 500 μm or less are used. As the inorganic powder, a powder having an average particle size of 50 μm or less, preferably 10 μm or less is used. When the amount exceeds the above range, the contribution of the inorganic filler to the surface of the molded body becomes small, the coefficient of friction increases, and the magnetic tape is greatly damaged.

The content of the inorganic filler is 1.5 to 30% by volume, preferably 5 to 20% by volume. If the amount is less than 1.5% by volume, the effect of the invention cannot be obtained. descend. The compounding ratio of the inorganic filler and the carbon material (carbon material: inorganic filler) is 1: 1 to 1:10, preferably 2: 1 to 10: 1. Outside this range, the coefficient of friction with the magnetic tape increases. , Satisfactory sliding characteristics cannot be obtained.

In the present invention, various surface modifiers may be used for the carbon material, carbon fiber and inorganic filler to enhance the affinity with the thermoplastic resin and polyethylene. Such surface modifiers include silane coupling agents, titanium coupling agents, higher fatty acids such as stearic acid and oleic acid, higher fatty acid glycerin esters, amides, higher fatty acid metal salts, higher alcohols, various waxes, polar polyolefins. (Maleic anhydride modified polyolefin, oxidized polyolefin, etc.) and the like can be used.

Among these, as the silane coupling agent,
For example, vinyltrimethoxysilane, vinyltris (2-
Methoxyethoxy) silane, N- (2-aminoethyl)
-3-Aminopropylmethyldimethoxysilane, N-
(2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-
(3,4-Epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloro Propylmethyldichlorosilane, 3-chloropropylmethyldiethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, hexamethyldisilazane-3-anilinopropyltrimethoxysilane, methyltrichlorosilane, dimethyldi Examples thereof include chlorosilane and trimethylchlorosilane.

Similarly, as the titanium coupling agent,
Examples thereof include isopropyl triisostearoyl titanate, isopropyl trioctanoyl titanate, and isopropyl dimethacryl isostearoyl titanate.

(Additional component) The resin composition of the present invention may further contain other additional components within a range that does not significantly impair the effects of the present invention. Examples of the additional component include a fluororesin, an antioxidant, a weather resistance improver, a nucleating agent, a flame retardant, various colorants and dispersants thereof. As the fluororesin, polytetrafluoroethylene (PTFE),
Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF) and the like can be used.

(Molding of Resin Composition) The resin composition according to the present invention can be produced by using an ordinary kneading machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, a Brabender, and a kneader. it can. Usually, each component is kneaded with an extruder or the like to form a pellet, and then processed into a pellet, but it is also possible to directly feed each component to a molding machine and knead the composition with the molding machine for molding. It is also possible to knead components other than the thermoplastic resin in a high concentration in advance to form a masterbatch, which is then compounded while being diluted with other components or directly molded. The resin composition of the present invention can be molded by a molding machine normally used for thermoplastic resins, but injection molding is preferable not only in terms of productivity but also in terms of sliding characteristics.

[0025]

EXAMPLES The present invention will be further described with reference to examples. The friction coefficient, magnetic tape slidability, melt viscosity, and Shore hardness in Examples and Comparative Examples were measured by the following methods.

(Frictional Coefficient and Sliding Property Against Magnetic Tape) A sample 1 having the shape shown in FIG. 1 is molded. This sample 1 is used as a power cylinder 2 of the evaluation device shown in FIG.
Attach it to the tip of at an angle of 45 degrees. Power cylinder 2
The load cell 3 is provided on the upper part of the magnetic tape 4 (VHS-C tape manufactured by TDK Corp.).
One end of the HGC30) is fixed. Magnetic tape 4
A 20 g weight 5 is attached to the other end of the magnetic tape 4 and the magnetic tape 4 is pressed against the sample 1. In this state, the power cylinder 2 is reciprocated and the sample 1 and the magnetic tape 4 are slid. From the state where the power cylinder 2 is most contracted (the state where the weight 5 is lowered) to the state where it is extended (the state where the weight 5 is raised), the load cell 3
The load applied to the end of the magnetic tape 4 fixed to was measured with the load cell 3 to obtain the coefficient of friction. The reciprocating speed of the sample (power cylinder) was 31 mm / sec, and the one-way distance of the power cylinder was 90 mm.

After measuring the load, the sliding surface (length 90 mm) of the magnetic tape was observed with the naked eye, and the degree of damage was ranked as follows. a No damage is noted b Within 5 short scratches c Within 10 scratches including long scratches and long scratches (continuous scratches on the entire sliding surface) Damage over dc

(Shore hardness) 2 to 5 parts by weight of polyethylene fine particles was added as a binder to 100 parts by weight of carbon powder to be measured, and the mixture was molded using a press molding machine under the conditions of 8 tons and 30 minutes. After shaping, it was heated at 120 ° C. for 30 minutes to obtain a carbon molded body. Shore hardness is JIS B-772
7, measured in accordance with Z-2246.

(Melt viscosity) Using a capillary rheometer manufactured by Intesco Co., Ltd., a capillary length of 10 m
The viscosity at a shear rate of 10 ³ sec ^-1 was measured under a molding condition of m and a diameter of 0.5 mm.

Examples 1 to 6 and Comparative Examples 1 to 9 These examples and comparative examples correspond to the resin composition according to claim 1. The following components were mixed in the ratios shown in Table 1 and Table 2 and kneaded with a twin-screw kneading extruder to obtain pellets. next,
Samples were molded and evaluated using a screw in-line injection molding machine. The results are shown in Tables 1 and 2.

Polyphenylene sulfide Toprene Co., Ltd. "Toprene T-4" Polycarbonate Mitsubishi Gas Chemical Co., Ltd. "Upilon S-200"
0 "Polyacetal BASF" Ultraform N2320 "Polyetherimide GE" Ultem 1000 "

Carbon material A Petroleum-based pitch is calcined at 1500 ° C., then crushed and classified. Average particle size 13 μm, Shore hardness 105. Carbon material B Petroleum-based pitch is fired at 1500 ° C., then crushed and classified. Average particle size 160 μm, Shore hardness 105.

Carbon Material C Phenolic resin fired carbon material. "Belle Pearl C-800" manufactured by Kanebo Ltd. Average particle size 20 μm, Shore hardness 110. Carbon material D Mesophase pitch fired carbon material. "MCMB-28" manufactured by Osaka Gas Co., Ltd. Average particle size 20 μm, Shore hardness 70.

Carbon Material E Natural graphite. "CP.B" manufactured by Nippon Graphite Co., Ltd. Average particle size 10 μm, Shore hardness 40. Glass fiber (treated with silane coupling) Average diameter 10 μm, fiber length 3 mm. As is clear from Table 1, the resin composition according to claim 1 has improved sliding characteristics.

(Examples 7 to 10 and Comparative Examples 10 to 13) These examples and comparative examples correspond to the resin composition according to claim 2. The following components were mixed in the proportions shown in Tables 3 and 4 and kneaded with a twin-screw kneading extruder to obtain pellets.
Next, the sample was molded and evaluated using a screw in-line injection molding machine. The results are shown in Tables 3 and 4. The melt viscosity of the thermoplastic resin and polyethylene is 10 at a shear rate at a composition molding temperature (300 ° C).
It is a value at ³ (sec ^-1 ).

"Toprene T-4" manufactured by Polyphenylene Sulfide Toprene Co., Ltd. Melt viscosity 8 * 10 ² P. Polycarbonate Mitsubishi Gas Chemical Co., Ltd. Iupilon S-200
0 ”. Melt viscosity 2 * 10 ³ P.

Carbon material A Petroleum-based pitch is calcined at 1500 ° C., then pulverized and classified. Average particle size 13 μm, Shore hardness 105. Carbon material a PAN-based carbon fiber (silane coupling treated). Average diameter 7 μm, fiber length 6 mm. Tensile modulus 235GP
a. Carbon material b PAN-based carbon fiber (silane coupling treated). Average diameter 7 μm, fiber length 6 mm. Tensile modulus 345GP
a.

Polyethylene a Dia Polymer Co., Ltd. "Mitsubishi Polyethylene JX-1"
0 ”. Density 0.95g / cm ³ , MFR 20g / 10mi
n. Melt viscosity 2 * 10 ² P. Polyethylene b Diapolymer Co., Ltd. "Mitsubishi Polyethylene BZ-8"
0 ”. Density 0.95g / cm ³ , MFR 0.03g / 10m
in. Melt viscosity 3 * 10 ³ P.

Polyethylene c Diapolymer Co., Ltd. “Mitsubishi Polyethylene JY-2”
0 ”. Density 0.95 g / cm ³ , MFR 9 g / 10 min. Melt viscosity 6 * 10 ² P.

As is clear from Tables 3 and 4, the composition shown in Examples 1 to 6 is mixed with polyethylene satisfying a specific condition with the thermoplastic resin to give the resin composition according to claim 1. Compared with this, the sliding characteristics are improved and it has excellent characteristics.

(Examples 11 to 13, Comparative Examples 14 to 18)
These examples and comparative examples correspond to the resin composition according to claim 3. The following components were mixed in the proportions shown in Table 5 and kneaded with a twin-screw kneading extruder to obtain pellets. next,
Samples were molded and evaluated using a screw in-line injection molding machine. The results are shown in Table 5. The thermoplastic resin and materials used in Examples and Comparative Examples are as follows.

Polycarbonate "Upilon S-200" manufactured by Mitsubishi Gas Chemical Co., Inc.
0 ”. Carbon material b PAN-based carbon fiber (silane coupling treated). Average diameter 7 μm, fiber length 6 mm. Tensile modulus 345GP
a.

Inorganic filler A Potassium titanate (treated with silane coupling). Fiber diameter 1 μm, fiber length 30 μm. Mohs hardness 4. Inorganic filler B Alumina boron whisker (silane coupling treated). Fiber diameter 1 μm, fiber length 30 μm. Mohs hardness 6.

Inorganic filler C Sintered alumina powder. Average particle size 10 μm, Mohs hardness 9 Inorganic filler D Talc. Average particle size 6.5 μm, Mohs hardness 2.

As is clear from Table 5, the composition of Examples 1 to 6 is mixed with an inorganic filler satisfying a specific condition in a specific amount determined by the amount of the carbon material.
Compared with the resin composition described, it has improved sliding characteristics and excellent characteristics.

[0046]

As described above, according to the present invention,
By blending a specific carbon material with a thermoplastic resin,
A resin composition satisfying the sliding characteristics with respect to the magnetic tape can be obtained.
Further, according to the present invention, by adding polyethylene having a specific relationship with the thermoplastic resin to the resin composition obtained by mixing the thermoplastic resin with the specific carbon material, a resin composition having further excellent sliding properties Can be obtained. Similarly, a resin composition in which a specific carbon material is blended with a thermoplastic resin is mixed with an inorganic filler satisfying specific conditions in a specific amount determined based on the carbon material, thereby having more excellent sliding properties. A resin composition is obtained. As a result, the magnetic tape sliding parts, which conventionally had to use metal parts, can be made of resin, and there is an effect that cost reduction, weight reduction, and size reduction can be realized.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

[Table 5]

[Brief description of drawings]

FIG. 1 is a diagram showing a sample shape for measuring a friction coefficient and a sliding characteristic with respect to a magnetic tape.

FIG. 2 is a diagram showing an apparatus for measuring a friction coefficient and a magnetic tape sliding characteristic.

[Explanation of symbols] 1 sample 2 power cylinder 3 load cell 4 magnetic tape 5 weight

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Yamazaki 8-3-1 Chuo, Ami-cho, Inashiki-gun, Ibaraki Mitsubishi Petrochemical Co., Ltd. Tsukuba Research Institute

Claims (3)

[Claims] 1. A resin composition comprising the following components. Component A Thermoplastic resin 95 to 40% by volume Component B Carbon powder having an average particle size of 0.1 to 100 μm, and a carbon material having a Shore hardness of 50 or more in a molded block body, a carbon material of at least one kind 5 to 60 capacity% 2. A resin composition comprising the following components. Component A Thermoplastic resin 94.5 to 20% by volume Component B Carbon powder having an average particle size of 0.1 to 100 μm and composed of at least one kind of carbon material having a Shore hardness of 50 or more in a molding block and carbon fiber Carbon material to be used 5 to 60% by volume Component C Polyethylene 0.5 to 40% by volume However, the melt viscosity ratio (A / C) of the component A and the component C is the shear rate (1 × 10 ³ ) at the molding temperature of the composition. sec ⁻¹ ), 0.5 to 8. 3. A resin composition comprising the following components. Component A Thermoplastic resin 83.5-
20% by volume Component B Carbon powder having an average particle size of 0.1 to 100 μm, a carbon material having a Shore hardness of 50 or more of a molding block, and a carbon material composed of at least one kind of carbon fibers 15 to 60% by volume Ingredient C Inorganic filler consisting of at least one of ceramic whiskers having a Mohs hardness of 3 or more and inorganic powders
1.5 to 30% by volume However, the compounding ratio of component B and component C B: C = 1: 1 to 1
Set to 0: 1.