JPH01161035A - Polyolefin bearing - Google Patents

Abstract

PURPOSE:To obtain a bearing having excellent wear resistance, heat resistance and abrasion resistance and keeping shafts of a small precision instrument, an automobile, etc., in good state without feeding a lubricant or impregnating with oil, by injection-molding a compsn. consisting of an ultrahigh-MW polyolefin and a low-MW-high-MW polyolefin. CONSTITUTION:The subject bearing is obtd. by injection-molding a polyolefin compsn. consisting of an ultrahigh-MW polyolefin (A) having an intrinsic viscosity of 10-40dl/g measured in decalin solvent at 135 deg.C and a low-MW-high-MW polyolefin having an intrinsic viscosity of 0.1-5dl/g measured in decalin solvent at 135 deg.C, wherein the amt. of the component A is in the range of 15-40wt.% based on the total wt. of both component A and B, and which contains at least a polyolefin having an intrinsic viscosity [eta]c of 3.5-15d$/g measured in decalin solvent at 135 deg.C and a dissolution torque T of 4.5kg.cm or lower. Since this process makes it possible to easily obtain the bearing by injection molding without spoiling excellent mechanical properties that the component A essentially has and without causing delamination, it is possible to obtain with relatively low cost a bearing having excellent wear resistance, heat resistance, impact resistance and abrasion characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bearing with excellent wear resistance, heat resistance, and slidability, and more particularly, to a bearing for use in small precision equipment such as video tape recorders (VTRs). The present invention relates to a polyolefin bearing that allows shafts used in equipment, automobiles, and other general equipment to slide smoothly without being supplied with lubricant or the like or impregnated with oil.

The shaft of the mouth can be freely rotated or reciprocated (generally referred to as "slidable").
Conventionally, as a bearing for holding the bearing in place, a bearing body made of a metal such as aluminum or stainless steel and the sliding portion thereof coated with a bearing material such as a soft penetrating metal is known. However, metal bearings are heavy and especially
TR, video camera, office automation (OA)
＞Precision equipment such as equipment, conveyors, automobiles, health equipment,
Alternatively, when these metal bearings are used in toys and other general equipment, the weight of the entire equipment increases, which is not desirable. Further, in the case of such metal bearings, the cutting process at the time of manufacture thereof is complicated, and there is a possibility that the manufacturing cost may increase.

In order to eliminate the disadvantages of such metal bearings,
Recently, such bearings have been made of plastic. Possible plastics constituting such a bearing include engineering plastics such as polyacetal resin, polyimide resin, and polycarbonate resin.

However, such engineering plastics such as polyacetal resins and polyimide resins have problems in that they are expensive, inferior in economic efficiency, and have insufficient sliding properties. Therefore, in practice, bearings made of relatively inexpensive nylon 12 or polyester rubber coated with molybdenum to improve sliding properties to some extent have been widely used in precision equipment such as VTRs and other equipment.

However, such bearings made of polyester rubber coated with molybdenum still have insufficient wear resistance, heat resistance, and sliding properties, resulting in wear and tear on the sliding parts of the bearings, and sliding problems. There is a possibility that sliding performance between the bearing and the shaft slidably attached to the bearing deteriorates due to temperature rise due to frictional heat caused by the movement, which may cause noise generation.

In order to eliminate such inconveniences, it may be possible to mold bearings used in such precision instruments using ultra-high molecular weight polyolefin.

Ultra-high molecular weight polyolefins, such as ultra-high molecular weight polyethylene, have superior lightning resistance, heat resistance, abrasion resistance, sliding properties, chemical resistance, tensile strength, etc., compared to general-purpose polyolefins such as general-purpose polyethylene. It is conceivable that it could be used as a bearing in various types of equipment. However, ultra-high molecular weight polyethylene has an extremely high melt viscosity and poor fluidity compared to general-purpose polyethylene, so it is very difficult to mold it by ordinary extrusion molding or injection molding, and most of it is molded by compression molding. and
Currently, only a small portion is extruded into rod shapes at extremely low speeds.

If such ultra-high molecular weight polyethylene with poor melt flowability is molded into a bearing shape by normal injection molding, shear fracture flow will occur during the process of filling the resin into the mold cavity, causing the resulting molded product to deteriorate. This causes delamination in a mica-like manner, and not only is it impossible to obtain a molded product with the excellent properties of ultra-high molecular weight polyethylene, but the result is usually that the bearing is inferior to bearings molded from general-purpose polyethylene.

■Hadakuni Danshun The present invention has been made in view of these circumstances, and it does not impair the excellent mechanical properties originally possessed by ultra-high molecular weight polyolefins, and does not cause delamination. Bearings that can be injection molded, do not require molybdenum coating to improve sliding properties, do not require a separate supply of lubricant or impregnate oil, are relatively inexpensive, and are especially used in various general equipment. The purpose of the present invention is to provide a bearing that is suitable for various applications, has excellent wear resistance, heat resistance, impact resistance, or slidability, and has low noise.

In order to achieve this objective, the polyolefin bearing according to the present invention is made of an ultra-high molecular weight polyolefin having an intrinsic viscosity of 10 to 40 d, Q/g measured in a decalin solvent at 135°C. (i) The ultra-high molecular weight polyolefin is composed of the ultra-high molecular weight polyolefin and the above-mentioned low molecular weight polyolefin having an intrinsic viscosity of 0.1 to 56 N/g as measured in a decalin solvent. It is in the range of 15 to 40% by weight based on the total weight of the molecular weight or high molecular weight polyolefin, and (ii) the intrinsic viscosity measured in decalin solvent at 135°C [
η]c is 3.5~15d, l! /g, and (i
ii) It is characterized in that it is obtained by injection molding a polyolefin composition containing at least a polyolefin having a melting torque T of 4.5 kg-am or less.

According to the polyolefin bearing according to the present invention, the polyolefin composition can be injection molded without impairing the excellent mechanical properties inherent to ultra-high molecular weight polyolefin and without causing delamination. Since it is easy to obtain, it is possible to obtain a bearing with excellent wear resistance, heat resistance, impact resistance, and slidability at a relatively low cost.

Moreover, according to the present invention, the polyolefin bearing obtained by injection molding a polyolefin composition has sufficient sliding properties, so there is no need to coat the sliding part with molybdenum to improve sliding properties. At the same time, there is no need to supply lubricant or impregnate oil. Furthermore, since the polyolefin bearing according to the present invention has excellent wear resistance, heat resistance, impact resistance, and sliding properties, the bearing is less prone to wear and tear, and even when the temperature inside the device increases, etc. The sliding performance between the bearing and the shaft slidably attached to the bearing does not deteriorate, and noise can be suppressed to the utmost.

Le skin a and body plate ally The present invention will be specifically explained below.

The polyolefin bearing according to the present invention is, for example,
'I'I' (, video cameras, precision equipment such as office automation (OA) equipment, conveyors, health equipment,
Polyolefin (A) preferably used in automobiles, toys, other general equipment, etc., and shown at least as shown below.
It can be obtained by injection molding a polyolefin composition containing, for example, in a mold.

Bo1-Refin A The polyolefin (A>) used in the present invention consists of an ultra-high molecular weight polyolefin and a low-molecular weight to high-molecular weight polyolefin. explain.

135 of the ultra-high molecular weight polyolefin used in the present invention
The intrinsic viscosity [η] measured in °C decalin solvent is 10
-40dj/g, preferably 15-3.56ρ/g. If the intrinsic viscosity [η] is less than 10d or 117g, the mechanical properties of the bearing as an injection molded product tend to deteriorate, which is undesirable.On the other hand, if it exceeds 406ρ/g, the bearing as an injection molded product tends to deteriorate. This is undesirable because the appearance deteriorates, flow marks occur, and delamination occurs.

The intrinsic viscosity [η
] h is 0.1 to 56 N/g, preferably 0.5 to 3 d
, 1/g. This intrinsic viscosity [η]h is 0.
If it is less than 1 du/g, the molecular weight is too low and there is a risk of bleeding on the surface of the bearing as an injection molded product, which is undesirable. If it exceeds /g, the melt fluidity decreases, making it difficult to use a general-purpose polyethylene injection molding machine as is, which is not preferred.

The ultra-high molecular weight polyolefins and low molecular weight to high molecular weight polyolefins mentioned above include, for example, ethylene,
α of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 4-methyl-1-pentene, 3-methyl-1-pentene, etc.
- Consists of homopolymers or copolymers of olefins. Among these, ethylene homopolymers or copolymers of ethylene and other α-olefins, with ethylene as the main component, are desirable.

In the polyolefin constituting the bearing according to the present invention, the ultra-high molecular weight polyolefin and the low-molecular weight to high-molecular weight polyolefin are such that the ultra-high molecular weight polyolefin covers 15 to 40% by weight based on the total weight of both polyolefins. In other words,
The low molecular weight to high molecular weight polyolefins are present in a proportion of 85 to 60% by weight based on the total weight of both polyolefins. The ultra-high molecular weight polyolefin as described above has a weight of 20% based on the total weight of both polyolefins.
It is preferable that it is present in such a proportion that it accounts for 35% to 35%. The amount of ultra-high molecular weight polyolefin is 15% by weight
If it is less than 40% by weight, it is undesirable because the mechanical properties of the resulting injection molded bearing tend to be poor, while if it exceeds 40% by weight, delamination will occur in the resulting injection molded bearing. As a result, a molded article with good mechanical properties cannot be obtained, which is not preferable.

The polyolefin used in the present invention essentially consists of an ultra-high molecular weight polyolefin and a low to high molecular weight polyolefin, which are present in the above quantitative proportions.

Therefore, the polyolefin used in the present invention has 13
The intrinsic viscosity [η] measured in a decalin solvent at 5°C is 3.
5 to 15 (in the range of IQ/g, melting torque T (k
g Han) is below 4.5 kg-au. Note that the melting torque T is determined using a JSR-% Nilastometer (manufactured by Hitachi Kikai Kogyo KK) at a temperature of 240°C and a pressure of 5k.
g/co! , amplitude 3° frequency 6 CPH.

If the above [η] c is less than 3.5 dfl/g, the resulting bearing as an injection molded product may have poor mechanical strength, especially wear resistance, which is undesirable. On the other hand, [η] is less than 15 dfl/g. If it exceeds /g, delamination will occur in the bearing as an injection molded product, resulting in a decrease in mechanical strength such as wear resistance, which is not preferable.

Moreover, if the melting torque T exceeds 4.5 kg·mark, it is not preferable because it will not bite into a normal screw during molding and injection molding will not be possible with a general-purpose injection molding machine.

The polyolefin used in the present invention is preferably [η
]c is in the range of 4.0 to 10 dU/.

The polyolefin used in the present invention can also be prepared by blending an ultra-high molecular weight polyolefin and a low-molecular weight to high-molecular weight polyolefin in the above proportions, but according to the studies of the present inventors, a specific high-molecular weight polyolefin Polyolefins obtained by the following multi-step polymerization method in which olefins are polymerized in multiple steps in the presence of a catalyst formed from an active solid titanium catalyst component and an organoaluminum compound catalyst component have excellent properties. I found out.

Such a multi-step polymerization method is carried out in the presence of a Ziegler type catalyst formed from a highly active titanium catalyst component (a) containing magnesium, titanium and halogen as essential components and an organoaluminum compound catalyst component (b). It is carried out by multistage polymerization of olefins. That is, in at least one polymerization step, the intrinsic viscosity is 10 to 406ρ.
/g of an ultra-high molecular weight polyolefin, and in another polymerization step, the olefin is polymerized in the presence of hydrogen to produce a low to high molecular weight polyolefin with an intrinsic viscosity of 0.1 to 5 dΩ/g.

The particular Ziegler type catalyst used is essentially a catalyst of a particular nature formed from a solid titanium catalyst component and an organoaluminum compound catalyst component. As the solid titanium catalyst component, it is preferable to use, for example, a highly active fine powder catalyst component with a narrow particle size distribution, an average particle size of about 0.01 to 5 μm, and several microspheres fixed to each other. It is. A highly active finely powdered titanium catalyst component having such properties is obtained, for example, in the solid titanium catalyst component disclosed in JP-A No. 56-811, by bringing a liquid magnesium compound into contact with a liquid titanium compound. When precipitating a solid product, it can be manufactured by strictly adjusting the precipitation conditions. Specifically, in the method disclosed in JP-A-56-811, a hydrocarbon solution in which magnesium chloride and higher alcohol are dissolved and titanium tetrachloride are mixed at a low temperature, and then 50%
When precipitating a solid product by raising the temperature to about ~100°C, a trace amount of monocarboxylic acid ester of about 0.01 to 0.2 mole per mole of magnesium chloride is allowed to coexist and under strong stirring conditions. By performing the precipitation,
A highly active finely powdered titanium catalyst component can be prepared. Further, if necessary, it may be washed with titanium tetrachloride.

In this way, a solid catalyst component having excellent activity and particle state can be obtained. The catalytic component is
For example, it contains about 1 to about 6% titanium, the halogen/titanium (atomic ratio) is about 5 to about 90, and the magnesium/titanium (atomic ratio) is about 5 to about 90.
Titanium (atomic ratio) ranges from about 4 to about 50.

Further, the slurry of the solid titanium catalyst component prepared as described above is subjected to a high-speed shearing treatment, and the particle size distribution is narrow and the average particle size is 0.01 to 5 μm.
Microspheres, preferably in the range of 0.05 to 3 μm, are also suitably used as the highly active finely powdered titanium catalyst component. Specifically, a method for high-speed shearing treatment is, for example, a method in which a slurry of a solid titanium catalyst component is treated in an inert gas atmosphere using a commercially available homomixer for an appropriate period of time. In order to prevent deterioration of catalyst performance,
It is also possible to adopt a method in which titanium and a similar organoaluminum compound are added in advance. Furthermore, sieve the slurry after processing? It is also possible to adopt a method of filtering to remove coarse particles. By these methods, the highly active fine powdered titanium catalyst component having the fine particle size can be obtained.

The polyolefin used in the present invention is produced by using the highly active finely powdered titanium catalyst component (a) and the organoaluminum compound catalyst component (b) as described above, together with an electron donor if necessary, and by using pentane, hexane, etc. It can be produced by slurry polymerizing an olefin in a hydrocarbon medium such as , heptane, kerosene, etc., usually at a temperature in the range of 0 to 100° C., in a multi-stage polymerization process of at least two stages.

Examples of the organoaluminum compound catalyst component (b) include trialkylaluminum such as triethylaluminum and triisobutylaluminum, siaaluminum chloride such as diethylaluminum chloride and diisobutylaluminum chloride, and alkylaluminum sesquichloride such as ethylaluminum sesquichloride. or a mixture thereof is preferably used.

In the multistage polymerization process of the olefin, a multistage polymerization apparatus in which at least two or more polymerization vessels are usually connected in series is employed, such as a two-stage polymerization method, a three-stage polymerization method,... an n-stage polymerization method. will be implemented. It is also possible to perform a multi-stage polymerization method using a batch polymerization method in one polymerization tank. It is necessary to produce a specific amount of ultra-high molecular weight polyolefin in at least one polymerization vessel of the multi-stage polymerization process. The polymerization step for producing the ultra-high molecular weight polyolefin may be a first stage polymerization step,
It may be an intermediate polymerization step or may be a multiple stage of two or more stages. It is preferable to produce an ultra-high molecular weight polyolefin in the first stage polymerization step because it facilitates the polymerization process and allows easy control of the physical properties of the resulting polyolefin. In the polymerization step, 15 to 4 of the polyolefin used in the present invention is
0% by weight is the intrinsic viscosity [η]lJ (1 in decalin solvent)
It is necessary that the ultra-high molecular weight polyolefin has an ultra-high molecular weight polyolefin of 10 to 406 ρ/g (value measured at 35° C.), and furthermore, 18 to 37% by weight of the polyolefin used in the present invention, especially 21 to 35% by weight of the polyolefin used in the present invention. Weight %, intrinsic viscosity [η] is 15 to 35 d, I! /g, especially 18~
30d, 117g of ultra-high molecular weight polyolefin. In this polymerization process, the intrinsic viscosity of the ultra-high molecular weight polyolefin produced [
Even if η] is less than 10d, I) 72, the ultra-high molecular weight polyolefin produced in the polymerization step is 15 to 40
It is difficult to obtain injection-moldable polyolefins even outside the critical weight range.

In the multi-stage polymerization process, in the polymerization process for producing an ultra-high molecular weight polyolefin, polymerization is carried out in the presence of a catalyst consisting of the highly active titanium catalyst component (a) and the organoaluminum compound catalyst component (b). Polymerization can be carried out by gas phase polymerization or liquid phase polymerization. In either case, in the polymerization step to produce the ultra-high molecular weight polyolefin, the polymerization reaction is optionally carried out in the presence of an inert medium. For example, gas phase polymerization is carried out in the presence of a diluent consisting of an inert medium, if necessary, and liquid phase polymerization is carried out, if necessary, in the presence of a solvent consisting of an inert medium.

In the polymerization process for producing the ultra-high molecular weight polyolefin, the highly active titanium catalyst component (a) is used as a catalyst, for example, about 0.001 to about 20 milligram atoms, preferably about 0.005 to about 10 milligrams of titanium atoms per ρ of the medium. Milligram atoms, organoaluminum compound catalyst component (b),
It is preferable to use At/Ti (atomic ratio) in a ratio of about 0.1 to about 1000, particularly about 1 to about 500.

The temperature of the polymerization step for producing the ultra-high molecular weight polyolefin is generally in the range of about -20 to about 120°C, preferably about 0 to about 100°C, particularly preferably about 5 to about 95°C. Further, the pressure during the polymerization reaction is within a pressure range that allows liquid phase polymerization or gas phase polymerization at the above temperature, for example, atmospheric pressure to about 100 kg/an! , preferably atmospheric pressure ~
It is in the range of about 50 kg/crlt. Further, the polymerization time in the polymerization step may be set so that the amount of prepolymerized polyolefin produced is about 1000 g or more, preferably about 2000 g or more per milligram atom of titanium in the highly active titanium catalyst component. Moreover, in the polymerization step,
In order to produce the ultra-high molecular weight polyolefin,
Preferably, the polymerization reaction is carried out in the absence of hydrogen.

Furthermore, after carrying out the polymerization reaction, it is also possible to temporarily isolate and store the polymer under an inert medium atmosphere.

Inert media that can be used in the polymerization process to produce the ultra-high molecular weight polyolefin include, for example, propane, butane, pentane, hexane, heptane,
Aliphatic hydrocarbons such as octane, decane, and kerosene; Alicyclic hydrocarbons such as cyclopentane and cyclohexane; Aromatic hydrocarbons such as benzene, toluene, and xylene; Halogenated hydrocarbons such as dichloroethane, methylene chloride, and chlorobenzene; Alternatively, a mixture thereof can be used. Particularly desirable is the use of aliphatic hydrocarbons.

In addition, when producing the polyolefin used in the present invention, in addition to the polymerization step for producing the ultra-high molecular weight polyolefin, in the polymerization step for obtaining a low-molecular or high-molecular weight polyolefin, A polymerization reaction of the remaining olefin is carried out in the presence of hydrogen. If the polymerization process for producing an ultra-high molecular weight polyolefin is the first stage polymerization process, then the second stage and subsequent polymerization processes correspond to the polymerization process. If the polymerization step is located after the ultra-high molecular weight polyolefin producing polymerization step,
A polyolefin containing the ultra-high molecular weight polyolefin is supplied to the polymerization step, and when the polymerization step is located after a polymerization step other than the ultra-high molecular weight polyolefin-producing polymerization step, the low molecular weight or high molecular weight produced in the previous step is supplied. The polyolefin is fed and the polymerization is carried out in each case continuously. At that time, the polymerization step usually includes
Feedstock olefin and hydrogen are supplied. When the polymerization step is the first stage polymerization step, a catalyst consisting of the highly active titanium catalyst component (a) and the organoaluminum compound catalyst component (b) is supplied, and the polymerization step is the second stage polymerization step.
In the case of a polymerization step after the step, the catalyst contained in the polymerization product liquid produced in the previous step can be used as is, or the highly active titanium catalyst component (a) and/or the catalyst can be used as necessary. Alternatively, it is okay to additionally supplement the organic aluminum compound (b).

The low molecular weight to high molecular weight polyolefin thus obtained is 5 to 70% by weight, preferably 20 to 60% by weight, based on the total olefin components polymerized in the entire polymerization process.
, particularly preferably in an amount of 25 to 55% by weight.

The hydrogen supply ratio in the polymerization steps other than the ultra-high molecular weight polyolefin production polymerization step is usually 0.01-1 mole of olefin supplied to each polymerization step.
50 mol, preferably in the range of 0.05 to 30 mol.

The concentration of each catalyst component in the polymerization product liquid in the polymerization tank in the polymerization process other than the ultra-high molecular weight polyolefin production polymerization process is 1.1 in the polymerization volume! per unit, the amount of the treated catalyst in terms of titanium atoms is about 0.001 to about 0.1 milligram atoms, preferably about 0.005 to about 0.1 milligram atoms, and the polymerization system AI/'T'i ( atomic ratio) is about 1 to about 1
000, preferably about 2 to about 500. For this purpose, an organoaluminum compound catalyst component (b) can be additionally used as necessary. In addition, hydrogen/electron donors, halogenated hydrocarbons, etc. may be present in the polymerization system for the purpose of controlling the molecular weight, molecular weight distribution, etc.

The polymerization temperature is within a temperature range that allows slurry polymerization and gas phase polymerization, and is about 40°C or higher, more preferably about 50 to about 100°C.
A range of 0.degree. C. is preferred. Further, the polymerization pressure is, for example, atmospheric pressure to about 100 kg/*, particularly atmospheric pressure to about 50 kg/*.
A range of ci is preferred. The amount of polymer produced is about 1000 per milligram atom of titanium in the titanium catalyst component.
It is preferable to set the polymerization time so that the amount of polymerization is at least 5,000 g, particularly preferably at least about 5,000 g.

Polymerization steps other than the polymerization step for producing an ultra-high molecular weight polyolefin can be similarly carried out by a gas phase polymerization method or by a liquid synergistic method. Of course, it is also possible to employ different polymerization methods in each polymerization step. Among the liquid phase polymerization methods, a slurry suspension polymerization method is preferably employed.

In either case, the polymerization reaction is usually carried out in the presence of an inert medium in the polymerization step. For example, gas phase polymerization processes are carried out in the presence of an inert medium diluent, and liquid phase slurry suspension polymerization processes are carried out in the presence of an inert medium solvent.

Examples of the inert medium include the same inert media exemplified in the polymerization process for producing the ultra-high molecular weight polyolefin.

Polyolefin composition obtained in the polymerization process at the final stage of the product [
η]C is usually 3.5 to 1.5 dfJ/g, preferably 4.0 to 10 dρ/g, and the melting torque is 4.5 kg.
・Polymerization reaction is carried out so that the temperature is below medium.

The multi-step polymerization method can be carried out in a batch, semi-continuous or continuous manner.

The olefins to which the multi-stage polymerization method can be applied include:
As mentioned above, ethylene, propylene, 1-butene, 1-
Pentene, 1-hexene, 1-octene, 1-decene,
α-olefins such as 1-dodecene, 4-methyl-1-pentene, and 3-methyl-1-pentene can be exemplified, and it can also be applied to a method for producing homopolymers of these α-olefins. It can also be applied to a method for producing a copolymer consisting of a mixed component of two ingredients-1 and z. Among these α-olefins, the above multi-step polymerization method is applied to the production of ethylene polymers, which are ethylene or copolymers of ethylene and other α-olefins, and whose main component is ethylene. is preferred.

A polyolefin composition suitable for manufacturing the polyolefin bearing according to the present invention contains a sliding filler (B) in addition to the polyolefin (A) as described above. But it's okay.

As the sliding filler (B), conventionally known sliding fillers can be used without particular limitation, but specifically the following compounds are used.

Graphite powder, polytetrafluoroethylene resin (
PTFE), tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (PFA),
Fluororesin powders such as trifluorochloroethylene resin (PCTFE), tetrafluoroethylene-ethylene copolymer resin (ETFE), vinylidene fluoride resin, molybdenum fluoride powder, molybdenum sulfide powder, titanium oxide powder, polyphenylene sulfide resin powder etc.

These sliding fillers (B) are preferably used in powder form, and the particle size is preferably 0.01 to 500 μm, preferably 0.05 to 100 μm.

In the polyolefin composition constituting the bearing according to the present invention, the sliding filler (B) as described above is contained in an amount of 1 to 70 parts by weight, preferably 3 to 50 parts by weight, based on 100 parts by weight of the polyolefin (A). Parts by weight, more preferably 5 to 30 parts by weight.

The polyolefin composition constituting the polyolefin bearing according to the present invention contains, in addition to the polyolefin (A>),
It may also contain a fibrous filler (C).

As the fibrous filler (C), conventionally known fibrous fillers can be used without particular limitation, but specifically the following are used.

Glass fibers, carbon fibers, boron fibers, potassium titanate whiskers, metal fibers such as aluminum fibers, stainless steel fibers, etc.

Asbestos, aramid fiber, polyester fiber, polyamide fiber, etc.

These fibrous fillers (B) have a fiber diameter of 1 to 30
μm is preferably 5 to 20 μm, and the fiber length is 1000 μm.
~10,000 μm, preferably 3,000 to 6,000 μm, and the aspect ratio is 33 to 10,000, preferably 15
It is desirable that it is 0-1200.

In the polyolefin composition constituting the bearing according to the present invention, the above-mentioned fibrous filler (C) is preferably 1 to 70 parts by weight, preferably 3 to 50 parts by weight, based on the polyolefin (A>100 parts by weight). Preferably it is used in an amount of 5 to 30 parts by weight.

Phenol di=ID In addition to the polyolefin (A), the polyolefin composition constituting the polyolefin bearing according to the present invention includes:
It may also contain a phenolic stabilizer (D).

As the phenolic compound, conventionally known compounds can be used without particular limitation, and specifically, the following compounds are used.

2.6-di-t-butyl-4-methylphenol, 2.
6-di-cyclohexyl-4-methylphenol, 2.
6-diisopropyl-4-ethylphenol, 2.6-
Di-t-amyl-4-methylphenol, 2.6-di-t-octyl-4-n-propylphenol, 2.6-
Dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl-6-t-butylphenol, 2-t-butyl-2-ethyl-6-t-octylphenol, 2-inbutyl-4-ethyl-6- t-hexylphenol, 2-cyclohexyl-4-n-butyl-6-isobrobylphenol, TeI-rakis [methylene (3,5-di-t-butyl-4
-Hydroxy)hydrocinnamate comethane, etc.

Furthermore, a phenol compound having two or more phenol nuclei can also be used as the phenol stabilizer. Specifically, the following compounds are used as such phenolic compounds having two or more phenol nuclei.

2.2°-Methylenebis(4-methyl-6-t-butylphenol) 4.4′-Butylidenebis(3-methyl-6-t-butylphenol) 4.4′-Thiobis(3-methyl-6-t-butylphenol) ) 2.2'-thiobis(4-methyl-6-t-butylphenol) 1.3.5-trimethyl-2,4,6-tris(3,5
-di-t-butyl-4-hydroxyphenyl)benzylbenzene, 1.3.5-tris(2-methyl-4-hydroxy-5
-1-butylphenol)methane, tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyphenyl)propionate comethane, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid alkyl ester , 2.2'-oxamidobis[ethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propione-1-] and the like. As the β-3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid alkyl ester, an alkyl ester having 18 or less carbon atoms is particularly preferred. Also, tetrakis[methylene(2,4-
di-t-butyl-4-hydroxyphenyl)propionate comethane, n-octadecyl-3-(4°-hydroxy-3,5-di-t-butylphenyl)propionate, 2,6-di-t-7' Chill-p-cresol, 2.
4.6-Tris(3°,5'-di-t-butyl-4'-
hydroxybenzylthiono-1,3,5-)riazine,
2,2-methylenebis(4-methyl-6-t-butylphenol), 4,4-methylenebis(2,6-t-butylphenol)
-butylphenol>,2,2'-methylenebis[6-
(1-methylcyclohexyl)P-cresol], bis[3,5-bis(4-hydroxy-34-butylphenyl)butyric acid coglycol ester, 4,4°
-Butylidenebis(6-t-butyl-m-cresol)
, 1. L3-tris(2-methyl-4-hydroxy-
5-t-butylphenyl>butane, 1,3.5-tris(2,6-dimethyl-3-hydroxy-4-t-butylbenzyl)in cyanurate, 1,3.5-tris(3
, 5-di-t-butyl-4-hydroxybenzyl) -
2,4,6-trimethylbenzene, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)
Isocyanudo, 1,3,5-tris((3,5-di-
t-Butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, 2-octylthio-4
,6-di(4-hydroxy-3,5-di-t-butyl)
Phenoxy-1,3,5-triazine, 4,4-thiobis(6-1-butyl-m-cresol), and the like are used.

These phenolic stabilizers may be used alone or in combination.

In the polyolefin composition constituting the bearing according to the present invention, the phenolic stabilizer (B) such as -I
It is used in an amount of parts by weight, preferably from 0.01 to 0.5 parts by weight, more preferably from 0.05 to 0.2 parts by weight.

-Phosphite r! 7' I E The polyolefin composition constituting the polyolefin bearing according to the present invention may contain an organic phosphite stabilizer (C) in addition to the polyolefin (A>).

As the organic phosphite stabilizer, conventionally known stabilizers can be used without particular limitation, but specifically the following compounds are used.

1 Helioctyl phosphite, trilauryl phosphite, tridecyl phosphite, octyl-diphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, triphenyl phosphite, tris(butoxyethyl) phosphite 1 , tris(nonylphenyl)phosphite, distearylpentaerythritol diphosphite, tetra(tridecyl)-1,
1,3-tris(2-methyl-5-tert-butyl-
4-hydroxyphenyl)butane diphosphite, tetra(C12-C15 mixed alkyl) -4,4'-isopropylidene diphenyl diposphite, tetra(tridecyl) -4,4°-butylidene bis(3-methyl-
6-tert-butylphenol) diphosphite, tris(3,5-di-tert-butyl-4-hydroxyphenyl) phosphite, tris(mono-dimixed nonylphenyl) phosphite, hydrogenated-4,4-inpropylidene diphenol poly Posphite, bis(octylphenyl) bis[4,4°-butylidenebis(3-methyl-6-tert-butylphenol)] 1,6-
Hexaneoldiphosphite, phenyl 4,4°-
Isopropylidene diphenol pentaerythritol diphosphite I, bis(2,4-di-tert-butylphenyl) pentaerythritol diposite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite Phosphite, I ~ Lis [4
, 4-impropylidene bis(2-tert-butylphenol)] phosphite, phenyl diisodecyl phosphite, di(nonylphenyl) pentaerythritol diphosphite, tris(1,3-di-stearoyloxyimprovil) phosphite I・,4,4゛-inpropylidene bis(2-tert-butylphenol)
・Di(nonylphenyl) phosphite, 9,10-di-
Hydro-9-oxa-9-oxa-10-phosphaphenanthrene-10-oxide, tetrakis(2,4-
Examples include di-tert-butylphenyl>-4; io-biphenylene diphosphite.

Further, as the bis(dialkylphenyl)pentaerythritol diphosphite ester, a spiro type represented by the following formula (1) or a cage type represented by the formula (2) are also used. Usually, mixtures of both isomers are most often used for economic reasons arising from the process of preparing such Posphi I-esters.

Here, R1 and R2 are preferably alkyl groups having 1 to 9 carbon atoms, particularly tert-butyl groups among branched alkyl groups, and the substitution position in the phenyl group is 2.
, 4th position is most preferred. A preferred phosphite ester is bis(2,4-di-tert-butylphenyl)pentaerythri-1-hel diphosphite.

These organic phosphite stabilizers may be used alone or in combination.

In the polyolefin composition constituting the bearing according to the present invention, the organic phosphite stabilizer (C) as described above is
0.005 per 100 parts by weight of polyolefin (A)
It is used in an amount of ~5 parts by weight, preferably 0.01 to 0.5 parts by weight, more preferably 0.05 to 0.2 parts by weight.

-, thiether-based polyolefin composition constituting the polyolefin bearing according to the present invention, in addition to the polyolefin <A>,
It may also contain an organic thioether stabilizer (1?).

As the organic 1,000-onythyl stabilizer, conventionally known ones can be used without particular limitation, and specifically, the following compounds are used.

Dialkylthiodipropionic acids such as dilauryl, simylistyl, disudearyl, etc., and polyalcohols of alkylthiopropionic acids such as butyl, octyl, lauryl, stearyl, etc. (e.g. glycerin, trimethylolethane, trimethylolpropane,
esters of pentaerythritol, trishydroxyethyl isocyanurate (e.g. pentaerythritol I-
lutetralauryl thiopropionate).

More specifically, dilaurylthiodipropionate,
Simyristylthiodipropionate, distearylthiodipropionate, laurylstearylthiodipropionate, distearylthiodibutyrate, etc.

These organic thioether stabilizers may be used alone or in combination.

In the polyolefin composition constituting the bearing according to the present invention, the organic thioether stabilizer (F) as described above is contained in an amount of 0°005 to 100% by weight per 100 parts by weight of the polyolefin (A).
It is used in an amount of 5 parts by weight, preferably 0.01 to 0.5 parts by weight, more preferably 0.05 to 0.2 parts by weight.

In the polyolefin composition constituting the bearing according to the present invention,
In addition to the above-mentioned polyolefin (A>), if a phenolic stabilizer (D), an organic phosphite stabilizer (E), an organic thioether stabilizer (F), or more than one of these is included, injection molding is possible. The thermal stability during injection molding and long-term heat-resistant stability are improved, but when metal salts of higher fatty acids (G), which will be described later, are added as a stabilizer, polyolefins with even better thermal stability and long-term heat-resistant stability during injection molding can be obtained. A manufactured bearing is obtained.

The polyolefin composition constituting the bearing according to the present invention is
In addition to the polyolefin (A), it contains a higher fatty acid metal salt (G).

Examples of metal salts of higher fatty acids include magnesium salts of higher fatty acids such as stearic acid, oleic acid, lauric acid, capric acid, araxic acid, palmitic acid, and behenic acid;
alkaline earth metal salts such as calcium salts and barium salts,
Cadmium salt, alkali metal salts such as salts, lead salts, sodium salts, potassium salts, and lithium salts are used. Specifically, the following compounds are used.

Magnesium stearate, magnesium laurate,
Magnesium palmitate, calcium stearate,
Calcium oleate, calcium laurate, barium stearate, barium oleate, barium laurate, barium araxinate, barium behenate, stearin? [[i9, zinc oleate, zinc laurate, stearate, sodium stearate,
Sodium palmitate, sodium laurate, potassium stearate, potassium laurate, calcium 12-hydroxystearate, etc.

These metal salts of higher fatty acids may be used alone or in combination.

In the polyolefin composition constituting the bearing according to the present invention, the above metal salt of higher fatty acid (E) is contained in an amount of 0.005 to 5 parts by weight, preferably 0.01 parts by weight, based on 100 parts by weight of the polyolefin (A). It is used in an amount of ~0.5 parts by weight, more preferably 0.05-0.2 parts by weight.

In the present invention, in addition to the above-mentioned components, the polyolefin composition constituting the bearing may contain, for example, a heat stabilizer, a weather stabilizer, a pigment, a dye, a lubricant, a flame retardant, a neutron shielding agent, etc.
Compounding agents that are normally added and mixed with polyolefins can be added within a range that does not impair the purpose of the present invention.

As explained above, the polyolefin bearing according to the present invention does not impair the excellent mechanical properties inherently possessed by ultra-high molecular weight polyolefin, and does not cause delamination. Since it can be easily obtained by injection molding a polyolefin composition without any process, it is possible to obtain a bearing with excellent wear resistance, heat resistance, impact resistance, and sliding properties at a relatively low cost. Moreover, according to the present invention, since the polyolefin bearing itself obtained by injection molding a polyolefin composition has sufficient sliding properties, there is no need to coat it with molybdenum or the like in order to improve sliding properties. There is no need to separately supply or impregnate lubricant. Furthermore, since the polyolefin bearing according to the present invention has excellent wear resistance, heat resistance, impact resistance, and sliding properties, wear and tear at the sliding parts of the bearing is less likely to occur, and the temperature inside the device The sliding performance between the bearing and the shaft slidably accommodated therein will not deteriorate even if the bearing is raised, etc., and noise can be suppressed as much as possible. Therefore, when such a bearing is used in various precision equipment such as a VTR or other general equipment, it is possible to reduce the weight, cost, and noise of these equipment.

Agent: Patent Attorney: Shunbetsu Suzuki

Claims (1)

[Claims] 1) Intrinsic viscosity measured in decalin solvent at 135°C is 10
-40 dl/g ultra-high molecular weight polyolefin;
Intrinsic viscosity measured in decalin solvent at 35°C is 0.1-5
dl/g, and (i) the ultra-high molecular weight polyolefin has a content of 15 to 15% based on the total weight of the ultra-high molecular weight polyolefin and the low-molecular weight to high molecular weight polyolefin. (ii) the intrinsic viscosity measured in decalin solvent at 135°C [
η]_c is in the range of 3.5 to 15 dl/g, and (iii) a polyolefin bearing obtained by injection molding a polyolefin composition containing at least a polyolefin having a melting torque T of 4.5 kg·cm or less. . 2) The above polyolefin is produced in at least one polymerization step in the presence of a Ziegler type catalyst formed from a highly active titanium catalyst component (a) containing magnesium, titanium and halogen as essential components and an organoaluminium compound catalyst component (b). In the step, olefins are polymerized to produce ultra-high molecular weight polyolefins with an intrinsic viscosity of 10 to 40 dl/g, and in other polymerization steps, olefins are polymerized in the presence of hydrogen to produce ultra-high molecular weight polyolefins with an intrinsic viscosity of 0.1 to 5 dl/g. The polyolefin bearing according to claim 1, which is manufactured by a multi-step polymerization method that produces a polyolefin having a molecular weight to a high molecular weight. 3) The polyolefin bearing according to claim 1 or 2, wherein the polyolefin composition contains a sliding filler. 4) Claim 3, wherein the slidable filler is graphite, fluororesin powder, molybdenum fluoride, molybdenum sulfide, or polyphenylene sulfide resin powder.
Polyolefin bearings described in . 5) The polyolefin bearing according to any one of claims 1 to 4, wherein the polyolefin composition contains a fibrous filler. 6) The fibrous filler is glass fiber, carbon fiber,
The polyolefin bearing according to claim 5, which is boron fiber, potassium titanate whisker, asbestos, metal fiber, aramid fiber, polyester fiber, or polyamide fiber. 7) The polyolefin bearing according to any one of claims 1 to 6, wherein the polyolefin composition contains a stabilizer. 8) The polyolefin bearing according to claim 7, wherein the stabilizer is a phenolic stabilizer, an organic phosphite stabilizer, an organic thioether stabilizer, or a metal salt of a higher fatty acid.