JPH05255520A - Production of sliding member - Google Patents

Abstract

PURPOSE:To obtain the title member free from accumulation of frictional heat by incorporating a specified amount of a specified mixture of a PE and a conductive carbon black into an engineering thermoplastic and melt molding the obtained mixture. CONSTITUTION:40-90 pts.wt. PE having a density of 0.92g/cm<3> or higher and a melt index of 0.1-30g/10min is melt compounded with 10-40 pts.wt. conductive carbon black and at most 20 pts.wt. arbitrary talc to give a mixture having a melt index of 0.1-40g/10min. 3-150 pts.wt. of this mixture and 100 pts.wt. engineering thermoplastic (e.g. polycarbonate) and mixed and melt molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a sliding member, and particularly to dimensional accuracy, sliding characteristics, mechanical characteristics and precision molding required for sliding members in the field of precision electronic parts such as information and video equipment. The present invention relates to a method for manufacturing a sliding member having excellent properties and the like.

[0002]

2. Description of the Related Art Precision electronic parts such as information and video equipment have been rapidly reduced in weight, thinned and used in various specifications. For example, main parts in driving devices such as copying machines, printers and video-related equipment are Since high precision and tough mechanical properties and high sliding properties are required, aluminum alloys have been conventionally used as the material for such components.

[0003]

However, aluminum alloys are disadvantageous in that they are heavy and require various secondary processing, so that they are inferior in productivity and the manufacturing cost of parts is high.

For this reason, attempts have been made to use a thermoplastic resin, which is light in weight, excellent in productivity and inexpensive, as a component material in the market.

However, in the composite material obtained by improving the conventional thermoplastic resin, various required characteristics as described above, that is,
It is not possible to satisfy high precision and tough mechanical properties and high sliding properties. In particular, it replaces conventional metal parts in terms of the amount of wear between the base material and the mating material, the coefficient of friction, and the change over time. Was not always enough.

It is an object of the present invention to provide a method for manufacturing a sliding member that solves the above problems.

[0007]

Means for Solving the Problems The present inventors have achieved the above object by preparing a melt-kneaded product containing carbon black in advance, blending the melt-kneaded product with thermoplastic engineering plastics, and performing melt-molding. Is.

That is, according to the present invention, 40 to 90 parts by weight of polyethylene having a density of 0.92 g / cm ³ or more and a melt index of 0.1 to ³⁰ g / 10 minutes, 10 to 40 parts by weight of conductive carbon black and 0 to 20 parts by weight of talc are used. Parts are melt-kneaded to form a mixture having a melt index of 0.1 to 40 g / 10 min, and then 3 to 150 parts by weight of this mixture is blended with 100 parts by weight of thermoplastic engineering plastics and melt-molded. It is a manufacturing method of a sliding member.

(Polyethylene) The polyethylene used in the present invention has a density of 0.92 g / cm ³ or more and a melt index (MI) of 0.1 to 30 g / 10 minutes, preferably a density of 0.945.
MI is a polyethylene of 5 to 20 g / 10 min at ~0.98g / cm ^3.

If the density of polyethylene is too low, the affinity with carbon black deteriorates, the carbon black aggregates, and the impact strength decreases. Upper limit of density is 0.98g / cm ³
It is a degree.

Further, when the MI is out of the above range, the carbon black is not uniformly dispersed, and the mechanical strength of the molded product is lowered.

The polyethylene used in the present invention may be a homopolymer of ethylene or a copolymer containing 15% by weight or less of a vinyl monomer copolymerizable with ethylene.

(Conductive carbon black) The conductive carbon black used in the present invention may be a thermal black or a channel black, which has a low conductivity but gives a sufficient conductivity by using a large amount. However, since it is desirable to be able to impart the necessary conductivity to the composition with a small amount of addition, highly conductive acetylene black and oil furnace black, especially oil furnace black has few impurities, and also has excellent conductivity. Therefore, it is preferable.

Among them, especially XCF (Extra Conductive Bl
ack), SCF (Super Conductive Furnace Black), CF (Con
ductive Furnace Black) and SAF (Super Abrasion Furn)
aceBlack) is suitable for use, among them BET by N ₂ adsorption
It is preferable that the specific surface area is 850 m ² / g or more, particularly 900 m ² / g or more.

XCF is "Ketjen Black EC" (trade name) of Ketjen Black International,
SCF, such as Cabot's "Vulcan XC-72" (trade name)
As a "Vulcan SC" (trade name) of Cabot Corporation,
"Vulcan P" (trade name) and Degussa "Corlux"
CF such as "L" (trade name) as CF, "Vulcan C" (trade name) from Cabot, and "Conductex" from Colombia
"SC" (trade name), etc., and as SAF, "Asahi # 9" (trade name) of Asahi Carbon Co., "Dia Black A" (trade name) of Mitsubishi Kasei Co., Ltd., "Vulcan 9" of Cabot Corporation.
(Trade name) etc. You may use these together.

Generally, when nylon, polyacetal, polycarbonate, etc. are blended with polyethylene, delamination (delamination phenomenon) easily occurs due to lack of compatibility, but a highly conductive oil furnace has a rich surface area with a graphite structure. The special graphite structure on the surface of carbon black exhibits a specific affinity with the crystal structure of polyethylene and is extremely well compatible with each other, does not cause delamination, and has a unique compatibility structure showing high conductivity. As a result, the effects of the present invention can be exhibited remarkably.

(Talc) The talc used in the present invention is
Suitably the average particle size is 0.2-50 μm, preferably 0.2-20
of μm. Talc in this range is particularly suitable for impact strength and dispersibility of carbon black.

Here, the average particle diameter is measured by a liquid phase sedimentation type light transmission method, and examples of the measuring apparatus include SA-CP type manufactured by Shimadzu Corporation or SKN type manufactured by Seishin Enterprise. The same measuring device is used for the particle size distribution.

The specific surface area is measured by a conventional method, a so-called air permeation method, using a constant pressure ventilation type specific surface area determination device, for example, SS-100 type powder specific surface area measuring device manufactured by Shimadzu Corporation.

(Thermoplastic Engineering Plastics) The thermoplastic engineering plastics used in the present invention are not particularly limited as long as they are generally used for injection molding, and examples thereof include polyamide, polyester, polyacetal, polycarbonate, Polyether sulfone, polyphenylene oxide, polyphenylene sulfite, polyether ether ketone,
Examples thereof include AS resin, ABS resin, polyarylate, polyetherimide, and polyether sulfone.
Of these, polyamide, polyester, polyacetal, polycarbonate, and polyphenylene sulphite are particularly preferable.

In addition to the above composition, the sliding member of the present invention further comprises 5 to 150 parts by weight of at least one fiber selected from the following (a) to (c): By blending in parts by weight,
The mechanical strength and dimensional accuracy of the obtained sliding member can be improved.

(A) Average diameter 3 to 20 μm, and average length 0.
03-15mm carbon fiber (b) Average diameter 3-15μm, and average length 0.05-10mm glass fiber (c) Average diameter 0.1-1μm, and average length 5-120μm
Potassium titanate fiber

(Carbon Fiber) As the above-mentioned carbon fiber used in the present invention, a general chopped carbon fiber is used, but when high mechanical properties and dimensional properties such as those of the composition of the present invention are required, , PAN (polyacrylonitrile) method is preferable.

The average diameter of the carbon fibers used is 3-20 μ
m, preferably 3-10 μm, with an average length of 0.03-60 m
m, preferably 0.5 to 30 mm. If it is out of this range, the mechanical strength and dimensional accuracy of the resin composition are deteriorated, which is not preferable.

The carbon composition is preferably 95% or more. By using such a carbon fiber, for example, in the molded product after being subjected to injection molding, the average length is slightly shortened, and it is dispersed with 0.03 to 15 mm, preferably 0.03 to 5 mm of carbon fiber, A good balance of performance between physical properties and dimensional properties is achieved.

The carbon fiber may contain a surface treatment component for the purpose of adhesion and affinity with the thermoplastic engineering plastics, and the adhesion amount thereof is generally about 2 to 8% by weight. Is.

(Glass Fiber) The glass fiber used in the present invention may have an average diameter of 3 to 15 μm, preferably 5 to 12 μm, and an average length of 0.05 to 10 mm, preferably
It is 0.1 to 6 mm. If the average diameter is out of this range, sufficient mechanical strength of the resin composition cannot be obtained,
If the average length is out of this range, sufficient dimensional accuracy cannot be obtained.

By using such glass fiber, for example, in a molded body after being subjected to injection molding,
Although its fiber length is somewhat shortened, it is dispersed in glass fibers having an average length of 0.05 to 10 mm, which is effective in terms of dimensional accuracy, mechanical strength and high sliding properties.

The glass fiber may contain a surface treatment component for the purpose of adhesion and affinity with thermoplastic engineering plastics, and the amount of adhesion is 0.01 to 0.6.
The thing of about weight% is common.

These glass fibers can be appropriately selected from commercial products, but when they are manufactured, they are marbled (glass beads of a predetermined size) in, for example, a pushing (spinning furnace).
Is softened by heat and allowed to flow down from a large number of nozzles of the furnace table. While stretching this base material at a high speed, the sizing agent is applied by dipping the sizing agent in a sizing agent application device to bundle the sizing agent, which is then dried and wound on a rotary drum. Manufactured by the take method. At this time, the average diameter of the glass fibers is determined by selecting the size of the nozzle diameter and the stretching conditions.

The form of the glass fiber may be any of roving, chopped strand, strand and the like, and so-called milled fiber, crushed product of so-called glass powder may be used, but chopped strand is preferable in view of workability with resin. .. The composition of the raw glass is preferably alkali-free, and E-glass is one example.

(Potassium Titanate Fiber) The potassium titanate fiber used in the present invention has an average fiber length of 5 to 120 μm,
The average fiber length is preferably 20 to 100 μm and 0.1 to 3.0 μm.
It is a fine white needle-like single crystal fiber of m, preferably 0.4 to 1.5 μm. Outside of this range, the mechanical strength and dimensional accuracy of the resin composition cannot be satisfactorily obtained.

The potassium titanate fiber can be subjected to a known surface treatment in order to enhance the adhesiveness. Specifically, it is an aminosilane-based, epoxysilane-based, or titanate-based surface treatment agent. Aminosilane type is particularly preferable.

(Blending Amount) In the present invention, the blending ratio of each of the above essential components is as follows. Polyethylene: 40 to 90 parts by weight, preferably 50 to 80 parts by weight, carbon black: 10 to 40 parts by weight, preferably 15 to 35 parts by weight, talc: 0 to 20 parts by weight, preferably 5 to 15 parts by weight, heat Plastic engineering plastics: 100 parts by weight.

When carbon fiber, glass fiber or potassium titanate is compounded, one or a combination thereof: 5-150 parts by weight, preferably 20-150 parts by weight.

If the blending amount of each of the above-mentioned components is out of this range, the following problems occur and the sliding members for precision electronic parts cannot be applied.

That is, if the blending amount of polyethylene is too low, the friction coefficient becomes large, and if it is too high, the phase separation from the thermoplastic engineering plastics becomes large, the delamination phenomenon occurs, and the mechanical strength decreases.

If the blending amount of carbon black is too low, the conductivity is lowered, and the thermal energy generated at the time of friction with the mating base material during sliding is accumulated, and the heat generation accelerates the abrasion of the self-base material or the mating base material. To be done. If it is too high, the mechanical strength of the resin composition will decrease.

If the blending amount of talc is too low, the dispersion of the conductive carbon black is particularly poor and the mechanical strength is lowered. If it is too high, the resin composition becomes brittle.

When the amount of the reinforcing filler of carbon fiber, glass fiber and potassium titanate is too low, the effect of improving the dimensional accuracy and mechanical strength is not expected, and when the amount is too high, the moldability deteriorates. Poor dispersion of the reinforcing filler occurs and impact strength and appearance deteriorate.

(Additional Component) In the production of the sliding member of the present invention, an additional component may be added in addition to these essential components as long as the effects of the invention are not significantly impaired.

Examples of such an additional component include various fillers other than the components used in the present invention, such as calcium carbonate (heavy, light and colloidal), mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, Barium sulfide, zinc oxide, zeolite, wollastonite,
Diatomaceous earth, glass beads, bentonite, montmorillonite, asbestos, hollow glass spheres, graphite, molybdenum disulfide, titanium oxide, aluminum fiber, stainless steel fiber, brass fiber, aluminum powder, wood powder, fir shell, etc. Thermoplastic resins such as polypropylene, polyethylene (high density, medium density, low density, linear low density), propylene / ethylene-block or random copolymers, maleic anhydride modified polyolefin, etc., rubber or latex components, such as Ethylene / propylene copolymer rubber, styrene / butadiene rubber, styrene / butadiene / styrene-block copolymer or hydrogenated derivative thereof, polybutadiene, polyisobutylene, etc., thermosetting resin such as poxy resin, melamine resin,
In addition to phenolic resins, unsaturated polyester resins, etc., antioxidants (phenolic, sulfurous, etc.), lubricants, various organic or inorganic pigments, ultraviolet absorbers, antistatic agents, dispersants, neutralizing agents, foaming agents , Plasticizers, copper damage inhibitors, flame retardants, cross-linking agents, flow improvers, and the like.

The addition of these additional components has respective effects, that is, physical property balance and surface properties of the molded product (surface scratch resistance, gloss, weld appearance, silver streak, flow mark, etc.), printability, paintability, adhesion. It is effective in improving the heat resistance, plating property, molding processability, durability, etc.

(Production Method of the Present Invention) The composition of the present invention can be produced by using a conventional kneading machine such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, a Brabender blast graph and a kneader. ..

In producing the composition of the present invention, first, a composition comprising polyethylene, conductive carbon black and talc is applied to a single screw extruder, a twin screw extruder, a Banbury mixer, a roll, a Brabender blast graph, a kneader and the like. A kneaded product is prepared by using an ordinary kneading machine, and then a predetermined amount is mixed with thermoplastic engineering plastics in combination with various reinforcing fibers, if desired, and kneaded again by using the kneading machine described above to form pellets. After that, the target sliding member is molded.

[0046]

In general, when carbon black is kneaded with a polymer, molecular breakage of the polymer occurs due to impurities of carbon black, and the molecular breakage increases due to the shear rate during kneading, resulting in a decrease in the molecular weight of the polymer and its impact strength. Lower. This tendency is noticeable in polyacetal. Therefore, it is effective to disperse carbon black in polyethylene before blending it with engineering plastics.

The dispersion structure of carbon black has a great influence on the sliding characteristics of the composition, and if it is dispersed in polyethylene beforehand, a uniform dispersion can be obtained and the sliding characteristics can be improved.

When not directly in the form of a masterbatch in which carbon black is preliminarily kneaded, but when the engineering plastics are directly kneaded, that is, the composition components of the present invention are all kneaded at the same time, the dispersion structure of carbon black becomes non-uniform,
Along with the decrease in strength, the amount of wear and the coefficient of friction increase.

[0049]

The present invention will be described below with reference to examples.

(Carbon masterbatch A-1)
70 parts by weight of polyethylene with a melt index (MI) of 4 g / 10 min at 0.92 g / cm ³ , 20 parts by weight of oil furnace carbon black (trade name Ketjen Black Black EC) and 10 parts by weight of talc with an average particle size of 10 μm The mixture was kneaded into pellets by a twin-screw extruder to obtain pellets of kneaded material having MI of 0.4 g / 10 min. This is hereinafter referred to as Carbon Masterbatch A-1.

(Carbon masterbatch A-2)
70 parts by weight of polyethylene at 0.97 g / cm ³ and MI of 8 g / 10 min, 20 parts by weight of Ketjenbu black EC and 10 parts by weight of talc with an average particle size of 10 μm were kneaded and pelletized by a twin-screw extruder.
Was a kneaded product pellet of 1.2 g / 10 min. Hereafter, this is designated as carbon masterbatch A-2.

(Carbon masterbatch A-3)
70 parts by weight of polyethylene at 0.97 g / cm ³ and MI of 8 g / 10 min, 20 parts by weight of acetylene black (trade name Denka Black) and 10 parts by weight of talc with an average particle size of 10 μm are kneaded into pellets by kneading. , MI was a pellet of kneaded material of 26 g / 10 min. Hereafter, this is designated as carbon masterbatch A-3.

Examples 1 to 16 These carbon masterbatches and P having an average particle size of 3.0 mm were used.
Carbon fiber made by AN method, average diameter 10 μm and average length
3.0 mm glass fiber, average diameter 0.8 μm, average length 60 μm
Polycarbonate, polyphenylene sulphite and polyamide as thermoplastic engineering plastics are blended with each of the potassium titanates in the proportions shown in Tables 1 to 3 and melt-kneaded with a twin-screw extruder to form pellets, which are then screw-in-line type. Test pieces were prepared using an injection molding machine and various physical properties were evaluated. The evaluation results are shown in Tables 1 to 3.
Shown in.

Comparative Examples 1 to 14 The compositions shown in Tables 1 and 2 were mixed, melt-kneaded with a twin-screw extruder and pelletized, and evaluated in the same manner as in Examples. The evaluation results are shown in Tables 1 to 3. The polyethylene used in the simultaneous kneading without using the masterbatch is the same as that used in the masterbatch.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

[Table 3]

The test method for evaluation is as follows:
As the practical performance required for sliding members of precision electronic parts, in the following test methods, the wear amount is 8 mg or less, the Izod impact strength is 5 kg.cm/cm or more, and the linear expansion coefficient is 4.0 × 10.
^-5 / ℃ or less.

(1) Amount of wear and friction coefficient tester: Tokyo Test Machine Co., Ltd., Ito type instrumentation wear tester IA
T-40 / 1500-01 Test piece: Injection molded product, thickness 2mm, length 30mm, width 30mm Counterpart material: SUS45C, φ20, width 2.8mm, ring shape, test effective diameter d = 22.8mm Test method: test piece With the above fixed, the SUS45C ring rotates in one direction on the test piece. Measurement conditions: Load 8kg / cm ² (only polyamide type 14kg / c
m ² ), rotation speed 180 rpm, test time 5 hr. Calculation of wear amount: weight before test-weight after test = wear amount (m
g) Calculation of friction coefficient: Torque T (kg ・ mm) from measurement chart
Calculate and calculate from the load and test effective diameter d by the following formula. Friction coefficient μ = (1 / load) × T × (d / 2)

(2) Flexural Modulus According to ASTM D790

(3) Izod impact strength According to ASTM D256.

(4) Mettle index of carbon masterbatch Test method: JIS-K7210, measurement temperature: 230 ° C, load: 8.55k
g.

(5) Dimensional accuracy The coefficient of linear expansion was used as a measure of dimensional accuracy. Measurement method: ASTM D696, heating rate: 2 ° C / min, temperature range:
23 to 100 ° C, measuring instrument: manufactured by Vacuum Riko Co., Ltd.

Use Example 1 The composition of Example 5 was kneaded by a twin-screw extruder into pellets, and the obtained pellets were molded into a gear for a copying machine using a screw in-line injection molding machine. When this gear was put to practical use, no wear or breakage of the tooth surface was observed even after 400 days.

Use Example 2 The composition of Example 14 was used to knead into pellets by a twin-screw extruder, and the obtained pellets were molded into a printer gear using a screw in-line injection molding machine. When this gear was put into practical use, no wear or breakage of the tooth surface was observed even after 300 days.

[0066]

According to the production method of the present invention, since most or substantially all of the carbon black is contained in polyethylene to form a fine dispersed structure, the polyethylene phase has thermal conductivity. As a result, the accumulation of thermal energy generated by friction with the mating base material during sliding was less likely to occur, and a reduction in the amount of wear was confirmed.

On the other hand, even if the composition is the same, in the conventional method of simultaneously mixing and kneading the compositions, the thermal conductivity is insufficient due to the difference in the carbon black dispersion structure, and the amount of wear due to the accumulation of frictional heat large.

According to the present invention, thermoplastic engineering plastics, which generally have poor sliding properties, are used as the base material, and high sliding properties can be exhibited, high sliding properties, high dimensional accuracy, and a tough machine. The characteristics can be satisfied at the same time. As a result, it has become possible to adapt to metal parts that could not be handled in the past, such as high-precision gears for copiers, printers, etc., high-precision and high-strength gears for video camera mechanical decks, and sliding parts with magnetic tape. It has become possible to put it into practical use as an advanced precision electronic component.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location C08L 23:04 (72) Inventor Seiichi Ikeda 1 Tohocho, Yokkaichi-shi, Mie Mitsubishi Petrochemical Co., Ltd. Company Yokkaichi Office

Claims (2)

[Claims] 1. Melt-kneading 40 to 90 parts by weight of polyethylene having a density of 0.92 g / cm ³ or more and a melt index of 0.1 to ³⁰ g / 10 min, 10 to 40 parts by weight of conductive carbon black and 0 to 20 parts by weight of talc. To obtain a mixture having a melt index of 0.1 to 40 g / 10 min, and then 3 to 150 parts by weight of this mixture is mixed with 100 parts by weight of thermoplastic engineering plastics and melt-molded. Production method. 2. Melt-kneading 40 to 90 parts by weight of polyethylene having a density of 0.92 g / cm ³ or more and a melt index of 0.1 to ³⁰ g / 10 minutes, 10 to 40 parts by weight of conductive carbon black and 0 to 20 parts by weight of talc. To obtain a mixture having a melt index of 0.1 to 40 g / 10 minutes, and then 3 to 150 parts by weight of this mixture and 5 to 150 parts by weight of at least one fiber selected from the following (a) to (c) are thermoplastic. A method for producing a sliding member, which comprises blending 100 parts by weight of engineering plastics and melt-molding. (A) Carbon fibers having an average diameter of 3 to 20 μm and an average length of 0.03 to 15 mm (b) Glass fibers having an average diameter of 3 to 15 μm and an average length of 0.05 to 10 mm (c) Average diameter of 0.1 to 1 μm and an average length of 5 to 120 μm Potassium titanate fiber