JP5086564B2 - Solid lubricant and rolling bearing with solid lubricant - Google Patents

Description

  The present invention relates to a solid lubricant used under conditions in which the fluidity of the lubricant itself hinders lubrication, and a rolling bearing enclosing the solid lubricant, and more particularly, a stranded wire machine, an electric device, and a printing machine. The present invention also relates to a solid lubricant encapsulated rolling bearing used as various bearings for automobile parts and the like.

  In general, a rolling bearing lubricated with grease needs to be sealed by providing a sealing device such as a seal member in order to cope with the fluidity of grease during rotation of the bearing. Therefore, this grease lubrication method cannot be adopted for a special bearing with a small width that cannot be sealed. In addition, in a stranded wire machine in which the bearing itself is centrifugally moved, grease in the bearing is scattered by the action of centrifugal force and seizes in a short period of time, so the bearings are frequently replaced.

  Therefore, in order to cope with the above-mentioned various problems, the present inventors heated a mixture containing ultrahigh molecular weight polyethylene and grease having a dropping point higher than the melting point of the polyethylene to the above melting point to solidify. A bearing lubricating composition has been developed (see Patent Document 1 and Patent Document 2).

However, in Patent Document 1 and Patent Document 2 in which the ratio of grease as a lubricant component is increased in order to improve lubricity, grease using a paraffinic mineral oil as a base oil, solid wax, and ultrahigh molecular weight polyolefin are used. The mixture (grease-like) that has been heated and mixed to the melting temperature of solid wax (cooled to room temperature) and then cooled to room temperature has a soft hardness. When sealed in a bearing and heated to the melting temperature of ultra-high molecular weight polyolefin, the mixture is removed from the bearing. There are problems such as leakage.
Japanese Patent Publication No. 63-23239 Japanese Patent No. 2912733

  The present invention has been made in order to cope with such problems. A solid lubricant and a solid that do not leak from the bearing even when sealed in a bearing and heated to a temperature higher than the melting temperature of the ultra-high molecular weight polyolefin. An object is to provide a lubricant-enclosed bearing.

The solid lubricant of the present invention is a mixture comprising grease, an ultrahigh molecular weight polyolefin powder having an average molecular weight of 1 × 10 ^{6 to} 5 × 10 ⁶ , and a solid wax, which is equal to or higher than the gel point of the ultra high molecular weight polyolefin powder. A solid lubricant obtained by heating to a temperature of, followed by cooling to solidify, wherein the mixture comprises 60 to 89% by weight of the grease, 30 to 10% by weight of the ultrahigh molecular weight polyolefin powder, and the solid wax. The solid wax is characterized by containing a normal paraffin component having 36 or more linear carbon atoms in total of 13% by weight or more. Further, the normal paraffin component is characterized in that the mode value of the content rate in the linear carbon atom number distribution is the normal paraffin component having 30 to 33 linear carbon atoms.
Here, the gel point of the ultrahigh molecular weight polyolefin powder refers to a temperature at which the viscosity of the mixture rapidly increases when the mixture with grease or mineral oil is stirred while being heated.

  The grease is characterized in that a base oil is blended with a thickener, and the base oil is a mineral oil. The mineral oil is a paraffinic mineral oil.

  When the mixture is heated to a temperature equal to or higher than the melting point of the solid wax and then cooled to 20 ° C., the hardness of the mixture is 410 or less at an immiscibility of 100 ° C. The immiscible penetration is an immiscible penetration measured by JIS K 2220.

  The solid lubricant encapsulated rolling bearing of the present invention is a rolling bearing comprising an inner ring and an outer ring, and a rolling element interposed between the inner ring and the outer ring, and a solid lubricant encapsulated around the rolling element, This solid lubricant is the above-mentioned solid lubricant.

The solid lubricant of the present invention is a solid containing a total of 13% by weight or more of grease, an ultrahigh molecular weight polyolefin powder having an average molecular weight of 1 × 10 ^{6 to} 5 × 10 ⁶ , and normal paraffin components having 36 or more linear carbon atoms. A mixture of a wax and a predetermined ratio is a solid lubricant formed by heating to a temperature equal to or higher than the gel point of the ultra-high molecular weight polyolefin powder, and then cooling to solidify the mixture. After heating to the above temperature, the hardness of the mixture when cooled to 20 ° C becomes 410 or less at an immiscibility of 100 ° C. After sealing in the bearing, it is heated above the melting temperature of the ultrahigh molecular weight polyolefin. Even so, there is no leakage from the bearing.

  The solid lubricant encapsulated rolling bearing of the present invention is formed by encapsulating the solid lubricant of the present invention, so that there is no leakage at the time of high temperature use, excellent lubricity, stranded wire machine, electric equipment, printing machine, automobile parts. It can be suitably used as a rolling bearing used in various industrial machines such as electrical equipment and construction machinery.

The solid wax used in the present invention is used as an additive for suppressing oil seepage from the solid lubricant and as an additive for preventing leakage of the solid lubricant from the bearing when heat treatment is applied. The
Examples of the solid wax include vegetable waxes such as carnauba wax and candelina wax, animal waxes such as beeswax and insect wax, and petroleum waxes such as paraffin wax. The solid wax may be a blend such as a low molecular polyolefin containing the solid wax.

In the present invention, among these, a solid wax containing 13% by weight or more of a normal paraffin component having 36 or more linear carbon atoms is used. Moreover, a normal paraffin component is a normal paraffin component in which the mode of content rate in the linear carbon atom number distribution is between 30 and 33 linear carbon atoms.
When the normal paraffin component having 36 or more straight-chain carbon atoms is less than 13% by weight, the mixture of grease and ultra-high molecular weight polyolefin is heated to a temperature above the melting point of the solid wax and then cooled to 20 ° C. Hardness exceeds 410 at an immiscibility of 100 ° C.

The distribution of the content of normal paraffin components in the solid wax that can be used in the present invention is shown in FIG. In FIG. 1, the vertical axis indicates the content of normal paraffin components, the horizontal axis indicates the number of carbons, and distribution curves A, B, and C contain 13% by weight or more of normal paraffin components having 36 or more linear carbon atoms. The distribution curve D shows an example in which the normal paraffin component is less than 13% by weight.
The normal paraffin component has 18 to 60 linear carbon atoms. A suitable solid wax contains a total amount of normal paraffin components having a straight chain carbon atom number of 36 or more of 13% by weight or more, and the mode value of the content ratio is a normal paraffin component having a straight chain carbon atom number of 30 to 33. It is. A normal paraffin component having 31 or 32 linear carbon atoms is preferred. Most preferred is a solid wax having a normal paraffin component having 32 straight carbon atoms as a mode value.

The preferred solid wax is that each of the normal paraffin components having 18 to 28 linear carbon atoms and the normal paraffin component having 35 linear carbon atoms is not more than 6% by weight based on the total solid wax. Each normal paraffin component having 29 to 34 linear carbon atoms is 5 to 8% by weight, and each normal paraffin component having 36 to 60 linear carbon atoms is 4% by weight or less. Moreover, it is preferable that it is a distribution shape similar to the normal distribution which makes the mode value of the normal paraffin content rate a vertex.
Suitable solid waxes may include isoparaffin. Isoparaffins preferably have 18 to 60 carbon atoms. The total content of isoparaffin is preferably 20% by weight or less based on the total amount of solid wax.

The content of the normal paraffin component in the solid wax can be measured by a gas chromatograph.
As the gas chromatograph, an Agilent gas chromatograph HP-6890 or the like can be used. The measurement conditions in this case are shown below.
Column: Rtx-1, 0.1 μm, inner diameter 0.32 mm x length 15 m
Oven: 100-350 ° C at a heating rate of 10 ° C / min
Detection method: FID
Carrier gas: He
Sample injection method: Dissolve 0.1 g of sample in 10 ml of chloroform and inject with a microsyringe.

  The solid wax containing 13% by weight or more of normal paraffin components having 36 or more linear carbon atoms used in the present invention is preferably blended in an amount of 1 to 10% by weight in the solid lubricant. If it is less than 1% by weight, the oil release rate of the oil exuded from the solid lubricant becomes too high, and if it exceeds 10% by weight, the oil separation becomes too small.

The ultrahigh molecular weight polyolefin powder used in the present invention may be a powder composed of polyethylene, polypropylene, polybutene or a copolymer thereof, or a mixed powder obtained by blending individual powders, and is measured by the viscosity method of each powder. The average molecular weight is 1 × 10 ^{6 to} 5 × 10 ⁶ . A polyolefin having such a molecular weight range is superior to a low molecular weight polyolefin in rigidity and oil retention, and hardly flows even when heated to a high temperature.

  The blending ratio of the ultrahigh molecular weight polyolefin powder in the solid lubricant of the present invention is preferably 10 to 30% by weight. If it is less than 10% by weight, it is difficult to ensure the rigidity of the solid lubricant, and if it exceeds 30% by weight, it is difficult to improve the lubricity of the solid lubricant.

The grease used in the present invention is not particularly limited, and is a base oil blended with a thickener. Examples of the base oil include mineral oil, synthetic hydrocarbon oil, diester oil, polyol ester oil, and alkyl diphenyl ether oil. , Silicone oil, fluorine oil, and the like. Among these, it is preferable to use a mineral oil that is well solidified with an ultrahigh molecular weight polyolefin, and it is more preferable to use a paraffinic mineral oil that has a good compatibility with a solid wax among the mineral oils.
Thickeners include lithium soap, sodium soap, aluminum soap, calcium soap, barium soap, etc., or composite soaps and mixed soaps of these soaps, and non-soaps include urea, sodium terephthalate, polytetrafluoroethylene, Bentonite, silica gel, etc. can be used without particular limitation.

The blending ratio of grease in the solid lubricant of the present invention is preferably 60 to 89% by weight. If it is less than 60% by weight, the lubricity is inferior, and if it exceeds 89% by weight, the rigidity of the solid lubricant is inferior.
The blending amounts of the above solid wax, ultra-high molecular weight polyolefin powder and grease depend on the degree of oil separation, tenacity and hardness required for the solid lubricant. Therefore, the greater the amount of ultrahigh molecular weight polyolefin powder, the greater the hardness of the gel after being dispersed and held at a predetermined temperature. Various organic or inorganic fillers can be blended in order to increase rigidity while maintaining a high oil content.

The solid lubricant of the present invention is prepared by uniformly mixing a predetermined amount of grease and a predetermined amount of ultrahigh molecular weight polyolefin powder, enclosing it in a mold having a predetermined shape, and heating it to a temperature above the gel point of the ultrahigh molecular weight polyolefin powder. Then, it is cooled and solidified to obtain a solid lubricant having an oily surface, that is, a surface from which oil oozes. In addition, it is preferable to heat above the gel point and below the dropping point of the grease.
The melting point of the ultrahigh molecular weight polyolefin powder according to the present invention is not constant because it changes in accordance with the average molecular weight. For example, the melting point of the one having an average molecular weight of 2 × 10 ⁶ by the viscosity method is about 136 ° C. Commercially available products with the same average molecular weight include Mipperon XM-220 (manufactured by Mitsui Chemicals).
Therefore, in order to disperse and hold the ultra-high molecular weight polyolefin powder in the grease, after mixing both, the temperature is higher than the temperature at which the ultra-high molecular weight polyolefin powder causes gelation and lower than the dropping point of the grease, for example, 150 to Heating at 200 ° C. is preferred. Thereby, a solid solid lubricant can be obtained.

An example of the solid lubricant-enclosed rolling bearing of the present invention is shown in FIGS. FIG. 2 is a cross-sectional view of a rolling bearing that encloses a solid lubricant in a spot pack shape, and FIG. 3 is a cross-sectional view of the rolling bearing that encloses a solid lubricant in a full pack shape.
A solid lubricant encapsulated rolling bearing 1 of the present invention includes an inner ring 2 and an outer ring 3, and a rolling element 4 interposed between the inner ring 2 and the outer ring 3, and a solid lubricant 5 is provided around the rolling element 4. It is obtained by encapsulating.
The following method is mentioned as an example of the sealing method of the solid lubricant 5. A predetermined amount of grease and a predetermined amount of ultra-high molecular weight polyolefin powder are uniformly mixed and then heated to 90 to 120 ° C. to obtain a semi-solid state. Next, the bearing 1 is sealed while maintaining this state. As shown in FIGS. 2 (a) and 2 (b), the sealing method is such that a cage 6 made of two strips is overlapped and fixed by a rivet 7 between the inner ring 2 and the outer ring 3. What is enclosed in a so-called spot pack shape, or what is filled in a so-called full pack shape between the inner ring 2 and the outer ring 3 as shown in FIGS. 3 (a) and 3 (b). Can be mentioned. In the sealed state as described above, the entire bearing is heated to a temperature equal to or higher than the gel point of the ultrahigh molecular weight polyolefin powder and equal to or lower than the dropping point of the grease, and then cooled to solidify the semi-solid. The solid material is solidified to become a solid lubricant, and the solid lubricant-enclosed rolling bearing 1 is manufactured.

  The solid lubricant of the present invention does not leak from the bearing even when heated to a temperature higher than the melting temperature of the ultra-high molecular weight polyolefin, so the life of the solid lubricant-enclosed bearing can be improved. Therefore, enclosed in ball bearings, cylindrical roller bearings, tapered roller bearings, spherical roller bearings, needle roller bearings, thrust cylindrical roller bearings, thrust tapered roller bearings, thrust needle roller bearings, thrust spherical roller bearings, etc. It can be used as a solid lubricant.

Example 1
A mixture of lithium soap-paraffin mineral oil grease, ultra-high molecular weight polyolefin powder, and solid wax A (containing 14.3% by weight of normal paraffin components having a linear carbon atom number of 36 or more) in a proportion shown in Table 1 is vacuum degassed. It was put into a foam mixer (Aikosha Seisakusho: AGM-30X10LVTH), heated and mixed to the melting temperature of solid wax (about 110 ° C), and then cooled to room temperature (20 ° C) to obtain a grease-like mixture. . The immiscibility consistency at 100 ° C. of this mixture was measured. The results are shown in Table 1. In addition, distribution of the normal paraffin component of solid wax AD used for each Example and the comparative example respond | corresponds to the distribution curve AD illustrated in FIG.
Further, Table 1 shows the results of observing the leakage state of the solid lubricant when the mixture is sealed in a bearing 6204 and the bearing is heated at 160 ° C. for 30 minutes.
The mixture was placed in a φ10 × 8 mm mold, heated at 160 ° C. for 30 minutes, then cooled and solidified to obtain a solid lubricant. The hardness of the obtained solid lubricant was measured by durometer A hardness based on JIS K6253. The results are also shown in Table 1.

Example 2
The same treatment and measurement as in Example 1 were performed except that the solid wax B (containing 20.1% by weight of a normal paraffin component having a linear carbon atom number of 36 or more) was used instead of the solid wax A of Example 1. The results are also shown in Table 1.

Example 3
The same treatment and measurement as in Example 1 were performed except that instead of the solid wax A of Example 1, solid wax C (containing 44.8% by weight of a normal paraffin component having 36 or more linear carbon atoms) was used. The results are also shown in Table 1.

Comparative Example 1
The same treatment and measurement as in Example 1 were performed except that solid wax D (containing 12.5% by weight of a normal paraffin component having 36 or more linear carbon atoms) was used in place of the solid wax A of Example 1. The results are also shown in Table 1.

  As shown in Table 1, after stirring and mixing in each example, the mixture cooled to room temperature (20 ° C) had an immiscibility penetration of 100 ° C or less of 410 or less, and the solid lubrication obtained by sealing this mixture in a bearing The agent-enclosed bearing did not leak even when heated at 160 ° C for 30 minutes.

  Since the solid lubricant encapsulated rolling bearing of the present invention is formed by encapsulating the solid lubricant of the present invention, it has excellent lubricity, stranded wire, electric equipment, printing machine, automobile parts, electrical accessories, construction machinery, etc. It can be suitably used as a solid lubricant used in bearings for various industrial machines.

It is a content rate distribution map of the normal paraffin component in solid wax. 1 is a cross-sectional view of a solid lubricant-enclosed rolling bearing according to an embodiment of the present invention. It is sectional drawing of the solid lubricant enclosure rolling bearing which concerns on the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling bearing enclosed with solid lubricant 2 Inner ring 3 Outer ring 4 Rolling element 5 Solid lubricant 6 Cage 7 Rivet

Claims (6)

A mixture comprising grease, an ultrahigh molecular weight polyolefin powder having an average molecular weight of 1 × 10 ^{6 to} 5 × 10 ⁶ , and a solid wax is heated to a temperature equal to or higher than the gel point of the ultra high molecular weight polyolefin powder, and then cooled. A solid lubricant obtained by solidification,
The mixture comprises 60 to 89% by weight of the grease, 30 to 10% by weight of the ultra-high molecular weight polyolefin powder, and 10 to 1% by weight of the solid wax,
The solid wax contains a normal paraffin component having 36 or more linear carbon atoms in total of 13% by weight or more based on the total solid wax ,
The normal paraffin component contained in the solid wax is characterized in that the mode of content in the linear carbon atom number distribution is between 30 and 33 linear carbon atoms . 2. The solid lubricant according to claim 1, wherein the normal paraffin component contained in the solid wax has a mode of content in the linear carbon atom number distribution of 31 or 32 linear carbon atoms.   The solid lubricant according to claim 1 or 2, wherein the grease comprises a base oil and a thickener, and the base oil is a mineral oil.   The solid lubricant according to claim 3, wherein the mineral oil is a paraffinic mineral oil.   The hardness of the mixture when heated to a temperature equal to or higher than the melting point of the solid wax and then cooled to 20 ° C is 410 or less at an immiscibility of 100 ° C. The solid lubricant according to any one of claims 1 to 4. A rolling bearing comprising an inner ring and an outer ring, and a rolling element interposed between the inner ring and the outer ring, wherein a solid lubricant is sealed around the rolling element,
A solid lubricant-enclosed rolling bearing, wherein the solid lubricant is the solid lubricant according to any one of claims 1 to 5.

Images