阅读说明：本技术 一种食品级润滑脂及其应用 (Food-grade lubricating grease and application thereof ) 是由 钱善华 巩龙飞 王韦 倪自丰 唐磊 于 2020-12-10 设计创作，主要内容包括：本发明公开了一种食品级润滑脂及其应用,属于润滑脂技术领域。所述食品级润滑脂包括食品级润滑脂基础脂和食品级添加剂,所述食品级添加剂占食品级润滑脂基础脂质量的0.5％～5.0％,其中,所述食品级润滑脂基础脂以质量分数计,包括食品级白油75％-85％,硬脂酸6％-16％,苯甲酸2.0％-3.0％,异丙醇铝5％-8.7％；所述食品级添加剂包括纳米聚四氟乙烯和碳酸钙的组合物或纳米聚四氟乙烯和食品级滑石粉的组合物。本发明中的食品级润滑脂具有良好的抗磨减摩特性,可用于食品生产行业以及家用食品电器中,有效地提高设备的使用寿命以及食品级润滑脂的使用寿命,同时对食品安全性具有一定的保障。(The invention discloses food-grade lubricating grease and application thereof, and belongs to the technical field of lubricating grease. The food-grade lubricating grease comprises food-grade lubricating grease base grease and food-grade additives, wherein the food-grade additives account for 0.5-5.0% of the mass of the food-grade lubricating grease base grease, and the food-grade lubricating grease base grease comprises, by mass, 75-85% of food-grade white oil, 6-16% of stearic acid, 2.0-3.0% of benzoic acid and 5-8.7% of aluminum isopropoxide; the food-grade additive comprises a composition of nano polytetrafluoroethylene and calcium carbonate or a composition of nano polytetrafluoroethylene and food-grade talcum powder. The food-grade lubricating grease has good wear-resistant and friction-reducing characteristics, can be used in food production industry and household food appliances, effectively prolongs the service life of equipment and the service life of the food-grade lubricating grease, and has certain guarantee on food safety.)

1. The food-grade lubricating grease is characterized by comprising a food-grade lubricating grease base grease and a food-grade additive, wherein the food-grade additive accounts for 0.5-5.0% of the mass of the food-grade lubricating grease base grease, and the food-grade lubricating grease base grease comprises, by mass, 75-85% of food-grade white oil, 6-16% of stearic acid, 2.0-3.0% of benzoic acid and 5-8.7% of aluminum isopropoxide; the food-grade additive comprises a composition of nano polytetrafluoroethylene and calcium carbonate or a composition of nano polytetrafluoroethylene and food-grade talcum powder.

2. The food-grade grease of claim 1, wherein the food-grade additive is a combination of nano-polytetrafluoroethylene and calcium carbonate.

3. The food-grade lubricating grease of claim 2, wherein the mass ratio of the nano polytetrafluoroethylene to the calcium carbonate in the composition is 1-4: 1-4.

4. A food grade grease according to any one of claims 1 to 3, wherein the food grade grease base comprises, in mass percent: 78-82% of food-grade white oil, 10-12% of stearic acid, 2.0-3.0% of benzoic acid and 6-7% of aluminum isopropoxide.

5. The food-grade lubricating grease of any one of claims 1 to 3, wherein the food-grade lubricating grease comprises a food-grade lubricating grease base grease and food-grade additives, and the food-grade additives comprise nano polytetrafluoroethylene accounting for 1.0% of the mass of the food-grade lubricating grease base grease and calcium carbonate accounting for 4.0%, wherein the food-grade lubricating grease base grease comprises, by mass, 80% of food-grade white oil, 10.95% of stearic acid, 2.35% of benzoic acid and 6.7% of aluminum isopropoxide.

6. A food-grade grease according to any one of claims 1 to 3, wherein the food-grade grease is prepared by the following method:

(1) mixing food-grade white oil, aluminum isopropoxide and benzoic acid, and heating to completely dissolve the mixture;

(2) adding stearic acid into the mixture dissolved in the step (1), and stirring to dissolve the stearic acid;

(3) adding water into the product obtained in the step (2) for saponification, dehydrating after saponification, then adding food-grade white oil, and heating and refining;

(4) adding food-grade white oil into the product obtained after the heating and refining in the step (3), cooling and grinding to obtain food-grade lubricating grease base grease;

(5) and (4) taking the food-grade lubricating grease base grease and the food-grade additive obtained in the step (4), stirring and mixing, and then carrying out ultrasonic treatment and grinding to obtain the food-grade lubricating grease.

7. The food grade grease of claim 6, wherein the saponification temperature in step (3) is 110-115 ℃ and the saponification time is 20-40 min.

8. The food-grade grease of claim 6, wherein the temperature of the temperature-raising refining is 200-210 ℃ for 20-40 min.

9. A lubricant comprising the food grade grease of any one of claims 1 to 8.

10. Use of the food grade grease according to any one of claims 1 to 8 or the lubricating material according to claim 9 in a food machinery apparatus.

Technical Field

The invention relates to food-grade lubricating grease and application thereof, and belongs to the technical field of lubricating grease additives.

Background

In recent years, food safety problems have been frequent, and more food safety events have been feared by people, and the food safety problems have also become a focus of global attention. There are many factors affecting food safety, and among them, contamination caused by lubricating materials present on mechanical equipment used in food processing is one of the main causes of food safety problems. In the production and manufacturing process of food, food mechanical equipment is indispensable, lubrication is necessary for each mechanical device, and once the lubricating material leaks, the lubricating material is easily mixed into the food in the production and manufacturing process of the food, so that the food safety is damaged. To avoid this problem, food grade lubricating materials must be used in parts of the food packaging and production. The food-grade lubricating grease is one of compositions of food-grade lubricating materials and is used for lubricating, sealing and protecting mechanical equipment for food processing and packaging. Because working conditions such as heating, cooking and the like often occur in the food processing process, the food-grade lubricating grease not only has the characteristics of common lubricating grease, but also has good high-temperature resistance and water resistance, and is nontoxic and harmless.

At present, fewer food-grade lubricating grease products meeting the requirements are produced in China, and most products in the market are foreign products and are expensive. In the existing food-grade lubricating materials, most of vaseline occupies a large amount and has a high proportion, but the vaseline has weak friction-reducing and wear-resisting effects and poor high-temperature resistance, and cannot be applied to occasions of high-temperature cooking, such as soybean milk machines and the like. In order to solve the problem, some researchers propose that edible vegetable oil and fat or animal oil and fat can be used as a lubricating material of food machinery, and the effect of non-toxicity is expected to be achieved, but the harm is greater in doing so because animal and vegetable oil and fat such as lard and rapeseed oil go bad and go moldy after being heated under a high-temperature and high-humidity environment, bacteria and the like which pollute food are easy to breed, and the long-term use of the edible vegetable oil and fat or animal oil and fat can bring adverse effects to consumers. Therefore, it is necessary to develop a special food grade grease research.

The composite aluminum-based lubricating grease is used in food-grade lubricating grease due to excellent characteristics of high temperature resistance, water resistance and the like. Some scholars use tripolymer aluminum as a thickening agent, but the tripolymer aluminum is an oil solvent, is mostly an industrial oil solvent, and can pollute food-grade white oil, so that the safety cannot be guaranteed. Along with the improvement of national food safety consciousness and the improvement of legal regulations, the application of the food-grade lubricating grease is more and more extensive, so that the food-grade lubricating grease with low harm and long service life is obtained by improving the preparation process of the food-grade lubricating grease, the aim of saving energy is fulfilled, and the food safety feeling of people is greatly met.

In addition, the service life of the lubricating grease greatly depends on the performance of the additive, most of the lubricating grease additives adopt carbon-containing nano materials, nano metal oxides and the like, but the materials are harmful to human bodies and are not suitable for food-grade lubricating grease. The food additive is used as an additive, is widely applied to the food industry, has the characteristics of no toxicity and no harm, and has a great development space when being used as an additive of food-grade lubricating grease. The food grade talcum powder belongs to food grade additives and is widely applied to flow aid and demoulding in food. The application of the additive in food-grade lubricating grease can ensure the safety.

Disclosure of Invention

Aiming at the problems, the invention provides the food-grade lubricating grease and the preparation method thereof, the food-grade lubricating grease provided by the invention can be used in the food production industry and household food appliances, has good wear-resistant and antifriction properties, can effectively improve the transmission efficiency and the service life of transmission modes such as gears, guide rails, chains, bearings and the like in food equipment, is expected to become food-grade lubricating grease with excellent performance, excellent price and excellent service life, is applied to the food production industry, and achieves the aims of reducing the food safety problem and saving energy.

The first purpose of the invention is to provide a food-grade lubricating grease, which comprises a food-grade lubricating grease base grease and a food-grade additive, wherein the food-grade additive accounts for 0.5-5.0% of the mass of the food-grade lubricating grease base grease, and the food-grade lubricating grease base grease comprises, by mass, 75-85% of food-grade white oil, 6-16% of stearic acid, 2.0-3.0% of benzoic acid and 5-8.7% of aluminum isopropoxide; the food-grade additive comprises a composition of nano polytetrafluoroethylene and calcium carbonate or a composition of nano polytetrafluoroethylene and food-grade talcum powder.

In one embodiment of the present invention, the food grade additive is preferably a combination of nano polytetrafluoroethylene and calcium carbonate.

In one embodiment of the invention, the ratio of the nano polytetrafluoroethylene to the calcium carbonate in the composition is 1-4: 1-4, preferably 1:4, by mass ratio.

In one embodiment of the present invention, the food grade grease base grease preferably comprises, in mass fraction: 78-82% of food-grade white oil, 10-12% of stearic acid, 2.0-3.0% of benzoic acid and 6-7% of aluminum isopropoxide.

In one embodiment of the invention, the food-grade grease comprises food-grade grease base grease and food-grade additives, wherein the food-grade additives comprise nano polytetrafluoroethylene with the mass of 1.0% of that of the food-grade grease base grease and calcium carbonate with the mass of 4.0%, and the food-grade grease base grease comprises, by mass, 80% of food-grade white oil, 10.95% of stearic acid, 2.35% of benzoic acid and 6.7% of aluminum isopropoxide.

In one embodiment of the present invention, the food grade grease is prepared by the following method:

(1) mixing food-grade white oil, aluminum isopropoxide and benzoic acid, and heating to completely dissolve the mixture;

(2) adding stearic acid into the mixture dissolved in the step (1), and stirring to dissolve the stearic acid;

(3) adding water into the product obtained in the step (2) for saponification, dehydrating after saponification, then adding food-grade white oil, and heating and refining;

(4) adding food-grade white oil into the product obtained after the heating and refining in the step (3), cooling and grinding to obtain food-grade lubricating grease base grease;

(5) and (4) taking the food-grade lubricating grease base grease and the food-grade additive obtained in the step (4), stirring and mixing, and then carrying out ultrasonic treatment and grinding to obtain the food-grade lubricating grease.

In one embodiment of the invention, the food grade white oil in step (1) meets the following criteria: FDA 21CFR regulation in article 172.878, article 178.3620(a), article 178.3570, article 176.170, and pass NSF H1 level, 3H level authentication.

In one embodiment of the present invention, the heating temperature in step (1) is 95-110 ℃ and the heating time is 30-40 min.

In one embodiment of the invention, the kinematic viscosity (40 ℃) of the food grade white oil in step (1) is 170mm²/s。

In one embodiment of the present invention, the saponification temperature in step (3) is 110-115 deg.C, and the saponification time is 20-40 min.

In one embodiment of the invention, the amount of water added in step (3) is 1.0-1.5% of the mass of the food-grade grease base.

In one embodiment of the present invention, the dehydration in step (3) is performed at a high temperature of 150 ℃ and 160 ℃, and the dehydration is performed under the saponification condition, so that the saponified floc is evaporated until the saponified floc is broken into lumps.

In one embodiment of the present invention, the temperature of the temperature raising refining in step (3) is 200 ℃ to 210 ℃, and the time is 20-40 min.

In one embodiment of the present invention, the grinding in step (4) is performed by using a three-roll grinder, and the grinding is performed 2 to 5 times.

In one embodiment of the present invention, the amount of the food grade white oil used in step (1) is 50-55%, the amount of the food grade white oil used in step (3) is 20-25%, and the amount of the food grade white oil used in step (4) is 25-30%.

In one embodiment of the present invention, the amount of the food grade white oil used in step (1) is 50% of the total amount of the food grade white oil used in step (3), the amount of the food grade white oil used in step (4) is 25% of the total amount of the food grade white oil used in step (4).

In one embodiment of the present invention, the stirring time in step (5) is 5 to 30 min.

In one embodiment of the present invention, the ultrasonic treatment in step (5) is performed by vibrating in an ultrasonic cleaning machine for 10-20 min.

It is a second object of the present invention to provide a lubricating material comprising the above food grade grease.

A third object of the present invention is to provide the use of the above food grade grease or the above lubricating material in food machinery apparatus.

The invention has the beneficial effects that:

1. the food-grade lubricating grease adopts the food-grade white oil as the base oil, is obtained by taking the mineral oil as the base oil and carrying out the processes of deep chemical refining, edible alcohol extraction and the like, is suitable for lubricating processing equipment in food industries such as grain and oil processing, fruit and vegetable processing, dairy product processing, bread cutting machine and the like, is applied to food glazing, anti-sticking, defoaming, planing and sealing, can be used as a mold release agent for food such as macaroni, bread, biscuits, chocolates and the like, and can prolong the storage and preservation periods of wine, vinegar, fruits, vegetables and cans. Therefore, the food-grade white oil is used as the base oil of the food-grade lubricating grease, so that the safety of the lubricating grease can be ensured to a certain extent.

2. In the invention, the composition of nano polytetrafluoroethylene and calcium carbonate or the composition of nano polytetrafluoroethylene and food grade talcum powder is used as a food grade additive, at least two of the food grade talcum powder and calcium carbonate are used as additives, and different additives can form a synergistic effect to obviously reduce the friction coefficient of a ball disc friction pair, and under the optimal condition, the friction coefficient of the ball disc friction pair can be as low as 0.039, and the abrasion volume of a steel disc is only 0.37 multiplied by 10⁷μm³Compared with a single additive, the lubricating performance of the lubricant is obviously improved.

3. The food-grade lubricating grease disclosed by the invention has the advantages that the additives are food-grade talcum powder, nano polytetrafluoroethylene and calcium carbonate, and a small amount of the additives are harmless to food, so that the safety can be ensured.

4. The food-grade lubricating grease disclosed by the invention adopts the composite aluminum base as the thickening agent, and the composite aluminum base lubricating grease has the properties of high dropping point, high temperature resistance, good water resistance, rust resistance and the like, so that the food-grade lubricating grease is suitable for working conditions such as heating, cooking and the like which often occur in the food processing process in the food machinery industry.

Drawings

Figure 1 is a photograph of the food grade grease prepared in example 1.

FIG. 2 is a schematic diagram of an MFT-5000 friction wear tester.

Fig. 3 is a photograph of the food grade grease prepared in example 3.

Detailed Description

The invention will now be further illustrated by reference to specific examples, which are intended to be illustrative only and not to limit the scope of the invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

The following table shows the raw materials used in the practice of the present invention, but is not limited to the raw materials listed.

TABLE 1 raw materials

Example 1

(1) Firstly, adding 400g of food-grade white oil, 67g of aluminum isopropoxide and 23.5g of benzoic acid into a reaction kettle, heating to control the temperature to be within the range of 95-100 ℃, and stirring to completely dissolve the white oil;

(2) then adding 109.5g of stearic acid into the mixture dissolved in the step (1), and stirring for 30min to fully dissolve and react;

(3) and (3) then linearly spraying 11.8g of water into the product obtained in the step (2), saponifying at the temperature of 110-115 ℃ for 30min, heating to 160 ℃ for dehydration, and dehydrating for 20min to evaporate the saponified floccule water until the saponified floccule is dispersed into blocks. Then 200g of food-grade white oil is added into the mixture, and the mixture is heated to 200-210 ℃ for high-temperature refining for 30 min;

(4) finally, adding 200g of food-grade white oil into the product obtained after the heating and refining in the step (3) for quenching, stirring and cooling, and grinding for 3 times by using an S65 three-roll grinding machine to obtain food-grade lubricating grease base grease;

(5) 100g of food-grade lubricating grease base grease, nano polytetrafluoroethylene accounting for 5.0% of the mass fraction of the food-grade lubricating grease and food-grade talcum powder (the mass ratio of the nano polytetrafluoroethylene to the food-grade talcum powder is 1: 4) are put into a beaker, evenly stirred for 10min, vibrated for 10min in an ultrasonic cleaning machine, and ground for three times by a three-roll grinder to obtain the food-grade lubricating grease containing 5.0% of food-grade additives.

Fig. 1 is a photograph of the food-grade grease prepared in this example, and it can be seen from fig. 1 that the prepared food-grade grease is purer white, has no other impurities and no special odor, and the prepared food-grade grease has better viscosity.

Frictional wear performance test

The food grade greases of the above examples were tested for frictional wear performance using an MFT-5000 frictional wear tester (Rtec Instruments), a schematic diagram of which is shown in FIG. 2. The steel balls used in the experiments were made of GCr15, and the friction discs used in the experiments were made of 45 steel. Before the test, food-grade lubricating grease containing food-grade talcum powder with different mass fractions is uniformly coated on the surface of the disc. And setting experiment parameters and then carrying out an experiment.

The food grade grease prepared above was tested for frictional wear performance and the results are shown in table 2.

TABLE 2 Friction test results for the food grease prepared in example 1 (condition: 1.69Gpa,0.157m/s,75 ℃ C.)

As can be seen from Table 2, the simultaneous addition of food grade talc powder and nano polytetrafluoroethylene can significantly reduce the friction coefficient and reduce the wear loss. Compared with comparative example 1 and comparative example 2, the nano polytetrafluoroethylene and the food-grade talcum powder are independently added, and the effect of simultaneously adding the nano polytetrafluoroethylene and the food-grade talcum powder is better, especially better than that of the food-grade talcum powder. This is probably because, on the one hand, food grade talcum powder and nanometer polytetrafluoroethylene take place the chemical reaction between the friction pair, form the chemical reaction membrane to reduce the probability that the friction pair directly contacts, thereby reduce the coefficient of friction and reduce the volume of wearing and tearing. On the other hand, the nano polytetrafluoroethylene is a nano material and has extremely strong adsorbability, and in the friction process, the nano polytetrafluoroethylene can be adsorbed on the surface of a friction pair to form an adsorption film, so that friction and abrasion are reduced. In addition, the food grade talcum powder mainly consists of SiO₂And MgO. In the friction experiment, the friction disc is processed, and the surface roughness of the friction disc cannot be guaranteed to be absolutely smooth, so that the real contact area between the friction ball and the friction disc is small, high contact stress is borne in the friction process, the friction disc is easy to break in the experiment process, and gullies are generated on the surface of a grinding mark. So that a part of the talc powder (mainly SiO)₂) The gully generated on the surface of the grinding mark can be repaired in the friction process, and the gap between the friction pair is increasedThe contact area reduces the contact stress between the friction pairs, thereby achieving the effects of reducing friction and reducing abrasion. At the same time, a small amount of SiO₂It also acts as a micro-polish, reducing the coefficient of friction and wear volume.

Example 2

(1) - (4) Steps (1) to (4) in the same manner as in example 1;

different food-grade lubricating greases were prepared respectively by changing the mass ratios of the nano polytetrafluoroethylene and the food-grade talc powder in the food-grade additive in example 1 to 2:3, 3:2, and 4:1, with the total addition of 5%.

The food grade grease prepared was tested for frictional wear performance in the manner of example 1 and the results are shown in table 3. TABLE 3 test results of different proportions of nano-polytetrafluoroethylene and food grade talc for grease

(working condition: 1.69Gpa,0.157m/s,75 ℃ C.)

Example 3

(1) Firstly, adding 400g of food-grade white oil, 67g of aluminum isopropoxide and 23.5g of benzoic acid into a reaction kettle, heating to control the temperature to be within the range of 95-100 ℃, and stirring to completely dissolve the white oil;

(2) then adding 109.5g of stearic acid into the mixture dissolved in the step (1), and stirring for 30min to fully dissolve and react;

(3) and (3) then linearly spraying 11.8g of water into the product obtained in the step (2), saponifying at the temperature of 110-115 ℃ for 30min, heating to 160 ℃ for dehydration, and dehydrating for 20min to evaporate the saponified floccule water until the saponified floccule is dispersed into blocks. Then 200g of food-grade white oil is added into the mixture, and the mixture is heated to 200-210 ℃ for high-temperature refining for 30 min;

(4) finally, adding 200g of food-grade white oil into the product obtained after the heating and refining in the step (3) for quenching, stirring and cooling, and grinding for 3 times by using an S65 three-roll grinding machine to obtain food-grade lubricating grease base grease;

(5) putting 100g of food-grade lubricating grease base grease and nano polytetrafluoroethylene and calcium carbonate accounting for 5.0% of the food-grade lubricating base grease by mass into a beaker (the mass ratio of the food-grade lubricating grease base grease to the nano polytetrafluoroethylene to the calcium carbonate is 1: 4), uniformly stirring for 10min, then vibrating in an ultrasonic cleaning machine for 10min, and grinding for three times by a three-roll grinder to obtain the food-grade lubricating grease containing 1.0% of the nano polytetrafluoroethylene and 4% of the calcium carbonate food-grade additive; a photograph of the food grade grease prepared in this example is shown in figure 3.

The food grade grease prepared was tested for frictional wear performance in the manner of example 1 and the results are shown in table 4.

TABLE 4 results of friction experiments for food greases prepared with different amounts of food grade additives

As can be seen from Table 4, the simultaneous addition of the nano-polytetrafluoroethylene and the calcium carbonate can significantly reduce the friction coefficient and the abrasion loss. Compared with comparative example 1 and comparative example 3, the nano polytetrafluoroethylene and the calcium carbonate are added separately, the effect of adding the nano polytetrafluoroethylene and the calcium carbonate simultaneously is better, the friction coefficient is as low as 0.039, and the abrasion volume is only 0.37 multiplied by 10⁷μm³. The possible reason is that in the food-grade lubricating grease added with the two food-grade additive compound nano-particles, a part of the compound nano-particles are adsorbed on the surfaces of the friction pairs to separate the direct contact of the friction pairs, so that the effect of reducing friction and abrasion is achieved. Part of the compound nano particles and calcium oxide, ferric fluoride and the like generated by chemical reaction between the friction pair are trapped in a contact surface in the friction process, repair the worn surface and have the micro-polishing function, so that the friction and wear are reduced. In addition, the nano polytetrafluoroethylene has strong adsorbability and can be adsorbed on the surface of calcium carbonate to form compound additive particles, so that abrasive wear caused by edges and corners on cubic calcium carbonate can be avoided. The formed compound nano particles roll between the friction pairs and play the role of lubricating a rolling bearing on the interface of the friction pairsThus reducing friction and wear between the friction pair. Therefore, the nano polytetrafluoroethylene and calcium carbonate compounded nano particles have a good synergistic effect on improving the extreme pressure performance and the friction performance of the food-grade lubricating grease.

Example 4

(1) - (4) Steps (1) - (4) in the same manner as in example 3;

the mass ratio of the nano polytetrafluoroethylene to the calcium carbonate in the food-grade additive in example 3 was changed to 2: 3. 3: 2. 4:1, respectively preparing different food-grade lubricating grease with the same total adding amount.

The food grade grease prepared was tested for frictional wear performance in the manner of example 1 and the results are shown in table 5.

TABLE 5 test results of food-grade greases at different ratios of nano-polytetrafluoroethylene and calcium carbonate (working condition: 1.86GPa,0.209m/s,75 deg.C)

Example 5

(1) - (4) Steps (1) to (4) in the same manner as in example 1;

changing the content of the food-grade additive in the step (5) into 1.0 percent and 3.0 percent of the mass fraction of the food-grade lubricating base grease, wherein the mass ratio of the nano polytetrafluoroethylene to the food-grade talcum powder is 1:4, a food grade grease containing 1.0% and 3.0% of food grade additives was prepared as in example 1, except that the conditions were the same.

The food grade grease prepared was tested for frictional wear performance in the manner of example 1 and the results are shown in table 6.

TABLE 61.0% and 3.0% test results for food grade greases with food grade additives (condition: 1.69Gpa,0.157m/s,75 ℃ C.)

Comparative example 1

(1) - (4) Steps (1) to (4) in the same manner as in example 1;

the food grade additive in the step (5) is nano polytetrafluoroethylene with the mass fraction of 5.0 percent, and the rest conditions are the same as those in the example 1, so that the food grade lubricating grease containing 5.0 percent of nano polytetrafluoroethylene is prepared (the comparative example is the optimal example of independently adding the polytetrafluoroethylene).

The frictional wear performance is measured in table 7.

Comparative example 2

(1) - (4) Steps (1) to (4) in the same manner as in example 1;

the food-grade lubricating grease containing 1.0% of food-grade talcum powder is prepared under the same conditions as in example 1 (the comparative example is the optimal example for adding food-grade talcum powder separately).

The frictional wear performance is measured in table 7.

Comparative example 3

(1) - (4) Steps (1) to (4) in the same manner as in example 1;

the food grade additive in step (5) was calcium carbonate, and the remaining conditions were the same as in example 1, to prepare a food grade grease containing 5.0% calcium carbonate (this comparative example is the most preferred example of calcium carbonate addition alone).

The frictional wear performance is measured in table 7.

Comparative example 4

(1) - (4) Steps (1) to (4) in the same manner as in example 1;

the additive in step (5) is industrial grade talcum powder, and the rest conditions are the same as those in example 1, so that the food-grade lubricating grease containing 1.0% of the industrial grade talcum powder is prepared (the comparative example is the optimal example for independently adding the industrial grade talcum powder).

The frictional wear performance is measured in table 7.

Comparative example 5

(1) - (4) Steps (1) to (4) in the same manner as in example 1;

the food-grade additive in the step (5) is nano polytetrafluoroethylene, calcium carbonate and food-grade talcum powder, and the mass ratio of the nano polytetrafluoroethylene to the calcium carbonate to the food-grade talcum powder is 2: 2: 1, the same procedure as in example 1 was repeated except that food grade grease containing 5.0% of polytetrafluoroethylene, calcium carbonate and food grade talc was prepared (the comparative example is the most preferable example in which nano polytetrafluoroethylene, calcium carbonate and food grade talc were added simultaneously).

The food grade grease prepared was tested for frictional wear performance in the manner of example 1 and the results are shown in table 7.

It can be seen that the three additives are added simultaneously, the abrasion is serious, and the friction coefficient abrasion loss is larger than that of the base grease without any additive.

TABLE 7 test results for food greases prepared with the different additives of comparative examples 1 to 4 (working condition: 1.69Gpa,0.157m/s,75 ℃ C.)

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.