JPH0730351B2 - Antibacterial water-soluble cutting fluid - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a water-soluble cutting fluid used for cutting and grinding.

Conventional technology Water-soluble cutting fluids used for cutting or grinding metals include mineral oils, oils and fats, extreme pressure additives, surfactants, defoamers, metal anticorrosives, antioxidants, antiseptic / antibacterial agents, etc. Is contained as a composition component, and these are appropriately mixed according to the purpose. The water-soluble cutting fluid is usually diluted with water by 10 to 100 times, and the diluted solution is called a coolant. Performance that improves machinability for coolant (primary performance)
And performance (secondary performance) related to workability and the like are required. Of these, the secondary performance is good rust resistance,
It is not easily deteriorated and is easy to manage, it is harmless to the human body, there is little foaming, and there is no bad odor.

The water-soluble cutting fluid has different emphasis points depending on the purpose of use and conditions, but it is necessary to have the above-mentioned various properties in a well-balanced manner.

Problems to be Solved by the Invention As described above, the coolant has a problem that it is easily deteriorated by microorganisms, that is, it is easily decomposed, and it is a very important problem to prevent the deterioration of microorganisms. When the deterioration of the coolant progresses, the primary performance and the secondary performance deteriorate, and the work environment becomes worse due to the bad odor. In addition, if the frequency of oil replacement due to decay increases, it will be disadvantageous in terms of cost.
Further, if mold is generated in the coolant, not only the primary performance and the secondary performance are deteriorated but also pipe clogging of the circulation system is caused.

In addition to the above, elution of iron ions is another cause of coolant deterioration. When metal working is continued using a coolant, iron ions gradually elute into the coolant, which causes the coolant to turn reddish brown, and a reddish brown substance adheres to the surface of the workpiece to impair its appearance. For this reason,
There is also a problem that the worker has to work to remove the coloring substance. Further, the elution of iron also caused a problem of promoting the generation of rust on the processed product.

Conventionally, in order to prevent the microbial deterioration of the coolant as described above, various antibacterial substances have been added to the water-soluble cutting fluid, but it is difficult to prevent the deterioration of the coolant for a long time,
I was not in a satisfactory state.

In addition, various studies have been made on the composition of the water-soluble cutting fluid in order to prevent the elution of iron ions, but no effective means has been found.

The present invention has been made in order to solve the above problems, particularly water-soluble cutting characterized by less microbial deterioration, i.e., spoilage, less mold, and less elution of iron ions. An oil agent is provided.

Means for Solving the Problems As a result of earnest research by the present inventors, by adding a special diamine derivative to a water-soluble cutting fluid, it is possible to prevent microbial resistance without impairing various performances that the water-soluble cutting fluid should have. The inventors have found that the deterioration property can be improved and the elution of iron ions can be reduced, and the invention has been achieved.

That is, in the present invention, an alkyl-substituted diamine selected from the following group is added to a water-soluble cutting fluid.

All of the alkyl-substituted diamines shown below have remarkable effects.

N, N'-dimethyl-1,2-propanediamine N, N-dimethyl-2-methyl-1,3-propanediamine N-isopropyl-2-methyl-1,2-propanediamine N, N-diethyl-1 , 4-Pentanediamine N, N-dimethyl-2-butene-1,4-diamine.

Further, in the present invention, the alkyl-substituted diamine is preferably present in the coolant in a proportion of 0.001 to 1% by weight. When the concentration of the alkyl-substituted diamine is less than 0.001% by weight, the effect of the present invention is hardly obtained. On the other hand, when the concentration of the alkyl-substituted diamine exceeds 1% by weight, the effect is hardly improved as compared with the case of 1% by weight or less, which is economically disadvantageous.

The diamine derivative to be added may be added to either the stock solution of the water-soluble cutting fluid or the coolant.

In order to produce the water-soluble cutting fluid of the present invention, each component may be mixed according to a conventional method except for the addition of the diamine derivative, particularly mineral oil, fats and oils, extreme pressure additives, surfactants, antifoaming agents. The components such as the metal anticorrosive agent and the antioxidant can be arbitrarily selected from those conventionally used.

Examples Next, examples of the present invention will be described according to each table.
Needless to say, the present invention is not limited to these examples.

Table 1 shows the composition of each emulsion type water-soluble cutting oil, and Table 2 shows the composition of each soluble type water-soluble cutting oil. The unit of numerical values relating to the composition in the table is parts by weight.

(Note 1) The surfactants and preservatives shown in Table 1 are as follows.

Anionic surfactant: Sodium salt of petroleum sulfonate ... 60 parts by weight Triethanolamine salt of ricinoleic acid ... 40 parts by weight Mixture of nonionic surfactant: Nonylphenol, 2 mol of ethylene oxide additive ...
30 parts by weight Oleic acid ester of sorbitan (oleic acid: sorbitan = 1.5: 1)… 30 parts by weight Coconut oil fatty acid diethanolamide… 40 parts by weight Mixture Preservative: Hexahydro-1,3,5-tris (hydroxyethyl)- 1,3,5-Triazine (Note 2) Comparative Examples are all conventional water-soluble cutting fluids.

(Note) The surfactants and preservatives shown in Table 2 are as follows.

Anionic surfactant: amine salt of linear fatty acid (A ₈ ) having ₈ carbon atoms and linear fatty acid (A ₉ ) having 9 carbon atoms (A ₈ : A ₉ = 1: 1) ... 60 parts by weight Triethanolamine salt of ricinoleic acid… 40 parts by weight of mixture Nonionic surfactant: oleic acid ester (monoester) of polyethylene glycol (average molecular weight 1000)… 40 parts by weight of beef tallow fatty acid ester (diester) of polyethylene glycol (average molecular weight 400) )… 30 parts by weight Block polymer of ethylene oxide, propylene oxide (content of ethylene oxide 40 tw%, average molecular weight 2000)… 30 parts by weight of mixture Preservative: hexahydro-1,3,5-tris (hydroxyethyl) -1 , 3,5-Triazine Water-soluble cutting fluids having the compositions shown in Tables 1 and 2 were subjected to the following experiments to obtain water-soluble cutting fluids. The performance of the cutting fluid was evaluated.

(1) Preparation of sample liquid The water-soluble cutting fluids of Examples having the compositions shown in Tables 1 and 2 and the water-soluble cutting fluids of comparative degree were diluted with sterilized water, and the water-soluble cutting fluids of Table 1 were prepared. Is 3% by weight in sterile water
The water-soluble cutting oil in Table 2 was diluted so as to be contained in 2% by weight in sterilized water to prepare a sample solution.

(2) Microbial deterioration resistance test Add 400 ml of each sample liquid to a sterilized 500 ml flat bottom flask. To this, 1% by weight of a rotten emulsion (viable cell count 2 × 10 ⁸ cells / ml, fungal count 1 × 10 ⁴ cells / ml) as inoculum was added.
The cells were inoculated at intervals of 2 days, 4 days, 8 days, 13 days and 17 days, and cultured at 30 ° C. for 21 days with shaking (rotation speed was 200 rpm).
Then, on days 0, 3, 7, 14 and 21, a portion of each sample solution was aseptically sampled to measure the number of viable bacteria and fungi, pH measurement, appearance change and odor. It was observed whether or not. At the same time, the rust prevention performance was also observed.

The viable cell count was measured by a plate counting method using a normal agar medium. The number of fungi was measured by the plate counting method using a potato dextrose agar medium supplemented with antibiotics (chloramphenicol and tetracycline).

The rust preventive property was observed by the cast iron chip method.
That is, about 15 g of dry cut cast iron chips (FC-2
5, 8 to 12 mesh) was sampled in a Petri dish (inner diameter of about 60 mm), about 25 ml of the sample solution was added thereto, shaken well, and then allowed to stand for about 4 minutes. Next, the sample solution was removed by the tilting method, and the state of rust generated on the Petri dish was observed over time.

Tables 3 and 4 show the above results as measurement results by day.

First, it can be seen that, with respect to the change in appearance, almost no change is observed after 21 days in all of the examples, whereas in each of the comparative examples, the change is bad by 21 days.

Next, regarding the pH, it can be seen that the decrease in the pH value of the example is relatively small, whereas the decrease in the pH value of the comparative example is relatively large.

Regarding the viable cell count, the number of viable cells in the example was about 5 × 10 ⁴ to 5 × 10 ⁵ cells / ml after 21 days, whereas the number of cells in the comparative example was significantly increased to 1 × 10 ⁸ to 3 × 10 ⁸ cells / ml. I know that As for the number of fungi, the number of fungi in each of the examples was 10 / ml or less even after 21 days, whereas that of the comparative examples was 2 × 10 ⁴ to 3 ×.
It can be seen that the number is greatly increased to 10 ⁴ cells / ml.

Regarding the odor, in each of the examples, almost no odor is felt even after 21 days have passed, whereas in each of the comparative examples, a bad odor is produced by 21 days.

Further, regarding the rust preventive performance, it can be seen that in the Examples, only some of them are slightly rusted even after 21 days have passed, whereas all of the Comparative Examples are clearly rusted.

As described above, the results of Tables 3 and 4 show that the water-soluble cutting fluids of Examples are superior in microbial deterioration resistance to the conventional water-soluble cutting fluids of Comparative Examples.

(3) Iron ion elution preventing ability test 400 ml of the sample solution prepared by the method of (1) above and dry-cut cast iron chips (FC-25, 8 to 12 mesh)
40 g was put in a 500 ml Erlenmeyer flask, a cotton stopper was put, and the sample solution was deteriorated by shaking at 37 ° C. for 20 days (rotation speed was 150 rpm). After allowing to cool, the solution was filtered through a No. 5A filter paper to obtain a deteriorated liquid. The appearance change of the deteriorated liquid was observed and the iron ion concentration was measured. The results are shown in Table 5.

(Note 1) ◯ means no change, and x means reddish brown.

(Note 2) Measured by absorptiometry. The iron ion concentration of the new solution was 1 ppm in all samples.

The following can be seen from Table 5.

(1) Change in Appearance No change in appearance was observed in all of the examples, whereas all of the comparative examples turned reddish brown.

(2) Iron ion concentration In the examples, the concentration was 2 to 4 ppm (that is, a very small amount), whereas in the comparative example, the concentration was 145 to 260 ppm, which was a high concentration.

EFFECTS OF THE INVENTION As described above, the present invention has the effects of being less susceptible to deterioration by microorganisms, that is, less likely to rot, less likely to cause mold, and providing a water-soluble cutting fluid with less iron ion elution. Play.

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Claims (1)

[Claims] 1. A water-soluble cutting oil containing at least one substance selected from the group consisting of mineral oils, oiliness agents and extreme pressure additives and a surfactant, or a group consisting of a surfactant and an antirust additive. A water-soluble cutting fluid containing at least one substance selected from
To e) containing at least one alkyl-substituted diamine selected from the group e) to e). a) N, N'-dimethyl-1,2-propanediamine b) N, N-dimethyl-2-methyl-1,3-propanediamine c) N-isopropyl-2-methyl-1,2-propanediamine d ) N, N-Diethyl-1,4-pentanediamine e) N, N-Dimethyl-2-butene-1,4-diamine