JPS6397683A - Antifreezing composition - Google Patents

Abstract

PURPOSE:To obtain an antifreezing composition which has an excellent effect of depressing a freezing point at low temperatures on a concentration basis, produces an immediate effect, and is suitable for use as, e.g., a snow-melting agent, by mixing urea, calcium chloride, magnesium chloride, a lower apiphatic alcohol, and water as its essential components. CONSTITUTION:An objective antifreezing composition is obtained by mixing urea, calcium chloride, magnesium chloride, a lower apiphatic alcohol (e.g., methanol), and water as its essential components. The suitable amounts of these components are such that the weight ratio of calcium chloride to magnesium chloride is 5:4-6:4, the amount of the lower apiphatic alcohol is at least 3%, and the amount of urea is at least 1/3 of the sum of calcium chloride and magnesium chloride. This antifreezing composition causes little salt damage and has little corrosiveness; therefore, it can be suitably used as an antifreezing agent, a deicer, a refrigerant, brine, etc., as well as a snow-melting agent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) Undeveloped IJI can be treated especially with fast-acting snow-melting agents or ice-melting agents, accumulation inhibitors, anti-icing agents, anti-icing agents, or refrigerants or ice-melting agents. This invention relates to an antifreeze composition useful as brine, etc.

(Prior Art) Snow and ice cause significant obstacles to transportation and people's lives in winter. For this reason, the conventional and widely used countermeasure is salt (
This involves spraying freezing point suppressants such as rock salt), halogens such as calcium chloride, urea or ethylene glycol on the snow or water surface. In addition, in areas where land and water are rich,
Water is also being discharged into direct channels. Furthermore, +li
lTo prevent the shaft from slipping, use spiked tires or chains! An has been implemented.

Among these methods, urea is superior in that it has no phytotoxicity to plants and is less corrosive to steel.
Since its ability to lower the freezing point per concentration is small, it is ineffective unless it is sprayed in large numbers, and it also has the disadvantage of breeding weeds in the area where it is sprayed. In addition, ethylene glycol is ideal in terms of non-corrosion and low toxicity to metals, but it is expensive and can only be used in special places such as airports, and in order to be effective at -20°C, Requires concentrations as high as 35%. In addition, groundwater dispersion not only requires a large amount of money to install and maintain new equipment, but is also not versatile because it requires an abundance of ground water.Furthermore, spiked tires can significantly damage the road surface. Not only that, but the dust that is kicked up causes dust pollution in roadside areas.Finally, installing chains is not only troublesome to install, but is even more dangerous than regular tires on frozen roads.

Therefore, it is practical to spray salt or calcium chloride, but these not only cause phytotoxicity to plants, but also
Those 1'i! A disadvantage is that elementary ions tend to corrode steel road transportation facilities such as bridges, guardrails, traffic signs, and manholes. In particular, the corrosivity of these salts containing chlorine ions becomes extremely high at around 3%, so the sprayed salts are diluted with melting water or melted ice, forming droplets that adhere to the underside of vehicles and road equipment. It is a problem that cannot be overlooked if these cause spot corrosion or if the salt solution penetrates into the concrete structure and corrodes the steel frame or reinforced structure. In addition, the viscosity of calcium chloride Kasa salts increases at high concentrations, causing slippage P? ! Although it tends to lower the friction coefficient, this drawback cannot be ignored in practice.

(Objective of the Invention) In view of the above circumstances, it is important for the present invention to provide a fast-acting freezing point depressant that has excellent freezing point depressing ability per concentration, especially at low temperatures, and has relatively low salt damage and corrosivity. A secondary object of the present invention is to provide an aqueous antifreeze composition useful as a refrigerant or a prine.

(Background of the Invention) Based on the above objectives, the present inventor has attempted various experiments and considerations, and as a result, has reached the following conclusion.

Φ　From the standpoint of practicality such as efficacy and price, 1 table salt.

Alkali or alkaline earth metal chlorides such as calcium chloride and magnesium chloride are the best.

Among the above chlorides, monosodium salt is superior in terms of cost and non-deliquescent properties, but it is inferior to freezing point lowering blades, so it is ineffective unless sprayed in large quantities, and it also causes the greatest phytotoxicity to plants.

Q) Comparing the remaining calcium 41ide and magnesium chloride, magnesium chloride is superior in terms of freezing point reduction per concentration. However, the freezing point
It is not as good as the former in terms of the low value of oint).

(4) The cold in Japan is mild compared to the eastern United States, which has a similar geographical relationship, and even in the Hokkaido region, the minimum temperature rarely drops below -20°C. It is sufficient to set the freezing point to around -20'C as the ability of the system.In fact, the freezing point of a 16% C aqueous solution of magnesium chloride is -19.
Since it is 9°C, it should roughly match the design value above.

lΦ As taught in Japanese Patent Publication No. 40-14508, the addition of urea can considerably reduce the chemical damage and corrosive effects of chlorine ions.
The method of dissolving urea in an aqueous solution of monohydric or dihydric alcohol having 1 to 4 carbon atoms, as disclosed in the above issue, has a low solubility of urea in alcohol (even the highest level of methanol is about 18%/room temperature).
The freezing point lowering effect of the alcohols or urea cannot be fully exerted.Alcohols are expensive and may be monohydric alcohols. , it is excellent as a non-corrosive, fast-acting freezing point depressant; etc.) The corrosivity of magnesium chloride to steel is somewhat greater than that of calcium chloride.

(7) Urea lacks the ability to supplement or completely enhance the freezing point lowering effect of chloride.

! ■ In order to expect immediate effect as an ice or snow melting agent, it is best to spray it in liquid form.

(Even when used as a brine, the specific heat increases as the concentration increases, so in order to increase heat transfer efficiency, it is desirable to have freeze resistance at a relatively low concentration.

Based on the above knowledge and 'IG facts': Liquid snow melting and ice melting agents include calcium chloride, magnesium chloride, urea,
It consists of a five-component system of lower aliphatic alcohol and water, as well as calcium chloride.

The problem to be solved is to reduce the concentration of magnesium chloride and lower aliphatic alcohol as much as possible, and to create an aqueous composition that can withstand temperature extremes of at least -20° C. in the form of a solution with as low a concentration as possible. Furthermore, since urea has a poor effect of assisting or enhancing the freezing point lowering effect of chloride, its use in high concentrations not only increases the total amount used, but also has the disadvantage of encouraging the growth of weeds. Therefore, it is desirable that the concentration of one bottle of urea is as low as possible.

(Means for achieving +1) Therefore, in order to solve the above problem, the originator 1N+ uses a freezing room whose temperature is set in advance at -20 to -21"C, and uses calcium chloride and/or magnesium chloride, urea and When freeze resistance tests were conducted on a number of compositions consisting of three to five component systems consisting of water and/or lower aliphatic monohydric alcohols,
We found the following facts.

(j) The combined use of calcium chloride and magnesium chloride synergistically improves the freezing resistance of the composition.

<b) The freezing resistance of the composition is significantly improved by the addition of a low concentration of lower aliphatic monohydric alcohol, in other words, the addition of lower aliphatic monohydric alcohol improves
Capable of significantly reducing the concentration of calcium monide and magnesium chloride.

The present invention is based on the above findings, and its gist is an aqueous composition containing urea, calcium chloride, magnesium chloride, lower aliphatic alcohol, and water as essential components. Exists in antifreeze compositions.

As is well known, Raoult's law applies to non-electrolytes such as urea and aliphatic monohydric alcohols, so substance 1
It is predicted that the freezing point will decrease by -186°C for each molar concentration, but this law does not apply to strong electrolytes such as calcium chloride and magnesium chloride. In the coexisting systems of the present invention, it is impossible to find a certain correlation between composition and freezing point depression, and the reason why the freezing resistance curve shown in attached Figure 1 shows a complicated unevenness is precisely because of this. This is a simple illustration of that. stop,
As shown in the attached Figure 2, f! ! Calcified magnesium, urea, methanol, and ethanol each have a content of 21.3% (actual measurement).

16. It shows a freezing temperature of =20°C at 1% (same left), 64.5% (theoretical), 32% (same left) and 49.5% concentrations (same left), but experimental results show that 10% methanol and 7% urea, 1! to give 1 freeze resistance at -20°C. The sum of the concentrations of calcium chloride and magnesium chloride should be at least 9%. Calcium chloride is about -5°C, magnesium chloride is about -7.2°C, and urea is about -2.7°C.
, −5,1”O for methanol and about −5,1”O for ethanol
Since this corresponds to 3.5° C., the synergistic effect of each component is obvious.

Here is the experiment that led to the present invention! Describe the facts.

(Experiment details) Anti-freezing test (see Tables 1 to 4) ■ Samples Calcium chloride, magnesium chloride, urea and methanol (all first grade reagents) Dissolve in 10% methanol water (medium) and put in a beaker, -2
After leaving it in a freezer kept at 0 to -21°C for 12 hours or more, take it out and check the frozen state.

〔Judgment criteria】

Complete freezing: Firmly frozen (indicated by an X in Figures 2 and 3).

Sherbet: The whole forms sherbet-like ice crystals (same as above).

When kneaded by hand, some or most of it forms sherbet-like crystals (
).

Slight freezing: A few ice crystals were observed on the surface (indicated by Δ in Figures 2 and 3).

Antifreeze: No ice crystals observed at all (indicated by O in Figures 2 and 3).

(Left below) Table 11 (methanol concentration 10%, urea 7%) (purchased
Taki-) gB: not frozen, *: slightly frozen, half: half-frozen, sha: frozen like a sherbet (same for Tables 2 to 4).

Table 2 (methanol concentration 5%, urea 7%) Table 3 (methanol e110%, urea 5%) Table 154 (Control test) As is clear, the thing that seems to have the most influence on freezing point depressing properties is the ratio of calcium chloride to magnesium chloride in the composition.

The second is the concentration of methanol and urea in the medium. The total ratio of both calcium chloride and magnesium chloride in the composition to avoid hand-kneading or sherbet-1 conditions that pose a risk of hydroplaying if the drawing temperature limit is set at 120 degrees Celsius or higher. is required to be at least 9% (see Table 1) when the tanol content in the All medium is 8%, and at least about 13% (see Table WS2) when it is approximately 4%. Common sense suggests that of the two, the higher the J4 ratio of magnesium chloride, which has a higher ability to lower the freezing point per duram, the better the freeze resistance, but the total ratio of both should be at least 11%. Surprisingly, if the ratio of both is 10=1 to 5:6, the composition ratio is concentrated when the ψ ratio of calcium chloride is high or the ratio is slightly magnesium chloride. There is.

Meta/-le alone is 120 degrees even at 10% e degree.
Cannot withstand temperature (see table 4 and cause 3),
However, their coexistence is useful in increasing freeze resistance, and as the concentration of methanol decreases, the drawing method limit line recedes significantly (see Tables 1 and 2 and Figures 1 and 2). )0 From the purpose of the invention, it is desirable that methanol has a value of 14, but since methanol has some toxicity and is flammable, if freezing resistance of -20℃ or higher is desired, it is generally 10%, as well as in the mountainous regions of Honshu.
In regions where freezing resistance of less than 20"O is sufficient, about 5% may be appropriate.However, in actual distribution form it is important to keep the bulk as low as possible, so it is recommended to dilute it appropriately before use. Since it is approved by the government, it is usually blended at a higher concentration in packaging for distribution.

The effect of urea on freezing resistance is relatively small, and adding 20% of urea to 25% methanol wood can give it a frost resistance of -20°C (see Table 4).
As is clear from the comparison between the table and Table 3, only 2% (
Even a difference in urine JIFf of 7% and 5% has the effect of increasing the sum of the threshold concentrations of calcium chloride and magnesium chloride by about 2%. Moreover, urea is harmless.

In addition, it has the effect of suppressing chemical damage and metal corrosion caused by chlorioin, so its blending is useful for the composition of the invention. It is preferable that the blending amount is equal to or larger than the total amount of calcium chloride and magnesium chloride.

The total concentration of calcium chloride, magnesium chloride, urea and methanol naturally affects freeze resistance.

As a result of experiments, it was found that this concentration needs to be at least 24% in order to expect freezing resistance above -20°C. However, it is interesting to note that this limit value does not show a strong correlation with the composition. The minimum drawing method density sum in is 24.4~27.1:24; 24.3~
A variation of 26.2 was observed, which suggests the existence of a subtle interaction among the four components (see also the unevenness of the drawing method limit line in Figures 2 and 3), and also suggests that the optimum composition cannot be determined. This also suggests that exclusively experimental methods are essential. However, in view of the experimental results to date, it appears that the optimal composition that has the lowest salt concentration and exhibits freezing resistance below -20'O'' is the following composition.

5 iqr-s 1 (button trouble) 1 hair clip or also 5z methanol if the concentration of methanol is reduced
The composition of both [μ2ヱj and above seems to be optimal. Therefore, in order to obtain a stock solution for distribution, it is preferable to appropriately increase the amount of components other than water so that the diluted product has the above-mentioned composition.The amount of diluted water can be calculated using a simple equation.

[Others] Each component constituting the composition of the present invention does not need to be a refined product.In the snow melting Φ ice melting agent, which is the main use of the composition of the present invention, the most important thing is that it is cheap. It is practical to use various chemical industry by-products and crude products. For example, calcium chloride can be obtained by using crude calcium chloride containing a small amount of salt, which is a by-product of the Tsurubei process, or by adding lime to bittern. In addition, magnesium chloride can be replaced with natural carnalite or artificial carnalite or bittern potassium salt obtained from bittern. Furthermore, methanol.

Although it can be substituted by a lower aliphatic alcohol such as ethanol, n-propanol, isopropanol or a lower aliphatic dihydric alcohol such as ethylene glycol, diethylene glycol or propylene glycol.
In terms of illumination, it is necessary to use it at a higher concentration than methanol, and it is also disadvantageous compared to methanol in terms of price.

Since the composition according to the present invention I11 itself exhibits a neutral to slightly alkaline pH of about 7.5 to 8.0, its corrosiveness to metal products is very small, and is less corrosive than tap water. However, if necessary, borax, phosphates, nitrites, silicates, chromates, tungstates, organic carboxylates, water-soluble organic amines, surfactants, hexamethylenetetramine, nitrophthalates, In addition to water-soluble proteins, known anticorrosive agents can be added. In addition, as the 11 base of powder 1 (ik), it may be colored with a harmless dye such as methyl orange, tsukusin, fluoroscein, malachite green, ultramarine, or stilbene fluorescent dye, and if necessary, phosphates,
Buffers such as borax and/or urea stabilizers such as dicyandiamide may be included.

The composition of the present invention may optionally contain thickeners such as starch, dexi-phosphorus, vegetable gums, carboxymethyl cellulose, methyl cellulose, and hydroxyethyl cellulose, modified calcium carbonate, rock powder, pumice powder, slag powder, and the like. Friction enhancers may be included. Compositions containing these thickeners and/or friction enhancers are not suitable for spraying on roads or runways, but are suitable for spraying on outdoor stairs, handrails,
・1 (By applying it to the surfaces of shafts, aircraft windows and mirrors, etc., it can prevent snow accumulation and icing).

As mentioned above, the composition of the present invention is preferably formulated in the form of a concentrated liquid, and can be applied directly or diluted to snow surfaces, water surfaces, or surfaces where snowfall or freezing is expected, runway surfaces, stairs, and heavy parking. The product of the present invention, which is sprayed on surfaces such as roads, etc., has immediate effect because it is in liquid form, and has almost no risk of drying out because it has deliquescent properties. Since it maintains its effectiveness and does not have the risk of drying and scattering like common salt, it is suitable not only for rapid snow melting or ice melting, but also for preventing freezing.

(Example) Hereinafter, an example of embodying the invention will be described with reference to an example and an application example. However, this example is for illustrative purposes only, and is not meant to limit the idea of the invention.

Example urea 28 urea (same below), calcium chloride hexahydrate 3
965 parts, 34.2 parts of magnesium chloride, 1 part of fluoroscein, 33.6 parts of methanol, and 63.7 ill of wood.
By adding and thoroughly mixing and dissolving in a stirring tank,
200 parts of intensely colored product were obtained. By diluting this solution to 4 times its volume with water, a spray solution for melting snow and ice that is resistant to temperatures above -20°C is obtained. A water truck can be used for spraying.Additionally, adding about 1 part of dextrin to this stock solution and applying it to exposed stairs in factories or scaffolding boards at construction sites will prevent falls due to freezing. It can prevent snow from accumulating on the roof of houses in areas with heavy snowfall, and it can also be used as brine itself as the above solution has almost no corrosive properties. Useful.

Application Example FIG. 4 is a schematic perspective view showing an example in which the composition of the present invention is used to prevent snow on a roof.

In this example, a pipe 0 with a large number of orifices (4, 4--) is installed horizontally along the ridge of a house (1), and the end of the chain pipe is connected to the ground (E>) through a pump ■. The snow melting agent of the present invention (T) is placed in the tank (■).When the main switch (■) is turned on during snowfall or before snowfall, the timer switch (■) operates and operates the pump (■) at predetermined time intervals, thereby melting snow. The snow melting agent (T) is sprayed in the form of a mist from the orifice ■, and the falling snow melting agent covers the entire roof in a film, so that the accumulated snow falls from the roof due to its own weight.The snow melting agent used for this purpose is , those with high viscosity containing thickeners are preferable.

Since the device of this example requires only a low m@ ratio and has low operating costs, it brings much good news to residents in areas with heavy snowfall who have trouble removing snow from their roofs.

(Effects of the Invention) As explained below, the present invention provides a quick-acting freezing point depressing agent and a liquid that have excellent water point depressing ability per concentration, especially at low temperatures, and are comparatively less salt-damaged and corrosive. Since it can provide a liquid antifreeze composition useful as a refrigerant or brine, it has a large value of 4 for both consumer and industrial purposes.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the concentration of tU/calcium chloride, pgnesium chloride, urea, methanol, and ethanol and the freezing point, and FIGS. A trigonometric graph showing the relationship between the composition of the five-component system of calcium chloride, magnesium chloride, urea, methanol, and water and the freezing property at -20°C (the explanations for each figure above are given using numbers in the figure),
FIG. 4 is a schematic perspective view showing seven examples in which the composition of the present invention was used to prevent snow accumulation on a roof. The meanings of the symbols in Fig. 4 are as follows: knee 1: house, 2: 1 ridge, 3 nisplay pipe, 4: 3 orifice, 5: pump, 6: snow melting agent tank, 7: main switch, 8: Timer switch

Claims (7)

[Claims] (1) An antifreeze composition characterized in that it is an aqueous composition containing urea, calcium chloride, magnesium chloride, lower aliphatic alcohol, and water as essential components. (2) The composition according to claim 1, wherein the weight ratio of calcium chloride to magnesium chloride in the composition is 5:4 to 6:4. (3) The composition according to claim 1, wherein the lower aliphatic alcohol is methanol. (4) The composition according to claim 3, wherein the amount of methanol in the composition is 3% or more. (5) The composition according to claim 1, wherein the amount of urea in the composition is 1/3 or more of the total amount of calcium chloride and magnesium chloride. (6) The composition includes an anticorrosive agent, a pH buffer, a stabilizer, a pigment,
A composition according to any one of claims 1 to 3 containing additives such as friction enhancers. (7) The composition according to any one of claims 1 to 6, wherein the composition is in a concentrated liquid form.