JP2000026843A - Snow-or ice-melting agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a snow- or ice-melting agent which prevents rolling of the agent caused by wind and slope of the road at an earlier stage after application, improves the stability against snow and ice surfaces and makes it possible to applying the agent uniformly on the road by compression-molding a water soluble salt into pillar particles having a specific length and a specific major axis. SOLUTION: A water soluble salt is molded into pillar particles having an average length of 2-10 mm and an average major axis of 2-6 mm. Thereby, particles are obtained which has not more than 40% of degree of dispersion, which is defined as a percentage of weight scattered out of a watch glass of 10 cm in diameter against the whole dropped weight when about 10 g of a snow and ice melting agent is dropped at once onto the watch glass whose recessed side is upward and which particles has not more than 40 degree of angle of repose measured by a cylinder rotation method. Preferably the water soluble salt contains 20-90 wt.% of calcium chloride dihydrate and 10-80 wt.% of a salt of an alkaline metal or an alkaline earth metal which salt is less deliquescent and less soluble than calcium chloride dihydrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melting ice and snow, that is, by spraying on ice or snow on roads or the like.
An agent for melting and removing the ice or snow.

[0002]

2. Description of the Related Art Calcium chloride has a high ability to melt ice and snow, and exhibits its performance immediately after being sprayed. Particularly in Japan, since about 1960, it has been sprayed in solid (granular or flake) or aqueous solutions on frozen or snowy roads. Among the above-mentioned spraying methods, spraying solid calcium chloride has a greater ability to melt ice and snow than spraying an aqueous solution.

[0003] However, calcium chloride has an immediate effect, but has a problem that the duration of the effect is short. In other words, after spraying, the melting ice effect disappears in a short time,
Since the thawed water is re-frozen, the treated surface of the road becomes a mirror surface, which may cause a problem that traffic is hindered.

[0004] Also, in the use of granular snow melting agent,
When spraying, it rolls under the influence of strong winds and road slopes,
There is a problem that the drug is unevenly distributed on the road surface. In the case of flake-shaped snow melting agent, in the case of mechanical spraying, especially using a simple sprayer, the formation of a bridge at the outlet of the drug hopper prevents continuous discharge of the drug, which hinders smooth work execution. Problems had occurred. Furthermore, in the wet spraying method in which a ground rock salt and a 30% aqueous solution of calcium chloride are sprayed at the same time, the fixation of the snow-melting agent on solids is high and the effect is immediate, but the persistence of the effect is low.

[0005] Calcium chloride has the effect of corroding metals, particularly carbon steel, and has the drawback of exerting a corrosive effect on metal parts such as automobiles and road signs when sprayed on roads, for example. The most anticipated form of the corrosion inhibitory effect is a method in which a corrosion inhibitor is added and uniformly dispersed during the production of solid calcium chloride, and attempts have been made to suppress corrosion by adding various corrosion inhibitors. . Generally, solid calcium chloride is obtained by boiling down an aqueous calcium chloride solution until it becomes a 170 ° C. melt of calcium chloride dihydrate salt and cooling it. Previous proposals for mixing a corrosion inhibitor before boiling down an aqueous calcium chloride solution have not been put to practical use because the corrosion inhibitor is exposed to a high temperature of 170 ° C.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a medicine spraying method that suppresses rolling due to the influence of wind and inclination of a road surface at the beginning of spraying, improves fixability to ice and snow surfaces, and is not biased to a road surface. It is possible to obtain an ice melting agent.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a compression-molded product of a water-soluble salt, having an average axial length of 2 to 10 m.
m, a melting and snow melting agent comprising columnar particles having an average major axis of a cross section perpendicular to the axis of 2 to 6 mm.

[0008] In the present invention, the term "ice-melting snow agent" means an agent mainly sprayed on an ice surface or a snow surface to dissolve and remove them. Furthermore, the melting agent for snow and ice of the present invention includes a medicine which is sprayed on a road surface in advance for the purpose of preventing freezing.

Since the snow melting agent of the present invention has the above-mentioned shape, it has good fluidity, good handleability, and when sprayed on the ice and snow surface, in addition to the inclination of the road surface and the wind. Rolling is suppressed, and non-biased spraying with less scattering becomes possible. A more preferable range of the average length in the axial direction is 3 to 5 mm. A more preferable range of the average major axis of the cross section perpendicular to the axis is 3 to 5 mm. Here, the average value for the particle size is the average value based on the number of the molded bodies excluding the fine powder.

[0010] The degree of scattering when sprayed on ice and snow
It can be evaluated by the degree of dispersion measured by the following method. The degree of dispersion is as follows: approx. 10 g of ice melting agent is placed on a watch glass of 10 cm in diameter, with the concave surface facing up, at 61 c.
1 m of the weight of the snow-melting agent scattered outside the watch glass with respect to the total weight of the snow-melting agent dropped from the height of m
Defined as 00 fraction. For measurement, powder measuring equipment,
For example, Hosokawa Micron Co., Ltd., trade name Powder Tester P
It is preferable to use a TD type or the like. The smaller the value of the degree of dispersion, the smaller the degree of scattering when sprayed, and the better the fixability.

The degree of fluidity can be evaluated, for example, by the angle of repose by the cylinder rotation method. The smaller the angle of repose, the better the fluidity.

In a conventional melting ice powder, for example, a commercially available granular calcium chloride having a substantially spherical external shape, for example, has a relatively good fluidity with a repose angle of about 30 degrees in a cylindrical rotation method, but a dispersion degree of 45 degrees. % Or more and easily scattered. Also,
Calcium chloride formed into flakes has a dispersity of about 1
Although the degree of scattering was as small as 4%, the angle of repose by the cylinder rotation method was about 45 degrees and the fluidity was low.

The snow melting agent of the present invention has a degree of dispersion of not more than 40% and an angle of repose of not more than 40 degrees by a cylindrical rotation method. That is, it is a melting and snow melting agent having both fluidity and dispersion. More preferably, the degree of dispersion is 30% or less. It is more preferable that the angle of repose is 35 degrees or less.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As the water-soluble salt, various inorganic salts and organic salts can be used as long as they can be dissolved in water to lower the freezing point. Particularly, salts capable of lowering the freezing point by 10 ° C. or more are preferable. Specifically, calcium chloride (−51 ° C.), magnesium chloride (−33.5 ° C.), sodium chloride (−21.1)
° C).

Calcium chloride is particularly preferred because of its high melting and snow effect. As calcium chloride, any of anhydrous salt and hydrate salt can be used without any limitation, but usually, dihydrate salt is preferably used.

In the present invention, calcium chloride and an alkali metal salt or an alkaline earth metal salt are less deliquescent than calcium chloride dihydrate and are more soluble than calcium chloride dihydrate as water-soluble salts. It is preferable to use a mixture composed of a salt having a low melting point (hereinafter, simply referred to as another water-soluble salt) because the melting and snow effect is immediately effective and the melting and snow effect is highly persistent. Representative examples of such other water-soluble inorganic salts include sodium chloride, sodium sulfate, sodium hydrogen sulfate, ammonium chloride, potassium chloride, magnesium sulfate, potassium sulfate, magnesium chloride, potassium nitrate, and the like.

In the snow melting agent of the present invention, specifically, 20 to 90% by weight of calcium chloride dihydrate, and
Among the alkali metal salts or alkaline earth metal salts, those containing 10 to 80% by weight of a salt having a lower deliquescence than calcium chloride dihydrate and a lower solubility than calcium chloride dihydrate are preferable. A more preferable range is 40 to 80% by weight of calcium chloride dihydrate and, among the alkali metal salts or alkaline earth metal salts, deliquescent is lower than calcium chloride dihydrate and is lower than calcium chloride dihydrate. The low solubility salt is 20 to 60% by weight.

When a snow melting agent comprising calcium chloride and a mixture of another water-soluble salt is sprayed on a snow-covered or frozen surface, melting ice and snow is caused by calcium chloride and another mixed water-soluble salt. At this time, first, calcium chloride having great deliquescence and solubility is dissolved to exhibit a melting and snow effect. Since the melting ice and snow water in the early stage of melting ice and snow is a high concentration of calcium chloride, the dissolution of another water-soluble salt is suppressed by the action of solubility equilibrium. It is presumed that another water-soluble salt that has been dissolved starts to dissolve, and exhibits a melting ice effect. Furthermore, by selecting the content of calcium chloride and the type and content of another water-soluble salt for the same reason, the speed of the onset of the melting and snow effect at the initial stage of spraying the medicine can be controlled.

It is preferable that the corrosion inhibitor is uniformly mixed with the snow melting agent of the present invention and then compression-molded, because the problem of metal corrosion caused by the snow melting agent can be reduced. The dissolution of calcium chloride and the water-soluble salt accompanying dispersing promotes the dissolution of the corrosion inhibitor. The corrosion inhibitor used in the present invention may be any known solid corrosion inhibitor soluble in water without any limitation. Examples thereof include carboxylate, tripolyphosphate, amine and triazole. system,
Examples include polyphenol-based and silicate-based corrosion inhibitors. Powder is preferred. The mixing ratio of the corrosion inhibitor is preferably from 0.3 to 3% by weight of the melting ice and snow agent.

When a plurality of materials are used as raw materials, it is preferable to mix them before putting them into a compression molding apparatus. Mixing methods include kneaders, shakers, double cone mixers, V mixers, ball mixers, I mixers, ribbon mixers, pot mixers, super mixers, universal mixers, cutter mixers, kneaders, It can be carried out using a generally known apparatus such as a ball mill and a pot mill without any limitation.

FIG. 1 shows an example of a compression molding apparatus for producing the snow melting agent of the present invention. In FIG. 1, a raw material powder 2 supplied to a hopper 1 is compression-molded by rolls 3 and 3 '. Here, in the rolls 3 and 3 ', a groove having a semicircular cross section is dug around the circumference, and many of these grooves are continuous in the direction of the axis of the roll. For this reason, the compression molded body 4 in which the columns are connected in a string form is obtained from the raw material powder.

In the apparatus shown in FIG. 1, the compression molded body 4 is
Next, it is supplied to the cutting rolls 5, 5 '. Cutting roll 5
Is a gear-shaped roll having convex portions having sharp ends at regular intervals, and the cutting roll 5 ′ is a flat roll having substantially the same outer diameter as the cutting roll 5. This cutting roll 5,
By making the gap 5 ′ slightly smaller than the maximum thickness of the compression-molded body 4, the compression-molded body 4 is cut into a length corresponding to the interval between the projections of the cutting roll 5, and the connection of the string-like body is performed. The portion is also broken to obtain columnar particles 6. In addition, in FIG. 1, 7 is a guide of the compression molded body 4.

When a compression roll having a groove having a semicircular cross section as shown in FIG. 1 is used, a cylindrical ice-melting agent can be obtained as described above. The compression molded body obtained in this case is cylindrical, the columnar surface is a surface formed in contact with the surface of the compression roll, and the bottom surface is a fractured surface formed by the cutting roll. When the cross section of the groove of the compression roll is semicircular, it is preferable because a stable and uniform compression molded product can be obtained, but the cross section of the groove is not particularly limited, and a triangular shape, a rectangular shape, or the like can be adopted.

The compression-molded body thus obtained can be used as it is, but when sizing is further performed, a snow-melting agent with less pulverization during transportation and storage is preferably obtained. The sizing can be performed using an ordinary spheroid machine. The spherical machine referred to here is generally used for the purpose of forming a cylindrical pellet into a sphere, but in the present invention, in order to prevent powdering and provide an easy-to-handle snow melting agent, a compression molded body is used. It is used for a similar purpose of removing adhering burrs, but is processed, for example, by shortening the processing time so that the shape of the compression molded body does not substantially change.

Further, it is preferable to carry out sieving from the sized product.

[0026]

EXAMPLES Example 1 Powdered calcium chloride dihydrate was
After compression molding using the apparatus shown in FIG. 1, the particles were sized, and then sieved to obtain a snow melting agent comprising compression-molded particles of calcium chloride dihydrate. The shape of this snow melting agent is
It was cylindrical with a diameter of 3 mm and a length of 3 mm.

The angle of repose of this snow melting agent was measured by a cylinder rotation method. The cylindrical rotation method is an inclination angle at which a cylindrical container having an inner diameter of 7.5 cm containing a granular material is slowly rotated to form a stable inclined surface. The relative evaluation was made by measuring the degree of dispersion and comparing the degree of ease of rolling. The degree of dispersion was measured using a powder measuring instrument (Powder Tester PT-D type, manufactured by Hosokawa Micron Corporation). The angle of repose was 35 degrees and the degree of dispersion was 28%.

Next, the duration of the melting ice effect was measured by the following method. Add the above ice-melting agent (10 g) to a diameter of 1
The dispersion was spread on 200 g of an ice plate in a 0 cm plastic container, kept in a low-temperature incubator set at −10 ° C., taken out after various times shown in Table 1, and the melting weight of the ice plate was measured. The measurement was repeated three times under the same conditions, and the average value was adopted as data. Table 1 shows the average value (unit: g) of the melting weight of ice. In the case of the snow melting agent of Example 1, no increase in the melting amount was observed even when the elapsed time exceeded 150 minutes. The time until the amount of melting of the ice floe does not substantially increase is hereinafter referred to as the duration of the melting ice effect. That is, the duration of the melting ice snow effect of the melting agent of Example 1 was 150 minutes. This evaluation method is described in Example 2 below.
The same applies to ７7.

Example 2 100 parts by weight of calcium chloride dihydrate and 100 parts by weight of sodium chloride were uniformly mixed by a mixer, and a snow melting agent was obtained in the same manner as in Example 1.

With respect to this snow melting agent, the snow melting effect was measured in the same manner as in Example 1. Table 1 shows the relationship between the elapsed time and the amount of melting.
Shown in The duration of the melting ice effect was 360 minutes.

[Example 3] 100 parts by weight of calcium chloride dihydrate, 80 parts by weight of sodium chloride and sodium sulfate 2
0 parts by weight were uniformly mixed with a mixer, and a melting ice powder was obtained in the same manner as in Example 1.

With respect to this snow melting agent, the melting effect was measured in the same manner as in Example 1. Table 1 shows the relationship between the elapsed time and the amount of melting.
Shown in The duration of the melting ice effect was 360 minutes.

[Example 4] 100 parts by weight of calcium chloride dihydrate, 34 parts by weight of sodium chloride and 8.6 parts by weight of sodium sulfate were uniformly mixed by a mixer, and a snow melting agent was obtained in the same manner as in Example 1. Was.

With respect to the snow melting agent, the melting effect was measured in the same manner as in Example 1. Table 1 shows the relationship between the elapsed time and the amount of melting.
Shown in The duration of the melting ice effect was 360 minutes.

Example 5 100 parts by weight of calcium chloride dihydrate, 100 parts by weight of sodium chloride, and 2 parts by weight of a corrosion inhibitor composed of a carboxylate and a chelating agent (trade name: Lescol, manufactured by Nitto Chemical Industry Co., Ltd.) Mix evenly with a mixer,
In the same manner as in Example 1, a snow melting agent was obtained.

With respect to this snow melting agent, the snow melting effect was measured in the same manner as in Example 1. Table 1 shows the relationship between the elapsed time and the amount of melting.
Shown in The duration of the melting ice effect was 360 minutes.

Example 6 (Comparative Example) A substantially spherical granular calcium chloride dihydrate having an average particle size of about 3 mm was used as a melting / ice melting agent.
The duration of the melting ice effect was evaluated by the above method. As a result, the duration of the melting ice effect was 150 minutes.

The angle of repose measured in the same manner as in Example 1 was 30 degrees and the degree of dispersion was 56%. That is, it was found that the fluidity was better than that of the snow melting agent of Example 1, but it was easily scattered.

Example 7 (Comparative Example) Average particle size: about 0.14 m
m of powdered sodium chloride was used as a melting agent for snow and ice, and the duration of the melting and snow effect was evaluated by the above method. As a result, the duration of the melting ice effect was 160 minutes. However, a phenomenon was observed in which water melted in the early stage of use (between 30 minutes and 90 minutes) was partially frozen again.

Example 8 (Comparative Example) Using the same powdered calcium chloride dihydrate salt as used in Example 1, compression granulation was carried out using a roller compactor having a 4.5 mm pocket forming roll. The formed sheet was crushed and sieved to obtain a melting agent for calcium chloride dihydrate salt. The angle of repose was 35 ° and the degree of dispersion was 47%. That is, although the fluidity was almost the same as that of the snow melting agent of Example 1, the degree of dispersion showed a large value, and it was found that it was easy to be scattered.

[0041]

[Table 1]

[0042]

The snow melting agent of the present invention can be used in the same manner as a conventional solid snow melting agent, and exhibits an excellent snow melting effect. Rolling due to the influence of the wind at the beginning of spraying or the inclination of the road surface is suppressed, the fixability to the road surface is improved, and the medicine can be sprayed without bias to the road surface.

In addition to the above, calcium chloride and an alkali metal salt or an alkaline earth metal salt, calcium chloride 2
When compression-molded from a mixture with a salt having a lower deliquescence than water salt and a lower solubility than calcium chloride dihydrate, it has an immediate effect and maintains the snow-ice melting effect for a long time. be able to. Further, when a corrosion inhibitor is added, the effect of suppressing corrosion of metal for a long time is also exhibited.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an apparatus for producing a snow melting agent according to the present invention.

[Explanation of symbols]

 1: hopper 2: raw material powder 2, 3, 3 ': compression roll 4: compression molded body 5, 5': cutting roll 6: particle 7: guide

Claims (5)

[Claims] 1. A compression-molded product of a water-soluble salt, comprising a columnar particle having an average length in the axial direction of 2 to 10 mm and a cross section perpendicular to the axis having an average length of 2 to 6 mm. . 2. About 10 g of the snow melting agent is dropped at a stroke from a height of 61 cm onto a watch glass having a diameter of 10 cm provided with the concave surface facing upward, based on the total weight of the dropped snow melting agent. 100 of the weight of the snow melting agent scattered outside the watch glass
2. The ice melting agent according to claim 1, wherein a dispersion rate defined as a fraction is 40% or less, and a repose angle by a cylindrical rotation method is 40 degrees or less. 3. The snow melting agent according to claim 1, wherein the water-soluble salt is calcium chloride. 4. A method according to claim 1, wherein the water-soluble salt is calcium chloride dihydrate 20 to 20.
90% by weight, and 10 to 80% by weight of an alkali metal salt or an alkaline earth metal salt having a lower deliquescent than calcium chloride dihydrate and a lower solubility than calcium chloride dihydrate. The snow melting agent according to claim 3, which is contained. 5. The snow melting agent according to claim 1, further comprising a corrosion inhibitor.