JP2017082024A - Grease, mechanical parts, method of using grease, and method for producing grease - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a grease which has a low environmental load, is excellent in safety for human body, has a high mixing consistency and a dropping point, is excellent in heat resistance, and can be easily washed with water, and the grease is used. Provided are a mechanical component, a method of using the grease, and a method of manufacturing the grease. A grease containing a base oil and hydrophilic nanofibers having a thickness (d) of 0.01 to 500 nm. [Selection diagram] None

Description

  The present invention relates to a grease, a mechanical component using the grease, a method of using the grease, and a method of manufacturing the grease.

  Various general industrial machines are equipped with sliding parts such as bearings, and the sliding parts of the sliding parts use lubricating materials such as grease and lubricating oil for smooth driving. . In particular, grease is widely used for lubrication of sliding parts because it is easier to seal than lubricating oil, and the size and weight of the applied machine can be reduced.

Incidentally, sliding parts such as bearings are also mounted on food machines for mixing and processing edible raw materials, and grease is often used for sliding parts of the sliding parts.
However, there is a possibility that the grease used for the sliding portion may be mixed into food raw materials and edible products. If a substance harmful to the human body is mixed as a constituent component of the grease, the grease may be mixed into food raw materials or edible products, thereby causing an unexpected harm to the human body.
Therefore, the grease used in food machinery for mixing and processing edible raw materials requires not only the lubrication performance required for general grease but also safety for the human body.

In recent years, various greases have been proposed as greases for food machinery that can meet such demands.
For example, Patent Document 1 discloses a grease for a food machine using calcium stearate as a thickener in a base oil containing a fatty acid ester and an oil as a food additive in a predetermined ratio.
Patent Document 2 discloses a grease composition in which the base oil is a saturated fatty acid triglyceride composed of an ester of a saturated fatty acid and glycerin, and the thickener is a mixture of calcium stearate and aluminum stearate. .
The greases disclosed in Patent Documents 1 and 2 are made in consideration of environmental load and safety to the human body.

JP 2009-91502 A JP 2014-240467 A

However, since the grease disclosed in Patent Documents 1 and 2 uses calcium stearate as a thickener, the dropping point is as low as less than 150 ° C., and the heat resistance is poor, so that it is difficult to use in a high temperature environment.
Further, since the greases disclosed in Patent Documents 1 and 2 have high water resistance, it is difficult to wash away the grease used for the sliding portion with water when the food machine is washed with water.
Therefore, there is a need for a grease suitable for food machinery that has excellent heat resistance and can be easily washed with water.

  The present invention has been made to solve the above-mentioned problems, has a low environmental load and is excellent in safety to the human body, has a high blending penetration and dropping point, is excellent in heat resistance, and An object of the present invention is to provide a grease that can be easily washed with water, a mechanical part using the grease, a method of using the grease, and a method of manufacturing the grease.

  As a thickener, the present inventors use hydrophilic nanofibers that have a low environmental burden and are excellent in safety to the human body, and are prepared so that hydrophilic nanofibers of a predetermined thickness are dispersed. However, the present inventors have found that the above problems can be solved and completed the present invention.

That is, the present invention relates to the following [1] to [5].
[1] A grease containing a base oil and hydrophilic nanofibers having a thickness (d) of 0.01 to 500 nm.
[2] A grease obtained by mixing hydrophilic nanofibers having a thickness (d ′) of 0.01 to 500 nm and a base oil.
[3] A mechanical part using the grease according to [1] or [2].
[4] A method for using grease, wherein the grease according to [1] or [2] is used for lubricating a mechanical part of a food machine.
[5] A method for producing grease, comprising the following steps (1) to (2).
Step (1): An aqueous dispersion obtained by blending hydrophilic nanofibers having an average thickness (d ′) of 0.01 to 500 nm in water, a base oil, and a compatibilizing agent are mixed, and a mixed solution Preparing the step.
Step (2): A step of removing water and the compatibilizer from the mixed solution.

  The grease of the present invention has a low environmental load and is excellent in safety to the human body, has a high miscibility and dropping point, is excellent in heat resistance, and can be easily washed with water. Therefore, the grease is suitable for use in lubricating a sliding part of a food machine.

[Aspect of Grease of the Present Invention]
The grease of the present invention is a grease (first grease) containing a base oil and hydrophilic nanofibers having a thickness (d) of 0.01 to 500 nm.
The grease according to another aspect of the present invention is a grease (second grease) obtained by mixing hydrophilic nanofibers having a thickness (d ′) of 0.01 to 500 nm and a base oil.
In the second grease, an aqueous dispersion obtained by blending hydrophilic nanofibers having a thickness (d ′) of 0.01 to 500 nm in water, a base oil, and a compatibilizing agent are mixed. And after preparing a liquid mixture, it is preferable that it is a grease obtained by removing water and the said compatibilizing agent from the said liquid mixture.
The details of the aqueous dispersion and the compatibilizing agent are as described in the item of “Production method of grease of the present invention” below.

Since both the first and second greases of the present invention use hydrophilic nanofibers as a thickener, they can be easily washed with water.
In the present invention, the term “hydrophilic” is used to mean a substance having a property of being partially dissolved in water at room temperature (25 ° C.). Specifically, 0.05 g of the target substance is dissolved in 50 mL of water with stirring until equilibrium, and when it is treated with a membrane filter having an opening of 1 μm, 1 mass of the component that passes is contained in the substance. If it is contained in an amount of at least%, it can be determined that the substance is “hydrophilic”.

In the first grease, the thickness (d) of the hydrophilic nanofibers contained in the grease (that is, the thickness (d) of the hydrophilic nanofibers dispersed in the base oil) is defined. The grease of No. 2 defines the thickness (d ′) of the hydrophilic nanofiber before mixing with the base oil.
By satisfy | filling the said prescription | regulation, it is easy to disperse | distribute hydrophilic nanofiber uniformly in a base oil, forming a higher order structure in hydrophilic nanofiber. As a result, even if the content of the hydrophilic nanofibers is small, a grease having a high miscibility and a dropping point and excellent heat resistance can be obtained.
In the present specification, “the content of the hydrophilic nanofiber is small” means that the content of the hydrophilic nanofiber is 20 mass% or less (preferably 15 mass%) based on the total amount of grease (100 mass%). Mass% or less, more preferably 10 mass% or less).
In this specification, the “first grease” and the “second grease” are collectively referred to as “the grease of the present invention” or “the grease of one embodiment of the present invention”.

  The grease of one embodiment of the present invention, together with the base oil and the hydrophilic nanofibers, does not impair the effects of the present invention, and is in the range of considering the influence on safety to the human body. You may contain the various additive mix | blended with grease.

  The total content of the base oil and the hydrophilic nanofiber in the grease of one embodiment of the present invention is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, based on the total amount (100% by mass) of the grease. %, More preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass.

Hereinafter, each component contained in the grease of the present invention will be described.
In the first and second greases of the present invention, details of hydrophilic nanofibers (preferable shape such as thickness (d ′), suitable forming material, preferred content range, etc.) and base oil Details (preferred types, properties, ranges of contents, etc.) and details (types, ranges of contents, etc.) of various additives blended with the hydrophilic nanofiber and the base oil are the same as each other.

<Base oil>
The base oil used in the present invention is not particularly limited as long as it can improve the lubricating performance as a grease, has a low environmental load, and is excellent in safety to the human body. Oils, synthetic oils such as fatty acid esters, and liquid paraffin.
In addition, the base oil used by this invention may be used individually by 1 type, and the mixture which used 2 or more types together may be sufficient as it.

  The vegetable oil is an oil derived from a plant, specifically, rapeseed oil, peanut oil, corn oil, cottonseed oil, canola oil, soybean oil, sunflower oil, palm oil, palm oil, safflower oil, Examples are camellia oil, olive oil, peanut oil and the like.

  Animal oils are oils derived from animals, and specific examples include lard, cow leg oil, willow oil, sardine oil, herring oil and the like.

Synthetic oils include fatty acid esters, specifically, medium-chain fatty acid triglycerides, diglycerin caprylate, diglycerin caprylate oleate, diglycerin oleate, decaglycerol caprylate oleate, deca Examples include glycerin oleate.
Synthetic oils other than fatty acid esters include normal paraffin, isoparaffin, polybutene, polyisobutylene, 1-decene oligomer, poly α-olefin (PAO) such as a copolymer of 1-decene and ethylene, and hydrides thereof. Etc.

The fatty acid constituting the fatty acid ester is preferably a fatty acid having 8 to 22 carbon atoms, specifically, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, erucic acid, palmitolein. Examples include acids, oleic acid, linoleic acid, linolenic acid, isostearic acid, arachidic acid, ricinoleic acid, 12-hydroxystearic acid and the like.
Specific fatty acid esters include glycerin fatty acid esters, polyglycerin fatty acid esters, and propylene glycol fatty acid esters.

  Examples of the glycerol fatty acid ester include glycerol monooleate, glycerol monostearate, glycerol monocaprylate, glycerol dioleate, glycerol distearate, and glycerol dicaprylate.

  Examples of polyglycerol fatty acid esters include diglycerol monooleate, diglycerol monoisostearate, diglycerol dioleate, diglycerol trioleate, diglycerol monostearate, diglycerol distearate, and diglycerol tristearate. , Diglycerol triisostearate, diglycerol monocaprylate, diglycerol dicaprylate, diglycerol tricaprylate, triglycerol monooleate, triglycerol dioleate, triglycerol trioleate, triglycerol tetraoleate, tri Glycerol monostearate, triglycerin distearate, triglycerin tristearate, triglycerin tetrastearate, triglycerin monocaprylate, triglycerin dica Relate, triglycerol tricaprylate, triglycerol tetracaprylate, diglycerol monooleate monostearate, diglycerol monooleate distearate, diglycerol monocaprylate monostearate, triglycerol monooleate monostearate Acid ester, triglycerin dioleic acid distearate, triglycerin dioleic acid monostearate, triglycerin monooleic acid monostearic acid monocaprylate, diglycerin monolaurate, diglycerin dilaurate, triglycerin mono Laurylate, Triglycerin trilaurylate, Triglycerin trilaurylate, Diglycerin monomyristylate, Diglycerin dimyristylate Triglycerol monomyristylate, triglycerol dimyristylate, triglycerol trimyristylate, diglycerol monolinoleate, diglycerol dilinoleate, triglycerol monolinoleate, triglycerol dilinoleate, triglycerol trilinoleate , Decaglycerin monooleate, decaglycerin monostearate, decaglycerin monocaprylic acid monooleate and the like.

  Examples of the propylene glycol fatty acid ester include propylene glycol monooleate, propylene glycol monostearate, propylene glycol monocaprylate, propylene glycol monolaurate, and the like.

Examples of the liquid paraffin include C _m H _n (m, where n is an integer of 1 or more, where n <2m + 2), an alicyclic hydrocarbon compound having a ring structure, or a mixture thereof.

The kinematic viscosity at 40 ° C. of the base oil used in the present invention is preferably 5 to 130 mm ² / s, more preferably 7 to 110 mm ² / s, and still more preferably 10 to 100 mm ² / s.
If the kinematic viscosity is 5 mm ² / s or more, it is possible to suppress the phenomenon that the grease is oil-separated. On the other hand, if the kinematic viscosity is 130 mm ² / s or less, oil is easily supplied to the sliding portion.
The base oil used in the present invention may be a mixed base oil prepared by combining a high-viscosity base oil and a low-viscosity base oil and adjusting the kinematic viscosity to the above range.

The viscosity index of the base oil used in the present invention is preferably 60 or more, more preferably 70 or more, and still more preferably 80 or more.
In the present invention, the kinematic viscosity and viscosity index at 40 ° C. mean values measured in accordance with JIS K2283: 2003.

  The content of the base oil contained in the grease of the present invention is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more, based on the total amount (100% by mass) of the grease. More preferably, it is 70 mass% or more, Preferably it is 99.9 mass% or less.

<Hydrophilic nanofiber>
In the present invention, the hydrophilic nanofiber means a fibrous material composed of a forming material containing a hydrophilic compound and having a thickness of 500 nm or less, and includes a flake-like material, a powder-like material, and a particulate material. Are distinguished.
In the present invention, the “thickness” of the hydrophilic nanofiber is the same as the thickness of a general fibrous material, but is perpendicular to the tangential direction at an arbitrary point on the side surface of the hydrophilic nanofiber. If the cut surface is a circle or an ellipse, the diameter or major axis is the cut surface when cut, and if the cut surface is a polygon, it indicates the diameter of the circumscribed circle of the polygon.

  When a flaky, powdery, or particulate hydrophilic compound having a size of several μm is added to the base oil as a thickener, the hydrophilic compound aggregates in the base oil, and so-called “dama” tends to occur. As a result, agglomerates of hydrophilic compounds are deposited on the surface of the resulting grease, and the dispersed state tends to be non-uniform. In this case, it is necessary to add a large amount of a hydrophilic compound in order to increase the blending degree of the obtained grease. However, since it contains particles larger than the oil film thickness, the grease has poor wear resistance. .

  On the other hand, the grease of the present invention includes hydrophilic nanofibers having a thickness (d) of 0.01 to 500 nm. As a result, the hydrophilic nanofibers maintain a uniformly dispersed state while forming a higher order structure in the base oil, and as a result, even if the content of the hydrophilic nanofibers is small. Regardless, it can be a grease with high penetration and dropping point.

In the present invention, “thickness (d)” indicates the thickness of the hydrophilic nanofibers contained in the grease and dispersed in the base oil. It is distinguished from “fiber thickness (d ′)”.
The thickness (d) of the hydrophilic nanofibers dispersed in the base oil is 0.01 to 500 nm, but from the above viewpoint, preferably 0.1 to 300 nm, more preferably 1 to 200 nm, still more preferably. Is 2 to 100 nm.

The grease of the present invention contains at least hydrophilic nanofibers with a thickness (d) in the above range, but contains hydrophilic nanofibers with a thickness (d) outside the above range. Also good.
However, in the grease of one embodiment of the present invention, from the viewpoint of forming a grease in which hydrophilic nanofibers are uniformly dispersed while forming a higher order structure by hydrophilic nanofibers, the hydrophilic nanofibers contained in the grease Among them, the average value of the thickness (d) of 10 arbitrarily selected hydrophilic nanofibers is 0.01 to 500 nm (more preferably 0.1 to 300 nm, still more preferably 1 to 200 nm, still more preferably. 2-100 nm).
In addition, from the above viewpoint, out of 10 hydrophilic nanofibers included in the grease, the number of hydrophilic nanofibers having a thickness (d) in the above range is 1 or more (more preferably). 5 or more, more preferably 7 or more), and any of the selected 10 hydrophilic nanofibers in thickness (d) is more preferably a hydrophilic nanofiber in the above range. .

The aspect ratio of the hydrophilic nanofibers contained in the grease of the present invention is preferably 5 or more, more preferably 10 or more, and still more preferably 15 or more.
The “aspect ratio” is the ratio of the length to the thickness of the hydrophilic nanofiber to be observed [length / thickness], and the “length” of the hydrophilic nanofiber is the hydrophilic property. The distance between the two most distant points of the nanofiber.
In addition, when it is difficult to identify the length of a part of the hydrophilic nanofiber to be observed due to contact with another hydrophilic nanofiber, the thickness of the hydrophilic nanofiber to be observed is measured. It is only necessary to measure the length of only the part where the aspect ratio is possible and the aspect ratio of the part is within the above range.
Further, among the hydrophilic nanofibers contained in the grease of the present invention, the average aspect ratio (hereinafter also referred to as “average aspect ratio”) of 10 arbitrarily selected hydrophilic nanofibers is 5 or more (more preferably). Is preferably 10 or more, more preferably 15 or more.

The thickness (d ′) of the hydrophilic nanofiber before mixing with the base oil is preferably 0.01 to 500 nm, more preferably 0.1 to 300 nm, still more preferably 1 to 200 nm, and still more preferably 2. ~ 100 nm.
Further, the average aspect ratio of the hydrophilic nanofibers as a raw material before mixing with the base oil is preferably 5 or more, more preferably 10 or more, and further preferably 15 or more.

  In the present specification, the thickness and aspect ratio of the hydrophilic nanofiber are values measured using an electron microscope or the like.

The hydrophilic nanofiber used in the present invention only needs to be composed of a forming material containing a hydrophilic compound. Examples of the hydrophilic compound include a compound having a functional group having a hydrogen bonding hydroxyl group such as a hydroxyl group and an amino group, and a metal oxide.
However, the hydrophilic nanofiber used in the present invention preferably contains a polysaccharide from the viewpoint of a grease having a low environmental load and excellent safety to the human body and from the viewpoint of compatibility with the base oil. .
In the present invention, the “polysaccharide” includes an oxidized polysaccharide.
Among the polysaccharides, it is preferable to include one or more selected from cellulose, carboxymethylcellulose, chitin, chitosan, seurouronic acid, chitouronic acid, and amylouronic acid, and more preferably to include cellulose.

Moreover, the hydrophilic nanofiber used in the present invention may be a nanofiber whose surface has been subjected to a modification treatment, and the modification treatment is performed using an oxidation treatment in the form of a metal salt. May be.
More specifically, hydrophilic nanofibers that have been subjected to at least one modification treatment selected from carboxymethylation, TEMPO oxidation, and periodate oxidation on the surface of the hydrophilic nanofibers can also be used. .

  In the hydrophilic nanofibers used in the present invention, the content ratio of the hydrophilic nanofibers containing polysaccharides is preferably 60 to 100 mass%, more preferably 70, based on the total amount (100 mass%) of the hydrophilic nanofibers. It is -100 mass%, More preferably, it is 80-100 mass%, More preferably, it is 90-100 mass%.

As a polymerization degree of polysaccharide, Preferably it is 50-3000, More preferably, it is 100-1500, More preferably, it is 150-1000, More preferably, it is 200-800.
In the present invention, the degree of polymerization of the polysaccharide polymer means a value measured by a viscosity method.

In the grease of the present invention, the content of hydrophilic nanofibers is preferably 0.1 to 20% by mass, more preferably 0.5 to 17% by mass, and still more preferably based on the total amount (100% by mass) of the grease. Is 0.7 to 15% by mass, more preferably 1.0 to 10% by mass.
When the content of the hydrophilic nanofiber is 0.1% by mass or more, a grease having a high miscibility and a dropping point can be obtained.
On the other hand, when the content of the hydrophilic nanofiber is 20% by mass or less, a grease having excellent wear resistance can be obtained.

<Various additives>
In the grease of one aspect of the present invention, various additives added to foods, food additives, and general greases are included within the range in which the effects on the human body are taken into consideration without impairing the effects of the present invention. You may contain.
Examples of the various additives include, for example, antioxidants, rust inhibitors, oiliness agents, antibacterial agents, rust inhibitors, friction modifiers, lubricity improvers, thickeners, modifiers, cleaning dispersants, and corrosion inhibitors. Agents, antifoaming agents, extreme pressure agents, metal deactivators and the like.
These various additives may be used alone or in combination of two or more.

  When the grease of one embodiment of the present invention contains these additives, each content of these additives is preferably 0.01 to 20% by mass based on the total amount (100% by mass) of the grease. More preferably, it is 0.05-10 mass%, More preferably, it is 0.1-5 mass%, More preferably, it is 0.2-2 mass%.

[Characteristics of the grease of the present invention]
The penetration of the grease of the present invention at 25 ° C. is preferably from 200 to 350, more preferably from 220 to 340, from the viewpoint that the hardness of the grease is in an appropriate range, and low temperature torque characteristics and wear resistance are good. More preferably, it is 250-320.
In this specification, the grease penetration is a value measured in accordance with JIS K2220 7: 2013.

The dropping point of the grease of the present invention is preferably 200 ° C. or higher, more preferably 220 ° C. or higher, still more preferably 240 ° C. or higher, and still more preferably 270 ° C. or higher.
In the present specification, the dropping point of grease is a value measured in accordance with JIS K2220 8: 2013.

In the grease of the present invention, when the grease is heated at 150 ° C., the time until the penetration of the grease becomes 200 or less or 350 or more is preferably 200 hours or more, more preferably 300 hours or more, More preferably, it is 400 hours or more.
The above-mentioned “time until the grease penetration is 200 or less or 350 or more” means a value measured based on the “heat resistance test” described in the examples.

In the grease of the present invention, the mass of the grease washed away with water measured by a test method based on the water wash durability test method of JIS K2220: 2013 using water at 38 ° C. is 100 parts by weight of the grease before the test. Is preferably 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, still more preferably 35% by mass or more, and particularly preferably 38% by mass or more.
In addition, said "method based on the water washing durability test method of JIS K2220: 2013" is specifically based on the method as described in an Example.

[Method for Producing Grease of the Present Invention]
It is preferable that the manufacturing method of the grease of this invention has the following process (1)-(2).
Step (1): An aqueous dispersion obtained by blending hydrophilic nanofibers having a thickness (d ′) of 0.01 to 500 nm in water, a base oil, and a compatibilizer are mixed to prepare a mixed solution. Process.
Step (2): A step of removing water and the compatibilizer from the mixed solution.
The grease obtained through such steps (1) and (2) has a thickness (in the base oil, while suppressing the aggregation of hydrophilic nanofibers and maintaining the fiber shape in the base oil. d) Hydrophilic nanofibers having a diameter of 0.01 to 500 nm can be dispersed. As a result, it is possible to produce a grease in which hydrophilic nanofibers are uniformly dispersed while forming a higher order structure with hydrophilic nanofibers in the base oil.
Hereinafter, steps (1) and (2) will be described.

<Step (1)>
In step (1), an aqueous dispersion obtained by blending hydrophilic nanofibers having a thickness (d ′) of 0.01 to 500 nm in water, a base oil, and a compatibilizing agent are mixed, and the mixed solution is mixed. It is a process of preparing.
The details of the hydrophilic nanofiber and the base oil used in the step (1) are as described above.
The “thickness (d ′)” used herein indicates the thickness of the hydrophilic nanofiber as a raw material before blending in the base oil or water as described above. The preferred range of d ′) ”is the same as above.

The solid concentration of the aqueous dispersion obtained by blending hydrophilic nanofibers is preferably 0.1 to 70% by mass, more preferably 0.5 to 0.5%, based on the total amount (100% by mass) of the aqueous dispersion. It is 60 mass%, More preferably, it is 1.0-50 mass%.
The aqueous dispersion can be prepared by mixing hydrophilic nanofibers in water, a surfactant or the like as necessary, and thoroughly stirring manually or by a stirrer.

From the viewpoint of producing a grease in which hydrophilic nanofibers are uniformly dispersed while forming a higher order structure with hydrophilic nanofibers in the base oil, the thickness of the hydrophilic nanofibers contained in the aqueous dispersion Is preferably 0.01 to 500 nm, more preferably 0.1 to 300 nm, still more preferably 1 to 200 nm, and still more preferably 2 to 100 nm.
From the same viewpoint, the average aspect ratio of the hydrophilic nanofibers contained in the aqueous dispersion is preferably 5 or more, more preferably 10 or more, and further preferably 15 or more.

The compatibilizing agent may be any solvent having good compatibility with both water and oil. For example, alcohols such as propanol, ethylene glycol, propylene glycol, N, N-dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP) and the like.
Among these, alcohols are preferable, and hexylene glycol or propylene glycol is more preferable.

  The blending amount of the compatibilizing agent in the mixed solution prepared in step (1) is preferably 5 to 70% by mass, more preferably 10 to 60% by mass, and still more preferably based on the total amount (100% by mass) of the mixed solution. Is 15-50 mass%.

  The amount of water in the mixed solution prepared in step (1) is preferably 1 to 60% by mass, more preferably 3 to 50% by mass, and still more preferably 5 based on the total amount (100% by mass) of the mixed solution. -40 mass%.

  The mixing ratio of water and the compatibilizing agent [water / compatibilizing agent] in the mixed solution prepared in the step (1) is preferably a mass ratio, preferably 0.01 to 10.0, more preferably 0. 0.02 to 7.0, more preferably 0.03 to 5.0, and still more preferably 0.04 to 4.0.

  The mixture may contain the above-mentioned various additives blended in general grease, together with an aqueous dispersion formed by blending hydrophilic nanofibers, a base oil, and a compatibilizing agent. These components can be mixed and sufficiently stirred manually or by a stirrer to prepare a mixture.

<Step (2)>
Step (2) is a step of removing water and the compatibilizing agent from the mixed solution prepared in step (1).
As a method of removing water and the compatibilizing agent, a method of heating the mixture and evaporating and removing the water and the compatibilizing agent is preferable.
As conditions for evaporating and removing water, it is preferable to heat the mixture at a temperature range of 0 to 100 ° C. under an environment where the pressure is 0.001 to 0.1 MPa.
Moreover, as conditions for evaporating and removing the compatibilizer, the pressure range is 0.001 to 0.1 MPa, and the temperature range is [the boiling point (° C.) of the compatibilizer] −120 ° C. to [the compatibilizer. The boiling point (° C.)] of the mixture is preferably heated at −0 ° C.
In addition, you may perform evaporation removal of water and a compatibilizing agent by atmospheric distillation.

  After removing water and the compatibilizing agent from the mixture, the grease of the present invention can be obtained through post-treatment steps such as homogenization using a roll mill or the like, if necessary.

[Mechanical parts using the grease of the present invention, method of using the grease of the present invention]
The grease of the present invention has a low environmental load and is excellent in safety to the human body, has a high miscibility and dropping point, is excellent in heat resistance, and can be easily washed with water.

Therefore, the grease of the present invention is suitable for lubrication of sliding parts such as food machine bearings and gears.
That is, the present invention also provides the following mechanical parts and methods of using grease.
(1) A mechanical component using the grease of the present invention.
(2) A method for using grease, wherein the grease of the present invention is used for lubricating mechanical parts of food machinery.
The mechanical component (1) is preferably a mechanical component incorporated in a food machine such as mixing food ingredients or manufacturing food.
The “grease” used in the above (1) and (2) is the grease of the present invention, and the details are as described above.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Various characteristics were determined according to the following methods.

(1) Kinematic viscosity at 40 ° C., viscosity index Measured according to JIS K2283: 2000.
(2) Thickness and aspect ratio of hydrophilic nanofibers Using a transmission electron microscope (TEM), the thickness and length of 10 arbitrarily selected hydrophilic nanofibers were measured, respectively. / The value calculated from “thickness” was defined as the “aspect ratio” of the target hydrophilic nanofiber.
(3) Mixing penetration It measured at 25 degreeC based on JISK2220 7: 2013.
(4) Dropping point Measured according to JIS K2220 8: 2013.

The details of the base oil and hydrophilic nanofibers used in the examples and comparative examples are as follows.
<Base oil>
Rapeseed oil: 40 ° C. kinematic viscosity = 39 mm ² / s, viscosity index = 204.
PAO: poly α-olefin, 40 ° C. kinematic viscosity = 64 mm ² / s, viscosity index = 135.
<Hydrophilic nanofiber dispersion>
CNF (I) dispersion: manufactured by Sugino Machine Co., Ltd., product name “BiNFi-s” (cellulose nanofiber (CNF (I)) having a polymerization degree of 600 (thickness (d ′) = 20 to 50 nm (average value)) 35 nm), aspect ratio = 100 or more (average aspect ratio of 100 or more)) in an aqueous dispersion having a solid content concentration of 11.0% by mass.

Example 1
91 g of the CNF (I) dispersion, which is a hydrophilic nanofiber dispersion (of which CNF (I) amount is 10.0 g), 90 g of rapeseed oil, which is a base oil, and 33 g of propylene glycol, which is a compatibilizing agent, are mixed. The mixture was sufficiently stirred at 25 ° C. to prepare a mixed solution.
Then, the mixed solution is heated to 90 ° C. in an environment of 0.02 MPa to evaporate and remove water from the mixed solution, and further heated to 170 ° C. in an environment of 0.02 MPa. The solubilizer propylene glycol was also removed by evaporation.
After cooling to room temperature (25 ° C.), homogenization was performed using a three-roll mill to obtain grease (1) having a CNF (I) content of 10 mass%.
Of the CNF (I) contained in the obtained grease (1), the thickness (d) of 10 arbitrarily selected CNF (I) is 20 to 50 nm (the average value of the thickness (d) is The aspect ratio of these 10 CNF (I) s was 100 or more (the average value of the aspect ratios was also 100 or more).

Example 2
73 g of the above-mentioned CNF (I) dispersion which is a hydrophilic nanofiber dispersion (of which CNF (I) amount: 8.0 g), 92 g of the rapeseed oil which is a base oil, and 33 g of hexylene glycol which is a compatibilizer. The mixture was mixed and sufficiently stirred at 25 ° C. to prepare a mixed solution.
Then, in the same environment and operation as in Example 1, water and hexylene glycol, which is a compatibilizing agent, are evaporated and removed from the mixed solution, cooled to room temperature (25 ° C.), and then homogenized using a three-roll mill. The grease (2) having a CNF (I) content of 8.0% by mass was obtained.
Of the CNF (I) contained in the obtained grease (2), the thickness (d) of 10 arbitrarily selected CNF (I) is 20 to 50 nm (the average value of the thickness (d) is The aspect ratio of these 10 CNF (I) s was 100 or more (the average value of the aspect ratios was also 100 or more).

Example 3
91 g of the CNF (I) dispersion, which is a hydrophilic nanofiber dispersion (of which CNF (I) amount is 10.0 g), 90 g of the PAO as a base oil, and 33 g of hexylene glycol as a compatibilizer. The mixture was sufficiently stirred at 25 ° C. to prepare a mixed solution.
Then, in the same environment and operation as in Example 1, water and hexylene glycol, which is a compatibilizing agent, are evaporated and removed from the mixed solution, cooled to room temperature (25 ° C.), and then homogenized using a three-roll mill. Processing was performed to obtain a grease (3) having a CNF (I) content of 10% by mass.
Of the CNT (I) contained in the obtained grease (3), the thickness (d) of 10 CNF (I) arbitrarily selected is 20 to 50 nm (the average value of the thickness (d) is The aspect ratio of these 10 CNF (I) s was 100 or more (the average value of the aspect ratios was also 100 or more).

Comparative Example 1
17 g (60 mmol) of stearic acid is dissolved in 80 g of the rapeseed oil as the base oil, and an aqueous solution in which 2.2 g (30 mmol) of calcium hydroxide is dissolved in 10 g of ion-exchanged water is added and heated to 100 ° C. to sufficiently react. Made progress.
After completion of the reaction, the mixture was cooled to room temperature (25 ° C.) and homogenized using a three-roll mill to obtain grease (4) containing calcium stearate.

Comparative Example 2
17 g (60 mmol) of stearic acid and 6.0 g (40 mmol) of azelaic acid are dissolved in 70 g of the rapeseed oil as the base oil, 4.4 g (57 mmol) of aluminum hydroxide is added, and the mixture is heated to 100 ° C. to react. It was fully advanced.
After completion of the reaction, the reaction mixture was cooled to room temperature (25 ° C.) and homogenized using a three-roll mill to obtain grease (5) containing aluminum stearate and aluminum azelate.

Comparative Example 3
45 g of cellulose powder (particle size 38 μm, passing through 400 mesh, manufactured by Wako Pure Chemical Industries, Ltd.) and 55 g of rapeseed oil were mixed and sufficiently stirred at 25 ° C. in the same manner as in Example 1. And the homogenization process was performed using the 3 roll mill, and the grease (6) whose content of a cellulose powder is 45 mass% was obtained.
In addition, floating of particles larger than the oil film thickness was observed on the surface of the obtained grease (6).

  About grease (1)-(6) obtained by the Example and the comparative example, while mixing the penetration and dropping point with the above-mentioned method, the following tests were done. These results are shown in Table 1.

[Heat resistance test]
Of the greases (1) to (6) obtained in the examples and comparative examples, the test was performed on grease having a dropping point of 150 ° C. or higher.
On the iron plate, the target grease was applied to form a coating film having a thickness of 2 mm. And the iron plate was heated to 150 degreeC, and the time until the said coating film hardened | cured with a heat | fever and a penetration degree became 200 or less or 350 or more was measured. It can be said that the longer the time, the better the heat resistance.

[Washing water resistance test]
Using the water at 38 ° C., the mass of the grease washed away with respect to 100% by mass of the grease before the test was measured by a method based on the water washing durability test method of JIS K2220: 2013.
It can be said that the larger the mass, the more excellent the detergency with water.

It can be seen that the greases (1) to (3) prepared in Examples 1 to 3 are excellent in heat resistance and low in water washing resistance, and thus can be easily washed with water.
On the other hand, the greases (4) to (5) prepared in Comparative Examples 1 and 2 have high water wash resistance and are considered difficult to wash with water. Moreover, it can be said from the results of the dropping point and the heat resistance test that the greases (4) to (5) are inferior in heat resistance to the greases (1) to (3).
In addition, although the grease (6) prepared in Comparative Example 3 uses cellulose powder as a thickener, a large amount of cellulose powder as much as 40% by mass is used in order to make the blending consistency comparable to other greases. The formulation was necessary. In the grease (6) of Comparative Example 3, a large amount of cellulose powder as much as 40% by mass aggregates to form “dama”, and large particles float on the surface of the grease (6), and the cellulose powder is uniform. It was difficult to say that they were dispersed. Therefore, it is considered that the grease (6) has poor wear resistance. Further, since a phenomenon of scorching and hardening during the measurement of the dropping point of the grease (6) was observed, the heat resistance test and the water resistance test for water washing were not performed on the grease (6).

Claims (12)

  A grease containing a base oil and hydrophilic nanofibers having a thickness (d) of 0.01 to 500 nm.   The grease according to claim 1, wherein the base oil contains one or more selected from vegetable oil, animal oil, synthetic oil, fatty acid ester, and liquid paraffin.   The grease according to claim 1 or 2, wherein the content of the hydrophilic nanofiber is 0.1 to 20% by mass based on the total amount of the grease.   The grease according to claim 1, wherein the hydrophilic nanofiber has an aspect ratio of 5 or more.   The grease according to any one of claims 1 to 4, wherein the hydrophilic nanofiber includes one or more polysaccharides selected from cellulose, carboxymethylcellulose, chitin, and chitosan.   A grease obtained by mixing hydrophilic nanofibers having a thickness (d ') of 0.01 to 500 nm and a base oil.   An aqueous dispersion obtained by blending hydrophilic nanofibers having a thickness (d ′) of 0.01 to 500 nm in water, a base oil, and a compatibilizer are mixed to prepare a mixed solution, and then the mixing is performed. The grease according to claim 6, which is obtained by removing water and the compatibilizing agent from the liquid.   The mass of grease washed away with water measured by a test method based on the water wash durability test method of JIS K2220: 2013 using water at 38 ° C. is 20 masses with respect to 100 parts by mass of grease before the test. The grease according to any one of claims 1 to 7, wherein the grease is at least part.   A mechanical part using the grease according to claim 1.   The use method of grease which uses the grease as described in any one of Claims 1-8 for lubrication of the mechanism components of a food machine. The manufacturing method of grease which has the following process (1)-(2).
Step (1): An aqueous dispersion obtained by blending hydrophilic nanofibers having a thickness (d ′) of 0.01 to 500 nm in water, a base oil, and a compatibilizer are mixed to prepare a mixed solution. Process.
Step (2): A step of removing water and the compatibilizer from the mixed solution.   The method for producing grease according to claim 11, wherein the compatibilizer is an alcohol.